Energy from the Biomass: Third EC conference

ENERGY FROM BIOMASS 3rd E. C. Conference Proceedings of the International Conference on Biomass held in Venice, Italy, 25–29 March 1985

ENERGY FROM BIOMASS 3rd E. C. Conference Edited by

W.PALZ Commission of the European Communities, Brussels, Belgium J.COOMBS Bio-Services, London, UK and D.O.HALL King’s College, University of London, UK

ELSEVIER APPLIED SCIENCE PUBLISHERS LONDON and NEW YORK

This edition published in the Taylor & Francis e-Library, 2006. “To purchase your own copy of this or any of Taylor & Francis or Routledge’s collection of thousands of eBooks please go to http://www.ebookstore.tandf.co.uk/.” ELSEVIER APPLIED SCIENCE PUBLISHERS LTD Crown House, Linton Road, Barking, Essex IG11 8JU, England Sole Distributor in the USA and Canada ELSEVIER SCIENCE PUBLISHING CO., INC. 52 Vanderbilt Avenue, New York, NY 10017, USA British Library Cataloguing in Publication Data International Conference on Biomass (1985: Venice) Energy from biomass: 3rd E. C. Conference. 1. Biomass energy I. Title II. Palz, W. III. Coombs, J. IV. Hall, D.O. 662′.6 TP360 Library of Congress Cataloging-in-Publication Data International Conference on Biomass (3rd: 1985: Venice, Italy) Energy from biomass. “Proceedings of The International Conference on Biomass held in Venice, Italy, 25–29 March 1985”—P. Organization of the conference by Commission of the European Communities, Directorate-General Science, Research and Development, and others. English, French and German. Bibliography: p. Includes indexes. 1. Biomass energy—Congresses. I. Palz, W. (Wolfgang), 1937- II. Coombs, J. III. Hall, D.O. (David Oakley) IV. Commission of the European Communities. Directorate-General Science, Research and Development. V.Title. TP360.I56 1985 333.79 85–16096 ISBN 0-203-97803-X Master e-book ISBN

ISBN 0-85334-396-9 (Print Edition) WITH 293 TABLES AND 471 ILLUSTRATIONS © ECSC, EEC, EAEC, Brussels and Luxembourg, 1985 Organization of the conference by: Commission of the European Communities, Directorate General Science, Research and Development, Brussels, in co-operation with Unesco, Ministero per la Ricerca Scientifica, Regione Veneto, Commune di Venezia, ENEA, Camera di Commercio, Azienda Regionale delle Foreste Emilia Romagna Published for the Commission of the European Communities, Directorate-General Information Market and Innovation, Luxembourg EUR 10024 LEGAL NOTICE Neither the Commission of the European Communities nor any person acting on behalf of the Commission is responsible for the use which might be made of the following information. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher.

PREFACE The success of the previous Conferences on Energy from Biomass, held in Brighton 1980 and Berlin 1982, and the continued interest among European countries, encouraged the Commission of the European Communities to organise the third conference on this area of energy production. It brought together about 500 experts from many countries thus presenting an international forum for discussion of the most recent advances in research and development, manufacture and industrial applications. In the development of energy production from indigenous resources the importance of biomass is steadily increasing. This is now notable in temperate regions where it is associated with aspects of conservation, waste treatment and materials recycling as well as the use of crops, trees and residues from agriculture and forestry. Large government and industrial sponsored programmes in many countries of the world give ample evidence of this fact. This is particularly relevant at present in Europe where the problem of agricultural surpluses in the European Community is being discussed in terms of ethanol and short rotation forestry schemes. The conference was organised on the basis of a number of common themes representing the resources upon which biomass energy in Europe is based. These are the sun, trees, wastes, agriculture, aquaculture and natural communities. These common themes were explored from a different viewpoint during each day of the conference. The opening sessions were used to introduce the Energy from Biomass programme of the European Communities, followed by presentation of some of the key areas in terms of problems, resources and technical progress which are influencing the rate at which biomass energy systems are being adopted within Europe. On the third day the technical sessions were concerned with biomass production and handling, and on the fourth day with conversion of biomass to fuel. The last day was devoted to implementation and analysis of the current status of biomass schemes within Europe as well as systems around the world. As an integral part of the programme there were very well presented Poster sessions (over 200 papers) and Round Table discussions on topical themes such as resources, land use for food or fuel, and environmental impacts; also Workshops where specific technical aspects were discussed in depth were successfully inaugurated. The participation of technical, industrial and scientific people along with politicians and planners made for a lively meeting. Biomass for energy is maturing fast as an established component of the energy scene. These Conferences play a very useful role in enabling people of such diverse interests to interact to great advantage Professor D.O.Hall Dr W.Palz Conference Chairmen.

Chairmen PALZ W

CEC Belgium

HALL D O

UK

Conference Secretariat COOMBS J

UK

GRASSI G

CEC Belgium

General Organization MAGNABOSCO G

Belgium

Local Organization BONALBERTI F

Italy

Publications NICOLAY D

CEC Luxembourg

Members ALFANI F

Italy

BALDELLI C

Italy

BANKS P

Zimbabwe

BENEVOLO G

Italy

BERESOVSKI T

Unesco France

BERNINI C

Italy

BURLEY J

UK

CESCON P

Italy

CHARTIER P

France

CROATTO U

Italy

de MONTALEMBERT M

FAO Italy

DOSIK A

World Bank USA

FARINELLI H

Italy

FERRERO G L

CEC Belgium

FITTIPALDI V

Italy

FOSTER K

USA

HAKKILA P

Finland

HAVE H

Denmark

KINSELLA E

Ireland

LEQUEUX P

CEC Belgium

LIPINSKY E S

USA

LJUNGBLOM I

Sweden

MARGARIS N

Greece

MEINHOLD K

Germany

MIYACHI S

Japan

MOLLE J F

France

MONACO L

Brazil

MORSELLI G

Italy

NAVEAU H

Belgium

OVEREND R

Canada

PERNKOPF J

Austria

PIAVAUX M

CEC Belgium

PRICE R

UK

PSYLLAKIS D

Crete

RABSON R

USA

REDDY A

India

REED T

US

RIEDACKER A

France

SAVOIA G

Italy

SIREN G

Sweden

STEWART G A

Australia

STREHLER A

Germany

STRUB A

CEC Belgium

TAGANAS T

Philippines

TANTICHAROEN M

Thailand

TIWARI T

India

van SWAAIJ W

Netherlands

van UDEN N

Portugal

VALERI MANERA M

Italy

VELLUTI S

Italy

VILLET R

France

WEISSIMANN A

Germany

WELLINGER A

Switzerland

WU WEN

China

VIANELLO V

Italy

CONTENTS Preface

iv

OPENING SESSION The energy from biomass programme of the Commission of the European Communities A S STRUB La biomasse dans la competition energetique: A GIRAUD Biomass fuels in a European context: R M SELIGMAN The Italian biomass scene: G AMMASSARI Avenir de l’agriculture europeenne et valorisation de la biomasse: L PERRIN The common agricultural policy and biomass energy: J J SCULLY Kurzfristige verfugbarkeit von forstlicher biomasse in der Bundesrepublik Deutschland: A F WEISMANN La biomasse, source de substituts au pétrole dans le secteur des transports: P LEPRINCE and J P ARLIE

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SESSION I: THE EUROPEAN SCENE Trees and wood as an energy source in the Nordic countries: G WILHELMSEN Biomass availability and use in the industrial regions A STREHLER Ressources en biomasses utilisables a des fins energetiques en milieu agricole—cas de l’europe des 10 C GOSSE Biomass for heating and fuels in Austria: a case study for Europe? A F J WOHLMEYER

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A F J WOHLMEYER SESSION II: TECHNICAL SESSIONS Zur agrarpolitischen bedeutung der ethanolproduktion in der Bundesrepublik Deutschland: K MEINHOLD and H KOGL The use of forests as a source of biomass energy: F C HUMMELL The availability of wastes and residues as a source of energy: G PELLIZZI The potential of natural vegetation as a source of biomass energy: T V CALLAGHAN, G J LAWSON and R SCOTT Photobiology—the scientific basis of biological energy conversion: M C W EVANS The biomass to synthesis gas pilot plant programme of the CEC; a first evaluaton of its results: A A C M BEENACKERS and W P M VAN SWAAIJ Biomethanation, the paradox of a mature technology: E-J NYNS, M DEMUYNCK and H NAVEAU Novel methods and new feedstocks for alcohol from biomass: U RINGBLOM Use of algal systems as a source of fuel and chemicals: E BONALBERTI and U CROATTO

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SESSION III: IMPLEMENTATION L E B E N—Large European bioenergy project: G GRASSI, U MIRANDA, C BALDELLI and F GHERI The production and use of fuel alcohol in Zimbabwe C M WENMAN Canada’s energy from the forest programme: R P OVEREND Integrated food-energy production systems: E L LA ROVERE The use of wastes as a source of energy in the UK: R PRICE The Southern US biomass energy programs with emphasis on Florida: W H SMITH Biomass energy utilisaton and its technologies in China rural areas: W WU Summaries of ROUND TABLES

182

Summaries of WORKSHOPS

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189 194 217 224 233 240 248

CONTRIBUTED PAPERS

279

Biomass from short rotation coppice willow in Northern Ireland: G H McELROY and W M DAWSON Biomass gains in coppicing trees for energy crops: W A GEYER, G G NAUGHTON and M W MELICHER Short rotation coppice forest biomass production—the work of the IUFRO S1.05–10 working party: D AUCLAIR Short rotation forestry for energy production: M NEENAN Une plante energetique a cycle courte: le genet Cytisus scoparius: P TABARD Energy and biomass of piedmont hardwoods: M A MEGALOS, L HORTON, D J FREDERICK, A CLARK and D R PHILLIPS Coppiced trees as energy crops: M L PEARCE FAO’s activities on industrial wood-based energy: M A TROSSERO Energy forestry research in Britain: C P MITCHELL Forest biomass: INRA’s programme: E TESSIER-DU-CROS Euphorbia project: renewable energy production through the cultivation and processing of semi-arid land biomass in Kenya: M DECLERCK, Ph SMETS, J SMETS and J ROMAN Potentialites de production d’un couvert vegetal: M CHARTIER, J M ALLIRAND and G GOSSE Productivite de roseau phragmites: J M ALLIRAND, M CHARTIER and G GOSSE

281 286 291

295 300 306 311 314 318 323 331

337 344

Comparative biomass yields of energy crops: W H SMITH and J R FRANK Onopordum nervosum Boiss as a potential energy crop: J FERNANDEZ, P MANZANARES and J MANERO Straw as a biomass resource and its acquisition in the United Kingdom: J M CLEGG, S B C LARKIN, D H NOBLE and R W RADLEY Studies about the potential of sweet sorghum and Jerusalem artichoke for ethanol production based on fermentable sugar: G KAHNT and L LEIBLE The potential for straw as a fuel in the UK: L P MARTINDALE Immediately available liquid fuel crops in the EEC: H STURMER, H THOMA and E ORTMAIER Energetic outlets of agriculture in the EEC: J J BECKER The development of wetland energy crops in Minnesota, USA—managing stands for continued productivity: D R DUBBE, E G GARVER and D C PRATT Energy from agriculture—some results of Swedish energy cropping experiments: U WUNSCHE Epuration des eaux et produits de haute valeur tires de la jacinthe d’eau: F SAUZE An integrated system: mass algae culture in polluted luke-warm water for production of methane, high value products and animal feed A LEGROS, H NAVEAU, E-J NYNS, E DUJARDIN, F COLLARD and C SIRONVAL Properties of algal biomass production and the parameters determining its fermentative degradation K KREUZBERG, G REZNICZEK and G KLOCK Potentialites de production de biomasse aquatique dans les lagunes d’epuration M VUILLOT and J BARBE Production of algal biomass in Venice lagoon: environmental and energetic aspects G MISSONI and M MAZZAGARDI Hydrogen production, ammonia production and nitrogen fixation by free and immobilised cyanobacteria M BROUERS and D O HALL Effect of different factors on the productivity of nitrogen fixing blue-green alga Anabaena variabilis under outdoor conditions A G FONTES, J MORENO, M A VARGAS, M G GUERRERO and M LOSADA

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An energy budget for algal culture on animal slurry in temperate climatic conditions H J FALLOWFIELD and M K GARRETT Photosynthetic basis of biomass production by water hyacinth grown under high CO2 level A LARIGAUDERIE, J ROY and A BERGER Eichhornia crassipes: production in repeated harvest systems on waste water in the Languedoc Region (France) M-L CHASSANY DE CASABIANCA The effect of nutrient application on plant and soil nutrient content in relation to biomass harvesting T V CALLAGHAN, G J LAWSON, A M MAINWARING and R SCOTT uptake through the roots in willow and sunflower and effect of uptake of willow cuttings P PELKONEN, E M VAPAAVUORI and H VUORINEN Controlled environment growth of Euphorbia lathyris in relation with temperature and water stress P T VENTAS, J L TENORIO, E FUNES and L AYERBE Micropropagation of willows (Salix spp) T TORMALA and E SAARIKKO The use of photointerpretation for biomass evaluation and possible biomass recovery in an area of the Lombardy region P BONFANTI and C SEMENZA Photosynthetic solar energy capturing in a cropping system with extensive exploitation of biomass for fuel production J ZUBR Micropropagation of some forest tree species G SAVOIA and S BIONDI Anaerobic digestion in the food processing industry: a feasibility study D J COX and D R NUTTALL Purification of biogas K EGGER, K SUTTER and A WELLINGER Contribution to comprehensive engineering conception of methanisation based on kinetic approach R BACHER, F YEBOUA AKA, M EL-HOUSSEINI and G GOMA Performance of anaerobic expanded bed reactors treating municipal sewage P GARCIA, L J REDONDO, I SANZ and F FDZ-POLANCO Anaerobic stabilisation of agricultural and foodbased industrial wastes J WINTER and F X WILDENAUER Anaerobic digestion and methane production of slaughterhouse wastes A STEINER, F X WILDENAUER and O KANDLER Fermentation mèthanique en discontinu des fumiers a la ferme: simulation du fonctionnement d’une installation en situation rèelle P A JAYET

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The production of methane from biomass in the United States: economics, tradeoffs and prospects J R FRANK, T D HAYES and W H SMITH Anaerobic digestion of pig manure: results on farm scale and new process C AUBART and F BULLY An economic approach to biogas generation and use D J PICKEN Methane from biological anaerobic treatment of industrial organic wastes R CAMPAGNA, G DEL MEDICO and M PIERONI Experiences with anaerobic digestion of various cassava residues in Indonesia R WURSTER Biogas technology developed and evaluated by ENADIMSA A J GARCIA, S CUADROS and R FERNANDEZ Influence of hydrogen addition on the potential of methanogenic ecosystems R MOLETTA, J D FINK, G GOMA and G ALBAGNAC Butyrate production and volatile fatty acids interconversion during propionate degradation by anaerobic sludges R MOLETTA, H C DUBOURGUIER and G ALBAGNAC Large scale anaerobic digestion of animal wastes in The Netherlands F M L J OORTHUYS and H J W POSTMA The Anoxal process: anaerobic treatment of liquid industrial effluents J CUTAYAR and M MOULINEY Biogas production from solid pineapple cannery waste at elevated temperature M TANTICHARONE, S BHUMIRATANA T UTITHAM and N SUPAJUNYA Adhesion of anaerobic bacteria from methanogenic sludge onto inert solid surfaces D VERRIER and G ALBAGNAC Granular methanogenic sludge: microbial and structural analysis H C DUBOURGUIER, G PRENSIER, E SAMAIN and G ALBAGNAC Full-scale methanizatin of sugary waste waters in a downflow anaerobic filter D VERRIER, J P LESCURE, B DELANNOY and G ALBAGNAC Methane fermentation of distillery waste water of sugar cane alcohol on a fixed biomass pilot A BORIES, F BAZILE, J RAYNAL and E MICHELOT Fixed biomass on lignocellulose media for the methane fermentation of industrial waste water A BORIES, M DUVIGNAU and N CATHALA Two-phase digestion of distillery slops using a fixed bed reactor for biomethanation K WULFERT and P WEILAND

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537 541 544 550 556 561 569

576 581 586

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Biogas from green and silaged plants in a digester with internal liquid circuit W BAADER Anaerobic digestion of organic fraction of municipal solid waste— preliminary communication P CESCON, F CECCHI, F AVEZZU and P G TRAVERSO Improved technologies in biogas production from algae of the Venice lagoon and waste treatment U CROATTO Applicaton of gas from biomass: conditioning of gas or adaptation of gas fired equipment F A J RIETVELD Pilot plant biomethanation of cultivated marine algae Tetraselmis for energy production in southern Italy A LEGROS, M R TREDICI, G FLORENZANO, R MATERASSI, E-J NYNS and H NAVEAU Joint Belgium-Burundi biomethanation development project: main results after two years activity D COMPAGNION, D ROLOT, E-J NYNS, H P NAVEAU, V BARATAKANWA, D NDITABIRIYE, J NDAYISHIMIYE and P NIYIMBONA Industrial results of SGN fixed film anaerobic fermentation process M ARNOUX, J Y MOREL, G COMINETTA and C OGGIONNI The bio-gas projects in Emilia-Romagna (Italy): first results of five full scale plants L CORTELLINI, S PICCININI and A TILCHE Methane production from green and ensiled crops technological and microbial parameters E ZAUNER and U KÜNTZEL Feasibility and efficiency of thermophilic methane fermentation with pig manure and potato stillage as substrates U TEMPER, J WINTER, F WILDENAUER and O KANDLER Anaerobic digestion of macroalgae of the Lagoon of Venice: experiences with a 5 mc capacity pilot reactor S NICOLINI and A VIGLIA Bioenergy from tannery biomass: experimental work on anaerobic digestion from laboratory to real plant scale M BREGOLI, D FERRARI and A VIGLIA Utilisation of activated carbon and carbon molecular sieves in biogas purification and methane recovery E RICHTER, K-D HENNING, K KNOBLAUCH and H JUNTGEN Membrane Cleaning of Biogas for injection to pipelines F DE POLI, M MENDIA and N MIGLIACCIO Biomass and coenzyme F420 distribution in anaerobic filters N O’KELLY, P J REYNOLDS, A WILKIE and E COLLERAN

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Kinetics of landfill leachate treatment by anaerobic digestion J M LEMA and E IBANEZ Biogas research in Austria J SPITZER, P SCHUTZ and W HIMMEL Mathematical model of a real scale digester R CHIUMENTI, A DE ANGELIS, F DE POLI and A TILCHE Anaerobic treatment of high load industrial waste water by means of a freecells fermentation process O ZUFFI, N MILANDE and B RAYMOND Cloning and analysis of genes involved in cellulose degradation by Clostridium thermocellum P BEGUIN, D PETRE, J MILLET, H GIRARD, R LONGIN, O RAYNAUD, M ROCANCOURT, O GREPINET and J-P AUBERT Nuclear magnetic resonance application in studying the biological production of ethanol from sugarcontaining media E TIEZZI, A LEPRI and S ULGIATI Basic trials to co-immobilize algae and yeast for the production of ethanol I MUCKE and W HARTMEIER Ethanol from unconventional substrates using yeast co-immobilized with non-yeast glycosidases W HARTMEIER, U FORSTER and C GIANI Ethanol from pentoses and pentosans by thermophilic and mesophilic microorganisms J WIEGEL and J PULS Rapid determination of yeast concentration in fermentation broths H NEIBELSCHUTZ and C BOELCKE Utilisation of bamboo for the production of ethanol J B DE MENEZES, C L M DOS SANTOS and A AZZINI Continuous conversion of lactose to ethanol using Zymomonas mobilis and immobilized B-galactosidase S TRAMM-WERNER and W HARTMEIER New continuous process for production of ethanol using immobilized cells reactor L LEULLIETTE, M HENRY and D GROS Acetone butanol fermentation of hydrolysates obtained by enzymatic hydrolysis of agricultural lignocellulosic residues R MARCHAL, M REBELLER, F FAYOLLE, J POURQUIE and J P VANDEĆASTEELE 692 Acid hydrolysis for the conversion of cellulosic biomass to ethanol J PAPADOPOULOS NMR analysis of fermentation products by Clostridium acetobutylicum C ROSSI, P VALENTI, N MARCHETTINI and N ORSI

710 715 721 724

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Enzymatic hydrolysis and SCP production from solvent delignified Eucalyptus globus L. biomass M T A COLACO and H PEREIRA Enhanced butanol-tolerance in mutants of Clostridium acetobutylicum P VALENTI, P VISCA and N ORSI Influence de la nutrition azotee sur la croissance et la production d’hydrocarbures d l’algae unicellulaire Botryococcus braunii F BRENCKMANN, C LARGEAU, E CASADEVALL and C BERKALOFF Influence of light intensity on hydrocarbon and total biomass production of Botryococcus braunii—relationships with photosynthetic characteristics F BRENCKMANN, C LARGEAU, E CASADEVALL, B CORRE, and C BERKALOFF Screening of wild strains of the hydrocarbon-rich alga Botryococcus braunii—productivity and hydrocarbon nature P METZGER, E CASADEVALL, A COUTE and Y POUET Chromatographic studies of crude oils from wood D MEIER, R DORING and O FAIX Methyl esters of tallow as a diesel component D W RICHARDSON, R J JOYCE, T A LISTER and D F S NATUSCH Production of hydrocarbons from biomass W HELD, M PETERS, C BUHS, H H OELERT, G REIFENSTAHL and F WAGNER Renewable hydrocarbons and industrial chemicals from Kenyan plants A NG’ENY-MENGECH and S N KIHUMBA Corn drying, cereal straw combustion, harvest and energetic valorization of corn cobs X GAUTIER Woodstoves in the Netherlands, environmental and social impacts P A OKKEN Fluidised bed combustion of both light and wet biomass B WILTON and J F WASHBOURNE Development of a domestic firewood burner for cooking S G MUKHERJEE Joint enterprise and utilization of a briquetting plant for straw M BRENNDORFER Pelletization of straw C WILEN, K SIPILA, P STAHLBERG and J AHOKAS Charcoal as fuel: new technological approaches J F GOUPILLON Results from research work in heat generation from wood and straw A STREHLER Basics of the combustion of wood and straw M HELLWIG

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852 859 862 867 873 879 884 891

Test results from pilot plants for firing wood and straw in the Federal Republic of Germany U KRAUS Biomass-fueled furnace coupled to greenhouse heating and crop drying systems R M SACHS, D ROBERTS, K M SACHS, B JENKINS, G FORISTER, J EBELING and D FUJINO Quality of densified biomass products J CARRE, J HERBERT, L LACROSSE and P LEQUEUX On the testing of woodburning cookstoves P BUSSMANN, K K PRASAD and F SULILATU Air pollution from biomass heated boilers compared with that from waste incineration and oil combustion C BENESTAD, M MOLLER, A OSVIK, T RAMDAHL and G TVETEN Kinetic of wood tar pyrolysis P MAGNE, A DONNOT and X DEGLISE An intermediate capital intensive pyrolysis system applicable to developing countries J W TATOM and K B BOTA Gasification of agricultural residues in a downdraft gasifier L LIINANKI, P-J SVENNINGSSON and G THESSEN Some kinetic aspects on the pyrolysis of biomass and biomass components C KOUFOPANOS, G MASCHIO, M PACI and A LUCCHESI Wood pyrolysis: a model including thermal effect of the reaction R CAPART, L FAGBEMI and M GELUS Platform tests of biomass combustion and gasification equipment M REYNIEIX Batch carbonisation of coconut shell and wood with the recovery of waste heat G R BREAG, A P HARKER and A E SMITH Fast pyrolysis of cellulose R G GRAHAM, B A FREEL, M A BERGOUGNOU, R P OVEREND and L K MOK Contribution to the exploitation of recovered wood through the development of carbonisation and activation processes G SAVOIA, G BARBIROLI, A GATTA, R OSTAN and G PASQUALI Results of tests with different gasifiers for farm use L BODRIA, M FIALA and G SALVI Environmental aspects of biomass gasification P S LAMMERS Modern equipment for the generation of producer gas out of block wood and granular wood waste K W JASTER

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Gasification of biomasses by HTW-gasification process H TEGGERS, H J SCHARF and L SCHRADER Syngas production from wood by oxygen gasification under pressure G CHRYSOSTOME and J M LEMASLE Thermal degradation of firwood and firbark influence of size and gaseous atmospheres J R RICHARD and C VOVELLE Gasification of rice husk in a small downdraft moving bed R MANURUNG and A A C M BEENACKERS Fuel- and synthesis gas from biomass via gasification in the circulating fluid bed P MEHRLING and R REIMERT Methane from biomass-process optimisation A V BRIDGWATER and D H SMITH Sensitivity of theoretical gasifier performance to system parameters J M DOUBLE and A V BRIDGWATER Wood liquefaction: total mass and energy balances X DEGLISE, D MASSON, H KAFROUNI and A LADOUSSE Study of the direct liquefaction of wood in the presence of iron additives C BESTUE-LABAZUY, N SOYER, C BRUNEAU and A BRAULT Direct thermochemical liquefaction of plant biomass using hydrogenating conditions D MEIER, D R LARIMER and O FAIX Le prétraitment, l’hydrolyse, la pyrolyse et la liquefaction de la biomasse: vers une approche unifiee R P OVEREND and E CHORNET A techno-economic comparison of biomass thermochemical liquefaction processes Y SOLANTAUSTA and P J MCKEOUGH What future for the thermochemical liquefaction of biomass? C ESNOUF Improvement of the ethylene glycol water systems for the component separation of lignocelluloses D GAST and J PULS Hydrothermolysis of short rotation forestry plants G BONN, W SCHWALD, O BOBLETER and V I BENEA Synthesis of several alcohols from biomass gases with zeolite catalysts J C GOUDEAU, A BENGUEDACH and L JULIEN Investigations on methanol catalytic synthesis from biomass gases: optimization of the process on a new catalyst A BOURREAU, J C GOUDEAU, L JULIEN, A NEMICHE and F SOUIL The solid-liquid transfer process in a slightly hydrated heterogeneous medium: a way to synthesise organic chemicals from biomass M E BORREDON, L RIGAL, M DELMAS and A GASET

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Bioconversion of organosolv lignins by different types of fungi A HAARS, A MAJCHERCZYK, J TROJANOWSKI and A HÜTTERMANN The fractionation of lignocellulosic substrates by steam explosion and the subsequent conversion of the various components to sugars, fuels and chemicals J N SADDLER, E K C YU, M MES-HARTREE, N LEVITIN and H H BROWNELL Chemicals from sugar industry waste products M G KEKRE and A TAHA New process for the fabrication of ethyl esters from crude vegetable oils and hydrated ethyl alcohol R STERN, G HILLIOIN, P GATEAU and J C GUIBET Biodegradation of native cellulose F ALFANI, L CANTERELLA, A GALLIFUOCO, L PEZZULLO and M CANTARELLA Study of enzymatic hydrolysis of alkali pretreated Onopordum nervosum C MARTIN, M J NEGRO, M ALFONSEL, F SAEZ, R SAEZ and J FERNANDEZ The role of microorganisms isolated from funguscomb-constructing African termites in the degradation of lignocellulose H ORSORE III. IMPLEMENTATION

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A biomass project (gasification and pyrolysis) for Lower Austria G SCHÖRNER New domestic renewable energy through high tehnology of biogases O KUUSINEN Prospective methodology adapted to global biomass project choices and integration (modelisation of a biomass valorization process) P MATARASSO and J P TABET An economic analysis of the energy valorisation of cereal straw in France V REQUILLART Integration and assessment of biomass research information by use of system analysis J W MISHOE Conversion of lignocellulosic material to ethanol influence of raw material yield and hemicellulose utilization on sales price of ethanol J FELBER, M SCHIEFERSTEINER and H STEINMULLER Bioenergy in regional energy systems—a case study from Hadeland in Norway A LUNNAN Possibilities of relieving the EC agricultural market through energy production for example rape and short-rotation forestry R APFELBECK

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1167

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The economics of thermochemical routes from wood to liquids L A MICHAELIS Chemical investigations in the Swedish agrobioenergy project O THEANDER Energetic optimization of biomass in the farming systems of marginalised areas—labour and capital restrictions—economic analysis J P CHASSANY Biomass as an energy source in the French context, promises and constraints J C SOURIE Fuel ethanol in Brazil and the implications for control of lead additives in the EEC countries F ROSILLO-CALLE Residue briquetting in developing countries S JOSEPH and D HISLOP An economic process for the production of a diesel fuel substitute from edible oil fractions H P KREULEN, H C A VAN BEEK, E VAN DER DRIFT and G SPRUIJT Thermochemical processing of lignocellulosic residues: alternatives in Thailand D L PYLE and C A ZAROR Energy from biomass (programme & policies) O P VIMAL and N P SINGH Development of biomass in Malaysia K S ONG and C F LAU The biomass role in the Brazilian energy balance I GOCHNARG and G L GROSZMANN Small steam systems for the Third World D HISLOP and S JOSEPH Biomass energy and rural development in Coastal Ecuador M MCKENZIE HEDGER Dissemination of energy technologies: stove and forestry projects in Gujarat M M SKUTSCH Fuelwood scarcity in rural India: perceptions and policies S MATHRANI and D L PYLE Implementation of wood gasifiers and their use within the project “solar village Indonesia” G HOFFMANN, U OHRT and H PITZER 1.4 and 4.8 MW woodgas power plants in operation S SONNENBERG, W O ZERBIN and T KRISPIN The bamboo: raw material for paper industries or fermentation industries T TSHIAMALA, A MOTTET, L FRAIPONT, P THONART and M PAQUOT Issues related to introduction of energy-cane to Latin America P JAWETZ and G SAMUELS

1177 1183 1190

1196

1201

1208 1213

1218

1224 1229 1234 1239 1244 1251 1256 1262

1266 1271 1276

The potential for alcohol as a fuel for spark ignition engines in Tanzania J S CLANCY, G RICE and S KAWAMBWA IV INDUSTRIAL

1281

Biogas as fuel: the adaptation of a tractor diesel engine and a small spark ignition engine to biogas operation J FANKHAUSER, M RUDKOWSKI, E STADLER, K EGGER and A WELLINGER The use of gas from biomass in engines experiences E NOLTING and M LEUCHS Aquatic biomass production and piscicultural waste stabilization C LE FUR, C SIMEON, M SILHOL and Ph BLACHIER Understanding refuse decomposition processes to improve landfill gas energy potential D J V CAMPBELL, E R FIELDING and D B ARCHER Environment protection and energy recovery—decomposition gas from the Berlin-Wannsee municipal waste disposal site J SCHNEIDER Product development needs of weste management P VILPPUNEN Sewage sludge as energy source H P ZWIEFELHOFER Flame development in spark-ignition engines burning lean methanol mixtures R A JOHNS and A W E HENHAM Rubber seed oil for diesel engines in Sri Lanka P D DUNN and E D I H PERERA New direct injection diesel engine development for using vegetable oil as a fuel K ELSBETT, G ELSBETT and L ELSBETT Optimisation of the spark advance in biogas engines B LEDUC and P LADRIERE

1287

Author Index

1348

Subject Index

1359

List of Participants

1366

1293 1298 1304

1310

1315 1319 1323

1329 1337

1344

OPENING SESSION The Energy from Biomass Programme of the Commission of the European Communities— A.S.Strub La biomasse dans la compétition énergétique— A.Giraud Biomass Fuels in a European Context— R.M.Seligman The Italian Biomass Scene— G.Ammassari Avenir de l’agriculture européenne et valorisation de la biomasse— L.Perrin The Common Agricultural Policy and Biomass Energy— J.J.Scully Kurzfristige Verfügbarkeit von Forstlicher Biomasse in der Bundesrepublik Deutschland— A.F.Weismann La biomasse, source de substituts au pétrole dans le secteur des transports— P.Le Prince et J.P.Arlie

THE ENERGY FROM BIOMASS PROGRAMME OF THE COMMISSION OF THE EUROPEAN COMMUNITIES A.STRUB Commission of the European Communities Brussels Summary In the past decade, bioenergy has been the subject of considerable R&D in the E. C., in other industrialized countries and developing countries. At large scale, biomass cannot be used as a fuel without reference to the social and economic framework in which food and fibre are produced. The main objectives of “Energy from Biomass” R&D should therefore now be directed into the following key issues: energy security, environmental aspects, relieving the overproduction in some agricultural sectors, creation of jobs in rural areas. Biofuels may have an extra chance in the frame of the new European fuel blend policy. The most likely scheme foresees replacing lead by 3% of methanol and 2% of co-solvents. Co-solvents derived from biomass by fermentation could form the basis of such a strategy. Biomass utilization schemes would offer great promise for rural development. Energy plantations, collection of agricultural residues and coppice and their conversion into energy carriers of higher density could be part of a regional network. Many jobs could be created, large amounts of wastes could be recycled and unused forests could become accessible for new commercial exploitation. There is therefore a good reason for further developing this alternative, renewable energy resource. In the past decade, the production and use of biomass for energy purposes has been the subject of considerable R&D efforts in many industrialized and some developing countries. The technologies which drew the main attention were wood and straw-burning, biogas production from agricultural wastes and thermochemical conversion by processes such as pyrolysis and gasification. Since 1975 “Energy from Biomass” has been a major topic of the European Community’s First and Second Energy R&D Programmes. In 1980 these R&D programmes were completed by a granting scheme for energy demonstration projects, including biomass production and conversion. The results of the Community action are numerous and certainly contributed to the overall progress achieved and the confidence with regard to the energy potential at stake. This Conference and its two predecessors at Brighton (UK) and at Berlin (F.R.Germany), all organised by the Commission’s services

Energy from biomass

4

responsible for the Energy from Biomass R&D Programme, are including reports on the Commission’s activities. But the time has come to broaden the scope of our efforts. Since almost all of today’s biomass is generated in agriculture and forestry, it has to be recognized that the bioenergy concept must duly take into account the social and economic framework in which food and fibre are produced and used. The main objective of the Community’s future “Energy from Biomass” R&D will therefore not only be determined by energy relevance but include also key issues such as improvement of the environment, alternative use of agricultural overproduction and creation of jobs in rural areas. This is a very wide field. To cope with all the problems, a joint European effort is required. At present, the total bioenergy potential in the EC is estimated at about 5% of our energy consumption. This could be doubled by relatively small changes in agricultural and/or forestry production. Therefore, the possibility to reinforce or to re-orient the already powerful incentives for rural development in the EC should be carefully considered. Rural areas could seek technologies for deriving energy from indigenous biomass and thereby compensate for their inherent structural and energy supply handicaps. Environmental considerations are playing an increasing role when assessing the pro’s and con’s of energy production from biomass. (Methane production from animal waste is a positive example of effluent treatment.) Biofuels may get their chance in the framework of the new European fuel blend policy. A possible scheme foresees replacing lead by 3% of methanol and 2% of co-solvents. Co-solvents derived from biomass by fermentation could form the basis of such a scheme. But it is important to note that fuel blending will require a considerable amount of further R&D, before final conclusions can be drawn. But this should not prevent us from implementing what we already know. For the European Community, which currently produces agricultural products without a real market on more than 5 million hectares of its farmland, there is also a pressing need to assess the potential of energy plantations as a new possibility to alleviate the problem of excess food production. In summarising, we therefore can only underline that biomass utilization schemes would offer great promise for rural development. Energy plantations, collection of agricultural residues and coppice and their conversion into energy carriers of higher density could be part of a newly designed regional network. Many jobs could be created, large amounts of wastes could be recycled and unused forests could become accessible for new commercial exploitation. But this requires the undertaking of investigations with a very wide scope. Our studies have to address complete systems with all their aspects, many of which go beyond of what scientists and engineers might consider as relevant. It is certainly not enough to treat these questions from the technical and economical side. The scientist and the engineer can only investigate options and provide the technical possiblitiy for choices. We now need a clear political push in order to come to an early and efficient implementation of any choice.

The energy from biomass programme of the commission of the european communities

5

In conclusion we can say that there are many good reasons for further developing biomass as an alternative renewable energy resource. More and more additional, not energy related motivations for pursuing R&D in this field make me believe that this Conference is again very timely. It is so timely as it will allow the scientific community as well as the interested decision makers to assess or to re-assess their priorities in the light of the latest developments. Given the problems at stake, this is a necessity.

LA BIOMASSE DANS LA COMPETITION ENERGETIQUE A.GIRAUD Professeur à l’Université PARIS-DAUPHINE ancien Ministre de l’Industrie Les énergies fossiles, le pétrole, le gaz naturel et le charbon sont des produits de transformation de la biomasse. On sait que le charbon résulte de l’enfouissement et de la décomposition des grandes forêts de l’ère primaire. Le pétrole a pour origine le phyto et le zooplancton qui s’est formé puis déposé avec des sédiments dans les zones marines peu profondes et peu oxygénées. Quant au gaz naturel, son origine est moins bien connue, et peut-être plus diversifiée. Certains gisements paraissent associés à des zones carbonifères, et le grisou lui-même est d’ailleurs du méthane. Dans d’autres cas, le gaz paraît s’être formé au cours du même processus que celui qui a conduit au pétrole. Enfin des résultats récents attribuent la formation des grands gisements de gaz profonds à la transformation de l’ensemble des matières organiques gui se sont développées, puis déposées, dans des zones saumâtres de marais et de deltas analogues à celles que l’on trouve aujourd’hui dans certaines zones tropicales. La nature de la biomasse d’origine est peu connue. Ce que l’on sait le mieux se rapporte à la tourbe et au charbon. Il s’agissait de plantes lignocellulosiques; on a retrouvé des troncs d’arbres et de grandes fougères. Le pétrole, lui, paraît plutôt descendre de microalgues. Quant aux processus de transformation, on ne peut non plus les identifier avec certitude. La température, la pression créée par l’accumulation des sédiments ont sûrement joué un rôle, les micro-organismes et la catalyse enzymatique aussi. Ce qui nous reste de biomasse transformée est extraordinairement faible par rapport à la quantité qui s’est formée au cours des millénaires et il ne nous reste plus, en fait, que les produits les moins dégradables: les hydrocarbures saturés, les noyaux aromatiques ou naphténiques. Pas d’hydrocarbures oléfiniques ou acétyléniques, pas de produits oxygénés sauf le CO2 lui-même, présent dans les gaz. Le soufre que l’on rencontre dans la matière organique se retrouve en effet fréquemment en quantités notables dans le pétrole, le gaz ou le charbon. Ceci n’est pas le cas, par contre, de l’azote, constituant important des protéines, qui n’apparaît que dans certains gaz, ramené à l’état d’élément. Finalement, nous récupérons ces produits ultimes et rares de transformation de la biomasse enfouis dans les profondeurs du sol. La nature et les millénaires ont pris soin de sa fabrication. Il nous reste à supporter le coût de sa détection puis de son extraction des pièges, forcément relativement inviolables qui ont pu les retenir jusqu’ici: Si la fabrication ne nous a rien coûté, la découverte et l’extraction sont, elles, difficiles et dispendieuses.

La biomasse dans la competition energetique

7

La question qui se pose à nous, alors que nous consommons ces ressources qui ne sont pas illimitées et dont le coût va bon an, mal an, en croissant, est la suivante: la biomasse contemporaine peutelle concurrencer la biomasse fossile? Le premier point à établir est de savoir de quelle biomasse contemporaine il s’agit. Pas nécessairement, et méme probablement pas de celle qui a donné naissance aux combustibles fossiles: soit qu’ils ne soient plus répandus sur la terre dans les conditions actuelles comme les grandes fougères de l’époque carbonifère, soit que leur croissance soit trop lente ou leur concentration trop diluée comme le phytoplancton pétrollgène. Il ne s’agit pas davantage—et l’on doit insister sur ce point—des plantes cultivées actuelles qui ont été sélectionnées et développées par des générations d’agriculteurs, savants et moins savants, pour des objectifs tout autres qu’énergétiques: soit pour fournir de la nourriture comme la canne à sucre, la betterave, le blé, l’arachide, le colza ou la luzerne, soit pour fournir des matières premières industrielles comme le coton, l’hévéa ou le sapin du Nord. Des circonstances particulières ont cependant conduit les hommes à utiliser certaines de ces plantes existantes à des fins énergétiques, soit telles quelles comme le bois de feu, soit après transformation comme la canne à sucre ou le maïs. La connaissance de ces procédés de transformation a suggéré à son tour, le recours à d’autres plantes sur lesquelles certaines connaissances, plus ou moins avancées, ont été acquises. C’est ainsi qu’il est devenu possible de dresser un état provisoire et simplifié du domaine de la biomasse énergétique. Celui-ci est caractérisé par une liste d’espèces végétales assurant une transformation relativement efficace de l’énergie solaire reçue en composants (figure 1) dont la conversion en produits énergétiques est connue, aboutissant à une gamme acceptable de coûts.

Figure 1

A titre d’exemple, quelques-uns sont cités dans le tableau 1. Il convient d’insister sur le fait que cette liste n’est pas complète. Elle omet volontairement des produits certes très utilisables, comme certains résidus, mais dont la quantité restera fatalement très faible par rapport aux tonnages de pétrole ou de charbon. Elle ne cite pas non plus des produits qui sont peut-être l’avenir comme certaines microalgues trop peu connues pour qu’un raisonnement économique quelconque ait un sens.

Energy from biomass

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Tableau 1 Culture

Rendetaent hamidité Composition de la matiere seche (en %) (en %) Lignine Cellulose Hemicellulose Lipides Glucides Proleines Cendres Europe PVD laillis à courte 12 à 16 t 20 à 25 t 50 20 à 30 40 à 45 25 à 30 1à3 rotation M.S./ha H.S./ha Canne de 18 à 22 t 50 21 42 32 3à4 Provence M.S./ha Luzerne 8 à 12 t 78 15 32 10 5 15 16 8 M.S./ha Graminées 8 à 13 t 50 à 80 12 32 28 3 10 10 5 Fourragères M.S./ha 2,5 78 13 à 14 2 Blé (grain) 5à7 15 3% t/ha Haïs (grain) 5 à 8 10 à 12 15 1,5 5 82 10 1,5 t/ha t/ha 1 72 7 6 Betterave 40 à 60 77 13 sucrière t/ha 75 8 6 lopinambour 40 à 50 80 11 t/ha Canne à sucre 50 à 120 70 10 23 15 1 42 5 6 t/ha Hanioc 20 à 50 65 3 8 90 3 3 t/ha Hapter 30 à 50 t 80 22 40 31 2 4à5 M.S./ha

Pour que l’on puisse parler de biomasse énergétique, il faut que le produit, s’il ne l’est déjà, soit mis sous une forme qui lui permette soit d’alimenter un foyer de combustion, soit de faire fonctionner un moteur. Il n’est pas nécessaire pour cela de fabriquer des sosies des produits pétroliers. Encore faut-il, en pratique, respecter certaines conditions essentielles, et celles-ci sont parfois surprenantes. Ainsi la gazéification directe du bois at-elle bien du mal à alimenter les moteurs qu’elle encrasse; dans presque tous les cas, le passage par le charbon de bois finit par être moins coûteux. Les ménagères africaines éprouvent beaucoup de réticence à remplacer le bois sec traditionnel par des agglomérés de pulpe de café ou autres qui refusent de s’allumer commodément. Dans l’état actuel de la question, la liste des produits que l’on peut réellement considérer comme capables de figurer de façon importante dans le bilan énergétique est très limitée. Elle comprend (figure 2) le bois lui-même, le charbon de bois (ou le bois torréfié), le méthanol et l’éthanol qui sont des produits de base; le mélange acétonobutylique, sensiblement plus coûteux pour l’instant, peut être nécessaire comme solvant de l’alcool dans l’essence. Nous ne retenons pas, pour l’instant, les huiles végétales qui devraient, cependant, être réintroduites s’il apparaissait la possibilité de trouver un substitut standard et économique au gas oil: n’oublions pas aussi que le moteur à essence peut être substitué au moteur diesel: en outre, dans beaucoup de pays elles doivent être réservées à l’alimentation. Nous n’évoquons pas non plus les résidus divers dont nous savons, bien sûr, qu’ils peuvent conduire à des utilisations locales économiques mais qui ne représentent pas de forts tonnages. Enfin, nous ne comptons pas pour l’instant la méthanisation directe des plantes car nous n’en voyons pas encore à l’horizon la viabilité industrielle à grande échelle sauf pour la dépollution.

La biomasse dans la competition energetique

9

Figure 2

Sur le plan technique, il est aujourd’hui démontré que le méthanol et l’éthanol, quitte à leur ajouter un tiers solvant comme le mélange acétonobutylique, peuvent remplacer l’essence dans les moteurs avec équivalence en volume pour les faibles pourcentages et en pouvoir calorifique au-dessus de quelques %. Pour ce faire, les voitures doivent connaïtre quelques transformations mineures, qui deviendront la règle sur des modèles de série, et un simple règlage d’ailleurs inutile pour les faibles pourcentages. Le kérosène, important dans les PVD, peut aussi être remplacé par les mêmes produits. Quant au gas oil et aux fuels, Selon les types d’usages, on peut les remplacer soit par le méthanol ou l’éthanol, soit par le bois et le charbon de bois, éventuellement gazéifiés. Il n’y a donc plus d’usage fondamental de la biomasse fossile qui ne puisse être pénétré par notre gamme de produits sauf peut-être le transport aérien où on exige un fort pouvoir calorifique par kg transporté. Les problèmes d’utilisation paraissent ainsi aisément surmontables. Les problèmes de production de ces produits intermédiaires, eux, conduisent à un jugement plus mitigé. Il est vrai qu’on sait brûler du bois de feu ou cultiver de la betterave et de la canne à sucre et en faire de l’alcool. Mais on sait aussi que l’on est loin de l’optimum. On pressent que d’autres espèces pourraient se montrer préférables selon les terrains, les climats et les conditions de culture. On sait qu’on va les faire évoluer génétiquement. On peut parier sans risque de se tromper sur d’importants progrès que vont accomplir aussi les procédés de transformation, dans la mesure où la biotechnologie est en plein mouvement. Disons en résumé que l’on dispose de filières agroindustrielles connues, et des chiffres nécessaires pour une évaluation économique, mais que ce ne sont pas encore les bonnes filières et les bons chiffres. Ces remarques étant faites, examinons maintenant la place que la biomasse pourrait se tailler dans le bilan énergétique et tout d’abord quantativement

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Dans une étude non encore publiée, M.J.J.BECKER a évalué que les surfaces cultivées de la C.E.E. correspondant à la production d’excédents agricoles seraient de 9 millions d’ha en 1990. Sans porter atteinte à l’autosuffisance alimentaire aujourd’hui atteinte, on voit que la C.E.E. pourrait produire sur ces seules sources 35 Millions de tonnes d’éthanol, c’est-à-dire plus du quart de sa consommation de carburant, ou 45 MT de charbon de bois, c’est-à-dire, déduction faite de l’énergie consommée, beaucoup plus que la production française de charbon. Au plan économique, des évaluations sérieuses montrent que le méthanol et l’éthanol ne sont pas, au niveau technologique actuellement atteint par leurs filières, compétitifs avec l’essence et le gas oil. Il s’en faut d’un facteur 1,5 à 3. Le charbon de bois, lui, pourrait ne pas en être loin* (voir tableau 2, col. 4). La première conclusion à en tirer, c’est que si l’on met bout à bout les progrès qui peuvent être accomplis par la sélection des espèces, l’organisation des cultures (pour alimenter les usines toute l’année) et les procédés de transformation, le niveau de compétitivité est accessible, surtout si, comme on peut le penser, le prix du pétrole remonte dans les années 90. On devrait donc attendre que les recherches aient progressé. * Et l’on peut même dire déjà qu’il coûte beaucoup moins cher que le charbon national français de certains bassins. Nous pourrions avoir intérêt à transformer une partie de nos mineurs en bûcherons et charbonniers

Il ne s’agit pas là d’un rêve. Nous sommes dans un domaine scientifique en plein mouvement, et le rendement “éthanol” d’un hectare de terre s’élève aujourd’hui seulement à 0,1% de l’énergie solaire reçue. Mais les problèmes rencontrés par l’écoulement des excédents agricoles obligent à se demander s’il ne vaudrait pas mieux convertir, dès maintenant, une partie de nos terres vers des cultures énergétiques. On observe en effet que toute politique agricole qui dépasse l’autosuffisance est forcément coûteuse. Les excédents ne peuvent s’écouler que sur un marché de surplus où les produits sont bradés, tandis que les surplus des autres pays viennent frapper à nos frontières et pèsent, peu ou prou—en empruntant des detours—sur nos prix intérieurs. Le marché du pétrole, lui, n’est pas un marché de surplus. Or, on peut calculer que si l’on appliquait aux cultures énergétiques, les subventions appliquées actuellement aux excédents agricoles, les carburants de biomasse pourraient, alors, devenir compétitifs (voir tableau 2, col. 5).

Tableau 2 Coût des carburants et combustibles dans la C.E.E. Produit

Super Méthanol ex bois

(1) (2) Prix Pc H.T. F/t th/t 2 520

10 500 1 677 4 760

(3) Prix à la thermie

(4) Prix avec subvention équivalente (1•) F/T c/th

(5) Prix avec subvention èquivalente (2•) F/T c/th

24 35

750 à 1 380

16 à 29 525 à 1 285

11 à 27

La biomasse dans la competition energetique

Ethanol

11

4 314

6 67 1 930 à 3 330 30 à 52 495 à 2 890 7,7 à 45 390 LPG 3 126 à 3 11 28 à 33 683 000 Fuel domestique 2 240 10 22 150 Fuel lourd 2 136 9 22 600 Charbon 600 5 12 000 Lignite 150 2 7,5 000 Charbon de bois 1 350 7 19 430 à 890 6 à 13 −1 165 à −16,6 à 10,3 000 720 Bois taillis à 180 1 9,5 23 à 100 1,2 à 5 −175 à 147 −9,2 à 7,7 courte rotation 900 J.J.BECKER—thèse non publiée (1) Coût du substrat agricole évalué en supposant la conservation de la main d’oeuvre agricole sur l’exploitation (2) Coût du substrat agricole évalué en ne conservant que la main d’oeuvre nécessaire à l’activité énergétique

On devrait conclure qu’il convient de s’engager sans tarder dans cette voie. On peut prédire, cependant, que celle-ci risque d’être—tout comme la politique agricole commune actuelle—une nouvelle impasse si on ne trace pas dès le départ une politique qui doit s’attacher à résoudre en tout cas deux problèmes: Le premier est de donner aux aides de la Communauté une forme qui conduise la biomasse au progrès. Ces aides doivent être construites pour disparaitre au fur et à mesure que les filières énergétiques feront des progrès. Il faut qu’elles les poussent au progrès. Il ne faut pas raisonner seulement sur les moyens de financer un “coup sec” tel que la construction isolée d’une usine d’alcool. Il ne faut pas en faire un nouveau rachat d’excédents. Le deuxième problème dont il faut se préoccuper est la façon dont l’agriculture et l’industrie vont se raccorder pour faire réussir une filière agro-industrielle. L’agriculture ne pourra pas, seule, distribuer ses produits; l’industrie du pétrole ne sait ni faire pousser des plantes, ni les collecter, ni les conserver et les conditionner au besoin par une première transformation. Certains rêvent sans doute d’un Office d’Etat rachetant les alcools comme des surplus agricoles et les revendant, au besoin par la force des règlements, et à perte, aux distributeurs. Comment ne pas voir qu’un tel dispositif maximiserait plutôt la divergence des intérêts que leur convergence, condamnant ainsi le développement de la biomasse à l’échec. Il faut, au contraire, intéresser les différents partenaires au succès, chacun faisant ce pour quoi il est le plus compétent. En analysant le développement de la filière, on se dit que le bon point de raccordement se situe peutêtre au milieu du processus de transformation: la première étape, pratiquée dans un dispositif de type coopérative agricole, consisterait à élaborer des produits bruts aisément transportables qui seraient terminés dans des usines de type pétrolier.

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Dans les PVD, la biomasse ne présente pas les mêmes caractères. Les rendements peuvent être, en certains endroits, plus élevés et les espèces utilisables ne sont pas les mêmes. La structure des coûts n’est pas non plus identique. Arithmétiquement, le problème de la surface disponible ne se pose pas car la consommation des produits pétroliers est généralement très faible comme le montre le tableau 3 sur quelques exemples. Ces chiffres montrent naturellement qu’il est parfaitement possible, en choisissant opportunément les filières, de ne pas empiéter sur les surfaces consacrées aux cultures alimentaires. Des végétaux tels que l’herbe de Napier (herbe à éléphant) ou l’eucalyptus pourraient donner de la matière sèche compétitive avec celle de la canne à sucre. Les obstacles rencontrés dans les PVD sont d’un autre ordre et sont malheureusement très variés. Malgré de grands efforts, la World Bank l’a constaté, il est très difficile de trouver un pays où l’un de ces obstacles au moins ne soit pas présent empêchant un projet industriel de se mettre en place. On peut citer:

TABLEAU 3 PAYS ETHIOPIE GHANA KENYA MAROC SOMALIE

(1) (2) SURFACE IMPORTATIONS NETTES KM2 PÉTROLIÈRES MILLIERS DE TEP 1 221 900 239 460 582 646 458 730 639 969

560 870 1 237 4 055 249

(3) SURFACE POUR BIOMASSE ÉQUIVALENTE 1 400 2 175 3 100 10 135 620

% SURFACE 0,11 0,91 0,53 2,21 0,09

– le fait que la culture qui serait favorable n’est pas encore suffisamment étudiée. (Un projet fondé sur le manioc en Nouvelle-Papouasie est dans ce cas; de même, on n’en sait pas assez long sur les végétaux adaptés aux zones arides). – la difficulté de modifier, fût-ce très peu, les engins d’utilisation (les fourneaux des ménagères, les voitures et les moteurs existants), simplement les habitudes (remplacer le kérosène par du charbon de bois). – l’inaccessibilité de nouvelles zones de culture, – le temps nécessaire pour former la main-d’oeuvre, – la faible taille des projets envisagés. On fait couramment par exemple les calculs sur une unité d’éthanol de 500T/j: c’est l’ordre de grandeur de la consommation d’essence de toute l’Ethiopie. Or, on ne peut pas convertir du jour au lendemain toutes les automobiles d’un pays, etc… etc… De ce fait, on doit être prudent à l’égard des évaluations économiques qui sont établies sur des cas théoriques ou même, sur celles qui correspondent à des projets assez détaillés, car il y a toujours une étape de ceux-ci qui comporte un certain pari. Cependant, les chiffres sont déjà favorables (tableau 4). Bien fabriqué, le charbon de bois est déjà deux à trois fois moins cher que le kérosène et le gas oil, quatre à cinq fois moins que les GPL. Le prix de gaz fabriqué dans un gazogène rivalise avec celui du gas

La biomasse dans la competition energetique

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oil et serait ainsi utilisable pour les camions et les moteurs fixes. La fabrication de méthanol ou d’éthanol, dans des conditions convenables (taille suffisante, combinaison de cultures) pourrait être à peu près compétitive, comme l’a montré l’exemple brésilien.

TABLEAU 4 COUT DES CARBURANTSSET COMBUSTIBLES DANS LES PVD PRIX F/T Pcc TH/T PRIX À LA THERMIE C/TH SURERCARBURANT 2 500 À 5 000 METHANOL EX BOIS 800 À 1 300 ETHANOL 2 000 À 3 500 FUEL LOURD 1 500 À 3 000 CHARBON 450 À 900 BOIS 65 À 100 CHARBON BOIS 550 À 750 J.J.BECKER—thèse non publiée

10 500 4 750 6 390 9 600 6 000 1 900 7 000

24 À 48 17 À 27 31 À 55 15,5 À 31 7,5 À 15 3,5 À 5,3 8 À 11

Résoudre le problème devient ainsi une affaire de volonté et d’obstination. Quatre-vingt quatre nations en voie de développement représentant des milliards d’hommes importent ensemble environ 300 millions de tonnes d’hydrocarbures. Cela constitue pour beaucoup d’entre elles une charge énorme: 30%, 40%, parfois plus, du montant de leurs exportations, une charge annuelle pour leurs économies du même ordre de grandeur que le montant total de leur dette. C’est pourtant ce qu’il serait possible de produire sur 100 millions d’hectares seulement, alors que l’Ethiopie seule compte 8 millions d’hectares de forêts et 20 millions d’hectares de savane, et que la superficie du Brésil est de 850 millions d’hectares et celle de l’Afrique de 3 milliards d’hectares. Il n’est pas possible de rester indifférent devant cet enjeu et il faut souhaiter que la Banque Mondiale, qui en a mesuré l’importance et les difficultés, reçoive tous les concours nécesaires, financiers, industriels et scientifiques. Ainsi, que ce soit en Europe ou dans le Tiers Monde, le moment est venu pour la biomasse de commencer à faire son entrée dans le bilan énergétique. Les problèmes sont identifiés, il faut les résoudre.

BIOMASS FUELS IN A EUROPEAN CONTEXT R.M.SELIGMAN, B.A. (Oxon) Member of the European Parliament for West Sussex, U.K. and Vice-Chairman of the Committee on Energy, Research, and Technology Summary Two and a half years after the European Parliament called for a 60 million ECU 5 year programme on Energy from Biomass, the Council of Ministers in Brussels has adopted such a programme, albeit a somewhat reduced one. The EEC, therefore, has to choose where to concentrate its efforts in the enormous field of Biomass energy. The writer considers that the areas where energy crops can make the most important economic and political impact are in Short Rotation Forestry for methanol production, and in root and cereal crops for Ethanol production, both to be used as ingredients of Motor Fuel. Biotechnology and improved equipment are causing Agricultural Productivity to increase relentlessly, producing unwanted food surpluses. Energy crops most replace these surpluses. The use of Agricultural oxygenates in Motor Fuel will not only reduce dependence on imported oil, it will improve the balance of payments, provide work for farmers, help the energy problems of the developing countries and, more recently, offer a solution to the octane and environmental problems of unleaded petrol. Major research efforts are now needed, using advanced biotechnology and process engineering, to reduce the cost of the agricultural oxygenates and to find profitable uses for the byproducts. Ways to sunmount the various political and economic obstacles, and the doubts and objections to the adloption of bio-energy, will be examined. 1.1 Introduction It is my intention today to comment on the political and economic realities which lie behind the move towards biomass energy. The oil crises of 1973 and 1979 greatly increased interest in Alternative Energy Sources. Unfortunately, it also increased the importance in alternative non-Opec oil sources, like Mexico and the North Sea. Non-Opec production increased in 4 years from 2.5m to nearly 9m Bpd. The World recession which resulted from high oil prices, combined with the new sources of oil, resulted in the present glut of oil. This oil glut then caused the

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slowing down or abandonment of many very promising R and D projects in Alternative Energies—not least coal liquification and gasification, biomass, solar and geothermal energy. But my impression is that there is now a renewed interest in Alternative Fuels, because oil prices are expected to rise again in the next 10 years, as economic recovery accelerates. As Henry Kissinger said in the Sunday Times recently, “The present temporary respite from oil pressures must be used to expand conservation policies and to encourage the development of Alternative sources of energy—exactly the opposite of the present shameful trends. “Otherwise the 1990’s, once more facing an energy shortage, may well CURSE the BLINDNESS and the lack of foresight of Current Leaders”. Our generation Mr. President—will go down in history as immoral and grossly selfish. In the short space of 70 years—one short life time—we have squandered finite resources of oil and gas, in blissful disregard for future generations—spending pathetically little on research in Renewable energy and rejecting an energy or oil import tax, because it would inhibit the greedy guzzling of imported non-renewable fuel. The revenue from such a tax could well be used for research into energy conservation, and alternative renewable fuels, fuels which come from the Sun’s energy. I sometimes despair of short-sighted politicians. But, Mr. President, I think things are beginning to move our way. The political background to the growth of energy from Biomass is becoming daily more favourable. Not only is North Sea oil production reaching its peak, shortly to decline, but the world is becoming more environmentally conscious every day. Citizens are turning their minds away from the politics of war, and turning more towards the politics of fighting pollution. And every anti-pollution move brings us closer to Biomass energy. Not only does burning coal, oil and gas as a fuel, waste a large number of complex and valuable ingredients, which go up the chimney in smoke—it also generates sulphur and nitric acids which pollute the air we breaths and probably kills trees, lakes and fish as well. Nuclear power is probably one of the cleanest and safest forms of electricity generation, but you cannot use that for driving motor cars, motor boats or aeroplanes. The Green movement in Europe is gaining political influence, especially in Germany. This means that we have to listen to them. And their message on energy is contained in an amendment to the Energy Pricing policy of the EEC, which the Greens pushed through in Strasbourg last Week. “Parliament notes that Research indicates that biomass can be used to oover up to 20 per cent of Mamber States energy requirements, and that our agricultural surpluses can be eliminated through using biomass; calls, therefore, for the necessary initiatives to be taken at European level, to develop the use of Biomass”. 20 per cent may be on the high side, but I am very glad that the Council of Ministers in Brussels, has at last adopted a Biomass Energy programme—albeit, however, only for 20m BCU against 60 BCU demanded by the European Parliament 2½ years ago, when I was Rapporteur for a 5 year international programme in biomass energy. This conference is ideally timed to make suggestions for incorporatian. in that programme. The European Parliament realises that Biomass must come of age. It can no longer be a futuristic, hypothetical technology. It must fight in the market place on equal terms with

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other technologies, We have to convince the authorities and the farmers that they can make a living out of energy crops. But a Biomass energy source which is suitable for one region, or climate may not be suitable for another. That is why I am delighted that this conference is drawing contributions from so many different countries. In particular, the Mediterranean, Scandinavia, Zimbabwe, Canada, Florida and China. Furthermore, different Biomass environments are discussed. Arable, industrial, aquatic and forests. The basic problem, however, is not technology, it is economics—it is MONEY. That is why there will be no massive swing into Biomass Energy, until the price of Hydrocarbons goes up again. We have to be ready for that moment. Basically, it is far better to use available land in the EEC and the Third World to produce energy crops that we need, rather than food surpluses which we don’t need, and that we have to sell off to the Russians and others at a substantial loss. It is costing the EEC somthing like 7 Bn BCU a year—just to get rid of the surplus food on World markets, and in free Food Aid. It must be sensible to replace this costly food surplus, with energy crops, if it can be done without costing more than it does now. 2. MOTOR AND TRACTOR FUEL The biggest prize in Biomass Energy at the moment is fuel for cars and tractors. But I understand that: cost estimates for producing Agricultural Alcohol are still far too high. An oil company told me that while conventional Motor spirit costs only 350 ECU a tonne/grain alcohol costs between 795 and 875 BCU per tonne to produce; sugar beet alcohol costs 675 BCU per tonne. I have no figure for artichoke alcohol. So one vital area of research is to find ways to make Agricultural Fuel Alcohol cheaper and more competitive with fossil fuel. I don’t believe we are anywhere near the end of the road in this sort of research. 3. RESEARCH IN SOUTH AFRICA In South AFrica, which I visited recently, the Government are hoping eventually to derive 15% of their liquid fuel requirements for cars and tractors from agricultural alcohol and plant oils. Since 50% of their fuel goes into Farm Tractors, they tend to concentrate on tractor fuel. 3.1 Ravno and Purchase of Durban University Agricultural Energy Institute, decided that the main obstacle to Ethanol in Motor Spirit, or tractor fuel, is the high cost of the raw mterials, which is 65% of the total cost. They are doing meaningful experiments to derive Alcohol directly from Bagasse, which otherwise accumulates as waste, and can be obtained very cheaply. Now maybe cane sugar bagasse is of little Interest to Europeans, but it certainly should be to the developing nations. The process seems to be to hydrolise the hemicellulose component, which is 35% of the waste by dilute H2 SO4 to Xylose, leaving a residue of cellulose and lignin. Xylose can then be fermented to alcohol.

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The balance of Bagasse Cellulose is converted to glucose by enzymes. One third of the carbon of the Bagasse then remains as burnable. In this process 70% of the Bagasse, which costs only £10 a tonne, is made fermentable, meaning that the raw material for alcohol costs not much more than £15 a tonne. So that could be one way to cheapen Bio-ethanol. 3.2 The Department of Agricultural Engineering in Natal University at Pietermaritzberg have been blending diesel with up to 15% Ethanol (mark you South Africa has a warmer climate than ours). They store the ingredients separately to avoid phase separation. They do use Nitrates as CETANE improvers from the Ethyl Corporation, Baton Rouge, U.S.A. The Economics of mixing Ethanol with Diesel depends very much on the price charged by the Government for SASOL diesel. This research work is important strategically in case South Africa’s supply of imported oil is cut off. 3.3 Thirdly, many of those present will be aware of the successful work done in the Agricultural Engineering division of the Department of Agriculture in Pretoria by Fuls and others, on using degummed sunflower oil esterified by Ethyl Alcohol with a Sodium Hydroxide catalyst in a direct injection compression ignitition engine. Fuls is convinced that many different plant oils (including non-food plant oils), could be used in the same way to drive Third World tractors, and this lends interest to Unilever’s new Palm oil clones, which yield 30% more oil than traditional strains. These are examples of the endless search by scientists for solutions to the energy problems of our time. Research has to go on constantly seeking new ways through, or around, apparent technical road blocks. 4. THE ADVANTAGES OF BIO-ETHANOL The World needs an alternative transportable motor fuel to mineral oil. It may one day be hydrogen, generated by nuclear energy, but ethanol has so many economic and political advantages. 4.1 Firstly, it provides a solution to the problem of farm food surpluses, and be sure these surpluses are going to increase every year due to the march of agriculture science, in selective breeding, growth regulation, hormone management, tissue culture and better fertilisation. 4.2 Secondly, ethanol offers import savings to the EEC and Third World countries, who have to spend most of their own export earnings just to pay for their fossil fuel imports. 4.3 Thirdly, the higher value of the dollar has made imported crude oil much more expensive than it was, compared with alternative indigenous fuels. 4.4 Ethanol offers an alternative to lead in petrol, as an octane booster. 4.5 Fifthly, ethanol offers an environmental improvement by replacing hydrocarbons containing sulphur, which pollutes the urban air we breathe. If ethanol can be cheapened, and if it’s bad effect on cold starting and the motor octane number can be resolved, it is bound to be used more and more.

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The practical problem with Ethanol lies in the reluctance of the international oil majors to using agricultural oxygenates. And after all, they are the people we have to persuade. They, and the motor manufacturers, have to take the action— they have to adapt their refining processes and engine designs to accommodate ethanol and methanol in their fuel. They have to be persuaded that their balance sheets at the end of the year will not suffer. How can this be done? This is an ideal job for the EEC Commission. The Commission should launch a research programme to provide answers to the specific objections raised

5. OBJECTIONS TO OXYGENATES 5.1 The first objection. I have heard that there is insufficient land in the EEC to produce the amount of Ethanol we would need. This must be nonsense. I am told that the Agricultural surpluses produced by the CAP occupy 8 to 9 million hectares out of a total of 152 million hectares. On one hectare, one could produce 4 tons of ethanol per year, plus one ton of biomass residues, which on 8 million hectares, would give us 32 million tonnes of ethanol per year. With 90 million tonnes of gasolene consumed per year in the EEC, 35% could theoretically come in the form of Ethanol from the land which at present is producing the unwanted food surpluses. In fact, with Ethanol likely to be limited in the EEC to 5% of motor fuel at present, we would have 7 times more land than we need. So don’t lets hear any more about the limitation of available land. 5.2 The second objection is—“How can you talk abcut converting good cereals into fuel alcohol, when these cereals are needed by the starving millions in Ethiopia and the Sahel?” Firstly, the EEC is planning to send 2.5 million tonnes per annum of cereals to Ethiopia and the Sahel. But the production surplus over requirements is more like 20 million tonnes a year. Most of this is sold abroad at World prices, which are tamporarily high—due to the high value of the American dollar. This may not last. In which case the cost of restitution, when we sell surplus cereals abroad, will go up again. If, and when, World cereal prices fall back again, it will become more difficult and more expensive to sell cereals on the World market and more will then be available for conversion into fuel alcohol. In any case, it would be quite wrong to regard Europe as the permanent granary for the starving world. To provide Emergency supplies in a crisis is a good humanitarian act. To plan to permanently dump our surplus food on the Third World would be quite wrong. We must help them to become self-sufficient in Food. In their own interest, we must help them to build up their agriculture and infrastructure by investing and giving them technological help. So I don’t see at all that the argument against using our surplus cereals for fuel alcohol instead of food has any validity at all. 5.3 The third objection is technical. It is that Ethanol as a substitute for lead is only a partial answer. If you have a high or medium compression engine, as we have in Europe, Ethanol will not eliminate high speed knock. There must be a research answer

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to this. Furthermore, for each 1% of ethanol added, you only get 1/5th of an octane number improvement. This means you would need 25% ethanol to gain the improvement of 5 octane numbers needed to replace the 0.4 grams/litre of lead which is currently in use in the EEC. You would need abcut 10% ethanol to replace the future level of lead of .15 grams/litre. This would be permissible in the U.S.A.; but in the EEC, the Commission has been more cautious and wants to limit ethanol to 5%. So the current thinking in Europe is that 3% methanol derived from hydrocarbons is acceptable with 5% ethanol as a cosolvent. The question is whether Ethanol has yet been proved to be an adequate cosolvent. If it is, the Farmers and the C.A.P. have a good outlet for 5 million tonnes of ethanol per year on over a million hectares. If it is not, oil companies may prefer to use T.B.A., as a cosolvent, or M.T.B.E., an as an actane booster, neither of which would come cheaply from Biomass. 5.4 The fourth main objection is the one about Energy Balance. It says that you have to put more energy in to Ethanol production than you get out of it. I don’t consider this a valid argument. Cars and aeroplanes cannot run on coal or nuclear power. They need a liquid transportable fuel. What the Brazilians have done is to convert solid raw mterial—cane sugar into a convenient liquid transportable fuel—alcohol. Provided the energy imbalance is not unreasonable, Gasohol production from sugar is a sensible replacement for petrol. The Swedes in their Biostil plant at Skaraborg,, saccharify, ferment and distill surplus wheat in a continuous process which is engineered for maximum heat regeneration, which should greatly improve the energy balance of ethanol production from cereals. 5.5 A fifth objection to Bio Ethanol production for motor fuel is that the surplus subsidised ethanol might compete with the potable spirit industry. Clearly, the production process must be adapted to make the product undrinkable. 5.6 But the real objection by the oil mjors is the Economic one. And the corridors of power in the Commission in Brussels and in Bonn and Paris, are buzzing with this controversy. For a 5% ethanol as cosolvent for methanol in motor fuel, we need about 5 million tonnes of agricultural ethanol. I calculate that this alone would need a subsidy of well over 1 Bn BCU per year. As I said earlier, the production cost of 100% DRY ethanol from Beet Sugar is about 675 BCU per tonne and from cereals between 795–875 BCU per tonne. The oil companies don’t want to pay more than about 250 BCU per tonne for dry ethanol. This seems an unfairly low figure when petrol. costs 350 BCU per tonne to produce. At this rate, a subsidy of 425 BCU per tonne of Dry sugar beet alcohol, or 545 BCU per tonne of Dry wheat alcohol, (compared with the proposed 700 BCU per tonne subsidy for wine alcohol), would be necessary. At the moment due to the high dollar, very little restitution—perhaps 25 ECU/Tonne—has to be paid by the EEC on cereals sold on the World market, which indicates that it is much cheaper at present to sell as much cereal as possible on the World market with only a 25 ECU/tonne subsidy, than convert it into ethanol with a 545 ECU/Tonne subsidy! This my change, however, and the

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dollar my fall again, and then World cereal prices will fall. Then the cost of restitution will increase, and a large subsidy on cereal alcohol for motor fuel will not look so out of line. Nor must we forget that the main alternative for oil companies is to change the oil refining process and invest in expensive reformers in order to reach the necessary octane number. This will consume more crude oil and cost more.

6. CONCLUSION Europe is getting increasingly excited about Bio-alcohol, as a substitute for lead in petrol. There are still a lot of hurdles to cross before it becomes a commercial reality. But there is a lot going for it. (a) Bio-Ethanol is environmentally more acceptable than lead, or Hydrocarbons. (b) Bio-Ethanol production would help to solve the problem of cereal surpluses. (c) Bio-Ethanol would help to reduce our excessive dependence on imported oil. (d) Bio-ethanol, is infinitely renewable, whereas liquid and gaseous fossil fuel reserves have only about 70 years to run. In its new Biomass progamme, or a separate one, the Commission must take each objection to the adoption in the EEC, and the Developing World, of Bio Ethanol and vegetable oils as fuels, analyse them and research for solutions, together with all interested parties. A new programme must bring together experts from the oil companies, the motor manufacturers and the farmers, to sponsor joint research to determine the facts, and finally come up with the solutions to these urgent problems. I am sure they can count on the full support of the European Parliament, if they do this. The Schleicher Resolution 1349/84 advocating Bio ethanol in motor vehicles for environmental reasons has wide support in the Christian Democrat, Conservatives and other Groups in the Parliament. The sooner we can adopt renewable motor and tractor fuels, the sooner will energy supplies for transport for future generations be assured. I look forward to the day, when, like Brazil, we have cars running on pure Alcohol. Meanwhile, I have one other quite different suggestion, which I want to make to the conference. It concerns the use of biotechnology for energy conservation. After all energy saving has been described as the fifth fuel. I think that the biomass programme should take under its wing the whole question of energy conservation, in food production by economising in the use of fertilisers, in the cost of fuel in horticulture, in selectibe breeding, or biotechnology, to accelerate growth rates and reduoe the heat and energy needed to achieve fully grown plants, flowers and vegetables. Biological energy conservation is a whole technology which should become part of the biomass energy programme.

THE ITALIAN BIOMASS SCENE by Prof. G.AMMASSARI Direttore Nuove Fonti d’Energia Ministero Industria Commercio Artigianato Roma, Italy 1. THE OBJECTIVES OF THE 1981 NATIONAL ENERGY PLAN IN THE BIOMASS SECTOR Italian energy policy is outlined in the National Energy Plan, which was approved by Parliament at the end of 1981 and which defines, by sector, objectives to be pursued, measures to be taken and resources available in the long-term, with three-yearly revisions. One of the main objectives of the National Energy PLan is the promotion of energy saving and the development of renewable energy sources as a means of reducing the consumption of primary resources. The other aims are the development of the nuclear, coal and natural gas sectors and the establishment of a programme for the petroleum sector. In the sector of renewable sources, particular emphasis is placed on the production of energy from biomass and the widescale promotion of the technologies which have already been developed. This is an extremely flexible sector in many ways, with a variety of sources of raw material (refuse, residues, agricultural/forestry crops etc.), conversion processes (biochemical, thermochemical, combustion) and final uses of t he product (heat, electricity, transport, agriculture) and with a number of advantages for the country and the environment. 2. THE BIOMASS POTENTIAL IN ITALY The most interesting sources of biomass in Italy, in view of the characteristics of the country and the structure of the agricultural and livestock systems, are: a) the organic fraction of urban and industrial waste b) green residues (cereal straw from corn stalks, beet tops and leaves etc.) c) livestock wastes (manure, slurry etc.), the recovery of which could Lead to a substantial reduction in the pollution of the environment, particularly the surface waters d) residues from forestry activities have some potential, although less than in other countries. a) It is difficult to assess how much urban waste is available nationwide. According to surveys carried out by the National Research Council (CNR) in 1980 for the first Specific Energy Project, Italy produces an estimated 14 million tonnes per year,

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approximately, at an average daily rate of 700g per capita, with a calorific value of between 1000 and 1500kcal/kg. Approximately 65% of solid urban waste is dumped, approximately 25% incinerated and approximately 10% recycled. We can estimate, from the geographical distribution, that only 15% is subject to any form of treatment which would allow energy recovery, while most of it is dumped in more or Less controlled tips. At the end of 1984, approximately one hundred incinerators were in operation, but only a few were equipped for heat recovery and/or electricity generation. Some thirty were equipped for the preparation of compost for agricultural purposes and only a few for recycling, separation of paper, metals, glass and plastic and/or production of refuse derived fuel. Annual production of industrial waste was estimated by the CNR at 35 million tonnes. of this, only the organic waste with chemical and physical properties enabling it to be treated by the same processes used for organic waste and biomass is used for recovery of energy. The most useful part is the waste from the food industry, amounting to some 2.5 million tonnes. b) Vegetable wastes in Italy amount to approximately 20% of the principal crops grown, or an average of some 30 million tonnes/year with green residues accounting for 5– 7%. The quantity of green residue which could theoretically be recovered from a crop depends on a number of factors such as the capacity of the crop to produce biomass (e.g. the straw grain ratio), and the properties of the crop, which determine how the residue behaves when it is harvested and thus suitable. it is for recovery (falling leaves, stalks etc) . Technical and economic aspects of recovery also need to be considered, such as: – useful period of recovery, i.e. harvest season, the time allowed for harvesting etc.; – the organization of the farm, particularly as regards harvesting and storage capacity; – preservation of the soil’s fertility: if organic matter is removed, the soil will become impoverished so that more fertilizer is required, and this has to be taken into account in the overall economic balance-sheet. c) The estimated production of Livestock waste in Italy is about 20 million tonnes/year. In the past, Livestock wastes have been spread on the Land as fertilizer to improve the physical properties of the farming Land. However, changes over the Last few decades in the structure and management of Italian livestock farms have altered the former balance significantly. Intensive breeding concentrated in limited areas has made available substantial quantities of liquid manure, the disposal of which is causing environmental problems. This is the reason for the interest shown by farmers and public authorities in technologiés which, if correctly deployed on an industrial scale, will resolve the serious problem of sewage disposal and permit the recovery of energy and fertilizers.

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d) As regards forest residues, it is estimated that from a national average of approximately 8 million m3/year of firewood, there are 2.5 million tonnes/year of waste to which can be added approximately 0.5 million tonnes/year of wood wastes. However, the expense of collection and transport has to be borne in mind, and especially in the case of forest residue, where costs are particularly high in view of the Low energy content of the wood. The use of wood wastes would be more simple, particularly if carried out in situ.

3. TECHNOLOGIES FOR USING BIOMASS The technologies chiefly used in Italy for the production of energy from biomass are as follows: a) Incineration with recovery of energy from urban waste The waste collected is held in a storage area before being transferred to a combustion chamber, from which slag and fumes are emitted. The yield from urban waste is approximately 1.2 kg of steam per kg of waste, or approximately 0.4 kWh of electrical power per kg of waste, if the plant is also equipped for electricity generation. Combustion with energy production does not exclude the possibility of recovery of materials for recycling (metals, glass, paper etc.), after examination of t he cost benefit of the operation as a whole. The presence of harmful elements in the exhaust fumes can be a problem, but this can be overcome by limiting the combustion of industrial waste and including a post-combustion chamber in the thermal cycle to minimize the formation of harmful substances. Methods of mixing finely ground Solid urban waste with coal dust to obtain a fuel which can be used in conventional furnaces or brick ovens arecurrently being examined. Research in this field is now underway in the ENEL (National Italian Electricity Board) power station at S.Barbara. b) Anaerobic digestion, by means of which a gas comprising 50–70% methane with a total calorific value of kcal/Nm3 can be obtained from vegetable and livestock wastes. The effluent from the anaerobic digester also makes good fertilizer. The need to maintain the system at a constant temperature and to preheat the Load to be introduced, as well as the running of some of the mechanical equipment, mean that part of the gas produced is not available for further use. Between 25 and 35% of t he gas produced is used to fuel the plant itself. Depending on the method used, it is possible to obtain between 1 and 1.5 Nm3/day of biogas per m3 of digester. The benefit of these methods to the farm depends on a number of variables, primarily the continuing high cost of the equipment, which is partly due to the fact that gas-holders have to be used to cope with variations in demand. One of the biggest problems is the size of the plant and the energy generation/consumption ratio. The Livestock breeding structure in Italy, with a

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large number of both small farms and Large industrial farms, means that a Large measure of flexibility is called for. This sector is, however, constantly changing, and a number of measures are being taken by state and private operators. One possible use for anaerobic digestion is to exploit the energy potential of seaweed, and a project is now being studied for the Lagoon of Venice. Its feasibility depends on the overall economic viability of the project and its effects on the ecosystem. c) Alcoholic fermentation: ethyl alcohol can be obtained from all the agricultural products and residues contained in sugars, cellulose and starches by hydrolysis. The alcohol produced can be used directly as a fuel in internal-combustion engines or mixed with petrol. Its use in Italy depends on the impact it would have on the present fuel production/marketing system and the limitations on its use in view of its purity. d) Direct combustion of forest residue and wood waste, straw, some crop waste. The incineration of green wastes and residues and wood wastes gives yields of approximately 50% for manual Loading equipment and approximately 65% for mechanical Loading equipment. Its economic viability depends on the type of product used, the size of the plant, and on making optimum use of the heat produced. e) Gasification of wood wastes and straw. This new process uses partial oxidization at high temperatures (900°C–1000°C) and injection of steam to produce a Low calorific value combustible gas (2500kcal/Nm3) with ash residue of 5% of original waste. Yield is around 65%. Gas produced in this way can be used to generate heat or electricity. In the latter case, in view of the high cost of the equipment, the system must be used intensively and the product must therefore be available virtually constantly throughout the year if it is to be economic.

4. MEASURES TAKEN IN THE PUBLIC SECTOR TO PROMOTE THE USE OF BIOMASS Between 1981 and 1984, on the basis of NEP information, national and local government and energy bodies introduced legislation and took specific measures to promote the use of biomass. The most important of these were: a) Law No 308/82 b) Presidential Decree 915/82 c) measures taken by the CNR with the ENEA and ENI’s first and Second Specific Energy Project d) EEC demonstration projects a) Chapter I of Law No 308/82 on the restriction of energy consumption and the development of renewable resources, provides for incentives for projects involving

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renewable energy sources, including the conversion of organic and inorganic solid waste and vegetable residues. Two types of projects can therefore be distinguished: 1) conversion of organic and inorganic solid waste; 2) generation of heat and electricity in incineration plants. The first group invcludes: 1) production of refuse derived fuel (RDF); 2) production of biogas from controlled tips or waste water purification plants; 3) recovery of material resources from waste sorted upstream or from recycling and processing plants downstream of collection. The second group comprises the thermal treatment of refuse, i.e. combustion or pyrolysis. A number of projects are now underway on the basis of specific Articles of this Law: – Article 10: part of the approximately Lit 20 000 million allocated was used for urban waste derived fuel projects, for electricity and/or heat generation and for plants using agricultural waste for combined heat and power generation. A Large number of urban waste projects were submitted by local authorities and firms involved in this field, so that optimum use can be made of this resource. There has also been a series of initiatives, particularly in the distilleries sector, to develop the use of processing waste (grape seed etc) and waste from other types of agricultural processing as fuel in suitable furnaces, to generate steam and electricity for use in the manufacturing process, thereby economizing on conventional fuels. There have been other useful applications in the wood working sector, where the incentives provided have encouraged energy recovery from wood wastes (shaviňgs and sawdusts). – Article 11 is designed to stimulate new technologiés in the field of renewable energy, providing for financing of 50% of the costs of demonstration projects on a nonreturnable basis. In this sector, there has been interest in new technologies for pyrolysis of industrial organic waste, anaerobic digestion and biogas production processes, the production of biogas from controlled Landfills etc. – Article 13 provides for a demonstration plan for the use of ethyl or methyl alcohol, in a mixture with motor gasoline. The plan has already commenced and comprises three tests: – a test to determine the movement of petrol with Low alcoholic level (3–5%) over a Limited but representative section of the present fuel supply circuit, to detect any possibility of pollution or separation of the fuel; – a fleet test to determiňe how suitable mixed fuels containing up to 10% alcohol are in practice, using a sample of motor vehicles representative of the types of vehicle on the road today;

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– a test on a Limited number of new vehicles to examine and compare the results of the demonstration test above in particutarly difficult operating conditions. The success of the demonstration may enable the national automobile industry to try out devices and materials which could be incorporated into all motor vehicles subsequently manufactured to make them suitable for running on alcohol/petrol mixtures. – Article 12 on incentives for the generation of energy from renewable sources in the agricultural sector, under the responsibility of the Minister of Agriculture and Forests, provides for a total of 126 000 million of financial aid to farms for 50% of the capital expenditure and a total of 20 000 million for interest charges. In a number of Regions the administrative and organizational procedures needed to enable the aid to be committed to the biomass and other sectors have already been set up. b) Presidential Decree No 915/82: Italy has fallen behind other countries in Legislation in the sector of solid urban waste. In 1982, Decree No 915 was promulgated assimilating the EEC Directives and bringing Italy up to European Level. Presidential Decree No 915/82 goes beyond the idea of waste disposal to waste recovery. It provides for the treatment of waste, by which is meant reuse, regeneration, recovery and recycling, to be carried out in accordance with a number of general criteria, including monitoring the impact on the environment and public health, economic and regional planning, and the promotion of systems designed to recycle and reuse waste or to recover materials and energy from it, while bearing in mind the criteria of economic viability and efficiency. The State’s responsibilities in this sector includes, apart from directing, coordinating and supervising activities, the definition of measures designed to stimulate the recovery of energy, promotion study and research where necessary. c) Activities of the ENEA and the CNR The ENEA is involved in a number of activities in the biomass sector: technological research into various processes for converting biomass into energetic products, promoting the industrial-scale production of various systems and components, and demonstrating technologies already tested with a view to encouraging their wider use. It is also involved in the specific energy projects together with the CNR. The ENEA’s commitment for the period 1981–1983 was Lit 15 000 million, chiefly used to monitor anaerobic digestion, direct combustion, gasification and pyrolysis, new biotechnological energy carriers (for alcohol etc.) and biomass production processes. Under the five-year plan for 1985–1989, the ENEA will allocate approximately Lit 30 000 million to the biomass sector for internal and external research, promotion in industry, and demonstration plants, concentrating on biogas production plants, the improvement of thermochemical conversion of wood and lignocelluloses and refuse-derived energy using various processes including biotechnological methods.

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The research carried out by the CNR in the second Specific Energy Policy on biomass is concerned with the rationalization of woodland crops, the colonization of marginal areas, the classification of residues and wastes, trials with processes and components (incineration, biogas, fermentation etc.), for a cost of more than Lit 7 000 million. This research involves the main universities, local authorities and specialist firms. Finally, the ENI is working in the biomass sector with AGIP-GIZA which is involved in the secondary biomass market (residues, processing waste) and is concentrating on both the national and international markets, particularly in developing countries. The period 1981–1984 saw mainly anaerobic digesters (approximately 30) made for livestock waste or food processing effluent. Research activities concentrated on optimizing costs, performance, the fields of application (e.g. solid urban waste) and biomass technologies which could be of some use in developing countries, particularly in the sector of wood gasification. Approximately 10 projects on different technologies are underway. d) EEC demonstration projects: in the period 1981–1984, Italy partici-pated in EEC demonstration projects to promote and develop biomass. The projects submitted by Italy to the EEC are chiefly concerned with the use of biogas, thermal gasification and combustion. Italy has for years been involved in the EEC programme of demonstration projects, obtaining on average 16% of the total funds for biomass. In 1983 and 1984, 8 projects were approved for an overall cost of 27 000 million on: – treatment and production of energy from a central plant serving 62 Livestock farms; – recovery and central treatment of waste and residues; – direct and indirect production of energy, integrated with acquiculture; – production of sawdust as an alternative fuel; – industrial-scale plant for the recovery of energy from waste from the textile industry; – plant for the production of compost; – generation of electricity from biomass; – recovery of energy from distillation waste.

5. CONCLUSION There are now a number of methods developed or at the development stage for producing energy from biomass. The production of energy (generation of heat, biogas, Lean fuels) is nearly always accompanied by other potential uses (fodder, fertilizers, recovery of materials etc.) and by environmental, legislative, economic and administrative implications. Efforts made by the energy authorities and by industry have helped to identify and improve some promising methods. Apart from wood, which makes the most substantial contribution to the energy balance-sheet, agricultural, industrial and urban waste are the

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major contributors to the production of energy from biomass in Italy. For the time being at [east, the use of “energy crops” as practiced in other countries seems unlikely. Considerations such as the protection of the environment and the elimination of waste have promoted the growth of biogas production plants, in view of the need to purify effluent from livestock farms. Further effort is needed by the authorities to coordinate research and cbvelopment to enable as much information as possible to be acquired and to identify the most suitable and promising technologies and build on the experience ecquired so far.

AVENIR DE L’AGRICULTURE EUROPEENNE ET VALORISATION DE LA BIOMASSE L.PERRIN Président de l’Assemblée Permanente des Chambres d’Agriculture C’est avec plaisir que j’ai accepté de participer à l’ouverture du troisième congrès sur la valorisation énergétique de la biomasse. Je remercie les organisateurs de m’avoir invité à cette conférence, me permettant ainsi d’exprimer le sentiment d’un agriculteur français sur l’avenir de l’agriculture et sur le rôle que peut y jouer la biomasse. Si vous le permettez, je ferai un rapide bilan de l’évolution de notre agriculture et des perspectives envisageables. Ceci pour vous expliquer l’impression de désarroi que nous ressentons mais aussi la volonté de réfléchir à notre avenir, de trouver des orientations qui permettent de faire vivre les agriculteurs et les campagnes. Les objectifs assignés à la P.A.C. par le traité de ROME étaient: – l’indépendance alimentaire; – la satisfaction des besoins des consommateurs; – une amélioration de la productivité; – une augmentation du revenu des agriculteurs. Ces objectifs, en tous cas, les trois premiers, ont été atteints avec un large succès. . En 1982–1983, le taux d’auto-suffisance était de 147% pour le sucre, 125% pour le vin, 118% pour les produits laitiers, 117% pour les céréales et 100% pour l’ensemble des viandes. La valeur de la production agricole de la Communauté a augmenté de 18% en termes réels, dans les dix dernières années, alors que la main-d’oeuvre agricole diminuait, elle, de 32%; peu de secteurs économiques ont réalisé de tels progrès de productivité. Les progrès prévisibles en génétique et technique de production permettent de penser que cette évolution est loin d’être terminée. Mais alors que l’Agriculture a encore un potentiel de production considérable: – la demande de produits alimentaires dans la communauté tend à stagner; – sur les marchés mondiaux, les perspectives de débouchés solvables sont limités et la concurrence très dure. Un autre facteur qui nous préoccupe est celui de l’évolution de la pyramide des âges des agriculteurs. Si nous prenons l’exemple de la France, on constate que deux agriculteurs sur cinq ont aujourd’hui plus de 55 ans et parmi ceux-ci, les 2/3 n’ont pas de successeur pour leur exploitation; ceci est vrai pour d’autres pays européens.

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Si on laisse faire, cette éolution se traduira sans doute par une double tendance: – concentration des productions dans certaines régions avec accroissement de productivité; – extension des friches dans les régions les plus deshéritées avec comme conséquences: . une liquidation partielle de l’outil performant de production et de transformation que nous avons mis en place; . une suppression d’emplois agricoles et ruraux; . une accentuation de la désertification des campagnes. Cependant, d’autres alternatives sont possibles. Elles s’appuient sur une diversification des productions agricoles soutenue par une politique vigoureuse d’installation de jeunes agriculteurs et c’est dans cette perspective que s’inscrit le développement de la production de protéines dont nous sommes très déficitaires. Enfin, ces alternatives positives passent par le développement de débouchés non alimentaires pour les productions agricoles: ces débouchés existent déjà mais peuvent augmenter considérablement dans plusieurs secteurs (énergie, chimie, bio-industrie). Dans cette perspective, l’énergie et le domaine des carburants plus particulièrement, offrent certainement un débouché privilégié. Actuellement, les agriculteurs européens produisent des quantités suffisantes pour assurer leurs besoins alimentaires et ils peuvent désormais rendre disponible des surfaces pour la production d’énergie et de matières premières pour l’industrie. Il s’agit là d’une véritable révolution pour le monde agricole: les agriculteurs ne seront plus exclusivement ou quasi exclusivement des producteurs d’aliments. L’affectation de certaines surfaces agricoles pour des usages autres qu’alimentaires et pour des cultures énergétiques en particulier, pourrait donner une sérieuse “bouffée d’oxygéne” à l’ensemble des régions agricoles de l’Europe. Prenons l’exemple du blé. En France, nous produisons deux fois notre consommation et l’excédent augmente de 2 à 3 millions de tonnes chaque année. Les nouveaux débouchés envisageables en alimentation sont très limités. Or le prix du blé en fait une matière première de plus en plus compétitive pour l’industrie que se soient les industries traditionnelles comme l’amidonnerie ou de nouvelles transformations, comme la distillation en éthanol. L’installation d’unités d’éthanol dans des zones où une partie des terres serait réservée à des cultures énergétiques, permettrait de maintenir les surfaces céréalières de l’Europe. Diverses cultures énergétiques telles que les taillis à courte rotation, peuvent être envisagées mais d’ores et déjà de nombreux sous-produits des exploitations agricoles et du milieu rural, peuvent être mieux valorisés pour réduire les coûts de production et procurer de nouvelles ressources aux agriculteurs. La valorisation de la biomasse est un enjeu essentiel pour notre agriculture de demain. Elle peut contribuer à lui donner un nouveau souffle. Nous sommes à l’heure des choix: – soit un développement des débouchés et le maintien de l’outil de production; – soit une extension des friches dans certaines régions d’Europe avec les problèmes d’entretien et d’aménagement du territoire qui pourraient en dé-couler. Si ce choix est primordial pour les agriculteurs, il concerne aussi l’ensemble du milieu rural et des citoyens européens. En effet:

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le développement de nouveaux débouchés et la valorisation de la biomasse en particulier est un facteur favorable au maintien de l’emploi dans les exploitations agricoles et dans l’agro-industrie et au maintien du tissu rural. Une modification de l’utilisation des sols vers des productions dont les débouchés existent, induirait des économies importantes dans les dé-penses d’intervention du F.E.O.G.A. La production d’énergies à partir des biomasses agricoles et forestières permettrait des économies de devises: 10% de carburants substitués représentent en devises 5 milliards de francs. Il m’apparait donc qu’une mobilisation de tous: agriculteurs, industriels, chercheurs, agents de développement, sera déterminante. Je sais que vous êtes nombreux à travailler depuis plusieurs années avec enthousiasme afin de faire progresser les connaissances scientifiques et mieux maîtriser les techniques dans ce domaine. Pour diverses filières, nous en sommes à une possible étape de développement grâce aux travaux que vous avez menés et en raison de la situation économique et sociale actuelle. Cette nouvelle étape, nous devons la réaliser et la réussir ensemble: . démontrer que le choix de productions non alimentaires, et surtout de productions énergétiques sur les surfaces agricoles est un bon choix; . mettre en place les filières énergétiques en gardant leur maîtrise technique et économique afin de préserver l’environnement et la fertilité des sols en particulier; . travailler ensemble à vaincre les résistances. Il est bien évident que la décision du 31 mars 1984 de fixer des quotas laitiers, a été ressentie par les agriculteurs comme un véritable signal d’alarme. Les mesures en préparation en matière de distillation obligatoire pour le vin ainsi que la fixation d’objectifs de production pour les céréales, obligent l’agriculture européenne à voir au delà des débouchés traditionnels. L’agriculture européenne qui s’est développée durant les dernières décennies, en produisant toujours davantage, ne peut pas changer brutalement son rythme, d’où la nécessité de trouver des débouchés nouveaux. La filière biomasse doit constituer un des maillons nouveaux de la P.A.C.

THE COMMON AGRICULTURAL POLICY AND BIOMASS ENERGY John SCULLY Directorate-General for Agriculture Commission of the European Communities Throughout history biomass has been used by man to provide energy, either directly by the combustion of fuelwood or indirectly by animal traction. Industrial development in the 18th and 19th centuries depended principally on the use of fuelwood. In the 20th century, the use of fossil resources came to the fore. It seemed likely that man would break away from the use of biomass. But the successive crises of the 70s showed that fossil energy resources were not unlimited and that an alternative had to be found. Attention was once again focussed on agricultural and forest biomass. But, compared with previous uses of biomass, some major changes were introduced in the conversion processes and techniques. It is now ten years since biomass conversion processes have been a subject of research and the Commission of the European Communities has been funding studies and demonstration projects in this area. The main impetus has come form two Directorates-General: the Directorate-General for Science, Research and Development (DG XII) and the Directorate-General for Energy (DG XVII). I would like to congratulate them for the work they have done. Other Directorates-General have been involved as well, especially the Directorate-General for Environment, which has funded research on anaerobic digestion, in the context of dépollution and the Directorate-General for Regional Policy, which has been studying prospects for short-rotation coppicing in less-favoured areas of the Community. In 1984, the Directorate-General for Agriculture (DG VI), which I am representing at this Congress, also launched a research programme on the subject. The conversion of biomass to energy thus has a long history as well as contemporary relevance. Recent developments fall into three phases: – the first phase ran from 1975 to 1979, when pioneering work consisted in identifying the problems and exploring the main fields of interest. – the second phase, which ran from 1979 to 1983, witnessed the proliferation of ideas and the first results. The media seized on the promises and brought them to public’s attention. This was a difficult but enriching period. The difficulties stemmed from the fact that the widespread publicity raised high hopes among policy-makers in agriculture and other branches of the economy. – the third phase is the present one. Things have quietened down, research findings are being analysed with more calmness of mind and new projects are being launched. The Directorate-General for Agriculture has taken the opportunity to launch a programme

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of research on biomass conversion to energy. And it has the benefit of previous experience from which a number of lessons can be drawn. 1)—The problems presented by fossil fuel supplies seem to be less crucial today than some years previously. But resources are undeniably limited. Furthermore, price forecasts for conventional fuel in the long term (to the year 2000–2030) point to a significant increase in fuel prices. There is even some talk of 80 dollars a barrel. So oil prices will eventually be extremely high and research must be geared to finding alternatives in the long term. Time must be taken to identify more clearly the areas where biomass can compete with fossil fuels. The main solid fuel is coal; among the liquid fuels, there is methanol derived from coal or bituminous schists. Ethanol was initially regarded as a possible aternative fuel but is today regarded as an additive. It is a molecule which should eliminate lead. In this case, agricultural ethanol could compete with ethanol from oil. This is the most valid case for comparison and should be carefully analysed. For applications in 1990, emphasis must be placed on processes which will be ready for development in the short term. For applications in the year 2030, research can be continued in the laboratory without too much concern for immediate economic profitability, although this must be tackled in the medium term. 2)—There has already been a number of scientific publications on the conversion of biomass to energy and significant results have been obtained. When shortages seemed imminent, inventions proliferated but real innovation was less common. Inventions did not reach the stage of development and application in economic life. Except in rare cases, new technologies were not competitive. Well-conceived technologies failed to reach the development stage. For instance, straw combustion in France was developed very little or not at all, even in areas where straw was in plentiful supply. The reason seems to be that the stakes are too small for the parties concerned and they are reluctant to take risks. Conversion of biomass to energy remains a matter for the scientists and engineers. Economic aspects have received little attention and often prove insurmountable when full-scale applications are envisaged. There is one exception, namely dry residues used on the farm or in the wood industry (straw, wood wastes etc.) on a sub-commercial level, i.e. without passing through normal market channels. For wet feedstocks, anaerobic digestion may be of interest in some cases. The process consists in methane production from wastes with a low dry-matter content (3–10%) in cases where there is a demand for biogas coupled with a need for pollution control. The case arises mainly in factory farming, particularly pig units of more than 5.000 animals. The cost is still high for the user but lower than aerobic depollution. The countries most concerned are naturally those where pollution problems are acute and where the government regulations are very strict. But governmental attitudes vary considerably from one member country to another: the matter is subject to few rules in the countries of Southern Europe and very stringent rules in those of the North.

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The fact that in some countries there has been remarkable progress in certain technologies (straw in Denmark, wood in the Scandinavian countries) confirms that we must continue to attach importance to this work. 3)—It is important to be more realistic in our approach. The present situation must be analysed more carefully. Converting biomass to energy is a vulnerable activity except where the producer is also the consumer. Otherwise, the hazards are many: prices can drop, oil producers can change their tactics, and so on. Given the complex physical and chemical composition of biomass, there are undoubtedly several different conversion processes which could well be competitive. For instance, conversion to feedingstuffs (treatment of cellulose and lignin), industrial or chemical feedstocks (chemical treatment of cellulose and lignin) and energy (production of alcohol for use as a fuel additive, in particular) are all worthy of attention. Similar treatment is reserved for starch, which is processed for its nutritional properties in the agricultural and food industries, is converted into glue for industrial use, and may be converted into ethanol for energy purposes. This approach calls for measures in several different fields (scientific, industrial and economic). Measures are also needed at political level. The situation in this respect needs some clarification. Starch for use in food is subsidized under the common agricultural policy. Starch for non-food uses is not subsidized. It is therefore subject to competition from starch produced outside the Community. This raises the question of whether the Community should organize the markets for agricultural products for non-food uses. The question of whether the biomass market should be organized at Community level should be studied. It is against this background of unanswered questions that the research programme of the Directorate-General for Agriculture is being implemented. At this point I would like to outline its scope and contents. First, the cost: we have 8.500.000 ECU for energy research between 1984 and 1988. Perhaps you think this is very little. If I tell you that the total budget for agricultural research in the same period is 30 million Ecu, you will see that more than one-third is reserved for energy research although there are seven other programmes to be run. As regards content, the programme concerns itself with two aspects of energy— energy saving and energy production. We have ten working groups which have issued or will be issuing invitations to tender. The subjects are as follows: I.—integrated crop protection, for which contracts were awarded in December 1984; II.—fertilization, symbiotic nitrogen fixation, for which the invitation to tender was launched in February 1985; III.—breeding of new crops with low energy inputs, for which subjects are being researched in preparation for the invitation to tender; IV.—energy saving in glasshouses, which has been the subject of research for many years and will continue as a subject for coordinated research in the future, i.e. exchanges of scientists between EEC countries;

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V.—optimization of agricultural machinery, to be a subject for coordinated research activities; VI.—development of integrated agricultural systems, also a subject for coordinated research; VII.—energy production and energy crops: work is in hand to prepare the invitation to tender. The projects will be financed directly; VIII.—conversion of dry agricultural residues, such as straw, walnut shells, wood, as a subject of coordinated research; IX.—advisory services to farmers, with the making of a film and advisory brochures: the invitation to tender is planned for the end of 1985; X.—economic aspects, which are being studied with a view to an invitation to tender towards the end of 1985; This is the general picture of our research programme. There is still room for discussions and proposals to the officials in charge of the programme in the Directorate-General for Agriculture, whom you are invited to consult for any further information. In conclusion, it seems clear that the conversion of biomass to energy is not something very new. On the basis of previous and present experience, we can plan our work for the immediate and more distant future, for which the targets of research and application will be different. It also seems clear that, despite economic problems, interest in the subject is still significant although certain factors are taking on new importance. In the case of environment, priorities in Northern and Southern Europe diverge or even conflict with each. The importance of linking up with agricultural policies and industrial policies is indisputable. For the developing countries, which we have not mentioned until now, ideas are already being formulated and it is important to take part. Some projects are under way at the initiative of the Directorate-General for Development (DG VIII). Attention is focused in particular on the economical use of biomass, limited consumption of fuelwood, introduction of new types of cooking appliance, and so on. But, for the developing countries where biomass is already used in large quantities for energy, there are plans to replant trees in village areas to prevent desertification. For this part of the world, the problem is more complex than it seems and much work remains to be done. My concluding words, as far as Europe is concerned, may seem rather severe but nonetheless realistic. It is important not to be too hasty in evaluating ambitious projects, but rather to wait until techniques are properly operational and economic viability is assured.

KURZFRISTIGE VERFÜGBARKEIT VON FORSTLICHER BIOMASSE IN DER BUNDESREPUBLIK DEUTSCHLAND A.F.WEISMANN Ministerialrat und Beauftragter für nachwachsende Rohstoffe im Bundesministerium für Ernährung, Landwirtschaft und Forsten, Bonn ZUSAMMENFASSUNG: Die Entwicklung der Energiemärkte seit 1973 und die agrarische Überschuß-Produktion in der EG führten zur Frage nach Nutzungsalternativen. Die Erwartungen richten sich auf die verstärkte Verwendung der Stoffgruppen Stärke, Zucker, Öle/Fette außerhalb des Food-Sektors. Auch die Erschließung der Potentiale von Lignocellulose könnte angesichts des geringen Selbstversorgungsgrades bei Holz für bessere Nutzung der Ressourcen beitragen. Es folgt die Darstellung der Ausgangssituation und Rahmenbedingungen einschließlich der Risiken, die aus den neuartigen Waldschäden resultieren. Anschließend werden die nutzbaren Potentiale forstlicher Biomasse mit Hinweisen auf die Wett-bewerbsfähigkeit von Wald-Restholz quantifiziert. Als zusätzliche Quelle wird der Anbau schnellwachsender Baumarten in der Feldflur und auf Waldflächen diskutiert; das Potential könnte mittelfristig an das Aufkommen von Industrierestholz heranreichen. Das Fazit hebt hervor, daß die Probleme auf den Agrarmärkten keinen Aufschub dulden und Lignocellulose in den etablierten Verwendungsbereichen ohne Konkurrenz für agrarische Rohstoffe eingesetzt werden kann. Land- und Forstwirtschaft bedürfen bei ihren Anstrengungen der weiteren Untersetzung durch verstärkte Förderung von Forschung und Entwicklung sowie durch Anpassung der Rahmenbedingungen, wenn die Entwicklung in der EG nicht Schaden nehmen soll. I. EINFÜHRUNG Von Wald und Holz in der Bundesrepublik Deutschland soll die Rede sein; beide Begriffe sind in der deutschen Sprache einsilbige Wörter und Bezeichnungen für Naturphänomene, die auch heute noch voller Wunder und Rätsel sind, und zwar trotz des Gebrauchs durch die Menschen seit Beginn ihrer Geschichte sowie trotz intensiver Erforschung während der letzten Jahrhunderte. Dagegen ist das Them praktisch, nüchtern, nicht von gleicher Faszination wie das Naturphänomen Wald, aber mit Risiken und Unwägbarkeiten behaftet. Die bekannte Entwicklung auf den Energiemärkten seit der 1. Hälfte der 70er Jahre und die wachsende Überschuß-Problematik auf den wichtigen Agrarmärkten der

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Europäischen Gemeinschaft haben die Frage nach Nutzungsalternativen außerhalb des Food-Bereiches in das politische Rampenlicht gerückt. Die Erwartungen der politisch Verantwortlichen, ferner der um ihre Existenz besorgten Landwirte und Waldbesitzer sind groß und hochgespannt; kaum geringer sind aber auch die Schwierigkeiten, die Wettbewerbskraft nachwachsender Rohstoffe für geeignete Produktlinien durch Züchtung, durch Optimierung der Bereitstellung und Konversionsverfahren in der gebotenen Zeit so zu verbessern, daß ausgewählte Nutzungsmöglichkeiten in die Praxis umgesetzt werden können. Hoffnungen verbinden sich nicht nur mit den Stoffgruppen Stärke, Zucker, pflanzlichen Ölen und Fetten, sondern auch mit den Lignocellulosen und ihren Komponenten Cellulose, Hemicellulose und Lignin. Die Ausführungen beschränken sich auf Holz, auch wenn das in den landwirtschaftlichen Betrieben nicht benötigte Stroh in einer Menge von ca. 5 Mill. t jährlich ein beachtliches Potential an technisch verwertbarer Cellulose darstellt. Die weitere Einschränkung auf die in der Bundesrepublik Deutschland kurzfristig verfügbare Holz-Biomasse wirft die naheliegende Frage nach den weltweiten Relationen und der Aussagekraft der Betrachtungen auf. Wenn von der gesamten Waldfläche der Erde mit ca. 4, 1 Mrd. Hektar (ha) nur 0,85% auf die Europäische Gemeinschaft entfallen und die Waldfläche in der Bundesrepublik nur etwa 22% der Waldfläche in der EG der 10 Staaten ausmacht, so können Sie die bescheidene Größe des hier in Frage stehenden Mosaiksteinchens aus globaler Sicht ermessen. Aus der Nähe unter einem anderen Blickwinkel betrachtet, stellt sich die Bedeutung anders dar: – In der stark mittelständisch geprägten Holzwirtschaft der Bundesrepublik Deutschland sind gegenwärtig 680.000 Mitarbeiter beschäftigt. Dieser Bereich erzielte 1983 einen Umsatz von über 92 Mrd. DM. Nicht mitgerechnet ist der Produktionswert der Forstwirtschaft, der rund 3 Mrd. DM ausmachte und von etwa 100.000 festen Beschäftigten und einer vielfachen Anzahl von Saisonarbeitskräften erzielt wurde. Einschließlich der Angehörigen der Beschäftigten gründet sich die unmittelbare Existenz einiger Millionen Menschen auf die Tätigkeit der beiden Sektoren. – Voraussetzungen dafür sind die Rohstoff- und Warenströme, wie sie sich in der nachstehenden Übersicht “Bilanz für Holz und Waren auf der Basis Holz in Rohholzäquivalenten” niederschlagen: 1982 1983 Bilanzposten Mio. m3 Erzeugung (Einschlag) Wiederverwendung von Altpapier (a.d. Inland) Einfuhr Bezüge aus der DDR Ausfuhr Lieferungen in die DDR Bestandsveränderung Inlandsverwendung Selbstversorgungsgrad einschließlich Altpapier a.d. Inland

28,9 27,5 9,9 10,3 43,8 48,5 1,7 2,0 23,4 24,5 0,2 0,2 0,9 0,3 61,6 63,9 in % 63,0 59,2

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Die Datenübersicht spiegelt die potentiellen Nutzungsmöglich-keiten für forstliche Biomasse aber nur unvollständig wieder; darauf wird noch näher einzugehen sein. II. AUSGANGSSITUATION, RAHMENBEDINGUNGEN Vorweg scheint es zweckmäßig, einige Rahmenbedingungen zu skizzieren, nämlich: 1. die Position des Waldes in der Rechtsordnung; 2. Elemente der Forststruktur sowie Merkmle der Waldnutzung und Holzverwendung; 3. natürliche Kalamitäten und neuartige Waldschäden als ökologische und ökonomische Störfaktoren; 4. strukturelle Überschüsse auf wichtigen EG-Agrarmärkten; Konsequenzen? Ad 1): Welche ökologischen und ökonomischen Funktionen werden vom Wald in der Rechtsordnung erwartet? Teilnehmer und Interessenten, die nicht aus dem deutschen Sprachraum kommen, werden nicht so ohne weiteres mit den Rechtsnormen vertraut sein, die sich in Mitteleuropa seit Beginn einer planmäßigen Forstwirtschaft für den Wald als Ökosystem und Rechtsobjekt, aber auch für die Waldeigentümer in zunehmend strengerer Ausprägung ergeben haben. Sowohl das Bundeswaldgesetz von 1975 als auch die Forstgesetze der Länder bestimmen unter anderem: 1.1 Der Wald ist wegen seines wirtschaftlichen Nutzens und wegen seiner Bedeutung für die Umwelt, insbesondere für die dauernde Leistungsfähigkeit des Naturhaushaltes, für das Klima, den Wasserhaushalt, die Bodenfruchtbarkeit, die Agrar- und Infrastruktur und für die Erholung der Bevölkerung zu erhalten, erforderlichenfalls zu mehren. 1.2 Die ordnungsgemäße Bewirtschaftung des Waldes ist nachhaltig zu sichern. 1.3 Es bedarf des Ausgleichs zwischen dem Interesse der Allgemeinheit und den Belangen der Waldbesitzer. 1.4 Die gesetzlich verankerten Funktionen des Waldes sind von den Behörden bei allen Planungen und Maßnahmen angemessen zu berücksichtigen, sofern diese eine Inanspruchnahme von Waldflächen vorsehen oder in ihren Auswirkungen Waldflächen betreffen können. 1.5 Wald darf nur mit behördlicher Genehmigung gerodet oder in eine andere Nutzungsart umgewandelt werden. 1.6 Die Waldbesitzer sind verpflichtet, kahlgeschlagene Waldflächen oder verlichtete Waldbestände wieder aufzuforsten oder die Be-stockung zu ergänzen. 1.7 Wald kann mit weitergehenden Auflagen zu Schutzwald erklärt werden, wenn es zur Abwehr oder Verhütung von Gefahren erforderlich ist. Anders ausgedrückt: Raubbau am Wald ist im Allgemeininteresse untersagt. Neben den ökonomischen Funktionen kommt den ökologischen Funktionen ein hoher Rang zu. Das die Bewirtschaftung des Waldes dominierende und von den Waldbesitzern längst akzeptierte Prinzip der “Nachhaltigkeit” führt im Ergebnis dazu, daß die planmäßige Nutzung den Zuwachs an Holz nicht überschreiten darf und daß die Waldflächen nicht beliebig einer anderen Nutzungsart zugeführt werden können.

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Ad 2): Elemente der Forst- und Agrarstruktur sowie Merkmle der Waldnutzung und Holzverwendung Der Waldanteil an der Fläche des Bundesgebietes beträgt 29,5%, d.s. über 7,3 Mill. ha; davon sind 31% mit Laubholz und 69% mit Nadelholz bestockt. Eigentumsverteilung: 56% Bund, Länder, Gemeinden, öffentl. Anstalten und Stiftungen; 44% Private. Zahl der Betriebe mit Wald: 473.000 (ohne 0,44 Mill. ha Waldfläche <1 ha), davon 372.000 landwirtschaftliche Betriebe mit 23,5% der Waldfläche und 101.000 Forstbetriebe mit 76,5% des Waldes. Daraus erhellt dreierlei: 2.1 Die starke betriebliche Verflechtung von Land- und Forstwirtschaft bei etwa der Hälfte der landwirtschaftlichen Betriebe mit durchschnittlich geringer Flächengröße des zugehörigen Waldes (4,40 ha). Dieser Sachverhalt legt nahe, eine lokale und regionale überbetriebliche Kooperation—ohne Verlust des Eigentums und der Dispositionsgewalt—in Forstlichen Zusammenschlüssen zu suchen. Nach einer älteren Zählung haben sich vor Jahren über 150.000 Waldbesitzer mit mehr als 1,5 Mill. ha Wald zu Kooperationen zusammengeschlossen. 2.2 Die durchschnittliche Flächenausstattung ist bei den Forstbetrieben mit 51,8 ha erheblich größer; dabei ist zu berücksichtigen, daß die Größenklasse über 1000 ha mit über 1000 Betrieben vertreten ist (bei den landw. Betrieben sind es nur 18). Eine ähnliche Relation besteht in der Größenklasse darunter mit 200–1000 ha. 2.3 In beiden Hauptproduktionsrichtungen dominieren der Zahl nach die Betriebe mit Wald unter 20 ha. Diese kleinteilige Struktur ist sozioökonomisch sicherlich vorteilhaft, läßt aber wegen der lokalen Gemengelage der verschiedenen Besitzgrößen eine optimale Waldbewirtschaftung nicht zu. Das Aufkommen an Rohholz aus dem Inland—bereits in der ersten Übersicht eingangs erwähnt—beträgt im mehrjährigen Durchschnitt knapp 29 Mill. m3 ohne Rinde. Nebenbei bemerkt: Das bei der Be- und Verarbeitung anfallende Industrierestholz wird nahezu vollständig als Rohstoff oder energetisch genutzt; seine Menge ist mit 30–35% des Rohholzaufkommens eine ökonomisch interessante Größe. Der Selbstversorgungsgrad bei Holz, d.h. eigene Erzeugung in % des inländischen Verbrauchs an Holz und Holzprodukten, beträgt rund 47%; einschließlich AltpapierRecycling 63%. Überschüsse wie auf den Agrarmärkten sind also nicht zu erwarten. Die Abhängigkeit der Bundesrepublik Deutschland von Importen im Bereich Rohholz und bei ausgewählten Produkten auf der Basis Holz ist entsprechend groß. So beträgt die Netto-Importquote, d.h. Netto-Inport in % der im Inland verfügbaren Mengen, z.B. bei – Papierzellstoff rund 79% –Sperrholz rund 55% – Holzschliff knapp 5% –Furniere rund 17% – Papier und Pappe rund 16% –Faserplatten rund 37% – Schnittholz und Schwellen 28% –Spanplatten nur 4%

Die beispielhaften Daten und die vorerwähnten Sachverhalte verdeutlichen skizzenhaft – die Produktionsstrukturen der Forstwirtschaft, aber auch der Holzwirtschaft; – die starke Importabhängigkeit bei Holz und Holzerzeugnissen.

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Diese Hinweise ergeben bestenfalls eine unscharfe Momentaufnahme. Alle genannten Elemente müssen aber auch in ihrer zeitlichen Dimension und Wechselwirkung gesehen werden, um falsche Schlußfolgerungen zu vermeiden. Ad 3): Natürliche Kalamitäten und neuartige Waldschäden als ökologische und ökonomische Störfaktoren Naturkatastrophen und weniger elementare natürliche Kalamitäten beeinträchtigen die Wälder und deren Nutzung seit Menschengedenken immer wieder auf’s Neue. Das ist keine nationale Spezialität, ebensowenig wie die seit Jahren deutlicher in Erscheinung tretenden neuartigen Waldschäden, die nach überwiegender Auffassung primär durch zu hohe Schadstoffimmissionen ausgelöst werden und auch in anderen Ländern Europas noch unübersehbare Gefahren hervorrufen. Durch Wind und Sturm verursachter Anfall von Holz in großen Mengen—so z.B. in den 70er Jahren über 14. Mill. m3 in einem Jahr oder 1984 über 9 Mill. m3—schädigt anhaltend den Waldaufbau und stört die Märkte. Außerdem gefährden die neuartigen Waldschäden (50% der Waldfläche sind+betroffen) zunehmend eine nachhaltige Produktion sowie die gleichmäßige Belieferung der Holzwirtschaft. Für die Arbeitsplätze zeichnen sich Risiken ab, wenn es nicht gelingen sollte, z.B. durch den Anbau schnellwachsender Baumarten Einbußen zu mildern. Die ökologische und ökonomische Brisanz des Prozesses wird im politischen Raum nach meiner Einschätzung vielfach noch nicht im vollen Ausmaße erkannt. Ad 4): Zur Überschuß-Situation auf wichtigen Agrarmärkten der EG-Konseguenzen? Strukturelle Überschüsse auf EG-Agrarmärkten erfordern kurz- und mittelfristig ökonomisch und ökologisch akzeptable Alternativen der Nutzung landwirtschaftlicher Böden. Eine spürbare Reduktion der gesamtwirtschaftlichen Kosten zur Beseitigung der Überschüsse wird nur durch ein Bündel von Maßnahmen gemeinschaftlich zu erreichen sein. Die Verwendung von Agrarprodukten für Energieträger und industrielle Grundstoffe kann in einigen Jahren einen Beitrag dazu leisten. Auch der Anbau schnellwachsender Baumarten kommt dafür in Frage. III. NUTZBARE POTENTIALE FORSTLICHER BIOMASSE Nach der Skizzierung der Ausgangssituation und wesentlicher Rahmenbedingungen lautet die Frage: Welche Arten von forstlicher Biomasse könnten mit welchen Potentialen kurzfristig verfügbar sein und wie konkurrieren sie hinsichtlich der verschiedenen Verwendungsmöglichkeiten als Rohstoff oder als Energieträger miteinander? Es soll hier zunächst von Restholz die Rede sein, also von jenem Anteil des Rohstoffes Holz, der in den verschiedenen Be- und Verarbeitungsstufen, d.h. von der Holzernte bis zur Herstellung der Produkte, anfällt. Außerhalb der Betrachtung bleiben noch ungenutzte Mengen von Altpapier und Reststroh aus dem Getreideanbau. Demnach geht es um folgende Reststoff-Arten:

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1. Industrierestholz; 2. Altholz aus Recycling; 3. Waldrestholz. Als eine zusätzliche Quelle steht zur Diskussion: 4. Holz aus dem Anbau schnellwachsender Baumarten. Ad 1): Industrierestholz (IR) Sägerestholz+Verarbeitungsabfälle gelten als preiswerte Rohstoffe mit festen Absatzwegen und werden zum geringeren Teil als Energieträger genutzt. Obgleich freiwerdende Mengen nicht in Sicht sind, bedarf IR wegen seiner preislichen Schlüsselfunktion der Berücksichtigung. Ad 2): Altholz aus Recycling Das Potential wird auf knapp 1 Mill. t pro Jahr geschätzt; der Markt nimmt aber bisher nur da. 0,15 Mill. t auf. Ad 3): Waldrestholz (WR) Die Ernterückstände betragen knapp die Hälfte eines Baumes. Dazu kommen noch aus Pflegeeingriffen ganze ungenutzte Bäume. Das nutzbare Potential wird auf 4 Mill. t atro pro Jahr geschätzt. Weitere 3,5 Mill. t pro Jahr wären bei Durchforstungen als Schwachholz verfügbar. Ein Markt fehlt noch. Eine Mobilisierung, z.B. in Form von Hackschnitzeln (HS), scheiterte bisher an den relativ hohen Kosten. Die Verwendung beschränkt sich bisher local auf energetische Nutzung. Nur Rohstoffengpässe könnten bei gegenwärtigem Kosten-Niveau für WR den Markt öffnen. Ad 4): Holz schnellwachsender Baumarten Die Möglichkeiten, durch den Anbau schnellwachsender Baumarten ein zusätzliches Potential zu gewinnen, werden in Europa und Amerika seit Jahrzehnten erforscht und erprobt, und zwar vornehmlich als Alternative zur landwirtschaftlichen Nutzung von “Grenzertragsböden” (marginale Böden). Die Potentiale und Verfügbarkeit des Materials sind noch ungewiß. Geht man aber davon aus, daß a) in den nächsten Jahren zunehmend landwirtschaftliche Flächen nicht mehr für die Food-Produktion verwendet werden können—die Berechnungen ergeben für Deutschland mittelfristig bis zu 1,2 Mill. ha (=10%), für die EG (10) ein Vielfaches dieser Zahl—, b) nach 1990 z.B. 500.000 ha für die Anpflanzung schnellwachsender Baumarten zur Verfügung stehen, so könnte bei einer Biomasse-Produktion von 12 t atro pro Jahr und ha ein Potential von 6 Mill. t atro/a zusätzlich verfügbar werden. Zum Vergleich: Eine solche Menge würde in der Größenordnung dem gesamten Industrierestholz nahekommen. Schnellwachsende Baumarten können 1. im Kurzumtrieb oder 2. im mittleren Umtrieb bewirtschaftet werden. Für den Kurzumtrieb zeigen erste Ergebnisse und Kalkulationen, daß die preisliche Wettbewerbsfähigkeit der gewinnbaren Hackschnitzel gegenüber IR oder anderen

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Energieträgern nicht höchste Massenerträge voraussetzt. Es ist vielmehr nötig, die Gesamtkosten zu optimieren. Die Optimierung der In-/Output-Relation wird auch darüber entscheiden, ob eine solche Landnutzung gegenüber bestimmten landwirtschaftlichen Nutzungsarten wettbewerbsfähig sein kann, vorausgesetzt, daß man in Bezug auf Subventionen nicht ungleich verfährt. Mittlere Umtriebszeiten für schnellwachsende Baumarten dürften zu einer Senkung der Produktionskosten je Einheit führen und die Palette der Verwendungsmöglichkeiten vergrößern, z.B. für die Produktion von Zellstoff. Modellrechnungen zeigen, daß bei teilweiser Umwidmung von EG-MarktordnungsAusgaben die Erzeugung von Industrieholz als Alternative zur bisherigen Flächennutzung für den Food-Sektor in Betracht kommt. Diese Möglichkeit, die Holzerzeugung innerhalb kürzerer Zeiträume zu steigern, würde bei engagiertem Vorgehen die Basis für die Produktion von vielseitig verwendbaren industriellen Rohstoffen verbreitern. Dies könnte auch dazu beitragen, entsprechende Produktions-stätten zu erhalten oder new zu schaffen. Das Flächenpotential ist angesichts der Agrarmarkt-Überschüsse in der EG vorhanden. Der Anbau schnellwachsender Baumarten, wie z.B. Aspen, Birken, Roteichen, und die Bewirtschaftung im mittleren Umtrieb in der Feldflur und auf Waldflächen wird aus zwei Gründen zu überdenken sein. Erstens: Wenn die neuartigen Waldschäden weiter zunehmen und dadurch bedingter Mehranfall an Waldholz als Vorgriff auf zukünftige Nutzungen die spätere Belieferung der Industrie reduziert, könnten Erträge aus solchen Anbauten helfen, teilweise auszugleichen. Zweitens: Sollten schadensbedingte Kahlflächen im Wald unvermeidlich werden, könnte der Anbau einen ökonomisch und waldbaulich interessanten Vorwald für die reguläre Wiederaufforstung ergeben. Die Natur hat nach der Eiszeit in Europa das Vorbild bei der natürlichen Ausbreitung des Waldes geliefert. IV. FAZIT 1. Die Probleme auf den Agrarmärkten der EG dulden keinen Aufschub. Abhilfe darf nicht nur innerhalb des Agrarsektors gesucht werden. Die alternative Flächennutzung durch annuelle Rohstoffpflanzen der Stoffgruppen Zucker, Stärke, Öle/Fette stößt bei der Züchtung, bei der Bereitstellung, bei der Konversion zu marktfähigen Produkten und bei deren Einführung in den Markt auf kaum geringere Schwierigkeiten als der Anbau und die Verwertung forstlicher Biomasse. 2. Lignocellulose könnte in industriell bereits etablierten Verwendungsbereichen eingesetzt werden und den Selbstversorgungsgrad zu Gunsten der volkswirtschaftlichen Bilanz erhöhen. Den landwirtschaftlichen Rohstoffpflanzen würde zusätzliche forstliche Biomasse keine Konkurrenz auf den Produktenmärkten bereiten. 3. Die Schwestern der Urproduktion—Land- und Forstwirtschaft—sind aufgerufen, zur Bewältigung ihrer drängenden Probleme die erforderlichen Anstrengungen unverzüglich zu unternehmen. Dazu bedarf es auch der Kooperation mit den verschiedenen Industriesektoren.

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4. Auf der Ebene der Gemeinschaft und national muß die Politik die Forschung und Entwicklung weiterhin fördern und gezielt vorwärtstreiben. Außerdem müssen die Rahmenbedingungen in der Agrarpolitik und in anderen Politikbereichen unverzüglich Schritt für Schritt an die Erfordernisse angepaßt werden. Die Europäische Gemeinschaft muß sich auch auf diesem Feld bewähren, sonst werden das Vertrauen der Bürger und die Entwicklung der Gemeinschaft Schaden nehmen. Ich schließe mit einem Zitat von Ernst Curtius: “Ohne den Unsterblichkeitsgedanken wären wir nichts als armselige Tagelöhner, durch ihn erhält alles, was wir beginnen, Bedeutung und Zusammenhang.”

LA BIOMASSE, SOURCE DE SUBSTITUTS AU PETROLE DANS LE SECTEUR DES TRANSPORTS P.LEPRINCE et J.P.ARLIE Institut Français du Pétrole RESUME Les analyses de conjoncture mettent toutes l’accent sur l’importance des transports dans le développement futur du monde. Ce sec-teur a connu en moins d’un siècle une expansion rapide grâce aux qualités exceptionnelles des hydrocarbures pétroliers, à leur faible coût de production et à l’abondance des réserves en place. On peut cependant s’interroger sur leur remplacement pour deux raisons: – la première est économique: le nouveau pétrole est de plus en plus coûteux à extraire, – la seconde est stratégique: dans tous les pays les transports sont un secteur vital pour l’approvisionnement duquel il peut être judicieux de faire appel aux ressources nationales. L’exposé se propose d’examiner au plan technique et économique l’aptitude des produits de la biomasse à se substituer au pétrole. Les aspects suivants seront étudiés: qualités des produits, ressources, implantation des installations, scénarios de pénétration, évolution de la compétitivité économique par rapport au pétrole. En conclusion, on présente les orientations possibles de la recherche et du développement, principalement en ce qui concerne les nouvelles technologies et leur impact.

1. INTRODUCTION Depuis 1973, date de la première crise pétrolière, la situation énergétique du monde s’est transformée: diminution de la demande, croissance de l’offre, développement de nouvelles énergies. Dans beaucoup de secteurs, la consommation énergétique a été profondément transformée par les nouvelles techniques économisant l’énergie ou par l’apparition de nouvelles sources d’énergie. Le secteur des transports est resté plus stable: les nouvelles sources d’énergie pour la propulsion des moteurs, comme l’hydrogène ou l’électricité, n’ont pas réussi à s’imposer et ne semblent pas en mesure de déplacer les carburants liquides, à haute densité énergétique. Ce secteur, dépendant aujourd’hui en quasi totalité des hydrocarbures liquides, est ainsi particulièrement sensible à la situation pétrolière mondiale qui se modifie dans ses

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données économiques et stratégiques par la découverte et la mise en exploitation de nouveaux gisements. Dans cette conjoncture il peut être décisif de recourir à de nouveaux types de carburants et en particulier à ceux qui proviennent de la biomasse. 2. L’IMPORTANCE ECONOMIQUE ET SOCIALE DU SECTEUR DES TRANSPORTS ROUTIERS Dans la CEE, le chiffre d’affaires total du secteur des transports peut être estimé à 170 milliards de dollars: 2/3 correspondent à la production des automobiles et 1/3 au transport des marchandises et des personnes. Les effectifs travaillant dans l’orbite de l’automobile re-présentent 9,0 millions de personnes dont 2,4 liés directement aux activités de production, 2,2 millions aux usages de l’automobile (réparation, entretien) et 4,4 aux transports publics et privés et aux activités annexes (routes, parking, location de véhicules, éditions et presse spécialisées). Ainsi, dans la CEE, une personne active sur 12 vit de l’automobile. 3. L’ENJEU DE LA SUBSTITUTION Aujourd’ hui, en Europe Occidentale, la consommation pétrolière dans le secteur des transports routiers est de 150 millions de tonnes, les 2/3 en carburants automobile et 1/3 en diesel: 80% du carburant auto est utilisé par les voitures particulières, 55% du gazole dans les camions pour le transport des marchandises. (Tableau I) A la fin du siècle, la consommation européenne de carburant auto devrait se stabiliser autour de 100 millions de tonnes par une compensation entre l’accroissement du nombre de véhicules en circulation et la moindre consommation au kilomètre des nouveaux moteurs. Au contraire, l’accroissement des transports de marchandise par la route et une progression de la dieselisation du parc de voitures particulières, devraient conduire à une croissance de la consommation de gazole jusqu’à environ 80 millions de tonnes/an. Au vu de l’importance des besoins, il est aisé de voir que la substitution ne peut être que partielle, en particulier si on fait appel à la biomasse dont on ne peut tirer en moyenne que 2 tonnes d’équivalent pétrole par hectare et par an. Des deux solutions possibles: synthétiser des hydrocarbures ou produire de nouveaux types de carburants, la seconde convient particulièrement à la biomasse qui conduit à des produits oxygénés (méthanol, éthanol, acétone, butanol) connus pour leur haute qualité de carburant. 4. QUALITE DES PRODUITS Dans la substitution des hydrocarbures pétroliers, les composés oxygénés présentent deux caractéristiques favorables: – leurs indices d’octane (RON et HON) sont généralement supérieurs à ceux des hydrocarbures, en particulier l’indice d’octane recherche, qui dépasse 100; cette propriété est particulièrement attrayante à une époque où en Europe comme aux USA et au Japon, les alkyles de plomb sont appelés à disparaître

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– leur aptitude à brûler en mélange pauvre (excès d’air) est excellente. On peut aussi obtenir une combustion quasi complète du carburant, ce qui améliore le rendement et conduit à réduire certaines émissions de polluants (CO, NOX, HC). Ces propriétés favorables sont cependant compensées par des défauts dont l’importance varie suivant la nature de l’alcool utilisé et les conditions d’emploi en particulier avec le taux de mélange avec les hydrocarbures. . Le pouvoir calorifique des alcools est plus faible que celui des hydrocarbures; cette caractéristique a deux conséquences:—à capacité égale de réservoir l’autonomie du véhicule est réduite—un réglage particulier du carburateur est nécessaire pour ajuster la valeur du rapport air/carburant dès que la teneur en oxygène du carburant conduit à un appauvrissement trop fort du mélange carburé. Cette teneur limite est voisine de 2,5% pour les moteurs européens les plus récents. dans les produits de combustion, on observe la présence d’aldéhydes, résultat de la combustion incomplète des hydrocarbures . la tenue des matériaux métalliques et organiques utilisée dans le véhicule est différente, ce qui impose des modifications dans le choix de ces matériaux . la chaleur de vaporisation est très élevée, ce qui suppose des dispositifs spéciaux pour obtenir le mélange carburé. D’autres défauts doivent être corrigés au moment de la fabrication des carburants: . leur tension de vapeur, particulièrement élevée dans le cas du méthanol, limite l’addition des hydrocarbures légers au carburant . à basse température et en présence de traces d’eau il se forme une séparation en deux phases dont l’une est incombustible. Ce phénomène est particulièrement gênant lorsqu’on utilise le méthanol: il peut disparaître en ajoutant des alcools plus lourds, en particulier le butanol. 5. MOBILISATION DES RESSOURCES ET IMPLANTATION DES INSTALLATIONS DE PRODUCTION Les produits agricoles—sucres, amidon, cellulose—susceptibles d’être utilisés pour la fabrication de substituts au carburant sont tous transformables par des techniques de fermentation soit directe (sucres), soit après hydrolyse (amidon et cellulose). En choisissant la fermentation finale, on obtient soit l’éthanol, soit le mélange butanolacétone (MBA). Une autre opération, la gazéification des substances lignocellulosiques permet d’obtenir le méthanol. Dans le contexte économique actuel, on peut mobiliser quatre ressources principales: la betterave, les céréales (blé et maīs), les déchets de l’agriculture (paille et tiges), le bois de taillis. Chacune d’elles présente des caractéristiques spécifiques qui conditionnent leur mode d’implantation. Betteraves—certaines variétés (betteraves semi-sucrières) fournissent des rendements exceptionnels en sucre totaux fermentescibles. Les sous—produits de la sucrerie (égout de premier ou de deuxième jet) peuvent être directement soumis à la fermentation; on peut ainsi optimiser la production combinée de sucres et d’alcools. Céréales—la croissance des rendements à l’hectare, observée ces dernières années, fait apparaître un excédent de blé dans la CEE, environ 8 millions de tonnes, qui représente une ressource potentielle de 2 millions de tonnes d’éthanol ou de 1,6 million de tonnes de

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butanol-acétone (MBA). La transformation des céréales fournit des produits commercialement intéressants: drêche riche en protéines (36%) utilisable, comme les tourteaux d’oléagineux, dans l’alimentation animale ou gluten utilisable dans l’alimentation humaine. Déchets de l’agriculture—la paille de blé représente une ressource de plusieurs millions de tonnes/an mais elle trouve souvent une meilleure utilisation en combustion directe. Les tiges de maïs aujourd’ hui sans valorisation, représentent un gisement évalué pour la France à 5 millions de tonnes par an de matière sèche. Bois de taillis—La substitution de la culture traditionnelle par des taillis de peupliers ou d’eucalyptus à courte rotation (7 à 10 ans) est attractive au plan du rendement (12 tonnes de matière sèche à l’hectare) mais rencontre des difficultés importantes: compensation pour l’agriculteur de la période financièrement improductive entre la plantation et la coupe, concurrence d’autres usages (panneaux de particules, papeterie, combustion directe). Le choix de l’implantation d’une unité de production doit tenir compte de deux facteurs antagonistes. Pour diminuer les charges de capital, de main d’oeuvre et les frais généraux, on cherche à concevoir l’unité de taille maximum et à l’opérer sur la période annuelle la plus longue, mais cette tendance conduit à des dépenses croissantes de collecte et de stockage du fait de la dispersion de la ressource et du caractère saisonnier de la production. Le poids relatif de ces deux facteurs est variable suivant le procédé et suivant la nature de la matière première. Aussi dans une usine de fabrication d’éthanol ou de mélange acétone-butanol à partir de blé, le coût de la collecte et du transport du blé varie peu (tableau II) avec la capacité de l’usine. Il n’en est pas de même pour la même usine utilisant la paille de blé. qui dépend On peut mesurer cet effet en calculant la distance moyenne de collecte du rendement à l’hectare (p), du taux d’occupation (t) de la surface totale par la culture énergétique, et de la quantité (Q) de biomasse nécessaire

A titre d’exemple, on a calculé cette distance moyenne pour deux types de fabrication: l’une à partir de blé, l’autre à partir de paille pour un taux d’occupation de 0,5 correspondant à une grande région agricole européenne. (Tableau II). Ce facteur peut être déterminant dans le choix des régions à affecter à ce type de culture afin d’assurer à l’agriculteur le revenu optimum de son activité. 6. LES SCENARIOS DE SUBSTITUTION Pour tirer le meilleur parti des composés oxygénés dans la carburation, on ne considère aujoud’hui que deux types de substitution: – l’amploi d’alcools à forte concentration , dans ce cas il faut concevoir de nouveaux moteurs dont le rendement énergétique peut être accru de 11 à 15% avec le méthanol et d’environ 10% avec l’éthanol. Cet effet est dû:

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– à une augmentation du taux de compression jusqu’à 12, grâce à l’indice d’octane élevé des alcools – à la diminution de la richesse du mélange qui résulte de l’aptitude des alcools et surtout du méthanol à brûler en mélange pauvre – à une récupération de calories sur les gaz d’échappement qui assure la vaporisation du carburant oxygéné. Ces effets favorables ne peuvent être obtenus avec les mélanges alcools-hydrocarbures (15 à 50%) (fig. 1) si bien que ce mode de substitution, très largement étudié, en particulier en Suède et en Allemagne Fédérale pour le méthanol, n’est plus d’actualité. Seul le Brésil maintient la première partie de son plan Proalcool (2,2 millions de m3/an d’éthanol utilisé en mélange à 20% dans les hydrocarbures). Mais, depuis 1979, la croissance de la substitution est assurée par l’usage de l’éthanol à 95%, dont la consommation a atteint 3 millions de m en 1983. – l’emploi des alcools en faible quantité de telle sorte que l’appauvrissement du mélange carburé, dû au plus faible pouvoir calorifique des alcools, soit compatible avec le fonctionnement des moteurs actuels. Dans ces conditions, le rendement énergétique du moteur est amélioré dans une proportion qui compense la baisse du pouvoir calorifique du carburant. De la sorte, la consommation exprimée en litrespar kilomètre ne s’en trouve pas modifiée. Avec les moteurs les plus récents et, en particulier ceux qui sont munis d’un réglage de la richesse par sonde à oxygène, il n’en serait plus de même et la consommation serait accrue de la variation du pouvoir calorifique du carburant. On a évalué la surconsommation à environ 2% pour les mélanges méthanol-butanol (5%) et éthanol (7%). Ce moae de substitution est entré dans une phase concrète aux USA et en Allemagne et des dispositions réglementaires ont été prises en France ou sont en voie de l’être dans la CEE. 7. ANALYSE ECONOMIQUE DE LA SUBSTITUTION Cette analyse doit prendre en compte, d’une part la substitution en équivalent énergétique qui correspond à l’usage des alcools à forte concentration et la substitution en équivalent litre pour litre qui correspond à l’addition en faible quantité. Les caractéristiques économiques des produits susceptibles d’être utilisés sont données dans le tableau III. 7.1—Usage des alcools à forte concentration. Equivalence énergétique. La situation actuelle du marché des produits pétroliers est très loin de favoriser la substitution massive par les composés oxygénés d’origine végétale. De plus elle évolue aujourd’hui dans un sens défavorable. Il suffit pour l’apprécier d’évaluer le prix des pétroles bruts en prenant comme base la valeur du dollar au moment du premier choc pétrolier. Exprimé en $ 1973, le prix du baril a atteint environ 20 $ en 1981, alors que le pétrole atteignait sur le marché spot son plus haut niveau. Aujoud’hui exprimé dans la même unité, il est voisin de 12 $ (1973)/bbl. Dans ces conditions, la compétitivité économique des composés oxygénés s’éloigne dans le temps: on peut calculer en effet qu’il serait nécessaire que le brut atteigne en $ 1983 le niveau de 60 à 80 $/bbl pour qu’il devienne économiquement attractif de faire appel aux produits de la biomasse (fig. 2).

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Cette situation est d’autant moins probable que la compétitivité du méthanol issu du gaz naturel sera atteinte pour des valeurs moindres, 35 à 40 $/bbl (fig. 3). L’avantage du méthanol comme futur carburant de substitution parait donc décisif pour les pays européens susceptibles de le produire ou de l’importer aux prix les plus bas. 7.2—Addition en faible quantité. Equivalence litre pour litre Ce type de substitution présente des caractéristiques plus favorables. L’écart de prix entre le carburant pétrolier et les carburants oxygénés est faible (tableau III); il peut même être favorable lorsque le méthanol y est associé avec l’éthanol ou le mélange butanol-acétone. De plus, dans certaines configurations de raffinerie, cet écart peutêtre en partie comblé par la prise en considération de l’apport en indice d’octane que procurent ces composés dans une perspective de production d’essence sans plomb. On trouve déjà cette situation en Allemagne Fédérale ou l’addition de composés oxygénés à faible concentration dans la fabrication d’essence à 0,15g/l de plomb est utilisée dans les 2/3 des carburants distribués aujourd’hui. Même si une telle situation ne peut être étendue à toutes les raffineries d’Europe, elle constitue le meilleur moyen de pénétration des composés oxygénés en substitution partielle des hydrocarbures. 8. CONCLUSIONS La substitution des hydrocarbures par les composés oxygénés n’apparait économiquement viable en Europe à moyen terme que si on se limite à des additions en faible quantité, principalement lorsque les mélanges contiennent du méthanol dontle faible prix exerce une influence économique favorable à la pénétration progressive de ces substituts. De plus, la mise en oeuvre des techniques de fermentation éthy-lique et acétonobutylique est encore susceptible de progrès scientifiques et techniques qui doivent améliorer leur compétitivité économique. On peut citer par exemple: – l’amélioration du bilan énergétique (souches thermophiles, techniques de séparation par membranes et par solvants utilisés en conditions supercritiques) – la diminution de la taille des fermenteurs (cellules immobilisées) – l’amélioration des rendements, en particulier dans la transformation des produits cellulosiques (prétraitement, hydrolyse enzymatique) – amélioration de la productivité des usines (transformation successive de plusieurs matières premières; blé, betteraves). Les auteurs remercient M.P.BOISSERPE pour sa contribution à la rédaction de cette communication. BIBLIOGRAPHIE J.C.GUIBET, Carburants de substitution, Orientations et Recherches françaises, Revue IFP Vol 40 N° 1, Janv.-Fev. 1985 J.P.ARLIE, Contenu énergétique des alcools d’origine fossile ou biomasse. Revue IFP, vol. 38 n° 2, Mars-Avril 1983

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V.SEIFFERT, Volswagen Prospects for alcohol-fueled engines, International Symposium on alcohol fuel technology, Ottawa Canada, 22 May 1984 M.VALAIS et P.LEPRINCE, Introduction des composés oxygénés dans le raffinage. Impact et stratégies, Revue de l’IFP, vol. 39 N° 6, Nov.-Dec. 1984 S.TRINDADE, Current status of development and implementation of alcohol fuels technology in Brasil. International Symposium on Alcohol fuels Technology, Ottawa Canada, 22 May 1984 P.LEPRINCE, Coût des carburants de synthèse et prix du pétrole équivalent. Séminaire du Centre de géopolitique de l’énergie et des matières premières. Université Paris-Dauphine, 1983.

TABLEAU I CONSOMMATION DES TRANSPORTS ROUTIERS EUROPE 1983 (106t/a) CARBURANT AUTO GAZOLE VOITURES PARTICULIERES VEHICULES UTILITAIRES LEGERS CAMIONS DEUX ROUES TOTAL

80 20 – 2 102

13 8 30 – 54

TABLEAU II USINES DE PRODUCTION DE BUTANOLACETONE F/t DE PRODUIT BLE: 60qx/ha—PAILLE: 2.7t/ha—TAUX D’OCCUPATION: 0,5 CAPACITE t/a MATIERES PREMIERES

50 000 100 000 150 000 BLE PAILLE BLE PAILLE BLE PAILLE

CHARGE DE CAPITAL MAIN-D’OEUVRE 1 520 COLLECTE TRANSPORT 220 DISTANCE DE COLLECTE (km) 14

2 940 1 190 390 230 30 20

2 170 1 010 540 250 41 25

TABLEAU III DONNEES ECONOMIQUES (F/l) EQUIVALENCE SUPERCARBURANT METHANOL ETHANOL ANHYDRE ETHANOL 95% MELANGES E5TBA2 E3TBA2 E5MBA2 E3M3

LITRE/LITRE ENERGETIQUE 1,88 1,05 2,50–3,00 2,10–2,40 2,40–2,70 2,10 2,80–3,20 1,80–2,00

1,88 2,10 3,90–4,50 3,30–3,80 – – – –

2 080 620 52

La biomasse, source de substituts au pétrole dans le secteur des transports

Fig. 1.

Fig. 2. Composés oxygénés de fermentation des plantes sucrières

51

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Fig. 3. Substitution par le méthanol I.F.P.MARS 1985

SESSION I THE EUROPEAN SCENE Trees and Wood as an Energy Source in the Nordic Countries— G.Wilhelmsen Biomass Availability and Use in the Industrial Regions of the EC— A.Strehler Ressources en biomasses utilisables à des fins énergétiques en milieu agricole—cas de l’europe des 10— C.Gosse Biomass for Heating and Fuels in Austria—a Case Study for Europe?— A.F.J.Wohlmeyer

TREES AND WOOD AS ENERGY SOURCE IN THE NORDIC COUNTRIES G.WILHELMSEN Research Director The Agricultural Research Council of Norway Summary The anticipated use of wood fuels the last two years has been somewhat greater than the existing market, particularly in Sweden. In some countries this has lead to a certain overcapacity in fuel production. The optimistic expectation was due partly to an underestimation of the use of electricity in district heating plants and the replacement of oil burners with electroboilers and partly to a slower development than expected in the regional plans for district heating systems in general. The initial phase of aggressive optimism is therefore being replaced by a reflecting, sound phase of consolidation. This will hopefully result in a stronger market structure with respect to both economy and organization. Socioeconomic motives, such as employment, energy security, overproduction in agriculture, etc., seem today to be much more important in marketing wood fuels in the Nordic countries than previous energy motives, such as lack of energy, renewable vs. fossile energy sources, etc. In spite of some drawbacks, more and more people heat their houses with wood, and biofuels seem to be increasing their market-share in all countries. In Norway, 30% of the private households regard wood as the cheapest and most important fuel. The consumption has increased every year, from 190.000 toe in 1973 to 420.000 toe in 1984. However, a broadening of the market in the Nordic countries will very much depend on the success of upgrading wood as fuel, and the result of establishing confidence between seller and buyer through a strong reliable marketing organization.

1. INTRODUCTION The surrounding world often looks upon the Nordic countries as a harmonic and homogeneous unit. In many cases this is true and co-operative work between Nordic countries has been successful in many fields. In the energy field, however, there are gaps with regard to both energy production and energy consumption. A certain amount of background information is therefore needed to fully understand the use or lack of use of wood fuels in these countries. The wood fuel market is most likely dependent on both the supply and price of alternative energy sources, such as coal, electricity and oil, and to

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what degree each country politically emphasizes socio-economic benefits using domestic and renewable energy sources. 2. HYDROPOWER, COAL AND OIL The share of hydropower in the energy supply of the world is overall quite small, but Finland and especially Norway and Sweden have the advantage of good hydropower resources. The very few district heating plants in Norway are partly due to cheap and easily available hydropower. Denmark used to depend almost entirely on oil-based thermal power, but has in recent years partly switched to thermal power based on coal. A smaller part of Sweden’s electricity supply is also covered by thermal power, based mainly on oil, but today oil has been replaced by nuclear power to a large extent. Both Norway and Sweden have a fairly low electricity price today and offer financial support to install electro boilers for those using surplus power. This has in a negative way seriously influenced the wood fuel markets in recent years.

Tab. 1 Production of primary energy, 1982 (PJ) Country Solid fuels Crude oil etc. Gases power Nuclear power Hydro power Sum Denmark Finland Norway Sweden

7 175 41 129

70 173 1 091 1

1 040 421

77 55 403 394 2 566 233 784

The coal supplies in Svalbard cover part of Norway’s coal consumption, while the other countries have to import all their coal. The consumption of coal is decreasing in all countries except Finland, where it has stabilized. The competition from coal is noticeable in all countries except Norway, due to the few district heating plants. Oil is the predominant energy source in Denmark, Finland and Sweden, but is also of great importance in Norway’s energy consumption. Essential in this connection are the important discoveries of oil and gas in recent years along the Norwegian coast. The extractable quantities are calculated to amount to about 529 mill. tons of oil and 360.000 mill Sm3 of gas fields which are in production, under development or for which development has been decided as per Dec. 31. 1983. It is obvious that this production of gas and oil influences goals and strategies in the wood fuel programme of Norway. For example Norway has very few opportunities for financing wood fuel combustion plants or other incentives to cut back oil consumption. In Denmark, Finland and Sweden, several financial opportunities have been introduced by the governments as a facet of their over-all energy policy. This can also work to other way around, as in Denmark, where the authorities want to ensure and develop the natural gas market and the construction of pipe lines. This has slowed down the financial support to the wood fuel market at the present time.

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3. THE WOOD FUEL SUPPLY Wood fuels in the Nordic countries still come from traditional forestry as hard-woods, first thinnings and forest residues, along with wood-residues from the forest industries. The total wood for combustion is at present 50 mill. cu.m solid wood or 8.765.000 toe, (Denmark 1,5%, Finland 40,8%, Swe-den 49,7% and Norway 8,0%).

Tab. 2 Background information DENMARK FINLAND NORWAY SWEDEN Land area (km2) Population (mill) GNP per capita 1981 (USD) Production forest area (mill ha)

43 000 5.1 13 120 0.41

337 000 4.7 10 680 19.7

325 900 4.1 14 060 6.7

411 600 8.3 14 870 23.4

Tab. 3 Energy use of wood in industry, district heat and space heating in 1983 DENMARK FINLAND NORWAY SWEDEN 1000 toe % 1000 toe % 1000 toe % 1000 toe % Black and sulphite liqueors Industrial waste wood Space heating District heating Sum

– 0 59 44.7 64 48.5 9 6.8 132 100.0

1 590 44.4 780 21.8 1 140 31.9 69 1.9 3 579 100.0

245 35.0 88 12.6 367 52.4 – 0 700 100.0

2 732 62.7 512 11.8 939 21.6 171 3.9 4 354 100.0

Energy plantations based on root shoots harvested at a few years’ intervals and on stock with life expectancies of up to 30 years at present can be said to be at the research stage in several respects. There are at least in Sweden large-scale pilot trials in order to establish an adequate requirement of continuous research and development work, but it is not possible to day to assess the energy contribution, economics or environmental effects of these energy plantations. 4. WOOD FUEL MARKET The wood fuel market is still very much dependent on the fact that the energy producers are the same persons or companies as the energy consumers—in other words no “market” in the traditional meaning of the word. The forest industry itself is today the biggest producer and consumer, as it burns its own waste material in kiln dryers or burns waste liquor. Next to the forest industry come the forest owners using their own wood or wood chips for heating purposes. In Norway we figure that about 2.5 mill. m3 of wood (430.000 toe) is used for heating in private households. About 65% of this wood is cut and handled by the consumer himself. Together with industrial waste this “market” part accounts for about 85% of the total consumption. There is a general feeling in all the Nordic countries

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that this “market” will level off very soon. Any expansion must be based on a tradi-tional market of buying and selling, which again will require an upgraded fuel that can be more easily transported, stored, handled and burned—preferably in district heating plants. 5. PELLETS AND BRIQUETTES We know that wood fuels can be processed in various ways. The simplest type of chipprocessing is drying and sorting by size and calorific value. The most interesting products for tomorrow seem to be pellets, briquettes or powder, either from wood, straw or peat. Dry and compacted wood with a high calorific value is needed to develop the market. This upgrading must in my mind be just the first step. The next step to broaden the wood fuel market will be to sell wood as heat. There are now in all the Nordic countries companies—planned or in operation—to take care of fincancing, installation, fuel production, fuel delivery, maintenance etc. in one packet. What’s needed to develop this market further is confidence—complete confidence between seller and buyer—as in the heat market where oil and electricity companies are involved. This confidence depends very much on contracts. Recent years have given us valuable experience in this respect concerning: ○ Fuel types ○ Fuel grades ○ Contract period ○ Delivery and reception of fuel ○ Measurement ○ Payment terms ○ Price adjustments ○ Delivery and operating irregularities ○ Damage, disputes, force majeure etc. I think it’s correct to say that in all the Nordic countries the last years these questions of organization and market development have been given much more attention than before, also compared to technological development. More companies responsible for heat delivery from wood as you have in the oil and electricity supply are needed. This thought needs, however, to be supported by the traditional and strong organizations within forestry and forest industries. 6. DISTRICT HEATING/WASTE DISPOSAL Densified fuel as pellets and briquettes will probably develop a market by replacing oil burners in medium-sized boilers at institutions, schools, hospitals etc. in urban areas. District heating plants seem more often to combine the burning of domestic garbage and biofuels. This wanted mixture is partly due to the fact that the heat value of garbage is lowered from time to time, because people sort out newspapers, paperbags etc. for their own stoves. This lowering of the heat value may subsequently influence the combustion temperature in the plant with a high and unwanted dioxin output as a result. In addition to

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favourable environmental aspects as this example, job creations will very often favour district heating plants. A recent official paper from Sweden states that limiting factors during the introduction stage seem to be: – Planning/preparations on the user’s part for burning of chips – Methods and organization for collection and distribution of fuel – Competition for the raw material from pulp and paper industry. For immediate application (next 8–10 years) wood fuels will probably be limited to substitution for oil in space and industrial use. This means that, with the exception of hydroelectric power, wood fuels cannot make any significant contribution to the direct replacement of large nuclear fuel or fossile power stations. 7. SOCIO-ECONOMIC GROUNDS In most countries one would like to see that public funds in grart form are viewed as an exceptional measure in the case of energy investments that are well justified on socioeconomic grounds, but not viable on strictly economic terms. In many ways wood energy projects have been regarded as such, with a strongdriving force for rural development. Important key issues are: ○ Contribution to the creation of jobs in rural areas ○ Ensuring energy security ○ Environmental aspects ○ Relieving overproduction in some agricultural sectors. Recent years have been regarded as a transition period to initiate and accelerate the desired investment activity. Some hope that the need for subsidies will be reduced and eventually phased out as the required investments are sufficiently supported by initial grants. Others want to continue this use of public funds to be able to direct the development with respect to the socio-economic grounds already mentioned. These views vary from one country to another and depend very much on the political system involved. It seems that Finland and Sweden emphasize socio-economic grounds more than the other countries. 8. RESEARCH AND DEVELOPMENT Five to six years ago strong energymotivated forces initiated and financed bioenergy research programs in all the Nordic countries. The R & D budgets increased dramatically and have been kept at a fairly high level since. At the moment this initial phase of aggressive optimism seems to have been replaced by a more reflective attitude. The R & D budgets have stabilized and in some countries been reduced. The socio-economic motives mentioned seem to be as important as previous energy motives such as lack of energy, renewable vs. fossile fuels etc. This has in some countries resulted in substantial financial support from “non-energy” sources e.g. agriculture.

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Tab. 4 Government Funds for Bioenergy Research and Development (1983) USD per year Total mill. Per capita Denmark 1.0 0.20 Finland 4.2 0.89 Norway 0.8 0.20 Sweden 21.3 2.57 Total/Average* 94.1 0.31 *) Total/average for 10 countries participating in the IEA Forestry Energy Agreement

The time since 1979 has in many ways been a pioneer period. In the last few years many bioenergy projects have been turned down and also some products and companies have disappeared. For the time being, the strategy seems to be of strengthening basic competance in bioenergy research, more seriously analyzing market barriers and focussing on a few promising products. This has been necessary and natural, but in some ways quite painful, development. 9. INFORMATION ABOUT THE NORDIC COUNTRIES Finally, I would like to advertize a directory called “Energy Research and Development Projects in the Nordic Countries” that is published yearly. In addition all information on published literature and research in progress is included in the computerized system NEI (Nordic Energy Index). Further efforts have been taken this year by the Nordic Council of Ministers to strengthen the basic competence and teaching facilities in bio-energy at university level. The Council has recently decided to offer two professorships and six fellowships in the area of bioenergy from 1986. REFERENCES (1) GILLIUSON, R. (1984). National R & D programmes in member countries of the IEA Forestry Energy Agreement area “Harvesting, on-site processing and transport”. (2) Yearbook of Nordic Statistics 1983. (Nordic Council and Nordic Statistical Secretariat). (3) Energy Research and Development Projects in the Nordic Countries.—Directory 1984 (Nordic Council of Ministers, 1984). (4) Energy Research Development and Demonstration in the IEA countries. 1983 Review of National Programmes (OECD Paris, 1984).

BIOMASS AVAILABILITY AND USE IN THE INDUSTRIAL REGIONS OF THE EC Dr. A.Strehler Technische Universität München Bayer. Landesanstalt für Landtechnik D—8050 Freising Summary Many options to replace fuel oil are in discussion. One of the most important energy resource is to be seen in biomass as residues from agriculture, forestry, human waste and from energy plantations. The advantages of waste and residues are manifold; less environmental load, cost reduction, saving of devices. The energy plantation is a good option to reduce the problems in financing the EC agricultural market and to guarantee the fuel supply in the future. Biomass is also used in industrial regions like the Federal Republic of Germany, in rural and municipal areas. In some areas household, heat demand can be covered up to 100% from biomass. It is mainly used as a solid fuel for heat generation. There are options for conversion to liquid fuel for powersupply in vehicles. The biomass energy of FRG, including energy plantations on surplus areas, can supply up to 8% of total demand. Today this supply mainly consists of woodwaste in the range of 1%. It is necessary to improve the combustion quality of most types of furnaces to get less emission of tar and smell. For use of biomass from energy plantations densification systems for fuel have to be improved, like briquetting, cutting, milling, thermal conversion, ethanol and plantoilproduction.

1. INTRODUCTION The total energy consumption of the EC is about 1Mrd. tOE (OE=oil equivalent). Agriculture utilizes directly 18.5Mio. tOE as energy products. The percent usage in agriculture is very different depending on the region. Estimations of the potential of energy from biomass which could be utilized in agriculture run from 1 to 10% of the primary energy demand. Agricultural countries have a relatively higher biomass contribution to the total energy consumption than industrial countries because industrial countries have a higher total energy consumption. However, the absolute quantity of energy from biomass in industrial countries is even higher than that in aqricultural regions because the population density is related to biomass waste. The 1 to 10% energy from biomass seems to be a low contribution to the total energy consumption. But one

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should keep in mind the additional effects from utilization of biomass for energy generation as: – Disposal of combustable waste – National economic effect by diminishing the import of energy – Possibilities to diminish problems of agricultural market of the EC. The importance of different resources for biomass is widespread. Further, the awareness of which different resources allow an effective economical usage is to be attained, employing mature technologies. Therefore there will be the term for further considerations: “Effective Utilization” Following resources will be taken in consideration: – Animal waste, mainly from agriculture – Waste from agricultural plants (mainly straw from cereals) – Waste wood from forest and wood processing – Communal waste – Waste of other only local resources – Special production of biomass as energy supplier in relieving problems faced in financing the agricultural market. As the problems of the agricultural market are very serious and the responsible people have not had great success in finding alternatives, the option of producing energy substitutes shall be treated especially in the following considerations. 2. ESTIMATION OF THE ENERGY POTENTIAL FROM WASTE 2.1 ENERGY POTENTIAL FROM ANIMAL WASTE Due to the waste quantity available, only swine, cattle and chickens will be in consideration. 2.1.1 WASTE POTENTIAL FROM SWINE From the number of animals, waste for different countries has been calculated. For economical and technical reasons only 5% of the resources can be utilized considering current technical standards and energy prices. The energy potential for Germany is 2.02MtOE, for Europe 0.094MtOE. 2.1.2 ENERGY POTENTIAL FROM CATTLE WASTE Depending to the number of animals and the restriction of 5% effective use the energy potential for FRG is about 0.15MtOE, for the EC 0.64 MtOE. 2.1.3 ENERGY POTENTIAL FROM CHICKEN DUNG For the FRG there are 0.01MtOE, for the EC 0.06MtOE.

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2.1.4 COMPARISON OF ENERGY POTENTIALS FROM THE DIFFERENT TYPES OF ANIMALS FOR EUROPE AND FRG As Table I shows, there is a potential for all 3 types of animals from 0.79MtOE for the EC and 0.15MtOE for the FRG. With technical progress there could be a higher potential than only 5% of the resources. The economic effective utilization also depends on the price of alternative energy sources.

Table I: Available energy from manure of swine, cattle and poultry animal column 1 swine cattle poultry

energy in the produced gas 1000 GJ/a 2

79.1 534.3 50.0 663.4 columns 2–5 EC, column 6 FRG

=MtOE (oil equivalent)

usable energy (5% of =MtOE potential) GJ/a EC

3

4 1.3 12.7 1.2 15.8

5 3.9 26.7 2.5 33.1

MtOE FRG 6

0.09 0.64 0.06 0.79

0.025 0.120 0.001 0.146

2.2 ENERGY FROM PLANT WASTE 2.2.1 CEREAL STRAW Since there are special straw combustion units on the market, straw can be utilized as an energy source when there is not a better “local utilization like animal bedding, animal food, fertilizer or raw material for industrial purposes. In many regions, especially with large cereal farms, little livestock and low rainfall, straw can be utilized with no or low costs from the field. The cereal straw obtained depends to the local situation and there are big differences even in small areas. A total estimation of cereal straw yield could be done and the potential availability is set at 20% of the total yield. In this case the 124Mio t total yield of straw in Europe would deliver an oil equivalent to 8.4MtOE/a. In Germany the equivalent would be 1.56MtOE/a. In small regions there is an availability of straw up to 60% of the total. In special research work (1) to determine the availability of straw assuming a perfect technique of conversion, farmers would be ready to deliver 34% of their total straw; that would be 9.4MtOE/a from a total yield from 27Mt in FRG. This quantity of energy corresponds to the current consumption of diesel fuel and fuel oil in the agriculture of FRG. Table II shows the total yield and energy potential from straw in the different countries of the EC.

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Table II: Energy potential from straw in the countries of the EC (1983) country straw total 1000 t/a column 2 1 FRG F I NL B LU UK IR DK GR EC

23 011 46 605 17 817 1 308 1 877 68 21 307 1 948 6 380 4 425 124 746

energy in straw energy in straw energy from straw with 20% 106 GJ/a MtOE availability MtOE 3 4 5 325.7 661.8 253.0 18.6 26.6 1.0 302.5 27.7 90.6 62.8 1 771.3

7.78 15.76 6.02 0.44 0.63 0.02 7.20 0.66 2.16 1.49 42.16

1.56 3.15 1.20 0.09 0.13 0.004 1.44 0.13 0.43 0.30 8.43

2.2.2 ENERGY FROM GREEN PLANT RESIDUES The main source is from potatoes, sugar beets and vegetables. Refering to PALZ (2) there is an energy potential via biogas production from 0.64 MtOE for FRG and 3.13MtOE for EC. 2.2.3 WOODY WASTE FROM AGRICULTURE AND HORTICULTURE The main resources are from wineyards and orchards; for Europe 2.7MtOE via combustion are calculated. 2.2.4 RESIDUES FROM PROCESSING OF AGRICULTURAL PRODUCTS There is wet waste from slaughter-houses, wine production, processing of vegetables and fruits and there is dry waste from seed cleaning and rice mills. These types of waste have only local importance. For example, in Italy in the Po region there is a potential of 70 000 t of rice halls. Also high amounts of local importance have been found in fruit and wine processing. The total yield is low and not considered further.

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2.3 ENERGY FROM WASTE OF FORESTS AND WOOD PROCESSING Europe has about 32Mio ha, the FRG 7.2Mio ha. That is 22% of the EC wood area. For the Community there is a fire-wood potential (2) of 17MtOE, in FRG fire-wood can be estimated in the range of 2.4MtOE including waste from processing. 2.4 ENERGY FROM COMMUNAL WASTE (HOUSEHOLDS) For the EC a potential of 15MtOE is calculated and 4MtOE for the FRG. 2.5 SUMMARY OF THE ENERGY POTENTIAL OF WASTE Literature from PALZ (2) and our calculations show a potential of 31.02 MtOE for the EC and 8.2MtOE for the FRG. Table III shows the totals of the energy potential from biomass in Europe and FRG.

Table III: Estimation from energy potential of biomass in EC and FRG (MtOE)

column 1

total energy content 2

animal waste 43.62 plant waste 52.69 (residues) residues of 17.08 forest and wood processing communal 17.00 refuse (municipal waste) total 130.89 column 2–6 EC; 7—FRG

energy content solid fuel 3

energy from biogas 4

effective degree of utilization 5

effective utilizable energy EC 6

effective utilizable energy FRG 7

– 44.87

15.8 4.7

5 –

0.79 6.69

0.146 1.653

17.08

–

50

8.54

2.400

–

–

50

7.50

2.000

61.95

20.5

–

23.50

6.200

3. ENERGY POTENTIAL FROM THE NECESSARY FUTURE PRODUCTION OF ENERGY SOURCES The EC is not able to finance the agricultural market further on without restrictions. One possibility is to be seen in the production of energy sources instead of surplus food products. The most discussed options are:

Biomass availability and use in the industrial regions

BASIC PLANT plants with starch and sugar content short-rotation forestry

ENERGY SOURCE

ANNUAL YIELD in t/ha

ethanol woodchips

oil plants

67

ENERGY in t OE/ha

3–5

2.5–3.5

10–20 1–2 4–8

3–7 1–2 1.5–3.0 2.5–5.0

oi1 plants, sum of oil and straw

Having a surplus area of agricultural production in 1986 of 8Mio ha in the EC (3), energy sources could be produced with an energy content of 32MtOE annually. This energy potential would be 3.2% of the actual EC energy consumption. For the FRG with 1.6Mio ha surplus, 6.04MtOE could be produced. 4. TOTAL POTENTIAL OF ENERGY FROM WASTE AND PRODUCTION OF ENERGY SOURCES MtOE from AREA RESIDUES (WASTE) ENERGY SOURCE TOTAL FRG EC

6.2 23.5

6.4 32.0

12.6 55.5

5. POSSIBILITIES TO UTILIZE RESIDUES AND ENERGY SOURCES IN RELATION TO THE ACTUAL TECHNIQUES OF CONVERSION 5.1 ANIMAL RESIDUES AND GREEN PLANTS ARE TO BE CONVERTED VIA BIOGAS If 5% of the animal waste in the FRG would be utilized, 8 500 biogas plants with 60GV (animal weight units) each could produce 0.146MtOE. The biogas technology is not ready within the next years to utilize residues from green plants. Actual biogas production in FRG: about 80 biogas plants are working in agriculture today and they are able to produce 1000 tOE annually. 5.2 POSSIBILITIES OF UTILIZATION, POTENTIAL AND ACTUAL UTILIZATION OF STRAW AND WOOD RESIDUES The resources of residues from straw and wood are 12Mio t with an energy equivalent to 4Mio t OE. These resources can be utilized for heat and power generation. Heat production is of more importance because it is cheaper to replace oil this way. But in

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some cases power generation is more economical. The technical standard of systems is as follows: Power via heat generation via combustion in cylinder Steam piston engine xxxx Thermal gasifier, updraft x Steam turbine xxxx Thermal gasifier, downdraft xx Sterling motor 0 Fluidized bed x Hot-gas turbine xxx Technical standard: xxxx=high; x=low; 0=in development stage

Technical standard: xxxx=high; x=low; 0=in development stage Aside of the technical standard, the total costs are important. They are in the range of 0.15 to 0.70DM/kW. Furnaces are delivered in a broad variety, 80 manufacturers deliver furnaces for wood and 20 from them for straw. The furnaces are produced with discontinuous and continuous charging, with small and large-sized combustion chambers and partly as prefurnaces (especially for wood chips). Most success had following system: bottomburning boilers with discontinuous charging in connection with heat stores, boilers and pre-furnaces with continuous charging with movable grates. Table IV shows the most important types of furnaces, the number of utilized plants and the market potential to utilize the available residues from straw and wood. Basis for the use of the big energy potential especially of straw is the availability of cheap, technical perfect furnaces with low critical emission and high efficiency and comfort. The important sponsorship of CEC, Gen. Dir. XII and BMFT Bonn for research was the basical start. Further research is necessary.

Table IV: Estimation of market potential for straw and wood furnaces (residues) Type of furnace number of current and fuel furnaces in consumption residues use straw+wood 1000 t OE column 1 2 3 single stoves, (200 000) wood logs <6 kW single stoves, (50) straw briquettes <6 kW small boilers, 386 820 wood logs <40 (50% in use) kW small boilers, 25 straw briquettes <40 kW through-burning boilers, 20–100 kW for

unused straw+wood residues 1000 t OE 4

number of furnaces required for unused residues, FRG 5

200

75

30 000

0.05

30

20 000

750

75

20 000

0.05

300

80 000

Biomass availability and use in the industrial regions

– wood logs (1 meter) – straw bales (small) bottom-burning boilers, 20–100 kW for – wood logs (1 meter) – straw bales (small) boilers for big bales, discont. 250–1000 kW boilers with automatic charging – straw bales small 40–150 kW – big bales, debaler, 200–1000 kW – wood chips, 20–200 kW total

69

9 220

30

150

75 000

1 315

3

100

0

9 029

30

150

75 000

200

0.6

400

10 000

15

0.3

75

100

180

0.9

200

5 000

10

0.3

75

100

7 000

35

300

50 000

613 864

1.3Mio

1.9Mio

365 200

The potential of residues and the production of energy crops is shown in Figure 1.

Figure 1: Comparison of convenient usable biomass energy potential with

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the at present used potential in the FRG REFERENCES: (1) PETERS, A.: Das Energiepotent.v.Biom. i.Kreisen BRD, 1983, ISSN-0303-2493 (2) PALZ, W.; Ph. CHARTIER: Energy f. Biom.i. Europe (1980) ISBN 0-85334-934-7 (3) SCHÄFER, R.; E.HEIDRICH: Einfluß u.Nutzung v.Biom. als Energieträger, TUM—Landt.— Weihenstephan, CEC Gen. Dir. XII, Study

RESSOURCES EN BIOMASSES UTILISABLES A DES FINS EMERGETIQUES EN MILIEU AGRICOLE—CAS DE L’EUROPE DES 10 Ghislain GOSSE Institut National de la Recherche Agronomique Station de Bioclimatologie 78850 THIVERVAL-GRIGNON La surface agricole utile de l’Europe des 10 est de 102M d’hectares soit 60% du territoire. La situation géographique et climatique de l’Europe ainsi que l’histoire différente des systèmes agricoles ont conduit à une très grande variabilité des productions aussi bien en quantité qu’en qualité. Nous nous efforcerons de dégager les grandes caractéristiques de cette production de biomasse et de l’illustrer par des exemples précis au détriment d’une analyse exhaustive de la ressource. Cette notion de ressource utilisable à des fins énergétiques doit être à chaque instant située par rapport aux utilisations concurrentes ou complémentaires (alimentaires, industrielles…) et évaluée en fonction de l’état des connaissances des différentes filières de production d’énergie.

LES COMPOSANTES DU GISEMENT POUR UNE PRODUCTION DONNEE Il est possible d’exprimer la ressource potentielle en biomasse d’un territoire donné par le produit d’un rendement agricole par la surface occupée par la production envisagée, cette ressource potentielle est alors fonction de deux coefficients: – un coefficient d’occupation, caractérisant la surface occupée, qui dépend de facteurs pédoclimatiques et économiques, – un coefficient dit “technique”, caractérisant le rendement agricole, qui est fonction des facteurs pédoclimatiques, des techniques de production, du niveau de technicité des exploitants et des atructures de production. Cette notion de ressource potentielle est très insuffisante pour élaborer un scénario d’utilisation de la biomasse, elle peut être utilement complétée par les notions de gisement disponible et de gisement utilisé. Chacune de ces notions se traduit par l’introduction d’un coefficient de réduction, soit: – un coefficient dè disponibilité traduisant les concurrences entre usages finals et l’adéquation de la matière première aux contraintes techniques de la filière, – un coefficient d’utilisation traduisant la mise en oeuvre du gisement, ce dernier coefficient illustre les concurrences avec les énergies fossiles, les concurrences au niveau

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de l’usage des facteurs de production et aussi le poids des facteurs humains dans la décision économique. Par la suite, nous choisirons des exemples pour illustrer cette cascade de potentiels en soulignant les points faisant obstacle au développement de la biomasse comme source d’énergie. LES SOUS-PRODUITS D’ORIGINE AGRICOLE: Les sous-produits d’origine agricole sont classiquement subdivisés en résidus secs, résidus humides et résidus d’élevage. Les résidus secs représentent un gisement potentiel important pour l’Europe des 10, de l’ordre de 85MT de matière sèche (Cf Figure 1) avec une contribution de 80% pour les pailles de céréales, à ce titre nous développerons plus en détail le gisement que représente ces pailles qui sont pour 90% des pailles de blé et d’orge. Au niveau européen, le coefficient d’occupation des sols est stable depuis 15 ans, une diminuation des surfaces en orge est compensée par une augmentation des surfaces en blé (Cf Figure 2); il reste néanmoins difficile de faire des projections dans le futur de ces observations et surtout d’identifier les zones pouvant faire l’objet de variations importantes. L’évolution du rendement en paille par unité de surface est une fonction du rendement en grain; en effet, la sélection a essentiellement porté sur l’augmentation du rapport Epi/Paille sans augmentation significative de la matière sèche totale soit une tendance à une décroissance du rendement en paille. Des travaux récents visent à augmenter la biomasse totale tout en gardant un rapport Epi/Paille intéressant, soit une inversion de la tendance pour le rendement en paille. Le coefficient de disponibilité de la paille pour un usage énergétique est essentiellement fonction des concurrences entre les différent usages finals (litière, alimentation animale, papier…). Le tableau 1 illustre pour 5 des pays producteurs européens la destination de ces pailles de céréales: – 60% des pailles sont récoltées et 90% des pailles récoltées sont alors utilisées pour la litière et l’alimentation animale; dans ces pays, l’usage de la paille comme source d’énergie ne représente actuellement qu’un total de 500 à 700 000 T de MS. – 40% des pailles ne sont pas récoltées, elles sont enfouies ou brulées sur le champ; à partir de ce gisement et en satisfaisant les besoins en matière organique des sols, notamment en enfouissant les résidus humides de la rotation ou les cultures dérobées (engrais vert); il semblerait possible d’estimer un gisement disponible au niveau européen d’une valeur de 18 à 20MT de MS (Cf Poster de V.REQUILLART). Pourquoi une utilisation de la paille aussi faible et pourquoi un développement aussi lent à quelques exceptions près (cas du Danemark)? Ces questions paraissent fondamentales, elles sont largement développées au niveau de posters spécialisés; néanmoins, il semble important d’identifier les obstacles de type technique (bilan humique des sols, collecte et faisabilité technique de la transformation,…), de type macro et microéconomique (concurrence avec les énergies fossiles, concurrence au niveau de l’usage des facteurs de production), et de type humain ou sociologique.

Ressources en biomasses utilisables a des fins energetiques en milieu agricole-cas de l'europe des 10

Les résidus humides et les déjections animales, on peut définir un gisement potentiel comme précédemment pour ces sous-produits (Cf Figures 3 et 4) mais le problème déterminant est au niveau de la transformation par méthanisation de ces résidus. Pour les résidus humides de culture, il semble plus intéressant de les valoriser sous forme de matiére organique enfouie afin d’améliorer le coefficient d’exportation de la paille tout en maintenant un bon équilibre humique à l’échelle d’une rotation. L’utilisation de la méthanisation peut conduire à une valorisation sur trois points: une production d’énergie (biogaz), un effet bénéfique sur l’environnment (odeurs, teneur en MO des effluents) et/ou une obtention d’un digestat valorisable. Schématiquement et dans le contexte actuel, il apparait que la méthanisation de ces sous-produits a une probabilité d’émerger pratiquement si deux des points précédents sont satisfaits, notamment l’effet sur l’environnement (cas des lisiers). LES CULTURES UTILISABLES A DES FINS ENERGETIQUES Les problèmes posés par les cultures énergétiques sont très généraux et ceci à double titre, en effet l’insertion d’une nouvelle culture dans un système établi n’est pas spécifique aux cultures énergétiques et, par ailleurs, dans le contexte européen, cette insertion est très liée à la Politique Agricole Commune (Conférences précédentes). Cette insertion des cultures énergétiques pose au moins trois grandes questions: – quelles formes d’énergie produire? – sur quelles surfaces (superficie et qualité)? – avec quelles espèces végétales? La première de ces questions abordées, par ailleurs, est déterminante car les réponses aux deux suivantes seront très dépendantes des orientations définies précédemment avec par exemple une production d’alcools ex-biomasse liée aux carburants sans plomb et une production de matière lignocellulosique valorisable par des voies thermochimiques. De nombreux scénarios ont été élaboré autour de l’autosuffisance de la CEE en matière de productions agricoles, scénarios plus ou moins globaux (avec ou sans les productions de protéagineux notamment); ces scénarios prévoient des surfaces disponibles variant de 2Mha à 15Mha selon les hypothèses de départ, mais avec une caractéristique systématique importante concernant la qualité agronomique des sols libérés (zones caréalières et prairiales). Cette notion “d’excédents” bien que relative est un problème d’actualité mais aussi en absence de modifications structurelles importantes un problème crucial pour l’avenir compte-tenu des progrès techniques et génétiques au niveau de la recherche et en voie d’application. Parmi les possibilités de reconversion de ces sols, seul un scénario énergétique sera ici envisagé. Compte-tenu des questions d’actualité (les carburants sans plomb) et de l’état d’avancement des filières thermochimiques, deux grands types de production sont envisageables: – des productions de sucres facilement hydrolysables, – des productions de matériel lignocellulosique à forte teneur en matière sèche. Avec quelles espèces végétales satisfaire ces objectifs?

73

Energy from biomass

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Deux types de production peuvent être envisagés: – des productions dont la phytotechnie est déjà maîtrisée grâce à des travaux antérieurs, c’est le cas des betteraves, des oléagineux (carburant de crise) et des céréales, – des productions dont la maîtrise à différents niveaux est à améliorer et à optimiser, c’est le cas des taillis à courte rotation ou du topinambour… Dans le premier cas, outre les travaux d’amélioration déjà entrepris pour optimiser la production à des fins alimentaires, deux points supplémentaires paraissent importants à développer: – améliorer la qualité technologique du produit compte-tenu des exigences définies par les industries de transformation, – améliorer les techniques et les gains de productivité afin de diminuer les coûts de la matiére première agricole, ceci est particulièrement vrai pour la betterave à sucre où le coût de cette matière première peut représenter 50 à 60% du coût de l’éthanol produit. Dans le second cas, une méthodologie est à définir pour caractériser les potentiels de production des espèces à introduire par rapport aux espèces concurrentes en place. Lorsque l’on s’intéresse à la production de biomasse aérienne, divers travaux sur le rayonnement intercepté par une eulture montrent que pour un type métabolique, C3 ou C4, la productivité annuelle d’un couvert végétal est essentiellement fonction de sa durée de végétation et la vitesse de colonisation de l’espace (Cf Figures 5 et 6). Ce type de démarche fixe une limite supérieure de produetivité en milieu agricole et les résultats largement supérieurs à cette limite ne peuvent être expliqués que par une mauvaise intégration des effets d’échelle (espace, temps). Ce type de démarche est directement applicable aux productions lignocellulosiques dont l’ensemble des parties aériennes est exploitée. Ce type de production peut être caractérisé par une plante pérenne dont le rythme d’exploitation est variable allant de quelques années (taillis à courte rotation, genêt), à l’année (Roseau, Canne de Provence) et jusqu’à quelques semaines (fourrages). Pour ces productions, des axes de recherches à privilégier peuvent être: – la sélection d’espèces ou de variétés présentant d’une part une vitesse de colonisation de l’espace rapide et d’autre part, une aptitude élevée à la fauche ou au recépage (pérennité des souches). Un effort particulier est à faire sur les légumineuses ou autres espèces fixant l’azote de l’air, – l’adaptation de techniques d’exploitation et de gestion permettant des covalorisations comme fourrage et énergie, énergie et bois industriel… Ces productions lignocellulosiques ne sont pas actuellement, d’un point de vue agronomique, en compétition directe avec des espèces déjà très améliorées et optimisées; il n’en est pas de même pour les espèces produisant des sucres facilement hydrolysables comme le topinambour… qui ont à justifier leur insertion dans le système traditionnel (betterave-céréale) par un attrait supplémentaire. A ce titre, le topinambour présente plusieurs intérêts: – les zones d’implantation de cette espèce ne sont pas nécessairement les rêmes d’un point de vue pédoclimatique que celles de la betterave par exemple, – la nature des sucres formés, inuline et ses composés -fructose et glucose- permet d’envisager une production de sirop de fructose parallèlement à la production d’alcool carburant,

Ressources en biomasses utilisables a des fins energetiques en milieu agricole-cas de l'europe des 10

– dans des conditions similaires (type de sol), les productivités du topinambour et de la betterave sont du même ordre, – cette espèce présente actuellement des défauts quant à sa mise en culture (date de récolte, forme et nombre de tubercules), mais une grande variabilité génétique existe sur ces critéres et les travaux en cours laissent espérer des solutions à ces problèmes phytotechniques. CONCLUSION Ce type d’analyse, dans le meilleur cas, ne peut être que le reflet d’une ressource à un instant t, compte-tenu de l’état de l’art au niveau des filières de transformation et des contingences macroéconomiques du moment. Néanmoins, il apparait possible de dégager quelques points à développer: – à court terme, l’amélioration de la produetivité d’une production lignocellulosique nécessite, d’une part, une colonisation rapide de l’espace et, d’autre part, un allongement de la période de végétation, – l’introduction d’espèces nouvelles ne doit pas être raisonnée uniquement en terme de quantité, mais surtout en terme de qualité, – la notion de covalorisation du produit agricole (énergie, alimentation humaine ou animale et la chimie du carbone), – identifier le poids de la ressource dans l’ensemble de la filière, – identifier les obstaoles au développement d’une filière de production d’énergie exbiomasse, à ce titre, le cas de la paille est un excellent outil méthodologique, – caractériser en qualité et quantité les surfaces disponibles pour l’insertion de ces cultures énergétiques.

Fig. 1: Résidus Secs-EUR10 (78–82) Gisement Potentiel

75

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Fig. 2: Evolution de la Sole Céréalière Française de 1972–1984

Fig. 3: Résidus Humides-EUR10 Gisement Potentiel (78–82)

Ressources en biomasses utilisables a des fins energetiques en milieu agricole-cas de l'europe des 10

Fig. 4: Déjections Animales-EUR10 Gisement Potentiel

Fig. 5: Evolution de la matière sèche aéricure produite en fonction du

77

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rayonnement intercepté et du cycle métabolique.

Fig. 6: Productivité potentielle en fonction du gisement solaire incident.

Ressources en biomasses utilisables a des fins energetiques en milieu agricole-cas de l'europe des 10

Fig. 7: Influence de la position du cycle de végétation, de la vitesse de mise au place de la surface foliaire sur la productivité potentielle.

79

BIOMASS FOR HEATING AND FUELS IN AUSTRIA A CASE STUDY FOR EUROPE? A.F.J.WOHLMEYER, Austrian Association for Agricultural Research, Vienna Summary Austria with her diversity in climate, geological formation and relief as well as with her ecological and economic situation can serve as a comprehensible case study for the present situation and the strategies, which have to be taken up. The wider context of the present ecological situation and the long term economic needs ask for a dramatic change. Covering the energy and raw material needs as far as possible within the circuit systems of nature in a decentralized style is the necessary answer. The potential of possible biomass production for energy and raw material uses is usually underestimated. The analysis shows that a doubling of agricultural and forestrial production can be foreseen. Since at the present state of productivity food, feed and export needs can be fully met, the increase in productivity per hectare can be dedicated to cover energy and raw material needs. Primary energy consumption being about 920PJ and biomass production amounting at present to about 1.000PJ, biomass has the potential to cover all present primary energy needs. According to the structure of energy consumption the use of biomass for producing heat and fuels for combustion engines is the most reasonable pathway.

1. Introduction The ecological situation asks for a new assessment for energy for biomass. Short term micro- and macroeconomic analysis within the traditional framework of thinking is no longer satisfactory. The ecological situation and the nightmare of structural unemployment as well as the danger of dying forests along with a substantial decline of the number of active farmsteads (which will aggravate the ecological and economic situation) strongly recommend a dramatic change. There are limitations of higher value which overrun the aim of a maximum of short term profit in micro-and macroeconomic models. If we want to ensure to the soil, to plants, animals and to ourselves a state of biological well-being, we must not take out of the ecosystem more organic substances than can be reintegrated. In other words, we have to live within the recycling system of nature in order to survive. The compensatory potential of many species is already overcharged and the worldwide ecological situation can be compared with a full pot. Any additional

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immission causes overflowing. This is to say that we are in the phase of breakdown, because the cumulative effect of the stressors can no longer be compensated by living organisms—especially by plants having a longer life time, because in their organisms the cumulative effect is much larger. We have to become aware of the fact that in one year’s time we consume an amount of fossile biomass which nature has produced within at least 500.000 years and by doing so, we are overstressing the ecosystem, which is not allowed the time necessary to adapt to the rapidly altering environmen-tal conditions (including ionizing radiation for which nature has so far not even developed a sense-organ, which could warn living beings in case of danger). Theres is a growing gap between the reality of the slowly changing biological information and the rapid anthropogenous environmental changes. The answer can only be that we have to practice a more cautious energy- and raw material management in line with nature and not against her. The principles of precaution provision and responsibility have to be an irrevocable part of national and international energy politics. Finally, we are not allowed to plunder this earth, which is entrusted to us. We have the obligation to render it to succeeding generations in the best possible state. 2. The underlying situation 2.1 Austria has on the one hand a lack of fossile energy resources and has legally banned the nuclear option (which is rather vulnerable in case of war). On the other hand, she has a surplus of biomass and is well endowed with water power. Those federal provinces, where the governments had foresight to invest in water power, although this was more expensive in the days of fossile energy available, are now in a favourable position, having relatively cheap energy available especially for industrial uses. Austria as a whole is in danger so lack the analogous foresight concerning organic primary energy sources. Her fossile energy resources may last for a maximum of 20 years only, although imports amount already to 90% approx. of total fossile energy consumption.

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2.2. Austria is one of the two permanently neutral members of the international community. Thus her constitutional obligation to a maximum of self-reliance in case of conflict or of restricted supplies is in its practical outcome very similar to what Europe as a whole should do in order not to be involved in international conflicts for energy reasons. 2.3. Austria’s energy imports amount to about 2/3 of total energy consumption. In terms of foreign exchange this is a volume of US $ 3 milliards approx. The Energy Concept 1984, which was approved by parliament in March 1985, is based on traditional forecast concepts and on the selection of the cheapest energy source, without taking account of the necessary ecological and economic restraints discussed at the beginning. Its consequence would be increasing imports of coal and an increased overall import-share of 70% approx. in the nineteen-nineties. This would have the following negative effects: additional burden to the ecosystem, no relief for the balance of payments, outflow of purchasing power in the view of growing unemployment and last but not least violation of the obligation of a permanently neutral state to direct its energy politics to a maximum of self-reliance. 2.4. The structure of energy consumption: the energetic endure of 682 PJ approx. can be allocated to the major consumer groups as follows: Consumers USES Annual Consumers 41% room and water heating 35,3% Industry 32% industrial thermal needs 27,8% Traffic 27% fuel for vehicles 24,2% mechanical work 10,3% light, communication and EDP 2,4% 100% 100,0%

Since about 50% of the population live in communities not larger than 5.000 inhabitants and since in industry smaller enterprises dominate also, Austria has a

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realistic chance to open the thermal market for biomass without inadequate direct transport costs and logistics as well as expensive investments in a new infrastructure for the transport of biomass. Austria also can step gradually into the market of fuels for motor vehicles since she has a great tradition in fermentation techniques (production and equipment), an evident need to find an outlet for lowgrade crops (due to climatic risks) and an industrial infrastructure with which production facilities can be easily associated. 2.5. Forestrial resources (wood): Approx. 40% of Austria’s area are covered with forests. Therefore, wood has to be an essential resource. This proportion is fortified by the following facts: The last thinning report shows a thinning deficit of 28,5 mill. c.m. of stock. The proper use of thinning wood is direct combustion in the form of wood chips. If the power of resistance to infections is impaired by immissions, forestrial hygiene becomes more important. Thus, the use of thinning wood has also a sanitary aspect. Forestrial plant breeding was a stepchild up to the last decade. The genetic potential is thus underused. The selection of species is still far from being the best. 64% of the population of trees are spruce. The native spruce as a postglacial plant has to be bred to be able to take advantage of the higher temperatures now prevailing. More deciduos trees have to be introduced into the population. The use of non arable enclaves, slopes and boundary lines for firewood production has practically been abandoned for the use of cheap fossile fuels. There is also a large deficit of knowledge and practice in forest fertilization. Thus a national planning scenario can count with the fact, that—all necessary measures being taken—Austria could double her forestrial production in the forseeable future. The main condition for this proposition is, that forest dying will be stopped by imposing the inevitable restraints to all causes of immissions. 2.6. Agricultural resources: Austria can already fully cover her nutritional needs from domestic production. Imports of plant protein and plant oil are due to price distortion in relation to carbohydrate rich plants. The assessment of the genetic potential which can be activated shows that a doubling of production is possible within the next 30 years. ACHIEVABLE YIELDS (GENETIC POTENTIALS) ACCORDING TO ESTIMATIONS OF THE INSTITUTE FOR PLANT CULTIVATION AND BREEDING AT THE AGRICULTURAL UNIVERSITY OF VIENNA AUSTRIA CROP in tons/ha

GRAIN CORN POTATOES BEETS

ESTIMATED POTENTIAL YIELDS 12–15 4 ACTUAL YIELDS

16–25 6,5

80–100 24,6

120 43

The additional volume of production, which can be achieved, could therefore be dedicated to technical—especially energy—uses. Irrigation is another productivity booster since water is normally a minimum factor in Austria. A wider crop rotation will also foster the natural fertility of the soil. In grain

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breeding emphasis can be put on straw as a desired by-product (so far we had the opposite breeding aims). 2.7. Forestrial and agriculturalresources seen thogether: We have seen that forestrial and agricultural productivity can be doubled. Since Austria has a primary energy consumption of 918PJ, which can still be reduced by sensible energy saving measures, and since the production of biomass is larger than 1.000PJ, we can draw the conclusion that all energy needs would be met out of biomass, if we fostered this aim. For the proper assessment of possible forestrial and agricultural productivity improvements of the leaf-area-index and of the efficiency of photosynthesis itself, have to be taken into account.

3. An adequate strategy for the use of domestic biomass 3.1. General considerations: If we recall, that according to the quantitative nature of light we can apply the Carnot-formula in order to estimate the proportion of useful work light can in principle be converted into, we find 95%!

Having an influx of solar radiation of 40.000KW approx. per inhabitant, of which 20.000 KW reach the surface of the earth, and an average European energy consumption of about 4.000KW, the use of solar energy is not a question of the potential—as it is often said—but of the best pathways to be chosen. We certainly have to further develop the solar thermal and the solar electric options. In both cases we have an energy storage problem, which is widely unsolved. The solar chemical option is so far practicable in the field of biomass only. Biomass has the advantage of a solved storage problem and of the possibility to work within the gentle pathways nature has developed for us. 3.2. Sensible pathways: 3.2.1. Teleheating systems for small communities: Larger boilers can be better equipped, they cause less emissions and have a higher efficiency (up to 85%). In addition, they bring more convenience to rural communities. According to the state of technique, optimal straw combustion demands a dust burning system. As a consequence, boilers smaller than 1MW are too expensive. Thus small teleheating systems should be given preference. 3.2.2. Individual heating: If cooperative heating is not possible—e.g. in scattered farm houses—individual heating systems are justified. According to the state of technique retorts and stockers fired with fine wood chips are the most convenient and least emissive choice. The good old tiled stove also compares favourably. 3.2.3. Substitution of electric heating: Water power suffices for the electric power needs of Austria (light, telecommunication, EDP and electrodynamik use). Electricity for heating purposes is mainly produced by thermal power stations. They have an efficiency of 40% approx. and are used only when the weather is

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cold. Thus it is reasonable to build up cheaper biomass firing systems instead of investing into electric power plants. 3.2.4. Industrial heating systems: Especially for enterprises in rural areas biomass is an apt source of energy. By coupling heat and electricity production (which can also be done in local teleheating systems) they can contribute to both forms of energy. 3.2.5. Biomass as a fuel for combustion engines: 3.2.5.1. Ethanol (“Biosprit R”): Rising productivity and a rising surplus of grain (at present 800.000 tons/ a year) as well as the necessity to find an outlet for low grade crops (especially from regions at a disadvantage) make an ethanol programme a sensible task. DEVELOPMENT OF ENERGY-EXPENDITURE FOR PRODUCING ETHANOL old 1980 1984 HYDROLYSIS FERMENTATION DISTILLATION DIV. TOTAL DISTILLERS WASTE

8,0 0,9 11,0 0,1 20,0 11,0

0,7 0,1 6,0 0,2 7,0 8,0

0,2 0,1 3,0 0,2 3,5 3,9

MJ/l.p.A. MJ/l.p.A. MJ/l.p.A. MJ/l.p.A. MJ/l.p.A. MJ/l.p.A.

In order to avoid mono- or oligocultures, a multiple crop system was developed and by research work energy needs for conversion and production of dried distilleries grain dropped from 31MJ to 7,4MJ to per litre pure ethanol. In order to avoid the inducement of feed lots around the factories, a new hydrolysis process has been tested. It allows recycling of the liquid fraction of the distillers’ waste and the economic production of a dried protein-rich byproduct. This technique gives indirect protection to the mountain farmers, who must earn their living from animal breeding and raising. It also satisfies the environmental target of a waste free production. The overall balance of energy is favourable since the input-output-ratio is 1:4 approx. 3.2.5.2. Plant oil: Plant oils esterified with etanol or methanol are tested fuels for diesel engines. The energy balance is even more favourable than with ethanol. A market for the by-product glycerol has to be developed. Rape and sunflower have been cultivated successfully. 3.2.6. Biogas: Biogas technology is developing rapidly. Owing to the fact that Austria has a small structured farm economy, a cheap standard system for approx. 20 cow equivalents has to be developed.

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4. Energy from biomass and biotechnology Energy from biomass and biotechnology are twins. They are enhancing each other. Considering at the energetic characteristics of biotechnological processes are normally low temperature and low energy input—because the pathways of nature are those of a minimum of entropy—the energy from a biomass programme also has an indirect energy saving effect which should not be neglected. In principle, petrochemistry can be substituted by biochemistry and this will be the future, because the end of the fossile period is foreseeable: It is therefore hard to understand that except for Japan (which again shows the proverbial foresight), European governments—Austria makes no exception—are so reluctant to engage in biomasstechnology. If they spent only one tenth of the funds which have gone into atomic power research (and which have not been repaid) for research in biomass-technology, the necessary progress could be financed easily: There is not much time to lose: The development of high technology on an industrial scale usually takes three generations of industrial investment. This is to say 30 years approx.! But this is just the space of time for which we still have fossile resources for our present style of living. 5. Energy and raw materials from biomass for the sake of nature and man About 200 years ago, agriculture and industry began to go separated ways; the “age of fossile energy” began. Evidently, it is not an “age” but a mere episode in the history of earth. The exhaustion of fossile reserves will be the main problem of our children and the extreme use of fossile energy is detrimental to living beings, which need integrated systems. However, one major effect of the past development is usually forgotten: The nearly exclusive use of cheap fossile energy on the one hand led to industrial accumulations in areas, where fossile energy is easily available, and on the other hand local enterprises were ruined and rural areas depopulated. Besides our ruinous style of covering our energy and raw material needs, these large accumulations of people and industries are the main ecological and social problem of our time. In order to communicate, we need no longer to dwell next to our neighbours’ door and to settle in large accumulations. We have developed telecommunication and traffic to such an extent that we can afford a decentralized style of living without losing information, culture and civilization. What we need is a style of living, respecting the proportions of man and nature, i.e. we have to cover our energy and raw material needs in line with and not against nature (within the biosystem) and we have the obligation to respect the human right for a sheltering and surveyable community. Why do we not start environmental protection at the roots instead of during symptoms by expensive investments? The overall profitableness and the wellbeing of nature and man call for the utilization of biomass.

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References: 1. Biomass for Energy (1984), OECD. 2. Bolhar-Nordenkampf, H. (1984). Faktorenanalyse des ‘Waldsterbens’ aus pflanzenphysiologischer Sicht. Institute of plant physiology, University of Vienna. 3. Eccles, J.C. and Zeier, H. (1980). Biologische Erkenntnisse über Vorgeschichte, Wesen und Zukunft des Menschen. Kindler Verlag, Munich, p.119. 4. Energiebericht und Energiekonzept 1984 der Österr. Bundesregierung. Federal Ministry for Trade and Industry, Vienna (1985). 5. Austrian Forest Stock-Taking 1961/1970–1971/1980. Federal Ministry of Agriculture. 6. Systemstudie Ottenschlag (1983). Austrian Association for Agricultural Research, Vienna. 7. E.Broda (1981). Solar energy in the nineteen eighties, expanded version of a lecture given at the International Atomic Energy Agency, Vienna, in June 1979 p. 19 a.f. 8. Österr. Forschungszentrum Seibersdorf (ÖFZS), (1984). Energie aus Biomasse— Energiebilanzstudie.

ENERGY FROM BIOMASS AND BIO-TECHNOLOGY—THE DIRECT WAY TO WELLBEING OF NATURE AND MAN

1) Structures according to the biological information of man (subtle structured societies with comprehendable authorities and networks of communication as well as socially satisfactory organisation and locally rooted cultures)

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2) Techniques which cover the requirements of small structures and do this in harmony with nature 3) Integrated utilization systems 4) Sound crop rotation 5) Best possible use of the local factors production

SESSION II TECHNICAL SESSION Zur Agrarpolitischen Bedeutung der Ethanolproduktion in der Bundesrepublik Deutschland— K.Meinhold and H.Kögl The Use of Forests as a Source of Biomass Energy— F.C.Hummell The Availability of Wastes and Residues as a Source of Energy— G.Pellizzi The Potential of Natural Vegetation as a Source of Biomass Energy— T.V.Callaghan, G.J.Lawson and R.Scott Photobiology—the Scientific Basis of Biological Energy Conversion— M.C. W.Evans The Biomass to Synthesis Gas Pilot Programme of the CEC: a First Evaluation of its Results— A.A. C.M.Beenackers and W.P.M. van Swaaij Biomethanation, the Paradox of a Mature Technology— E-J.Nyns, M.Demuynck and H.Naveau Novel Methods and New Feedstocks for Alcohol from Biomass— U.Ringblom Use of Algal Systems as a Source of Fuel and Chemicals— E.Bonalberti

ZUR AGRARPOLITISCHEN BEDEUTUNG DER ETHANOLPRODUKTION IN DER BUNDESREPUBLIK DEUTSCHLAND K.MEINHOLD und H.KÖGL Institut für Betriebswirtschaft der Bundesforschungsanstalt für Landwirtschaft Bundesallee 50, D-3300 Braunschweig Bundesrepublik Deutschland Summary 1. Adjustment of agricultural product prices to world market prices and reduction of sugar quotas according to domestic demand are not only favourable from a macroeconomic point of view but also important conditions for the economic viability of renewable resources. 2. In order to minimize the cost of renewable resources compared with fossil substitutes special crops with high yields and efficient technologies of conversion and use are needed. 3. If these conditions are fulfilled, the future development of world market prices of agricultural comodities and energy will decide wether agricultural resources should be diverted into the production of renewable resources. Furthermore, to assess completely advantages and disadvantages of the ethanol production from biomass, one has to analyse too effects on other parts of the economy, on foreign trade as well as on the quality of the environment.

1. PROBLEMSTELLUNG Die Umlenkung von landwirtschaftlichen Ressourcen aus der Nahrungs-mittelproduktion in die Produktion von Energieträgern und industriellen Rohstoffen kann weder lösgelöst vom Hintergrund der EG-Agrarpolitik gesehen werden noch stellen einzelwirtschaftliche Rentabilitätsargumente hinreichende Kriterien für ihre sachgerechte Beurteilung als agrarpolitische Alternative dar. Da die augenblickliche Problemlage der Agrarpolitik der Europäischen Gemeinschaft sowie die Ursachen dafür hinreichend bekannt sind, erübrigt sich zur Begründung dieser These eine Aufzählung aller einzelnen Punkte. Es sollen aber im folgenden diejenigen Gründe genannt werden, die eine Beibehaltung der bisherigen Politik als kaum wahrscheinlich erscheinen lassen, auch wenn dies aus der Sicht einzelner Nationalstaaten unterschiedlich beurteilt wird.

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1. Eine Anpassung von Angebot und Nachfrage nach Agrarprodukten innerhalb der EG kann bei herrschenden Preis-Kosten-Relationen nicht erreicht werden. 2. Ein weiterhin um 20v.H. pro Jahr steigender Finanzbedarf für den EG-Agrarhaushalt steht im Widerspruch zu den Bemühungen, die nationalen Haushalte zu konsolidieren. 3. Steigende Agrarüberschüsse traditioneller Agrarexportstaaten erschweren es der EG, weitere Überschüsse am Weltmarkt unterzubringen. 4. Für die Politiker aller Parteien wird es zunehmend schwieriger, ihre Wähler davon zu überzeugen, daß Aufwand und Ertrag der Europapolitik unter diesen Bedingungen in einem zufriedenstellenden Verhältnis zuein-ander stehen. Es ist deshalb nach Lösungen zu suchen, die die vorhandenen und auch weiterhin wachsenden Agrarüberschüsse volkswirtschaftlich so nutzen, daß die gesamtwirtschaftlichen Kosten ihrer Verwertung minimiert werden. Die Verwendung von Agrarprodukten für Energieträger und industrielle Grundstoffe kann zukünftig ein erfolgversprechender Weg in diese Richtung sein. Denn sowohl im Bereich der Energieträger als auch anderer industrieller Grundstoffe ist—im Gegensatz zum aktuellen Geschehen—wieder mit steigenden Knappheiten und damit steigenden Kosten zu rechnen. 2. ZIELSETZUNG DER VORLIEGENDEN ARBEIT Im Gegensatz zu anderen Lösungsvorschlägen für die Anpassung von Angebot und Nachfrage bei Agrarprodukten weist der von uns vorgeschlagene Weg den Vorteil auf, daß 1. weder der Dirigismus in der Landwirtschaft erhöht wird (Besteuerung von Betriebsmitteln, Erhöhung des Außenhandelsschutzes bei Futtermitteln, Beschränkung der Produktionsmengen, Stillegung von Produktionsfaktoren), 2. noch die Marktkräfte zum alleinigen Mechanismus der Preisbildung werden, wenigstens solange nicht, wie eine alternative Verwendung landwirtschaftlicher Produktionsfaktoren in anderen Wirtschaftsbereichen wenig Aussicht auf Erfolg hat. In unsere Überlegungen nicht einbezogen sind solche Maßnahmen, die durch direkte Einkommensübertragungen oder andere sozialpolitisch wirksame Instrumente den Strukturwandel beschleunigen wollen. Die konkrete Fragestellung dieser Arbeit ist vielmehr, herauszuarbeiten, in welchem Maße Produktpreise und Preisrelationen zu verändern und Produktions- und Verarbeitungstechnologien zu entwickeln sind, damit folgende Ziele erreicht werden: 1. Wettbewerbsfähigkeit der Rohstoffproduktion gegenüber der Nahrungsmittelproduktion auf betrieblicher Ebene 2. Minimierung des Wettbewerbsabstands gegenüber fossilen Substituten 3. Berücksichtigung des Einkommenszieles der Landwirtschaft 4. Versorgungssicherheit bei Nahrungsmitteln 5. Keine Erhöhung der gesamtwirtschaftlichen Kosten der Agrarpolitik

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3. BESCHREIBUNG DES VERWENDETEN MODELLS UND DER ZUGRUNDELIEGENDEN ANNAHMEN Für unsere Überlegungen zur Wettbewerbsfähigkeit der Produktion von nachwachsenden Rohstoffen benutzen wir eine Kette von Modellansätzen, angefangen von der einzelbetrieblichen Analyse über die Regionalanalyse bis hin zum sektoralen Ansatz einschließlich eines Modells der deutschen Mineralölwirtschaft. An dieser Stelle wird, da die agrarpolitische Perspektive im Vordergrund steht, ausschließlich der sektorale Ansatz zur Diskussion gestellt. Dabei beschränken wir uns auf die Betrachtung von Ethanol als nachwachsenden Rohstoff, da eine vergleichbare Datenbasis für die anderen Rohstofflinien bisher noch nicht vollständig erarbeitet werden konnte. In diesem Modell ist der Sektor Landwirtschaft nicht deckungsgleich mit dem in der volkswirtschaftlichen Gesamtrechnung verwendeten Begriff, da einzelne Teile entweder ausgeschlossen sind (Sonderkulturen) oder vor- und nachgelagerte Wirtschaftssektoren vollständig oder teilweise einbezogen sind (Herstellung von Mischfuttermitteln, Verarbeitung vom Agrarprodukt zu Nahrungsmitteln). Dieses Modell stellt einen Optimierungsansatz dar, bei dem Anpassungen an veränderte Rahmenbedingungen ohne Zeitverzögerungen erfaßt werden und selbst marginale Differenzen ausreichen, um eine Reaktion herbeizuführen. Mit Hilfe dieses Modells wollen wir die folgenden Fragestellungen beantworten: 1. Beschreibung der heutigen Situation (Basis 1984) 2. Fortschreibung der heutigen Situation bei anhaltendem technischen Fortschritt bis hin zum Jahr 1990 (0-Variante) 3. Bestimmung von Preisniveau und Preisrelationen zwischen Nahrungsmitteln und Nichtnahrungsmitteln für das Jahr 1990, bei denen die Ethanolproduktion eine wettbewerbsfähige Produktionsalternative wird (1. und 2. Variante) Im folgenden sollen stichwortartig die wichtigsten Annahmen genannt werden, ohne die das Verständnis der Modellergebnisse unvollständig bleiben muß. 1. Fortschreibung der naturalen Erträge entsprechend dem Trend (s.Anhang Übersicht 5) 2. Annahme einer “normalen Preisentwicklung” auf den Weltmärkten für Agrarprodukte und Energie, einer realen Verteuerung von industriellen Vorleistungen und einer marktorientierten EG-Agrarpreispolitik (s.Anhang Übersicht 6) 3. Konstante Nachfrage nach im Inland erzeugten Nahrungsmitteln 4. Beibehaltung der bisherigen Handelsbeziehungen mit Agrarprodukten zwischen der Bundesrepublik Deutschland und anderen EG-Mitgliedsstaaten 5. Marktordnungskosten definiert als Differenz zwischen Interventionspreis und Weltmarktpreis.

4. ERGEBNISSE Die Fortsetzung der bisherigen Preispolitik führt bei steigenden Erträgen, trotz steigender Betriebsmittelpreise, zu einer erheblichen Steigerung der Getreideproduktion (siehe Übersicht 1 und 2, Basis 1984 und 0-Variante). Diese Tendenz drückt sich in einer

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Zunahme der Weltmarktexporte von Getreide um+179v.H. bzw. einer Steigerung des Selbstversorgungsgrades der Bundesrepublik auf 120v.H. aus. Das Sektoreinkommen steigt ebenfalls an, und zwar hauptsächlich verursacht durch Ausdehnung der Exporttätigkeit (+39v.H.) sowie Einsparung bei den Vorleistungen infolge effizienterer Produktionstechnik. Damit geht ein Anstieg der Marktordnungsausgaben für Getreide um +177v.H. einher, von +22v.H. bei Milch (sinkende Magermilchverfütterung) und von +28v.H. bei den Ölsaaten (Produktionsausdehnung). Insgesamt erhöhen sich die Marktordnungsausgaben bei dieser Variante um +68v.H. gegenüber der Basis 1984, wogegen das sektorale Einkommen lediglich um +15v.H. ansteigt. Projektion 1990 Ubersicht 1: Vorleistungen, Produktionswert und Basis Marktordnungskosten 1984 0 1 Variante Variante Deckungsbeitrag insg in Mrd DM Vorleistungen ″ ″ Verkaufe Inland ″ Verkaufe Ausland ″ Stutzung Getreide in Mio DM ″ Zucker ″ ″ Milch ″ ″ Olsaaten ″ Summe Marktordnungskosten ″ Stutzung Getreide in DM/ha

20,64 29,75 44,62 5,77 413 121 641 192 1367 945

23,66 29,54 45,18 8,01 1144 121 781 245 2291 928

20,85 27,85 42,47 6,22 323 – 781 122 1226 453

Ubersicht 2: Bodennutzung und Getreidebilanz Basis 1984 Projektion 1990 0 Var. 1.Var. Landw. genutzte Flàche in 1000 ha Ackerflàche ″ Dauergrunland ″ Getreide insgesamt ″ Zuckerruben ″ Kartoffeln ″ Ölfrúchte ″ Futterfrúchte ″ Getreidebilanz in 1000 t Aufkommen. Erzeugung+ Saldo Außenhandel ″ Verwendung: Saatgut, Schwund, Ernährung, ″ Verfütterung Überschuß ″ ″ in 1000 ha Futterimporte ohne Getreide in 1000 t

11 551 11 076 10 445 7 111 7 055 7 055 4 440 4 021 3 390 5 371 5 422 5 171 355 334 285 220 209 209 232 280 280 932 810 906 28 206 31 570 30 434 25 694 24 560 25 847 2 512 7 010 4 587 436 1 171 736 6 807 7 114 5 785

Die Schlußfolgerungen aus dieser Entwicklung sind folgende: sowohl die Getreidepreise als auch die Ölsaatenpreise und die Quoten für Zucker sind der künftigen Marktlage besser anzupassen als dies heute der Fall ist. Dieser Ansicht hat sich auch die Kommission der EG angeschlossen, indem sie bei Überschreiten bestimmter Zielmengen für Getreide und Ölsaa-ten eine nominale Preissenkung für diese Produkte festgelegt hat.

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In Analogie dazu haben wir für das Jahr 1990 folgende Annahmen über Agrarpreise, Quoten und Produktionstechnik getroffen (s. Anhang Übersicht 6): 1. Reduzierung der Interventionspreise für Getreide auf 80v.H. des heutigen Niveaus 2. Reduzierung des Interventionspreises für Raps auf 85v.H. des heutigen Niveaus 3. Kürzung der A- und B-Quote für Zucker auf das Niveau des heutigen Inlandverbrauches 4. Beibehaltung der derzeitigen Preis- und Mengenregulierungen bei Milch-und Rindfleisch 5. Annahme, daß Kostensenkungen in der Schweinemast, der Geflügel- und Eierproduktion, verursacht durch verminderte Getreidepreise, in den Erzeugerpreisen zumindest teilweise weitergegeben werden 6. Bereitstellung von Produktionsverfahren zur Biomasseproduktion Diese Annahmen führen bei unveränderten sonstigen Nebenbedingungen und zunächst ohne die Möglichkeit der Ethanolproduktion zu folgenden Ergebnissen (s. Übersicht 1u. 2, 1. Variante). Der sektorale Deckungsbeitrag sinkt gegenüber der 0-Variante ab und erreicht fast das Ausgangsniveau des Jahres 1984. Der Produktionswert der am Inlandsmarkt absetzbaren Güter vermindert sich um 5v.H. gegenüber der Basis 1984. Dies bedeutet trotz Erhöhung des Selbstversorgungsgrades bei Schweinefleisch von 87 auf 95v.H. nichts anderes als eine Entlastung der Verbraucher. Der Getreideexport geht auf 65v.H. der 0-Variante zurück und beträgt, gemessen in Flächenäquivalenten, nur noch 736.000ha. Die Marktordnungskosten sinken infolge des Wegfalls der Zuckerüberschüsse und der verminderten Preisstützung bei Getreide sogar unter das Niveau der Ausgangssituation von 1984. Die Einführung der Produktion von nachwachsenden Rohstoffen, hier dem Ethanol, wird auf folgende Weise vorgenommen: Bei den getroffenen Annahmen über Produktpreise, Produktionsquote und Konversionstechnologie reicht ein Verkaufspreis von 1,00DM/l Ethanol aus, um eine Produktionsmenge von 890.000m3 Ethanol bereitzustellen (s. Übersicht 3). Dies entspricht 5v.H. des 1983 in der Bundesrepublik verkauften Superbenzins. Insgesamt steigt der Deckungsbeitrag um 13Mio DM an, was in bezug auf die produzierte Menge Ethanol nur eine marginale Veränderung darstellt. Deutlichere Veränderungen ergeben sich bei den Vorleistungen, die um +415Mio DM ansteigen, und beim inländischen Produktionswert (+890Mio DM). Da die Ethanolproduktion ausschließlich Getreide verdrängt, das bisher auf den Weltmarkt exportiert wurde, sinken auch die Marktordnungskosten für Getreide, und zwar um 72Mio DM. Das sind, bezogen auf den Hektar Rohstofffläche, 343DM bzw. 81DM je produzierten Kubikmeters Ethanol. Werden diese eingesparten Marktordnungskosten für die Preisstützung von Ethanol verwendet, so betragen die Nettoherstellkosten 919DM/m3. Bei den getroffenen Annahmen über die Weltmarktpreise für Getreide und Energie hängt die relative Vorzüglichkeit gegenüber einer exportorientierten Getreidepolitik weitgehend vom Substitutionswert des Ethanols ab. Da dieser Wert seinerseits weitgehend unternehmensspezifisch determiniert ist, sind hier drei Varianten aufgeführt und hinsichtlich ihrer haushaltswirksamen Konsequenzen mit dem Export von Überschußgetreide verglichen (Übersicht 4).

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Ubersicht 3: Auswirkungen der Ethanolproduktion auf Bodennutzung, landw Einkommen und Marktordnungsausgaben

ETOH-Produktion 1000m3 Getreide insgesant 1000 ha Zuckerruben ″ Kartoffeln ″ Futterfruchte ″ Rohstoffflache 1000ha Sektoraler Deckungsbeitrag Mio.DM Vorleistungen ″ Verkaufe Inland ″ Verkaufe Ausland ″ Marktordnungskosten insg Mio. DM Uberschußflache 1000ha MO-Kosten je ha Uberschußflache Eingesparte MO-Kosten je ha Rohstoffflache Eingesparte MO-Kosten je m3 Ethanol Nettokosten Ethanol DM/m3

Ubersicht 4: Wettbewerbsstellung von Bioethanol im Kraftsfoffbereich

97

Projektion 1990 Veranderung gegenuber 2 1. Variante Variante 890 4 961 366 224 1 223

−210 +81 +15 +114 210 +13 +415 +890 −462 −72 −182

20 862 28 261 43 366 5 757 1 154 554 453 343 81 919

Modellannahme 1990

Nettokosten Ethanol DM/m3 919 (Herstellkosten-eingesparte MO-Kosten) Raffinerieabgabepreis fur Superbenzin DM/m3 770 Subshtitutionswert von Ethanol 2) 770 8091) Differenz DM/m3 149 110 Verwendungsbeihilfe DM/ha Rohstoffflache 3) 631 446 +Preisstutzung aus eingesparfen MO-Kosten DM/ha 343 343 Rohstoffflache =Gesamte Stutzung DM/ha Rohstoffflache 974 809 −Preisstutzung Exportgetreide 453 453 Wettbewerbsdefizit DM/ha Rohstoffflache −521 −356 1) Preis Superbenzin×1,05 (entspricht Preis von TBA) 2) geschatzt Preis Ethanol=Preis Superbenzin+(Pr Superbenzin−Pr Normalbenzin) 3) 4.24m3 Ethanol/ha Rohstoffflache

835

8352) 84

770 835 –

356 343

– 699

699 453

699 783

−246

+84

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5. SCHLUSSBETRACHTUNG Die bisher berichteten Ergebnisse aus den Modellkalkulationen lassen sich aus gesamtwirtschaftlicher Sicht wie folgt zusammenfassen: Geht man davon aus, daß die Preise für Energieträger langfristig schneller steigen als es bei den Agrarprodukten der Fall ist, so ist es eine Frage der Zeit, bis die Wettbewerbsfähigkeit der Ethanolproduktion erreicht ist. Für die Finanzierung der bis dahin erforderlichen Stützungsbeträge von hier 52bis 109Mio DM pro Jahr wären folgende Denkansatze möglich: – Durch die Landwirtschaft: Beispielsweise mit einer Abgabe in Höhe von 0,34bis 0,71DM/dt auf den bisher unverändert gelassenen Preis von 11,13DM/dt Rüben innerhalb der A- und B-Quote. Das würde gleichzeitig auch eine bessere Anpassung der Preisrelation gegenüber Getreide bedeuten. – Durch den Finanzminister: Mittels Steuerminderung für ethanolhaltige Kraftstoffgemische, die geringer sein könnte als es dem verminderten Heizwert entspricht. Dem stehen zusätzliche Steuereinnahmen aus einer verstärkten Nachfrage nach gewerblichen Vorleistungen in Höhe von 415Mio DM, das sind rund 2.000DM/ha Rohstofffläche, gegenüber. Der Saldo aus beiden Positionen entspricht der effektiven Steuerveränderung, dessen genaue Ermittlung an dieser Stelle noch nicht möglich ist. – Durch den Konsumenten: Durch eine Preiserhöhung von 0,42bis 0,75Pf/l Kraftstoffgemisch bei 5v.H. Mischungsanteil. Da Ethanol sauberer verbrennt als Kohlenwasserstoffe, wäre auch hier ein Gegenwert vorhanden, dessen Quantifizierung bekanntermaßen nicht leicht fällt. Eine über die eingesparten Marktordnungskosten hinausgehende Verwendungsbeihilfe für Ethanol wäre im Rahmen des vorgestellten Modelles bereits 1990 nicht mehr erforderlich, wenn entweder das Weltmarktpreisniveau für Getreide auf ca. 80v.H. der hier unterstellten Annahmen absinkt oder aber ein ausreichend hoher Substitutionswert für Ethanol erzielt werden könnte. Weiterhin muß daran erinnert werden, daß Marktordnungskosten hier lediglich Exporterstattungen umfassen. Bei Einbeziehung aller anderen Marktordnungskosten, vorausgesetzt sie wären eindeutig zuordenbar, würde sich das ausgewiesene Wettbewerbsdefizit noch verringern. ANHANG

Übersicht 5: Entwicklung von Erträgen in der Bundesrepublik Deutschland (Werte in Klammern: jährliche Veränderungsrate) Basis 1984 Projektion 1990 alle Varianten Weizen1) Wintergerste1) Körnermais1) Raps1) Speisekartoffeln1)

: Ertrag t/ha : ″ : ″ : ″ : ″

5,37 5,15 6,45 2,76 30,83

5,88 5,57 7,20 2,92 32,45

(+1,52) (+1,32) (+1,85) (+0,94) (+0,86)

Zur agrarpolitischen bedeutung der ethanolproduktion in der bundesrepublik deutschland

Ethanolkartoffeln2) : ″ 40,00 55,00 Zuckerrüben1) : ″ 50,52 53,79 Ethanolrüben2) : ″ 50,52 70,00 Corn-Cob-Mix1) : ″ 11,60 12,96 Milchleistung1) t/Kuh u. Jahr 4,88 5,45 Ferkel je Sau2) 16,20 17,00 Futterverwertung2) in der Schweinemast 1:3,45 1:3,12 1) Trendschätzung basierend auf den Jahren 1949–1983 bzw. 1974–1983 2) geschätzt

99

(+5,45) (+1,05) (+5,59) (+1,86) (+1,86) (+0,81) (−1,66)

übersicht 6: Annahme über Entwicklung wichtiger Preise im Sektor Landwirtschaft (Werte in Klammern: jährliche Veränderungsrate) Basis 1984 Strom Dieselöl N-Dünger P-Dünger K-Dünger andere Betiebsmittel Getreide: Interventions preis Rüben A+B Quote Rapssaat Milch Garantiemenge Schweinefleisch Geflügelfleisch Eier Weizen Mais Gerste Zucker Rapssaat Soja Maiskleber Tapioka

DM/kWh DM/l DM/kg ″ ″

DM/t ″ 1000 t DM/t ″ 1000 t DM/t LG ″ DM/t DM/t ″ ″ ″ ″ DM/t ″ ″

Projektion 1990 0 Variante 1. u.2. Variante Inland—EG

0,20 1,18 1,81 1,30 0,53

0,26 1,26 1,98 1,34 0,56 (+1,0) 438,20 111,30 2 602 ,30 1 005,00 609,00 2 324,80 3 019,00 2 040,00 2 827,00

(+4,1) (+1,1) (+1,4) (+0,5) (+0,6)

350,95 111,30 2 222,00 854,00 609,00 2 324,80 2 700,00 1 763,00 2 444,00

(−3,63) (±0)

(−1,84) (−2,40) (−2,40)

5656) 4276) 3756)

(−1,75) (−1,75) (−1,75)

(−2,67) (±0)

Weltmarkt 3321) 2982) 2663) 4504) 7054) 6285) 474 417

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Heizöl S ″ 500 591 (+3,00) 1) Durchschnitt der Jahre 1977–1983 2) 90v.H. des Weizenpreises unterstellt 3) 80v.H. des Weizenpreises unterstellt 4) geschätzt 5) Durchschnitt der Jahre 1980–1983 6) Preisannahme infolge sinkender EG-Getreidepreise

THE USE OF FORESTS AS A SOURCE OF BIOMASS ENERGY HUMMEL, F.C. Associate Senior Fellow, Centre for European Policy Studies (CEPS), Brussels Summary In Western Europe and in industrialized countries in general, the main source of forest biomass for energy continues to be the residues from conventional logging—tops, branches, bark—as well as trees for which there are no other markets. Crucial to making such operations viable economically is the development of markets very close to the sources of supply because transport constitutes a major component of costs, forest biomass being a bulky commodity of low unit value. Short rotation biomass plantations on bare land are still largely at the experimental stage, at any rate in Europe, Progress has been greater than opponents had predicted, but slower than enthusiasts would wish. The two main lines of development are, first single stem plantations on rotations of 20–30 years which combine timber production with biomass production for energy, and secondly the coppice crops which are usually managed on very short rotations of 2–6 years. In the European Community, our main interest lies in technology that permits viable small scale operations. This is partly for environmental reasons and partly because of the fragmentation of land ownership. The most urgent need in the world for more forest biomass for energy exists in the developing countries where almost half of the world’s population continues to depend on wood fuel for cooking and heating and where rising populations have led to an over exploitation of the forest resource which in turn has caused wood shortages and soil erosion. While more research is needed, especially in arid regions, the main emphasis must be on the application of existing knowledge as an integral part of rural development.

1. INTRODUCTION Wood was at one time man’s main source of energy. It not only provided the fuel for cooking and domestic heating, but also for many industrial purposes such as the smelting of metals, the burning of bricks, the manufacture of glass and the refining of salt. For these industrial uses, wood has been replaced almost completely, by fossil fuels as well as by hydroelectric and nuclear power. In the home wood has also largely been replaced in most developed countries, but in the developing countries some 2000 million people, that

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is nearly half of the world’s population, still depend almost entirely on wood to cook food and keep warm. The present status and future potential of wood as a source of energy, and the priorities for future research and development work in this field, depend not only on technological and economic factors but also on social considerations. Deep-seated human emotions and interests are involved. The problems must also be seen in the broader perspective of the complex relationships between forests, biomass and energy. On the one hand, the production of biomass for energy is only one of several forest functions; forests must also (1) produce timber and fibre for industry, (2) help to prevent erosion, to conserve wildlife habitats and (3) provide opportunities for recreation. On the other hand, forest crops are not the only sources of biomass for energy, though they are among the most efficient in terms of the ratio of energy contained in the harvested crop to total energy input. Field crops such as rape and sugar beet can also be used for energy production. While attempting in this paper to take a global view, the emphasis will be on the European Community (EC). Within the EC there have been a number of forest energy projects paratially funded under the Commission’s Research and Development programme, while others have been undertaken nationally. Some Member States also participate in the relevant activities of the International Energy Association (IEA) and most forest research institutes involved are members of the sub-group concerned in the International Union of Forest Research Organizations (IUFRO). Although the total research effort has been considerable, it falls short of what is being done in North America and Sweden. The developed world will be considered first under two main headings: biomass haravest from existing forests and the afforestation of bare land. The problems in developing countries will be considered separately, because they are so very different. 2. ENERGY BIOMASS FROM EXISTING FORESTS IN DEVELOPED COUNTRIES In developed countries the generation of energy was, until very recently, regarded as a residual use of wood for which there is no other market. The increases in the prices of fossil fuels a decade ago have slightly modified the position, but have as yet brought about no radical change. There are three main sources of wood residues. First, there are the residues from wood processing, some of which may themselves be used industrially as well as for energy. Sawmill residues for example, may be used for the manufacture of pulp or various kinds of wood board panels -particle board, fibre board, etc. The relevant technologies, while no doubt capable of further improvement, are well developed and need not concern us here. Whether it pays a sawmiller to use or sell his residues for the generation of energy or for other purposes, will depend on his particular circumstances. Very few of these residues are wasted. The second source of wood residues is wood that is no longer used for its original purpose, for example the timber in old buildings that are pulled down. This use of wood

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for energy has scarcely begun—at any rate, not in Europe. The difficulties of organising the collection of this wood instead of merely burning it on site are obvious, but the volumes are considerable. At any rate the matter deserves much more attention than it has received. The third and by far the most important potential additional source of residues is the forest itself. Although the EC depends on imports for more than half of its consumption of wood products, millions of tonnes of potential annual wood harvest are left in the forest instead of being utilized. The physical potential is of the order of 5–10 million tonnes per year of oil equivalent. If a significant proportion of this wasted wood could be harvested economically, it would be a worthwhile achievement. The biomass left in the forest consists in the first place of trees of small dimensions or inferior quality for which there are no markets or which do not repay the cost of harvest because of distance to the markets. Transport costs loom large in all forestry operations and they are a decisive factor for material of low unit value. The removal of these trees would also benefit timber production, because the removal of inferior trees reduces competition for the better tres which then grow faster. Where there are no good trees, as in some 6 million ha of neglected coppice in the EC, the harvest of this biomass for energy would at least recoup part of the cost of clearance for replanting. The second component of the unutilized forest biomass are the residues from conventional logging. This logging is generally confined to the stemwood, leaving tops, branches, stumps and roots in the forest and sometimes also the bark, depending on whether logs are debarked in the forest or at the sawmill or other wood-processing plant. There is now a general consensus in the EC that stumps and roots should not be extracted; the risks of damage to the soil are too great. There is therefore no point in pursuing that line of development. On the other hand, there are many sites where the removal of a significant proportion of the biomass in tops, branches and bark is unlikely to cause a reduction in soil fertility or deterioration in soil structure. The main efforts have therefore been directed towards harvesting this part of the biomass. The removal of too much foliage with tops and branches would be harmful because of its high nutrient content. In extreme cases, the drain of nutrients might have to be remedied by the application of fertilizers. The technology of biomass harvest in the forest has followed two main lines. The first is whole tree chipping carried out in the forest. This method is usesd for trees of small dimensions for which there are no better markets. Considerable advances have been made in recent years in the development of suitable machines of various sizes and of logging systems to go with them. of particular interst to us in the EC, for further research and development, are the smaller chippers, especially those powered by a farm tractor. This is because our forests are rarely large and the ownership in these forests is often fragmented. Small operations are therefore the rule and farmers doing this type of work part time are important in some countries. The larger machines too have a role to play in some of our forests but countries with much larger forest resources than countries of the EC are in a better position to take the lead. Two more restricted lines of development must also be mentioned; one is aimed at speeding up the preparation of conventional fuel wood billets for domestic use by appropriate combinations of sawing and splitting mechanisms, the other is the conversion of residues into briquettes for ease of handling.

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The second main line of biomass harvest in the forest is to combine it in some way with conventional logging. One approach has been to load the trees with their tops and branches onto lorries equipped with a device which enables the load to be compressed. Topping, delimbing and debarking is then carried out at the pulpmill, which pulps the stemwood. The biomass that is left is converted into energy for the mill’s own use or for sale either as it is or after conversion to electricity. The other approach is to separate the stemwood from the biomass already in the forest. The first approach is less labour intensive, but is generally suitable only for large logging operations of the type that pulpmills undertake. The second approach is better suited to the woodland owner who sells what he can to industry and converts the rest into biomass for energy if there is a local market for it or if he himself can utilize it, e.g. on a farm or other enterprise owned by him. Given the circumstances of the E.C. the further development of the second approach should receive priority. 3. SHORT ROTATION BIOMASS PLANTATIONS IN DEVELOPED COUNTRIES A complement to using for energy the hitherto unharvested biomass in existing forests is to create plantations on bare land specifically for the purpose of producing the maximum amount of biomass in the shortest possible time and with the minimum input of external energy in the form of fertilizers, fuel for machinery, etc. This technology is still at the experimental stage. The research and development work of the last 10 to 15 years, has been carried out mainly in North America and Scandinavia as well as in some countries of the E.C. It now appears that there is likely to be a limited but very significant role for such plantations. Some of the early claims by the supporters of these plantations have proved to be greatly exaggerated, but so have the fears of the opponents. There can be little doubt now that the development work in this fieldl should be strengthened. Strengthening international cooperation might also prove beneficial. I shall consider in turn the land that might be available for such plantations, the selection and breeding of planting material, treatment of crops and site and finally harvesting, storage and transport. 3.1 The Potential There is no shortage of land for forest energy plantations. According to a recent study prepared under the auspices of the E.C.’s energy from biomass programme, the elimination of surplus agricultural production in the E.C. alone would release for other use 8 million ha. of land as well as the enormous farm subsidies that are spent on this surplus production. The area of land that is surplus to agriculture will continue to increase because productivity per unit area is still rising and will go on doing so, unless there is a switch to new forms of low input—low output farming. There are several claims on the surplus land apart from forestry. Urban developments, nature conservation and recreational facilities may also require more land. About 6 million ha of the surplus land are devoted to meat and milk production and it is some of this that would be most

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suitable for forestry in some form. The other two million ha are under cereals and other agricultural crops. Some of these latter areas might be considered for agricultural energy crops. In Sweden, where the question of forest energy plantations has been studied more thoroughly than in most countries in Europe, million ha of land have been identified as physically suitable for the purpose of which about one million ha might become available in practice. In North America there is obviously no shortage of land, quite apart from the areas no longer needed for agriculture. Estimates of potential yields vary considerably. With existing technologies yields of about 8 tonnes of dry matter/ha/yr are achieved in practice over large forest areas in Western Europe. That is equivalent to about 3 tonnes of oil. Yields twice as high have been achieved on limited areas and potential yields in the range of 25–30 tonnes of dry matter/ha/yr are considered achievable in due course, given an adequate input of further research. The economic potential of energy plantations is even more difficult to assess than the physical potential. According to some estimates, yields of at least 15 tonnes of dry matter/ha/year are necessary to make energy plantations an economically viable proposition; but these estimates do not take into account that the opportunity cost of such plantations may be very low if they are on land now used for highly subsidized surplus production of milk and meat. It also seems probable that research will not only lead to an increase in yields but also to a reduction in costs. Research on energy plantations has followed two main lines. First there are the very short rotation plantations managed on a 2–6 year rotation. They usually consist of broadleaved species which coppice (i.e. regrow from the stumps after being cut over). Then there are the single stem plantations which may be of either coniferous or broadleaved species; they are generally regenerated by planting and managed on 20–30 year rotations. Present indications are that there is a future for both types of energy crops. The longer rotation crops have the following advantages: – the technology is already better developed; that applies particularly to the harvesting and conversion to energy, but also in some measure to the silviculture; – part of the produce can be used for sawmilling or pulping as well as for energy; this improves the income from these plantations because industrial wood, especially sawlogs, generally fetch a higher price than fuelwood; – in some areas they are considered preferable on environmental grounds—more pleasing in the landscape, less need for fertilizers, better habitats for wildlife etc. – if the alarming dying of old forest stands in Germany and elsewhere continues, there will be an urgent need to plant fast growing timber trees to ensure future supplies. The main advantage of the very short rotation crops on the other hand, lies in the fact that the time interval between establishment and harvest is so much shorter. The early harvest is especially important for farmers who wish to switch part of their land to the production of energy for use on the farms. They are rarely willing or able to forego income from their land for more than a very limited period; moreover, the cultivation of very short rotation tree crops is more closely related to farm practices than more conventional forestry, an important consideration in countries where there is no forestry tradition

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among farmers. In this context the proposal by the EC Commission must be warmly welcomed, that farmers who embark on forestry should receive for a number of years a subsidy to replace the subsidies which would have been payable under agricultural use of the land. It would obviously be premature to set any targets for wood energy production from afforestation, but even a very modest achievement of an annual production in the EC of 5–10 million tonnes of oil equivalent, would double the amount available from forest residues and would make a major impact on the economies of the rural areas where this production would be concentrated. 3.2 Selection and Breeding The selection of species and the selection and breeding of clones within species has made considerable progress in recent years and has been boosted by the cooperation that has developed between research workers from different countries. This cooperation has been encouraged by international organisations including, apart from the EC, the IEA, FAO and IUFRO. Most of the research has been empirical but research on the use of advanced technologies, such as propagation by tissue culture, is on the increase. There appears to be a need at this stage to support the existing effort with more fundamental research, taking advantage as far as possible of work already done on plants other than trees, e.g. on problems of photobiology. Most of the work on very short rotation coppice crops has been concentrated on the genera Salix and Populus. The genus Alnus has been found useful on some wet and nutrient-poor soils (NOT peats), but its very capacity for nitrogen fixation diverts energy from production. Where climatic conditions have been suitable, genera such as Eucalyptus have also received some attention. Some very promising clones for particular sites have been identified, but experience has already shown that some clones do not keep their early promise and that they are too site specific. Good progress has also been made with testing for disease resistance. The testing of new clones for resistance to bacterial canker in poplar is now done on a coordinated basis in the EC, in a programame launched with financial support from the EC Commission. Some conifers such as Picea sitchensis, when planted at very high densities and cut over on a 2–6 year cycle, have also given high yields of biomass comparable to those of the broadleaved species, but the cost is high and the disadvantage that conifers do not coppice is accentuated on these very short rotations and it seems doubtful whether there should be much further effort in this direction. For single stem plantations on rotations of 20–30 years, the choice of species is somewhat wider. Broadleaved genera, such as Betula and Prunus deserve mention as well as some species of conifers. In Ireland for example, high yields are achieved with Picea sitchensis which is also an excellent timber tree, and with some provenances of Pinus contorta which regenerates naturally on some sites. 3.3 Management and Harvesting Very short rotation coppice stands resemble agricultural crops rather than forest plantations in their high demands on site, need for fertilizers and drainage, suppression of

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weeds and intensive capital and labour input. The spacing of the crop too is very important so as to make best use of the site while at the same time permitting access to the machines used for the various tending operations and the final harvest. Much progress has been made on these questions in recent years and, while much research remains to be done, sufficient is now known to embark on substantial pilot operations as an essential link between research and practice and also in order to provide the basis for testing harvesting machinery. Apart from some short term problems, such as weed control and uncertainties which can only be resolved in the longer term such as the longevity of coppice stools under very short rotations, by far the most serious problem is presented by the harvesting of the biomass. As far as I know, there are as yet no satisfactory machines for larger scale harvesting operations. The main efforts to solve this problem are being made in North America. In the EC our main interest lies in the improvement of intermediate technology suitable for smaller scale operations. The single stem plantations on 20–30 year rotations present fewer management problems because well tried practices of conventional forestry can serve as a guide, even if they require some adaptation. That applies to the treatment of the site, the tending of the crop and also to its final harvest and conversion to chips. 4. FOREST BIOMASS IN DEVELOPING COUNTRIES Only a few general remarks on this vast subject are possible in the present context. The situation was summed up at a meeting convened by FAO in Rome in 1982 as follows: “Excessive wood removals, fuelwood and charcoal mostly for domestic use, are a factor of degradation, above all of open forest formations. Studies carried out by FAO on the fuelwood situation show, that three quarters of the population in developing countries—2000 million people—depend on fuelwood and other traditional fuels for their daily energy needs. 100 million people are living in such scarcity situations, that they cannot obtain sufficient supplies to meet their daily energy needs: a further 1000 mio rural dwellers suffer increasing shortages and can meet their minimum needs only at the expense of exhausting available resources. The developing world as a whole suffers a deficit of 400mio cbm of fuelwood to supply the minimum needs of people depending on this fuel.” What do these statistics signify in terms of human misery for the myriads of villagers engaged in collecting the fuelwood from ever greater distances as the nearer forests are exhausted and disappear? Often it is the women and children who have to spend hours each day collecting and carrying the wood. The food is then cooked on primitive stone hearths which use only 5–8% of the wood’s energy. Furthermore, the over-exploitation of the forests leads to soil degradation and erosion and so to poorer farm crops and pastures which, in turn, lead to further over-exploitation of the soil and erosion. Some remedial measures have been taken, but they need to be pursued with far greater urgency. They include

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(i) Making better use of the fuelwood by promoting the introduction of more efficient stoves. This can immediately cut fuelwood consumption to less than one half. Some good designs have been developed which are inexpensive, can be made locally and are adapted to local customs. What is now needed is to make these designs more widely known and used. (ii) The protection of the remaining forest areas—often open savanna or scrub—against avoidable destruction by uncontrolled grazing, fire etc. This is only possible with the full cooperation of the inhabitants. This cooperation can only be expected in the broader context of the introduction of better farm practices including, where appropriate, various systems of agroforestry. (iii) The production of fuelwood by agroforestry as well as in pure fuelwood plantations within easy reach of the villages. Experience has shown that these measures are most likely to succeed if they form part of a general improvement of rural land use and if they also supply other forest products for domestic use such as timber for construction and fodder for cattle. The urban and industrial role of fuelwood in developing countries must also not be ignored, especially the supply of charcoal in countries without fossil fuels. The urgency of immediate action based on existing knowledge must not obscure the vast field of research and development work that requires attention. Some very high yielding fuelwood species which can be grown on very short rotations of 1–4 years where there is adequate rainfall, have already proved their worth. Leucaena leucocephala (ipilipil) is one of the better known examples. Unfortunately, as with some other “wonder trees”, its very success has led to it being planted in some countries on sites for which it is not suited. Far less work has been done on the selection and cultivation of species which are suitable for semi-arid and arid conditions where the fuelwood shortage is often most acute. Another priority in developing countries must be the cultivation and use of forest based energy to replace fossil fuels for the generation of electricity for industrial use and for domestic consumption in towns. There are of course countries where land shortage is a serious obstacle to any such developments. 5. THE WAY AHEAD Looking to the future, there can be little doubt that forest based energy will have an increasingly important role to play, given an adequate effort and a sensible approach by those concerned. Many detailed decisions will be required and only a few general conclusions are justified at this stage. 1. There is little point in trying to allocate priorities between the main lines of action discussed because they complement one another; moreover, they often involve different experts, different institutions and different sources of funding. – The greater use of residues from conventional logging gives immediate results and is already technologically and economically achievable. – The afforestation of bare land in developed countries will not only add to the production of timber and biomass for energy, but will also help to solve the problems

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associated with surplus agricultural production. Some of the balance of advantage at present appears to lie with single stem plantations managed on rotations of 20–30 years for the production of both timber and biomass but, taking a longer term view, there is also a strong case for pursuing with greater vigour the development of the energy plantations grown on very short coppice rotations of 2–6 years. – Finally, there is the gigantic problem of remedying the immediate shortage of wood fuel of well over one third of the world’s population in the developing countries. 2. Within each line of action, priorities must depend on the stage of development reached. It would appear for example, that in the utilization of forest residues, while the development of better machines must go on, the emphasis should now be on case studies, pilot schemes and demonstrations of logging systems; the further development of very short rotation plantations, on the other hand, is likely to require much more support from fundamental research. 3. Priorities must also depend on local circumstances. Thus, in the EC the pattern of land ownership and environmental considerations dictate that we accept that ‘small is beautiful’. It is up to us to ensure that small is also practicable and economically viable. 4. Progress in the application of biomass for energy, including forest biomass, will largely depend on: – soundly based research; in the past some exaggerated claims were due to defects in experimental methodology. – sound economic evaluations of forest biomass production and utilization. – good contacts between all concerned at both national and international level. The EC research and development programme in this field can make a major contribution to these objectives.

THE AVAILABILITY OF WASTES AND RESIDUES AS SOURCES OF ENERGY G.PELLIZZI Institute of Agricultural Engineering University of Milan Summary The report is organized in three sections. The first section contains an exhaustive analysis of the actual availability of rural (agriculture, forestry, food technology industries and civil) byproducts and residues of the EEC Countries (some 90 million tons/y-TS). The second section discusses an energy evaluation procedure based on the calculation of the residue’s energy return in relationship to the conventional technologies to be replaced (25 Mtoe/y). The third section is a review of the existing mechanization chains for collection, loading, conveyance and pre-treatement of byproducts and of the problems to be solved for an effective utilization of such by products and residues for energy purposes. Two annexes follow.

1. INTRODUCTION The subject matter of this report had been discussed at the 1st EC Conference on Energy from Biomass (Brighton, Nov. 1980), where some significant methodological contributions were made. Later, a rather exhaustive book by Palz and Chartier was published. Thus, dealing further with this topic might appear redundant, especially since additional research has been carried out in the past four years on the available and recoverable amounts, chiefly of cereal straw. Nevertheless: – The sources do not agree on specific (t of total solids -TS- per ha or per head of livestock) and total amounts, nor on the actual amounts recoverable for energy conversion after deducting what is currently being used for other purposes; – A clearcut evaluation methodology is as yet lacking; – Scanty data are available on agricultural and non-agricultural byproducts other than cereal straw; – In the meantime, modern recovery and energy conversion techniques and technologies having been developed, the actual energy contribution of the various byproducts can be assessed more accurately; – The structural characteristics of the various crops evolve continuously (suffice to recall that the height of soft wheat has dropped by some 30% in 30 years);

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– Alternative uses are being developed for vegetal byproducts (treating straw with NAOH or NHm and use of maize stalks for fodder etc.); – There is growing demand for biomass (chiefly straw and wood residues) energy conversion technologies. In 1983 for instance, some 300,000 straw burners were in operation in Denmark, 3,500 in France and barely some 20 in Italy; by late 1984, the situation changed and a few thousand straw burners are now operating in Italy, where approximately sixty firms make straw and wood burners for a growing international market. 2. AVAILABLE WASTE AND RESIDUES 2.1—Therefore, there is scope to update periodically the evaluations and methodologies and to reassess the conventional energy replaceable by the various byproducts. For the above reasons, the data on available agricultural (vegetal and animal) biomass in the EEC countries needed updating. Available biomass here means the amount of TS that is actually usable for energy purposes, after deducting present alternative uses insofar as information thereon can be gleaned from the literature. The results of these calculations, obtained from Eurostat data by the procedures illustrated in Annexes 1, 2, are contained in Tables 1 (vegetal byproducts) and 2 (animal byproducts). The tables also contain the energy density, in replaceable toe per km useful farming area and per rural area dweller. It can be seen that upwards of 90 million t/y of byproducts (expressed in TS) are available; density ranges, according to the country, from a minimum 42 to a maximum 225t/km2 useful farming area or from 1.7 to 6.1 per dweller. 2.2—The effluents of produce processing plants, which are often scattered throughout the rural area, the residues of wood harvesting and processing and the household solid waste of the rural populations should be added to the locally available and locally usable agricultural byproducts (for which a more thorough analysis, based on areas of 10 to 15km square, will be in order). It will thus be possible to assess more reliably the energy demand-and-supply ratio of agriculture. Unfortunately, information on the above three classes of byproducts is rather scanty and a coordinated, in-depth investigation in every country involved is called for. Since the amounts involved are quite significant, we submit here a tentative global evaluation covering the 10 EEC countries. The amount of waste from the produce-processing industry was calculated by a conservative extrapolation of the values determined in Italy for the various industrial branches and attributing an average 1.2t TS waste per million ECU added value; only plants located in rural areas were considered. This simplified procedure yields a total available amount of 25–30Mt TS per year for whole European Community. Wood residues instead come from both forest cutting and the wood processing industry. Here too scanty specific data exist, with the exception of what can be gleaned from the mentioned work by Chartier & Palz. A conservative reassessment of the data therein shows the actually recoverable wood byproducts to be approx. 20Mt TS per year, 70% of which in France and Germany.

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Finally, household waste amounts to 0.3t per dweller and year (at some 30% TS, recoverable for energy purposes), and the total amount lies around 5Mt TS/y. Total EEC availability thus is of the order of 140Mt/y, 65% of which of agricultural origin; the corresponding density lies slightly below 140t TS per km useful farmland, with a probable peak of 300t/km in some countries. 3. AVAILABLE ENERGY 3.1—The amount of conventional energy that can be replaced by the above byproducts was calculated by the procedures outlined in the Annexes. This amount is defined “energy return” and is based on the number of toe effecticely replaceable by 1t TS of the biomass considered. The calculation procedure adopted is based on determining, for each biomass: i) the energy content (E) per kg TS biomass ii) the energy cost of biomass (C): energy outlay per unit biomass (or unit fluid fuel obtained) delivered at conversion plant inlet; iii) the replacement energy value of biomass (V): amount of conventional energy that biomass can replace at user point, with various conversion technologies; iv) the energy return of biomass (P): difference between value and cost. Specifically: The energy content (E) of biomass represents the energy that can be theoretically obtained from 1kg TS. This has to be calculated: – as concerns byproducts for thermochemical processes, from the net heat value (H) of biomass, accounting for its moisture content (M):

E=H−[3,590. M.(1−M)] (kJ/kgTS) where 3,590 is the average energy content of 1kg steam at 100°C temperature and 1bar pressure (2,514kJ/kg) divided by the average efficiency of the drying process, assumed as 0.7; – as concerns byproducts for biochemical processes,

(kJ/kg TS) where; B=gross yield of biogas or ethanol per kg VS H’=net heat valve of biogas or ethanol η’=conversion process efficiency. The replacement energy value of biomass (V) is to be calculated with reference to the specific end use of the conventional energy replaced by biomass. Therefore: V=E/Q.η1/η2 (kgoe/kg TS)

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where: Q=net heat value of oil equivalent (42,000 kJ/kgoe) η1=efficiency of biomass-fed plant η2=efficiency of conventional plant. The energy cost of biomass (C) accounts for the energy spent to collect, pre- treat, handle, etc. the biomass and deliver it at conversion plant inlet. It is: C=R+D+T+Ci−Ef (kgoe/kg TS) where: R=energy outlay for biomass collection D=energy outlay for pretreatment and storage T=energy outlay for handling Ci=energy extra-cost of biomass against conventional plant Ef=energy value of process effluent. The energy return of biomass (P) thus becomes the difference between energy value and energy cost: P=V−C (kgoe/kg TS) 3.2—As Tables 1, 2 show, the amount of conventional energy that can actually be replaced by agricultural byproducts in the 10 EEC countries lies around 16Mtoe/y; energy density is slightly above 15toe/km2 or 0.35 toe per rural dweller. By country, these values range from 8.5toe/km2 (Ireland) to 32.9toe/km (Belgium-Luxembourg) and from 0.27toe/dweller (The Netherlands) to 0.96toe/dweller (Denmark). The corresponding total energy demand of stationary user points (farm and household) in the various countries ranges from 4 to 15toe/km2 useful farmland. The above should be increased by the energy yield of industrial waste, wood residues and solid civil waste. The contribution of the first and last items was calculated assuming energy conversion by anaerobic digestion, for an overall output of 3–3.5Mtoe/y. Thermochemical processes were evidently assumed for the wood residues; the total output is some 6Mtoe/y. Therefore, the contribution of residues and waste to the energy demand of agriculture in the EEC countries can be assessed at present around 25 Mtoe/y; a figure well in excess of the demand of stationary user points and which could contribute significantly to other professional or household requirements. This is evidently valid in general terms, and requires additional analyses and surveys on micro-areas of some 10–15km square. 4. EXISTING AND NEW MECHANIZATION CHAINS 4.1—The a bove calculations consider the short-range utilization of biomass, collected, loaded, handled and pre-treated with the currently available mechanical facilities. Such facilities are: – For straw and herbaceous crop residues in general, pick-up balers (for round or square bales) and lorries to collect the byproducts left over after harvesting the main crop;

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– For wood residues, suitably modified pick-up balers for thin (below 1–1.5cm dia.) residues, or more complex systems (cutting into short lengths and collecting in bulk) for coarser residues, both being left on the field. Natural drying was assumed, and the currently available chopping and wafering or briquetting techniques were considered; – For animal and industrial waste, different types of mechanical or hydraulic conveyors, depending on waste type and dilution; – For household solid waste, various simple, mostly manual systems, which generally do not segregate organic from inorganic material (glass, metal, plastic, etc.). Some data on pre-conversion energy outlay are given in the Annexes. Such outlay depends on the type of pre-treatment and type of biomass; it ranges from 1.5% (for livestock waste) to 3% (for straw) and 7% (wood residues) of the energy obtainable from the respective TS. Another cost item is transport, which Italian calculations show to account for 0.3–0.4 of the energy contents per km. Therefore, rather than reducing this energy outlay, the present problem is how to devise mechanical solutions for the recovery of non-recoverable or only partly recoverable byproducts, and to develop and diffuse complete, suitable and cost-efficient systems to deliver such byproducts to conversion plant inlet, with physical characteristics that are kept consistently close to the optimum for plant efficiency. This should eventually lead to the development of standard, modular systems so as to attain the scale economies needed to make competitive those conversion technologies and to overcome the technical and operative barriers to widespread application. 4.2—As known, only a few researchers (among whom Strehler is foremost) have dealt with this subject, and mostly for specific kinds of byproducts. Quite a lot still remains to be done, and the need for a coordinated, European research programme is to be emphasized. Such programme should determine the economic and technical feasibility of collecting, treating, storing and delivering residues at plant inlet. We shall mention a few, still open issues: – for cereal straw, investigating the feasibility of producing and adopting whole-plant harvesting chains followed by stationary threshing, in order to increase the recoverable byproduct by 60%; – for maize cobs and leaves, investigating the feasibility of modifying the existing mechanization chains to facilitate recovery; – for tree-crop pruning and forest residues, studying pick-up and pre-treatment (baling, chopping, pelleting, drying) chains to make these residues actually recoverable; – for animal excreta, developing stabling systems to facilitate removal in relationship to conversion plant optimization. (A similar approach applies to waste from the produce processing industry) Essentially, after having developed and optimized individual components and energy conversion technologies and analyzed the available residues, we shall have to devise and define complete packages to be offered to the farmer: without such packages, widespread use of these technologies in the rural world, and consequent utilization of the huge energy content of the available waste and residues, could hardly be implemented. Aknowledgment: the Author is grateful to Dr. M.Jarach and Dr. C.Semenza for their assistance in evaluating the available residues, and to Prof. G.Castelli and Ing.G.Riva for their conceptual contribution.

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MAIN REFERENCES (1) ADAS-NFU (1982), Proc. of the 6th Straw utilization Conference—Oxford. (2) AHNER D., FARGET M.A., (1980), La biomassa agricola e forestale: una fonte di energia per l’Europa—EUR 7937 IT. (3) ARANDA HEREDIA E., (1981) Récolte mécanique de la biomasse à destination énergétique: le bois de taille des oliviers—Proc.Intern.Symposium on Agricultural Mechanization, Bologna, 11. (4) BALDINI E., (1982), A preliminary investigation on alternative uses of Italian fruit tree biomass for energy conversion—CNR Ed.—Rome, 3. (5) BALDINI E., (1982), Residui di potatura e risparmio energetico—L’Informatore Agrario, 4. (6) BARTOLELLI M., PELLIZZI G., LIGUORI F. et Al., (1982), Il sistema agro-silvo-alimentare in rapporto all’energia—CNEL ed.—Roma, 3. (7) BENEVOLO G. et Al. (1982), Energie da biomasse: realtà e prospettive industriali—Atti Conf.Int.Energia da biomassa, Venezia, 3. (8) BODOLAI I., TOZSER I., (1984), Possibilities and axperiences of energy utilization of agricultural by-products—Proc.10th Int.Congress of Agricultural Engineering, Budapest, 9. (9) BODRIA L., GUIDOBONO CAVALCHINI A., LAZZARI M., (1984), Raccolta dei cereali a pianta intera: convenienza ancora difficile—L’Informatore Agrario, 2. (10) CHARTIER P., (1980), Constribution de l’agriculture à la satisfaction des besoins énergétiques—Comptes rendus Colloque Intern. du CENECA, Paris, 2. (11) DEBRUYN M. et Al., (1980), La biomasse comme source d’énergie alternative—Revue de l’Agricult., 6.

TABLE 1—TOTAL AVAILABLE VEGETABLE BY PRODUCTS AND NET ENERGY OUTPUT EEC COUNTRIES (1983) Country

Belgium & Lux. Denmark France Germany Greece Ireland Italy Netherl. U.K. E.E.C. %

Byproducts with c/N>30 TS Energy (kt/y) (ktoe/y)

Byproducts with C/N<30 TS Energy (kt/y) (ktoe/y)

900

270

300

2000 8000 6700 2900 800 6400 550 7000 35950 88

600 2400 2000 870 240 1940 165 2100 10585 95

100 1070 900 200 110 800 600 800 4830 12

30

Total TS (kt/y)

Energy density

Energy (toe/km2) (toe/dw.) (ktoe/y)

1200

300

19.3

0.196

40 2200 105 9070 88 7600 20 3100 11 910 78 7200 59 1150 78 7800 479 40080 5 100

610 2505 2088 890 251 2018 224 2178 11064 100

21.4 7.9 17.3 9.6 4.4 11.4 11.1 11.6 10.8

0.792 0.356 0.226 0.468 0.405 0.223 0.104 0.275 0.245

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TABLE 2—TOTAL AVAILABLE ANIMAL WASTE AND NET ENERGY OUTPUT, EEC COUNTRIES (1983) Country

Cattle Swine Poultry Total Energy density TS Energy*) TS Energy*) TS Energy**) TS Energy (toe/km2) (toe/dw.) (kt/y) (ktoe/y) (kt/y) (ktoe/y) (kt/y) (ktoe/y) (kt/y) (ktoe/y)

Belgium 1690 132 410 53 140 & Lux. Denmark 1330 104 740 96 73 France 11100 865 920 120 1002 Germany 7700 400 1770 230 523 Greece 500 39 95 12 178 Ireland 2740 214 90 12 44 Italy 6700 523 850 110 750 Netherl. 2440 190 780 100 365 U.K. 6630 517 640 83 700 E.E.C. 40830 3184 6295 816 3775 % 80 67 12 17 8 *) Calculated as obtained by anaerobic digestion **) Calculated as obtained by direct combustion

28 2240

213

13.6

0.139

15 2143 200 13022 105 9993 36 773 9 2874 150 8300 73 3585 140 7970 756 50900 16 100

215 1185 735 87 235 783 363 740 4756 100

7.6 3.7 6.1 0.9 4.1 4.4 18.0 3.9 4.6 –

0.279 0.168 0.079 0.046 0.379 0.087 0.168 0.094 0.105 –

(12) DEVANEL A., MEKIKDJIAN C., (1984), Chaine de production, de stockage et de transformation énergétique de la Canne de Provence—Proc.10th Int.Congress of Agricultural Engineering, Budapest, 9. (13) DOBIE et Al., (1973), Systems for handling and utilizing rice straw—Transactions of ASAE, 16. (14) FARGET M.A., (1983), Valorisation énérgétique de la biomasse d’origine agricole—Séries FAST n.15—EUR 8666 FR. (15) FIALA M., (1985), La combustione della biomassa: una tecnologia economicamente valida— L’Infomatore Agrario, 5. (16) GEO PAUL N., (1980), Some methods for the utilization of waste from fibre crops and fibre wastes from other crops—Agricultural Wastes, 4. (17) GIEROBA J., NOWAK I., (1984), Hay and straw harvesting technologies applied in Poland— Rivista di Ingegneria Agraria, 2. (18) GUARELLA P., (1984), Raccolta e condizionamento in balle di residui di potatura di vite e olivo—L’Informatore Agrario, 39. (19) HAVE H., (1979), Regional analysis of potential energy production from agricultural wastes—Inst. of. Agric. Engineering Paper. (20) HJORTSHOJ-NIELSEN A., (1980), The energy demand of Danish agriculture and its potential role as producer of alternative energy—Compte rendus—Colloque Intern. du CENECA, Paris, 2. (21) LARKIN S.B.C.., MORRIS R.M., NOBLE D.H., RADLEY R.A., (1980), Production, distribution and energy content of agricultural wastes and residues in the U.K.—Energy from biomass 1st E.C. Conference, Brighton, 11. (22) LUCAS N., (1978), Whole crop harvesting—Power Farming, 8–10. (23) KASTROLL H.J., (1984), Aktuelle Probleme der Enegieproduktion und Energieanwendung in der Landwirtschaft—Proc.10th Int.Congress of Agricultural Engineering, Budapest, 9.

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(24) KUMAR K., BAL S., OJHA T.P., (1984), Fuel characteristics of agricultural residues—AMA, 4. (25) NATALICCHIO E., SEMENZA C., (1981), Production, recovery techniques, present and alternative uses of agricultural byproducts—Report CNR n°23, 10. (26) PALZ W., CHARTIER P., (1980), Energy from biomass in Europe—Applied Science Pubbl. (27) PELLIZZI G., (1980), New and renewable energy in agriculture—FAO Report, 4. (28) PELLIZZI G., (1984), Prime analisi comparative di differenti processi di conversione energetica delle biomasse—Rivista di Ingegneria Agraria, 2. (29) PELLIZZI G., (1984), Energy utilization of biomass—Proc. 10th Inter. Congress of Agricultural Engineering, Budapest, 9. (30) PELLIZZI G., (1985), La legna fonte di energia rinnovabile—L’Informatore Agrario, 5. (31) PETTERSON I., (1982), Halm som energikölla—Pikon Energikonsult, Örbyhus. (32) POSSELIUS J.H., STOUT B.A., (1980), Crop residues availability for fuel—Proceedings of “Bioenergy 80” Congress, Atlanta, 4. (33) REQUILLART V., (1982), La filiére paille granulée; analyse économique—Etude COMESINRA. (34) REQUILLART V., (1984), Upgrading straw in Europe—Biomass News Intern. 1. (35) REXEN F.P., (1980), Straw and animal residues available for energy—Energy from biomass 1st E.C. Conference, Brighton, 11. (36) SATEK J., (1968), Czech three-stage cereal harvesting—Power Farming, 1. (37) STANIFORTH A.R., (1979), Cereal straw—Clarendon Press. (38) STANIFORTH A.R., (1982), Straw for fuel, feed or fertiliser?—Farming Press Ltd., (39) STREHLER A., (1984), Energiegewinnung aus Bio-Masse—Proc.10th Int. Congress of Agricultural Engineering, Budapest, 9. (40) TESIC M., (1984), Die Bewertung der Maisstrohernterverfahren in Jugoslavien—Proc.10th Int.Congress of Agricultural Engineering, Budapest, 9. (41) VOLPI R., VATTERONI G., (1982), L’apporto della biomassa al sistema energetico nazionale—Atti Conf. Int. Energia da Biomasse, Venezia, 3. (42) WILTON B., (1978), Whole crop cereals: harvesting, drying and separation—The Agricult. Engin.

ANNEX 1 1. The calculation procedure used to determine the actual availability of vegetal byproducts for energy conversion is based on the following equation: TS=Σ[A.y.α.δ(1—M).(1—AL)] (t/y) where: TS=total solids available for energy conversion (t/y) A=farmed surface per crop (ha) y=main crop yield (t/ha y) α=byproduct/main crop ratio, for the byproduct actually recoverable with standard mechanization chains δ=surface reduction coefficient, to account for small, isolated plots and generally for those plots where byproducts are difficult to collect M=moisture content of byproduct as collected (% H 0) AL=byproducts for alternative uses (%). Crop & Ave.ratio Ave.moisture C/N Alternative Remarks byproduct (α) content (%) ratio use (%) Wheat, oats,

0.6

10–20

60–

40–60 For whole-plant harvesting

Energy from biomass

barley, rye straw Maize leaves & cobs

130 0.2

45–55

70– 80

1.3

35–45

80– 90

1.1

10–20

28– 30 14– 17 22– 26 23– 25 61– 65 57– 65

118

chains v/stationary thresher: =0.9–1 0–15 Stalks are better used for fodder. They account for 1.2 times the main product, at 55– 65% moisture content 0–20

Oleaginous crops, stems & leaves Bean crops, straw Beet tops & leaves, Potato vines

0.3

55–65

Toma to vines

0.17

75–90

Rice straw

0.55

40–50

0.3

40–50

0.7

35–45

67– 70

0.1

35–45

45– 60

0–10

0.2

35–45

47– 55

0–10

1.9

35–50

55– 70

0–10 Moisture content of leafy branches is higher than that of wood

Vineyard pruning residues Olive tree pruning residues Pear, apple & citrus pruning res. Stone fruit tree pruning residues Nut tree pruning residues

75–85

0–20 10–40 0–10 0–10 15–30 Min.mowing height with current harvesting chains: 30cm 0–10 Amount depending on training pattern: greater for single-row, smaller for GDC. 0–10 Leaves have higher moisture content than wood

The tabulated values are drawn from actual data, based on the physical characteristics of the crops, quantity of byproduct recoverable with standard mechanization chains and on exhaustive tests. The following calculation example refers to soft wheat, barley, oats and rye. In the various countries, these crops account for more than 60% of the available byproducts, with a peak of 95%. The breakdown by weight is 36% grain; 27% roots and stubble; 37% straw and other residues. The theoretical ratio of recoverable epigeal parts to grain is therefore: α=0.37/0.36=1.03. The actual value of α varies with harvesting height: if this is assumed to be 15 to 20cm, the recoverable straw is some 80% of the above; therefore, 0.37×0.8=0.30, and α=0.30/0.36=0.81. Moreover, chaff, leaves and stalk chips cannot be picked up; they account for 26–28% of the epigeal part. Therefore:

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and the amount of vegetal material left on the field is some 40% of total production or 1.2 times the harvested grains: this significantly contributes to safeguarding the soil’s physical properties and nutritional value. 2. The procedure adopted to assess the energy contribution of these byproducts is based on the calculation of the relevant energy return (P), or on the amount of conventional energy that they can actually replace after deducting the energy outlay and accounting for conversion plant efficiency, by the methods described in the report: (toe/y) In particular, the following was assumed: – for TS for anaerobic digestion (C/N≤30): E (mean energy content): 4800kJ/kg TS η”(efficiency of biogas utilization against conventional energy utilization; biogas is assumed to be used as fuel in place of Dieseloil): η1/η2=0.88 H (net heat value of biogas): 21,000kJ/Nm C (mean energy outlay)= 1500kJ/kg TS – for TS (C/N>30) for direct combustion processes: E (mean energy content): 16,400kJ/kg TS for straw; 17,100kJ TS for pruning residues; η” (relative efficiency of utilization plant: biomass-fuelled burner replacing a Dieseloil burner): 0.88 C (mean energy outlay): 1700kJ/kg TS The above indicatively yields: – for byproducts having C/N≤30: P=0.088toe/t TS; – for byproducts having C/N>30: from herbaceous crops: P=0.30toe/t TS from tree crops & forests: P=0.31toe/t TS For those byproducts meant for anaerobic digestion, the energy value of process affluents is evidently also to be accounted for. These effluents, usable as fertilizers, can be assessed at 0.10–0.12toe/t TS; hence, P=0.20toe/t TS. ANNEX 2 1. The actual available animal byproducts for energy use were calculated on basis of equivalent livestock units as follows: Livestock Animal equivalent (AE) (kg) Excreta TS (kg/t on the hoof) VS (% TS) Cattle Swine Broilers Hens

450 100 0.8 1.7

8.5 6.0 13.0 13.0

73 75 70 70

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(NB: 100kg was assumed per equivalent pig and 0.8kg per equivalent broiler to account for average residence time, average growth during residence and final selling weight. For cattle, account was taken of the ratio of milking cows to fattening cattle). The formula used is: TS=Σ[n.D.AE.365.δ.γ] (t/yr) where: – TS=total solids per year (t/y) – n=number of head equivalent – D=total solids per day and animal unit weight (kg/t.d) – AE=equivalent weight (t) –δ=reduction coefficient to exclude animal farms below a certain number of head equivalent (cattle: <10 head eq.; swine <100 head eq.; chicken: <1000 head eq.) – γ=reduction coefficient for cattle, to account for actual yearly stabling time and actual recoverable excreta: γ=0.6 for northern Europe, γ=0.85–0.9 for southern Europe. 2. The energy contribution of such TS was obtained by the formula given earlier (cf. Report and Annex 1), where: – for TS for anaerobic digestion: E (mean energy content)=3,800kJ/kg TS for cattle excreta and= 5,600kJ/kg TS for swine excreta; η” (efficienty ratio of biogas utilization plant; biogas is assumed to be used as fuel in place of Dieseloil)=0.88 H (net heat value of biogas)=19,000kJ/Nm3 for cattle excreta;= 22,200kJ/Nm for swine excreta; C (mean energy outlay)=800kJ/kg TS; – for TS for direct combustion processes: E (mean energy content)=11,000kJ/kg TS; η” (efficiency ratio of utilization plant: biomass-fuelled burner in place of Dieseloilfuelled burner)=0.88 C (mean energy outlay)=1300 kJ/kg TS The above indicatively yields: – Cattle excreta:

P=0.078toe/kg TS

– Swine excreta:

P=0.129toe/t TS

– Chicken excreta:

P=0.200toe/t TS

For those byproducts meant for anaerobic digestion, the energy value of process affluents is also to be accounted for. These effluents, usable as fertilizers, can be assessed at 0.10– 0.12toe/t TS; hence, P=0.180 toe/t TS for cattle; P=0.230toe/t TS for swine.

THE POTENTIAL OF NATURAL VEGETATION AS A SOURCE OF BIOMASS ENERGY T.V.Callaghan, G.J.Lawson & R.Scott The Institute of Terrestrial Ecology Grange-over-Sands Cumbria LA11 6JU, UK Summary of 250,000 species of higher plants in the world only 1000 are used as crops. The world area of cropland is not expected to increase greatly by 2000, and increased food demands will dictate that most biomass feedstocks are produced from uncultivated and marginal land. A diversity of natural vegetation already occurs on these areas, and many species have acquired tolerance to extremes of aridity, erosion, salinity, exposure, inundation, toxicity and grazing pressure. In addition to providing bioenergy, indigenous species can often be exploited for human and animal feed, fibre and structural materials, shelter and shade for crop plants, chemicals, medicines, and organic fertilisers. Many species of natural vegetation are associated with nitrogen fixing micro-organisms, and species mixtures generally enhance biological activity and nutrient recycling. Mixtures can also permit more complete utilisation of light and moisture resources. The possibilities of mixed agricultural, forest and energy cropping still receive inadequate attention, both in tropical and temperate regions. Significant yield increases are expected in natural vegetation following selection and breeding, although there will be initial management difficulties in establishing energy plantations which match the observed yields of native plants in the wild.

1. INTRODUCTION In the modern world two main attitudes to vegetation predominate. The first is that of utilisation and production, which destroys primeval forests as well as the old, varied, semi-natural landscapes, for the sake of short-term gains from a narrow range of products. The second is that of nature conservation which strives to preserve as much as possible of the rich variety of life and ecological systems (1). The first attitude, if it wins, will do so to the detriment of the biosphere, the genepool and man himself; the second attitude can be modified, using an understanding of the physiology of plant growth and environmental processes, to generate renewable supplies of feed, fuel and fibre in cooperation rather than conflict with nature.

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There are some 250,000 species of higher plants in the world, of which around 155,000 are found in the tropics (2). However the world’s crop plants are estimated to comprise less than 1000 species (3), and despite recent efforts to convince agriculturalists of the value of plants which have been excluded from modern agriculture (4), there remains great scope for the adoption of novel species and sytems of cultivation. This paper contends therefore that bioenergy production provides further justification for looking outside traditional crops and trees, and it also looks at the problems and advantages of managing these new resources. 2. THE WORLD VEGETATION RESOURCE The International Biological Programme has enabled reasonably accurate estimates of plant productivity in the world’s major ecosystems to be compiled (5,6). Around 133Pg (billion tonnes) of terrestrial biomass is estimated to be produced annually from a world standing crop of 1244- Pg. However, as little as 11.3% of this total production is from cultivated areas (occupying 10.7% of the land surface), and only 1.1% and 1.3% of agricultural and forest production are used by man in the form of food or timber (7). A theoretical study of the climatic and soil limits to agricultural production has estimated that 3419 million hectares of land are potentially cultivable in the world, and this extent could maximally produce 49.8 billion tonnes of grain equivalent (8). This compares with a current world production of 1.57 billion tonnes (9). However, this theoretical study could account neither for the social, economic and political constraints to an expansion of cultivation, nor did it consider the many practical reasons for suboptimal harvests of grain. At a more practical level, the FAO predict that the proportion of potential arable land which is actually cropped will increase from 40% at present to only 50% by the end of the century. Thus, 72% of the extra food necessary by 2000 must be met by an increase in productivity (10). Yet such an increase will depend on energy intensive practices such as fertilisation or irrigation. Also, breeding for higher grain yields at the expense of total biomass, and more complete harvesting methods, will reduce the residues available for soil fertilisation or utilisation as an energy source. Yields in the developed world appear to be approaching a ceiling (11), and large surpluses for export cannot be relied upon. Thus the FAO conclude that “in many developing countries, large scale production of biomass for energy, if it is to be undertaken at all, will need to come mainly from the land areas which are not devoted to agriculture and from marginal agricultural land” (10). Here then is the role for natural vegetation, and in developed countries too it is likely that energy farming will make most impact on marginal lands, at least in the immediate future. 3. THE PRODUCTIVITY OF NATURAL VEGETATION Comparisons of managed and unmanaged vegetation in Germany and N.America have demonstrated little overall difference in yield between the two systems, but emphasised

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that agricultural yields were achieved on the best land, and with considerable inputs of fertiliser (12). Many native plants have recorded high yields, which often exceed those of crop species selected for food or timber production rather than for maximal biomass (7). The following section explores the reasons why many native species can fully exploit existing environments, and the folly, in many circumstances, of seeking to alter the environment to suit the requirements of crop plants. As stated in the planning of the International Biological Programme: “The natural communities present us with a basic yardstick, since they exhibit the level of productive effectiveness that has been brought into being by natural selection operating over geological periods of time” (13). In short, bad weeds possess most of the attributes necessary for good energy crops. 4. CHARACTERISTICS OF NATURAL VEGETATION ENERGY SYSTEMS 4.1 Greater diversity of cropping sites If energy cropping is to take place principally on uncultivated areas, as suggested by the FAO, then a major role will be played by natural vegetation which is already adapted to the various extremes of aridity, salinity, exposure, erosion, innundation, toxicity, or grazing pressure. 4.1.1 Arid lands. These areas already support a wealth of native species which can potentially be used for the production of food, feed, fibre and fuel. These include, cresote bush (Larrea tridentata), mesquite (Prosopis spp., quinoa (Chenopodium spp.), buffalo gourd (Cucurbita foetidissima), saltbrush (Atriplex spp.), Russian thistle (Salsola kali), carob (Ceratonia siliqua, pinyon (Pinus sembroides), Yucca spp. and various cacti (14). North American plants studied as a source of hydrocarbons include ragweed (Ambrosia trifida, milkweed (Asclepias spp.), pale indian plantain (Cacalia atriplicifolia), tall bellflower (Campanula americana), field thistle (Cirsium discolor), tall boneset (Eupatorium altissimum), mole plant (Euphorbia lathyrus), smooth sumac (Rhus glabra), sassafras (Sassafras albidium), sow thistle (Sonchus arvensis) and iron weed (Vermonia spp.) (15). Hydrocarbon plants do not have a major role in current US Government programmes (16), largely through doubts over economics (17). These constraints will, however, be less severe in third world countries, where fossil fuels consume most available foreign exchange. Native arid land plants, particularly those containing hydrocarbons, are in cultivation for energy purposes in several countries such as Euphorbia spp. in Kenya (18), black quince (Cydonia spp.) in Brazil (19) and guayule (Parthenium arginatum) in Mexico (20). Calotropis procera is under investigation in India (34).

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4.1.2 Saline areas. Native species have evolved tolerance of saline conditions in deserts, and also in coastal saltmarshes. These areas suffer no competition from other land uses. Extreme examples of desert tolerance to salt encrustations are Saltbrush (Atriplex spp.) and some species of mesquite, such as tamarugo (Prosopis tamarugo). Mesquite even grows in foreshore conditions. Cordgrass (Spartina anglica) has been investigated as an energy crop on saltmarshes in the UK, giving an average yield over three years of 12t ha−1 in October and 5t ha−1 in January (21). Silt-grass (Psalpum vaginatum) would be an appropriate energy crop on tropical saltmarshes. 4.1.3 Exposed climates. Crop plants are not adapted to wind and exposure. Native species, and trees, also grow slowly in these severe conditions, but bracken (Pteridium aquilinum) can sustain an average yield of 9t ha−1 yr−1 for at least 4 years (21). Dwarf shrubs like heather could provide a small yield (1t ha−1 yr−1) in combination with moorland management. 4.1.4 Eroded areas. Perennial natural vegetation is of particular use in stabilising eroded areas, and energy harvesting can be conducted with little or no cultivation. Prosopis chilensis, for example, is being spread naturally in the Sudan by feeding the fruits to goats. This type of species stabilises the sands and initiates the accumulation of organic matter in the soil, which crop species can then utilise. Another example is Kudzu vine (Pueria lobata), which was extensively planted in United States after the great depression. It is now regarded as a major weed, because it outgrows trees and pasture. However, the needless costs of spraying could be avoided by exploiting the value of Kudzu for energy cropping, land restoration, feed production, and even paper making (22). 4.1.5 Inundated areas. Natyral aquatic communities can give yields ranging from 8 to 60t ha−1 yr−1, with minimal management effort (7). 200Mha of swamps and marshes exist in the world, and, although this is only 1.3 of the land area, it estimated to produce 5.5% of global plant production. Catail (Typha latifolia), reed (Phragmites australis) and giant reed (Arundo donax) have been thoroughly investigated as energy crops in Minnesota (23), Sweden (24) and France, the last in strip-intercrops with corn and sunflower (25). These species are reported to yield up to 43, 37 and 59t ha−1 yr−1, respectively, although such yields are not likely to be sustained in extensive energy plantations. Papyrus (Cyperus papyrus) has been suggested as an energy crop for Rwanda (26). and its maxiraum productivity, measured in India, is 78t ha−1 yr−1 (27). Water hyacinth has attracted considerable attention (28), but many other emergent macrophytes remain to be studied. One drawback of aquatic energy crops, however, is their low energy content of around 13kJ g−1, compared with the average for all vegetation of 18.3 kJ g−1 (7). This is largely due to a high ash content.

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Much money and effort is devoted to the eradication of potentially useful weeds. Water hyacinth is perhaps the best example, and $1 million is spent annually on its conrol in the Sudan alone (29). In two states of the United States the cost of control was $15 million in 1976 (30). Yet water hyacinth can grow with astonishing rapidity, 10 plants increasing to 600,000 within a period of 8 months, and giving yields in laboratory conditions in excess of 100t ha−1 yr−1 (31). In addition to being used for anaerobic digestion, water hyacinth can operate as a biological filter for sewage, taking up heavy metals and pathogens (28). Many wetland species with potential for use as energy crops can serve similar multiple purposes (32). It is sad therefore that these most productive areas of the world are being drained and destroyed: yet the crops which relace them are far less productive and exploit, rather than create, the fertility of the soil. 4.1.6 Toxic and waste lands. Native weeds of waste ground are invasive and resilient in nature, making them suited to repeated harvesting. The perennial species of Japanese and giant knotweed (Reynoutria japonica, R.sachalinense) have yielded around 15t ha−1 yr−1 on unfavourable sites in the UK, and several other species such as nettle (Urtica dioica, Gunnera manicata, willowherb (Epilobium hirsutum), himalayan balsam (Impatiens glandulifera) and gorse (Ulex europea) have been suggested for areas not suitable to agriculture or forestry (33). Productive indigenous weeds occur in all countries. In India for example, species such as Saccharum munja, Camera lanata, and Bougainvillea are reported as having higher yields than nearby agricultural crops, without the aid of irrigation (34). Supplementing the value of these species as biofuels are their uses for animal feed, rope and furniture making, paper and fibre-board manufacture, and the extraction of chemicals. The area of waste land in India is estimated to be 43.7Mha, with 2.7Mha occurring around the periphery of farms (35). 4.1.7 Areas of high grazing pressure. Where grazing pressure is intense it is useful for an energy crop to be unpalatable. Many native plants with thorns and thick leaves are useful in this regard, as are species like bracken and Calotropis procera (29), with a high alkaloid content. However, care must be taken over the introduction and use of poisonous weeds (36). 4.2 Fuller utilisation of sunlight A theoretical limit to the efficiency of terrestrial plants in capturing solar energy is set around 5.5% (37). However actual efficiencies fall far short of this: averaging 0.24% world-wide. This represents an aboveground production of 8.9t ha−1 yr−1 (7), compared to the theoretically possible 203t ha−1 yr−1. Efficiencies are particularly low in annual agricultural crops, due partially to their incomplete leaf cover through the growing season, and the fact that, even when the canopy is fully developed, much radiation will not be utilised by an erect monoculture. This is less true at high latitudes, and monocultures with leaves at 65 to the horizontal at

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40N require twice the leaf area to intercept the same amount of light as when growing at 70N. Interception may not be significantly greater in mixtures than in a dense monoculture, but the light will be better distributed over the leaves, and understory species are better able to utilise the reduced light intensity, and altered spectral composition of light within the canopy (38). Manmade systems can be postulated which mix tall, erect, C4-species with smaller, more horizontal, C3-species. The latter being more suited to to shade because they become light saturated at lower intensities. The most efficient interception of radiation takes place in natural communities, where forests may consist of two layers of trees, a shrub layer and a herb layer. One example of the utilisation of naturally occuring understory species in an energy-forest mixture is the use in India of Pinus roxburghii (‘open bunch’ canopy) with the middle structure of Michelia champaca (‘column’ canopy) and the lower structure of Cinnamonum camphora (‘umbrella’ canopy) (39). Even in temperate woodlands, with lower radiation intensity, the natural understory vegetation has a significant biomass which is available for energy purposes. A survey of pine and pine/hardwood stands in southern USA indicated that an average of 2.5 t ha−1 yr−1 could be harvested from the shrub layer on a 10 year cycle, with the additional advantages of increasing tree growth and reducing the need for brush control. (40). Similarly, the production of a bamboo species (Chusquea culeou) under an open canopy of southern beech. (Nothofagus spp. in Chile has been observed to exceed 10t ha−1 yr−1 (41). 4.3 Lower nutrient input requirements The manufacture and delivery of each Kg of fertiliser Nitrogen in the UK requires between 62 and 82 Megajoules of energy, and synthetic fertilisers are largely unavailable to poor farmers. Therefore more reliance is being placed on nitrogen-fixing energy and fodder crops, such as tree-legumes of the genera Prosopis, Leucaena, Acacia, Calliandra and Sesbania. Nitrogen fixing species often increase the yields of accompanying nonlegumes, and several mixed tree-plots including the N-fixing species of alder (Alnus) have recorded improved combined growth, particularly on poor soils. In northern Australia native legumes and yams have been recommended as alternatives to cassava as fuel crops. In addition to growing in more arid areas, they have advantages of decreased fertiliser costs, propagation by seed, early ground cover and easily harvested tubers (42). Lupins have been used as nurse crops to establish trees on nitrogen poor sands (43) and toxic wastes (44), and a novel energy-crop mixture of hedges of Monterey cypress (Cupressus macrocarpa) and gorse (N-fixing) is being investigated in New Zealand (45). Nitrogen fixing also takes place in associations of non-nodulated natural vegetation. For example, a weed dominated plot in England is reported to fix 55kg N ha−1 yr−1 (46). Blue-green algae are always associated with the water fern (Azolla pinnata), and this plant is regularly cultivated amongst the rice paddies of China (47). Azolla is also thought to be be a useful adjunct to aquatic energy crops like water hyacinth (29). Another blue-green alga, Nostoc, is found in the stems of Gunnera manicata, which has been suggested as an understory energy crop in temperate woodlands (21).

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Nitrogen fixing is the most obvious advantage of many natural associations, but native species are often adapted to low levels of other nutrients, and the unusually high efficiency of bracken (Pteridium aquilinum) in mobilising soil reserves of phosphorus (48), is one example. The different components of a species mixture can utilise distinct soil pools of nutrients and moisture, and there is also evidence in trees that leaf-litter decomposition rates are faster in mixtures, partly because of stimilated soil-fauna activity (49). 4.4 Potential for selection and breeding Crop breeding has involved the selection of those characteristics which will respond to intensive management and maximise commercially Important parts of the plant like grain, tubers and structural timber. This is usually achieved at the expense of other parts of the plant, and total biomass will often have been reduced in the process. Many agricultural crops seem now to be reaching the limit of their response to management, selection and fertilisers, and it is in wild species that the largest gene pool exists for selectively increasing yields. Although yield is the most important criteria, other attributes will also be important, such as resilience under intensive croping, the ability to grow in harsh conditions with minimal management inputs, resistance to pathogens, ingreased energy to biomass ratios, and the ability to grow in mixed stands. New methods of breeding for woody perennials, and particularly trees (50), involving tissue culture of selcted clones, promise exciting yield increases in the future. 5. CONCLUSIONS This paper has not considered the social, economic or technological aspects of biomass production and biofuel conversion from natural vegetation (7,21,29), but we would nevertheless stress the importance of using local technology to exploit native plants and cropping systems. Simple methods of briquetting (51), charcoal making (52) and protein extraction (53) bear special mention. Although the food versus fuel argument expresses valid fears about existing ethanol production schemes (54), the conflict need not exist if the imperative were followed of integrating biofuel production with agriculture and forestry. Neglected species and uncultivated land can thereby be brought carefully into production. REFERENCES (1) WESTHOFF, W. (1983). Man’s attitude towards vegetation. In: ‘Man’s impact on vegetation. W.Holzner et al. (Eds). Junk. The Hague. (2) BRENAN, J.P.M. (1983). Economic plants. Biologist 30: 75–79 (3) DUKE, J.A. and TERRELL, E.M. (1974). Crop diversification matrix. Taxon 23: 759–799. (4) NAS (1975). Underexploited tropical plants with promising economic value. National Academy of Science, Washington DC. (5) AJTAY et al. (1979). Terrestrial primary production and phytomass. In ‘The global carbon cycle’, B.Bolin et al. (eds). Sci. Comm. on problems of the environment No. 13. p129–181.

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(6) OLSON, J.S et al. (1983). Carbon in live vegetation of major world ecosystems. Oak Ridge National Lab., Tennessee, Report 5862. 180pp. (7) LAWSON et al. (1984.). Renewable energy from plants: bypassing fossilisation. Adv. Ecol. Res. 14: 57–114. (8) BURINGH.P et al. (1975). Computation of the absolute maximum food production of the world. Dept. Tropical Soil Sciences, U. of Wageningen. (9) FAO (1981). Production yearbook 1980. Food and Agricultural Org. Rome. (10) FAO (in press). The future supply of bioenergy in developing countries. In workshop on bioenergy in developing countries, Gothemburg 1984. (11) JENSEN, N.F. (1978). Limits to growth in wld. fd. prod. Sci. 201: 317–320 (12) LIETH, H. and ASSELMAN, I. (1983). Comparing the primary productivity of natural and managed vegetation. An example from Germany. In ‘Man’s impact on vegetation’. W.Holzner et al. (Eds.). Junk, The Hague. (13) WADDINGTON, C.H. (1963). Mobilising the world’s biologists to enlarge our resources. New Scientist 337: 248–250. (14) McGINNES, W.G. (1979). Potential of native plants for food, fibre and fuel in arid regions. In ‘Biosaline concepts’, Plenum, New York. (15) BUCHANAN, R. et al. (1980). Multi-use botanochemical crops, an economic analysis and feasibility study. Ind. Eng. Chem. Prod. Res. Dev. 19, 489–496. (16) BERGER, B.J. and CUSHMAN, J.H. (1985). Herbaceous energy crops-planning for a renewed commitment. In ‘Bioenergy 84’. H.Egneus (Ed). Pergamon. (17) WARD, R.F. (1982). Euphorbia..hydrocarbons in the future. Sol. En. 29: 83–86. (18) LEAKEY, P. (1981). A report on the Euphorbia research and the indentified process route to produce gasolene from Euphorbia. Ministry of Environment and Natural Resources, Nairobi. (19) ANON (1980). Alternative fuels take to the bush. New Scientist 87: 527. (20) ANON (1980). Mexico will build a facility to produce 5,000t/yr of rubber from Guayule. Chemical Engineering 87: 29. (21) CALLAGHAN, T.V. et al. (1984). An experimental assessment of native and naturalised species of plants as renewable sources of energy in G.B. Vol V—Overview. Report to UK Dept of Energy from Inst. Terr. Ecology. (22) TANNER, R.D. et al. (1980). Kudzu (Pueria lobata): a potential agricultural and Industrial resource. Econ. Bot. 33: 400–412. (23) PRATT, D.C. et al, (1983). Wetland biomass production: emergent aquatic management options and evaluations. SERI/ TR-3–2094–1, Golden, Colorado. (24) GRANELI, W. (1984). Reed as an energy source in Sweden. Biomass 4: 183–208. (25) ARNOUX, M et al. (1984). Joint research on Arundo donax as an energy crop. In ‘Energy from biomass’. Ser.E, Vol.5. D.Reidel, Dordrecht. (26) JONES, M. (1983). Papyrus: a new fuel for the 3rd world. New Sci. 99: 418–421 (27) WESTLAKE, D.F. (1963). Comp. of plant productivity. Biol.Rev. 38: 385–425 (28) WOLVERTON, B.C. and MacDONALD, R.C. (1979). The water hyacinth: from prolofic pest to potential provider. Ambio 8: 2–9. (29) CALLAGHAN, T.V. et al. (in press) The energy crisis in Sudan: alternative supplies of biomass. Biomass. (30) COX, L.M. (1977) First—know your weed. Utah Sci. 38: 59–61. (31) SAUZE, F. (in press). Stock taking of development possibilities of aquatic biomass. In ‘Bioenergy 84’. H.Egneus (ed) Pergamon Press. (32) SEIDEL, K. (1971). Macrophytes as functional elements in the environment of man. Hidrobiologia 12: 121–130. (33) CALLAGHAN, T.V. (1981). The yield, development and chemical composition of some fast growing indigenous and naturalised British plant species in relation to management as energy crops. Instutute of Terrestrial Ecology.

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(34) VASUDEVAN, P. and GUJRAL, G.S. (1985). Potential of underexploited weeds as a bioenergy resource. In ‘Bioenergy 84’ H.Egneus (Ed). Pergamon. (35) KAUL, R.N. and GURUMURTI, K. (1981). Planting for energy. Science Today October 1981: 43–46. (36) WILLIAMS, M.C. (1980). Purposefully introduced plants that have become noxious or poisonous weeds. Weed Science 28: 300–305. (37) HALL, D.O. (1979). Solar energy conversion through biology—could it be a practical energy source? Biologist 26: 16–22. (38) WILLEY, R.W. (1979) Intercropping—its importance and research needs. Field Crop Abstracts 32: 1–10 and 32: 73–85. (39) GURUMURTI, K. (1981). Principles of optimising energy fixation in forest crops. Indian Forester 107: 830–837. (40) KU, T et al. (1980). Understory biomass for energy fuel. Proc. Southern Sylvicultural Conf. 1. 230–233. USDA Forest Service. (41) VEBLEN, T.T et al. (1980). Dry matter production of two species of bamboo in south-central Chile. J.Ecol 68: 397–404. (42) SAXON, E.C. (1981). Tuberous legumes: preliminary evaluation of tropical Australian and introduced species as fuel crops. Econ. Bot. 35: 163–173. (43) GADGIL, R (1976). Nitrogen distribution in stands of Pinus radiata with and without lupin in the understory. N.Z.Jl For.Sci. 6: 33–39. (44) MARRS, R.H. et al. (1982). Tree lupin: an ideal nurse crop for land restoration and amenity plantings. Arboric.J. 6: 947–174. (45) TAYLOR, J.O. (1978). The Monterey cypress: a new concept in farming for fuel. Span 21: 30–32. (46) JENKINSON, D.S. (1971). The accumulation of organic matter in soil left uncultivated. Rep. Rothamsted exp. Stn. 1970. 113–137. (47) FAO (1977). China: recycling of organic wastes in agriculture. Food and Agriculture Organisation. Rome. (48) MITCHELL, J. (1973). Mobilisation of phosphorus by Pteridium aquilinum. Plant and Soil 38: 489–91. (49) BROWN, A.F.H and HARRISON, A.F. (1983). Effects of tree mixtures on earth-worm populations and nitrogen and phosphorus status in Norway spruce. In New Trends in Soil Biol. P.Lebruin et al. (Eds). Dieu-Brichart. Ottignes (50) LEAKEY, R.R.B et al. (1982). Domestication of tropical trees: an approach securing future productivity and diversity in managed ecosystems. Commw. For. Rev. 61: 33–42. (51) HISLOP, D. and JOSEPH, S. (in press). Briquettes for domestic energy in developing countries. This volume. (52) GUJRAL, G.S. (1984). Pyrolytic carbon from waste-land weds. Agric. Wastes 9: 155–57 (53) OKE, O.L. (1974). Leaf protein for better nutrition. App. Technol. 1: 11–12. (54) BROWN, L. (1980). The energy cropping dilema. Ceres Nov-Dec: 28–32.

PHOTOBIOLOGY—THE SCIENTIFIC BASIS OF BIOLOGICAL ENERGY CONVERSION M.C.W.EVANS Department of Botany and Microbiology University College London Summary All systems designed to obtain energy from biomass are ultimately dependent on the growth of plants or photosynthetic microorganisms and therefore an understanding of the biology of these organisms is essential. Many of the systems to be discussed at this meeting have developed from agricultural and forestry techniques, and much of their development in the near future will depend on classical techniques of plant selection and breeding. Other systems, notably those dependent on algal culture, have developed from laboratory studies of the photobiology of the organisms now used for mass culture. In the long term the development and viability of biomass systems will depend on the efficiency of solar collection and conversion to useful energy. In order to overcome many of the limits to efficiency a detailed understanding of the mechanism of photosynthesis at all levels from the whole plant to the primary reactions in the chloroplast membranes will be required. In the more distant future the selection, or synthesis by genetic modification, of organisms with the ability to synthesise directly products which currently have to be made by secondary processing of biomass may revolutionise both mass energy production and the photobiological production of high value products. All systems designed to obtain energy from biomass, whether from new biomass grown specifically for energy or from waste materials, are ultimately dependent on the growth of plants or photosynthetic microorganisms. They are therefore ultimately solar energy systems dependent on photosynthesis. Optimisation of these systems will require a thorough knowledge of the biology of the organisms involved and particularly of their photosynthetic and energy metabolism. Many of the systems to be discussed at this meeting have developed from classical agricultural and forestry techniques coupled to secondary processing systems developed from waste disposal systems. In the immediate future improvements in these systems will probably depend on classical techniques of plant selection and breeding. However the growth of plants in agricultural and forestry systems is very inefficient in terms of solar energy conversion, with yields rarely exceeding 1–2% while the introduction of secondary processing reduces the yield further. This may be acceptable if the biomass used would otherwise be waste, for example from food production, but greatly improved yields will be required if biomass production for

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energy is to develop on a large scale. Systems which can function on non-agricultural land will also be essential. One solution to this problem may be the use of novel or genetically modified organisms, for example the development of algal culture. With a small number of exceptions the culture of microalgae has been developed in the laboratory as a technique for studying algal photobiology. One of the results of this work has been the demonstration that algae can be grown in the laboratory with an efficiency in conversion of light energy to biomass energy approaching 30%, close to the theoretical limit of photosynthesis (1). This can of course only be achieved under very carefully controlled conditions, but it does suggest that it should be possible to greatly improve the yields obtained from more normal photosynthetic growth. Photosynthesis is normally limited by a very wide range of internal and environmental factors. Photobiology attempts to understand the mechanism of photosynthesis and provide the knowledge which will enable internal limitations to be overcome and also may eventually permit the more direct conversion of light to useful fuels. This knowledge will come from many different sources and application of the results will combine genetic information with the results of biochemical and biophysical investigation to allow the control and modification of specific photosynthetic activities. Perhaps the most immediately obvious problem where large gains in productivity might be made is photorespiration (2). Losses due to the oxygenase activity of ribulosebis-phosphate carboxylase may rise to twenty or thirty per cent of fixed carbon dioxide. This problem is the subject of major research effort at the present time. The immediate objectives being to understand the chemical reaction catalysed by the enzyme to understand why oxygenation occurs as well as carboxylation. The determination of the struture of the enzyme and elucidation of the active site, both from the amino acid sequence determined from gene sequences, and from X-ray crystal structure analysis combined with knowledge of the enzyme mechanism may eventually allow modification of the enzyme to a more effective form. The function of photorespiration must also be investigated since it would clearly be pointless to “cure” it if it is essential to the growth of the plant. Other limitations on photosynthetic efficiency lie in the earlier events of photosynthesis, the collection of light, the operation of the photochemical reaction centre, the oxidation of water, electron transport to NADPH and the synthesis of ATP (3). Light harvesting involves the absorption of light by a bed of chlorophyll molecules and transfer of the energy to the reaction centre of photosystem 1 and 2. The distribution of energy between the photosystem is the first control point of photosynthesis. In higher plants a complex control system has developed (4), sensitive to the redox state of the plastoquinone pool of the intermediary electron acceptor chain, and operating through the phosphorylation of chloroplast membrane components controlling the grana structure and protein distribution in the chloroplast membrane. Following energy transfer to the reaction centre the photochemical charge separation occurs with high efficiency but forward electron transfer is subject to control both by environmental factors and the efficiency of the electron transport chain. The electron acceptor side of photosystem 2 is particularly sensitive to control and also to damage. Electron transport through the photosystem 2 acceptor complex requires the presence of CO2 (5). In the absence of CO2 electron transport is inhibited. Photoinhibition of electron transport at high light intensities is localised on the protein which binds CO2 and the

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electron acceptors of photosystem 2 (6). It occurs at high light intensities when CO2 limitation prevents electron flow damaging the reaction centre. Apart from crop damage CO2 control of this site may significantly affect attempts to operate semi-artificial systems for hydrogen production or dye reduction. This protein is also the binding site for many herbicides. Its amino acid structure has been determined and there is considerable homology with a bacterial reaction centre protein. X-ray structure analysis of the bacterial reaction centre (7) may therefore contribute to knowledge of its structure. Genetic modification can result in herbicide resistance; it may be possible to produce modification to give independence from CO2 and resistance to photoinhibition. The mechanism of water oxidation remains the least understood part of the photosynthetic electron transport chain; it is known to involve manganese and a mechanism to accumulate four oxidising equivalents, the details remain almost combletely obscure; it is clearly one of the main areas for basic research in photosynthsis where the limitation and control mechanisms cannot be characterised until the basic system is understood (8). Many other enzyme systems are involved in the overall photosynthetic growth of a plant or alga, in the control of electron transport between the photosystems, in the control of coupling of ATP synthesis to electron transport, in the distribution of ATP and NADPH between carbon fixation, nitrate reduction and protein synthesis. All of these systems have evolved to optimise the reproductive growth of the plant, to divert the products of photosynthesis to desirable energy products will require that all of these be controlled. If the biochemistry can be understood means will have to be developed to introduce permanent modification into the strain to be used, involving complex genetic manipulation (9). Rapid advances are being made in understanding the genetics of photosynthesis, much of the chloroplast genome has been characterised, identification of nuclear genes involved in photosynthesis and the developmental control is however only just beginning. Techniques for permanent genetic modification of plants or algae using a variety of different vectors are being investigated but none have yet reached a practical stage. If such techniques can be developed the biomass for energy programme may be able to move from the present emphasis on separate production and processing systems to direct production of high value products. It may already be possible to select algae which excrete useful products and to obtain mutants with enhanced production. In the future gene insertion might be used to divert photosynthates. For example in theory photosynthates could be diverted to ethanol by insertion of only two enzymes. However such diversion would result in major changes in the energy balance of the cell and is unlikely to occur on a large scale unless all the control mechanisms involved can be understood and manipulated. However the possibility that an alga which diverted 80% of its photosynthate to for example ethanol or glycerol while growing with 10% efficiency of energy conversion might be developed would make the research effort worthwhile. It is essential if the biomass programme is to develop to its full potential that applied research should be supported by basic research in photosynthesis.

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REFERENCES (1) GOEDHEER, J.C. and HAMMANS, J.W.K. (1975). Nature 256, 333–335. (2) OGREN, W.L. and CHOLLET, R. (1983). In: Photosynthesis Vol. 2, pp. 191–230 Ed. by GOVINDJEE, Academic Press, New York. (3) HAEHNEL, W. (1984). Ann. Rev. Plant Physiol. 35, 475–503. (4) ALLEN, J.F. (1983). Trends in Biochem. Sci. 8, 369–373. (5) VERMASS, W.F.J. and GOVINDJE (1983). In: Photosynthesis Vol. 2, pp. 541–558. Ed. by GOVINDJEE, Academic Press, New York. (6) KYLE, D.J., OHAD, I. and ARNTZEN, C.J. (1984). Proc. Natl. Acad. Sci. (USA), 81, 4070– 4074. (7) DEISENHOFFER, J., EPP, O., MIKI, K., HUBER, R. and MICHEL, H. (1984). J. Molec. Biol. 180, 385–398. (8) AMESZ, J. (1983). Biochim. Biophys. Acta 726, 1–12. (9) WHITFIELD, P.R. and BOTTOMLEY, W. (1983). Ann. Rev. Plant Physiol. 34, 279–326.

THE BIOMASS TO SYNTHESIS GAS PILOT PLANT PROGRAMME OF THE C.E.C.; A FIRST EVALUATION OF ITS RESULTS A.A.C.M.BEENACKERS* and W.P.M.VAN SWAAIJ** Summary and Conclusions Four pilot plant projects aiming at the production of synthesis gas suitable for methanol manufacturing were supported by the Commission of the European Communities during a three year programme lasting from January 1982 to the end of 1984. This paper gives a first evaluation of its results. It is a personal view of the authors only. The most important properties of the four pilot plants, which ranged in design capacity from 4.8–12 tons dry wood/day, are given in Table IV. For each of these projects a checklist has been worked out with the more important and/or critical development items. The results have been condensed in Table VII. From the most successful projects synthesis gas was actually converted to methanol in a methanol pilot unit of Lurgi. The Creusot Loire plant was able to run for more than 24hrs on the CEC-bonus conditions given in Table III. Positive points of the process are excellent product gas quality for methanol synthesis, high degree of conversion of biomass, high hydrocarbon conversion and good prospects for pressurized operation; a pressurized pilot plant of 60 ton dry wood/day is to be constructed at Clamecy. Uncertainties lay in the area of heat recovery from the product gas (if desired) and possibly removal of entrained ash while the high oxygen consumption is a disadvantage. The Lurgi Circulating Bed pilot plant also operated satisfactorily for more than 24hrs nearly at CEC-bonus conditions. Only the methane content was a bit too high due to the relatively low operation temperature. Positive points of the process are high specific unit capacity; large operation flexibility, a relatively simple single bed system with proven scaling-up abilities in other areas. Due to the lower than anticipated bed temperature the unit capacity was lower than foreseen and the methane content of the product gas a bit too high. Unfortunately no data at higher temperature have been published yet and stable operation at these conditions remains to be proven. Heat recovery from the product gas was not piloted in this project. A disadvantage is the use of oxygen which will still increase a bit if synthesis gas according to the CEC bonus conditions is to be produced. The John Brown Wellman ODG pilot plant made a longest testrun of 9.5 hrs but the gas composition was still far away from the CEC bonus conditions due to the high methane content. It is not completely sure that the product gas was produced via the complex chemical mechanisms on which the process is based; possibly part of it was produced by other

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* Groningen University, Laboratory for Chemical Engineering, Nijenborgh 16, 9747AG Groningen, The Netherlands ** Twente University of Technology, Laboratory for Chemical Reaction Engineering and Industrial Processes, P.O. Box 217, 7500AE Enschede, The Netherlands

mechanisms like steam gasification. It is a pity that simple steam gasification was not tried in the test series. Positive points of the process are the use of only air as a gasification agent and the elegant solution of the solids circulation system. Disadvantages are the complex chemistry of the process, which is not yet completely proven, the high hydrocarbon content of the gas (in case methanol production is desired), the high specific stone consumption and the potential danger of sulphur emission. Not enough data are available yet to make accurate balances, specially because also a small amount of coal was co-fired in the plant during the testrun. The Italenergie/AGIP pilot plant was not yet in operation when this report was written. During the development and construction several aspects became clear however. An advantage is the use of indirect heating by which oxygen can be avoided in the primary gasification step although oxygen is used to bring the product gas to methanol synthesis gas specifications in the secondary gasifier. A second positive point is the testing of all important heat exchangers in the pilot plant. Potential problems are related to the high temperature heating wall around the gasifier, fouling problems in the primary gasifier system and recycle streams and only partial conversion of the char. Two additional pilot projects with slightly different scope have been supported by the CEC. The AVSA project (University of Brussels) concerns a double fluid bed steam/air gasifier in a special compact lay-out avoiding solids transport lines by circulating solids between gasifier and combustor by an ingeneous kind of manipulated “free convection”. A large scale pilot plant (200kg wood/hr) has been constructed and the combustor section has already been operated. Presently the gas exchange rate between gasifier and combustor is still much too high (20–40%) and this will require further development. The product gas will certainly contain tar and methane. The Twente University of Technology project on hydrogen recovery aims at recovery and pressurizing hydrogen from low Joule gases obtained by simple air gasification in a continuous process using an hydridible metal slurry in an absorption/desorption cycle. If this system can be operated on a large scale both oxygen and complex double bed gasification can be avoided. Together with existing absorption processes for CO and/or shift processes both synthesis gas and pure hydrogen can be produced. Laboratory experiments look promising and a pilot plant will be operated in the near future. Future developments improving the application prospects both for the gasification step and the methanol process are shortly discussed. The paper starts with a condensed overview of methanol synthesis processes as far as it is relevant to select an optimal upstream gasification process. 1. INTRODUCTION Biomass is a renewable, relatively clean, source of energy with a low sulphur content and with less environmental problems as e.g. coal. Main disadvantage probably is its

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scattered availability and moreover it is still a solid fuel with all the well known disadvantages of solids as fuels relative to gases and liquids. Therefore many types of conversion processes for wood to other energy carriers like liquids, gases and electricity have been developed. Liquid fuels can be made by pyrolysis, direct liquefaction or via the so called indirect route where the wood is first converted to synthesis gas which then is converted to a liquid mixture of hydrocarbons or alcohols. Comparative feasibility studies have shown that the indirect liquefaction of wood to methanol presently probably is the most promising process for generating liquid fuels from biomass. Industrial production of methanol from synthesis gas already stems from 1920 or earlier and has made a long development to a modern process. Production of synthesis gas from wood is also very old, probably more than 250 years [1], Therefore, one could think that the production of methanol from wood would not require additional research and development work. It is not true, mainly due to the difficulty in producing efficiently and economically a clean synthesis gas, preferentially under pressure. There is still no such commercial process available although a few processes are in a stage of advanced development. Most of them in the E.C. with financial support of the C.E.C. Solar Energy R&D Research Fund. A memorable event in this respect is the production by Lurgi, Frankfurt, of small amounts of methanol from wood through the indirect route, probably for the first time ever, at least in Europe, in June 1983. To provide some background information we start with a discussion on the various process routes and reactor types that could be used for producing methanol from biomass via synthesis gas. For a more detailed analysis on the possibilities, economics, and for a state of the art in the world the reader is referred to our previously published reviews (see e.g. [2], [3]). In this paper the results of the current C.E.C. pilot projects on gasification of biomass for synthesis gas production will be analysed whilst unsolved problem areas will be identified. We start, however, with a short summary on methanol production technology because this process dictates the optimal synthesis gas composition and pressure and therefore has a significant impact on the question what type of gasification process is optimal with respect to downstream methanol production. 1.1 Methanol production A modern large scale methanol plant may have a capacity of a 1000 tons/ day of methanol and is carefully energy integrated with the synthesis gas production plant. Several processes are available but the processes of ICI and Lurgi are most commonly used [4,5]. Both operate at temperatures between 220°C and 300 °C, use a copper based catalyst and operate between 50–100bar. Figure 1 gives a schematic view of the reactor section. Because methanol production via −90.77kJ/mol (1) with usually some co-production via

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−49.52kJ/mol (2) is overall strongly exothermic, heat removal from the conversion/recycle loop and efficient utilization of this heat and of the bleedstream gas are crucial factors in the process economics. The processes of ICI and Lurgi differ in a few details of which the heat removal from the reactor (by direct raising of steam (Lurgi) or by the cold shot technique (ICI)) is the most significant one [2]. One of the possible schemes for wood (or other biomass) based methanol production is given in a simplified form in Figure 2. It is based on an oxygen blown pressurized gasifier but of course also other types producing a suitable synthesis gas can be used. After the gasification step some clean-up of the gas from dust and residual tar will be required. In the CO-shift reactor the ratio of CO/H2 can be adjusted by steam addition via the catalytically enhanced slightly exothermic reaction −40.5kJ/mol (3) Then, prior to the synthesis step, CO2 and H2S have to be removed. Some CO2 can be tolerated, is in fact even essential to get the methanol synthesis going, but H2S is a catalyst poison and has to be removed completely. Wood only contains very small amounts of sulphur (<50ppm) and therefore the “sweetening step” (CO2 and H2S removal) can be relatively cheap compared to e.g. a methanol from coal process. A major problem with biomass, at least in Europe, is its scattered availability. Usually the production areas will be too small to allow for a typical methanol plant capacity of a thousand tons per day. The economy of scale of the whole methanol complex is relatively important [2]. This is mainly caused by the methanol synthesis plant. Therefore addition of the crude synthesis gas to the feedstock of a large scale (e.g. natural gas based) methanol complex could ease the large scale requirement for biomass gasification. On the other hand, the methanol plant itself could be improved and/or adapted to the wood gasifier or, generally, to small scale operation. Firstly, it should be realized that it may not be necessary to produce a chemical grade methanol if the product is to be used as a fuel and the purification step may be omitted or simplified. New methanol processes may produce more economically a fuel grade product; Indeed, such new processes have been announced recently by IFP (France) and Lurgi (FRG) [6]. Another new development of the last decade is the so called Chem Systems [7,8] LPMeOH process. Here, an inert liquid phase (typically an aliphatic C12-C21 or an aromatic C10-C11 fraction) is used to suspend and cool the catalyst. Two versions are under consideration: a liquid fluidized bed version with particles typically in the mm range and an entrained bed version with catalyst particle dimensions in the micron range. It is claimed that these processes have a higher flexibility towards fluctuations in the feedstock, better temperature control, a higher conversion per pass (reduced recycle costs) and the possibility to accept a feed with a wide variety of CO/H2 ratios.

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Factors like catalyst stability, life expectation of catalyst, attrition/erosion resistance and process economics, presently are investigated by Air Products under a DOE contract. The investigations are carried out in a 5 tons methanol per day pilot plant facility at Laporte (Texas, USA). Some fundamental chemical reaction engineering research on this process recently started at Groningen University, The Netherlands. A typical synthesis gas suitable for methanol production is defined in Table I.

Figure 1 Methanol synthesis loop

Figure 2 Simplified scheme of a possible methanol synthesis from wood Table I. Typical synthesis gas required for methanol production; H2/(2CO+3CO2)~1 Component Conc. [mol%] CO+H2 CO2 CH4+N2 H2S

maximal (typically >70) 2–10 minimal (typically <3) <10−5

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1.2 Reactor types and process conditions To produce a suitable synthesis gas from wood several different routes can be chosen. None of these are completely proven on a commercial scale, but some have reached the demonstration scale of 10–50 tons of wood gasification per day. Ideally, only useful synthesis gas components should be produced, e.g. by: (4) Apart from the fact that this reaction is endothermic it can not be realized with 100% selectivity. Already during drying and heating-up of the biomass a broad variety of pyrolysis products is produced such as methane and higher hydrocarbons, water and carbon dioxide. Furthermore, additional water and carbon dioxide will generally be produced as by-products from undesirable combustion reactions proceeding simultaneously with the gasification process while some additional methane can be formed by hydrogenation. Therefore, the composition of the raw synthesis gas will differ substantially from what eqn. (4) may suggest. Moreover, the actual composition will not only depend on the choice of gasifying agent (steam or oxygen), but also on both the reactor type selected and the operating conditions for the gasifier. We, therefore, can distinguish two main factors by which the various gasification processes can be characterized, i.e.: – process conditions – reactor type This is done in form of a matrix in Table II. Both the particularly promising combinations and the CEC supported project areas are indicated in this table. For a detailed discussion on the merits and disadvantages of the various process conditions and reactor types, the reader is referred to one of our previous reviews on this topic [2,3]. 2. THE PILOT PLANT PROGRAMME SUPPORTED BY THE C.E.C. Early 1981, the Commission of the European Communities published a call for tenders on the development of pilot plants for the production of synthesis gas from wood at a capacity of 10–20 tons wood/day aiming at methanol production [9]. Continuous downstream production of methanol from the synthesis gas produced was not part of the pilot plant program as this technology was considered to be proven already. A special financial bonus was announced to be available for those contractors that could produce, during a controlled 24hrs testrun, a synthesis gas of a specified quality suitable for methanol synthesis. These bonus conditions are given in Table III.

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TABLE II Reactor types and process conditions for gasification of wood to synthesis gas – no interest ± little interest and development \\\ important research/dev. areas /// EC supported projects Table III. Bonus conditions in the CEC pilot plant programme Duration of the testrun ≥24hrs Capacity, wood 20% moisture ≥400kg/hr dry wood ≥320kg/hr (H2+CO), volumetric percentage ≥70% Methane+HC+inert <3% * After correction for purge flows for instrument protection

Nine proposals were submitted to the Commission and discussed during the EC Workshop of 22 October 1981 in Brussels [10]. Shortly thereafter four proposals were selected on basis of optimal development potential. It meant the actual start of a three year development program of which the final reports have been published recently. The contractors involved in the programme, the process principles and the pilot plant characteristics are all summarized in Table IV. 2.1.1 Reactor types chosen As can be seen from Table IV all pilot plants are based on one or two fluid bed reactors thus providing the feedstock flexibility required to process wood chips or other biomass fragments which are generally difficult to handle in other type of reactors, specially on a large scale of operation. Moving bed reactors would require severe feedstock preselection and/or complex and costly feedstock preparation steps. Powder flame reactors would require a costly milling step as discussed elsewhere [2]. Nevertheless, the secondary gasifier of the Creusot Loire plant and to a certain extent the Lurgi Circulating Bed plant have incorporated powder flame reactor characteristics. 2.1.2 Gasifying agent The processes of both Lurgi and Creusot Loire use mixtures of steam and oxygen to gasify the wood. Agip/Italenergie basically uses steam and air but still needs oxygen in the secondary gasifier. Due to the special features of the John Brown/Wellman process, only air (and possibly a small amount of steam) reportedly will be required for this process. It should be realized, however, that for the latter process it has not been demonstrated yet that complete gasification to synthesis gas can indeed be effected without using any oxygen because, at the present state of development, the product gas

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still contains substantial amounts of methane and other pyrolysis products. Therefore, major process improvements still have to be realized before a secondary (oxygen consuming) gasification or a steam reforming step safely can be skipped from a technically feasible design. 2.1.3 Scale of operation The proven scale of operation (see table IV) is different for each of the four pilot projects but is always large enough to get all main technical problems at least identified. Nevertheless, none of them is probably large enough to allow for a safe extrapolation to the commercial scale unless additional experience from a similar reactor in a related application is available. For the Creusot Loire process a much larger pilot plant will be built in the near future. In this pilot plant also pressurized operation will be tested (±15bar). Consortium or Company

pressure design reactor [bar] capacity type [ton dry wood/h]

Creusot Loire

1

Lurgi

1

John Brown/Wellman

1

Italenergie/AGIP

1

gasification duration syngas proven next step oxygen and agent testrun methane actual steam [hrs] +HC capacity consumption content [ton dry [kg/kg dry [vol %] wood/hr] wood] 0.320 fluid bed oxygen/steam 24 0.6 0.350 2.5t/h O2:0.57 plus H2O:0.08 for primary 15bar secondary and Clamecy empty secondary tube gasifier gasifier 0.320 circulating oxygen/steam 36 6.5 0.191 not yet O2:0.453 (fluid) bed announced H2O:0.02 gasifier 0.44 double air 9.5 12.5 ±0.4 not yet only air fluid bed +0.04ton/h announced with coal chemically active solids – – – – 0.5 primary steam for 0 fluid bed primary steam gasifier gasifier oxygen for heated secondary through gasifier wall plus secondary fluid bed gasifier

TABLE IV Main characteristics of the four CEC supported gasification pilot plant projects 2.1.4 Criteria for success of the pilot projects To put the results of the pilot plant programme into perspective we will discuss for each project how the difficulties of wood gasification have been solved and to what extent the

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solutions were successful. The projects can be considered to be a complete success if all technical aspects were found to be satisfactory and an economical evaluation shows favourable prospects for the full scale operation. Unfortunately, no pre-feasibility studies are available yet to allow for a quantitative comparison of the relative merits of the four different processes if they would be operated at a full scale. Moreover, the number of variables involved and the uncertainties inherent in comparing unproven technologies will prohibit accurate comparison of wood gasification plants coupled with gas treating units and methanol synthesis plants with, as a rule, different degrees of possible integration. Elsewhere [2], we concluded that such comparative studies may predict a spread in production costs from the various methanol to wood processes of no more than 20% which is too small to be of significance in the light of the still existing uncertainties in both actual capital and operation costs. Nevertheless, if the use of oxygen can be eliminated, there may be a definite decrease in the production costs of the synthesis gas and probably also in the costs of the methanol produced [2]. Therefore, though with some hesitation, this economical factor can be translated into a technical criterium. A successful testrun of 24hrs is a direct and relatively reliable indication that at least the serious short term technical problems have been solved. Therefore, this criterium has been included in the CEC bonus conditions. On the other hand, typical long term problem areas such as erosion/ corrosion, fauling etc. will not be detected in a run of only 24hrs. Moreover, not all items of an integrated full scale plant have been piloted in the projects (e.g. heat exchangers). We made a short list of 10 criteria for checking the development of a synthesis gas from wood process (table V). Before we check the different items of this list for each of the pilot projects we will first discuss the criteria seperately.

TABLE V 10 criteria for checking the development of a synthesis gas from wood process a. Introduction of feedstock in the bed b. Danger of ash melting/agglomeration of ash c. Incomplete gasification due to a low temperature and/or a short residence time d. Methane and other pyrolysis products in product gas e. Entrainment of ash and char particles f. Use of expensive oxygen g. Safe and effective separation between gasifier and combustor (for double fluid beds only) h. Heat transfer between gasifier and combustor i. Recovery of sensible heat from product gas j. Prospects for pressurization

a. Introduction of the feedstock in the fluid bed Although this may seem to be a relatively simple matter, it is in fact a difficult development item. Due to its fibrous nature wood may easily block feeding devices. Moreover, because the feeding device is connected to a hot reactor, backmixing of heat into the feeder may cause partial pyrolysis of wood already in the feeder which may greatly promote the blocking. To provide gas-tightness and favourable solids flow often two or three separate devices in series are required.

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b. Danger of ash melting/agglomeration Wood ash may melt or agglomerate at the bed temperature or in the hot spots in the fluid bed (e.g. near the oxygen inlets). In some cases it may form a low melting eutecticum with the outer layers of inert fluidization material within the fluid bed. Agglomeration may be eminent only after several hours of operation and because the ash components may vary with the type of feedstock it remains a difficult item probably for all fluid beds operating at a temperature higher than 800–900°C. c. Incomplete gasification due to a low temperature and/or a short residence time To alleviate problems with materials of construction and with ash melting and/or agglomeration the designer is often tempted to select a low reactor temperature. However, if the gasification temperature is low then also the char gasification rate will be low and this problem at best can only be partially counteracted by char recycling. A second problem occurring at low temperatures is the low conversion rate of the hydrocarbons formed in the critical wood pyrolysis step. d. Methane and other pyrolysis products in the product gas In pyrolysis of wood unavoidedly hydrocarbons are produced, specially methane. The higher the reactor temperature the less methane and other hydrocarbons will be formed and moreover the rate of conversion of these products to CO and H2 by secondary gasification or reforming reactions is faster. Table VI gives the gas composition of both the Creusot Loire and the Lurgi pilot plant. As can be seen from this table there is a large difference in methane content which is due to the difference in the highest temperature in the process. The methane and other hydrocarbons conversion rate cannot be calculated beforehand because of unknown reaction kinetics. Therefore the actual methane and hydrocarbon concentrations can only be obtained experimentally. Increasing temperature and residence time will, however, improve the conversion of these components whilst, with decreasing temperatures below 800°C substantial amounts of CH4 will be obtained irrespective of the residence time because of thermodynamic equilibrium considerations. The other gaseous components CO, H2, CO2 and H2 use to be close to the chemical equilibrium that can be calculated from the Schläpfer model (table VI). This model is based on mass and heat balances in combination with the water shift reaction equilibrium calculated at the reactor outlet temperature:

Gas compositions thus calculated by the authors are included in table VI. Indeed, these theoretical data are very close to the composition observed experimentally.

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TABLE VI Typical dry gas compositions for the Creusot Loire and Lurgi gasification pilot plants compared to those calculated from the modified Schläpfer model. % vol

Creusot Loire experimental T 1300°C

calculated* T=1300°C

Lurgi experimental T calculated* 750°C T=750°C

H2 30.8 31.0 33.7 CO 39.3 41.2 30.0 CO2 25.0 23.3 26.6 CH4 0.6 0.6 4.9 C2 etc. – 1.6 N2+A 4.3 3.9 3.2 Heatloss 9% * Calculated by the authors from mass and heat balances assuming watershift reaction at equilibrium and assuming CH4+HC+N2 as in experiments Assumed to be equal to experimental data

33.0 31.3 26.0 4.9 4.9 3.2 5%

e. Entrainment of ash and char particles Usually a substantial fraction of the char produced from the wood in the gasifier will be entrained with the fluidizing gas together with the ash. In most cases these solids will have to be recovered from the gas and at least partially be recycled. Another solution may be secondary gasification. Ash always will have to be recovered somewhere in the system and this ash should preferably contain minor amounts of char only. f. Use of expensive oxygen As we discussed elsewhere [2] the use of oxygen contributes largely to the operating costs of a gasification process. Therefore, processes in which the use of oxygen is avoided certainly have an important advantage which then still has to be judged against any disadvantage possibly caused by the fact that no-oxygen processes usually are more complex both in construction and operation. g. Safe and effective separation between gasifier and combustor (for double fluid beds only) If the solids present in a double fluid bed system are used as a heat carrier, technical solutions must be found to allow for a sufficiently fast circulation between the gasifier and the oxidiser (or combustor/regenerator) whilst maintaining an effective gas barrier between these two fluid beds. If, alternatively, the gasifier is heated up indirectly, then the problems are in finding the appropriate materials and geometry allowing for a sufficient and often considerable amount of heat to be transferred at high temperatures on both sides of the heat exchanging area, all in the hostile environment of a fluid bed. Failure of the wall may result in a dangerous situation.

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h. Heat transfer between gasifier and combustor (for double fluid beds only) For the different types of double fluid bed gasifiers both the heat transfer rate and its control are critical design and operation parameters. i. Recovery of sensible heat from the product gas If heat exchangers are planned in the full scale operation to recover heat of a dust and/or tar loaded product gas, this cannot be considered to be a proven technology but should be piloted. j. Prospects for pressurization Pressurization of the gasification process may reduce overall wood to methanol production costs [2]. For some processes pressurization will be possible for others difficult or impossible. Specially if delicate pressure balances have to be maintained between fluid bed sections pressurization will be a difficult matter. The different pilot projects will now be discussed separately using the checklist as a guideline. Table VII gives an overview of the results of the criteria applied to the four pilot plants. 2.2 Creusot Loire Short general description [11] This process consists of a two stage gasifier with a steam/oxygen mixture as gasification agent (Fig. 3). The first stage is a more or less classical fluidized bed gasifier. Due to the relatively low gasification temperature, the primary gas still contains a lot of pyrolysis products (tar, methane, etc.) together with unconverted char. This raw gas is fed to a secondary gasifier which is essentially an empty vessel. Here, an additional amount of oxygen (and possibly steam) is added. As a result, the temperature increases to typically 1300°C and the primary product gas together with the entrained carbon particles are gasified virtually completely. a. Introduction of feedstock in the bed As explained in the report of Creusot Loire, the feeding system consists of two screw feeders in series separated by a rotary valve. The first screw will be cold, the second one can be hot due to contact with the reactor. Because the second screw has a higher feeding rate it will remain almost empty and therefore is not likely to be blocked by pyrolysis products. The rotary valve provides gas tightness to separate the gasifier from the feed bunker. This problem will become more difficult in pressurized operation as foreseen in the future development of the process and probably some additional development will be required. b. Danger of ash melting/agglomeration This problem has been avoided in the primary reactor by choosing a low operation temperature (±700°C), below the ash fusion temperature. In the secondary gasification reactor the temperature is much higher (±1300°C) and therefore all the ash will be melted here. In the pilot plant, directly after the secondary gasifier, the product gas is quenched and the ash becomes solid again. It is not completely sure that with this procedure all the ash melting problems have been solved. On what happens with the molten ash particles

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that may reach the wall no information is presented and in a commercial unit, product gases will probably be cooled down in a heat exchanger where molten ash particles might settle on the cooling surface. Although these problems have been solved in coal gasification processes (Texaco, Shell) their solution has not yet been demonstrated in the Creusot Loire process. c. Incomplete gasification, due to a low temperature and/or a short residence time Due to the two stage gasification and the high temperature in the second stage, the gasification in the Creusot Loire process is virtually complete. Consortium or Company

Complete Solution for Avoiding Safe and Introduction Melting; agglomeration gasification entrainment expensive effective of the of ash and oxygen separation feedstock of ash between char gaaifier and combustor + +P ±S + + NA + + + + NA + ± ± +± ± +

Creusot Loire Lurgi John Brown/Wellman Italenergie/AGIP ? + solved/demonstrated − not solved/demonstrated ± not completely sure ? awaits future NA not applicable to this process

?

?

?

±

?

Heat transfer between beds

Recovery Prospects of Methanol Medium pressurization grade gas Joule Gas of production production sensible heat product gas

NA NA ±

+

+ ± -

+ ± -

+ + +

?

?

-

?

?

TABLE VII Summary of different development items realized in the CEC supported gasification pilot plant project d. Methane and other pyrolysis products in the synthesis gas Due to the high temperature in the second gasification stage there are no pyrolysis products left and the methane content is very low e. Entrainment of ash and char particles Due to the secondary gasification step, practically no char is entrained with the product gas. Ash is removed in a water scrubbing step and thus collected as a water slurry. f. Use of expensive oxygen Because of the secondary gasification step, oxygen consumption is relatively high (0.57kg O2 per kg wood). i. Recovery of sensible heat from product gas No attempt has been made in the pilot plant to simulate these process steps. j. Prospects for pressurization No delicate pressurization balances have to be observed inside the plant and on these grounds the prospects for pressurization are good.

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Concluding remarks on the Creusot Loire project Due to a two-step gasification process ash melting problems in the fluid bed are eleminated and a high quality synthesis gas suitable for methanol production has been produced. These features were demonstrated during a 24 hrs testrun. The process shows good prospects with respect to pressurization and this will be demonstrated in the next phase of the project. A disadvantage is the high oxygen consumption. If heat recovery from the product gas has to be applied this has to be demonstrated for this particular process. 2.3 The Lurgi process Short general description [12] In the Lurgi process the gasifier is a single reactor with a circulating (fluid) bed (see Fig. 4). It differs from a normal fluid bed by the much higher gas velocities applied, resulting in a high circulation rate of the solids present in the system: reactor—cyclone— feedback pipe. Due to this circulation high temperatures can be maintained in the whole reactor with intensive gas-solids contact. The gasification agent is an oxygen/steam mixture. If the circulating bed can operate without ash agglomeration problems a single step gasification at high temperatures could be realized and producing a synthesis gas low in pyrolysis products. a. Introduction of feedstock in the bed The wood is fed to the reactor via a screw feeder and due to the high gas velocities applied in a circulating fluid bed no particular distribution or blocking problems are to be expected. b. Danger of ash melting/agglomeration In a testrun, which exceeded 24hrs, the reactor temperature has been relatively low (±760°C) and no ash melting problems have been encountered. At these temperatures gasification was not complete, however, and some pyrolysis products were still present in the product gas (mainly methane). At higher temperatures, where these undesired products for methanol synthesis gas can be eliminated, only short runs have been carried out [13] and therefore the absence of ash agglomeration problems cannot yet be considered to be proven for these conditions.

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Figure 3 The Creusot Loire Process

Figure 4 Lurgi’s circulating fluidized bed gasifier c. Incomplete gasification due to a low temperature Considering the temperature level of the testrun, the results show a relatively good conversion of pyrolysis hydrocarbons. Yet the absolute amount (6–7% vol) of these products is still high for a methanol synthesis gas. The exact value of the carbon/char conversion will also depend on the temperature. The problem of partial conversion can only be solved by increasing the reactor temperature. No experimental results for long

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duration runs at high temperatures (say 900–1000°C) are available at the moment. The char conversion efficiency is already good at 760°C. d. Methane and other pyrolysis products in the synthesis gas As a consequence of the previously mentioned low reactor temperatures during the testrun the hydrocarbon content of the product gas (mainly methane) is still fairly high (~6.5% vol). Just as in the Creusot Loire process this could be solved by secondary gasification (or reforming) but this has not been effected in the Lurgi project. If it is possible to obtain stable operation at a higher temperature a more attractive methanol synthesis gas could be obtained directly. Up till now this has not yet been demonstrated for a sufficiently long period of time. e. Entrainment of ash and char particles In the circulating bed system entrained ash and char is separated from the product gas by a system of a main circulation cyclone followed by secondary and tertiairy cyclones. Such a set-up indeed may allow for a recovery of ash/char mixtures at different positions in the separation process, possibly with varying char content. f. Use of expensive oxygen During the long duration testrun, the oxygen consumption was 0.45kg/kg dry wood. This seems to be significantly lower than reported for the Creusot Loire process (0.57kg/kg dry wood) but it should be realized that the product gas in the Lurgi process still contains an important quantity of hydrocarbons. Perhaps the oxygen consumption should also be compared with the first gasification step of the Creusot Loire process (0.2kg/kg dry wood). i. Recovery of sensible heat from product gas This process step has not yet been piloted, and inclusion in a commercial plant has not yet been stated. Problems could be fouling of the heat exchanger due to remaining hydrocarbons (tars) and ash/char dust. j. Prospects for pressurization Lurgi did not announce a pressurized version of the process and because the circulating fluid bed concept still has a relatively short history, little can be said about the possibilities of pressurization. Concluding remarks on the Lurgi project The circulating fluid bed gasifier operated satisfactorily and produced, during a relatively long duration run, a medium Joule product gas. On a pilot scale, methanol was produced from this gas but the hydrocarbon content (mainly methane) of the gas was still on the high side. In principle, at higher reactor temperatures (say 900–1000°C) it should be possible to obtain a gas nearly free from hydrocarbons possibly even at higher capacities. Unfortunately, up till now it was not demonstrated under such conditions for a longer period of time. Possible difficulties might be unstable operation due to low char hold-up at high temperatures and/or ash agglomeration or melting.

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2.4 Oxygen Donor Gasification of John Brown/Wellman Short description of the process [14] The process produces a medium Joule gas using biomass and air only. The reactor consists of a double fluid bed (see fig. 5) with intensive exchange of bed material between the two bed compartments via a special slot. Part of the bed material acts as an oxygen carrier from oxidiser to gasifier. In the oxidiser, oxygen is chemically bound by calcium sulphide according to: CaS+Air→CaSO4 Additionally, also some char present in the bed material is combusted in the oxidiser to provide additional heat to the gasifier system. The relatively hot, sulphate rich bed material flows from the oxidiser to the gasifier where oxygen is recovered by reduction of the bed material with the gases present in that reactor: CaSO4+4H2→CaS+4H2O CaSO4+4CO→CaS+4CO2 These reactions provide the gasification reactants H2O and CO2 which, after reaction with the biomass pyrolysis products, produces a surplus amount of carbon monoxide and hydrogen. With an additional amount of steam injected in the gasifier section and replacing the CaSO4/CaS carrier by inert material the system could in principle also operate as double bed steam gasifier. a. Introduction of feedstock in the bed The gasifier is completely surrounded by the oxidiser [14]. Therefore, ssthe biomass feedstock has to be introduced either through the bottom or through the top of the reactor. By a specially designed pneumatic feeder in series with a two screw feeder sluice system this problem has been solved successfully. b. Danger of ash melting/agglomeration This problem should be especially important for the regenerator section where the highest temperatures are found (up to 1000°C). Although a good circulation behaviour was observed in the hot bed, ash agglomeration still may become visible after a prolonged operation time. Moreover, ash agglomeration may depend on the stone refreshing (consumption) rate in the fluid bed which was very high during the particular test reported by John Brown/ Wellman. Therefore, though ash agglomeration problems have not been observed yet, long duration tests are still necessary for a final proof on this aspect. c. Incomplete gasification, due to a low temperature and/or a short residence time The data reported by John Brown/Wellman do not allow for a calculation of the char conversion, specially not because extra coal was added to the oxidiser. However, due to the coupling with a combustor, there is no reason to doubt the char conversion to be insufficient. It may be concluded that the product distribution is similar to that of a double bed steam gasifier. In fact, the evidence that the system worked in the oxygen

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donor mode is based on the strong temperature dependence of CO+H2 formation in the gasifier and on the fact that these gases were produced at a small partial water-vapour pressure in the inlet gas of the gasifier. In any case, it can be safely concluded that to reach the CEC bonus set of conditions a secondary gasification or reforming step will be necessary. d. Methane and other pyrolysis products in the synthesis gas The product gas of the ODG still contains a (too) large amount of hydrocarbons, reportedly nearly all methane (12–13 vol %). The contractors are right in stating that the process has not been optimized yet, so that this figure still may go down as a result of future optimization programme. On the other hand, we have always been sceptical on predictions with respect to methane which were substantially below those for steam gasification in fluidized beds at corresponding temperatures. e. Entrainment of ash and char particles Ash and char are removed by cyclones, preferably downstream of the oxidiser because here the ash contains the smallest amount of char. In principle, the char content in the ash can be low in a double fluid bed system, but the ODG process may require a minimum of char present in the oxidiser to prevent SO2 emission via the regenerator exhaust gases. Because also some coal was fired in the regenerator during the biomass test, no quantitative data on char entrainment can be given nor on char conversion. A special complicating factor with the ODG process is the stone handling. f. Use of expensive oxygen No pure oxygen is used in the process. The methane content, however, is still too high. May be, the contractors will succeed in getting this figure sufficiently reduced by optimizing the process in a follow-up programme. But if this fails and if secondary gasification has to be applied for getting a synthesis gas sufficiently low in hydrocarbons, then, still substantial amounts of oxygen will be necessary. g. Safe and effective separation between gasifier and combustor Product gas composition indicates a sufficiently effective and probably safe separation between oxidiser and gasifier. h. Heat transfer between gasifier and combustor Both from direct measurements in cold models and from results during gasification it can be concluded that the heat transfer with the solids flow through the slots is more than sufficient and relatively simple to operate. i. Recovery of sensible heat In the pilot plant an air preheater was installed which recovered sensible heat from the regenerator flue gas. Some difficulties were encountered during the operation due to entrained fines that slipped through the cyclone system. Although these problems may easily be overcome in further developments it demonstrates once more that for complex processes like wood gasification a completely integrated pilot plant is required to be sure that any surprise with “standard technology” in full scale plants will be eliminated.

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j. Prospects for pressurization Due to the complexity of the process it does not seem logical to pressurize the process and no developments towards a pressurized version are foreseen. Concluding remarks on the O.D.G. process of John Brown/Wellman The pilot plant has been constructed and operated for several runs of which the longest reportedly lasted for 9.5hrs. A medium Joule value gas was produced without the use of pure oxygen. The product gas did not fulfill the desired methanol synthesis gas composition as mentioned in the bonus condi-tions (see Table III). The methane concentration was still too high. Without the Introduction of a secondary gasifier or reformer it is unlikely that the methane content of the product gas can be sufficiently reduced. It is not completely sure yet that the plant indeed produced its synthesis gas mainly via the Oxygen Donor principle as a certain fraction of the gas may have been produced by other mechanisms like steam gasification in a double bed. Unfortunately pure steam gasification which easily could have been tested with (nearly) the same equipment was not carried out. At the present state of affairs the stone consumption is still rather high and should be reduced to make the process attractive. A complicating factor is that during operation on biomass, always some coal was co-fired in the combustor and no data on pure biomass conversion are available yet. Another uncertain point is the potential emission of traces of SO2 from the oxidiser. This has not been reported but no data on the actual value of SO2 in the oxidiser flue gas have been published either. If the flue gas contains a substantial amount of SO2 originating from CaSO4 than this would be a particular disadvantage for wood which is a clean almost sulphur free feedstock. Nevertheless, in applications like power generation or combined heat/power generation the ODG process looks attractive both for biomass and coal as feedstocks. The question remains whether the lower or zero steam consumption justifies the rather complex chemical system relative to the simple alternative of steam gasification with inert heat carrier in almost the same equipment, particularly if the feedstock is biomass. For methanol production, the product gas still should be subjected to secondary gasification or steam reforming unless a substantial improvement in operating performance will be realized during a follow-up programme. 2.5 The Italenergie/AGIP-S.p.A. process Short description of the process [15] A simplified scheme of the process is given in fig. 6. A medium Joule gas is produced by steam gasification of wood in the inner fluid bed. The heat for this endothermal process is provided through the corrigated wall of the reactor. Part of the gas produced is combusted in a second fluid bed located in the annular space of a vessel around the gasifier. To produce a methanol grade gas, the product gas of the steam gasification is further converted in a fluid bed secondary gasifier (cracking chamber) where oxygen is introduced, raising the temperature to 1300°C. Upon completion of this report the plant had not yet been in full operation and was still in the starting-up phase.

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a. Introduction of feedstock in the bed Because the feedstock has to be Introduced into the central bed, just as in the case of John Brown/Wellman, this is a specially complicated matter and the technical solution will have to show its usability. b. Danger of ash melting/agglomeration No problems with ash melting are to be expected in the gasifier because of the relatively low temperature Ash melting in the secondary gasifier is a potential problem only in case wood ash traces can be transported to this vessel. In the present setup, the danger of ash melting is low in the combustion chamber because the fuel used here is gas (with possible traces of ash/char) and the temperature is relatively low (850°C). c. Incomplete gasification due to a low temperature and/or a short residence time Due to the relatively low temperature in the gasifier it should be doubted that a full char conversion can be realized, specially not with steam gasification. The primary product gas will contain still a lot of hydrocarbons and methane but for methanol synthesis gas production this gas is sent to the secondary gasifier where these products are converted.

Figure 5 The Oxygen Donor Process of John Brown/Wellman

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Figure 6 The Italenergie/AGIP S.p.A. process d. Methane and other pyrolysis products in the synthesis gas No problems here because the secondary gasifier is expected to convert these products to CO and H2. e. Entrainment of ash and char particles The entrained ash and char particles in the primary product gas have to be removed at a high gas temperature. Fractional slip of ash particles may lead to blocking and fouling of the gas recycle to the gasifier, to ash entrainment to the heater/combustor and to ash melting problems in the secondary gasifier. Actual runs with the pilot plant will show whether these potential problems can be avoided. f. Use of expensive oxygen No oxygen is consumed in the primary gasification step. In the secondary gasifier oxygen will be consumed and based on the Creusot Loire experience the quantity is expected to be considerable. g. Safe and effective separation between gasifier and combustor Several potential problems can be identified for the corrugated separation wall between gasifier and combustor such as maintaining gas tightness during thermal expansion, erosion/corrosion, material stresses etc. A hot wall between two fluid beds is a relatively

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new development item on which hardly any experience is available. Also here, only the actual pilot plant test will indicate whether the technical problems have been solved. h. Heat transfer between gasifier and combustor Because the gasifier is heated-up indirectly through a corrugated wall and because fluid beds can provide high heat transfer coefficients no problems are expected with the heat transfer itself. On possible material problems with the heat exchanging wall; see under g.). i. Recovery of sensible heat from product gas Heat exchangers are provided in the pilot plant to recover sensible heat from the product gas and from the combustor flue gases but we will have to wait for the operational data to judge the performance. j. Prospects for pressurization Because of mechanical problems to be expected it seems to be unlikely that the heat exchanging wall will coincide with the separation of the pressurized/non pressurized part of the process. Therefore the whole reactor system (combustor/gasifier/secondary gasifier) will have to be pressurized. This is not impossible but certainly rather difficult. Concluding remarks on the Intalenergie/AGIP-S.p.A. process Indirect heating of the gasifier through a wall seems to be an attractive route to produce raw synthesis gas if it can be realized on a technical scale at a sufficient rate and degree of biomass conversion. If secondary gasification is done with oxygen, much of the attractiveness is lost as a large amount of oxygen will still be used. However, for medium Joule gas production and with a (secondary) steam reforming step, also in the case of methanol production, the process regains much interest. A critical condition will still be whether gas clean up from tar and particles will be sufficient for these cases. 2.6 Additional pilot projects Two additional pilot projects have been incorporated in the present pilot programme of the CEC: – The AVSA fluid bed Combustor-Gasifier Project – The Twente University of Technology project on hydrogen recovery. 2.6.1 The AVSA fluid bed Combustor-Gasifier Project (University of Brussels) In this project [16] a double fluid bed gasifier has been developed with a simple but ingeneous system of solids circulation (see figure 7). To circulate the solids between gasifier and heater and vice versa the solids are transported from a fluid bed with a lower gas velocity (and therefore higher density) via a hole or slit to a fluid bed with a higher gas velocity (and lower density). The driving force for solids transport is the difference in pressure on both sides of the holes. Both the gasifier and the combustor each consist of

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two beds separated by a wall, one with a relatively high, the other with a relatively low gas velocity. Solids are transported from the bed with a high gas velocity to the bed with a low gas velocity by flowing over the top of the wall separating these two sections. Very high solids transport rates can be obtained (up to 1000kg/per m2 transport hole area). Also the important problem of sufficiently large biomass solids circulation and segregation has been .studied and solved. A pilot unit has been constructed, but up to now only the combustion section has been tested successfully. Present problems are the gas exchange rate between gasifier and combustor which is too high (20–40%) and more development will be required to reduce this quantity. Another problem will certainly be the high hydrocarbon content of the product gas (as can be derived from small scale experiments). For methanol production this is an important disadvantage but for many other applications it will often be acceptable, provided the tar content is low. On the latter aspect, no reliable data are available yet. Char conversion can be relatively high in a double bed gasifier due to the combustion section but tar/char/ash dust mixtures entrained with the product gas may still form a difficult problem if a clean gas is desired. Nevertheless, the project forms an interesting addition to the CEC program, extending the value and being complementary to the John Brown/Wellman and the Italenergie/AGIP projects. 2.6.2 The Twente University of Technology project on hydrogen recovery This project [17] aims at the selective absorption of hydrogen at low partial pressures typical for low Joule producer gas obtained from simple atmospheric air gasification of wood. With slurries containing finely dispersed hydridible metals it is possible to recover the hydrogen continuously and get it available in a pure form at increased pressures. Because continuous processes to recover CO already exist, it should be possible this way to produce pressurized synthesis gas e.g. for methanol production from low Joule gases obtained from simple air gasification. By steam shifting of all CO to H2 it is also possible to produce hydrogen only, which then could be used e.g. for hydrogenation or biomass liquefaction. Presently, only small scale laboratory tests are available but they look quite promising. Also a continuous pilot plant (fig. 8) including the hydrogen absorber and desorber has been constructed and is being started up at this moment. Important development items are prevention of poisoning of the metal alloy slurry and possibly still increasing the volumetric absorption rate. The process could play an important role in several kinds of biomass conversion processes if it can be developed up to a commercial scale.

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Figure 7 Schematic view of the AVSA process (University of Brussels)

Figure 8 Experimental hydrogen separation and recovery unit (Twente University of Technology)

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3. FUTURE DEVELOPMENTS The four gasification pilot plant projects together with the additional pilot projects form an interesting platform for future developments both for future methanol from wood processes as well as for other biomass to energy processes. For the methanol route it is important that developments will allow a methanol plant to be economically feasible on a 100.000ton/year scale producing fuel grade methanol. This will require several modifications on the present processes which are directed to high purity methanol for chemicals on a 1.000.000tons/year scale. Probably the new fuel grade methanol and the new liquid phase methanol processes are good candidates for these developments. Another factor is the production of a cheap synthesis gas. Avoiding the use of expensive oxygen resulted in the present pilot programme always to synthesis gases rich in hydrocarbons. Therefore, it would be interesting to develop or to adapt steam reforming processes which could convert these gases to better synthesis gases; this should preferably be done immediately after the primary gasification step. Another way out could be air gasification (primary and secondary) and recovery of the synthesis gas components from the low Joule gas. Apart from possible methanol synthesis, the processes have a potential application in several other fields like: production of reducing gas, fuel gas, electricity with gas turbines, diesel aggregates or fuel cells and hydrogenative liquefaction of biomass. As stated in their paper the Creusot Loire project will be followed up by a much larger pilot project and also other projects will be continued in some form. Now, in 1985, particularly on the short term, the economic incentives for large scale synthesis gas production from biomass do not look very bright, at least not within the European Community. On the long term, however, it might well become the most prospective and attractive way of harvesting solar energy. The pilot programme of the CEC has certainly given an important contribution to this development. REFERENCES 1. S.Hales, Vegetable statics or an account of some statical experiments on the sap in vegetables, being an essay towards a natural history of vegetation of use to those who are curious in the culture and improvement of gardening. Also a specimen of an attempt to analyse the air, by a great variety of chemico statistical experiments, which were read at several meetings before the Royal Society, London (1727). Reference found in: A.J.J.van de Velde, Jan Pieter Mickelers en het steenkool gas, Mededeling van de Koninklijke Vlaamse Academie van Wetenschappen, Letteren en Schone Kunsten van Belgie, Brussels (1948). 2. A.A.C.M.Beenackers and W.P.M.van Swaaij, Methanol from Wood I+II, Int. J. of Solar Energy, (1984) 2, 349 and 519. 3. A.A.C.M.Beenackers and W.P.M.van Swaaij, Gasification of Biomass, A State of the Art Review, in: A.V. Bridgwater (Ed.), Thermochemical Processing of Biomass, Butterworths (1984) London, 91–136. 4. T.B.Reed, A Survey of Biomass Gasification, Vol III, SERI, Golden (1980); SERI/TR-33–239VI. 5. Ullmann’s Encyclopadie der technischen Chemie, 4th Ed., Band 16 (1978) 624.

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6. H.Hiller, Co-production of methanol and higher alcohols for automotive uses, E. supp, European Methanol Conf., Dec. 1984. 7. M.E.Frank, in: Proc. Intersoc. Energy Conversion Eng. Conf. 15th (2) (1980) 1567. 8. D.M.Brown, in: ISCRE-8, The Inst. Chem. Engrs Symp. Ser. no 87 (1984) 699. 9. Call for tenders, Publikatie blad van de Europese Gemeenschappen Nr C 18/2 d.d. 27–1–1981. 10. W.Palz and G.Grassi (eds.), Energy from Biomass, Vol 2, Proceedings of the Workshop on Biomass Pilot Projects on Methanol Production and Algae, held in Brussels, 22 October 1981, Reidel, Dordrecht (1982). 11. Contribution of Creusot Loire (Framatome) to final project report (to be published). 12. Contribution of Lurgi GmbH to final project report (to be published). 13. P.Mehrling, pers. communication. 14. Contribution of John Brown/Wellman to final project report (to be published). 15. Contribution of Italenergie/AGIP S.p.A. to final project report (to be published). 16. Contribution of University of Brussels to final project report (to be published). 17. Contribution of Twente University of Technology to final project report (to be published).

BIOMETHANATION, THE PARADOX OF A MATURE TECHNOLOGY E.-J.NYNS, M.DEMUYNCK and H.NAVEAU Unit of Bioengineering, University of Louvain, 1/9, Place Croix du Sud, B-1348 Louvain-la-Neuve, Belgium Summary Biomethanation is an anaerobic biological energy-yielding and depolluting process by which organic matter (among which residues and wastewaters) is bioconverted in methane-rich biogas. Five hundred fifty biogas plants have been identified in Europe and were scrutinized by a team of twelve experts. The results of this vast inquiry reveal that biomethanation is definitely a mature technology. Yet its implementation cannot be called a success. Why is this paradox? Biogas plants on family farms can be economical but seldom are so. Either the investment cost has been too high or satisfactory performances of the process could not be maintained over long periods of time. Biogas plants in agro-industries are just becoming well-established environmental biotechnologies. Landfills are more and more looked at as economically attractive sources of biogas. Biogas refineries, that is large-scale industrial biogas plants, are being seriously thought of. Biogas from energy crops remains of socioeconomical interest. The latter five propositions are substantiated in the present paper.

1. INTRODUCTION Methanogenesis is a process by which a vast number of microbial species -up to 20organize themselves in a dominant and, hence, very stable microbial community and degrade almost any organic compound all the way down to methane, CH4 and inorganic carbon, namely carbon dioxide, CO2, which escapes with the methane as biogas, and hydrogenocarbonate, HCO3−, which remains in the liquid effluent. The process of methanogenesis still rises a number of questions of great scientific interest but its understanding is nowadays largely sufficient to allow the process to be mastered in a reliable biotechnology (Winfrey (1), Daniels et al. (2)). A large variety of methane reactor designs, well appropriate to the methanogenic processes, are presently at hand to biomethanize almost any biomass substrate, whether a wastewater, a slurry or a solid residue in a reliable, performant and hence economically attractive way (Kirshop (3), Sahm (4), van den Berg (5)). Still, the implementation of biomethanation, a mature biotechnology, in Europe, in the industrial world as well as in the developing countries cannot yet be called a success. Why is this paradox?

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2. A SURVEY COMMISSIONED FOR THE DIRECTORATE GENERAL FOR SCIENCE, RESEARCH AND DEVELOPMENT (DG XII) OF THE COMMISSION OF THE EUROPEAN COMMUNITIES WITHIN THE FRAMEWORK OF ITS SOLAR ENERGY R AND D PROGRAMME An assessment of “Biogas Plants in Europe” was realized between mid 1981 and early 1984 by a team of 12 experts. Each of them identified, visited and scrutinized almost every methane digester existing in his home country, following a common format. By 1983, a total of 546 methane digesters, were built in the European Community and in Switzerland. A synthesis of the survey has been published as a book intended to give guidance on the state-of-the-art and possible future developments (Demuynck et al. (6)). Individual results and national papers have been gathered in a three-volume compendium (Demuynck and Nyns (7)). For the economic analysis, The Financial Model Processor perfected as a processing tool by Schepens was used. This model not only allows the calculation of the Simple Pay Back periods but also of the Net Present Values and the Internal Rates of Return. 3. BIOGAS PLANTS ON FAMILY FARMS By 1983, 420 biogas plants, among which 378 full-scale plants and 42 pilot-scale plants, were treating agricultural wastes. The total digestion working volume was 95000m3. Two hundred ninety one biogas plants were treating liquid or semi-solid wastes, mainly cattle and pig manure. Fourty five biogas plants were treating solid wastes, mainly manure with bedding. Seventy seven biogas plants were treating mixed agricultural wastes, mainly mixtures of manures. Biogas plants on farm can be economical, but this is seldom the case. There are two major reasons for this: too high an investment cost or too low performances. Among the 32 biogas plants for which enough data were available for a valuable economic analysis, only 6 were found profitable. Among these were 3 out the 5 Do-ItYourself biogas plants. Their Simple Pay Back periods lie between 3 and 4 years and their Internal Rates of Return are higher than 30% which in turn is higher than the capital cost of 15%. Although they have a low daily biogas production, below 1m3 biogas per m3 of digester working volume, they are still profitable because their investment cost lie between 100 and 160 ECU per m3 digester working volume. Three biogas plants, constructed on a turn-key basis by companies, among which one includes an electricity generator, are profitable with Simple Pay Back periods of 5 to 6 years and Internal Rates of Return higher than 15%. An average complete biogas plant on farm includes the methane digester itself, the system of gas storage and utilization and the system of influent and effluent storage and/or treatment, if any. The methane digester itself is of the continuous, completelymixed type without recycle. The threshold value of the investment cost for a complete biogas plant on farm for profitability was found to lie between 400 and 450 ECU (value 1983) per m3 working volume of the methane digester. When the investment costs were analyzed as a function

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of the scale of the methane digester, it appeared that the price per m3 digester working volume decreased with increasing scale, up to 100m3, when the investment cost per m3 became more or less stable. Whenever the investment cost is too high, nothing can be done afterwards to cure the problem. For profitability, the performance of an average biogas plant on farm must be at least equal to 1m3 biogas, containing 1/2 to 2/3 methane, per m3 digester working volume and per day. This performance must be maintained over most of the year. As a general result from the survey, it appears that each existing biogas plant on farm has suffered during its present lifetime an average of 2 major and 4 minor problems. Major problems result in the temporary shut down of the biogas plant. Major problems were encountered as well with the loading device (mainly failure of the feedstock pump) as with the methane digester itself (mainly gas leakage, insufficient mixing or heat transfer) as with the gas collection storage and utilization (mainly with the biogas compressor, the engine running on biogas, and the waste heat recovery system). Major problems were not only encountered with the equipment but also with the operation of biogas plants. Upstream of the methane digester, settlement during storage, foreign water entry and scum formation, blockage of loading pipes and operational problems with heating of feed, during digestion, settlement in the reactor and scum formation were among the principal causes of failure. Gas metering was an often encountered major problem. A wide variety of other phenomena caused major problems in few cases and numerous minor problems. These problems were mainly encountered during the two first years of operation of a biogas plant. Quite often, the treshold of performance was reached thereafter, so that the present impression of lack of profitability must be taken with a grain of salt. Why do these two reasons apply so often? First, many is not most existing methane digesters are each the first one if not the only one constructed by either its owner or a small entreprise. The know-how of methane digestor construction and operation exists but is not well widespread. In as much that the same basic errors have been made over and over again. Secondly, methane digesters are often poorly integrated in the farm: not enough agricultural waste upstream, ill-studied end-uses for the produced biogas. As a consequence, the implementation of new biogas plants on farm presently suffers from adverse publicity by owners of existing biogas plants. 4. BIOGAS PLANTS IN AGRO-INDUSTRIES OR IN VERY LARGE ANIMAL BREEDING UNITS By 1983, 89 biogas plants, among which 69 full-scale plants and 20 pilot-scale plants were treating industrial wastes or wastewaters. The total digestion working volume was 174000m3. Twenty one different types of industrial wastewaters and 2 different types of industrial wastes served as substrate biomass or load for biomethanation in industry. Most wastes originated from agro-industries although a few wastewaters originated from the leather, wooden plates or paper industries. Continuous, completely-mixed systems were only used for the biomethanation of animal manures from large scale animal breeding units. Up-flow anaerobic sludge beds

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and fixed-film systems competed as mature full-scale biotechnologies. Fluidized beds exist as experimental full-scale plants. The investment cost for an industrial biogas plant per m3 biogas produced was about the same as that for a biogas plant on farm. Its performance is however 1 to 5 times better. Its investment cost per m3 working volume appears therefore larger than that of a biogas plant on farm. However, the cost of the methane reactor itself in an agricultural biogas plant amounts usually to around 30 to 40% of the overall cost. The cost of the methane reactor itself in an industrial biogas plant amounts usually to around 20% of the overall cost. The reason for this difference is that industrial requirements for efficiency and reliability are more severe and, hence, require extra-ancillary equipment. Often also industrial quotations include the costs of start-up and one-year follow-up. Besides energy production which is still a too often neglected end-use, pollution control is the major target. The fringe benefit of dépollution is more evident for industrial biogas plants than for biogas plants on family farms. A few constructors possess sufficient know-how to warrant safe investment cost and reliability of the biogas plant. As a result of all this, the anaerobic biological wastewater treatment has become quite competitive with aerobic biological wastewater treatment. Both technologies appear equal in the two following aspects: mean hydraulic residence times, θH, which even tend to become lower in anaerobic systems (less than 1 day down to a few hours), and cost for the maintenance of the equipment (a yearly average of 2% of the investment cost). Anaerobic wastewater treatment systems offer the following advantages over aerobic systems: lower investment cost and lower production of excess sludge which is furthermore already stabilized. Aerobic wastewater treatment systems offer the following advantages over anaerobic systems: better performances (conversion, N-treatment), larger array of applications (including cold and low-strength wastewaters) and a still betterreputed reliability with time. Aerobic wastewater treatment is energy-costly: ±1.8 electric MJ kg−1 removed COD. Anaerobic wastewater treatment is energy-yielding: ±12 thermal MJ kg−1 removed COD. Safely constructed, well managed existing industrial biogas plants offer positive support for new industrial decision making. Industrialists and certainly agroindustrialists, as well as Water Authorities must nowadays at least take into consideration both anaerobic and aerobic treatment systems on a comparative basis when seaking a solution leading to environmental control. 5. EXTRACTION OF BIOGAS FROM LANDFILLS Domestic waste represents a permanent source of organic matter of the order of magnitude of 0.5–1kg per inhabitant per day. Individual landfills, where millions of tons of domestic waste are disposed off, are natural biogas plants from which vast quantities of biogas may or might be extracted over long periods of time. 1 ton of domestic waste, as it comes, can produce 5 to 10m3 biogas per year during 10 to 20 years. Hence, an average landfill of 10 million tons domestic refuse will produce yearly between 50 to 100 million m3 biogas which is equivalent to 800 to 1600 trucks of 25 tons of fuel each year.

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Whereas 2 sites only, where biogas was being extracted, were identified in Europe in 1980, 36 sites were identified in 1983 and this number is expected to grow rapidly. In as much that the Commission of the European Communities intends to undertake a special inquiry to update the know-how and know-where of landfills for biogas extraction. Spreading of biogas extraction from domestic wastes will thus most probably follow up the spreading of industrial biogas plants as a second successfull wave. The following technical developments may be expected in the 5–10 year term: improvement of technologies for biogas collection, organisation of new landfills specially for biogas collection, namely recovery of the leachate and its treatment in a separate biogas plant. But some industrialists are already thinking in terms of biogas refineries where domestic waste would be industrially treated by advanced biogas plants. Reliable continuous reactors made to handle solid biomass substrates remain the present bottleneck. 6. BIOMETHANATION OF ENERGY CROPS The growth and harvest of energy crops as a potential biomass substrate for biogas production remains at present in the R and D state at least in Europe. When energy production is the sole output, the process is not economically attractive. But, when besides, dépollution becomes a major target, as is the case in the lagoon of Venice, or when the digested mixed liquor can be valorized for agricultural use because of its fertilizer value or its compost-like properties, as was planned in the Lamezia project (Asinari et al., (8)), the process may become of socioeconomical interest. Further development could be promoted if energy crops were to replace excess food crops and financial aids for the latter used as incentives for the former. 7. THE WAY AHEAD First and foremost, a European network of selected biogas plants should be monitored and made to contribute to a substantial popularization effort of biomethanation to create on farms and develop in industries, a confident market. Basic research should aim at improved performances on a larger array of substrate compounds and provide energyyielding molecules other than methane. Research on engineering should aim at cheaper, more reliable, as well as second-generation, highly performant methane digesters. Appropriate integration of biogas plants on farms remains a major target. Upgrading of side-products will add fringe profits. Adequate legislation as regard safety as well as sales practices, should help implementation. This is the message on which the 12 experts of the CEC inquiry on “Biogas Plants in Europe” unanimously agreed.

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REFERENCES (1) WINFREY, M.R. (1984). Microbial production of methane. In “Petroleum Microbiology” (R.M.ATLAS, ed.) McMillan, New York, N.Y., 153–219. (2) DANIELS, L., SPARLING, R. and DENNIS SPROTT, G. (1984). The bioenergetics of methanogenesis. Biochim. Biophys. Acta 768, 113–163. (3) KIRSOP, B.H. (1984). Methanogenesis. CRC Crit. Rev. Biotech. 1 (2), 109–159. (4) SAHM, H. (1984). Anaerobic wastewater treatment. Adv. Biochem. Engin. Biotech. 29, 83– 115. (5) van den BERG, L. (1984). Developments in methanogenesis from industrial wastewater. Can. J. Microbiol., 30, 975–990. (6) DEMUYNCK, M., NYNS, E.-J. and PALZ, W. (1984). “Biogas Plants in Europe: A Practical Handbook”. Reidel Publ. Co., Dordrecht, Neth. (7) DEMUYNCK, M. and NYNS, E.-J. (1984). Biogas Plants in Europe. Compendium of Original Formats and National Papers. Vol. 1. F.R. Germany, Denmark and Netherlands. Vol. 2. United Kingdom, Ireland, Belgium and Switzerland. Vol. 3. France, Italy and Greece. Publ. EUR 9096 of the CEC. To be obtained from the authors at their affiliation. (8) ASINARI di SAN MARZANO, C.-M., LEGROS, A., NAVEAU, H.P. and NYNS, E.-J. (1983). Biomethanation of the marine algae Tetraselmis. Int. J. Solar Energy 1, 263–272. (In collaboration with R.MATERASSI, Firenze, Italy).

NOVEL METHODS AND NEW FEEDSTOCKS FOR ALCOHOL FROM BIOMASS U.RINGBLOM Alfa-Laval AB, Tumba, Sweden Abstract Sweden, where the climate favours cereal production, has a steadily increasing grain surplus. At the same time the country is an importer of protein feeds as well as of all petroleum products. Along with the national schemes for renewable energy resources, the Swedish Farmers’ Coop has built the first fuel alcohol plant utilizing excess grain. The 20 000 1/day plant was commissioned in late 1983 in the county of Skaraborg and demonstrates, at Swedish conditions, the feasibility for ethanol blended gasoline and coproduced high protein animal feed. The Skaraborg plant is based on a truly continuous fermentation process, which allows the use of concentrated feedstocks and avoids the effluent problem. Commercial Biostil plants, using molasses and concentrated cane juice, are already in operation in e.g. Brazil. The application of the process to grains involved the solution of challenging separation problems as well as the thermal integration of the distillation and animal feed drying sections of the plant. The technical considerations are discussed together with the economical aspects of fuel alcohol production.

INTRODUCTION Sweden has a fertile soil and a fair climate which favour cereal production. The highly rationalized agriculture gives steadily larger crops and an increasing grain surplus. Most of it is currently exported to the world market, although at prices lower than those guaranteed to the Swedish farmers. Having no mineral oil resources Sweden imports all its petroleum products. The country is also a net importer of protein feeds. Along with several other national schemes aiming to find efficient use of renewable energy resources, the Swedish Farmers’ Coop built the first fuel alcohol plant which utilizes excess grains in 1983. The Skaraborg plant produces 20 000 1/day of anhydrous alcohol from feed grade wheat. The alcohol is marketed as a 4% gasoline blend.

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Coproducts are protein-rich feed of unusually high quality, bran and carbondioxide. The animal feed is used by the Farmers’ Coop in the cattle feed mix where it partly replaces imported soy protein. The CO2 is liquefied and used in the beverage industry. The Skaraborg plant is based on a truly continuous fermentation system. In this unique system, using the Biostil concept, the fermenter is fully integrated with the primary distillation, which leads to significantly reduced effluent volumes. Furthermore the problems with bacterial infections, which often plague continuous fermentation systems, are avoided. The process was initially developed for clean substrates. Two plants are in operation on cane and beet molasses and four more plants are scheduled to come on stream in 1985. PLANT DESIGN Apart from the application of the process to grain feestocks, the Skaraborg plant has demonstrated a number of other “firsts”. The plant is first to apply yeast recycle to a continuous whole grain mash fermentation and to utilise part of the disitllation heat to dry the animal feed product. The stillage dryer was designed to work at a low temperature level to ensure good digestibility of the dried protein-rich feed. A basic feature of the fermentation concept is the ability to accept very concentrated feedstocks, which is exploited also in the application to grains. In the Skaraborg plant, every ton of wheat processed requires only 0.5 ton of process water. This dramatic reduction in process water requirement permits the recovery of a dried animal feed product in a very simple process which avoids the need for separation and evaporation of a grain solubles fraction. The plant produces no liquid effluents. Typical product pattern from Swedish wheat is shown below:

PROCESS SECTIONS The basic process sections are illustrated in fig. 1. The fermentation section is a key feature of the Skaraborg plant and it influences the design of all the other process sections. In mid 1984 the plant was extended with a process line for A-starch recovery. The effluent from the starch line is routed to the fermentation section. Fermentation Contrary to clear substrates, it was soon realized that whole-grain feedstocks would require considerable modification of the basic Biostil concept in order to be able to

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handle the insoluble fraction of grain. A first approach was to separate the insolubles from the saccharified feedstock prior to fermentation. However, the cost of making such a separation was prohibitive if excessive sugar losses were to be avoided. The finally accepted solution was to separate fibre and protein within the recycle loop. Such an approach has two signigicant advantages. 1. Viscosity after fermentation is relatively low, thereby facilitating separation. 2. The fermenter liquid contains only residual sugar concentrations which eliminates significant sugar losses. The practical implementation of the fibre and protein separation is illustrated in figure 2. Unlike in the clear substrate substrate system, the stream leaving the fermenter cannot be pumped straight to the yeast centrifuge. The fibre is first separated on a bent sieve and the fibre-free phase transferred to the centrifuge, where yeast is separated and recycled to the fermenter. The fibre phase is further washed in a rotating sieve to remove residual yeast, which is subsequently recycled to the fermenter. The stream entering the yeast centrifuge contains both yeast and grain proteins and it is essential that a separation be made between these two components if an execcive build up of protein in the fermenter is to be avoided. Fortunately, yeast is slightly more dense than grain protein and, uder the steady state conditions prevailing in the process, it is possible to separate more than 95% of the yeast togehter with only a small amount of grain protein. The bulk of the grain protein leaves the separator in the light phase and is transferred to the mash column. The proteins leave the system as a component of the stillage. The single fermenter works at constant conditions chosen as to give optimum operation. Since all conditions are steady the operation is easy to control. The fermenter temperature is kept at 32°C and pH at 4.5. The alcohol content is 6.5–8% voland the residual sugar level around 0.1% wt. The concentration of vital yeast cells in the fermenter is around 300 millions per ml. A remarkable feature of the Biostil fermentation system is that it sidesteps the otherwise common problems of bacterial infection. This experience from operation of molasses and cane juice plants located in tropical countries, has been reaffirmed in the Skaraborg grain plant. The fermentation was inoculated with a yeast slurry in November83 and no new inoculation has been required due to infections since then, despite a number of routine production stops and holiday shut downs. This microbiological stability does not mean that bacteria do not grow in a Biostil fermenter, but to balance this bacterial growth the recycle of the fermenter liquid through the primary distillation column ensures a very effective destruction of bacterial cells. At equilibrium only very low levels of bacteria are present in the fermenter. The low pH and low sugar concentration in the fermenter also help to suppress bacterial growth. Milling and starch conversion The short residence time in the fermenter requires that the starch be saccharified prior to fermentation, as illustrated in fig. 2. The dry milled wheat, from which a certain amount of bran has been separated, is mixed with weak beer, process water and enzymes to effect starch liquefaction at around

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90°C. After flash cooling the liquefied substrate is saccharified using glucoamylase enzyme. Distillation The distillation system is designed to produce anhydrous industrial alcoholof min 99.8% wt quality. Distillation is achieved in four columns: mash column, rectification column, dehydration column and a regeneration column, which recovers the cyclohexane entrainer. Efficient use of energy is achieved by operating the rectifier under elevated pressure and condensing the rectified vapour in the reboiler of the mash column. Subsequently the top vapours from the mash column provide the reboil heat for the dehydration column. The mash column is split into two sections, as is typical of the Biostil system. Stillage leaving the mash column has a very high dry solids concentration, usually above 30%, and is transferred to the drying section without dewatering. A significant proportion of the heat utilized in distillation is recovered and used for drying the pelleted stillage. Stillage Drying In Sweden, the price obtained for the DDG depends upon its nutritional quality. A stillage drying system was developed for the Skaraborg plant to utilize very gentle conditions (fig. 3). The pelleted product, containing 35 percent moisture, is dried against 70°C air in a two stage grain dryer. The moisture content of the wet pellets is adjusted by recycling milled dried pellets and mixing this dry material with stillage from the mash column prior to pelleting. After some initial trimming of the dryer conditions, the dried animal feed product (of 85–90% DS) demonstrates a very high digestibility, as indicated by a pepsine solubility in exess of 80%. The protein content is usually 35–40% wt (on DS). OPERATING EXPERIENCE Preceeded by extensive pilot plant work the Skaraborg plant was brought on stream, despite the many novel features, with only minor adjustments. During this first year of operation the plant has proven the realiability of the process but, more important, it has demonstrated the feasibility to utilize all products obtained from surplus wheat. Some operating data: In fermentation the ethanol yields are 92% of theoretical (G.L.). Despite the relatively small capacity of the plant, which did not justify maximum energy savings, the steam consumption of the entire plant including dryer is 3.7kg per litre of anhydrous ethanol. Three operators per shift run the entire complex including the next door CO2 plant. Since all f lows are constant and conditions steady, the plant is easy to monitor. A microprocessor is installed for the control system.

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ETHANOL AS FUEL The ethanol produced in Skaraborg was introduced by a domestic oil company as a 4% gasoline blend in the greater Stockholm area. The oil company reports a positive response to the new gasoline grade. In winter time it eliminates the need for anti-freeze “carburator alcohol”, which otherwise is commonly added by the car drivers at the filling stations. The ethanol blend, which is prepared at a local depot, required an initial cleaning of all storage tanks to be used and careful transport routines are maintained to avoid water contamination. ECONOMICS The economics for ethanol namufacture from grain are exemplified in fig. 4 for Swedish conditions based on the Skaraborg operation (1985 domestic prices). Raw material costs represent 60–70% of total production costs and the price level for wheat has a dramatic impact on the economics. Maximizing ethanol yield is essential but reduction of energy consumption is also vital to the overall economics. While the energy demand for fermentation is low, the major part of the energy required is for distillation and stillage processing. The low water requirements and the correspondingly reduced stillage volumes in the Biostil, leads to savings in stillage processing of 10–20% of the total energy consumption. Furthermore, the total investment in Skaraborg could be reduced by 10– 20% since equipment for stillage dewatering and evaporation were not required. It is noteworthy that a substantial part of the by-product credit is related to the proteinrich feed fraction and its quality. The straight cost comparison illustrated in fig. 4 shows the minimum ethanol price. The value put on domestic fuel ethanol will, however, be determined by national considerations for such aspects as agricultural area reserves, employment and lead-free gasoline. A general Introduction of ethanolblended gasoline in Sweden would correspond to an annual demand of 200–300 000m3 ethanol. The foreseen capacity of the large scale plants is 50–70 000m3 per year. At higher capacities the additional gain from economy of scale is counter balanced by increased transport costs.

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Fig 1. Skaraborg plant process sections

Fig 2. Biostil section

Fig 3. Skaraborg stillage dryer

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Fig 4. Economics for ethanol production from wheat

USE OF ALGAL SYSTEMS AS A SOURCE OF FUEL AND CHEMICALS E.BONALBERTI and U.CROATTO Centro Studi Applicazioni Risorse Energetiche (CSARE)-Venice (Italy) Centro Tecnochimico (C.T.) and Consiglio Nazionale delle Ricerche (C.N.R.)Padua (Italy) SUMMARY Micro-and macroalgal systems are examined for their direct uses or upon chemical transformations as a sources of power, food, and chemicals in diverse anthropic, farming, and industrial activities.

1. ALGAL SYSTEMS Algal systems, which are present on the planet in staggering amounts with rapid reproduction features, may play an important role in the fields of energy (in the broad meaning, such as fuels and foods) and of chemicals (chemical elements collected from the environment and collected or synthesized compounds). This stems also from the realization that many non-renewable energy and mater resources of the planet are progressively and rapidly dwindling and the human population is increasing exponentially together with its living standard, which require a carefully planned environment management. As is known, algal systems are made up by autotrophic organisms belonging to thallophyta cryptogams. Algae vary widely in size and structure. They may be either microscopic or tens of meters long with mono- or pluricellular structure. They may grow in either fresh or salty water, on rocks, on humid soil or tree bark either alone or in symbiosis with other organisms. Algae are coated by a cell membrane that generally contains mucilage, si licic, or calcareous substances. The plastids contain chlorophyll and often other pigments (chlorophyll, phycoerithrine, phycoyanine, phycophaeine, xanthophyll) wich allow algae to develop and grow by photosynthesis under different environmental illumination conditions. Reproduction occurs by scission in monocellular algae by means of spores in polycellular algae. The main limiting factors of algal growth in sufficiently deep water are temperature, presence of nutrients, low content of poisonous substances, and light availability. In the lower part of macroalgal colonies in deep waters light is drastically reduced, causing the system to cease growing in thickness so that sta tionary conditions are reached. When part of the material is removed from such colonies, its replenishment at the stationary level is rapid.

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Whereas in open water algal systems keep on growing, in lagoon, lake, or river basins, the size of the system reaches a limiting value which varies with seasonal conditions. For example, the Venice Lagoon system (550 square km) has a stationary presence of wet macroalgae (ulva lactuga, ulva ri– gida, gracilaria confervoides, chetomorpha aerea, valonia agropila) of ca.2 million tons in warm months and of 0.5 million tons in cold months, When al gal collection is carried out in such a basin in warm months (AprilSeptember), the material is regenerated in about 3–5 days, Therefore, by partial collection (about 3/4 of the algae present, in order to mantein the original algal productivity) programmed at 3–5 day intervals, a total availabi lity of ca. 68 million tons might be effected in 6 months, which is about 34 times the residing stationary amount. Algal systems in water basins are generally able to extract and concentrate substances from the waters, so that they can exert a remarkable purifying action as far as pollution is concerned. Mono- and polycellular algae make up phytoplankton and are the first step of food chain in natural or artificial reproduction (aquiculture) of fish, crustacea, and mollusca. Some algae are used in the production of feeding mixtures and also in hu man feeding, especially those rich in high-value proteins. The aerobic fermentation of algal biomass yields biogas as a fuel, which is one of the topics of this symposium. Some particular algae yield chemicals, whereas diatomaceous earth is extracted from fossil siliceous algae deposits converted into sedimentary rocks. Deposits of microalgae are the source of organic substances from which oil and natural gas were developed in ages. In symbiotic associations between algae and fungi (lichens) algae provide a photosynthetic biomass for the fungus, which in turn collects by its hyphae the water and mineral salts making them available also for the alga. Lichens grow on tree bark and rocks. They are quite common in alpine and ar ctic regions (steppes, tundras, northern sea coasts). They can also thrive in place where life would be impossible for both algae and fungi. alone. They survive in extremely low temperature and play a major role in the formation of farming soil since they crush rocks by their excretion productus and lea ve organic debris for the settling of other plants. Some lichens also yield chemicals of industrial interest. 2. FUEL FROM ALGAL SYSTEMS 2.1. INTRODUCTION —The energy crisis has shown the opportunity to use renewable energy sources as an alterative to non-renewable ones, such as fos sil and fissile fuels which are dramatically dwindling. Such renewable energy sources are essentially related to solar energy flux, geothermal energy and to the mechanical energy flux (tides) due to the gravitational attrac—tion of other heavenly bodies. As for the solar energy flux, an important ro le is related to the photosynthetic production of biomass. Any energy source is exploitable if it meets the requirement that the energy expenditure for extraction and use is lower than the energy produced. Algal systems of

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water basins appear to satisfy this requirement since the material is located at the surface and easily collected and there are several means of tapping the energy stored in then. 2.2. COMBUSTION OF ALGAE —Microalgae are not usually employed for combustion, due to the large amounts of water they contain, the difficult collection, and the other better uses that they lend themselves to. Combustion of macroalgae requires their prior drying which is easy to carry out,due to the state of this biomass, but which is energy consuming. Drying can be carried out from June to September under sunlight on soils that are not used for farming in such period. The dried material is fit for combustion even in pul verized form, but further experimenting is in order, 2.3. THERMAL TREATMENT OF ALGAE —Microalgae are not used in this fields for much the same reasons detailed under 2.2. Thermal treatments of macroalgal biomass yields instead solid (charcoal and tar), liquid (hydrocar—bons and derivatives), and gaseous fuels (hydrocarbons and derivatives), be sides chemicals of interest as such, related under 4. Macroalgal biomasses, previously dried, can be “pyrolyzed”, that is, thermally “decomposed” in the absence of air in a proper reactor heated by combustion of part of gaseous products. Alternatively, algae can be subjected to “gassification” by heating with a limited amount of air, or better, oxygen, with formation of the gaseous fuel carbon monoxide. If the biomass is only partially dried, the water also takes part in the reacting system to yield large amounts of hydrogen, another gaseous fuel. Both pyrolysis and gassification are still under experimental study at CSARE-Venice. 2.4. BIOGAS FROM ALGAL BIOMASS —Production of biogas (methane and carbon dioxide) from algal biomass by anaerobic fermentation in aqueous me—dium has been the subjest of intensive study in some countries under both mesophilic and thermophilic conditions. The fermentation take place in two consecutive stages: methanogenic and acidic. The main studies in Italy, mostly supported by CEE funding, are the following. a) Microalgae: at the Autotrophic Microorganism Center-C.N.R., University of Florence (prof. G.Florenzano) in collaboration with the Biophysics Dept., Technical University, Aachen (prof K. Wagener) and with the Unite de Génie Biologique, Louvain (prof.E.T.Nyns and H. Naveau). These studies are being carried out at Lamezia Terme (Southern Italy), using the microalga tetraselmis in see water in shallow basins located along the coast line and having a high growth rate (doubling of biomass in ca. 2 days). Microalgae are separated from the liquid phase and subjected to anaerobic mesophilic fermentation to yield biogas. b) Macroalgae: at CSARE-Venice, in collaboration with AGIP NUCLEARE (ENI) and at C.T.-Padua in collaboration with ISTITUTO CTRC.N.R.- Padua. The macroalgae ulva, gracilaria and valonia are collected from the Venice lagoon basin by means of appropriate boats and subjected to anaerobic mesophilic fermentation.

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It is noteworthy that biogas production does not entail energy expense for biomass drying since fermentation requires the presence of water anyway and the biogas separates out spontaneously through physical phase change. Anaerobic biomass fermentation also produces small amounts of hydrogen sul—fide in the biogas due to the presence of sulfur-containing proteins in the algae and to reduction of sulfates present in the algae through transfer from sea water. CSARE and C.T. studies have defined the separation conditions from the biogas of methane, carbon dioxide and hydrogen sulfide to yield a better fuel (pure methane). A remarkable advance in anaerobic fermentation technology has been achie ved by grinding and pressing the macroalgal biomass, collecting and filte—ring the pressing liquid and percolating it on anaerobic fermentation bacte tial colonies immobilized on solid bodies. Owing to the homogeneous features of the liquid material to be fermented and to the higher concentration of bacteria, the kinetics is ca. 25 times faster than when operating on wet macroalgae as such. This entails the notable benefit that size and cost of the plant are reduced by ca. 25 times, other things being equal. This technology has been applied jointly by CSARE and AGIP NUCLEARE to ul va and by C.T. to valonia. As for the use of methane on biogas as an energy source, its combustion can yield thermal energy, electric power, or a mixed power production, depending on energy use demands. In Italy the use of power plants “TOTEM” using a FIAT 127 car engine have proven quite satisfactory. 3. FOODS FROM ALGAL SYSTEMS 3.1. MICROALGAE AS FOOD FOR ZOOPLANKTON AND AQUICULTURE LARVAE —Reproduc tion and raising of fish, mollusca and crustacea is known to start up with the animals larvae which require microalgae-based food, i.e., phytoplank ton (e.g. artemia salina), followed by subsequent feeding on microfauna (e. g. rotifers), to end up in the adult stage with macroflora and macrofauna or artificial feeding. In natural water basins phytoplankton reproduces and grows in fertilized environments, like all autotrophic plants. Zooplankton, on the contrary, being etherotrophic, reproduces and grows by feeding on phy toplankton or on other zooplankton. Finally, for the initial stage in fish, crustacea and mollusca aquiculture, the larval plankton food is produced in appropriate phytoplankton rearings in fertilized and lightened waters; part of this phytoplankton is also used to produce and feed the zooplankton necessary as the subsequent plankton food. This technology is now widely applied in many countries such as Italy. 3.2. MICROALGAE FOR HUMAN FEEDING —Some microalgae are particularly sui ted for human feeding due to their high growth rate and chemical composition. Worthy of mention is spirulina, which grows in waters rich in alkali carbonates that yield most of the carbon dioxide for photosynthesis. Its protein content is quite high (up to 65%). This alga is present in lake Ciad, Africa, and in

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salty lakes of Mexico, where it has represented in remote ti mes and still partly represents today the main food through the preparation of pies for those poor populations. Studies on the cultivation of such algae in artificial water basins rich in alkali carbonates are being carried out in Italy in warm months at the Autotrophic Center-C.N.R., University of of Florence (prof. G.Florenzano)1 Other microalgae used are Chlorellae. 3.3. MACROALGAE FOR ANIMAL AND HUMAN FEEDING —Particular macroalgae are used for animal and even human feeding. These studies in various countries are still in progress, especially as far as ease of digestion and salt content of algal biomass from sea water are concerned. The ease of digestion is favoured by the almost total absence of lignin. As for salt content, the use of algae for goat feeding appears promising. Macroalgae are food for fish (e.g. herbivorous carp). Lichens are the only wintertime food for arctic animals (reindeer). The use of macroalgae in natural basins as food always entails the risk of the presence of poisonous pollutants (heavy metals) of industrial, farming or urban origin, so that sanitary control of the material is needed. 4. CHEMICALS FROM ALGAL SYSTEMS 4.1 PROTEINS, POLYPEPTIDES AND AMINOACIDS FROM MICROALGAE —Spirulina, al reasy mentioned under 3.2, is a source of proteic material that yields proteins, polypeptides and aminoacids. 4.2. FOSSIL MATERIALS FROM MICROALGAE —The formation in remote ages of huge deposits of dead mono- and polycellular microalgae forming the phytoplahkton together with dead zooplankton, trapped in layers of inorganic se-diments, has provided the biomass which originated oil and natural gas by “naphthogenesis”. The dead monocellular microalgae diatomeae, present in all the planet’s waters and having a siliceous membrane forming a rigid shell, upon sedimen tation on the depth, have built up siliceous deposits, named “fossil flour” which have evolved into a very porous, light, pale yellow sedimentary rock which has several industrial applications. As a dust it is used as a light abrasive; it is employed in the manufacturing of dynamite by soaking with the explosive liquid nitroglycerine in order to decrease mechanical sensiti vity to shock explosion. It is also used in the manufacture of refractory brick. Another material akin to fossil flour is tripoli, made up by cell walls of diatomeae and radiolaria. Owing obviously to their long genesis, these materials are all classified as nonrenewable.

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4.3. CHEMICALS FROM ALGAE —Macroalgae, on account of their ability to absorb many water-dissolved materials, will extract some chemical elements, often in a highly selective fashion. An industrial exploitation is represen ted by the extraction of iodine from sea water by some macroalgae,the ashes of which, commercially named “kelp” or “varec” contain potassium iodide from which iodine is extracted chemically. Various metal elements in waters are trapped onto algae. In general, howe ver, their concentration in algal biomass is only scanty (at ppm level) and cannot exploited for industrial purposes. In contrast, noteworthy is the use of algae in purifyring processes involving polluted waters. 4.4. MUCILAGE CHEMICALS FROM MACROALGAE —Some sea macroalgae are used to produce agar-agar. In Ireland gelidium is employed, whereas gracilaria is used in Italy. In particular, the Venice lagoon yields large amounts of gracilaria. Agar-agar is a polymer of galactose, soluble in warm water, which is used to prepare gels, drug excipients, laxatives and bacterial culture me dia. Furcellaran, akin to agar-agar, is extracted from algae in Denmark. Chondrus crispus, which grows along the Northern Atlantic coast lines, yields carragenine, a polysaccharid produced in France and Britain, which is used in food industry. Laminaria, ascophyllum and fucaloides of Ireland and Britain (the former two also in France) yield alginates, salts of alginic acid, which are used in food, paper, fiber, dye, ink, cosmetic, and paint industry. 4.5. CHEMICALS FOR DYE INDUSTRY FROM MACROALGAE —Purple and carmine are extracted from the lichen rochilla tintoria. 4.6. CHEMICALS FOR PERFUME INDUSTRY FROM MACROALGAE —Everna furfuracea, ramalina calicaris and fulmonaria sticta yield oaken musk, which is used in perfumery as essence or as a fixer for other perfumes. 4.7. LABORATORY CHEMICALS FROM MACROALGAE —The lichens lecanora and variolaria yield litmus, a pH indicator. 4.8. CHEMICALS FOR AGRICULTURE FROM MACROALGAE —Macroalgae can be used as farming soil fertilizers. Furthermore, wet algae, mixed with biological sludges from water purifica tion or algae biogas production, and subjected to aerobic fermentation yield humus of which farming soils are lacking.

SESSION III IMPLEMENTATION L.E.B.E.N.—Large European Bioenergy Project, Abruzzo, Italy— G.Grassi, U.Miranda, C.Baldelli and F.Gheri The Production and Use of Fuel Alcohol in Zimbabwe— C.M.Wenman Canada’s Energy from the Forest Programme— R.P.Overend Integrated Food-Energy Production Systems— E.L.La Rovere The Use of Wastes as a Source of Energy in the U.K.— R.Price The Southern U.S.Biomass Energy Programs with Emphasis on Florida— W.H.Smith Biomass Energy Utilisation and its Technologies in China Rural Areas— W.Wu

L.E.B.E.N.—LARGE EUROPEAN BIOENERGY PROJECT/ABRUZZO, ITALY G.Grassi, U.Miranda, Commission of the European Communities (DG’s XII and I respectively), Brussels, Belgium C.Baldelli, Cassa per il Mezzogiorno, Roma, Italy F.Gheri, Regione Abruzzo, Pescara, Italy SUMMARY Present concepts of optimized bio-energy schemes represent a new field of integrated activities which open perspectives of such large dimensions, not only for Europe, which justify the intensive world-wide R&D and demonstration programmes actually being carried out. Large bio-energy schemes can give a substantial contribution to general regional development, especially for the more disadvantaged internal agricultural districts, through the upgrading of properly converted non-exploited resources (residues, wastes, biomass from marginal land and eventual agricultural surpluses). The multi-disciplinary aspect of this type of project will give vast opportunities for new jobs in rural communities. The LEBEN project, already in the preliminary phase of implementation in the Abruzzo Region of Italy, will be the first large European Bio-energy project. This project is based on the exploitation of about 450.000 t/year of biomass. It will utilize a diversified harvesting, collection and chipping system, a network of dispersed pyrolytic conversion units and an ethanol factory (150–200 t/day). The pyrolytic products will be fired in the Avezzano power station (27MWe). Waste heat will be recovered for alcohol distillation and for heating greenhouses (20ha). A laboratory unit for the “in-vitro” fast reproduction of plants will supply greenhouses with the plants needed for the regional energy crop programme and for other particular forestation programmes. An educational, training and maintenance centre for about 200 young people per year will be operational in 1986. A second sector of activity will be production of electricity by the construction of 12 small hydro-electric power stations for a total installed power of 22MW. A third sector of activity will be the exploitation of a group of agroindustries for processing local products.

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The LEBEN project will be technically supervized jointly by the Commission of the European Communities (DG XII and DG XVII in cooperation with DG V, DG XI and DG XVI), the Italian Authority for the development of South Italy (CASMEZ), the Abruzzo Regional Authority, and the Organization for the agricultural development of the Abruzzo Region (E.R.S.A.). It is considered of great strategic importance for demonstrating, for Europe and other countries in a similar situation: – the economic feasibility of energy-oriented innovative and complete biomass schemes; – the high socio-economic impact and benefit resulting from the wide penetration of pyrolysis conversion processes and alcohol conversion processes, eventually in combination with the new concept of energy crops. The total budget foreseen for the implementation of the LEBEN project is approximately 230 million ECU; 120 million ECU* (52% of the total) is needed for the bio-energy activities. Completion is scheduled for 5 years’ time.

INTRODUCTION At the Commission of the European Communities, after eight years of exploratory Research and Development activities (as significant as the pilot- projects and the demonstration programmes of DG XII and DG XVII), it is considered that the modest technical risk, still present in some areas of biomass production, harvesting and conversion, now allows for the implementation of large bio-energy (or “agro-energy”) schemes, which are absolutely necessary to demonstrate the full potential interest of exploiting the large amount of biomass available in many countries (85 million t.o.e./year of net energy for the Community in the year 2000). Only in this way, we shall be able to prove the validity of the strategic European biomass issues, which are outlined below : 1. technical and economical viability for the massive, fast and rapid thermochemical conversion of agricultural and forestry wastes into fuel products (for local heat and electricity production), especially for the inland districts of the Mediterranean region of the Community—about 20 million t/year in the short-term, about 40 million t/year in the medium term. 2. Technical viability and social interest for alcohol production as ingredients for motor fuels from unwanted agricultural surpluses available in all regions of the Community (cereals: 30 million ton/year—sugar: 4 million t/y—wine: 3 million t/y in 1984), to reverse the past 10 year situation. 3. technical viability and economic viability (at a later stage) for ethanol production from energy crops (100 million t/year of biomass could be available in the European Community from short rotation forestry, catch crops… in the year 2000) for car fuel application.

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SCOPE OF THE LEBEN PROJECT/ABRUZZO The LEBEN—Project is considered particularly important for the verification of the above-mentioned strategic option n° 1. The Abruzzo Region is a part of the “Mezzogiorno” of Italy where the inbalance between energy (electricity) production and consumption is * 1 ECU—1.382 Lire (March 1985)

large (40% in the year 1990) and the specific energy consumption in agriculture (500Kg O.E./Ha) is lower than the Italian average value. Therefore, if a large amount of thermal and electrical power, produced at a low cost and using unused resources, can be offered to the agro-forestry sector, a strong contribution to the intensity and quality of the regional development will rise through the increase of the technological contents of all activities (energy production, more sophisticated energy-intensive agricultural and agroindustrial activities, services). In this respect, the LEBEN, which is an integrated project, constitutes the basic instrument to promote the general development of the more disadvantaged inland districts of the Abruzzo Region and an important step towards the accomplishment of its energy self-sufficiency in agriculture (this is another point of great strategic importance in the long term). The multi-dimensional aspects of this integrated agro-energy project (biomass production, collection, pre-treatment, conversion and utilization) will open vast job opportunities to a wide range of specialists (agronomists, foresters, engineers, technologists, consultants, administrators, policy-makers, scientists, teachers…). OBJECTIVES OF THE LEBEN PROJECT/ABRUZZO The main objectives of the LEBEN project are the following: – cheap production of pyrolytic fuel for thermal power application and of electricity in the Avezzano power station and by hydro-electric power stations; – the creation, in rural communities of many new and qualified jobs (for biomass production, collection and conversion alone); – to verify the practical validity of the modular concept for conversion units as well as for large agro-energy schemes, thus lessening the risks which would be associated with a large scale and new technology.

DESCRIPTION OF THE LEBEN PROJECT We give below a very short presentation of the content of this complex project. The main sectors are the following: 1. Bio-energy sector, which is based on: a) biomass resources for a total permanent amount of 450.000 t/year;

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285.000t/year derived* from 70.000ha of “Bosco-ceduo”, 130.000t/year from agricultural residues (vineyards, olive and fruit trees… −70.000ha) and, at a later stage, at least 120.000t/y derived from energy crops (for short rotation forestry in marginal land, 105.000ha are available). * At present the total amount available is 3.500.000 ton, of which 1.800.000 ton for energy utilisation and which could be recovered in a 15 years’ period. The actual productivity is about 2.34t/ha.y.

Furthermore, an amount of about 10.000.000t/year of sugar-beet will be available in the surrounding area of the Avezzano power station (production cost—1984–120 ECU/ton; market value—185 ECU/ton) b) A diversified biomass harvesting-collection-chipping system: Up to now only preliminary tests on several harvesting machines have been carried out. The harvesting technology and methodology is currently under examination. c) A network (20–50) of dispersed pyrolytic conversion units for the thermochemical conversion of biomass into fuel. Such units will be of a “fluidized-bed” type and of a modular design, showing enough flexibility to match their conversion capacity to the biomass accumulation in different sites. Their energy-conversion efficiency is about 80%. The average fuel production (from 1 ton of dry biomass) is the following: – gases:

300kg (heating power 900Kcal/kg); part of the gas will be supplied to a 70KWe motor generator and to a biomass drying unit – charcoal: 250kg (heating power 7000Kcal/kg) – bio-oil: 200kg (heating power 5000Kcal/kg)

d) A 27 MWe power station. The existing (3 sections) oil-operated Avezzano power station will be modified for an optimum utilisation of pyrolytic products. Two solutions are now under study: – installation of charcoal/bio-oil gasifiers (nr. 3) – direct firing in the boilers of a “bio-oil/charcoal powder/water/fuel-emulsion”. The waste-heat from the power station will be recovered: – to supply heat to the “green-house” system; – to supply heat to the distillation of alcohol; e) A unit for the preparation of the emulsion to be fired into the boilers, should this approach be adopted; f) A system of “green-houses” (for a total covered area of 20 ha) situated near to the power station for the production of early fruits and vegetables and the temporary planting (10–12 months) of fruit and forestry trees to be transplanted or to be exported. g) A laboratory for “in-vitro” fast reproduction of plants having a capacity of 8–10 million plants/year.

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h) Ethanol factory (total capacity: 40.000–50.000t (eth.)/year) will replace an existing sugar factory. A surrounding area of 20.000ha will supply the raw material (sugarbeet, sorghum..). The ethanol will eventually be utilized as “octane-booster” in unleaded-gasoline for motors. i) an educational and training centre (S=8.000m2) for a total maximum capacity of 200 young people and open to other Italian regions, other Member States of the EC and also to developing countries. Main subjects of training will be: the production, harvesting, collection and storage of biomass, pre-treatment and conversion technologies, utilisation of conversion products. j) a maintenance centre to insure correct and regular operation of all sub-systems of this very complex and diversified project. 2. ELECTRICITY PRODUCTION SECTOR (by hydraulic power stations). A total number of 12 stations are foreseen for a total electric power of 22 MWe and an electricity production of 107 million KWh/year. 3. AGRO-INDUSTRIES SECTOR A group of 8 agro-industries for processing several types of agricultural products grown in the Abruzzo Region. These processes require large amounts of thermal power and electricity (processing, drying, liophilisation, cold storage, freezing…)

TIME SCHEDULE OF THE LEBEN-PROJECT/ABRUZZO Completion is scheduled within 5 years, starting June 1985 as shown here below: 1985 1986 1987 1988 1989 bio-energy sector electro-hydraulic sector agro-industries sector

Activities already under way: – General design and special assessment studies on the potential of biomass potential harvesting and conversion technologies, elaboration of a socio-economical model on computer – Intensive testing of the pyrolytic process (pilot-plant in operation since 1983) – Group of conversion units under construction – Preliminary experimental tests by forest harvesting machines.

ECONOMIC EVALUATION Here below we present the main economical data:

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A. Investments MECU (forest infrastructures (roads): (Pyrolysis Conversion Units: (Avezzano Power Station (modifi (cation): (ethanol factory: Bio-energy sector (Green-houses+infrastructures: (Laboratory for “in-vitro” re (production of plants): (Centers for training+mainte (nance+services: partial total Hydro-electric sector: Agro-industries sector: Divers TOTAL:

9,2 28,2 8,3 21,7 38,5 6,5 6,8 119,2 24,0 70,5 13,3 227,0

B. Energy production cost Preliminary assessments based on these costs give the following figures: – Fuel cost (average) for thermal application: 140 ECU/T.o.e. – Electricity cost; – by pyrolytic fuels 60Li/KWh – hydro-electric: 30–50Ll/KWh

C. Pay-back period for investments Limiting ourselves to the bio-energy sector and in particular to the forestry biomass harvesting, transportation, pre-treatment and pyrolytic conversion, the recovery-time of investment seems to be around:

t=4 years

SOCIAL BENEFITS The LEBEN Project/Abruzzo is estimated to be capable of creating many new job opportunities. A preliminary evaluation gives the following figures: – bio-energy sector: 1.500 new jobs – hydro-electric sector: 50 ″ ″ – Avezzano power station: 10–20 ″ ″ – Agro-industries sector: 2.100 ″ ″ TOTAL: 3.660 new jobs

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INTERNATIONAL COOPERATION The results of the LEBEN project and the experience drawn from it are of high interest for cooperation with third countries, namely developing countries. The LEBEN project applies an integrated approach to agroenergy on a regional basis and, for this reason, is well suited for many developing countries whose economy is based on agriculture. It is also important to note that this project has an important social impact on the population of such countries. The development of local energy resources in an integrated scheme, facilitates the social life of the country and reduces the need for urbanisation. Cooperation with developing countries can be foreseen at different levels, starting with a transfer of expertise to feasibility studies or operational projects. Training programmes can also be set up for personnel coming from third countries, as well as the participation of specialists in the programme preparation and/or in its implementation. As far as financial aspects are concerned a large spectrum of possibilities exists depending on the type of cooperation under which the project is to be implemented. Conclusions To conclude, the implementation of large agro-energy schemes will demonstrate: – the possibility for agricultural and forestry activities to enter the energy market which has, for oil importing countries, the attraction of a non-saturable market. The LEBEN project in particular, by the exploitation of a significant amount of the biomass potential of the Abruzzo Region (about 450.000 t/year of agricultural and forestry residues), will demonstrate: – the possibility (option 1) of a local massive and cheap production of thermal and electrical energy; – the consequent specific and high socio-economic benefit. The total expected number of new jobs is about 3.600; – the possibility, by the adoption of the less-sophisticated pyrolytic conversion process to recover (with a pay-back time of 4 years), the capital investment required and the operating costs (interest rates, manpower, biomass, services…) – the importance to dispose, locally, of a technological industrial infrastructure (based mainly on small-medium size organizations) which because of the inherent flexibility leads to a more economical and efficient exploitation of regional resources. The operational experience obtained from the implementation of large agro-energy schemes such as the LEBEN project/Abruzzo, can be of great and valuable importance for the penetration of this concept into the general development strategy and some form of cooperation for emerging and developing countries.

THE PRODUCTION AND USE OF FUEL ALCOHOL IN ZIMBABWE. C.M.WENMAN TECHNICAL DIRECTOR, TRIANGLE LIMITED, TRIANGLE, ZIMBABWE. SUMMARY. A plant to produce 40 million ℓ of absolute alcohol per annum was built in 1980 in Triangle, Zimbabwe, adjacent to an existing Sugar Mill. This plant has run successfully since that time and operating experiences to date are discussed. The rationale for building the plant and specific difficulties encountered during this phase of the project are probably relevant to many developing nations today. All the alcohol produced is blended with petrol and distributed throughout Zimbabwe. This 12% alcohol/petrol blend is the only fuel available in the country for spark-ignited engines. Minor difficulties experienced during introduction of this fuel are discussed. In 1978 sugar production in Zimbabwe was 309 500 tons, of which 108 500 tons was consumed within the country, the balance being exported. At that time, the export price of sugar was approximately US.$100. per ton whilst transport costs of US.$20. per ton further reduced the amount received by the producers. Two producers of roughly equal size accounted for the total sugar production in Zimbabwe. With a production cost of some US.$130. per ton, my Company Triangle Limited, decided to pursue the possibility of converting part of its sugar exports into ethanol. From a national point of view, local fuel production would reduce the amount of imported hydrocarbon fuel, thus reducing foreign currency expenditure and high transport costs to our land-locked country. Strategically, the production of a liquid fuel within the country made very good sense, particularly at that time when a war situation existed in Zimbabwe prior to the country gaining its independence. Against this background, Triangle Limited’s proposal to produce ethanol and market it solely through the Government’s Oil Procurement Company made good economic, political and strategic sense and readily gained the approval of Government Authorities for its implementation. Notwithstanding the attractive nature of the project to the national economy, a very strict limit was put on the amount of foreign currency allocated to the project. This is a situation not uncommon in most Third World countries today. Having received Government and Company Board approval to proceed, a number of technical decisions had to be made, the most critical of which was the choice of plant to be installed. The criteria which were set in making this choice were as follows: – Minimal foreign currency content. The plant should be constructed as much as possible within the country with a minimum imported content. – In a developing country it was necessary to design and build a plant appropriate to the abilities of the people who were to run it. Therefore a large amount of automatic

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control and sophisticated equipment had to be discarded in favour of simpler manual processes. – The conversion yield on the plant should be of an acceptably high level to ensure that in sacrificing sugar production for ethanol the Company was not making an economically retrogressive step. This was particularly important as it must be emphasised that the project was conceived and implemented entirely by private enterprise without Government assistance or subsidies. To meet the above criteria numerous processes were considered and the decision made to build a straight-forward batch fermentation plant to produce dehydrated alcohol. This plant was designed by Gebr. Herrmann, now part of the Buchauwolf Group. The agreement reached with the designers was that the design only would be bought from them and that all construction would be carried out in Zimbabwe with the proviso that the critical aspect of building the distillation columns would be overseen in the initial stages by a Construction Supervisor sent out by the designers, and once the building was completed, pre-commissioning checks and ultimately commissioning would be carried out by a team sent out from Germany. To undertake the construction, a Project Team was set up in Triangle to translate the specifications received from the designers into equipment available within Zimbabwe, or, where necessary, to be imported from outside the country. In this category such items as plate heat exchangers, air blower and certain dairy-standard pumps had to be imported, as well as basic essential instrumentation. Material in the form of stainless steel plate, piping and certain specialised valves were also imported for fabrication and assembly within the country. The major aspect of fabrication which was undertaken was the construction of the distillation columns. These measure some 2 metres in diameter and 30 metres in height with perforated trays, up to fifty five in number, supported internally. The levelness and symmetry of these distillation trays was the most critical aspect of their construction which had to be monitored and controlled continuously during fabrication. To undertake this, a Local Inspection Authority was appointed with standards being set by the German Construction Supervisor. Construction of the buildings and structures and assembly of all components had to be done to a very high standard, and to achieve this, semi-skilled local welders were put through a short training course in a school specifically set up to ensure that their work met an acceptable standard. Periodically during construction, spot checks were made on welds and welders not maintaining an acceptable standard lost their Quality Bonus and had to undergo re-training before being allowed back on the construction site. In this way a very high standard was maintained and on commissioning, virtually no weld faults were detected. Construction of the plant started in March 1978 and it was commissioned in May 1980. The final cost of the total project, including integration with the sugar mill, was some US.$6 million (at the rate of exchange applicable at that time). The plant was positioned as close as was practical to the existing sugar mill in order to take advantage of facilities already existing in the mill. The feedstock to be used— although potentially crystal sugar—was to be bled as liquid from the sugar mill at an appropriate point. This point could vary from, immediately after the raw juice was expressed from the sugar cane and prior to any clarification or evaporation had taken

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place, to as far down the sugar manufacturing process as “B” molasses. It is normal practice to further exhaust the molasses in a third or “C” process but the decision was taken to dispense with this stage. The reasons for this were twofold: – Additional energy was required to extract this final amount of sugar which was unnecessary. – In laboratory tests it had been determined that molasses produced after three boilings was considerably less fermentable than after one or two boilings. Steam savings achieved by cutting out the third boiling stage and by taking juice directly from the sugar mill without evaporating it, equalled the amount of steam required for distillation. Thus it was unnecessary to build additional boilers and a low pressure steam supply was taken from the existing Power Station directly to the distillery. The operation and management of the distillery was integrated into the duties of the existing sugar mill staff, which could be achieved as less attention was required in the sugar mill due to the decreased emphasis on molasses exhaustion. Maintenance staff were similarly redeployed and no increase in staff was required. The plant is designed to produce 120 000 ℓ per day. With a 96% time efficiency and operating for fifty weeks of the year it can produce 40 million ℓ per year. During the first year of operation, the plant ran for some nine months, and since that time annual production has not quite reached 40 million ℓ, although it is hoped to achieve this figure by the end of the current year ending March 31, 1985. PERFORMANCE OVER PAST FIVE YEARS. 1984 1983 1982 1981 1980 Ethanol produced.. (million ℓ) *40,000 36,704 38,377 38,282 30,186 Tons sucrose from: Molasses *77 786 69 154 54 850 49 124 32 807 Juice 799 3 637 16 987 21 843 20 854 TOTAL: *78 585 72 791 71 837 70 967 53 661 Yield * 509 504 534 539 562 Mol % Total 99% 95% 76% 69% 61% * Estimated

During the last two years, expanded milling capacity has been available, and as a result, far less sugar juice has been consumed as more molasses is now available from the Factory. This has resulted in a slightly less efficient utilisation of steam, as water has to be evaporated from the sugar juice during the production of molasses which is then rediluted prior to fermentation. In reviewing the past five seasons’ performances it can be seen that the conversion yield of sugar to ethanol has steadily decreased. Coincidentally the proportion of molasses in feedstock has increased and this is one of the main reasons why the yield has dropped off. In analysing for total sugars, the traditional method used in a sugar factory is the Lane and Eynon titration method which in fact analyses for total reducing substances, not sugars. This over-estimates sugars and increasing errors are therefore introduced with increased molasses usage. To overcome this, we will introduce from the forthcoming year

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chromatographic analyses for sugars which will give a much more accurate measure of the total sugars being used. In an attempt to further improve yield, we have now purchased a yeast centrifuge which it is hoped will enable us to dispense with the pre-fermentation stage by recycling yeast directly from a fermented batch back to a newly prepared one. In this way all sugars will be used in the production of ethanol with a minimal amount being used to produce yeast. Maintenance problems so far have been few. The most serious one related to incorrect specification of circulating pumps on the main fermentation tanks which resulted in their premature failure. These have now been correctly sized and normal life expectancy is being achieved. To save foreign currency during initial construction, the main fermentation tanks were made from 6 mm mild steel plate and severe corrosion is now being detected on the heat-affected zones at all the welds. These are being re-welded and the interior of the tanks protected with epoxy paint which appears to have stood up well during a oneyear test programme. From the operating point of view, one of the major long-term problems is the disposal of stillage. The initial plan was for this to be diluted 40:1 with irrigation water and used to irrigate some 1 100 ha of cane fields. This has proved successful in that a large saving in fertiliser has been achieved. However, the stage is now being reached where there is an over-application of minerals to these fields and the stillage is now being applied to a further 1 200 ha to increase the dilution factor. Although the fertiliser value of the stillage more than pays for the cost of application and maintenance of equipment, the long-term effect on the fields has yet to be established. Furthermore, inevitably, mis-application of the irrigation water results in diluted stillage running directly into water courses causing pollution of the environment. It is therefore felt necessary to investigate and pursue other disposal methods in the longer term. In this regard, the best solution with minimal operating cost and maximum recovery, appears to be anaerobic digestion, but this is very costly. Certainly cheaper, and possibly more applicable in a country where land is not at a premium, would be lagooning or aerobic digestion of the stillage. However, this is not very efficient in reducing pollution levels and no energy recovery is possible. Concentration and subsequent incineration has also been considered, but at best this alternative is only energy self-sufficient and would again be costly in foreign currency. All the alcohol produced at Triangle is used as a motor fuel by blending with petrol. As Zimbabwe has no natural oil deposits, all its petrol and diesel fuel is brought into the country in a refined form and blending takes place at numerous centres around the country. The main reason for having various blending points is to have separate storage of petrol and ethanol until they are loaded into road tankers for distribution to retail outlets. By keeping these products separate, fire fighting procedures can be simplified as different foams and fire fighting techniques are required for the two products. The overall blend of alcohol in petrol now stands at 12% having been reduced from an initial blend of 15% as a result of increased fuel consumption and static production facilities. During the initial stages of the introduction of the blend fuel, numerous vehicle faults were attributed to it, ranging from broken fan belts to intoxicated drivers !! However, on

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investigation there appeared to be only two faults which could in fact be substantiated. These were: – The solubility of certain plastic components—particularly in one brand of car—in the blended fuel. The solvent properties of the alcohol also affected glass fibre fuel tanks such as were fitted to some motor boats. These problems soon manifested themselves and were remedied by replacing the affected item by a non-soluble one. – The effect of alcohol on certain acrylic enamels which were mainly used during the repair of motor vehicles. Many cars throughout the country could be seen with strips of paint taken off the bodywork from the petrol filler to the ground. This problem has been minimised by liaison with fuel retailers who have instructed their Forecourt Attendants to dilute with water any spill at the fuel filler. Liaison with automotive paint suppliers in the country has also resulted in the withdrawal of alcohol-soluble paints from the market so that the problem should disappear in time. Milling capacity has been increased in the past two years and as a result of this, sufficient feedstock is available to double the capacity of the distillery. By increasing the capacity, proportionately less molasses can be used and advantage can once more be taken of the energy savings inherent in sending cane juice directly to fermentation. It is anticipated that by utilising yeast recycling no major increase would be required to the size of the fermentation plant to supply fermented beer to a second distillery. Even if production were doubled to 80 million ℓ per year, this would represent, at today’s petrol consumption within the country, a blend of some 25%. The option, however, remains to introduce vehicles powered by pure alcohol engines so that increased production up to twice our present capacity could easily be accommodated. Talks are currently underway with Government to finalise arrangements for the building of a second plant and it is expected that this will become a reality in the not too distant future.

CANADA’S ENERGY FROM THE FOREST PROGRAM Ralph P.OVEREND National Research Council of Canada Summery In 1978 Canada implemented 2 programs to encourage the development of bioenergy as a reliable and economic substitute for fossil fuels. The FIRE program, a capital incentive program, will have stimulated almost 370 PJ/a of additional biomass fueled capacity when all projects are completed. The ENFOR program, the subject of this paper, has played a significant role in the provision of technical support for commercial and developmental work in forest energy applications. The ENFOR program has established a forest biomass inventory, and developed new harvesting machines to provide increasing quantities of biomass for bioenergy, while at the same time contributing to improved forest regeneration practice. Other achievements are the development of a large scale simulation of forest nutrient dynamics, and improvements in the mechanization of Short Rotation Intensive Culture (SRIC). On the conversion side of the ENFOR program, contributions to materials handling and combustion technology have been made. MJV gasification has been scaled up to 10 t/h throughout in a pilot installation and direct liquefaction has been taken to the PDU scale. A major project completed under ENFOR conversion was a technoeconomic assessment of commercial and near term technologies as well as of the more futuristic proposals. This will serve as a basis for the implementation of bioenergy options through to the year 2000 when it is expected that the contribution will be around 1000 PJ as against today’s 545 PJ (1978, 380 PJ).

1. INTRODUCTION Following the first of the 1970’s oil shocks a review of the Canadian terrestrial biomass energy potential was undertaken in order to establish the policy actions necessary to access this source of renewable energy (1). Due to the northern and continental nature of Canada, almost 50% of the land mass is terrain which is relatively non- productive. An additional 30% is able to support forestry and 6–8% supports agriculture; the balance is freshwater and urban areas. The preliminary study identified a major energy potential in the use of mill and process residues from the forest industries, with the possible export of fuels from that sector in the form of solid, liquid and gaseous fuels.

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To encourage the development of this potential energy source, the Federal government instituted two programs during 1978: FIRE and ENFOR. The former is a capital investment assistance program to bring about the replacement of fossil fuels in the forest industry sector; the latter was an R&D program to secure the knowledge necessary to facilitate a marked increase in the contribution of forest biomass to Canada’s energy supply The FIRE program has been described previously and a detailed analysis of its accomplishments was recently given by Juneja (2). The present paper focusses on the activities and results of work undertaken during the course of the 6-year, 29 million dollar ENFOR program. 1.1 ENFOR Program Structure and Administration From the beginning the program was structured around two sub-programs: Biomass Production (which dealt with matters relating to the raw material supply), and Biomass Conversion (which was concerned with the transformation of forest biomass into energy, prepared fuels, or energy intensive chemicals). Objectives and priorities for each of the sub-programs were developed annually by appropriately structured committees. These same committees followed the course of each year’s research and monitored the progress of existing projects, as well as evaluating the proposals received against an annual solicitation and recommending to the Minister those that should be funded. The major part of the program was carried out under the terms of the Canadian government’s “make or buy” policy of the 1970’s and as a result, most of the research was contracted outside of the government research laboratories. The production committee was composed of representatives from the headquarters and regional laboratories of the Canadian Forestry Service (CFS), whereas the conversion committee was drawn from other government research laboratories, the forest products laboratories of the CFS and an equal number of forest industry representatives. During the lifetime of the program the CFS forest products laboratories were “privatised” and became the FORINTEK Canada Corporation. As before, they continued to give appreciable technical direction to the program by both participating in projects and in the provision of technical liason officers or monitors of contract activity. In the case of the government scientist assigned to this task, his/her title was that of scientific authority. During the first 5 years of the program the administration of the special energy funds for ENFOR was entirely under the jurisdiction of the CFS. Following the second oil shock there was an expansion of the federal research programs under the National Energy Program (NEP) of 1980. This expansion resulted in the transfer of responsibility for conversion programs to the Department of Energy, Mines and Resources, leaving the responsiblity for the forestry production aspects with the CFS. In 1984 the original ENFOR program ended and the continuing CFS production program has retained the name for that aspect only, the conversion program continues under the auspices of EM&R under the title of Biomass Development Program (BDP). The objectives of each program were as follows:

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PRODUCTION a. Inventory The broad objective was to define the quantity, form and location of forest biomass in Canada. This centered on methods of deriving biomass data from the existing provincial forest inventory, which existed only in the form of the volume of the merchantable bole. This included: the development of new techniques for estimating biomass quantities; and providing data on the proportions of various tree components (eg. stump, bole, branches) to the total biomass. b. Forest Management: Growth and Yield The general objective was to determine the biomass growth potential of forest land under various management prescriptions. Typical concerns were biomass productivity and its estimation, especially from conventional growth and yield data. This category also included investigating the production of biomass under different regimes along with species selection and genetic improvement for maximum biomass production. c. Forest Management: Silviculture and Harvesting This program aimed at determining the technical and economic requirements of growing, harvesting and transporting biomass. Topics studied included: the intensive culture of energy plantations, and the development of integrated systems for harvesting, on-site processing and transporting of biomass. d. Impacts Broadly, the objective of this program was to assess the impact of forest biomass utilisation on economic, social and ecological systems. Typical projects included: biomass nutrient budgets under different management regimes; effects of intensive operations on mammal and avian populations; effects on the forest industries themselves and on the human populations in the forest regions. CONVERSION a. Feedstock Preparation To minimise the problems of raw material handling and maximise the efficiency of various conversion proceses, projects were promoted in the following areas: materials handling; moisture content reduction; comminution and agglomeration and storage. b. Prepared Fuels Conversion Technology This category of activity was the major component of the conversion program. The goal was the preparation of gaseous, liquid or solid fuels with enhanced heating value, cleanliness, storage and transportability qualities. Proposals to improve combustion systems were accepted also, though subject to criteria concerning economic and technical considerations, since it was considered to be basically a well established technology. The major technology areas considered were:

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Gasification: Low Joule systems Gas Cleaning for LJV LJV from wet feedstocks MJV or Syngas production Liquefaction: Direct Hydrogenation Catalyst Development Ethanol and other alcohols from wood Densification: Green wood to water resistant densified fuel

c. Industrial Chemicals Conversion Technology The major emphasis was on the conversion of forest biomass to energy intensive industrial chemicals which were either directly marketable commodities or intermediates for further processing. The topics included treatment of wood gas to convert it to a syngas of specified hydrogen: carbon monoxide ratios. Also included here was the fractionation of ligno-cellulosics and the subsequent processing of the hemicellulose, cellulose and lignin-derived fractions. 2. ENFOR PROGRAM RESULTS The appendix to this paper contains a serial list of ENFOR projects and reports for the period through to April 1984 which was the final period of the ENFOR program before it split into the two separate fractions. The list includes all of the projects funded in serial order. In some instances no report is available since the project served to furnish raw, unprocessed data for other work. Due to the fact that all project proposals were numbered serially and were not all supported, the number sequence is not complete. The missing numbers represent proposals that were not accepted either for monetary, technical or mandate reasons. The reports list does not include the activities engaged in under the Canadian participation in the Forestry Energy Agreement of the International Energy Agency, which was supported under the ENFOR program by the CFS. 2.1 ENFOR Production Program For the purpose of analysis the 14.5 M$, 142 individual contracted elements of the production program are grouped and analysed according to the 4 major activities shown in Table I below. In the space available it will only be possible to discuss some of the major findings and highlights of each of the areas of activity.

Table I. “Production program data for dollar and sub-program distribution.” Research Area Biomass Availability Harvesting Technology Environmental Impacts Short Rotation Intensive Culture TOTAL

% Dollars Spent % of all Projects 33 39 20 8 100

44 20 24 12 100

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2.1.1 Biomass Availability The major concern of this program was the total availability of the forest biomass for all purposes and the share that might be available for energy. Prior to the ENFOR program, the basis for such estimates was the inventory data for the merchantable species and the application of factors of poor reliability relating the merchantable volume to that of unmerchantable trees and the ratio of other tree components to the merchantable volume. A further consideration is the accessibility of forest stands; since the economic availability is a direct function of the access to roads and other transportation links. The information for the stated aim, “to determine the quantity, form and location of biomass in Canadian forests”, was obtained through the acquisition of data on the biomass of tree components and the development of biomass equations, in combination with the computer based system of national inventory which was developed in parallel by the Forestry Statistics and Systems Branch (FSSB) of the CFS. The FSSB had already prepared the national inventory “Canada’s Forest Inventory 1981” (3) under this system known as the Canadian Forest Resource Data System (CFRDS) which is used for the input, manipulation, summary and output of forestry biomass data. In CFRDS the forest lands are divided into 40,000 geographic cells. For each of these cells data bases on inventory, change data, biomass, access, geographic features and so forth are maintained. The total size of the data base is of the order of 150 Mbytes. In the 1981 inventory only the merchantable volume was available and it is the availablity of biomass equations that have enabled the the assembly of a biomass inventory. 2.1.1.1 Tree Biomass Equations The basis for the conversion of a volume inventory to a biomass inventory is the use of equations of the form: M=a+bD2H where M=oven dry mass kg D=tree diameter at breast height in cm H=tree height (m) and a, b=equation coefficients Such equations are derived for individual tree species, for geographical regions or provinces, and for tree or stand components. of the eight components, seven relate to components of merchantable trees; the last is the stand component and includes all the small trees that have no merchantable wood, ie. the sub-merchantable trees. In some regions (Alberta, Sasktachewan, Ontario and the territories), equations are either still unavailable or the inventory data is only available as a volume; in these instances the volume is converted mass and then factors derived from the equations are used to estimate the biomass. Inherently this introduces more error than the equation approach. Numerically the projects to determine the coefficients are the major part of the ENFOR production program. At the last estimate, data had been obtained for approximately 12,000 trees comprising all major species in Canada, by region and province.

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2.1.2 Biomass Availability Findings A brief summary of the findings (4) is set out below: The total forest biomass is 27 Gt. 79% of this is on productive forest lands. 62% has access through a nearby transportation corridor. 47% of the total is merchantable wood, ie., sawlogs or pulpwood. 33% is residue from merchantable trees, ie., branches, bark and foliage. 20% is small, sub-merchantable trees. 36% is in British Columbia with an average biomass of 159t/ha. 16% is in Ontario with an average biomass of 58t/ha 16% is in Quebec with an average biomass of 52t/ha 79% are coniferous species. 35% are spruce 18% are pine 10% are aspen/poplar The toal area of forest land is 449×106 ha and the productive area is 242×106 ha. The average forest biomass is 62t/ha, while on the productive land it is 90t/ha. After considerations of productivity and accessibility the sustainable yield of biomass for energy purposes has been estimated to be 54 Mt, a primary energy content in excess of 1 EJ. 2.1.3 Harvesting Technology The traditional harvesting system in use in Canada is the shortwood method in which only the merchantable stem is removed from the forest. Aproximately 47% of the total biomass is left in the woods and the sole energy component is the bark at 6%. Emerging systems are the tree length method and the full tree harvesting technology. With the tree length method the tree is sheared at the base, delimbed and then removed. As a result there is extra fibre and energy biomass with 36% left behind and 11% for energy exclusive of mill and process residues. The full tree method results in the total removal of branches and tops along with the merchantable bole. Only 20% is left behind with this method including the submerchantable trees. The bioenergy component is 27% on the same basis as before. Many of the biomass collection projects were designed around methods of logging residue recovery from the short wood technology. Development work was also undertaken with respect to the emerging technologies. 2.1.3.1 Bioenergy and the Shortwood Method The existing infrastructure of logging is based on the shortwood method. The bioenergy interest is in accessing logging residues, submerchantable trees and non-commercial trees on the site. Extensive studies were undertaken on the cost and performance of the existing machinery, such as skidders, in these applications. These studies ranged from: small scale measurements; the development of machinery simulation models; and a large scale demonstration project in Newfoundland that harvested in excess of 60 kt of noncommercial material as boiler fuel.

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Partly in the light of the existing studies, developments were undertaken for two machines. The first was a brush harvester for the harvesting of non-commercial species and/or thinning for energy, while the second, a machine for the collection of logging residues was developed around a comminution rotor known as the Recufor. Both concepts continue to be developed. The Recufor also evolved into a stationary version for the processing of full trees at the mill. 2.1.3.2 Full Tree Harvesting Full tree harvesting can take several variants: full tree transported to the mill site; full tree to a landing for processing into pulp lengths and the residues for chipping, or whole tree chipping. All of these were studied under the program. The transportation of full trees to the mill site virtually requires a private road system to accomodate the bulky oversize loads neccessary to obtain a reasonable weight of material on a truck. Processing at the landing appears to offer a commercial compromise in that public roads can be used for both products. The whole tree chipping concept still requires development for both the chipping unit to accommodate the full tree and of the separation of the chips if the fibre values are to be extracted. It appears that residue collection, non-commercial tree harvesting and full tree concepts all achieve two benefits: they yield energy products and at the same time they help prepare the harvest site for subsequent restocking. The sum of the two yields a net benefit and the use of these concepts seems to be assured. Since in most cases the bioenergy harvest is by a captive user, the mill site, there is the possibility of well integrated economic operations. 2.1.4 Environmental Impacts The impacts of bioenergy use on the forest can be on the flora, fauna and on the human populations. The main concern, however, has been the risk of damage to the biosphere itself in terms of erosion and nutrient depletion which has led to the development of a an ecosystem-based forest management model and simulation program called FORCYTE10. This model examines the the long term consequences of intensive forest management on site nutrient capital and biomass production, and allows the evaluation of the economic performance and energy efficiency of alternative management scenarios. A forest manager can model the consequences of variations in the rotation length, regeneration delays, species selection, initial stocking density, spacing, utilization level and final harvest. It is possible to run through 300 years of forest management in 10 minutes of simulator time. The model was initially developed around the nitrogen budget but now includes several nutrients. Presently there is on-going work to validate the model and to extend the number of biomes to which it can be applied. 2.1.5 Short Rotation Intensive Culture (SRIC) SRIC has as its basis the use of species that are high yielding in short rotations. Using hybrid poplar as an example it is possible to obtain yields of 60–70 t/ha in a rotation period of 10–12 years rather than the equivalent yield obtained in 80 years in the natural

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forest. Most studies have been undertaken on the Alnus, Populus and Salix genera. Much of this work has been shared with the International Energy Agency’s Forestry Energy Agreement under which there have been exchanges of experience in the management and harvest of short rotation energy plantations. Because of the rapid response of short rotation species this area has also served as the testing ground for studies of mycorrhiza and actinorhiza. The former symbiont assists in the uptake of nutrients and its study has led to improved strains and innoculation procedures, while the latter has been studied with a view to transfer the nitrogen fixing ability of Frankia associated with Alders to other species. 2.2 ENFOR Conversion Program Unlike the production program which by definition is restricted to the Canadian biome, the conversion program was more general in scope and had to recognise the existence of large programs outside of Canada under the auspices of the EEC and the USDOE. Thus, to some degree the program consisted of elements to enable Canadians to follow work going on elsewhere, a “Watching Brief ” so to speak, on areas in which Canada had a unique requirement or qualification. The proportion of the 77 contracts and of the total of 14.5M$ expenditures in the 5 key areas of the program are shown in Table II. There is no category for the impacts of this program since the environmental and social impacts tended to be evaluated as an integral part of each project.

Table II. “The Conversion program distribution of effort.” Research Area

Percent Dollars Spent Percent of all projects

Feedstock Preparation Direct Combustion Thermochemical Conversion Biotechnology Industrial Chemicals Techno-economic Assessment TOTAL

14 27 31 8 7 13 100

22 12 42 9 7 7 100

2.2.1 Feedstock Preparation Analysis of the conversion chain from receiving the feedstock through to the final product shows that an appreciable part of the investment is in the front end materials handling. Projects ranged from dewatering technology, the preparation of pelletized and water resistant prepared fuels, to the assessment of sensors available for the on-line determination of fuel moisture. A very succesful component of the effort was in studies of storage bin design and materials transfer facilities, this work originally at BC Research, one of Canada’s provincial research councils, is now being commercialised in the forest products industries. Though much work was done in this area, there still exists a need for the demonstration of the best technology to ensure its adoption.

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2.2.2 Direct Combustion The initial program direction assumed that this area would need little input since it was the basis of the already extensive bioenergy contribution. However, there were 2 areas in particular that required attention. The first was in the direct use of wood and residues to fire lime kilns in kraft pulp mills. Elsewhere most needs can be satisfied either by hot gases or more probably by steam generated in hog fuel and recovery boilers. The second area was in the efficiency and emmissions characteristics of units in use. A survey of mills showed that in the majority, the combustion of wood residues required inordinately large quantities of fossil fuels to enable load following and to compensate for the variations of the moisture content of the feedstock. A boiler test program was established to investigate this and to identify the means by which fossil fuel use could be minimised or eliminated. Three major avenues were followed in the substitution of oil in the lime kiln: the use of hot combustion gases; mixing wood chips with the lime mud; and finally the firing of clean pulverised fuels. The hot gas and the wood chip addition projects were targeted at the partial replacement of oil in the kiln. In both instances, the projects C-14 and C-123 were carried to a succesful conclusion. Commercial adoption is a function of local economics and with declining oil prices has not yet been implemented. The pulverised clean dry fuel option is more expensive, yet has been already adopted at one mill in Sweden. The boiler test program has examined the performance of 4 boilers with steam capacities in excess of 90 t/h (200,000 lb/h). Each of the boilers was considered to be of a type likely to be replicated in the future in Canada. The test procedure involved “tuning” the boiler and by operating at various loads the thermal and emmissions performance was evaluated. For each test it was established that with minor adjustments and modifications the boiler concerned could significantly reduce fossil fuel consumption while still meeting load and emmissions criteria. The results will be used to provide guidance to the industry and could result in appreciable reductions in the use of fossil fuels in existing installations while at the same time lead to a better design basis for new units. 2.2.3 Thermochemical Conversion By excluding combustion as such, this category covered pyrolysis, gasification and direct liquefaction of wood. Each area involved basic research, process development and in some instances the evaluation of near commercial units. The classification of projects was primarily in terms of the primary product: gas, char or a liquid. 2.2.3.1 Gasification The three end uses envisaged in Canada are: fuel gas for boilers and processes; gasifier/heat engine combinations for remote community and possibly grid-connected electricity generation; and the production of synthesis gas for the production of liquid fuels such as methanol. Projects were undertaken in all of these areas, partly through the importation of World War II derived European gasifiers and by the development of indigenous expertise in fluidised bed gasification.

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Electricity generation in a country with a large hydro and nuclear potential is not very profitable unless it is for in-plant use as in cogeneration or in remote community applications. Demonstration experiments showed that the labour requirement compared with the diesel competitor usually resulted in the gasifier option being unattractive. Current activity is targeted at a much larger scale than the 250kW of the average remote community with an eye to export sales of multi-MW units. Most development was applied to the fluidised bed option on the basis of prior experience in INCO (C-12) and ECO-Research (C-68). This and other fundamental work has lead to the construction of a prototype pressurized fluidised bed gasifier at St. Juste, Quebec under the aegis of a crown corporation. The BIOSYN project has a design rating of 10 t/h at 2MPa. to produce a medium joule value gas for reforming to syngas and possible conversion to methanol in a projected second phase of the project. 2.2.3.2 Liquefaction Though longer term in nature than the gasification syngas route to liquid fuels, there was extensive research and international collaboration on direct routes to liquids. In part this was because of hoped for process simplification and partly as a result of theoretical analysis that showed an efficiency advantage under conditions of lower severity than gasification. Projects ranged from pyrolysis C-28, C-223 under rapid heating conditions to vacuum pyrolysis C-33 and C-326, through to classical liquefaction similar in process conditions to coal hydrogenation and liquefaction. (C-44, C-48, C-69, C-118, C-256, C288, C-442). The Canadian effort in this field was a contribution to a major IEA project known as the IEA BLTF (Biomass Liquefaction Test Facility). This study in which the USA, Finland and Sweden, also participated was a complete survey of the performance of liquefaction processes and their technoeconomic potential. The final report of this project shows that while some processes could produce a cost competitive heavy fuel oil (HFO) replacement, most are too expensive when compared with current oil prices. The major finding was that the product composition is dominated by the chemistry of the individual wood components under the relatively low severity condition of the liquefaction processes. Thus the products are a complex mixture of oxygenated hydrocarbons and aromatics with little hope of easy conversion to either a conventional gasoline or diesel specification. There may still be a chemical products opportunity though this can only come from a more detailed understanding of the process chemistry. 2.2.3.3 Biotechnology As the program evolved it became evident that there were a number of low cost steam pretreatment processes available in Canada. Two of these, commercially known as IOTECH and STAKE, initially derived from the treatment of lignocellulosics to make the cellulose accessible to ruminant animals as an energy feed. Essentially the steam treatments lead to a variety of fractionation procedures giving 3 outputs, hemicellulose derived materials, cellulose and lignin. Once fractionated, the potential for biological conversion is clear and in particular processes leading to ethanol, mixed alcohols, solvents such as acetone, butanol, or to methane were attractive (C-181, C-187, C-222, C299, C-300, C-378). These areas remain as important objectives, with the central problem

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of finding markets for all three product streams. It is likely that one or more will have to find relatively high value in the chemicals and polymers or fibres markets for the fuel option to be viable. 2.2.3.4 Industrial Chemicals Only a few projects fell into this category, C-48 (in part), C-51, C-147, C-191, C-209, O288(in-part), C-295, C-378 (in-part). The challenge of course is the need for a chemical from a widespread resource such as wood to have a large market potential. Only a few wood fractionation plants producing ethanol would be required for the lignin co-product to satisfy a large portion of today’s adhesives market, assuming that this is feasible. Thus the applications have to have large scale intermediates such as ethylene or BTX from the ultra pyrolysis process or the application of the pulping process by-products products in tertiary oil recovery where the market is very large. 2.2.3.5 Techno-Economic Assessment At intervals during the ENFOR program, it was necessary to commission studies on the state of the art in various conversion technologies in order to either serve the client community such as saw mills looking for wood residue substitution of fossil fuels, C-111, C-95, C-185, or alternatively to serve program needs in the identification of R&D requirements. One of the final outputs of the ENFOR program was the assessment of all conversion technology based on international and Canadian experience up until 1984, (C258). This study composed of 9 volumes and two supplements, treated the biomass conversion system as being composed of a series of building blocks—unit processes. This methodology enables an informed reader to construct an overall system of such processes to evaluate the energy and mass balances and to derive an estimate of the cost. Though built up from the unit operations familiar to chemical engineers, the use of unit processes allows the system to be composed of many fewer operations than would be required for an ab-initio design. 3. CONCLUSIONS Between 1978 and 1983 the use of bioenergy in Canada increased from 370 PJ to 545 PJ or 4.9% and 7.2%, repectively, of the primary energy supply. This comparison with primary energy is unfair mainly because the role of biomass is at the secondary and tertiary levels of the economy. Residential heating by wood is an activity that displaces oil or gas at the tertiary level. Most bioenergy use is in fact at the secondary level in hog fueled boilers and recovery boilers. On that basis the share increases from 5.7% to 8.8%. The FIRE program has supported 177 projects at a cost to the Federal Government of 84 M$ to produce savings of 370 PJ when the projects are all completed. The ENFOR program has played a significant support role in this growth of bioenergy in the economy by providing a large pool of qualified people at the consultant and implementation level. The findings of the program will be applied over the next decade in terms of increased recovery of biomass from the forest and the application of conversion

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technologies today described as near term. Though very large scale application is heavily dependent on the energy supply and price future, use in the existing forest industries is not so price or market dependent since the residues required can be considered to be “captive” to that industry. A combination of silvicultural improvements and plant investments could lead to the industry becoming more self-sufficient in energy than today, with probably a further doubling of the quantity of bioenergy in the economy by the year 2000. The conversion of Canada’s forest inventory from a volume to a biomass basis has opened the door not only to increased use of bioenergy but also to new industries that can use the material on a non-specific property basis. The newly discovered “resource” is almost equivalent to today’s forest harvest and, in conjunction with fractionation processes and biotechnology, could lead to an increasing role of renewable resources in the economy. REFERENCES (1) LOVE, P. and OVEREND, R.P. (1978). Tree power: an assessment of the energy potential of forest biomass in Canada. Report ER-78–1, Energy, Mines and Resources, Ottawa. Canada. (2) JUNEGA, S.C, et al. (1985). Socio-economic and financial vaiability of bioenergy projects supported by Canada’s Forest Industry Renewable Energy Program. In Proceedings of “Energy from Biomas and Wastes IX”, Lake Buena Vista, Florida. Jan 28-Feb 1, 1985. (3) BONNOR, G.M. (1982). Canada’s forest inventory 1981. Forestry Statistics and Systems Branch. Canadian Forestry Service. Catalogue No. F0–41–10/1981E. (4) BONNOR, G.M. (1985). Inventory of forest biomass in Canada. Forestry Statistics and Systems Branch. Canadian Forestry Service.

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APPENDIX I PROJECT # P–1* P–2* P–4* P–6* P–8*

P–9* P–10

P–11* P–14 P–15* P–16*

P–19* P–20 P–21* P–22* P–23 P–25* P–28*

ENFOR PROJECTS—PRODUCTION SERIES TITLE CONTRACTOR/AUTHOR Energy from Newfoundland’s Forest Biomass Fuelwood Consumption in Newfoundland

R.S.van Nostrand (N-X-180) Northland Associates Ltd., St. John’s, Nfld. M.F.Ker (M-X-108)

Tree Biomass Equations for Ten Major Species in Cumberland County, N.S. Volume of Wood Residues for Energy Blais, McNeil, Lussier, Tremblay et Production at Parent, Quebec Associés, and Dendrotik Inc. Tabular Summary of Data from the Dr. J.P.Kimmins Literature on the Biogeochemistry of Temperate Forest Ecosystems Forest Utilization for Energy and the Role of Dr. A.Fortin Nitrogen Fixation: A Literature Review Intensive Culture of Green Ash and Japanese Ontario Ministry of Natural Resources Larch Plantations to Maximize Biomass Production Energy from Forest Biomass: Public J.D.Coates Awareness Program Direct Assessment of Forest Biomass with a GRW Resource Inventory Radar Ltd., Radar Altimeter Rescott, Ont. Complete Tree Utilization: An Analysis of Dr. Robert W.Weldwood the Literature (1970–78), Part I–IV Growth of Forests in Canada—Part 2: A A.Bickerstaff, W.L.Wallace and F.Evert Quantative Description of the Land Base and (PI-X-IF) the Mean Annual Increment Cost Estimates of Forest Biomass Delivered at the N.A.Wiksten and P.G.Prins Energy Conversion Plant Data Collection for Mature Softwood Biomass Horton Forestry Services Ltd., Conversion Factors Stouffville, Ont. Biomass Inventory of Tolerant Hardwoods in Algoma, J.B.Thomas Ontario Biomass Productivity of Young Aspen Stands in Western Ecological Services Western Canada Edmonton, Alberta Prediction of Forest Residues After Harvesting Timmerlinn Ltd., Ste.Agathe des Monts, Quebec Energy from Forest Biomass on Vancouver Island Paul H.Jones and Associates Ltd., Vancouver, B.C. Inventory of Forest Biomass Left After Logging in Forest Engineering Research Canada Institute of Canada. Pointe Claire, Quebec.

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P– Biomass Yield Tables for Aspen in Ontario K.W.Horton 30(1)* (2)* Biomass Potential of Aspen and White Birch in Ontario K.W.Horton P–36* Development and Testing of a Field Treatment System K.J.Blakeney for Logging Residues P–38* Tree Biomass Equations for Seven Species in M.F.Ker (M-X-114) Southwestern New Brunswick P–39* Biomass Harvesting and Chipping in a Tolerant B.S.Chisholm & G.D.van Raalte Hardwood Stand in Central New Brunswick P–40* Biomass and Nutrient Removals by Conventional and A.J.Hanson Whole-tree Clear-Cutting of a Red Spruce-Balsam Fir Stand in Central Nova Scotia Intensive Forest Harvest: A Review of Nutrient Budget B.Freedman (M–X–121) Considerations Forest Biomass and Nutrient Studies in Central Nova Scotia B.Freedman (M–X–134) P–41 Rate of Growth of Biomass in Young, Naturally-Regenerated Dr. A.J.Kayl Stands of Different Species and Origins P–51* Upper Limites of Standing Crop Density and Growth Rates for Western Ecological Woody Species in the Prairie Provinces Services Edmonton, Alta. P–54* Implications of Full-Tree Harvesting for Biomass Recovery Jean-Guy Routhier P–59* Energy Analysis of Energy from the Forest Options M.J.Ash, P.C.Knoblock and N.Peters P–64* A Proposal to Develop a Comprehensive Forest Biomass Dr. J.H.G.Smith and Growth Model D.H.Williams P–67 Planting Macine for Mini-Rotation Poplar HYD-Mech. Engineering Ltd. Woodstock, Ont. P–71 Field Research and Computer Simulation Modelling of the Dr. J.P.Kimmins Long-Term Consequences of Intensive Biomass Fertility and Biomass Production P–75 Intensive Culture of Plantations to Maximize Biomass Ontario Ministry of Production Natural Resources P–78&* Uses of Nitrogen Fixation and Other Root Symbioses for Dr. A.Fortin 198 Biomass Production P–92* Biomass Equations for Ten Major Tree Species of the Prairie T.Singh (NOR–X–242) Provinces P–95* Evaluation of Potential Impacts of Forest Biomass Harvesting Le Groupe Dryade Ltée, Que. P–102* An Improved Stand Growth Model for Trembling Aspen in K.O.Higginbothom, the Prairie Provinces of Canada (2 Volumes) I.D.Heidt and T.Grabowski P–112 Biomass Equations for Six Tree Species in Central Northland Associates Ltd., & 190* Newfoundland St. John’s, Newfoundland P–115* Whole Tree Chipping for Hogged Fuel in Newfoundland W.C.Wilton & W.P.Duffett George E.Ogar P–121* Effects of Spacing and NK Fertilizers on Dry Matter Accumulation and Nutrient Contents of Two-Year-Old Populus×euramericana cv. I-45/51 and cv.robusta DN17 P–135* Forest Biomass Energy in British Coumbia: Opportunities, T.McDaniels Impacts and Constraints P–138 Macronutrient Content of Deciduous Tree and Shrub Samples Northwest Soil Research

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from the Great Lakes-St.Lawrence Forest Region. P–139* Update of Canadian Activities in Poplar Biomass Production and Utilization P–140 Forest Biomass Inventory System

Ltd., Edmonton, Alta. L.Zsuffa, D.Boufford and M.A.Leggat Statistics Canada, Ottawa, Ontario G.H.Manning (BC–X–250) J.T.Standish

P–141* Metric Single-Tree Weight Tables for the Yukon Territory P–142* Development of a system to Estimate Quantity of Biomass Following Logging in British Columbia Forests to Specified Recovery Criteria P–143* Integrated Logging for Production of Pulpwood and Hog Fuel W.C.Wilton P–144* Manual of Data Collection and Processing for the I.S.Alamdag (PI–X–4) Development of Forest Biomass Relationships P–145 Reforestation of Areas Harvested for Biomass Price (Nfld) Pulp and Paper Ltd., Grand Falls, Nfld. P– Procedures for Estimating Newfoundland’s Biomass Reserves Northland Associates Ltd. 146* St. John’s, Newfoundland P– Development and Pilot-Scale Demonstration of an Integrated Systemshouse Ltd. Ottawa, 148 Information and Mapping Capability for Forest Biomass Ontario Inventories in the Prairie Provinces and the Northwest Territories. P– How Climate Affects Tree Growth in the Boreal Forest L.A.Jozsa, M.L.Parker, 149* P.A.Bramhall & S.G.Johnson P– Impact of Climatic Variation on Biomass Accumulation in the E.B.Peterson (NOR–X– 150* Boreal Forest Zone: Selected References 254) P– Biomass Harvesting in Tolerant Hardwoods Lake Superior Forestry 152* Services, Sault Ste.Marie Ontario. P– Hardwood Coppice Silviculture Perreault, Larouche, 154 Houde, et Associés, Quebec, Quebec P– Postcut Impacts in Hardwood Stands Le Groupe Dryade Ltée, 155 Quebec, Quebec P– Perspectives d’utilisation de la biomasse forestière au Quebec. L.J.Lussier (LAU–X–52) 157* Prospects for the Use of Forest Biomass in Quebec. P– Tree Biomass Equations for Young Plantation Grown Red Pine Ian Methven 158* (Pinus Resinosa) in the Maritime Lowlands Ecoregion P– Biomass Equations for Seven Major Maritimes Tree Species M.F.Ker (M–X–148) 159* P– Analysis of Salvage Yarding Systems and Costs in Pacific Coast George S.Nagle 162* Forests P–163* Costs of Harvesting Aspen Stands for Energy The Coban Institute Resource Production Management Consultants, Edmonton, Alberta P–164 Impact on Wildlife of Short-Rotation Management D.A.Westworth and Assocs. Ltd., of Boreal Aspen Stands Edmonton, Alta. P–169* Biomass Equations for Six Major Tree Species of T.Singh (NOR–X–257) the Northwest Territories

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P–170* Evaluation of Potential Interactions Between R.Coulombe & A.B.Lemay Forest Biomass Production and Canadian Wildlife P–172* A Pilot Study on the Feasibility of Establishing Alison Dyer Willow Energy Plantations in Newfoundland P–179* Mass Equations and Merchantability Factors for I.S.Alemdag (PI–X0–23) Ontario Softwoods P–182* Biomass Inventory of Tolerant Hardwoods in Dr. J.B.Thomas & 21 Algoma, Ontario P–183* Further Development of Logging Residue Forestal International Ltd. Vancouver, Processing Systems B.C. P–184* The Harvesting and Processing of Residual K.A.Nelson Biomass in Hemlock-Cedar Stands in the B.C. Interior Wet Belt P–189* The Economics of Harvesting Fuelwood Under D.C.Peters (M–X–139) Four Different Stand Conditions on Prince Edward Island P–190 Tree Weight Equations for Newfoundland Tree M.B.Lavigne (N–X–313) & 112* Mass Equations for Common Species M.B.Lavigne (N–X–313) P–191* Harvesting Forest Biomass as an Alternative Fuel Bowater Newfoundland Ltd. P–193 Regeneration Assessment Following Complete Tree Les consultants Pluritec Ltée. Harvesting Trois Rivières, Que. P–194 Alnus for Energy Production Pamper Inc. P–197 Computer Modelling of Intensive Biomass Management Dr. J.P.Kimmins Impacts P– Uses of Nitrogen Fixation and Other Root Symbioses for Dr. A.Fortin 198* Biomass Production & 78 P–199 Impact of Harvesting Immature Trees by the Whole-tree University of Guelph, Guelph, Method on the Microbiology, Organic Matter Contents, Ontario and Nitrogen Transformation of a Forest Soil P–201 Design and Fabrication of a Bundle Typing Device for the Hovey and Associates (1979) Mini-Rotation Harvester Ltd., Ottawa, Ontario P– Impact on Wildlife of Short-Rotation Management of D.A.Westworth and Assoc. 203* Boreal Aspen Stands Edmonton, Alberta P–205 Determination of Biomass and Nutrient Content in Trees, Alan Moss & Associates Ltd. Ground, Vegetation and Soil of Aspen Stands in the Kelowna, B.C. Prairie Provinces P–207 Development of an Integrated Harvesting and Processing Woodland Resource Services System for Hardwood Sawmilling and Energy Production Edmonton, Alberga P–210 Development of the RECUFOR Logging Residue Forest Engineering Research Processor (FERIC Proposal F–1) Institute of Canada, Pointe Claire, Quebec P–211 Preparation of Report on ENFOR Project P–152 Matcam Forestry Consultants Sault Ste.Marie, Ont. P–215 Application of the RECUFOR Rotor to Comminution of Forest Engineering Research Residues at Landings and Processing Plants Institute of Canada, Pointe Claire, Quebec P– Development and Testing of a Roll Splitter Forest Engineering Research

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216* P– 219 P– 224* P– 225* P– 226*

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Institute of Canada and K.C.Jones & Assoc. T.M.Thomson & Assoc. Ltd.

Availability and Cost of Forest Biomass in Canada

InterGroup Consulting Economists Ltd., Winnipeg Manitoba. Biomass Equations for Black Spruce Biomass in Quebec D.Ouellet (LAU–X–60E)

Potential Impacts of Intensive Forest Biomass The Environmental Applications Production on Reptile and Amphibian Populations of Group Ltd., Toronto Ontario Southern Ontario and Quebec P– Coordination of ENFOR Biomass Estimation Projects, T.M.Thomson & Associates 227 and Development of Biomass Estimates Based on Victoria, B.C. Provincial Timber Inventories P– Feasibility Study on the Conversion of an Oil/Gas Charles Turner & Associates Don 228* Heating Plant at CFB Borden to a Biomass Fuel Plant Mills, Ontario P– Development of a Mechanized Brush Harvester ELMS Design Inc., Ancanster 231 Ontario P– Transfer of Nigrogen Fixing Ability from Alder to Birch Université Laval, Ste.Foy 232 P– Energy Plantations and Soil Nutrients Levels Ontario Ministry of Natural 233 Resources, Kemptville, Ont P– Total Tree and Merchantable Stem Biomass Equations I.S.Alemdag (PI–X–46) 234* for Ontario Hardwoods P– Biomass Prediction Equations for Twelve Commercial D.Ouellet (LAU–X–62E) 236* Species in Quebec P– Modèle de simulation pour la récolte de et J.G.Routhier (LAU–X–53) 237* biomasse forestière P– Trial Conversion of Conventional Inventory D.Fowler 238* Data to Biomass Data in New Brunswick P– Pilot Trial of a Forest Biomass Inventory Northland Associates Ltd. St. John’s, 240 Newfoundland P– Pilot Study for a Canada Biomass Inventory Northland Associates Ltd. St. John’s, 242* Newfoundland P– Optimization of the RECUFOR Rotor Forest Engineering Research Institute of 243 Canada Pointe Claire, Quebec p– Review of the ENFOR Production Program Dendron Resource Surveys Ottawa, 245* Ontario P– Development of Biomass Prediction Equations M.R.C.Massie 246* for Yukon Tree Species P– Trial Conversion of Conventional Inventory G.D.MacQuarrie 247* Data to Biomass Data in Nova Scotia P– Land Application of an Industrial Sludge to Dupont Canada Inc. Maitland, Ontario 248 Hybrid Poplar Plantations P– Preparation of Report on ENFOR Project P-138 Dr. I.R.Methven Fredericton, N.B. 249 P– Processing Biomass in a Central Location with A.W.J.Sinclair (BC–X–255) 250* the Separator-Shear System

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P– 251* P– 252* P– 253

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Recovery and Transport of Roadside Biomass in A.W.J.Sinclair Mountainous Terrain Residential Fuelwood Supply and Demand in Greater T.M.Thomson & Associates Victoria and Vancouver Victoria, B.C. Socioeconomic Impact of an Integrated Fuel and Fire Nawitka Renewable Resource Production and Merchandizing System for the British Consultants Ltd., Victoria, B.C. Columbia Coast P– Green Volume (Basic) Specific Gravity of Tree Species in University of Alberta, Edmonton, 255 the Prairie Provinces Alberta P– Determination of Available Heat of Combustion Data for John M.Kryla 256* Canadian Woody Species P– Silvicultural Treatments to Maximize Biomass Production B.J.Horton 257* in Aspen Stands P– Ovendry Mass and Volume Equations for Canadian L.R.Roy 258 Species P– Biomass Growth and Yield Models for the Major Forest Woodlot Service (1978) Ltd 262 Cover Types of the Maritimes Fredericton, N.B. P– Domestic Fuelwood Consumption in Newfoundland Northland Associates Ltd. 263* P– Calibration of FORCYTE Simulation Model for Northland Associates Ltd. 264 Newfoundland Forest Types St.John’s, Newfoundland P– Cell Access for the 1984 National Biomass Inventory T.M.Thomson & Associates 265* P– Coordination of the National Forest Biomass Inventory T.M.Thomson & Associates Ltd., 266 Program Victoria, B.C. P– Compilation of Forest Biomass Inventories for New New Brunswick Dept. of Natural 268 Brunswick Resources, Fredericton, N.B. P– Compilation of Forest Biomass Inventories in Nova Scotia Nova Scotia Dept. of Lands and 269 Forests, Truro, N.S. P–270 Compilation of Forest Biomass Inventories for Manitoba Data Services Winnipeg, Manitoba Manitoba P–271 Compilation of Forest Biomass Inventories and British Columbia Ministry of Forests, Collection of Forest Biomass Data Victoria, B.C. P–272 Collection of Forest Biomass Data on Unsurveyed Dendron Resource Surveys Ottawa, Forest Lands in Ontario Ontario P–273 Collection of Forest Biomass Data for the Prairie Woodland Resource Services Provinces and Northwest Territories Edmonton, Alberta P–275 Collection of Forest Biomass Data for the Yukon Pacific Forest Research Ctre P–276 Production of National Forest Biomass Inventory Dendron Resource Surveys Ottawa, Report Ontario P– Harvesting of Forest Biomass for Energy Thérèse Sicard-Lussier 280* Terminology Study P–283 Collection of Forest Biomass Data for Quebec Le Groupe Dryade Ltée Quebec, Quebec P–284 Effect of Acid Rain in the Development of Université Laval, Ste.Foy, Quebec. Dr. Mycorrhiza A.Fortin P–285 Refinement, Evaluation, and Testing of FORCYTE Univ. of British Columbia Vancouver, Simulation Models B.C. Dr. J.P.Kimmins

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P–286 Calibration of FORCYTE Simulation Model for University of Toronto, Toronto, Application in Central Canada Ontario P–287 Impact of Intensive Forestry on Denitrification University of Windsor, Windsor, Kinetics in Forest Soils Ontario P–288 Assembly of a Base Collection of Canadian Alnus (various contractors) Seed P– Poplars and Willows—Their Socioeconomic Impact Poplar Council of Canada 289 in Canada P– An Analysis of Two Trials of a Portable Shear-type Philip Oakley & G.H. Manning (BC– 291* Residue Processing System X–249) P– Economic Evaluation of Wood Chip Production IEA Consulting Group Ltd. 292 Alternatives for P.E.I. Charlottetown, PEI P– Impact of Heavy Fuel Oil and Natural Gas Prices on Robinson Consulting & Assoc. 293* the Value of Biomass Delivered to British Columbia Victoria, B.C. Pulp Mills P– Review of Commercial and Industrial Wood/Peat Northland Associates Ltd. St.John’s, 294* Energy in Atlantic Canada, 1978–83 and Beyond Newfoundland P– Energy Biomass Yield by Selected Full-Tree Forest Engineering Research Institute, 295 Harvesting Methods in Frozen Conditions Pointe Claire, Quebec. P– Identification of Logging Waste in the Vancouver Nawitka Renewable Resource 296* Forest Region Consultants Ltd., Victoria, B.C. P– Field Testing of the Experimental Prototype of the Forest Engineering Research Institute of Canada and the Tennessee Valley 297 Roll Splitter Authority P– Report on European Congress on Economics and Sandwell and Company Ltd. 298 Management of Energy in Industry Vancouver, B.C. ENFOR PROJECTS—CONVERSION SERIES C–2* Assessment, Selection, and Commissioning of a B.H.Levelton & Associates Vancouver, Small-Scale Research Gasifier B.C. C–3* Great Lakes Forest Research Centre Boiler Study: Sanwell & Company Ltd. Vancouver, Wood Fired Boiler Feasibility Study B.C. C–4* Performance Monitoring and Thermal Efficiency Determination ADI Limited, Fredericton, of a Wood-Gas Heating System New Brunswick. C–5 Energy Self-Sufficiency through Total Residue Utilization by Stott Timber Corporation Conversion to Energy and Production of Marketable Fuel Sydney, N.S. C–6* Design, Construction, and Testing of a Pilot Scale Continuous Stake Technology Ltd. Dewatering Device Ottawa, Ontario C–7* Hog Fuel Availability in British Columbia P.W.Appleby C– Evaluation of Wood Gasifier at Hudson Bay, Sask. Saskatchewan Power 8(1)* Corp. C– The Social, Environmental and Resource Impact of Wood Saskatchewan Power 8(2)* Gasification on Isolated Northern Communities Corp. C–9* Evaluation of a Fixed Bed Wood Gasifier Using chipped Round Manitoba Research Wood as Fuel Council C– Application of Fluid Bed Technology to the Gasification of A.Dalvi 12* Waste Wood C– Oil Replacement on a Pulp Mill Lime Kiln Using Hog Fuel in a I.G.Rowe 14* Lamb Wet-cell Burner

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C– Rapid Gasification of Wood Waste H.G.Brandstatter 18* C– A Study on the Rapid Devolatilization/Hydrogenation of S.N.Basu; P.C.Stangeby 24* Biomass Material C– The Flash Pyrolysis of Wood in a Bench Scale Fluidized Bed D.S.Scott 28* C– Pilot Plant Investigation of a Wood Gasifier for Generation of G.A.Weisserber 29* Electricity C– Catalytic Pyrolysis and Gasification of Lignocellulosic Materials E.Chornet 33* C–39* Development of Techncial Basis for Assessing Wood Gasifier D.W.Bacon; J.Downie Design and Operation C–44* Further Studies on Wood Liquefaction through Operation of a D.G.Boocock; Continuous/Semi-continuous Wood Liquefaction Unit D.Mackay C– Study of the Conversion of Lignocellulosic (Aspen) Materials to J.M.Pepper; R.L.Eager 48(1)* Liquid Fuels and Chemicals C– Production of Liquid Fuels & Chemicals from Lignocellulosic J.M.Pepper; R.L.Eager 48(2)* (Aspen) Materials C–51* Supercritical Gas Extraction of Chemicals from Forest Products; J.Howard Phases I-III C–53* Characterization of Tar Produced during Gasification of Wood D.W.Duncan C–68* Application of a Fluidized Bed Gasifier to Conversion of Forest G.Gurnik; K.Luke Biomass to an Energy Source C–69* Study on the Design and Optimization of Biomass Liquefaction SNC Inc., Montreal, Process Units Quebec C–87* Biological Transformation of Waste Forest Biomass to Humus for A.McNaughton; Use as an Agricultural Soil Amendment S.J.Cunningham C–92* Evaluation of Fuels for Operation of a Fixed-Bed Downdraft Forintek Canada Corp. Commercial Gasifier C–95* Wood Waste Fuels Preparation and Handling B.H.Levelton & Assoc. C–96* Cost Benefit Analysis of Systems Using Fuel Gas or Steam for Sandwell & Company Drying of Wood Waste Feedstocks Ltd. C–97* Development of a Moisture Resistant Densified Solid Fuel from B.H.Levelton & Assoc. Forest Biomass C– A Study on the Rapid Devolatilization/Hydrogenation of P.C.Stangeby; S.N.Basu 98* Biomass Material, Phase Il C– A Kinetic and Catalytic Study for the Optimization of the Forintek Canada Corp. 103 Fluidized Bed Gasification Process Ottawa, Ontario C– Development and Small-Scale Demonstration of a Reliable on- T.Y.Yung 110* line Monitor for the Continuous Measurement of Feedstock Moisture Content C– Evaluation of Wood Waste Energy Conversion Systems, 1980 B.H.Levelton & Assoc. 111* Edition C– Study on the Generation of Design Data for Biomass N.E.Cooke; J.M.Moffatt 118* Liquefaction Pilot Plant C– Wood Residues as Fuel Source for Lime Kilns R.J.Philp; M.K.Azarniouch 123* S.Prahacs C– Evaluation of Infrared Moisture Analyzers for Hog Fuel

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124* C– 130* C– 143* C– 144* C– 147* C– 149* C– 150* C– 154* C– 166* C– 172* C– 178* C– 181* C– 185* C– 187* C– 191 C– 197* C– 209* C– 214* C– 220* C– 221* C– 222 C– 223* C– 235

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Bin and Silo Design for Biomass Materials Phase I

N.Brundalli; O. Martinez

Identification of Hydrocarbon Emissions from Industrial Combustion of Forest Biomass/Oil Mixtures A Study of Pyrolytic Explosion for Subdividing Wood

Charles J.Wiesner

Ultrapyrolysis of Cellulose and Wood Components

Univ. of Western Ontario

John Stone & Assoc.

Advanced Feedstock Preparation System for Large-Scale Hog Industrial Process Heat Fuel Boilers Eng. Ltd., Vancouver, B.C. Development and Demonstration of a Small-Scale Gasifier for Industrial Process Heat Wood Waste Engineering Ltd. RF Transmission Line Method for Feedstock Moisture Content Carleton University Determination Ottawa, Ontario Evaluation of Reforming as a Practical Technique for the J.W.Black Elimination of Water Pollution from Wood Gasifiers Development of Analytical Methodology for Biomass E.G.McDonald Gasification Products Production of Electricity Generation by Wood-Fired Steam SNC Inc., Montreal, Quebec Engines for Remote Communities Conversion of Cellulose to Ethanol Using a Two-Stage J.N.Saddler Process A Review of the Options Available to the Forest Industry for B.H.Levelton & Assoc. Producing Electricity from Wood Residues Liquid Fuel Production from Hemicellulose J.N.Saddler Forest Product Based Sacrificial Agents for Enhanced Oil Recovery Technical Assessment of Down-Draft Wood Gasifiers

B.C.Research, Vancouver, British Columbia D.Bacon

Development of Lignin Adhesives

T.Szabo; J.Shields

Hog-Fuel Drying Using Vapour Recompression

N.Sayegh; M.K.Azarniouch

Fuel Value of Stored Forest and Mill Residues

H.Unligil

RF Transmission Line Methods for Feedstock Moisture Content Determination Pretreatment Preparation of Forest Biomass as Feedstock for Bioconversion Processes Continuous Flash Pyrolysis of Wood

Avtech Electrosystems Ltd. Ottawa, Ontario. Univ. of Waterloo Waterloo, Ontario D.S.Scott

Test Program on Boilers Burning Wood Refuse

Canadian Boiler Society & Environcon Eastern Ltd., Toronto, Ontario C– Comparative Study of Laser Spectroscopic Techniques for MPB Technologies Inc., 240* Analysis of Biomass Gasifier Products Ste.Anne de Bellevue, Que.

Canada's energy from the forest programme

C– The Development of Machinery for the Recovery and 253* Preparation of Biomass Feedstocks for Conversion Systems at a Central Full Tree Processing Complex C– Forces Exerted on Restraining Structures by Hog Fuel 254* Piles C– Development of a Method for Characterizing Pyrolytic 256* Oils C– Effect of Particle Size on Gross Heat of Combustion of 257* Wood C– A Comparative Assessment of Forest Biomass Conversion 258* to Energy Forms C– 259* C– 273 C– 288* C– 293* C– 295* C– 299* C– 300* C– 326 C– 334* C– 343 C– 378 C– 390 C– 401 C– 433 C– 442

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D.D.Hamilton

W.C.Edwards H.Ménard; C.Roy J.M.Kryla Simons Resource Consultants B.H.Levelton & Assoc., Vancouver, B.C. B.H.Levelton & Assoc.

Development of a Dense Phase Pneumatic Conveying B.C.Research Vancouver, B.C. System for Biomass Materials Further Development of Processes for the Conversion of D.G.B.Boocock; D.Mackay Wood to Liquid Fuels Through the Operation of a Continuous/ Semicontinuous Liquefaction Unit Research on Gasification of Wood in a Plasma Pyrolysis Resorption Canada Ltd. Unit Study of Biomass Feedstocks from Poplar Wood Using E.McDonald; J.Howard Supercritical Fluids Pretreatment Methods for Enhancing Conversion of Forintek Canada Corp. Ottawa, Lignocellulosic Material to Liquid Fuel Ontario Feasibility Assessment of Biogas Generation by Anaerobic ADI Limited, Fredericton, Fermentation of Pulp and Paper Wastes New Brunswick Detailed Design, Construction, and Initial Operation of a University of Sherbrooke Vacuum Pyrolysis Process Development Unit Sherbrooke, Quebec. C.Roy Electrical Discharge Flash Pyrolysis of Biomass A.N.Sivell; J.M.Beekmans Suspension Firing of Pulverized Biomass in Large Industrial Boilers Scale-up Testing of IOTECH’s Enzyme Production and Hydrolysis Unit Processes with Subsequent Commercialscale Testing of Lignin Resins Tall Oil as Fuel for Mobile Equipment in the Kraft Pulp Industry Wood Firing of Lime Kilns in Bleached Kraft Mills

Millar Enterprises, Powell River, B.C. IOTECH Corporation Ltd. Gloucester, Ontario.

Prince Albert Pulp Company Limited. Domtar Inc., Senneville, Quebec Grinding of Wood Chips and Bark to Fine Powders University of Toronto Toronto, Ontario Study on the Techncial Viability of a Low Pressure/Low McGill University, Montreal, Temperature Process for the Conversion of Wood to Liquid Quebec. Dr. W.J.M.Douglas Fuels and Chemicals NOTES: *=Report Available To obtain Production Series Reports contact Canadian Forestry Service, Environment Canada, Place Vincent Massey, Hull, Quebec. K1A 1C8

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To obtain Conversion Series Reports contact Energy, Mines and Resources, Renewable Energy Division, 460 O’Connor Street, Ottawa, Ontario. K1A OE4

INTEGRATED FOOD-ENERGY PRODUCTION SYSTEMS E.L.La Rovere FINEP—Financiadora de Estudos e Projetos Av. Rio Branco, 124, Rio de Janeiro, 20042, Brazil Summary The sharp increases of oil prices in the international market during the seventies put a heavy burden on the trade balances of oil importing developing countries. For those third world countries having large land availabilities and suitable climatic conditions, the domestic production of energy from biomass as a substitute for oil products is seens as a hopeful alternative. However, if appropriate measures are not taken the production of bio-energy may be achieved at the expense of the agricultural performance related to its traditional goals: providing food, industrial feedstocks and export products Brazil was the world pioneer in launching an important national alcohol programme in 1975. Today more than 10 billion litres a year of alcohol are produced from sugarcane and more than one and a half million cars run on pure alcohol engines. Besides that, all the gasoline consumed in the country has an alcohol content of 20% on average. However, the programme relies on capital-intensive big plantations with disruptive social and ecological effects. The best agricultural land, government capital funds and subsidies, as well as private savings, are being channelled into the production of alcohol from sugarcane aiming to reduce the oil import bill at the expense of the food production for the internal market. Integrated food-energy production systems offer a promising alternative of better utilisation of biomass resources, avoiding the potential risk of competition between fod and energy production. In Brazil, the need for establishing an alternative model of producing energy from biomass, in opposition to the way that alcohol production is being developed, led to an effort on research, development and demonstration for integrated food-energy production systems. A number of programmes and projects applying this concept are being sponsored by FINEP. Research and development in this field presents a wide range of possibilities for south-south cooperation. The main findings of an international seminar jointly organised by FINEP, UNESCO and the United Nations University, held in Brasilia (September 1984) indicate the large scope for scientific and technological cooperation on the foodenergy nexus and related fields among third world countries.

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I. L’Interface Enérgie/Alimentation au Tiers Monde L’approvisionnement en énergie et aliments est une dimension absolument essentielle du développement socio-économique, ca la satisfaction de ces deux types de besoins est une condition sine qua non de la survie humaine. L’augmentation des prix du pétrole dans le marché international, qui s’est produite au cours des années 70, a difficulté l’élévation de la consommation énergétique des pays du Tiers Monde importateurs de pétrole avec l’aggravation de la situation de leurs balances de paiements. La production interne d’énergie à partir de la biomasse, dans des pays a grande abondance de terres disponibles et conditions climatiques appropriées, a été considérée comme une alternative prometteuse pour rendre viable l’expansion de la consommation énergétique, en se substituant aux derives de pétrole. Cependant, mème dans des contextes avec abondance de terres disponibles, la production de bioénergie peut se fair aux dépens de la performance agricole mesurée par rapport at ses objectifs traditionnels: production alimentaire, approvisionnement de l’industrie en matières premières et produits d’exportation. Le risque de compromettre l’augmentation de la production alimentaire merite une attention particulière, en vue des niveaux précaires de consommation de calories e protéines de la population dans la plupart des regions du Tiers Monde. En plus, les petits producteurs, responsables d’un apport important a la production alimentaire, en général, se trouveront dans des conditions disavantageuses pour concurrencer les puissants interêts commerciaux de la production d’énergie (qui épargne des devises) dans l’approvisionnement en ressources essentielles comme intrants, credits, main d’oeuvre qualifiée, facteurs de production rares dans ces pays. II. Le Concept de Systèmes Intégrés Dans ce contexte la poursuite d’une integration entre la production d’énergie et d’aliments apparait comme un essai de concévoir des solutions technologiques appropriées à l’harmonisation de ces deux objectifs. Cet approche propose une planification “ex-ante” de l’utilisation du sol, des déchets agricoles, animaux et forestiers et des ressources aquatiques, mettant en valeur les complementarités possibles au lieu de la simple juxtaposition de grands projets intensifs en capital, si typiques des essais de modernisation de l’agriculture aux tropiques. À travers la promotion de cultures associées, l’utilisation des résidus agricoles pour produire de l’énergie et réciproquement, la mise en valeur des résidus de la production énergétique dans les activités agricoles, on cherche a obtenir un effet de sinérgie. La productivité globale du système serait donc supérieure à l’adition des deux productions (énergétique et alimentaire) effectuées separemment avec l’emploi de la même quantité de ressources. De cette façon les impacts sur l’environ-nement seraient réduits a un niveau minimum et on pourrait rendre viable une decentralisation de la production avec les maximum d’impacts sociaux béné-fiques pour les petits producteurs. Le défi à être rélevé par la recherche consiste donc dans la conception, experimentation et mise a point de differents schémas technologiques appropriés aux ecosystèmes et contextes socioéconomiques divers, qui soient a la fois économiquement viables, socialement désirables et soutenables sur le plan écoloqique.

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III. Explorant les Possibilités de Coopération Sud-Sud Pionnier au monde dans la mise en oeuvre d’un programme de production a grande échelle de combustibles liquides à partir de la biomasse, à travers le Plan National Alcool, le Brésil occupe aussi une place de relief dans la scene internationale par ses activités de recherche et développement de systèmes de production intégrée d’aliments et énergie. On peut mentionner, parmi d’autres les projets de systèmes d’autoapprovisionnement énergétique developpes par l’EMBRA* et le Programme des Communautés Agro-énergétiques créé par la FINEP**. Cet effort a attiré l’attention de l’Université des Nations Unies-UNU, qui a récemment lancé, à la fin 1982, un programme d’études sur l’interface énergie/ alimentation (1). Ce programme, qui vise particulièrement a la promotion d’un échange scientifique et technologique au niveau international dans ce domaine, a soutenu la visite d’une mission brésilienne au Sénégal, en Inde et an Chine, réalisée en novembre-decembre 1983. Son but a été celui de favoriser l’échange d’informations, de résultats et d’approches de la recherche dans ce domaine parmi chercheurs et responsables de la planification de différents pays en voie de développement, qui doivent rélever des défis et contraintes du même genre. Evidemment, cet appui a la cooperation scientifique et technologique internationale ne voulait pas promouvoir une simple transposition de l’exper-ience brésilienne à la réalité africaine ou asiatique, et vice-versa, ce qui serait à l’opposé de l’approche mème de concévoir differéntes configurations technologiques de systèmes intégrés selon les specificités de chaque contexte. Au contraire, le type d’échange Sud-Sud at poursuivre, a notre avis, doit s’inscrire dans l’esprit de la loi, ennoncée pour l’Histoire mais valable aussi pour l’analyse comparative internationale: “elle ne fournit jamais des modèles a suivre, mais seulement des anti-modèles à superer. Cet article present quelques observations effectuées pendant le voyage, d’une duration totale de cinq semaines (une semaine au Sénégal, deux en Inde et duex en Chine, grosso modo) (2). Nous n’avons donc la prétension de traiter d’une facon systématique et rigoureuse un sujet si vaste et complexe comme celui de la réalité agroénergétique des regions diverses des pays visités. Nous nous bornerons ici a enrégistrer quelques impressions recuillies au long de ce parcours, et qui donnent lieu a des reflexions sur les possibilités de cooperation scientifique et technologique entre le Brésil et les pays visités, dans le domaine de la recherche et développement de systèmes intégrés de production d’énergie et aliments, et domaines liés. IV. Le Cas Brésilien IV.i. Un bref bilan du Plan Alcggl La conception de programmes de recherche et développement de systèmes intégrés de production d’énergie et aliments au Brésil est nee de l’évaluation de la performance du Plan Alcool. Ses résultants sont indéniablement positifs en termes de l’augmentation de la capacité de production d’alcool dans des délais trés courts: elle atteint aujourd’hui environ 8 milliards de litres par an, faisant rouler plus d’un million de voitures à l’alcool pur, et permettant un apport de plus de 20% d’alcool dans de melange carburant

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essence/alcool. Cependant, il éxiste certainement un énorme potentiel d’augmentation de la productivité du procédé d’obtention de l’alcool à partir de la canne à sucre, soit au niveau agricole (production de la canne à sucre) comme au niveau industriel (production de l’alcool dans les distilleries), à travers l’introduction de procédés technologiques plus performants, ce qui permettrait d’améliorer l’éfficacité économique due Plan Alcool et de réduire son impact dans l’augmentation du niveau des prix. * Empresa Brasileira de Pesquisas Agropecuárias—l’entreprise de recherche agricole du Ministère de l’Agriculture brésilien. ** Financiadora de Estudos e Projetos—l’agence pour le financement de projets de recherche et développement technologique du Ministère du Plan brésilien.

La réussite des objectifs sociaux du Plan Alcool a été fortement, 1imitée par le modele adopté pour l’expansion de la production d’alcool, base sur l’ctroi de facilites de financement pour l’implantation de distilleries, de grande taille (120 mille litres par jour et plus) aux grands propriétaires de vastes monocultures de canne à sucre du genre “plantation” où la main d’oeuvre est employee dans des condions très précaires, aggravées par un chômage saisonnier. Quant à l’aspect écologique, il faul résoudre avec urgence le problème de traitement des énormes volumes de vinasses résiduelles produites dans les distilleries (10 a 17 litres par litre d’alcool produit) et très polluantes des cours d’eau, à travers l’emploi de procédés technologiques nouveaux qui réduisent le volume de ces résidus et rendent possible son utilisation économique (par exemple, la digestion anaérobie). Enfin, it faut rappeler que parallèlement à l’augmentation de la production d’alcool on remarque une diminution de la production par tête des principaux produits alimentaires de base et une élévation du niveau des prix des aliments supérieure même aux taux d’inflation, sans précedent dans l’histoire économique du pays, récemment enrégistrés. Sans approfondir la polémique sur le degré de resonsabilité du Plan Alcool dans la production de ces deux phénomènes, nous pouvons constater que l’expansion de la surface cultivée avec canne a sucre a déjà commence à déplacer des cultures alimentaires, au moins dans les regions à frontière agricole quasiment fermée, comme l’état de São Paulo (3). En tout cas, le risque potentiel de compétition avec la production d’aliments devra être pris en compte avec attention toujours croissante dans le futur, au fur et à mesure que la production d’énergie de biomasse augmente, soit à travers le Plan Alcool comme par d’autres programmes dont on examine la possibilité de creation (huiles végétales, alcool à partir d’autres matières premières, etc.). IV.ii. Les systèmes intégrés de production d’énergie et aliments au Brésil Les premiers systèmes intégrés de production d’énergie et aliments proposes par la communaûté technito-scientifique brésilienne étaient centres dans leur conception sur la combinaison d’élements divers autour d’une microdistillerie d’alcool. Le renforcements divers autour d’une micro-distillerie d’alcool. Le renforcement du Plan Alcool à partir de 1979 a éveillé un grand interèt sur la possibilite de se décentraliser la production d’alcool a“travers l’implantation de micro et mini-distilleries (500 à 20.000 litres par jour), pour augmenter les bienfaits sociaux et minimiser l’impact ecologique du programme. Une polemique aigüe sur la viabilité technoéconomique de la production d’alcool en petite

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éche le s’est alors instauree. Aujourd’hui, on semble s’orienter vers la conclusion que, même isolée, la micro-distillerie est économiquement viable et se compare bien vis-à-vis de la production d’alcool en grande échelle (4). En 1981, l’EMBRAPA a lancé, dans le cadre de son Programme National de Recherches sur l’Énergie, une ligne de recherche et développement de systemes de production de bioénergie en milieu rural. La configuration de base des huit systèmes en operation dans les unites de terrain de l’EMBRAPA rassemble les élements suivants: – micro-distillerie d’alcool de canne à sucre et sorho doux (ou manioc, beterrave) – élévage bovin sous stable – biodigesteur de déchets animaux (et/ou bagasse, vinasses) – production d’électricieté et fonctionnement de machines agricoles par l’utilisation de l’alcool ou biogaz (ou gazogènes) – application du biofertilisant dans les champs de culture Cette configuration de base, avec quelques variations, est aussi appellée par l’EMBRAPA de systèmes d’Auto-Approvisionnement Energétique, dans la mesure où ils veulent essentiellement assurer l’auto-suffisance énergétique au niveau de la proprieté rurale (5). Une configuration semblable, mais plus compléte, incluant aussi la culture en milieu aquatique de jacynthes d’eau et l’élévage de poissons, est proposée dans le Système Intégré de Production de Bioénergie et Protéine Animale. Ce systéme, testé dans l’unité de terrain du Secretariat à l’Agriculture de l’état de Rio Grande do Sul, à Capela de Santana, vise explicitement à la production d’un surplus d’énergie (sous la forme d’alcool) et d’aliments (grains de sorgho, viande de boeuf et poissons) pour la commercialisation. L’alcool est produit dans une micro-distmerie (500 litres/jour) à partit de la canne à sucre (25 hectares) et du sorgho doux (41 hectares). Les feuilles et pointes de canne et de sorgho, et une partie de la production de grains de sorgho, sout utilisées dans l’alimentation de 80 têtes de bétail. Une partie des bagasses de canne et de sorgho, aussi bien que la protéine qu’on peut obtenir a partir de la jacynthe d’eau, peuvent être testées avec le même but. Le biodigesteur (100 metres cubes) produit, à partir des déchets animaux, du biofertilisant pour les champs de canne et sorgho et pour les bassins de poissons, en plus du biogaz qui peut être utilisié pour la production de vapeur dans la micro-distillerie ou pour faire face aux bésoins énergetiques de la population rurale, Une partie de la bagasse de canne et de sorgho se destine a la chaudière de la micro-distillerie, et le surplus est disponible pour l’utilisation à l’exterieur du systeme, comme matiere premiere de la fabrication de pate a papier ou comme combustible. La vinasse est utilisee pour la production de jacynthes d’eau et, ensuite, clarifiée, comme base de l’activité de pisciculture, ce qui évite la polution et contribue à l’obtention de protéine animale et végétale (6). Une analyse préliminnaire de viabilité économique (7) indique que ce système intégré présente une rentabilite superieure à celle des distilleries d’alcool isolées (soit les micro comme les macro), mème sans prendre en compte dans le calcul quelques activités qui demandent encore a mieux éprouvees du point de vue technologique (utilisation de proteine obtenue a partir de jacynthes d’eau et de la bagasse dans l’alimentation du bétail) ou commercial (exportation des sous-produits bagasse et biogaz a l’exterieur du système). Le programme de Communaùtés Agro-Energetiques propose par la FINEP (8) suggere la generalisation de l’approche qui même de la micro-distillerie au système intégré, c’est

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à dire: at partir de chaque contexte socio-économique et ecosysteme specifique, concévoir une configuration technologique appropriée à la production integree d’energie et aliments, selon des critères de viabilité economique, de l’ampleur des bienfaits sociaux et de maitrise des impacts ecologiques à long terme. La methodologie pour conćevoir le complexe agro-énergétique doit partir du bilan des ressources naturelles disponibles et due diagnostic socio-economique établi avec le maximum de participation de la communaùte locale. Il est encore suggére que l’implantation, le suivi et l’évaluation du système integré combinent un niveau de recherche et dévelop-pement avec un stade de demonstration, de facon à minimiser le risque technologique à étre supporte par les petits producteurs ruraux. Le degré de sophistication des options technologiques retenues doit etre compatible, ou bien rendu compatible par moyen d’un processus pedagogique approprié, avec maximum d’autonomie au niveau local dans la fabrication, l’opération et le maintien de l’équipement nécéssaire. Enfin, deux orientations sont à éviter: (a) la simple installation d’équipements chers et sophistiqués pour la mise en valeur de sources non conventionnelles d’énergie (capteurs solaires, éoliennes, biodigesteurs) visant à la satisfaction des bésoins demésti-ques en énergie de la population rurale, comme l’on peut remarquer dans quelques projets de ce genre. La cojugaison de la production energetique avec une activité agro-industrille, capable de fournir un surplus économique à la communaûté locale, est absolument essentielle si l’on veut démontrer la viabilité économique de la généralisation de l’exper-fence pilote a d’autres communaûtés rurales. (b) la production d’un système intégré donné, “standard”, dans des contextes divers at être adaptés pour rendre possible son utilisation. Au contraires, les procédés technologiques et les formes d’organisation sociale associées aux systèmes intégrés doivent varier et constituer des configurations différentes selon les particularités de chaque cas. Un projet de recherche et développement d’une communaûté agro-énergétique dans la region de Tabuleiros de Valença, au sud de Salvador (Bahia), a été démarré par la CEPLAX (*) et le CEPED(**), avec soutien de la FINEP (9). Son but est de concévoir et implanter un système intégré de production d’énergie et aliments base sur le développement de technologie appropriée pour l’extraction d’huille de palme en petite échelle, avec la mise en valeur des sous-produits, et sur l’association des cultures d’haricots, mais, manioc, bananes, etc., avec les palmiers a huile, occupant les interstices de la plantation de palmiers (espacés de 10 en 10 metres). L’huile de palme produite peut être utilisée comme carburant, car elle se substitue tres bien au gazoil après son craquage catalytique, déjà testé avec succès dans les raffineries de PETROBÁS (***) et, au stade de laboratoire, par le CEPED (où on a obtenu jusqu’à 720 kg de “gazoil végétal” à partir de 1 tonne d’huile de palme). L’extraction de l’huile de palme dans une micro-usine (1.5 tonne/heure de matiere premiere) performante, avec la mise en valeur des sous-produits dans la production d’énerqie, fertilisant et matières premières industrilles, permettrait de rendre viable sa production par une cooperative de petits paysans, gardant une tradition de polyculture qui éxiste déjà dans la region. Du point de vue agronomique, en plus de l’augmentation de productivité des palmiers à huile, on cherche a travers les cultures associées d’obtenir un degré plus éléve d’auto-suffisance alimentaire et d’augmenter les recettes de commercialisation de matieres premieres pour la communaùté locale.

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(*) Comissà’o Executiva para a Lavoura Cacaueira—agence du Ministère de l’Agriculture responable, dans la region, de la culture du cacao et du développement agricole. (**) Centro de Pesquisa e Desenvolvimento—centre de recherche et développe-ment technologique de l’etat de Bahia. (***) Entreprise d’Etat pour l’exploration, production, raffinage, transport et distribution de pétrole et ses derives.

D’une facon génerale, l’approche de développement de systèmes intégrés de production d’énergie et aliments présente encore un grand potentiel à être exploité dans le cas du Brésil: on peut souligner son interèt particulierè-ment pour les zones d’expansion de la frontière agricole, comme les savannes brésiliennes (“cerrados”) et la region amazonienne. References 1. Sachs, Ignacy. The Food-Energy Nexus, Subprogram Proposal, United Nations University, Paris-Tokyo, October111982. 2. La Rovere, Emilio Libre: South-South Cooperation in the Framework of UNU’s Food-Energy Nexus Subprogram. Report of the visit of a Brazilian team to Senegal, India and China, April 1984. 3. Coordenadoria de Planejamento e Avalicao do IAA/PLANALSUCAR: A cultura da cana-deacucar e a evolcuao do uso da terra em Sao Paulo, 1974 a 1979. 4. CNPq: Avaliacao da Viabilidade Tecnico-Economica de Microdestilarias de Alcool, Brasilia, 1983. 5. Corgatti Netto, Agide: Yeganiantz, Levon: EMBRAPA’s Food-Feed-Bio-Energy Production Systems, EMBRAPA, Brasilia, 1982. 6. Porto, Rogerio Ortiz: Bio-Energy and Animal Protein Production System—Capela de Santana; Resource Management and Optimisation, Vol.3, No.1, 1983. 7. Tolmasquim, Mauricio Tiomno: Avaliacao de Sistemas Integrados de Producao de Energia a Alimentos; these en elaboration pour la COPPE/ UFRJ. 8. Baiardi, Amilcar, La Rovere, Emilio Lebre: Food-Energy Integrated Development Schemes in Brazil: FINEP’s Agro-Energy Communities Programme; Resource Management and Optimization, Vol.3, No.1, 1983. 9. Aguiar, Sergio Catao, Oliveira, Hermano Peixoto: Agro-Energy Community—Tabuleiros de Valenca; Resource Management and Optimization, Vol.3, No.1, 1983.

THE USE OF WASTES AS A SOURCE OF ENERGY FOR THE UK DR R PRICE Energy Technology Support Unit, Harwell, England Summary In the UK interest in biofuels is focussed on the use of wastes as a fuel rather than energy crops. This is mostly because of the pressure to use a restricted land area for producing higher value food and timber crops. However wastes are attractive in their own right as fuels particularly since there are often environmental benefits to be gained as well as fuel costs to be saved. The paper describes the UK programme of waste-as-fuel demonstration projects and some of the lessons which have been learned.

1. INTRODUCTION Biofuels are fuels which, directly or indirectly, have an organic origin. They include not only agricultural and forestry energy crops of various sorts, but also waste products derived originally from these sources. Wastes can come in a variety of types, shapes and sizes. Domestic rubbish ranges from teabags to bedsteads but commercial, industrial and farm wastes are fairly well defined. Paper, plastics and packaging make up the bulk of commercial and industr al waste, but in addition, there are residues of manufacturing processes. On farms, animal wastes, crop residues and straw are produced in large quantities. In developing a programme to research or promote the use of biofuels, each country will place a different emphasis on the relative importance of wastes to energy crops. The UK view is much influenced by our own particular national situation. We have a relatively densely populated country which is not self sufficient in food production. Moreover, we produce less than one tenth of our timber requirements. On the other hand we are in the fortunate position of being a net energy exporter. In addition we are relatively well endowed with fossil fuels, the most notable of which are known coal reserves amounting to at least 400 years supply at the current rate of use. Bearing in mind that both food and timber are of much higher value per kilogramme than energy crops, it becomes understandable why our first priority is to use our limited land area for the former more conventional uses.

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UK FOOD, TIMBER AND ENERGY PRODUCTION: TABLE 1 The UK produces: • 63% of its food requirements (by value) • 9% of its timber requirements • 105% of its energy requirements

Wastes, on the other hand cannot be ignored; if they are not exploited they have to be disposed of in some other way. In the UK, this includes burying large quantities of refuse in landfill sites, releasing treated industrial effluent into waterways and burning unwanted straw in the fields. Where organic wastes can be used as fuels, there are therefore often associated environmental benefits. In many cases these can be translated directly into financial savings, through savings in waste disposal costs. The value of environmental benefits together with associated fuel savings can often therefore make the use of waste as fuel an attractive option. Work is now well advanced in the UK Department of Energy’s “Waste as Fuel Programme”. Initially studies looked at the size of the resource of usable waste, determined its nature, and investigated where it could be used sensibly and economically. These showed that wastes totalling over 22 million tonnes of coal equivalent are technically available for use as fuel each year, and over a quarter of this amount could be used economically at today’s energy prices.

THE UK WASTE RESOURCE: TABLE 2 WASTE TYPE

DRY WASTES (FOR domestic commercial Industrial straw

TOTAL WASTE TECHNICALLY AVAILABLE Mtcepa

ECONOMIC POTENTIAL Mtcepa

COMMUSTION)

WET WASTES (FOR ANAEROBIC DIGESTION) agricultural – animal – crop resldue domestic – sewage – landfill industrial (food & drink)

1.5

3.5 1.3 0.6 19.2

2.0 0.8 0.4 0.2 4.9

1.7 0.8

0 0

0.4 (3.8)

0.2 0.4

0.1

0.1

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3.0 (6.8)

0.7

22.2

5.6

TOTAL, DRY & WET WASTES Note: 1 Mtce=27GJ

Technologies for handling, treating and burning wastes were also studied to determine how they should be developed further and what new techniques would be necessary to improve technical and economic viability. Many of these technologies are in principle available but there has been a reluctance to move towards using them because of fears about associated risks, high capital costs and reduced convenience. Our first priority has therefore been to move towards a comprehensive programme to demonstrate how and under what conditions it is sensible to use wastes as fuel. Under the Energy Efficiency Demonstration Scheme we are planning a total of 56 demonstrations of the use of domestic, industrial, commercial, agricultural and wet wastes. This will cost about £25 millions, of which the UK government will pay one quarter, but is expected to stimulate energy savings of around 1.8 million tonnes of coal equivalent per year in the longer term. 25 of these projects are now under way and some of them are described in this paper.

UK WASTE-AS-FUEL DEMONSTRATION PLAN: TABLE 3 WASTE PROJECTS COST TO GOVT. £k REPLICATION POTENTIAL 000 tce/y Domestic Industrial Agricultural Wet TOTAL

8 31 9 8 56

1,905 2,785 812 761 6,263

560 514 482 240 1,786

There are several different ways of using waste as a fuel. Dry materials can be burnt directly to provide heat and even those with a higher moisture content may be suitable for combustion after some drying and processing. Wastes too wet to burn can best be converted to fuel by anaerobic digestion, biological breakdown in the absence of oxygen, producing methane gas. The method adopted will depend on the nature of the waste, where it occurs and where it will be used as a fuel. These are the two techniques which are nearest to commercial use: there are others, such as methods of conversion to liquid fuels which may offer some promise in the longer term if early research is successful and if conventional fuel prices continue to rise. 2. COMBUSTION The principle of burning waste to provide useful energy is not new. However in recent years, increases in the price of fuel coupled with technological improvements and a growing awareness of the need to find new ways of dealing with waste have renewed

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interests in combustion. It is now the most advanced technique available for utilising the energy content of waste. Even after separation from its non-combustible components, waste has different properties from more conventional fuels, and has to be burnt either in specially designed equipment or in modified coal-burning systems. Several technical options are available. It can be burnt with little or no pre-treatment in large incinerators or purpose designed boilers, or it can be processed to a greater or lesser degree so that it can be used in a smaller, simpler and cheaper furnace. There is obviously a trade-off between the cost of processing and the cost of the furnace equipment. The system adopted will depend on the nature of the waste, the scale of operation and the pattern of heat use. Domestic Waste Although most of the domestic waste in the UK goes directly to landfill, it is becoming more difficult in urban areas to dispose of it in this way. Suitable sites are becoming increasingly scarce and in many cases waste is transported considerable distances for disposal. Local Authorities are faced with rising transport costs and a growing reluctance of residents near disposal sites to accept other people’s rubbish. Burning waste can provide useful heat; it also reduces the volume which must be dumped and improves the economics of disposal. Because domestic refuse consists of a wide range of materials, the cheaper alternative is to pretreat the refuse and then burn it in a smaller boiler. At the Great Coates Works of Courtaulds Ltd., in Grimsby, domestic waste and coal are used to feed two chain grate stokers, firing boilers which are each rated at 20,000kW, raising 70,000lb/hour of steam. They are normally coal fired, but have been adapted so that they can operate on a mixture of coal and shredded refuse. Pulverised and screened waste is supplied to Courtaulds by Humberside County Council. The prepared waste is blown into the combustion space of the boilers, where it burns principally in suspension with a proportion landing on the moving grate where combustion is completed. The project has been supported by EEDS and has been monitored for two years to determine its effectiveness as an energy saving measure. Up to 30% of the coal can be replaced by refuse without seriously affecting the combustion efficiency. Such a system could prove attractive to sites where large coal fired boilers are already installed and where cooperation with the Local Authority can be established. For smaller boilers, there are also advantages in making a preformed fuel out of domestic waste before it is burned. Refuse derived fuel (rdf), as it is known, is made up of hard pellets of compressed waste with a calorific value of around 60% of that of coal and with an ash content of around 15%. The pellets are made by shredding, sorting, compacting and then drying the refuse before pelletising it. Two EEDS projects aim to show that rdf is a cost-effective alternative method of waste disposal where direct landfill is not available, or where refuse disposal costs exceed around £10 per tonne. Merseyside County Council has set up a company, Merseyside Waste Derived Fuel, to manufacture rdf from the shredded waste output of its pulveriser plant at Huyton. The total output of this plant will be sold to Associated Heat Services Ltd, who will burn the fuel in a multi-fuel fluidised bed boiler plant. These projects represent an important step forward in waste utilisation technology and are being carefully watched by other Local Authorities who have problems with waste

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disposal. Already the West Midlands County Council is installing similar equipment at its Castle Bromwich incinerator site. Commercial and Industrial Waste Unlike domestic refuse, much of the waste produced from commercial and industrial activities is easier to segregate and use as a fuel. In addition there is normally a demand for heat (either process or plant heating) close to the place where the waste is produced. There are several technical options available and the most appropriate one for a particular site will depend on the amount of waste being produced, the heat demand and the type of boiler plant already installed. Broadly speaking there are two main approaches. The material can either be burned directly in an incinerator plant (which, because the waste can be preselected, will be simpler and cheaper than the incinerator used for domestic waste and so can be operated economically at a smaller scale), or it can be shredded and burned with or without coal in a boiler. To demonstrate the economics of burning the waste directly, Freemans (London) Ltd, a mail order company, have installed an incinerator at their Peterborough factory. This has been running since 1982 and results from the monitoring are now available. Basically the system consists of a starved air incinerator which is producing 1800kW as hot water for space heating; consuming 16 tonnes of waste packaging material each week. The waste is fed to a primary combustion chamber with a limited air supply so that it pyrolises and produces combustible gases. These are then taken to a secondary chamber where sufficient air is introduced to complete the combustion. Energy savings of about 270tonnes coal equivalent (tce) have been achieved, giving a payback time of around four years on a capital investment of £143,000. If the quantity of waste and the heat load were more closely matched, a payback of three years should be realistic. This shows that the economics of waste combustion are dependent on matching the size of the system to the size and nature of the demand. In another EEDS project, a retail store in Leeds city centre is being heated by the combustion of shredded waste. Schofields (Yorkshire) Ltd generates some 12–13 tonnes of general commercial waste each week. A waste fired boiler rated at 1220kW has been installed which has a fixed bed above which the fuel is sprinkler fed. The design has a large furnace volume which appears to be highly suitable for waste burning and also incorporates auxiliary gas burners to allow total firing by gas if necessary. The reduced energy use achieved with this system is expected to save Schofields around £24,000 per year. Taking into account lower electrical and disposal costs adds further savings of £15,000 per year. With an investment cost of £130,899 for the system this should give Schofields a payback period of 3.3 years. Some industrial waste is peculiar to an industry. A demonstration project with a company that remoulds tyres fits into this category. At Colway Tyres Ltd., over 750,000 scrap tyres have to be disposed of each year. For many years this has presented the company with a major problem, costing them something like £65,000/year. They have now installed a shredder and controlled air incinerator which consumes about 24 tonnes of tyres esch week. The primary chamber of the incinerator rotates slowly to ensure complete combustion of the fuel, while the secondary chamber remains static. The exhaust gases are scrubbed of sulphur dioxide, to prevent the possibility of acid pollution.

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The waste heat boiler has an output of 1230kW and provides the total requirement for process steam, space heating and domestic hot water at the factory. Colway Tyres expects to save about £88,000 per year in fuel costs which, when added to the savings in the cost of disposal, give the company a payback time of just under two years for its investment of £269,053. Farm Waste Every autumn, UK farmers are criticised for burning straw in the fields after harvesting. It is a simple and quick means of disposal which clears the land and provides a fertilizer for the following year’s crops. However, it is a nuisance which produces many complaints. Approximately 13.5 million tonnes of straw are produced at present each year in the UK. of this, about half is used as animal food and bedding and the rest is either burnt in the field or ploughed in. By developing the appropriate technology, it should be possible to extend its use as an economic fuel. According to figures produced recently, straw could make a costeffective contribution of over 1.3 Mtce per year to the UK energy supply by 2000. Already many farmers have installed boilers that can burn straw for heating farm buildings. For them, it is costeffective, a convenient means of disposal and incurs no transport costs. Today, approximately 166,000 tonnes of straw are used mainly for farmhouse heating. By 2000, it is expected that farmers will be heating glasshouses, animal houses and crop drying units on a much larger scale and that 1 million tonnes of straw will be used annually in this way. Although straw would also appear to have considerable potential as a fuel away from the farm, there are certain limiting factors which have to be taken into account. It is bulky and expensive to transport and has a lower fuel content than conventional fuels which makes it uneconomic to transport far—at least in its original form. There are opportunities for using straw as a fuel in industry located in rural areas. Typical applications could include maltings, distilleries, sugar beet processors, mineral processing industries etc. It has been estimated that a maximum of 4 million tonnes of straw could be used annually in boilers and a further 0.4 million tonnes used in furnaces. Some 0.3 million tonnes of this might be realised by 2000. EEDS is supporting a demonstration project in a chalk drying plant operated by Needham Chalks Ltd in Suffolk. A 7300kW (25 million Btu/hour) cyclone furnace which will be fired by straw is being installed at the plant. This will be the largest straw-fired combustor in the world and is eight times larger than anything built to date in the UK for this fuel.

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7.3MW straw burning cyclone furnace at Needham Chalks Ltd, Suffolk Straw might be used more widely as an industrial fuel if it is compacted. Various methods of making straw briquettes have been explored but none have yet been produced at a competitive price. Within the Departments Biofuels Programme R & D studies have been initiated which aim to reduce the manufacturing costs of briquettes and so make them attractive as an industrial fuel. 3. ANAEROBIC DIGESTION Anaerobic digestion is the process by which methane and other gases are produced when an organic waste product decays via bacterial action in the absence of oxygen. Anaerobic digestion has been identified as the most promising method of producing fuel from wastes with a moisture content of greater than 50%. The technique is already being used successfully in the treatment of domestic sewage and most sewage disposal plants are now equipped with anaerobic digesters which provide energy for use on-site. of the other possible applications, the closest to realisation concern landfill gas extraction and the treatment of industrial effluents. Landfill At present, about 90% of domestic, commercial and industrial waste goes to landfill. Whatever new methods of disposal are developed, this technique will continue to remain popular so long as suitable sites are available. Anaerobic digestion occurs spontaneously in landfill sites under certain conditions. Parameters such as the availability of oxygen, water content and density of the refuse affect landfill gas production. If conditions are suitaable, sites become what is termed ‘biologically active’ producing large volumes of methane gas. A study carried out in 1981 identified the 20–25 largest sites in the UK where landfill gas extraction schemes could be installed most effectively. Early work on landfill gas was carried out in R & D trials at the London Brick Company’s premises at Stewartby. Here gas extracted from an adjacent landfill site was piped to fire brick kilns. Following on from this, there is now an EEDS project at the Thames Board Ltd works at Purfleet in Essex. Gas generated in a landfill site at Aveley is piped underground two and a half miles to the Thames Board works and then used as a base fuel on a 57,000kW (200,000 lb/hour) steam-raising boiler. Initially one burner out of four was converted but this has proved so successful that the company has changed over another burner. The total cost of the demonstration was £243,000 and the energy savings in the first full operational year were 14, 760 tce, representing a payback period of less than two years. Energy savings are likely to increase to 37,000 tce in succeeding years, making this project highly successful. More R & D is still needed to determine the best methods of extracting gas and to overcome other technical problems. Although it is theoretically possible to produce 400m3 of gas for every tonne of refuse, yields of only 10–60m3/tonne over a 10-year life have so far been obtained. In the longer term, it may be possible to increase gas yields to

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100m3/tonne or more by optimising and conserving landfill gas production in new sites. New types of wells improved abstraction apparatus, methods of biologically activating sites, and techniques such as capping with polythene sheeting to minimise gas loss are being studied. Much of the R & D work is being carried out by London Brick Landfill Ltd in conjunction with the Harwell Waste Unit. Industrial Effluent Some liquid effluents produced from industrial processes are suitable for anaerobic digestion. They are most common in the food and drink sector where large and fairly consistent streams of hot and easily degradable liquids are produced. There are estimated to be about 120 sites in the UK producing effluent of this type. Studies have shown that industrial digesters with a volume of 2,000m3 and above could produce sufficient biogas to be viable at current energy prices. A demonstration project at South Caernarvon Creameries (SCC) near Pwllheli is expected to save 570 tce annually using this process. A total of 20,000–22,000m3 of whey are produced each year as a byproduct of the factory. A 2,400m3 high-rate Hamworthy digester has been installed to digest the whey anaerobically and this is expected to produce 775,000m3 of biogas each year. The plant also reduces substantially SCC’s disposal costs. The cost of the plant is around £400,000 and the payback period is expected to be around six years. 4. LESSONS FROM WASTE-AS-FUEL DEMONSTRATION PROJECTS Although many of the above projects have not yet been fully monitored a number of lessons are already emerging of how technical and economic success is to be assured. Firstly, it is important that the potential user has detailed information about the quantity and quality of waste arisings. It is important to weigh the refuse rather than estimate the volume of arisings. Its average calorific value should also be accurately known. Likely incombustibles should be assessed for type, size and concentration. Secondly, the plant should be matched carefully with the likely load. It should be sized to meet the base energy waste rather than to dispose of peak waste arisings; if necessary surpluses of waste should be disposed of by an alternative method. In industry, process heat applications have higher annual load factors than space heating, and therefore have shorter payback times. Similarly, continuous or double shift operations yield better economics than single shift 5-day per week operations. Thirdly, the importance of detailed contractual specifications cannot be overstressed. The fuel properties (size range, calorific value, moisture content etc) must be spelt out in as much detail as the plant specification. It is also important to delineate responsibilities between the various bodies concerned; a turnkey contractor having overall system responsibility is to be recommended.

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HINTS TO WASTE-AS-FUEL USERS: TABLE 4 1. Verify the quantity and quality of waste arisings 2. Match energy supply with energy demand. 3. Specify fuel characteristics and system responsibility in the plant supply contract.

The waste as fuel demonstration programme has also resulted in considerable feedback indicating where further R & D is required to increase the scope for using the resource. On the combustion side it is clear that more work is needed to verify the fuel properties of refuse derived fuels, especially with regard to the emission of effluents from chimney stacks, ash slagging and fouling of boiler tubes. With landfill gas the main need is to improve our understanding of the basic microbiology of the process, and to develop practical ways of improving the yields, duration and controllability of gas production, especially on smaller, drier sites. Our overall conclusion is that the use of wastes as fuel is one area in which biofuels can have an immediate, significant and economic impact in supplementing fossil fuel supplies in the UK, and that there is a good case for continued R, D & D to increase the scope for using this resource.

THE SOUTHERN US BIOMASS ENERGY PROGRAMS WITH EMPHASIS ON FLORIDA W.H.SMITH Center for Biomass Energy Systems University of Florida—IFAS Summary The Southern US is a warm humid region with abundant underutilized lands and waters. Much is forested with hardwoods with limited market potential. This “Sun Belt” region is rapidly growing in population and increasing its energy consumption. Plant growth is rapid in the terrestrial and aquatic sites in the region; thus, it is well-suited for biomass production. Abundant forest and agricultural residues exist in the region and several energy crops appear promising. Conversion technologies are also being advanced in order to economically produce useful biofuels from the available feedstock. Progress in this region has been possible largely because of significant biomass program development by various federal agencies and land-grant universities in the South.

1. INTRODUCTION The Southern US east of mid-Texas possesses a warm, humid climate with long growing seasons; considerable underutilized land and freshwater resources; and substantial marine coasts. These factors favor biomass production and create a substantial bioenergy potential. In this humid portion of the “Sun Belt” region, conditions also favor growth in the human population and energy demand. Thus, several biomass programs have emerged to explore biomass production and conversion to meet the need for alternatives in the future energy mix. The deliberate production of energy crops has not been a commodity objective in agriculture since the era of producing feed energy for draft animals. Forest and agricultural wastes and residues (including animal manures) have the potential for meeting certain on and off-farm energy needs, but, because of restraints on convertibility, seasonal availability, and unpredictability of supply, supplements with biomass from energy crops will be needed to sustain a biofuels industry. Present domestic crops in the US were developed over the past centuries to meet criteria important to food/feed/fiber crops. Thus, they cannot be expected to be desirable energy crops for energetic and economic reasons. Many domestic crops in the US are easily overproduced; thus, there is a need for new crops in demand and growable at a profit. Conversion technologies now available simiarly are not compatible with requirements of a bioenergy industry because they were mainly developed for the spirits and industrial chemicals

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industries and/or for waster disposal. That these technologies do not prove economical for energy production should not be a surprise. Several failures could be cited where attempts have been made to commercialize these inadequate conversion technologies. Most of the agricultural and forestry research including that pertaining to biomass is conducted at federal laboratories or at the state experiment stations located at land-grant universities. These universities have ties to the US Department of Agriculture through formula funding and special grant projects. State support either matches or exceeds the federal contribution. For example, in Florida federal formula support represents 16 percent of the state’s research budget. Extra-mural support for research at the principal research performing institutions supplements in-house funds. 2. STATE EXPERIMENT STATIONS Since 1980, about 95 biomass research projects have been initiated at the experiment stations in the Southern US. of these, 31 have dealt with biomass production while the remaining 54 have focused on conversion processes or utilizaton options. of the 27 projects continuing past 1984, 16 are targeting conversion goals. Among the states, Florida has reported a total of 35 projects and Texas, 10 from 1980 to present. Other states reported fewer projects with only one state reporting no biomass research activity. The Texas and Florida programs will be discussed later in this paper. Several projects at land-grant universities also contribute to the programs described subsequently. 3. OAK RIDGE NATIONAL LABORATORY (ORNL) This agency manages a number of US Department of Energy (DOE) biomass programs. These total about $5 million annually. Nationally, the Short Rotation Woody Crops Program includes 24 projects—9 in the Southern US. Four of the 9 projects evaluating the effects of whole tree harvesting on site quality are in the Southern US. Among the 7 Herbaceous Energy Crops Program Projects, 2 are in this region. In addition, ORNL manages a winter rape project at USDA, Tifton, Georgia. In total, 16 projects have been conducted in the Southern US since 1978 in these programs. Presently, they are focused on genetically improving productivity, testing operational crop trials with industry and evaluating nutrient demands on soils producing energy crops on or from which biomass energy has been harvested. Most of these projects have been conducted by land-grant universities and the forest products industry. Species showing the most promise and now receiving interest include eucalptus, slash pine, sycamore, sweetgum, cottonwood, black locust, sorghum, and winter rape. Economic evaluations of some species are nearing completion but increased use of tissue culture technologies are allowing expanded, more rapid progress on species improvement in productivity and site stress tolerance. Regional differences in nutrient removals and regrowth were determined between conventional and whole-tree harvests. The herbaceous program recently initiated has selected lignocellulosic grasses/legumes annuals or perennials showing adaptability to marginal lands.

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4. U.S. DEPARTMENT OF AGRICULTURE (USDA) Agricultural Research Service: This agency manages the Southern Agricultural Energy Center (SAEC), Tifton, Georgia, established for research on the on-farm collection, storage and utilization of solar and wind energy and for the production, harvesting, processing/converting and utilization of biomass energy. This encompasses both crop residues and biomass which may be produced specifically for energy. The biomass programs of the SAEC receive primary funding from USDA, with supplemental funding from the DOE. Research programs are conducted at SAEC with satellite locations at Bushland, Texas and Ames, Iowa for wind energy research, and at Columbia, Missouri for research on anaerobic digestion of manure for methane. Partial funding was supplied for three years to Belle Glade, Florida for research on utilization of the biomass residue from sugarcane. At the peak of activity there were 65 projects, in addition to those at Tifton and the satellite locations, conducting research on renewable energy. Due primarily to the current excess supply of oil, the interest in and support for renewable energy has diminished. Today there are only 16 projects, plus those at Tifton and the three satellite locations making up the research program. Last year, new funding was received from ORNL for vegetable oil/diesel fuel research. The goal is to develop methods and processes which will maximize the use of renewable energy for the production of food. Research is being conducted on the harvesting, storing, processing and utilization of crop residues, animal manure, and herbaceous crops produced for energy and wood. The processes of conversion/utilization being studied include direct combustion, gasification and pyrolysis, anaerobic digestion, small scale alcohol production and extraction of vegetable oils (peanuts and rapeseed) for diesel fuel substitutes. Forest Service: The Forest Service has both the Southern (west South) and Southeastern Experiment Stations. Much of their research addresses biomass inventory, residue harvesting, handling and utilization schemes for woody biomass. In the Southeastern Station a major biomass inventory has been conducted by the Forest Inventory and Analysis Group. From their survey network state-by-state biomass inventories are emerging in Forest Resource reports. Other biomass for energy research has focused on developing ways of measuring economic potential for using biomass, especially the residual from harvesting other timber products. They have developed the Total Biomass Cruise Program (TBCP), a computer-based program that uses conventional cruise data to provide simultaneous estimates of wood product weights and volumes as well as the total stand biomass. The TBCP is now being used by both Forest Service stations, the National Forests and by forest industries in the Southern US. In addition, the Southeastern Station has examined cost-effective shipping distances for wood fuel and developed a simulation model, Wood Residue Distribution Simulator (WORDS), to derive least-cost allocations of wood fuels from supply sources to demand points. Under investigation, also, is the impact of biomass capture on the potential for nutrient depletion and ways to reduce wood moisture for improving burning efficiencies and energy yield. To date, nutrient depletion is not markedly affected and transpirational drying possesses potential for increasing energy recovery. The Southern Station projects mostly indirectly relate to biomass energy objectives. Results from projects in this Station could benefit intensive culture techniques, prediction of biomass yield, harvesting and utilization.

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5. TENNESSEE VALLEY AUTHORITY (TVA) TVA Biomass Fuels Program is designed to develop information through research to assist industry in commercializing renewable energy resources. The TVA program managed by its Office of Agricultural and Chemical Development in Muscle Shoals, Alabama has several integrated facets designed primarily for Valley conditions; however, the technologies and concepts have national and international applications and implications. The program emphasizes use of the Tennessee Valley hardwood resource because of its abundance and current underutilization. Over 50 percent of the 23.6×106 ha of land in the Valley is forested, and 80 percent of the forests is hardwoods. Foresters are updating the total support for these programs which is about $6.4 million annually. Production of alcohol from hardwood, which includes greater utiliztion of all cellulosic components, is being studied in TVA laboratories. This involves two-stage hydrolysis of wood with short hydrolysis retention times, explosive release to physically disrupt the wood, and use of dilute acid to form solutions of predominantly five-carbon and sixcarbon sugars, respectively, from the two stages. These sugars are available then for fermentation to ethanol. Design work is in progress, and equipment for a 0.9 Mg day−1 pilot-plant facility is being purchased at this time. DOE funded research at Purdue University on the conversion of agricultural residues (such as corn stover and wheat straw) to ethanol by a concentrated acid hydrolysis process using low temperatures and pressures was encouraging. Communications between DOE, Purdue University and TVA resulted in the design of an experimental facility as a front-end modification of the existing 37.8 ℓ hr−1 ethanol unit built by TVA in an earlier DOE sponsored program to obtain benchmark data on grains and alternative starch and sugar crops. Acid hydrolysis equipment to process 3.2 Mg day−1 of non-woody biomass is installed and shakedown tests are being conducted. TVA also provides technical monitoring assistance for the DOE loan guarantee program. DOE will guarantee loans for construction of privately owned plants to produce. ethanol from corn or molasses. Plant sizes range from 57 to 227×106ℓ yr−1. DOE incurs a liability only if the firms default on the loans; hence, technical assistance has been requested to ensure that the plants are properly constructed and effectively operated. The New Energy plant at South Bend, Indiana, is nearing completion; it is a 189×10θℓ yr facility. Tennol, Inc., has completed final preconstruction, requirements with DOE and is beginning construction of its 94×106 ℓ yr−1 plant. The Southeastern Region Biomass Energy Program (SERBP) was established by DOE to promote effective use of regional biomass resources to meet regional energy needs. The focus is on information development/transfer and technoloy transfer for a broad range of biomass resources, conversion technologies, and end uses. Much of the effort in the 13 Southeastern States is carried out under competitive contracts selected with the assistance of key representatives of industry, academia, and government. TVA has another agreement with DOE to conduct activities to develop/improve technology for harvesting wood for energy. The focus is on equipment for harvesting short—rotation intensive tree crops and other small diameter energy wood (such as from rights of way and tree crowns from traditional forest harvest operations). This is a new project in cooperation with ORNL’s Short Rotation Woody Crops Program.

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6. TEXAS A & M UNIVERSITY The program at this site includes various projects. One is directed toward fluidized bed gasification and cyclonic burner development. These were designed to primarily use cotton gin trash and similar agricultural residues for fuel. Gas clean-up has proven critical because of the corrosive properties of the ash upon the metal at high temperatures. Other projects have evaluated plant oils and animal fats as diesel fuel substitutes. Engine tests have shown that fully esterified cottonseed oils provide the best alternative fuel followed by beef tallow and alkali refined cottonseed oil. Longer termed tests with more complex engines are in progress. Grain sorghum has been investigated as feedstock for ethanol. Research on grain treatment chemicals showed that some did not affect ethanol fermentations. Certain chemicals were destroyed in the process while others appeared in the stillage in levels of concern. Disposal problems associated with stillage have been investigated using recycling and nutrient recovery procedures. Sweet sorghum processing in preparation for ethanol fermentation has shown that fermenting chopped stalks yielded more ethanol than shredded sorghum or juice. In 1983, Texas A & M initiated a cofunded program with the Gas Research Institute (GRI) to research sorghums for methane. This is a multidisciplinary research program to establish the technical and economic feasibility of producing pipeline quality methane from sorghum. The overall objective is to develop an integrated system for methane production utilizing sorghum as the feedstock. Research emphasizes genetic manipulation, crop physiology and production systems, harvesting, storage, processing and conversion systems and economic and system analyses. First year results indicate that the proposed methane from sorghum system is in the realm of economic feasibility; storage and high-efficiency conversion are critical to the economics; and the system economics is improved if the grain and vegetative materials are harvested for separate purposes—food and energy. While crop management and genetic improvement for methane production research are in their early stages, results indicate that sorghum yields up to about 35Mg ha−1 are possible with sweet sorghums. In these, the yield is mainly vegetative. In the high-energy sorghums, yields ranged between 16 and 26 Mg ha−1 with 45–51 percent of the yield as grain. Genetic manipulation of both lodging and chemical composition of the vegetative portion shows promise for improving the sorghum as a feedstock for methane. 7. UNIVERSITY OF FLORIDA-- IFAS In 1979 the Florida Legislature funded a low energy technology research program in the Institute of Food and Agricultural Sciences (IFAS), University of Florida. A substantial portion of the $6.4 million appropriated for the 1979–81 biennium was directed to alternative energy, mainly biomass. After redirection guidelines were met, the annual statewide biomass program was about $3.0 million. Subsequently, funding from other agencies (e.g., GRI, DOE etc.) brought the annual effort to about $6.0 million. The program was reduced in response to revenue shortfalls and now stands at about $4.5 million annually with the major portion contributing to the joint GRI program. Current research is conducted by about 50 faculty located throughout 13 academic departments

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on the Gainesville campus and 13 research centers dispersed throughout the state. The projects can be grouped into five major areas of investigation. Wastes and Residues: Projects in this area have focused on the inventory and capture of various wastes and residues. Major resources include wood (non-merchantable residual trees, tree parts not harvested, and mill processing wastes), sugarcane bagasse, vegetable culls, field crop residues and animal manures. Wastewood and bagasse appear to be the only feedstocks reliably available in adequate quantities. Unfortunately, the demand is for liquid and gaseous fuels, and wastewood and bagasse presently cannot be economically converted to these energy forms. Energy Crop Development: A large effort is underway to identify plants that have potential as biomass crops. Over 150 species (350 cultivars and varieties) have been field tested for their suitability as energy crops. Three species (water hyacinth, Eichhornia crassipes; Napiergrass, Pennisetum purpureum; and sorghum, Sorghum biocolor) have been chosen for intensive evaluation in the GRI/IFAS program. Annually, water hyacinth yields near 75Mg ha and Napiergrass more than 50Mg ha with low production inputs. Other promising species are being identified in the systematic process for further development as energy crops. This process involves conventional cultural and genetic improvement practices as well as advanced biotechnologies such as tissue culture and somatic hybridization by protoplast fusion. Plants of both Napiergrass and sweetpotato have been produced from somatic embryos. Gel-seeding of these plantlets appears promising. Thermochemical Gasification: The thrust has been on small-scale gasifiers to meet onfarm and other distributed energy needs (about 112KW or less). Project activities have focused on wood fuel improvement, fuel feeding, gasifier design, gas clean-up, microprocessor controls, supercharging in engine applications and gas utilization applications—commodity drying, space heating, electrical generation, pump engine powering etc. Alcohol Production: Research projects in this area have three thrusts: technology for small-scale alcohol production, physical/chemical treatments to hydrolyze lignocellulosics into fermentables, and genetic engineering of microorganisms to improve the efficiency of the alcohol fermentation process. Research on small-scale operations optimized feedstocks, enzymes, and physical controls to manage the rate of alcohol production and produce beer with high alcohol concentrations. A gasifier was designed and adapted to provide the necessary heating to make small-scale units independent of fossil fuels. Hydrolysis of lignocellulosics has been accomplished by a novel acid hydrolysis process using of the acid anhydride sulfur trioxide. NASA has assisted in designing a laboratory pilot plant, which they subsequently fabricated and sited in the IFAS Bioconversion Laboratory. Licensees for the patented process assigned to the University of Florida are being sought. IFAS research is attempting to genetically engineer organizms that can tolerate higher temperatures, osmolarity and alcohol concentrations. Unconventional organisms (e.g., Zymomonas) for alcohol production are being researched to improve fermentation efficiency. Other work is designed to manipulate the organism in a way that substrate range is increased (e.g., ferment lactose as well as glucose). Transfer of important genes that control alcohol fermentation to E. coli (the best understood microorganism known) is being attempted.

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Methane Production: For anerobic digestion, one approach is off-the-shelf equipment for designing a low-cost system adaptable to low-solids waste streams that are typical of Florida animal confinements. Wood chips have been experimentally compared to several plastic media with different geometries as packing for fixed bed digesters. Wood chips cost about one-tenth as much as plastic media. The second strategy in concert with GRI is to design innovative digestion systems that will accommodate various highly productive biomass crops in the generation of pipeline quality methane. The process for this development activity involves: (a) bioassay plant and plant parts for chemical properties relating to methane production; (b) improve microbial inocula; (c) develop ways to control the rates of the hydrolytic, volatile acid, and methanogenic processes; and (d) design low-cost, efficient digesters. Biotechnologies are exploited in improving the quality of the plant for methanogenesis, accelerating biological hydrolysis with cellulase enzymes, and improving the rate and efficiencies of the microorganisms active in volatiee acid conversions to methane. A recent development is the initiation of research with a new digester design that is multiphase in function and potentially capable of using multiple feedstocks. The GRI/IFAS program is presented in 3 other papers in this set. ACKNOWLEDGEMENTS Information was provided by Dr. Robert Van Hook, ORNL, Oak Ridge, TN 37831; Dr. James Butler, USDA, SAEC, Tifton, GA 31794; Dr. Eldon Ross, USDA, Forest Service-Southeastern Station, Ashville, NC 28804; Dr. Thomas Ellis, USDA, Forest Service-Southern Station, New Orleans, LA 70113; Dr. Joe Roetheli, TVA, Muscle Shoals, AL 35660; and Dr. Edward Hiler, Texas A & M University, College Station, TX 77843. Details on these programs are available from these sources.

BIOMASS ENERGY UTILIZATION AND ITS TECHNOLOGIES IN CHINA RURAL AREAS W.WU Research Professor and Chairman of Scientific Council of Guangzhou Institute of Energy Conversion Chinese Academy of Sciences Summary The energy situation in China rural area is first descri“bed with biomass energy as the major supply source. Various biomass supply sources (straws & stalks, firewoods, animal manures, industrial wastes) and their respective quantities are then related. Different utilization methods, such as traditional and improved cookstoves, “biogas, gasification and ethanol, employed now in China countryside, are discussed separately. Finally the trends of development of various biomass energies and their relavant technologies are presented.

1. BIOMASS ENERGY AS A MAJOR RURAL ENERGY SUPPLY A survey in 1979 of 28 provinces and cities showed that the “biomass energy contributed 68.6% of the total energy supply in China’s rural area (1). The details of the energy supply are listed as in table 1.

Table 1. Rural Energy Consumption in 1979 Item

Energy

1 2 3 4

Biomass Coal Electricity Diesel, gasoline & kerosine Total

Consumption Quantity % 2.25×108 TCE 68.60 0.572×108 TCE 17.45 0.314×108 TCE 9–57 0.144×108 TCE 4.38 3.28×108 TCE 100.00

Even though the total amount of energy consumption of 3.28×108 TCE is large, but the average individual energy consumption is rather low, which is 7791 kcal/cap.-day on account of rural population of 8.074×108 in 1979. The household portion of the total energy consumption 3.28×108 TCE is 79.7% while the portion for agriculture production is 20.3%.

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2. BIOMASS ENERGY RESOURCES AND THEIR POTENTIALS The amount of Biomass Energy supply of 2.25×108 TCE of table 1 consists of the following components as showing in table 2. (2)

Table 2. Biomass Energy Components & Their Quantities in 1979 Item

Energy

1 Straws & Stalks Firewoods 3 Human & Animal Manures Total

Quantity

%

Remarks

1.14×108TCE 50.44 The total production amount is 1.84×108 TCE 1.04×108TGE 46.43 Nearly double the quantity of rational havesting 0.07×108 3.13 Only a few percent of the total production TCE quantity 2.25×108 100.00 TCE

It can be seen from Table 2 that: (1) The cropwastes used as an energy source is about 62% of its total production, 3.78×108tonnes in 1979. However, the cropwastes, besides being used as an energy supply, are also being used as fodders and raw materials for chemical and other industries. Therefore, the potential of getting more cropwastes as energy source is very small. (2) The consumption of firewood in 1979 as an energy source is nearly two times the amount of rational and legal havesting. Hence the potential of getting more firewoods as rural energy supply is not existing. On the contrary, the supply of firewood as rural fuel will be diminished in the coming few years. (3) The supply of human and animal manures in 1979 as rural energy source is only 4% of its annual production, 2.61×108 tonnes. Hence there is ample ground in getting more supply of this kind of biomass as an energy source in China countryside, especially in utilizing the animal manure to yield both the biogas and the fertilizer via anaerobic digestion. It has been estimated that the biomass supply potential in 1983 was 3.074×108TCE and was 37% more than the quantity of biomass consumption of 2.25×108TCE in 1979. However, to realize this potential of energy supply for the peasants will rely on the full utilization of the human and animal manures by anaerobic digestion. 3. UTILIZATION METHODS OF BIOMASS IN CHINA RURAL AREAS Now in China rural areas, the biomasses are utilized as energy sources in four different ways, namely: (1) direct burning (2) biogas (3) gasification (4) ethanol 3.1 Direct Burning—The most common method being used by Chinese peasants is to burn the cropwastes, firewoods and dry animal manures by traditional stoves, either the

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small porta-ble type or the large stationary type. However, a rigorous test had shown that (4) the thermal efficiencies of those traditional stoves are low, as shown in Table 3.

Table 3. Thermal Efficiencies of Traditional Cookstoves Type of stoves

Material burned Thermal efficiencies

1. Cropwaste stove corn stalks 2. Firewood stove firewood 3. Firewood stove with forced ventilation firewood 4. Biogas stove biogas

8–14% 15% 19–21% 50–61%

The reasons of the low efficiencies are due to: (a) too large inlet opening and combustion chamber (b) no fire grate and chimney (c) poor heat insulation 3.2 Biogas --Before 1979, about million biogas digesters had been built in China’s rural areas. But about 40% of those digesters are not operated normally because of ill construction at the early stage and poor maintenance at later dates. The total biogas yield of those operating digesters was around 7×108M3 annually (1). Nearly all the digesters built before 1979 were of water pressure design which has high gas pressure of 200–800m/m H2O column within the top of the digester and the pipelines. This high gas pressure causes gas leakage in the gas system. Generally, a 6–8M3 digester of family size can supply 1.2–1.5M3 of biogas daily; this amount of biogas will suffice to meet the energy requirement of a five person family -- 3 meals and 2 hours of lighting with biogas lamp. Feedstocks for biogas fermentation are abundant in China ‘s rural areas. They can be divided into two groups: (1) Carbon-rich group--such as cropwastes, grasses and forest leaves (2) Nitrogen-rich group--such as human and animal manures. The favourable C/N ratio for good fermentation performance of these two groups is 25/1 to 30/1. The total cost to build a family size digester is between 200–300 Chinese yuan (1980; 1 U.S. dollar=2.8 yuan). 3.3 Gasification --This is another way to utilize the biomass in the countryside but of small number. One merit of this method is that it can provide gaseous fuel for the transportation vehicles and other internal combustion engines. Even though the wood and charcoal gasifier had been used in trucks and buses as early as around 1930 in China, the revival of interest to this kind of equipment for rural use is only a decade or so and of small quantity of application also. Both updrift and downdrift design of various sizes had been constructed, tested and used recently. One gasifier designed in burning the rice husk had been built in a rice processing factory to generate electricity with an output of 120 kW. This generating set

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consumed 2kgs of rice husk for every kW-HR of electricity. The size and thermal efficiency of the gasifies were 6.8M3 and 61% respectively. (5) It seems that in the areas which are rich in forest wastes or other biomasses not suitable for microbial digestion, the gasification method will be in a competitive position to be adapted, especially in occasions which the need of gaseous fuel is essential. 3.4 Ethanol (alcohol) —This fuel is good both for cooking and for engines in the rural areas. However, the market price of alcohol is about 1,000 Chinese dollars per tonne, which is a little higher than that of gasoline. This prevents the ethanol to be used as an energy supply for Chinese peasants. China now produces about 700,000 tonnes of ethanol annually, mostly by fermentation method and a few percent by synthetic method. The fermentation materials consist of both sugar base and starch base. It is estimated that the production potential of biomasses in China’s rural areas is 2–3 times the quantity of the present ethanol production. There exists large resources of biomass of cellulase nature, such as forest wastes and timber processing residues, which can produce ethanol by the combination of hydrolysis and microbial fermentation. A factory of this nature produces 2760 tonnes of ethanol in 1980 together with the yielding of 378 tonnes of fodder enzyme and 119 tonnes of activated charcoal at the same time. (6) 4. TRENDS IN DEVELOPMENT AND UTILIZATION OF BIOMASS ENERGIES Two programmes are now being taken in the aim to ease the energy shortage problem in China’s rural areas regarding the biomass energy, i.e. (1)To increase the utilization efficiencies of the biomass utilization equipments and processings by improvement of their technologies. (2)To increase the supply of various sources of biomass and the number of the utilization equipments units. 4.1 Improved cookstoves Two government organized fuel-saving stoves contest conventions have been held in 1981 and 1982 respectively. Durning the conventions, “Three Ten” criterions were used to judge the performance of the contested cookstoves—Ten catties(5kgs) of water to be boiled by burning Ten taels (0.5kg) or less of stalk or wood in less than Ten minutes. The thermal efficiencies (η) of 14 winning stoves out of 42 contested ones in 1982 were in the range of 25–44%, specifically: (7) 6 firewood stoves—wood burning η=36.2−43.9% 2 firewood stoves (portable)—wood η=31.2−38.6% burning 4 cropwaste stoves—stalk burning η=27.5−31.2% 2 cropwaste stoves—rice straw η=25.5−26.4% burning

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The thermal efficiencies of these improved stoves are much higher than those of traditional ones (η=8–15%). Generally, saving of 40–60% fuels can be realized by using these improved stoves. The government agencies had disseminated approved fuelsaving stoves around 7 million units in 1983 in 90 selected counties. To build an improved stove will cost 30–50 Chinese yuan and this amount of investment can be gained back within one year by saving 1,000kg of stalks. 4.2 Biogas Even though about 40% of the digesters being built before 1979 were not operative, but the digesters being built after 1979 were functioning normally with good percentage of 95%. From 1979 to 1983, nearly 3 million new units has been built with an average figure of 600,000 units per year. (8) Following ways are now being taken to encourage the peasants to utilize their biomass sources through the biogas technology: (1) To revive the defective built digesters with the adequate repairing and remodelling works. (2) To build new digester on self-financing basis with emphasizing peasant’s initiative. (3) To employ new technologies in increasing the biogas yielding rate or in easing the maintenance work, such as—dry fermantation; two stage fermentation; floating cover design; plastic bag storage etc. (4) To train local techniciens to ensure good management and maintenance. (5) To use new materials to prevent gas leakage and water seepage or to reduce the investment cost. (6) To enlarge the overall benefit by comprehensive utilization of the anaerobic digestion of the biomass—biogas, fertilizer, fish and earthworm breeding, mush-room planting etc, Biogas technology are now also being applied in big villages and towns to treat the industrial organic wastewaters. The treated wastewaters included: alcohol distillery waste,

slaughter house waste,

synthetic fatty acid waste,

gourmet powder waste,

furfural waste from sugar

paper black liquid.

factory,

4.3 Gasification and Ethanol No definite planning were formulated for both gasification and ethand production from biomass in rural areas. However, some research projects are undergoing in various institutions. New manufacturing processes are also implemented in some related factories. For example, a new process of continuous fermentation of fixed enzymatic cells had been employed in 1980, and the ethanol yielding rate reached a high level of 20.6 g/l·hr. (9)

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4.4 Firewoods Firewood come next only to the cropwastes as the energy source in China’s rural areas. It is important to enlarge its supply by increasing the forestry areas as well as the yield rate. From 1949 to 1981, we had planted 1.13×108 hectares of forests altogether. During 1976– 1980, the average annual afforestation area is 4.72×106 hectares, and the figure is 4.11×106 hectares for the year 1981. But the percentage of preservation to the newly planted young trees in well growing is low, only 31% before 1982. (10) In China, we have 7.79×107 hectares of arid and waste lands which are suitable for afforestation, in addition to the existing forest areas of 1.22×108 hectares. Each citizen is urged to plant 3–5 young trees every year and the armed force personnel are requested to plant 20 young trees in 1985. The aim has been set to harvest 85×108 tonnes/year by the firewood forest alone in 1990, and total harvesting of the firewoods from all kinds of forests being 1.8×108 tonnes/year in the same year (1). We have many shrubs and trees, the so called fast growing forests, which can grow in the dry, infertile land, and can be harested within 3–5 years. To screen the right species and to cultivate them in the unused lands is another urgent task to do to increase the biomass supply for Chinese peasants. 5. CONCLUSIONS 1. Biomass contributes the most energy, nearly 3/4 of the total, for China’s peasants. However, the biomass energy supply together with other sources of energy still can not meet the villager’s energy demand. 2. The major resources of biomass energy supply are stalks and straws, followed by firewoods then human and animal manures. In 1979, the percentages of each of them are 50.5%, 46.4% and 3.1% respectively. But the supply potentials of these sources are larger. 3. Various methods in utilizing the biomasses are now developing vigorously in China. These methods are: inproved stoves; biogas; ethanol and gasification. Certain progresses have been made in last few years of these methods, but further improvements and researches are needed. 4. Massive afforestation, especially the fast growing forests, dissemination of improved stoves and biogas are current effective measures in easing the demand—supply tense sui ta-tion in China’s rural areas. REFERENCES (1) National Exhibition of Rural Energy. Beijing, China. July, 1982 (2) Deng, Ke-yun.(1981). To probe ways and methods in solving the rural energy problem. New Energy Sources. March, 25–26 (3) Wu, W. (1984) Biomass Energy Utilization in China. Yang, F.G. (1981) Determination of Thermal Efficiencies of Rural Cookstoves. Energy Sources. March, 46–47. (4) Yang,F.G.(1981) Determination of Thermal Efficiencies of Rural Cookstoves. Energy Sources. March, 46–47.

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(5) Zhao, M. (1983) The Electricity Generation By Rice Husk Producer Gas. Energy Sources. January, 43 (6) Hu, X.Y. (1982) Anaerobic Digestion of Alcohol Dregs. Joint China—U.S. Biomass Conversion Technologies Symposium, Chengdu, China. (7) Anon. (1983) Selected Improved Stoves of Good Performances. Energy Sources. January, 42. (8) Bian, J. To Create A New Status of Biogas Developments. Economic Daily. May 25, 1984 (9) Chen, T.S. Review and Outlook of Research of China Brewery Since 1982. China Brewery. No.1 1–8. (10) China Agriculture Yearbook (1982). 324. (11) China Agriculture Yearbook (1981). 156.

SUMMARIES OF ROUND TABLES A. Research Needs and Resources for the Development of Biomass Energy B. Land Use, Food and Fuel Production C. Development and Environmental Issues D. Institutional Aspects of Biomass Production and Use

ROUND TABLES by D.O.Hall & J.Coombs Bio-Services King’s College, 68 Half Moon Lane, London, SE24 9JF, UK. A. Research needs and resources for the development of biomass energy Chairman: P.Chartier (France) Panel members: E.Teissier du Cros (France) H.Naveau (Belgium) K.Kocsis (FAO, Italy) The main consideration on furthering biomass for energy at present is on the price of the biofuel and how it competes,and in the future with competing fossil and nuclear fuels. These factors are determining the current support for biofuels and the R, D & D which will be undertaken in the future. A major point of discussion was whether further field trials are necessary to establish the yield potential and economic viability of short rotation forestry. These have been underway for over 10 years in various parts of the world and some people consider that this is sufficient to launch much larger demonstration and commercial projects. However, others thought that we still lack good yield data and harvesting technology especially on diverse sites and because the trials have been small the economic data is a poor base from which to make large scale capital investments. It was also thought that we have too little good data on multiple-use forestry which could make biomass fuel schemes more economically attractive. If we wished to take a longer term view of biomass energy, it is essential that we improve productivity through basic research on breeding and physiology and we improve the efficiency of conversion,whether it be thermochemical or biological. A detailed analysis of the European biogas installations, mostly using manure, has shown disappointment in the number of problems which have arisen primarily as a result of inexpert construction and maintenance. However, the situation is now improving with more established firms doing good work and the integration of energy production with pollution control. The need for widely accepted standards in all types of biomass conversion apparatus was stressed, especially since biomass is mainly a local fuel being used in numerous conversion “machines”. The necessity for R&D follow-up of apparatus for its improvement to ensure reliability, longevity and ease of operation,was repeatedly emphasised if biofuels were to be more widely accepted. The recently established European Network of Rural Energy Use attempts to provide collaboration on how applied research can help solve practical problems in biomass use. It acknowledges the diversity of expertise and experience available in Europe. Transferring such knowledge between regions is difficult and even more so to developing countries—although there are a number of regions in Europe which have levels of R, D & D close to those of many developing countries.

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The session concluded with a discussion on the recently announced Call for Tenders by the Commission of the European Communities’ Third Phase of Energy from Biomass R & D Programme. One part stresses field trials, improvement of productivity and improved harvesting techniques. The second part covers biological conversion to ethanol and some basic biological studies, plus thermochemical processes of conversion such as pyrolysis and gasification. B. Land use, food and fuel production Chairman: J.F.Molle (France) Panel Members: E.La Rovere (Brazil) H.Wohlmeyer (Austria) J.Zubr (Denmark) A number of studies have concluded that the Commission of the European Communities (10) will have about 10 M hectares of “spare” land by 1995 which will have been released from agriculture due to changing social and economic circumstances. The large EC and national subsidies for agriculture which now approach 30 billion ECU per annum in the EC (10) distort land use and production. Any changes in subsidies and land use will undoubtedly affect biomass energy opportunities, as will any changes in the subsidies in other energy industries such as coal and nuclear. Within a country, the import and export of fuels, food and animal feed must be considered jointly before biomass energy schemes can be implemented. Local conditions and requirements are preeminent in determining any biofuels policy. The Brazilian example was discussed in some detail since over 1.3M hectares of sugar plantations have been established there since 1976 to provide for the 11 billion litres of ethanol being produced now to run the 9 million cars. Much of this land has been converted to sugarcane from pastures but much food producing land (beans and maize) has also been converted. However, Brazil has simultaneously also greatly increased its food producing and cash crop (for export) producing areas, so that a simple competition between food and fuel is very difficult to discuss. There are moves in Brazil to encourage intercropping and rotation of food and fuel crops, and also to disperse sugar-alcohol projects (both large and small scale) throughout this vast country and not just to concentrate them in a few favourable regions. In Denmark an extensive 3-year trial on the optimum system for producing energy from biomass crops was discussed; 18 crops and various rotations within annual cycles have been studied to maximise the light-absorbing leaf area and thence productivity. The biomass is being used for biogas and ethanol production. The economics of such systems were discussed but it was agreed that insufficient data is yet available to make any longer term predictions as to their viability. A study in Austria has concluded that biomass energy production is feasible if it is combined with existing systems of agriculture such as the sugar and starch industries and foresty; starting with waste products then to byproducts and finally to energy crops themselves . It was stressed that the social and economic needs of the farmers and the population are being considered when trying to formulate a food, feed and fuel programme. The year-to-year financial requirements of farmers were repeatedly stressed

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as being most important in trying to implement any biomass energy schemes—whatever the regime of subsidies and long term alternative requirements. C. Development and Environmental Issues Chairman: B.Bini Smaghi (EC) The major issue is the wood crisis in the developing countries, which is linked to the depletion of the world’s forests and increasing desertification. Discussions related to the contributions made by the EC to development of alternative energy resources from biomass, and the mechanics for dissemination of information in Africa in particular. Concern was expressed by representatives from developing countries who felt that insufficient aid was given, that technology was often inappropriate and that the emphasis (through government) should perhaps be changed so that EC funds could go more directly to projects under control of universities and NGOs. (non-governmental organisation; The current contributions made through DGVIII of the EC are financed by the European Development Fund (EDF) in the African, Carribean and Pacific countries (ACP) through the Lome convention. However, such aid for biomass energy projects is relatively small and hence care is taken in choice of projects which are assessed on the basis of practical value and rational use of the available funds. In general the objective is to demonstrate the suitability of proven technology which may be adapted to local needs in order to avoid technical failure or socio-cultural rejection. At the same time steps are taken to involve local research and training bodies in order to achieve success. Typical projects have included development of a gasifier fuelled with coconut husks in the Ivory Coast, supply of mobile gasifier/ generators in Guyana, production of gas and charcoal in Mali, etc., as well as studies of biomass resources and agricultural wastes,and setting up of biogas projects. Such projects are assessed and monitored in order to establish the best means of replication of a given technology throughout a region following initial demonstration. The size of the programme was criticised from the audience. However, it was pointed out that the major effort of EDF was in food. Other critical remarks related to (i) the choice of technology (often large scale, e.g., dams, rather than aimed at meeting rural and environmental needs); (ii) funding of high profile projects; (iii) use of developing countries as a proving ground for untried technology; (iv) restricting technology transfer by patents and licences, and so on. It was suggested that the EC funding should be directed in such a way that countries can solve their own problems. However, the chairman pointed out that governments were asked for their input in the setting of strategies and may in future insist on specific fields of action in order to complement projects being funded by the World Bank and other aid agencies. Larger projects were favoured since it is easier and more cost effective to fund one or two large projects than several hundred small ones. The discussion in general highlighted problems of energy, environment and food which lay beyond possibilities of being solved by the financial aid and resources available. The magnitude of the problem are such that there is no answer but on the other hand on a local basis the input of a well funded project can be of significance, especially where this can be replicated through education and dissemination of information.

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D. Institutional aspects of biomass production and use Chairman: R.S.Dosik (World Bank) Panel Members: U.Miranda (EC) F.depoli (Italy) H.Quadflieg (France) Implementation of biomass energy programmes in both developed and developing countries depend on similar factors which are technical, political, social and economic. Much of previous R&D effort has centred on the technical aspects on the basis that oil prices would rise and fossil fuel supplies become significantly depleted. Hence, the emphasis was on oil substitution. However, the picture has now changed with the major problems facing Europe being ones of agricultural surpluses and the related problem of land use. Production of liquid fuels and/or octane enhancers from these surpluses could represent a short term answer. However, the fact that end use technology had been developed might not be a sufficient answer to the problems. This was already clear from results of large projects such as the Dendrothermal project in the Phillipines where lack of fuel wood trees had negated technically sound large scale electricity generation, Within the EC most countries had revised their energy laws, especially in relation to the sale of gas and electricity, during the last four or five years. This had led to numerous small scale generators based on biogas or direct combustion. However, these might not be economic in real terms unless other benefits were associated with them. Such benefits related in particular to pollution control, and as such depended on strict enforcement of relevant legislation. In the same way the emphasis on use of crop surpluses for production of fuel ethanol related to the need for an alternative octane booster once lead was removed from petrol at the end of this decade. Again ethanol was only one answer to a problem which could be solved by changes in the refining of oil to liquid fuels, by changes in car engines, or by changes in the oxygenate used. The move in any particular direction could be induced by institution of, or removal of tax in a particular sector, or by introduction of specific legislation. Such moves could upset economic logic. In general it was felt that the biomass programme in Europe, which had started as a response to energy shortages, was now justified in terms of energy efficiency, recycling of materials, use and avoidance of waste on the one hand, and regarded by some as the answer to problems of surpluses and the CAP by others. Many of the technical problems of enduse had now been solved. We were now in a position where both incentives and subsidies were needed if significant biomass energy programmes were to be implemented. Incentives were needed in order to establish an infrastructure to support economically sound energy programmes based on wastes and possibly short rotation forestry. At the same time financial inputs, in the form of tax relief or subsidies, were needed if agricultural products were to be used as a source of liquid fuels. This analysis of the situation was felt to contrast with the current EC policy which supports extension of the land area which is used for agriculture at the expense of natural vegetation and the destruction of forests. The technology for greater use of biomass is now available, what is needed is the removal of institutional restraints. However, in most European countries biomass would probably contribute only a few percent of total energy needs and hence the incentives are not perceived at a national level, although they may be significant on a local basis, or within a particular sector.

SUMMARIES OF WORKSHOPS I. Biomass Resources II. Biological Conversion III. Research Priorities in Thermal Conversion Technology IV. Densification and Combustion

WORKSHOPS I. Biomass Resources C.P.Mitchell, Aberdeen University, UK J.F.Molle, CEMARGREF, France The purpose of the workshop was, by discussion and verbal presentation of relevant poster papers, to identify critical areas for future R&D. An important constraint on development of biomass resources, particularly energy cropping, is the availability of suitable land. Rationalisation of the Common Agricultural Policy (CAP) in Europe will have the effect of releasing land from agricultural production for food. Studies of these effects indicate that by the mid 1990s some 5–10 million hectares of land would have come out of agriculture. Land released from cereal production will more than likely be used for high grade pasture and that the land for energy production will be on the medium to poor pasture lands. However, what is lacking from these analyses is information on the detailed nature and location of this land. Such information would be very useful in designing a research strategy to optimize use of the available land for growing energy crops. The type and production of energy crops is very closely tied to site quality and location. Conventional crops can be used as a source of energy. Ethanol can be produced from sugar beet and cereals. Much valuable research has been undertaken on the improvement of production of sugar beet. Yields of sugar beet have increased dramatically over the last 50 years but the sugar content has declined. It is anticipated, however, that with improvements gained from breeding, agronomy and better storage techniques the sugar yield can be increased from 9 to 10.7 percent during the 1990s. Agricultural residues represent a significant resource. Large quantities of cereal straw are generated each year within the Community, much of which has to be disposed of and which could be used as a source of energy. Where the potential market is some distance from the source then transport becomes a problem as straw, with its low bulk density, is expensive to move. Research on methods of compacting straw, possibly in the field, has a high priority if the resource is to be exploited. When looking at the potential of utilising ‘new’ biomass species it is important to note that there is relatively little variation in photosynthetic metabolism. It is the suitability of the species to the site, climate and cropping system which is of importance. In this regard information on biomass production between different parts of the plant (as influenced by treatment) is needed in order to manipulate the plant to provide the right quantity and quality of biomass. In ecological terms stands of mixed species, in which the canopy structure makes best use of the available light, are very productive. Evidence from several studies appears to indicate that high yielding natural stands do not grow well when managed intensively. Further, it is often not possible to maintain yields with repeated harvests. This, however, may be a function of a lack of knowledge of how the species should be handled in managed stands. Studies of the basic biology and selection

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of genotypes amenable to cultivation may result in some natural vegetation being suitable for energy cropping. In many countries research is active in the use of agricultural energy crops. of these, Jerusalem artichoke is particularly well studied: the tops can be used for the production of biogas. Cultivation and harvesting account for some 50% of the cost, and R & D is required to reduce the overall production costs. There is some debate as to whether agricultural energy crops or short rotation (coppice) forestry should be the preferred use of the land. In Northern Ireland there has been a systematic examination of the growth and management of Salix aquatica gigantea for several years. Some 500,000 ha of land is suitable for such a crop in Ireland alone. Investigations indicate that a 4-year cutting cycle gives the best yields and that even with annual cutting cycles yields have not declined after 10 years. No fertilizers have been used. Despite these detailed studies it is clear that further work is required to establish optimum rotations, spacing and system economics on a range of sites (and species). With more traditional, i.e., longer rotation, coppice cultivation there is some research ongoing but this is often fragmentary and uncoordinated at present. Undoubtedly the coppice resource is extensive in the Community, particularly France and Italy, and studies on how it can be more effectively utilized and managed are necessary. Tree breeding and improvement has in the past been concentrated primarily on conventional forest tree species. However, the selection criteria necessary for biomass production are somewhat different. In the future it is suggested that there are three courses open: (1) add new selection criteria; (2) examine ‘new’ species, e.g., alder, Robinia; (3) reorientate existing breeding programmes and find suitable material which might otherwise be discarded. In the future it will be necessary to broaden the genetic base and possibly make more use of N-fixing species. Harvesting is a very important element in the growing of forest energy crops and can account for a significant proportion of the overall production cost. Some work is already being undertaken on the harvesting of short rotation coppice (Loughry coppice harvester) and scrub woodland (Scorpion wastes harvester). However, it is considered imperative that further trials and development be undertaken to improve harvesting techniques on a range of crops and reduce costs. The problem of implementation of growing energy crops and marketing is not just one of policy but has R&D implications. It is essential to have a sound knowledge of the type and nature of the product required in order to direct the breeding, management and harvesting R&D effort. Cooperation between those working in biomass production and supply with those in the conversion area should be actively encouraged. It can be concluded that: – cultivation and harvesting costs can be reduced by further R&D; – high energy inputs (such as fertilizer) can be beneficial; – overall system economics should be examined to optimize production practice; – selection and breeding can lead to improved biomass production; – data on type and location of land available should be collected in order to better direct the R&D effort.

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II. Biological Conversion Francesco Alfani, University of Naples, Italy. Emer Colleran, University College, Galway, Ireland. The following is a summary account of the proceedings of the workshop on biological conversion technologies for energy production from biomass. The purpose of the workshop was to provide a forum for in-depth discussion of key aspects of biological conversion, thereby supplementing the more formal morning sessions where time considerations limited both the number of papers and the length of discussion. Biological conversion covers a wide variety of processing options and biological disciplines and includes anaerobic digestion, bioethanol, fermentation chemicals, enzymic saccharification of lignocellulosics, algal hydrocarbon production etc. In order to structure the discussion and in an attempt to equitably divide the workshop time between the various processing options, the session chairmen invited a number of experts to present short papers on topics likely to stimulate discussion. The cooperation of the following experts is gratefully acknowledged: Barry Rugg (USA); Francis Nativel (France); Peter Weiland (FRG); E.J.Nyns (Belgium); D.Verrier (France); A.Rozzi (Italy) and R.Materassi (Italy). Pretreatment and Hydrolysis of Lignocellulosic Materials Utilisation of cellulosic and lignocellulosic materials for ethanol or fermentation chemical production requires extensive pretreatment of the raw material followed by acid or enzymic hydrolysis of the cellulosic component. Contributors to the discussion emphasised the need to develop cost-effective methods which would enhance both the rate and the extent of cellulose hydrolysis. Current interest appears to be focussed on steam explosion of hardwood materials. However, a major limitation of this process is the large loss of the hemicellulose fraction due to degradation by the high steam temperature. A promising alternative is freeze-explosion using liquid anhydrous ammonia insofar as the freezing temperature of the liquid ammonia eliminates the problem of heat degradation of the carbohydrate components. Organosolv procedures are also considered to provide promising pretreatment methods and have the advantage of being applicable to both hardwoods and softwoods. In addition, these processes permit the utilisation of the three main components of the biomass—namely lignin, cellulose and hemicellulose—and some contributors considered that all three components must be utilised in order to achieve cost efficiency. The point was clearly stressed too that no one pretreatment is ideal for all biomass types and that the optimal pretreatment or combination of pretreatment methods will have to be determined on an individual basis for each biomass substrate. No clear decision as to the optimal method for cellulose hydrolysis emerged. Barry Rugg described a mild acid procedure at elevated temperatures currently being evaluated in New York for hydrolysis of paper pulp, twelve different agricultural residues and hardwood materials such as aspen and poplar. The necessity to maximize rates and yields and minimise sugar decomposition losses was emphasised. Hemicelluloses may be preferentially hydrolysed by a preliminary pass through at temperatures below 180°C, thereby minimising subsequent fermentation problems arising from the use of pentose/hexose mixtures. Increasing the sugar concentration in the hydrolysis liquor was

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also considered to be essential. Cold processes utilising concentrated acids, although generally achieving higher yields, were regarded as costly because of the need for complex and capitalintensive plant which would allow recirculation of the large quantities of acid involved. The use of gaseous hydrogen fluoride appears promising, particularly if preceded by a mild pre-hydrolysis with dilute sulphuric acid to remove hemicellulose and other materials such as waxes, resins, organic acids etc. Discussion on enzymic methods of hydrolysis centred on the need to reduce enzyme costs by development of higher-yielding cellulase producers or by recirculation of the enzymes using ultrafiltration membrane reactors. Cellulose losses by adsorption of the enzymes onto undigested material were regarded as being significant. In practice, the cost and energy balance of any cellulose-based project requires very critical and careful analysis and the results of the two-year French study on enzymic hydrolysis of steam exploded biomass will be of value in assessing both of these factors. Alberto Rozzi stressed, in particular, the necessity for energy balance analysis with respect to processes with high steam input requirements. Ethanol and Fermentation Chemicals The feasibility of producing biofuels from surplus agricultural products and the potential role of such fuels in the new European fuel blend policy were discussed. Clearly, production of ethanol from molasses, concentrated cane juice or whey is already an established commercial process. The data presented by Ulla Ringblom from Alfa-Laval in Sweden show that ethanol production from surplus grain is also economically feasible provided byproduct use is ensured—i.e. utilisation of the milled wheat residue as an animal feed, production of liquefied CO2 etc. Further research on the development of yeast strains with greater sugar and ethanol tolerance was seen as essential as was the development and scale-up of more novel fermentation systems such as the vacuferm method. Considerable interest was also expressed in solid-state fermentation methods for both ethanol and acetone-butanol-ethanol (ABE) production. For cellulosic substrates, the need to develop pentose—utilising strains capable of high ethanol yields was considered to be a priority. The recent studies by Scheffers and co-workers in Delft on xylose fermenting Pichia sp. are of interest in this regard. With regard to fermentation chemicals and solvents, Professor Materassi outlined the wide variety of chemicals which can be produced by different fermenting strains. It was felt, however, that the choice between ABE and ethanol fermentation is likely to be dictated more by political than by technical considerations and depends largely on whether EC strategy opts for replacement of lead in petrol by 3% methanol and 2% co-solvents or promotes the use of 10% ethanol. Anaerobic Digestion With respect to the digestion of solid substrates, Peter Wieland of FAL, Braunschweig described a novel process for continuous methanation of grass silage at high solids concentration and utilising a screw press system which dewatered effluent solids and returned the liquid to the fermenter. In a stimulating presentation, Jacques Nyns of Louvain-la-Neuve highlighted the importance of physico-chemical factors in determining the microbiology and hence the fermentation product composition obtained during digestion. This concept implies that, with detailed knowledge of the various physicochemical factors involved, it should be possible to predict the fermentation products

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which would be obtained from a given substrate under various operating conditions. Such a concept is of particular interest in the context of two-phase anaerobic digestion processes since it implies that the first phase can be manipulated physicochemically to yield a feed of suitable and constant composition to the methanation reactor. It also has important implications with respect to the production of fermentation chemicals from biomass. Although it is now apparent that high-rate digesters such as the UASB, fixed-bed design or fluidised-bed system are making a significant impact at full-scale throughout the world for biomethanation of industrial and agricultural wastes, the workshop participants stressed the need for more fundamental microbiological and physicochemical research which would provide valid design criteria and establish optimum start-up and running conditions for retained biomass reactors. A very interesting contribution from Dominic Verrier of INRA highlighted the deficiencies in our knowledge of the factors/mechanisms involved in biofilm and granule formation. A distinction was made between adsorption and attachment of microorganisms to support material surfaces and the importance of adhesin, capsule and glycocalyx formation together with specific attachment mechanisms between individual organisms was stressed. General agreement was reached on the need for the following specific studies: identification and determination of the function of individual bacterial species in biofilms and granules; influence of substrate composition on excreted polymer production; characterisation of the role of methanogens in biofilm formation and cohesion; determination of the influence of the support materials’ characteristics on the initial adsorption phase; identification of the factors which determine the unusually high level of both exopolymer and endopolymer production by methanogens in granules; modelling of biofilm thickening and substrate and product diffusion characteristics in both biofilms and granules. Such studies will require the development of immunological and autoradiographic techniques in order to identify the component microorganisms in the extremely complex ecosystems provided by fixed film and granules. The need for indepth study of the known tolerance of retained biomass reactors to toxicants was emphasised by Alberto Rozzi as was detailed investigation of the mechanisms underlying microbial adaptation to toxicants. III. Research Priorities in Thermal Conversion Technology A.V.Bridgwater, Aston University, UK. A.A.C.M.Beenackers, The University of Groningen, The Netherlands. 1. INTRODUCTION The interest in thermal conversion technology, status and future is reflected by the participation of 70 delegates in the Thermal Conversion Workshop. There was lively discussion throughout the meeting, and it is hoped that the range of views expressed in the meeting is reflected in this report. The objectives of the Workshop were to discuss: – Current state of art,

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– Prospects for thermal conversion technology, – Identification of problem areas, – Identification of research needs, – Possibilities for implementation, in order to provide some recommendation and priorities for research and development in this area. The Workshop programme was divided into five sessions: – Gasification for liquid fuels production (large scale systems) – Gasification to give low heating value gas/producer gas (small scale systems) – Conventional pyrolysis – Flash pyrolysis – Direct liquefaction Each is described and discussed with particular reference to the objectives set out above. Finally some conclusions and recommendations are presented. 2. GASIFICATION FOR LIQUID FUELS PRODUCTION Liquid fuels can be produced from biomass in a variety of ways (1) including: – indirectly by synthesis of liquid fuels from syngas, including methanol, fuel alcohol, gasoline and diesel (discussed here), – directly as pyrolysis liquids which require upgrading (see later discussion in sections 4 and 5), – directly by pressure liquefaction (see later discussion in section 6) The significant constituents of syngas from biomass gasification are CO, H2, CO2 and CH4 together with a large number of minor components and contaminants. Nitrogen from an air gasification process, is conventionally considered to be unacceptable due to the complexity and cost of its removal. Most processes rely on either steam and/or oxygen gasification to give a nitrogen free gas. Gas composition and quality is dependant on a wide range of factors relating particularly to feedstock characteristics, type of gasification reactor, and reaction parameters. The raw gas requires cleaning and conversion using state-of-art technology to give the final liquid product. Each of these aspects is discussed below. 2.1 Synthesis Gas Productions The four EC sponsored demonstration projects for methanol production— AGIP/Italenergie, Creusot-Loire (now Framatome), John Brown/Wellman, and Lurgi are described in detail in another paper (2). Other current work in Europe is being carried out by Rheinbraun, Studsvik Energietecknik, Twente University, and University of Brussels all of which are reported in these proceedings. Although extensive research and development has been performed on all the above processes, much work still remains to be carried out on optimisation and design studies. A number of topics attracted special attention in the Workshop:

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Pressure: The economic and energetic advantages of a pressurised gasifier in reducing compression costs for methanol synthesis or improving power production efficiency, must be set against the higher costs of feeding under pressure and greater operating problems, particularly when using oxygen. The trade-off is not well understood and requires evaluation. Ash:The low levels and relatively stable characteristics of wood ash cause few problems in gasification except when very high temperatures are encountered in either the primary or secondary reactors when using oxygen. Solid waste/refuse, however, gives rise to much more potentially serious problems with ash unless the temperature is carefully controlled. Other biomass feedstocks such as straw and rice hulls also need careful processing to avoid ash fusion in unwanted locations. The principle of slagging gasification of high ash biomass materials has only successfully been applied to refuse, and is unlikely to be suitable for other high ash biomass fuels. Tars:These are an unwanted and almost intractable byproduct of gasification, (although in some pyrolysis processes this fraction is maximised as discussed later). The mechanism of formation and decomposition is not yet well understood, although some interesting research is being carried out and good gasifier design will help to reduce tar production. The results obtained by Creusot Loire with thermal secondary gasification are promising. In situ catalytic gasification, both in the primary gasifier and in secondary gasification, have shown preliminary promising results in R&D work at Battelle Pacific North West and Studsvic Energietechnik. The latter methods, if successfully developed to a commercial scale, may permit lower operating temperatures and hence higher energy efficiencies for the process. This will provide a solution to possible ash melting problems in thermal secondary gasification. These catalytic processes deserve attention in other ongoing R & D work within the EC. Other alternatives might be found in separation of tars followed by either recycling to the gasifier or by disposal. All these alternatives require evaluation in a total system concept. Feeding:The problems of controlled feeding of biomass to a gasifier are being overcome, but the reliability of these systems remains to be proved. Such problems are multiplied when pressurised systems are considered when the feeding system can cost as much as, or more than, the gasifier. Modelling:Thermodynamic modelling of ideal gasifier performance is now well established with empirical modifications to account for deviations from ideality. Stagewise modelling of the various progressive steps in gasification will enable more robust predictive models to be developed for system evaluation and feasibility studies, which are needed for economic and market evaluation. Kinetic modelling for commercial design purposes is necessarily more complex and confidential, and will tend to be reactor-specific. Considerable scope exists for Improvements in both areas, but reliable and robust data resources are necessary. 2.2 Gas Treatment and Conversion The product gas from gasification contains particulates, tars, and contaminants such as H2S, that are deleterious to downstream conversion processes. It is necessary to clean the raw gas prior to compression for the conversion processes. Reliable hot gas cleaning and

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waste heat recovery systems are not yet widely available. While wet washing systems can be designed to give adequate clean-up, there is no long term experience available nor information available of specific requirements for contaminant levels in feeds to compressors. There is, therefore, an opportunity for development of high efficiency scrubbers, The waste water contains dissolved organics and suspended tars, and constitutes a significant disposal problem. While the tars may be separated and recycled to the gasifier or burned as fuel (as discussed above), an environmental problem still remains. This is a further area where useful R&D may be carried out. The orthodox view that syngas for methanol production should have as low a CH4 content as possible was challenged with a view that a secondary reformer in the synthesis loop or purge stream could be economically and energetically preferable to a more costly gasifier giving a low methane product. This requires evaluation. 2.3 Products Although most attention has been paid to production of methanol, a range of other fuel and chemical products are also possible such as methane, gasoline, diesel, syncrude, ammonia, ethanol and mixed alcohols for fuel based on methanol. The more economically attractive products are currently methanol, methanol based fuel alcohol and ammonia; all of which have to be produced at a substantial scale of operation to take advantage of the economies of scale. None, however, is competitive with conventionally derived products in Europe. Circumstances where any of these products could become economically viable need to be identified. A significant feature of these syngas producers is that the product gas is of medium heating value (12–14MJ/Nm3) as it is nitrogen free. It may readily substitute for natural gas in a retrofitting mode without requiring extensive, costly, and space consuming modifications to the burner system, as is required with low heating value gas from air gasification. The higher energy density of the gas will also benefit electricity generation as a smaller engine is required which will also operate more efficiently. An evaluation is required of the costs and benefits of the higher quality gas in order to identify advantageous situations. 2.4 Some New Developments Attention was drawn to a number of interesting new developments concerning modification of syngas composition within the gasification reactor system by: – employing a catalyst in the fluid bed (eg Battelle Columbus and Battelle PNL) to achieve equilibrium compositions of specific favourable reactions, – employing a secondary reformer or partial oxidation reactor downstream of the primary reactor for hydrocarbon decomposition and/or tar elimination. This may be a thermal system (eg Creusot Loire) or catalytic (eg Studsvik’s MINO). There are many opportunities in this area for syngas composition adjustment and quality improvement. Although there is extensive ongoing industrial R&D on Fischer Tropsch catalysts, the small scale biomass to diesel fuel process being developed at the University of Arizona,

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USA, is noteworthy. Claims made for the viability and performance of small scale plants are particularly interesting. However these claims were challenged at the Workshop by arguments that economic evaluations in coal conversion have not shown a favourable effect in down-scaling such a process relative to the indirect route via methanol synthesis. A promising new development is the synthesis gas based production of so-called fuel methanol developed by Lurgi. This product consists of a mixture of methanol and higher alcohols which make it more amenable, rellative to methanol, to blending with gasoline over a wide range of compositions. This is more attractive than methanol alone, and the methanol content also provides enhancement of octane number, thus reducing the need for antiknock agents such as tetraethyl load (TEL), methyl tertiary butyl ether (MTBE) and tertiary butyl alcohol (TBA). There are many other new developments as reported in these proceedings, and the above items reflect the discussion at the workshop. It is also important to note the interactions of developments both outside and inside the biomass conversion field, and it is encouraging to note the process of technology transfer between different process industry sectors. 2.5 Implementation Although substantial technological and scientific progress continues to be made in thermochemical processing of biomass, it is essential that commercial aspects are not overlooked. For industry to participate in, and fund, R & D in this area, companies have to reassure themselves that it is in their short to medium term financial interests to do so. As far as methanol from biomass in Europe is concerned, extensive reservations were expressed about the viability of such a process even for a long time horizon, due to competition from imported methanol and historically low oil and gas prices. A similar view pertains for other synthetic fuels and chemicals when viewed in the same European scenario of large scale production plants. Very different circumstances prevail outside Europe, and there are grounds for greater optimism that implementation is likely in the shorter term with corresponding export opportunities for European industry. As recommended above, it would be helpful to identify the economic, commercial, and technical circumstances under which any of this technology might be implemented. Opportunities are, however, seen within Europe for the technologies that are being developed in methanol based fuel alcohol production and combined heat and power applications, both of which can be considered viable at a substantially lower scale of operation than methanol. There is an ongoing debate on the relative merits of biomass and coal as fuels for gasification and product synthesis which require evaluation both in general and site specific terms. 2.6 Recommendations A summary of the recommendations and opportunities identified for further R&D is given below in respect of activity in the field of gasification for liquid fuels production. 1) Continue optimisation and design studies on gasification reactors (2.1) 2) Obtain experience of pressurised gasification and evaluate the advantages (2.1,2.2) 3) Study biomass ash characteristics (2.1)

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4) Evaluate tar management in respect of degradation, recycling and disposal (2.1, 2.2)— this is related to recommendation 9. 5) Develop more robust predictive gasifier models for system evaluation (2.1) 6) Establish a data base resource for modelling (2.1) 7) Develop hot gas cleaning and waste heat recovery systems (2.2) 8) Establish gas quality specifications for engines and turbines for power generation (2.2) 9) Evaluate in-situ low methane gas production (related to recommendation 4) and methane reforming steps in downstream conversion processes (2.2) 10) Establish the possibilities and circumstances of viable liquid fuels production in Europe (2.3). 11) Evaluate the advantages of medium heating gas in retrofitting and power generation applications (2.3). 12) Examine the use of catalysts in gasification (2.4). This can affect tar and methane production (recommendation 4 and 9). 13) Examine and continue work on secondary gasification (partial oxidation/reforming) with either catalytic or thermal processing (2.4). This can affect both tar production (recommendation 4), and methane production (recommendation 9). 14) Examine the feasibility and viability of very small scale liquid fuel production (2.4) 15) Develop and evaluate the production of methanol based fuel alcohols (2.4) 16) Identify market opportunities for implementation of European technology in biomass conversion in the world-wide market place (2.5) 3. GASIFICATION FOR LOW HEATING VALUE (PRODUCER) GAS 3.1. Gasifiers Extensive research, development and demonstration has been carried out on small scale air gasifiers to produce fuel gas and power in the size range 50–500kg/h biomass (50– 500kWe). Although a range of systems are installed in the field or as demonstration units, there is still a surprising lack of operating experience available. Most problems appear to lie in reliable feeding systems and adequate economic gas clean-up systems. In Europe, most installations are in France where some comparative assessment has been carried out of gasifiers manufactured by Creusot Loire, Cemagref, Babcock, Pillard, Everard, Duvant, Chevet, and Tuillot. No general conclusions were derived. There is still little robust experience of gasifiers operating in the field and a thorough appraisal of gasifiers operating in a real-life situation would be very valuable. Activity currently seems to be evenly split between fixed bed and fluid bed systems. The former are simpler to construct and operate, but have more specific feedstock limitations; while fluid beds are more versatile for feedstocks but are more complex and costly. Specification of a suitable gasifier for a given application is still dependent on the commercial skills of the supplier rather than technical or economic performance of the gasifier. Operating experience and technical back-up are important considerations.

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3.2. Feedstocks Most R&D has been carried out on wood. Other feedstocks considered include bark, agricultural residues, refuse derived fuel (loose and pelletised); and bagasse (loose and pelletised) and rice hulls for developing country applications. Refuse derived fuels offer a range of problems related to their diverse constituents. Aluminium causes jamming of feed screws with shredded feed, and glass softens and agglomerates. Pelleted feed is easier to handle and feed, and gives more consistent gasification but has a significant cost penalty compared to shredded feed, of approximately double the cost. 3.3. Gas Cleaning Heat recovery and gas cleaning were still seen by many members of the workshop as a difficult area, particularly for smaller gasifiers of less than 200kg/h (200kWe). For retrofitting or direct firing, it is energetically advantageous to burn a hot gas, and efficient hot gas cleaning devices are not available. The performance requirement is dependant in application and raw gas quality. For remote fuel gas use or use in an engine for power generation, two systems are available: dry and wet. Dry cleaning gives rise to heat exchange problems from fouling and difficulties in achieving an adequate degree of particulate and tar removal. Bag filters were claimed to be effective but little experience is available. High efficiency systems can be designed and installed, but are claimed to be too expensive. Tar is considered to be the biggest problem in handling, cleaning and using fuel gas from biomass. The alternatives for tar management inside and outside the gasifier were discussed above in section 2.1 and apply here also. Ash also causes problems with some feedstocks, such as the high level of potassium in Euphorbia, and the high silica content of rice hulls. Further work on ash characteristics and management is recommended. 3.4. Applications There is growing awareness by European engine manufacturers of the opportunities afforded by biomass to power applications throughout the world. Some engine manufacturers have acquired considerable practical experience both of engine performance and design, and fuel gas specification. The relatively high cost of the resultant electricity makes for applications in remote areas where there is no utilities infrastructure. It was suggested that power costs from biomass gasification are times that from gasoline. Retrofitting applications with low heating value gas give rise to a number of problems. Boilers are downrated by as much as 25% dependant on the proportion of low heating value gas and design of boiler. In addition burner designs for this gas are relatively large and cumbersome, and hence expensive, and often need to be an additional installation since co-combustion of natural gas and low heating value gas is not considered practicable. It is preferable to burn the gas when hot to avoid loss of sensible heat and an adequate hot gas cleaning system is, therefore, desirable. In such applications, a low ash feedstock is advantageous. Examples include lime calcination and cement manufacture.

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It is claimed that the main competitor to biomass gasification is combustion for heat and power applications. No work has been carried out on a comparative economic assessment, although it is likely that an engine is preferred to a Rankine steam cycle for power generation for smaller scale applications of below about 5 MWe. For less developed countries, licensing agreements for local manufacture are a more acceptable way of implementing gasification. 3.5. New Developments The introduction of low cost oxygen enrichment technology means that a higher heating value gas might be achievable at an acceptable cost. An evaluation of low heating value gas, from air gasification, medium heating value gas from oxygen or steam gasification, and intermediate heating value gas from oxygen enriched air needs to be carried out, paying particular attention to the relative values and uses of the three products. As for syngas production in section 2, there are many opportunities for catalysts and secondary reactors to control tar production and modify gas composition. The innately lower value of producer gas is unlikely to justify use of such sophisticated developments, but the possibilities should not be ignored. Pressurised air gasification offers interesting possibilities for power generation applications, but no activity is known. 3.6. Markets There is a small but steady growth in commercial implementation of gasifiers into the European market. All to date are of European design and manufacture, but there is known to be extensive interest in the European market by American manufacturers. Applications are in fuel gas/process heat, for example lime kilns and crop drying; power generation and combined heat and power (CHP), for example in the wood, timber, and paper industry; and retrofitting for substitution of fossil fuels. Marketable sizes were claimed to range from 50kg/h (50kWe) to 1000 kg/h (1000kWe). Little experience has been gained with larger sizes other than a multiple unit power generation system of total capacity 6.7 MWe in Guyana which is understood to consist of 900kWe modules linked through a common gas manifold. Although market information is understandably commercially sensitive, there is value in undertaking a European market assessment in order to identify opportunities and limitations. A considerable market was seen to exist in the less developed countries, particularly for power generation, for example for irrigation pumping. Technology requirements are significantly different with an emphasis on simplicity, reliable operation and easy maintainability. 3.7. Recommendations A summary of the recommendations and opportunities identified for further R&D is given below in respect of activity in the field of producer gas. 17) Continue development of producer gas systems as an insurance technology. (3)

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18) Monitor gasifier performance in the field. (3.1) 19) Evaluate feeding systems for different feedstocks. (3.1) 20) Evaluate gas cleaning systems. (3.1) 21) Develop hot gas cleaning systems and heat recovery systems from dirty gas. (3.3) 22) Evaluate tar management methods including in-situ decomposition, and post-gasifier removal. (3.3) 23) Characterise ash from different feedstocks. (3.3) 24) Identify and minimise boiler downrating problems. (3.4) 25) Investigate mixing and burning characteristics of low heating value gas and natural gas. (3.4) 26) Undertake a comparative techno-economic assessment of gasification to power and combustion to power systems. (3.4) 27) Investigate the technical and economic advantages of oxygen enriched air for gasification. (3.5) 28) Undertake European market assessment. (3.6) 29) Identify differences in specification for less developed country applications. (3.6) 30) Gain experience with catalysts in gasification to modify product gas quality and/or composition. (3.5) 31) Examine feasibility of secondary reactor to improve gas quality. (3.5) 32) Investigate advantages of pressurised operation. (3.5) 4. PYROLYSIS Thermal degradation of biomass in the absence of oxidising agents is known as pyrolysis. Three main products are formed: – gas: medium heating value fuel gas – liquid: aqueous phase containing dissolved organics, and a nonaqueous phase consisting of oxygenated high molecular weight tars. – solid: char The proportions of each product are dependant on a variety of process parameters, of which heating rate is particularly important. For example a very low heating rate maximises the solid char yield, as practised in carbonisation. 4.1. Solid Products This carbonisation technology is well established in Europe for production of charcoal for metallurgical and leisure (barbecue) industries. It is being rapidly implemented in developing countries for fuel charcoal. 4.2. Gas Products The gas is a valuable fuel gas of medium heating value which has a high level of organics and tars in both vapour and particulate form. Cooling will cause condensation and precipitation of tars, and this must, therefore, be carried out in a controlled manner to avoid problems. Alternatively the gas may be burned hot. This gives extra heat from

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combustion of tars which are also effectively destroyed. Some attention has been paid to maximising the gas yield and minimising tar yield by carrying out a secondary gasification reaction above the pyrolysis bed. A large scale unit of 200,000t/y feed is understood to be operating for production of fuel gas and char in a hearth oven. 4.3. Liquid Products Finally the liquid fraction contains water and a wide variety of organic products from C1 to C30+. This is the pyroligneous acid of a bygone age which produced crude organic chemicals for the alchemist. Water is present from both water in the biomass feed and, to a lesser extent, as a result of reaction. Two phases are formed—an aqueous phase containing the water and low molecular weight oxygenated organics which are dissolved; and higher molecular weight insoluble oxygenated organics which are often referred to as “oil”, but bear little resemblance to the familiar conventional material. Conventional pyrolysis as discussed in this section gives a relatively low liquid yield. “Oil” production: Considerable attention has been paid to maximising this oil yield as it is the product of highest energy density and is superficially the most valuable product, being a liquid “oil”. Most processes employ high heating rates to achieve this effect, and this is discussed further in the next section on flash pyrolysis. An intermediate step between conventional pyrolysis and flash pyrolysis is known as fast pyrolysis. An early version of “oil” production using this approach was the Garrett process which employed finely shredded refuse as feed on a demonstration scale fast pyrolysis unit. Relatively high oil yields were obtained, and trials were carried out on utilising the liquid product. It was claimed to be compatible with, but immiscible with, number 6 fuel oil. There were, however, substantial problems with corrosion from the low pH and from instability which caused polymerisation and setting of the product. These applications problems were never overcome, and the process was abandoned soon after. “oil” upgrading: There is still considerable Interest in the liquid product from pyrolysis in spite of the disappointing evidence of past processes. There are several interesting opportunities for overcoming these problems of which flash pyrolysis and liquefaction are discussed later. Another option is to chemically upgrade the oil after production, for example by hydrogenation. No work is believed to be underway in this area, although it is understood to be a difficult process. Thus, while production of crude liquid is relatively inexpensive (about equivalent to gasoline), upgrading is very costly. Physical stabilisation of oil or stabilised two phase char/oil slurry are possibilities to be investigated. This concept is also applicable to products from flash pyrolysis, and to a lesser extent, liquefaction products. 4.4. Feedstocks Any biomass feedstocks may be pyrolysed. Most work on refuse has now ceased due to problems of poor heat transfer and handling and feeding problems, although there is still

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some interest in rotary kiln, moving bed and spouting bed pyrolysis. Wood is currently being commercially pyrolysed/carbonised for charcoal production in many parts of the world. Agricultural wastes from a variety of sources have been experimented with, but there is little current activity. 4.5. Reactors A fundamental problem of pyrolysis is the supply of heat which either has to be added indirectly through the reactor walls; or directly with an inert heating medium such as solid steel balls, recirculating hot sand, molten metals, molten salts, and hot inert gas; and/or adding a little air/ oxygen to provide some in-situ heat by combustion but insufficient for gasification. A variety of reactor configurations have been employed including fixed beds, rotating kilns, horizontal moving beds, multiple hearths, fluid beds, and spouting beds. Fixed beds and rotary kilns have the major disadvantage of poor heat transfer which limits the size of equipment and gives poor economies of scale. Fluid bed and liquid phase systems have limitations on both solid or liquid movement and also heat transfer to the system, but are generally easier to scale up. Many of these problems can be overcome with either flash pyrolysis or liquefaction, and most attention is being directed to these areas for maximum liquid or gas yield. Most opportunities lie in developing physical and/or chemical liquids upgrading processes, for which little work has been carried out. Gas clean up is by conventional processing as described above under gasification. 4.6. Environment A major environmental problem is disposal of the aqueous liquor which is acidic and has high BOD and COD levels. In commercial carbonisation plants this is conventionally incinerated as a satisfactory method of disposal. The energy balance for incineration is dependent on the water content of the biomass feed and the degree to which it can be dried using waste heat. In developing countries where charcoal production is practiced, the harmful effects of byproduct gas and tar are recognised, and steps are being taken to not only reduce the emissions but also utilise their energy content. 4.7. Modelling Pyrolysis is the process that gives char which is subsequently gasified. The pyrolysis process is believed to be relatively fast, and the rate limiting step is claimed to be that of char gasification. Inevitably the gas and liquid fractions of the pyrolysis process are also at least partly gasified and the extent to which the tars are cracked governs the quality of the product gas in gasification. There are two main steps in secondary cracking of pyrolysis products: partial oxidation or gasification as occurs with char, and thermal cracking as occurs for example in the freeboard above a fluid bed reactor. A better understanding of the pyrolysis process and behaviour of primary pyrolysis products in a thermal, catalytic and/or oxidising environment will considerably aid gasifier design

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procedures. While there is some ongoing work, considerable scope exists for further R&D. 4.8. Commercial Aspects Multiproduct processes such as pyrolysis are difficult to justify on a small scale when up to three markets have to be identified and exploited. The high energy density of the liquid organic fraction means that this must be utilised for viable operation, yet it is known to have severe problems in utilisation. The gas is of medium heating value, and after cleaning, is a valuable product. It is often used to provide the heat for the pyrolysis process. The solid char is slightly worse than coal in marketability and value, and is probably the least useful or valuable of the products in a European context. There are, however, special limited applications in the leisure and metallurgical industries. 4.9. Recommendations A summary of the recommendations and opportunities identified for further R&D is given below in respect of activity in the field of conventional pyrolysis. 33) Examine the physical and chemical characteristics of pyrolysis “oil”. (4.3) 34) Review processes for production of “oil” and assess feasibility of new programme. (4.3) 35) Examine physical and chemical upgrading processes for liquid. (4.3, 4.5) 36) Examine stabilisation of “oil” (4.3) 37) Examine possibility of stabilised char/“oir” slurry fuel. (4.3) 38) Evaluate technical limitations of utilising “oil”. (4.3) 39) Assess environment problems of process including waste water disposal. 40) Instigate a programme to study the pyrolysis process, and secondary processing of pyrolysis products. (4.7) 41) Examine markets and values of 2 or 3 products together. (4.8) 5. FLASH PYROLYSIS This approach is a variation of conventional pyrolysis in which heat-ing rates are considerably increased to maximise either gas or liquids production and in which kinetic control is prevalent. This produces valuable non-equilibrium intermediates which might be exploited more as chemicals than fuels and for which a higher value may be attributed. The non-equilibrium products include ethylene and benzene-toluene-xylene. 5.1 Reactor Four characteristic reaction parameters can be defined:

– high temperature: 700–1000°C, or 2000°C with a solar furnace – high heating rate: 1000°C/s

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– short contact time: 10–100 ms – rapid quenching: ca 50 ms The basic problem to date has been to produce continuous laboratory scale processes to satisfy these requirements. While this has substantially been effected in a number of research institutes in North America and France, several scale-up problems may be readily identified. The very high heating rates necessary are achieved with small particle sizes and a high heat flux. Production of small particles is very energy intensive and expensive, and it is difficult to see how viable commercial scale operation can be realised without significant modification of the process. Similarly the high heat flux required is likely to give problems in scale up, without recourse to a less common method of heat transfer. Further work has been carried on fast pyrolysis in a reactive atmosphere with interesting results. A range of non-euqilibrium chemicals have been produced, and it will be interesting to see how the process may be optimised, scaled-up, and costed. 5.2 Products Varying reactor conditions and feedstocks enables either gas or liquid products to be maximised with corresponding minimisation of the other two usual products i.e. liquid or gas, and char. The gas is of medium heating value and can include products of value as chemicals, although the viability of their separation has not yet been examined. Gas clean-up is conventional. The liquid has a relatively high water content, and the organic fraction is oxygenated and physically unstable. There will also be suspended particulates of char and ash. Liquid upgrading, therefore, requires physical processing and chemical reaction for oxygen reduction. The cost of upgrading is likely to be lower than for conventional pyrolysis products, but still considerably more than for liquefaction products. A similar programme for utilisation of the “oil” is necessary as for conventional pyrolysis “oil”. The product obtained in the Canadian programme is thought to Include sugars, but this has not been fully analysed. 5.3 Problems This area of work is still at an early stage of development. The problem of scale-up in respect of particle size and heat flux has already been noted. For reactor design scale-up, cold modelling of reactor geometry and particle flow patterns is recommended. Erosion is another problem requiring attention. There may be parallels with the LR process (LurgiRuhr) which needs to be investigated. 5.4 Recommendation A summary of the recommendations and opportunities in the area of flash pyrolysis is given below:

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42) Support some small scale research in flash pyrolysis and in reactive flash pyrolysis at laboratory scale (5) 43) Examine viability of chemicals production (5.2) 44) Evaluate upgrading and utilisation of “oil” as for conventional pyrolysis (5.2). 45) Research and development in scale up is necessary, particularly with respect to heat transfer. Feasibility should be demonstrated before pilot plant work (5.3). 6. LIQUEFACTION Liquefaction has developed in parallel to flash pyrolysis and is at about the same stage of development. The characteristic reaction parameters are: – low temperature: up to 350°C – high pressure: up to 300 bar – low heating rate and relatively long residence time – possible addition of hydrogen, CO, and/or catalyst – liquid phase processing. The lower temperatures and heating rate offer the potential to overcome the disadvantages of scale-up noted above for flash pyrolysis, but at the expense of high pressure, a longer reaction time, and use of costly reagents. Analogies with coal liquefaction processes were noted, and a view as expressed that direct liquefaction technology may be more suitable for biomass conversion than coal conversion. It is interesting to note the favourable C:H ratio but unfavourable C:O ratio for biomass compared to coal. Since there are substantial coal liquefaction facilities available, a direct comparison would be interesting. 6.1 Product Yields of liquids of up to 70% by weight of feed have been reported. The liquid product is typically of low water content and low oxygenates and is more stable than pyrolysis “oil”. Although it is more easily upgraded than pyrolysis “oil” it costs considerably more to produce. A recent IEA study into the technoeconomic merits of flash pyrolysis and liquefaction for production of a marketable fuel product is understood to have found that overall, there was relatively little difference in final product cost—in both cases the production cost was several times that of conventional fuel costs. A further feature is the low char yield, possibly due to the higher activity of biomass derived char, which fits the view above about coal and biomass liquefaction potential. The discussion relating to liquids upgrading and use from flash pyrolysis apply equally to liquefaction products; and there is considerably scope for experimentation, applications, and utilisation studies. A variety of other products have been reported such as phenolic oil, hydrocarbons, monosaccharides, hydroxylic and carboxylic acids. Little work has been carried out on product analysis or characterisation, which would be a useful addition to an R&D programme.

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6.2 Reactor Most experimentation has been carried out in a batch mode. It is believed that scaling up liquefaction processes may present fewer technical problems than flash pyrolysis with less constraints on particle size, residence time, and heating rate. Experience of coal processing will aid identification of problem areas. It will also be possible to draw on the practical experience gained with coal liquefaction R&D, and the possibilities of using biomass on a coal liquefaction pilot plant are quite interesting. Particular problem lie in feeding and product separation, which will require special attention. 6.3 Implementation The technology is insufficiently developed to provide useful indications of application or viabilities, although the current prognosis is discouraging. A monitoring activity should at least be maintained, and a small R&D programme can be justified. 6.4 Related technologies Other related technologies that are recognised as interesting but which have been little research to date are supercritical solvolysis, hydropyrolysis, and separation processes for recovery of sugars and BTX. There is Insufficient data to make any prognostication, but activity should be monitored. 6.5 Recommendation The recommendations and opportunities identified for further R&D in the area of liquefaction and related technologies are summarised below: 46) Compare biomass liquefaction technology with coal liquefaction technology (6). 47) Investigate and experiment with physical and chemical upgrading processes for liquids (6.1). 48) Develop product characterisation and analysis, with suitable procedures (6.1). 49) Identify specific chemicals that might be efficiently produced with this technology (6.1). 50) Examine and monitor feasibility and viability of liquefaction technology (6.2). 51) Implement a small R&D programme on liquefaction (6.3). 52) Monitor activity in related technology areas (6.4). 7. CONCLUSIONS The status and prognosis for all thermochemical processing areas have been reviewed, and 52 recommendations made in the five areas discussed. In addition to an overall recommendation to continue fundamental and applied R&D in the well established areas of gasification, there is another overall recommendation to broaden sponsorship into the more specialised and less developed technologies, particularly when there is an emphasis on liquid products.

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It is important not to forget that the justification for any R&D programme is the eventual commercialisation of the technology. Any programme must therefore take account of both the technical feasibility and potential economic viability of the process under investigation, even if the research topic is many steps removed from the market place. It is hoped that the discussion and recommendations resulting from this Workshop will prove of value to researchers, sponsors and policymakers, and the chairmen would like to thank all the participants for their contributions and active involvement in the Workshop. 8. REFERENCES 1) Beenackers, A A C M, and Bridgwater, A V, “The status and future of thermochemical processing of biomass”, in Energy from Biomass vol 5 (Reidel 1984) 2) Van Swaaij, W P M, “The Commissions programme on advanced gasification” these proceedings.

IV. Combustion and Densification A.Strehler, University of Munich, FRG. T.T.Pederson, Royal Veterinary & Agricultural University, Denmark. Dr Strehler gave an introductory paper about technical possibilities and economical problems of combustion and densification of biomass, concentrating on wood and straw. The resources from agricultural waste and biomass from futural energy plantations were shown. For energy production rape and short rotation forestry were good options. The most serious problem in combustion were: – combustion quality – efficiency – work load – costs – material in critical places of furnaces (thermal and chemical stability) Large quantities of straw and wood are available for heat generation. The combustion quality has to be improved to diminish the environmental impact of furnaces. Depending largely on local conditions, many farms can be heated via biomass combustion on a solid financial basis while being independent of imported fuel. Mr Brenndorfer, KTBL Darmstadt, gave a report about briquetting of straw in an onfarm-demonstration plant. According to present operation experience the operating reliability can be considered as good. Costs for producing briquettes depend on the rate of utilization, organisation and preparation. At a utilization rate of about 1,000 hours/year the production costs amount to about 210 DM/t of briquettes. Combustion of these briquettes resulted in very low emission (dust content), which are fully in accordance with the emission standards of the FRG. Mr Sturmer, TUM, FRG, spoke about, “Economics of High Pressure Densification” Three straw briquetting enterprises were compared, two on solid economical success, one

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without. In his summary, Sturmer stressed that it was the related circumstances that determined whether the results were positive or negative. Mrs Christel Benestad, Central Institute for Industrial Research, Oslo, Norway, gave a very interesting lesson about air pollution by combustion of wood and straw. Polycyclic aromatic hydrocarbons (PAH, some of which are known carcinogens, are formed by incomplete combustion of any carbonaceous materials. Recently, studies in Scandinavia showed that very high concentration of PAH could be found in emissions from combustion of biomass. These emissions have also been shown to contain large amounts of mutagenic materials, as detected by the Ames’ Salmonella mutagenicity assay. Results for different furnaces. Studies were done in 20–50 kW performance. Small single stoves had the lowest combustion quality. While starting a cold furnace, pollution is worst. Stoves have to be improved in combustion quality. Straw as a fuel was near to wood. Mr Wilson from Foster Wheeler, UK, showed the technical possibilities of combustion and gasification of biomass in fluidized bed systems of the manufactuer, Foster Wheeler. Some information was presented about peat combustion. Mr Gautier, France, reported about cereal straw combustion for corn drying, harvesting and energetic valorization of corn cob. The rise of fossil energy price entails difficulties for the farmers and collector organisms which dry corn. Drying costs are high. The waste such as cereal straws or corn cobs, used by combustion, represent a solution. They allow organisms to control their fuel stock and to master its cost price better. From 1979, straw furnaces have been settled in farms, in the parisian area. Trials have been realised with this equipment, in relation with the constructors in order to determine their performance with a view to improve them. In 1984, more than 30 straw furnaces were in operation. The equipment make the investment overcosts profitable from 3 to 4 years. At the same time, three establishments burned dried cobs in high powered furnaces in order to dry corn seeds. Some furnaces have high performances of up to 700kWth. Rotary grates and drump boilers were described. Dr Okken, NL, spoke about wood stoves in The Netherlands, including environmental and social aspects. In general wood stoves have too much heating capacity. As a consequence they must be operated with little air supply in order to temper the heat output. This has an adverse impact on air pollution; emissions of polycyclic aromatic compounds, particiles and carbon monoxide will rise. Mr B: Wilton, Univ. of Nottingham, UK, reported about fluidized bed combustion of both light and wet biomass. The problem Fluidised bed combustion is a potentially desirable process for biomass; however, in practice one major problem is encountered, namely the air velocity required to fluidise the bed elutriates light biomass before it has a chance to burn complete. When this happens the bed temperature drops and the process becomes unstable. Densification of some biomass materials to make them resemble coal may overcome this problem, but if this operation could be avoided and a more generally applicable solution found, biomass would become a more attractive fuel.

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A particular problem outside the EEC is rice husks, which at the moment often causes environmental problems because they are disposed of by allowing large heaps to smoulder; another potential fuel is maize stover and there are several by-products for agriculture and forestry that are normally considered too wet to burn. The solution At the University of Nottingham a somewhat unusual fluidised bed combustor has been designed and is being built. It has three features that will encourage biomass to burn within the bed and a further two that will retain any elutriated material for a period long enough for combustion to be completed. Mr M.Hellwig, Chile, guest scientist at TU-Munich, Weihenstephan, FRG, presented a paper about “Fundamentals of the Combustion of Wood and Straw under Special Consideration of the Burden on the Environment”. The direct combustion of wood and straw is the most important use of biomass in substitution oil, since the technical equipment required is minimal. However, difficultires often arise with the combustion of biomass, which result in a serious burden to the environment. This work discusses the importance of the essential combustion characteristics of wood and straw and compares these to other fuels. Mr U.Kraus, TU-Weihenstephan, spoke about test results from pilot plants for firing wood and straw in the Federal Republic of Germany. In the FRG, the entire energy demand for agriculture could be met with regenerative energy sources. Forestry waste and straw deliver by far the largest portion. The combustion of these materials often leads to problems. Apart from a high combustion quality, practical applications require a high degree of automatisation of the plant. Plant for wood chips give very good results with regard to the combustion quality. The dust emissions are clearly below the values allowed under FRG laws. Efficiency of 80% and more can be reached with a moisture content of around 25% for chips and when operating the boilers at near capacity. Slag problems have not as yet appeared at any of the supervised plants. The firing of straw is accompanied by still larger problems. Even with dust filters, it is difficult to reduce the solid particle emissions in the flue gas to a value of 300 mg/m3 as required by law. In addition, the formation of slag represents a problem, which however will be solved with the use of new grate systems. There were further discussions about: combustion quality, costs, regulations in different countries, availability of biomass, and test methods.

CONTRIBUTED PAPERS I. RESOURCES (a) Trees (b) Crops (c) Algae and Aquatic Plants (d) Physiology

BIOMASS FROM SHORT ROTATION COPPICE WILLOW IN NORTHERN IRELAND G H McELROY AND W M DAWSON HORTICULTURAL CENTRE, LOUGHGALL, NORTHERN IRELAND SUMMARY This project began in 1973 with the objective of maximising the production of willow biomass on agriculturally marginal land as an alternative and renewable energy source to fossil resources. After screening a range of species Salix x’Aquatica Gigantea’ was identified as the most promising for this investigation. Plot work at both the Horticultural Centre and on the marginal surface water gley soils of County Fermanagh, the area identified as having the greatest potential for biomass production in the United Kingdom, has shown that at the planting density of 20,000 ha−1 annual yield increments of 17 t oven dry matter ha–1 have been achieved from triennial harvesting cycles. Having established basic production criteria a development plot of 2.0 ha was established in County Fermanagh to provide feed-stock for commercial end product evaluation. Initially two routes were investigated viz: (i) Chipping for direct burning. An automatic stoker and boiler system has been operating for two seasons to heat a 200 m2 glasshouse producing early tomatoes. Mean daily usage for the February to June period in 1983, maintaining a daily minimum of 18°C with a 2°C night set-back was 292 kg willow biomass at 30–35 per cent moisture. (ii) Animal feed supplement. Chipped willow biomass has been further processed and evaluated with silage as an animal feed and has been shown to have the feeding value of cereal straw. New techniques for fractionating wood show promise for developing this use.

INTRODUCTION Northern Ireland’s position as a relatively isolated part of the United Kingdom not having significant fossil energy resources led to an examination of the contribution that the large area of marginal agricultural land in the west of the province could make to local energy requirements. In a basically agricultural economy with a low population density(in this area 27.5 km−2) it was envisaged that biomass could make a significant contribution. Following earlier work at the Horticultural Centre Loughgall trials began in 1975 in Co Fermanagh where most of the heavy surface water mineral gley soils are found. This area

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of County Fermanagh and west County Tyrone has been identified as the largest area (200,000 ha) of potentially suitiable land for biomass production in the United Kingdom (1). Trials carried out in 1973/74 identified willow (Salix ) as the most productive genera (2) (3) for biomass production in this area. Investigations centred on identifying the most suitable species planting densities, harvesting cycles and management techniques. 2. SPECIES AND SPACING Following screening trials (4) two species were selected for evaluation at a range of densities—Salix x ‘Aquatica Gigantea’ and viminalis. Salix viminalis proved unsuitable because of lower yields and poor persistence under intensive harvesting cycles. From establishment (1975) nine annual harvests have been taken from Salix x ‘Aquatica Gigantea’ and the yields are given in Table I.

TABLE I Yield data (t ha–1) of Salix ‘Aquatica Gigantea’ planted at eight densities and harvested annually. Spacing (m) Fresh wt. Dry wt. Mean Fresh wt. Mean Dry wt.* 1984 1984 1976–84 1976–84 1.0×0.25 44.0 19.4 1.5×0.25 37.1 16.3 2.0×0.25 35.9 15.8 3.0×0.25 24.2 10.6 1.0×0.50 33.2 14.6 1.5×0.50 32.5 14.3 2.0×0.50 33.1 14.6 3.0×0.50 25.7 11.3 *Calculated using 1984 dry weight figures.

38.7 30.6 26.5 20.6 30.7 27.9 24.1 20.1

17.0 13.5 11.7 9.1 13.5 12.3 10.6 8.8

At the higher densities maximum yields are obtained generally within two years of establishment and have been maintained to date; there being no trend towards decreasing yields. The lowest densities show a significant reduction in yield indicating that the complete ground capture has not been obtained to date with annual harvesting. In addition at lower densities competition is reduced and so cane number per stool increases. Further evidence indicates that square planting (0.7×0.7 m) may be more productive than rectangular plantings at the same density. However for our current harvesting operation a minimum of one metre is required between rows (5). Based on this information it was decided that a spacing of 1.0×0.5 m (20,000 ha–1), had the best potential for optimising yield whilst at the same time minimising management problems.

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3. HARVESTING CYCLES A series of trials with Salix x ‘Aquatica Gigantea’ planted at adensity of 20,000 ha–1 in 1976 was carried out to evaluate the effect of annual biennial and triennial harvesting cycles on yield. These trials were carried out on the surface water mineral gley soils of Co Fermanagh and the results obtained are recorded in Table II.

TABLE II Yield data (t ha−1) of Salix x ‘Aquatica Gigantea’ for three harvesting cycles (planting density 20,000 ha−1). Harvesting Mean annual yield Cycle ′77 ′78 ′79 ′80 ′81 ′82 increment Fresh wt *Dry wt Annual 8.7 16.6 17.0 22.6 16.7 18.7 Biennial – 36.5 – 66.3 – 51.0 Triennial – – 82.3 – – 97.3 *Based on 1982 dry matter analysis.

16.6 25.6 29.9

7.8 12.0 14.6

This data shows an increasing annual dry matter yield increment with increasing harvesting interval. The triennial harvest carried out in 1982 (see above) gave the highest total yield with a mean of 97.3t ha–1 fresh weight. At a dry matter content of 49 per cent at harvest this gives a yield increment of 15.9t ha–1 year–1 dry matter. With increasing annual yield increments being recorded from biennial and triennial harvesting cycles observational plots were established at Loughgall in 1979 to investigate yields after four, five and six year harvests. These longer cycles however have the disadvantage of a less attractive cash flow and will be much more difficult to harvest and handle mechanically. The most important concept underlying the production of biomass from short rotation coppice is to maximise the nett energy gain both in production and utilisation. Early results showed a yield increase with added nitrogen and over a nine year period a mean yield increase of 1.2t ha–1 dry matter has been recorded following an annual application of 45 kg ha–1 nitrogen costing £17.50. Trials to determine the effect of further increasing nitrogen application up to 250 kg did not show economic yield responses. Calculations based on leaf litter analysis show that Salix x ‘Aquatica Gigantea’ contributes 130kg N ha–1 yr–1 and yields to date have been maintained by this level of fertilisation. 4. UTILISATION Having established production technology for willow biomass on low grade mineral soils the emphasis of this project has been changed to investigate and evaluate the opportunities which exist for the utilisation of biomass in specific areas of Northern Ireland. Two main topics are currently under investigation—the use of biomass as a fuel for direct burning and as an animal feed supplement. To provide a feedstock for these investigations and to obtain yield data from a commercial block of willow coppice a

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2.0ha plantation was established in County Fermanagh in 1982 and will provide its first three year harvest in the winter of 1985. Direct burning: Since combustion technology using wood as a fuel is well established initial work has concentrated on the use of biomass as a fuel source for commercial purposes and to create self sufficiency in energy requirements on farms. Chipped willow rods were used as the energy source for the production of early tomatoes using a heating system incorporating an automatic stoker, gasifier and high output boiler (216 MJ hour−1). For this system it was necessary for the chipped willow biomass to have a minimum dry matter of 50 per cent up to a maximum of 75 per cent. Three year old willow has a dry matter of approximately 50 per cent at harvest and experience (6) has shown that under natural drying conditions in the open the preferred dry matter content (65–75 per cent) was achieved in twenty four weeks from harvesting in OctoberNovember, but little drying occurs before mid-February. Two years experience have been obtained with this system maintaining a regime of 18°C day 16°C night with ventilation at 27°C for early tomatoes. Fuel consumption has varied between 225–359kg of willow chip day−1 with a mean over the two years of 292kg day−1. A mean dry matter of 70 per cent with a thermal value of 14.2MJ kg−1 was recorded for the wood chip during the period. Comparative data for three fuels are recorded in Table III.

Table III Comparative data for alternative energy sources supplying 1.0TJ Fuel Biomass (70% DM) Coal Oil (35 Sec)

Energy value (MJ kg–1) Total reqd (t) Cost t–1 (£) Cost MJ–1 (£) 14.2 32.6 44.2

88.1 43.7 30.2

17.6 90.0 238.7

0.12 0.28 0.54

For self sufficiency in energy requirements it has been calculated that the average farmhouse will require 1.8ha of willow coppice with 0.6ha harvested annually. This will produce an energy equivalent of 4.0t of coal the average annual usage. In addition to burning the willow biomass as wood chip its value in the production cf compressed briquettes has been investigated. The briquettes produced had a thermal value of 17.8MJ kg−1 and being dense had good burning properties thus extending the market for biomass based fuels. Animal feed supplement: In the spring of 1980 7.0t of three year old rods of Salix x ‘Aquatica Gigantea’ were treated with sodium metabolisable energy content of 6.2MJ kg−1 compared with silage at 10.2MJ kg−1. Their acceptability to beef cattle proved to be poor hydroxide and processed into animal feed pellets. These pellets had a (7). Up to 20 per cent silage dry matter was replaced with willow biomass and serial increases in the levels of inclusion of willow biomass resulted in a corresponding reduction in liveweight gain of the 430 kg steers used in the trial. Bearing in mind the levels of nutrition and digestibility of this material its evaluation as a maintenance diet for suckler cows would be more realistic. Trials have also been carried out with similarly treated willow biomass fed to sheep in pelleted diets (8). Digestibility and energy content of the various diets declined with increasing content of treated willow and it was considered that because of low

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digestibility and consequent low metabolisable energy content, in this case 5.7MJ kg−1 dry matter that it is unlikely to have a major use in present ruminant winter feeding systems. However, because Northern Ireland agriculture has a large dependence on imported feedstuffs further technological advances in wood processing may identify a valuable contribution from willow biomass. In this context relatively recent work carried out in Canada (9) is promising. This involves a steam explosion technique to break the ligno-cellulosic bonding in wood and in so doing improve its overall digestibility to 65 per cent. The production of celluloses suitable for use in animal feeds would enhance the economic prospects for willow biomass utilisation. Salix x ‘Aquatica Gigantea’ rods have been processed in this way and up to 32 grams per litre glucose has been recoverd where 55 grams per liter representes 100 per cent recovery. Other opportunities for the utilisation of willow biomass including the manufacture of charcoal, the production of chipboard and its use as a source of viscose for the textile industry are under consideration. 5. REFERENCES (1) STOTT, K.G. (1977). Coppice willow pulpwood - feasibility study. Report for Paper Industry Research Association. Leatherhead, Surrey, England. (2) STOTT, K.G., McELROY, G.H., ABERNETHY, W. and HAYES, P. (1980). Coppice Willow for Biomass in the U.K. 198–209. In Energy from Biomass 1st E.C. Conference Brighton. (3) STOTT, K.G., PARFITT, R.I., McELROY, G.H. and ABERNETHY, W. (1982). Productivity of Coppice Willow in Biomass trials in the UK, 230–235 In Energy from Biomass. 2nd E.C. Conference Berlin. (4) STOTT, K.G. (1971). Check list of Long Ashton willows. Rep. Long Ashton Research Station, Bristol 1971. 143–249. (5) McLAIN, H.D. (1982). The development of a harvester for 2–3 year old Willow Coppice 225– 229. In Energy from Biomass. 2nd E.C. Conference Berlin. (6) ANON. (1983) Annual Report The Horticultural Centre, Loughgall, Northern Ireland. 96–98. (7) McCULLOUGH, I. (1981). Evaluation of willow nuts as a feed for beef cattle. Internal Report. Department of Agriculture Northern Ireland. (8) WYLIE, A. (1984). The apparent digestibility of alkali-treated willow ( Salix x ‘Aquatica Gigantea’) when fed to sheep. J.Sci. Food Agric. 35. 1174–1177. (9) ANON. (1984). Iotech Biomass Review. Iotech, Montreal Canada.

BIOMASS GAINS IN COPPICING TREES FOR ENERGY CROPS W.A.GEYER, G.G.NAUGHTON, and M.W.MELICHAR Department of Forestry, Kansas State University Manhattan, Kansas 66506 Summary Woody biomass is an appealing energy source. When grown under the short-rotation intensive culture (SRIC) system, fuelwood crops are harvested at a relatively young age. Subsequent crops are dependent upon coppice regrowth from established root systems. Use of species/clones that resprout profusely and consistently is crucial to the successful application of this concept. In 1968 a series of experiments were initiated to evaluate biomass yields in seedling and coppiced tree plantings. Several fastgrowing deciduous tree species and Populus clones were tested using two- to fouryear cutting cycles over several rotations. Survival was over 90 percent for seven species when first cut at two years. Firstcycle coppice yields were about 60 percent more than seedling yields. Some two-year sprouts at 0.3×1.2m spacing yielded 20 dry tonnes/ha. Acer sp. demonstrated the longest root system viability. Many Populus clones did not sprout when first cut at four years. Those sources from the central United States grew and sprouted best. The biomass yields and sprouting longevity observed in our studies indicate that several deciduous tree species and selected Populus clones have potential for succesive coppice harvest cuts in shortrotation energy forest plantations.

1. INTRODUCTION Use of wood as an energy resource has tripled in the United States since the 1960s. In 1981 wood supplied about six percent of industrial and 10 percent of residential heating requirements nationwide (4). Forest plantations managed intensively for biomass production could contribute significantly to energy supplies. SRIC forestry is a silvicultural system that incorporates close spacing, intensive cultural techniques, and short cutting cycles. This system was first studied intensively in the United States in the mid-1960s (5). In 1978 a comprehensive national program was initiated by the United States Department of Energy. Successful coppice rotations are crucial to the SRIC concept. Time of harvest, stump height, age, and tree species affect stump survival and coppice response. Establishment and production costs are reduced substantially with high coppice yields (6).

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This report summarizes the results of numerous coppice experiments with several fastgrowing deciduous tree species grown in the central Great Plains region of the United States. 2. PRELIMINARY STUDIES In 1968 silver maple was planted on a loamy alluvial site at three spacings--0.3×0.3, 0.45×0.45 or 0.6×0.6m—and replicated six times. Plots were hand cultivated throughout the experiment. Trees were cut and weighed on 1- to 3-year cutting cycles for a period of eight growing seasons (1). Spacing affected yield during the first two growing seasons (Table I). Mortality was highest at the closer spacing and increased with successive harvests. Yields averaged nine dry tonnes/ha annually. Longer cutting cycles increased the annual growth rates.

Table I. Survival and growth of coppiced silver maple 1/ 3/ Years Growing Survival Annual Growth-Rate 2/ Seasons 1 2 3 1 2 3 (%) (dry tonnes/ha) 2 3 4 5 6 8

2 73 3 61 1 39 1 41 1 37 2 29

68 88 56 81 40 66 48 62 40 56 28 50

8.7 11.6 5.6 9.0 7.2 12.8

5.8 9.0 3.4 8.3 6.3 10.8

4.0 11.4 5.2 10.8 7.6 14.8

1/ One-half plots cut and weighed after 2nd and 3rd year; all cut at 4th, 5th, 6th and 8th year. 2/ Spacing—1) 0.3×0.3m, 2) 0.45×0.45m and 3) 0.6×0.6m. 3/ Annual growth by actual cut and weighed plot yield.

3. MULTI-SPECIES STUDIES Several additional species were studied for their coppice potential in subsequent trials and early results were reported (2). Seven tree species were planted in rows 1.2m apart on two alluvial planting sites—sandy and loamy. Spacing within rows was 0.3, 0.6, or 1.2m. Plots (0.01 hectare) were set up for each spacing with 370, 190, or 100 trees, respectively, per plot. Weeds were controlled by cultivation. Biennial harvest cuts were made during the dormant season.

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ANOVA tests (split split plot) revealed significant differences in annual growth rates for growing sites, spacing, harvest cycles, and spacing-harvest cycle interaction. Yields are presented in Table II. In general, the loamy site produced 50 percent more biomass than the sandy site; boxelder (Acer negundo) produced substantially less biomass than the other six species; closer spacing produced 10–25 percent greater yield than wider spacing; the first 2-year coppice harvest produced 60 percent greater yield than the first 2-year seedling harvest. The percentage growth increase was not as large at closer spacings as at wider spacings. Some species did not respond well to multiple cuttings, especially on the sandy site. Sycamore (Platanus occidentalis) sandbar willow (Salix exigua) and the male cottonwood (Populus sp.) cultivar (Siouxland) died after one coppice harvest. Native cottonwood and European black alder (Alnus glutinosa) had greater longevity than these three species, but eventually died on the dry, sandy site. Production on loamy soil was better than the original seedling yield for four successive coppice harvests.

Table II. Biomass production yields from two alluvial sites cut on several 2-year cycles. Species Spacing1/ Boxelder

Sycamore

Cottonwood (Missouri)

Black alder

Sandbar Willow

Silver Maple

Cottonwood (Siouxland)

1 2 3 Mean 1 2 3 Mean 1 2 3 Mean 1 2 3 Mean 1 2 3 Mean 1 2 3 Mean 1 2

Annual Growth Rate (Dry T/ha/yr) Seedling Coppice 1 Coppice 2 Coppice 3 Coppice 4 1.91 0.85 0.78 1.19 4.64 3.36 3.32 3.74 4.82 5.29 4.21 4.77 3.77 3.18 2.73 3.23 3.70 3.77 2.13 3.21 5.60 4.82 3.10 4.51 7.51 6.95

5.10 3.99 2.96 4.01 5.04 5.27 5.49 5.27 6.81 7.40 7.85 7.35 8.92 7.20 6.20 7.42 7.58 5.56 4.21 5.78 7.62 8.52 7.13 7.76 6.32 6.68

6.73 5.20 3.86 5.27 1.75 2.13 1.91 1.93 6.95 5.83 6.95 6.57 6.28 4.60 4.75 5.20 – – – – 7.62 8.18 7.67 7.82 – –

6.32 5.49 4.60 5.47 – – – – 3.47 4.04 3.92 3.81 1.70 2.11 1.26 1.68 – – – – 6.32 7.51 5.87 6.57 – –

4.20 3.92 3.47 3.87 – – – – 2.73 2.47 3.14 2.78 1.68 2.47 1.68 1.95 – – – – 5.04 5.65 5.38 5.36 – –

Biomass gains in coppicing trees for energy crops

3 6.23 6.73 – Mean 6.90 6.59 – Catalpa 1 3.36 5.42 6.61 2 3.25 5.33 5.94 3 2.87 5.60 6.16 Mean 3.34 5.45 6.23 1/ Code: 1–0.3 by 1.2m, 2–0.6 by 1.2m, and 3–1.2 by 1.2

289

– – – – – –

– – – – – –

Two species of Acer have shown remarkable longevity following numerous harvests. Silver maple (Acer saccharinum) is among the top biomass producers, while boxelder is lowest. The boxelder source was from southeastern United States, suggesting that this race may not be suited to the central plains states environment. At the widest spacing, coppice yield production for both species was one to four times greater than original seedling yield. Coppice survival was high (80+percent) at the 1.2×1.2m spacing, and dropped to 50 percent at the 0.3×1.2m spacing. 4. POPULUS SOURCE TESTS Thirty Populus clones were tested to find suitable planting materials for the Great Plains. Most were P.deltoides from the central United States. The NE sources are hybrids (P.nigra x deltoides). Parentage of these test materials can be found in Hansen et a1. (3) and Read (7). Ten rooted cuttings of each source were planted in 1978 at 1.2×1.2m spacing in a completely randomized field design. After four years in the field, the cuttings were harvested. Coppice growth was evaluated two years later. Local sources did not survive or grow well. Twelve of the original sources had at least 50 percent survival at four years (Table III). Two years after harvest, seven sources had successfully coppiced from 50 percent or more of the cut stumps and only three sources (2,8,21) of the original planted rooted cuttings had survival rates of 50 percent or more after six years. Volume (D2H) values calculated from non-destructive tree measurements were used to evaluate growth. These three sources coppiced well and were among the top four clones in volume production.

Table III. Rooted cutting and coppice growth of promising Populus sources. Clone #

Source

1 62C 2 Missouri 6 254C 7 243C 8 259N 16 NE 222 17 NE 238

Rooted Cutting (4 yrs) Survival Diam.1/ Ht. Vol. 2/ (%) (cm) 90 60 60 60 50 60 50

7.6 10.7 8.4 7.9 9.9 11.1 13.0

6.6 8.1 5.6 7.1 7.4 7.1 7.1

209 504 231 235 369 356 606

Coppice (2 yrs.) Survival Ht. Vol.2/ (%)3/ (m) 20 50* 10 40* 50* 20 30*

4.2 5.3 2.7 4.8 5.3 4.9 4.2

42 193 10 66 193 78 102

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18 NE 264 70 9.9 7.0 366 30 2.2 12 20 Miss. 74 60 6.9 5.1 173 30* 4.9 126 21 Souixland 100 11.9 7.4 557 70* 3.9 113 22 379N 50 11.1 7.4 592 30* 4.5 238 24 181N 50 8.4 6.0 223 20 3.6 50 1/ Stump diameter at 5cm above ground. 2/ Volume expressed by stump D2H values. Relative value as calculate in English units (diameter in inches, height in feet). 3/ Survival from original planting, while those* indicate 50% survival of cut stumps .

While Populus clones are often screened for rooting ability, it appears that coppice production and survival are also clone related. Thus selected clones should be screened for both characteristics. 5. DISCUSSION AND CONCLUSIONS Biomass gains from coppicing trees are essential in the success of the short-rotation forestry concept. In these studies, coppice yields were substantially greater than the original seedling yields, especially at the wider spacing of 1.2m. Some species— boxelder, silver maple, Siberian elm, and European black alder—and selected Populus clones—Missouri, 259N and Siouxland—coppiced well at young ages, while others did not. Acer species have excellent coppicing viability and can maintain biomass production after four or five cuttings. Several deciduous tree species grown under SRIC have the potential to produce high yields for a number of harvests. High biomass yields combined with favorable climatic conditions in the eastern Great Plains region suggest woody plants could contribute to energy supplies. REFERENCES (1) GEYER, W.A. (1978). Spacing and cutting cycle influence on shortrotation silver maple yield. Tree Planters Notes. Vol. 29 (1) 5–7, 26. (2) GEYER, W.A. (1981). Growth, yield, and woody biomass characteristics of seven shortrotation hardwoods. Wood Science. Vol. 13 (4) 209–215. (3) HANSEN, E., MOORE, L., NETZER, D., OSTRY, M., PHIPPS, H. and ZAVITKOVSKI, J. (1983). Establishing intensively cultured hybrid poplar plantations for fuel and fiber. USDA For. Serv. No. Cntrl. For. Expt. Sta. Gen. Tech. Rpt. NC–78. 24 pp. (4) HEWETT, C.E. and GLIDDEN, Jr., W.T. (1982). Market pressures to use wood as an energy resource—current trends and a financial assessment. Resources Policy Center. Thayer Sch. of Engg. Dartmouth College. Hanover, VT. USA. 24 pp. (5) MCALPINE, R.F., BROWN, C.L., HERRICK, W.H. and AUARK, H.E. (1976). “Silage” Sycamore. For. Farmer. Vol. 26 (6). 6–7, 16. (6) NAUGHTON, G.G. and GEYER, W.A. (1982). An economic analysis of energy forest plantations. Proceeding: Energy from Biomass, edited by A.Strub, P.Chartier and G.Schleser. Berlin, Germany. Applied Science Publishers. 94–98. (7) READ, R.A. (1967). Hybrid poplar performance at 10 years in the Nebraska sandhills. USDA For. Serv. Rocky Mtn. For. and Rg. Expt. Sta. Res. Note RM–91. 8 pp.

SHORT ROTATION COPPICE FOREST BIOMASS PRODUCTION THE WORK OF I.U.F.R.O. S1.05-10 WORKING PARTY D.AUCLAIR Institut National de la Recherche Agronomique Station de Sylviculture d’Orléans S1.05–10 working party chairman Summary The International Union of Forestry Research Organisations (I.U.F.R.O.) gathers approximately 200 scientific research units into six “divisions”. The working party S1.05–10, entitled “monospecific coppice stands in short rotation” includes forest scientists working worldwide on this subject, and mostly interested in biomass production. An enquiry has been sent to interested members of I.U.F.R.O. to compile available data, mainly concerning coppice biomass production in various experimental conditions. The present work summarizes the results of this enquiry, giving some information on the various existing experimental plots and on the research objectives.

1. INTRODUCTION The International Union of Forestry Research Organisations groups 10 000 scientists belonging to 500 member organisations, coming from 90 countries. It is divided in 200 research units under 6 main divisions. In Division 1, “Forest Environment and Silviculture”, the fifth Subject group (S1.05– 00), “Stand establishment, treatment and amelioration”, includes two working parties interested in coppice: S1.05–09, “Treatment and conversion of coppice stands”, and S1.05–10 “Monospecific coppice stands in short rotation”. This last working party has received a new impulse with the growing interest for biomass production. At present sixty scientists coming from 18 countries have answered to an enquiry concerning their projects and their experimental plots. Countries most represented in this group are, inside Europe : France and United Kingdom, and outside EEC: Sweden, USA and Canada. The aim of the present paper is to outline the main characteristics common to the studies undertaken by members of IUFRO working party “Monospecific coppice stands in short rotation”, after an enquiry sent out to those scientists which were registered in the IUFRO files. 2. TRADITIONAL COPPICE

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The IUFRO group most interested in traditional coppice is S1.05–09 “Treatment and conversion of coppice stands”. The objective is mainly to study means of improving the quality of timber produced with this technique, mostly by conversion to coppice with standards or high forest. However, several scientists in France, Italy, UK, and Canada, have been interested in studying the quantity of biomass produced in these traditional coppice stands. In this respect they can provide precious information concerning the evolution after several rotations. The species studied are quite diverse, from the genera Alnus, Betula, Carpinus, Castanea, Populus, Robinia, Quercus… Most studies concern Castanea sativa and Carpinus betulus, The traditional rotation length lies around twenty years. However, quite a large amount of stands are over-aged and may remain up to thirty or fourty years, or even longer. Some experiments have led to shorter rotations. In most cases the number of previous rotations is unknown. This type of silviculture has been practised for centuries: in Roman literature one can find the expression “sylvae caeduae”. At each clearcut, some stumps may die, and new stumps appear (from seed or from root suckers). It is therefore very difficult to trace the exact age of a stand. The number of stumps per hectare can vary between 1 000 and 10 000, and the number of sprouts per stump depends mostly on the age of the sprouts. The number of stems per hectare goes from 1 000 up to 20 000, depending of course on the age of the stems and the number of stumps. The size of plots used for yield estimations is very variable, mostly in relation to the purpose of the study. In some very homogenous stands, from 3 to 15 trees were considered as sufficient, whereas in other cases up to 50 trees were sampled. This corresponds to mensuration areas ranging from 100 to 3 000 square meters. These plots are usually situated inside regular stands covering a much wider area (several hectares). The estimated current annual biomass production can go from 0.15 up to 1.0kg/m2. The mean annual increment figures vary from 0.1 to 0.7kg/m2 in the studied stands. 3. RECENT PLANTATIONS Many scientists, mostly in France, Sweden, USA and Canada, have been interested in the coppicing ability of numerous highly productive species. This type of silviculture provides two main advantages: a rapid juvenile growth, and the presence of a root system which can remain for several rotations, lowering the cost of establishment. The species studied are here again very diverse. The most common are Populus, Salix and Eucalyptus species, clones or cultivars. Other genera are Platanus, Quercus, Alnus, Liquidambar, Liriodendron, Fraxinus, Robinia. The rotation length lies in most cases under 10 years, even under five years. The number of previous rotations is usually very small, as most studies have begun only recently and very few plantations have been coppiced more than once. Some stands are still single-stemmed, many are in their first coppice rotation. Some have however had three or four rotations, going up to fourteen one-year rotations in one case.

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The spacing is usually around 2.5m to 3.5m between rows, going from 0.5 up to 2.5m in the rows. Some closer or wider spacings have also been studied on very small plots, corresponding to a number of stumps per hectare ranging between 300 and 40 000. The size of plots used in these studies varies in a very wide range, from 9 trees planted in containers, up to an area of one hectare or more. The usual size of individual plots remains between 30 and 600m2. The number of sample trees also varies very widely, from a few individuals up to the whole plot being measured. A common figure lies between 20 and 30 individual trees being measured precisely. The estimations of annual biomass production vary in a much wider range than with traditional coppice: from 0.03 up to 2.4kg/m2. The most common estimated productions are around 0.5 to 1.2kg/m, however quite a few studies give figures between 1.5 and 2.kg/m2. It should be noted that yields higher than 1.5kg/m2 have only been found on small plots (less than 50m2), and that up to now no results have been given concerning individual plots of more than 800m2. It is therefore difficult to extend the given figures to larger plots. 4. RESEARCH OBJECTIVES It is interesting to consider what is the purpose of the studies described here. Most of them are relatively technical: – different spacings – rotation length – herbicides, fertilizers, pesticides – genetics: clones, cultivars, species, hybridization – harvesting date – cutting methods (chain saw, shearing,…) – thinning treatments – more generally, intensive or extensive cultivation. They concern the effect of various treatments on yield, the objective being either “undifferenciated biomass”, or more specifically, fiber, energy, chemicals, or animal feed. Most studies are undertaken on agricultural land, or quite intensive nursery or experimental plots. Few are concerned with marginal soils. Some studies in traditional coppice are directed towards a survey of existing resource and yield. It should be noted that very few studies are concerned with the comparison between coppice and single-stem production, or with the study of the particularity of coppice: i. e. several stems on one single root system, a root system remaining for many rotations, root or stump regeneration,…

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5. CONCLUSIONS This paper summarizes rapidly the answers to an enquiry sent out to scientists known by IUFRO to be interested in short rotation coppice. The results given here are far from being exhaustive, mainly for two reasons : – some scientists have very many experimental plots and have only summarized their answers in the enquiry; – many other experimental plots have been omitted, as some researchers did not receive the enquiry, and some did not answer. This is however a contribution which may help scientists interested in coppice production to communicate via IUFRO working party S1.05–10. It is very difficult to compare data collected in different ways, on different soils or climatic regions. The next step of this working party should be to try to acquire more knowledge concerning the particularity of coppice compared to single-stemmed trees. It should also be to suggest a standardization of methods of estimation and of units : some data are given in volume, some in wet biomass, some samples are dried at 60°c, others at 85 or 105°c. American, Imperial, or metric tons, acres, hectares, or square meters are used. If most scientists are well aware that data obtained on small plots are only useful for comparisons, another objective of our working party is to make it quite clear to “decision-makers” that one should be very cautious in extending these figures on a perhectare basis to large areas or regions.

APPENDIX List of countries represented in IUFRO S1.05–10 Country Members Australia Belgium Canada China Finland France Ireland Italy New Zealand Senegal South Africa Spain Sweden Uganda United Kingdom United States Zambia

1 1 7 1 1 10 1 1 1 1 2 1 3 1 5 8 1

SHORT ROTATION FORESTRY FOR ENERGY PRODUCTION M.Neenan An Foras Taluntais (Agricultural Research Council) Oak Park, Carlow, Ireland. Summary The yield of short rotation forestry is determined by a number of factors such as species, spacing, length of growing cycle and soil fertility. All of the these factors interact with one another. A number of these variables have been tested in a series of field experiments begun in 1977. On soils of very low fertility only conifers, which will not resprout, will survive. On slightly more fertile soils the most promising species are Salix, Populus and Alnus. Yields of up to 18t ha−1 annum−1 of dry matter have been obtained on a 3 or 4 year growth cycle. Most species so far tested suffer from some biological disadvantage. On wet soils, Salix aquatica gigantea outyields all other species. Alnus fixes nitrogen at rates of 105 to 212kg ha−1 annum−1. However the species is slow to recover from harvesting. In the young stage, some Populus clones are prone to frost injury. There are indications that the clone Fritzi Pauley may not be tolerant of coppicing.

1. INTRODUCTION In this Investigation, the objective is to utilise the methods of agricultural technology to produce an energy crop. Theoretically, many species of plants can be used, but there are obvious advantages in using a crop which is relatively high in dry matter, and perennial in growth habit [1][2][3]. Short rotation or coppice forestry is one such crop. The efficiency of production depends very much in matching the species to the site. The availability of land is complicated by sociological and democratic factors; nevertheless it can be assumed that only land which is uncompetitive for agricultural production, will be devoted to forestry. Such land can be infertile in different ways e.g. poor soil cover, located at high elevations, or rendered infertile by poor drainage conditions. On very poor soils only coniferous species will survive. If planted at close spacings i.e. less than 1m apart, these species will provide an acceptable yield on a 7 to 10 years rotation. Planting accounts for approximately 20 per cent of the cost of the fuel. Because of this, and the earlier return on investment [4], coppice forestry has certain economic advantages. From studies begun in 1977, three main genera, Alnus, Populus and Salix, were chosen as having the best possibilities.

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2. MATERIALS AND METHODS Beginning in 1977, a series of species trials were carried out on different soils. Coppicing, spacing and other trials were carried out at 3 centres. A series of field and laboratory trials on Alnus was conducted by O’Neill [5] at Johnstown Castle Station, Wexford. The willows and the poplar Fritzi Pauley were Propogated from cutting. To allwo for mortality, these were spaced 0.3×1.0m, as against 0.6×1.0m for Raprooted plants. Survival of the cuttings was higher than expected. A late severe frost in May 1984 provided a useful opportunity to assess the hardiness of some Populus clones. 3. RESULTS A number of species including Betula pubescens, Castanea sativa. Fraxinus excelsior, gave Poor yields. The yield results obtained with the more promising species on a wet mineral soils are shown in Fig.1. It will th seen that the yield of copplce is substantially higher than that of the primary growth, and that in some species this is being maintained in the second coppice. In 1982 a trial with 29 poplar Clones was established on a peatbog. In the second year when the plants were under 2m high, many clones were severely damaged af a frost of −5.0°C Which occurred when the trees were almost in full leaf. The most tolerant clones were TT32, Konk, and a German hybrid, P.maximowiczii×P.berolinsis (Table 1). It is believed however that this is only a problem at the establishment stages. Nevertheless, it is prudent to use only genetic material whic comes from an appropriate climatic zone.

Fir. 1 Equivalent annual yields of dry matter from Salix vimimilis (S.c.) S. dasyclodos (S.d), Salix aquatica gigantea (S.a.g.) Polulus cv. Rap, Populus cv. Fritzi Pauley (FP) planted in Spring 1977 on wet mineral soil at Carlow.

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TABLE 1: Effect of −5°C air frost on May 13, 1984, on Poplar clones. 1=total failure; 2=killed and resprouting from base; 3=moderate damage to foliage; 4=slight damage. Planted as rooted plants 21 April 1983; the Muhs hybrids were grown from seed. Clone

Origin

HP206 HP510 TT32 Rap Donk Vrecken Unal 7 Muhle Larsen

U.S.A. P.clarkowiensis×P.caudina do. P.maximowiczii×P.trichocarpa U.K. P.tachamacha×P.trichocarpa Netherlands P.trichocarpa×P.deltoides do. P.deltoides×P.trichocarpa do. Belgium Fritzi Pauley×P.deltoides P.trichocarpa×P.trichocarpa (Washington State) (Idaho)

71009/1 72040/2

Parentage or type

Frost damage index 3.5 2.8 5.0 4.3 4.7 2.5 1.6 3.3 1.8 3.0

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72040/5 Tannenhoft 2.011 71015/1 Oxford Muhs hybrid 1981/2 1981/3 1981/4 1982/1 1982/2 Muhs 1982/3 Fritzi Pauley

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W.Germany P.canadensis×P.serotina (Marialandica) P.maximowiczii×P.berolinsis Bel gium P.deltoides×P.trichocarpa U.S. P.maximowiczii×P.berolensis W.Germany P.tremula×P.tremuloides

2.0 3.8 5.0 2.8 4.2 2.8

do. do. do. do. W.Germany U.S.A. T.trichocarpa

2.0 1.7 2.2 2.0 1.7 2.8

"" "" "" "" ""

The spacing of plants is a difficult problem because there is an interaction with the length of coppicing cycle. A spacing of 0.3×1.0m gives high initial yields, but this is not sustained in some species such as poplar Fritzi Pauley which showed a high mortality at the second coppice (Fig.2).

Fig. 2 Plant populations in a coppice cycle from a plantation made in Spring 1977

4. DISCUSSION The most important consideration is the species. of the 38 species of Alnus which exist, only four, A.glutinosa, A.incana, A.rubra and A.cordata have been tested on a range of soils. The species recovers slowly after cutting, and makes little growth in the first coppice year. A.rubra tends to die off to the extent of 80% ater cutting. This is believed due to genetic variation. O’Neill [5] found that these species fix nitrogen at rates varying from 105 to 212kg per annum, but exotic species were less efficient in this regard [6]. In the case of Salix, testing has so far been confined to European types of which about 300 species and many more hybrids and clones exist. It has been found that in wet soil conditions, the hybrid, Salix aquatica giqantea, outyields every other species, giving 18.00t ha annum of dry matter. It is also highly resistant to the leaf beetle Phyllodecta vulgatissima to which other Salix species are sensitive. The species is however extreMely

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crooked and branched and therefore somewhat difficult to harvest. Another natural hybrid, S.dasyclados, is equally high yielding on reasonably good soil, but is prone to leaf beetle attack. Only one clone of S.viminalis, an Irish one, was tested. This proved low yielding as did S.smithiana. Two poplar hybrids, Rap and TT32, and P.trichocarpa Fritzi Pauley, were tested initiallly. TT32 is not well adapted to adverse soil conditions. Although Salix aquatica gigantea outyields all other species so far tested, there are indications that some of the European hybrid poplars may come very close to attaining the same yields. It has been shown [7] that species differ but slightly in calorific value, but that bark has a higher heating value than wood. This gives a slight advantage to small dimensional wood, provided it is allowed to dry out before burning. Harvesting small dimensional wood creates some problems but these appear to have been overcome in Finland where more than one hundred wood fired plants ranging in size form 0.5 to 1.0 MW are now in operation [8]. Possibly one of the main obstacles to the commercialisation of fuel wood is the lack of standards and quality specifications [9]. This, however, is an institutional and administrative problem. REFERENCES [1] NEENAN, M. (1980). The production of energy by photobiological methods. Energy. Commission of European Communities ESBN–92–825, 1982–1, p.141–167. [2] LAVOIE, G. and VALLEE, G. (1981). Inventory of species and cultivars potentially valuable for forest biomass production NE.1981–17. National Swedish Board for Energy Source Development Box 1103, S–16312 Spanga, 43 pages. [3] KHALIL, M.A.K. and A.W.ROBERTSON (1984). Conifers for Biomass production. Vol.I and II. Forest Energy Program, Canadian Forestry Service and I.E.A. [4] NEENAN, M. and G.LYONS (1981). The production of energy from short rotation forestry. Energy from Biomass, Vol.1, Series E. Proc. Contractors Meeting, Copenhagen, 1981. p.47–51. [5] O’NEILL, P. (1984). Studies on the symbiotic performance of the nitrogen fixing tree species and microbiological aspects of the nitrogen fixing endophyte. Ph.D. thesis, National University of Ireland, 1984. [6] O’NEILL, P. and P.M.MURPHY (1983). Nitrogen fixation and dry matter yield in Alder species. Research Report, Soils Division, 1983. An Foras Taluntais, p.23. [7] NEENAN, M. and K.STEINBECK (1979). Calorific values for young sprouts of nine hardwood species. Forest Sci. 25, No.3, pp.445–461. [8] HAKKILLA PENTTI (1984). Forest chips as fuel for heating plants in Finland. Folia Forestalia 586, Finnish Forest Research Institute, Helsinki. [9] NEENAN, M. (1984). Biomass qualities for energy conversion with particular reference to the combustion of wood. Report No.2. Biomass growth and producion. International Energy Agency Forest Energy Agreement, Ministry of Natural Resources, Ontario, Canada.

UNE PLANTE ENERGETIQUE A CYCLE COURT LE GENET: CYTISUS SCOPARIUS P.TABARD Laboratoire de Bioclimatologie I.N.R.A. Domaine de Crouelle 63039 Clermont-Ferrand-France Summary Grazing areas of Central France (Auvergne) are composed of about 250 000 hectares of moor land, waste land and low yield pastures. With the purpose of rehabiliting these areas, it would be possible to sow 20 to 25% with broom as part of a rotation, as an energetic plant. Life duration of a broom canopy is about 12 years. Its evolution goes through several stages lasting 2 to 4 years each: setting of the plants, growth, decay, death and resowing. During maximal growth, toward the 7th year and at 1 000m altitude, a dense population yields 50 Tons dry matter per hectare. With P.K fertilization, this crop may yield up to 15 Tons per hectare and year. The broom being a legume brings about 100kg of nitrogen/year/hectare, therefore it is an interesting rotation head. Broom which has a calorific power of about 4 400 Kilocalories/kg of dry matter has long been used as fuel. A survey of biology, yield and possibilities of utilization has been undertaken to bring up conditions of a rationnal cultivation.

1. INTRODUCTION Le mode de culture en moyenne montagne d’Auvergne a évolué sensiblement depuis le début du siècle. Le système agro-pastoral ancestral s’est progres sivement modifié par suite de la désertification rurale avec une réduction sensible du troupeau ovin d’où, un envahissement progressif des prairies, pâturages et même terres de cultures par les broussailles et les genêts. Ces derniers sont souvent dominants et forment parfois une couverture totale sur des grandes étendues, spécialement dans les zones a statut collectif. Il est possible d’estimer ces surfaces a 10% de la surface agricole totale soit 250 000 hectares. Au début du siècle, beaucoup de ces parcelles étaient soumis au système d’assolement suivant : – semis de genêts avec pâturage pendant 4 à 5 ans, – culture de céréales pendant 3 ans.

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Les genêts fournissaient un fourrage d’appoint pour le bétail, du bois utilise pour le chauffage des fours a pain et enfin un precedent cultural intéressant grace a la fixation de l’azote atmosphérique. Ces différentes constatations nous ont amené a rechercher un système rationnel de remise en valeur d’une partie de ces friches avec des cultures de genêts utilisées comme plantes productrices de biomasse énergétique et cultures améliorantes. 2. BIOLOGIE: DESCRIPTION GENERALE Le genêt appartient à la famille des papillonacées, il se rencontre dans presque toute l’Europe spécialement sur les sols acides (pH 5 à 6) sauf ceux humides en permanence. Sa durée de vie est de 10 à 12 ans, à l’état adulte il peut atteindre 2 à 3m. Il possède de nombreux rameaux chlorophylliens cannelés qui restent verts toute l’année. Les feuilles sont de deux types : – trifoliées et pétiolées à la partie inférieure du rameau – simples et sessiles à l’extrémité du rameau. Elles axilent toutes un bourgeon. La floraison a lieu de mai à juillet suivant l’altitude et ne s’observe que sur des pieds de 3 ans ou plus. Les fruits sont des gousses velues de 3 à 4cm de long contenant 8 à 10 graines. Ces gousses s’ouvrent par déhiscence élastique sous l’action du soleil ce qui provoque la dispersion des graines. Ce phénomène pose d’ailleurs un problème pour la récolte. Si les graines semblent pouvoir se conserver très longtemps dans le sol il est très difficile de les faire germer. A l’état naturel, le renouvellement se fait le plus souvent à la suite de la destruction du vieux peuplement par le feu ou après un défrichement. Même dans ces conditions il faut au moins 2 ans pour obtenir une couverture totale. L’appareil racinaire est formé d’un pivot de 20 à 25cm de long entouré d’un important chevelu sur lequel on observe des nodosités en quantité importante. Les mesures montrent que les genêts peuvent fixer environ 100kg d’azote atmosphérique par an et par hectare (1). 3. ESSAIS CULTURAUX 2.1 Essais en conditions contrôlées. 2.1.1 Germination des graines. Le pouvoir germinatif des graines est très faible et, comme dans le cas de nombreuses légumineuses, celles-ci semblent subir une inhibition tégu-mentaire très importante. Sans traitement la germination est toujours infé-rieure à 5%, aussi divers procédés ont-ils été expérimentés pour essayer d’améliorer cette capacité germinative :

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– trempage des graines dans l’eau à différentes temperatures 50–80 et 100° pendant 5 et 10mn, – scarification, – traitement par le froid à−3° C, −30° C et trempage dans l’azote liquide, – traitement a H2SO4 pur pendant 2–4 et 24 heures. C’est la scarification et surtout le traitement par H2SO4 pendant 4 heures qui donnent les meilleurs résultats (80% de germination). 2.1.2 Mesures de la photosynthèse et bilan hydrique. Des mesures de photosynthèse ont été effectuées sur un couvert dense de genêts de 1 an (Fig. 1). La réponse au rayonnement est largement supérieure a celle obtenue sur une culture de graminées placée dans les mêmes conditions. Le bilan journalier atteint 50 grammes de CO2 par m2 pour une radiation de 25M. joules. La surface foliaire, très élevée (LAI >5) ne paraît avoir qu’une incidence limitée sur la photosynthèse. L’effet temperature est très important, on constate un palier des que celle-ci atteint 23 à 25°C. Par contre, par température inférieure à 0°C la photosynthèse est loin d’être négligeable (6,5g de CO2 absorbé pour un rayonnement de 1,8M.joule par jour). Les besoins en eau sont toujours importants et ont dépassé 5 1 par m2 et par jour dès que l’éclairement atteignait 11M.joules par jour. 2.1.3 Croissance et production de biomasse Dans des conditions optimales d’alimentation hydrique et minérale ce même peuplement de genêts a eu une croissance lente en début de vegetation, maximale pendant l’été puis un ralentissement progressif avec arrêt de la croissance fin novembre. (Fig. 2). Un prélèvement effectué en fin de vegetation a donné 1,5kg de biomasse par m2. 2.2 Essais sur peuplements naturels en altitude (2). Les contrôles sur peuplements naturels presentent une grande hétérogénéité tant sur l’âge des genêts que sur la taille et la production de biomasse. L’influence du pacage des ovins réduit sensiblement la croissance par suite de l’épointage des pousses et d’une casse importante de rameaux. 2.2.1 Croissance Dans un peuplement naturel on observe 4 périodes végétatives importantes; l’implantation des genêts d’ une durée de 2 à 3 ans, survie d'une croissance rapide pendant 3 à 4 ans, puis d’un début de sénescence avec apparition de rameaux secs a la base, seuls les houppiers terminaux possèdent des rameaux fonctionnels, et enfin la mort et un nouveau resemis.

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Des mesures effectuées sur un peuplement de 2 ans dont une partie a reçu un apport d’engrais phospho-potassique à la dose de 200 unités par hectares montre l’action des engrais minéraux sur la croissance qui passe de 1 à 3 (Fig. 3). 2.2.2 Production de biomasse. Des mesures de production réalisées sur un peuplement adulte situé à 1000m d’altitude pendant 3 ans ont donné les rendements suivants: Age Matière sèche/ha Production an/ha 1982 6 1983 7 1984 8

33,7 Tonnes 50,7 T 53,4 T

5,6 T 7,2 T 6,7 T

3. RECOLTE DES GENETS L’exploitation peut être réalisée dans de bonnes conditions avec un tracteur de 40 à 50 CV et une débroussailleuse classique sous reserve que celle-ci soit pourvue d’une sole lisse et d’un dégagement lateral suffisant pour évacuer les produits de coupe. Le séchage est assez rapide, le genêt étant très aéré. En 15 jours a l’air libre il perd plus de 80% de son eau et pourrait alors être compacté. 4. UTILISATION DU GENET Le genêt se situe parmi les meilleurs combustibles ligneux avec un PCI de 4.450 Kcalories/kg et un taux de cendres de 1%. Les résultats de combustion realises sur une chaudière type de CEMAGREF sont du même type que ceux effectués avec de la paille. Le rendement thermique est de 63% environ. 5. CONCLUSION Le genêt se situe en bonne place comme culture énergétique, il cumule plusieurs avantages: – un cycle de revolution court – un pouvoir calorifique élevé – une fixation d’azote atmosphérique. Un système d'assolement du type suivant pourrait être envisage. – Implantation d'une genêtière et croissance des plantes pendant 6–7 ans – récolte de la biomasse au maximum du développement – cultures fourragères pendant 3 à 4 ans.

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Malgré ces aspects positifs le développement et l’utilisation de cette biomasse ne peut s’envisager que dans un contexte de petites regions et dépendre de decisions prises au niveau local en fonction de critères économiques et socio-culturel. REFERENCES (1) ROUSSEAU S., LOISEAU P. (1982). Structure et cycle de développement des peuplements à Cytisus scoparius dans la Chaine des Dômes. Acta Oecologie applica. Vol. 3 n°2, 155) 168. (2) WILLIAMS P. (1981). Aspects of ecology of broom (Cytisus scoparius) in Canterbury, New Zeeland. New Zeeland journal of Botany, Vol. 19, 31–43.

fig 1. Relation entre le rayonnement et l’assimilation nette

fig 2 Croissance en conditions controlées Genêts de 1 an

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fig 3 Croissance d’un peuplement de genêts de 2 ans . (altitude 1000m)

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ENERGY AND BIOMASS OF PIEDMONT HARDWOODS 1/ M.A.Megalos, Research Assistant L.Horton, Research Assistant D.J.Frederick, Assoc. Professor School of Forest Resources North Carolina State University Raleigh, North Carolina, U.S.A. A.Clark, Research Scientist U.S. Forest Service Athens, Georgia, U.S.A. and D.Phillips, Project Leader U.S. Forest Service Clemson University Clemson, South Carolina, U.S.A. Summary Piedmont hardwoods in the southeastern United States represent a large, available resource for biomass energy production. Covering a land base of over 11.3 million hectares, hardwoods comprise 62% of the total standing biomass in the Piedmont province, a staggering 1.18 billion metric tonnes. Most stands are degraded because of past harvesting practices but can be rehabilitated by using conventional harvesting and wholetree chipping, planting and/or natural regeneration. There is a large potential market for energy wood in the Piedmont province, including both forest and nonforest-based industries. This paper outlines a regionwide study in the Southeast for estimating the biomass, nutrient and energy yields of natural stands. Current data are reported for the Piedmont province.

1. INTRODUCTION The southern Piedmont of the United States consists of over 17.8 million hectares within the states of Virginia, North and South Carolina, and Georgia. The province extends 720k northeast to southwest, with a maximum width of 200k. Elevation ranges from about 100m at the eastern fall-line to 400m above sea level at the western boundary of the Appalachian province. Soils are primarily highly weathered ultisols which are inherently fertile. Past agricultural practices have removed much of the original topsoil and reduced

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productivity. Agricultural land abandonment has resulted in the reestablishment of natural pine-hardwood forests and the stabilization of these highly erodable soils. Nearly 9% of the total U.S. population resides in the southern Piedmont states, where the majority of citizens are centered around the four state capitals and other major cities near or on the fall-line, between the Piedmont and the Coastal Plain. The Piedmont region is typified by an ample work force, fine transportation infrastructure, and a multitude of processing facilities. The forest industry presently uses most of the annual hardwood harvest for products and fuel, but in the future other sectors will increase their share of the market as imported oil prices escalate. 1/ Paper presented at the Third EC Energy from Biomass Conference, Venice, Italy. March 25–29, 1985

2. THE HARDWOOD RESOURCE More than 11.3 million ha, roughly 64% of the total land area in the southern Piedmont, is classified as commercial forest. (2) of this area, 6.8 million ha (59%) is allotted among three hardwood types—oak-pine, upland hardwood, and bottomland hardwood. Hardwood biomass distribution among forest types averages 62%, with slightly greater values in the northern regions and lesser values to the south. Total green weight estimates of aboveground hardwood biomass is 1.18 billion metric tonnes. (2) The hardwood resource can be divided into two major categories—the Upland and the Bottomland forest site types. Upland sites are characteristically mesic and relatively low in fertility; common species include red oak (Quercus rubra), black oak (Q. velutina), white oak (Q. alba), red maple (Acer rubrum), and black cherry (Prunus serotina). Bottomland sites are more fertile/ slightly more basic and hydric in nature. Bottomland sites have the highest productivity rates of any land in the southern Piedmont and represent the best sites for hardwood growth. Typical species include sycamore (Platanus occidentalis), willow oak (Q. phellos), water oak (Q. nigra), American elm (Ulmus americana), and green ash (Fraxinus pennsylvanica). Currently, hardwood growth exceeds harvest by about 2 to 1. Much of this growth is in lower-quality species unsuitable for solid wood products. (3) 3. POTENTIAL FOR BIOMASS AND ENERGY Many hardwood stands show the effects of repeated harvests and past neglect. (6) The harvesting of only pine, leaving understory hardwoods and residuals for the next rotation, has adversely affected quality and potential of many hardwood stands. One possible solution for stand rehabilitation is whole-tree harvesting and either replanting pine or allowing the stand to regenerate naturally. Whole-tree harvesting is an excellent method for utilizing low-grade timber and replacing or upgrading forests of poor quality. Harvesting degraded hardwood stands for biomass can be profitable but, when coupled with conventional harvesting regimes, the potential gains are substantial.

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Improved harvesting techniques can increase forest biomass yield by 30 to 57% in conjunction with conventional practices. (7,9) Increased mechanization and overall operability of hardwood sites in the southern Piedmont point to the future potential of harvesting hardwoods for energy. Presently forest industry is the leader in the use of biomass and mill residues for energy needs and is moving toward energy self-sufficiency. The forest industry is successful in using wood energy because of an established procurement system and a readily available supply. Small-scale biomass energy use and facilities, including certain governmental institutions or small manufacturing facilities, are becoming increasingly common. 4. SOUTHEASTERN HARDWOOD FOREST BIOMASS, ENERGY AND NUTRIENT STUDY Since 1979 the North Carolina State University Hardwood Research Cooperative,1/ in conjunction with the U. S. Forest Service, Southeastern Forest Experiment Station, has been sampling natural stands of hardwoods 1/

The North Carolina State University Hardwood Research Cooperative consists of 17 forest industries and public organizations which own or control 10 million ha of land int he southeastern United States.

in the Southeast. Plots have been established in even-aged (10-, 20-, 40- and 60-year-old) stands on various site types, including bottomland and upland. Numerous plots and replications have been located throughout the three major provinces—Coastal Plain, Piedmont, and Cumberland Region west of the Blue Ridge. Area plots (.04-ha have been established, with all aboveground vegetation cut and weighed. Supplemental trees outside of area plots have also been sampled to develop prediction equations for measured parameters. Samples are used for determination of green and dry biomass, nutrient and energy content of total trees, components and understory vegetation. (8) Listed below are mean energy yields for major species from 10-yearold stands on Piedmont upland and bottomland site types (Table 1).

Table 1. Average energy yields for major species on 10-year-old upland and bottomland Piedmont sites, by component Species Black cherry Green Ash Yellow-Poplar Sweetgum Mean

10-year-old Upland Site Composite (Wood & Bark) Branch Foliage ----------------------------cal/g----------------------4592a2/ 4264a 4408a 4584a 4503

473la 4364a 4l99a 4514a 4493

10-year-old Bottomland Site

4836a 4754a 4688a 4549a 4652

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Composite Branch Foliage ----------------------------cal/g----------------------American Elm Black Oak Red Maple Sweetgum Mean 2/

4561a 4499a 4490a 4486a 4504

4562a 4545a 4495a 4413a

46l2bc 4863a 4746ab 4457c

Numbers followed by the same letters are not significantly different at the .05 level.

The greatest variability in energy values for Piedmont hardwoods occurs within the foliage component (Table 1). All other comparisons between site types or among components within site types are nonsignificant. Similar relationships have been reported for hardwoods growing in the Coastal Plain. (5) Currently, estimates are available for Coastal Plain forests. (4,8) Piedmont samples are being analyzed and field sampling is complete for the Cumberland Region. Data compiled from these studies will comprise the most detailed biomass, nutrient and energy information available for southeastern hardwood forest. 5. CONCLUSIONS The potential for harvesting Piedmont hardwoods for energy production is great. Presently only 37% of all harvested hardwood biomass is being utilized. (2) This represents a gross underutilization of southeastern Piedmont forest productivity. In the past the forest industry and economics have undervalued the worth of the hardwood resource. However, market prices and new product advances are causing hardwood markets to expand. New pulping technologies (60:40 pine-hardwood mix) and the increased use of hardwoods in composite boards are evidence of this trend. Increased hardwood demand can be a positive force in rehabilitating and upgrading present stand conditions. Conventional harvests combined with whole-tree chipping of the residual stand for energy wood could well be the most economic and silviculturally sound option available. Whole-tree chipping can accomplish residual control, site preparation, and in many cases make a marginal harvesting operation profitable. The potential for increasing stand quality, the added value from harvesting energy wood and proximity to strong markets suggest continued growth of Piedmont hardwood markets. REFERENCES (1) BARRETT, J.W. (1980). Regional silviculture of the United States. 2nd Ed. J.W.Wiley & Co., N.Y. 528 pp. (2) BECHTOLD, W.A. and PHILLIPS, D.R. (1983). The hardwood resource on nonindustrial private forest land in the southeast Piedmont. Res. Pap. SE-236., USDA For. Ser., SE For. Expt. Sta. 19 pp. (3) BOYCE, S.G. and KNIGHT, H.A. (1980). Prospective ingrowth of southern hardwood beyond 1980. Res. Pap. SE-203. USDA For. Ser., SE For. Expt. Sta. 33pp.

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(4) GOWER, S.T., FREDERICK, D.J. and CLARK, A. (1984). Distribution of energy in differentaged bottomland forests. For. Ecol. Manage. 9:127–146. (5) GOWER, S.T., FREDERICK, D.J. and CLARK, A. (1982). Caloric content estimation and distribution in seven bottomland hardwood tree species growing in natural stands in the South. IN Proc.,4th Central Hdwd. Conf., Lexington, Ky. (6) KELLISON, R.C., FREDERICK, D.J., GARDNER, W.E. (1981) A guide for regenerating and managing natural stands of southern hardwoods. Bull. 483. N.C. State Univ., Ag. Expt. Sta. 24 pp. (7) KNIGHT, H.A. and McCLURE, J.P. (1981). Multiresource inventories--forest biomass in South Carolina. Res. Pap. SE-230. USDA For. Ser. (8) MESSINA, M., GOWER, S.T. , FREDERICK, D.J., CLARK, A. and PHILLIPS, D.R. (1983). Biomass, nutrient and energy content of southeastern wetland hardwood forests. Hdwd. Res. Co-op. Ser. #2. 28 pp. (9) WELCH, R.L. (1980). Living residues in the South Atlantic states. For. Prod. J. 30(6):37–39.

COPPICED TREES AS ENERGY CROPS M.L.PEARCE Forestry Commission, Research & Development Division U.K. Summary Foresters are only now beginning to evaluate wood production in terms of ‘biomass’. This project is collecting data from coppiced tree crops with the singular object of maximising production. The end product has no dimensional specifications other than tonnes of fuelwood over a minimal harvest rotation. The system is ‘renewable’—that is several harvests from an initial crop planting. Early results indicate that production levels will be dependent upon the chosen tree species and the crop spacing. It is too early to determine the effect upon production of the harvest rotation period. Highest levels of production so far attained from experimental plots are 23 tonnes (fresh) ha−1 yr−1.

1. INTRODUCTION A series of experimental plots are situated in Southern Britain to reflect broad environmental zones—hot/dry to cool/wet, Each experiment includes a range of tree species to match the site and have been established at two crop densities—10,000 plants/ha and 2,500 plants/ha. The matrix of species and densities are further divided to test the effect of harvesting rotation upon levels of production—will the crop produce a better annual increment if left two or four years between successive harvests? An additional variable has arisen which was not designed into the experiment, and can crudely be described as the ‘start-up’ time for the production system, There has occurred variation in the time lapsed between the initial planting of the crop (as maiden trees) to the optimal time for the first coppice cut (when the single stem maiden tree is cut off at ground level) to allow multiple coppice shoots to develop. The periods have ranged from 1 to 4 years, and the variation can be attributed to species, site nutrition and environmental factors such as annual precipitation and temperature. In the results which follow, the ‘start-up’ time is shown by the difference between stool age (i.e. planting date plus years to any particular harvest) and coppice age (i.e. interval between harvests). (Fig. I). Some data has been included for production during the ‘start-up’ period (described as ‘Maiden’ in Fig I) but it must be remembered that this represents production from single stem maiden growth before coppicing has taken place. The hypothesis of this project, expects sustained production from coppiced trees to be greater than that from maiden trees.

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2. RESULTS It is far too early in the life of these experiments to make any judgements about production levels, but the data available (Fig I) does show some interesting trends. There is no data yet for alder and Nothofagus, but of the remaining three species, poplar is showing the higher range of production levels. The exception to this is where Eucalyptus has been grown for 4 years before coppicing, its annual production increment is the greatest at 23.26 tonnes (fresh) ha−1 yr−1. In comparing these data, it must be remembered that they are derived from different sites and different growing seasons (environment). The most useful comparisons at this time are for the three assessments from the same site (L.A.R.S.) which indicate an effect on production of the two crop densities. The two graphs (Fig. II) express the production levels for poplar and Eucalyptus on the same site, but separate the two crop densities. At this early stage, these graphs show an expected trend, that neither species has fully exploited the space available at the lesser crop density, and that production from the higher density crop is the greater. In the final analysis it will be the calorific value of biomass production that will determine its economic value, and to this end the data in Fig. I is shown in both fresh weight and dry weight values. The latter figures have been obtained by oven drying subsamples of the freshly harvested biomass from the experimental plots. It is a little surprising that there is not a greater variation in the % fresh weights—but again, it must be remembered that this is limited data from young material only. To evaluate the calorific value of the dry tonnes of biomass produced, a conversion factor of 20GJ per dry tonne can be used, It has been found that this value does not change significantly between species of tree, but with more data it may be found to vary with age of tree (or coppice shoot!) 3. DISCUSSION It must be patently obvious from the above, that it is too early in the life of this project to make any strong predictions about the value of biomass production from coppice crops. But, even though the existing values are extrapolated from small experimental plots, they represent encouraging annual production increments which will compare favourably with conventional forestry production in the United Kingdom. This of course, is largely due to the fact that production is not constrained by dimensional specifications, and that the hypothesis of this project expected short rotation coppice to produce a higher annual increment than conventional forestry. What is now needed, is time to build up substantial data from each of the experiments, which will then show a range of values for species, crop density and site.

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Figure II

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FAO’S ACTIVITIES ON INDUSTRIAL WOOD-BASED ENERGY M.A.TROSSERO Forest Industries Division—Forestry Department Food and Agriculture Organization of the United Nations Summary The paper analyses the activities of FAO on wood-based energy which are being implemented by the Forestry Department since this subject has been stressed as a priority area for action in many international meetings such as the 21st FAO Conference. The energy situation in developing countries and the role of wood energy is briefly described in order to accelerate the transition from non-commercial use of wood energy to commercial energy schemes specially through the promotion of wood-based energy systems in rural industries and village activities. Finally, the main FAO strategies for action implemented through the Regular Programme and Field Projects are briefly mentioned in order to reach the ambitious targets of the Nairobi Plan of Action.

1. INTRODUCTION Energy is one of the most important commodities required to satisfy the physical needs of mankind. Over the years, Limits in the availability, technological changes, location, prices and use of certain fuels have necessitated the search for new energy alternatives. Furthermore, the growing population, the continuing industrialization and the economic growth of countries have Led to an increasing demand for commercial sources of energy. The growth of energy consumption since 1860 has been essentially exponential and during the Last forty years has grown at an annual rate of about 5 per cent. Developed countries, comprising only 28% of the world population, use 82% of the total commercial energy, so that, the per caput consumption of energy is 11kW in the USA, 5kW in Germany, while developing countries consume only 0,2kW. Although fuelwood and charcoal provide only six per cent of the world’s energy supply, around half of the world population depends on wood for its energy needs, which is mainly considered as a non-commercial source of energy. Traditionally fuelwood was considered a free good provided by nature. However, due to the expansion of agriculture and other reasons, fuelwood is becoming scarcer and people are forced to devote more time or money to obtain it. Fuelwood increasingly becomes an economic commodity with more and more people involved in its exploitation and trade. For this reason, developing countries are compelled to ensure a sustained supply of wood energy under a structured commercial basis in order to satisfy the needs of poor

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people and to improve their Living conditions, while wood energy can also be used for industrial purposes to substitute imported fossil fuels. This Latter use would provide a number of social and economic benefits such as: – creation of new jobs – increase the profitability of local resources – save foreign exchange − distribute money from the urban to the rural sector − improve the welfare and life quality in rural areas − promote the settlement in rural areas

2. THE WOOD ENERGY TRANSITION The economic difficulties that most countries are facing, together with high oil prices, are bringing about a period of energy transition from an economy based primarily on hydrocarbons to one based increasingly on new renewable sources of energy, although it is expected that oil and gas will continue to dominate the market during this century. In some of the Less developed countries woodfuels are covering about 90% of their primary energy consumption which is obtained from their immediate environment without payment and is commercialized in non structured economic markets, so that, in areas where forest resources for energy use were previously plentiful they are now becoming scarse. In this situation, woodfuels increasingly become an economic commodity commercialized under well established rules of trade. If the economic circumstances are favourable or the prices of wood fuels are too high, the fuelwood consumers begin to use kerosene or bottled gas which means increased expenditure on imports. In these countries, which begin to have well structured markets, the incentives for implementing tree plantations become economically feasible. If this happens on a sufficiently Large scale, wood fuels' supply, instead of being based on a depleting resource, could be based on a planned and sustained resource which could be considered as a commercial source of energy. 3. THE ROLE OF WOOD ENERGY Many technical solutions using new and renewable sources of energy are being tried in order to substitute fossil fuels. However, due to technical, economical and social reasons, forest biomass seems to be one of the most appropriate alternative sources of energy not only for domestic use but also for industrial purposes and a clear demonstration of this are the policies being implemented. The role which trees can play in easing world energy problems is much broader than is generally realized. Fuelwood and charcoal have, until recently, been regarded simply as subsistance fuels but it is now clear that they are also the fuels of the future which could contribute to the development of countries, especially through the substitution of imported fossil fuels.

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Fuelwood and charcoal are relatively cheap compared with imported fossil fuels and they can be used not only to cover the energy needs of cooking food but also as industrial fuels for a Large variety of uses (e.g. Lime kilns, cement factories, electricity generation, etc.) The use of wood-based energy gives several direct social, political and economic benefits through foreign exchange savings, increasing profitability of forests and more rational use of local resources, creating new jobs, improving the quality of life in rural areas, as well as the ecological and agricultural advantages derived by the tree plantations. For the above reasons, many countries (Sweden, Brazil, U.S.A., Canada, Philippines, etc.) are encouraging the mobilization of their forest biomass for energy purposes in order to use local resources and substitute oil and to get a more diversified utilization of energy sources in their national energy balances. 4. THE DEVELOPMENT OF INTEGRATED ENERGY SYSTEMS Supply of energy is not the only reason for the establishment of tree plantations. Plantations can take different forms and provide different advantages. As well as yielding fuel, they can provide timber for houses and rural industries, restore fertility to the land, halt desertification, prevent soil erosion, reduce flooding, provide animal forage and improve the environment in general. Fuelwood and charcoal have many positive features also as a commercial source of energy. They are ideal for providing both process heat and power for forest industries, (for instance, in sawmilling, chipping, panel production), agroindustries (grain processing and drying) and in cement factories, metallurgical furnaces, etc. Secondly, there are many small-scale predominantly rural industries where wood fuels can provide a convenient source of heat. These include crop drying, brick-making, pottery firing, Lime production. Finally, wood fuels are used for electrical power production for communities in several countries as well as for energy generation for water pumping in irrigation projects. These complex energy consuming activities:, if analysed at communal or village level, can be seen as integrated energy systems where wood is the basic source of energy for their implementation, and which play an important role in the communal life of developing countries. Until now, very little attention has been paid to these energy activities in the rural environment but these energy systems could contribute significantly to rural development and accelerate the transition from non-commercial structured markets of wood energy to commercial energy projects especially if carried out as a set of integrated activities. Therefore, the application of wood-based energy systems in rural industries and village electrification would not only provide for energy needs as an isolated aspect, but would also contribute to community development as a whole and promote people’s participation which is very important for a self-sustained, continuing process of development.

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5. FAO STRATEGIES FOR ACTION The Food and Agriculture Organization of the United Nations (FAO) recognizing the energy needs of developing countries is devoting much attention to energy from forest biomass. Through its Regular Programme and field activities, FAO’s Forestry Department is making determined efforts to improve the fuelwood situation and to help developing countries mobilize more of their forest biomass to provide energy not only for domestic use but also for industrial purposes, as well as supply other goods and services for rural development. In addition, FAO operates the Forestry and Rural Energy Programme, which is essentially a field programme, but financed through Trust Funds provided by donor nations. The objective of this Programme is to provide technical assistance to developing countries in improving their wood energy situation. The strategies for the actions carried out by the Forestry Department projects are designed in such a manner that the problems of wood energy are to be solved according to the needs of each individual country. Usually, the actions to be taken are: – analyzing the wood energy supply and demand situation in a particular region, country or area through wood fuel surveys in order to identify the main problems in wood fuel supply, consumption, transport and distribution; – mobilizing the political forces, strengthening institutional support and developing the necessary structures to plan and implement wood energy projects; – improving the management of existing forest resources in order to increase productivity and create new forest resources by, for instance, introducing fast growing species; – improving the efficiency of wood energy conversion systems by introducing new technologies and/or new equipment; – promoting research activities to develop appropriate technologies, and establishing demonstration plants using mature technologies; encouraging the exchange of information and technical cooperation between developing countries (TCDC) regions by establishing cooperative networks. These strategies have Led to several successful activities, and consequently FAO’s activities in the field of wood energy have grown rapidly. However, much remains still to be done in order to reach the ambitious targets of the Nairobi Plan of Action.

ENERGY FORESTRY RESEARCH IN BRITAIN Single Stem Short Rotation Systems C.P.MITCHELL Forestry Department, Aberdeen University, Aberdeen, U.K. AB9 2UU SUMMARY Trials of eleven single stem short rotation forest energy plantations recently established in Britain are described. They were designed to provide, in the short term, information on the logistics and costs of establishment. In the longer term production curves can be established. The trials were established in four geographical regions and on three site types using ten commercially available tree species at one planting density (10,000/ hectare). Costs of operations for the first three years are detailed and discussed in relation to the financial viability of forest biomass production. Although more expensive than conventional forestry on a per hectare basis costs for initial establishment are similar on a per thousand tree basis. Good weed control, although costly, is considered essential.

1. INTRODUCTION Earlier studies (1) indicated that wood has a potential as an alternative source of fuel within the U.K.Various possible end-uses were postulated and detailed studies undertaken to establish the area and nature of land which might become available for the supply of wood for energy under a number of scenarios (2). Wood is now seen to have its major outlet as a fuel in the domestic, institutional and small-scale industrial combustion markets. Both coppice and single-stem short rotation energy plantations are appropriate; coppice in the more fertile and sheltered lowlands, single stem on the less fertile and more exposed lowlands and sheltered uplands. The experimental programme to establish production curves for coppice is reported elsewhere in these proceedings (3). Machinery for harvesting short rotation coppice is being developed at Loughry College (4). The trial single stem energy plantations, with which this paper is mainly concerned, were established initially to examine the logistics and costs of growing trees on relatively small areas of land. The rationale being to see whether it was possible for farmers to grow trees for energy on the small areas of under-utilized land which occur on every farm.

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2. METHOD A total of eleven trial single stem energy plantations have been established on three site types : marginal agricultural land, scrub woodland and existing young plantations. The trials are situated in four geographical regions of Britain (Table I). Three were planted in 1981, seven in 1982 and one in 1983. At each site two replicate plots of each species were planted at one by one metre spacing (ie. 10,000 per hectare). Ten tree species (Alder, Alnus glutinosa; Birch, Betula pendula; southern beech, Nothofagus procera; Sycamore, Acer pseudoplatanus; Corsican pine, Pinus nigra var maritima; Scots pine, Pinus sylvestris; Douglas fir, Pseudotsuga menziesii; hybrid larch, Larix x eurolepis; Sitka spruce, Picea sitchensis and western hemlock, Tsuga heterophylla) as bare-rooted stock were obtained from commercial nurseries and planted on all sites. Forestry contracting companies were employed to carry out the work as it was felt that would be the course adopted by many farmers and landowners wishing to plant trees for energy on their land. 3. DESCRIPTION Detailed descriptions of the site and operations necessary to establish the trials have been given elsewhere (5); only a summary is given here. A. Craibstone—An area of marginal agricultural land planted in spring 1981. A polythene mulch was used initially to control weed growth but hand and chemical weeding was required in subsequent years. Most of the trees are growing well, particularly alder, Sitka spruce, larch and Scots pine. Corsican pine, southern beech and birch are growing poorly and are not suited to the site.

Table I LOCATION AND DESCRIPTION OF SINGLE STEM TRIALS SITE*

REGION

PREVIOUS LAND USE AREA (ha) PLANTING YEAR

A N.E. Scotland Marginal agri. B N.E. Scotland Scrub woodland C N.E. Scotland Young woodland D Scottish Borders Marginal agri. E Scottish Borders Scrub woodland F Southern England Marginal agri. G Southern England Scrub woodland H Southern England Young woodland I S.W. England Marginal agri. J S.W. England Scrub woodland K S.W. England Young woodland * See text for site letters.

0.2 0.6 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0

1981 1981 1981 1982 1982 1982/3 1982/3 1982 1982 1982 1983

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B. Banchory—Originally covered with a sparse birch scrub the site was cleared and ploughed prior to planting. Weeding was not necessary until the second and subsequent years. All trees except Corsican pine are successively established. C. Aldroughty—This young plantation was cleared and replanted in spring 1981. Weed control has been particularly difficult with woody and herbaceous weeds growing in profusion. Mechanical cleaning of the site followed by application of herbicides was necessary in 1983 and 1984. Most of the trees, except Corsican pine and western hemlock, are well established. D. Marlefield—This area of marginal agricultural land was ploughed prior to planting. Survival of all species, except Corsican pine and western hemlock, was good although the southern beech has suffered from frost damage. Control of weed growth has been necessary in each of the years following planting. The conifers, particularly Sitka spruce, hybrid larch and Scots pine, are now showing vigorous growth. E. Kilham—This dry and exposed site had a cover of sparse wood-land. Extensive drought in the two seasons following planting has had a devastating effect on survival and the few trees remaining are only growing slowly. F. Witney—Black polythene mulch was laid over this marginal agricultural site prior to planting to control weed growth. This was successful in the first season but in the following winter it was damaged by wind and had to be removed. Most species are successfully established but growth is poor—a possible micro-nutrient deficiency is being investigated. G. Tar Wood—An area of old mixed broadleaved woodland was cleared prior to planting. Growth of weeds has been extensive and difficult to control (hand and chemical). Most species are established but the survival and growth rate is poor. H. Longridge Wood—This site carried a young stand of European larch which was cleared prior to planting. There were some plant fatalities in the first year; Corsican pine and western hemlock suffering badly. Weeding by hand has been necessary in each year. Growth of alder, birch and southern beech has been particularly good. I. Crowcombe—A bracken covered area of marginal agricultural land was cleared using ‘Asulox’ and then planted. Survival and growth of all species is good but hand weeding of the bracken is still necessary. J. Queenhill—One hectare of old mixed broadleaved woodland was cleared prior to planting. Use of an antimammal smear was necessary to deter deer. All species are successfully established and growing well, notably birch and southern beech. K. Holmington—This area of young birch wood was cleared and planted later than the other sites. Plant survival is good but it is too early to judge growth. Control of weed growth is a potential problem. 4. RESULTS AND DISCUSSION The main initial aim of these studies was to study the establishment procedure and ascertain the likely costs of establishment. Costs of production as a percentage of total costs appear in Table II. The costs of initial establishment (ie. ground preparation, fencing, plants and planting) are somewhat higher than for conventional forestry. The average cost for these trials was £3,700 compared with £987 for a conventional mixed

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plantation (20–80% broadleaved). However, the initial cost per thousand plants compares favourably; £370 as compared with £375 for conventional forestry (6). The major cost elements are fencing, plants and planting, and weeding, The costs for fencing were higher than might be expected in practice as security of the trials was required. A farmer would probably make more extensive use of existing fences than was possible here. It would not be possible to reduce the cost of plants considerably unless large numbers were bought, say, by a cooperative. Planting costs may be reduced, as indeed might all labour costs, by using surplus farm labour in slack periods although this may not always be possible. Weeding is an essential operation if good and speedy establishment is to be guaranteed. Polythene mulch, however, was not found to be cost effective (Table III). A question often raised is—‘is energy forestry a viable financial proposition?’. Unfortunately, the ‘experimental’ nature of these trials and the lack of adequate data on yields and harvesting costs procludes a definitive answer. However, it is possible to gain a rough idea of the value wood for fuel would need to command 20 years hence if the operation is to breakeven. These values have been determined for three sites, two discount rates (with and without grants) and at three assumed rates of

Table II COSTS OF OPERATION PER HECTARE AS PERCENTAGE OF TOTAL OPERATION/SITE A1

B1

C1

D2

E2

F2,3 G2,3 H2

I2

J2

K4

Clearance – 3 9 – 8 4 32 20 8 10 8 Plough – 9 – 2 1 – – – – – – Fence – 20 23 17 20 18 18 14 21 21 23 Plants and Planting 21 42 26 53 41 21 30 39 39 38 57 Beating Up 6 11 7 – – – – 9 – – – Weed 73 16 35 29 29 57 20 18 28 22 13 Protection – – – – – – – – 3 4 – Total 6,269 3,595 5,175 5,121 4,971 4,693 4,669 5,496 5,865 6,237 4,549 1 P81; 2 P82; 3 Not possible to clearly disaggregate from coppice trials on same site; 4 P83.

Table III BREAKEVEN VALUES1 (£/tonne) DISCOUNT RATE (%)

Without Grants 3 5

With Grants 3 5

5 10 15 5 10 15 5 10 15 5 10 15 PRODUCTIVITY2 Craibstone 126 70 52 174 95 68 113 64 48 156 86 62 Craibstone3 74 45 35 100 58 43 62 39 31 82 49 37 Banchory 80 47 37 109 62 46 67 41 33 91 53 40 Aldroughty 107 61 46 148 81 59 95 55 42 130 73 53 1 A price of £45 after 20 years is equivalent to a present value of investment of £25 at 3%. A price of £66 after 20 years is equivalent to a present value of investment of £25 at 5%. 2 Dry tonnes/hectare/year. 3 Without polythene mulch.

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production (Table III). Harvesting was costed at £15/dry tonne. Forestry grants were included at the appropriate rate (7) assuming that mixed stand 40:60 broadleaved:conifers is planted. Clearly, for the system to breakeven at a cost competitive with other sources of energy a productivity of £10/dry tonne/hectare will have to be obtained—this is within the range predicted from studies of existing stands of these species (8). 5. CONCLUSION Valuable information on costs and logistics of establishment of energy plantations has been obtained. However, to be meaningful the trials should be continued to provide information on continuing costs and eventually yields. Despite their high potential yields Corsican pine and western hemlock appear not to be suitable for energy plantations as they are too difficult to establish. 6. ACKNOWLEDGEMENTS The work described was supported by the U.K. Department of Energy’s Biofuels Programme and the EEC Energy from Biomass Programme. Views expressed are those of the author and not necessarily of the Department or the EEC. 7. REFERENCES (1) KING, G.H. (1980). An assessment of how the forest production which is currently not used could be obtained for energy. In ‘Energy from Biomass’. Taormina, EC Report EUR 7550 En. (2) MITCHELL, C.P.; BRANDON, O.H.; BUNCE, R.G.H.; BARR, C.J.; TRANTER, R.B.; DOWNING, P.; PEARCE, M.L.; WHITTAKER, H.A. (1983). Land Availability for production of wood for energy in Great Britain. In Proc. 2nd EC Conference ‘Energy from Biomass’. Ed. A. Strub et al. Applied Science, London. p. 159–163. (3) PEARCE, M.L. (1985). Progress of short rotation coppice trials. These proceedings. (4) McLAIN, M.D. (1983). The development of a harvester (patent pending) for 2–3 year old willow coppice. In Proc. 2nd EC Conference ‘Energy from Biomass’. Ed. A. Strub et al. Applied Science, London. p. 225–229. (5) MITCHELL, C.P. (1984). An experimental study of short rotation forestry for energy. In Proc. EC Contractors Meeting. ‘Energy from Biomass’. Reidel Pub. Co., Dordrecht, Vol. 5, p. 88–95. (6) DOLAN, A.G. & RUSSELL, B.P. (1983). Economic Survey of Private Forestry : England Wales Establishment Costs. Thirtieth Ann. Rep. for the Forest Year 1981. Oxford University. (7) FORESTRY COMMISSION (1984). Forestry Grant Scheme. (8) MITCHELL, C.P.; MATTHEWS, J.D.; PROE, M.F. & MacBRAYNE, C.G. (1981). An experimental study of single stem trees as energy crops—Biomass yields of forest trees. ETSU Tech. Rep. B1081a.

FOREST BIOMASS. INRA’S PROGRAM E.TEISSIER-DU-CROS, coordinator Institut National de la Recherche Agronomique (INRA) Ardon 45160 OLIVET (France) Summary There are two main parts to the biomass research programme conducted by the Forestry Department of Institut National de la Recherche Agronomique (INRA): – existing stands of coppice and coppice-with-standards which, for practical reasons, cannot be all converted into high forest stands. This resource is available for immediate use. Our research programme concerns the measurement of the productivity in terms of total biomass and the techniques which will increase productivity while maintaining site quality (e. g. mineral nutrition). – possibilities for future plantations on the numerous marginal forest and agricultural sites. Research in this area has long-term goals. It includes forest tree breeding for short term biomass production, optimization of silvicultural techniques, fertilization and use of nitrogene fixing species. We are also studying the insect and disease problems associated with short rotation intensive cultures. Studies in this area were begun in 1980.

1. INTRODUCTION France, like several other countries of western Europe, has very little of its own energy resources. Several factors have led to greater interest in forests as a renewable energy source and have precipitated the initiation of new research programs: – a third (roughly 5 million hectares) of France’s forests is presently unproductive due to lack of management. Part of it could produce wood for biomass if investments could bring short-term revenues; – a second third of France’s forests is under coppice or coppicewith-standard management. Even if most of these stands are converted into high forests, many of them will remain in their present status due to patchwork ownership patterns and its small size. – EEC economists forecast that between years 2000 and 2030, the European excess of agricultural land will be 3 to 7 million hectares, of which two thirds will be in France (1); – petroleum supplies are presently sufficient and prices have decreased, but a new shortage can be anticipated after years 1990–95 or earlier in case of war in the Middle East; – several national or regional organizations and many private landowners believe in the role of forests for energy production. Support for research in this area has been shown by direct funding of projects and by allowing use of private and state land; – public and private research organizations have started investigations on methods of harvesting and uses of forest biomass.

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2. OBJECTIVES Research initiated by INRA and funded by the French Energy Agency (AFME), by the European Community and by Regional administrations have two major themes: – existing stands. Forest stands under coppice or coppice-withstandard management have not been harvested regularly since the 1940’s. These stands need to be inventoried for current volume and growth. Techniques to increase production should be studied, as well as the impact of these techniques on the nutrient balance. – short rotation forestry. There are 3 objectives: (a) to choose appropriate species and improve them through genetic selection; (b) to develop silvicultural techniques including planting density, rotation period, fertilization, irrigation and weed control; (c) to evaluate the impact of insect pests and diseases on short-term biomass stands. These two main themes have resulted in a series of research activities which I will briefly summarize. 3. MANAGEMENT OF EXISTING STANDS 3.1. Effect of rotation shortening on soil nutrient balance 3.1.1. Problem. One way to increase coppice production is to shorten rotations length. But after a few harvests this treatment may result in decreased productivity due to nutrient depletion or deterioration of roots. In chestnut stands of central western France certain coppices have been harvested every 5 to 8 years for a long time. Studies of nutrient uptake in these stands will serve to develop models which will be applied later in short rotation intensive cultures. 3.1.2. Investigators. Jean BOUCHON, Laboratory of Silviculture and Production; Claude NYS and Jacques RANGER, Laboratory of Soil Science and Forest Fertilization (N*). 3.1.3. Approach. Six stands at an approximate age of 25 years have been sampled on sites of different fertilities. The analysis concerns biomass production and nutrient balance in relation to site fertility. A second series of stands at ages 5, 9, 15 and 19 years have been sampled to study biomass production, nutrient uptake and nutrient transfer between growth rings in relation to age. Finally, a third series of stands which were coppiced every 5 to 8 years have been sampled near stands which were coppiced every 25 years. The analysis will concern biomass production and nutrient balance in relation to length of rotation.

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3.1.4. Preliminairy results. Provisional results (2) show a slow but steady decrease of N, P, K and Ca concentration in the wood with an increasing age. The six coppices with rotation periods of 5 to 8 years showed productivities from 5.4 to 16.9m3 ha−1 yr−1. In three classical coppices productivity ranged between 13.9 to 16.3m3 ha−1 yr−1. An accurate comparison will be made after soil analyses have been completed. 3.2. Quercus ilex coppices and fire-break maintenance in southern France 3.2.1. Problem. The project comprises two aspects. (a) Approximately 400 000 ha of French Mediterranean forests are covered with aging and abandonned green oak (Q. ilex) coppices. Harvesting these stands would have a double purpose: an important biomass resource and rejuvenation. (b) Fire-breaks are created and maintained either with hand tools or with sophisticated machines like the Scorpion brush harvester-chipper. The material harvested in the maintenance of these fire-breaks could be an important source of biomass. (N*)

This letter refers to the full address of the scientists which can be found in paragraph 6.

3.2.2. Investigators. Yves BIROT, Laboratory of Mediterranean Silviculture (A). 3.2.3. Approach. (a) Regrowth of green oak coppices will be studied under different site conditions, stand ages and harvesting techniques. A series of trials will be established in the Nîmes region in 1985. (b) Fire-break maintenance will be studied in order to determine the quantity of dry matter harvested and the subsequent evolution of flora composition, of stand structure and the biomass regrowth. One trial will be established in 1985 in a maquis stand in the Var department. 3.3. Silvicultural improvement of coppice production(3) 3.3.1. Problem. The low productivity of existing coppices may result from at least 3 factors: (a) low site fertility, (b) low stand density and long rotations, (c) improper species.

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3.3.2. Investigators. Alain CABANETTES, Laboratory of Silviculture, Luc BOUVAREL, Technical Biomass Service. (0) 3.3.3. Approach. The different techniques studied are ploughing, fertilization, interplanting and variation of rotation period. They have been or will be applied partly or totaly to birch, chestnut and hornbeam stands. 3.3.4. Provisionnal results. Results concern only the oldest trial which was laid out in 1982 in a birch coppice in the Sologne (central France, south of Orléans). Surface ploughing with a blade roller and long term fertilization were compared with and untreated control. Site effects were very large and resulted in productivities ranging from 1.1 to 4.4m3 ha−1 at age 3. Treatments have shown no significant effect, as expected, since they were intended to have a longterm effect. 4. SHORT ROTATION CULTURES 4.1. Forest tree improvement for short-term biomass production 4.1.1. Problem. A tree improvement programme which is versatile has to be developed for species with multiple uses. Extensive field trials are needed in order to evaluate tree performance on a variety of forest and agricultural sites. of particular interest is the comparison of growth on rich soils and poor, acid and hydromorphic soils. 4.1.2. Investigators. Eric TEISSIER-DU-CROS, Laboratory of Forest Tree Improvement, Luc BOUVAREL, Technical Biomass Service (0). Christian DUMAS, Mireille GAGET, Marc VILLAR, Laboratory of Cell Recognition and Plant Breeding (L). 4.1.3. Approach. Three routes are being followed simultaneously: (a) Choice of the most vigorous genotypes derived from species improved for sawlog production (poplars, larch, Sitka spruce); (b) Addition of selection criteria for biomass production to recently started improvement programmes (American red oak, yellow poplar, sugi); (c) Initiation of specific improvement programmes (alder, black locust). Route (a) involves improvement of fast growing poplars for wet sites. The ideotypes are clones with a high rooting ability

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of stem cuttings, adaptation to acid soils, fast juvenile growth and high rigor. One approach is interspecific hybridization which requires overcoming crossing barriers. 4.1.4. Preliminary results. Since 1980, almost 20ha of field trials have been laid out in different representative sites of several French regions (4). Genotype ranking is now starting to stabilize. Provisional conclusions will be drawn after one more growing season. Studies of interspecific hybridization barriers in poplars have led to a few hybrid seedlings involving 4 species of different sections of Populus which are not normally compatible (5). Several interspecific alder hybrids have been obtained and combinations of Alnus rubra and A. incana look promising. 4.2. Silviculture for optimum biomass production 4.2.1. Problem. Appropriate silviculture techniques must be developped for short-rotation biomass plantations. 4.2.2. Investigators. Daniel AUCLAIR, Laboratory of Silviculture, Luc BOUVAREL, Technical Biomass Service, (0). 4.2.3. Approach. Different combinations of spacings and rotations will be studied for a number of species under extensive and intensive silvicultural methods. Plots will be at least 0.1 ha and each trial roughly 3ha. For example, one trial was established in 1984 in central western France where the Belgian poplar clone “Beaupré” and American red oak were planted at spacings of 2.5m×0.5, 1.0 and 2.0m. 4.2.4. Preliminary results. Older trials with “Fritzi Pauley” on very poor sites and with extensive silviculture at very high densities (25 pl m−2) showed a productivity of 180, 300, 150 and 100g m−2 yr−1 at ages 1, 2, 3 and 4 years respectively when harvested every year. Trials at 10 trees m−2 and a 2-year-rotation period showed a productivity of 400g m−2 yr−1. These productivities which are far below what is considered acceptable show that extensive silviculture on poor sites is perhaps not profitable (6).

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4.3. Optimization of biomass production of short rotation coppices with fertilization 4.3.1. Problem. Short rotation intensive culture may lead to nutrient deficiencies. 4.3.2. Investigator. Maurice BONNEAU, Laboratory of Soil Science and Forest Fertilization (N). 4.3.3. Approach. Nutrient uptake of plants is being studied in field fertilization trials. These studies have the advantage of being based on undisturbed soils. The following nutrient combinations were applied to a short-rotation plantation of the Belgian poplar clone “Unal” on a leached pseudogley forest soil in central France : control, P1, P1 K, NP1 K, NP2 K, NP1 KCa with N=200kg ha−1 N, P1 and P2=160 and 240kg P2O5 ha−1, K=160 kg K2 0 ha−1, Ca=2 000 kg crushed Calcium ha−1. Planting density was 3 000 cuttings ha−1 on plots of 530m2 . Plantation was establish in 1984. No results are available yet. 4.4. Use of nitrogen fixing species for short term biomass production 4.4.1. Problem. An increase in soil fertility may be obtained through nitrogen fixing forest species. The goal of the present action is to study different species mixtures. 4.4.2. Investigators. François LE TACON, Laboratory of Forest Microbiology, (N). Daniel AUCLAIR, Laboratory of Silviculture, Luc BOUVAREL, Biomass Technical Service, Eric TEISSIER-DU-CROS, Laboratory of Forest Tree Improvement, (0). 4.4.3. Approach. The nitrogen fixing species, black and grey alder, and black locust, have been planted in mixtures with American red oak and different poplar species and clones. Generally, mixture ratios of 1 to 1 have been compared with single species plots. Occasionally other ratios such as 1 to 3 have also been used.

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4.4.4. Preliminary results. At age 3 years, the production of mixed plots of Alnus glutinosa and of the Belgian poplar clone “Unal” is half way between that of pure Unal plots (most productive) and pure Alnus glutinosa plots (7). This is confirmed at age 5. 4.5. Insect pests and fungal diseases in short rotation forestry 4.5.1. Approach. In short rotation forestry, the use of introduced species like red alder, the high foliage density and the coppicing scars may be ideal environments for leaf insects and diseases and twig borers. 4.5.2. Investigators. Jean LEVIEUX, André DELPLANQUE, Laboratory of Forest Entomology (0); Jean PINON, Laboratory of Forest Pathology (N). 4.5.3. Approach and preliminary results. A survey of insect pests of poplars and alders has been started. The host-insect interaction will be studied in order to determine whether certain chemicals of the host are associated with resistance to insect attack. Pathology studies are concentrated on the poplar rust, Melampsora larici-populina, and particularly on a new strain of this fungus called E2 which damages clones previously held to be resistant. 5. CONCLUSION The forest biomass programme of INRA has many aspects that are short-and-long-term in nature. At present the programme is very young and has only shown preliminary results. This paper was aimed at showing foreign colleagues the nature of our research and at stimulating interest in cooperative research. Readers are encouraged to contact scientists involved in the various projects. 6. ADDRESSES (N): INRA-CRF, Champenoux, 54280 SEICHAMPS (France) (0): INRA, Ardon, 45160 OLIVET (France) (A): INRA, avenue Antoine Vivaldi, 84000 AVIGNON (France) (L): University of Lyon, 43 boulevard du 11 novembre 1918, 69622 VILLEURBANNE (France)

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7. REFERENCES (1) MOLLE J.F. (1984). La biomasse énergie. Forêt de France. vol 276. 44–49. (2) BOUCHON J., RANGER J., NYS C. (1985). Biomasse forestière, ressource existante. Evolution de la croissance des taillis. Compte rendu final des travaux de 1984. Accord cadre INRA-AFME. Convention 1984. 7 p. (3) CABANETTES A. (1985). Biomasse forestière, ressource existante. Amelioration sylvicole de la production des taillis classiques. Compte rendu final des travaux de 1984. Accord cadre INRA-AFME. Convention 1984. 8 p. (4) TEISSIER-DU-CROS E. (1983). Improvement of forest Trees for short term biomass production. Energy from Biomass, volume 5, PALZ and PIRRWITZ Ed. 104–111. (5) GAGET M., VILLAR M. , DUMAS C., LEMOINE M. , TEISSIER-DU-CROS E. (1984). Poplar improvement. New strategies currently in progress in France. Proceedings. IUFRO WP S2.03–07 meeting, Ottawa, Canada, 6 p. (6) AUCLAIR D. (1984). Optimisation de la production des taillis a courtes rotations selon le milieu et la sylviculture. Compte rendu final des travaux de 1984. Accord cadre INRA-AFME. Convention 1984. 6 p. (7) TEISSIER-DU-CROS E., JUNG G. , BARITEAU M. (1984). Alder-Frankia interaction and alder-poplar association for biomass production. Plant and Soil 78, 235–243.

EUPHORBIA PROJECT : RENEWABLE ENERGY PRODUCTION THROUGH THE CULTIVATION AND PROCESSING OF SEMI ARID LAND BIOMASS IN KENYA. M.DECLERCK, PH.SMETS, J.SMETS and J.ROMAN TRACTIONEL ELECTROBEL ENGINEERING 75, Rue de la Loi—1040 BRUSSELS-BELGIUM Abstract A 100ha plantation of Euphorbia tirucalli and other semi-arid species was successfully established near Lake Baringo, Kenya. of the investigated species, Euphorbia tirucalli has so far proven to be the most performing in terms of yield and resistance, especially under very arid conditions (1984 drought). Several biomass conversion routes were investigated, in bench scale or commercial equipments, and technico-economic evaluations of the most promising processes were performed. At the end of the present phase of the project (March 1985) the elements are now available which make possible the realization on site of a demonstration project on the use of biomass for production of solid and gaseous fuels for the local market (household and small industrial applications). Production of high quality activated coal seems also attractive. Research on other semi-arid species should further be intensified, thus leading to an optimal use of the human and material resources established between 1981 and 1985.

1. INTRODUCTION The Euphorbia Project is a project undertaken since early 1981 and funded by the Belgian and Kenyan Governments in view of detining and evaluating the means for semi-arid land valorization through biomass production in Kenya. Within the scope of the Particular Agreement of March 28, 1981, the Governments decided to call upon the services of the Consultant Tractionel Electrobel Engineering, in view of evaluating the project. The main tasks of the Consultant included assistance in project management and coordination, establishment of a program for testing and data collection, and a scientific, technical and economic evaluation of the selected biomass processing technologies.

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2. EXPERIMENTAL TOOLS FOR THE PROJECT 2.1. In Kenya • Establishment and maintenance of a 100ha plantation in the Lake Baringo district with Euphorbia tirucalli, and competing semi-arid species, including Prosopis Chilensis , Leucaena L. which covered 15% of total planted area. • Set up of a laboratory, enabling the on site monitoring of the plantations • Optimization of the agronomical conditions and study of seasonal effects, rainfall,…on biomass yields. 2.2. In Europe Set up of a comprehensive research program on the valorization of Euphorbia tirucalli, carried out in collaboration with several leading Belgian research institutes and including: • Testing of biomass pretreatment processes (e.g. mechanical dewatering) • Liquid fuel production (methanol+gasoline) • Low btu gas production in a commercial gasifier • Biogasification of Euphorbia tirucalli (juice and/or whole plant samples) • Production of renewable solid fuels (pellets, briquettes, charcoal) • Production of activated coal.

3. BIOMASS PRODUCTION: MAIN EXPERIMENTAL RESULTS 3.1. Production data More than 150 samplings carried out between December 82 and January 85 demonstrated Euphorbia tirucalli yields ranging from 6–10 dry tons/ha/a on low density plantations up to 16–20 tons/ha/a on high density plantations (300.000 plants/ha). First quantitative data have confirmed the excellent regrowth of the coppice. Resistance to stressed environmental conditions (1984 drought) proved to be superior to any other biomass tested on site. In 1984 nearly 30 samplings of semi-arid trees were also carried out. Productivities were much lower, generally between 2 to 4 dry tons/ha/a. Especially during the heavy and prolonged drought of 1984, no significant net increase in dry matter could be recorded. Through better selection and utilization a substantial improvement of these species can certainly be expected. 3.2. Economic costs of the biomass Detailed calculations were carried out on basis of the experimental data recorded on site. Cost estimates include all direct and indirect equipment and personnel costs, amortization, 12% interest on capital investment…; basic project data were: 15 year

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lifetime; plantation size selected for 9600 dry tons/a biomass production; 6 year lifetime per crop (harvesting every three years). Biomass costs of Euphorbia Tirucalli versus planting density Density (plants/ha) 20.000 80.000 330.000 Yield (dry tons/ha/a) 8 20 20 Production cost (BF/dry ton)* 5.000 3.700 4.300

Nonwithstanding slightly higher production costs, low density plantations (20–40.000) seem more recommendable in view of the easier phytopathological monitoring of the plantation. In conclusion, Euphorbia tirucalli offers the following comparative advantages in view of the valorization of the semi-arid lands: – better resistance, especially under stressed environmental conditions – no need for irrigation if planting is secured before the rains – reduced size of the plantations (2 to 8 times smaller for same dry matter production). – cheaper to establish than other semi-arid species (according to data recorded on site). * on 15.03.85:1 Ecu=45.00BF 1 US$=68.00BF 4. Biomass conversion: main experimental results 4.1. Physico-chemical characteristics of raw Euphorbia tirucalli • Proximate analysis moisture % (wet basis): 83+/−1.5 volatile matter % (dry basis): 76.3+/−0.5 fixed carbon % (dry basis): 15.7+/−1 ash (at 950°C)% (dry basis): 8.0+/−1

• Elementary analysis expressed on moisture an ash free basis C%: 49.3+/−0.8 H%: 6.1+/−0.1 0%: 43.3+/−1.0 N%: 1.0+/−0.4 S%: 0.3+/−0.1

• Higher heating value –dry basis :17.6MJ/hg –dry, ash free basis :19.0MJ/kg

4.2. Overall processing sheme of Euphorbia tirucalli • The coproduction of substitute solid fuels and biogas is illustrated hereunder (fig.1)

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Data are base on bench-scale tests carried out at University of Ghent (Prof.Dr. W.Verstraete) and compactation tests carried out in a commercial unit in the South of Belgium. Estimated production costs 16BF/m3n for the methane and 6000BF/dry ton or 1400BF/Gcal for the briquettes. This includes the cost of the fresh biomass (presently estimated at 3700BF/ton. 4.3. Air gasification tests Tests in a commercial 100kVA unit were carried out in collaboration with the belgian research institute INIEX. Taking into account actual costs of biomass and of local diesel fuel, the pay-back period for a gasifier group for electricity generation would be between 2.5 and 4 years for the different cases. 4.4. Activated charcoal production First results of the tests, carried out in collaboration with a Belgian university are very promising as the end product competes favorably in terms of quality with the best commercial granulated coals (cfr fig.2). A thorough technico-economic evaluation of this processing will be carried out upon completion of the bench scale experiments.

Fig.1 Coproduction of solid and gaseous fuels from Euphorbia tirucalli

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Fig.2 Properties of activated carbon Euphorbia Commercial coals 8 11 powder granulated F400 Methylene blue index g/100g 20.0 21.1 loding index mg/g 1215 1211 Phenol index 32.4 33.1

10–15 20–26 25–3 500–600 +1000 1118 30–35 +35 44.2

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REFERENCES 1. Tractionel Electrobel Engineering, Euphorbia Project, Evaluation Report, January 1984. 2. Idem, Euphorbia Project, Status Report on Testing and Data Collection, July 1984. 3. Idem, Euphorbia Project, Final Report, January 1985. 4. SCHOETERS J., MANIATIS K., BUEKENS A., Research Project Kenya, Euphorbia, Gasification Experiments, Final Report for B.A.D.C., June 1984. 5. VERSTRAETE W., DE WILDE B., Project Euphorbia, Biogasification of Euphorbia tirucalli, Report on Phase 2, October 1984. 6. DUTRECQ and PARMENTIER, Report ont he Phytosanitary cover within the framework of the “Euphorbia Project”, June 1984. 7. V.VOLCKAERT, Study of Some Aspects of Euphorbia tirucalli L. cultivation (in Dutch), edited at the Faculty of Agricultural Sciences R.U.G., May 1984.

ACKNOWLEDGMENTS We wish to express kind regards to the responsibles of the Belgian Agency for Development Cooperation and to the Kenyan Ministry of Environment and Natural Resources for their making possible the realization of the Project. Also, issuing this paper would not have been possible without the efficient and appreciated collaboration of the Kenyan and Belgian researchers, technicians and field workers which carried out the testing and data collection program and helped to establish and maintain the pilot plantations.

POTENTIALITES DE PRODUCTION D’UN COUVERT VEGETAL M.CHARTIER, J.M.ALLIRAND, G.GOSSE Station de Bioclimatologie—INRA 78850 Thiverval-Grignon FRANCE L’utilisation du rendement énergétique dans l’analyse de la croissance d’ un couvert végétal (MONTEITH 1972; VARLET-GRANCHER et al. 1982…) s’est avérée très intéressante et a particulièrement mis en évidence l’ importance du rayonnement solaire intercepté par la culture pour expliquer les variations de production de matière sèche. En conditions d’ alimentation hydrique et minérale optimales, plusieurs auteurs ont établi des relations linéaires entre la matière sèche accumulée et la quantité d’énergie interceptée (MONTEITH 1977; BONHOMME et al. 1982; GOSSE et al. 1985). Ces relations, faciles à mettre en oeuvre, permettent simplement de caractériser le potentiel de production d’ une espèce dans une région donnée. Grâce à des expérimentations réalisées sur de nombreuses espèces et sous des climats variés, nous proposons de généraliser cette démarche et d’ en faire une méthode d’ analyse de la croissance, particulièrement utile pour les productions lignocellulosiques tels que les fourrages, la Canne de Provence, les Roseaux…, dont on exploite l’ ensemble des parties aériennes. MATERIEL ET METHODES Les mesures de rayonnement intercepté par la culture et les productions de matière sèche ont été réalisées selon un protocole défini par ailleurs (GOSSE et al. 1985). Le tableau suivant rappelle les différentes espèces et les conditions climatiques qui ont été étudiées, soit au total 80 courbes de croissance représentées chacune par 6 à 8 points expérimentaux.

TABLEAU I ESPECES Canne à Sucre Panicum Maximum Maïs Vigna Sinensis Luzerne Féverole Fétuque Blé d’hiver Colza

CARACTERISTIQUES CONDITIONS CLIMATIQUES C4 " " C3—légumineuse " " C3 " "

Climat tropical " Climat tempéré Climat tropical Climat tempéré " " " "

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" "

" "

RESULTATS EXPERIMENTAUX a) Pendant la phase active de croissance, il est possible d’établir des relations linéaires entre la matière sèche accumulée et la somme du rayonnement intercepté par la culture. Sur les différentes cultures étudiées, ces relations appartiennent à trois groupes statistiquement différents selon la nature de leur mébtabolisme carboné et azoté (cf. figure 1.). La stabilité de ce type de relation a été discutée par ailleurs (GOSSE et al. 1985). b) Ces résultats peuvent servir de base à deux types d’application: – détermination des potentialités de production d’ une espèce en fonction du gisement solaire et de ces caractéristiques de végétation (position du cycle dans l’année, durée du cycle et vitesse d’établissement de la surface foliaire), – méthode d’étude de la croissance d’un couvert végétal par l’analyse des effets d’un stress sur l’abscisse (somme de rayonnement intercepté) et sur la pente (efficience de conversion). DETERMINATION DES POTENTIALITES DE PRODUCTION D’UNE ESPECE DONNEE: Cette détermination se fait en trois temps: – on suppose une espèce caractérisée par son cycle photosynthétique et présentant une efficience d’interception égale à 1 pendant toute l’année (cf. figure 2.). Cette hypothèse permet de définir un potentiel de production pour une espèce donnée en fonction du gisement solaire. – On suppose une espèce caractérisée par son cycle photosynthétique et présentant une efficience d’interception égale à 1 pendant sa période de végétation. Il est ainsi possible de tester pour un lieu et une espèce donnée, l’influence de la durée du cycle de végétation et de sa position dans l’année (cf. figure 3., pour des espèces en C3 dans la région de Versailles). – Tout en gardant les hypothèses précédentes, on suppose de plus d’une part, des vitesses d’apparition et de disparition de la surface foliaire différentes, et d’autre part, des structures de végétation différentes (inclinaison des feuilles (cf. figure 4.)). METHODE D’ETUDE DE LA CROISSANCE D’UN COUVERT VEGETAL La méthode présentée est bien adaptée aux couverts végétaux dont l’ensemble de la biomasse aérienne est exploitée (Fourrages, Canne de Provence,…). Les relations précédentes ont été établies en conditions optimales d’alimentation hydrique et minérale,

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l’analyse de la croissance proposée repose sur l’examen des distorsions au modèle cidessus. Les distorsions peuvent porter sur les deux points suivants : – une action sur la vitesse avec laquelle est parcourue l’abscisse, cet effet traduit l’action d’un stress (azoté, hydrique) ou d’un facteur climatique (température) sur les conditions d’établissement de la surface foliaire (cf. figure 5. dans le cas d’une alimention azotée déficiente). – une action sur la pente des relations Matière sèche aérienne en fonction de la somme du rayonnement intercepté, cette pente traduit, d’une part, l’efficience de la photosynthèse de la culture, et d’autre part, la répartition des assimilats entre les parties aériennes et souterraines (cf. figure 6.). CONCLUSION Cette approche globale permet de répondre en première approximation aux questions posées par la productivité des espèces végétales mal connues (Jacynthe d’eau, Roseau…) pouvant être utilisées a des fins énergétiques. Par ailleurs, elle permet d’identifier les points de physiologie à traiter de façon analytique pour améliorer ou stabiliser la production de ces espèces. REFERENCES GOSSE. G., VARLET-GRANCHER C., BONHOMME R., CHARTIER M., ALLIRAND JM., LEMAIRE G.–1985–Production maximale de matière sèche et rayonnement intercepté par un couvert végétal in Agronomie en cours de publication. MONTEITH J.–1972–Solar radiation and poroductivity in tropical ecosystems. J.Appl. Ecol., 9, 747–766. VARLET-GRANCHER C., BONHOMME R., CHARTIER M., ARTIS P. 1982–Efficience de la conversion de l’énergie solaire par un couvert végétal. Oecol. Plant., 3, 3–26.

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Potentialites de production d'un couvert vegetal

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PRODUCTIVITE DU ROSEAU PHRAGMITES J.M.ALLIRAND, M.CHARTIER, G.GOSSE Institut National de la Recherche Agronomique Station de Bioclimatologie 78850 THIVERVAL-GRIGNON (France) Résumé Une méthodologie d’approche de la production utile d’une culture fournissant du matériel lignocellulosique est établie et développée en s’appuyant sur l’exemple du roseau Phragmites.

1. INTRODUCTION Les filières de production d’énergie à partir de la biomasse actuellement envisagées semblent privilégier la production de matériel lignocellulosique. Dans ce contexte, il nous a paru utile de développer une méthodologie d’évaluation de la production d’une culture pérenne a partir de l’exemple du roseau Phragmites (common reed), graminée des zones humides tempérées. 2. EVALUATION DE LA PRODUCTIVITE Estimation de la production potentielle – après simplification des termes du bilan radiatif d’un couvert végétal, on peut définir une efficience de l’interception de la culture de la façon suivante :

avec PARt=rayonnement visible PARi=rayonnement visible – les mesures effectuées ont permis de formuler

transmis incident en fonction de l’indice foliaire (LAI)

– on définit le rayonnement abosrbé PARa:

– il est possible de relier la production de matière sèche d’un couvert végétal en phase végétative au rayonnement PARa absorbé (cf poster CHARTIER, ALLIRAND, GOSSE) MSaérienne=1, 5+0, 02 PARa Estimation de la production réelle

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L’observation de l’évolution de la matière sèche du couvert met en évidence une déviation au modèle proposé: après la floraison, la matière sèche aérienne reste constante avec simultanément une mise en réserve des assimilats Estimation de la production agricole Une récolte automnale ne permettrait pas d’utiliser la totalité de la matière sèche aérienne, car une partie des feuilles tombe. L‘évolution du rapport β (matière sèche tiges/matière sèche totale aérienne) permet de mieux cerner la production lignocellulosique récoltable: à la date de la récolte, il ne reste que 65% de la matière sèche totale aérienne. La production utile du couvert peut donc être formulée: MS utile=0, 65 (1, 5+0, 02 PARa), avec PARa=PARaJF A la latitude de PARIS, le modèle donne une production utile de 7 tonnes de Matière Sèche, soit environ 3 TEP, 3. CONCLUSION Il est possible d’estimer à partir de données météorologiques simples (PAR=0, 5×Rayonnement global) la production utile d’une espèce fournissant du matériel lignocellulosique. Les niveaux de productivité atteints dans un milieu non artificialisé justifient d’approfondir un certain nombre de points susceptibles d’améliorer les rendements: – étude des facteurs influant sur la mise en place du feuillage. – étude des processus de mise en réserve, liés à la pérennité du système – analyse des contraintes, notamment hydriques, au fonctionnement du couvert. L’acquisition de ces données devrait permettre aux agronomes d’établir les bases d’une phytotechnie, et d’envisager par la suite en terme de rentabilité une filière énergétique fondée sur ce type de végétaux.

COMPARATIVE BIOMASS YIELDS OF ENERGY CROPS W.H.Smith Center for Biomass Energy Systems University of Florida—IFAS J.R.Frank Regional Biomass Gas Research Institute Summary Biomass yield is a major cost consideration in the production of crops for energy. Biomass yields of crops grown for energy rather than food, feed, or fiber often can be doubled through variety selection and appropriate crop management. This paper catalogues the biomass yields of plant species in five plant resource groups (woody, grasses, root and herbaceous, aquatic and hydrocarbon-producing). Much of the data were produced in a joint program of the Institute of Food and Agricultural Sciences and the Gas Research Program which is focused on the production of methane from biomass. Over 150 species comprising more than 350 varieties and cultivars have been field tested to characterize their yield potentials as biomass energy crops. Napiergrass (Pennisetum), water hyacinth (Eichhornia), sugarcane (Saccharum), (Sorghum), and sweetpotato (Ipomoea) are among the most productive of about 20 promising specieis. These plants are now serving as a focus for more detailed analyses and research efforts to produce methane from biomass.

1. INTRODUCTION Domestic crops now grown were developed over many decades to meet food/feed/fiber needs. Biomass energy crops must possess different plant characteristics and meet different production criteria (1). Energy crop development will require the scientific methods employed with food/feed/fiber crop improvements but the process should be accelerated by the new biotechnologies available today. Many parameters impact overall costs of energy from biomass, but biomass yield and convertibility appear to be most significant. Both yield and convertibility can be improved. Thus, an important first step is to select high yielding biomass crops for improvement and adaption to energy cropping. This paper catalogues the biomass yields of plant species grown as energy crops in five plant resource groups (woody, grasses, root and herbaceous, aquatic, and hydrocarbon). Much of this data was compiled from the joint program of the University of Florida’s Institute of Food and Agricultural Sciences (IFAS) and the Gas Research Institute (GRI).

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Higher biomass yields have been recorded for several crops in the program but reporting here was restricted to the yields now in the published literature for comparison with other published data. In total, the IFAS/GRI program has evaluated in field tests nearly 350 cultivars and varieties among 150 species. Goals for conversion by anaerobic digestion and systems integration of production/conversion systems for assessing cost sensitivities and research progress are reported in companion papers in this conference (Frank et al. and Mishoe). 2. ENERGY CROP DEVELOPMENT Biomass yields for several energy crops among the five plant resource groups are listed in Tables I, II, III, IV, and V. Within all groups there are individual species that show superior yields. The energy crops that appear most promising in terms of yields are among the grasses (e.g., Napiergrass Pennisetum), sugarcane (Saccharum) and (Sorghum), aquatics (e.g., Eichhornia), and root and herbaceous (e.g., sweetpotato (Ipomoea). Biomass yields of grasses (Pennisetum and Saccharum) have approached 50– 70 Mg/ha in the south temperate to sub-tropical zones and 20–30Mg/ha in the north temperate zones (e.g., Sorghum). Tropical water hyacinth yields in field tests have exceeded 50Mg/ha. In controlled laboratory tests, hyacinth yields have reached 100Mg/ha, indicating a high potential for the tropical species. In areas where seasonality is important, energy crops with high growth rates over short growing seasons are desirable. For example, industrial sweetpotato has produced yields up to 22Mg/ha. This and other succulent herbaceous crops often reach maturity in 60–150 days. The biomass of these crops is in the form of starch and other easily digestable forms for methane production. Some unconventional herbaceous weed species are showing promise as biomass crops. Woody plant yields are generally low but so are the production and storage costs. Storability is an important factor in biomass energy crop selection. While wood has not been a desirable substrate for methane, some recent evidence shows that some hardwoods, especially those grown in high density, very short rotations are reasonably convertible to methane (34). Crop environment and management practices are proving to have significant effects on biomass convertibility (35). About 20 species show promise and are being further evaluated and additional species with potential are being sought. The GRI/IFAS program is initially focusing research and development of Napiergrass, water hyacinth and sorghum and the production/conversion systems best suited for generating cost competitive methane.

TABLE I. BIOMASS YIELDS OF HYDROCARBON PLANTS IN VARIOUS LOCATIONS Crop/Location Calotropis N.Australia(Summer) N.Australia(Irrig.)

Yield(Ref.) Dry Mg/Ha/Yr Crop/Location Asclepias latifolia 10.80(15) Texas, US 20.00(15)

Yield(Ref.) Dry Mg/Ha/Yr 9.80(18)

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Arizona, US Euphorbia lathyris Spain S.Australia (Winter) S.Australia (Irrig.) Euphorbia antisphillitica Texas, US Euphorbia tirucalli Florida, US (Irrig.) Florida, US (Fert.) Florida, US (Fert. & Irrig.)

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21.90(16) Asclepias rotundifolia E.Australia

7.50(15)

9.90(17) Ascelpias curassavica 3.00(15) Florida, US (Irrig.) 10.00(15) Florida, US (Fert.) Florida, US (Fert. & Irr.)

1.95(21) 2.44(21) 2.36(21)

2.43(18) Asclepias speciosa Utah, US

4.07(20)

0.09(21) Guayule 0.14(21) Arizona, US 0.11(21) Australia

2.47(19) 5.00(15)

TABLE II. BIOMASS YIELDS OF GRASS PLANTS IN VARIOUS LOCATIONS Crop/Location Sugarcane (Saccharum) Brazil Thailand Philippines Hawaii, US Florida, US Texas, US Florida, US Louisiana, US Puerto Rico Sorghum: Sweet Cultivars: MN 1500 Texas, US Florida, US M81E Texas, US Florida, US Rio Texas, US Florida, US Wray Texas, Florida Keller

Yield(Ref.) Dry Mg/Ha/Yr Crop/Location Dry Sorghum (Continued) 49.0(2) Grain 38.0(2) Giza-114 38.0(2) Texas, US 39.6(3) BT×623 53.0(4) Texas, US 30.0(3) AT×623 xP-3 53.0(4) TMT 430 66.0(5) Texas, US 70–73.4(6) Hybrid N. Atlantic US Central US Limpograss (Hemarthria) 30.8(7) 32.6(8) Napiergrass (Pennisetum) S. Florida, US 30.3(7) N. Florida, US 31.5(8) Puerto Rico 22.8(7) Bermudagrass (Cynodon) 23.9(8) South East US N. Atlantic US 20.8(7) Switchgrass (Panicum)

Yield(Ref.) Mg/Ha/Yr

22.3(7) 20.4(7) 22.6(7) 21.3(7) 8.2(9) 8.5(9) 7–22(10)

55.4(10) 48.6(10) 34.5 (6)

7–15(10) 15.9(9)

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Texas, Florida Brandes Texas, Florida Forage Red Top Kandy Florida, US Titan R Florida, US “High Energy” AAtlas×BMR-12 Texas, US AAtlas×Rio Texas, US AT×623×82C5796 Texas, US AAtlas×P-3 Texas, US

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25.4(7) Central & SW Plains, US

10.0(9)

37.0(7) Blue Paniegrass (Panicum) Westerm US

8.0(9)

28.8(8) Reed Canarygrass (Phalaris) Central US 25.1(8) North East US

7.6(9) 6.1(9)

Smooth Bromegrass (Bromus) 26.3(7) N. Atlantic, US

6.2(9)

24.1(7) Orchardgrass (Dactylis) Wisconsin, US 23.4(7) Wheat (Triticum) 22.4(7) US (Whole Plant)

12.1(9)

4.4(9)

TABLE III. BIOMASS YIELDS OF AQUATIC PLANTS IN VARIOUS LOCATIONS Crop/Location

Yield(Ref.) Dry Mg/Ha/Yr

Yield(Ref.) Dry Mg/Ha/Yr

S.Wild Rice(Zizansiopsis) Pennywort (Hydrocotyle) Florida, US 25.0(30) Florida, US 5–10(30) Cattails (Typha) Bulrush (Scirpus) Minnesota, US (S+R) 15–40(32) Florida, US 5.0(30) Florida, US (S) 8–23(30) Britain (S) 10.7(32) Taro (Colocasia) S.E. Asia (S) 4.2–22.5(32) Florida, US 6–7.5(33) Wisconsin, US (S+R) 19.0(32) Czechoslovakia (S+R) 8–34(32) Elodea Florida, US 3.0(30) Soft Rush (Juncus) Florida, US 16.0(30) Water Lettuce (Pistia) Florida, US 3–5(30) Water Hyacinth (Eichhornia) Florida, US Water Fern (Salvinia) Agric. Drainage Water 50. 0(31) Florida, US l-3(30) Sewage Effluent 52.0(31) Nutrient Solution 106.0(31)

TABLE IV. BIOMASS YIELDS OF ROOT AND HERBACEOUS PLANTS IN VARIOUS LOCATIONS

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Yield(Ref.) Dry Mg/Ha/Yr

Yield(Ref.) Dry Mg/Ha/Yr

J. Artichoke(Helianthus) Cassava (Continued) California, US (Tubers) 1.8–6(11) Philippines 8.7(13) Florida, US (Tubers) 5.5(12) Florida 6.1–11.4(13) Canada (Tubers) 2.8–9(11) Fodderbeat (Beta) Netherlands (Tubers) 3–4.6(11) Florida, US 7.4–14.1(13) Sweetpotato (Ipomoea) Brassica Cultivars: Forage Rape Centennial Florida, US 11.4(12) Florida, US 21.8(12) Louisiana, US 10.3(9) GatG-3 Turnip Florida, US 9.9(13) Louisiana, US 10.3(6) W-119 Florida, US 9.6(12) Florida, US 5.6(13) Rojo Blanco Fodder Carrot (Daucus) Florida, US 5.0(13) Florida, US (Root) 9.8(13) Japan 20.9(2) Philippines 9.6(2) “Weeds” Amaranthus Florida, US 1.6–4.2(14) Sugarbeet (Beta) Florida, US 7.8(13) Sida Ohio, US 15.4(19) Florida, US 4–16.7(14) Eupatorium Cassava (Manihot) Florida, US 4.8–13.4(14) Brazil 13.2(2) Thailand 12.7(2)

TABLE V. BIOMASS YIELDS OF WOODY PLANTS IN VARIOUS LOCATIONS Yield(Ref.) Crop/Location Dry Mg/Ha/Yr Crop/Location Eucalyptus grandis California, US Arizona, US Florida, US robusta Florida, US regnans New Zealand nitkens New Zealand saligna

Populus (Continued) Ontario, Canada 20.0(22) Pennsylvania, US 21.9(22) trichocarpa 15–23(23) Washington, US deltoides 16.5(24) South East US 21.4(25) Mesquite (Prosopis) US 17.9(25) Leucaena

Yield(Ref.) Dry Mg/Ha/Yr 16.4(9) 5.4- 9.6(27) 8.1(9) 5.6–13.9(27)

7.1(16)

Comparative biomass yields of energy crops

New Zealand Alnus Pacific NW US Pinus Slash Florida, US Sand Florida, US Jack Wisconsin, US Monterey New Zealand Melaleuca Florida, US Casuarina Florida, US Robinia Kansas, US Indiana, US Populus Hybrid Wisconsin, US

26.4(25) Florida, US Salix 5.1–7.4(27) dasyclado Ireland (Seedling) Ireland (Coppice) viminalis 9.5(23) Ireland (Seedling) Ireland (Coppice) 9.0(23) Fraxinus 5.6(9) Ireland (Seedling) Ireland (Coppice) 12.9(25) Platanus Kentucky, US 22.7(23) South East US Betula 15.3(23) Ireland (Seedling) Ireland (Coppice) 7.2–10.3(27) Castanea 8.0–12.0(26) Ireland (Seedling) Ireland (Coppice)

351

5–40(28)

6.5(29) 15.2(29) 3.2(29) 4.9(29)

3.4(29) 3.3(29)

1.7(9) 4.1–6.3(27) 1.3(29) 0.5(29)

0.8(29) 0.3(29)

10.5(9)

ACKNOWLEDGEMENT: Mr. K.Reddy assisted in data compilation. REFERENCES (1) SMITH, W.H., (1983). Energy from biomass: a new commodity. In: Agriculture in the 21st Century. S.W.Rosenblum (ed). John Wiley & Sons, N.Y. 61–69. (2) MATSUGA, S. and KUBOTA, H. (1984). The feasability of national fuel-alcohol programs in Southeast Asia. Biomass 4:161–182. (3) ELAWAD, S.H., GASCHO, G.J. and SHIH, S.F. (1982). The energy potential of sugarcane and sweet sorghum. Energy from Biomass and Wastes. IV 65–106. (4) GASCHO, G.J. and SHIH, S.F. (1981). Cultural methods to increase sucrose and energy yields of sugarcane. Agron.J. 73:999–1003. (5) GIOMDVA, M.J., CLARKE, S.J. and STEIN, J.M. (1984). Sugarcane hybrids for biomass. Biomass. Vol. 6:61–68.

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(6) ALEXANDER, A.G. (1982). Management of tropical grasses as a year round alternative energy source. Energy from Biomass and Wastes IV. 87–104. (7) MILLER, F.R. and MONK, R.L. (1984). Breeding and development. In: Hiler, E.A.Sorghums for Methane Production. International Gas Research Conference Proceedings. In press. (8) STANLEY, R.L. and DUNAVIN, L.S. (1985). Potential sorghum biomass production in North Florida. Proc. Third S. Biomass Energy Res. Conf. Gainesville, Fla. In press. (9) KLASS, D.L. (1984). Energy from biomass and wastes: update. Energy from Biomass and Wastes. IV 1–42. (10) PRINE, G.M. and MISLEVY, P. (1983). Grass and herbaceous plants for biomass. Proc. Soil and Crop Sci. Soc. of Florida. Vol. 42:8–12. (11) KOSARIC, N., COSENTINO, G.P. and WEICZOREK. (1984). The jerusalem artichoke as an agricultural crop. Biomass 5:1–36. (12) O’HAIR, S.K., DANGLER, J.M., EVERETT, P., FORBES, R.B., LOCASIO, S.J., OLSON, S.M., SHUMAKER, J.R. and WHITE, J.M. (1985). Cruciferous and root crops for year-round biofuel production. Proc. Third S. Biomass Energy Res. Conf. Gainesville, Fla. In press. (13) O’HAIR, S.K., LOCASCIO, S.J., FORBES, R.R., WHITE, J.M., HENSEL, D.R., SCHUMAKER, J.R. and DANGLER, J.M. (1983). Root crops and their biomass potential in Florida. Proc. Soil and Crop Sci. Soc. of Florida. 42:13–17. (14) GILREATH, J.P. (1985). Effect of plant population on biomass production by six weed species. Proc. Third S. Biomass Energy Res. Conf. Gainesville, Fla. In press. (15) STEWART, G.A., HAWKER, J.S., NIX, H.A., ROWLINS, W.H.M. and WILLIAMS, L.R. (1983). The potential for production of “hydrocarbon” fuels from crops in Australia. CSIRO, 86. (16) PEOPLES, T.R. (1984). Dry matter and hydrocarbon yields of calotropis procera. Biomass 2:153–158. (17) AYERBE, L., FUNES, E., TENORIO, J.L., VENTAS, P. and MELLADO, L. (1984). Euphorbia lathyris as an energy crop-part II. Hydrocarbon and sugar production. Biomass 5:37– 42. (18) NEWTON, R.J., GOODWIN, J.R., MARGAR, D.L. and PURYEAR, J.D. (1982). Biomass from unconventional sources in semi-arid West Texas. Energy from Biomass and Wastes VI. 167–220. (19) FOSTER, K.E. AND KARPISCAK, M.M. (1984). Arid lands plants for fuel. Biomass 3:269– 285. (20) ADAMS, R.P., BALANDRIN, M.F.and MARTINEAU, J.R. (1984). The showy millkweed, asclepias speciosa: a potential new semi-arid land crop for energy and chemicals. Biomass 4:81–104. (21) DEHGAN, B. and WANG, SC.C. (1983). Evaluation of hydrocarbon plants suitable for cultivation in Florida. Proc. Soil and Crop Science Soc. of Florida. Vol. 42:17–19. (22) SACHS, R.M., GILPIN, D.W. and MOCK, T. (1982). Yields of short rotation eucalyptus grandis in high density plantations. Energy from Biomass and Wastes IV. 107–114. (23) ROCKWOOD, D.L., COMER, C.W., DIPPON, D.R., HUFFMAN, J.B., RIEKERK, H. and WANG, S.C. (1983). Current status of woody biomass production research in Florida. Proc. Soil and Crop Science Soc. of Florida. Vol. 42:19–27. (24) ROCKWOOD, D.L., COMER, C.W., CONDE, L.F. AND FISHER, R.F. (1981). Maximizing woody biomass production in Florida. Proc. International Gas Research Conf. Los Angeles, Calf. (25) FREDERICK, D.J., MADGWICK, H.A. and OLIVER, G. (1982). Biomass and energy production of eucalyptus in New Zealand. Proc. 2nd E.C. Conf. on Energy from Biomass. 150– 153. (26) POPE, P.E. and GIBSON, H.G. (1984). Biomass and nutrient distribution of robinia pseudoacacia grown under intensive culture. Proc. S. Forest Biomass Workshop. USDA Forest Service, Ashville, N.C. 83–90.

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(27) RANNEY, J.W., WRIGHT, L.L. AND PERLACK, R.D. (1985). Short-rotation woody crops production research in the south. Proc. Third S. Biomass Energy Res. Conf. Gainesville, Fla. In press. (28) OTHMAN, H.B. and PRINE, G.M. (1985). Biomass production and nutrient removal by leucaena in colder subtropics. Proc. Third S. Biomass Energy Conf. Gainesville, Fla. In press. (29) NEENAN, M. (1982). Short rotation forestry as a source of energy and chemical feedstock. Proc. 2nd E.C. Conf. on Energy from Biomass. 142–146. (30) REDDY, K.R., SUTTON, D.L. and BOWES, W. (1983). Freshwater aquatic plant biomass production in Florida. Proc. Soil and Crop Science Soc. of Florida. Vol. 42:28–40. (31) REDDY, K.R. (1984). Water hyacinth biomass production in Florida. Biomass 6:167–180. (32) PRATT, D.C. and ANDREWS, N.J. (1982). Cattails (typha spp.) as an energy source. Energy from Biomass and Wastes IV. 43–64. (33) SNYDER, G.H. and O’HAIR, S.K. (1985). Biomass production from taro (colocassia esculenta) in subtropical wetlands. Proc. Third S. Biomass Energy Res. Conf. Gainesville, Fla. In press. (34) CHYNOWEYTH, D.P. and JERGER, D.E. (1985). Anaerobic digestion of woody biomass. Developments in Industrial Microbiology. In press. (35) SHIRALIPOUR, A. and SMITH, P.H. (1984). Conversion of biomass into methane gas. Biomass 6:85–92.

ONOPORDUM NERVOSUM BOISS, AS A POTENTIAL ENERGY CROP J.FERNANDEZ, P.MANZANARES and J.MANERO División de Biomasa. Programa de Energias Renovables Junta de Energia Nuclear. MADRID (SPAIN) Summary This paper presents the species Onopordum nervosum Boiss as a potential crop for lignocellulosic biomass production. Its high productivity and adaptation to grow in poor lands makes it a feasible source of biomass for energy or—chemicals, O. nervosum is a plant that grows spontaneously in uncultivated lands of the Iberian Peninsula, mainly in limy soils, often reaching heights up to 3.5m. From—experimental measurements in wild populations, it has been estimated an average productivity of 24 tons of dry matter per ha. The fractionation of the dry biomass in the plant was: 40% stalks, 30% leaves and 30% capitules. The chemical analysis of the lignocellulose fraction showed a 15–19% of lignin, 65–70% of holocellulose and 35–40% of cellulose referred to the total dry matter. Some aspects related to the domestication of the species for large scale production have been studied in field conditions: improvement of the germination rate of wild seeds in order to prevent the natural inhibitors action, determination of the optimum number of plants per ha for maximum biomass production and evaluation of the plant development during its vegetative cycle.

1. INTRODUCTION Until now, Onopordum nervosum has been always considered as a weed and consequently, it has never been cultivated, but erradicated. However, O. nervosum could be considered as a potential energy crop due to several advantages that may be summarized as follows: – Abundant vegetation that prevents others weeds growing that would compete with it. – Plant structure that provides an efficient capture of solar energy by the leaves distribution along the stem, result ing in high biomass yields. – Strong root system that minimize the use of artificial fertilizers and allow to get water from the subsoil. – Vegetative cycle adapted to continental climate with cold and dry periods. – Possibility to grow in poor lands which can not support traditional crops. In several countries of the mediterranean area there are a lot of marginal lands where traditional crops give low produc tivity due to hard climatic conditions. In many of these lands O. nervosum could be cultivated for biomass production (1).

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2. PLANT DESCRIPTION Onopordum nervosum is a C-3 plant from the Compositae family whose habitat extends to the center, south and east of the Iberian peninsula, mainly in limy soils. Test carried out on twenty samples of soil where these plants were found, showed an average content of lime of about 20–25%. Its vegetative cycle starts in autumn, forming a roset during the winter. At mid spring, the stalk starts a fast developments growing more than 5cm daily for several days (see Figure I). In summer, at the end of its cycle, it very often reaches a height up to 3.5m. When seeds cannot germin ate due to drougth or endogenous inhibitors action, they remain dormant until the end of the winter. In this case, the roset is formed during spring, leaves get dry in the summer and reappear the next autumn to complete its cycle next summer. The plant holds yellowish stem with wide wings, reticulated veined. Leaves are oblong-lanceolate, white tomentose, lobed and spiny. Capitules are about 3×5cm, with involucral acuminate bracts. Flowers borne at the end of the main stem and branches produce plenty of greyish-brown seeds, 4–5mm lenght (2) (3). There are several morphological types of plants in relation to the degree of ramification, resulting in different distributions of the dry matter on the plant (Table II). The average chemical composition of the different fractions of O. nervosum is showed in Tables III and IV. 3. EVALUATION OF NATURAL PRODUCTIVITY IN A WILD POPULATION In order to evaluate the natural productivity of Onopordum nervosum, a sample of plants growing in an area of 10m2 was taken from a wild population located near Madrid. The— distribution of the size and dry weigth in the 61 plants of the sample is expressed in Table I. The estimated productivity of this population would be about 24 tons per ha of dry matter with an energy content of 84×106 kcal/ha=8.4 Toe (Ton oil equivalent)/ha. It is assumed a calorific value of O. nervosum biomass of 3500kcal/kg.

TABLE I. Distribution of the size and dry weight of the plants in a sample (10m2) from a wild O. nervosum population. HEIGHT INTERVAL NUMBER OF Average Dry Weight TOTAL DRY (cm) PLANTS Mean Value (g) v.c. WEIGHT (g) <150 4 32 0.36 151–200 15 65 0.40 201–250 25 338 0.79 251–300 14 779 0.39 301–350 3 1204 0.35 TOTAL 61 394 0.99 The estimated productivity would be 24.059kg/ha (dry weight).

128 975 8438 10906 3612 24059

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TABLE II. Percentage of biomass distribution (based on dry weigth) in three morfological types of O. nervosum. Degree of ramification Portion of Low Medium High the plant Stalk Branches Leaves Capitules TOTAL

44 5 42 9 100

38 14 32 16 100

23 23 30 24 100

TABLE III. Average basic composition of O. nervosum biomass (percentage based on dry weight) . Component Stalk Leaves Capitules Lignin Cellulose Hemicelluloses : – Pentosans – Others Ash Others

19.4 36.5

13.5 35.1

14.6 30.1

21.3 15.4 4.7 2.7

17.0 11.4 7.6 15.4

20.4 11.0 6.0 17.9

TABLE IV. Mineral composition of stalk and leaves of O. nervosum (percentage based on dry weight). Mineral elements Macronutrients Stalk Leaves Nitrogen Phosphorous Potassium Calcium Magnesium Sulphur

1.56 0.17 2.41 1.50 0.17 0.07

2.95 0.17 3.48 3.22 0.33 0.18

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Fig.I Stalk elongation curve of O. nervosum. 4. EXPERIMENTAL CULTURES The domestication of the species for large scale production started with the study of the germination of wild seeds from different places. In general, seeds present a high dormancy due to the endogenous inhibitors action. In order to remove the dormancy, seeds were treated with a solution of giberellic acid (1000ppm) for 24 hours. Increases in the germination—rate of about 60% were obtained. The effect of planting density and nitrogen fertilization in spring season on the biomass production, was tested on an experimental cultivation. Results summarized in Table V show that when plants are grown at 0.5×0.5 (40000 plants/ha), the highest production is obtained, being advantageous the nitrogen fertilization. Productivities are lower than that obtained in wild popula tions due to the small content in lime of the soil where the experiments were carried out on.

TABLE V. Productivity of O. nervosum in an experimental cultivation. Planting density

Nitrogen fertilization

1×1 1×1 1×0.5 1×0.5 0.5×0.5 0.5×0.5

NO YES NO YES NO YES

Productivity tons/ha(dryweight)

Average Height (m) 8.954 10.349 10.608 12.198 13.296 14.496

2.30 1.95 1.70 1.75 1.50 1.50

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5. CONCLUSIONS From results of natural productivity, it can be inferred the good forecasts offered by O. nervosum cultivations as a lignocellulosic biomass source. However, the low productivity found in the first experimental cultivations compared with that obtained in natural plantations, makes the optimization of culture techniques of this species neccesary for large sca le production. REFERENCES (1) FERNANDEZ, J. (1982) Plantaciones de encrgía. In: Energias Renovables y Medio Ambiente. Centro de Estudios de Ordenación del Territorio y Medio Ambiente. Monografía n°16, pp 53– 67. (2) TUTIN, T.G. y D.WOOD (1976) Onopordum. In: Flora Europea. Vol.4. Cambridge University Press. (3) GARCIA ROLDAN (1981) Onopordum. In: Claves de la Flora de España. Vol.1.

STRAW AS A BIOMASS RESOURCE AND ITS ACQUISITION IN THE UNITED KINGDOM J.M.CLEGG*, S.B.C.LARKIN, D.H.NOBLE and R.W.RADLEY Silsoe College, Silsoe, Bedford, England. *Hertfordshire College of Agriculture and Horticulture, St. Albans, England Summary To assist in the development of straw as a fuel, straw production, distribution, disposal and utilisation have been examined to determine how much of the resource could be available. 1984 U.K. straw production is estimated at 17.8 million tonnes with 6.3 million tonnes burnt in the field. Costs of not burning straw are given, as are costs of baling, handling, storage and transport. Straw can compete with coal and oil as a fuel in the agricultural, industrial, commercial, institutional and domestic sectors, with up to 1.7 million tonnes potentially being used by the year 2000.

1. INTRODUCTION Cereal straw is the most important agricultural residue in the United Kingdom, having the greatest potential for use as a fuel. A study was therefore undertaken for the Department of Energy covering all aspects of its production, disposal, acquisition and utilisation as a fuel (1). Some of the results of the study are summarised in this paper. 2. STRAW PRODUCTION. DISPOSAL AND UTILISATION Accurate yield and production figures for straw are not available but applying estimates of straw to grain ratio from a survey (2) to grain yields, straw production in 1984 in the United Kingdom can be estimated at 17.8 million tonnes. For the last two years a survey has been carried out (3) of straw dispossl in England and Wales. Assuming that in Scotland and Northern Ireland 95% of the straw is baled and 5% is burnt in the fields, the disposal of total U.K. straw production can be estimated as 10.2 million tonnes baled, 6.3 million tonnes burnt and 1.2 million tonnes incorporated into the soil. of the straw baled it has been estimated that 482 thousand tonnes are used off farm in England and Wales with stables, mushroom production and sodium hydroxide industrially treated straw being the main users (5). On the farm a similar quantity is estimated as being used for fuel, treated livestock feed, crop storage and for horticultural

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purposes with the remainder, estimated at 7.4 million tonnes in the U.K. in 1984 being used for livestock bedding, untreated for livestock feed or wasted. An estimated 166 thousand tonnes of straw are currently used on farms for fuel (1), mainly for domestic heating. Other current uses of baled straw are unlikely to increase much, so the estimated 6.3 million tonnes burnt is potentially available for use as a fuel or for new uses such as production of paper or chemicals. 3. THE COSTS OF STRAW ACQUISITION The cost of straw acquisition includes recompensing the farmer for foregoing the benefits of burning and the costs of straw baling, handling, storage and transport. Each of these has been examined (1), with the use of computer models using the costs of all relevant factors such as labour, machinery, fuel, vehicles, buildings, etc. A survey of cereal farmers (1) has shown that they burn straw because it is an easy or convenient disposal method, it is quick, it is the cheapest or most economic method, it allows easier cultivations and they believe it assists in weed and disease control. If straw is baled instead of burnt extra costs may be incurred, which are extremely variable depending on factors such as the following crop, the cultivation system, the nutrient status of the soil and the presence or absence of problems with weeds, diseases and pests. Baling straw, leaving the stubble behind, can reduce the yield of a following autumn sown cereal crop. This is thought to be principally because decomposing stubble produces acetic acid and other toxins which inhibit seed germination. This problem can be reduced by carrying out extra cultivations to reduce contact between decomposing stubble and germinating seed. Total costs are most likely to be in the range £0 to £12 per tonne, with £5 per tonne being a typical, average cost. The costs of baling straw and carting it to an on-farm store, or to a temporary stack are very variable. The cost depends principally on the tonnage baled each year, but also on the baling and handling system adopted and the average carting distance from field to store. Seven different baling and handling systems have been costed (4). Costs for baling and carting straw over a distance of 0.8km are shown in Table 1 for different annual utilisations of the machinery involved.

Table 1 Total cost (£/tonne) of straw baling and carting 0.8km to store Baling system and amount baled tonne/annum 100 250 500 1000 2000 3000 4000 Conventional &, Flat 8 56 bale transporter 5’ round bale (trailer) 5‘round bale (spike) 4’ round bale (trailer) Hesston 4800 ‘big bale’ Chopped straw

25.3 13.5 9.6 8.1 8.1 7.9 8.0 27.4 15.1 11.0 9.4 9.4 9.4 9.4 26.0 13.3 9.1 7.2 7.2 7.0 6.9 25.0 14.8 10.1 8.7 8.6 8.3 8.3 24.8 13.5 9.7 8.3 8.3 8.3 8.3 70.6 31.3 18.2 11.7 9.5 10.1 9.5 26.6 14.7 10.8 10.2 10.2 10.2 10.1

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The use of straw as a fuel, or for any other purpose, will involve a period of straw storage. The cost of storing straw depends on the method adopted and the type of bale being stored. If the method of straw storage is improved this will incur extra costs, but will reduce wastage of straw. Straw losses are very variable, but for costing purposes can be taken as 5% in a building, 15% in a covered stack and 30% in an uncovered stack. Costs including losses are shown for the different types of bales and a selection of storage systems in Table 2.

Table 2 Total cost (£/tonne) for selected systems of straw storaqe Fabric Tarpaulin Conventional bales (Flat 8) Conventional bales (56 bale pack) Hesston big bale 5’ round bale 4’ round bale Chopped straw

Polythene 1000g

Dutch barn 6m eaves

No cover

3.5 3.5

6.6 6.6

5.4 6.4

5.0 5.0

3.0 5.0 5.2 n.a.

7.4 11.6 13.9 n.a.

4.2 7.3 5.8 13.3

5.0 5.0 5.0 n .a .

The cost of straw transport depends on the bale system, the type of vehicle, its level of usage and the length of the journey. Transporting straw bales is relatively expensive because the low bale density means that vehicles can carry only a fraction of their maximum load. An articulated vehicle with a 12.2m long low loader trailer is of suitable dimensions to maximise the use of the vehicle carrying capacity compared with other vehicles, for all types of bale except round bales, which would be unlikely to be chosen for transport. This vehicle has therefore been chosen to give the examples of straw transport costs shown in Table 3. All costs are based on the current U.K. gross vehicle weight limits and a weekly vehicle usage of 800km.

Table 3 The cost of straw transport in an articulated vehicle with a low loader trailer (£/tonne) Package type Conventional bales (Flat 8) Conventional bales (56 bale pack) Hesston big bale 4’ round bale

Round trip distance (km) 40 80 160 320 5.99 8.97 5.05 8.03 3.90 6.80 8.39 13.71

14.94 14.00 12.61 24.36

26.87 25.93 24.23 45.66

The total costs of straw acquisition are summarised in Table 4. Because costs are so variable ranges and typical costs are given for each of the components. The typical values are in accord with contract prices that have been made for the supply of straw to industries.

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Table 4 Overall costs of straw procurement Range £/tonne Typical £/tonne Costs of not burning Baling and handling 7–14 Storage 3–6 Transport (40km round trip) 4–6 Total 14–38

0–12 5 9 4 5 23

4. THE POTENTIAL MARKETS FOR STRAW AS A FUEL Straw can potentially be used as a fuel as whole bales, or in the form of chopped straw or as briquettes. It could be used as a fuel on the farm, in industry, for commercial or institutional use or as a domestic fuel. Baled straw is most suitable for use on the farm. Chopped straw is suitable for industry and large scale agricultural purposes. Either of these systems may be appropriate in the commercial and institutional sector depending on scale. Briquettes are the only form of straw fuel suitable for the domestic market. Each of these potential methods of using straw for fuel has been assessed, technically and economically (1). The distribution of fuel demand has been compared with the distribution of surplus straw (mainly in Eastern England). Using this information the maximum possible use of straw as a fuel has been estimated, together with likely use of straw by the year 2000 (1,6). In the short term the most significant user of straw as a fuel will be agriculture for purposes such as farmhouse domestic heating, glasshouse heating, grain drying and pig house heating. There are examples of all of these in use at present in the U.K. The maximum potential could be 1.9 million tonnes, with 0.9 million tonnes used by 2000. Straw could be used as an industrial fuel, mainly to replace coal or oil in boilers, but also mixed with coal in furnaces in industries such as cement or brick. From estimates of fuel consumption in industries where straw could economically replace oil, located in Eastern England where surplus straw is available, the maximum possible use of straw would be 5.1 million tonnes. Because penetration of the market is not likely to be rapid the maximum use of straw by 2000 is 386 thousand tonnes in industry. Straw could be used as a fuel for schools, colleges (especially agricultural colleges), hospitals and offices located in rural areas where straw is available. To replace present fuels in the commercial and institutional sector in Eastern England a maximum of 4.3 million tonnes of straw would be required with 230 thousand tonnes achieveable by 2000. Straw briquetees are available from nine briquetting presses currently installed in England. While it is too early to judge the success of these enterprises at present it seems unlikely that with present equipment they can be run economically and produce a fuel sufficiently attractively priced to maintain a large share of the domestic market. 5% of the domestic coal market in Eastern England is estimated to be equivalent to 115 thousand tonnes of straw briquettes, which could be the market size by 2000.

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It is concluded that up to 1.7 million tonnes of straw could be used as a fuel in total in the U.K. by 2000. 5. STRAW BURNING While a ban on straw burning in the field in the U.K. seems unlikely at present, in 1984 more restrictions were placed on the practice. The main changes are that straw can no longer be burnt at weekends and can only be burnt in blocks of land not exceeding 10 ha. This has not significantly changed the tonnage of straw baled, but the area incorporated increased from 2% in 1983 to 9% in 1984 (3). This suggests that if the market for baled straw were to increase farmers would be prepared to supply that market instead of burning the straw in field. This would be preferable to incurring the costs of incorporation. 6. CONCLUSION More than sufficient straw is available to meet forseeable demand for straw as a fuel in the U.K. Systems are available for acquiring it economically in forms suitable for its use as a fuel. 7. ACKNOWLEDGEMENTS This work has been funded by the Department of Energy and forms part of the Energy Technology Support Unit’s programme on biomass energy. The views expressed are those of the authors and not necessarily those of ETSU or the Department of Energy. REFERENCES (1) CLEGG, J.M., LARKIN, S.B.C., NOBLE, D.H. and RADLEY, R.W. (1985). The Acquisition and Utilisation of Straw as a Fuel. Silsoe: Silsoe College. (2) HUBBARD, K.R. (1984). Personal communication. Ministry of Agriculture, Fisheries and Food. (3) MINISTRY OF AGRICULTURE, FISHERIES AND FOOD (1984). Straw Survey 1984: England and Wales. Stats 292/84, Guildford: MAFF. (4) NOBLE, D.H. and CLEGG, J.M. (1984). Costing Different Systems of Straw Conservation. Silsoe College Occasional Paper No. 12. Silsoe: Silsoe College. (5) LARKIN, S.B.C. (1984). Straw availability and procurement. In: D.J.White (Ed.) Straw Disposal and Utilisation: A review of knowledge. London: MAFF. (6) MARTINDALE, L.P. (1984). Straw as a fuel. In: D.J.White (Ed.) Straw Disposal and Utilisation: A review of knowledge. London: MAFF.

STUDIES ABOUT THE POTENTIAL OF SWEET SORGHUM AND JERUSALEM ARTICHOKE FOR ETHANOL PRODUCTION BASED ON FERMENTABLE SUGAR G.KAHNT and L.LEIBLE Dept of Agriculture, University of Hohenheim Box 700562, 7000 Stuttgart 70, Germany SUMMARY A two-year experiment with sweet sorghum and Jerusalem artichoke was conducted at three locations in the south of Germany, evaluating the potential for ethanol fuel production. Jerusalem artichoke (tubers) is more stable in yield of fermentable sugar respectively ethanol than sweet sorghum; with increasing temperature it is significantly surpassed by sweet sorghum.

1. INTRODUCTION Passing the first oil crisis in the beginning of the Seventies, the interest in renewable fuel resources increased rapidly. Nearly forgotten crops like sweet sorghum [Sorghum bicolor (L.) Moench] and Jerusalem artichoke [Helianthus tuberosus (L.)] got a renaissance (6,8,5,9). In Germany in the past sweet sorghum was primarily evaluated under the viewpoint of forage production, as a direct competitor to corn for silage (2,3). Today sweet sorghum seems to gain new interest for its potential in ethanol fuel production (4). The cultivation of Jerusalem artichoke has an old tradition in Germany (7); but in spite of the extensive experience with this high yielding crop, Jerusalem artichoke today has only local importance for some schnaps producing farmers in the south-west of Germany. The objective of the studies reported here was the evaluation of the potential of sweet sorghum and Jerusalem artichoke for ethanol production under different agricultural conditions. 2. MATERIALS AND METHODS The field trials in 1982 and 1983 were conducted at three locations.

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Description of Localities Loc.1 Loc. 2 Loc. 3 Altitude [m] Temperature [oC] :1982 :1983 Precipitation [mm] :1982 :1983

442 9.2 9.1 877 664

280 9.3 9.7 825 940

404 9.4 9.6 798 724

Sweet sorghum varieties Dale and Rio (1982 only Dale) were planted in May 5th-13th 1982 respectively in June 14th-16th 1983. Averaged plant population was 20 plants per sqm in rows 50cm wide. Two local varieties (S2,S3) of Jerusalem artichoke and two registered varieties (Topianka and Rozo) were planted 18th-21st of April 1983. In 1982 only the variety S2 was examined, planted at 2nd-6th of April. Plant density was 6 plants per sqm (50×35). The N fertilization was applied 4 weeks after planting, at rates of 0, 200, 300, 400kg N/ha in 1982 and at rates of 0, 80, 160, 240kg N/ha in 1983. Sweet sorghum (stem and leaves) was harvested in the middle of October and Jerusalem artichoke (tops and tubers) in the middle of November. The samples were ovendried at 70°C. The fermentable sugar (FS) was extracted with water and additionally the extracts of the Jerusalem artichoke tubers were hydrolysed with hydrochloric acid (0.5% (w/w)) for 30 min in a water bath (95°C). The fermentable sugar was determined enzymatically and expressed in % (w/w) sucrose (1). Based on FS the potential ethanol yield was calculated, assuming that 85% of the theoretical ethanol output can be realized under practical conditions. Multiple comparisons were tested with Tukey’s HSD test. 3. RESULTS AND DISCUSSION Biomass yield (Fig.1) In 1982 biomass yield of sweet sorghum (Dale) was 31.1t/ha at the 200kg N rate. In 1983 the averaged yield level of Dale was 12.8t/ha lower than in 1982, because the planting date was nearly 5 weeks later due to the weather conditions in May. In 1983 the variety Rio yielded 2.5–4.0t/ha higher than Dale.

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Fig. 1 Biomass yield of sweet sorghum and Jerusalem artichoke as affected by year, location, variety and N fertilization Jerusalem artichoke yielded in 1982 at the 200kg N/ha rate 11.1 metric t/ha tops and 10.5 metric t/ha tubers. Increasing N rate resulted in a depression in biomass yield. The averaged yield level in tops and tubers in 1982 was 0.9t/ha respectively 2.2t/ha higher than in 1983, due to the better weather conditions in 1982. The registered varieties were not superior compared to the local varieties. Yield of fermentable sugar (FS) respectively ethanol (Fig.2) In 1982 sweet sorghum yield was 11.4t FS/ha at location 1 (not separately figured out). The averaged yield of Dale was 7.0t FS/ha respectively 3990l ethanol per ha. In 1983 yield of variety Dale was 4.8t FS/ha at location 1, significantly surpassed by Rio (6.1t FS/ha), due to the greater biomass yield and the higher FS content of Rio.

Fig. 2 Yield of fermentable sugar and ethanol of sweet sorghum and Jerusalem artichoke as affected by year, location, variety and N fertilization

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In 1982 Jerusalem artichoke (tubers) achieved 6.7t FS (3840l ethanol) per ha (average of 3 locations) at the 200kg N/ha rate. The best location (Loc. 1) resulted 10.3t FS/ha (not separately figured out), respectively 5850l ethanol. In 1983 variety S2 yielded 1.5t FS/ha less than in 1982 (average of 3 locations). Variety S3 realized the greatest FS and ethanol yield, i.e. 5.9t FS respectively 3380l ethanol per ha (average of 3 locations and 4N rates). In 1982 sweet sorghum yielded significantly more ethanol per ha than Jerusalem artichoke, but in 1983 Jerusalem artichoke produced higher ethanol yields (2950l/ha) than sweet sorghum (2190l/ha), regarding total averages. Jerusalem artichoke seems to be more stable in yield of FS and ethanol than sweet sorghum; but sweet sorghum can surely be better adapted to the described climatic conditions by plant breeding. Because of harvesting problems of Jerusalem artichoke tubers on heavy and compacted soils the cultivation is limited to locations with sandy loam/sandy soils. Besides optimization of the cultivation of sweet sorghum and Jerusalem artichoke the technical background of processing ethanol has to be better evaluated and improved. ACKNOWLEDGEMENT These studies were financially supported by a grant from Ministry of Research and Technology, Bonn, Germany. LITERATURE CITED 1. ANONYMOUS, 1983: Methoden der enzymatischen Lebensmittelanalytik. Boehringer Mannheim GmbH, Mannheim, West Germany. 2. ATANASIU, N. und K. SHAABAN, 1966: Untersuchungen ueber den Einfluss der N-Duengung und der Saat- und Schnittzeit auf den Ertrag von Sorghum-Hirse und Mais. Die Bodenkultur 17, 52–63. 3. BOGUSLAWSKI, E.v., N.ATANASIU und K. SHAABAN, 1965: Naehrstoffaufnahme, Naehrstoffentzug, Naehrstoffbedarf und Ertragsleistung von Sorghum-Hirsen (Sorghum vulgare var. sacch. und var. techn) unter gemaessigten Klimabedingungen. Z.f.Acker- und Pflanzenbau 122(3), 251–266. 4. DEMMLER, D., 1984: Versuche mit Zuckerhirse in der Pfalz. Deutsche Zuckerrueben Zeitung, Juni, 18. 5. KOSARIC, N., G.P. COSENTINO, A.WIECZOREK, 1984: The Jerusalem artichoke as an agricultural crop. Biomass 5, 1–36. 6. MILLER, F.R. and R.A.CREELMAN, 1980: Sorghum a new fuel. In: Papers annual corn and sorghum research conference, American Seed Trade Assoc., Corn and Sorghum Div. (35th), 219–232. 7. PAETZOLD, C., 1957: Die Topinambur als landwirtschaftliche Kulturpflanze. AID-Heft 4, 161 S. Herausgegeben vom Bundesministerium fuer Ernaehrung, Landwirtschaft und Forsten in Zusammenarbeit mit dem Land- und Hauswirtschaftlichen Auswertungs- und Informationsdienst e.V. (AID). Braunschweig-Voelkenrode, West Germany.

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8. REEVES, S.A., Jr., B.W.HIPP and B.A.SMITH, 1979: Sweet sorghum biomass. Part I, Agronomic Data. Sugar y Acucar 74, 23–30. 9. VILLECHANOUX, J.L., 1981: Une culture oubliée: le topinambour. Cultivar, Sept., 53–55.

THE POTENTIAL FOR STRAW AS A FUEL IN THE UK* L P MARTINDALE Energy Technology Support Unit AERE Harwell, UK Summary of the straw produced each year in the UK, some 7.5 million tonnes, equivalent to 2.4 million tonnes of oil (Mtoe), find no saleable outlet; this surplus is largely burnt in the field. However, straw could be put to cost effective use as fuel both on the farm and in local industry/institutions. Already, 166,000 tonnes/year (0.06Mtoe/y) are used on farms, and this could rise to around 0.9 million tonnes/year (0.29Mtoe/y) by the year 2000. Straw is just starting to be used as fuel off the farm, and it is estimated that use in rural-industry and institutions could reach 616,000 tonnes/year (0.20Mtoe/y) by the year 2000. Research, Development and Demonstration Programmes supported by the Department of Energy are designed to help bring forward and extend this potential; the total value of these Programmes is £0.55M.

1. INTRODUCTION The nature of straw production in the UK has changed rapidly since the 1960’s; the area under cereals has grown by 30%: the yields of grain have increased dramatically, although with a reduction in cereal straw heights: winter cereals have become commonplace: wheat is now more widely planted than barley, oats have all but disappeared, and oil seed rape has now become the third biggest crop: combine harvesters have taken over collection operations: animal numbers in cereal producing areas have fallen sharply. The consequence of these changes is that straw production has almost doubled, and utilisation has fallen. The “surplus” created is now largely burnt in the field, with concern over the resultant environmental (and public) impact recently leading to calls for a ban on burning. It is perhaps not surprising that the use of straw as a fuel in the UK is very much in its infancy. Rising fossil fuel prices in the 1970’s only then made straw an economic fuel for on-farm use, and the increasing availability of straw and pressure to find alternative uses for the surplus have since led to a rapid growth in utilisation as fuel. Suddenly, straw can now be an economically viable fuel for industrial users situated in arable areas, and with further increases in fossil fuel prices utilisation of straw is certain to grow. Hence the Department of Energy through its Biofuels R&D Programme and the Energy Efficiency Demonstration Scheme is actively supporting work to develop and demonstrate effective ways of using straw as fuel.

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* The views expressed in this paper do not necessarily represent the official views of either the Department of Energy or UKAEA.

2. THE STRAW RESOURCE Estimates by Silsoe College suggest that in the UK around 17.8 millions tonnes of straw are produced yearly (Ref. 1); the straw is produced predominantly in the East of England, away from livestock areas, and in the South-Midlands. Just over half is baled for use, primarily for animal bedding and feed. The remaining 7.5 million tonnes of straw (2.4Mtoe) are burnt in the field or ploughed in (Ref. 1)). Increases in straw yield and area point to a continuing rise in the production of straw. However, changes in the Common Agricultural Policy of the EEC are likely to limit the production of cereals, and a stabilising of the production of straw at around 15–16 million tonnes to the year 2000 is anticipated. Use in traditional markets is unlikely to expand significantly, and the fuel market is likely to become an increasingly important outlet for surplus straw (Ref. 2). 3. STRAW AS A FUEL Straw has a gross calorific value approximately the same as that of well seasoned wood (14.7GJ/tonne at 17% moisture content), one-half that of coal, and one-third that of oil. Straw has a very high volatile content compared to coal (75% cf 30%). In consequence, when it is burnt most of the combustion processes occur above the fuel bed. Volatiles are released and ignited at relatively low temperatures, but chars require much higher temperatures and more turbulent conditions to fully burn out. Straw is particularly well suited to burning in suspension, although it may be satisfactorily burnt on a grate providing it is relatively finely prepared. Straw may even be burnt in baled form, but the inherently low efficiency and slow combustion of this technique limits its application to small boilers used on farms. Many combustion techniques have been shown to be suitable for industrial scale utilisation of straw. For small boiler applications (up to 3MW) underfeed stokers integral with shell boilers have generally been used. For larger boiler applications, shell boilers using sprinkler stokers and coking stokers have been demonstrated in Denmark. The large furnace space associated with water-tube boilers appears to make them eminently suitable for the combustion of straw in suspension, although they have not yet been demonstrated in the UK. Straw may also in principle, be burnt in fluidised bed furnaces or cyclone furnaces external to waste heat boilers or kilns. Fluidised bed furnaces have not yet been demon-strated in the UK, although a 7.5MW cyclone furnace fired upon straw is shortly to be commissioned at Needham Chalks in a project supported jointly by the EEC and the Department of Energy. There may also be scope for direct substitution of coal by straw in existing boilers/furnaces. However, the differences in calorific values, specific densities, and volumes of combustion products will almost certainly limit the degree to which substitution is feasibile without significant downrating. This is the subject of a study

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currently being undertaken by Fuel and Energy Consultants, and supported under the Department of Energy’s Biofuels R&D Programme. 4. THE ECONOMICS OF USING STRAW AS FUEL There is a wide range of costs associated with getting straw from the field to it being used as a fuel. For example, straw has a value on the field, and there are costs to bale, handle, transport on farm, and to store. Typically, the acquisition cost for on-farm use as fuel is around £18/tonne. Additional costs for off-farm transport range from around £4/tonne for a 20km round trip, to at least £17/tonne for a 320km round trip (Ref. 2). Equipment to handle and combust straw is significantly more expensive than that for coal or oil because the market is smaller, larger handling and combustion plant is required for the same output, straw requires chopping or shredding plant, and storage requirements are considerably greater. Thus, although the cost of straw delivered in is much less than that for oil and coal, the cost per unit energy output from combustion plant may not be significantly less. Nonetheless, straw can certainly be a cost effective fuel for use on the farm. At the smallest scale, say 0.3MW thermal demand, automatically stoked straw fired boilers are not economic with respect to oil firing (because fuel cost savings are insufficient to recover the large difference in capital costs in a sensible period). However, against coal they are very cost effective, largely because of the high cost of small scale coal firing plant. For boilers of up to 1.5MW, straw firing can be a very attractive option, with payback periods of as little as 2 years versus coal and 4 years versus oil (Ref. 2). Straw can also be a reasonably cost effective fuel for use by ruralindustry and institutions. At the smallest scale, as on the farm straw fired boilers are not economic with respect to oil fired boilers, although they are with respect to coal fired boilers. For boilers of 1.5MW, straw firing offers payback periods versus oil firing of as little as 5 years, and versus coal firing as little as 3 years. For boilers of 4.4MW, straw is no longer cost effective with respect to coal, although it becomes increasingly attractive with respect to gas-oil (payback periods of 4 years or less) and heavy fuel oil (payback periods of 6 to 8 years). Although straw firing can still offer payback periods of around 10 years versus heavy fuel oil firing for boilers of up to 14MW, coal firing is clearly a much more attractive proposition with payback periods of as little as 2 years (Ref. 2). At present, there is no economic justification in hauling straw outside straw producing areas for use as fuel—the haulage costs are simply too great. Indeed, economic haulage distances within straw producing areas are substantially constrained. However, as fossil fuel prices rise there is no doubt that the economic case for using straw as fuel will improve, and longer haulage distances—to the more significant industrial markets— could become economically viable. 5. THE POTENTIAL FOR STRAW AS FUEL There is technology available that permits the processing and efficient combustion of straw over a wide range of outputs. The smallest boilers are already being used on-farm,

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while larger installations have been demonstrated in Denmark and will be demonstrated in the UK over the next few years. The best opportunities will be where high rates of utilisation can be achieved, where fuel costs are a significant proportion of total costs, and where straw is considered ‘credible’ because similar materials are already being handled. In the short term, the most significant outlet for straw as fuel is for on-farm applications. Already, there are around 7700 boilers in the UK that are at least in part fired by straw, and these consume around 166,000 tonnes of straw (0.06Mtoe) each year. Silsoe College have analysed the potential for use of straw on the farm; they report that the maximum utilisation of straw could be 1.9 million tonnes/year, and that use is likely to reach 0.9 million tonnes/year (0.29Mtoe/y) by the year 2000 (Ref. 3). Currently, straw is only marginally more attractive than coal as a fuel for ruralindustry and institutions, although the economics versus oil are generaly much better. The lead rural industrial markets have been identified as food and drink, fruit and vegetable processing, sugar, milk and milk products, cement and brick, and light engineering. The scale of these markets is large, and Silsoe College’s analyses suggest that up to 5.1 million tonnes of straw could in theory be used as fuel. However, a more realistic assessment is that use of some 386,000 tonnes of this (0.12Mtoe) annually could be realised by the year 2000 (Ref. 3). Silsoe College’s analyses also suggest that a further 230,000 tonnes/year could be being used by the year 2000 in the institutional/commercial sectors (Ref. 3). Although there has been a lot of interest in the briquetting of straw to produce a domestic fuel—and up to 1984 around 13 presses had been installed in the the UK—the high costs of compaction leads to a poor economic return to the producer, and little financial incentive for the user to switch from coal or wood. Thus, there is some uncertainty over the future of this market, reflected in an assumed market potential of no more than 115,000 tonnes of straw (0.04Mtoe) by the year 2000 (Ref. 2). 6. THE DEPARTMENT OF ENERGY’S RD&D PROGRAMMES Much of this assessment of the potential for straw as a fuel is based on an earlier study by Silsoe College, commissioned by ETSU on behalf of the Department of Energy (Ref. 3). Although a significant part of this potential is likely to be realised on the farm, the Department of Energy’s current RD&D programmes are designed to develop the off-farm markets, since: – more straw is produced than can be used on farms – use of straw off farms appears economically viable, but greater credibility needs to be established in the technology of processing combusting straw, and in the economics in real user-situations – off-farm markets could use at least 0.7 million tonnes of straw –more if lower cost compaction technology were developed. A series of combustion trials, to assess the degree to which chopped straw may substitute for coal in existing combustors, is currently being undertaken by Fuel and Energy Consultants.

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One industrial Scale Demonstration Project at Needham Chalks, has already been supported by the Department of Energy and the EEC. A 7.5MW cyclone furnace is being installed to dry chalk, saving some 580,000 litres of heavy fuel oil through use of 2000 tonnes of straw, and giving a payback period of 4 years. A much smaller scale demonstratlon, involving the installation of a 0.8MW boiler to provide space heating for an institutional application, has recently been offered funding by the Department of Energy. Further industrial scale demonstration projects are planned, involving straw supplying steam for process heat requirements, and these are likely to commence in 1985 or 1986 as discussions mature. A study to assess the scope for development of straw compaction machinery (designed to enable straw to economically replace coal in existing boilers/furnaces) has already been started, following on from the earlier Silsoe College Study. This work is being carried out by Silsoe College, in collaboration with Warren Spring Laboratory and Energy Options. REFERENCES (1) CLEGG, J M, LARKIN, S B C, NOBLE, D H, RADLEY, R W (1985), Straw as a Biomass Resource and its Aquisition in the United Kingdom. Proceedings of the 3rd Energy from Biomass Conference, CEC. (2) MARTINDALE, L P (1984). The Potential for Straw as a Fuel in the UK. ETSU Nl/84, ETSU. (3) CLEGG, J M, LARKIN, S B C, NOBLE, D H, RADLEY, R W. The Acquisition and Utilisation of Straw as a Fuel. Study carried out by Silsoe College on behalf of ETSU. To be Published, 1985.

IMMEDIATELY AVAILABLE LIQUID FUEL CROPS IN THE EEC H.STÜRMER, H.THOMA, E.ORTMAIER Technische Universität München Lehrstuhl für Angewandte landwirtschaftliche Betriebslehre, D-8050 Freising-Weihenstephan Summary It is possible to produce liquid fuel from many crops containing sugar, starch or oil, but right now only few agricultural plants can be converted to fuel with a satisfactory result. One reason is that for big scale production crops must be well known, widely spread and allow a relatively easy processing. Crops fulfilling these demands are e.g. cereals, maize, sugar beet, rape seed and sunflower, beet and rape being the most interesting from the economic point of view for large parts of Europe. This paper examines the costs of agricultural production with different methods and levels of yield and gross margins at EEC prices. The sensitivity to changing prices of fossil inputs is analysed. One result is that neither ethanol nor plant oil are competitive with gasoline or diesel at the present stage, but ethanol more than oil may become economic if prices of fossil fuel increase.

1. LIQUID FUEL CROPS Although crude oil prices were stable in the last years, it could become necessary to produce liquid fuels from biomass in the future due to various reasons. Two different levels of demand ought to be considered: A: Ad hoc production within one or two years for example after a sudden delivery failure. B: Long term partial substitution of crude oil within about the next fifteen years, to reduce dependence and to create new EEC agricultural markets.

Whereas in the long run many plants have to be examined on their energy use, right now few crops can be converted to fuel with a satisfactory result. This paper focuses on biofuel which could go into production right away. For that purpose some conditions have to be fulfilled: – The raw material should be a widely spread and will known crop with low production risk (Farmers will not make risky experiments). – The conversion process should be well known.

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– The end product should be suitable to normal engines. In the EEC ethanol from sugar beets as a petrol additive and rape oil as a diesel substitute seem to be promising. Different production methods and levels of yield (sugar beets 40t/ha, 47.5t/ha, 65t/ha, rapeseed 2.5t/ha, 3.0t/ha, 3.5t/ha) have been compared and the variable costs of production calculated. They vary from 1480DM/ha to 2200DM/ha (sugar beets) and from 1150DM/ha to 1430DM/ha (rapeseed), calculated on the base of 1980 energy prices, which are very similar to 1984/85 prices. Other price assumptions of course change production costs. These costs include an amount of 250 to 400DM/ha for direct (diesel, fuel oil, electricity) and indirect (seed, fertilizer, plant protecting agents) energy input, representing an equivalent of 17% to 23% of total variable costs. Ceteris paribus doubled energy prices increase production costs by about one fifth and cause a lack of gross margin which could be compensated by increasing the product prices between 6% and 10%. Former studies (1), (2), (3), (4) compare different prices for fossil fuel with biofuel, give more detailed information about production systems and levels of yield and discuss several crops and different models. 2. CONCLUSIONS Sugar beets and rape seed can be easily planted and processed, but at actual prices they are not competitive with fossil fuel, if no subsidy or tax exemption is granted. The actual monetary ratio between agricultural ethanol and gasoline is 2:1 and between rape oil derivates and diesel is 3:1 (taxes not considered). The prices of both crops are very insensible to changing oil prices, therefore rising oil prices improve their competitive ability considerably. It is expected that technical progress in agriculture and in conversion technology will cut down the costs per liter biofuel in future, but after all a political decision is necessary to start up biofuel production. 3. REFERENCES (1) STÜRMER, H., ORTMAIER, E. and THOMA, H.: Production Costs and Economics of Energy Plants at Rising Energy Prices. Bio Energy 84 World Conference, Göteborg 1984 (2) STÜRMER, H. und THOMA, H.: Energieverteuerung und Wirtschaftlichkeit nachwachsender Rohstoffe—Auswirkungen einer weiteren Energieverteuerung auf die Rentabilität der Nutzung nachwachsender Rohstoffe zu Energiezwecken. Eine ökonomisch-statistische Auswertung für vier ausgewählte Länder. Schriftenreihe des Bundesministers für Ernährung, Landwirtschaft und Forsten, Reihe A: Angewandte Wissenschaft Heft 290, Münster-Hiltrup 1983 (3) THOMA, H., ORTMAIER, E. und STÜRMER, H.: Auswirkungen steigender Energiepreise auf die Kosten variabler Input-Komponenten in der landwirtschaftlichen Produktion der BRD. 1aConferenza Internazionale Energia e Agricoltura, Vol. 3, P. 40/1–40/28, Milano 1983 (4) THOMA, H., ORTMAIER, E. and STÜRMER, H.: Effects of the Rising Price of Energy on the Variable Input-Factors in Agricultural Production. Bio Energy 84 World Conference, Göteborg 1984

ENERGETIC OUTLETS OF AGRICULTURE IN THE EEC J.J.BECKER CEMAGREF, division ENERGIE, ANTONY (France) Summary Since 1962, the progressive development of the Common Agricultural Policy (CAP) has led to reach or exceed self-sufficiency as far as the main agricultural produces are concerned. In a more general context, when defining the use of land no longer needed for food purposes the energy production from biomass was analysed and estimated from an economic viewpoint. A first comparison with alternative solutions was outlined. One of the main concerns in establishing Green Europe was to guarantee a sufficient supply of foodstuffs in the EEC. The increases in productivity enabled the objectives for satricto sensu self-sufficiency to be exceeded (vexed question of surpluses…). It would be necessary to question the exclusive use of agriculture for food production purposes which seems to be brought to a standstill as far as outlets are concerned. This research will firstly be based on a prospective evaluation of main foodstuff supply balances for 1990/1995. It would then be possible to assess the cultivated area not necessary for EEC food self-sufficiency. The results obtained are presented in the following table, land areas being classified according to their original use.

Table 1 SURPLUS LAND IN THE EEC As a result, 12 to 14 million hectares (i.e 12 to 14% of the EEC agricultural area) will produce surpluses for the 1990/1995 years unless new outlets are not defined by the time.

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The analysis of energy outlets for agriculture takes an exhaustive survey of energy processes from biomass as a basis and leads to energy vectors suitable for meeting all requirements. The procedures in use in agribusiness (particularly in sugar industry) would be applied to this production namely: – decentralized agricultural production, the charge of which would generally be taken on by numerous independent farmers. – collection and processing taken on by an industry (possibly a cooperative) An economic assessment of the various processes was made in two stages: – determining the cost of agricultural raw materials in various farming systems (cereals, cattle-milk, cattle-beef). The cost was defined as the lowest price that keeps steady agricultural income at the same level. – calculating agricultural raw material conversion coste in various units. Their size was optimized in terms of collection costs as well as economies of scale that could be made at the conversion level. As shown in the diagram 2, the most interesting energy production routes are reviewed and the production cost ranges of the various energy vectors obtained are mentioned. Some conclusions can be drawn up from now on: – the competitiveness of energies produced from biomass compared with fossil energies is not get reached taking both heat and fuel production into account. – energy vectors drawn from a lignocellulosic biomass crop are the nearest to economic profitability. – ABE mixture is not competitive with ethanol. But its main advantage consists in its use as a co-solvent for methanol. The above analysis of economic factors enable to make a first comparison among other potential uses for “surplus lands”. Three different options are taken into account: – following current trends, which means either selling foodstuff production on the world markets, or on the EEC markets at preferential prices. It implies regulation costs that can be estimated from the average cost entailed by the elimination of agricultural surpluses in the EEC countries during the last decade. – developing protein production for animal freeding. EEC is particularly poor in feedstocks and imports great amounts of soya cakes. This option can be evaluated on the basis of rape internal production. To compete with imported products, protein production must be supported by direct subsidies, the amount of which can be assessed by means of studies concerning that production in the last decade. – freezing surplus lands. Its cost can be evaluated on the basis of the unemployment benefits that must be paid in case of original farming activity cessation, that is to say 58 000 FF per worker. Conclusions from the comparative analysis are given in the following figure(3) in terms of right amount of subsidies per hectare to be paid to implement

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DIAGRAM 2 ENERGY PRODUCTION ROUTES FROM BIOMASS each project in the best possible way. In order to assess the subsidies to be granted for energy activities breakeven prices for energy from biomass are defined using the most competitive fossil energies as point of reference: coal for heat production, high-grade gasoline and Diesel fuel for mechanical energy production. As for alcohols, two methods of calculation were followed: in case of high level blends with gasoline substitution made on a thermal unit basis (supposing an little improvement in engine efficiency…) and in case of low level blends substitution made

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on a volume basis (in the second case methanol from biomass is compared with methanol from natural gas)

Figuer 3 AMOUNT OF SUBSIDIES REQUIRED

From the economic profitability point of view, the confrontation of the various data collected shows that energy production will bring a more positive contribution than competing options. Still we have to choose the best technical processes. Indeed, those factors are insufficient to bring the study to a close the effects on the balance of payments should be examined and the assessment of conventional options (export or protein production) should be, of course, refined.

THE DEVELOPMENT OF WETLAND ENERGY CROPS IN MINNESOTA, USA MANAGING STANDS FOR CONTINUED PRDUCTIVITY D.R.DUBBE, E.G.GARVER, and D.C.RATT Bio-Energy Coordinating Office University of Minnesota Summary Through a combination of basic and applied research covering biomass production, harvesting, land use planning, and economics, the BioEnergy Coordinating Office at the University of Minnesota is in the process of generating multiseasonal information critical to an evaluation of the commercial potential of using emergent aquatic plants grown on marginal lands as sources of bio-energy.

1. INTRODUCTION Emergent aquatic plants such as Typha (cattail), Phragmites (reed), and Scirpus (rushes) are of interest for bio-energy production in Minnesota because of their high productivity, and the fact that they grow naturally on a substantial portion of the state’s 3.5 million hectares of wet marginal lands (1). Evaluation of the commercial potential of emergent aquatic plants as an energy source depends on an understanding of the tradeoffs between productivity and production costs. Research at the University of Minnesota has sought, through a multidisciplinary program, to generate the information base needed to make this evaluation. Projects involving production, equipment development, land use planning, and economics have been supported and coordinated through the University’s Bio-Energy Coordinating Office. Typha species have received the greatest attention because of their superior productivity, pest resistance, and adaptability to wide ranging wetland conditions. This paper highlights several current projects examining aspects of stand establishment, management, and harvesting. 2. STAND ESTABLISHMENT METHODS AND PRODUCTIVITY As shown in Table I, field experiments have demonstrated that Typha stands can be successfully established by transplanting seedlings or rhizome pieces and, in one case, planting seed. The values shown in Table I are aggregates from several field experiments

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examining various aspects of Typha stand management. Because of this, the values do not represent the maximum productivities that have been achieved within individual experiments. Table I does, however, provide insights into factors affecting multiseason Typha productivity. The most important stand establishment factors affecting productivity appear to be the species of Typha selected and the initial planting density. Contrary to expectations based on natural stand studies (2), Typha latifolia appears to have lower biomass yields than either Typha angustifolia or the hybrid Typha×glauca. The lower yields may be attributable to increased flowering, lower shoot densities, and increased competition from competitors. Planting density appears to affect productivity by increasing shoot density in years subsequent to establishment. In Table I, the Typha angustifolia established from seed had an initial density of 41 plants/m2 compared with 5–9 plants/m2 for other experiments. This translated into an equilibrium shoot density of 100/m2 for Typha angustifolia, whereas the equilibrium shoot density was 40/m2 for the other experiments.

Table I. Multiseason Productivity of Typha spp. SPECIES

EST. ESTABLISHMENT SECOND THIRD SEASON METHOD* SEASON SEASON PRODUCTIVITY PRODUCTIVITY PRODUCTIVITY (T/ha) (T/ha) (T/ha)

SHOOT TOTAL SHOOT TOTAL SHOOT TOTAL 0.5 0.9 13.9 21.5 11.6 25.2 1.7 4.5 4.9 11.7 8.8 16.5 0.0 0.1 2.2 5.1 6.0 11.0 6.7 12.8 (NOT ATTEMPTED) GLAUCA T 3.1 7.7 6.6 14.5 8.0 17.4 * Establishment Method: S=Seeded; T=Transplanted TYPHA ANGUSTIFOLIA TYPHA LATIFOLIA TYPHA X

S T S T S

The costs associated with planting stock and transplantation, which also limit as well initial plant density, necessitates the development of methods for direct seeding. Methods designed to optimize site conditions for germination and early plant growth have been attempted in greenhouse, small paddy, and field experiments with mixed results. Dry seeding requires precise control of soil moisture for germination and early growth to occur. Too little moisture inhibits germination and stimulates weed growth; too much moisture can lead to a redistribution of seeds or death of young seedlings. Hydroseeding overcomes the problem of germination, but still requires a narrowly defined environment for continued growth in the month following application. Experiments are currently underway examining modifications of previously successful methods which would increase their reliability in field situations.

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3. STAND MANAGEMENT Following the initial establishment phase of the production process, management of Typha stands becomes critical for maintaining high sustained productivity. Pest control, nutrient input requirements, and water level control are of primary concern. Pests, in the form of weeds, insects, and herbivores, have been studied, but currently do not appear to seriously reduce productivity in either natural or managed stands of Typha (3). Because of this, current research is focused on gaining a better understanding of nutrient uptake patterns, nutrient requirements, and water use of Typha spp. Fertilizer represents a potentially large input into the Typha production system. Nitrogen is of primary interest because of its cost and potential for loss through denitrification. Basic research examining the magnitude of denitrification losses, factors affecting low level associative nitrogen fixation (4), and the role of mycorrhizae in nutrient uptake is currently being conducted. Complementing these basic studies have been field studies examining seasonal nutrient uptake and alternative methods of fertilizer application. A two year field study examining seasonal biomass accumulation, nutrient uptake, and biomass/nutrient partitioning between the above–and belowground portions of Typha sought to provide information that could be used to: 1) develop a fertilization schedule that would minimize nutrient losses by timing application to coincide with the period of greatest nutrient uptake, and 2) develop a harvesting schedule that would minimize nutrient removal (3). Figure I presents results of this study for nitrogen; phosphorus and potassium accumulation follow similar patterns.

Figure I. Seasonal nitrogen accumulation for Typha spp. during the

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establishment and second growing season. During the establishment season (planting date=June 9), growth was in a lag phase until early August, and maximum biomass accrual occurred between the sampling dates of August 4 and September 2. Forty-six percent of the season’s total biomass was produced during this period. The greatest amount of each nutrient (g/m2 basis) was also taken up in this period with 48%, 46%, and 48% of the season’s total N, P, and K accrued, respectively. During the last two months of sampling, changes in partitioning of biomass and nutrients occurred, with total plant biomass and nutrients continuing to increase but with shoot biomass and nutrients decreasing and rhizome biomass and nutrients increasing rapidly. The period of maximum biomass production in the second year occurred at the same time as in the first year in terms of shoot age (between 56 and 84 days after plant growth began), but this period was reached one month earlier during the second season. Additionally, in most cases greatest nutrient uptake preceeded the period of greatest biomass production in the second season. Biomass and nutrient partitioning was similar to that occurring in the establishment season. The patterns of nutrient and biomass accrual observed in this experiment can serve as a starting point for testing Typha stand management options such as time of fertilization and harvesting. If fertilizer, particularly nitrogen, had been applied to these plots at the beginning of the growing season, much of it may have become unavailable through physical and biological processes before it could be used by Typha. Methods of midseason application are being examined. This study also suggests that harvest of aboveground material could take place as late as the end of September without much sacrifice in aboveground biomass, and that fewer nutrients will be removed from the system at this time. Another potentially positive factor of a late harvest is that the biomass may be drier by the end of September. For these experiments, moisture percent had dropped from a mean of 76% in early September to 72% in late September. These values may be more or less, depending on weather conditions. Although total plant biomass increased throughout October, aboveground biomass decreased, and plants lodged, making harvest difficult. Plant water requirements and water level control are another area of stand management currently under investigation. Although Typha will be grown on wetlands, irrigation and water control may be necessary to ensure optimum conditions for growth and accessibility by harvesting equipment. Based on preliminary experiments, Typha evapotranspiration in Minnesota appears to be about twice that of two common agricultural crops, Zea mays and Medicago sativa. A study supported by the Herbaceous Biomass Program of the U.S.Department of Energy (DOE) will be conducted this summer to determine water loss of three species of Typha under various water management scenarios. 4. HARVESTING When Typha was first being considered as a biomass candidate, one of the attractive features of the plant was the belowground rhizome system consisting of about 50% of the

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total plant biomass and composed of 40% starch and sugars. As a result, agricultural engineers began an equipment development project to develop a rhizome harvester based on existing agricultural equipment. An experimental potato harvester was modified and successfully tested in field experiments (5). The harvester is capable of cutting and lifting strips of soil and rhizomes. Further studies on methods of separating rhizomes from soil are currently underway. Because of the difficulty and potential expense of harvesting rhizomes, the uncertainly as to how a rhizome harvest would affect subsequent year’s productivity, and largely unspecified compositional requirements for biomass, a simpler harvesting system involving shoot biomass only is being considered. With support from DOE, a new study was begun at the end of 1984 to evaluate sustained productivity under three harvesting scenarios in both natural and managed stands of Typha. The three harvesting scenarios include: 1) shoot biomass only, harvested annually, 2) shoot biomass only, harvested semiannually, and 3) shoot biomass harvested annually, rhizome biomass harvested biennially. 5. CONCLUSIONS Information generated from multiseason studies of Typha spp. is being used to suggest and evaluate biomass production options that will result in high sustained productivity, while at the same time minimizing production costs. At this point in time, Typha spp. remains a promising biomass candidate for production on wet marginal lands. Further information on sustained productivity under different harvesting scenarios is being gathered which should allow a final evaluation of Typha’s potential within the next several years. REFERENCES (1) CENTER FOR URBAN AND REGIONAL AFFAIRS. (1981). Available wetlands for bioenergy purposes: Lane use and drainage constraints. Map produced under contract with the Minnesota Energy Agency. (2) PRATT, D.C., ANDREWS, N.J., GLASS, R.L. and LOVRIEN, R.E. (1981). Production of Wetland Energy Crops in Minnesota--an update. Proceedings of Biomass Workshop sponsored by Midwest Universities Energy Consortium, pp. 158–175. (3) PRATT, D.C., DUBBE, D.R., GARVER, E.G. and LINTON, P.J. (1983). Wetland Biomass Production: Emergent Aquatic Management Options and Evaluations. Final report to the Solar Energy Research Institute. 74 pp. (4) BIESBOER, D.D. (1984). Nitrogen fixation associated with natural and cultivated stands of Typha latifolia L. (Typhaceae). American Journal of Botany 71:4, pp. 505–511. (5) SCHERTZ, C., DUBBE, D.R. and PRATT, D.C. (1983). Harvesting Cattail (Typha spp.) Rhizomes as an Alternative Feedstock for Alcohol Production: Modifications of Potato Harvester. Final report to Dept. of Energy—Alcohol Fuels Division under subcontract DOE/DE-FG07–811D12343. 19 pp.

ENERGY FROM AGRICULTURE—SOME RESULTS OF SWEDISH ENERGY CROPPING EXPERIMENTS U.Wünsche Department of Plant Husbandry Swedish University of Agricultural Sciences Summary Within the project Agro-Bioenergy surveys are made of the yields of various energy crops in Sweden. Some results of these energy cropping experiments are given. Tops of Jerusalem artichoke (Helianthus tuberosus) can be used for biogas production. The highest yields obtained was 20 tons of dry matter per ha. Winter wheat varieties with a high yield of starch for ethanol production have been tested since 1981 in 10 field trials in different parts of Sweden . In a number of cases some of the tested varieties yielded more than 10 tons of grain per ha. Also root crops for ethanol production have been tested. In six field experiments in different parts of Sweden the yields of four grass species are compared at six different harvesting times and at four nitrogen levels. The results obtained hitherto show that several agricultural crops may be of interest for energy purposes owing to their ability to give high dry matter yields.

1. INTRODUCTION Energy cropping research at the Swedish University of Agricultural Sciences started in 1979. At present it is being conducted within the framework of the Agro-Bioenergy project and is financed by the National Energy Administration. It is an interdisciplinary project ranging over several subject areas such as plant husbandry, microbiology, chemistry, technology and economics. The aim of the project is to identify possible fuel crops in agriculture and which kinds of energy carriers can be processed from these raw products. Surveys are made of the yields of various energy crops under different production conditions. Some results of these energy cropping experiments are given below. 2. JERUSALEM ARTICHOKE FOR BIOGAS PRODUCTION The idea to use Jerusalem artichoke (Helianthus tuberosus L.) as an energy crop is not new. It has been tested for production of ethanol and also for production of an alternative sweetener (fructose) (1), (2), (4), (5). In our experiments we have studied the possibility of producing biogas (methane) from the above-ground parts of the plant. Three varie-ties were tested, one of which (No. 1168) is a hybrid of Jerusalem artichoke and sunflower. The tubers were planted in early

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May in rows spaced at 70cm with 33cm between the tubers at a depth of about 7cm. The total amount of nitrogen fertilization corresponds to 100kg N /ha. Beginning in the first week of September the above-ground parts of the plants were harvested. Four harvesting times at intervals of two weeks were compared. The dry matter yields are given in Fig. 1. The tested varieties are adapted for high tuber production in Central Europe but are rather late in tuber production under long day conditions. Normally they did not flower in our field. At this latitude tuber production does not start until late September, but instead the plants produce a strong vegetative growth of stems and foliage. The highest yield obtained was 20 metric tons of dry matter per hectare. An advantage of Jerusalem artichoke as an energy crop is that it can be kept as an permanent crop. The tubers can be left in the soil over the winter period to produce a new crop in the following year. Anaerobic digestion experiments have shown the possibility of producing biogas from both fresh and ensiled above-ground parts of Jerusalem artichoke (6).

Fig. 1. Dry matter yields of tops of two varieties of Jerusalem artichoke at four harvesting times. First, second and third year after planting. 3. WINTER WHEAT AND ROOT CROPS FOR ETHANOL PRODUCTION If wheat is to be used as raw material for ethanol production one could reduce some of the demands concerning baking quality Therefore, it is of interest to test varieties with poorer baking quality and low protein content but with a high yield of starch. Such wheat varieties have been tested since 1981 in 10 field experiments in different parts of Sweden. In a number of cases some of the tested varieties yielded more than 10 tons of grain per hectare. The results of the field experiments with wheat are summarized in Fig. 2. In the near future a maximum starch production per unit area will be the most important goal. In the long run, however, also the content of cellulose and hemicellulose could be transformed to ethanol in an economical way. In this situation the total dry

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matter yield would be the most essential goal and hence the straw yield will also be of importance. of course, this would also be the case if the ceral crop is to be used as a solid fuel for direct combustion.

Fig. 2. Grain yields (15% moisture content) of seven winter wheat varieties. To the left: mean values for 10 experiment sites, 1981–84 (35 trials). Holme=6970 kg/ha. To the right: mean values for 16 trials in Scania (south Sweden). Holme=7480 kg/ha. Different types and varieties of root crops (sugar beet and fodder sugar-beet) have been tested in field experiments. Root crops could be used for production of ethanol as well as biogas. Results of trials in different parts of Sweden during 1981–1984 are summarized in Fig. 3.

Fig. 3. Dry matter yields of sugar beet and fodder sugar-beet varieties. Mean

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values for six experiment sites, 1981– 84 (25 trials). The hatched parts of the bars indicate the amount of sucrose. The variety Kyros, a fodder-sugar beet, had an average yield of 57 tons of roots per ha against 40 tons for the sugar beet varieties. As the sugar beet varieties had a considerably higher dry matter content than the fodder sugar beet, the dry matter yield was almost the same for all varieties, on average arond 10 tons per ha of which 7–7.5 tons consists of sucrose. 4. ENERGY GRASS Grass can be used as a solid fuel or for the production of biogas. In six field experiments in different parts of Sweden the yields of four grass species are being compared. The following species were tested: Timothy (Phleum pratense), Smooth bromegrass (Bromus inermis), Reed anary grass (Phalaris arundinacea) and Tall fescue (Festuca arundinacea). The experiments include six different times of the first harvest (15 June, 1 July, 15 July, 1 August, 15 August and 1 September) and a second harvest on 1 October. In another series of field trials the yields at four different levels of nitrogen application are compared. The nitrogen levels are 0, 100, 150 and 300kg N per ha. Depending on species, harvesting time, nitogen level and site of experiment, the yields varied between 3 and 17 tons of dry matter per ha (total of two harvests). Tall fescue often yielded more than other species, especially in areas with high precipitation. The optimal harvesting time varied with location of the field trials. On average,the highest total yields were obtained with the first harvest in the middle of June and the second harvest on 1 October. 5. DISCUSSION In this paper, illustrated with a poster during the conference, only part of the energy cropping experiments within the Agro-Bioenergy project have been dealt with. In addition for example we are comparing short rotation forestry (different species of Salix) with agricultural crops on farm land. However, no conclusions can yet be drawn from the results as the experiments have been carried out for only four years. The project has been restricted to the cultivation of energy crops on arable land with the aim of studying the entire system from cultivation to the use of the produced energy carrier. The results obtained hitherto show that several agricultural crops may be of interest for energy purposes owing to their ability to give high dry matter yields per hectare. Thus, for example the cultivation experiments and assessments of plant breeding possibilities show that in the year 2000 it would be possible in practical production to obtain yields of 7–15 tons of dry matter per ha for energy grass, winter wheat and sugar beet. Even higher yields may be obtained if high-yielding crops suitable for production of biogas are chosen.

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Chemical analyses show that in addition to the energy raw products, also considerable amounts of by-products with different ranges of use are obtained in many cases, e.g. as feeds for domestic animals. Valuable chemical components can be used in technology as chemical raw products (7). The introduction of fuel crops on agriculural land naturally depends on the economic conditions. In a systems analytic approach the following issues have been penetrated: Can energy from agriculure compete with other alternatives? Is energy cropping competitive with food cropping? How do energy crops from agriculture affect the national economy of Sweden? (8), (9). REFERENCES (1) SHOEMAKER, D.N. (1927). The Jerusalem Artichoke as a Crop Plant. U.S. Dep. of Agr. Technical Bulletin No.33, 1–32. (2) STAUFFER, M.D. (1979). Jerusalem Artichoke—What is its Potential Inter-Energy 79. Proceedings. Agriculture. R3M 357 Manitoba, Canada Oct. 1979. XXIII: 1–5. (3) KOSARIC, N., COSENTINO, G.P., WIECZOREK, A. & DUVNJAK, Z. (1984). The Jerusalem Artnichoke as an Agriculural Crop. Biomass, 5, 1—36. (4) CHABBERT, N., BRAUN, Ph., GUIRAUD, J.P., ARNOUX, M. & GALZY, P. (1983). Productivity and Fermentability of Jerusalem Artichoke According to Harvesting Date. Biomass, 3, 209–224. (5) CHUBEY, B.B. & DORELL, D.G. (1974). Jerusalem Artichoke, a Potential Fructose Crop for the Praries. Can.Inst. Food Sci.Tech.J., 7: 98–100. (6) GUNNARSON, S., MALMBERG, A., MATHISEN, B., THEANDER, 0., THYSELIUS, L. & WUNSCHE, U. (1985) Jerusalem Artichoke (Helianthus tuberosus) for Biogas Production. Biomass, 7: in print. (7) THEANDER, O. (1985). Cemical Investigations in the Swedish Agrobioenergy Project. Third EC Conference Energy from Biomass, March 25–29, 1985, Venice, Italy. PIII/208. (8) BERGMAN, K.-G. (1982). Energy from Agriculture—Economic Aspects. Swedish Univ. Agric. Sciences, Dep. of Economics and Statistics, Report no. 205. (9) GUNNARSON, S., HANSSON, K. & JOHNSSON, B. (1984). Economic Studies of Fuel Crops in Swedish Agriculture. Unpublished stencil. Dep. of Economics and Statistics, Swedish Univ. Agr. Sciences, o Box 7013, S-750 7 Uppsala, Sweden.

EPURATION DES EAUX ET PRODUITS DE HAUTE VALEUR TIRES DE LA JACINTHE D’EAU F.SAUZE Station d’Amélioration des Plantes—INRA, 9 place Viala 34000—MONTPELLIER FRANCE Summary The culture of waterjacinth, especially studied and practised in hot countries, is also possible under temperate climates, with yields of 30 to 50 tons/ha of dry matter, data which proceed from recent experiences in FRANCE. Wastewaters constitute a particularly convenient medium of culture, from a double economic and environmental point of view, and are efficiently depolluted by plants of this species. Study of feasibility shows that processes including production, methanization, and valorization of biomass with products contained in sludges of digestion, would be able to give an income competitive with these of conventional sources.

I. INTRODUCTION La culture de la jacinthe d’eau a été surtout étudiée dans les pays chauds, assez peu dans les climats tempérés ou froids. Or cette plante peut y presenter un intérêt tout aussi grand, car même sous de tels climats ses potentialités se montrent souvent supérieures a celles d’autres espèces, notamment terrestres, tant pour la productivité gue pour la composition chimique. En outre il semble possible, dans les regions tempérées, d’accroître sa durée annuelle de végétation, soit en recouvrant la culture d’un abri durant la mauvaise saison, soit en utilisant un réchauffage de l’eau à l’aide de calories de récupération. Cependant, diverses expériences réalisées en FRANCE au cours de ces dernières années, à l’échelle de petits bassins pilotes, ont montré qu’en atmosphére naturelle et sous climat assez ensoleillé, on peut escompter une période productive de plus de six mois, permettant une production totale en biomasse sèche supérieure a celle de toute autre culture. Bn climat plus méridional, ceux des pays méditerranéens par exemple, des rendements plus élevés encore pourraient être obtenus. Compte tenu de ces résultats expérimentaux, des opérations pilote à échelle réelle sont actuellement entreprises. et une approche est tentée pour prévoir la faisabilité d’un système de culture et de valorisation.

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II. ESTIMATION DU POTENTIEL EN BIOMASSE ET DU POUVOIR EPURATEUR Sur le tableau I sont portéesles durées des périodes culturales et les productivités moyennes obtenues dans les principales expériences réalisées en FRANCE, à diverses latitudes allant de celle du littoral méditerranéen à celle de PARIS, les périodes de croissance s’étalant sur 6 à 7 mois. et la température de l’eau variant de 5 à 30°C. Toutefois deux expériences, celles de l’E.D.F. (Electricité de FRANCE), et celle du C.E.N. (Centre d’Etudes Nucléaires) ont été effectuées en eau réchauffée par rejets thermiques. En conditions naturelles, on peut retenir une productivité probable de 15 à 20. de matière sèche (MS) par m2 et par jour dans les régions Nord, (Centre, Bassin Parisien, Loire) et 25 à 30g/m2/j. dans la zone méridionale. Ces valeurs correspondent à des rendements à l’hectare de 30 et 50t. de MS environ, Des rendements plus élevés peuvent être espérés pour l’avenir, grâce à des améliorations génétiques de l’espèce. et à l’op-imisation des méthodes culturales.

Tableau I Expériences de culture des jacinthes d’eau sur divers milieux en atmosphére naturelle. Lieu VERSAILLES ST.LAURENT DES EAUX PIERRELATTE

Milieu de culture

Temp.eau (d°C)

Période culture (j)

Synthétique Eau de la LOIRE réchauffée Eff luent de pisciculture réchauffé

5–20

185

13,9

INRA 1983

15–30 11,7–26

135 204

33,0 20,0

EDF 1983 CEN-VALRHO 1984

24,3 25,4

INRA 83–84

SALLES D’AUDE

ST. GELY DU FESC TOULOUSE

– brut – laguné Effluent urbain secondair Effluent urbain secondaire

Effluent urbain 8,5–31 190 8,5–31 190 données non encore communiquées 6–25 180

Product. Référence Moy. –2–1 g m j

CNRS 1984 22,0 HYDRO-M 1983–84

L’influence du type de milieu nutritif sur les rendements ne senible pas prépondérante, mais elle modifie comme on le verra la composition chimique du vegetal. L’absorption par la plante des éléments constituant la pollution des eaux résiduaires urbaines a fait l’objet de nombreux essais, en particulier ceux de l’INRA et du CNRS dans le LANGUEDOC. La méthode a consiste au départ à ensemencer des bassins d’environ 20m2, situés en bordure d’une station de lagunage, et ces premiers essais se prolongent actuellement par une expérience de culture dans des lagunes réelles, avec 350m2 de culture. Bien que les biomasses produites sous cette latitude soient un peu inférieures à celles de DISNEYWORLD en FLORIDE, les taux d’élimination des principaux polluants ont été au moins équivalents.

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III POTENTIEL EN PRODUITS CHIMIQUES ET EN ENERGIE. La composition chimique d’Eichhornia en fait une plante spécialement intéressante parmi les espèces aquatiques. La teneur en protéines de la biomasse produite en milieu eutrophe peut atteindre 35% du poids sec, ces protéines renfermant plus de 30% d’acides aminés essentiels pour l’alimentation. Cependant certaines filières de valorisation plus complexes incluent l’extraction d’autres produits, doues de pouvoir énergétique par exemple, et fournissant un résidu ou un tourteau qui renferme sensiblement autant de protéines que la plante d’origine. La filiére méthanique a été la mieux étudiée, aux ETATS-UNIS et en FRANCE notamment, avec des rendements en biogaz qui sont les plus élevés parmi ceux obtenus avec un substrat exclusivement végétal. La production potentielle d’un ha d’Eichhornia peut dépaseer 15.000m3 de méthane à l’ha, représentant une énergie bien supérieure à celle d’l ha de culture alcooligéne (4.000l/ha). Le bilan énergétique reste supérieur à celui de la plupart des filières de la biomasse. L’énergie pourrait être également extraite par d’autres filières de conversion, notamment celle des corps gras, qui constituent de 1,5 à 3% de la matière sèche. Le tableau II indique les potentialités en huiles de la jacinthe d’eau ainsi qu’en protéines exploitables dans les tourteaux, en comparaison avec celles d’autres espèces aquatiques et de cultures actuelles sur sol. Le rendement d’Eichhornia serait supérieur en huile à ceux des oléagi neux terrestres courants en climat tempéré (0,4 à 1,5t d’huile/ha) et très largement supérieur en protéines à ceux des meilleurs protéagineux telles gue les légumineuses: 15t/ha (contre 0,5 à 3).

Tableau II Rendements en matières grasses et en protéines de diverses plantes aquatigues (climats tempérés). Végétaux Micro-algues Macro-algues (Fucus) Jacinthe d’eau (Eichhornia) Lentille d’eau (Lemna)

Teneur en Rendement en Teneur en. Rendement en huiles %M S huiles T/ha protéines protéines T/ha 9–53 2–11 1,5–3 3–4

9–53 0,1–0,8 2–4 1–1,5

8–57 7–10 25–35 25–30

50–94 3–4,5 15–18 3–5

Les matières grasses d’Eichhornia sont surtout à base d’acides gras saturés et conviendraient à la fabrication de carburants, lubrifiants, savons, et produits divers d’industrie chimique. De très hautes teneurs en phosphore—jusqu’à 2,7%—ont été observées chez les plantes issues de nos cultures en eau résiduaires, partiellement sous forme de produits de haute valeur telle que phospho-lipides. Pour l’obtention de carburants lé-gers, les huiles brutes peuvent être estherifiées ou crack ées, mais il serait également possible de les utiliser telles quelles dans certains moteurs diesel ou du type

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Stirling. Cependant le coût des huiles végétales, comparé à celui des hydrocarbures fossiles, pourrait être un obstacle à cette utilisation. Cesdivers produits riches se retrouvent encore, au moins partiellement, dans les digestats issus de la méthanisation. La concentration en matière sèche y est souvent supérieure a celle de la biomasse d’origine, ce qui constituerait un avantage économique pour le traitement dans les huileries ou les usines d’aliments, et le bilan énergétique de la filière complete serait amélioré par la production de biogaz. Une autre option consiste à utiliser le digestat comme compost agricole, dont la valeur fertilisante réside non seulement dans ses éléments nutritifs, mais en outre dans des stimulateurs biologique, également présent dans les jus de jacinthes d’eau. III FAISABILITE ECONOMIQUE Pour tenter de préciser la faisabilité et le coût du système, une étude chiffrée à été réalisée sur le modèle suivant: – Unité de 10ha de bassins d’épuration et de culture, application de la filière: eau résiduaire urbaine → méthane → valorisation du digestat, avec 2 variantes. valorisation comme fertilisant (compostage). . valorisation comme aliment de bétail. – Population desservie par les bassins de culture—épuration: 20.000habitants. – La production de biomasse est de 500 tonnes MS/an, celle de biogaz de 150.000m3/an. On admet que les frais de personnel sont répartis par moitié, entre le fonctionnement habituel de la station communale pour l’épuration et celui de la filière introduite. En échange, la commune bénéficie de la surprime encaissée du fait de la qualité accrue de l’effluent sortant. (0,25 F/m3). Une fraction du biogaz (20%) est auto-consommée. Les valeurs admises pour les produits sont: biogaz 2F/M3, Compost 300F/t; aliment 4.000F/t de protéine. On aboutit ainsi à un coût de la biomasse de 1.100F à la tonne de MS. Les bénéfices correspondants sont respectivement dans le cas de l’aliment et dans celui du compost de 824 et 17 4F., assurant un temps de retour de sept ans environ dans le premier cas.

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Dimension nécessaire de l’unité de production en fonction du bénéfice escompté. Il est évident que ce bilan est fortement influencé par la dimension de l’unité pilote, correspondant à la population désservie. Le graphique ci-dessus montre les seuils dimensionnels permettant d’escompter un niveau de rentabilité donné pour les deux options. Celle du compostage devient bénéficiaire pour une population d’au moins 10.000 à 15.000 eq. habitants, tandis que celle de l’aliment rapporte déjà près de 0,F 50 par kg de MS. pour moins de 1000 e-h. On constate gue dans la mesure des disponibilités en capitaux et en terrain, il y a intérêt a accroitre la superficie cultivée, même au-delà du minimum qu’impose la seule finalité de l’épuration des eaux. On peut également penser, en vue d’accroître la rentabilité, à traiter en mélange avec les jacinthes d’eau divers déchets urbains ou agroalimentaires, souvent disponibles en plus des eaux usées domestiques : boues d’épuration, ordures ménagères, déchets industriels liquides ou solides, grâce auxquels les équipements de conditionnement, transport, et méthanisation fonctionneront plus longtemps dans l’année. Par ailleurs il n’est pas exclu d’envisager pour l’avenir une valorisation supplémentaire par le phytoplancton, qui offre souvent des potentialités non moins prometteuses que les plantes supérieures. Des progrès notables restent toutefois à accomplir pour améliorer la faisabilité de sa récolte. Dans l’immédiat le système à macrophytes. même limité à son fonctionnement estival, apparaît comme techniquement et économiquement réalisable. La culture sur les milieux nutritifs constitués par les eaux résiduaires et autres déchets paraît être la plus intéressante. grâce à la simplicité et au faible coût de revient par rapport à ceux des cultures en conditions artificielles telles qu’atmosphère contrôlée. effluents thermiques, nutrition par engrais du commerce. Le système peut facilement s’insérer dans les unités existantes de traitement des eaux de type classique ou du type lagunage, et il y aurait grand intérêt à l’adopter dans les futures stations à édifier. BIBLIOGRAPHIE DINGES R. (1978) Upgrading stabilization pond effluent by waterhyacinth culture. Journ. Wat. Poll. Control. Fed, mai, 833–845 SAUZE F. (1983) Culture de jacinthes d’eau sur eau résiduaire. In “Valorisation de la jacinthe d’eau : EDF-DER. série A 3/4,27–33 CHATOU SAUZE F. (1983–1984) Croissance de la jacinthe d’eau en eau résiduaire urbaine, et effet épuratoire de la culture. Ecologia Mediterranea; T.IX, 3/4 55–77 et TX 3/4, 51–73 REDDY K.R. et SUTTON D.L. (1984) Waterhyacinth for guality improvement and biomass production. J. Environ. Qual. 13, 1, 1–6 WOLVERTON B.C. et Mac DONALD R.C. (1979). Upgrading facultative wastewater lagoons with vascular aquatic plants. Journ. Wat. Poll. Control, 51 n° 2, 305–213.

AN INTEGRATED SYSTEM : MASS ALGAE CULTURE IN POLLUTED LUKEWARM WATER FOR PRODUCTION OF METHANE, HIGH-VALUE PRODUCTS AND ANIMAL FEED. A.Legros**, E.Dujardin* , F.Collard* , H.Naveau** , E.J.Nyns** and C.Sironval* . *Laboratoire de Photobiologie. Université de Liège. B.22, Sart Tilman. Belgique. **Ûnité de Génie Biologique. Université Catholique de Louvain. Place Croix du Sud, 1, Bte 9; B-1348, Louvain-la-Neuve. Belgique. Summary An integrated cyclic system for mass algae culture has been set up. Its various processes, shown in figure 3, include: (I) production of fuel, chemicals, animal feed; (II) recycling of wastes; (III) thermal and biochemical dépollution; (IV) production of oxygen in the atmosphere and consumption of CO2. Biomethanation of Hydrodictyon algae with a second generation system, 2 phases, is characterized by 1) high volumetric loading rates (12,5 COD l−1 d−1) 2) mean solids retention time of 5 days 3) total methane yield (0,195 1 CH4.g−1 COD introduced) higher than with classical system (0,175 1 CH4 g−1 COD) 4) reliable and stable digestion. The integrated, cyclic system will be further developed in a pilot of industrial size, aimed at optimizing the various variables involved and at demonstrating the integrated functioning of the whole.

1. PURPOSE OF THE WORK The goal of our research was the setting-up of a cyclic integrated system which produces: 1.- fuel; 2.- high-value chemicals; 3.- feed for domestic animals and 4.- fertilizers, from macroalgae grown in luke-warm water of industrial origin. 2. RESULTS A. Part I—Algae cultures Since 1978 the alga Hydrodictyon reticulatum has been grown in shallow lagunes irrigated by the polluted luke-warm water (20° to 30°C) coming out the cooling circuit of the nuclear power-plant at Tihange (Belgium). The culture has been extended

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progressively from 400m2 up to 2200m2; it will reach 1ha in 1985. The biological composition of the biomass has been continuously controlled. The algal biomass has been bioconverted into biogaz (fuel) in a two phase biomethanation process. Highvalue chemicals have also been extracted from the biomass. The by-products have been used as feed for animal breeding. The residues from animals and from biomethanation have been recycled into a pilot plant for intensive algae culture (18.000 liters). The heat contained in the luke-warm water was found to be able to increase the yield of the collected dry Hydrodictyon reticulatun biomass from 6–7 tons/ha year (non heated lagunes) up to 10 to 12 tons/ha year. The algae were fed with the mineral and organic components (including pollutants) of the River Meuse. The biological composition of the harvests has been well reproducible from 1979 to 1984 (fig.1); it was shown that Hydrodictyon was the dominant species, while Lemna and gastropods fluctuated between 2 to 36% TS in 1983. The chemical composition of the biomass has shown a high content in minerals. These include mainly Ca carbonate (due to the calcareous zone through which River Meuse is flowing upstream), and salts of K, P, Mg, S, I, Na, Cu, Zn, Hg, Pb (Cd not detectable). The protein fluctuates between 16 to 25%; its lysine content (ca 6%) is suitable for the feeding of domestic animals.

June July August June July August Sept July August Sept Several natural dyes were extracted from the biomass (yield around 0,5%) as well as other biochemicals suitable for cosmetics and pharmacy (yield 3 to 5%). The by-products from the extraction were used to feed

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fishes and laying hens. The residues from animal breeding (manure) and from biomethanation of the algal biomass have been used as nutrients instead of mineral fertilizer in an intensive culture of microscopic algae (Scenedesmus) and in a 132m2 pilot plant. Fig. 2 shows the growth of Scenedesmus on mineral fertiliser (curve 1) and on the hen’s dung (curve 2). The growth is very similar on both nutrient media. On the other hand, the meat of the fishes (Tilapias, chinese carps…) and of the hens is considered as excellent by customers. The eggs are of the best quality (the brown color of the shell is very attractive, the shell is very smooth and thick, the yolk is intense yellow, the white is very viscous).

Fig. 3. the integrated system may be represented as follows :

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Part II—Biomethanation of Hydrodictyon algae in a second generation digestion system. A second generation digestion system has been set up at laboratory scale as a two-phase system on the basis of previous results. An active biomass accumulation has been developped in the second phase of the digestion system by using an upflow anaerobic digester. The second main goal was to optimise the liquefaction and acidogenesis phase. For this, it was necessary to design a fermenter allowing good individual control of parameters. A.1. Design of the second generation digestion system. This system is composed of a percolation phase in which dissociation of hydraulic and solid mean retention times is possible. A continuous dilution of the liquid phase can be operated due to the sedimentation and flottation of the solid fraction and the possible preferential extraction of the liquid fraction. This liquid fraction contains the excess of the fermentation products of the liquefaction and acidogenesis phase and is brought to the methane producing active biomass of the second fermenter (the up-flow digester) by over-flow. The over-flow of the latter up-flow digester can be recycled as liquid of dilution for the first fermenter. This over-flow contains the excess active biomass which can be collected in a small decanter before the recycling of the liquid. The percolator is loaded with solid substrate on a semi-continuous basis. The liquid effluent of the system is withdrawn from the effluent of the up-flow digester. Two identical second generation digestion system were built and run in parallel at 20°C and 35°C. The evaluation of the biomethanation potentiality of the solid effluent of the percolator was done in a batch digester by filtration of the mixed liquor effluent of the percolator on a Wattman filter (rapid). Filtration cake is resuspended in water and introduced in a batch digester. A classical two phase biomethaoation system was run with a low volumetric loading rate (BV: ±1g COD.l−1.d−1) and long mean retention time (θ=56d) in order to give a reference for the yield of biomethanation.

Table I : Global results obtained with the second generation digestion system Second generation system N° Exp.

BV

θs (d)

rV.CH4

Total (1)+(2)

Reference

YCH4/CODo(1)

(1)* 1.83 7.0 0.160 0.090 (2)** 3.79 7.0 0.490 0.129 (3)** 6.15 7.0 0.700 0.114 (4)* 1.83 7.0 0.210 0.115 (5)** 1.83 4.2 0.090 0.049 (6)** 3.79 7.0 0.690 0.182 (7)** 6.15 7.0 1.140 0.185 (8)** 12.50 5.0 2.440 0.195 * use of water as liquid of dilution for the percolater ** recirculation of the effluent of the up-flow digester,

YCH4/CODo 0.165 0.190 0.174 0.165 0.148 0.190 0.174 0.174

(2) YCH4/CODo 0.041 0.081 0.023 0.047 0.076 0.063 0.030 0.015

YCH4/CODo 0.131 0.210 0.137 0.162 0.125 0.245 0.224 0.210

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EXP (1)→(3): 20°C; EXP (4)→(8): 35°C Symbols abbreviations and units: see Table II.

Table II: Abbreviations, symbols and units – Concentrations (kg/m3)

– Indices

– Yields

COD: chemical oxygen demand

o: in inlet (in feed)

– Rates BV: volumetric loading rate

– Various ML: Mixed Liquor (useful volume

YCH4/CODo: methane yield (lCH4×g−1) TS: total solids

rv.CH4: methane production rate – θ: mean retention time (d), θs: mean solid retention time (d)

A.2. Liquefaction and acidogenesis of Hydrodictyon algae The yield of liquefaction increases respectively with the temperature while absolute yield of acidogenesis is decreasing. The initial rates of liquefaction and acidogenesis increase with the pH. Maximum rate of liquefaction appears at pH=7 (10.78g COD.]−1.d−1) and maximum rate of acidogenesis at pH=6.5 (10.77g COD. l−1.d−1). The maximum yields of “liquefaction and acidogenesis are observed at pH=7.0 and are after 12 days of batch fermentation, 69% (liquefaction) and 57% (acidogenesis). Relative yield of acidogenesis is also maximum at pH=7 (83%). At all pH values, acetate is the major product of fermentation and represents 58% and 56% of the total products respectively at pH=4.5 and 7.0. It only represents 33% of the former products at pH=5.5. In semi-continuous experiments at 35°C, a volumetric loading rate of 16g COD. l−1 −1 .d and a solid retention time of 5d can be maintained in a percolator with a mean hydraulic retention time of 1.04d and a pH of the mixed liquor of 7.2. The yield of liquefaction (g CODsol.g−1COD) increases also with the volumetric loading rate. A.3. Biomethanation of Hydrodictyon algae in a second generation digestion system. From Table I, it is shown that higher methane yields (YCHA/CODO) can be obtained in the up-flow digester with higher yield of acidogenesis in the percolating step. This yield of acidogenesis is thus the limiting step in the up-flow digester. The evaluation of the biomethanation potentiality of the solid effluent of the percolator shows that the methane yield (YCH4/CODO) decreases with the increase of efficiency of the second generation digestion system. The global results of the second generation digestion system compared with the reference are presented in Table I. These results show that this second generation digestion system can be run in a reliable way with a volumetric load of 12.50g CODo.l−1.d−1 and a mean solids retention time of 5d. In those conditions, the methane yield obtained (YCH4/CODO=0.195 l CH4.g−1 CODo) is greater than the yield obtained with the reference bio methanation system (YCH4/CODO=0.174 l CH4.g−1CODO). The biomethanation is also more stable.

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REFERENCES (1) LEGROS, A., ASINARI DI SAN MARZANO, C.M., NAVEAU, H. and NYNS, E.J. (1982). Fermentation profiles in bioconversions. Biotechnology Letters, 5(1), 7–12. (2) DUJARDIN, E. , COLLARD, F., LEGROS, A., ASINARI DI SAN MARZANO, C.M., NYNS, E.J., NAVEAU, H. and SIRONVAL, C. (1983). Methane production by anaerobic digestion of algae. II. Production of algae. In “Energy from Biomass”. Series E. vol. 5. Palz, W. and Pirrwitz, D. eds, Reidel D Publishing Company. Dordrecht; Holland, 218–225.

PROPERTIES OF ALGAL BIOMASS PRODUCTION AND THE PARAMETERS DETERMINING ITS FERMENTATIVE DEGRADATION K.KREUZBERG, G.REZNICZEK and G.KLÖCK Institute of Botany, University of Bonn, D–5300 Bonn 1, FRG Summary The properties of starch production and its fermentative degradation were investigated during growth of the unicellular green algae Chlorogonium elongatum and Chlamydomonas reinhardii. Biomass and cellular starch were effectively produced during photoheterotrophical and heterotrophical growth at 28ºC with 2mM phosphate and 5mM ammonium. The rate of starch fermentation depended on the plastidic starch content. The results gave evidence for the determination of the algal fermentation rate by parameters affecting plastidic starch activation e.g. the phosphate concentration within the chloroplast.

1. INTRODUCTION The microalgae Chlorogonium elongatum and Chlamydomonas reinhardii effectively produce high value biomass during autotrophical, photoheterotrophical and heterotrophical growth. This biomass can be degraded by subsequent fermentation to energy-rich products e.g. acetate, ethanol, formate, glycerol, lactate, 2,3-butanediol and hydrogen (1). Recent investigations confined cellular starch as sole substrate for algal fermentation (2). However, this starch is known to be completely localized within the chloroplast of both algae. The all-over efficiency for the conversion of the biomass produced to energy-rich products is firstly dependent on the amount of starch synthesized and secondly on the parameters determining the rate of starch degradation within the whole cell or the algal chloroplast. The aim of this study is to elucidate the influence of different growth parameters on the production of starch during continuous cultivation of Chlorogonium elongatum. Further analysis of starch degradation in whole cells and isolated chloroplasts from Chlamydomonas reinhardii will give evidence for the parameters determining the rate of starch degradation and thus the rate of algal fermentation.

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2. EXPERIMENTAL Algal strain and cultivation. Chlorogonium elongatum, L 12–E, and Chlamydomonas reinhardii, 11–32b, were obtained from the Sammlung für Algenkulturen, Göttingen, FRG. Chlorogonium elongatum was continuously (4) and Chlamydomonas reinhardii synchronuously (2) cultivated under axenic conditions. Cellular prameters. The determination of biomass (D.W.) and of the cellular content of starch, protein, lipids and of chlorophyll followed the methods given in reference (5). Fermentation. The incubation procedure for the fermentative degradation of cellular starch resembled that described elsewhere (2,3). Potassium phosphate (50mM, pH 6.8) was replaced by 50mM Hepes (pH 6.8) in cases, where the influence of phosphate on the fermentation was investi- gated. Chloroplast preparation. Intact chloroplasts were isolated from protoplasts of Chlamydomonas reinhardii as described earlier (3). Cross contamination with mitochondria or cytoplasm was judged from the activities of phosphoenolpyruvate carboxylase (cytoplasm) and cytochrom c oxidase (mitochondria), respectively. The intactness of chloroplasts was proofed by the ferricyanid dependent Hill reaction and inspection by electron microscopy. The isolated chloroplasts photosynthetically fixed CO2 with a rate of 46.8±7.0 umol CO2 mg Chl−1 h−1 . The content of dihydroxyacetone phosphate and 3-phosphoglyceric acid was estimated as given in (6). 3. PARAMETERS INFLUENCING STARCH PRODUGTION Growth rate. Biomass production increased during light limited photo-heterotrophical growth from 0.227g l−1 d−1 at an irradiance of 0.371wm−2 up to its maximum of 3.179gl−1 d−1 at 5.76w m−2, , respectively. The composition of cellular dry matter did not change with increasing irradiance and remained constant with 57.3% protein, 14.9% starch and 5.0% lipids. During oxygen limited heterotrophical growth the daily biomass output increased from 0.78gl−1 d−1 at a flow rate of 0.1lh−1 to 1.89gl d−1 at a flow rate of 18.0lh−1 . In contrast to light limited growth the content of cellular protein decreased from 60% to 52% and that of starch increased from 10.4% to 25%, respectively, whereas lipids remained constant at 3.5% of dry matter. The data for maximum production rate are compiled in Table I, which shows the production of important amounts of starch even under heterotrophical dark conditions.

Table I MAXIMUM PRACTICAL BIOMASS PRODUCTION BY CHLOROGONIUM ELONGATUM DURING CONTINUOUS HETEROTROPHIC (DARK) AND PHOTOHETEROTROPHIC (LIGHT) CULTIVATION.

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During heterotrophic conditions maximum biomass production yielded with an aeration rate of 18.0lh−1 at a specific growth rate of 0.22h−1. . During photoheterotrophical cultivation maximum biomass production was obtained with an irradiance of 5.76ww−2 at specific growth rate of 0.22h−1 Fraction Biomass (D.W.) Protein Starch Lipids

Maximum Production Rate heterotrophic photoheterotrophic (mgl−1d−1) (mgl−1d−1) 1870.0±28.4 1037.6±24.9 387.5±7.4 66.2±3.5

3179.0±47.6 1818.4±27.3 473.6±9.1 159.0±0.9

Temperature. The temperature of algal cultivation influenced the cellular starch content during photoheterotrophical growth of Chlorogonium elongatum (Fig. 1A). Therefore optimum biomass production, which was found at 40ºC, did not coincidenced with the maximum of starch production at 28ºC. with temperatures higher than 41°C algal cells lost their chlorophyll and no growth further persisted. Phosphate and ammonium. Optimum biomass and starch production rates resulted with phosphate concentrations as low as 2mM. Further increase in phosphate up to 30mM only caused minor changes in yield and in the cellular composition of dry matter.

Fig. 1. The influence of temperature (A) and ammonium (B) on the

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production rate of biomass (●) and of cellular protein (o), starch (▲) and lipids (∆) during photoheterotrophical growth of Chlorogonium elongatum. In contrast , with varying ammonium concentrations from 0.2mM to 50mM a more pronounced effect in biomass, protein and lipids were observed (Fig. 1B). Nevertheless, starch output was hardly stimulated by increasing ammonium concentrations (0.2mM to 8mM) and significantly droped with ammonium higher than 10mM. 4. STARCH DEGRADATION Cellular starch content. The fermentative starch degradation depended on the cellular starch content in cells of Chlamydomonas reinhardii (Fig. 2A) yielding in a typical saturation kinetics. From the double reciprocal plots (Fig.2A, insert) an apparent Km of 0.38µmol glucose unit mg Chl−1 resulted. The maximum theoretical rate of starch degradation was determined to 1.8µmol glucose units mg Chl−1 h−1 in whole cells. Starch content of the chloroplast. The isolation of chloroplasts with a high starch content appeared extremely difficult due to the fragility of this large organell. Therefore the starch content per mg chlorophyll was lower in the intact, isolated chloroplasts than in whole cells (Fig. 2B). Nevertheless, even under these conditions the rate of starch degradation depended on the actual plastidic starch content and showed saturation kinetics. The corresponding kinetic data for plastidic starch degradation were Km=3.8µmol glucose units mg Chl−1 and Vmax=1.4µmol glucose units mg Chl−1 Phosphate. The fermentative starch degradation was not affected by varying extracellular phosphate concentrations from 0.2mM to 20mM in whole cells of Chlamydomonas reinhardii (Fig.3,▲). In contrast, starch catabolism of isolated chloroplasts clearly depended on the addition of of phosphate. Saturation pattern resulted with increasing phosphate from 0.2mM to 5mM (Fig.3, ●). Nevertheless, the observed Km of 0.42mM pointed to the necessity of only low phosphate concentrations to yield optimum rates in starch degradation.

Properties of algal biomass production and the parameters determining its fermentative degradation

Fig. 3.The dependency of starch degradation on phosphate in (▲) whole cells and (●) isolated chloroplasts from Chlamydomonas reinhardii.

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Fig.2.The dependency of starch degradation on the starch content in (A) whole cells and (B) isolated chloroplasts from Chlamydomonas reinhardii. Products of anaerobic starch degradation. In whole cells anaerobically degraded starch carbon could be balanced by 96% in the analyzed products formate, acetate, ethanol and CO2 (Table II). Main products of the anaerobic starch degradation in isolated chloroplasts were dihydroxyacetonephosphate and 3-phosphoglyceric acid, which both accounted for 74% of the catabolized starch carbon (Table II). In contrast to the results with whole cells no fermentation products could be detected during anaerobical starch mobilization in the chloroplast. 5. CONCLUSIONS Optimum conditions for the production of cellular starch differs from that for maximum biomass production in unicellular green algae. Nevertheless, the high yields in starch synthesis during heterotrophic and photoheterotrophical cultivation offers the advantage

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for a low cost production of fermentable biomass on waste water in the dark and in the light. The rate of algal fermentation is determined by the rate of cellular starch degradation. The failure of a fermentative starch metabolism in isolated chloroplasts rules out an regulatory function of the fermen-

Table II ANAEROBIC STARCH DEGRADATION IN WHOLE CELLS AND ISOLATED CHLOROPLASTS FROM CHLAMYDOMONAS REINHARDII. Cells were incubated in 50mM potassium phosphate (pH 6.8) and chloroplasts in 50mM Hepes (pH 6.8), containing 120 mM mannitol, 5 mM Pi., 1 mM MnCl2, 1mM MgCl2, 2mM EDTA. Aliquots (200µg Chl) were gased with argon for TO min and incubated for 1h at 25ºC. Starch is given in glucose units. Products

Cells Chloroplasts (µmol mg Chl−1) C1 (µmol mg Chl−1) C1

Starch Formate Acetate Ethanol CO2 H2 Dihydroxyacetone phosphate 3-Phosphoglyceric acid sum

1.30 7.80 2.34 2.34 1.31 2.62 1.20 2.40 0.09 0.09 0.10 ----7.45 0.96 0.76

0.68 4.08 0.00 0.00 0.00 0.00 0.00 0.00 0.05 0.05 0.10 0.48 1.44 0.53 1.59 3.08

tation pathway itself and points to a rate limiting step involved during plastidic starch activation. 6. REFERENCES (1) KLEIN, U., KREUZBERG, K. and BETZ, A. (1981). Chemicals produced by unicellular green algae in anaerobiosis. Adv. Biotechnol., Vol II , pp. 97–100. (2) KREUZBERG, K. (1984) Starch fermentation via formate producing pathway in Chlamydomonas reinhardii, Chlorogonium elongatum and Chlorella fusca. Physiol. Plant. 61, 87–94.

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(3) KREUZBERG, K. (1984) Evidences for the role of chloroplast in algal fermentation. Adv. Photosyn. Res. Vol III, pp. 437–440. (4) KREUZBERG, K. and HEMPFLING, W.P. (1981) . Properties of the green alga Chlorogonium elongatum during light limited continuous culture in the Phauxostat. Adv. Biotechnol., Vol I, pp. 287–293. (5) REZNICZEK, G. and KREUZBERG, K. (1984). Carbon and energy balance during continuous algal growth. Adv. Photosyn. Res., Vol III, pp. 395–398. (6) WIRTZ, W., STITT; M. and HELDT, H.W. (1980). Encymic determination of metabolites in the subcellular compartments of spinacea protoplasts. Plant Physiol. 66, 187–193.

POTENTIALITES DE PRODUCTION DE BIOMASSE AQUATIQUE DANS LES LAGUNES D’EPURATION M.VUILLOT, J.BARBE et Coll.CEMAGREF Division Qualité des Eaux, Pêche et Pisciculture 3, Quai Chauveau—69009—LYON Résumé Les lagunes d’épuration sont le siège d’une importante production vivante, sous-produit de la transformation de la charge polluante traitée. Un programme d’étude sur sites réels, visant a préciser les conditions de production de cette biomasse a été engagé. Ont été suivies simultanément les performances d’épuration des installations, l’évolu-tion qualitative et quantitative du phytoplancton et les cinétiques de croissance des macrophytes flottants. Ont été mises en évidence la valeur en moyenne élevée et les variations importantes dans le temps de la biomasse algale présente. La production de Lemnacées et l’exportation possible de nutrients par récolte des végétaux ont été quantifiées. Des régles de gestion compatibles avec le maintien des performances d’épuration ont été proposées. Sont présentés ici les résultats relatifs à un des lagunages qui ont été étudiés.

1. PRESENTATION Le lagunage naturel est un procédé de traitement des eaux résiduaires. Les installations sont constituées d’une série de bassins peu profonds (lagunes) dans lesquels s’opére une degradation bactérienne, essentiellement aérobie, des mtières organiques. L’oxygène nécessaire a cette dégradation provient de l’activité photosynthétique des organismes chlorophylliens qui se développent dans les bassins. Ceux-ci assimilent également une part des élements minéraux dissous. Un dépot organique se forme progressivement dans le fond des bassins, par sédimentation des mtières en suspension contenues dans les eaux usées et des biomasses mortes. Il concentre la plus grande partie du flux de matière entrant dans l’installation. Le reste se retrouve, largement transformé, dans la pleine-eau et dans l’effluent, sous forme dissoute ou particulaire (déchets, bactéries, algues, zooplancton). Ces produits de transformation des charges polluantes, plus diversifies que dans les stations d’épura-tion classiques, représentent un potentiel dont les conditions de valorisation méritaient d’être étudiées, en liaison avec l’augmentation rapide, en France, du nombre des installations de lagunage naturel en service.

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Un programme particulier d’étude des conditions de production des biomasses planctoniques et macrophytes a ainsi été entrepris par le CEMAGREF avec le concours incitatif de l’Agence Française pour la Maîtrise de l’Ener-gie. Est présentée ici une synthèse des résultats obtenus sur une des installations qui ont été étudiées dans le cadre ce de programme. Le suivi, conduit sur une période de 3 ans, de 1980 à 1983, s’est attaché a caracté-riser le fonctionnement du lagunage, les biomasses et la production algales, les populations zooplanctoniques et les conditions de production et de ré-colte de végétaux flottants (Lemnaceae) colonisant les bassins. 2.- CARACTERISTIQUES ET CONDITIONS DE FONCTIONNEMENT DU LAGUNAGE DE CHAU-CENNE (fig.1) L’installation de CHAUCENNE (département du Doubs) est conçue pour traiter les eaux usées domestiques d’un village de 500 habitants. Elle a été mise en service en avril 1980. Ses principales caractéristiques de conception et de dimensionnement sont présentées à la figure 1 ci-après. Les eaux acheminées par le réseau d’assainissement sont pompées dans un poste de relèvement, et admises sans traitement préalable en tête de la première lagune. Peu après la mise en service, les bassins se sont trouvés colonisés par plusieurs espèces de lentilles d’eau. Les conditions de fonctionnement ont été appréciées principalement sur la base de cinq campagnes de mesure, d’une durée de 24 à 48 heures, entre mai 80 et juillet 83, permettant la collecte et l’analyse d’échantillons moyens et l’enregistrement de paramètres caractéristiques (débits, oxygène dissous et température dans les bassins). L’installation reçoit une charge polluante à peu près constante et égale en moyenne à 13kg DCO/jour (5kg DBO/jour) , soit environ 20% de sa charge nominale. Toutefois, les debits a l’entrèe presentent de grandes fluctuations, en raison du caractère pseudoséparatif et drainant du réseau d’assainissement: Pour une charge hydraulique nominale de 75m3/jour, les valeurs mesurées varient de 45m3/jour en période sèche (juin 1981) a plus de 370m3/jour (janvier 1982). En période très pluvieuse, les pompes de relèvement ne peuvent suffir a évacuer l’en-semble des debits, et les lagunes peuvent être by-passées. A partir des enregistrements pluie/débit réalisés, la charge hydraulique moyenne sur une année peut être estimée à environ 120% de la charge nominale. Les performances d’épuration et la qualité de l’effluent rejeté dans le milieu naturel sont forteraent influencée par le développement des lentilles d’eau : les lagunes présentent un fonctionnement satisfaisant lorsque ces végétaux sont absents (mai 80, août 80, janvier 82), ou lorsqu’ils sont récoltés avant l’apparition d’un pallier de production. Dans ces conditions, les abattements moyens sont sur les flux entrants, de 65% pour la DCO et les MES, 90% sur l’azote kheldahl et 75% sur le phosphore total. En revanche, lorsque les lentilles d’eau ne sont pas récoltées à temps, la présence d’un couvert vegetal dense finit par obérer le fonctionnement des lagunes : les analyses traduisent une oxydation très faible des composés organiques et un pH inférieur a la normale. Le traitement est également perturbé par les relargages d’éléments réduits consécutifs aux variations du potentiel d’oxydo-réduction au niveau du sediment. Le résultat global est un rejet dont les caractéristiques chimiques sont proches de celles de l’effluent à l’entrée.

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3. BIOMASSE ET PRODUCTION ALGALES DANS LES LAGUNES (fig.2) Les populations algales ont été observées a un rythme hebdomadaire : identification et cotation en abondance relative des espèces présentes, dosage des pigments chlorophylliens (méthode SCOR UNESCO), et évaluation de la production primaire (méthode STEEMAN NIELSEN). 22 taxons se développent avec abondance dans Ll (26 dans L3) . Ils appartiennent essentiellement aux chlorophycées (Ll: 54%; L3:38%) et aux Euglé-nophycees (Ll: 41%; L3:30%) . Les diatomophycées sont présentes dans L3 (19%). Les cyanophycées sont peu représentées. Ces taxons se regroupent en 4 peuplements principaux sur Ll (5 sur L3) qui se succèdent dans le temps. L’optimum de développement d’un peuplement correspond à un maximum de biomasse présente dans les bassins (jusqu’à 2285mg chl a.m−3 sur Ll et 3200mg.m3 sur L3; Il s’agit dans les deux cas d’un peuplement dominé par Chlamydomonas sp.) Le passage d’un peuplement à un autre se traduit par une baisse importante des concentrations. La succession des peuplements est liée principalement aux variations des paramètres abiotiques (dilution plus ou moins importante de la charge entrante) et dans un second temps aux conditions météorologiques. Ces facteurs, lorsqu’ils varient rapidement, modifient également la dynamique de chaque peuplement. Les lentilles d’eau, lorsqu’elles recouvrent complétement les bassins, favorisent le développement de bactéries hétérotrophes au détri-ment des algues : par exemple, celles ci disparaissent complétement dans Ll du 5 au 12 août 82 (densité des lemnacées: 6kg/m2) pour recoloniser rapidement le milieu dès la récolte. La prédation par le zooplancton provoque également d’importantes fluctuations de la biomasse présente: par exemple, en mars 82, un développe-ment de Daphnies dans Ll se traduit par une baisse de plus de 90% de la biomasse algale en une semaine (de 300 à 20mg chl.a. m−3). En moyenne annuelle, la biomasse algale présente des valeurs élevées, décroissantes du ler au 3ème bassin (de 250 à 150mg chl.a. m−3), mais elle se caractérise surtout par une forte instabilité. La production primaire maximale peut être trés importante lorsque la biomasse est élevée (jusqu’à 3700mg C.m−3.h−1). Les profils verticaux sont typiques des milieux chargés, avec un maximum en surface, et une diminution rapide en profondeur; en été l’épaisseur de la zone trophogène est inférieure à 30cm. 4. CROISSANCE ET PRODUCTION DES LENTILLES D’EAU (fig.3 et 4) Les lemnacées ont colonisé spontanément les lagunes, dès 1980 sur L3 (Lemna minor) et à partir de 81 sur Ll (peuplement dominé par L.gibba). L’évolution des macrophytes a été étudiée en 81, 82 et 83 par échantillon-nage hebdomadaire, et pesée de la totalité des végétaux lors des récoltes. En 81, les lentilles d’eau sont récoltées chaque fois qu’elles recouvrent la totalité de la surface des lagunes (3 récoltes sur Ll; 4 sur L3); en 82 la

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récolte est réalisée lorsqu’est atteint un pallier de production, avant la sédimentation des plantes (1 récolte sur chaque lagune); en 83, l’évo-lution est suivie sans interventions. La période de végétation s’étend de mai à octobre. En début de saison, la croissance est exponentielle. En absence de récolte, elle atteint un pallier après environ 60 jours. Les végétaux commencent alors à se né-croser, puis a sédimenter et les courbes de croissance présentent un aspect irrégulier. En 82, la biomasse maximale mesurée a ce stade est de 6kg/m2 sur Ll et 3,5 kg/m2 sur L3 (en poids frais). Elle dépasse 7kg/m2 sur L3 en 83, en liaison avec des conditions climatiques estivales exceptionnelles (au mois de juillet : température moyenne de l’air: 24°C; précipitations: 26mm , les valeurs moyennes sur 35 ans étant 18,7°C et 79mm). En 1981, la réalisation régulière d’opérations de récolte permet de maintenir une croissance exponentielle durant tout l’été. A l’automne, les conditions climatiques (vent et précipitations) deviennent limitantes et perturbent fortement le développement des végétaux. Le tableau de la page ci-après résume les données relatives à la production récoltable. L’évolution des teneurs des végétaux en composés azotés et phosphorés a été suivie en 1983. L’azote se trouve sous forme organique (85%) ou ammoniacale (15%). Les concentrations maximales ont été mesurées sur lespeuplements jeunes (âge compris entre 10 et 40 jours). L’azote “kjeldahl” représente alors 7% du poids sec. Cette teneur décroit ensuite avec l’âge des peuplements et l’état physiologique des végétaux, jusqu’à des valeurs de l’ordre de 4% du poids sec. Le phosphore est égale-ment présent sous forme organique (36%) et minérale (64%). Les teneurs apparaissent relativement stables: le phosphore total représente 1,4% du poids sec et les ions orthophosphate 0,9%. Biomasse récoltée en t.de poidsfrais Rdt en pc oids frais t/ha Rdt en poids sec t/ha 81 82

Ll 19,9 17,5

L3 5,5 8,2

Ll 80 70

L3 41 60

Ll 4 3,5

L3 2,1 3

Selon les teneurs en N et P et les courbes de croissance peut être déter-minée la date de la récolte qui permet l’exportation maximale de nutrients. Sur la lagune L3, en 1983, celleci se situe après 60 jours de croissance. La biomasse en place représente alors 2,3t. de matière séche/ha, et sa ré-colte permet l’exportation de 125kg Nk/ha et 30kg P total/ha (voir fig.4). 5.- CONCLUSION. Compte tenu des fluctuations importantes et des difficultés de récol-te de la biomasse algale, les macrophytes apparaissent comme la principale biomasse exploitable. Dans le cas des lentilles d’eau colonisant spontané-ment les lagunes, la récolte périodique des végétaux est à la fois compa-tible avec l’épuration, et nécessaire au maintien des performances de l’installation. Elle permet de plus une exportation significative de nutrients et évite un vieillissement accéléré des lagunes par sédimentation des plantes à l’automne. Ainsi les opérations de récolte peuvent pour une part s’intégrer aux tâches normales de maintenance. Une valorisation des produits permettrait d’en réduire le cout global. Le caractére dispersé de ce type de production et la faible taille moyenne’des

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lagunes d’épuration ne semble toutefois permettre actuellement que des valorisations locales, selon des circuits courts à faible valeur ajoutée. PRINCIPALES REFERENCES BIBLIOGRAPHIQUES BARBE J. (1981)—Les peuplements planctoniques des installations de lagunage en France. C.R. Congr. Int. Phytoépuration. Parme (Italie), 15–16 mai 1981. p.321–329. BOUTIN C. (1983)—Les Macrophytes : leur rô1e dans l’épuration des eaux usées; étude sur site réel de 1’ exportation d’éléments nutritifs par les lentilles d’eau. Mémoire ENSP-CEMAGREF, Sept.83, 105p. CEMAGREF (1984)—Biomasse dans les lagunes d’vpuration. Rapport AFME, mai 84, 45p. STEINER B (1984)—Sur 1’ utilisation du phytoplancton pour la caractérisa tion des installations de lagunage naturel. Thèse doc.3ème cycle. Bio. Végt. juillet 84. 225p. VUILLOT M (1982)—Biomasse végétale récoltable dans les lagunes d’épura-tion de Chaucenne (Doubs). Actes du séminaire des contractants AFME, Sophia Antipolis—27 mai 1982.

Fig.1 : Lagunes de CHAUCENNE. Vue en plan et coupes

Fig.2 : Evolution des teneurs en chl.a et des peuplements dans Ll

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Fig.3 : Courbes de croissance des lentilles d’eau.

Fig 4 : Bilancharge pour L3 sur 60j. de croissance des lentilles (en kg de N ou P)

PRODUCTION OF ALGAL BIOMASS IN VENICE LAGOON, ENVIRONMENTAL AND ENERGETIC ASPECTS GUIDO MISSONI AGIP S.p.A.—ROME (ITALY) MARIO MAZZAGARDI C.S.A.R.E.—VENICE (ITALY) INTRODUCTION AGIP and C.S.A.R.E. have carried out a study, which has followed an empirical approach in the attempt of defining conditions and parameters useful to the assessment of: a) partial harvesting of macroalgae in order to control the amount of biomass present in the lagoon; b) transforming, via anaerobic digestion, algal biomass into valuable products (biogas and materials for agriculture) and at the same time removing nitrogen and phosphorus from the lagoon. A– MACROALGAE PRODUCTION UNDER PERIODICAL YEARLY HARVEST The algal growth follows a typical seasonal cycle. Only occasionally the concentration of algae reaches 40÷50Kg/m2 . Macroalgae species are Ulva Rigida, Gracilaria Confervoides, Chaetomorf a Aerea and Valonia Aegrophila. As climatic conditions improve, vegetation expands, different soecies succeed to one arother. Ulva Rigida is the one that finally obtains the largest diffusion and density (5÷ 15Kg/m2). The regrowthing time of macroalgae after harvest has been investigated in a small fenced aerea: the biomass doubling time is 3÷5 days when optimal environmental parameters f have been adopted. Sampling of macroalgae density throgh the lagoon has indicated the areas where amounts of industrial relevance could be harvested and where such a harvesting could be beneficial to the environment. The areas are listed in the following table:

MACROALGAE IN LAGOON NAME OF THE PLACE

1. PALUDE MAGGIORE– VALLE DI CA’ ZANE

AREA DRIPPED (Km2) Amounts (T)

ALGAE Density (Kg/m2) MAX MIN MAX MIN

27.0 160.000 34.000

5.9

1.3

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2. PALUDE DELLA ROSA– PALUDE DI CONA 3. VENICE—CANALE S. SE CONDO BURANO— TORCELLO 4. VENICE—CANALE PETROLI 5. CANALE NUOVO—PEROGNOLA LIO VALGRANDE—ISOLA DI PELLESTRINA

416

9.0 75.000 15.000 38.5 440.000 14.000

8.3 11.4

1.7 0.4

27.0 450.000 13.500 32.5 250.000 2.500

16.7 7.7

0.5 0.08

B– MACROALGAE HARVESTING Harvesting must not be harmful to the ecosystem; specifically, it must not impair the possibility of repeated harvest, year after year. The harvesting must be carried out so that the cost of algal biomass be minimal: it must be compatible with algae regrowing. In the program two problems have been considered: design of a harvesting boats and harvesting procedure. A special type of boat has been designed. With such a fleet of boats and barges it could be possible to harvest in 59 days the area in the central basin where available algal density is at least 5Kg/m2. This area has an extension of about 35Km2. C– PRETREATMENT OF ALGAL BIOMASS It is useful to pretreat the algal biomass before feeding it to a digester. In fact while the cell liquids are easily digested, the cell walls rich in cellulose and lignine resist digestion and present a good yield of the process if not properly fragmented. Different treatments have been tested: a) grinding, pressing and fractional wet pressing, in order to separate a liquid fraction containing most of the digestable matter from a residue consisting of cellulose material (cell walls); b) homogenization of the algal biomass in order to produce a fluid in which the cells are broken and cell walls reduced to small fragments. Only the last one gave satisfactory results. After honogenization of algal biomass it is convenient to check the possibility of separating it in to a “liquid fraction” to be digested with fix bed digestors and a “solid fraction” to be fed to continuous stirred reactors or to be gasified. To achieve this separation the homogenized algal biomass is centrifuged. Analysis of harvested and dripped algae, of homogenized fluids and of liquid and solid fractions gives the following informations: –a) To homogenize the algae in equal amount of water must be added. –b) The solid fraction, by weight, accounts for abount 20% of the homo genized biomass. –c) The original content of total and volatile solids of the algal biomass is shared at about 50% between the two fractions. –d) The ratio BOD5/COD, taken as an indicator of biodegradable organic matter, increases in the liquid fraction and decreases in the solid one. –c) Dry matter in the solid fraction is made of: 38% ashes and 62% volatiles. The volatile composition is: fats 21%, lignine 27%, cellulose fiber 52%. Dry matter in the algal biomass, only washed after harvest, contains: ashes 24% and 76% volatile solids, whose composition is carbohydrates+fats=35%, lignine=11.5%, cellulose fibers 61%. These figures indicate that to a great extent homogenization breaks the algal cells leaving fibrous structures and cell inner fluids separated and that the ensuing

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centrifugation actually enriches the solid fraction with cellulose and lignine fragments, leaving a liquid fraction which contains only about 50% of original volatile matter but probably the most digestible one. D– ANAEROBIC DIGESTION OF PRETREATED MACROALGAL BIOMASS It has been found necessary to carry out direct measurements of the relevant parameters of macroalgae anaerobic digestion in order to check: –a) Actual possibility of digesting pretreated macroalgae or fraction thereof with fix bed as well as stirred reactors. –b) Definition of process parameters at pilot plant scale. After several runs at laboratory scale, a 5m3 stirred reactor and a 30 1 fix bed reactor have been used with the following results: –a) homogenization plus centrifugation actually transfer 50% of the easily digestable organic matter from algal biomass to the liquid fraction. –b) The liquid fraction is more easily digestable. –c) The stirred reaction pilot plant has been run with a load of 5.25Kg total solid/m reactor/d, HRT=12 days, temp.=35°C, yield = =0.27Nm3/Kg TS or 0.36Nm3/Kg volatile solids. –d) The fix bed reactor has performed quite well digesting the liquid fraction. HRT=0.88, load up to 36.7Kg TS/d or 15.2 Kg VS/d with 30,000mg/l of COD have been tested. –e) Deprimental effects od inhibitors (Cl, SO42and 2S) have been kept to such a minimum as not to impair good yields. All these results show that anaerobic digestion of pretreated macroalgae is feasible although further data are needed for the industrial plant. A great problem of such a plant is the disposal of wastes. E– OUTLINE OF THE INDUSTRIAL PROCESS Two possible solutions have been devised. First solution: after harvest and homogenization the algal biomass is fed to stirred reactors, the effluents of which are centrifuged. The solid fraction is dried and used as amendant. The liquid fraction is sent to the Mestre (Venice) plant for treatment of urban and industrial wastes. Second solution: the homogenized biomass is first centrifuged and the liquid fraction fed to a fix bed reactor while the solid fraction is once again dried and used as amendant. The liquid effluent from the digester is sent to the Mestre treatment plant. A very preliminary economic assessment indicates that, althongh biogas and amendants are valuable resources, they cannot cover the cost of the whole operation, which must there fore be considered also as an environmental control and thus financially supported accordingly.

HYDROGEN PRODUCTION, AMMONIA PRODUCTION AND NITROGEN FIXATION BY FREE AND IMMOBILISED CYANOBACTERIA M.BROUERS and D.O.HALL Department of Plant Sciences, King’s College, London SE24 9JF, U.K. Summary A comparative study was made of hydrogen and ammonia production by free and immobilised Anabaena azollae. Polyvinyl foams and alginate matrices were tested. Immobilisation of cyanobacteria led to an increase and/or to a stabilization of the rate of H2 photoproduction under argon as compared with free living cells; this increase occurred mainly via hydrogenase-mediated production. Immobilisation also stabilized the acetylene reduction activity (nitrogenase activity, equivalent to nitrogen fixation) under continuous working conditions; an increase in the initial rate of acetylene reduction was observed which was best seen when immobilising the Mastigocladus laminosus in polyvinyl foam. High yields of ammonia production were obtained from polyvinyl-immobilised A.azollae (up to ca. 400 µmoles NH3 per mg chl a during a 24h. incubation period) in the presence of an inhibitor of glutamine synthetase activity: L-methionine-DL-sulphoximine (MSO); free-living and alginateimmobilised cells produced less than 10 µmoles mg chl−1 in the same conditions. Pretreatment of alginate beads with acetone led to a net increase of ammonia production; this was observed even in the absence of MSO, suggesting an inhibition of glutamine synthetase by the acetone treatment.

1. INTRODUCTION Cyanobacteria (blue-green algae) are O2-evolving photosynthetic prokaryotes most of which show ATP-dependent nitrogenase activity and are able to fix atmospheric N2 (1). Concomitant to the fixation of N2, a nitrogenase-mediated H2 production is observed (2). Besides nitrogenase at least two other enzyme activities are involved in the metabolism of H2, a so-called uptake hydrogenase (membrane bound) that catalyses H2 consumption and a soluble hydrogenase that catalyses ATP-independent H2 formation (3,4). Hydrogen evolution from nitrogenase is inhibited by N2 and C2H2 but not by CO; in contrast hydrogenases are sensitive to CO and are unaffected by N2 (5 , 7). Although nitrogenase activity is inhibited by O2, heterocystous cyanobacteria fix N2 in aerobic conditions because the heterocyst provides O2 protection for the enzyme (it lacks

Hydrogen production, ammonia production and nitrogen fixation by free and immobilised cyanobacteria

photosynthetic O2 evolution and has an envelope which serves as an O2 barrier). Nitrogenase and uptake hydrogenase are located in the heterocyst while hydrogenase is found both in heterocyst and vegetative cells. It has been shown that immobilisation and subsequent use in bioreactors greatly facilitates the use of many biocatalysts. The main advantages are the prolonged operational stability, the cheaper isolation of the excreted product, the increase in biomass ratio, and the possibility of avoiding washout at high dilution rates. This paper reports on H2 and ammonia production by free-living and immobilised cells of heterocystous cyanobacteria A.azollae and of acetylene reduction (nitrogenase activity, equivalent to N2 fixation) by free-living and immobilised A.azollae and Mastigocladus laminosus. Immobilisation was performed either in Ca-alginate beads or in polyvinyl foam matrices. A.azollae occurs naturally as a symbiotic partner of the water fern Azolla and is known to have a heterocyst frequency of 30–60% of the total cells present,and to excrete ammonia for host metabolism when living in the symbiotic association (8). In normal physiological conditions the nitrogen fixed by the cyanobacteria is not released as ammonia but enters the nitrogen metabolic pathway. In order to induce extracellular release of ammonia the primary enzyme in ammonia assimilation, namely glutamine synthetase, is inhibited by L-methionine-DLsulphoximine (MSO) (9). To test the role of membrane permeability on the yield of ammonia production an acetone pretreatment of alginate beads containing immobilised cyanobacteria was performed. 2. MATERIAL AND METHODS Anabaena azollae and Mastigocladus laminosus were grown on BG11 medium (10) without nitrate plus micronutrient solution of Allen and Arnon (11) or on Allen and Arnon medium (11), respectively. Immobilisation in polyvinyl foam (code Jan. 84 and PR22/60, Caligen Foam Ltd, Accrington, UK) was performed according to procedure described by Muallem et al (12) by inoculating cyanobacteria into growth medium containing pieces of foam. The method for immobilisation in Ca alginate beads was described elsewhere (13); all manipulations were performed under sterile conditions. After immobilisation beads were stored in the growth medium (without phosphate) renewed each 48h. Na-alginate Protonal 10/60 was provided by Protan A.S, Drammen, Norway. Nitrogenase activity was assayed by acetylene reduction under a gas phase argon/10% C2H2; ethylene formation was measured by gas chromatography. H2 photoproduction was followed under argon or argon/4% CO. H2 was measured by gas chromatography. For determining ammonia production, polyvinyl or alginateimmobilised and free-living A azollae were incubated in the “light in the growth medium during three successive 24h. periods in the presence or absence of 50 µM MSO. The media were sampled at the end of each 24h. period for determination of ammonia concentration by the colorimetric method of Solorzano (14). The algae were then resuspended in the growth media for the next 24h. period. For acetone pretreatment, alginate beads were suspended in acetone for 1h. before the first 24h. incubation period.

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3. RESULTS 3.1 Hydrogen production Hydrogen photoevolution by A.azollae, free-living or immobilised in alginate beads and in polyvinyl foam, is shown in Fig. 1. Under argon, free-living cells showed a net H2 photoproduction up to 9h. after onset of illumination up to a total of ca. 8 µmoles H2mg chl−1. A decrease in the H2 content was then observed. When C0 (an inhibitor of hydrogenase activity was present) the total amount accumulated was 7 µmoles H2 mg chl−1, after 9h. and remained constant up to 20h. This shows that most of the H2 was produced from nitrogenase activity and that the decrease under argon was due to the development of an uptake hydrogenase activity. When A.azollae was immobilised in foam the rate of H2 evolution under argon was increased by a factor 2 as compared with

Fig.I. Hydrogen photoproduction by 8 d old free living and immobilised A.azollae in alginate beads two d. after immobilisation, and in polyvinyl foam matrix Jan.84 8d after foam inoculation. The samples were incubated beneath an initial gas atmosphere of Argon/4% CO (closed symbols) or Argon(open symbols). Light intensity: 250 µmoles photons m−2 sec−1. Temp. 25°C.

Hydrogen production, ammonia production and nitrogen fixation by free and immobilised cyanobacteria

free-living cells. Comparison with H2 production under argon /4% CO showed that ca. 50% of the H2 evolution was hydrogenase mediated (instead of ca. 20% in the free-living sample) indicating that the increased H2 yield was mainly due to increased hydrogenase activity. Alginate-immoblised cells 2d. after immobilisation produced 12 µmoles H2 mg chl−1 under argon after 19h. illumination; in this case, 85% of the H2 production was hydrogenase mediated. When assayed 40d. after immobilisation, alginate-immobilised cells were no longer able to photo produce H2. 3.2 Nitrogenase activity The initial rates of acetylene reduction (nitrogenase activity, equivalent to nitrogen fixation) and rates after 10h. continuous light under argon/10% C2H2 are shown in Table I. Free-living A.azollae cultures showed a decrease in nitrogenase activity from 8 to 40d. No activity was measurable in 40d. old cultures. Immobilisation in alginate beads led to an increase in the initial rate of C2H2 reduction. The activity was maintained at an appreciable level even after 40d. immobilisation in polyvinyl foam. Immobilisation was also shown to stabilize the nitrogenase activity; the remaining activity after 10h. continuous light incubation was greater in immobilised than in free-living cells (Table I). In recent experiments the increase of C2H2 reduction activity on immobilisation was more evident when comparing free-living and polyvinyl-immobilised M.laminosus; initial rates increased by a factor 10 in the immobilised samp1e (3.6µmoles C2H2 reduced mg chl−1 h−1) as compared with the free-living sample (0.3 µmoles mg.chl−1h−1). 3.3 Ammonia production Ammonia production by free-living and immobilised A.azollae was measured after three successive 24h. incubation periods in the light ±MSO (Table II). Low amounts of ammonia were produced by free-living and alginate-immobilised cyanobacteria without acetone pretreatment. High yields were however obtained from alginate-immobilised cells when beads were pretreated with acetone (±MSO) and from polyvinyl-immobilised cells in the presence of MSO. It must be emphasized that acetone pretreatment of alginate beads resulted in a subsequent excretion of phycobilins into the incubation medium. At the end of the three 24h. periods, the beads were light green indicating a degradation of chlorophyll pigments. Production of ammonia in Table II is expressed relative to the initial chlorophyll content. 4. DISCUSSION Free-living and polyvinyl-immobilised A.azollae produced H2 under argon for 7 to 8h. After that time H2 was consumed due to the development of uptake hydrogenase activity as shown when CO (inhibitor of hydrogenase activity) was added in the gas phase (see Fig. 1). The amount of H2 produced under argon by polyvinyl-immobilised cells was twice that produced by free-living cells; however, under argon and 4% CO it was similar for both samples. This indicates that the increase seen on immobilisation is mainly due to an increase in hydrogenase-mediated H2 production. Immobilisation in alginate did not

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significantly increase the rate of H2 production as compared with free-living cells but it maintained a net production for at least 20h. This can be due either to a stabilization of the enzymes on immobilisation or to a lower level of uptake hydrogenase activity in the immobilised cells. If we assume that hydrogenase and uptake-hydrogenase activity were completely inhibited in argon/4% CO and that no appreciable uptake-hydrogenase activity was developed under argon after 7h illumination, the comparison of H2 production under argon (hydrogenase+nitrogenase-mediated H2 production) and under argon/4% CO (nitrogenase-mediated H2 production) allows an estimation of the percentage of hydrogenasemediated H2 production. The calculated percentages were 26, 52 and 86% for free-1iving, polyvinyl-immobilised and alginate-immobilised cyanobacteria, respectively. The percentage of H2 production from hydrogenase was significantly increased on immobilisation, although nitrogenase activity (measured as C2H2 reduction) was maintained (see Table I). High yields of ammonia production were obtained from immobilised A.azollae in alginate with acetone pretreatment,and in polyvinyl foam PR22/60 in the presence of MSO. To our knowledge, such high yields have not been reported using cyanobacteria. Acetone pretreatment is known to increase the permeability of cell walls and membranes leading to facilitated transport of reactants and products. In the present case, excretion of phycobilins and degradation of chlorophylls during incubation following the acetone treatment indicates that it induces lysis of the cells and also affects the internal membranes, thus leading to the production of immobilised, non-viable cells; nevertheless, nitrogenase activity is preserved at least for 72h. Production of ammonia by acetone-pretreated, alginate-immobilised cells even in the absence of MSO suggests that glutamine synthetase activity was

Table I Initial rates of C2H2 reduction and rates measured after 10h. continous incubation in the light under argon/10% C2H2; temp. 25°C. 2d and 40d=days following immobilisation process in alginate or inoculation of the polyvinyl foam PR22/60. Sample Free (8d old culture) Free (2d old culture) Free (40d old culture) Imm. Alg. (2d) Imm. Alg. (40d) Imm. PR22/60 (40d)

Initial rate of reduction C2H2 Rate of C2H2 reduction reduction after 10h.

Per cent remaining

18.7

2.5

13

5.7

0.2

4

0

0

28.0 11.0 12.0

8.3 3.6 2.6

30 33 22

Hydrogen production, ammonia production and nitrogen fixation by free and immobilised cyanobacteria

Table II Ammonia production by free-living and immobilised A.azollae Alg: immobilisation in alginate beads (40d. after immobilisation) Alg. Ac: alginate beads with acetone pretreatment (1h acetone) PR22/60: immobilisation in polyvinyl foam PR22/60 (40d after inoculation of foam) Free: Free living control culture of immobilised filaments in PR22/60 –MS0: no addition of methionine sulphoximine (MSO) +MS0: in the presence of 50 µM MSO. Light intensity during incubation 70 µmoles photons m−2 sec−1 • temp. 30°C. Sample

Ammonia production (µmole NH3 mg chl−1) First 24h period Second 24h period Third 24h period Total

Alg.−MSO Alg.+MSO Alg.Ac−MSO Alg. Ac+MSO PR22/60−MSO PR22/60+MSO Free−MSO Free+MSO

0 1 25 20 1 151 9 8

2 0 27 67 0 387 0 0

2 7 18 162 0 298 0 8

4 8 70 249 1 836 9 16

partly inhibited by the acetone treatment. The highest ammonia production yield was obtained from A.azollae immobilised in polyvinyl foam. As this is not correlated with an increase of nitrogenase activity (C2H2 reduction) as compared with alginate-immobilised or free-living cells, it can be inferred that this high yield is related to an increase in cell wall permeability induced by the immobilisation process itself; this allows a greater accessibility of substrates and the inhibitor MSO and facilitates excretion of ammonia. Similar effects of immobilisation has been reported previously for bacteria immobilised in polyacrylamide matrices (15).

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ACKNONLEDGEMENTS M.Brouers is in receipt of a training contract from the Commission of the European Communities (Biomolecular Engineering programme). REFERENCES (1) CARR, N.G. and WHITTAN, B.A. (1982). The biology of cyanobacteria. Blackwell, Oxford. (2) LAMBERT, G.R. and SMITH, G.D. (1981). The hydrogen metabolism of cyanobacteria. Biological Reviews. 56, 589–660 (3) TEL-OR, E., LUIJK, L.W. and PACKER, L (1977). FEBS Lett. 78, 49–52. (4) TEL-OR, E., LUIJK, L.W. and PACKER, L. (1978) , Arch. Biochem. Biophys. 185–194. (5) HOBERMAN, H.D. and RITTENBERG, D. (1943). J. Biol. Chem 147, 211–227. (6) PETERSON, R.B. and BURRIS, R.H. (1978) Arch. Microbiol. 116, 125–132. (7) DADAY, A. LAMBERT, G.R. and SMITH. G.D. (1979). Biochem. J. 177, 139–144. (8) PETERS, G.A., RAY, T.B., MAYNE, B.C. and TOIA, R.E. (1980). In Nitrogen fixation (Newton, W.E., Orme-Johnson, W.H. eds.). Vol.II, pp.293–309. University Park Press, Baltimore. (9) STEWART, W.D.P. and ROWELL, P. (1975). Biochem. Biophys. Res. Comm. 65, 846–856 (10) STAINER, R.Y., KUNISAWA, R., MANDEL, M and COHEN-BAZIRE, G. (1981) Bacteriol. Rev. 35, 171–205. (11) ALLEN, M.B. and ARNON, D.I. (1955). Plant Physiology 30, 366–372. (12) MUALLEM, A., BRUCE, D. and HALL, D.O. (1983). Biotech. Lett. 5, 365–368 (13) BROUERS et. al. In “Photochemical, Photoelectrochemical and Photobiological processes” (1982–1983) (D.O.Hall and W.Palz eds.) Vol. I. pp.134–139. Vol II pp. 170–178. D. Reidel Pub. Co. Dordrecht. (14) SOLORZANO, L(1969). Limnol, Oceanogr. 14. 799–801. (15) YAMAMOTO , K, SATO, T., TOSA, and CHIBATA, I. (1974). Biotechnol. Bioeng. XVI, 1589–1599 and 1601–1610.

EFFECT OF DIFFERENT FACTORS ON THE PRODUCTIVITY OF THE NITROGEN FIXING BLUE-GREEN ALGA Anabaena variabilis UNDER OUTDOOR CONDITIONS A.G.FONTES, J.MORENO, M.A.VARGAS, M.G.GUERRERO and M LOSADA Departamento de Bioquímica, Facultad de Biología y C.S.I.C. Apartado 1095, E-41080 Sevilla, Spain Summary The effect of several relevant factors influencing the productivity of the blue-green alga Anabaena variabilis has been investigated in outdoor semicontinuous cultures. Air, sparged through the cultures to promote turbulence, was enough by itself to provide all the carbon and nitrogen needed for maximal productivity when supplied at a flow rate of 601 per 1 of cell suspension per h. As a matter of fact, the addition of either or both, CO2 and combined nitrogen (as KNO3 or NH4C1) , did not result in any productivity increase. For a suspension depth of 25cm, the optimal cell loading was 0.2– −0.3g (dry weight) 1−1. Reciprocally, for a cell loading of 0.2g (dry weight) 1−1, optimal suspension depth was determined to be 20– −25cm. Under these conditions, the protein content of the cells was about 65% of the dry weight, and obtained productivity values were 13±1g (dry weight) m−2 day−1. The nitrogen-fixing blue–green alga A.variabilis seems thus a suitable organism for the production of proteinrich biomass at the expense of solar energy and atmospheric nitrogen, the latter being fixed at a rate of about 1.4gNm−2 day−1. A dual extrapolation, both in time and area, of the results obtained gives a productivity value per ha and year of 47 ton dry biomass with a content of 30 ton protein, which corresponds to the fixation of 5 ton nitrogen.

1. INTRODUCTION The use of microorganisms for the generation of biomass with a high protein content, suitable for different aims, is a scope of increasing interest. Among the microalgae, the nitrogen-fixing blue-greens (cyanobacteria) appear particularly attractive for the production of protein-rich biomass, since they are able to synthesize all their cell components, at the expense of solar energy, from water, air and a few mineral salts. Nitrogen fertilizer, expensive in terms of both money and energy, is no required as a

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component of the growth medium for these organisms, since they can use atmospheric nitrogen as the sole nitrogen source (1). A basic issue in microalgae biomass production is the achievement of conditions under which an optimal use of incident sunlight energy by the cells in the culture takes place. In this context, and provided that nutrients are not limiting, factors as the cell density and the depth and turbulence of the suspension have a relevant effect on productivity (2–4). The present study is aimed to determine optimal values for these factors in relation to the outdoor semicontinuous culture of the N2-fixing blue-green alga Anabaena variabilis. 2. MATERIALS AND METHODS Anabaena variabilis strain ATCC 29413 cells were grown in containers of variable depth, with the upper surface (0.25m2) open to the air, set up on the roof of the Faculty of Biology, Seville. The suspensions were sparged with air or CO2-supplemented air (1–99, v/v) at a rate of 601 per 1 cell suspension per h, and the temperature was kept at 30°C. The culture medium of Arnon et al. (5) was used. Once a day, in the late afternoon, part of the cell suspension was removed and replaced with fresh medium in order to start the subsequent light period at a convenient cell density. Chlorophyll concentration in the cells was determined according to MacKinney (6). For dry weight determination, 100–200 ml aliquots of the cell culture were filtered through Whatman GF/C paper, washed twice, and the filters containing the algae were dried at 80°C for 24h. Nitrogen content was estimated in dried samples with an elemental analyzer Carlo Erba Strumentazione model 1106/R connected to a Hewlett-Packard integrator model 3390 A. The experiments were carried out for several months during the Summer. The mean value of total incident solar energy was 23MJ m−2 day −1, corresponding to an average irradiance of 450W m−2 during an illumination period of 14h. 3. RESULTS AND DISCUSSION A study of the effect of sparging the cell suspension with air at various flow-rates showed that limitation of growth existed at flow rates below 60l per l of cell suspension per h, with no further improvement in productivity being observed by sparging air at flow rates higher than 60 1 1−1 (cell suspension) h−1 (results not shown) . All further experiments were therefore carried out by using an air flow rate of 60 1 1−1 (cell suspension) h−1. The sparging of air through the cell suspension at this flow rate provided not only the turbulence required for a convenient exposure to light of the algae in the suspension, but also all the carbon

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TABLE I. Effect of the nitrogen source and the carbon dioxide supply on biomass productivity in semicontinuous outdoor cultures of A.variabilis Nitrogen source Productivity (g (d.w.) m−2 day−1) air air, 1% CO2 N2 (air) KNO3 (10 mM) NH4C1 (5 mM)

13.6±3.2 14.2±3.1 14.4±3.0

13.2±3.8 13.6±3.7 13.5±3.1

The depth of the cultures was 25cm, and the cell density was maintained at a value of 3.5mg (ch1) 1−1. The values shown, with their corresponding standard deviations, are averages of four independent determinations throughout four consecutive days. and nitrogen required for optimal growth. This is substantiated by the results shown in Table I, which clearly indicate that neither the supply of CO2 to the air sparged nor the addition of combined nitrogen (either as nitrate or as ammonium) resulted in any significant improvement in productivity. Selection of the appropriate density of the cell suspension is an important point for optimal operation of the system. The determination of the optimal cell density value was performed by using several 25cm-deep containers containing suspensions with variable cell loading. The results in Fig. 1 show that maximal productivity was obtained at cell density values between 2 and 3.5mg (chlorophyll) 1−1, equivalent to 0.2–0.3g (dry weight) 1−1. Increasing the cell density resulted in a decrease in productivity, which might well be a consequence of mutual shading of the cells.

Figure 1 Effect of cell density on biomass productivity in

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semicontinuous outdoor cultures of A.variabilis. The depth of the cultures was 25cm. The values shown, with their corresponding standard deviations, are averages of six independent determinations throughout six consecutive days. The effect of the culture depth was studied by using several containers of different depth (15–55cm) filled with the same Anabaena suspension containing 2mg (chlorophyll) 1−1. From the results in Fig. 2 it can be concluded that the optimal depth for such a cell loading is 20– –25cm, with the productivity decreasing significantly at depths below 20 cm and above 25cm. The results might be interpreted in terms of overexposure of the cells to light for depths below 20cm and suboptimal illumination at depths of 30cm or more. The suspension depth also had a noticeable effect on the chlorophyll and nitrogen content of the cells. As shown in Fig. 3A, the chlorophyll

Figure 2. Effect of the culture depth on biomass productivity in semicontinuous outdoor cultures of A.variabilis. The density of the cell suspensions was maintained at a value of 2mg (ch1) 1−1. The values shown, with their corresponding standard deviations, are averages of four

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independent determinations throughout four consecutive days.

Figure 3. Effect of the culture depth on the chlorophyll and nitrogen content of A.variabilis cells in semicontinuous outdoor cultures. The density of the cell suspensions was maintained at a value of 3.5mg (ch1) 1−1. The values shown, with their corresponding standard deviations, are averages of three independent determinations throughout three consecutive days. content of the cells increased from 1.25 to 1.47 per cent in response to an increase in the culture depth from 15cm to 30cm. This can reflect an adaption of the cells to a decreased availability of light in the deeper cultures. In line with this interpretation is the fact that a similar increase in the chlorophyll content of the cells is also observed in response to an increase in cell density of the cultures (results not shown). The nitrogen content of the cells also increases in response to an increase in the culture depth (Fig. 3B) . This can also be related to the adaptive increase in the level of photosynthetic pigments under conditions of decreased availability of light, since the predominant accesory pigments in the blue-green algae are phycobiliproteins. From the estimated values of N content, crude protein content values (N×6.25) of 59–64% of the dry weight can be calculated for A.variabilis. In summary, with air sparged through the cultures at a flow rate of 60l per 1 of cell suspension per h as the sole source of carbon and nitrogen, a vigorous growth of

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A.variabilis, with mean productivity values of 13±1g (dry weight) m−2 day−1, can be sustained in outdoor semicontinuous cultures. Actually, a dual extrapolation of this quantity, both in time and area, gives a productivity value per ha and per year of 47 ton dry biomass with a content of 30 ton protein, which corresponds to 5 ton ha−1 year−1 of atmospheric nitrogen being fixed. This emphasyzes the potential of the N2-fixing bluegreen algae for the purpose of photoproduction of biomass with a high-protein content. 4. ACKNOWLEDGEMENTS Research supported by grants from Dragados y Construcciones S.A. and Comisión Asesora de Investigación Científica y Técnica (Spain). The authors thank Mrs. M.J.Pérez de León for secretarial assistance. 5. REFERENCES (1) FONTES, A.G.,RIVAS, J., GUERRERO, M.G.and LOSADA, M. (1983). Production of highquality biomass by nitrogen-fixing blue-green algae. In; Proceedings of the 2nd E.C. Conference Energy from Biomass (A.Strub, P.Chartier and G.Schlesser, Eds.), Applied Science Publ., London, pp. 265–269. (2) RICHMOND, A. , VONSHAK, A. and ARAD, S. (1980). Environmental limitations in outdoor production of algal biomass. In: Algae Biomass (G.Shelef and C.J.Soeder Eds.), Elsevier/North Holland Biomedical Press, Amsterdam, pp. 65–72. (3) VONSHAK, A., ABELIOVICH, A., BOUSSIBA, S., ARAD, S. and RICHMOND, A. (1982). Production of Spirulina biomass: Effects of environmental factors and population density. Biomass, 2, 175–185. (4) RICHMOND, A (1983). Phototrophic microalgae. In; Biotechnology, vol. 3 (H.Dellweg, Ed.) Verlag Chemie, Weinheim, pp. 109–143. (5) ARNON, D.I.,McSWAIN, B.D.,TSUJIMOTO, H.Y.and WADA, K. (1974). Photochemical activity and components of membrane preparations from blue-green algae. I. Coexistence of two photosystems in relation to chlorophyll a and removal of phycocyanin. Biochim. Biophys. Acta, 357, 231–245. (6) MacKINNEY, G (1941). Absorption of light by chlorophyll solutions. J. Biol. Chem., 140, 315–322.

AN ENERGY BUDGET FOR ALGAL CULTURE ON ANIMAL SLURRY IN TEMPERATE CLIMATIC CONDITIONS H.J.Fallowfield1 and M.K.Garrett, Department of Agricultural and Food Chemistry, Queen’s University of Belfast, Newforge Lane, Belfast, Northern Ireland Summary A pilot plant (11.1m2) for the outdoor photosynthetic treatment of the diluted (1:9) liquid phase of pig slurry using the green alga Chlorella vulgaris was operated in autumn 1981 and summer 1982. Pilot plant performance, algal biomass production and effluent treatment efficiency was monitored. Electrical energy inputs and potential biomass energy yields were determined and an energy budget for mass algal culture was constructed. Algal culture mixing was the most energy intensive pilot plant operation. The algal biomass, together with a relatively minor contribution from the separated slurry solids, was the major potential source of energy. The results of the pilot plant study were used to produce a theoretical energy budget for a large integrated energy yielding system by which electrical energy may be generated from algal biomass via anaerobic digestion.

1. INTRODUCTION The concept of the high-rate algal pond for mass algal culture in wastewater has been researched and developed by Oswald (1 & 2) and Shelef (3). The integration of intensive animal rearing units and algal treatment systems may, however, more effectively utilise the potential value, both nutritional and calorific, of the algal biomass produced (4). Following almost a decade of laboratory studies by Garrett and co-workers (5) an outdoor pilot plant for the culture of algae in the diluted liquid phase of pig slurry was constructed and operated (1981–1982) at the Agricultural Research Institute, Hillsborough, Co. Down. The aims of the project were, firstly to determine algal dry matter (DM) productivities and effluent treatment capability and secondly to construct an energy budget for the process. The detailed results of pilot plant operation, effluent treatment efficiency and biomass production have been presented elsewhere (6). The potential for algal bioconversion of solar energy has been reviewed by several workers (7, 8 & 9) and data are available for tropical and sub-tropical locations (10 & 11). In this paper an energy budget is presented for algal culture in pig slurry in the temperate climatic conditions of Northern Ireland.

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2. PILOT PLANT DESIGN AND OPERATION Pilot plant design considerations were previously discussed (12). The two raceways for algal culture each provided a surface area of 11.1m2 which, at a depth of 0.2m, gave a volume of 2.2m3. The cultures were

Fig. 1 The power consumption and energy input for pumping slurry to algal cultures. mixed by a 12 bladed paddlewheel powered by a 3 phase electric motor. The cultures were operated continuously with the rate of addition of separated, flocculated diluted pig slurry (via a diaphragm metering pump) controlling retention times. The power inputs in the slurry pretreatment area were; the slurry mixer (135kJ s−1), a submersible pump (269) delivering slurry to the rotary press screen separator which was powered by a 3 phase electric motor (570). 3. ENERGY INPUTS The energy expenditure for slurry separation was dependent upon retention times (12.8– 4.5d) and varied from 2.93–5.71kJ m−2d−1. This energy input was offset against that potentially available from the separated solids (18.5kJ g−1). Assuming a 2% solids removal there was a net energy deficit for separation of 2.1–4.05kJ m−2d−1. Delivering slurry to the cultures at a rate of 24 1h−1 (retention time 4.5d), continuously over 24h, expended 9.12MJ d−1 equivalent to 821kJ m−2d−1. The energy requirement was estimated (Fig 1) for pumping to systems with from the data that at surface areas <50m2 there was an inverse relationlarger surface areas (retention time 4.5d); depth 0.2m). It was evident ship between energy input and surface area. The energy requirement for pumping was

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excluded from the energy budget; firstly because the size of the plant was artificially inflating the energy input and secondly, gravity flow was considered a more appropriate delivery method for larger treatment systems. The algal culture was mixed (24h d−1) at a constant mean surface velocity of 0.21m s−1 which required an input of 688.8kJ 4. POTENTIAL SOURCE OF ENERGY The mean energy content of the algal/bacterial biomass was 21.17 kJ g−1 This value together with the total DM productivity was used to calculate the potential gross biomass energy production (Table I). These results suggested a 153d Northern Ireland growing season with a productivity of 0.16t ha−1d−1 equivalent to a gross energy yield, at 2.3% solar conversion efficiency (visible spectrum), of 3.38GJ ha−1d−1.

Table I Mean

biomass production values Productivity Algal Total DM

g m−2d−1 7.18 kJ m−2d−1 152 May–Aug, 1982 g m−2d−1 18.29 kJ m−2d−1 387 Sept-Nov, 1981

15.33 325 28.52 604

5. AN ENERGY BUDGET FOR ALGAL CULTURE Overall there was a net energy deficit for algal cultures operated on a 24hd−1 mixing regime. Isolated net energy surpluses were recorded in June, July (+259kJ m−2d−1) and August. The major energy input was for culture mixing. Preliminary experiments suggest that an 8h d−1 mixing regime, whilst significantly reducing the energy input, has only a minor effect upon algal productivity. A theoretical budget for 8h mixing, assuming no decrease in productivity, is also presented in Table II. Further calculations show that such a culture could withstand a 30–40% reduction in mean total DM production whilst still maintaining at least a balanced energy budget.

Table II An energy budget for algal culture in pig slurry liquid phase 1981 1982 Mixing Regime Sept Oct Nov May June July Aug 24h d−1 (kJ m−2d−1) −230 −426 −380 −300 −72 −58 61 8h d−1 (kJ m−2d−1) 228 33.3 19.2 159 387 401 520

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6. A THEORECTICAL ENERGY BUDGET FOR A LARGE INTEGRATED ENERGY YIELDING SYSTEM It was possible using Manning’s equation, describing open channel flow to estimate 8h d−1 mixing energy requirements for 1ha pond systems. A theoretical energy budget for an integrated algal biomass—anaerobic digestion—electrical generation system was calculated using algal productivities attained in the 11.1m2 pilot plant system. The daily energy budget for outdoor mass algal culture (May—September) in temperate climatic conditions is presented in Fig 2. The following assumptions were made; an 80% harvest efficiency (9, 10); a 60% recovery of solar energy via methane (9) and electrical energy generated from methane at 25% efficiency (9). Further calculations suggest that, from algal biomass produced at a photoefficiency of 2.3%, methane and electricity may be generated at 1.1 and 0.3% solar conversion efficiencies respectively. 7. DISCUSSION The algal productivities presented here are approaching the predicted

Fig.2. A theoretical daliy energy budget for outdoor mass algal culture (May–September) in temperate climate condition.

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maximum values (7) attainable at latitude 50°N for 2−3% solar conversion efficiencies. These optimised biomass productivities resulted in theoretical energy yields, for a 1ha integrated pond system, comparable with similar estimates by Oswald (7) and Keenan (9) for the USA. However, the estimated Northern Ireland values would only be attainable for a limited growing season (May—September). The greater potential value of an algal wastewater treatment plant may be as a photosynthetic oxygenation system to reduce BOD; conserving energy otherwise consumed by intensive mechanical aeration systems (10, 4). REFERENCES (1) OSWALD, W.J. (1963). The high rate pond in waste disposal. Developments in Industrial Microbiology, 4, 112–121. (2) OSWALD, W.J. (1980). Algal production-problems, achievements and potential. In: Algae Biomass. Elsevier/North Holland Biomedical Press, Amsterdam. (3) SHELEF, G. et al (1976). Combined algae production-waste water treatment and reclamation systems. In: Microbial Energy Production (Schlegel, H.G. & Barnes, J.) Erich Galtze, K.G., Gottingen. (4) FALLOWFIELD, H.J. & GARRETT, M.K. (1985). The treatment of wastes by algal culture. In: Microbial Aspects of Water Management (White, W.R.). Society of Applied Bacteriology Symposium No 14, Blackwell Scientific Press. (5) GARRETT, M.K. & ALLEN, M.D.B. (1976). Photosynthetic purification of the liquid phase of animal slurry. Environ. Pollution 127–139. (6) FALLOWFIELD, H.J. & GARRETT, M.K. (1985). The photosynthetic treatment of pig slurry in temperate climatic conditions: A pilot plant study. Agricultural Wastes, 12, 111–136. (7) OSWALD, W.J. (1976). Determinants of feasibility in bioconversion of solar energy: In: Research in Photobiology, (Castellani, A.) Plenum Press , New York. (8) BENEMANN, J.R et al (1977). Energy production by microbial photosynthesis. Nature (London), 268, 19–23. (9) KEENAN, J.D. (1977). Bioconversion of solar energy to methane. Energy 2, 365–373. (10) OSWALD, W.J & EISENBERG, A.M. (1981). Energy from waste grown microalgae. A.S.C.E. Conference, ‘Energy and the man built environment—The next decade’. Vail, Colorado, August 3–5, 1981. (11) BALLONI, W., et al, (1983). Mass cultures of algae for energy farming in coastal deserts. In: Energy from Biomass. Proceedings of 2nd EC Conference. Applied Science Publishers. (12) GARRETT, M.K. & FALLOWFIELD, H.J. (1981). Algal biomass from farm waste—A pilot plant study. In: Energy from Biomass. Proceedings of 1st EC Conference. Applied Science Publishers. 1

Present address: Microbiology Department, The West of Scotland Agricultural College, Auchincruive, Ayr, U.K.

PHOTOSYNTHETIC BASIS OF BIOMASS PRODUCTION BY WATER HYACINTH GROWN UNDER HIGH CO2 LEVEL A.LARIGAUDERIE, J.ROY and A.BERGER, Laboratoire d’Ecophysiologie, C.N.R.S./ Centre Louis Emberger, Route de Mende BP 5051, 34033 MONTPELLIER cedex, FRANCE. ABSTRACT Long term CO2 enrichment do not decrease either the high photosynthetic capacities of water hyacinth or its ability to utilize high irradiances. The response of water hyacinth to CO2 enrichment differs from what has been shown on other species. The relationships between these results and the high biomass production capacity of water hyacinth are discussed.

1. INTRODUCTION Short term exposure to high CO2 atmospheric concentrations enhances photosynthetic rates (e.g.: BRUN and COOPER 1967, MAUNEY and al. 1979, MORISON and GIFFORD 1983…) and in most cases culture of plants at high CO2 levels in optimized systems results in enhanced dry matter accumulation (e.g.: COOPER and BRUN 1967, WONG 1979, SIONIT and al. 1980, CARLSON and BAZZAZ 1982…). However, long term CO2 enrichment affects not only photosynthesis but also its regulation by other physiological processes not clearly defined. Very few studies have examined the effect of long term CO2 enrichment on the photosynthetic capacities of the plants and their results suggest that elevated rates of photosynthesis observed during short term exposure cannot be maintained during long term exposure and that growth at high CO2 concentration results in a reduction of photosynthetic capacity (RAPER and PEEDIN 1978, CLOUGH and al. 1981). More studies are needed on the response of the physiological mechanisms to CO2 enrichment and on the variation of this response between species. The plant examined in this study is water hyacinth (Eichhornia crassipes). It is a perennial, fresh water plant which constitutes the more important weed in most tropical or subtropical countries because of its high capacity of biomass production -by vegetative multiplication essentially-. This biomass can be utilized for different purposes and is in our case exploited for protein production. Photosynthetic response to light and to CO2 concentration of water hyacinths grown at normal and 10000ppm CO2 are presented. 2. MATERIAL AND METHODS Water hyacinths from a single clone were grown during the summer under two conditions: in a greenhouse at 10000 ppm CO2 (Relative humidity ~100%, Day/ Night

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temperature: 30–40°C/ 20°C, PAR -Photosynthetic Active Radiation- received per summer month: 800mol.m−2) and outside at normal (330–340ppm) CO2 concentration (Day/ Night temperature: 25–65°C/ 15–20°C, PAR received per summer month: 1300mol.m−2). We used a COIC- LESAINT nutritive solution whose composition was verified and adjusted daily. Photosynthetic measurements were done on the last fully expanded leaves. Non excised leaves were enclosed in assimilating chambers connected to an open gas exchange system (WINNNER and MOONEY 1980). Light, humidity, ambient CO2 concentration and temperature were controlled. All the curves presented were realized in the optimal range of leaf temperatures. 3. RESULTS AND DISCUSSION 3.1 Photosynthetic response to CO2 concentration Greenhouse plants present a classical response to increasing ambient CO2 concentration, with a saturation plateau reached at about 1800ppm (Figure 1A, three repetitions on different leaves are presented). For outside plants, maximum CO2 assimilation rate is reached at 1000–1200ppm but then decreases (Figure 1B, four repetitions). The decrease of net photosynthesis with increasing CO2 concentration is immediately reversible. An interaction between light intensity and CO2 concentration during growth is responsible for this particuliar photosynthetic response to CO2 of outside plants (LARIGAUDERIE 1985). Mean maximum net photosynthetic rates are 63.1±7.4 and 56.9±4.4 µmolCO2.m−2.s−1 (mean ±standard error) respectively for outside and greenhouse plants. These values are not statistically different. Thus, in water hyacinth, long term CO2 enrichment do not decrease the photosynthetic capacity. The maximum net photosynthesis (at 1200ppm) is high and twice that at normal CO2 level (340ppm) for both types of plants.

Figure 1: Response of net photosynthesis to ambient CO2

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concentration (µmol.mol−1); E= 2000µmol.m−2.s−1, VPD=1 KPa; A: plants grown at 10000ppm. B: plants grown at 340ppm, 3.2 Photosynthetic response to light intensity Regardless of their growth conditions plants are capable of utilizing very high irradiances. Photosynthesis is not light satured at 1500 µmol.m−2.s−1 when measured either at 340ppm or at 1200ppm (Figure 2). Quantum yield (µmolCO2 fixed per umol quanta absorbed) is determined by the photosynthesis versus light curves at low light intensities. Quantum yield measured at 340ppm is similar for outside and greenhouse plants (.0562±0086 and .0562±0069) and increases by 30 and 60% when measured at 1200ppm for these two types of plants respectively. The increase of quantum yield with CO2 has already been shown on plants grown at normal CO2 concentration (EHLERINGER and BJORKMAN 1977) and is attributed to the decrease of the oxygenase activity of the Ribulose 1–5, Biphosphate Carboxylase Oxygenase with respect to its carboxylase activity. Our study shows that growth of the plants at high CO2 level does not reduce their quantum yield. The higher response of the quantum yield to the ambient CO2 in greenhouse plants compared to the outside plants needs to be confirmed.

Figure 2: Response of net photosynthesis (µmol .m−2.s−1) to light intensity (µmol.m−2.s−1); Tf= 32°C, VPD= 1 KPa; A: plants grown at 340ppm, B: plants grown at 10000ppm.

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4. CONCLUSION Our water hyacinth clone produced a very high biomass production grown in CO2 enriched atmosphere (BROCHIER and al., this symposium). The physiological measurements presented in this study are in good agreement with biomass measurements: Long term CO2 enrichment does not decrease the high photosynthetic capacity of water hyacinth as it does with other species. Photosynthetic rates at 340ppm (35– 40µmolCO2.m−2.s−1) are higher than the mean values for other C3 plants (14– 23µmolCO2.m−2.s−1) (KÖRNER et al. 1979). Models of the photosynthetic efficiency of crop species (VARLET-GRANCHET and al. 1981) indicate that quantum yield and photosynthetic rate at saturating light are two important parameters as far as canopy productivity is concerned. These results show that physiological in addition to demographic (leaf and ramet birth rates) traits contribute to the high productivity of water hyacinth and make it an adequate species for biomass production in CO2 enriched atmosphere. REFERENCES BRUN W.A. and COOPER R.L..,1967.—Effects of light intensity and carbon dioxide concentration on photosynthesis rate of soybean. Crop Sci., 7, 451–454. CARLSON R.W. and BAZZAZ F.A., 1982.—Photosynthetic and growth response to fumigation with SO2 at elevated CO2 for C3 and C4 plants. Oecologia, 54, 50–54. CLOUGH J.M., PEET M.M., and KRAMER P.J., 1981.—Effects of high atmospheric CO2 and sink size on rates of photosynthesis of a soybean cultivar. Plant Physiol., 67, 1007–1010. COOPER R.L. and BRUN W.A., 1967.—Response of soybeans to carbon dioxide-enriched atmosphere. Crop Sci., 7, 455–457. EHLERINGER J. and BJÖRKMAN 0., 1977.—Quantum yield for CO2 uptake in C3 and C4 plants. Plant Physiol., 59, 86–90. KÖRNER Ch., SCHEEL J.A. and BAUER H., 1979.—Maximum leaf diffusive conductance in vascular plants. Photosynthetica, 13, 45–82. LARIGAUDERIE A., 1985.—Ecophysiologie des échanges gazeux chez Eichhornia crassipes Mart. Solms (Jacinthe d’eau): réponse aux fortes teneurs en CO2. Third cycle thesis, U.S.T.L. Montpellier, 109p. MAUNEY J.R.,GUINN G. FRY K.E. and HESKETH J.D., 1979.—Correlation of photosynthetic carbon dioxide uptake and carbohydrate accumulation in cotton, soybean, sunflower and sorghum. Photosynthetica, 13, 260–266. MORISON I.L. and GIFFORD R.M., 1983.—Stomatal sensitivity to carbon dioxide and humidity. Plant Physiol.., 71, 789–796. RAPER C.Dand PEEDIN G., 1978.—Photosynthetic rate during steadystate growth as influenced by carbon-dioxide concentration. Bot. Gaz., 139, 147–149. SIONIT N., HELLMERS H. and STRAIN B.R., 1980.—Growth and yield of wheat under CO2 enrichment and water stress. Crop Sci., 20, 687–690. VARLET-GRANCHET C., BONHOMME R. CHARTIER M. and ARTIS P., 1981.—Evolution de la réponse photosynthétique des feuilles et efficience théorique de la photosynthèse brute d’une culture de canne a sucre (Saccharum officinarum L.). Agronomie, 1, 473–481.

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WINNER W.E. and MOONEY H.A., 1980.—Ecology of SO2 resistance: I. Effects of fumigations on gas exchange of deciduous and evergreen shrubs. Oecologia, 44, 290–295.

ACKNOWLEDGMENTS We thank J.Brochier, F.Jardon, J.Fabreguettes and J.L.Salager for their assistance during the experiments. This work was supported by Spie Batignolles.

EICHHORNIA CRASSIPES : PRODUCTION IN REPEATED HARVEST SYSTEMS ON WASTE WATER IN THE LANGUEDOC REGION (FRANCE) Marie-Luce CHASSANY DE CASABIANCA CNRS—USTL, Place Bataillon, F-34060 Montpellier Cedex France Summary The original method attempted allows the study of E. crassipes production (in terms of real harvest values) and the purification results (in terms of biomass removed) on a seasonal and annual basis, using five systems operating in parallel on waste water. These systems have different on-site biomass values, maintained by regular harvests ; the harvest is adjusted each time according to system production. Production, conditioned by maximum temperatures greater than 15°C, went on for 6 months, 4/5 (production greater than 20g m−2 day−1) being concentrated in the three summer months. An integrated harvest systems the mean varies between 40.5 to 47 t ha−1 year−1 DW (30.6–35.2g DW m−2 day−1 for the whole of the production period). This corresponds to the removal of 1500–1900g m−2 of Cn 180– 220g m−2 of N and 35–43g m−2 of P2O5. The best system (annual production of 69.5t ha−1 year−1) in this cultivation mode had an on-site biomass of 13kg WW m−2 at the beginning of the summer and 33kg WW m−2 at the end. Production and purification of systems limited to a single harvest (at the end of the summer) were inferior by a factor of 3.

1. INTRODUCTION The study was part of a coordinated and integrated regional effort combining summer biomass, its development and water purification. The use of Eichhornia crassipes systems in a semi-artificial environment with waste water was analysed. It is a well known fact that this species has a high productivity and purification potential. The acclimatization of E. crassipes and its adaptability to waste water were tested in preliminary experiments carried out at the medium load sludge purification station at Saint-Gély-du-Fesc, in the Hérault departement (1). We chose to characterize production and/or purification systems in terms of biomass removed in the different harvest methods and the annual climatic variability in the Languedoc region. When compared to the large number of previous studies on this topic (2–10) this study of E. crassipes presents several new problems :

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1) If pilot projects are to be set up, it is essential to establish seasonal as well as annual production and purification figures. These data should have the following two unprecedented characteristics: – They should represent workable figures, with which valid averages may be established, i.e. based on various cultivation modes, and reduces to a specified initial biomass m−2. – They should represent production and purification values \which correspond to a real biomass value removed by harvest. 2) New elements, which allow the testing of harvest influence on the production system. 2. METHODS The experimehts were carried out at the medium load activated sludge purification station at Saint-Gé1y-du-Fesc (Hérault, France) on samples of Congo strain E. crassipes. They were cultivated in five basins with a surface of 8m2 and a depth of 0.5m, operating in parallel on waste water, in a discontinuous mode, with total water replenishment by siphoning. 3 day detention time in the basins was adopted for a high nutritive salt surplus feeding (the nutritive salt variations were 0.1–19ppm of N for NH4, 0.05ppm of N for NO2 and NO3 and 2.4 to 27ppm of P2O5 for PO4). (1) The stands were monitored for 5 months from 25 May to 25 October, 1983. Five basins with differents biomass operated in parallel. Each of the first four was reduced to its original biomass by weekly harvesting. The harvest was adjusted to the production value. The fifth basin was not harvested until the end of the season. The experimentation period as a whole can be divided into three pha- ses, which apper in fig.1

Fig 1: diagram of the experiment: biomass variations (WW m2) in the, regularly harvested basins basins (B1,

Eichhornia crassipes: production in repeated harvest systems on waste water in the languedoc region (france)

B2, B3, B4) and the basin without harvest (WH) during 1983. (i) Spring and summer (from 10 June to 3 August, 1983) with harvests during which the chosen initial biomass values were respectively (kg): 1, 4, 6, 8 and 11. (ii) Summer allows the populations to grow, giving greater biomass values. (iii) Fall, during which the chosen initial biomass values were respectively (kg WW m−2): 24, 28, 33 and 40. The formulae for production, growth and purification were as follows. Annual production of E. crassipes in the Languedoc region, in open air systems, was calculated in 1983 for the 4.5 months experimentation period from the average values for the four basins and was based on real harvest values, without extrapolation. It corresponds to the formula : Hs where Bi and Bf are, respectively, initial and final biomass and where the total of the seasonal production, Ps can be integrated with the total of the successive harvests Hs. 3. RESULTS A. Production variations accordinq to climatic data 1) Seasonal variation curve for E. crassipes production (Fig 2):

Fig. 2: Daily production means over the whole of thd systems With harvests (mean values and devia-tions from the. me,an calcu-lated over two consecultive time intervals, each separated by two harvests). Hatching for production greater than 20g DW m−2 day−1. The mean production curve shows very clearly that, outside, E. crassipes production over the year is greater than 10g DW day−1 over 6 months. Virtually all the production took

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place over three months, with a mean daily production greater than 20g DW m−2 (calculated for the entire series of basins); this refers to 2.5 months, where 2030g DW m−2 day−1. The remainder of the production is limited to 15 days where 10
Fig. 3: Correlation between between the, E. crassipes daily daily production means (in g DW m−2 day−1 calculated for the whole. of the four harvested basins and for each weekly period separated by two harvests) and means of the daily maximum temperatures (C) caleulated during the same period, from 25 May to 3 August, 1983. The formula y=1.65x–25.13 shows in particular : – No production when the mean maximum temperature of the period under consideration is less than 15.15°C. – A mean production located between 10 and 20g DW m−2 day−1 for maximum temperatures between 20°C and 30°C. – Mean production greater than 30g DW m−2 day−1 for maximum temperatures greater than 33°C. B. Production analysis accordinq to on-site biomass Fig. 4 shows that the curves (curves 1 et 2) of production depend on the on-site biomass. The following was observed: there was a production increase, depending on the on-site biomass increase, up to the production peak obtained in spring with a biomass value of

Eichhornia crassipes: production in repeated harvest systems on waste water in the languedoc region (france)

13.1±2.2kg (WW m−2) and in autumn with a biomass value of 32.5kg WW m−2, whereas the density peak occurred in the inflection zone:

Fig. 4: Daily production means per system, as a function of the corresponding mean in initial biomass August, 1983 (curve 1). Period from 75 September to 11 October, 1983 (curve 2). Excepting the shift of the growth curve on the ordinate, which should be attributed to seasonal temperature influence, the shift of the growth on the abscissa can be connected to another physiological phenomenon linked to the season through population structure: hence, the exponential phase of curve (1) corresponds to a great extent to horizontal multiplication through runners, whereas curve (2) corresponds more to vertical growth rather than to horizontal vegetative propagation. C. Seasonal and annual productions and purification resulting from the biomass removed by harvest in the various systems (Table 1)

Table 1: Mean Annual Production and Purification in Harvested Systems (I, II, IV) Characterized by Increasing Biomass Biomass Ranges, and in WH (without harvest) Systems during the, Spring and Fall periods Different systems (mean biomass)

I(6.8/20.5) II(8.85/27.9)

Productiona (t DW Harvest or daily ha−1 year−1) production (*)

38 42.27

30.62 35.22

Elements removed by harvest (g m−2 year−1) Purifi cationb C N P 1565.5 1741.4

184.3 205

35.5 39.2

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45.45 20.0 64.76

35.16 16.4 51.25

1872.5 824 2668

229.4 97 314

42.5 18.7 60.5

a Production (t DW ha−1 year−1) expressed in biomass removed by harvest in the different systems (calculated over 4 months) b Purification: nitrogen and phosphorus removed by harvest (g DW m−2)

4. CONCLUSIONS 1) The mean production figures for the harvested systems in waste water show relatively small differences and vary between 38 and 45.5t ha−1 year−1; this corresponds to a mean daily production from 30.6 to 35.22g DW m−2 day−1, calculated for the experimentation period. These values cor-respond to 1500–1900g m−2 of carbon, from 180 to 220g m−2 of nitrogen and from 35 to 43g m−2 of phosphorus removed annually (calculated over 4.5 months). 2) In a system with no harvest, production obtained is only 20t ha−1 year−1, i.e. is half as much, on a production or purification level, as in the harvested systems. 3) The highest cumulative production values are 64.76t ha−1 year−1 with a daily mean of 51.25g DW m−2 day−1 over 4.5 months. These figures correspond to a range of on-site biomass maintained in the basins of 13kg WW m−2 during the first period and 30–33kg WW m−2 during the second and third periods. 4) The mean daily production values obtained in Saint-Gély-du-Fesc over the entire production period, compared to the existing data (2–10), are in general greater; thus, the daily production values, correlated with the maximum temperatures, can in the most efficient systems in Saint-Gély-du-Fesc reach mean values of 65g DW m−2 day−1 over the production period. However, the staggering of the production period, being limited by minimum temperatures less than 10°C, reduces the daily production calculated over 12 months to a value of less than one-third of this. REFERENCES (1) CHASSANY DE CASABIANCA, M.L. (1983). Données préliminaires sur la production d’Eichhornia crassipes sur eaux résiduaires (Station d’Epuration de St Gély du Fesc, Hérault, France). Rapp. Comm. int. Mer Médit. 28(6), 365–67. (2) SEAMAN, D.E. & PORTERFIELD, W.A. (1964). Control of aquatic weeds by snail Marisa eornaurietis. Weeds, 12, 87–92. (3) MORRIS, T.L. (1974). Water hyacinth Eichhornia crassipes (Mart.) Solms. : its ability to invade aquatic ecosystems of Paune’s Prairie Reserve. MS Thesis. University of Florida, Gainsville, USA. (4) KIRBY, C.J. & GOSSELINK, J.G. (1976). Primary production in a Louisiana gulf coast Spontina alterniflora marsh. Ecology, 57, 1043–51.

Eichhornia crassipes: production in repeated harvest systems on waste water in the languedoc region (france)

(5) CENTER, T.D. & SPENCER, N.R. (1981). The phenology and growth of water hyacinth (Eichhornia crassipes (Mart.) Solms.) in a eutrophic north-central Florida lake. Aquatic Bot., 10, 1–32. (6) DEBUSK, T.A., RYTHER, T.A., HANISAK, L.D. & WILLIAMS (1981). Effects of seasonality and plant density on the productivity of some fresh-water macrophytes. Aquatic Bot., 10, 133–42. (7) TUCKER, C.T. & DEBUSK, T.A. (1981). Seasonal growth of Eichhornia crassipes (Mart.) Solms.: relationship to protein, fiber and available carbohydrate content. Aquatic Bot., 11, 137– 41. (8) BOYD, C.E. & SCARSBROOK, E. (1975). Influence of nutrient additions and initial density of plants on production of water hyacinth Eichhornia crassipes. Aquatic Bot., 19, 253–61. (9) WOLVERTON, B.C. & McDONALD, R.C. (1979). Water hyacinth (Eichhornia crassipes) productivity and harvesting studies. Economic Bot., 33(1), 1–10.

Research sponsored by Agence Française pour la Maitrise de l‘Energie -(French Agency for Energy Control).

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THE EFFECT OF NUTRIENT APPLICATION ON PLANT AND SOIL NUTRIENT CONTENT IN RELATION TO BIOMASS HARVESTING T.V.CALLAGHAN, G.J.LAWSON, A.M.MAINWARING and R.SCOTT Institute of Terrestrial Ecology, Grange-over-Sands, Cumbria, UK Summary In field trials, bracken (Pteridium aquilinum), Japanese knotweed (Reynoutria japonica) and cordgrass (Spartina anglica) showed little positive yield response to nitrogen, potassium and phosphorus fertilizer application. Tissues analysed contained elevated levels of nutrients but this was not reflected in greater biomass production, which seems to be limited by other factors. Soil N and K levels were depressed in cropped areas of bracken and Japanese knotweed. Soil concentration of P was lower on cordgrass and knotweed sites after annual cropping for three years. Surprisingly the bracken soil did not show a reduction in P level. The lack of response of plants to nutrients is difficult to interpret and it appears that application of nutrients may not give enhancement of yield in some vegetation types. These results highlight the need to investigate further the crop physiology of candidate species for biomass harvesting. Effects of biomass removal on soil fertility will need to be examined in order to construct nutrient budgets. These are often specific to the site and the crop plant.

1. INTRODUCTION Previous papers (1,2) have reported the yield, nutrient content and organic composition of a range of naturally occurring species which could be used as energy crops in the United Kingdom. There would be positive benefits in using certain large areas of vegetation, for example bracken and heather moors, whose amenity and wildlife function would not be adversely affected (3). Biomass cropping from areas of land not previously utilized (here called natural vegetation) and from plantations dedicated to fuel production would remove inorganic nutrients from the site and decrease the soil fertility. We have constructed budgets for the amount of each element that would need to be replaced under different cropping regimes to maintain the desired level of yield (4). However, simple replacement budgets are unlikely to provide the complete answer as many other growth factors are involved. In the case of dedicated energy plantations the high investment in the crop would dictate that high levels of yield should be maintained. This would be less

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important in opportunity crops when fuel production would only be an adjunct to existing management. Other features are linked to the nutrient economy of the plant which it is impossible to consider in isolation. Damage to roots during harvesting, loss of soil surface litter and competition with other plants are all likely to reduce production. Species show different patterns of nutrient use and sites also differ greatly in their potential for holding nutrients (5). An understanding of long term effects is needed to conserve the fertility of soils and to maintain predictable and stable yields, This paper considers species from three contrasting sites. 2. METHODS The sites for bracken and Japanese knotweed were at Lindale, Cumbria and the cordgrass site was at Southport, Merseyside. The Japanese knotweed was transplanted in 1980, the others were naturally established. The same basic design was used. Details have been presented elsewhere (5). Granular agricultural fertilizer (20:10:10, N:P:K) was applied by hand to 6×6m treatment sub-blocks at rates of 0, 0.5, 1 and 2t/ha at the start of the growing season, April for bracken and knotweed, June for cordgrass, timed to avoid spring tides in its coastal habitat. 1×1m samples of aboveground matter were harvested from the centre of 3×3m treatment squares. Fresh weights were performed on whole samples, which were then partitioned when other species were present in measurable amounts. All were dried at 80deg.C. Soil cores were taken to a depth of 5cm. Litter was excluded and drying was at 4–0deg.C. Techniques of chemical analyses for N, P and K were as previously described (5). The split-split plot design results were subjected to analysis of variance. 3. RESULTS Bracken and cordgrass showed a decline in biomass after annual harvests (Figure 1). Yield of Japanese knotweed was the most dependent on nutrients, the species increasing its biomass under annual harvests from an initially low level. In bracken there was evidence that the highest level depressed growth. Evidence from later years of growth under the same cropping regime suggests that climatic variation may have played a part in the decline and that there has been recovery from the low yields found in 1982.

Table I. Soil nutrient concentrations (in % dry weight) in December of unfertilized plots harvested annually for biomass. Year

Bracken Cordgrass Japanese knotweed 1980 1982 1980 1982 1980 1982

Total N 1.85 1.52 0.33 0.32 Extractable P 0.0012 0.0018 0.0051 0.0027 Extractable 0.050 0.032 0.078 0.080

0.40 0.0048 0.0098

0.19 0.0030 0.0062

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K

In the soil, N and P levels showed different patterns in the three sites (Table I). No overall pattern of decline could be seen in the soils to match biomass production but the luxury level of fertilizer applied was ineffective, indeed in the cordgrass site the reduction in soil P was the only detectable effect in unfertilized sites and this had no influence on growth. In addition to the lack of vigour in the annually cut bracken and cordgrass, vegetation change took place. Bracken changed from monoculture to a sparse stand with other species. Similarly cordgrass was yearly less dominant and was being replaced by other saltmarsh plants.

Figure 1. Yield and nutrient content of bracken, cordgrass and Japanese knotweed in growth trials given 4

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levels of fertilizer, over 3 annual harvests. 4. DISCUSSION Yield showed a decline over three years in our trials. In subsequent years a balance is likely to be reached. Annual fluctuation in climate and other habitat factors (6) will give variable productivity. Also, as in the cases of bracken and cordgrass, there may be vegetation change. Repeated cropping would result in a cutting tolerant sward. When establishing energy plantations the aim may be to form a monoculture of the crop species. Weed control, fertilizing and a period without harvests may be needed to achieve good cover. Weedy annuals may be better in this respect than slow-establishing herbaceous perennials. The options in species and habitats in a World context are discussed elsewhere (7). Optimal planting density is difficult to predict. The results of the Japanese knotweed transplant, sown at 4 plants per square metre, showed that this was too low a density. The young plants competed badly with grass and clover in the unfertilized plots and against nettles and thistles in high nutrient treatments. Selective herbicides were largely ineffective because both broad-leaved and grass weeds were present. The problems of establishment have been examined by Pratt et. al. (8). Grasses may have advantages as crops, but there would still be problems with undesirable species, eg. Phalaris and Glyceria in the case of Typha crops. Rootstocks and seed of potential competitors would be difficult to eradicate in the soil. By increasing initial density, perhaps up to 20 plants per sq. metre, the time to close the canopy would be reduced but at much greater planting cost. However, without any help to establish dominance rapidly, some crops would be unable to claim the necessary share of habitat resource, notably soil nutrients. The reasons why nutrient application did not improve yield are unclear. Toxic effects from the 2t/ha treatment are a possibility. Precocious emergence of fronds occurred and it is known that they are prone to frost damage (9). This also happens when surface litter is removed, giving wider temperature extremes at the soil suface, Annual harvests of bracken would prevent the build up of litter. The paradox of lack of growth stimulation on the poor soil of bracken is harder to explain than the failure to enhance growth in the eutrophic cordgrass site, However, nutrients, though often present in high concentrations, may be unavailable to plant roots because of high salinity and lack of oxygen in the soil (10). In Japanese knotweed, only where high levels of nutrients were applied did the young plants make good progress in these annually harvested trials. The presence of underground storage organs of competitor plants will also reduce nutrient availability. Time and frequency of harvest are critical in order to optimize yield and feedstock quality and to reduce the removal of nutrients from sites. For the maintenance of a crop and the reduction of nutrient inputs,the fewer that are removed from sites the better. In the case of combustable fuels the minimum possible N, P, and S emissions would also be an environmental benefit, The detailed understanding of the processes of nutrient cycling in crop species is essential to the development of good management practices. These would have the aim of optimizing yield and conserving the fertility of sites, For instance it is suggested that bracken cropping should be after senescence when the bulk of

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nutrients are withdrawn to the rhizome (2). In bracken it is believed that the recycling process is by internal transport. Other species (eg.Petasites hybridus) rely on decomposition and uptake by roots. The strategy for cropping might take these differences into account. Despite the lack of conclusive effects of nutrients on growth, we found reduced P and N levels in plant tissues on unfertilized sites. The soil level of nutrients was reduced significantly in some cases and the absence of nutrients would hinder the establishment of a new crop, Nutrient rundown could not be sustained without decline in production. This highlights the need to investigate the nutritional requirements and cycling within perennial plants and their response to the perturbation of harvesting. 5. ACKNOWLEDGMENTS This project was funded in part by the United Kingdom Department of Energy and the Commission of the European Communities. The views it contains are those of the authors. We thank the staff of the Chemistry Analytical Service at Merlewood for their painstaking work, also Mr R. Atkinson, Holker Estates, Sefton Borough, Southport and Mr T.Ward of Meathop, Cumbria, for the use of field sites. REFERENCES (1) CALLAGHAN, T.V., SCOTT, R., LAWSON, G.J. and MAINWARING A.M. (1984). An experimental assessment of native and naturalised species of plants as renewable energy sources in Great Britain, In : Energy from Biomass. Vol.5 (Eds W.Palz and D.Pirrwitz) Reidel, Dordrecht. 57–65. (2) LAWSON, G.J., CALLAGHAN, T.V., SCOTT, R.& PROCTOR, A.M. (1983). Biofuels from natural vegetation in the U.K. :the management of novel energy crops. In : Energy from Biomass, Eds. A.Strub, P.Chartier & G.Schleser. 212–221. (2nd E.C. Conference, Berlin , 1982). Applied Science Publishers : London. (3) CALLAGHAN, T.V., LAWSON, G.J. and SCOTT, R. (1982). Bracken as an energy crop? In : Solar World Forum (Eds. D.O.Hall and J.Morton) Pergamon, Oxford. 1239–1247. (4) CALLAGHAN, T.V., SCOTT, R. & WHITTAKER, H.A. (1981). The yield, development and chemical composition of some fast-growing indigenous and naturalised British plant species in relation to management as energy crops. 178pp. Report to U.K. Dept. of Energy. ITE: Cambridge. (5) CALLAGHAN, T.V., SCOTT, R., LAWSON, G.J. & MAINWARING, A.M. (1984). An experimental assessment of native and naturalized species of plants as renewable souces of energy in Great Britain. IV. Energy Crop Nutrition. 28pp. Report to U.K. Dept. of Energy. ITE: Cambridge. (6) COOPER, J.P. (1982). Photosynthesis and energy conversion. In: Energy management and Agriculture. Eds. D.W.Robinson & R.C.Mollan. 105–118. Royal Dublin Society: Dublin. (7) CALLAGHAN, T.V., LAWSON, G.J., MAINWARING, A.M.& SCOTT, R. (1985) The Potential of Natural Vegetation as a Source of Biomass Energy. This Volume: Energy from Biomass. Venice: 3rd EC Conference. (8) PRATT, D.C., DUBBE, D.R., GARVER, E.G. & LINTON, P.J. (1983). Wetland Biomass Production: Emergent aquatic management Options and Evaluations. Bioenergy coordinating office. University of Minnesota.

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(9) LOWDAY, J.E. MARRS, R.H. & NEVISON, G.B. (1983). Some of the effects of cutting bracken (Pteridium aquilinum) at different times during the summer. J. Environ. Manage. Vol. 17:373–380. (10) MORRIS, J.T. (1980). The Nitrogen uptake kinetics of Spartina alterniflora in culture. Ecology. Vol. 61:1114–1121.

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uptake through the roots in willow and sunflower and effect of uptake on the productivity of willow cuttings P.Pelkonen, E.M.Vapaavuori and H.Vuorinen The Finnish Forest Research Institute, Suonenjoki Research Station, SF-77600 Suonenjoki, Finland Summary Young willow (Salix ‘aquatica gigantea’) and sunflower (Helianthus annuus L.) plants were grown in hydroponic culture media, and 14Clabelled sodium bicarbonate was fed to the roots. Uptake of 14C-label in the leaves and shoots was assayed after two different feeding periods (6h, 48h). Even during the shortest feeding period, 14C-label had been transferred to the leaves and shoots. A second experiment was designed to test whether carbon uptake by the roots affects the growth of young willow plants. Rooted cuttings were grown in hydroponic cultures at five different levels of bicarbonate: 0, 0.015, 0.147, 0.737, and 1.473 mM NaHCO3. After a 4-week growing period we determined the biomass of leaves, shoots, roots and cuttings. Production of total dry matter (shoots, leaves and roots) increased with increasing bicarbonate concentration. Saturation of dry matter production was reached at 0.737mM NaHCO3, but a higher concentration of NaHCO3 (1.473mM) caused a slight decrease in the dry matter production.

1. INTRODUCTION In rapidly decomposing soils the concentration of CO2 can be markedly higher than that in the atnosphere, from 0.5 to 1.5% by volume (1). Part of this CO2 equilibrates with the water of to produce carbonic acid, which further dissociates to proportions of the ionic species depends on the pH.

and

The relative

Many aquatic plants and algae are able to take up both and CO2, which obviously could make them photosynthetically more competent(2). In bean plants, uptake of bicarbonate was detected using 11C as a tracer with a decreasing gradient of label from roots to leaves (3). Several reports have indicated that high concentrations of bicarbonate (from 5 up to 20mM) in soils and irrigation waters inhibit uptake of other nutrient ions and decrease crop growth (4, 5,). These high concentrations, reported for example in strongly anaerobic conditions in rice fields (6), are unlikely to occur in normal soils.

HCO3 uptake through the roots in willow and sunflower and effect of HCO3 uptake of willow cuttings

The purpose of this experiment was to test, using radiotracer studies in hydroponic cultures, whether willow and sunflower plants take dissolved CO2 from nutrient solution and whether the availability of dissolved CO2 at low concentrations in the medium would affect growth and biomass produetion of young willow plants. 2. MATERIAL AND METHODS 2.1 NaH14CO3 feeding experiment Cuttings of willow (Salix ‘aquatica gigantea’) that were about equal in length and diamster were selected for the experiments. The cuttings were rooted in deionized water for about two weeks and then transferred to a nutrient solution (7), pH 5.5, for the experiments. Seeds of sunflower (Helianthus annuus L.) were sown in washed sand. At the cotyledon stage the plantlets were transferred into the above nutrient solution, pH 7.0, for further growth and for the 14C uptake experiment. Using a rubber stopper, the plants were tightly sealed into 300ml flasks with a small inlet for aeration of the solution with CO2-free air. The outgoing air was led into a CO2-trap (20ml of 2-ethoxyethanolethanolamine mixture 7:1). Before the experiment, plants for 8 different treatments were incubated for 3 days in the nutrient solution with either 0.015mM NaHCO3 (treatments 1 to 4) or 1.473mM NaHCO3 (treatments 5 -to 8). After this incubation period, 3–604µM of either unlabelled or 14C labelled NaHCO3 (NaH14 CO3 53.5mCi/mmol, The Radiochemical Centre, Amersham) was injected into the medium. After the 6 and 48h feeding period the shoots were cut into pieces; each sample contained one leaf with the internode below. Fresh and dry weights of the samples were measured, after which they were treated with 20ml of 5N HCl to free the inorganic carbon compourds from the plant material as CO2. The evolved CO2 was trapped into 20ml of 2-ethoxyethanol-ethanolamine mixture (7:1). The acid treated plant materials were collected on filter papers and washed twice with 5ml of distilled water, after which the samples were dried and finally burned in a combustion chamber. Radioactivities of the combusted samples were measured with a liquid scintillation counter (LKB Wallac 1215 Rackbeta Liquid Scintillation Counter). Samples of the 2-ethoxyethanolethanolamine mixture and of the acid with washings were taken for radioactivity measurements on a liquid scintillation counter (LKB Ultrobeta 1210). 2.2 Effect of carbon uptake on productivity Rooted willow cuttings of equal size were selected for the experiments. Rooting conditions were as in the 14C feeding experiment. The cuttings (7 cuttings for each treatment) were transferred into Erlenmeyer flasks and cultivated in 275ml of the nutrient medium (7) in a greenhouse. To prepare a CO2-free nutrient medium the solution was boiled for 30 min and then tightly stoppered. The pH of the cooled media was rapidly adjusted to 7.00, 7.00, 6.90, 6.70 and 6.40 in Treatments 1,2,3,4 and 5 respectively. The media were aerated with OC2-free air for 30 rain. NaHCO3 was then added to the media to bring the pH of the media to 7 and the NaHCO3 coccentration in Treatments 2,3,4 and

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5 to 0.015mM, 0.147mM, 0.737mM and 1.473mM, respectively. Treatment 1 served as a control. The nutrient media were changed every 2 days during the 24-day experiment. After 2 days in all the treatments the pH of the media decreased to pH 6.4. During the growing period, daylight was supplemented with Osram HQ1 400 W-71 lamps to give a photoperiod of 18h and an air temperature between 20 and 15 ºC. After the 24-day growing period, the plants were harvested for determination of the fresh and dry weights of leaves, shoots, roots and cuttings. 3. RESULTS AND DISCUSSION 3.1 NaH14CO3 feeding experiment The 14C label was detected in the leaves and shoots of willow and sunflower in both preincubation treatments even after a 6h feeding period (Table 1). Our results with willows thus confirm the data for beans and Galenia pubescens (3) and show that HCO3− moves from the soil into the shoot and leaves. The rate of HCO3−-uptake with willow and sunflower was dependent on concentration, since incorporation of 14C label, calculated both on the basis of fresh as well as dry weight, was higher in treatments preincubated at 1.437mM NaHCO3 than at 0.015mM NaHCO3. After the 6 h feeding period, most of the 14C label was found in acid-labile products. Incorporation of the label through the metabolism into the acid-stable products was time dependent, which could be seen as a higher percentage of the label in acidstable products after the 48h treatments (Table 1).

Table 1. Rate of 14C uptake during 6h and 48h feeding periods in leaves and shoots of willow and sunflower plants at two concentrations of NaHCO3. NaHCO3, concentration during preincubation mM

willow 0.015 0.015 1.473 1.473 sunflower 0.015 0.015 1.473 1.473

Duration of 14C 14C fixed in % of 14C fixed feeding h leaves + shoots nmol g−1 dw in acid labile in acid stable h−1 products products 6 48 6 48

6.93 1.51 1239.69 184.96

41.4 21.0 60.8 36.4

58.6 79.0 39.2 63.6

6 48 6 48

27.50 8.33 1895.33 530.50

74.0 37.1 71.7 52.6

26.0 62.9 28.3 47.4

Our 14C labelling data does.-not, however, allow us to determine what proportion, if any, of the 14C label in the acid-labile and acid-stable products was derived from the HCO3−-

HCO3 uptake through the roots in willow and sunflower and effect of HCO3 uptake of willow cuttings

molecules transported to the site of synthesis in the shoots. Malate, which is thought to be formed in the roots by PEP carboxylase and/or PEP carboxykinase (8), may be decarboxylated again; and in this case the evolved CO2 molecules would be transported to the site of synthesis in the shoots. 3.2 Effect of carbon uptake on productivity Results from the experiment in which willow cuttings were grown in cultures with different concentrations of NaHCO3 show that the dry matter production of the whole plant (shoots, leaves and roots) inereased by 31–1% in culture medium with 0.737H NaHCO3 and that even at the highest NaHO3 concentration (1.473 mM) the biomass production was higher than in the control plants (26.8% increase in dry weight, Fig 1.). The same trend was found separately in the dry matter production of leaves and shoots. In the roots such an effect of NaHCO3 on the dry matter production was not obvious, and at 1.473mM NaHCO3 the dry weight increased only slightly (results not shown).

Fig. 1. Effect of different concentrations of NaHCO3 in the culture media on the dry matter production of whole willow plants (shoot, leaves, roots). Individual data points and the mean values f or each treatment are shown 1=0mM, 2=0.015mM, 3=0.147mM, 4=0.737mM and 5=1.473 mM NaHCO3.

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Our data with willow strongly suggest that the availability and uptake of through the roots is beneficial for growth of the plants at NaHCO3 concentrations about 50–100 times the concentration of CO2 dissolved in water at ambient CO2 pressure at 25°C. Depending on the source of the—

ions taken up by the roots from the soil, the effect of their

uptake on plant productivity and carbon budgeting might differ markedly. If the ions incorporated into the plant arise from decomposition of organic matter other than the plant itself, this uptake would result in a net carbon gain.

Fig. 2. Liquid consumption during the 24-day experiment in willows grown in media with different NaHCO3 conc. 1=control; 2=0.015 mM; 3=0.147mM; 4=0.737 mM; 5=1.473mM. The path of carbon through the roots to the sites of synthesis in the stems and leaves is difficult to trace. Our data with willows show that in plants grown in the culture media with the highest NaHCO3 concentrations, which caused increased productivity, transpiration was highest, even though in the beginning of the 24-day growing period all treatments had similar rates of liquid consumption (Fig. 2). The average water consumption in plants varied from 800 to 1000g during the 24-day growing period. From this data we have calculated that with the highest NaHCO3 concentration the amount of carbon flow from the culture media into the shoots and leaves was about 1.2% of the total amount of carbon in the plants. Let us consider the effects of carbon supply with two different concentrations as percentages p1 and p2 (p=p1–p2). If the initial dry weight of the substances available for growth in plants is Wo

HCO3 uptake through the roots in willow and sunflower and effect of HCO3 uptake of willow cuttings

and dry weights at the end of the growing period W1 and W2, the ratio of dry weights (x=W2/W1) can be calculated according to the following formula:

Fig. 3. Dry weight ratio (×) as a function of relative growing time ((W2/Wo)−1) using three different values for p (p=difference in the carbon concentration). The values of dry weight ratio (×) as a function of relative growing time ((W2/Wo)−1) using three different values for p have been presented in Fig.3. These theoretically calculated figures confirm our experimental data. Thus the CO2 molecules taken up by the roots and transported to the site of synthesis in the shoots have an increasing effect on the productivity of willow plants. REFERENCES (1) Larcher, W. (1975) Physiological Plant Ecology. Springer-Verlag, Berlin, Heidelberg, New York. 252 pp. (2) Lucas, W.J. (1983). Annual Review of Plant Physiology, 34, 71–104. (3) Wallace, A., Mueller, R.T., Wood, R.A. & Soufi, S.M. (1979) . Plant and Soil, 51, 431–435. (4) Paliwal, K.V., Maliwal, G.L. & Nanawati, G.C. (1975). Plant and Soil, 43, 523–536. (5) Andel, J. van, Bos, W. & Ernst, W. (1978) New Phytologist, 81, 763–772. (6) Yoshida, S. & Tanaka, A. (1969) Soil Sciences and Plant Nutrition, 15, 75–80.

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(7) Arnon, D.I. & Hoagland, D.R. (1943) Botanical Gazette, 104, 576–590. (8) Popp, M., Osnond, C.B. & Summons, R.E. (1982) Plant Physiology, 69, 1289–1292.

CONTROLLED ENVIRONMENT GROWTH OF EUPHORBIA LATHYRIS IN RELATION WITH TEMPERATURE AND WATER STRESS P.VENTAS, J.L.TENORIO, E.FUNES and L.AYERBE . Fisiología. Instituto Nacional de Investigaciones Agrarias Apdo. 8.111 Madrid-Spain Summary Some experiments have been carried out, in controlled environment cham bers, to know the growth response of Euphorbia lathyris, in relation—with temperature and water stress. Four temperatures were tried out:—26, 21, 16 and during the day; night temperatures were five or—ten degrees lower. Plants were sown in pots with a soil composed by a mixture of peat and sand. Controls were irrigated, whenever necessary, to maintain the soil at field capacity, other treatments suffered di—fferent degrees of water stress. The optimum temperature for shoot—growth was , being somewhat lower for root development. Leaf water potential decreased with progressive water stress, but never went below −17 bar, showing this species a drought avoiding pattern. According—with that behavior, growth measured as dry matter production and as—leaf area index, was very much restrained in stressed plants, further—more, leaf diffusion resistance increased, favouring the maintenance—of a good water status. Water stress induced a greater amount of sugars to be accumulated in the plants, specially in stems, although it did—not increase hydrocarbon contents.

1. INTRODUCTION In the last years some studies have been developed in order to evaluate Euphorbia lathyris as an energy crop (1, 2, 3, 4), but few if any, have been devoted to analyze this species growth in a controlled environment. So we—have tried to evaluate the effect of temperature and water stress, on the—growth pattern and dry matter production of this plant, cultivated in pots—in a climatic chamber.

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2. MATERIALS AND METHODS We made two experiments (I and II), in the first one, four day temperatures were tried (night temperatures were lower in each case), day and night out: 26, 21, 16 and length were 12 hours each, relative humidity—was 72±5% during the day and 86±5% during the night. Photosynthetic acti ve radiation (PAR), was 317µ E m−2 s−1, measured at the top of the plants. Soil was a mixture of peat and sand (3:1, V:V), the soil had been previously calibrated by means of a pressure membrane to know its humidity content at—field capacity (CC=1/3 bar), and in the permanent wilting point (WP=15 bar). Forty pots (11,5dm3 capacity, one plant per pot), were assayed for—each temperature, half of them were permanently maintained at CC whereas to the other half, a progressive water stress was imposed, adding no water for the whole experiment (18 weeks). Fresh and dry weight (DM), and height of—the plants were measured periodically. Leaf diffusion resistance (RD) and leaf water potential (LWP), were also measured on leaves from the fifth or sixth verticil, counted from the youngest, completely open leaf. Critical saturation deficit, was also evaluated on leaves. Total sugar contents and hydrocarbons were evaluated at the end of the experiment (5, 1). In experi ment II, the effect of different degrees of water stress on plant growth—was investigated. Day (12 hours), temperature was , the best one in—the previous experiment; night (12 hours), temperature was . Soil was a mixture of peat and sand (1:3, V:V): The other environmental conditions were the same as in experiment I. All the plants, as in experiment I, star ted with soil at field capacity, then the next three different irrigation treatments, were given to groups of twenty plants (one per pot), for 19—weeks: a/ The soil was maintained at CC for the whole experiment. b/ Soil was brought to CC whenever, available water went below five per cent. c/ Not irrigated; (available water was depleted by the 12th week; available water: water at CC minus water at WP).

3. RESULTS AND DISCUSSION Experiment I. According with soil calibration data, available water in stressed plants was , by week 13th at and by week 17th at . depleted by week 11th at 26 and Plants at field capacity, at any temperature (except ), grew better than plants, at the same temperature, under stress (fig. 1 a, b and c). Twenty one degrees centigrade was the best—treatment for shoot growth, reaching the plants 91cm mean height and 40g mean dry weight, per plant, at the end of the experiment. Leaf area index (LAI), at CC and was always higher than others with the same water—regime, but different temperature, reaching at week 17th a value of 4.4; at the same time, well irrigated plants, at , showed a LAI of 3.8—(fig. 2a). Leaf area indexes for stressed plants were much lower, compa—red, with well irrigated ones, and never reached a LAI value of one (fig. 2b). On week 17th, the best root dry matter yield was for plants at , that reached 17.7g DM per plant at CC , and 4g DM per plant under stress. Leaf diffusion resistance was almost always, lower in plants at CC than in stress, and grew higher with time in the last ones, going higher than 30 s cm−1 in plants at 26 and . Lef diffusion resistance values at CC remai ned more or less constant until the end of the experiment (fig. 1).

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Leaf—water potential never went below −10.5 bar in irrigated plants and −17 bar in stressed ones (fig. 1b). Critical saturation deficit, for leaf disks,—was 41%, this means that E. lathyris can be considered as a xerophytic mesophyte plant (6). Hydrocarbon content (week 17th), was significantly (P= =0.01), higher in leaves: 7.9% of DM, than in stems: 3.1%. Mean hydrocar bon content for the whole plant was 5.4% There was no significant differen ce, neither for different temperatures, nor for water stress treatments.—Other fraction containing also hydrocarbons, that according to Nemethy (1) can amount to 3% of the total dry matter, was not evaluated. Sugar content was significantly (P=0.01), higher in stressed plants: 10.5% of the dry—matter, than in irrigated ones: 5.8%. Sugar in stems of unirrigated plants was also significantly (P=0.01), higher: 13.2% compared with the leaves content: 7.8%. Experiment II. Growth of plants permanently cultivated at CC (treat ment a), was not significantly different from that of plants stressed until only 5% of the available water was left (treatment b). Maximum mean height and dry weight of plants from treatments a and b, were 83cm and 18g per plant respectively, at the end of experiment II, these values, are lower—than the corresponding in experiment I, at and CC, this was probably— due, to the decrease in night temperature in the last assay. In the treatment c, the final dry weight was only 3.3g per plant. Leaf diffusion resis tance did not go higher than 4s cm−1 in treatment a, and 6 s cm−1, in b;—but in the not irrigated treatment (c), RD reached 32s cm−1 in the last—week. Leaf water potential was not significantly different for the three—treatments (a, b and c), being the lowest registered value: −14.5 bar (c). Hydrocarbon contents did not differ from those obtained in experiment I. The amount of sugars was also in this experiment significantly (P=0.01)—higher in stressed plants (c): 8%, compared with well irrigated ones (a):—6.6%, and it was also higher in stems: 9.9%, than in leaves: 6.5%, the two last values are mean of a, b and c treatments . From all the above data, we can conclude that is the best tempera ture for shoot growth, although somewhat lower seems better for root deve—lopment. The combination (day/night), enhances also shoot growth—verus 21/ . As was expected, 21/ plants at CC grew better than stressed ones (experiments I and IIC), nevertheless, apparently medium stressed plants,—from experiment IIb, did not decrease their DM production compared with plants constantly maintained at CC, this fact was probably due to the low—evaporative demand of the environment, due to high air relative humidity,— and perhaps because the roots thrive better in a well drained soil. It can be said that E. lathyris has behaved as an extremely drought avoiding plant, as the lowest leaf water potential never went below −17 bar (fig. 1b). To—this pattern, we think has contributed mainly the growth restraint exhibi—ted by stressed plants (fig. 1a, b and c). Leaf area indexes were also much lower in stressed than in well irrigated plants (fig. 2a, b). Finally, leaf diffusion resistance also increased with progressive stress (fig. 1a, b), and differences found between well irrigated and stressed treatments showed at least the same degree of sensitivity as differences between dry matter—production in wet and unirrigated treatments (fig. 1a, b and c). Plants grown at suffered a negligible water stress (available water was not—depleted until week 17th), and leaf diffusion resistance and water poten—tial values were alike in wet and dry treatments; in this case, low DM production, must be mainly atributed to a deficient temperature. It is also—interesting to notice that water stress, in the assayed conditions did not increase hydrocarbon, but almost doubled sugar contents.

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REFERENCES (1) NEMETHY, E.K., OTVOS, J.V., and CALVIN, M. (1981). Hydrocarbons from Euphorbia lathyris. Pure and Appl. Chem. 53, 1101–8. (2) KINGSOLVER, B.E. (1982). Euphorbia lathyris reconsidered: Its potential as an energy crop for arid lands. Biomass, 2, 281–98. (3) SACHS, R.M. et al. (1981). Euphorbia lathyris: A potential source of petroleum-like products. Calif. Agric. 35, 29–32. (4) AYERBE, L. et al. (1984). Euphorbia lathyris as an energy crop-Part 1. Vegetative matter and seed productivity. Biomass, 4, 283–93. (5) YEMM, E.W. and WILLIS, A.J. (1954). The estimation of carbohydrates in plant extracts by anthrone. Biochem. 57, 508–14. (6) STREET, H.E. and OPIK, H. (1970). The physiology of flowering plants: Their growth and development, 236 p. Edward Arnold Publishers London.

Fig.1. Leaf diffusion resistance (•—• Soil at field capacity (CC .—. Soil under stress(st); Leaf water potential(◦—◦(CC), ◦—◦ (st)) and Shoot dry weight (+—+(CC),+—+(st) a=26ºC , b=21ºC, c=16ºC , d=11ºC

Controlled environment growth of euphorbia lathyris in relation with temperature and water stress

Fig.2 Leaf area Index (•—• =26°C, o— o =21°C, +—+ =16°C, ■—■=11°C). a: Soil at field capacity. b; Soll under stress.

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MICROPROPAGATION OF WILLOWS (SALIX SPP.) T.TORMALA and E.SAARIKKO Kemira Oy, Espoo Research Centre PO Box 44, 02271 Espoo, FINLAND Summary In the context of a breeding and testing program for short rotation biomass production of willows, 16 genotypes were micropropagated using a modification of Bhojwani’s (4) method. The method can be simplified using same medium for initiation and proliferation phases and rooting the microshoots directly into soil in vivo.

1. INTRODUCTION The energy crisis in the early 1970’s launched many national and private short rotation energy forest programs. While in relatively few places the projects have resulted in large scale production, the interest in short rotation forestry has sustained and even broadened in scope. In addition to burning other alternatives such as landscape reclamation, production of biomass for pulp and feed stocks for chemical industry have received increasing interest. Willows (Salix spp.) are most promising species for short rotation forestry together with alders (Alnus spp.) and poplars (Populus) in the temperate zone. Salix is taxonomically and ecologically an extremely diverse genus offering an almost unlimited source for breeding and genetic improvement in general. The propagation and planting of most willows is easy using cuttings. The procedure can easily be mechanized. If so, one may ask, what are the incentives for using tissue culture propagation in willows? With micropropagation desired genotypes can be bulked up rapidly for cutting production. Secondly, plantlets are more uniform and practical than cuttings in tests, especially in the laboratory environment. In this paper we describe our experiences in willow micropropagation which has been directed toward genotype improvement and field testing for short rotation forestry in mined peatlands in northern Finland. 2. MATERIALS AND METHODS The following clones were used in the experiments: S. dasyclados 3 clones (V761, P6011, 196), S. aquatica (E4856), S. viminalis 2 clones (S15111, E7899), S. myrsinaifolia (V78), S. dasyclados H3159×trinadra P6010 (V777), S. purlamb H3172×S. aquatica V768 (V778), S. dasyclados H3159×, S. aquatica E4856 (V779), S. viminalis

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H3157×aquatica E4856 (V780), S. viminalis H3157×S. caprea E6762 (V781), S. viminalis H3157× aquatica E4856 (V782), and S. viminalis H3157×smithiana H3163 (three clones V783, V784, V785). Disinfestation was achieved by dipping the explants in 70% ethanol for 30 seconds, prior to soaking in 3% sodium hypochlorite for 15–20 min. (a few drops of detergent added) and finally rinsing four times in sterile water. Two kinds of explants were used: shoot tips from soft vegetative growth and single node segments from hard wood cuttings (ca. 2.5cm long). The basal media tested were MS (1), half strength MS and woody plant medium (WPM) (2). No6-benzyladenine (BAP) and 1-naphthalenacetic acid (NAA) were applied in different concentrations. The cultures were incubated in growth chambers (L:D 16:8h, Temp. 25°/18°C). The light intensity was ca. 2000 lux. 3. RESULTS AND DISCUSSION The success of surface sterilization depended highly on the source of explant. Using greenhouse stock plants, which had not receive overhead watering, a 95–100% rate of disinfestation was obtained. When material from the field was used the disinfestation procedure applied was not satisfactory. The use of excised buds as explants would probably have given better results (3). Of the three tested basal media WPM gave the best general response in initiation and multiplication phase (Table 1). The results were, however, dependent on the clone. There were no striking differences between the response of shoot tips and lateral buds.

Table 1. Percentage of single node explants, which developed into a 2–3cm shoots after (12–21 days) in vitro. BAP treatments (0.05, 0.2 and 0.5mg/l) pooled. N=18 % transferred for multiplication Clone 1/2 MS MS WPM 777 778 779 780 785 E4856

88 11 50 17 38 45 41

78 22 55 5 28 62 42

83 28 50 38 67 45 52

83 20 52 20 44 50

Three levels of BAP were tested in an experiment. It seems that optimal concentration is ca. 0.1–0.2mg/l for most clones (Table 2). No significant interaction between the basal medium and the growth regulators could be observed. The time elapsed from the initiation of the culture to the transfer of ca. 3-cm long shoots depended primarily on the genotype. The cytokinin level alone did not have any consistent effect on the bud break.

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A small amount (0.05 mg/1) of NAA in addition to the BAP enhanced the bud break slightly in some clones (e.g. P6011, V761). The shoot proliferation was best on a similar medium as in initiation (BAP 0.1– 0.2mg/l with/without 0.05mg/l NAA). Especially, in the presence of NAA, roots often developed in this phase. The multiplication rate was 1.5–5.0 depending on the clone. Similar rates have been obtained by other authors (3, 4). Most of the clones rooted well in vitro (basal medium, 0.1 mg/1 NAA) and in vivo in greenhouse. E4856 and V782 were hard to root. E4856 does not root well from the cuttings in the field, either. The proliferation of E4856 is poor, too, and probably a single node culture (3) could be better for this genotype. In 1984 all plantlets (ca. 450) grown in greenhouse a height of more than 5cm survived in the field.

Table 2. Effect of BAP concentration on the bud break of single node segments. Data from 1/2 MS, MS and WPM pooled. N=18 % transferred for multiplication Clone 0.05 BAP mg/1 0.5 0.2 777 778 779 780 785 E4856

88 28 30 22 50 66 52

88 12 50 33 55 72 52

72 22 45 5 28 12 30

CONCLUSIONS 1. Well fertilized (5) greenhouse grown stock plants not watered from above are preferable to field material as sources of explants. 2. Buds in large (2–3cm) single node explants develop into shoots that can be transferred faster than excised buds (3) or small bud explants (3, 5) without the stem. Some of the shoots can be transferred in fact already after one week and most in two weeks. 3. The same media can be used both for initiation and multiplication (BAP 0.05–0.2mg/l with/without 0.05mg/l NAA). 4. Most genotypes can be rooted directly e.g. in peat-sand mixture in the greenhouse in high humidity. The hardened plantlets can be transferred into the field when they are at least 5cm tall. ACKNOWLEDGEMENTS Dr. Stephen Garton kindly commented on the manuscript.

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REFERENCES (1) MURASHIGE, T. and SKOOG, F. (1962). A revised medium for rapidgrowth and bioassays with tobacco tissue culture. Physiol. Plant 15:473–497 (2) LLOYD, G. and MCCOWN, B. (1981). Commercially feasible micropropagation of mountain laurel, Kalmia latifolia, by use of shoot tip culture. Comb. Proc. Intern. Plant Prop. Soc. 30:421– 427 (3) BERGMAN, L.v. ARNOLD, S. and ERIKSSON, T. (1984). Culture of Salix species in vitro. Energy Forestry Project. Uppsala, Sweden, Report 36 (4) BHOJWANI, S.S. (1980). Micropropagation method for a hybrid willow (Salix matsudana×alba N2–1002). New Zealand J. Bot. 18:209–214 (5) GARTON, S., READ, P.E., FARNHAM, R.S. (1983). Effect of stock plant nutrition on macro and micropropagability of Salix. Acta Hort. 131: 141–151

THE USE OF PHOTOINTERPRETATION FOR BIOMASS EVALUATION AND POSSIBLE BIOMASS RECOVERY IN AN AREA OF THE LOMBARDY REGION P.Bonfanti, C.Semenza, Institute of Agricultural Engineering University of Milan Summary Survey methods were developed and improved to evaluate biomass amount and distribution starting from the survey of a limited area as a basis for factual considerations giving sound support to future feasibility studies. To assess the available biomass, data gleaned from the official statistics were checked against those obtained by photointerpretation. A suitable data acquisition methodology based on aerial photography was developed: the territory was broken down into homogeneous zones and some sample municipalities were selected for photointerpretation. Further checks were executed at ground level to identify the crops and evaluate their yield. These data were used to assess the amount of biomass available for energy conversion. The feasibility of using such biomass and installing energy recovery facilities was also evaluated, and the short-range limit defined.

FOREWORD AND SCOPE OF RESEARCH Lately, several projects were conducted in Italy at national (CNR) and regional (Lombardy, Piedmont, Emilia-Romagna, etc.) level to obtain reliable data on the amount and distribution of biomass for energy conversion. However, these projects covered rather wide areas and only yielded approximate data, since the official data are scanty and the available ones are not sufficiently disaggregated. The scope of this study, which was conducted on a subregional scale, is to set up and verify methods based on aerial photography. The area selected for the study is farmland of some 800 km located south of Milan, in the Lodi district.

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METHODOLOGY The area of the survey was subdivided Into six homogeneous zones (Fig.1) based on statistical and bibliographic data, and from indications obtained from locally available black-and-white photographs, enlarged to an average scale of 1:10,000.

Fig. 1

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Within the six zones, some municipalities were randomly selected for photointerpretation by aerial colour photography, average scale 1:20,000 (1980 flight, Lombardy Region). The classification aimed at identifying crops yielding byproducts usable for energy conversion (maize and grain cereals). The relevant areas were measured and the result was extrapolated to the whole territory. Any swine or cattle farm in each municipality was identified on the photographs to double check information obtained elsewhere (statistical data, veterinary offices, etc.). After evaluating the farmland area, the amount of available byproducts was obtained by applying some indices that account for crop yield, feasibility of mechanical residue collection and current uses of such residues. In a similar way, the amount of animal waste was estimated from herd size data, through suitable conversion indices. RESULTS Table 1, 2 contain the values obtained by photointerpretation against those from other sources (official data, local surveys and our calculations). As concerns livestock, the data obtained from the aerial photographs roughly agree with those obtained from the local authorities. Some minor differences in the number of cattle farms are to be ascribed to difficult identification of the smaller farms (with fewer than 20 head of cattle) where no identifiable facilities (silos, manure pits, haylofts, etc.) are evident in the photograph. Significant discrepancies were found instead in farmland area data, further proof of the difficulty of extracting reliable, updated information from the official statistics. Fig.2 shows the evaluated available vegetal byproducts and livestock data, both referred to one hectare of farmland in the six zones. These calculations were made to assess the amount of available biomass for energy conversion by suitable means—in our case, combustion for ligno-cellulosic residues and anaerobic digestion for animal waste—and to determine whether the required facilities can be installed in the area under consideration. Cereal straw and maize cobs were considered for combustion (the latter, when mechanised collection is feasible). Maize stalks instead, owing to their high moisture content (>50%), fair nutritional value and on account of the locally prevalent crop patterns, are preferably used as fodder. As concerns anaerobic digestion, simplified systems are certainly suitable for small farms; however, because of scale economies, the current economic threshold for swine farms lies around 3–4,000 head. For inter-farm or pooled facilities, any solution where the animal farms are more than 500m away from the processing facility is economically unsound. For vegetal byproducts, the economic threshold depends on their market price (if any), or replacement value (as fodder, fertilizer etc.). This value should in any case be compared with the recovery cost in economic and energy terms to determine the maximum utilization range, which was determined in 8km for cereal straw under the average conditions prevailing in the surveyed region.

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REFERENCES (1) NATALICCHIO E., SEMENZA C. (1981). Possible production, recovery techniques, present and alternative uses of agricultural byproducts. CNR—Progetto Finalizzato Meccanizzazione Agricola. Quaderno n°23. (2) PELLIZZI G. (1984). First comparative energy analysis of some biomass energy conversion process. Rivista di Ingegneria Agraria. Anno XV, n°2.

Table 1—Land breakdown by main crop, Lodi district: Comparison of data from various sources (ha) CROP

STATISTICAL DATA(1)

ESTIMATED DATA(2)

PHOTOINTERPRETATION DATA(3)

Wheat 9,772 7,329 Grain barley 1,417 1,785 Rice 661 659 Grain maize 13,145 13,697 Forage crops 33,791 35,229 Wood crops, 4,789 4,789 forest, nurseries Other 3,845 3,719 Tare 3,592 3,592 Total, farmland 71,012 70,799 & woods (1) Lombardy Region, 1978 (2) 1980 estimated data, based on 1978–80 percent. variations over the whole province of Milan (3) Aerial photographs, Lombardy Region, 1980.

14,661.53 682.25 22,601.48 28,779.47 3,661.43 n.a. n.a. 70,386.162

Table 2—Cattle and swine farms in the sampled municipalities: Comparison of data from various sources STATISTICAL DATA ZONES CATTLE SWINE FARMS (1) FARMS(2) (No.) (No.) ZONE A ZONE B ZONE C ZONE D ZONE E ZONE F

TERRITORIAL DATA (3) CATTLE SWINE FARMS FARMS (No.) (No.)

PHOTOINTERPRETATION DATA (4) CATTLE SWINE FARMS (No.) FARMS (No.)

21

8

16

3

20

7

39 15 31

19 3 7

20 9 14

5 4 8

30 8 30

6 4 11

81 89

13 15

53 22

19 8

59 41

21 14

Energy from biomass

(1) UNIONCAMERE-Lombardy, 1980 (2) Lombardy Region, 1978 (3) Lodi District Survey, 1980 (4) Aerial photographs, Lombardy Region, 1980.

Fig. 2

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PHOTOSYNTHETIC SOLAR ENERGY CAPTURING IN A CROPPING SYSTEM WITH EXTENSIVE EXPLOITATION OF BIOMASS FOR FUEL PRODUCTION J.Zubr The Royal Veterinary and Agricultural University Copenhagen, Denmark Summary A cropping system designed for maximum capturing of solar photosynthetic energy by field crops has been under evaluation for three years. The capacity of crops to capture PAR was measured by LAI and by the production of TS. The biomass of selected crops has been investigated as a source of substrate for bioconversion into alcohol and biogas. Batch alcoholic fermentation of sugar beet (BETA VULGARIS) roots, Jerusalem artichoke (HELIANTHUS TUBEROSUS) tubers and potato (SOLANUM TUBEROSUM) tubers was performed in the laboratory at 30°C for 72 hrs. Prior to the fermentation, potato mash was liquefied and saccharified by the enzyme THERMAMYL and AMG NOVO and as a variable treatment for all materials a specific enzyme SP 249 NOVO has been applied. The fermentation has been carried out by the use of an alcoholic strain of SACCHAROMYCES CEREVISIAE. Maximum yield of alcohol 0.53l/kg TS was achieved from sugar beet roots pretreated with the enzyme SP 249 NOVO. Methanogenic fermentation of crop residues has been carried out in the laboratory using batch system fermentation reactors operating under mesophilic conditions (35°C). From selected raw materials the highest yield of biogas 638l/kg VS added and the highest yield of methane 451l/kg VS added was obtained from ensiled cabbage (BRASSICA OLERACEA var. Capitata) leaves. When an extensive exploitation of the biomass for fuel production was considered, the gross energy yield of 251.555GJ/ha in the form of alcohol and methane produced from sugar beet roots and top, respectively, was the maximum achieved under the above experimental conditions.

1. INTRODUCTION During the last decade in Danish agriculture about 60% of the arable land has been used for growing grain crops such as barley, wheat, rye and oats (1). This large percentage of grain crops enforced new practices in agricultural management making crop rotations

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one-sided. The specialization has led to development of an excesive production capacity contributing now to the surplus stock of grains. This controversial situation requires new strategies for the planing of crop production in the near future. At the same time, the economics forces development in the direction of efficient production while ecological considerations demand sustainable cropping systems safeguarding the environment. In future cropping systems which should be both economically and ecologically justifiable, the crop structure is to be adapted to the local climatic and soil conditions. Anyhaw, the maximum photosynthetic energy capturing by the crops remains still the primary demand. In this respect, long term crops with a high photosynthetic capacity, producing a biomass rich in carbohydrates are considered as a substitute for the excesive grain crops. These crops besides of the main products will yield large quantities of byproducts in the form of crop residues. The main crop products can be used as raw materials for industry while the byproducts offer the possibility of exploitation in an nontraditional way for production of fuel. With regard to abundance of the crop residues, the exploitation should be located in the rural area in order to keep the transportation expenses as low as possible. From an ecological point of view the most beneficial method for conversion of the biomass into fuel under this conditions seems to be the methanogenic fermentation. It has been recognized, however, that the economics of methanogenic fermentation is still the crucial problem. This depends on a number of factors such as the technology, quality of raw materials, biodegradability of the substrates etc. Although a certain progress has been made f. inst. with application of cellulolytic enzymes (2, 3), much remains still to be done concer ning the specific problem of lignocellulosic compounds, the technology etc. 2. CLIMATIC CONDITIONS The experimental area is located at 55°40’ N 12°18’ E about 20km west of Copenhagen at an altitude of 30m a.s.l. The climatic conditions, mainly the temperature, delimit the duration of the growth seasons to the period from 1. April to 31. October. The normal daily mean temperature is 7.5°C, during the growth season 11.9°C. The available PAR amounts to 49% of the global radiation having the maximum in the middle of summer (Figure I). The normal annual precipitations amount to 583mm of which 371mm makes up rainfall for 7 months of the growth season (Figure II). Under normal conditions the rainfall compensates for the transpiration of intensive crops also during the summer months. This allows a growth of long-term crops with maximum photosynthetic production during the summer.

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Figure I. (left) Daily totals of photosynthetically active radiation (1955–1979) Einstein m−2 (4).

Figure II. (right) Monthly normal precipitations (1955–1979) mm (4). 3. CROPPING SYSTEM The predominating crop grown in Denmark is spring barley (HORDEUM VULGARE). As shown in Figure III, the growth cyclus of spring barley is short. This becomes important when such a crop is grown repeatedly without crop rotation. In this way the PAR available during the summer and the autumn is lost. To eliminate these losses and the drawbacks of the overspecialization as mentioned above, a field experiment with a cropping system including 20 different crops and 18 crop rotation combinations was started in 1982. The field experiment was designed to become a model for a liberal-ecological cropping system with production of biomass for energy purposes. In order to capture maximum of the PAR for a large part of the season as passible, long-term crops and catch crops were incorporated. The LAI and prodution of TS were

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measured periodically and on this basis the cropping system has been evaluated. The leaves area distribution in the form of LAI of selected crops is shown in Figure III.

Figure III. Distribution of leaves area—LAI of field crops. Symbols: +=crop during the postemergence stage LAI <1. *=crop during the vegetative growth LAI >1. Each line represents a unit of LAI. 4. PRODUCTION OF BIOMASS The local climatic conditions give the theoretical possibility of photosynthetic production of biomass during the growth season of 7 months per year. Provided that all growth factors are optimal, then LAI of a crop can be considered as a measure of the respective crop capacity to capture the PAR.

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Different terms can be used to express the growth rate and the photosynthetic energy efficiency of a crop. Growth rate is usually cited as dry matter production per unit area per day while the photosynthetic energy efficiency is given by the TS production per unit of radiation (5, 6). The interrelation between these two parameters expresses the photosynthetic capacity of the crop in question. Thus, the crops with large LAI remaining photosynthetically active during the period of optimal growth conditions can be regarded as feasible for production of biomass. The evaluation of selected crops is summarized in Tables I and II showing differences among these crops in the ability to accumulate photosynthetic energy and also to release this energy from the biomass. Evaluation of crops taking the only parameter of fuel production into consideration is of course not complex. From some of the crops only crop residues are used for production of biogas, nevertheless, the yield of TS namely 22.894t/ha of sugar beet roots and top and the yield 23.099t/ha of Jerusalem artichoke tubers and stalks proved the superiority of these two crops in the cropping system. Both these crops can be classified as energy crops with a high energy potential of the products and byproducts. 5. EXPLOITATION OF THE BIOMASS The exploitation of both the main products and the byproducts for fuels has been performed experimentally in the laboratory. The economics of microbial conversion of biomass into fuel, although being decisive, has not been subject of consideration in this context. Production of alcohol from biomass is becoming actual with the increasing need for clean fuels for motor vehicles. One of the factors determining the applicability of a crop for the microbial conversion into alcohol is the yield of fermentable substrates. According to recent report the ethanol yield of crops such as f.inst. Jerusalem artichoke can reach 56hl/ha (8). In connection with the field experiment a laboratory investigation was performed with a comparative production of alcohol from sugar beet roots, J. artichoke and potato tubers. All three crops were grown under similar conditions and were harvested in the last days of October 1984. In the laboratory the materials were boiled under pressure for 30min. and homogenized with a blender, finally the pH was adjusted to 4.5–5.0. The mash of potato tubers was liquefied and saccharified enzymatically by the use of THERMAMYL and AMG NOVO. All materials were then fermented without and with SP 249 NOVO enzyme, using the alcoholic strain SACCHAROMYCES CEREVISIAE under temperature of 30°C during 72 hrs. Yield of alcohol was determined after distillation by using alcohol dehydrogenase (9).

Table I. Production and yield of alcohol from selected crops. RAW MATERIAL

TS %

SUGAR BEET var. Brita 22.90

REFRACT. SUGARS 20.32

ENZYME ADDED –

ALCOHOL 1/kg TS 0.40±0.08

YIELD ALCOHOL TS t/ha hl/ha 16.034

64.14

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SUGAR BEET var. Brita J. ARTICHOKE var.Urodny J. ARTICHOKE var. Urodny POTATO var.Tylva POTATO var. Tylva

480

22.90

20.32

SP 249 NOVO

0.53±0.10

16.034

84.98

20.23

16.59

–

0.33± 0.01

10.979

36.23

20.23

16.59

0.37±0.03

10.979

40.62

0.35 ±0.04

13.324

46.63

0.39±0.04

13.324

51.96

25.60 25.60

SP 249 NOVO 7.93 THERMAMYL +AMG NOVO 7.93 THERMAMYL +AMG+SP 249

The table shows that sugar beet roots exerted the highest respons to enzymatic treatment. The effect of the enzyme SP 249 should be ascribed to the degradation of plant tissue (polygalacturonase, pectinase activity) releasing additional substrates for the fermentation. The yield of alcohol per area unit confirms that sugar beet root is a superior raw material for production of alcohol. The difference between J. artichoke and potato in yield of alcohol per area unit was mainly caused by the difference in yield of tubers. In order to evaluate the feasibility of crop residues for production of gasous fuel via bioconversion, a laboratory investigation has been carried out with anaerobic fermentation by the use of batch system reactors operating under mesophilic conditions (35°C). The investigation included 30 different plant materials mainly crop residues (7) of which selected examples are presented in Table II.

Table II. Production and yield of biogas from crop residues. RAW MATERIAL SUGAR BEET fresh top J. ARTICHOKE silage stalks POTATO silage top WHITE CABBAGE silage leaves MAIZE fresh stalks SPRING BARLEY straw

TS %

B G 1/kg C H4 1/kg YIELD TS VS VS t/ha

YIELD VS kg/ha

YIELD CH4 m3/ha

12.9

534±18.2

355

6.860

5214

1851

17.1

468±14.8

315

12.120

10787

2718

17.7

347±11.6

246

2.567

2026

498

10.4

638±15.9

451

6.720

5242

2364

24.8

378±7.8

257

7.315

6730

1730

89.4

427±16.3

274

5.784

5495

1506

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As shown, the highest yield of CH4/kg VS added has been achieved from ensiled leaves of white cabbage. The yield of methane from potato top when expressed per area unit is not satisfactory in comparison with the other raw materials. This is mainly due to the very low yield of the top. The exploitation of crop residues for production of biogas is associated with specific problems of biodegradability, production rate as well as the handling of fermentation residues (7). From economical point of view the bioconversion of crop materials into gasous fuel via methanogenic fermentation needs further investigation.

Table III. Yield of gross energy from selected crops. Raw material

Alcohol=Energy Methane=Energy Total O.E. 1/ha GJ/ha m3/ha GJ/ha GJ/ha 1/ha

SUGAR BEET var. Brita 8498 J. ARTICHOKE var. Urodny 4062 POTATO var.Tylva 5196 WHITE CABBAGE var. Vernida – MAIZE var. Pioneer 3995 – SPRING BARLEY var. Tyra – Symbol: O.E.=oil equivalent (diesel fuel)

181.772

1851

69.783 251.555 7066

86.886

2718

102.469 189.355 5319

111.142

498

18.775 129.917 3649

–

2364

89.123

89.123 2503

–

1730

65.221

65.221 1832

–

1506

56.776 56.776 1595 Methane =37.7 MJ/m3(10) Ethanol=21.4 MJ/l (11) Diesel fuel= 35.6MJ/1 (11)

6. GROSS ENERGY YIELD Proper experimental evidence proves that the main products rich in fermentable substrates as well as the byproducts from long term crops, both can be exploited for fuel production. Under climatic conditions of Norhern Europe, with the exception of seasons extraordinary dry, these crops can be grown with succes without irrigation. Anyhaw, a certain limit is given by the agrotechnical demands of crop rotation particularly in the case of sugar beet. For comparative purposes the gross energy yields in the form of alcohol and biogas from selected potential crops are presented in Table III. The highest gross energy yield was achieved from sugar beet which being used for alcohol and biogas production yielded 251.555GJ/ha equivalent to 7066l O.E. /ha/year. In a crop rotation with other field crops and with Jerusalem artichoke, which yielded 189.355GJ/ha equivalent to 5319l O.E./ha/year, this crop combination appears feasible for incorporation into a cropping system designed for intensive capturing of PAR in the biomass of plants.

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ACKNOWLEDGEMENTS The experimental work was supported by The Royal Veterinary and Agricultural University, Copenhagen, and partly sponsored by the Danish Agricultural and Veterinary Research Council. Linguistic revision of the text by E.Svenstrup. REFERENCES (1) DANMARKS STATISTIK (1983). Landbrugs statistik, (Danish). (2) PAGUOT, M., THONART, P., FOUCART, M., DESMONS, P. and MOTTET, A. (1984). Improvement of pretreatments and technologies for enzymatic hydrolysis of cellulose from industrial and agricultural refuse and comparison with acidic hydrolysis. In: Anaerobic digestion and carbohydrate hydrolysis of waste. Edit. FERRERO, C.L., FERRANTI, M.P., NAVEAU, H. Elsevier Appl. Publ. London, 112–124. (3) RIJKENS, B.A. (1979). Methane and compost from straw. In: Proc. of the third Coordination Meeting of Contractors “ENERGY FROM BIOMASS” 6–8 June 1979, Taormina, Italy. (4) HANSEN, S., JENSEN, Sv.E., ASLYNG, H.C. (1981). Jordbrugsmeteorologiske observationer statistisk analyse og vurdering 1955–1979, (Danish). Den Kgl. Veterinaer-og Landbohøjskole, København. (5) SIBMA, L. (1977). Maximization of arable crop yields in the Netherlands, Neth. J. Agric. Sci. 25, 278–287. (6) STEWART, G.A. (1970). High potential productivity of the tropics for cereal crops, grass forage crops and beef. J. Austr. Inst. Agr. Sci. 36, 85–101. (7) ZUBR, J. (1985). Crop residues and energy crops as renewable sources of convertible photosynthetic energy for methanogenic fermentation. In: Biotechnology and enviromental systems, WISE, D.L., CRC Press. (8) WILLIAMS, L.A. and ZIOBRO, G. (1982). Processing and fermentation of Jerusalem artichoke for ethanol production. Biotechnol. Letters Vol. 4 1, 45–50. (9) BERNT, E. and GUTMANN, I. (1974). Ethanol determination with alcohol dehydrogenase and NAD. In: Methods of enzymatic analysis, BERGMEIER, H.U., Acad. Press, N.Y. Vol. 3, 1499– 1502. (10) BABA (1982), Anaerobic digesters, A code of practice on safety in and around anaerobic digesters. (11) BERG, P.S., HOLMER, E. and BERTILSSON, B.I. (1980). The utilization of different fuels in a diesel engine with two separate injection systems In: Proc. of third International Symposium on Alcohol Fuel Technology, Asilomar, California 29–31 May 1979.

MICROPROPAGATION OF SOME FOREST TREE SPECIES G.SAVOIA and S.BIONDI Azienda Regionale delle Foreste dell’Emilia-Romagna, Bologna, Italy Summary In view of the need to increment biomass production for energy, the A.R.F.E.R. is examining ways to increase the productivity and economic viability of Regional forests by increasing the genetic gains. This can be achieved by selecting and cloning the best individuals within the best geographic sources of the best species. Using micropropagation as an in vitro technique of vegetative propagation, quality trees are selected and mass-produced. In this way the rapid multiplication of selected genotypes which are scarce and/or difficult to propagate by rooted cuttings can be achieved. The species chosen to date for the micropropagation studies are chestnut, walnut, Douglas fir, wild cherry, alder and elm. Only mature trees, old enough to have demonstrated their superior characteristics, are propagated. This often requires the application of “rejuvenation” treatments on the donour-plant to improve the response of the explants to micropropagation. The field performance of the micropropagated plants will be evaluated in every case and clonal collections and seed orchards established.

1. INTRODUCTION The potential energy obtainable from forest biomass is impressive. For biomass production, the major objective is to obtain the maximum growth of the most desired wood in the shortest possible time at as low a cost as possible. With this objective in mind, the A.R.F.E.R. is examining ways to: – increase the yield on already good sites, and – develop trees capable of growing on marginal or non-productive areas that currently do not support an economical forest enterprise. The A.R.F.E.R.’s project on the micropropagation of forest tree species is aimed at obtaining genetic gains from tree improvement by: – locating and using the correct species; – using the best geographic sources within the best species; – selecting and cloning the best individuals within the best sources of the best species.

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Hybrids especially developed in breeding programmes (elm) and elite cultivars (chestnut) are also used. When the energy and fuel-wood species are selected, special consideration should be given to adaptability, rapid growth (short rotation), ability to coppice and production of wood of high calorific value (1). The micropropagation project has also taken into consideration those species which can assist in land consolidation on steep hillslopes (over 90% of the Regional forests are in hilly or mountainous areas), which can grow on clay soils and which provide high quality wood. This latter aspect is of fundamental importance since Italy imports 75% of this wood and these imports weigh heavily in the country’s foreign trade balance. Using in vitro techniques, quality trees and disease-resistant clones are selected and mass-produced (this also ensures the conservation of our dwindling genetic reserves); also the risks associated with the collection and variable quality of seeds and with nursery practice are reduced. It is expected that this alternative approach to the vegetative propagation of elite trees or cultivars will consent the following: a) the rapid multiplication of selected genotypes especially when these are scarce, since tissue culture offers the advantage that a few explants are sufticient to produce several thousand propagules; b) cloning selected genotypes in species which are difficult to propagate by rooted cuttings; c) an improvement in the rooting percentage of cuttings. It has been reported that when micropropagated plants are used as ortets, the rootability of cuttings is higher (2). To date the following species have been considered for our micropropagation studies: Castanea sativa, Juglans regia, Prunus avium, Pseudotsuga menziesii, Alnus cordata and Ulmus spp. In line with the fore-mentioned objective of improvine forest productivity and obtaining high genetic gains by using carefully selected genotypes, only mature trees old enough to have demonstrated their superior characteristics, are used as donour-plants. In view 01 the well-known difficulties encountered when attempts are made to propagate mature clones, two solutions are being examined: – pre-treatments on the donour-plant that convert mature tissues to a more juvenile state (“rejuvenation”); – propagation of adolescent trees (5–10 years old depending on the species). Theoretically the propagules can be kept in cold storage for several years during which time the quality of the donour-plants is evaluated. Subsequently, the propagules of the plus genotypes are mass-propagated while the others are discarded. In all cases, the field performance of the micropropagated plants is to be determined. Seed orchards (as a complement to vegetative propagation) to supply genetically improved seed for the forest industry can be set up using micropropagated plants. As well, if in vitro mass propagation proves not to be economically viable with respect to other means of vegetative propagation, micropropagated plants can be produced in limited numbers to create clonal orchards from which classical cuttings can be taken for large-scale production. These clonal orchards will also play a role in germplasm conservation.

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2. MATERIALS AND METHODS The micropropagation programme is subdivided into the following stages: I. choice of donour-plants and explants II. rejuvenation of donour-plants III. in vitro propagation IV. transfer of plantlets to soil and field trials V. clonal collections. The materials and methods used in each of these stages will be described briefly. I. Choice of donour-plants and explants As stated in the Introduction, our project makes use of high value donour-plants selected for specific genetic traits such as wood quality, form, growth rate, disease resistance, etc. They are located on the basis of: – a survey carried out in Emilia-Romagna in which the best individuals were selected; – ongoing breeding programmes (at the Istituto Sperimentale per la Selvicoltura of Arezzo and the Centro di Studio per la patologia delle specie legnose montane, C.N.R. of Florence) in which different geographic sources are subjected to comparative tests or, as in the case of elm, in which new hybrids are being created and tested for their resistance to Dutch elm disease. For chestnut, elite cultivars which have been vegetatively propagated (by grafting) for many years in Tuscany and collected in trial areas set up by the Istituto di Selvicoltura of the University of Florence, are used as donour-plants. The choice of the explant (bud) refers principally to the part of the tree from which it is collected and the time of year it is collected. Bud break in culture occurs faster and better if the buds are in the predormant stage. It has been recognized that the rooting response of cuttings and the feasibility of in vitro propagation rapidly decline with increasing age of the donour-plant. Several approaches have been taken in recent years to overcome this obstacle and obtain physiologically younger or so-called “rejuvenated” material. First of all, some parts of adult trees are thought to be more juvenile, in particular those which are closer to the roots. Thus, buds or ramets taken from stump sprouts or root suckers of mature trees are more easily propagated. II. Rejuvenation When a mature tree does not spontaneously form juvenile material, several techniques can be applied to induce the process of “rejuvenation”. – Grafting scions taken from the mature tree onto young rootstock. It may be necessary to repeat the grafting cycle several times in succession (“successive grafting”). – Nut-grafting. This approach is based on the same concept that grafting on a young rootstock tends to“rejuvenate”mature scions. Nut-grafting can be applied to chestnut and walnut. The scion is grafted on a germinated nut after removal of the radicle and part of the hypocotly, into a transversal slit cut across the nut. Alternately, only the apical part of the radicle is excised and the scion is joined onto the remaining part.

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– The release of suppressed buds, by hedging to form epicormic shoots which are frequently more juvenile. – Cytokinin foliar sprays. Cytokinins are a class of plant growth regulators (phytohormones) which, when applied at relatively high concentrations to a plant, release lateral buds from apical dominance. These compounds are used in tissue culture to induce bud break and shoot proliferation, but also to induce or maintain a rejuvenated phase. Indeed, studies carried out principally in France and the U.S.A., seem to indicate that several weekly applications of cytokinin foliar sprays prior to natural bud burst produce rejuvenated material which is more easily propagated both by rooted cuttings and by axillary bud cultures. III. In vitro propagation In our programme, in vitro propagation is carried out by means of axillary bud cultures. This approach requires surface sterilization of buds collected preferably in the predormant stage, followed by bud scale removal, excision of the shoot apex with attached young leaf primordia and introduction in aseptic culture on an appropriate medium. The components of this medium must be empirically determined at each subculture to allow the following succession of events: – bud break (within approximately 4 weeks) – the development 01 lateral meristems and the outgrowth of small shoots (multiplication phase) – the elongation of these shoots to at least 10mm lengths – the rooting of elongated shoots for plantlet formation. This technique is commonly referred to as “micropropagation” and has led to many recent successes in mass propagating woody species. It must be emphasized that each species and sometimes each cultivar to be cloned more often than not requires the development of a specific procedure which can, with our present knowledge, only be derived empirically. IV. Transfer of plantlets to soil and field trials. Plantlets produced in vitro must be acclimated or hardened, i.e. they must undergo a gradual transition to the lower humidity and higher light intensities existing in the open. This is achieved by transplanting the plantlets into potting mixtures and placing them under warm and highly humid conditions, for example in a greenhouse under intermittent mist. However, different species require specific methods of handling, light and temperature regimes, etc. which must be determined by trial-and-error. Upon transfer to nursery or field conditions, several points must be borne in mind: – the quality of the root system. This is important for nutrient absorption, wind stability and form. Sometimes what may seem like plagiotropic growth is due to a poorly balanced root-shoot system. – Plantlets are very vulnerable to pathogen attacks and must be treated with pesticides, fungicides, etc. Field performance is evaluated in terms of growth rate, topophysis, disease resistance, etc. and in comparison to seed-derived seedlings and rooted cuttings.

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V. Clonal collections In parallel to the studies linked to the micropropagation of the species under examination, efforts are being made to set up clonal collections with the selected genotypes using grafting techniques in nurseries or plantations belonging to the A.R.F.E.R.. This scheme has a dual purpose: – to render the plants more accessible for the collection of material for propagation; – to ensure the conservation of unique genotypes even where micropropagated plants are not yet available. At the same time, the performance of clones or cultivars which have demonstrated their superior characteristics in other geographic locations can be tested in the Appenines of Emilia-Romagna where the future reforestation programmes are to be carried out. 3. RESULTS Castanea sativa. Varietal collections have been established by grafting scions of 8 elite cultivars on 1-year old seedlings or 2-year old stump sprouts. Various techniques related to the grafting operation and the incidence of ink disease and chestnut blight are examined. The method of nut-grafting in which the scion is grafted onto the radicle has given positive results but the use of extremely small scions to match the diameter of the radicle may carry epigenetic defects which impair the later development of the plant. Our micropropagation studies have proceeded with buds obtained from scions grafted several years ago on young and vigourous stump sprouts and pruned annually. The results obtained to date regard mainly one cultivar (Mozza). In the presence of a growth hormone (0.5 mg/l benzyladenine (BA)) proliferation by axillary budding can be achieved. The multiplication rate is approximately 3:1 every 3–4 weeks. The subsequent elongation of the shoots thus obtained, which is enhanced by reducing the BA supplied to the medium, is somewhat erratic. Consequently, experiments aimed at inducing rhizogenesis in the shoots are limited. With the material available, numerous trials have been carried out varying the macro- and micro-nutrient formulas, the hormonal treatments, the physical support, etc., but as yet this phase of the micropropagation process remains to be accomplished. Prunus avium. Seven selected clones have been introduced in aseptic culture. Approximately 1000 micropropagated plants of each of 4 clones have been planted in the field for comparative tests on the performance of the different geographic sources. A further 1000 plants of the clone Paradisino have been planted out (November’ 84) for the purpose of creating a seed orchard. The micropropagation of this species followed the usual scheme of inducing axillary budding on a medium supplemented with BA (1.5mg/l). The multiplication rate was rather high since several hundred plantlets can be obtained from one explant in 8 to 10 months. Following shoot elongation on a medium with reduced BA, rooting was induced in the presence of 3 mg/l indole acetic acid. The rooting percentage varied from clone to clone (15 to 80%). Rooted plantlets were successfully hardened in a greenhouse (over 90% survival rate) and transferred to soil for field trials.

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Ulmus spp.. Two species and several elm hybrids with a good level of resistance to Dutch elm disease developed in the breeding programmes undertaken in Italy and abroad under the auspices of the EEC in order to combat this disease have been introduced in one of our nurseries by grafting on U. pumila seedlings. In the spring of ‘85 scions taken from ortets of U. carpinifolia and of their spontaneous hybrid U. carpinifolia×pumila which, as a survey in progress in Emilia-Romagna will demonstrate, have survived the Dutch elm disease epidemic will be added to the collection in order to preserve their germplasm for future breeding programmes in the hope that at least some of them are resistant. Another possibility is that in the future the Dutch elm disease epidemic may recede, or that effective chemical and biological controls for elm bark beetles will be found so that even the less resistant clones can survive. Buds were excised from the root suckers of a mature (ca. 100-year old) clone, free of Dutch elm disease. The buds were subjected to the normal sterilizing procedures and placed in culture on a suitable growth medium (1mg/l BA). Shoot multiplication by axillary budding occurred in these conditions. Rooting was induced by adding 1mg/l naphthalene acetic acid and 100mg/l activated charcoal. Rooted plantlets were hardened in a greenhouse for 40–50 days with excellent survival rates. Over 1000 plantlets were transferred to soil in a nursery for field trials. Some of the resistant hybrids and species mentioned earlier have now been introduced in culture. In some cases (e.g. U.wilsoniana, U.villosa and “454 Lobel”), their micropropagation is already in the final stages. Pseudotsuga menziesii. Numerous North American and one Italian provenance of this species have been introduced in experimental areas via rooted cuttings for comparative tests between the various provenances. The cuttings from these superior provenances are part of a IUFRO programme aimed at comparing over 80 provenances. Another collection has been set up by grafting on 2-year old seedlings scions taken from 20 individually selected phenotypically superior clones growing in the forest of Vallombrosa, Tuscany. These clones are approx. 60–80 years old and are currently subjected to progeny tests. Two approaches have been taken in order to rejuvenate the mature clones: – successive grafting – foliar applications of a cytokinin (BA). Experiments to induce axillary budding are now in progress with buds collected from 6–7 years old trees of various provenances. Juglans regia and Alnus cordata. Work with these species has thus far proceeded as far as constituting clonal collections or sowing the seed of selected clones. Some mature walnut clones have been severely pruned to induce the formation of epicormic shoots which may provide “rejuvenated” material for propagation. For alder, scions from 42 plus ortets selected in the province of Florence were grafted on seedlings in the spring of ’84. These have been planted out in the forest following an experimental design.

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REFERENCES (1) DURZAN, D.J. (1982). Cell and tissue culture in forest industry. Tissue Culture in Forestry (J.M.Bonga and D.J.Durzan, eds), Martinus Nijhoff Publishers, The Hague 36–71. (2) BOULAY, M. (1985). Some practical aspects and applications on the micropropagation of forest trees. International Symposium on In Vitro Propagation of Forest Tree Species, Bologna.

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Micropropagation of some forest tree species

II. CONVERSION (a) Anaerobic Digestion (b) Fermentation (c) Hydrocarbons (d) Combustion (e) Gasification and Pyrolysis (f) Liquefaction (g) Chemicals (h) Enzymes

491

ANAEROBIC DIGESTION IN THE FOOD PROCESSING INDUSTRY : A FEASIBILITY STUDY D.J.COX and D.R.NUTTALL Polytechnic of the South Bank, London SE1 OAA, U.K. Summary Over 200 companies in the UK food and beverage sector were contacted and asked to collaborate in a study of effluent treatment/disposal strategies. Fifty-one were visited and senior personnel interviewed during site tours. A further 50 exchanged correspondence. Detailed questionnaires were completed (in some cases) concerning strength, volume, nature of wastes, costs incurred and company perspectives and strategies. The economics of on-site treatment were generally favourable with anaerobic digestion showing most promise. Pay back of most anaerobic systems was (or would be) within the limits considered suitable for commercial investment (2–5 years). However, a large proportion of industrialists were not kindly disposed towards on-site treatment of any type, and often preferred to reduce disposal costs through factory husbandry. Suspicion of on-site treatment was principally on aesthetic grounds (particularly the prospect of malodorous emissions) and also there were worries about practicality of operation, maintenance and monitoring. The prospects of biogas use for process or other heat was of peripheral interest to all but the most committed devotees. Many sites were too restricted for space, or were unable to collect trade waste easily. Vegetable processing and malting seemed most suitable for on-site anaerobic treatment in the UK. Meat and poultry processing least so.

1. INTRODUCTION The effluent disposal problems of the UK food processing and beverage sector has been evaluated on a number of previous occasions. (e.g. (1)), as often as not, however, the results of these surveys or evaluations have either not passed into the public domain (since they were sponsored by organisations with commercial interests in the results), or have been targetted to specific subsectors (e.g. brewing), or are reports of field trials of particular designs of plant. Many evaluations have been based on literature studies alone where speculative projections have been made from average COD/flow data, with little attempt being made to consider the needs, aspirations and problems of the actual endusers of plant. Generally speaking, the industry has not been well served by consultants in this field, whose experience is rooted in domestic wastewater dogma. Thus there are

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several painful examples of activated sludge-type processes being installed to treat certain industrial wastes which are clearly unsuited to such treatment, resulting in a high waste activated sludge disposal problem. Similarly, poorly field-tested novel designs of plant have been installed on several occasions with exaggerated claims being made for their capabilities. The subsequent lacklustre performance of these systems has done much to encourage suspicion among other potential users. Consequently, on-site treatment in the UK food processing industry is not common, and the desire to embrace novel designs, including high-rate digestor systems, is not great. There are at least 8 anaerobic digesters installed in UK food, drinks and fermentation industries (2) and several dozen other types of plant, but in comparison with the total number of manufacturing sites, the penetration is very small. Nevertheless, the potential for cash (and energy) saving through onsite treatment seems, on the surface, to be great. The UK food and beverage industry pays several hundred million pounds each year in trade effluent charges, and discharges between 300– 400 million m3 of high COD, high biodegradeable material into the municipal sewerage system. This material represents a wasted resource and, if treated anaerobically, could yield over 100 million m3 of biogas. A large brewery, for example, could reduce its trade effluent bill by £200,000 per year and produce substantial quantities of biogas, easily and usefully deployed in the raising of steam for processing. The original purpose of this work, in surveying the UK sector was to develop a scheme by which effluent and treatment options could be rationally matched. However, it soon became apparent that there were numerous non-technical barriers to exploitation of on-site treatment technology, and local circumstances which had a profound effect on treatment strategies. This report attempts to summarise these factors. 2. SURVEY METHODOLOGY Over 200 companies in England and Wales were contacted by letter and asked to collaborate in the survey. Absolute confidentiality was guaranteed and therefore no names, addresses, or easily identifiable case histories can be given. Fifty-one companies agreed to site visits and a further fifty exchanged correspondence. The most numerous response was from the brewing industry with 18 companies visited, representing a 22% conversion (76 letters sent). Six maltings were visited (29% conversion) and 5 confectionery factories (10%). The remaining 22 visits were to vegetable/fruit canning factories (5) poultry/meat processing operations (5), cider breweries (3), cereal/starch processors (4), and factories with miscellaneous or multi-product operations. The dairies seemed especially reluctant to participate in the project, with only one site visited. At each visit senior staff were interviewed and questioned about the strength, nature and volume of wastes, diurnal and other variations, local Water Authority (WA) consent conditions, sampling and monitoring practises and costs incurred. The company posture on on-site treatment was also explored in some detail, as was their experiences in and opinions of any advice which had been sought externally. Interviewees generally considered themselves knowledgeable about their sector in general, as well as their own factory, and over all the interviews a coherent picture of the food beverage sector began to emerge.

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Information gleaned from correspondence was usually detailed with respect to effluent characteristics and disposal costs, but less informative regarding the non-technical issues. Nevertheless, opinions expressed tended to reinforce, rather than detract from the overall view. After each visit a detailed report was prepared and discussed. Numerical data were stored on record sheets for later statistical analysis. 3. THE FINDINGS Those operations producing effluents whose treatment incurs significant cost (greater than £40,000 per year) are listed in Table 1.

Table 1: Factories with effluent treatment costs greater than £40,000 (1983 prices) Operation

Scale

COD range (mg 02/L)

Poultry processing all 3000–4500 Brewing/cider medium-large 1000–2000 Malting large 1500–3500 Confectionery large 2000–28,000 Canning/freezing medium-large 1500–4000

The actual costs incurred in trade waste disposal via WA sewer obviously varied greatly according to the scale of individual factory operations and strength/volume of waste generated. In addition, local consent conditions imposed by WA’s and individual sampling procedures employed by WA inspectors often produced quite surprisingly wide differences between similar operations located in different areas. To quote two extremes from brewing, we found that effluent charges varied from £0.73 to £6.40 per m3 of beer produced, with an average of £1.36/m3. In general, breweries faced the most substantial disposal charges, followed by confectionery, starch/cereal processing, vegetable processing/ canning, meat/poultry processing and malting. However, this is probably little more than a reflection of the sizes of the various operations. On-site treatment of effluent in the factories visited was not common. of the 51 visited, only 9 used some form of treatment. None used anaerobic digestion. In the case of brewing, canning/freezing and confectionery (with one notable exception), the effluent was generally discharged to sewer without any treatment. Malting operations were invariably sited in remote rural areas not served by sewers. This implies direct discharge to watercourse, and therefore some form of treatment is legally required. In all cases this was aerobic (either activated sludge or trickling filter). In the case of poultry processing, and in some meat processing operations, Dissolved Air Flotation (DAF) plants were widely used. Wherever possible the protein-rich sludge was used as a by-product additive. In general users were well satisfied with this approach to trade waste disposal, and showed litle inclination to consider other options.

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Attitudes to effluent and on-site treatment : There was quite a high degree of awareness among companies regarding the problem of effluent disposal. No doubt this is because they are continually reminded of this by the arrival of the WA trade effluent bill, which In some cases amounted to greater than £300,000 per year. Additionally, WA officials in the UK maintain a regular presence in factories and are often regarded as hostile by company personnel. Most companies had undertaken some form of evaluation of their trade waste disposal and the majority had invited commercial representatives to their premises and requested quotations for treatment plant. In those cases where a realistic economic assessment had been made (about 30%), and where there were no special problems associated with the effluent itself, then anaerobic systems were overwhelmingly favoured over aerobic. Pay back times of between 2–5 years had been calculated for the former, as opposed to 7–10 years for the latter. Interestingly, interviewees had accounted for the obvious features of capital cost and trade charge savings, and had also considered labour charges, power costs and sludge disposal problems, but few had bothered to estimate the potential value of any biogas produced. There is evidence to suggest that since these savings would accrue to a different ‘cost centre’ within the company, then there was little incentive for the effluent treatment ‘manager’ to rate these savings highly in his own budgetting. Nevertheless, even in those cases where pay back times had been calculated as 2–3 years, companies were often reluctant to invest several hundred thousand pounds in treatment plant, arguing that a similar investment in production plant would pay back even sooner. One of the most surprising conclusions of the survey was the extent to which companies were concerned with aesthetic and non-technical problems associated with onsite treatment plant. Most interviewees were very worried that systems would produce malodorous emissions which would create ill-feeling among local residents who were usually already mildly hostile to neighbouring factories. In the company’s perception, anaerobic systems were favoured in this regard since, being enclosed, they would be less likely to generate smells. Balancing tanks, apart from being very costly, are often the culprit in malodorous plants, and commmercial prizes await the effluent disposal company which devises a system with a reduced or eliminated requirement for balancing. The opinion was also regularly voiced that food processing companies are not in the ‘business’ of effluent disposal—they are not used to it, they do not have personnel trained in it, and the use of such operations may detract from the company’s ‘image’. In other words effluent treatment (and for ‘effluent’ read ‘sewage’!) is not consistent with food production. Finally, it was clear that a large number of factories either did not have the space for on-site treatment plant, or did not have an adequate system of drains. This was particularly so in breweries (especially older breweries) which usually occupy urban sites several centuries old, and also in confectionery factories. The same problem also applied to poultry and meat processing factories, although to a lesser degree. In any case, the effluents generated by brewing and meat processing are not well suited to on-site (anaerobic) treatment, largely due to their inconsistent nature and extremes of pH, toxic content and so on.

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4. CONCLUSIONS The authors are aware that to a certain extent the conclusions of this survey are subjective and based on concensus views rather than unassailable scientific data. Moreover, the sample size was not large in relation to the total UK sector. Nevertheless, we believe that the picture that had emerged after more than a year ‘on the road’ is a true reflection of the prevailing views of putative practitioners of anaerobic digestion in the food and beverage industries. We conclude that the prospects for penetration of current anaerobic digestion technology are not good in the brewing and confectionery industries, largely due to poor sites, aesthetic considerations and in the former case, to a ‘difficult’ effluent. Prospects for digestion in the meat and poultry sector are even less interesting, owing to the predominance of DAF. Vegetable processing, canning and malting, however, seem useful target sectors since they usually occupy rural sites, have ‘easy’ effluents and can easily use any biogas generated. Potential savings on trade effluent charges are great in vegetable processing/canning, but less so in malting owing to reduced scale of operation. The tendency of these factories to operate on a seasonal basis does not seem to constitute any serious impediment to onsite treatment. REFERENCES (1) HERZHA, A. and BOOTH, R.G. Eds. (1983). Food Industry Wastes: Disposal and recovery. Applied Science Publishers. (2) KEMP, D. (1984). Anaerobic digesters treating industrial digesters in the UK. BABA Digest Vol 13 (Nov.) 6–9

PURIFICATION OF BIOGAS K.EGGER, K.SUTTER and A.WELLINGER BIOGAS PROJECT, Swiss Federal Research Station for Farm Management and Agricultural Engineering, CH-8355 Taenikon 1. INTRODUCTION Biogas formed from any substrate is usually composed of methane, carbon dioxide, water vapor and trace amounts of hydrogen sulfide. Often the question is risen whether it would be of advantage to remove all gases but the energy rich methane. The scrubbing of CO2 as inert gas is of limited interest only, for applications where the gas is compressed or has to be brought up to pipeline qualities. For the hydrogen sulfide however, it is strongly recommanded to strip it off before any utilization of biogas. It is at the same time a nuisant and heavily toxic compound. The subject of the present study was to design H2S and CO2 purification plants for on-farm utilization. Construction parameters were defined in pilot plant experiments and consequently full-size installations have been built and monitored on the farm for about nine months. The purified gas was used to run a biogas tractor (see poster PIV/234). 2. CHEMISORPTION OF HYDROGEN SULFIDE When protein or sulfate containing organic waste is anaerobically degraded,trace amounts of hydrogen sulfide are formed, ranging in biogas from animal manure up to 0.5% (v/v). H2S is not only a very toxic gas, it is also very corrosiv. Gas utilities therefore have stringent quality requirements: – For the use of biogas in internal combustion engines, manufacturers usually require concentrations of less than 50 to 100ppm. – If biogas is used as boiler fuel, H2S causes an increase of the exhaust gas dew point (the so called acid dew point). With common concentrations of several hundred ppm’s H2S in the biogas, the condensation temperature of the flue gas is increased up to 160 C. This value compares to natural gas with a dew point of 57 C only. The condensate formed is rich in sulfuric acid and leads to heavy corrosion of exhaust pipes, chimneys and parts of the heater. – Virtually all of the H2S has to be removed for the storage of biogas under high pressure (200bar). Together with traces of water, H2S leads to heavy corrosion of the pressure bottles within a few weeks. – The same is true for cooking where H2S is reduced to SO2 which is odourless but even more poisenous than the former.

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Chemisorption: Proceedures to remove H2S from a gas phase have been known for many years however, they were hardly applied with biogas. One of the oldest technologies is the chemisorption by iron oxide: Fe2O3.3H2O+3H2S=Fe2S3+6H2O With the addition of oxygen the iron sulfide is regenerated in a strongly exergonic reaction: Fe2SO3+3/2 O2+3H2O=Fe2O3.3H2O+3S The pure sulfure formed during the reaction is an ecologically harmless compound and adheres usually to the iron oxyde. This dry purification process fits perfectly well into the requirements of agricultural biogas production: it is a simple and low cost technique and is easily adaptable to gas flow rates of 10 to 500m3 per day. The market offers a variety of products usually in the form of iron oxyde-coated pellets in lengths of 10 to 30mm and diameters around 12mm. The water content of the different products varies from 5% to 20% (w/w). Two process parameters essentially describe the behaviour of an adsorption column: the load and the zone of reaction. Both were defined in a pilot-size column of a height of 1m and a diameter of 65cm which was filled with 33 litres of iron oxide pellets (Hamm Chemie, Germany). Biogas with defined concentrations of H2S was added at the bottom and its adsorption meassured at different levels (C1…Cn) in the column (Fig.1).

Fig.1 H2S adsorption column: pilot plant.

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Load: The total amount of H2S which can react with iron oxide is a function of H2Sconcentration and reaction temperature. At 22°C, the maximal adsorbtion determined in a single load without regeneration increased from 2 to 25g H2S/100g of pellets with increasing concentrations (Fig.2). After every regeneration step a part of the active reaction surface was covered with adhering sulfure and hence, the potential of adsorption reduced. With the product investigated, the load was reduced by about 15% after every oxydation. With an initial H2S-concentration of 3500 to 4000ppm the total load per 100g of pellets was about 50g H2S (Table 1). In a two-column full-size installation which was designed according to the parameters defined in the pilot-plant experiments for the treatment of about 100m3 of biogas per day, the total load reached only about half that value (25g per 100g pellets). Two parameters were probably responsible for that drop: 1) the ambient temperature on the farm was far lower than 22 C and 2) the gas was saturated with water vapor which condensed in the column and moistened the pellets which got caked.

Table 1: Total load of H2S after Repeated Regeneration Concentration Ambient Dry Pellets H2S Load

of H2S ppm Temperature C kg g g H2S/100g pellets

3500–4000 1100–4000 18–24 3.51 1790 51

20–23 1.4 644 46

Zone of reaction: The span of the reaction zone was essentially defined by the temperature which determined the velocity of reaction of the iron sulfide formation (Fig.3). Other factors such as gas velocity in the column or initial H2S-concentration were of minor importance.

Fig.3 Span of reaction zone in function of ambient temperature

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Fig.2 Adsorbtion of H2S in a single load in function of H2S-Conc. Continuous addition of air: If trace amounts of air are directly added to the biogas, both reactions, the reduction and the oxidation take place at the same time in the column. However, determinations revealed that the zone of reaction becomes increasingly longer without reaching the point of saturation in the lower part (Fig.4). Depending on the ambient temperature, the zone of reaction reached the top of the column within 30 to 100 hours with every concentration of air added from 0.9 to 9%.

Fig.4 Concentration of H2S within the column after 3 resp. hours of reaction

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with bioto which 1% of O2 have been added. 3. SCRUBBING OF CARBON DIOXIDE

Fig.5 CO2 scrubbing column Removal of CO2 increases the energy content of biogas and hence, the storage capacity particularly at elevated pressure as it is required for the utilisation of biogas as tractor fuel. For that purpose a counter-flow water scrubbing column was developped for the purification of 5 to 10m3 of gas per hour. The column had a diameter of 20cm and was filled to a height of 1.3m with plastic saddle bodies (Fig.5). Thanks to the fact, that CO2 is about 25 times better soluble in water than methane, the two gases can easily be seperated. The raw biogas was compressed to approx. 9bar and entered the column at the bottom. The water was sprayed at an equal pressure from the top onto the saddle bodies where the CO2 was disolved. After having decreased the pressure to ambient conditions the gas was released and the water could be recycled. The size of the expansion vessel did not allow an entire regeneration of the water, thus about 10% of fresh water had to be added in order to achieve a constant rate of CO2 disolution.

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The rate of CO2 removal was influenced in decreasing order by the flow rate of water and the gas flow rate (Fig.6). To reach a methane concentration of 85% which is an optimal value to run a dual fuel engine (biogas/diesel), 43litre per minute of water had to flow through the washing column. However with such a high flow rate also the CH4 losses became important with 16%. Thus, from 7.7m3 of raw biogas which were processed per hour, 4.6m3 left the column with a methane content of 85%.

Fig.6 CO2 removal and CH4 losses in function of water and gasflow rates. Beside CO2 and CH4 also H2S is disolved in the washing water. It’s solubility is even three times better than that of CO2. In our experiments the initial H2S concentration was varied from 300 to 6600ppm. The scrubbing reduced the amount by 90 to 95%.

CONTRIBUTION TO COMPREHENSIVE ENGINEERING CONCEPTION OF METHANISATION BASED ON KINETIC APPROACH R.BACHER, F.YEBOUA AKA, M.EL-HOUSSEINI and G.GOMA Département de Génie Biochimique et Alimentaire, Institut National des Sciences Appliquées, ERA-CNRS N° 879, Toulouse, France Summary Biological methanisation of biomass occurs after consecutive reactions (fermentation, acidogenesis, methanogenesis) complicated by semi parallel reaction (reduction of CO2 by H2). The rate of these reactions are described. The critical concentration of salts Na+1, K+, Ca++ which become inhibitory on methanogenesis is high compared with other ones available in the literature. The effect of initial concentration of acetic acid has been demonstrated. Butyric acid concentration up to 20g/l has no toxicity effect on the acetoclastic methanogenesis in continuous fixed bed bioreactor.

INTRODUCTION Methanogenesis has traditionally been viewed as a two-stage process, the acid forming and CH4-methane forming stage (Toerien and Hatting, 1969, Kirsch and Syke, 1971). Bryant (1976, 1979) proposed a scheme that attempts to synthesize informations on methanogenesis from organic matter. In general, the first stage involves species of fermentative bacteria, which, as a metabolic group, hydrolyse complex carbohydrates, proteins and lipids and ferment these products to fatty acids, H2 and CO2. The second metabolic group, called the hydrogen-producing acetogenic bacteria produces acetate, CO2 and H2 from the fatty acids generated in the first stage. The third stage involves the methanogenic bacteria that utilizes the products of the first two stages, mainly acetate, CO2 and H2 to produce CH4 and CO2. Recently, an additional stage was added to this scheme. This metabolic group is called the homoacetogenic bacteria which synthesize acetate using H2 and CO2 and formate (Zeikus, 1979 and Wolfe, 1979). The rates of the hydrolysis and acidogenic reactions are higher than the methane formation rates (Ghosh et al., 1975). There-fore the volatile fatty acids can be accumulated and have an inhibitory effect on the methane forming bacteria if the equilibrium between these stages are not realised (Kroeker et al., 1979). Also, the rates of reactions are inhibited by cations (Na+, K+, Ca++) and toxicity effect is associated with the cation rather than anion portion of the salts (Pfeffer, 1974).

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The present work is aimed to describe the dynamic behaviour of the different consecutive reactions of the biomethanization process, to compare the critical concentration of cations, to demonstrate the effect of initial concentration of acetic acid on the biodegradation of butyric acid and to study the effect of different concentrations of -butyric acids on the acetoclastic and methanogenic bacteria. MATERIALS AND METHODS Two laboratory batch experiments were made up in bottles of 500mL. In the first one, the degradation rate of sucrose, glucose (acid fermentors), lactic, butyric, propionic and acetic acid (methane fermentors) were studied. The second experiment was carried out to state the inhibitory effect of different cations on both acidogenic and methanogenic stages. Different cation concentrations of K+, Na+ and Ca++ (0.15, 0.30 and 0.65mole/L) were used. These cations associate with anions of CL−, NO3− and SO4−− . Glucose (11g/L) and acetate (2g/L) were utilised as substrates in both acid and methane fermentors respectively. The experimental conditions for both two kind of fermentors are described as following : Acidogenesis Methanogenesis Medium: (g/L)

Na2HPO4.12H2O

NaH2PO4.2H2O (NH4)2HPO4.2H2O K2HPO4.2H2O MgSO4.7H2O CaCL2 KCL Tap water pH: 6.0 Temperature: 40°C Inoculum: was taken from a laboratory continuous acid fermenter.

0.42

KH2PO4

6.5

0.18 2.0 0.5 0.4 0.03 0.08 1L

MgSO4.7H2O (NH4)2SO4 NaCL Tap water

3.1 7.5 0.5 1L

pH: 0.7 Temperature: 40°C Inoculum: was taken from the effluent of biogas unit operated with Gowdung.

In order to study methanogenesis from butyrate, another two series of experiment were carried out. The first one, in batch culture to investigate the degradation rate of butyrate alone or mixed with various concentrations of acetic acid (2, 4, 6 and 12g/L). The same conditions used for methane fermenters were applied. For continuous methanogenesis of butyrate a 9L up-flow anaerobic fixed bed (flocor R plastic rings) reactor was constructed. At first, the reactor has been fed for three months with fresh Cow-dung to develop the microbial population of methanogenic process. The reactor operate at hydrolysic retention time equal to 53 hours. The acid medium provided with constant concentration of acetic acid (3g/L), different concentrations of butyrate (from 4 up to 20g/L) and yeast extract (0.2g/L) is used as influent solution. Other operational conditions are the same as mentioned previously.

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Glucose and reducing sugar were measured by glucose analyser model YSI 27 and method of Miller (1959) respectively. Volatile fatty acids were determined by gas chromatography as described by (Yeboua Aka, 1984). RESULTS AND DISCUSSIONS 1. —Kinetic degradation of sucrose, glucose and different intermediate metabolites involved in the biomethanization process The consumption of substrates by microorganisms is a function of fermentation time as shwon on figure 1. Retention time needed to degrade glucose, sucrose and lactic acid is shorter than that needed for fermenting other acids. Lag phase and kinetic parameter are represented in Table 1. The degradation rates were found in the order of:Propionate
Figure 1.: Biodegradation of different substrates involved in biomethanization process.

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Table 1. Degradation rate and lag phase for different formented substrates involved in biomeyhanization process. Substrate Sucrose Glucose Lactate Butyrate Propionate Acetate Parameter 1.00

1.85 0.0266

0.0068

0.0028 0.0039

lag phase 30 hours 20 hours 1.5 days

1 day

4 days 4 days

2. —Effect of different mineral salts on the biological activity of both acid and methane forming bacteria The relation of VFA production per unit of initial sugar added is function of salt concentration as shown in figure 2. The results indicate that the activity of cations is dependent on the nature of the associated anions. At the same cation concentration of all salts used, the inhibitory effect of NO3− is higher than CL− and this increases with higher concentrations of different cations. On the other hand, cations of Na+, K+ when associated with anions of SO4−− have a stimulatory effcct. The second experiment is still going on; the first results indicate that there is no toxicity effect, but we have observed a low inhibition on the acetoclastic methanogenesis. 3. —Methanogenesis of butyrate Biodegradation of butyrate in batch culture is affected by the initial concentration of acetic acid. Main results are described in figure 3 and Table 2. Concentrations of acetic acid up to 6g/L has stimulatory effect on butyrate degradation. On the other hand, acetate concentration excess of 6g/L has an inhibitory effect and this increases with increasing the concentration of acetic acid. Similar result were obtained by Stafford (1982) and Laroche (1983) who found that concentrations of 1g/L and 5g/L has an stimulatory effect on butyrate degradation respectively. On the other hand, Laroche (1983) showed that there was a low inhibition with concentration of 10g/L acetic acid.

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Figure 2: Effect of different concentrations of cation in association with different anions; •—• reference, □—□ CL−, ∆—∆ NO3−, O—O SO4−− The main results obtained from the fixed bed reactor are Summarized in Table 3. Acetate accumulation begins with low initial concentration of butyrate. But butyrate accumulation appears at 10g/L initial concentration. The gas production increases from 1 to 3.5L/L/day with increasing butyrate concentration. On contrary, methane percentage decreases from 82% to 75% when butyrate increases from concentration of 4 to 20g/L./ REFERENCES 1—Bryant, M.P. In Schlegel, H.G. and Barnea, J. (eds). Microbial Energy Conversion, Pergamon Press. p. 107–117 (1976). 2—Bryant, M.P. Theoretical aspects. J. Anim. Sci., 48, 193 (1979). 3—Finck, J.D. These Laboratoire de Génie Biochimique, INSA. Toulouse France (1983). 4—Ghosh, S., Conrad, J.R. and Klass, D.L. J. Water Poll. Cont. Fedn. vol. 47, 30–45 (1975). 5—Kirsch, E.J. and Sykers, R.M. In Hockenhull, D.J.D. and Churchill, A. (eds). Progress in Industrial Microbiology. London. (1971). 6—Kroeker, E.J., Schulte, D.D., Sparling, A.B. and Lapp, M.M.J. Water Poll. Control. Fedn. 51, 518 (1979). 7—Laroche, M. These, Institut National de la Recherche Agronomique de Narbonne, France (1982). 8—Miller, G.L. Anal. Chem., 31, 426–428 (1959). 9—Pfeffer, J.T. Biotechnol. Bioeng., 16, 771–787 (1984). 10—Stafford, D.A. Biomass, 2, 43–55 (1982). 11—Toerien, D.F. and Hattingh, Water Res., 3, 385 (1969). 12—Uribelarrea, J.L. Thèse, Laboratoire de Génie Biochimique, INSA, Toulouse France (1980). 13—Wolfe, R.S. In J.R.Quayle (ed). Microbial Biochemistry. Vol. 21 (1979). 14—Yeboua Aka, F. Thèse, Laboratoire de Génie Biochimique, INSA, Toulouse, France (1984).

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15—Zeikus, J.G. First International Symposium on Anaerobic Digestion. Univ. Industry Center Univ. Collège. Sept. 17–21, Cardiff Wales (1979).

Figure (3): Degradation of butyrate with various concentrations a) Og/L, b) 2g/L, c) 4g/L, d) 6g/L, e) 12g/L. Table (2) ‘Degradation of butyrate, with various initial acetate concentrations; rB=rate of butyratc degradation. C2 (g/l) 0 2 4 6 12 Lag phase (day) 0 0 0 5 10 rB(mg/l/d) 6.7 7.5 8.8 7.1 4.6

Contribution to comprehensive engineering conception of methanisation based on kinetic approach

Table (3) Caracceristics of the fixed bed reactor feeding with different concentrations of butyric acid at retention time of 53 hours Rt C2 g/l feed feed C4 g/l pH C2 g/l . Effluent C4 g/l pH Gas 1/1/day’ % CH4,

53 h 53 h 53 h 53 h 53 h 2 4 7.3 1.1 05 7.4 1.8 82

3 7 7.3 3.0 0.5 7.3 2.2 82

3 10 7.3 6.0 1.0 7.4 2.6 80

3 3 13.5 20 7.3 7.3 7.0 – 1.5 – 7.5 7.4 3.1 3.5 78 75

509

PERFORMANCE OF ANAEROBIC EXPANDED BED REACTORS TREATING MUNICIPAL SEWAGE P.GARCIA, L.J.REDONDO, I.SANZ and F.FDZ-POLANCO Dpto. Química Técnica, Universidad de Valladolid, Spain Summary The performance of two laboratory scale anaerobic expanded bed reactors treating raw domestic sewage has been evaluated over a period of some nine months. The support media used were uniformly sized particles (0.14−0.28mm) of red brick and clay. The temperature changed between , with daily variations of . At a volumetric loading rate of 4Kg COD m−3 d−1 (HTR=4h) the ave rage total COD-reduction was greater than 70%, and the so luble COD-reduction was in the range of 50%. Removal effi ciencies showed very little sensitivity to fluctuations in influent wastewater quality. A very high efficiency of removal of suspended solids was achieved, effluent TSS below 20mg/l were common. The stability of the reactors was very good, they were unaffected by fluctuations in temperature, flow rate, organic loading rate and suspended solids concentration.

1. INTRODUCTION. Municipal wastewater treatment using conventional aerobic technology consumes a great deal of energy and produces large excesses of sludge. The development of new digester types as Up flow Anaerobic Sludge Blanket (UASB) and Anaerobic Expanded or Fluidised Bed (AEB, AFB) reactors could allow the treatment of dilute effluents (ie COD<200mg l−1) (1) (2) (3). Therefore, the general purpose is to develop a new approach to sewage—treatment, that would minimize energy input while producing—energy, and minimize excess biological solids production. The use of the AEB reactor for the treatment of domestic sewage has been studied by Jewell et al. (2)(4) and by Rockey (5). Jewell concludes that the process is effective at low—temperatures with an organic loading rate of 4Kg COD m−3 d−1 and a 75% removal efficiences. Otherwise, the data of Rockey using unsteady-state conditions indicate that the process is unlikely to provide an effective system for the treatment of domestic sewage.

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2. MATERIALS AND METHODS. Two anaerobic expanded bed reactors were used. A diagram of the system is shown in Figure 1. A summary of design charac teristics of both reactors are shown in table I.

Figure 1. AEB reactor Reactor 1 Reactor 2 Diameter (cm) 3 3 Length (cm) 30 30 Expansion (%) 20 20 MEDIA Material Red brick Arlita® Diameter (mm) 0.14–0.28 0.14–0.28 Density (g/cm3) 2.53 1.94 Void fraction (%) 55 57 Superficial velocity (m s−1) 0.14 0.11 Temperature Room Temperature Arlita® is a commercial expanded clay

Table I. Characteristics of the reactors All analysis were determined by Standard Methods. All loa ding rates and retention times were calculated on an empty volume basis that is occupied by the expanded media. The develop ment of the methanogenic biofilm on the support was very similar in both reactors. Domestic wastewater was obtained from a municipal sewer once or twice per week and stored at . A degree of biodegradation occurred in the storage reservoir. Daily fresh feed was prepared and continuously pumped to the reactors, a little biodegradation was also observed. No settled sewage was used, the feed system allowed solids to be pumped to the reactors.

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3. RESULTS AND DISCUSSION. The variation in the experimental conditions of the sewage is shown in Figure 2. A large fluctuation in the COD, (maxi mum=590mg/l, minimum=110mg/l) was observed. This fluctua tion subjected the reactors to varying organic loading rates, so the system never achieved steady state conditions. The variation in the COD of the sewage, and therefore the effluent, is shown in Figure 2. The COD of the effluent was di rectly measured without filtration or centrifugation. The—effluent always had a very low turbidity. An examination of the COD removal versus organic loading rates (Figure 3) showed that, when organic loading rates are lower than 1Kg COD/m3 d , COD removal greater than 80% is—

Figure 2. COD variation easily achieved. With loading rates of 4Kg COD/m3.d (HRT=4h) a COD removal of 70% is achieved.

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Figure 3. The effect of OLR on organic removal efficiency The influence of temperature is shown in Figure 2. In the first period with average temperatures above the COD-re duction was greater than in the second period. The stability of the reactors against temperature changes was very good. They have been operated between with average daily changes of . The suspended solids removal was very high in the whole range of operation. The average TSS-removal was 90%. Morris (6) suggests that the removal of the small particles of sus—pended solids is effected by both physical and biological phe nomena. It is possible that a little settling in the feed reservoir was achieved. The average value of all influent and effluent parameters during the period 245−260 day, are summarized in table II. Gas production rates were not easy to measure due to the size of the experimental system. It is interesting to note the effects of methane and carbon dioxide solubility on ,a gas produc tion rates. Assuming a CH solubility of 33.1ml CH/l water, methane yield of 0.35l CH /g COD and a 70% of COD removal, the lost of methane could be 33% for 400mg/l of influent COD and 66% when the influent COD is 200mg/l. From this analysis it appears that energy recovery potencial for anaerobic systems treating low strength domestic wastewater is further diminished due to soluble methane loss in the effluent.

Table II. Influent and effluent characteristics. Influent Reactor 1 Reactor 2 Loading Rate (Kg COD m−3 d−1) HRT (h) Temperatura Total COD (mg/l) Soluble COD (mg/l) BOD (mg/l) TSS5 (mg/l) VSS (mg/l)

---496 260 305 187 158

3.7 3.2 20 149 -75 22 16

2.7 4.5 20 137 -72 15 13

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7.9 7.8 220 200 Not detectable

7.8 200

3. CONCLUSIONS. The results of this experimental study of the performance of the anaerobic expanded bed reactor suggest that the sys tem would be adecuate for the practical treatment of raw sewa ge at moderate temperatures. The reactors were unaffected by fluctuations in tempera− ture, flow rate and organic loading rate. REFERENCES. (1) GRIN, P.C., ROERSMA, R.E. and LETTINGA, G. (1983). Anaerobic Treatment of raw sewage at lower temperatures. Proceedings of the Anaerobic Waste Water Treatment European Symposium. Noordwijkerhout. (2) SWITZENBAUM, M.S. and JEWELL, W.J. (1980). Anaerobic attached film expanded bed reactor treatment. J. Wat. Pollut. Control Fed. 52, 1953–1965. (3) KOBAYASHI, H.A., STENSTROM, M.K. and MAH, R.A. (1983). Treat ment of low strength domestic wastewater using the anaero bic filter Water Res. 17. 903–909. (4) JEWELL, W.J., SWITZENBAUM, M.S. and MORRIS, J.W. (1981). Municipal Wastewater treatment with the anaerobic attached microbial film expanded bed process. J.Wat. Pollut. Control. Fed. 53, 482–490. (5) ROCKEY, J.S. and FORSTER, C.F. (1982). The use of an anaero bic expanded bed reactor for the treatment of domestic se wage. Environmental Technology Letters. 3, 487–496. (6) MORRIS, J.W. and JEWELL, W.J. (1981). Organic particulate removal with the anaerobic attached, film expanded bed—process. 36th Purdue Industrial Waste Conference. Purdue University. Indiana.

ANAEROBIC STABILIZATION OF AGRICULTURAL AND FOOD-BASED INDUSTRIAL WASTES J.Winter and F.X.Wildenauer University of Regensburg, Department of Microbiology, Universitätsstr. 31, D-8400 Regensburg, FRG. Summary: Anaerobic fermentation of cattle manure (7% total solids) in a mixed tank digester at a HRT of 15d revealed 0.7l biogas/ l.d and a COD-reduction of 18%. When most of the solids were removed by filtration (4% solids left) before digestion only 15% less gas was produced (0.6l/l.d). No improvement was observed when filtered cattle manure was digested in a fixedfilm reactor. Although attachment of bacteria to the red brick material was observed the gas production was only insignificantly higher than in the conventional system (0.64 versus 0.6l/ l.d). Digestion of piggery waste with a solids content of 1.6% at 10d HRT resulted in 58% COD-removal and produced 0.7l biogas/l.d. Undiluted sour whey could be stabilized with 95% COD-reduction and a gas productivity of 5.6l/l.d in a fixed-film upflow loop reactor, operated with pH-controlled whey addition. At a pH of 6.7 a maximum loading of 14kg COD/m3.d was obtained and disturbances by oxygenation or overloading were corrected automatically by the system.

Introduction: To prevent further pollution of the environment, not only sewage sludge and domestic refuse from big cities and rural communities should be extensively treated before final disposal, but also agricultural wastes and wastes based on farm product processing. Especially wastewater from plant and milk processing for human food is highly polluting and needs treatment before disposal, In this contribution we report on the anaerobic treatment of cattle manure and piggery waste in conventional digesters and fixed-film digesters and on the anaerobic digestion of sour whey from cheese production in a pHcon trolled fixed-film upflow loop reactor.

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Materials and Methods: Cattle manure, piggery waste and sour whey were frozen in portions to operate a digester 3–4 days. Cattle manure was homogenized with an Ultraturrax before freezing. Samples were thawed a day before use and stored in a refrigerator. For the digestion of diluted cattle manure (7% solids content), filtered cattle manure (4% solids content) and piggery waste mixed tank digesters (Biostat V, Braun Melsungen, 1.5l) were used, which were operated at 30–33°C. The operation mode was semi-continuously by manual sludge removal and sludge addition once a day, to maintain the desired HRT (hydraulic retention time). Steady state conditions were assumed when the time for 4 HRTs had passed. Filtered cattle manure was additionally digested in a fixed-film digester containing red brick material as a support material for bacterial adhesion. The brick volume was 2l and 2l of cattle manure were initially added to fill the reactor. The reactor was operated in an upflow mode semicontinuously by displacement of digested manure from the top part with fresh sludge from the bottom with a manually operated pump. After feeding, with another pump in an external loop the digester volume was recirculated 3 times to assure complete mixing. The digester system used for sour whey digestion is shown in Fig. 1. The cylindical digester was filled with porous clay material of 1cm diameter and a surface of 21m2. 2l of digested sewage sludge and 100ml of sour whey were added to start the digestion. The whey addition was automatically controlled by a titrator. The sytem was self-supplying and reached its maximum steady state automatically, when the population on the porous clay material was developed. The composition of the biogas and the volatile fatty acids in fresh and stabilized sludge were determined gas chromatographically (Wildenauer et al., 1984). Dry matter, volatile solids, mineral content of sludge, ammonia content and total nitrogen were determined according to standard methods (Deutsche Einheitsverfahren zur Wasser-, Abwasser- und Schlammuntersuchung, 9. Lieferung, 1981, Verlag Chemie, Weinheim). The COD was determined by a micromethod: To 5ml of saturated K2Cr2O7 in 50% H2SO4 in srew vials 1ml of diluted sludge sample was added, screw-capped and heated for 2h at 170°C. The COD was calculated from a phthalate standard after colorimetric determination of the K2CrO4 formed.

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Fig. 1: Fixed-film loop reactor for sour whey digestion Cylindrical reactor (200cm long, 5cm diameter, 3.9 1 volume) with clay beads (1cm diameter, 1.8 1 volume, 21m2 surface), reaction temperature 35°C. 1 recirculation pump; 2 dual peristaltic pump for whey addition (10) and whey removal (9); 3 pump for pHloop; 4 pH probe; 5 titrator; 6 separation device; 7 siphonlike decanter; 8 tubing to gasometer. (From: Wildenauer and Winter, submitted to Appl. Microbiol. Biotechnol.) Results: Composition of wastes: The composition of the wastes used for digestion experiments is shown in table 1. Cattle manure was diluted from 12% to 7% dry matter to avoid clogging of pumps. Part of the cattle manure was filtered to remove the particulate solids before digestion (finally 4% solids left). Piggery wastes had only 2.2% dry matter and sour whey was partially fermented to lactic acid due to its origin from cheese production. No pHadjustment was necessary. The COD, nitrogen content and the fatty acids levels are summarized in table 1.

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Table 1: Composition of raw materials for anaerobic digestion experiments Type of sludge Components Dry Volatile Minerals COD Ntotal matter solids % % % g/l g/l g/l

Acetate Propionate Butyrate pH g/l

g/l

g/l

Cattle 7 5.6 1.5 80 5.1 3.0 4.1 1.0 0.4 7.2 manure, diluted1 4 2.7 1.2 54 4.7 2.2 3.9 1.0 0.4 7.2 Cattle manure, filtered2 Piggery 2.2 1.6 0.6 n.d. n.d. 2.6 3.2 1.8 0.6 6.6 waste Sour 7.8 7.1 0.7 79 2.0 0.7 0.7 0.4 0.0 4.5 whey4 n.d.=not determined; 1undiluted cattle manure contained 12% dry matter; 2Filtration was performed with a grid with pores of 1mm diameter- Manure samples were drawn during winter time, when the diet mainly consisted of roughage and mineral feed; 3The diet for fattening pigsmainly contained barley residues from a brewery; 4From cottage cheese production, undiluted. Storage of raw material was in a deep freezer in portions of the daily demand. Sour whey was continuously pumped into the reactor from a refrigerator. Sour whey additionally contained 6.8 g/l of lactate, the lactalbumine and lactglobuline content was 0.8 g/l. Milk fat could not be detected.

Anaerobic digestion of cattle manure, piggery waste and sour whey: The digestion of cattle manure and filtered cattle manure in conventional mixed tank fermenters and in a fixedfilm digester was compared for COD-loadings between 3.2–11 kg/m3.d or HRTs from 20–10d (table 2). For the same HRT only little more gas was produced from cattle manure in the mixed fermenter as compared to fermenters containing filtered cattle manure. An increase of the active biomass by attachment of bacteria to red brick material as a microbial carrier did not improve the overall digestion over that in conventional systems (table 2) with the same sludge. At 10d HRT from 1m3 untreated cattle manure (12% total solids) 1.4m3 biogas can be produced per day in the conventional mixed fermenter. In the fixedfilm or completely mixed fermenter operated with filtered cattle manure approximately 20% less biogas were produced. Thus, some components in the filter residue must contribute to the biogas. In the mixed tank digesters besides acetate some propionate was found, while the effluent of the fixed-film digester was free of propionate. The overall COD-reduction averaged 18% (table 2), indicating that only part of the ingredients of cattle manure were biodegradable within the desired HRT. For comparison, 58% of the COD of piggery waste were degraded at a HRT of 10d and 0.7m3 biogas/m3.d were produced (table 2). A much better stabilization was obtained for sour whey in a fixed-film upflow loop reactor, operated by pH-control (table 2). A pH of 6.7 was automatically regulated by sour whey addition. The pH-static operation led to an automatic optimization of the whey

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addition. The maximum capacity of the system was reached after 10 weeks. The steady state loading was 14kg COD/m3.d and the gas productivity 5.6m3/m3.d. Within the 10 weeks starting phase a thick biofilm had developped on the surface and in the pores of the clay beads, which made the system resistent to disturbances. A manually caused overloading or oxygenation over 24h could only randomly disturb the population. During overloading the acid production rate increases immediately and the dropping pH switches off the whey pump. A severe overloading is avoided and when the population catches up with the fatty acid degradation the system is self-accomplishing the steady state conditions again. When oxygenation occurs, acetogens and methanogens are severly inhibited or even damaged, while the fermentative bacteria continue to produce acids. Thus, the whey addition is stopped. When the oxygen is removed by microaerophilic bacteria, at least the methanogens in the biolayer on the clay beads are active and produce methane from H2:CO2. and acetate. Volatile fatty acids can be degraded by the acetogenic population and the system reaches its optimum steady state condition within three days. Acknowledgement: This work was supported by the Bundesministerium für Forschung und Technologie, Bonn Literature: F.X.Wildenauer, K.H.Blotevogel and J.Winter, Appl. Microbiol. Biotechnol. 19:125–130, 1984.

Table 2: Performance of cattle manure, piggery waste and sour whey digesters Digester type, substrate Mixed tank, cattle manure (7% dry matter) cattle manure (4% dry matter, filtered) Fixed-film-red clay reactor, cattle manure (filtered)

HRT COD COD pH Spec. gas Biogas Volatile acids in effluent loading removal production productivity acetate propionate butyrate m3/kg m3/m3·d g/l g/l g/l d kg/m3.d % COD 20 15 10

5.5 7.2 11.0

23 7.4 18 7.4 13 7.4

0.50 0.55 0.55

0.62 0.72 0.80

1.1 1.1 1.2

0.3 0.5 0.6

0.0 0.0 0.0

15 10

3.6 5.4

19 7.4 18 7.4

0.80 0.70

0.60 0.67

0.6 0.7

0.2 0.6

0.0 0.2

20 15 10

3.2 4.0 5.4

18 7.4 18 7.4 18 7.4

0.70 0.60 n.d.

0.60 0.64 0.72

1.0 1.5 1.5

0.0 0.0 0.0

0.0 0,0 0.0

Energy from biomass

Mixed tank, piggery waste Fixed-film-loop reactor, sour whey

10 5

520

3.6 58 6.9 0.33 0.70 1.5 1.0 0.0 14.1 95 6.7 0.42 5.60 0.3 0.4 0.0

ANAEROBIC DIGESTION AND METHANE PRODUCTION OF SLAUGHTERHOUSE WASTES A.STEINER, F.X.WILDENAUER and O.KANDLER Bayerische LWF, Freisinger Landstr. 181, 8 Muenchen 45 Summary: Slaughterhouse wastes (2.9% up to 10.5% VS) were fed semicontinuously into 2l fermenters and digested at 35°C and 55°C. Some of the experiments were carried out with added pathogenic organisms (Salmonella typhi. and E. coli) to check the efficiency of disinfection. The fermentation of slaughterhouse wastes led to digestion failure with an organic loading of more than 8.75 kg VS/m3.d caused by enrichment of volatile acids. No differences were found in gas production, percentage of methane and VS or COD reduction in mesophilic and thermophilic digestions. At thermophilic conditions E. coli had a D10-value of 20 mins (Salmonella typhi. D10=30 mins). Only a slow reduction (D10=10.5h) of E. coli occurred at mesophilic temperatures.

Introduction: Because of their high organic matter slaughterhouse wastes are potential sources for methane fermentation. In the FRG (1) about 5×105 t/a of slaughterhouse wastes have to be treated mainly in the form of waste waters with a COD of 1 to 10kg/m3. Previous work (2,3,4,5,6,7) showed that anaerobic fermentation of slaughterhouse wastes under mesophilic and thermophilic (2) conditions is possible with organic loadings (OL) of 0.35 to 6.0kg VS/m3.d. Retention times of 12h to 30d led to a gas production of 0.27 to 0.55m3 gas/kg added VS. This paper reports the results of mesophilic and thermophilic digestion of slaughterhouse wastes under steady state conditions with special reference to high OL and hygienic qualities of the digested sludge. Substrates: The substrate contained rumen and intestine con-tents (13%) 9 manure from the animal buildings of the slaughterhouse (25%), surplus sludge from the aerobic sewage treatment plant (44%) and fat derived from the fat separator (19%). The mixture exhibited a COD of 165g/l, a BOD of 112g/l, a dry weight of 120g/l and a VS concentration of 105g/l with 25% fat and 23% proteins. In order to guarantee waste of constant composition

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throughout the experiments, equal portions of a homogenized mixture were stored in plastic bottles at −20°C until use. The mixture was diluted with tap-water to allow variations in the OL at equal retention times. Table I gives some data of the substrates and the OL. Digersters: Cylindrical, complete mix (CSRT) 2l fermenters (Biostat V, Braun Melsungen FRG) with a filling volume of 1.51 were used. Mixing was performed with 3 propeller type stirrers each about 5cm apart from the others on the central shaft (mixing at 75rpm). COD (g/l) 47 65 93 128 93 165 165 VS (g/l) 28 43 60 81 60 105 105 RT (d) 10 10 10 10 7 12 10 OL (g VS/l.d) 2.9 4.3 6.0 8.1 8.6 8.75 10.5

Table I : Composition of the substrates, retention times and organic loadings Experimental design: Fermentation was carried out in a semicontinuous mode. New feed was added every 24h subsequent to the removal of the desired volume of fermented sludge. Samples for the analytical procedures were withdrawn before the new substrate was added. Biogas was collected in a gasometer and measured once a day. The results shown were determined after the fermentation had reached steady state conditions. Thermophilic fermentations (55°C) were carried out at all OL, mesophilic at OL of 2.9 and 8.1. Analyses were performed according to standard procedures. Results: Reduction of COD and VS High OL led at both temperatures to gradual decrease of COD and VS reduction. At OL of 10.5 VS and COD reduction decreased drastically. The BOD reduction of 72% at OL of 8.6 dropped to 64% at OL of 8.75. The decomposition of proteins was better at 35°C, the decomposition of fat better at 55°C. Thus differences in the overall VS and COD reduction at 35°C and 55°C were not observed.

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Fig. 1: Reduction of COD and VS

Gasproduction Rising the OL from 2.9 to 8.6 (Table II) brought a nearly proportional rise in gas production with constant percentage of CH4 and nearly identical gas yield. Higher OL reduced gas production and gas yield. No significant differences were observed when mesophilic and thermophilic digestions were compared.

Table II: Gasproduction f rom Slaughterhouse Wastes OL (g VS/l.d) 2.9 2.9 4.3 6.0 8.1 8.1 8.6 8. 75 Temp. (°C) 35 55 55 55 35 55 55 55 Gasprod. (l/l.d) 1,79 1,81 2.7 3.8 4.88 4.87 5.4 4. 1 CH4 (%) 68 67 67 67 68 67 65 64 m3 CH4/kg VSadd 0,43 0,43 0.42 0.42 0.41 0.40 0.40 0. 30

Volatile acids and ammonia Concentration of volatile acids in the effluents increased as the OL was raised. At an OL of 8.75 the concentration in the effluent exceeded that in the substrate, but due to the buffering effect of NH4+ (100mmol/l) the pH in the fermenter remained at 7.7. With higher OL the concentration of volatile acids exceeded the ammonia level and gave rise to a drop in the pH to 6.1, which led to digestion failure.

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Fig. 2: Concentration of volatile acids in substrates and fermenter effluents Hygienic qualities

Fig. 3: Reduction of Salmonella and E. coli Under mesophilic conditions (35°C) E. coli showed a decimal reduction time of 10.5h. At 55°C the D10-values of E. coli and Salmonella typhi. were 20 and 30 mins respectively. Thus sufficient hygienization is to be expected at 55°C if the digester is only loaded twice or three times a day, thereby guaranteeing a minimum pasteurization time of 8 to 12h.

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Final remarks: Stable fermentations of slaughterhouse wastes could be obtained with retention times of 7 to 12d and OL up to 8.75. Reduction of COD and VS and gas production were identical at mesophilic and thermophilic temperatures. With gas production rates up to 0.635m3 gas/kg VSadd and 0.425m3 CH4/kg VSadd slaughterhouse wastes proved to be excellent substrates for anaerobic digestion. Treating all waste waters anaerobically would provide about 65% of the energy requirements of a slaughterhouse. Thermophilic treatment would be favourable as pathogenic organisms could be destroyed. Literature: 1) Holzherr, K., Ulrici, W.: Schriftenreihe des Institutes für Nationale und Internationale Fleischwirtschaft, 91 (1981); 2) Lloyd, R., Ware, G.C.: Food Manufacture, 31, 511–515 (1965); 3) Reinhold, F.: Die Fleischwirtschaft, 6, 405–409 (1954); 4) Hemens, J., Shurben, D.G.: Food Trade Review, 29, 2–6,18 (1959); 5) Stephan, B.: Untersuchungen zu einer Biogasanlage am Hamburger Schlachthof, Untersuchungsbericht (1983); 6) De Faveri, L., et al: Poster presented at the 2. Int. Symp. on Anaerobic Digestion, Travemünde (1981); 7) Lindauer, G.D., Sixt, H.: Proceedings of the Int. Conf. on Biomass, 440–447, Brighton (1980).

FERMENTATION METHANIQUE EN DISCONTINU DES FUMIERS A LA FERME: SIMULATION DU FONCTIONNEMENT D’UNE INSTALLATION EN SITUATION REELLE P.A.JAYET Chercheur au laboratoire d’Economie Rurale de Grignon—INRA— FRANCE Résumé Un modèle de simulation du fonctionnement d’une installation de fermentation méthanique des fumiers a été élaboré. Adapté à l’utilisation de l’énergie pour le chauffage et l’eau chaude domestiques, intégrant les disponibilités en biomasse et en travail offertes par l’agriculteur au cours du temps, il devrait permettre de mieux appréhender un grand nombre de situations réelles. Les installations sont ici supposées fonctionner en discontinu. hypothèse classique à l’échelle de la ferme, et pour les types de substrat les plus fréquents en France; en surmontant les difficultés mathématiques ainsi accrues. un tel modèle. à caractère technicoéconomique. devrait aider l’utilisateur dans le choix d’une installation. ll devrait aider aussi à mieux apprécier le potentiel économique de la filière. Un module d’optimisation associé au programme de calcul de la simulation donne un instrument plus performant. Tout en confirmant le faible intérêt économique de la filière, le modèle met en évidence en particulier l’intérêt relatif d’une utilisation du gaz “au fil” de la production. avec un stockage tampon du gaz de faible volume.

1. LE PROBLEME Les études microéconomiques précédentes portant sur la fermentation méthanique des fumiers à la ferme avaient mis en évidence le problème de l’ajustement des besoins et de la production d’énergie au cours du temps [1][2], Mais les périodes retenues [l’année. le mois] pour le calcul économique ne permettraient pas de mesurer l’importance du phénomène. En effet, les besoins en chauffage (cas étudié ici], avec les aléas climatiques. subissent des variations quotidiennes assez sensibles. D’autre part. la forme des fonctions de production du biogaz [figure 1] nous complique la tâche lorsqu’on envisage un fonctionnement des réacteurs en discontinu. A partir d’un ajustement de données de la bibliographie [3], nous proposons une forme

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analytique de la production cumulée en fonction du temps et de la température pour un cycle de production :

T: temperature [°c] t: temps [semaines] P: production cumulée de biogaz [m3N/kg MOI] P∞=.43; production cumulée à t—∞

[figure 1] production instanée de biogaz Le gestionnaire d’une installation de fermentation doit pouvoir décider à tout instant de la charge. de la mise en fonctionnement, de l’arrêt ou du déchar-gement des cuves de fermentation. Cela en fonction de ses disponibilités en temps de travail. en biomasse. de la capacité de son installation et de ses besoins en énergie. Une bonne connaissance de l’exploitation agricole est donc nécessaire. et tout modèle d’analyse doit être asez souple vis à vis de ces caractéristiques pour prétendre à une certaine généralité. ll importe aussi de définir un “signal” qui dicte au gestionnaire la décision préférable qu’il peut prendre vis à vis de l’exploitation des cuves. Interpretable mathématiquement, ce signal, équivalent à une décision de gestion. pourra être intégré à tout modèle d’analyse de notre problème. La finalité de notre étude étant d’évaluer l’intérêt économique de la filière, il s’agit pour nous de retenir tout élément ayant une incidence sur l’investissement ou le coût de fonctionnement, imputable à l’insertion d’une installation de fermentation dans une exploitation agricole. Face à la complexité de l’interaction technicoéconomique, deux hypotheses sont proposées : – les éléments constitutifs de l’installation de fermentation, ayant un rôle direct dans le problème d’ajustement soulevé en préambule. sont ici limités aux digesteurs, à la capacité de stockage du gaz, à la puissance et au rendement de la chaudière brûlant le biogaz [figure 2]. – on suppose que l’insertion de cette installation n’a pas d’effet indirect sur l’économie de l’exploitation agricole. c’est-à-dire qu’elle n’a pas d’autre effet que la seule modification de la dépense d’énergie domestique. En particulier. on admet que la valorisation agronomique globale du fumier reste inchangée. qu’il y ait fermentation ou non [4]. 2. SIMULATION ET OPTIMISATION: LE MODELE PROPOSE La méthode d’analyse retenue est fondée sur la simulation du fonctionnement de l’ensemble [digesteurs, stockage de gaz, chaudière] par rapport à son environnement

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[temperature extérieure, travail et biomasse disponibles. prix de l’énergie substituée…]. L’intervalle de temps au bout duquel les variables de la simulation sont modifiées est de préférence la journée: un intervalle “plus grand” ne permet pas de tenir compte des aléas climatiques et des variations de la production instantanée de biogaz ; un intervalle plus court conduirait à des difficultés de calcul thermocinétique. A chaque période, sont effectués des bilans d’énergie. de biomasse, de travail. de l’état du stockage [figure 3], La règle de décision quant au fonctionnement d’un digesteur consiste à décider du chargement, du démarrage, de l’arrêt et du déchargement de celuici. Une règle est choisie pour toute la durée de la simulation. Un ensemble de decisions possibles est propose. En particulier, pour l’arrêt d’un digesteur, citons deux cas extrêmes. 1. Si l’on veut maximiser l’énergie produite par unité de biomasse disponible, la règle de décision est d’arrêter le digesteur si la consommation c quotidienne pour son réchauffage dépasse la production p [le “signal” est alors calculé. comme la différence . où est le temps de séjour courant]. 2. Si l’on veut maximiser l’énergie moyenne produite par unite de temps, la règle de décision est alors fixée par le signal [p production cumulée pour le cycle de durée , p production quotidienne, Co[t] coût initial de chauffage à la date , to instant de démarrage du cycle courant]. Pour compléter cette analyse à caractère descriptif, un calcul d’optimisation est proposé selon le principe suivant. Celui qui décide d’investir dans une telle installation doit pouvoir juger de l’efficacité de la solution qu’il aura choisie relativement à ces possibilités de choix. Efficacité que nous évaluerons selon deux critères au choix : 1. maximisation du taux de substitution du combustible classique par le biométhane pour les besoins en chaleur domestique. 2. minimisation de la dépense moyenne annuelle actualisée relative à ces besoins. Parmi l’ensemble des paramètres de notre modèle initial, une sélection de variables est opérée. variables par rapport auxquelles sera effectuée l’optimisation. A chaque valeur de ces variables. la fonction d’objectif est calculée par le modèle de simulation. L’idée générale de l’algorithme est précisée [figure 4]. 3. RESULTATS ET LIMITES Le modèle est concrétisé par des programmes informatiques écrits en FORTRAN. L’ensemble logiciel fonctionne actuellement sur du matériel CII-HB (DPS-8, système d’exploitation MULTICS]. Ce modèle, exploité avec les conditions réelles correspondant à l’élevage bovin de l’Ouest de la France. nous permet de tirer quelques enseignements. Tout d’abord. même dans un cas d’excès de biomasse disponible. la limitation du volume de stockage de gaz conduit à une substitution partielle du combustible classique par le biométhane [ne dépassant pas 70% pour 100m3de stockage]. L’intérêt économique optimal conduit même au choix d’un stockage minimal malgré une chute sensible du taux de substitution [<50 ou 60% selon que la durée de vie des cuves est de 10 ou 15 ans].

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Plus précisément, si optimum énergétique [en] et optimum économique [ec] s’accordent pour limiter le nombre de cuves [1 ou 2], augmenter au maximum la charge du réacteur. i1 est plus difficile de conclure pour le choix de la température de fermentation [en général T*ec
Fig. 1: Fonction de production de biogaz pour un cycle Production de fonction du temps a differentes voleure de La temperature BIBLIOGRAPHIE [1] REQUILLART [V.] [1980]. Le biométhane: les problèmes liés à sa production à la ferme. Mémoire de fin d’études I.N.A.-P.G.—I.N.R.A. Laboratoire d’Economie Rurale de Grignon.

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[2] FLORENTIN [J.][1981]. Analyse de l’ajustement production—consommation d’une installation de fermentation méthanique à la ferme. Mémoire de DEA—INSTN—INRA— Laboratoire d’Economie Rurale de Grignon. [3] ZELTER [S.Z.] et coll. [1978]. Fermentation méthanique en discontinu des déchets agricoles. INRA—BERTIN—Compte-rendu d’une recherche DGRST Comité VEDA—Station d’élevage porcs INRA—Jouy-en-Josas. [4] JUSTE [C.] et coll. [1981], Influence de la fermentation méthanique sur la valeur fertilisante de divers déchets organiques. Académie d’Agriculture, 13 Mai 1981., pp. 782–790.

Figure 2—Schéma de principe du fonctionnement du système

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Figure 3—Principe du calcul de simulation

Figure 4—Principe de calcul d’optimisation sous contraintes

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THE PRODUCTION OF METHANE FROM BIOMASS IN THE UNITED STATES: ECONOMICS, TRADEOFFS, AND PROSPECTS J.R.FRANK AND T.D.HAYES GAS RESEARCH INSITUTE P.H.SMITH UNIVERSITY OF FLORIDA Summary Methane produced from dedicated biomass facilities can play an Important role in supplying a significant fraction of future methane demand in the U.S. if improvements can be made which reduce methane costs between $5 to $7/GJ at the city-gate. Both applied and fundamental research focused on specific reactor and plant systems will be needed if this goal is to be achieved. A systems approach is used which results in a continuous assessment of research progress and requirements and aids in the development of cooperative research efforts. In 1983, supplemental supplies constitute approximately 6 percent of the U.S. gas consumption (1). A recent study indicates that the availability of gas from the conventional gas resources in the lower contiguous 48 states will continue to decline and that supplemental gas supplies (e.g. foreign imports, Alaskan gas, coal gas and LNG) will provide an increasing percentage of the gas that is used (1). If only currently available technologies are utilized, it is estimated that supplements will provide almost 25% of the U.S. gas supply by 2000 and 40 percent by 2010 (1). If new technologies are developed providing lower cost unconventional natural gas, gas from advanced coal gasification processes and methane from biomass, these sources will become major supplements. Another study that considered the potential Impact of biomass-to-methane systems indicates that if pipeline quality methane from biomass could be available at the city-gate for $6.80/GJ (in 1983 levelized constant dollars), by the years 2010 and 2030, a gas demand could exist for up to 1 quad (1.06×109 GJ) and over 4 quads (4.2× 109 GJ) respectively (K.Darrow, personal communication). This study assumed that GRI’s research in producing gas from unconventional gas sources and coal gasification would be successful. If a price closer to $5/GJ can be attained or the promise of these latter technologies is not fully realized, the Impact of biomass could be significant much earlier. These estimates do not include the potential nearer term impact of up to 1.8 quads (1.9×109 GJ) of pipeline quality methane which may be contributed from non-agricultural wastes (2).

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To make a significant energy impact, substantial amounts of land must be available for energy crop production. In the United States, it has been estimated that at least 60 million hectares could be used to produce methane from energy crops (2). If 14 million hectares (or 10% of the principal cropland in the United States) were utilized for energy crop production, from 2 to 5×109 GJ of methane could be produced if biomass yields from 20 to 45MT/ha-yr and a conversion efficiency of about 60% (0.28m3 CH4/Kg biomass) could be sustained. Though large amounts of land could be available for energy crop production on a national scale, it is necessary to determine what land is available for local facilities. To answer this question, it is Important to determine what facility outputs are required for a dedicated methane from biomass facility. According to site specific evaluations of several methane-from-biomass systems, the economy of scale is achieved at sizes around 106 GJ/year (3). This means that an economy of scale exists for methane from biomass systems which is 10 to 100 times smaller than for production-scale coal gasification facilities, 1 to 3 times more than the output of some of the larger landfill gas operations, 10 to 100 times larger than most U.S. municipal waste treatment facilities in which methane is a byproduct, and considerably larger than single-farm agricultural waste systems which may produce less than 1000GJ per year. Analyses of land availability at specific sites suggests that facilities producing 106 GJ/year can be supported (4, 5). In one study, the Florida Lake Apopka Natural Gas District was mapped and analyzed for land use. This district is an area of 175,000 hectares. A survey showed that 8,100 hectares of land and 13,200 hectares of freshwater are available for siting a biomass-to-methane system. No competing uses could be identified for these areas. Support of a facility producing 106 GJ/year would require either 2100 hectares of napiergrass with a biomass yield of 45MT/ha-yr or 1,800 hectares of water hyacinths with a biomass yield of 75MT/ha-yr. Biomass yields of napiergrass exceeding 57MT/ha-yr have already been observed in small field plot experiments in north Florida. Biomass yields of water hyacinths of 106MT/ha-yr in small laboratory systems and about 75MT/ha-yr in 1/10 hectare channels have been recorded (6) . Yield improvements have been attained during the past 3 to 4 years by improving crop management practices and variety selection, and not by breakthroughs in advanced biotechnology. A biomass-to-methane system sized to produce 106 GJ/yr would have satisfied almost all of the 1982 gas demand of the Lake Apopka District (4). During periods of low gas demand, the excess production would be compressed and sold to the local transmission pipeline company. Such systems could be attractive sources of gas for municipal and distribution gas companies that service a local market. A major thrust in converting biomass to pipeline-quality gas is the development of high-solids, anaerobic reactors, that are capable of converting grasses to methane with minimum energy inputs and minimum materials handling requirements. The research focus is on the engineering and microbiology of a leachate bed/packed bed staged reactor system (Figure 1) in which the rate restricting hydrolysis step occurs in a low cost, 20 to 60 day solids retention time (SRT) reactor vessel and gas production occurs in a high performance methanogenic reactor. While this work is at a fairly early stage in the United States as compared to Europe, research issues for this system Include biomass

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compressibility, inhibition, phase separation, process regulation, and the achievement of a high methane content in the biogas. Other work is focusing on adapting

Figure 1 ADVANCED CONVERSION TECHNOLOGIES

Figure 2

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upflow solids reactors to particulate feeds, such as aquatic plants, which have a relatively low solids content. Results to date indicate that higher yields (15 to 25%) and rates(10 to 20%) than with a stirred tank reactor (CSTR) are realized. Research issues include energy savings accomplished by solids/juice separation of the feed and two stage processing (7). Another key component of the GRI program is the development of systems models which relate complex data from a number of disciplines to an economic evaluation of research accomplishments and permit simulations of crop management and conversion which can be empirically tested. As a first step in this iterative process, a system model called BIOMET has been developed at the University of Florida which describes crop growth, biomass handling and management, costing of conceptual systems and economics. Initially, growth models and conversion models for napiergrass and water hyacinths have been included in BIOMET. Other promising feedstocks including sorghum will be added. The development of BIOMET is described in more detail in the companion paper by Mishoe in this symposium. At the present time economic estimations by BIOMET are very preliminary, but iterative improvements are expected to provide expanded data bases, validation, and more detailed algorithms and Improve its usefulness in estimating gas costs. It is now used to simulate crop growth and management strategies which can be tested experimentally. Programmatically, it is useful as a tool for estimating the impacts of various trade-offs and research approaches. For example, using this methodology it has been estimated that significant reductions in gas cost may be achievable through longerterm research. Areas targeted for long-term research have the potential of reducing gas costs significantly through improved feedstocks and better system control. Figure 2 shows the relative impacts of various system Improvements that were estimated with the current BIOMET program considering conceptual designs developed in site-specific studies. Dollar cost estimates assume sustained yields for napiergrass of 60MT/ha-yr and .31M3/Kg VS added. It is estimated that a 35% reduction in end product gas costs might be achieved if the methane yield of the napiergrass can be increased from .31 to .44M3/Kg VS added by improving both plant composition and the conversion process, chemical inputs reduced by 70%, and planting costs reduced 90% (e.g. tissue culture propagation). A 30% reduction in end product gas costs of conversion/gas cleanup is estimated if methane yields of .44 M3/Kg VS added could be attained by both feedstock and conversion process Improvements, solids retention times reduced from 60 to 30 days and material costs reduced 15%, and methane content in the gas is increased to over 90%. In addition to work on variety selection, crop management, and process development, longer term work on the tissue culture and propagation of grasses like napiergrass, sorghum and other potential energy crops and cropping systems is underway. Also, it has been demonstrated that the addition of cellulase can enhance hydrolysis rates and yields in a small bioreactor (6). Genetic engineering approaches are now being focused on cellulytics important in the high-solids reactor systems (6). Other related work on the lifecycle of Methanosarcina mazei may lead to control of the aggregation and disaggregation of its cyst-like structures and enhanced control of acetate metabolism (9). A major emphasis has been placed in these programs on interdisciplinary cooperation. It is anticipated that research thrusts will continue to focus on the development and improved understanding of high solids conversion processes, Improving the biomass and methane yields of promising biomass feedstocks through improved crop management and

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genetic selection, the application of new biotechnologies to promising production and conversion systems, and continued development, validation, and evaluation of the system models. REFERENCES (1) HOLTBERG, P.D., et al. (1984). 1984 GRI Baseline Projection of U.S. Energy Supply and Demand, 1983–2010. Gas Research Insights, (October 1984). (2) LIPINSKI, et al. (1983). Review of the Potential for Biomass Resources and Conversion Technology. Final report to Gas Research Institute. GRI -83/007. (3) BIRD, K.T. and A.B. ASHBY. (1984). Recent Economic Results of Converting Biomass to Methane. IGT Symposium on Energy from Biomass and Wastes VIII. Ed. D.Klass. (4) WARREN, C.S. et al. (1984). The Methane from Biomass and Wastes Program: Evaluation of the Lake Apopka Natural Gas District. Gas Research Institute Topical Report. GRI 84/0015.1. (5) HINTON, S.W. and C.S. WARREN (1985). The Methane from Biomass and Waste Program: Biomass Resource Assessment Belle Glade Area. Gas Research Institute Topical Report (In Press). (6) SMITH, W.H. (1985). Methane from Biomass and Wastes: Annual Report for 1984. Gas Research Institute Report (In Press). (7) CHYNOWETH, D.P. et al. (1984). Biogasification of Water Hyacinth and Primary Sludge. Proceedings of the International Gas Research Conference. Government Institute, Inc. (In Press). (8) LIU, Y. et. al (1985). Methanosarcina mazei LYC, A New Methanogenic Isolate which produces a disaggregating enzyme. Applied and Environmental Microbiology. (In Press)

ANAEROBIC DIGESTION OF PIG MANURE RESULTS ON FARM SCALE AND NEW PROCESS C.AUBART, F.BULLY Research Laboratory on Fermentation BIOMAGAZ Aspach le Bas—68700 CERNAY—France— Tél. (89) 48.96.11. Summary The economical profit of pig manure biogas plants requires an optimisation of the process. Since July 1981 we carry out a scientific follow up of a 200m3 experimental biogas unit (completely mixed) which is loaded with a pig manure daily flow of 18.5m3 . The capacity of this plant has been determined by the results of experiments made on six litre digesters (completely mixed). The net production of biogas is processed in a gas engine generator without treatment. It produces 71,958Kwh/year. Chemical oxygen demand decrease and deodorisation occuring in pig manure anaerobic digestion permit to suppress the aerobic treatment and economize 94,900Kwh/year on the consumption of electricity. Complementary laboratory experiments were carried out to decrease the retention time and in consequence the digester capacity and investment cost. Retention times tested are 7.5 and 5 days. Results show that to obtain about same performances on energy production and pollution control a digester capacity of 139m3 is sufficient. A digester capacity of 93m3 permits to obtain 86% of the precedent production. From the results presented above, we can conclude : – first: possibility to decrease investment cost of biogas plant, – second: possibility with the same system to treat the daily flow of a very large pig farm. The new process permits to decrease investment cost and to increase biogas production and the annual economy.

INTRODUCTION The energetic aspects of an anaerobic unit for biogas production (useful capacity 200m3) have been presented (C.AUBART, F.BULLY, 1984). The digester is functionning in a pig farm (3.000 pigs) without break since July 1981. The retention time is 10.8 days and the annual mean biogas production is 208m3/day. The biogas is used in a generator set

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(35Kva) which produces annualy 71,958Kwh. The electricity consumption of the previous aerobic process is 95,000Kwh/year, which present now an economy. This biogas unit gives entirely satisfaction on the technical point of view. However, laboratory studies are carrying out to decrease size of the digester and in consequence the investment cost and to increase results obtained from completely mixed digesters. The used digester is a new process and the patent is in writing elaboration (second generation). The scientific approach has been previously presented (C.AUBART, 1982). Three different pig manures are tested. The characteristics are described in table 1. Two retention times are used on the laboratory digesters : 7.5 and 5 days. 1. LABORATORY RESULTS WITH LOW RETENTION TIMES It has been showed that the size of digesters don’t affect results between laboratory and industrial scale digester (C.AUBART, JL, FARINET, 1983). The results are indicated in table 2. We show that the productivity increases regularly in terms of the loading rate increase with completely mixed digesters. On the other hand, the biological yield decreases in terms of retention time from: – 7 to 8%, when biological yield is described in 1 gas. kg−1T.S. input – 13 to 14%, when biological yield is described in 1 CH4.kg−1 V.S. input – 12 to 13%, when biological yield is described in 1 gas.kg−1 V.S. input These results are constantly raising during fourth months of studies. A flushing bacteria effect with the decrease of retention time seems to explain the lower results on biological yield. But the functionning of the digester is stable during this study. The percent of organic compounds decrease is lower with shorter retention time. When we diminish the retention time in digester, the organic matter is less destroyed. This results indicate that it is possible to use shorter retention time than 10 days, but with smaller yield. These observations conducts us to perform a new process for anaerobic digestion of manures. Others studies show that methanogenesis for animal wastes is not the limiting step in anaerobic digestion (C.AUBART and al., 1984). The new process permits to increase the performances of the first bioconversion steps: hydrolysis and acidogenesis. The results are described in table 2. The productivity of the new process is higher than the productivity of completely mixed digesters: +36% for a retention time of 7.5 days and the same thing for the biological yield: +31%. The decreases of organic compounds are cleanly improved. The consequences on development of this new process are examined in part II. 2. RESULTS EXTRAPOLATION TO INDUSTRIAL SCALE In this study, the productivity is corrected in terms of the pig manure total solids content in the pig farm, 3.5%, the different characteristics of tested pig manure having an effect upon productivity. Table 3 presents interests in the decrease of retention time and in the new process: – first: decrease of investment cost,

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– second: increase in annual economy for the new process. The annual economy is calculated using previous electricity consumption of aerobic treatment in the pig farm and the net biogas production used in the generator set according results presented by C.AUBART and F.BULLY, 1984. With the completely mixed digester, according an investment basis of 100 for the digester unit of useful capacity 200m3 we show that the decrease of retention time permits a decrease of investment cost of : – 30% with a retention time of 7.5 days – 37% with a retention time of 5.0 days But the net annual economy decreases: – 3,000FF 84 with a retention time of 7.5 days – 5.500FF 84 with a retention time of 5.0 days The new BIOMAGAZ process permits a lower investment cost (decrease of 33%) and a taller annual economy: +13,500FF 84. CONCLUSION The application of biotechnological researchs and fundamental studies on bioconversion mechanisms have permitted to perform a new process. The new process does not involve annual running cost and the investment cost is lover. The obtained results indicate that improvement in pig manure anaerobic digestion can be brought. Consequences on investment cost and economy project in the future the development of this technology. REFERENCES (1) AUBART, C., Mise au point industrielle de production d’énergie par méthanisation des déchets agricoles et des résidus agro-alimentaires. Expose CCE, Wageningen, 3 mars 1982. (2) AUBART, C., BULLY, F., Development of installations for the production of biogas from stock-farming waste. Anaerobic digestion and carbohydrate hydrolysis of waste. Elsever Applied Sciences Publishers, pp. 318–322, 1984. (3) AUBART, C., FARINET, JL., Anaerobic digestion of pig and cattle manure in large scale digesters and power production from biogas. IGT SYMPOSIUM “Energy from Biomass and Wastes VII”, Orlando, 24–28/1, pp. 741–766, 1983 (4) AUBART, C., BULLY, F., REISINGER, O., Anaerobic digestion of mixed animal wastes/Biogas production and approach of bioconversion mechanisms. Poster session, Bio Energy’ 84, Göteborg, Sweden, June 18–21, 1984.

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Table 1 CHARACTERISTICS OF TESTED PIG MANURE STUDY Retention time days Total solids % Volatil solids % C.O.D. mg02/1 Total solids (supernatant) % Volatif solids (supernatant) %

COMPLETELY MIXED NEW PROCESS 7.5 3.70 2.71 45,312 1.14 0.60

5 3.37 2.65 34,459 0.84 0.49

7.5 3.97 2.83 49,535 1.30 0.73

Table 2 LABORATORY RESULTS DIGESTERS

B.U. C.M.

L.D. C.M.

L.D. C.M.

L.D. N.P.

Retention time days 10.8 7.5 5.0 7.5 Productivity 1 gas. 1−1 dig.d−1 1.04 1.46 1.86 2.28 1 CH4.1−1dig.d−1 0.72 1.0 1.26 1.56 Biological yield 1 gas. kg−1 T.S. 321 296 276 432 1 CH4.kg−1 V.S. 320 277 238 415 1 gas.kg−1 V.S. 461 404 352 606 T.S. Decrease % 34 30 28 49 V.S. Decrease % 39 37 34 57 C.O.D. Decrease % 43 41 36 64 B.U.: Biogas Unit (useful capacity 200m3) C.M.: Completely mixed L.D.: Laboratory digesters N P.: New process

Table 3 RESULTS EXTRAPOLATION TO INDUSTRIAL SCALE DIGESTERS

B.U. L.D. L.D. C.M. C.M. C.M.

L.D. N.P.

Retention time days 10.8 7.5 5.0 7.5 Productivity 1 gas. 1−1 dig.d−1 1.04 1.38 1.93 2.01 Useful capacity of digester m3 200 139 93 139 Daily biogas production m3 208 192 179 279 Investment basis 100 70 63 67 Annual economy FF 84 75,000 72,000 69,500 88,500 B.U.: Biogas Unit (useful capacity 200m3) C.M.: Completely mixed L.D.: Laboratory digesters N.P.: New process

AN ECONOMIC APPROACH TO BIOGAS GENERATION AND USE D.J.Picken Leicester Polytechnic Summary The economic returns on the production of biogas in developed countries have been generally disappointing. Many studies have shown that even when the problems of digester design and operation have been satisfactorily solved the payback from the use of biogas has been well below expectation. Sometimes this has been due to plant unreliability or incorrect operation. More often it has been due to the continuous production of biogas not matching the fluctuating demands for energy near the plant. This is possibly due to the digester system being designed to deal with the available biomass supply. An alternative approach to design is to consider the energy needs and possible savings and match this to the investment available for building the digester system. This paper attempts to show the results of such design considerations. Before any sensible costings can be made it is essential to decide what base load of continuous power can be usefully used at or near the digester site. This can include the generation of electricity to sell back to the electricity supply company, but the price offered is generally not attractive. Having decided on the power requirement from the digester, an estimate must be made of the value of this power in terms of annual income. This can best be calculated by taking the cost of the fuel supply which is to be replaced, or which offers the most likely alternative to biogas. Depending on the particular location of the plant, and on the type of energy to be used, this can either be solid fuel, natural gas, mains electricity or diesel oil. Unfortunately each of these fuels is normally priced in a different way, and the price will vary with location as well as from one year to another. It is a fairly simple calculation however, to put fuel costs in terms of cost per kW hr so that direct comparisons can be made in UK the following costs are normal:– (i) Electricity cost=£0.03/kWhr (average) If biogas is to be used to generate electricity then the amount of biogas required is that which when used as a fuel for an engine generator set to produce electricity. As a general rule we may take the efficiency of such a set as 20%. Thus biogas energy required=5×electrical energy required. Biogas value per kW/hr=£0.03/5

=£0.006 per kWhr. Thus if biogas is to replace electrical energy its annual value is

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£0.006×8760 per kW =£52.56 per kW power Now if we assume that the specific energy of biogas is 25MJ/m3 then the gas production rate to produce a power of 1kW is /day

=3.46m3

Each m3 of digester capacity will normally produce between 1 and biogas per day. If we assume a well designed digester producing times its volume of biogas per day, then per kW output its volume will be 2.3 in /kW. We can therefore expect an annual return (saving) of £52.56/2.3 =£22.85 per m3 of digester volume (ii) If the fuel to be saved is diesel fuel (i.e. in an existing diesel generator), for which a typical cost is £1 per gallon, taking the energy content of diesel fuel as 44MJ/kg, and taking 1 gallon as 3.36kg we arrive at a price of diesel fuel of £0.024/kWhr (annual value £212.8 per kW). The same calculation as above suggests an annual return on biogas as £92,52 per m3 of digester volume. (iii) A typical cost of natural gas is £0.11 per m3 (UK prices). The best biogas has a calorific value of about 70% of natural gas. Thus its value is £0.077 per m3. Thus its annual return is £0.077×365×1.5 per m3 digester volume =£42.1per m3 digester volume (annual value £96.80 per kW). With these figures it is easy to calculate the maximum cost of a digester system for a given pay-back time, Thus using Graphs 1 and 2 it is possible to find the limits of cost for a particular proposed installation. e.g. (1) A farm has a requirement for a constant 20kW of heating, at present supplied by gas oil: A Pay back time of 3 years is required. From graph 1 digester size must be 50m3 Maximum cost of digester system is £220/m3. i.e. system must cost less than £11,000. e.g. (2) An alternator has a constant electrical demand of 20kW and requires an energy pay-back of 3 years. Digester size must be 230m3. Digester cost must be less than £70/m3. Digester system must therefore cost less than £16,100. Note that although pay-back time is relatively short, no allowance has been made for maintenance, or breaks in demand. In particular the costs are for the whole system (including pumps, pipework, enginegenerator sets etc).

An economic approach to biogas generation and use

Fig. 1

Fig. 2

543

METHANE FROM BIOLOGICAL ANAEROBIC TREATMENT OF INDUSTRIAL ORGANIC WASTES R.Campagna, G.Del Medico, M.Pieroni Istituto G.Donegani S.p.A., Via Fauser, 4-I 28100 Novara (Italy) Organic wastes of various industrial origin were char acterized, desk evaluated and then tested in batch di gesters, either alone or in codigestion with other wastes, at the aim to check their amenability to anaerobic biotreatment. Finally, microorganisms were gradually acclimated and fed, in bench scale anaerobic digesters, with most of these wastes. A good agreement was obtained between results from batch and continuous tests. Each industrial waste was found to be a unique case but generally it was concluded: (I) primary sludges from wastewater treatment plants are seldom bioanaerobically treatable; (II) secondary (i.e. biological) sludges from well operated wastewater treatment plants are often amenable to anaerobic biotreatment, with the same degree of gasification and specific rate of reaction of secondary sludges of domestic origin; (III) organic process wastes and wastewaters frequently can be treatable and, if so, with high yields; (IV) anaerobic co-bio treatment of wastes of different origin is often bet ter than the separate treatments.

1. INTRODUCTION Anaerobic biological purification plants are becoming more and more widespread and they could be safely and economically applied to a broader class of organic wastes of industrial origin. The wastes considered in this work included: – primary sludges from industrial wastewaters treatment plants; – secondary sludges, as above; – organic industrial process wastes and wastewaters. Products were first characterized, desk evaluated and then tested, with controls, in batch digesters, fig.1, to check their amenability to anaerobic biotreatment. The most of these wastes were also semi-continuously fed to laboratory completely mixed mesophilic anaerobic digesters, fig.2, allowing for the acclimation of microorganisms.

Methane from biological anaerobic treatment of industrial organic wastes

545

2. RESULTS The experimental main results obtained are listed in tab. I and II. Each waste was found to be a unique case but the fol. lowing general remarks can be concluded: – primary sludges from industrial wastewaters treatment plants are seldom bioanaerobically treatable as such; sometimes major pretreatments (dilution, washing, hydrolisis, specific toxic removal, etc.) may remove the cause of inhibition and/ or improve the bioanaerobic treatment but are usually expen sive. – Secondary (i.e.biological) sludges from well operated industrial wastewaters treatment plants are, instead, usually bio treatable as such or only with minor pretreatments; their kinetics and degree of gasification are in the same range of those of domestic origin. – Organic industrial process wastes and wastewaters frequently can be treatable and, if so, often with high yields. – Anaerobic co-biotreatment of wastes of different origin is almost always better than the separate treatments.

3. DISCUSSION Biological anaerobic treatment can be applied to a wide range of industrial organic wastes, obtaining useful methane while reducing pollution load. Industrial factories have, or may rapidly have, the neces sarily expertise to do so; the methane produced could be entirely used for other more useful purposes than that of digest; er heating, having for this waste-heat to use; furthermore, the methane in the developed biogas is usually much less than that required (and commonly used) for the factory activities and so the biogas could be used as such or only with minor pre treatments in the factory utilities. An improved stability to the process is obtained if wastes of different origin are biotreated together (co-biotreatment); important is the choice of the plant location, its size and its integration with other nearby existing facilities; other advantages include: – more than proportional methane production, due to the positive synergistic effects of a more complex and better balanced environment; this leads also to: – minor pretreatments need, due especially to the dilution and, often, to the complementarity effects; – savings in chemicals to be eventually added; – minor posttreatments (especially for N and P) eventually required.

Energy from biomass

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TAB. I-MAIN CHARACTERISTICS AND RESULTS OF THE WASTES TESTED WITH BATCH DIGESTERS waste origin CODO,total Kg×m−3 Slaughterhouse conc. wastewater Wool scouring (1st factory) ww Wool scouring (2nd factory) ww Polypropilene yarn production ww Primary sludge from chemical (acrilate deriv.) ww treatment Secondary sludge, as above Secondary sludge from domestic ww treatment (as control) Mixture 1:1 by vol. of sec, sludges from domestic and chem. wws treatment Primary sludge from complex chemical industries ww treatment Washed primary sludge, as above Secondary sludge, as above Washed secondary sludge, as above Mixture 2:1 by vol. of primary and secondary sludges, as above Mixture 2:1 by vol. of washed primary and washed secondary sludges, as above Mix.1:1:1 by vol. of sewage sludge, washed sec sludge as above and waste refect food Conc. ww from pharmaceutical industry

Maximum Need of long CODo,total acclimation gasification time? %

Need of Inhibition? maior (at higher dilution? concentr.)

196.0

65.

no

yes

moderate

55.9

50.

no

no

weak

51.7

60.

no

no

weak

38.7

70.

no

yes

strong

71.5

10.

yes

yes

strong

25.0 18.2

32. 38.

no no

no no

weak none

21.6

38.

no

no

none

3.35

0.

yes

yes

strong

2.53

0.

yes

yes

strong

5.3 5.16

0. 20.

yes no

yes no

strong weak

3.18

0.

yes

yes

strong

2.58

5.

yes

yes

strong

27.2

50.

no

no

none

8.0

80.

variable

variable

variable

Methane from biological anaerobic treatment of industrial organic wastes

547

Recovery ww, as above 11.7 45. no yes strong Solvent distillation ww, as above 25.5 100. no yes strong Cephalosporin micelia waste, as above 245. 70. no yes weak Tetracycline micelia waste, as above 200. 15. no yes strong Primary sludge from pharmaceutical industry ww treatment (1st batch) 6.3 15. yes yes strong Secondary sludge, as above 4.36 35. no no none Mixture of primary and secondary sludges, as above (2nd batch) 8.5 45. no no weak Mixture 1:15 by vol. of domestic primary sludge and pharm. prim. 4 sec. 7.91 45. no no none sludges Primary sludge from domestic treatment (diluted, as control) 7.02 55. no no none Source of inocula: bench or full scale anaerobic reactors fed with sewage sludge, 30–35°C.

TAB.II-MAIN CHARACTERISTICS AND RESULTS OF THE WASTES TESTED WITH LABORATORY COMPLETELY MIXED, SEMICONTINUOSLY FED, MESOPHILIC ANAEROBIC DIGESTERS. waste origin Slaughterhouse conc. wastewater (dilured in water) Mix 1:1 by vol. of dil. slaughterhouse ww and sec. sludge from domestic ww treatment Secondary sludge from chemical industry (I) ww treatment Secondary sludge, as above Secondary sludge from domestic ww Treatment (as control) Secondary sludge, as above Secondary sludge from chem.industryZ(II) ww treatment Secondary sludge, as above, with biogas recirculation and H2S removal Secondary sludge, as above, with Fe++ addition to the feed Secondary sludge, as above, with pre-washing of the feed Secondary sludge from complex chem.ind.(III) ww treatment Primary sludge from municipal ww treatment (as control) Primary sludge from municipal ww treatment (as control)

HRT,SRT1 d

CODa, total Kg×m−3

CODe,total Kg×m−3

22.9

21.9

9.5

0.92

0.20

22.9

50.2

22.0

2.24

0.18

16.1

26.9

22.0

1.67

0.06

35.9 16.1

34.8 20.6

24.7 15.0

0.97 1.28

0.10 0.07

35.9 23.7

19.1 12.5

13.3 12.5

0.53 0.53

0.10 0.00

23.7

12.5

11.0

0.53

0.04

23.7

12.5

10–8

0.53

0.04

23.7

10.8

8.6

0.45

0.07

18.7

13.9

13.4

0.73

0.00

18.7

35.0

20.0

2.19

0.14

23.4

30.0

15.1

1.28

0.15

Energy from biomass

548

Primary sludge from municipal ww 23.4 30.0 treatment, flocculated with Al salts Primary sludge from municipal ww 23.2 26.7 treatment (as control) Primary sludge from municipal ww 23.2 26.7 treatment; flocculated with Fe salts Cephalosporin micelia waste from 31.0 30.0 pharmaceutical industry (dil. in water) Mix. 1:1 by vol of micelia, as 31.0 50.0 above, and prim.+second. sludges from domestic ww treat. Primary sludge from municipal ww 22.0 30.0 treatment (as control) Mix. 2.3:1 by vol. of sludge as 22.0 27.2 above and prim.+sec.slud. from pharm.ind. ww treat Primary sludge from municipal ww 23.3 32.6 treatment (as control) Mix. 1:1 by vol of sludge as above 23.3 31.1 and prim.+sec. sludges from pharm ind ww treat. 1: HRT=Hydraulic Retention Time; SRT=Sludge Retention Time

14.8

1.28

0.15

15.0

1.15

0.16

14.9

1.15

0.15

7.5

0.96

0.25

21.5

1.61

0.19

18.4

1.36

0.13

15.1

1.23

0.14

15.1

1.40

0.16

15.8

1.33

0.15

2:

FIG. 1—ANAEROBIC DIGESTERS FOR BATCH TESTING

Methane from biological anaerobic treatment of industrial organic wastes

FIG. 2—LABORATORY COMPLETELY MIXED ANAEROBIC DIGESTERS

549

EXPERIENCES WITH ANAEROBIC DIGESTION OF VARIOUS CASSAVA RESIDUES IN INDONESIA R.Wurster EAT-Systemtechnik GmbH, D-8012 Ottobrunn SUMMARY Geographical, environmental and climatic factors proved to be very much in favor of the application of anaerobic digestion processes in Indonesia. From a large number of digestible substrates originating from agroindustries (4), cassava derived residues were selected for digestion experiments. The digestibility of solid tapioca residue could be demonstrated in different types of digesters. An alternative of improved recovery of energy from this residue is sketched, and first Indonesian digestion results with cassava derived ethanol slop are reported.

1. INTRODUCTION On the basis of the cooperation agreement for scientific research and technological development between the F.R. of Germany and the Republic of Indonesia, a joint project called “Solar Village Indonesia”, was established in 1979. In the scope of this project EAT was asked in 1983 to promote the experience in the use of biomass for anaerobic digestion in Indonesia. The original goal of the project was to assist the Indonesian partner (B.P.P.Teknologi) in the final design, construction and operation of a large-scale experimental biogas plant, as well as to carry out a study on the biomass potential for anaerobic digestion in Indonesia in general. As first step, laboratory digestion tests with various substrates should be performed and an investigation on the general feasibility of anaerobic digestion processes should be carried out, leading to recommendations how to proceed. The experiments were scheduled to be carried out by BPPT-staff. Assistance from the German side should take place on site during the stays of the visiting experts as well as by monitoring the test results continuously from abroad. The BPPT-staff involved in the activities should have been sent to Germany for a six weeks training program on biochemical analysis and on anaerobic digestion. 2. MATERIALS AND METHODOLOGY The digestion tests in Indonesia were carried out with an experimental set-up consisting of 8 batch digesters of 60l each and of 4 semi-continuously fed 40l digesters. Four of the

Experiences with anaerobic digestion of various cassava residues in indonesia

551

batch digesters were equipped with a simple device for up- and downward stirring. Two of the 40l digesters were of the so-called two phase type, where the feed intake also serves as a hydrolysis and acidification section. The volumetric ratio of acetogenic to methanogenic section was of about 1 to 8. In contrary to this, the both socalled one phase digesters have a volumetric ratio of about 1 to 30. Main efforts were laid upon experiments with the semi-continuously fed digester type, because it is better suitable for practice oriented operation. Simple measuring equipment was provided only for the determination of the total organic solids (TOS) content, the pH-value of the substrate and for the CO2-content in the biogas. More detailed analyses should be regularly performed by specialized institutions. The following operational parameters were measured and recorded daily: substrate feed, gas production, gas quality; furthermore the pH-value of substrate, digester contents and digester effluent. The digester temperature was controlled thermostatically and kept at 35°C. For the start-up of the digestion process with solid tapioca production residue (STR), cattle manure was used, since no sewage sludge as inoculum could be obtained, because in Indonesia waste water treatment plants are lacking almost completely. The digestion tests performed during the training program at the University of Regensburg, Germany, were carried out in 1l continuously stirred, semi-continuously fed cylindrical laboratory digesters at 35°C. As starter substrate cattle manure as well as sewage sludge were applied. The digestion tests were supported by all necessary analysis activities, like gaschromatography, COD-, NH3-, NK- and SO4-determinations. 3. EXPERIMENTAL EXPERIENCES -FIRST TEST AND ANALYTICAL RESULTS During initial digestion tests in Indonesia using cattle manure it was decided to focus future efforts on substrates which are locally concentrated (e.g. from industrial plants) and cause harm to the environment. Among others, cassava residues were identified to meet these requirements. From this group of materials, solid tapioca production residue (STR) was chosen. The TOS-content of the diluted STR fed to the digester was increased step by step from 0.68kg-TOS/m3d to 2.0kg-TOS/m3d in order to increase the gas production rate. As a result the daily gas production rate was raised from poor 9l/d to moderate 25l/d, and the fluctuating specific gas yields consequently varied between 236l/kg-TOS and 377l/kgTOS. The initial pH-value of the STR measured some hours after the termination of the production process, normally dropped to around pH4. Thus the substrate was very acidic. Due to this low pH-value, due to the organic overload which sometimes occured, and due to repeated and excessive curtailing of the digestion starting phase to less than two weeks, overabundant acidification of the digester contents was caused very easily (for the minimum time requirement of the start-up, cf. 8). This retardation or obstruction of the anaerobic process mainly was attributed to the insufficient growth of the methanogenic bacteria and thus to an accummulation of acids and of hydrogen. Most of these operational disturbances have been avoided during a thoroughly monitored training program on anaerobic digestion of STR which was performed in

Energy from biomass

552

Germany. Gas yields of 0.8m3-biogas per kg-TOS (added) proved to be realistic. The mean methane content reached 65% and the COD-reduction of the originally highly polluted substrate (120–140g-COD/l) reached 65%. Also during these tests, which were continued after the end of the training program for another two months, a severe deficiency of nitrogen in the STR was observed. Therefore the addition of nitrogen sources is suggested to avoid obstruction of bacterial build-up. The most essential analysis and performance data, acquired during the above mentioned training program, are summarized in the following tables I and II: Raw Tapioca Residue: TOS

:

42%

Diluted Tapioca Residue (ready for feed to digester) TOS Ash COD Ntot Starch Fibre Sugar pH

7,2–7,7% 0,1–0,2% 120–140g/l 0,15% 88–98% 5–10% no uncombined sugars 3,5–4,0

Table I: Chemical Analysis of Solid Tapioca Production Residue pH 7,0–7,5 Gas Yield 0,8m3-biogas/kg-TOS 68m3/m3-tapioca residue Gas Quality 65% methane Degradation 65% of COD Acids 1200mg/l Additives addition of nitrogen is mandatory for maintaining a stable digestion process

Table II: Mean Values of Experimental Digester Performance 4. DISCUSSION OF EXPERIMENTAL AND STUDY RESULTS 4.1 Experimental Results: During the one year’s experimental digestion phase in Indonesia it turned out that reliable chemical analyses neither could be carried out on-site, nor could be obtained at short notice and completely enough from specialized private or university institutes due to organizational difficulties. Many of the problems which occured were related to this fact. On the other hand the digestion tests were performed with a still rarely known substrate: solid tapioca residue (STR). As a result of the training program for Indonesian staff in Germany, it was decided to provide additionally the necessary analytical equipment for the determination of TOS,

Experiences with anaerobic digestion of various cassava residues in indonesia

553

COD, NH3, NK, SO4 and volatile acids to ensure an improved continuation of the tests with this extraordinarily well suited substrate in Indonesia. Regarding the requirements of the biogas process on one hand, and the conditions of a tapioca factory on the other, for practical application, it is recommended to dilute the STR with the liquid effluent of the tapioca factory due to its very high TOS-content. Notwithstanding, STR obviously has a very high starch content of more than 85%, and therefore it would be even more advisable to carry out alcoholic fermentation. By doing so, prior to an anaerobic digestion step performed on the liquid effluents from both, alcoholic fermentation and tapioca production, a more versatile applicable energy can be recovered. 4.2 Study Results: In parallel to the digestion experiments the biomass potential suitable for anaerobic degradation was investigated. Further the impacts caused by the application of this technology were studied (4). The study concludes that conversion of agricultural residues, forest residues, weeds, and municipal wastes to biogas roughly can substitute as much as 3.5Mtce/a or 5% of the present Indonesian primary energy consumption. Furthermore the very favorable effects of biogas technology concerning its net-potential for job creation and its possible benefits to an increasingly polluted environment are presented. All these effects count even higher in a basically still agrarian society with an actual growth rate of 2.5% and 160mio. inhabitants, of which more than 60% live in an average density of more than 750inhab./km2 on the island of Java, whereas the rest of the population lives scattered over approx. 2,000 inhabited islands with an average density of 34 inhab./km2. 5. PROSPECTS OF ANAEROBIC DIGESTION OF CASSAVA DERIVED SUBSTRATES Since 1984 new environmental laws are enacted in Indonesia, forcing major polluters to purify their production effluents to a maximum organic load of 2,500mg-COD/l before discharge to public waters. The existing large tapioca factories as well as the numerous ethanol distillation plants conceived by the government, produce large quantities of concentrated organic effluents or residues. Aerobic treatment for the purification of these effluents would require a large amount of energy, mainly electricity. Since the ethanol plants will be located in remote transmigration areas, energy supply will be both, difficult and expensive. Therefore anaerobic treatment of the ethanol stillage is suggested, to provide purification capacity and to substitute process energy. Digestion experiments with cassava distillation slop (TOS: 3%) were carried out by BPPT. The diluted slop (BOD: 20g/l) was fed to the digester at a load ratio of 5kgTOS/m3d. The yield at a HRT of 4 days was 0,7m3biogas per kg-TOS. As known from experiments with distillation stillage in upflow anaerobic filter reactors (cf. 6,7), CODdegradation of up to 90% can be regarded as feasible, if the percentage of SS is low.

Energy from biomass

554

Considering these benefits, aerobic posttreatment seems to be unnecessary for many applications in Indonesia in the short run. To realize this idea, a biogas pilot plant is under planning as an integral part of the almost finished ethanol complex at Tulang Bawang Transmigration Area in Sumatra. For the design of the plant the following input/output ratio is taken as a basis: daily Output daily Input 90.0t of cassava or sweet potato – 15m3 of ethanol (95%) 10.0t of cassava or sweet potato – 2t of high fructose syrup 7.5t of cassava or sweet potato – 1t of dry yeast solids approx. 200m3 of ethanol slop

6. CONCLUSION The recent difficulties encountered in the digestion of cassava processing residues in Indonesia were more related to infrastructural and organizational shortcomings, as well as to shortages in equipment, than to technological problems. These circumstances became obvious within the the training program. Cassava is arable under a wide range of climatic and soil conditions (from arid to tropical), furthermore it is rich in starch content, and it has a high latent potential for increased root yield. Therefore it will be a very important food a/o energy crop also for Indonesia (cf. 2). An envisaged wider utilization of cassava and other crops in industrialized production processes, like used in tapioca factories, ethanol plants, palm oil mills, sugar factories, canneries, paper mills, etc., will cause locally concentrated effluents of high organic pollution potential. This will result in a severe environmental impact, if effluents are discharged to public waters without any treatment. Modern anaerobic digestion technology can provide very reasonable means of waste water purification and will further make available a strongly needed auxiliary energy source and an energy-saving natural fertilizer. Both, the environmental and the energetic aspect will gain increased importance in Indonesia. On the overcrowded island of Java the pollution potential is very high due to almost complete lacking of industrial and municipal purification plants. On the scarcely populated and often poorly developed other islands, the supply of energy can be difficult, timeconsuming, and thus costly; all this is of even greater significance in transmigration areas. Additional advantage of the biogas technology is the limited level of technology which will be required with regard to fabrication and plant installation. Therefore a wider application of this technology will be feasible, when mainly using indigenous capacities. On the other hand, skilled personnel is required for plant operation. Considering rural applications, the acceptance of the biogas technology has to be investigated for each special case separately, to prevent probable failures. 7. REFERENCES 1. “US-ASEAN Seminar on Energy Technology, LIPI, Bandung, Indonesia, 7–18 June 1982

Experiences with anaerobic digestion of various cassava residues in indonesia

555

2. “Cassava as an Energy Crop for arid and semiarid Lands”, by Porto/Marcarian, 2nd ECConference, Berlin, 1982 3. Statistik Indonesia, Biro Pusat Statistik, Jakarta 1982 4. “On the Prospects of the Anaerobic Digestion Technology in Indonesia”, by O.Ullmann, EATSystemtechnik GmbH, Dec. 1984 5. “Results of Cassava Digestion Experiments”, Universität Regensburg, 1984—not yet published 6. “A Pilot Scale Anaerobic Upflow Reactor treating Distillery Waste Waters”, by Pipyn/Verstraete, Rijksuniversiteit Gent 7. “Anaerober Abbau von Weinschlempe”, by Dr.M.Morper, Linde AG, 1982 8. “The Prospects of Anaerobic Waste Water Treatment”, by G.Lettinga, Agric. Univ. Wageningen, CEC-Conference, Luxembourg, May 1984

BIOGAS TECHNOLOGY DEVELOPED AND EVALUATED BY ENADIMSA A.J.GARCIA, S.CUADROS and R.FERNANDEZ Unidad de Residuos Só1idos, ENADIMSA Empresa Nacional ADARO de Investigaciones Mineras, S.A. Madrid—SPAIN Summary A wide program of studies and project oriented towards the better use of the residual biomass as energy source, has been taking place since 1978. The first studies were oriented towards the estimation of the potencial residual biomass in Spain, using detailed inventories from various provinces. Subsequently, studies have been made regarding the technicaleconomical viability towards establishing practical applica tions and developing the technology for the employment of energy coming from the residual biomass. Among the studies which ENADIMSA has carried out in this field, the following are examples: – Use of gas from rubbish landfill as energy. – Use of the residue from an alcohol factory as energy. – Development of technology for the anaerobic digestion of farm wastes and self-supply of energy. – Use of crop residues as energy. – Use of forest residue as energy source through charcoal. – Program and practices in the f ield of biomass in different countries. – Economical aspects of the use of biomass residue. These studies have led to the installation of demostration units for the different technologies used in the conversion of biomass into energy.

1. BIOGAS TECHNOLOGIES EVALUATED Within different PEN (National Energy Plan) projects (References 1, 2, 3, 4) various installations for the production of biogas have been constructed and are currently in a follow-up phase, in collaboration with the INIA (Instituto Nacional de Investigación Agraria) and the “Instituto de la Grasa y sus Derivados, CSIC”, with the objective of evaluating different technologies for the treatment of organic residues and wastes. Within the framework of these projects, ENADIMSA has achieved a technology of its own, developing three systems: rural, DAC and DAL. The systems and installations evaluated are described as under.

Biogas technology developed and evaluated by enadimsa

557

– Discontinuous system For the treatment of cattle-manure (30% at solids), ENADIMSA has perfected a rural technology dry route discontinucus system, in two modu les of 50m3 constructed in Gerona. The biogas is exploited in a Totem Co-generator. The results achieved are of a 48 hour cycle for the aerobic phase and 15 days for the anaerobic phase, with biogas yields of 0,6m3/m3 digester/day. – Mixed System This low technology system has been evaluated in a partial mix digester of 100m3 contructed by De Gaspari, S.A., in Zaragoza, for the experi mental treatment of farm residues. The mean results achieved were: • Loading rate: 1,75–2,25kg VS/m3 digester/day • Biogas yields: 0,75–1,00m3/m3 digester/day • Process efficiency: 50–60% • Hydraulic retention time (HRT): 15 days – Plug-flow System The Plug-flow system has been evaluated in a digester of 1.150m3 constructed in Zaragoza by CASIS, S.A., with the technology of Sheaffer & Roland (USA). The biogas produced is used for the generation of electxical energy in a Caterpilar motor generator group (285kW). The results achieved in the treatment of liquid cattle manure at 7% solids are: • Loading rate: 3–4kg VS/m digester/day • Biogas yields: 1,0–1,3m3/m3 digester/day • Process efficiency: 65% • Hydraulic retention time (HRT): 15 days – D.A.L. System ENADIMSA has developed a plug-flov technology named D.A.L. (Longitudinal Activity Digester) and constructed a digester of 500m3 for the treat—ment of cattle farming residues in Mérida, with the following results: RESIDUE Pig Cow • Loading rate 4–6 • Biogas yields 1,3 • Process efficiency 70 • Hydraulic retention time (HRT). 10

6 kg VS/m3 digest./day 1,6 m3/m3 digester/day 60 % 10 days

Energy from biomass

558

– Contact System The contact system with recycling of biomass has been evaluated in a digester of 250m3 constructed by ATEINSA in Sevilla for the treatment of mollase distillery slops, obtaining the following results: • Loading rate: 4kg VS/m3 digester/day • Biogas yields: 20–24m3/m3 distillery slops • Process efficiency: 65–70% • Hydraulic retention time (HRT): 17–20 days – D.A.C. System ENADIMSA has developed an internal contact system named D.A.C. (Central Activity Digester) which eliminates the problems and surpasses the yields of the recycle contact systems. The positive results evaluated in a pilot plant of 15m3 constructed in Sevilla, has led to the cons truction of a industrial installation of 500m3 in Badajoz, for the treatment of slurry of 5.000 pigs, with the use of the biogas for heating. The yields of this system are summarised as under: RESIDUE Pig Cow Distillery Slops • Loading rate: 2,3–6,6 8,2 • Biogas yields: 1,2–2,2 3,3 • Process efficiency: 85–70 70 • Hydraulic rerention time: 12–6 8

6–8 kg VS/m3 digest/day 2,5 m3/m3 digester/day 65–75 % 10 days

– Filter System This system has been evaluated in a pilot plant of 20m3 in Soria and in an industrial instalation of 120m3 in Toledo, constructed by SUFISA with the technology of S.G.N. (France). The results achieved in the digester operating with slurry from 4.000 pigs are: • Loading rate: 3,75–6,00kg VS/m3 digester/day • Biogas yields: 3–4m3/m3 digester/day • Process efficiency: 60% • Hydraulic retention time (HRT): 3–5 days

2. CURRENT PROGRAM The objectives of ENADIMSA are to continue the follow-up of the different technologies tested for the treatment the residues of farming, and to iniciate a program of evaluation of new systems, developing downflow stationary fixed f ilm technology and to extend the range of the organic effluents tested.

Biogas technology developed and evaluated by enadimsa

559

REFERENCES (1) Aprovechamiento energético de residuos de alccholeras (Project PEN, 1980). (2) Desarrollo de Tecnología para la digestion anaerobia de residuos ga naderos (Project PENMAPA, 1981). (3) Autoabastecimiento energético en explotaciones agropecuarias (Project PEN-MAPA, 1982). (4) Digestión anaerobia natural de residuos ganaderos en digestores rurales (Project PEN, 1983).

DIGESTER 2×50m3, RURAL SYSTEM (Gerona)

DIGESTER OF 500m3, D.A.L. SYSTEM (Merida)

Energy from biomass

560

DIGESTER OF 500m3, D.A.C. SYSTEM (Badajoz)

INFLUENCE OF HYDROGEN ADDITION ON THE POTENTIAL OF METHANOGENIC ECOSYSTEMS R.MOLETTA(1), J.D.FINCK(2), G.GOMA(3) and G.ALBAGNAC(4) (1) and (4) STATION DE TECHNOLOGIE ALIMENTAIRE—I.N.R.A. 369, Rue Jules-Guesde F—59650 VILLENEUVE D’ASCQ (1) present address: STATION D’OENOLOGIE ET DE TECHNOLOGIE VEGETALE—I.N.R.A.—Bd du Général de Gaulle F 11100 NARBONNE (2) and (3) Département de GENIE BIOCHIMIQUE ET ALIMENTAIRE ERA—CNRS 879—Avenue de Rangueil F—31077 TOULOUSE (2) present address: ELF BIO RECHERCHES La Grande Borde, BP 62, Labège F—31320 CASTANET-TOLOSAN Summary In microbial ecosystems of anaerobic digesters, reduction of carbon dioxide into methane by exogenous hydrogen may be of economic interest. According to thermodynamical considerations, a partial hydrogen pressure of 10−4 atm may lead to a total arrest of propionate degradation and thus reduce the admission of that gas into the digester. Supply of hydrogen to the gas phase at a very high partial pressure (0.24atm) inhibited the degradation of propionate by anaerobic sludge without fully stopping it. This event may be explained by a limitation of hydrogen transfer from the gas phase to the liquid phase. The propionate degradation rate varied linearly with the logarithm of hydrogen partial pressure. Admission of hydrogen into an anaerobic digestor ensuring a discontinuous methanisation of dung led to a slighty lower biogas (CO2+CH4) production, but the final yield was the same. When the hydrogen supply was adjusted to the consumption capacity of the system, the produced biogas contained 98–6 p.100 methane, 0.4 p.100 CO2 and 1 p.100 residual hydrogen. Combined with hydrogen producing reactions, either by fermentation or via chemical pathways, this procedure allows to recover energy and to store it as methane.

I. INTRODUCTION During anaerobic digestion of organic matters, volatile fatty acids (especially acetate) are the main intermediates of the energy flow.

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Among these acids, propionate exerts the largest inhibition of the biological reaction (1) and plays a fundamental role in methane fermentation (2). During anaerobic digestion of cow dung, acetate, propionate and butyrate, are respectively the intermediates for 72– 75, 13, and 8 p.100 of the methane (3). Propionate and butyrate degradation leads to production of hydrogen (Table 1), which concentration plays an important role in the reaction energetics (Fig. 1). Partial pressure lower than 10−4 atm are generally required for the degradation of propionate. This low pressure is mainly due to hydrogenophilic methanogenic bacteria which produced methane and water from H2 and CO2. The addition of hydrogen to the fermentation medium should lead to production of biogas almost exclusively composed of methane, but should also inhibit the degradation of volatile fatty acids, especially propionate (5), (6). The purpose of the present work was to study the influence of hydrogen on the kinetics of propionate degradation and methane fermentation of cow dting and to use the kinetic abilities of methanogenic hydrogenophilic bacteria of producing a gas including almost only methane. II. MATERIAL AND METHODS a) Propionate degradation in the presence of hydrogen The sludge came from an industrial digester of vegetable cannery waste waters. The reactors used were 1 200ml glass flasks containing 250ml sludge and 6 ml sodium propionate was added (pH 7, 1M). Using a syringe, hydrogen was introduced into one of the flasks. The flasks were thereafter placed on a BRAUN TV 1 stirrer and subjected to a linear stirring of 120 cycles/min. and an amplitude of 25mm. b) Continuous addition of hydrogen to a cow dung digester Hydrogen was introduced from the bottom into a 100 1 PVC reactor in which the liquid phase was recycled from the top using a centrifugal pump (40l/min.) (Fig. 2). Another identical reactor was used as a control. These reactors were filled up with cow dung containing 10 p.100 dry matter after dilution. III. RESULTS AND DISCUSSION a) Influence of pH2 in the gas phase on propionate degradation Propionate degradations in the presence or absence of hydrogen are shown in figure 3. Although, pH2 largely exceeded the theoretical values leading to a positive G’ value, propionate degradation was not fully inhibited. This is because hydrogenophilic methanogenic bacteria have a great hydrogen consumption capacity (8) and because the transfer from the gas phase to the liquid phase is the limiting step. Under the present experimental conditions it may be assumed that with a pH2 of 0.42atm, the complete inhibition of propionate degradation would be accomplished (Fig. 4).

Influence of hydrogen addition on the potential of methanogenic ecosystems

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b) Continuous addition of hydrogen to a cow dung digester The amounts of biogas (CO2+CH4) produced with and without addition of hydrogen are reported in figure 5. Although, the H2 partial pressure ranged from 0.16 to 0.55atm, the methane fermentation was not fully inhibited and the biogas production rate decreased by 25 p.100. Several hydrogen addition rates were used during these experiments (Fig. 6). At constant flow rates, the hydrogen consumption rate increased with time accounting for an adaptation of the number of hydrogenophilic methanogenic bacteria. The introduction of hydrogen modified the composition of the biogas produced. When the amount of H2 introduced was adjusted to its degradation capacity, the biogas included almost only methane. (On day 35, 98.6 p.100 methane, 0.4 p.100 CO2 and 1 p.100 hydrogen;. The procedure involving introduction of exogenous hydrogen into an anaerobic digester offers several advantages: – the energy of the added hydrogen is stored in a form of reduced volume; – it enables the recovery of the different forms of CO2 and of a gas containing almost only methane; – this CO2 consumption may cancel the inhibition related to that molecule in connection with VFA degradation.

Fig. 1. Influence of pH2 on the ∆G’ (Kj) on hydrogen production and consumption. The gas phase is in equilibrium with the liquid phase. The concentrations selected were for the acids 10−3M, and for 50×10−3M. pCH4=0.5atm. (1) Degradation of

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propionate. (2) Degradation of butyrate. (3) Reduction of CO2 to CH4. (4) Homoacetogenesis. Stoichiometry of the reactions are described in Table 1.

Fig. 2. 100 litres reactor used for the digestion of cow dung in the presence of hydrogen. (1) Transparent PVC tank. (2) Heating pipe. (3) Recycling circuit. (4) Temperature sensor. (5) temperature controller. (6) Heating tank. (7) Discharge. (8) Hydrogen inlet. (9) Gas meter.

Influence of hydrogen addition on the potential of methanogenic ecosystems

Fig. 3. Influence of addition of hydrogen on propionate consumption. Temperature: 35°C. (1) Degradation of propionate in the presence of hydrogen. Initial concentration So=0.474g/l. (2) Degradation of propionate in the absence of hydrogen So=0.406g/l.

565

Energy from biomass

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Fig. 4. Propionate degradation rate rpr (mmoles.l−1.h−1) against log pH2 (atm.).

Fig. 5. Cumulated production of biogas (CH4, CO2) in the presence (H2) or absence (T) of hydrogen. Substrate

Influence of hydrogen addition on the potential of methanogenic ecosystems

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cow dung containing 10 p.100 dry matter. Temperature: 35°C.

Fig. 6. Anaerobic digestion of cow dung in the presence of hydrogen. Evolution of the hydrogen input flow rate (●), partial pressure in the effluent gas (▲) and consumption rate (O). TABLE 1 Stoichiometry of propionate (1) and butyrate (2) degradation, methane production (3) and homoacetogenesis (4) reactions according to THAUER and al. (4). HYDROGEN PRODUCTION REACTIONS (1). CH3−CH2−COO−+3H2O (2). CH3−CH2−CH2−COO−+2H2O 2 CH3− COO−+H++2 H2 ∆G’0=+48.0kJ/reaction

HYDROGEN CONSUMPTION REACTIONS ∆G’0=−30.9kJ/reaction ∆G’0=−104.5kJ/reaction

Energy from biomass

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REFERENCES (1) MOLETTA R., ZIGMUNT M., MORFAUX J.-N. (1981). Effect of organic acids on growth of acidogenic bacteria from anaerobic digesters. IInd International Symposium on Anaerobic digestion, 06–12 September 1981, TRAVEMUNDE. R.F.A. (2) STAFFORD D.A. (1982). The effect of mixing and volatile fatty acid concentrations on anaerobic digester performance, BIOMASS, 2, 43–55. (3) MACKIE, R.I. and M.P. BRYANT. (1981). Metabolic activity of fatty acid oxidizing bacteria and the contribution of acetate to propionate, butyrate and CO2 to methanogenesis in Cattle waste at 40 to 60°C. Appl. Environ. Microbiol., 41: 1363–1373. (4) THAUER R.K., JUNGERMANN K., DECKER K., (1977), Energy conservation in chemotrophic anaerobic bacteria, Bact. Rev., 41, 100–180. (5) KASPAR H.F., and K.WUHRMANN. 1978. Product inhibition in sludge digestion. Microbiol. Ecology. 4: 241–248. (6) BOONE, D.R., (1977). Mechanism of the assimilation of volatile organic acids by methanogenic enrichments. Dissertation presented to the graduate Council of the University of Florida for the degree of Doctor of Philosophy N°=78, 10, 924. (7) KASPAR H.F., and. K.WUHRMANN. (1978). Kinetic parameters and relative turnovers of some important catabolic reactions in digestive sludge. Appl. Environ. Microbiol. 36: 1–7. (8) HANSSON G., MOLIN N., (1981). End product inhibition in methane fermentation: Effects of carbon dioxide and methane on Methanogenic bacteria utilizing acetate, European J. Appl. Microbiol. Biotechnol., 13, 236–241. (9) HANSSON G. and N.MOLIN. (1981) End product inhibition in methane fermentations: effects of carbon dioxide on fermentative and acetogenic bacteria. Eur. J. Appl. Microbiol. Biotechnol., 13: 242–247.

BUTYRATE PRODUCTION AND VOLATILE FATTY ACIDS INTERCONVERSION DURING PROPIONATE DEGRADATION BY ANAEROBIC SLUDGES R.MOLETTA*, H.C.DUBOURGUIER. G.ALBAGNAC STATION DE TECHNOLOGIE ALIMENTAIRE—I.N.R.A. 369, Rue Jules Guesde F—59650 VILLENEUVE D’ASCQ * present address: STATION D’OENOLOGIE ET DE TECHNOLOGIE VEGETALE— I.N.R.A. Bd du Général de Gaulle F—11100 NARBONNE Summary Discontinuous degradation of propionate by anaerobic sludges of an industrial digester of vegetable cannery waste waters led to a transitory accumulation of butyrate and acetate. For an initial concen—tration of 32mM propionate, the maximum concentrations reached were 3.5mM butyrate and 0.8mM acetate. Introduction of carboxyl 14C labeled propionate showed that the specific radioactivity of acetate was half that of propionate. This seems to confirm that propionate is degraded through a randomizing pathway. The specific radioactivity of butyrate was almost similar to that of propionate, During propionate degradation, addition of 14 C labeled butyrate or acetate showed the existence of metabolic pathways of V.F.A. (acetate, propionate, butyrate) interconversion. The degradation of one molecule of propionate led to the production of 0.2 molecule of butyrate. This study made on a mixed population including O.H.P.A. bacteria analogous to Synthrophobacter or Synthrophomonas did not allow to determine whether butyrate proceeded from the condensation of two acetate molecules or it was directly derived from a symmetrical intermediate with four carbon atoms.

I. INTRODUCTION Propionic acid is an important intermediate in the microbial ecosystems of anaerobic fermentation (1), (2), (3) and its inhibitory effect is larger than that of the other V.F.A. (4). In the conventional metabolic pattern this acid is converted into acetic acid,carbon dioxide and hydrogen by acetogenic bacteria (O.H.P.A.). Synthrophobacter wolinii was

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identified as responsible for this conversion in the presence of a H2 using bac-terium (5). In methanogenic ecosystems the energy flows producing methane from propionate are sometimes more complex. In fact, propionate degradation in municipal waste water treatment may lead to a transitory butyrate accumulation (6). In the present study, we showed that this also occurred with another kind of sludge and that propionate degradation could be accompanied by a V.F.A. (acetate, propionate and butyrate) interconversion. II. MATERIALS AND METHODS Sludges studied came from an industrial digester producing methane from waste waters of a vegetable cannery. Reactors used were 100ml penicillin flasks (drained by an oxygen free gas, N2 and CO2 at 80 and 20 p.100. respectively) into which 10ml of sludge were added. Eight flasks were prepared to duplicate each experiment. In all the flasks 0.4ml of sodium propionate (pH 7 et 1 mole/ l) was added. This corresponding to time zero. Two flasks were used as controls. In two other flasks (PA and PB) carboxyl 14C labeled sodium propionate was added immediately after unlabeled propionate. Addition of carboxyl 14C labeled butyrate was done 9.30h after addition of un-labeled propionate to flasks BA and BB as well as that of 14C1 labeled acetate to flasks AA and AB. The quantity of radioactive VFA supplied at each time represented an increase in the medium concentration of 25mole/l. III. RESULTS AND DISCUSSION Addition of propionate to the sludge led to a transitory accumulation of butyrate (Fig. 1). Radioactivity present in the propionate carboxyl was partly recovered in the butyrate and acetate of the medium (Fig. 2). The specific radioactivity of acetate was stabilized about 2fold earlier than that of propionate, while that of butyrate was almost similar to that of propionate (Fig. 3). When assuming a single degradation pathway of propionate to acetate, these results document those indicating that propionate is degraded through a randomizing pathway, i.e. one molecule in the pathway is symmetrical (7) and that butyrate production may be due to the condensation of two acetate molecules. The supply of 14C l labeled butyrate led to the occurrence of labeled propionate and acetate (Fig. 4). Addition of labeled acetate led to the same phenomenon, i.e. production of labeled propionate, then of labeled butyrate (Fig. 5). This radioactivity transfer was due to a true carbon flux from one acid to another and not only to a transcarboxylation phenomenon from CO2 present in the sludges. In fact, total concentration of all forms of CO2 was about 11mM, and its maximum specific radioactivity (S.R.A.) was about 2 000DPM/mole. Therefore, this molecule cannot generate S.R.A. of 30 000 DPM/mole, for example, for acetate (Fig. 3) or of 10 000DPM/mole for propionate, 12.30h after addition of butyrate (Fig. 4). There is therefore a true interconversion of V.F.A. in methanogenic sludges (3).

Butyrate production and volatile fatty acids interconversion during propionate degradation

571

During experiments BA and BB (propionate degradation with supply of labeled butyric acid), if considering that the amounts of radioactive butyrate produced are negligible relative to that which may be consumed (true for a large part of the experiment) it is possible from the butyrate pool and its turnover to calculate its true degradation rate and thus its true production rate (on account of its accumulation rate). These values are reported in figure 6 with the propionate degradation rate. The amounts of butyrate produced (between 10h and the end of the experiment) obtained by integration in figure 6 as well as the propionate concentrations at 10h are reported in table 1. According to the ratio of these values the degradation of l mole of propionate produces about 0.2 mole of butyrate. IV. CONCLUSION In the sludge studied, propionate degradation led to butyrate formation. About 0.2 mole of butyrate was produced per molecule of degraded propionate. This study did not allow to determine whether butyrate proceeded from the condensation of two acetate molecules or it was directly derived from a symmetrical intermediate with four carbon atoms. Under these experimental conditions there was V.F.A. interconversion in which acetate could be the main axis (8).

Fig. 1. Variation in the VFA concentrations during discontinuous degradation of 33 mmoles of propionic acid.

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Fig. 2. Discontinuous degradation of propionic acid: variation in the VFA radioactivity with time during addition of 25µmole/l of carboxyl 14C labeled propionic acid at time zero.

Fig. 3. Discontinuous degradation of propionic acid. Variation in the

Butyrate production and volatile fatty acids interconversion during propionate degradation

specific VFA radioactivity (25µmole/l carboxyl 14C labeled propionic acid at time zero).

Fig. 4. Discontinuous degradation of propionic acid: variation in the VFA radioactivity during addition of 25µmole/l of carboxyl 14C labeled butyric acid after 9.30h of culture.

573

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Fig. 5. Discontinuous degradation of propionic acid: variation in the VFA radioactivity during addition of 25µtmole/l of carboxyl 14C labeled acetic acid after 9.30h of culture.

Fig. 6. Discontinuous degradation of propionic acid. Variation in the

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propionic and butyric acid consumption rates and butyric acid production with time during addition of 25µmole/l of carboxyl 14C labeled butyric acid after 9.30h of culture. TABLE 1 Butyrate produced by mole of propionate consumed during degradation of propionate by anaerobic sludge (calculated from duplicate experiment -BA and BB- with carboxyl 14C labeled butyrate addition) Propionate conc. after Amount of butyrate produced from Butyrate produced 10h run (m.mole) 10h run to the end (m.mole) propionate consumed BA BB

26.6 28.9

5.1 6.39

.19 .22

REFERENCES (1) JERIS J.S., Mc. CARTY P.L., (1965). The Biochemistry of methane fermentation using C14 Tracers, J.W. P.C.F., 37, pp 178–192. (2) KASPAR H.F. WUHRMANN K., (1978). Product Inhibition in Sludge Digestion, Microbial Ecology, 4, pp 241–248. (3) COHEN A., VAN DEURSEN A., VAN ANDEL J.G., BREURE A.M., (1982). Degradation patterns and intermediates in the anaerobic digestion of glucose: Experiments with C14-labeled substrates. Antonie van Leeuwenhoeh, 48. pp 337–352. (4) MOLETTA R., ZYGMUNT M., MORFAUX J.-N. (1981). Effect of organic acids on growth of acidogenic bacteria from anaerobic digesters. IInd International Symposium on Anaerobic digestion. 06–12 September 1981. TRAVEMUDE. F.R.G. (5) BOONE D.R., BRYANT M.P., (1980). Propionate degrading bacterium, Syntrophobacter Wlinii sp. nov. gen. nov., from methanogenic ecosystems. Appl. and Env. Microbiol., 40. pp 626–632. (6) Mc CARTY P.L., BROSSEAU M.H., (1963): effect of high concentrations of individual volatile acids on anaerobic treatment. Purdue UNIV. ENG. BULL. EXT. SER. 115. pp 283– 296. (7) KOCH K., DOLFING J., WUHRMANN K., ZHENDER A.J.B., (1983). Pathways of propionate degradation by enriched methanogenic cultures. Appl. and Env. Microbiol., 45, pp 1411–1414. (8) STAFFORD D.A., (1982). The effects of mixing and volatile fatty acid concentrations on anaerobic digester performance. BIOMASS, 2, pp 43–55.

LARGE SCALE ANAEROBIC DIGESTION OF ANIMAL WASTES IN THE NETHERLANDS F.M.L.J.OORTHUYS—H.J.W.POSTMA Grontmij n.v. consulting engineers, the Netherlands presentation: H.Snoek—P.H.A.M.J de Bekker Summary About 25 Dutch biogas plants on individual farms digest various types of animal waste slurries. Considerable operational and technical problems turned the economic balance negative in most cases. In spite of the government’s financial support, the development and wide application of these small scale biogas plants is now impeded. Large scale biogas plants were recently studied by Grontmij based on national and foreign practical experience with anaerobic digestion of animal wastes. These plants are generally found to be economically and technically feasible. Several projects are prepared for central processing of manure which originates from large numbers of livestock units. It is foreseen that 35 to 45 large scale biogas plants may be impleroented in the next decade, to process about 10 million m3 of animal wastes annually. Nett generation of biogas may reach 100 to 200 million m3 annually, equivalent with 55 to 110Kt.o.e. The paper covers a case study of central anaerobic digestion of 100.000m3 of pig wastes and 50.000m3 of poultry wastes per year simultaneously. The nett biogas production is estimated to be 3.0 million m3 per annum (appr. 1,5Kt.o.e.)

1. INTRODUCTION In the Netherlands livestockfarming is concentrated in several regions causing detoriation of the environment by uncontrolled disposal of animal wastes and overfertilization. In an ever increasing number of occasions during the past decade acid precipitation, nuisance and nitrates present in groundwater, which is a source of drinking water, were related hereto. On the other hand areas used for arable farming require commercial and organic fertilizers. The long term purpose is to use the surplus of animal waste to balance the need for fertilizers. Large scale central anaerobic digestion of animal wastes may support the development of centrally managed recycling of manure surplusses as a first step in a série of unit operations, providing the energy that is required for further processing.

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2. PROBLEM Argicultural manure surplusses in the Netherlands. Manure surplus in million tons per yr total manure production in million tons per yr – cattle: – fattening calves: – pigs: – poultry:

7.5 1.0 7.5 2.0 18.0 106 T/a

67.0 1.7 14.6 2.7 86.0 106 T/a

3. ENERGY RECOVERY About 25 Dutch biogas plants on individual farms digest various types of animal waste slurries. Considerable operational and technical problems turned the economic balance negative in most cases. In spite of the government’s financial support, the development and wide application of these small scale biogas plants is now impeded. Large scale biogas plants were recently studied by Grontmij based on national and foreign practical experience with anaerobic digestion of animal wastes. These plants are generally found to be economically feasible (gas-utilisation through production of electricity and heat). Several projects are prepared for central processing of manure which originates from large numbers of livestock units. A number of large scale biogas plants may be implemented in the next decade to treat about 10 million m3 of animal wastes anually. Nett generation of biogas may reach 100 to 200 million m3 annually, equivalent with 55 to 110 Kt.o.e. (*). In this paper a case study on central digestion and further handling of yearly 150.000m3 of animal wastes is presented. In the Netherlands the present project is considered to be in the most advanced stage and can be implemented as a suitable energy demonstration project for large scale anaerobic digestion of animal wastes, including large scale manure processing. The plant is projected in the industrial zone near the harbour of Meerlo-Wanssum’s municipality (Province of Limburg, in the southern region of the Netherlands). 4. DEMONSTRATION PROJECT WANSSUM (NL) By order of “Stichting Mestbank Limburg”, Grontmij designed a large scale plant for transhipment and anaerobic digestion of animal wastes. The manure is supplied by tanker-lorries, while the residue is conveyed by tanker-vessels or tanker-lorries. Storage tanks are applied to tune both flows. The anaerobic digestion plant is fed with fresh manure taken from the storage tanks. Biogas generated is utilized in several ways: – for energy consumption of the digestion plant (electricity and heat);

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– for energy consumption of the transhiprment plant (electricity). * Note: one t.o.e.=4.19×1010 Joule.

The surplus of biogas is supplied to a local cattle feed factory or the regional gasdistribution company. Agreement on supply of biogas has been reached. 5. EVALUATION OF ALTERNATIVE DESIGNS Three variants which appeared to be most attractive are evaluated: Variant a 3

Anaerobic digestion of 75,000m of piggery waste and 35,000m3 of poultry waste annually, while 40,000m3 of poultry waste are shipped directly. Nett biogas production of 1.9×106m3 per annum is used to cover the forage factory’s need for gas. Biogas will be flared during the weekend as the factory closes. In this case storage of the entire gasproduction during the weekend turns out to be not economically feasible. Variant b This variant is technically equal to variant a, however in this case biogas is entirely supplied to the gasdistribution company. Therefore flaring of biogas will not take place in normal operation. Variant c 3

Anaerobic digestion of 100,000m of piggery waste and 50,000m3 of poultry waste annually. The nett biogas production of 3×106m3 per annum is entirely supplied to the gasdistribution company. The production costs of biogas depend on the technical solution adopted and the financial support granted to the project. The following tabel shows the production costs excluding tax, expressed in Dfl/m3 of natural gas equivalent. In the Netherlands the current price of natural gas for annual supply between 1×106m3 and 10×106m3 is nowadays Dfl 0.475/m3, excluding tax.* Production costs of biogas in Dfl/m3 vs degree of subvention on investment. Subvention on investment Variant 0% 25% 50% a. b. c.

0.67 0.56 0.44 0.49 0.41 0.33 0.35 0.30 0.25

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Conclusions 1. Gas supply to the gasdistribution company at an annual b: 1.9×106m3 is favoured in case the additional costs for upgrading and transport of biogas are less than Dfl 0.11– 0.18 per m3 of natural gas equivalent. (Comparison of variant a and variant b). 2. Production costs of biogas are at minimum by anaerobic digestion of 100,000m3 of piggery waste simultanously with 50,000m3 of poultry waste per annum. Net biogas production is 3.0×106m3 per annum (variant c). * Note: 1m3 natural gas=31MJ

6. DETAILED DESIGN OF MANURE DIGESTION PLANT WANSSUM (variant c) Feed; pig manure 100,000 m3/a (140,000 pigs) poultry manure 50,000 m3/a (600,0 00 chickens)

DESIGN DATA Feed: pig manure 6,000t TS/a (6% TS) poultry manure 8,000t TS/a (16% TS) 14,000t TS/a=40t TS/d=410m3/d Chemical dosage for H2S removal

: 800l FeCl3/d (41% w/w)

Digester volume

: 2×4,750m3

Mean hydraulic retention time

: 23d

Digester operating temperature

: 30°C

Solids load

: 4kg TS/(m3.d)

Biogas production

: 10,200m3/d

Energy content

: 235,000MJ/d

Used for heating (average)

: 35,000MJ/d

Nett biogas volume

: 3,000,000m3/d

Nett energy value

: 200,000MJ/d

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PROCES FLOW DIAGRAM

7. COSTS ASPECTS7. Investment for complete digestion plant excluding transhipment plant, including 30% subvention on investment: Yearly capital costs: (15 years, 9% interest): Yearly running costs (excluding external transports): Operation: Maintenance: Chemicals: Digestion costs per ton of raw manure Running benefit 3,000,000m3 biogas/a (750kWe, 1650t.o.e. per year)

Dfl. 3,800,000. Dfl. 470,000. Dfl. 60,000. Dfl. 80,000. Dfl. +130,000. Dfl. 270,000. Dfl. 5,00 Dfl. PM

REFERENCES Large scale transhipment and anaerobic digestion of manure at Wanssum (NL) Grontmij n.v. consulting engineers 1984 (in Dutch).

THE ANOXAL PROCESS ANAEROBIC TREATMENT OF LIQUID INDUSTRIAL EFFLUENTS J.M.CUTAYAR L’Air Liquide Centre de recherche CLAUDE DELORME BP 126. 78350 Les Loges en Josas FRANCE M.MOULINEY L’Air Liquide D.C.V.M, CP 26,57 avenue CARNOT 94503 Champigny sur Marne FRANCE Summary Biological treatments of industrial effluents usually consisted in aerobic fermentation or in unoptimized anaerobic fermentation techniques (CSTR process, Contact process…). The main limitations of these techniques are economic or technical ones. The aerobic treatments cause important investments and high operating costs; the first generation of methanization processes cannot accept high dilution rates because of the washing out of the microorganisms. The Anoxal process developped by l’AIR LIQUIDE is an upflow anaerobic filter; the reactor is loosely packed with an inert plastic media which induces microorganisms retention. Since high active biomass concentrations can be reached, the process allows the anaerobic treatment of any kind of industrial effluents with important COD loading rates and methane productions. Several studies carried out from laboratory to full scale plant have established the efficiency and the reliability of the Anoxal process.

1. Introduction The anaerobic treatment of liquid industrial effluents is developped by l’AIR LIQUIDE since 1981. A two years basic research in our research center completed by several pilot plant studies (from 3 to 10m3) led us to the definition of the Anoxal process. It consists in an upflow anaerobic filter, loosely packed with an inert material (polypropylene pall rings) which induces microorganisms retention. Most of the biomass is present in suspended form in the intersticial void spaces within the media matrix and only a small portion of the biomass is attached to the packing surfaces. Since the suspended growth tends to collect in the bottom of the reactor, most of the activity is in the bottom of the fermentor and the attached growth has a polishing action (see pictures 2 and 3).

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In most of anaerobic digestion processes transport of unattached biological solids occurs because of hydraulic lifting and flotation due to attached gas bubbles, the consequence is a physical biomass washing out. In the Anoxal process, the packing itself serves to separate the gas and to provide quiescent areas wich ensure the settlement of the suspended solids. The gas mixing and the liquid upward movement are some of the factors wich cause the biological solids floculation. These microbial flocs become heavy enough to settle downward. The combined effects of the packing on the one hand and the hydrodynamic regime on the other hand, ensure, in the Anoxal process, an effective biomass retention. An excess biological solids removal device is necessary to avoid an eventual development of “dead” zones and short-circuiting paths within the media. An adequat liquid distribution at the bottom of the reactor allows also to avoid these hydraulic problems. As it is shown in the following picture,the Anoxal process also includes: – a pretreatment stage wich assumes, according to the type of effluent: • the liquid flow regulation • the pH neutralization • the nutriment’s supply(minerals, vitamins…) • the temperature regulation – a biogas purification unit – a biogas storage unit

PICTURE 1: THE ANOXAL PROCESS PRINCIPLE The first full scale Anoxal plant was built in 1983–84 for FLODOR SA (potato industry) at Peronne in the north of France and was started in June 1984. This plant currently treats

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potatoes bleaching water, featuring a 13 tons of COD (chemical oxygen demand) daily load. A second full scale plant has been sold to “La Cellulose du Pin” at Tartas in the south west of France; this unit will be started on a sulfite evaporator condensate effluent. The previous load is 21 tons of COD per day. 2. Anoxal process references 2.1 Treatment of a potatoes bleaching water This waste water which mainly consists of starch, represents an organic load of 13 tons of COD per day. Its chemical and physical characteristics vary a lot; however, the mean ones are: – COD (chemical oxygen demand)=

2000 to 10 000mg/l

– BOD5 (biological oxygen demand)

1500 to 8500mg/l

– TSS (total suspended solids)=

500 to 4000mg/l

– Dry matter=

1500 to 6000mg/l

– Total nitrogen=

50 to 100mg/l

– pH=

4 to 7.5

– Temperature=

25 to 40°C

After a one year pilot plant study (on a 5m3 unit),the full scale plant was built and started in June 1984. The applied pretreatment only consists of a temperature control. The anaerobic digestion occurs in a 1750m3 cylindrical reactor (13m×13m). The hydraulic retention time is about 24 hours and the loading rate about 8kg of COD/m3.day. During the last ten months, the results observed were showing COD and TSS degradation values of respectively 95 and 90% (see pictures 2 and 3). The medium daily biogas production (65% CH4) is about 5800m3.

Energy from biomass

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PICTURES 2 & 3: THE TSS AND SOLUBLE COD PROFILES IN THE REACTOR The energetic balance of the operation is as follows: biogas produced= autoconsumption (heating)= electric consumption= operating costs saved by anaerobic treatment in compare to aerobic one=

+1100toe/year −150toe/year −50toe/year +600toe/year +1500toe conserved per year

2.2 Treatment of a sulfite evaporation condensate Evaporation of the spent liquors from sulfite pulp mills produces sulfite evaporator condensates. This type of effluent has the following composition and characteristics; acetic acid

=3000mg/l

methanol

=2000mg/l

furfural

=1200mg/l

phenols

=500 to 1000mg/l

SO2

=600 to 2000mg/l

formaldehyde

=10mg/l

The anoxal process: anaerobic treatment of liquid industrial effluents

formic acid

=150mg/l

COD

=7000 to 8000mg/l

pH

=1 to 2

TSS

≠0

585

The complex chemical composition and the presence of substances which may be toxic for the methanogenic bacteria (phenols, polyphenols, free or combined SO2,…) require an adapted population to the substrate. A 14 months pilot plant study was carried out on a 5m3 unit on the industrial site. A long period of time (about 2 months) appears to be required for the start up. The organic loadings to the reactor were slowly increased in steps, allowing time for acclimatation and growth of adapted populations. The optimum loading rate was 8kg COD/m3. day with an hydraulic retention time about one day. The COD degradation was 70% and the biogas productivity from 2 to 3m3/m3.day. The full scale plant is today under construction; the fermentor will be a 2900m3 volume. This unit will treat 21 tons of COD and produce 7800m3 of biogas per day The energetic balance of the operation is as follows: biogas produced= autoconsumption= electric consumption= operating costs saved by anaerobic treatment in compare to aerobic one=

+1500toe/year −150toe/year −100toe/year +1000toe/year +2250toe conserved per year

The economic balance will include the pH neutralization and the nutriments requirements. 3. Conclusions During the last ten years, there have been numerous laboratory studies to demonstrate the various anaerobic treatment systems feasibilities. In view of the differents pilot plant studies and the full scale plant realizations, the upflow anaerobic filter seems to be the fittest anaerobic treatment pro-cess for most industrial wastawaters. In spite of all these advantages, the anaerobic filter isn’t the easier process to scale up; lack of design experiences can lead to hydraulics problems like channeling, dead-zones… In the Anoxal process, these problems are avoided owing to an optimized hydraulic regime (improved liquid distribution system…). The first full scale Anoxal plant has confirmed the realiability of the process; the second one has shown a great methanization potential for pulp and paper wastewaters.

BIOGAS PRODUCTION FROM SOLID PINEAPPLE CANNERY WASTE AT ELEVATED TEMPERATURE M.TANTICHAREON, S.BHUMIRATANA, T.UTITHAM and N.SUPAJUNYA King Mongkut’s Institute of Technology, Thonburi Bangkok 10140, Thailand Summary The results reported herein are methane production using solid waste from pineapple cannery for industrial purpose. The experiments were aimed at reducing retention time and increasing the rate of reaction and amount of loading. The investigations were run at mesophilic and thermophilic temperature (32,37,45,50,55 and 60°C). The reactor was 1 gallon glas bottle with 3 litre working volume. Each reactor received seeding from digester previously operated at ambient temperature with pineapple waste. To minimize the effect of temperature shock, the cultures were acclimatized to the incubation temperature by increasing the digester temperature approximately 1°C/day. Increasing the feed concentration from 12.5 to 17.5gm. wet weight/litre of reactor volume per day at 50 day retention time increased methane production from 1.27 to 1.79litre of reactor volume per day at 55°C and 1.22 1. to 1.46 1. at 37°C. At high feed concentration, the ratio of gas production to total solid added at mesophilic temperature was lower than at thermophilic temperature. Increasing the feed concentration beyond those values indicated above resulted in decreased methane production, pH instability, and subsequent digester failure. The studies indicated that loading rates and organic destruction were higher at thermophilic range than at mesophilic range. The energy required, to maintain the system at higher temperature, is offset by energy gained from the operation.

INTRODUCTION Thailand pineapple-canning industry has grown rapidly. In a factory, 50 percent of the pineapple is left over as fruit waste. It is essential that these solid waste composed of peel and core are disposed of properly. Preliminary studies in our laboratory and subsequent pilot tests in 5M3 digestor at ambient temperature indicated the possibility of producing methane from this waste in large scale. The gas production was approximately 1m3/m3 of reactor volume (1). The results showed that the organic loading was limited to as low as 10kg, wet waste/m3-day. If the gas produced was fully and properly utilized, the large scale production would have a relatively short economic returns. However, to treat the amount of waste left over, the system would be very large and cumbersome. Effect of temperature on rate and degree of conversion on the anaerobic digestion have been

Biogas production from solid pineapple cannery waste at elevated temperature

587

reported in literature (2,3). Within each temperature range (mesophilic and themophilic), the reaction rate increased as the temperature increased. But the temperature effects on reaction rates vary depending on the composition of the substrate used (4). This paper describes the effect of temperature on anaerobic digestion from low to high feed concentrations, using fresh waste of solid pineapple. The net energy return was investigated to examine the feasibility of thermophilic fermentors. MATERIALS AND METHODS Reactors The fermentation vessel was 1 gallon glass bottle with 3 litre working volume. The reactors were placed in a constant temperature water bath adjusted to designed temperature. The reactors were fed once a day or once every few days, and effluent of an equal volume was removed just prior to the feeding. Substrate Fresh pineapple solid waste (peel and core) collected from pineapple cannery in Cholburi Province was chopped and then stored at 4°C until use. The waste contained approximately 95% volatile solid and the moisture content was 81%. The amount of feed indicated in this paper was on a wet weight basis. The effect of temperature on the efficiency of pineapple anaerobic fermentation was studied by varying the fermentor operating temperature. The temperature was increased at a rate of 1°C per day until the working temperature was reached (37,45,50,55 and 60°C). A 30-day acclimation period was allowed. During this period, pineapple was added just enough to maintain the growth of microorganism. After cultures were established, each reactors was fed with a predetermined substrate concentration. The reactors were held at a certain condition for the duration of experiments which no less than 60 days. The gas production was measured daily. The effluent COD and gas composition were also determined. RESULTS AND DISCUSSION 1. Effect of temperature on rate of methane production from anaerobic digestion of solid pineapple waste. In this study, the effect of temperature on anaerobic digestion of solid pineapple waste was investigated in batch digestors which were fed, at 4 days interval, with 25gm solid waste (wet) per litre of the reaction volume. The experiments were carried out at room temperature and at 37,45,50,55 and 60°C . It was found that, for the thermophilic fermentation, the rate of methanogenesis was faster at the higher fermenting temperature (55 and 60°C) than at the lower temperature. The degree of hydrolysis increased and thus affected on the total gas yield. The anaerobic digestion of the substrate at 45°C appeared to be the least efficient (Table 1). In the mesophilic range, the rate of gas production at the temperature of 37°C was slightly higher than that at room temperature. It was observed that the reaction rate of the thermophilic fermentation was higher than that of mesophilic fermentation.

Energy from biomass

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Table 1 also shows that the rate of gas production of the first two days following feeding were approximately the same for the two ranges, but the thermophilic gas production rate of the latter two days were higher. The phenomena could possibly be explained by the fact that the raw materials composed of sugar and organic acids as well as fibrous materials of high molecular weight compound. The conversion of easily digested soluble substrates may be responsible for the initially rapid gas production. The high temperature of the thermophilic range may enhance the hydrolysis of polymeric substrate and made available more substrates for a subsequent methane production. 2. Effect of retention time (RT) Pfeffer (5) showed that effect of temperature on methanogenesis of cattle waste depend on RT and loading rate. For solid pineapple waste of this study, we found that there were practically no effect of RT on the rate of gas produced when RT was higher than 30 days and the feed rate between 6.25–12.5gm. wet waste/l. of reactor volume-day (Table 2). At the higher feed rate, a slight decline in rate of gas production was observed, for the shortest RT. 3. Effect of temperature and feed concentration Table 3 shows the effect of temperature on the highest possible organic loading at 50 days retention time. For both temperature ranges, the gas yield increased proportionally to the loading rate up to the loading of 17.5gm wet weight/l of reactor volume-day. But the efficiency of the mesophilic system decreased with increasing loading rate where as the efficiency of the thermophilic system remained constant. Another point in favor of thermophilic digestion was the favorable physical of sludge residues. Many investigators (6,7) reported the problem of thick scum when plant materials were used. We found that the layer of solids in thermophilic digestion was only of that occured in mesophilic digestor. The interaction of mixed population of microorganism involved in the process of methane formation is complicated subject. The unbalance in the growth of bacterial subpopulations may cause the freguent failure of domestic waste water fermentors (8). As far as COD is concerned, our results raised another speculation on the numbers of bacterial subpopulations actively involved at each selected temperature. We observed a high COD value of liquid effluent with a greater total solid destruction at 55°C which may predict a more active hydrolytic microorganism in the thermophilic range in comparison with mesophilic temperature range. Identification of bacterial subpopulation and chemical analysis of intermediate product would be of interest. 4. System Energy Balance To determine net energy gained at elevated temperature, an energy balance on a system was carried out with the following assumptions: 1. A feed rate of 17.5kg/m3-day, for which the rate of gas production at 55°C is 5.39m3/m3—day and the rate of gas production at 37°C is 4.12m3/m3—day.

Biogas production from solid pineapple cannery waste at elevated temperature

589

2. The system is equiped with a heat exchange to transfer heat from effluent stream to the inlet stream. The exit stream from the exchanger is assumed to be 5°C higher than the inlet stream to the system (at ambient 32°C). This condition implies that the inlet stream into the reactors is at 48°C (7°C below the reactor temperature), thus energy needs to be added to this stream. 3. All heat capacities are the same as that of pure water. 4. The reactor is insulated so that total heat of pure water than 2% of total heat content of the reactor (sensible heat only) over 24 hours period. 5. Heat of reaction is negligible. With the above assumptions, Table 2 summarized net energy gain for various reactor volumes. It is cleared that the energy required by the system is offset by the energy gained from operating at higher temperature. The bigger the reactor, the smaller heat loss per unit volume, thus improved in term of energy. Obviously the final decisions will have to be based on economic considerations.

Table 1 Daily gas production from anaerobic digestor incubated at elevated temperature and fed with 18.75gm wet waste in every 4 day. The daily gas production were averaged from 5 values. day after fed batch

litre of gas/3 L. reactor volume-day at °C 32 37 45 50 55 60

1 3.74 3.76 2.62 2.98 3.27 3.72 2 2.33 2.29 1.71 1.82 2.26 2.40 3 0.87 1.00 1.42 1.47 1.56 1.19 4 0.51 0.56 1.24 1.23 1.04 0.42 Total gas production (L.) 7.45±0.21 7.61±0.44 6.99±0.59 7.5±0.14 8.13±0.16 7.73±0.19

Table 2 Energy analysis of biogas production at 55°C for various reactor sizes, (ambient temperature=32°C) Energy (kJ)\Reactor size (m3)

1

2

3

4

Heat require at start up 96,174.5 192,349.0 384,698.0 577,047.0 Heat loss thru wall 3,833.5 6,085.4 9,660.0 12,658.2 Heat loss thru product gases 41.5 83.0 166.0 249.0 Heat loss thru effluent 219.5 439.1 878.1 1,317.2 Heat gain from gas 7,114.1 14,228.2 28,456.4 42,684.5 Heat gain above digestion at ambient temperature 3,019.5 7,620.7 17,752.2 28,460.2 Energy break even point (days) 32 25 22 20

Table 3 Effect of loading concentration on anaerobic fermentation of pineapple waste at different temperature (loading once a day, RT 50 day)

Energy from biomass

Loading gm. wet waste/L. of reactor volume 12.5

15.0

17.5

590

gas production Temperature L./gm L./L. of reactor °C TS volume-day

% total solid destruction

32 37 55 60

0.49 0.51 0.53 0.51

1.17±0.07 1.22±0.09 1.27±0.02 1.22±0.10

86.48 88.85 90.78 89.40

32 37 55 60 32 37 55 60

0.44 0.44 0.54 0.54 0.43 0.44 0.54 0.54

1.24±0.09 1.24±0.09 1.54±0.09 1.55±0.09 1.42±0.05 1.46±0.07 1.79±0.08 1.79±0.12

80.26 80.19 92.87 93.28 80.28 80.30 91.99 92.24

pH 7.25 7.25 7.60 7.6– 7.7 6.9 7.0 6.95 7.35 6.9 7.0 6.9 7.35

Loading with 20.0gm/L of reactor volume were not possible in every digester. pH dropped from 7.0 to 5.4 with gas production approximately 0.2–0.4 L/L. REFERENCES (1) TANTICHAROEN, M., BHUMIRATANA, S., TIENTANACOM, S. and PENSOBHA, L. (1982). Biogas production from solid pineapple waste. Proceedings of the National Workshop on Agricultural and Agro. Industrial Residue Utilization. Petch-Buri, Thailand, December 13– 18, 1982. (2) COONEY, C.L., and D.L.WISE. (1975). Thermophilic anaerobic digestion of solid waste for fuel gas production. Biotechnol. Bioeng. 17: 1119–1135. (3) PFEFFER, J.T. (1974). Reclamation of energy from organic refuse. Final report EPA-R800776. Department of Civil Engineering University of Illinois, Urbana. (4) Adams, K.H. Optimization of net energy return. The effect of temperature on rate and degree of conversion in anaerobic digestion. Proceeding First Asean Seminar Workshop on Biogas Technology. 16–20 March 1981, Manila, Philippines. (5) Pfeffer, J.T. (1974). Temperature effects on anaerobic fermentation of domestic refuse. Biotechnol and Bioeng. XVI: 771. (6) TANTICHAROEN, M. and CHUNTRANULUCK, S. Biogas production from aquatic weeds. Proceeding of the International solar Energy Society Congress, Brighton, England 23–28 Aug. 1981. Edited by David O.Hall and June Morton. Pergamon Press. (7) CHITTENDEN. A.E., HEAD, S.W. and BREAD, G. Anaerobic digestors for small-scale vegetable processing plants. Tropical Product Institute G 139 August 1980. (8) CHYNOWETH., D.P., and R.A.MAH. (1977). J.Water Pollut. Control Fed 49: 405–412.

ADHESION OF ANAEROBIC BACTERIA FROM METHANOGENIC SLUDGE ONTO INERT SOLID SURFACES D.VERRIER and G.ALBAGNAC Institut National de la Recherche Agronomique BP 39–59651 VILLENEUVE D’ASCQ Cedex—France Summary The mechanisms of bacterial adhesion on solid surfaces in anaerobic fixed film reactors remain poorly understood. The influence of the most significant parameters on the adhesion kinetics are presented as a preliminary contribution. Kinetics of biofilm formation were obtained during 3-months experiments using methanogenic communities continuously fed with a mixture of V.F.A. The fixation of the first bacterial layer was characterized using short submersion times of the support into batch cultures. Bacterial adhesion on glass or P.V.C. slides was quantified using measurement of microbial proteins and microscopic techniques. A rapid initial adsorption (a few hours) is followed by a rather slow thickening of the biofilm. On P.V.C. slides, it was determined during a 60-days experiment that biofilm growth was 0.13µg of protein per mm2 per day. Initial adsorption was optimal at pH 7.4: more than 4×104 bacteria per mm2 were counted within four hours while less than 5×103 bacteria/mm2 were fixed when the pH was adjusted above 6.8 or above 7.8. Calcium and sodium up to 4 milliequivalents per liter had a rather positive effect on the microbial attachment. Scanning electron microscopy showed the prevalence of filamentous acetoclastic methanogens in the fixed biomass. These results are discussed in confrontation with the physico-chemical theories of adhesion.

1. INTRODUCTION Bacterial adhesion onto solid surfaces have been studied in relation with human diseases, dental plaque formation, fouling in marine environments, etc.). However, mechanisms involved in anaerobic fixed film reactors remain poorly understood. General theories (DLVO theory, thermodynamics approach) cannot be useful without previous studies in this particular ecosystem. As a preliminary contribution, the influence of significant parameters on kinetics of anaerobes attachment on inert supports are presented here. 2. MATERIAL AND METHODS Glass and grey Polyvinyl Chloride (P.V.C.) slides were used as supports. Before each experiment, new slides were carefully cleaned and rinsed in distilled water. The device

Energy from biomass

592

schematized in figure 1 was used for long-term adhesion experiments. It consists mainly of a 750ml column with four sampling ports specially designed to facilitate the removal of plane supports without damaging the fixed biomass. Methanogenic bacterial suspensions were from a completely mixed reactor continuously fed with a semisynthetic medium containing acetate, propionate and butyrate (5g/l each) at pH 6.0. The stirred reactor and the column were fed with the same substrate and dilution rate (0.07 day−1). In both cases VFA conversion to methane was complete. Bacterial attachment was measured according to BRADFORD (1) after peeling the slides in 10% trichloroacetic acid and solubilization of proteins in 0.1M NaOH.

Figure 1: Device for the study of anaerobes adhesion rate

The formation of the first bacterial layer was studied in anaerobic flasks (500ml or more) filled with the bacterial suspensions adapted to V.F.A. The P.V.C. slides were submerged and fixed to the flask stopper during the incubation time (0.5 to 8 hours). Then, they were sampled, rinsed with 0.1M cacodylate buffer and stained with acridine orange. They were rinsed in distilled water and viewed at 1000xusing a NACHET NS-400 microscope equipped for epifluorescence. Numerations were done on a minimum of ten fields for each slide. All the experiments were performed at 35°C. 3. RESULTS AND DISCUSSION Long-term experiments showed that bacterial attachment on glass slides was very fluctuating and remained always low. On the other hand, it was higher and increased constantly with time on P.V.C. slides (Table 1). The average rate of biofilm formation was 0.13µg of protein (expressed as equivalent B.S.A.) per 100mm2 of P.V.C. and per

Adhesion of anaerobic bacteria from methanogenic sludge onto inert solid surfaces

593

day. As 1g of protein was equivalent to 5–6×106 bacteria in this case (data not shown), we could calculate that 7×103 bacteria adhered per mm2 of P.V.C. and per day. Scanning electron microscopy evidenced that the spatial distribution of bacteria was much more uniform on P.V.C. than on glass slides. Moreover the predominant bacteria were filaments with septa and irregular surfaces tentatively identified to Methanothrix soehngenii.

Table 1: Biomass fixed on glass and P.V.C. slides in relation with incubation time (results are expressed as g protein equivalent SAB per 100mm2; average of two slides) Incubation time (days) 19 63 Glass 1,61 1,22 P.V.C. 2,50 8,33

Short-term experiments evidenced that initial fouling was a rapid adsorption (a few hours) followed with a rather slow thickening of the bacterial layer (Fig. 2). Rates can be expressed by the relation Xads= k1t½+k2t where k1 is the initial adsorption rate. In subsequent experiments, incubation time was therefore fixed to four hours. Influence of pH was studied in the range 6.5–8.0, pH being adjusted with 6N HCl or 1N NaOH. Optimal pH for initial adsorption was 7.2–7.4 with more than 42×104 bacteria counted per mm2 while less than 5×103 bacteria per mm2 were adsorbed for pH values below 6.8 or above 7.8 (Fig. 3). Influence of cation concentration was then examined using calcium chloride or sodium chloride additions. A strong influence of calcium concentration on bacterial adhesion was observed with an optimal effect at about 2mM of Ca++. Above this concentration a negative effect appeared due to bacterial aggregation (Fig. 4). Sodium additions were less effective. Very similar influences of pH and calcium have been reported with marine bacteria (2, 3, 4). The same effect of calcium on methanogenic granular sludges formation was reported by HULSHOFF POL et al. (5). Nevertheless, the exact mechanisms involved in bacterial adhesion in anaerobic fermenters remain unknown. Three hypothesis at least must be further examined to underline the prevalent one: – As suggested by DLVO theory, electrical double layer must decrease when ion concentration increases in the liquid medium, thus reducing repulsion electrostatic forces provocated when a negatively charged bacteria approaches a surface and allowing attractive VAN DER WAALS forces to predominate. As a consequence, the number of attached bacteria will increase with cation concentration. – Divalent cations may play an active role in the formation of hydrogen bonding between negative surface charges. – Cations may indirectly interact to increase hydrophobicity of surfaces, as suggested by FATTOM and SHILO (6). Moreover, it will be necessary to examine how acid or basic pH modify the polysaccharidic sheath of the bacteria. Though this was not the goal of this study, a great difference was observed between supports like glass and P.V.C. and it will be important

Energy from biomass

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to define their surface characteristics in relation with their ability to promote bacterial adhesion. ACKNOWLEDGEMENTS This study was partly supported by a pluriannual agreement between the French A.F.M.E. and I.N.R.A. REFERENCES (1) BRADFORD, M.M., 1976. A rapid and sensitive method for the quantitation of microgram quantities utilizing the principle of protein-dye binding. Anal. Biochem. 72, 248–254. (2) FLETCHER, M. (1977). The effects of culture concentration and age, time and temperature on bacterial attachment to polystyrene. Can. J. Microbiol. 23, 1, 1–6. (3) STANLEY, P.M., 1983. Factors affecting the irreversible attachment of Pseudomonas aeruginosa to stainless steel. Can. J. Microbiol. 29, 11, 1493–1499. (4) GORDON, A.W. and MILLERO, F.J., 1984. Electrolyte effects on attachment of an estuarine bacterium. Appl. Environ. Microbiol. 47, 3, 495–499. (5) HULSHOFF POL, L., DOLFING, J., DE ZEEUW, W., LETTINGA, G., 1982. Cultivation of well adapted pelletized methanogenic sludge. Biotechnology Letters 4, 5, 329–332. (6) FATTOM, A., SHILO, M., 1984. Hydrophobicity as an adhesion mechanism of benthic cyanobacteria. Appl. Environ. Microbiol. 47, 1, 135–143.

Figure 2: Medial number of attached bacteria vs incubation time in a 2.2×109 bact./ml suspension

Adhesion of anaerobic bacteria from methanogenic sludge onto inert solid surfaces

Figure 3: Medial number of attached bacteria vs pH 4 h-incubation time in a 3.65×109 bact./ml suspension

Figure 4: Medial number of attached bacteria vs Ca++ and Na+ concentration

595

GRANULAR METHANOGENIC SLUDGE: MICROBIAL AND STRUCTURAL ANALYSIS H.C.DUBOURGUIER1, G.PRENSIER2, E.SAMAIN1, G.ALBAGNAC1 1 Institut National de la Recherche Agronomique BP 39–59651 VILLENEUVE D’ASCQ Cedex—France 2

I.N.S.E.R.M.—U 42—CERTIA—59650 VILLENEUVE D’ASCQ— France

Summary In granules sampled from an upflow sludge bed reactor, glucose and lactate were mainly fermented by Propionibacteriaceae. Acetogenesis with obligate hydrogen transfer was performed either by sulphate reducers (lactate) or syntrophs (ethanol, butyrate, propionate). The hydrogen scavenger was Methanospirillum hungatei and the prevalent acetoclastic methanogen was a filamentous organism similar to Methanothrix soehngenii. Scanning electron microscopy revealed a network of Methanothrix entrapping various rod-shaped bacteria, Methanosarcina packets and cell debris. Transmission electron microscopy evidenced a matrix of cell debris entrapping mineral precipitates and individual small colonies made of pure or associated bacteria. Many cells were surrounded by abundant exopolymers appearing as fimbriae, capsules or fibrous glycocalyces. Methanothrix filaments were sometimes observed as winded into balls. Cells of Methanosarcina contained high amounts of cytoplasmic polysaccharidic inclusions. Other bacteria contained cytoplasmic inclusions (polyglucose or polyhydroxybutyrate). Thus, structure of cytoplasmic inclusions and cell morphologies allowed localization and presumptive identification of syntrophs and methanogens. The granules appeared as heterogeneous aggregates including the major trophic groups performing acetogenesis and methanogenesis. In this microecosystem, ultra-structural studies suggest that interspecies transfer of hydrogen and metabolites occured within the granules rather than through the liquid phase.

1. INTRODUCTION In anaerobic ecosystems, bacterial interactions such as interspecies hydrogen transfer and cometabolism may be dependent on the microenvironment. In second generation digesters including anaerobic sludge blankets or fixed-film reactors, bacterial pelletization or formation of biofilms enhance retention of bacterial biomass. But little basic research has been done on the structure of these bacterial aggregates.

Granular methanogenic sludge: microbial and structural analysis

597

2. MATERIAL AND METHODS Anaerobic sludge was sampled from a 5m3 pilot upflow sludge bed treating wastewaters from corn starch industry. Enumerations were done by the MPN method as previously described (5) and quantified by recording growth, microscopic appearance, gas and VFA analysis of the cultures after incubation for 2 to 14 weeks at 35°C. For microscopy, samples were fixed by ruthenium red and glutaraldehyde and postfixed by OSO4 (1). Ultrathin sections for TEM were stained with uranyl acetate and lead citrate. Scanning electron microscopy was performed on samples post-treated with TCH. 3.— RESULTS AND DISCUSSION By the acridine orange method, total counts were between 1010–1011 cells per ml. Enumeration (Table 1) on lactate and glucose indicated that acidogenesesis was mainly due to Propionibacteriaceae. This could be explained by their low Ks for these substrates which confers an ecological advantage compared with C. propionicum and M. elsdenii in substrate-limited conditions. Methanogen numbers were very high (109 cells/ml) and the dominant acetoclastic species was filamentous and morphologically similar to Methanothrix soehngenii. In the prime subcultures, these organisms presented particular surface properties since numerous rods sticked to their filaments; they also agglutinated precipitates of ferrous sulphide. Although they were never observed in numeration flasks, the presence of Methanosarcina sp. was pointed out either by light microscopy or by electron microscopy. The main hydrogenophilic methanogen was a long curved motile rod identified as Methanospirillum hungatei. Short pointed-end rods were also identified as Methanobrevibacter sp. Acetogenesis from lactate was performed by motile curved sulphate reducers (Desulfovibrio?, 108–109 per ml). In contrast, ethanol, propionate and butyrate were mainly catabolized with obligate hydrogen transfer by syntrophic association of rods with M. hungatei. Numbers of sulphate reducers degrading these substrates were lower than those of syntrophs (106–107 and 108–109 cells per ml respectively). Direct optical microscopy and SEM were difficult to perform (Fig. 1) because of masking by exogenous polymers or numerous minerals and cell debris. But in some areas, a network of Methanothrix sp. entrapping other bacteria has been observed. Microcolonies of Methanospirillum sp. or Methanobrevibacter sp. associated with rodshaped bacteria were evidenced (Fig. 3, 4, 5). Methanosarcina sp. appeared as small aggregates or pairs of spherical cells (Fig. 6). Thin sections stained with toluidine blue showed patches of various colonies included in a light material with some deposits of ferrous sulphide (Fig. 2). Electron microscopy evidenced that the light material was mainly composed of a matrix of cell debris entrapping mineral precipitates and colonies of bacteria. In general, cells presenting cytoplasmic inclusions of polyhydroxybutyrate formed pure colonies (Fig. 7). In contrast, cells with a clear cytoplasm and polyglucose inclusions were often associated with short rods morphologically similar to Methanobrevibacter sp. (Fig. 8). In addition, numerous cytoplasmic polysaccharidic inclusions were also observed in

Energy from biomass

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Methanosarcina cells. Methanothrix was evidenced either as individual filaments or as filaments winded into balls (Fig. 9). The presence of high amounts of exopolymers was significant in granules. Indeed, numerous individual bacterial cells and microcolonies were surrounded or included in a glycocalix matrix as described in the rumen (1). These exopolymers appeared as fimbriae (Fig. 10), capsules (Fig. 11) or fibrous glycocalyces (Fig. 12) depending on the morphology of bacterial cells. Such exopolymers have already been mentioned in granules (4) and in biofilms (3). Thus, the granules which are present in the upflow sludge bed reactor appear as heterogeneous aggregates including all the major trophic groups performing acetogenesis and methanogenesis. They are a more complex microecosystem than described by other authors (2). Our results point out several fundamental developments. First, in order to specify the identity and the metabolic function of the various morphotypes, immunological techniques and autoradiography are to be developped. Secondly, exocellular and intracellular polymers are never observed in such high amounts in in vitro cultures. Thus, their presence in the granules may be due to metabolic regulations involved in nutrient limiting conditions. Finally, the whole structure of these granules challenges the concepts issued from known cocultures. Indeed, not only metabolite transfer but also hydrogen transfer must occur inside of the granule to achieve complete methanogenesis. Thus, liquid phase may not be representative for hydrogen or carbon fluxes. REFERENCES (1) CHENG, K.J., COSTERTON, J.W. (1980). The formation of microcolonies by rumen bacteria. Can. J. Microbiol. 26, 1104–1113. (2) LETTINGA, G., HULSHOFF POL, L.W. et al. (1983). Upflow sludge blanket processes. 3rd Anaerobic Digestion Symp. BOSTON. (3) RICHARDS, S.R., TURNER R.J. (1984). A comparative study of techniques for the examination of biofilms by scanning electron microscopy. Wat. Res. 18, 767–773. (4) ROSS, W.R. (1984). The phenomenon of sludge pelletization in the anaerobic treatment of a maize processing waste. Water SA, 10, 197–204. (5) SAMAIN, E., DUBOURGUIER, H.C., ALBAGNAC, G. (1984). Isolation and characterization of Desulfobulbus elongatus sp. nov. from a mesophilic anaerobic digester. System. Appl. Microbiol.

Trophic group Substrate Acidogens

Sulphate Reducers

1st numeration

2nd numeration

Glucose N.D. 1.1×109 Prop. +0.4×107M.elsd. 9 7 Lactate 1.1×10 Prop. + 2×10 M. elsd. 3×109 Prop. 8 Lactate 1.1×10 1.1×109 6 Ethanol 6.5×10 2.0×107 7 Propionate 1.1×10 6.5×107 6 2.0×107 Butyrate 6.5×10

Granular methanogenic sludge: microbial and structural analysis

Ethanol Propionate Butyrate Acetate H2/CO2

Syntrophs

Methanogens

1.1×108 3.0×108 1.1×108 1.5×109 2.2×109

599

2.0×109 2.5×108 1.1×108 2.5×109 2.5×109

Table 1 Bacterial counts in the upflow anaerobic sludge bed. Prop.=Propionibacteriaceae; M. elsd.=Megasphaera elsdenii

Fig. 1: SE Micrograph of a granule (×280)

Fig. 2: Thin-section stained by toluidine blue. Note the presence of Methanosarcina sp.(×1800).

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Fig. 3: SE Micrograph of M. hungatei associated with curves rods (×7250)

Fig. 4: SE Micrograph of Methanobrevibacter associated with rod-shaped bacteria. Note also the presence of ferrous sulphide and of Methanothrix sp.(×7250)

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Fig. 5: Network of Methanothrix sp. entrapping various rod-shaped bacteria

Fig. 6: SE Micrograph of Methanosarcina sp. cells (×22000).

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Fig. 7: Needles of ferrous sulphide and microcolonies of cells accumulating polyhydroxybutyrate (×6300).

Fig. 8: Mixed colony of cells accumulating polyglucose and Methanobrevibacter sp. (×8800).

Granular methanogenic sludge: microbial and structural analysis

Fig. 9: Methanothrix sp. winded into a ball (×9I00)

Fig. 10: A rod showing fimbriae-like exopolymer (×22000).

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Fig. 11: Exopolymers appearing as capsule (×22000).

Fig. 12: Fibrous glycocalyces (×22000).

FULL-SCALE METHANIZATION OF SUGARY WASTEWATERS IN A DOWNFLOW ANAEROBIC FILTER D.VERRIER*, J.P.LESCURE**, B.DELANNOY**, G.ALBAGNAC* *

Institut National de la Recherche Agronomique BP 39–59651 VILLENEUVE D’ASCQ Cedex—France I.R.I.S.—CERTIA—59650 VILLENEUVE D’ASCQ—France **

Summary Methane fermentation of wastewaters in one beet sugar factory located in Northern France (THUMERIES) is performed in a 1,100m3 downflow anaerobic plant packed with plastic rings. The incoming wastewaters (2,000 to 5,000mg COD.l−1) are pumped from the settling ponds and heated with warm condensates through an external heat exchanger allowing an accurate control of the fermenter temperature at 35°C. The biogas is burnt for process steam generation. Fermentation balances obtained during the first start-up procedures are presented. Briefly, very short hydraulic retention times (about 8 hours) and high volumetric loading rates (13kg COD.m−3.day−1) were reached within 3 months. More than 90% removal of the total COD was achieved with a 3,000m3 daily methane production. A survey of the VFA concentration along the reactor height showed a complete elimination in the upper part. As a consequence, a significant bacterial colonization was only observed on the rings sampled at the top of the reactor. V.S.S. concentration in the interstitial medium was low, except in the sludge deposit at the bottom of the reactor. The fixed film observed by scanning electron microscopy revealed a network of filamentous bacteria identified as Methanothrix soehngenii and colonies of coccoïd bacteria.

1. INTRODUCTION Methane fermentation of wastewaters arising from the beet sugar factory BEGHIN SAY in THUMERIES (Northern France) is performed for two campaigns using a downflow anaerobic filter built by S.G.N. according to a process perfected on distillery slops (1). It has to be considered as the first step of a complete wastewater treatment including a nitrification post treatment. This is presently studied at the pilot-scale in fixed film processes. As shown in the flow-sheet (Fig. 1), the anaerobic filter serves as a substitute for the aerobic lagoon. It is fed with the supernatant of the settling pond heated through an external heat exchanger for an accurate control of the temperature to 35°C. Calorific

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energy is supplied by hot condensates. The reactor is a steel cylindrical tank of 12m diameter with a 1,400m3 total volume packed with 1,100m3 FLOCOR R plastic rings. A centrifugal pump (nominal flow=60m3 per hour) ensures the downflow recirculation of waters. The generated biogas is immediately used without any storage nor treatment. It is burnt in a special burner for process steam production. 2. START-UP PROCEDURE AND 1983 BEET CAMPAIGN The anaerobic filter was started in October 1983, after inoculation with 500 tons of anaerobic sludge from MARQUETTE urban digester (31.4g SS.l−1; 12.7g VSS.l−1) and 67 tons of sludge from an anaerobic IRIS plant located in another sugar factory (7.8g SS.l−1; 3g VSS.l−1). Methanogenic activities of these inocula were 0.25 and 0.05kg COD.kg−1 VSS. day−1 respectively and were used to define the initial loading rate. A few days before starting the wastewater feeding, a small amount of concentrated distillery slops was introduced in the fermenter in order to start methanogenic activity without sludge losses. Then, the incoming wastewater flows were gradually increased. As it appears in figure 2, influent COD increased during this campaign from 2,000 to 5,500mg.l−1. Soluble COD represented more than 90% of total COD and was nearly exclusively due to V.F.A. (acetic, propionic and butyric acids). At the end of this first campaign which lasted two months, the obtained performances were as follow: – 1,500m3 of wastewaters containing 5,500mg COD.l−1 could be treated daily with 90% COD removal. – 2,500Nm3 of methane were produced daily, i.e. about 3m3 of biogas (80% CH4) per 3 m of fermenter per day. – residual VFA represented less than 200mg.l−1 while COD of the suspended solids was less than 500mg.l−1. – total nitrogen was about 120mg.l−1 and ammonia-nitrogen about 75mg.l−1 in the treated effluent. The survey of VFA concentrations and pH along the reactor height revealed a gradient as illustrated by figure 3a. The majority of substrate elimination was realized in the upper part of the reactor. As a consequence, a significant bacterial colonization was only observed on the rings sampled at the top of the reactor (Fig. 3b). Volatile Suspended Solids concentration was low in the interstitial medium, except in the sludge deposit observed at the bottom of the reactor. Sampled colonized rings were prepared for Scanning Electron Microscopy according to COSTERTON technique (2). As shown in figure 4, the biofilms observations revealed a network of filamentous bacteria identified as Methanothrix soehngenii, sometimes forming microcolonies (A); in the upper part of the reactor, colonies of coccoïd bacteria (presumably Methanosarcina sp.) were simultaneously observed (B). Consortia of hydrogenophilic Methanobrevibacter-like (C) with ovoid bacteria (D) presumably OHPA species, were also noticed. This ecology results of the particularity of the substrate in which the soluble fraction is only composed of V.F.A. and is related to gradient in the reactor.

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3. RESTART-UP DURING 1984 SYRUP AND BEET CAMPAIGNS After two months starvation, the fermenter can be heated again during the syrup crystallization campaign producing low-temperature lost calories. Restart-up was very quick and wastewater flow rates were increased to reach very short hydraulic retention times (about 8 hours) and high volumetric loading rates (13kg COD per m3 per day). Nevertheless, COD removals were somewhat reduced to about 80% due to a loss of suspended solids in the effluent and the recycling pump was therefore stopped. Biogas and methane yields were 370 and 320l per kg removed COD respectively. It shoud be stressed that the methane content of the gas was very high (87–88%) and very constant during this 40 days-campaign. The combustion of this gas produced 30 tons of steam daily. At the end of this campaign, new sampling of the rings and of the interstitial medium allowed the estimation of the biomass stock accumulated

Figure 1: Flow-sheet of wastewater treatment plants

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Figure 2: Influent and effluent COD during first start-up

Figure 3: V.F.A. and biomass gradients along the fermenter

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Figure 4: Interior of a biofilm sampled at the top of the fermenter (SEM JEOL JSM-35 CF)

in the fermenter and the carbon balance presented in Table 1. This evidenced a twofold biomass increase and a 9% carbon deficit which can be attributed to methane losses in the effluent. After a new six-months starvation, the restart-up was again very quick as soon as temperature in the fermenter reached 35°C. For influent COD values between 2,000 and 2,800mg.l−1 during this campaign, and for hydraulic flows of 100 to 140m3.h−1, daily methane production was about 1,700m3 per day and soluble COD in the effluent was about 200–300mg.l−1 In the future, a modification of the water circuits will allow an increase of the COD and hence of the volumetric loading rates. During starvations, an increase of free Kjeldahl nitrogen in the fermenter was observed, presumably due to a slow hydrolysis of proteinic matter. 4. CONCLUSION After two beet campaigns, anaerobic filtration of dilute sugar factory wastewaters appears to be an efficient and reliable process. In the downflow system, the fixed microorganisms are actually the predominant responsible of the dépollution efficiency.

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ACKNOWLEDGMENTS This study was supported by the French A.F.M.E. while financial assistance to the project was partly supported by the F.I.R.S., the Agence de l’Eau ARTOIS-PICARDIE and the A.F.M.E. REFERENCES (1) BORIES, A., RAYNAL, J., JOVER, J.P., 1982. Fixed film reactor with plastic media for methane generation of distillery wastewaters. 2nd E.C. Conference Energy from Biomass, BERLIN, 567–571. (2) COSTERTON, J.W., 1980. Some techniques involved in study of adsorption of microorganisms to surfaces. In Adsorption of Microorganisms to Surfaces, Ed. G.BITTON and K.C.MARSHALL, 403–432. INCOMMING Initial fermenter content Organic C 1 647 Mineral C 101 Influent Organic C 94 203 Mineral C 3 407 Total 99 358 FINAL Final fermenter content Organic C 3 413 Mineral C 130 Effluent Organic C 15 740 Mineral C 30 475 Gaz Methane 36 232 CO2 4 642 Total 90 632

Table 1: Carbon balance (kg C) obtained during 1984 syrup campaign

METHANE FERMENTATION OF DISTILLERY WASTE WATER OF SUGAR CANE ALCOHOL ON A FIXED BIOMASS PILOT A.BORIES*, F.BAZILE**, J.RAYNAL*, E.MICHELOT** INSTITUT NATIONAL DE LA RECHERCHE AGRONOMIQUE * Station d’Oenologie et de Technologie Végétale F- 11104 NARBONNE ** Station de Technologie F- 97170 PETIT-BOURG Summary Feasability of the methane fermentation for waste treatment and energy recovery of molasses sugar cane stillage is studied at pilot scale on a fixed bed reactor (10m3) with plastic support (FLOCOR). Reactor performance data are particularly good=load: 14.2–20.4kg DCO/m3.d., HRT: 3.2–2.5d., biogas productivity: 6.5–8m3/m3.d. COD elimination rate are optimal for this type of waste water: 60–73 p.100 and BOD rate are better than 90 p.100. The biofilm measurement after one year of experimentation shows a great concentration of fixed matter, equivalent to 47g/l of reactor and confirms the good ability of this support for microbial biomass. Biogas production from molasse stillage (22m3/m3 of stillage) is able to account for 48 p.100 of the distillation energy consumption.

1. INTRODUCTION La production d’alcool à partir de canne à sucre (alcool industriel, rhums) et notamment des mélasses est une activité à fort potentiel de pollution. Les effluents sont particulièrement concentrés en matières organiques (DCO=60–100g/l) et minérales. En outre la distillation s’effectue sur des milieux à faible degré alcoolique, d’où d’importants volumes de rejets et des besoins énergétiques élevés. La fermentation méthanique peut s’appliquer à ces eaux résiduaires avec les objectifs: dépollution—valorisation énergétique. Cependant, les technologies classiques de fermentation: mélange complet, contact anaérobie, sont limitées dans leur performance par des aspects d’ordre biologique: faible taux de croissance des bactéries méthanogènes. La conception de réacteurs améliorant la rétention des micro-organismes permet de contourner ces limitations et d’augmenter les capacités de traitement: réacteurs à lit fixé, réacteurs à lit fluidisé (1).

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Grâce au développement de nouveaux supports (matières plastiques) pré-sentant des avantages par leur surface spécifique, leur indice de vide, et leur poids, les réacteurs à lit fixé ont montré des performances élevées (2). L’expérimentation à l’échelle pilote d’un réacteur à film fixé sur support plastique est réalisée en méthanisation de vinasse de mélasse de canne à sucre. L’étude vise à préciser la faisabilité de la dépollution de ce milieu par fermentation et à déterminer les performances du réacteur en regard de résultats acquis par ailleurs (2). 2. MATERIEL ET METHODES 2.1. Fermenteur à film fixé sur support plastique La plateforme expérimentale (+) comprend un fermenteur de 10m3, contenant un support en PVC, sous forme d’anneaux (FLOCOR R.), dont la surface spécifique est 230m2/m3 et la porosité de 95% (pourcentage de vide). Le réacteur est alimenté en circuit down-flow, avec une boucle de recirculation de la phase liquide, également en down-flow, pour assurer l’ho-mogénéisation du milieu de fermentation. La fermentation est effectuée à 37°C. La plateforme dont la conception générale est analogue à celle dé-crite précédemment (2) est équipée d’un gazomètre souple (10m3), d’un moteur à biogaz, et d’un ensemble de régulations et de mesures: températures, débits gazeux, liquides. Elle est implantée en Guadeloupe (France) à la Société Industrielle de Sucrerie. 2.2. Substrat Les vinasses de mélasse de canne à sucre sont collectées en sortie de distillation, refroidies dans une tour à ruissellement, puis dirigées vers une cuve tampon (1m3) en amont du réacteur. Un lot de vinasse de mélasse a été stocké afin d’assurer la continuité des essais hors périodes de distillation. Les vinasses ne subissent aucune correction de composition ni de pH, sauf lors de la phase d’ensemencement du réacteur (pH 7,5). La composition moyenne des vinasses est mentionnée dans le tableau 1. 2.3. Méthodes analytiques La fermentation méthanique est suivie par détermination du pH, de la demande chimique en oxygène (DCO) sur les milieux brut et centrifugé, de la demande biochimique en oxygène (DBO) sur les milieux brut et centrifugé, des acides gras volatils (AGV) par chromatographie en phase gazeuse. Les matières en suspension (MES) sont mesurées après centrifugation et séchage du culot à 105°C. La composition du biogaz est déterminée par la mesure du CO2, CH4 et hydrogène sulfuré après chromatographie en phase gazeuse et dé-tection par catharomètre. L’analyse du substrat et du digestat porte également sur l’azote total Kjedahl (NTK), et les éléments minéraux: Phosphore total, sulfate, calcium, potassium, sodium.

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3. RESULTATS – Ensemencement. La fermentation méthanique des vinasses de mélasse est opérée à partir de flores anaérobies issues de milieux naturels, préalablement sélectionnés par des tests de fermentation. L’ensemencement du réacteur est effectué par l’apport de 4m3 de suspension de boues, de lm3 de substrat neutralisé à pH 7,5 et un complément d’eau. Pendant la phase d’adaptation des populations, l’alimentation du ré-acteur est assurée à la charge volumique de 1,5 à 6kg DCO/m3j. Durant cette période d’environ 40 jours, on note l’accumulation dans le milieu de la DCO: jusqu’à 20g/l, et des acides gras volatils: acétate: 0,5–1g/l; propionate: 1–1,9g/l. La diminution brutale observée par la suite sur ces paramètres témoigne de l’acclimatation complète des populations (DCO résiduelle ≠16g/l, acétate: 300mg/l, propionate: 200mg/l). Dès lors, l’expérimentation consiste à augmenter la quantité de substrat apporté, par palliers. – Performances du réacteur. Sur une période ininterromoue de 180 jours, la charge volumique a été augmentée jusqu’à 20,4kg DCO/m3j, et le temps de séjour hydraulique diminué de 20 à 2,5j. Le tableau 2 rassemble les moyennes des valeurs obtenues dans la période d’essais à fortes charges. (+)Société Générale Pour Les Techniques Nouvelles—Saint Quentin les Yvelines FRANCE. La stabilité de la fermentation et les valeurs optimales d’épuration (DCO>71 p.100, DBO>90 p.100) sont maintenues pour des charges atteignant 14,2kg DCO/m3.j. La productivité du réacteur est élevée: 6,3m3 biogaz/m3.j., et le rendement de gazéification varie de 224 à 288l CH4/kg DCOi. Pour des charges volumiques extrêmes: 17,4–20,4kg DCO/m3.j., la diminution du rendement d’épuration (60–62 p.100 de la DCO), ainsi que l’augmentation des teneurs en acide acétique (0,4g/l) et propionique (1,2g/l) sont observées sans toutefois déséquilibrer le système. La productivité en biogaz est encore augmentée: 8m3/m3.j. – Dépollution organique, azotée, minérale. Le tableau 1 indique la composition type du digestat. Le taux d’élimi-nation maximal de la DCO enregistré pendant les essais est compris entre 72 et 75 p.100. La charge organique résiduelle est encore importante (DCO: 10–16g/l), mais non biodégradable. Les valeurs de la DCO indiquent en effet une élimination quasi complète des substances biodégradables (90–95 p.100). La composition des vinasses en azote montre une proportion équilibrée: DBO/N=100/3. La fermentation méthanique n’en consomme qu’une faible part, de 15 à 30 p.100, soit environ 150mg N/l. On peut évaluer ainsi la production potentielle de biomasse à 3g/l soit 9 p.100 de la DCO dégradée. Quant au phosphore, les valeurs paraissent suffisantes, avec une élimination poussée. – Composition du biofilm. L’analyse du biofilm a été pratiquée à l’issue de l’expérimentation (tabl. 3). La colonisation du support au bout de près d’une année représen-te 0,8g matières fixées/g

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support, soit l’équivalent d’une concentration de biomasse de 47g/l de réacteur. Exprimée par rapport aux matières volatiles (MVS) fixées sur le support, la charge massique appliquée représente 0,5–0,6g DCO/g MVS. La minéralisation du biofilm ne semble pas excessive, compte tenu de la composition minérale du substrat. La proportion d’azote et de phosphore est proche de boues bactériennes anaérobies. On ne relève aucune précipitation de matières minérales sur le support. – Potentiel énergétique. Le potentiel énergétique de la méthanisation des vinasses de mélasse a été dressé et situé dans le contexte de la distillerie. – production d’alcool 1m3 (référence) – consommation d’énergie de la distillation 0,33 TEP – production de vinasse 15,4m3 – production de biogaz 339m3 – production de méthane 186m3 – potentiel énergétique (pouvoir calorifique) 0,158 TEP (48 p.100)

4. DISCUSSION—CONCLUSION La fermentation méthanique des eaux résiduaires de distillation d’alcool de canne à sucre (vinasse de mélasse) en réacteur à film fixé sur support plastique est réalisée dans des conditions optimales tant au niveau des performances cinétiques qu’en dépollution. Vis à vis des matières organiques des vinasses de mélasse, la fermentation est un procédé efficace qui élimine plus de 90 p.100 de la fraction biodégradable (DBO). Le rendement sur la DCO est plus limité (73 p.100); il souligne la nature réfractaire des substances résiduelles: mélanines, composés phénoliques,…Ces résultats sur la dépollution s’avèrent cependant au moins aussi intéressants que ceux obtenus avec les systèmes aérobies. La méthanisation se présente comme la filière biologique la plus avantageuse. Les performances très élevées enregistrées ici avec le réacteur à bio-masse fixée sur supportplastique (C.V.: 14,2–20,4kg DCO/m3.j., temps de séjour: 2,5–3,2j., productivité: 6,5–8m3 biogaz/m3.j.) confirment les résultats obtenus précédemment sur d’autres substrats (2). La concentration en matières fixées (équivalent à 47g/l) montre la capacité de ce type de support dans l’édification du biofilm et dans la rétention des micro-organismes et justifie les performances obtenues. La charge massique appliquée représente 0,5–0,6g DCO/g MVS. La comparaison avec les autres technologies expérimentées dans ce domaine atteste le très bon niveau des résultats. Les procédés de type “mélange intégral” fonctionnent à des charges volumiques de 2,4 et 3,2kg DCO/m3.j. (3,4). En réacteur “pseudo-contact-lit de boues”, HIATT, 1973 (5) obtient une charge de 10kg DCO/m3.j. POLE et RAMESH KUMAR (1984) mentionnent pour un digesteur U.A.S.B. des valeurs de 4 à 7kg DCO/m3.j.(6). En ce qui concerne les systèmes à biomasse fixée (film fixé), des charges de 6 à 13,3kg DCO/m3.j. sont obtenues

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à l’échelle du laboratoire (4,7). En filtre anaérobie à support plastique orienté et à l’échelle industrielle, SZENDREY, 1983, indique une charge de 7kg DCO/m3.j pour un temps de séjour de 9j (8). Les très bonnes conditions de fermentation permettent d’envisager l’aspect valorisation énergétique de ces résidus. Près de la moitié de la consommation énergétique de la distillation d’alcool peut être couverte par la méthanisation des effluents. 5. BIBLIOGRAPHIE (1) BORIES A., VERRIER D., 1984. Ind. Alim. Agric., 101, 493–497. (2) BORIES A., RAYNAL J., JOVER J.P., 1982. Energy from biomass, 2nd E.C. Conf. STRUB, CHARTIER, SCHLESER. 567–571. (3) ROTH L.A., LENTZ C.P., 1977. Can. Inst. Food Sci. Technol. J., 10, 2, 105–108. (4) VAN DEN BERG L., KENNEDY K.J. 1982. Energy from biomass and wastes. VI Buena Vista. Florida. 21 p. (5) HIATT W.C., CARR A.D., ANDREWS J.F., 1973. 28th Purdue Ind. Waste Conf. Proc., 142, 2, 966–976. (6) POLE K.M., RAMESH KUMAR I.V., 1984. Energy from biomass and wastes. VIII Buena Vista. Florida. 22 p. (7) BORIES A., 1981. Trib. CEBEDEAU 456, 34, 475–483. (8) SZENDREY M.L., 1983. Energy from biomass and wastes. VII Buena Vista. Florida. 24 p.

Table 1: Analysis of sugar cane molasses stillage and of effluent of methane fermentation stillage effluent pH 4.2 Total Suspended Solid (g/l) 2.1–2.8 COD (g O2/l) 51–57 BOD (g O2/l) 16.5–21.6 BOD/COD 0.35–0.5 Nitrogen Kjeldahl (mg N/l) 690–728 Phosphorus (mg P/l) 80–180

7–7.5 0.7–2 10–16 0.5–2.5 0.2 560 33

Table 2: Performance evaluation of the methane fermentation of rum stillage on fixed film reactor (10m3) with plastic support (Flocor). load (kg DCO/m3.d.) 9.2 11.4 14.2 20.4 19.4 17.4 HRT (d.) 4.9 4 3.4 2.7 2.8 3.2 Biogas productivity (m3/m3.d.) 4.5 5.6 6.3 8 7.3 6.8 Biogas production (m3/m3. stillage) 22.3 22.5 21.3 21.4 20.7 21.8 Gasification rate (1 CH4/kg CODi) 288 287 224 216 206 212 COD substrate (g O2/l) 47.7 46.3 48 54.6 55.4 55.7 COD elimination rate (p.100) 72.1 71.6 71.3 61.9 60.4 62.4 acetate (g/l) 0.3 0.3 0.3 0.4 nd nd propionate (g/l) 0.4 0.5 0.5 1.2 nd nd

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nd: no determination

Table 3: Analysis of the biofilm on the plastic support (FLOCOR) dry matter 0.83g/g support solid volatil matter 64 p.100 dry matter SVM Nitrogen Kjeldahl (N) 3.82 ″ ″ Phosphorus (P) 1.38 ″ ″ Calcium (Ca) 5.67 ″ ″ Potassium (K) 2.82 ″ ″ Magnesium (Mg) 1.01 ″ ″ Sodium (Na) 0.57 ″ ″

FIXED BIOMASS ON LIGNOCELLULOSIC MEDIA FOR THE METHANE FERMENTATION OF INDUSTRIAL WASTE WATER A.BORIES*, M.DUVIGNAU et N.CATHALA INSTITUT NATIONAL DE LA RECHERCHE AGRONOMIQUE Station d’Oenologie et de Technologie Végétale F. 11104 NARBONNE Summary Lignocellulosic supports are used for micro-organisms fixation in two reactors design: fluidized bed and fixed bed. Comparison between lignocellulosic (wood, vine shoot) and inert (sand, PVC) media shows better fixation on the first type of supports. The effect of adjuvants: methanol, biopolymers, on microbial adhesion is studied. Alginate and pectin addition (0.1–10mg/l) improves adhesion to wood particles. A fluidized bed reactor with cork support is experimented for the methane fermentation of dairy by-product (deproteinized whey). After three months, reactor performance data are: load: 7.48g COD/l.d., HRT: 2.8d., productivity: 3.8l biogas/l.d., COD elimination rate: 96 p.100. For the fixed bed reactor, the selected filling matter is an agricultural by-product: rape of grapes. The methane fermentation is achieved on a distillery waste water (wine stillage). Performance data, after 8 months are: load: 5.1g COD/1. d., HRT: 3.2d., COD elimination rate: 93.8 p.100. Fixed matter is well distributed all over the reactor height (0.6 to 1.1g dry fixed matter/g support). Lignocellulosic matter seems to be interesting supports for performant and rustic design reactors (low weight, wide variety and cost: low to nonexistent).

1. INTRODUCTION Les réacteurs à biomasse fixée apportent des gains très appréciables sur les performances cinétiques de la fermentation méthanique. Les supports de fixation varient dans leur conception: fixe, mobile, dans leur agencement: vrac, orienté, dans leur nature (1). De très nombreux matériaux ont été proposés: -matières minérales: galets, supports d’argile orientés pour les lits fixés, sable pour les lits fludisés, -matières de synthéses: chlorure de polyvinyl, polyuréthane,…, ou encore -matières d’origine organique: charbon actif (2,3,4).

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Les matières lignocellulosiques peuvent aussi être proposées comme supports dans les deux types de réacteurs: lit fixé, lit fluidisé. Elles sont en général très difficilement dégradées en anaérobiose et se rencontrent sous des formes très diverses: biomasses végétales (bois,…), dé-chets agro-industriels (rafles, bagasse,…). Elles allient plusieurs avantages: faible densité d’où intérêt pour les lits fluidisés, coût peu élevé voire nul. La composition très complexe de ces matières fournit une surface de contact substratumbactéries riche en sites pouvant intervenir dans les phénomènes d’adhésion et/ou d’adsorption. Dans la présente étude, nous avons examiné la fixation des micro-organismes sur des matières lignocellulosiques et étudié le comportement de deux types de réacteurs: lit fluidisé, lit fixé, en fermentation d’eaux rési-duaires d’industries agro-alimentaires. Pour le lit fluidisé, un support végétal très léger, le liège, a été utilisé. Les performances du réacteur ont été évaluées en fermentation de lactosérum déprotéinisé. En lit fixé, le garnissage retenu est un sousproduit agricole: rafle de raisin, et l’étude de la fermentation porte sur un effluent de distillerie. 2. MATERIEL ET METHODES 2.1. Matériel de fermentation – Réacteur à lit fluidisé Il est constitué par une colonne en verre de diamètre intérieur 6,7cm et d’un volume de 2l, thermostatée à 37°C. A la partie supérieure de la colonne un tamis de maille 0,2mm retient les particules de support. Le support est du liège de granulométrie: 0,2–0,35mm, à la concentration de 20g/l. La fluidisation est assurée par recirculation de gaz (0,1l/mn) injecté au bas de la colonne. Le substrat est introduit au même niveau et réparti de façon homogène au sein du réacteur par recirculation du milieu de fermentation à contrecourant du gaz, à égal débit. – Réacteur à lit fixé Il consiste en une colonne en PVC, de 20cm de diamètre, thermostatée à 37°C. Le volume total liquide du réacteur est de 34,9l. le garnissage lignocellulosique expérimenté est un sous-produit de la vigne: rafles de raisin qui sont sous forme de tiges de 2 à 8cm de longueur et quelques millimètres de diamètre. Le poids de support initialement introduit est de 1725g. Le substrat de fermentation est apporté en continu à la partie inférieure du réacteur qui fonctionne en circuit up-flow. La phase liquide est recyclée à 1l/hr également en up-flow. – Dispositif d’étude de la fixation sur divers supports Les fermentations sont réalisées en fioles de 500ml, disposées sur table d’agitation orbitale à 37°C, contenant la suspension microbienne (200ml) et le support (8g). L’alimentation en substrat est séquentielle: 20ml tous les trois jours soit 1,2g DCO/l.j., de façon à maintenir l’ac-tivité tout au long de l’essai (30j). Les supports testés sont: le bois, le sarment de vigne, le PVC, le sable. Leur granulométrie est 0,2–2mm.

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2.2. Substrats de fermentation Les fermentations avec biomasse fixée sur particules mobiles sont menées sur lactosérum déprotéinisé. Ce milieu est conservé au froid sous forme concentrée, puis dilué à la concentration souhaitée au moment des essais. Le substrat utilisé avec le réacteur à lit fixé est une eau résiduaire de distillerie: vinasse de vin rouge, obtenue dans plusieurs établissements et dont la DCO varie de 16 à 36g O2/1. 2.3. Populations microbiennes La fermentation méthanique du lactosérum déprotéinisé est opérée à partir d’une flore issue d’un digesteur de boues de station d’épuration d’eaux usées urbaines, adaptées au laboratoire sur le substrat pendant plusieurs mois. La flore microbienne utilisée pour la fermentation de l’effluent de distillerie provient d’une population d’un digesteur pilote industrieletest entretenue sur ce substrat en réacteur mélangé. 2.4. Méthodes analytiques Le suivi des fermentations porte principalement sur les paramètres: pH, demande chimique en oxygène (DCO), acides gras volatils (AGV), volume et composition du biogaz, matières en suspension (MES). La DCO est dosée selon la norme AFNOR sur un échantillon centrifugé à 10 000t/mn pendant 10mn. Les AGV sont dosés par chromatographie en phase gazeuse sur colonne SP 1200 (SUPELCO Inc.), à 105°C en présence d’acide éthyl2butyrique comme étalon interne. Le volume de biogaz est mesuré par compteur volumétrique de type SCHLUMBERGER. Sa composition est déterminée par analyse en chromatographie et détection par conductibilité thermique, après séparation des composants sur deux colonnes: silicagel, tamis moléculaire 5X, montées en séries. La mesure des matières fixées sur les supports mobiles est effectuée après séparation des bioparticules par filtration sur tamis de 0,2mm et séchage à 105°C. la biomasse fixée est évaluée par le dosage de la teneur en azote total (Kjeldahl). La valeur de référence de la composition des bactéries est mesurée sur une culture témoin, sans support. La composition du support en azote est également déterminée. Cette démarche est pratiquée pour les supports organiques: bois, sarment, PVC. Pour le sable, les matières fixées sont mesurées directement par les matières volatiles après passage au four à 550°C. Pour le support en lit fixé, le biofilm est séparé par agitation dans l’eau et les matières détachées sont mesurées après centrifugation. 3. RESULTATS. DISCUSSION 3.1. Adhésion bactérienne sur supports lignocellulosiques L’étude comparative de la fixation des micro-organismes sur des supports lignocellulosiques et sur des supports inertes (PVC, sable) montre qu’après 30 jours de

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culture, les résultats les meilleurs sont enregistrés avec les particules végétales: bois, sarment (fig. 1), et dans une proportion importante. L’influence d’adjuvants connus pour leur effet favorable sur les phé-nomènes d’adhésion a été examinée. Le méthanol stimulerait la synthèse de polysaccharides de bactéries méthanogènes (5). L’addition de méthanol dans nos cultures, à doses similaires à celles mentionnées, se solde par un effet défavorable sur la quantité de matière fixée, pour les divers supports hormis le PVC. On peut penser que les populations ne sont pas suffisamment adaptées à ce composé et/ou à un effet toxique. Des biopolymères participent aux phénomènes d’adhésion. Les alginates sont des agents adhésifs en milieu marin (6). Les polyosides interviennent dans des pontages bactéries-végétaux (7). L’apport de pectines et d’alginates dans nos cultures en présence de support lignocellulosique (bois) améliore nettement les quantités de matières fixées= gain de 19,6 et 37,5 p.cent respectivement, après 30 jours. 3.2. Réacteur à lit fluidisé sur support liège La montée en charge volumique du réacteur a été effectuée en maintenant le temps de séjour hydraulique, constant del 10 jours, et en augmentant par palliers la concentration du lactosérum. Pour la gamme de charge étu-diée, 1,84 à 7,48g DCO/l.j., on observe un taux optimal d’élimination de la DCO (tabl. 1) s’améliorant avec l’augmentation de la charge, ce qui indiquerait une acclimatation progressive de la flore au substrat. La productivité du réacteur en biogaz est augmentée de 1 à 3,89l/l.j. Dans une seconde phase d’étude, la charge volumique précédemment atteinte a été maintenue constante, et le temps de séjour hydraulique diminué de 10 à 5 à 2,5j (tabl. 1). Cette forte diminution du temps de séjour n’affecte pas les performances de la fermentation, ce qui suppose une retention efficace des micro-organismes par fixation sur le support liège. De très faibles teneurs en AGV soulignent la stabilité du processus. La légère diminution de la productivité en biogaz observée pour Tsh=2,5j est due à des composés lentement hydrolysables ou fermentescibles. Ces résultats sont très encourageants car obtenus après seulement trois mois de fonctionnement du réacteur fluidisé, ce qui est relativement court pour ce type de réacteur. Ils sont en accord avec ceux mentionnés par SUTTON et LI (1982) (8) dont l’étude portait sur un substrat identique mais en réacteur fluidisé avec le sable comme support. Des performances plus é-levées sont signalées par (9) en fermentation de lactosérum acide, mais après une année de fonctionnement (CV=37,6g DCO/l.j.). 3.3. Réacteur à lit fixé Le réacteur à garnissage lignocellulosique: rafle de raisin, montre de bonnes performances en fermentation méthanique de vinasse de vin. Après 8 mois de fermentation, les valeurs optimales sont: temps de séjour hydraulique: 3,2j, charge volumique: 5,1g DCO/l.j. pour un taux d’épuration de la DCO de 93,8 p.cent. La productivité volumique atteint 2,07l biogaz /l.j.(tabl. 2). L’étude du profil de matières fixées sur ce support lignocellulosique montre pour ce système de réacteur up-flow recirculé une répartition des boues dans toute la hauteur du

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lit, avec cependant une plus grande quantité en partie inférieure (tabl. 3). La quantité de biomasse retenue par le support est importante: 0,6 à 1,1g/g de support. L’observation du support montre un biofilm enrobant les tiges de rafles. Après lavage, aucune dégradation importante n’est relevée, et l’analyse de fibres confirme de faibles modifications de sa composition après 8 mois de séjour dans le réacteur. Ce type de support peut être envisagé pour des utilisations à plus long terme. 4. CONCLUSION Les matériaux lignocellulosiques s’avèrent de bons supports de fixation de microorganismes. Leur potentialité vis à vis de l’adhésion bacté-rienne semble supérieure à celle des supports inertes, généralement utilisés: sable, PVC. Par leur composition, ils peuvent offrir des possibilités d’amélioration de la colonisation du support, par utilisation d’adjuvants. Cette phase est la plus importante dans la mise en oeuvre de réacteur fluidisé. Sur le plan de la technologie des réacteurs, la diversité des matières lignocellulosiques permet de multiples solutions: – support léger, rendant le réacteur fluidisé plus abordable. – support fixé concourant à des réacteurs rustiques et performants. Les performances obtenues dans les deux cas soulignent l’intérêt de tels réacteurs, dans le traitement anaérobie d’effluents agro-industriels. 5. BIBLIOGRAPHIE (1) BORIES A., VERRIER D., 1984. Ind. Alim. Agric., 6, 493–497. (2) BORIES A., RAYNAL J., JOVER J.P., 1982. In STRUB A., CHARTIER P., SCHLESER G., Energy from biomass, 2nd EC. Conference, BERLIN. Applied Science Publishers, London. (3) HENZE M., HARREMOES P., 1983. Wat. Sci. Technol., 15, 1–101. (4) SWITZENBAUM M.S., 1983. Wat. Sci. Technol., 15, 345–348. (5) BULL M.A., STERRIT R.M., LESTER J.N., 1982. Trans. I. Chem. E., 60, 373–376. (6) MORRIS E.R., REES D.A., YOUNG., WALKINSHAW M.D., DARKE A., 1977. J. Mol. Biol., 110, 1–16. (7) FLETCHER M., FLOODGATE G.D., 1973. J. Gen. Microbiol., 74, 325–334. (8) SUTTON P.M., LI A., 1982. Proc. 36th. Purdue Indust. Waste Conf. 665–677. (9) HICKEY R.F., OWENS R.W., 1981. 3rd Symp. on biotechnology in energy production and conservation. May 12–15, GATTLINBURG, Tenessee.

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FIG. 1: COMPARAISON DES MATIERES FIXEES SUR DES SUPPORTS LIGNOCELLUSOSIQUES ET DES SUPPORTS INERTES. ENFLUENCE DE L’ADDITION DE METHANOL SUR L’ADHESION.

FIG. 2: EFFET DE L’ADDITION DE DIOPOLYMERES (ALGIMATE, PECTINE) SUR L’ADHESION MICROBIENNE SUR DES PARTICULES DE BOIS

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Tableau 1: Performances en fermentation méthanique de lactosérum déprotéinisé d’un réacteur fluidisé avec support en liége. charge tps de séjour DCO DCO taux productivité AGV (mg/l) volumique hydraulique substrat digestat d’élimination biogaz (l/l.j.) acétate (g DCO/l.j.) (j.) (mgO2/l) (mgO2/l) DCO (p.cent) propionate 1,8 3,9 5,6 7,5 7,4 7,4

10 ″ ″ ″ 5 2,5

18 700 37 380 56 110 74 801 37 600 18 726

1 206 1 100 990 910 750 670

93,6 97,1 98,7 98,8 98,0 96,4

1,0 2,2 3,1 3,9 3,6 3,9

nd 180 nd 216 6 42

nd 331 nd 331 252 136

nd: non déterminé

Tableau 2: Performances en fermentation d’eau résiduaire de distillerie, d’un réacteur à lit fixé, à garnissage lignocellulosique: rafle de raisin. charge volumique tps de séjour (g DCO/l.j.) hydraulique (j.) 2,3 3,7 4,2 5,1

productivité p biogaz/l.j.

15,7 6,7 5 3,2

DCO substrat g O2/l

1,2 1,8 2,3 3,4

taux d’élimination DCO (p.cent)

36,1 24.8 21,0 16,3

Tableau 3: Profil des matières fixées sur le support: rafle de raisin, dans le réacteur à lit fixé, après 8 mois de fermentation. hauteur du prélèvement cm 20 40 60 80

Matières fixées g/g support g/l réacteur 1,10 0,77 0,93 0,62

54,6 37,8 45,7 30,4

87,2 89,4 88,7 93,8

TWO-PHASE DIGESTION OF DISTTLLERY SLOPS USING A FIXED BED REACTOR FOR BIOMETHANATION K.Wulfert and P.Weiland Institute of Technology, Fed. Res. Centre of Agriculture (FAL) D-3300 Braunschweig (FRG), Bundesallee 50 Summary In order to determine the most important factors for obtaining a high efficient biomethanation of potatoe distillery slops, the influence of preacidification, support media type for anaerobic fixed bed and various operational conditions were tested in different laboratoryscale reactors. Results show, that random packed reactors operate with higher performance and greater stability than reactors with channeled packing. Surface roughness and porosity of the support material is important for the colonization velocity and total biomass content in stationary state, especially in the case of channeled packing materials. Acid concentration in the effluent of the acidification stage depends strong on the residence time but the influence on COD degradation and biogas yield in the biomethanation stage is only of minor importance.

1. INTRODUCTION The production of ethanol from renewable sugary and starchy raw materials gains increasing importance because the surplus in food-production can be reduced and the availability of fuels and chemical feed stocks can be improved. One of the vital points for an economic ethanol production is the good use of the distillery slops, which are generated as a by-product in an amount of 10–12 times the production volume of ethanol. The slops are highly polluted with yeasts and non-converted organic compounds of the raw mterials which results in a chemical oxygen demand (COD) of 20.000–100.000mg/l. Anaerobic digestion of the slops offers the most profitable use, because on the one hand side production of biogas can supply up to 80% of the energy demand for downstream processing of the fermentation broth and on the other hand more than 85% of COD can be removed. For a large demonstration plant which will produce daily 48.000 1 ethanol from a raw mterial mix of potatoes, sugar beets and corn-cob-mix, a concept for slops disposal was developed, according to that the slops are separated in a solid enriched phase for feed production and a nearly solid free liquid phase for biomethanation [1]. The main effort of this work was to improve the biomethanation process with respect to space time yield of biogas and COD elimination.

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For investigating the technical and economic feasibility of treating slops in a twophase process using a fixed bed reactor for biomethanation, experimental studies were performed on laboratory and pilot scale units [2]. In order to get specific data for process evaluation and design, the process behaviour in the acidification and biomethanation stage was studied as also the effect of different support materials and operational conditions. The experimental results of the laboratory tests will be discussed in the following. 2. MATERIAL AND METHODS Three fixed bed column reactors were utilized, one random packed with foamed clay (d=8–16mm), two othier units equipped with vertical laminates of porous plastic webs. A schematic drawing of the units is shown in Fig. 1.

Fig. 1: Schematic drawing of the fixed bed reactors Reactor 1 was operated in upflow mode without pre-acidif ication, because flow pattern shows almost plug flow behaviour. Reactor 2.1 and 2.2 were operated in up- and downflow mode using a separated well-mixed preacidification stage. The typical composition of the potatoe slop used is shown in Table 1. The laboratory tests were carried out at 350C.

Table 1: Composition of a typical thin potatoe slop COD Ntot NHX Ptot K total soluble [g/l] [g/l] [g/l] [g/l] [g/l] 39 36 1,0 0,17 0,43 4,0

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3. RESULTS 3.1 ACIDIFICATION The objective of the hydraulic separation of the acidogenic and methanogenic phase is the creation of optimum conditions for acidogenic and methanogenic microorganisms. The influence of residence time on acid formation was studied. Fig. 2 illustrates, that up to hydraulic residence times of about 36h the concentration of acids formed is strong dependent on residence time, whereas at higher values the acid composition is independent on residence time. Production of acetic and n-valeric acid dominates at residence times below 24h without a degradation of the influent lactic acid. At longer residence times lactic acid is degraded to butyric acid and the formation of acetic and valeric acid is diminished. The degradation of butyric acid is accompanied by a shift in pH and gas production. The degree of acidification is about 70% for residence times above 1d.

Fig. 2: Influence of residence time on the acidification of potatoe slops It is evident from biomethanation, that the change in acid composition at residence times of about 36h is of minor influence on biogas yield and COD reduction. The only consequence of the increasing butyric acid concentration is a shift in the methane content of the biogas from 60 to 69%. 3.2 COLONIZATION BEHAVIOUR OF SUPPORT MATERIALS An important aspect for start-up of anaerobic fixed bed reactors is the colonization velocity of the support mterials for methanogenic biomass. For studying the influence of the surface properties, reactors with random and channeled packing configurations were investigated. Results show, that the surface properties of packed bed materials are of

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minor influence with respect to start-up, because a relative large amount of biomass is entrapped in the interstial void spaces after seeding the reactor. In the case of film support materials the surface properties determine the colonization velocity and biomass concentration in stationary state. Fig. 3 shows the daily gas production within 100 days after seeding for four identical biogas reactors filled with different support materials. The gas production is considered to be proportional to the biomass density, so that the rate of colonization is reflected by the increase of the daily gas production. Results show, that the gas production for the non-porous support materials is nearly constant during the course of the experiment. This demonstrates, that no colonization occurs and gas production results only from suspended biomass. The most rapidly colonization could be obtained with the open cell foamed plastic. The gas production of the reactor with the glas fabric support rises in a similar rate but the total amount of fixed biomass on the rough, but non-porous surface is smaller than in the case of open cell mterials.

Fig. 3: Influence of support mterial on biomass colonization 3.3 REACTOR PERFORMANCE In order to obtain basic data for reactor design and operation behaviour reactors of Fig. 1 were investigated for more than 120 days at various COD loading rates. The results show, that the reactor behaviour is strong dependent on support material used. The random packed reactor leads to a flow behaviour similar plug flow. As a consequence, strong dependence of COD removal and biological solid distribution throughout the reactor

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height results. Up to COD loading rates of 5kg/m d more than 90% of the influent COD is removed in the lower one-third of the reactor but the contribution of the upper reactor zones on COD degradation increases with increasing loading rates. As a result the degree of COD degradation is constant 99% up to loading rates of 12kg/m3d (Fig. 4). At higher loadings the degree of COD removal gradually decreases but even at high loading rates in excess of 45kg/m3d the biomethanation process is not inhibited. In contrast to the random packed reactor the liquid phase in the reactor filled with channeled packings is almost ideally mixed and a significant part of the biomass is attached on the support media. As a consequence the COD degradation is strong dependent on COD loading rate and the process breaks down above a critical loading rate of about 10kg COD/m3d (Fig. 4). The performance of the upflow and downflow unit is comparable but the down flow unit shows a better restart behaviour after overloading. Independent on reactor type the methane yield per kg COD removed was approximately 400l/kg COD. The methane concentration varied between 60–69%, dependent on the residence time of the acidification stage. A maximum biogas production rate per unit volume of 8m3/m3d was maintained in the random packed reactor at a volumetric COD loading rate of about 16kg/m3d.

Fig. 4: COD degradation as function of loading rate CONCLUSIONS Although this study is still on-going on pilot-scale, it is evident from the results obtained, that media type, shape and surface characteristics are important factors in determining the start-up and operational efficiency. Random packed bed reactors exhibite better degradation performance and greater operational stability than reactors with film support

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materials. The acid composition of the pre-acidified slops is only of minor influence on COD degradation and biogas yield. The optimum residence time of the acidification stage is lower than 1.5 days. REFERENCES (1) BAADER, W., WULFERT, K., MICHAELSEN, Th., KLOSS, R.; WEILRND, P.: Gewinnung von Biogas und festen Wertstoffen aus Rückständen der Ethanol-Destillation und pflanzlichen Zuschlagstoffen. BML-Statusseminar “Nachwachsende Rohstoffe”, Bonn 26.–27.11.1984. (2) WULFERT, K., WEILAND, P.: Betriebsverhalten von Festbettreaktoren zur Biomethanisierung von Abläufen der Gärungsindustrie. Chem-Ing. Techn. 57 (1985), No. 5, in press.

BIOGAS FROM GREEN AND SILAGED PLANTS IN A DIGESTER WITH INTERNAL LIQUID CIRCUIT W.BAADER Institute of Technology, Fed. Res. Centre of Agriculture (FAL) D-3300 Braunschweig (FRG), Bundesallee 50 Summary Green and silaged plants are, in principle, well suited to serve as a source for biogas. Besides of vegetable residues also crops especially grown for energy purposes my have a chance for biogas production, provided there are no problems of supplying the digester with liquid and of handling the liquid effluent. A system was developed and tested for digesting continuously vegetable matter unless to mix it before with water or any kind of slurry. In the digester a constant volume of liquid was stored. Both the feed and the residual matter after conversion consist in solids. For nearly 1 year a 6m3 digester was fed only with grass-silage (average TS 50%, pH 4.5) . The liquid, separated from the effluent by a screw press, was recycled to the digester. Apart from adjusting occasionally slight deviations of liquid volume in the digester—depending on the moisture content of the silage—the liquid in the digester has not be renewed or diluted during a 290 days period. The methane yield from VS added ranged from 280l/kg (VS-loading rate BVS=1kg/m3d) and 200l/kg (BVS=3kg/m3d). Corresponding with increasing loading rates BVS from 1 to 3kg/m3d the gas production rate per volume digester increased from 0.6 to 1.2m3/m3d of 54–56% methane.

1. INTRODUCTION The conventional way of utilizing vegetable matter for biogas production is to mix it as an additive with liquid manure or similar organic slurries used as the main substrate. In this case the biogas plant is part of a liquid handling and treating system. However, if biogas is to be produced from green crops only, which are grown exclusively for this purpose, the vegetable matter is the predominant substrate and every additional liqoid my cause costs and management need with respect to provide the liquid as well as to handle and to dispose the effluent. In order to eliminate these problems, an integrated system for biome-thanation of crops only was defined and estimated to be an appropriate one consisting in the elements A Crop harvesting by conventional methods (chopped forage).

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B Ensiling nearby the biogas plant. C Once daily feeding the digester with silage or, during harvest, with green crop, whenever energy is needed. D Digestion in fluidic state. E Retaining the liquid separated from the effluent in the digester, hence no need to provide permanent fresh liquid for supplying the digester and to dispose slurry. F Stocking the dewatered undigested fibrous residue for further utilization as animal feed additive or as fertilizer. From numerous research works it was known, that green and silaged crops are well digestible (1, 2). But no informtion has been given on the process stability, if liquid is recycled for a longer period instead of being renewed. In particular it was not clear, whether the acidic substrate will drop the pH in the digester, thus the performance of the process is limited by the feed rate, and whether accumulations of TS, NHX and other components in the retained liquid will limit the process. A further problem was, how to control the flow of the substrate, rich in fibrous and floatable matter, through the digester. With regard to the real operation conditions in mterial properties and controlling the mass-flow, the research work on which is being reported in following, was conducted in a medium scale. 2. INSTALLSTION AND MATERIAL FLOW The digester (Fig. 1) adapted to handle liquid substrates with a high content of fibrous matter was a cylindrical tank (a) with conical shape of both the bottom and the cover, inlet tangential at the lower section of the cylinder, outlet at the top, totally filled, with a

Fig. 1: Configuration and flow sheet of the experimental installation a digester (6m3 vol., 1.8m diam.), b screw

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agitator (90rpm), c guide tube (0.4/0.6m diam.), d screw press, e holding tank (300l net vol.), f dewaterer (6mm mesh). loop flow of the mixture induced by a rotating screw (b) acting downward in a central tube (c). This new type of digester has been tested successfully in 6m3 and 100m3 size with animal manure (3, 4). The silage is pushed into the digester by a screw press (d), supported by liquid which is pumped from the bottom of the digester during feeding. Before feeding (once per day), liquid stocked in a high positioned holding tank (e) is fed at the inlet. This results in a overflow of solid-liquidmixture, from which the free liquid is separated subsequently by a screwtype dewaterer (f) and is given back to the holding tank (e). This cycle of liquid flow is repeated depending on the provided solids retention time. 3. MATERIAL AND METHODS The grass-silage was taken every 2–3 days from tower silos of the FALExperimental Farm. Due to the previous harvesting conditions variation in the mterial properties (Table I) had to be tolerated.

Table I: Substrate data Vegetable matter

grass-silage

Particle length mm 20–80 Content total solids (TS) % 42–77 Content volatile solids (VS) % 34–62 pH-value – 4.5–5.0 Concentr. volatile fatty acids (VFA) mg/l 8000–22000 Concentr. acetic acid (AA) mg/l 3500–5500

The mterial properties were determined according the methods mentioned in Table II. The gas flow was measured continuously by a water desplacement system combined with both an analog and a digital electrical data output. Gas flow rate, methane content, temperature in the digester and the accumu-lating weight of separated liquid were recorded continuously.

Table II: Determination of material properties Data

Methods

Material

Frequency

Total solids (TS) T=105°C silage liquid each charge daily Volatile solids (VS) T=550°C solid residue daily Volatile fatty acids (VFA) chromatography silage, liquid weekly Ammonia nitrogen (NHx) distillation silage, liquid weekly

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Methane content (cCH4)

IR

gas

633

daily

For starting the experiments the digester was filled with 5.5m3 effluent of a previous run of digesting dairy manure and grass-silage (coarse suspended solids separated, TS 4,5%) than 78kg TS of grass-silage were added in portions during 4 days. After further 6 days 0.3m3 recycled liquid and 4kg TS grass-silage were fed daily. Within 35 days a constant gas production of a methane yield of 280l/kg (VS) was reached (begin of trial no.1). In order to vary the volumetric organic loading rate, and the hydraulic retention time of solids rsp., several trial runs each of a defined quantity of moist vegetable matter corresponding with a defined volume of recycled liquid were carried out (Table III).

Table III: Operating data Feed rate Veget. matter Recycl. (moist) liquid kg/d m3/d

Trial No. 1 2 3 4 5

7.5 15.0 22.5 22.5 33.8

Concentr. veget. matter i. Hydr. ret. time Temp. digester solids 3 kg/m d °C

0.3 0.6 0.9 0.6 0.9

25.0 25.0 25.0 37.5 37.5

20 10 6.6 10 6.6

36 36 36 36 36

4. RESULTS 4.1 Process Efficiency The influence of the volumetric organic loading rate, based on VS input of silage, on gas production is shown in Fig. 2. It could be determined that with increasing loading rates up to 3.2kg(VS)/m3d the gas production rate per unit reactor volume raised to 1.2m3 (gas)/m3d. However, corresponding herewith the methane yield per unit VS added dropped from. 0.360 to 0,170m3/kg (VS). The methane content always differed between 54% and 56%. Beetween 60% and 70% of VS input have been digested, thus follows that the methane yield per unit VS digested differed between 0.240 and 0.490m3/kg (VS).

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Fig. 2: Gas production vs. organic volumetric loading rate 4.2 Process stability (Fig. 3) During continuous operation of 290 days the composition of the recycled liquid changed in – content of TS from 4.5 to 9.0% – concentration of NHX-N from 2000 to 4000mg/l – concentration of acetic acid from. 100 to 550mg/l. No accumulations of P, Na, K, Mg, Ca, zn, Fe, Mn, Cu could be found. The pH ranged all the time between 7.5 and 8.0.

Fig. 3: Composition of the recycled liquid during the total period of

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experimental operation. T1—T5 duration of trials 4.3 Mechanical effects After separating of liquid the fibrous residues consist in 20% TS (average). During the 290 days of operation only in total 860l of surplus liquid were yielded, whereas in the same time 2.800l water must be added. The totally filled loop-flow digester rendered a controlled continuous flow of the fibrous solids through the tank up to a concentration of vegetable matter in the digester of 37kg/m3 (liquid of 8% TS). 5. CONCLUSIONS Silage of green crops can be digested for a long period unless to substitute continuously the liquid. However, for dilutiin with respect to TS and NHX, exchange of limited quantities of liquid by water is necessary occasionally. Gas yields and gas production rates per volume digester were in the range known f rom laboratory experiments but comparably in shorter retention times (5). The system seems to be appropriate for biogas production from crops only. REFRENCES (1) BADGER, D.M., BOGUE, M.J. and STEWART, D.J. (1979) Biogasproduction from crops and organic wastes. New Zealand Journal of Science, Vol. 22, pp. 11–20. (2) SCHUCHAEDT, F. (1981). Untersuchungen zum Gärverhalten von tierischen Exkrementen und Pflanzen (Study of the fermentation process in animal excrements and plants). Grundlagen der Landtechnik, Vol. 31 pp. 42–47. English: Translation T 478, NIAE, Silsoe, Bedford (UK). (3) BAADER, W. (1981). Erste Erfahrungen mit einem vollständig gefüllten, vertikal durchströmten Biogasgenerator (First experiences with a com-pletely filled vertical f low anaerobic digester). Grundlagen Landtechnik, Vol. 31, pp. 50–55. English: Translation T 476, NIAE Silsoe, Bedford (UK). (4) BAADER, W. et al. (1984). Die FAL-Versuchsbiogasanlage (The FAL-Experi-mental-Biogas plant), Landbauforschung Völkenrode, Special vol. No.72. (5) MATHISEN, B. and THYSELIUS, L. (1984). Biogasproduction from fresh and ensiled plant mterial. In proceedings of World Conference Bioenergy 84, Göteborg (Sweden).

ANAEROBIC DIGESTION OF ORGANIC FRACTION OF MUNICIPAL SOLID WASTE-PRELIMINARY COMUNICATION Paolo Cescon, Franco Cecchi, Franco Avezzu and Pietro G.Traverso Dipartimento di Scienze Ambientali—Università di Venezia Calle Larga S.Marta 2137–30123 Venezia INTRODUCTION —Anaerobic digestion for energy recovery from organic fraction of municipal solid waste (OFMSW) is one of the recent biological methods developed. In previous studies an evaluation of the potential for processing organic wastes has been made (1–4). In a recent rewiew (5) a clear projection of favorable economics for the OFMSW anaerobic digestion is presented in comparison with other bioconversion technologies. The aim at different total solids content in the feed slurry. The first experiments are carried out in order to evaluate the digester performance by varying the OFMSW/Primary sludge (PS) total solids (TS) ratio. The reactor size (3mc working volume) is a means of predicting the full scale plant problems. MATERIAL AND METHODS —The pilot plant is schematically shown in Fig.1. The source separated OFMSW is shredded and analysed (TS) before mixing in a ho mogenizer with the sludge from a municipal wastewater PS. The ratios (OFMS W/PS) and the TS percentage in the feeding sludge are controlled, hence the feed is pumped into the storage tank. The digester is feed discontinuosly (three times a day). The TS content in the digester is controlled by purging the bottom sludge (when archimedian screw stirring devices is adopted). The liquid level in the reactor is controlled by a hydraulic valve so that the discharge of the effluent is a consequence of the feeding flow. A hydraulic valve in the gas pipe warrants 150–180mm w.c. pressure of the gas in the digester top. The analytical plan and the parameters which are controlled are in tabb. 1–2. EXPERIMENTALS AND RESULTS —The experimental data from a preliminary analy ses of the components of the MSW from a representative quarter in Treviso City are in Fig. 2. The averaged values are consistent with the related ones in N.W. Italy (6). The main characteristics of OFMSW,

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PS, Feed are in Tabb. 3–5. The operative conditions are in Tabb. 6; pH and temperature in the reactor are, respectively: 6.9–7.3 and 34–36°C. The SV percentage in the selected size ranges inside the reactor and in the OFMSW are in Fig.3. Figg. 4,5 show the comparison between the specific TS-VS, Inert Solids (I) values in each size fraction (TS or VS or I retained by the sieve/TS or VS or I in the sample) and the related values in OFMSW. Figg. 6 and 7 show the TS and VS (respectively) fractions of the sample not retained by the sieves. The SGP vs. OFMSW percentage in the feed is shown in Fig. 8. CONCLUSIONS —a) The OFMSW digestion process can be carried out without the addition of nutrients or baffers; b) The SGP is linearly dependent on the OFMSW percent in the feed, the SGP with 100% OFMSW is about twice the SGP with 100% PS; c) The archimedian screw stirring device is lacking when the feed OFMSW exceeds 30–35%: an inactive scum layer is produced during digestion; d) The particle size distribution and characteristics (VS, TS) of the selected size ranges inside the reactor are strictly related to the stirring devices. Nevertheless the SGP seems not to depend on the checked stirring devices in the mixed regions. REFERENCES 1) C.G.Golueke and P.H.Mc.Gadhey “Comprehensive Studies of Solid Waste Ma nagement” 2nd Annual Report SERL Report n.69.1, University of California, Berkeley (1969). 2) J.T.Pfeffer “Reclamation of Energy from Organic Refuse” EPA Report n. PB231176 (1984). 3) D.L.Klass and S.Ghosh “Fuel Gas from Organic Wastes” Chemtech. Vol.3, pp. 689–698, Nov. (1973). 4) L.F.Diaz., F.Kurz, G.Trezek “Methane Gas Production as Part of Refuse Recycling System” Compost Science, 15, (3), Summer, (1974). 5) D.L.Wise and R.G.Kispert “A Review of Bioconversion Systems for Energy Recovery from Municipal Solid Waste Par. III Economic Evaluation” Resources and Conservation, 6, 137–142 (1981). 6) C.N.R. Progetto Finalizzato Energetica I “Atti II Seminario Informativo. Utilizzazione Energetica dei Rifiuti Solidi Urbani” Padova 21 aprile (1980).

AKNOWLEDGMENTS –The authors wish to thank ENEA for financial support, Isti tuto Trevigiano di Ricerca Scientifica for the interest, and Drs. E.Vita, S.Badoer, M.Visentin for their help in experimental program. PARAMETERS ANALYSES/WEEK FEED EFFLUENT REACTOR

COD, TS, VS, TKN, NH4, NO3, PO4 TA, VFA, PH, C, H, N, Particle Size Distribution COD, TS, VS/TKN, NH4, NO3, PO4 COD, TS, VS, TKN, NH4, NO3, PO4, TA, VFA, PH

2 1 6/2 2

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C, H, N, Particle Size Distribution SLUDGE-OUTLET COD, TS, VS/TKN, NH4, NO3, PO4 GAS CO2, Gas Production/H2S PS COD, TS, VS, TKN, NH4, NO3, PO4 OFMSW COD, TS, VS, TKN, NH4, NO3, PO4, C, H, N, Particle Size Distribution

1 2/at intervals 6/at intervals 1 1 1

Tab. 1 –Analyses Plan. PARAMETERS

ANALYSES/WEEK

FEED Flow Rate, Temperature/OFMSW/PS (TS/TS) EFFLUENT Flow Rate REACTOR Temperature, Pressure

7/at intervals 7 7

Tab. 2 –Controlled Parameters PARAMETERS COD (g/l) TS (g/l) VS (g/l) PO4 (mg/l) MEAN VALUE

218

200

176

4, 5

Tab. 3 –OFMSW Characteristics PARAMETERS COD TS VS TKN NH4 NO3 TA ——g/l—— ————mg/l———— MEAN VALUE

39.0 41.3 30.2

296

114

.5 887

Tab. 4 –Primary Sludge Characteristics OFMSW% 0% 40% 60/ 90% 100% C (%TS) H (%TS) N (%TS)

39.93 43.03 44.22 45.79 46.93 5.42 6.04 6.34 6.37 6.33 2.29 – 2.32 3.25 3.00

Tab. 5 –Feed Characteristics OFMSW(TS%)

0 16 35 60 90 60 100

ORGANIC LOAD KgVS/mcs, d 1.63 1.28 1.43 1.26 1.88 1.95 HRT, 14.5 18.0 16.0 20.0 18.0 25.0 VSRT, d 33.0 32.0 21.0 25.0 18.0 25.0 REACTOR, TS (g/l) 46.5 50.5 45.2 50.0 56.5 33.0 REACTOR, VS (g/l) 26.0 27.8 24.0 31.3 34.5 21.0 Armed anchor stirring devices

Tab. 6 –Operative conditions.

1.97 27.0 27.0 31.2 20.0

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IMPROVED TECHNOLOGIES IN BIOGAS PRODUCTION FROM ALGAE OF THE VENICE LAGOON AND WASTE TREATMENT U.CROATTO University, National Research Council (CNR) and Centro Tecnochimico (C.T.)—PADOVA (Italy) Summary Macroalgae of the northern part of the Venice Lagoon have been employed as energy source for the seasonal seaside tourist resort of Jesolo (Venice). The adopted treatment process is the following: a) –separation of the algae in two fractions (liquid and solid); b) –percolation of the liquid algal fraction during 24 hr through anaerobic bacteria immobilized on solid support at hight surface concentration. With this treatment a drastic reduction of plant size and cost is achieved in comparison with the traditional digestion plant; c) –recovery of methane from biogas; d) –cogeneration of heat and electric power; e) –aerobic fermentation in a proper mixture of the solid algal fraction with sludges to produce humus.

1.– INTRODUCTION Previous studies of ours, which were reported on at the CEE conference in Berlin, on biogas production from algae of the Venice Lagoon, have established the general conditions for availability and collection of algae and biogas production by traditional digestion plants. Further studies have now been completed, on a pilot plant scale, with the following aims: a) –to develop general procedures to reduce the costs of plants by working on algal species from watersheds near resort location with summertime activity; b) –to study a way of reusing the process wastes. The zone involved is sited around Jesolo, a beach resort north of Venice, which is backed by the northern basin. The alga in question is valonia agropila which is particularly suited for grinding and pressing (see below).

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2.– PERIOD OF PRODUCTION ACTIVITY AND PLANT LOCATION The period of warm months has been chosen which is related to the fact that Jesolo population, a modest number in cold months, increases enormously during the vacation period with huge needs for energy. The period coincides also with a high concentration of macroalgae (ulva, gracilaria, chetomorpha and valonia), with fair weather and with long sunlight. Using appropriate boats there are little problems for the collection and transportation of macroalgae in the northern basin. Jesolo is also connected with the Lagoon zone through the Sile river, so that transportation by river is highly favoured. Studies on ulva and gracilaria have now been extended to valonia. At time of insufficient supply of such alga, ulva and gracilaria will also be used. The chosen plant location is south of Jesolo on the river bank near the depuration plat of urban waste waters. 3.– TREATMENT PROCESS The process involves washing, mechanical grinding and pressing of the algae with recovery and filtration of the liquid for anaerobic digestion. The liquid is percolated under mesophilic condition through anaerobic bacteria immobilized on solid supports with high surface concentration. The percolation time is 24 hr, which is much shorter than the average residence time of un-ground algae in a traditional reactor. This means a drastic reduction of plant size and a drastic cut-down of plant cost. The yeld of fermentation is 60%. 4.– RECOVERY OF METHANE FROM BIOGAS Absorption-desorption of carbon dioxide and hydrogen sulphide on ethanolamine solution at different temperatures and pressures have been adopted. The separated products can be reused for technical purposes. 5.– COGENERATION OF HEAT AND ELECTRIC POWER A “TOTEM” system based on a Fiat engine has been used. 6.– SOLID ALGAL FRACTION AND SLUDGES TREATMENT The solid algal fraction, which is essentially cellulosic, mixed in proper percentage with sludges of the plant, and also with unpolluted sludges of the depuration plant of urban waste waters have been subjected to aerobic digestion to produce synthetic humus to be used for sandy soils of Jesolo country to improve farming quality. The local farming production is generally employed in the seasonal tourist activity. Considering that the

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algal growth in the northern Lagoon is due to the runoff fertilization of the farming land, we must conclude that with this project the environmental cycle will be closed.

APPLICATION OF GAS FROM BIOMASS Conditioning of gas or adaptation of gasfired equipment? F.A.J.Rietveld VEG–GASINSTITUUT n.v., Apeldoorn, The Netherlands Summary The success of a biogas installation depends largely on the correct application of biogas. Too many of these projects have failed because of an improper use of the gas. VEG-GASINSTITUUT n.v., which is the central technical organisation of the gas distribution companies, has the task of furthering the safe and efficient use of gas in the Netherlands. During recent years the institute has been increasingly involved in applications of gas from biomass. Gas from biomass, such as from landfills, animal waste or sewage sludge varies in quality. The gas and Its combustion products are often corrosive. This imposes special demands on the gas distribution system and the equipment. A choice has to be made between two important options i.e. conditioning of gas or adaptation of gasfired equipment.

1. INTRODUCTION The gaseous fuels which are produced from biomass are an alternative to the application of natural gas. This has led to an increasing interest within the public gas supply industry in the Netherlands for this form of energy. Especially where biogas from landfills and large scale anaerobic digesters is distributed to consumers which are located outside the boundaries of these sources. The expected contribution of gas from biomass to the energy supply in the Netherlands by the year 2000 will be approximately 1000 million m3 natural gas equivalent per year. The gas is expected to come from the following sources. Biomass source Gas production in million cubic meter per year natural gas equivalent Animal waste Agricultural waste Municipal waste (landfill) Wood waste Waste water Total

410 50 180 340 40 1020

Related to the domestic gas consumption within the public gas supply, this amount contributes to approximately 5%. The production of biogas from animal waste, municipal

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waste (landfill) and waste water are in the first instance attractive to the public gas supply because these gases are related to natural gas. Thats why this paper deals with the application of these gases and in particular with gas from landfills and gas from large scale anaerobic digesters. In all cases the biogas represents a market value and has to take care of the revenue for the installation. For an optimum application of the biogas, hence for the highest revenues, we have to consider four important points of attention. These points are: – Supply and demand – Gas quality – Application – Cost price/market value In the following paragraphs these points of attention will be dealt with in more detail and also the relationship to each other. In this relationship, factors have to be considered such as: storage, flaring, the magni-tude of the appliance population, dual fuel, added value, adaptation of equipment and the selling price of heat, power and/or electricity. 2. GAS SUPPLY AND DEMAND The production of gas from biomass is a microbiological process and is consequently sluggish in operation and difficult to control. The process is therefore best served by a continuous production hence a continuous supply. This is usually not the case with the gas demand. Interruptions in demand often occur and may be long or short in duration. An example is shown in Fig. 1. Where gas from a municipal landfill is used to heat some municipal office buildings.

Figure 1. Gas demands are irregular with extensive peak periods during start-up in the morning. But also with otherwise constant gas consumptions, as is the case with tunnel kilns in the ceramic industry, gas demand is reduced to zero when, for several minutes, the kilncars

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are pushed through the kiln. When gas from biomass is used for underfiring in industry, demands are usually for the five working days and not during the weekend. A continuous demand is usually guaranteed when gas from biomass is converted into either SNG or electricity and led into the public pipeline system or power grid. 3. GAS QUALITY The gases which are produced from biomass have a certain quality. This quality may be defined as a quality with respect to the calorific value, but also with respect to impurities. The factors which influence the quality are: – Calorific value – Wobbe index – Humidity – Sulphur content – Ammonia content – Content of halogenated hydrocarbons – Dust VEG-GASINSTITUUT has specialised in analysing gases from biomass, especially for impurities such as halogenated hydrocarbons. These analyses are executed by means of temperature-programmed capillary gas chromatography with electron capture and flame ionisation detector. 5. GAS APPLICATION Gas from biomass can be used in all applications where other fuels such as natural gas, L.P.G., light and heavy fuel oils and coal are used. These applications are in general: – In boilers, for the generation of hot water or steam – In air heaters – In gas engines for power generation (traction) – In gas engines for electricity generation – In gas engines for cogeneration (electricity and heat) – In industrial processes such as in ovens, kilns and/or furnaces

6. COST PRICE AND MARKET VALUE OF THE GAS The cost price of gas from biomass is usually expressed per Mj or per m3 natural gas equivalent and is mainly fixed by the following costs: – Depreciation of the total investment costs of the installation (installation from source to application) – The cost of borrowing money – Labour costs

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– Maintenance costs – Energy costs – Material costs The market value is the price which a consumer is prepared to pay. In many cases this is the price of the replacing fuel, but sometimes this price is less because consumers may be concerned about a certain risk. This risk may have to do with the guaranteed supply or with the quality of the gas. The market value is usually higher in the small consumer sector (households) than in the large consumer sector (industry). 7. GAS STORAGE OR FLARING After investments have been made the produced gas from biomass has a certain value and flaring of the gas means a destruction of capital. It is therefore necessary to prevent this as much as possible and to examine the economic feasibility of temporary storage of the gas. In studies executed by VEG-GASINSTITUUT storage proved to be a good alternative to flaring, especially when interruptions in the demand are relatively short in duration. In some cases the pipeline between source and application can act as a buffer and variations in demand can be absorbed by the pressure build-up in the pipeline. 8. DUAL FUEL The application demands often more gas than can be supplied and requires also a standby fuel in case of supply interruption. In this case another fuel has to be available. In a large boiler installation (1, 5Mw) in the Netherlands which is fired with gas from a landfill, it was necessary to install a dual fuel system, the other fuel being natural gas. Because of the difference in calorific values of the fuels, the system was controlled by a process computer. The system constantly monitors the calorific value of the gas coming from the landfill. This and other relevant information such as gasflows, pressures and temperatures are used to compute the ideal gas and air flows to the burners. In an application of gas from landfill in a tunnel kiln in a brick plant, the base-load is supplied by this gas. Natural gas is used as a supplemental fuel. Control of this supplemental supply was by pressure. When the pressure in the supply line from the landfill dropped below a certain value, natural gas was injected. The total overall demand for gas was controlled by means of thermocouples located in the various control zones of the tunnel kiln. Also with the application of gas from biomass in diesel engines for traction, dual fuel systems are applied because the gas from biomass lacks the necessary power.

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9. MAGNITUDE OF APPLIANCE POPULATION When we have to consider if the quality of the gas has to be improved or if the gas fired appliances have to be adapted, then the number of appliances plays a role. If one appliance is involved, it can usually be adapted to use gas from biomass. Even when we would consider to recover heat from products of combustion that are corrosive, corrosion-resistant materials may be used. But if we have to consider a large appliance population, as may be the case in a village or a town, it is recommended to condition the gas and to use standard appliances. 10. ADDED VALUE The quality of a gas has an influence on its market value. By improving the quality the gas will get an added value. As stated before, the market value of the gas in the small consumers sector (households) is usually higher than in the large consumers sector (industry). Studies by VEG-GASINSTITUUT indicate that improving the quality of gas from biomass to substitute natural gas (SNG) can be financially highly attractive (fig. 2). Depending on its application the quality of the gas has to be adapted. For instance when gas from biomass is used in gas engines, the gas has to meet the requirements concerning the allowable contents of sulphur and halogenated hydrocarbons. 11. ADAPTATION OF EQUIPMENT For every application we have to consider if we can best condition the gas or adapt the gas-fired equipment in order to use this gas. This consideration is purily based on economics. In paragraph 4 the factors are listed which influence the quality of the gas. Conditioning of the gas will raise the quality to certain, predetermined standards. For the adaptation of the gasfired equipment we have to consider the influence of the gas on the materials of, for instance heaters, piping, valves, storage vessels and in the case of engines on the lubricant. Eve if the gas is non-corrosive the burners and/or the carburettors have to be modified to take the usually low calorific gas.

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Figure 2. 12. SELLING PRICE OF ENERGY Gas from biomass will always be converted to another usable form of energy such as heat, power or electricity. In order to get the highest price for these forms of energy, its conversion has to be efficient. For instance in case of hot water generation, heaters have to be used with high gas-to-water efficiencies, i.e. heaters with low thermal losses. In case of electricity generation its is recommended to find use for the cogenerated heat. The thermal efficiency of electricity generation is around 25%, while the remaining 75% is usually lost as waste heat. It is therefore necessary to pay attention to this aspect of the application. The higher the revenue of these energy streams, the more profitable a biogas installation will be.

PILOT PLANT BIOMETHANATION OF CULTIVATED MARINE ALGAE TETRASELMIS FOR ENERGY PRODUCTION IN SOUTHERN ITALY A.Legros*, M.R.Tredici**, G.Florenzano**, R.Materassi**, E.–J.Nyns and H.Naveau* *

Unit of Bioengineering, Catholic University of Louvain, 1/9, Place Croix du Sud, B–1348 Louvain-la-Neuve, Belgium ** Centro di Studi dei Microorganismi Autotrofi, Universita di Firenze, Piazzale delle Cascine, 27, Firenze, Italy Summary It has been shown previously that marine algae Tetraselmis can be transformed into methane by a one step completely-mixed biomethanation process, in a reliable way and with good yields and good methane production rates. This process can be adapted to work equally well in sea water. Based on previous laboratory results (1) (2), a pilot-scale 1 m3 digester has been installed by the authors at Lamezia-Terme (Calabria, Italy) . The digester has been fed for more than one year with Tetraselmis algae produced by 400m2 of culture ponds built and operated by the group of Professor Florenzano (Firenze, Italy) and K. Wagener (Aachen, Germany). It has been run on a moderate volumetric loading rate (0.5kg volatile solids per m3 digester and per day). The same methane yield and same methane production rate have been reached with the 1m3 pilot digester than with the laboratory scale installations. The one year work with this pilot plant has also given the possibility to integrate all the steps of this energy production system and to show its technical feasability.

1. INTRODUCTION The final goal of this research was to install at the pilot scale level an integrated plant for energy production by biomethanation of cultivated marine algae Tetraselmis in Southern Italy. It has been shown previously (1) (2), that methane production from biomethanation of marine algae Tetraselmis can be obtained with good rate and yield and good reliability in a one step continuous and completelymixed methane digester maintained at 35°C. E.g., a maximum biogas production of 1.33m3 gas×m−3ML×d−1(*) ‘can be obtained with a volumetric loading rate of 4kg VSO×m−3ML×d−1 and a mean retention time of 14d. A

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yield of 0.25m3CH4×m−3ML×d−1 can be obtained with a concentration of sodium in the mixed liquor of 10.6g×1−1ML, a mean retention time of 14d and a volumetric loading rate of 3kg VSO×m−3ML×d−1. In the same conditions of biomethanation but without sodium in the mixed liquor the same yield has been reached. (*) For abbreviations and symbols see Table I.

This report deals with the results obtained with the pilot scale installation. 2. MATERIALS AND METHODS 2.1. Description of the installation This installation has been set up at Lamezia-Terme (Calabria-Italy) at the beginning of April 1982. It has been built on a surface of nonarable land close to the sea (±800m) . A global scheme of the installation is proposed in Fig. 1. The installation has been set up on a platform of 1000m2 (20m×50m) made of concrete. On this surface six ponds of 40m2 (2m×20m) and four ponds of 80m2 (4m×20m) have been built by the team of Professors K.Wagener (University of Aachen, Germany) and G.Florenzano (University of Florence, Italy) and equipped with a mechanical mixing device. Near the ponds, a digester of 1m3 working volume, loaned by the Region Wallonne of Belgium has been set up by the authors. This digester is described in Fig. 2. Marine algae Tetraselmis are unicellular organisms. A harvesting system based on a two step sedimentation process has been set up. A preliminary sedimentation is done in a pond in which a given volume of algal suspension is introduced each day, five days a week. The supernatant is taken off or recycled into the culture ponds and the somewhat concentrated algal suspension is introduced in a sedimentation tank. This tank is the second step of the harvesting system and it is described in Fig. 3. The final concentrated algal mixture is taken out of the sedimentation tank and used to load the digester. 2.2. Operation of the installation 2.2.1. Management of the algal cultures: The cultures of Tetraselmis tetrathele in the 40 and 80m2 ponds were run on a semicontinuous regime. Every day a given volume of culture suspension was drawn and introduced in the sedimentation basin. An equal volume of new seawater, taken up directly from the sea with a submersible pump, was added to the ponds. The amount of culture suspension harvested daily was adjusted in order to keep the biomass concentration within the optimal values. Carbon, nitrogen and phosphorus were suppled daily as sodium bicarbonate, urea and potassium dihydrogen phosphate, respectively, in the amount required by the growing algal population. Assimilation of the majority of the carbon added in the form of bicarbonate was achieved by frequent adjustment of the pH to 8.6 with diluted HCl.

Pilot plant biomethanation of cultivated marine algae tetraselmis for energy production in southern italy

The yield of the ponds for 355 days amounted to 5.1kg of dry weight m−2. Hence the mixing device utilized proved to be effective. 2.2.2. Starting up of the digester: The digester was filled on day 0 with 1m3 of sludge from a stabilisation tank of piggery wastes situated in a farm at Lamezia-Terme. From day 0 to day 11 the digester mixed liquor was let to ferment at 35°C without loading until the biogas production had stopped. On day 11 the pH of the mixed liquor was 8.1 and the percentage of methane in the biogas was 94%. On day 12 the digester was loaded as described in (2.2.3). 2.2.3. Running conditions of the digester : The digester was run at a temperature of 35°C. After a three months starting and trials period and from day 85 to day 220, an hydraulic retention time of 25 days was used. The amount of concentrated algae to be added to freshwater to reach a volume of 40 liters was estimated so as to reach a volumetric loading rate of 0.5kg VSO×m−3ML×d−1. The real concentration was measured on a sample (see § 2.3.) and used for all further calculations of parameters. From day 280 to day 310, the same procedure was used with the exception of the mean

Fig. 1.: Global scheme of the installation

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1. ponds of 40m2; 2. ponds of 80 3. 1m3 digester; 4. sedimentation

Fig. 2.: Description of the digester 1. digester 2. load inlet 3. 4. and 5. heating system 6. outlet of mixed liquor 7. and 8. sampling 9. overflow 10. pump for mixing 11. storage of load 12. pumping of load 13. sediment from sedimentation tank 14. effluent storage tank 15. control of mixing

Pilot plant biomethanation of cultivated marine algae tetraselmis for energy production in southern italy

Fig. 3.: Sedimentation tank 1. sedimentation tank; 2. and 3. m2; algal suspension inlet; 4. algal tank. sedimentation outlet; 5. supernatant outlet. retention time which was 50 days. From day 310, the volumetric loading rate has been maintained between 0,4 and 0,6kg VSO×m−3ML×d−1 (average±0.5) while the volume added and hence the mean volumetric retention time could be changed to accomodate to the concentration in COD of the algal sediment as measured daily. A concentration of NaCl of 5g×l−1 was kept by using freshwater for dilution of the concentrated algae. 2.2.4. Daily operations of the digester: All the installation is run on a semi-continuous basis with loading once a day, five days a week. Daily operations can been summarised as follow: each morning the concentrated algae are taken out of the sedimentation tank. While mixing the content of the digester, the loading is introduced into the digester and effluent mixed liquor goes out through the overflow. The mixed liquor is further homogenised for 10 sec each hour.

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2.3. Analytical methods: All analytical methods used in this work have been previously described (2, 3, 4). 2.4. Analytical control of the digestion The following determinations were made each day: biogas production, percentage of methane, pH and temperature of the mixed liquor. Gravimetric analyses giving the concentration of the organic matter in the load and the effluent of the digester were made once a week from day 0 to day 310 on the total volume of the samples collected each day, 5 days a week and placed at −20°C until analysis. In addition, from day 310 to now, a daily COD analysis of the samples was made to give a better control of the volumetric loading rate of the digester (see § 2.2.2.). 3. RESULTS OF THE PILOT-SCALE BIOMETHANATION The results obtained during the first year of experiment are summarised in Fig. 4. From those results it can be seen that this digester is working since more than one year without problems and with better yields than those obtained at the laboratory scale. A mean methane yield of 0.35 m3CH4×kg−1 VSO has been obtained. This first year of pilot-scale work has also given us the possibility to integrate all the steps of this system and to show its technical feasability: culture of algae, harvesting system, semi-continuous digestion, sun-drying of the algae and characterisation of the process at all levels.

Table I: Abbreviations, symbols and units – Concentrations (kg/m3) – Indices TS: total solids o: in inlet (in feed) VS: volatile solids COD: chemical oxygen demand – Various – Rates ML: Mixed Liquor (useful volume) BV: volumetric loading rate (kg VS×m−3ML×d−1) rV gas: biogas production rate (m3gas×m−3 ML×d−1) rV.CH4: methane production rate (m3CH4×m−3 ML×d−1) – θ: mean retention time (d) – Yields Yec: methane yield (m3CH4×kg−1 VSO or m3×kg−1CODO)

Pilot plant biomethanation of cultivated marine algae tetraselmis for energy production in southern italy

Fig. 4. Results of biomethanation obtained during the first year work. REFERENCES (1) ASINARI, C.-M., LEGROS, A. , PIRON, C., SIRONVAL, C., NYNS, E.-J. and NAVEAU, H.P. (1981) Methane production by anaerobic digestion of algae. In “Energy from Biomass”, série E, vol. 1, Chartier P. and Palz W. eds, Reidel Publ. Co., Dordrecht, Netherland, 113–120. (2) LEGROS, A., TREDICI, M.R., ASINARI, C.-M., COLLARD, F., DUJARDIN, E., SIRONVAL, C., FLORENZANO, G., NYNS, E.-J. and NAVEAU, H. (1983). Methane production by anaerobic digestion of algae, I. In “Energy” from Biomass”, Series E, vol. 5, Palz W. and Pirrwitz, D., eds, Reidel Publ. Co., Dordrecht, Netherland, 210–217. (3) LEGROS, A., ASINARI DI SAN MARZANO, C.-M., NAVEAU, H. and NYNS, E.-J. (1982). Fermentation profiles in bioconversions. Biotechnology Letters, 5 (1), 7–12. (4) BALLONI, W., MATERASSI, R., DE ZARLO, S., PELOSI, E., SILI, C. (1982). Outdoor mass culture of algae in southern Italy utilizing sea water enriched with algal digested sludge. In “Energy from biomass” Series E, vol. 3. Grassi, G. and Palz, W., eds. Reidel Publ. Co., Dordrecht, Netherland, 107–113.

ACKNOWLEDGEMENTS This research has been supported by research contracts n° ESE-R-025-(B) and ESE-P021-D from the CEC and E3/CE/IV/l from the Belgian Science Policy Programming Service.

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JOINT BELGIUM-BURUNDI BIOMETHANATION DEVELOPMENT PROJECT : MAIN RESULTS AFTER TWO YEARS ACTIVITY D.Compagnion, D.Rolot, E.-J.Nyns and H.P.Naveau* V.Baratakanwa, D.Nditabiriye, J.Ndayishimiye and P.Niyimbona** *

Unit of Bioengineering, University of Louvain, 1/9, Place Croix du Sud, B-1348 Louvain-la-Neuve, Belgium ** Ministère des Travaux Publics, de l’Energie et des Mines, Travaux Publics, de l’Energ BP 745, Bujumbura, Burundi Summary The aim of the project is to make credible the development of biomethanation in tropical rural areas, especially in Burundi (Africa). It includes the setting up of a “biogas cell” and of six biogas plants for demonstration; moreover a large part of the project is devoted to training and vulgarisation. The field-laboratory of the biogas cell at Bujumbura, is equipped for the technical and scientific monitoring of methane digesters. The four first biogas plants (5–20m3) are built, partly near Bujumbura and partly inside the country. The scientific follow-up, through the experimental laboratory, has led to the continuous running (20 months) of these digesters, based each on a reliable process of biomethanation particularly adapted to each residue and each implementation site. The digesters are running in a semicontinuous or discontinuous mode, according to their design and local conditions. The biogas is used for cooking, lighting and heating, in the aim of fuelwood or liquid fuel economy; the digested effluent is used as fertilizer.

1. FRAMEWORK This project, fully identified elsewhere (1), is subsidised through the Belgian Administration for Development Cooperation (BADC). The 4 year-work has begun in January 1983. The project is placed under the supervision of the Burundi General Direction of Energy, from which scientists or technicians are regularly trained.

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2. THE BIOGAS CELL AT BUJUMBURA: A STABLE INFRASTRUCTURE The biogas cell at Bujumbura is equipped with laboratory and small scale methane digesters and a field-laboratory for the follow-up of these and full-scale digesters. The digesters installed there includes simple laboratory batch and semi-continuous digesters, working at ambient temperature (25°C), and at 35°C by means of a thermostatised room connected to solar collectors. Tests at laboratory (1–5l) and pilot (60–1 000l) scales allow to evaluate the methane digestion potentialities of the available biomass-substrates and the possible mechanical problems before scaling up on the field. The different methods regularly used at this rural laboratory are summarized in Table 1.

Table 1. Methodologies used at the field-laboratory of the biogas cell Parameters – pH – conductivity – total solids (TS) – volatile fatty acids (VFA)

Methods

Units

field pHmeter field conductimeter Drying under infra-red light distillation

mS cm−1 g TS kg−1 (or %) meq 1−1 as acetic acid – ammonium nitrogen (NNH4+) distillation g N 1−1 – total nitrogen (NTK) mineralisation and distillation g N 1−1 – alkalinity titration of the supernatant till pH 4.2 meq HCO3−1−1 – gases .O2−CO2−(CH4) field analysers (CH4 obtained by % difference) .H2S detector tubes ppm – Chemical Oxygen Demand oxydation (K2Cr2O7) g COD 1−1 (COD)

A modular semi-continuous biogas plant, adapted to rural tropical areas, is being developped (2). It combines reinforced concrete to insure the liquid tightness of the bottom part, with flexible polymeric material put on light metallic structure, to insure the gas tightness of the upper part of the digester and of the separate biogas holder. The design of this kind of digester, with the shape of a flat parallelepiped, is in the trend of the horizontal tubular processes (3, 4). A unit of one m3 has been installed in the garden of the biogas cell; it allows to confirm the results obtained at the laboratory scale with different kinds of animal manure. Moreover, a pilot biogas plant has been set up, with the financial support of the I.F.S. (International Fundation for Science), to valorise domestic refuses in a two phases process. The soluble organic matter extracted in the first step through a pereolation system feeds an anaerobic filter where the active biomass is fixed on a support formed of local bamboo-canes pieces.

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3. IMPLEMENTATION OF BIOGAS PLANTS Spectacular results have been obtained with the first biogas plant implemented within this project, at the Experimental Farm of the Faculty of Agronomy at Bujumbura. This site was completely devoid of energy source and the needs suited well to a fuel like biogas. In fact, the biogas produced by digestion of goats solid manure, is used at night to warm up chicks during their first three weeks of life. The same kind of heating tests has also been done by the National Research Centre in Cairo (5). The excess biogas is used for the family needs of the caretaker of the methane digester. The lay out of the biogas plant is depicted in Fig. 1. It comprises two units of the modular digester described above, of 7m3 working volume each, and two membrane gasholders, of 4m3 capacity each. Separate storage of the produced biogas in two gasholders, allows first, its collection at low pressure and, secondly, its independent use at a higher pressure. For this purpose, a simple removable ballast covers the gasholder ready to be emptied. From the productivities mentioned in Table 2 and the results obtained on several lots of 500 chicks each, one concludes that about 25m3 of biogas are necessary for heating one lot during three weeks.

Fig. 1: Modular biogas plant with two semi-continuous digesters and two supple gasholders

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A similar system was set up at the slaughterhouse of Bujumbura. It uses paunch manure as biomass-substrate. The simple mechanical mixing device, manually operated from outside, is not sufficient to avoid the accumulation of straws on the upper part of the liquor; so that, every three months, the digester has to be opened to remove the build-up scum layer. But this operation is quite easy with the fixed dome in supple polymeric material; indeed it takes only a few hours. The produced biogas is burned in boilers to generate hot water used in the process of pigs skining. Two other biogas plants have been implemented in rural areas, inside the country, where the fresh temperature requires heating through a greenhouse effect. The methane digesters are surrounded by a simple-made tent, serving as elementary glass-house for sun-heating the fermenting liquor. The large surface to volume ratio as well as the concept of building the digesters partly above ground and their location inside a tent, suffice to maintain the temperature in the range of 25–30°C. The sites of implementation are chosen to ensure the popularisation of the process (rural community, school, dispensary,…). A biogas plant has been so built in the Research and Diffusion Center of Kisozi, depending of the Burundi Institute of Agriculture (ISABU). It consists of two discontinuous digesters of 10m3 each connected to a metallic gasholder of 5m3. The biomass-substrates are crop residues and solid bovine manure. Finally a modular semicontinuous methane digester has been built in the school of Kiremba (Bururi); this unit of 7m3 is fed with bovine manure. These two last biogas plants are in starting conditions. The characteristis of the four biogas plants are summarized in Table 2.

Table 2. Main characteristics of the four biogas plants built within the project Biogas plants

Biomass-substrates

BUJUMBURA Exper . Farm Goats solid manure Slaughter-house Rumen fluids RURAL AREAS Kisozi Crop residues and bovine solid manure Kiremba Bovine manure * SC=semi-continuous D=discontinuous

Working TSO Θ rV gas volume (%) (d) (m3) 2×7 2×7

9 30 6 30

2×10 20 7 10

Design*

0.2–0.3 0.4

SC SC

in starting conditions

D SC

An important part of the project is devoted to training and vulgarisation. Demonstrations of the use of biogas appliances and digested slurry are regularly organized. Training courses are organized with the aid of UNESCO-ANSTI and AUPELF, and permit african scientists or technicians to receive theoretical and practical instruction and to get acquainted .with biomethanation. Moreover, members of the Burundi General Direction of Energy have the opportunity to be trained at Louvain-la-Neuve University.

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4. CONCLUSIONS The project strives to combine the building of a few demonstration biogas plants with the important aspect of training, so as to ensure a reliable implementation of biomethanation in Burundi. The biogas cell of Bujumbura, equipped of a field-laboratory and of several pilot digesters, allows to follow-up the biogas plants. The enclavement of this country, its energetic dependence and the requirements of the soils in organic matter, emphasized the advantages of this technology. Moreover, the Authorities have expressed their wish to implement, in a second phase, the process at the community or agroindustrial scales, for the rural electrification. A national biogas program is starting. In this perspective, a national infrastructure has been established to provide technical assistance and to coordinate activities of different projects (IARD, BADC, FAO, GTZ, BORDA, IFS, EGL and chinese team) that have built about 20 methane digesters so far. REFERENCES (1) COMPAGNION, D., ROLOT, D., NAVEAU, H.P., NYNS, E.-J., BARATAKANWA, V., NDITABIRIYE, D. and NIYIMBONA, P. (1983). Développement, popularisation et integration de la biométhanisation au Burundi. Tropicultura, Vol. 1, n° 3, 108–109. (2) COMPAGNION, D., ROLOT, D., NAVEAU, H.P., NYNS, E.-J., BARATAKANWA, V., NDITABIRIYE, D., NDAYISHIMIYE, J. and NIYIMBONA, P. (1984). Modular biogas plant particularly adapted to tropical rural areas. Poster presented at the Int. Conf. : State of the Art on Biogas Technology, transfer and diffusion, Cairo, Egypt. (3) CHEN, R.C. (1983). Up-to-date status of anaerobic digestion technology in China. Third Int. Symp. Anaerobic Digestion, Boston, USA, 415–418. (4) STUCKEY, D.C. (1983). Biogas in developing countries: a critical appraisal. Third Int. Symp. Anaerobic Digestion, Boston, USA, 253–270. (5) EL-HALWAGI, M.M., DAYEM, A.M. and HAMAD, M.A. (1983). Design and construction of a new type of digester attached to an egyptian poultry farm. Poster presented at the third Int. Symp. Anaerobic Digestion, Boston, USA.

INDUSTRIAL RESULTS OF SGN FIXED FILM ANAEROBIC FERMENTATION PROCESS M.ARNOUX and J.Y.MOREL Société Générale pour les Techniques Nouvelles (SGN) 78184 SAINT QUENTIN EN YVELINES CEDEX—FRANCE and G.COMINETTA and C.OGGIONNI BS—Smogless, via Mascheroni—20145 MILANO—ITALY ABSTRACT The SGN anaerobic digestion process utilizes immobilized cells on random plastic media. This allows a considerable reduction of the hydraulic residence time (down to 0.3 day). High organic loading rates can be attained (up to 20kg COD/m3 reactor. day). We present in this paper results obtained in industrial demonstration plants treating effluents from distilleries (wine, sugar cane) or piggeries (manure). Industrial full scale plants operating, or in starting up phases are also presented. Those units treat effluents from sugar plants (wash water), distilleries (spent wash) or piggeries (manures). In each case the economical aspect is summarized. The SGN process can be successfully applied to treat agricultural wastes (slurry), food industry effluents (breweries, yeast plants, starch plants, potato industry…). Petrochemical and paper industry fields are now investigated.

1. INTRODUCTION Today anaerobic digestion gives an extremely advantageous solution to reduce organic pollution, enabling high pollution abatement with concomitant recovery of energy. The anaerobic digestion has been successfully applied for several decades to biological sludges stabilization, and to the treatment of animal manure. These substrates having a high concentration in solids, one or two stages of completely mixed digesters may be efficiently used but this requires a long residence time (over ten days) which imposes expensive installations. In order to reduce the size of these units, and consequently the investment, a high biomass concentration has to be kept in the digester. Certain improvements have permitted the biomass concentration to be increased by recycling sludges to the digester. Nevertheless, these improvements are not sufficient to reduce to a great extent the residence time, and consequently, the size of the bioreactors.

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One of the most important progress in anaerobic digestion is based on fixing biomass. 2. SGN FIXED FILM TECHNOLOGY 2.1. Process Development SGN having over ten years experience in the use of biological fixed films in aerobic biofilters decided to take an active interest in applying this technology to anaerobic digestion. SGN patented technology applies a plastic media which has been widely used in trickling filters. This material is characterized by high specific surface (230m2/m3) and high void volume (95% min). This allows to fixe a large amount of biomass and minimize the risk of clogging. In 1979, a pilot experimentation was carried out in cooperation with the French National Institute of Agronomic Research (INRA). Led to build in 1982 an industrial scale demonstration unit, to confirm laboratory results and to define optimal operating conditions, reliability of the process, investment and operating costs. After this first industrial plant, others demonstration units processing effluents from different fields (spent wash from distilleries, pig manures), have been successfully operated. Now, several full scale plants have been built and commissioned or in construction stage. Operating data concerning these plants are presented hereafter. 2.2. SGN fixed film process general description General description of SGN process is presented in figure I.

fig. 1: SGN FIXED FILM PROCESS

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Raw effluent to be treated is fed through a cooling/heating system (30) to adjust, if required, its temperature. In some cases, a buffer tank (10) is needed to control the inlet flowrate. Raw effluent is then mixed with the recirculating flow, and fed to the digester (40). Temperature is controlled in the range of 35–37°C. The inlet distribution system (40.2) ensures an uniform distribution through the whole section. The recirculation pump (40.1) allows an adequate hydraulic velocity in the plastic media. Treated effluent leaves the digester through an overflow pot (40.5) and an hydraulic seal (40.6). In most cases, the net biogas is locally used in a boiler or for cogeneration of electricity and heat. Biomass quantity in the digester is controlled by recycle facilities (40.7). Vacuum breaker (40.3) and flare (or vent) (40.4) are installed to prevent abnormal conditions. In some cases, preliminary neutralization of the effluent is needed and facilities are provided (20) to control pH, especially during start-up phases. In most cases, the buffering effect of the recycle makes this pH-control unnecessary during normal operation. 3. DESIGN AND OPERATING DATA ON INDUSTRIAL PLANTS 3.1. Industrial Demonstration Plants Wine distilleries (Société Interprofessionnelle de l’Armagnac—CONDOM FRANCE) Commissioned in January 1982, SGN first industrial scale demonstration unit (reactor active volume: 16m3) has been in operation during two distillation campaigns. Restarting after the inter-campaign interruption has been successful. The use for an original Programmable Logic Controller allowed complete control of the unit and data recording. In order to check the secondary treatment efficiency, a gas treatment for H2S removal and an aerobic trickling filter were also installed. The plant has been continuously fed with wine vinasses (mean COD 25g/l) alone or in admixture with lee vinasses (mean COD 50g/l). Average results obtained are presented hereafter : Loading rate: 13 to 18kg COD/m3 reactor. day Pollution abatement: BOD over 90%; COD 85 to 92% (soluble) Biogas productivity: 8Nm3/m3 reactor. day with 60 to 70% CH4 H2S content after treatment is negligible. The secondary aerobic treatment allowed a dépollution over 98%. Sugar cane molasses distilleries (Société Industrielle de Sucrerie—GUADELOUPE—FRANCE)

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A second demonstration unit was built in the french West Indies (LA GUADELOUPE) and was operating from May 1983 to January 1984. The equipment of this demonstration unit were similar to those used in CONDOM: – reactor (active volume 10m3) – gas holder 5m3 with electrial biogas power generation unit. The plant was continuously fed with spent wash from sugar cane molasses distillery having a COD concentration between 45 and 65g/l. Very interesting results were obtained: Loading rate: over 20kg COD/m3 reactor. day Pollution abatement: BOD 85 to 90%; COD 65 to 75% Biogas productivity: 8Nm3/m3 reactor. day with 55 to 65% CH4 3.2. Full scale plants Sugar Refineries (BEGHIN-SAY COMPANY—THUMERIES—FRANCE) Figure II presents a block flow diagram of the waste water treatment unit. The existing waste water treatment includes a 30 000m3 lagoon with an aeration basin equiped with six 15kwh aerators. The BEGHIN-SAY company (one of the leading european sugar groups) decided to replace their conventional aeration plant and to install a SGN fixed film process. The total COD to be treated was 16 tons/day (wash water from 5 000 to 8 000 tons/day of beets). The plant, commissioned in October 1983, includes: – Heat exchanger – 1 100m3 packed bed reactor – flare – biogas boiler It was designed for a minimum 90% COD reduction with a “loading rate of 14,5kg DCO/m3 reactor. day. Key design data were 100m3/h of raw effluent containing 7 000mg/1 COD, for an operation campaign of three to five months each year. The energetical context is the following: – no autoconsumption (heating by waste hot water) – methane production of 5 000Nm3/day (used for production of steam) – saving in electrical consumption (by elimination of the aeration facilities) The total investment (6 MFF—1983) is provided to be paid out in 7 years on the bases of energy conservation alone and taking into account a short campaign period of 90 days/year. Please notice the plant capacity to treat high flowrates: 125% of the design flowrate in 1984 (because of the low load of the influent) with a COD reduction over the provided one.

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fig. 2

fig. 3 wine distilleries (REVICO—MARTELL GROUP—COGNAC—FRANCE) (TOMELLOSO—SPAIN): REVICO used initially a multistage evaporation process to treat effluents coming from over hundred distilleries. Convinced by the results of the demonstration unit of CONDOM, and considering the increasing energy costs, the REVICO—MARTELL GROUP decided to replace the existing evaporation unit by SGN anaerobic process (figure III). The plant, commissioned in late November, shall treat wine and lee vinasses having COD of 80 tons/day in two reactors:

– 4 300m3 packed bed reactor (soluble COD), presented on picture n° VI – 4 000m3 intimate mixed bed reactor (settled effluent)

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The total COD abatement expected is 99% taking into account finishing lagoon. Please note that this plant uses a PLC controller for on line monitoring of the operation. Due to the particularly interesting context, the raw pay out time for the total investment (18,5MFF—1984 2M US$) is 2.6 years with a methane production of 1 700 000Nm3 (1 450 TOE) and a saving of 2 850 TOE/year due to shut-down of the evaporation plant and this despite a short operating period of 180 days/year. The TOMELLOSO plant, (two 1400m3 each packed bed reactors) under construction in SPAIN under SGN licence by PROSER S.A. will treat 1 400m2/day of distillery vinasses and several by-products of the wine industry for a total COD of 45 tons/day. Sugar cane distilleries (Société Industrielle de Sucrerie (LA GUADELOUPE—FRANCE) As an application of the demonstration unit performances observed in GUADELOUPE, SGN proposed a project for a full scale plant. The unit will have a 1 500m3 packed bed reactor and will produce 5 400Nm3/day of methane (4,5 TOE/day) with a treatment capacity of 24 COD tons/day. The plant is scheduled to start operation early 1986. 4. CONCLUSIONS Although the SGN anaerobic digestion being an advanced technology, it has already acquired a strong industrial experience in several fields. Operating facilities and easy monitoring of the SGN process are major advantages for industrial size units. More over, treatment performances are among the best recorded in international l itterature. Many advantages characterize the SGN technology from a technical and economical point of view: – high loading rate and short residence time – 90% or more pollution abatement – flexibility – ease of operation, – complete manitoring by a PLC controller, – reliability, – short return investment cost and positive operating cost balance.

THE BIO-GAS PROJECT IN EMILIAROMAGNA (Italy); FIRST RESULTS OF FIVE FULL SCALE PLANTS CORTELLINI L., PICCININI S.* TILCHE A.** *

Centro Ricerche Produzioni Animali—Via Crispi, 3–42100 Reggio Emi lia (Italy) ** ENEA—Dip. FARE—TER COM IBI—Via Mazzini, 2–40138 BOLOGNA

SUMMARY The operation and performance of five full scale plants installed in breeding farms are analyzed in this paper. The digesters were operated at an HRT from 10 to 40 days with pig, pig and cattle and cattle waste. The digesters, fed by pig waste, gave an average biogas yield of between 0.30 and 0.55m3. Kg−1 VSo.d−1, 0.80 and 1.20 m .Kg−1 VSr.d−1 at an HRT of 10–15 days, at an average organic loading rate of 0.84–1.95 Kg VS.m−3.d−1, and at a digestion temperature of 28–40°C; TS, VS, COD removal was respectively 30–47%, 46–57%, 42–59%. One of the plants fed by mixed waste and operated at an organic loading rate of 0.60– 1.78Kg VS.m−3.d−1 gave an average biogas yield of 0.46m−3.Kg−1 VSo.d−1, at an HRT of 20–35 days and at a digestion temperature of 30– 34°C; TS, VS, COD removal was respectively 35%, 46%, 50%. The experimental plug flow plant opera-ting on cattle waste gave a biogas yield of 0.24–0.41m .Kg−1 VSo.d−1 at an HRT of 24–40 days, at an organic loading rate of 2.7–4.5Kg VS.m−3.d−1 and at a digestion temperature of 33–37°C.

1. INTRODUCTION One fourth of the entire national pig population is concentrated in Emilia-Romagna, a Region that represents one twentieth of the Italian land surface. The average farm size is 600 heads; 48% of pig population is on farms larger than 1,000 heads. Therefore, on the one hand many farms have large energy needs, while on the other they have the availabi lity of high energy potential in the waste water. Anaerobic digestion is the technology that recovers energy from such wastes. The Emilia-Romagna Authorities have financed the realization of 4 demonstration full-scale plants in order to monitor: 1) the efficiency of the anaerobic digestion process; 2) the technical reliability of the plants sold by industry; 3) their economic convenience; 4) the farmer’s capacity to manage a digester. The plants have been installed in farms which differ in size, type of animals bred and management; they are of C.S.T.R. type with different mixing and heating systems. They

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have been in operation since early 1983. An experimental plug-flow plant on a dairy farm has been brought out and used within the programme. The results given below concern: 1) the efficiency of the digestion process; 2) energy contribution of the plant towards the energy needs of the farm; 3) the electric and thermic consumption of the plant; 4) problems relating to the introduction of the plant on a farm, and solutions relating to this.

2. MATERIALS AND METHODS The main characteristics of the farms are reported in table I and the main characteristics of the plants are reported in table II.

TABLE I –Main characteristics of the farms Farm

type of breeding

1 TESTA

live weight (tons)

Full cycle pigs

raw waste (m3 .d−1)

100

2 S. MATTEO Dairy with fattening pigs 3 PERUGINA Fattening pigs and beef cattle 4 dairy cattle PELLERANO 5 I.C.S.A. piglet production

180 300 (pigs) 390 (beff cattle) 72 410

waste disposal

30–40 pollution treatment 22–25 land spreading 60–85 land spreading 2.5–4 land spreading 140–160 pollution treatment

TABLE II –Main characteristics of the plants Farm

type of plant

1

single stage with slurry recycling

2

single stage with out slurry recirculation

3

single stage with recirculation of slurry from the post digester plug-flow

4

digester mixing heating system gas storage biogas use working system volume volume (m3) (m3) 220 auger and external heating pump exchangers 350 external external heating gas lifter exchanger in the gas lifter 1260 internal periferic gas lifter exchangers 65

internal coils

50 combined heat and power units 200 steam pro duction in the dairy boiler 450+600 forage drying

40 hot water production

The bio-gas projects in emilia-romagna (italy): first results of five full scale plants

5 single stage with out slurry 1500 internal gas internal exchanger in recirculation lifter the gas lifter

671

200 combined heat and power unit

The content of Total Solids (TS), Volatile Solids (VS), Total Kjeldahl Nitrogen (TKN), Ammonia Chemical Oxygen Demand (COD), Volatile Acids (VFA), pH and Total Alcalinity (TA) in feed, in digestion and in effluent were measured. Analyses for TS, VS, COD, TKN, were carried out in accordance to Standard Methods (APHA, 1975); VA were determined by steam distillation and titration, TA by titration at pH 3.8. The biogas methane and CO2 content were measured by IR and CO2 absorption. Furthermore the plants are equipped with a computerized sy stem for the continuous recording of data relating to the temperatures of waste, gas and water in different points, the biogas production and consumption, the production and consumption of electric power and hot wa ter, and the CO2 and CH4 percentage in biogas. The data obtained will enable us to determine the energy flow of the plants and to evaluate the efficiency of the different heating and mixing systems. 3. RESULTS AND DISCUSSION The biogas yield and organic loading rate of the plants are reported in table III.

TABLE III –Biogas yields, organic loading rate, HRT, digestion temperature of the plants Plant

1 2 3 4 5

Biogas yield Organic loading rate HRT (days) Temperature (°C) (m3.Kg−1VSO.d−1) (m3.m−3d−1) (Kg VS.m−3.d−1) average range 0.30 0.28–0.33 0.55 0.45–0.60 0.46 0.39–0.53 0.37 0.24–0.41 0.45 0.33–0.50

average average 0.60 1.95 0.62 1.13 0.40 0.79 1.22 3.60 0.36 0.84

range 1.70–2.55 0.66–1 .69 0.60–1.78 2.70–4.50 0.55–1.12

11–15 14–16 20–35 24–40 10–15

30–40 32–34 30–34 33–37 28–35

Biogas yield as reported in the operating conditions given above, shows a rather high level. The lower yield observed in farm 1 is due to the lay-out of the plant. Infact the wastes are loaded into the digester after settling and in this plant the settling tank serves also as a clarifer with the mixing of feed and effluent. The highest yield has been observed in farm 2 with fattening pigs fed on whey and housed on slotted floors. During the first year of operation, plants 2, 3 and 5 were fed with a specific organic loading rate lower than the expected one: therefore the volume of biogas produced is lower than that predicted in relation to the number of animals present. The low organic load fed into the plant is mainly due to stagnation of solids in the pit and in the collection system, to the dilution of manure with cleaning and ground water. In order to rectify these drawbacks different solutions have been studied together with the farmers. The influence of the variations in temperature in the mesophilic range is in evidence in plants 3 and 4 that treat

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cattle waste. In plant 4 it has been observed that a process temperature lower than 35°C determines a much lower speci fic biogas yield. In plants 1, 2 and 5 fed with pig waste no influence of temperature on biogas yield has been observed when kept in the mesophilic range. The average VS, TS and COD removal of the plants is reported in table IV. The low organic removal of VS, TS and COD as shown on plant 3 is due in part to the operation of the post-digester: the sludge from the bottom has not been removed consistently and systematically. In two of the five farms, anaerobic digestion constitutes the first stage in the pollution treatment. The system is composed by digester followed by aerated lagoons (farm 1) or by solid/liquid separation of the effluent and ammonia stripping (farm 5).

TABLE IV—VS, TS and COD removal of the plants Plant VS removal (%) TS removal (%) COD removal (%) 1 46(a)–61(b) 30(a)–55(b) 2 57 47 3 46(C) 35(C) 4 40 32 5 49 44 Note: a—digester only b—digester plus settling tank c—primary digester plus post digester

42(a)–61(b) 59 50(c) -56

On Testa farm biogas in used in two Fiat Totem combined heat and power units. The performance of the Totem is reported in table V.

TABLE V—The performances of Totem units Electic power (Kw) 11.27 Thermal power (Kcal.h−1) 30095 Biogas consumption (Nm3.−1) 8.94 CH4 biogas content (%) 62

In the period November 82—October 83 the average Totem electric energy production was 154Kwh.d−1 representing 81% of the total electric energy requirement (plant and breeding). Heat was used for heating digester. On S.Matteo farm net biogas production is used for the dairy’s steam generator. In the period October 83—ne 84 the average biogas production is 210m3.d−1 with 58% used to satisfy the digester heat requirement and 36% used for the dairy’s steam generator. On Perugina farm net biogas production is used for drying forage and cereals. The drying machine came into operation in June 84, and has been used up till now in the months of June, July, September and October 84. In the period January-November 84 the average biogas production is 506m3.d−1 and the average biogas used for the digester heat requirements is 277m3.d−1. The plant’s average electric consumption for plants 1,2 and 3 is respectively: 206wh.m−3 digester.d−1, 341wh.m−3 digester. d−1, 148 wh.m digester.d−1.

The bio-gas projects in emilia-romagna (italy): first results of five full scale plants

673

4. PLUG-FLOW EXPERIMENTAL PLANT Interesting data were obtained about the heat exchange capacities of the two coils immersed in the still manure, that range from 23 to 46 W.m−2.°C−1 for this experiment. The iron coil showed a lower heat exchan ge capacity in respect to the polyethylene one. This means that in such conditions the exchange material is relatively less important, because the resistance of the manure to heating is very high. The relatively lower coefficient found for the iron pipe can be explained by the fact that the iron coil is in the first part of the reactor where the density of the manure is higher and the bubbling of biogas is lower. The overall efficiency of the heating system is between 80 and 85%. The biogas con sumption used in maintaining a constant temperature ranges from 25 to 65% of the biogas produced, depending on the loading rate and the temperature of the environment. As far as the needs in electric energy are concerned, they are very low, only about 21kWh/d; 50% are used for the chopping and for the discharge pumps. The concentration of total solids, volatile solids and volatile acids decreases regularly from the beginning to the end of the reactor, showing good plug-flow behaviour of the plant, probably due to the presence of three internal baffles that force the digesting waste to pass over or under them. 5. CONCLUSIONS The monitoring scheme carried out on 5 full-scale plants, 4 demonstrative ones and an experimental one, shows high biogas yield (m3.Kg−1 VSO .d−1). The anaerobic digestion process is shown to be stable, even when there are falls in digestion temperature, or breaks in the mixing and feeding process. Considerable problems were noted, however, in the manure collection system: stagnation leading to partial digestion of the organic substance, and dilution of the waste by ground or cleaning water. Several methods have been studied to rectfy this and in part put into practice in order to improve working conditions. Improvement techniques are also needed in order to make full use of the energy. REFERENCES – APHA—American Public Health Association (1975): “Standard Methods for examination of water and waste water”, 14th edition, APHA, N.Y. – Bonazzi G., Cortellini L., Piccinini S., Tilche A., (1984): “The Biogas Project in Emilia-Romagna (Italy)”, paper presented to the BioEnergy 84 Conference, June 18–21, Gotebörg, Sweden. – Chiumenti R., De Poli F., Gabbi P., Mozzi A. and Tilche A. (1983): “A data acquisition system for the monitoring of anaerobic digesters: design and application”, in Proceedings of the Anaerobic Waste Water Treatment Symposium, Noordwijkerout, 23–25 November, 559–572. – Tilche A., De Poli F., Ercoli L., Tesini O., Cortellini L., Piccinini S.: “An improved plug-flow design for the anaerobic digestion of dairy cattle waste” paper presented to the International Conference” State of the art on biogas technology transfer and diffusion”, Cairo, November 17– 24, 1984.

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– Regione Emilia-Romagna, Dipartimento Attività Produttive Agricoltura e Alimentazione (1983): “Programma di ricerca per la produzione e utiliz zazione di energie integrative in zootecnia”. – Regione Emilia-Romagna Dipartimento Attività Produttive Agricoltura e Alimentazione (1983): “Risultati di due anni di controllo su cinque im pianti di Biogas in Romagna”. – Tilche A., De Poli F., Ercoli L., Tesini O., Cortellini L., Piccinini S. (1984): “Un impianto semplificato di biogas tipo “plug-flow” per li quami bovini”, Regione Emilia-Romagna— ENEA, Bologna, 23 pp.

METHANE PRODUCTION FROM GREEN AND ENSILED CROPS TECHNOLOGICAL AND MICROBIAL PARAMETERS E.ZAUNER and U.KÜNTZEL Institute of Grassland and Forage Research, Federal Research Centre of Agriculture (FAL), Braunschweig, Germany Summary Methane fermentations of green and ensiled crops were performed at laboratory scale analyzing effects of substrate compounds, bacterial inoculants and varied fermentation conditions on digestion process. Use of enriched bacterial populations precultured and already adapted to plant material was proved to be advantageous for inoculation. Crops consisting of C:N ratios about 16–12:1 were preferable for anaerobic digestion. Methane yields obtained from continuous fermentations of plant biomass generally decreased at increasing loading rates and reduced retention times, whereas quantity of anaerobic bacteria was not influenced by changed process conditions. In most cases critical ranges of loading rate were detected about 5 kg total solids/m3 ·day and at retention times below 10 days.

1. INTRODUCTION In view of increased interest in renewable sources for energy supply investigations on anaerobic digestion of plant biomass were carried out to increase basic knowledge necessary for development of suitable conversion technologies. At present little informations about methane production from plant material are available to derive preferable substrates and fermentation conditions (1–5). This paper presents the results of batch and continuous fermentations of green and ensiled crops to check out influences of bacterial inoculants, substrate composition, loading rate and retention time on digestion process. 2. RESULTS The conversion ability of enriched bacteria precultured on different substrates was examined in comparison with rumen fluid and cattle manure bacteria. Batch

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fermentations of ensiled grass showed highest turnover rates and methane yields when bacteria grown on grass silage were used for inoculation (Figure 1). A great quantity of crops materials differing in N and N-free extract (NFE) compounds were digested in batch-tests to select suitable substrates. Increasing nitrogen content generally raised methane yield reinforced in combination with increasing NFEcontents. Progressive load reduced these effects (Figure 2). Continuous fermentations of green and ensiled plant biomass (Table 1) were performend at 37°C by use of 16l laboratory flow digesters (Figure 3). Substrates were fed once a day simultaneously with recycling of effluent.

Figure 1

Figure 2

Methane production from green and ensiled crops technological and microbial parameters

Silage

677

NUTRENT COMPOSITION OF ENSILED PLANT MATERIALS % % of tota 1 solids (TS) TS Crude Cellulose1 Lignin2 Organic Total Total C: pH ash acids3 C N N

Zea mays, milk stage 20.0 7.3 28.9 Zea mays, dough 37.2 7.6 33.5 stage Mixed grass 43.0 11.9 29.8 Lolium west. 15.1 15.0 31.1 Sugarbeet leaves 13.6 24.7 16.0 Vicia sativa 14.9 16.4 25.1 1 ADF—ADL determined according to van Soest 2 ADL determined according to van Soest 3 VFA (C1−C6)+lactic acid

3.2 3.7

8.7 11.6

41.3 49.1

1.3 32:1 3.8 1.6 31:1 3.9

3.6 3.9 3.4 6.9

5.6 23.3 19.0 14.6

37.8 40.3 35.0 36.0

2.4 3.6 3.0 4.7

16:1 4.8 11:1 4.4 12:1 3.9 8:1 4.6

Table 1

Figure 3 Composition of bacterial population in digester fluids was investigated by selective enumeration of anaerobic bacteria using roll tube technique (6). Colony counts of acido-, aceto- and methanogenic bacteria, obtained in agar media containing different carbon sources, remained nearly constant despite of varied loading rates, retention times and plant materials (Table 2).

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SELECTIVE COLONY COUNTS OF ANAEROBIC BACTERIA OBTAINED IN MEDIA CONTAINING DIFFERENT SUBSTRATES Carbon source of nutrient media Colony counts/g digester fluid’ “acidogenic” bacteria

glucose lactate “acitogenic” bacteria propionate butyrate acetate “methanogenic” bacteria formate

109−1010 109−1010 106−107 106−107 108−109 107−108

Table 2 range of 57 samples during fermentation of all ensiled plant materials Disturbance of methane formation was not caused by reduction of cell numbers but by inhibition of metabolic activity. Methane yields obtained of all substrates used in experiments generally decreased at increasing loading rates and retention times indicated by raising concentrations of propionic acid in effluents (Figure 4).

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Figure 4 Limiting loads and retention times that provided still high methane yields and productivities are given in Table 3.

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METHAKE YIELDS AND PRODUCTIVITIES AT LIMITING VALUES OF LOADING RATE AND RETENTION TIME Silage Loading rate (kg Retention Methane yield Productivity TS/m3-d) time (d) (l/kg TS) (m‘CH4/m3.d) Zea mays. milk stage Zea mays. dough stage Mixed grass Sugarbeet leaves Vicia sativa

4.0

10

184

0.7

4.0

10

181

0.7

5.4 5.0 2.8

15 12 12

199 135 247

1.0 0.7 0.7

Table 3 Highest loading rates could be achieved when plant materials of C:N ratio about 16–12:1 were digested. Data reported from continuous fermentations have to be regarded as preliminary values that have to be proved by long run and scale up experiments to check possible activating or inhibitory effects which might influence fermentation process. REFERENCES (1) KÜNTZEL, U. (1984). Biogaserzeugung aus Grüngut. 1. Mitteilung: Einfluß der Grüngutbeladung und des Trockenmassegehaltes auf die Methanbildung im Batch-Verfahren. Landbauforschung Völkenrode 34 155–162. (2) BADGER, D.M. (1979). Biogas production from crops and organic wastes. 1. Results of batch digestion. New Zealand Journal of Science 22, 11–20. (3) SCHUCHARDT, F. (1981). Untersuchungen zum Gärverhalten von tierischen Exkrementen und Pflanzen. Grundlagen der Landtechnik 31 No.2, 42–47. (4) BAADER, W. (1982). Zur Technologie der Erzeugung von Methan über anaeroben Abbau von Pflanzenstoffen. In: Fischbeck, G. et al. (Eds.): Nichtnahrungspflanzen, 116–132, agrarspectrum 4, BLV-Verlagsgesellschaft, München. (5) STEINER, A. and KANDLER, O. (1984). Anaerobic digestion and methane production of grass and cabbage wastes. Third European Congress on Biotechnology, Vol. III, Verlag Chemie, 3–8. (6) HUNGATE, R.E. (1969). A roll tube method for cultivation of strict anaerobes. In: Methods in Microbiology, Vol. 3B, Norris, J.R. and Ribbons, D.W. (Eds.), Academic Press, New York, 117–132.

FEASABILITY AND EFFICIENCY OF THERMOPHILIC METHANE FERMENTATION WITH PIG MANURE AND POTATO STILLAGE AS SUBSTRATES U.Temper, J.Winter, F.Wildenauer, O.Kandler, Botanical Institute, University of Munich, Menzingerstr. 67, D-8000 München 19 Summary: In experiments using completely mixed bench scale fermenters, methane fermentation of pig manure was possible at 35°C but not at 56°C. When at 56°C sewage sludge was replaced by pig manure as a substrate for fermentation (loading rates of 1.2g and 2.4g vs/l·d), gas production decreased and virtually ceased after 20 days. The concentration of volatile fatty acids increased to about 100 mmol/l. Due to high concentrations of ammonia in pig manure, the pH value in the fermenters remained above 7. In contrast, stable fermentation of potato stillage could be obtained at 56°C, however there was no advantage in the decomposition of organic matter and in gas production compared with mesophilic fermentation. Furthermore, high concentrations of volatile fatty acids (55mmol/l) even at a low loading rate (1.5g vs/l·d) did not allow high organic loading under thermophilic conditions.

Introduction At present the anaerobic treatment of pig manure in agricultural biogas plants is common in Europe. According to a study ordered by the commission of the E.C. the main reason for farmers to instal a biogas plant on their farm is to produce energy, i.e. to cover a large part of their energy requirements with the gas produced (1). However, the main reason for the anaerobic treatment of stillage is rather the efficient reduction of the organic load. Usually, both substrates are fermented at mesophilic temperatures. The studies reported in this paper were performed to show whether thermophilic (56°C) digestion would be an improvement in the decomposition of organic matter and in gas production.

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Substrate Homogenized portions of pig manure and potato stillage (substrate composition Table I) were dispensed into plastic bottles and stored at −20°C until use. Experimental design Fermentation experiments were carried out semicontinuously using completely mixed bench scale fermenters (working volume 4.5l). Pig manure and potato stillage were added to fermenters operated with sewage sludge as substrate, maintaining the retention time and temperature. When all the sewage sludge was replaced by the new substrates and steady state conditions were reached, samples were taken and analysed using standard methods. Gas production and pH-value were continuosly measured. The methanogenic bacteria in the fermented slurry were examined under a fluorescence microscope.

Table I. Substrate composition pig manure potato stillage Total solids (g/l) volatile solids (g/l) COD (g 02/1) Total N (g N/l) (g N/l) protein (g/l) grease (g/l) volatile organic acids (mmol/l) lactic acid (mmol/l) pH

73 53 75 7.3 3.9

43 34 52 2.1 0.1

21 5.1 162 1 7.5

12.5 n.d. 24 99 4.8

Results 1. Pig manure as substrate Stable methane fermentation of pig manure could be attained at 35°C but not at 56°C. When at 56°C sewage sludge was replaced by pig manure, gas production decreased at both loading rates (1.2g and 2.4g vs/l·d) and ceased after about 20 days. After stopping the daily feed there was no recovery in the following two months (Fig.1). The addition of pig manure to the fermenters raised the concentration of volatile acids constantly. Within a period of two weeks a concentration of about 100 mmol/l volatile acids was reached (50% acetic acid). Since high concentrations of ammonia are present in pig manure, the pH remained above 7. Due to the accumulation of ammonia during the two weeks period, the ammonia -nitrogen level was 2.9g N/l, equivalent to a concentration of free ammonia of 465mg N/l at pH 7.6 and 56°C. In such fermentations, rod-shaped methanogenic bacteria, forming methane from CO2 and H2, could not anymore be detected and

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Methanosarcina, the acetate-degrading methanogen, lost its fluorescence. Consi-derable background fluorescence was visible probably caused by a release of the factor F 420 from lysed methanogenic bacteria into the media. At 35°C stable fermentations with pig manure could be attained at retention times of 22.5 and 10 days (loading rates of 2.4g and 5.3g vs/l.d) (Fig. 1). Gas production and reduction of organic material (tables II, III) were within the range of earlier results (2). The kinetics of the gas production within a feeding interval (24 hours) were similar at both retention times (Fig. 2). After the addition of fresh substrate only a small increase in the gas production rate could be observed. Almost constant gas production rates in the following hours indicated substrate saturation of the enzyme systems responsible for gas production. The dominant methanogenic bacteria in the mesophilically fermented slurry belonged probably to the genus were coccoid. The small coccoid forms belonged Methanobrevibacter (Mbr. smithii?), whereas the larger ones either to the Methanococcaceae or to the genus Methanogenium. Other types of methanogenic bacteria like Methanobacterium, Methanospirillum and Methanosarcina were also detected in the fermented manure but in relatively low concentrations. 2. Potato stillage as substrate Stable methane fermentations of potato stillage could be

Fig. 1. Gas production in pig manure fermentation at 35°C and 56°C.

Fermentation retention volatile COD grease protein free vol. pH solids NH3 acids substrate time (d.) 9/1 %degr. gO2/l %degr. g/l %degr. g/l %degr. mg N/ mg mmol/l N/l pig manure

10 37,5 22.5 32 5 m.* 26

29 40 51

51 42 38

32 3.0 43,5 2.9 50 2.3

41 21 43 20.5 55 16

0 3.900 227 2.5 4.100 295 23 4.700 571

49.5 7.65 18.5 7.8 1.5 8.0

Energy from biomass

pot. stillage 22.5 16 *m: months—batch experiment

54 29.5

57 n.d.

684

n.d.

9

30

810 130

55 7.35

Table II. Fermentation data with fermented pig manure at 35°C and potato stillage at 56°C. obtained at 56°C (Table II). Volatile solids reduction (54%) and gas production (0.75l gas/1.d) were of about the same magnitude as in earlier experiments using sewage sludge as substrate (3). Due to the low concentration of -nitrogen in the digested stillage the concentration of free ammonia was very low (about 130mg N/l), inspite of a high fermentation temperature and a high pH of 7.4. The fresh stillage already contained a very high concentration of lactate (about 26% of vs) which was fully decomposed at a retention time of 22.5 days. The decomposition of lactic acid was accompanied by an increase in volatile organic acids. Remarkably high concentrations of propionic acid (44mmol/l) were detected, i.e. 80% of the total volatile acids (Table IV). The decompostion of propionic acid (mainly formed from lactic acid contained in fresh stillage) to acetic acid, H2 and CO2 is thermodynamically very unfavourable and seems to be the rate-limiting step in thermophi1ic stillage fermentation. Methanosarcina and long rods (M. thermoautotrophicum) Fermentation substrate retention time (d.) 1 gas/1·day ml gas/1 g v.s. methane % added degraded pig manure

10 1.205 22.5 .795 5m.* 21.000** pot. stillage 22.5 .745 *m.: months—batch experiment,**1 gas/1·5 months

227 338 396 490

785 852 777 910

69–70 69–70 68 65

Table III. Gas production with pig manure (35°C) and potato stillage (56°C) as substrates tot.volat. acids fresh potato stillage fermented pot. stillage

acetic acid

propion. acid

isobut. acid

butyr. acid

isoval. acid

valer. acid

lactic acid

24

16

1

0.5

4.5

1.5

0.5

99

55

4

44

3

2

2

0

0

Table IV. Organic acids (mmol/l) in fresh and fermented (56°C) potato stillage

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Fig. 2. Kinetics of gas production with pig manure as substrate (35°C)

Fig. 3. Free ammonia fraction of total ammonia as a function of pH and temperature

were the only methanogenic bacteria detected in the fermented stillage. Final remarks level the concentration of free ammonia rises Figure 3 reveals that in a defined as the pH-value and the temperature increase. The main reason for the digestion failure at 56°C using pig manure as substrate may be the high concentration of free ammonia (>450 mg/1) found in the thermophi1ic fermenters. Similar toxicity effects of free ammonia have been reported by van Velsen et al. (4) and Zeeman et al. (5). The damage

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to methanogenic bacteria by free ammonia could be seen studying their fluorescent intensity. Both the H2-using bacteria (e.g. M. thermoautotrophicum) and the acetateusing Methanosarcina were damaged. Further evidence for the toxicity of free ammonia is given by Mathisen et al. (6): By stripping most of the ammonia from fresh pig manure thermophilic digestion was possible. Because of the high costs such pretreatment of pig manure is only reasonable if waste hygienization is required. In contrast to the digestion of pig manure stable fermentation of potato stillage could be obtained at 56°C. However, no difference is observed when comparing potato stillage fermentations under mesophilic (7) and thermophi1ic conditions. Furthermore, high concentrations of volatile fatty acids (55mmol/l)—in particular propionic acid—even at a low loading rate (1.5g vs/l·d) did not allow high organic loadings under thermophilic conditions. For these reasons mesophilic rather than thermophilic digestion of potato stillage should be applied in practice. Acknowledgement This project was supported by the government of the Federal Republic of Germany under contract PTB 8151. References (1) W.Baader, R.Kloss. Final report: Assessment of Biogas installations in the FRG, national German contribution to the project “Assessment of Biogas installations in Europe” —Ref. Nr. ES-E-R-051-D(N)—in the Solar Energy R/D-Programme of the Commission of the E.C., Braunschweig 1982. (2) A.Wellinger, W.Edelmann, R.Favre, B.Seiler, D.Woschitz Biogas Handbuch, V erlag Wirz AG, Aarau, 1984, pp. 37–40. (3) U.Temper, J.Winter, O.Kandler. Methane fermentation of wastes at mesophilic and thermophi1ic temperatures. In: Energy from Biomass, 2nd E.C. Conference, Palz, Chartier and Schleser (eds.) pp. 521–525; Appl. Sci. Publ. London, New York 1983. (4) A.F.M.van Velsen, G.Lettinga. Effect of feed composition on digester performance. In: Proceedings of the first Int. Symp. on Anaerobic Digestion, Univ. College, Cardiff 1979. (5) G.Zeeman, W.M.Wiegant, M.E.Treffers. The influence of ammonia in the thermophi1ic digestion of dairy cow slurry. In: Proceedings of the AWWT-Symp., Noordwijkerhout, 1983, pp. 529–530. (6) B.Mathisen, M.Hagelberg, A.Sandkvist. Thermophilic anaerobic digestion of piggery waste. In: Proceedings of the 3rd Int. Symp. on Anaerobic Digestion, Boston, USA, 1983, p. 531. (7) R.Braun, S.Juss. Anaerobic digestion of distillery effluents. Process Biochemistry, July/August 1982, pp. 25–27.

ANAEROBIC DIGESTION OF MACROALGAE IN THE LAGOON OF VENICE: EXPERIENCES WITH A 5 mc. CAPACITY PILOT REACTOR S.NICOLINI and A.VIGLIA AGIPGIZA S.p.A., Reggio Emilia, Italy Summary Research was conducted in order to check the conversion yields of algae biomasses into biogas with increasing organic loads and decreasing HRT’s aimed at verifying the limits of the system itself. The treated material consisted of a mixture of three species of macroalgae infesting the lagoon of Venice: Ulva rigida, Valonia aegrophila and Gracilaria which the lagoon contained in percentages varying according to the season and area of collection. The system was operated in mesophylic conditions (35°C) to identify and/or to optimize the following parameters: – patial load – HRT – biogas conversion yields – CH4 % in the biogas. 1. METHODS The investigation was conducted in the f ield with the aid of a 5m3 capacity anaerobic pilot reactor located in the lagoon area. Before digestion, the algae biomass was subject to a series of pretreatments such as washing.homogenization and storage, in order to make the organic substance more available for transformation. The analytical examination of the algae showed the presence of many cations of heavy metals which could negatively influence the microbic flora responsible for the anaerobic process, hindering correct metabolism. Even with very high specific loads, the adopted methods did, however, enable the control of both H2S levels in the biogas and the inhibition phenome na to which the microbic flora themselves could have been subjected.

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2. CONCLUSIONS The results obtained in the above mentioned operative conditions show that the anaerobic digestion of the utilized algae biomasses is feasible and that it is possible to reach conversion yields equal to one volume of biogas per daily reaction volume, even with low HRT (ca. 10 days). The inhibition levels related to the presence of cations of heavy metals and to the high salinity of the medium which particularly contained sulphates, can be limited and controlled within paraphysiological values for the flora subject to a progressive acclimatization.

Anaerobic digestion of macroalgae of the lagoon of venice: experiences with a 5 mc capacity pilot reactor

CORRELATION BETWEEN H.R.T., SPECIFIC YIELD & V.S. CONCENTRATION

CORRELATION BETWEEN CONCENTRATION.

SPATIAL

BIOGAS PRODUCTION

LOAD,

pH

&

CO2

AND

H2S

689

BIOENERGY FROM TANNERY BIOMASS: EXPERIMENTAL WORK ON ANAEROBIC DIGESTION FROM LABORATORY TO REAL PLANT SCALE M.BREGOLI, D.FERRARI and A.VIGLIA AGIPGIZA S.p.A., Reggio Emilia, Italy Summary The research was conducted in order to check the possibility to treat tannery sludges with a high content of organic substances produced by the depuration systems of one of the most important Italian tanneries poles. In this frame, the system is also working on primary sludges and their mixture with biological ones, in order to give operative solutions to industrial problems. Research allowed to identify and/or optimize the following parameters in mesophyl running conditions (35°C): – spatial load (C); – HRT; – biogas conversion yields; – CH4 % in the biogas. 1. METHODS The investigation was conducted in two separate phases; the first one incentered on an explorative research in the laboratory with a pilot unit having an operative volume of 300l, the second one was conducted in the field with a 200m3 capacity industrial reactor. In both cases, there was the same starting-up procedure and the consequentiality of the tested sludges in order to study feasible running situations and to obtain a CS of 3Kg ST/m3r.g with an HRT of 15 days. 2. CONCLUSIONS Research showed how, in certain cases and particularly for primary sludges, the conversion yields of organic carbon into biogas are high and equal about to 70% of those obtained with secondary biomasses of animal origin. As often observed with biological sludges, metabolic inhibitions related to high percentages of sodium, chromium and other salts present in the examined substrates in high concentrations is, however, a possibility which should not be ignored.

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This presence, together with the extreme variability of the relative concentrations, might pose certain limits to the application of this practice which can be considered subsidiary but not “alternative” in the global field of tannery sludge elimination. Furthermore and with reasonable investments, this technology cannot currently be recognized as an active part of the general energy balance of depuration unless the tanning industry rationalizes its productive cycles.

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Bioenergy from tannery biomass

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UTILIZATION OF ACTIVATED CARBON AND CARBON MOLECULAR SIEVES IN BIOGAS PURIFICATION AND METHANE RECOVERY E.RICHTER, K.-D. HENNING, K.KNOBLAUCH, H.JONTGEN Bergbau-Forschung GmbH, Essen, Federal Republic of Germany Summary Biogas can be used for heat and electricity production or, after methane enrichment, as substitute natural gas. However, typical impurities like hydrogen sulphide, halogenated hydrocarbons need to be removed prior to use of such gas. Adsorption processes using activated carbon or carbon

Fig. 1.: Biogas Purification molecular sieves are particularly suited for these purposes. Hydrogen sulphide is separated by catalytic oxydation producing sulphur. The halogenated hydrocarbons are removed by adsorption to activated carbon.

Utilisation of activated carbon and carbon molecular sieves in biogas purification and methane recovery

By means of special carbon molecular sieves and a newly developed pressure swing process, the methane concentration can be boosted to reach natural gas quality.

1. INTRODUCTION Generally, the term “biogas” stands for a gas mixture consisting predominantly of methane (50–70% by vol.) and carbon dioxide (30–50%) produced by anaerobic microbiological degradation of organic compounds in bioreactors, fermenting towers or landfills (1). After hydrogen sulphide removal, gas produced in wastewater treatment can be cycled to burners or gas motors for heat or electricity production respectively. Processing to produce SNG quality or motor fuel requires additional carbon dioxide separation and compression. Landfill gas may contain halogenated hydrocarbons which lead to considerable corrosion damage to gas motors and heating systems (2). Adsorption processes using crbonaceous adsorbents (activated carbon, carbon molecular sieves) can be used as alternatives to other processes for all the above-mentioned treatment steps (Fig.1). 2. PURIFICATION PROCESSES 2.1 Hydrogen sulphide removal Typically, the H2S contents of landfill gases and gases from water purification range between 0,2 and 6g/m3. A lowmaintenance activated-carbon process of robust design converting hydrogen sulphide in one step into elemental sulphur is trial-run at present (3). Hydrogen sulphide reacts on activated carbon in presence of oxygen at low temperatures already to produce sulphur and water:

695

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Fig. 2.: H2S-Removal from Biogases The sulphur is adsorbed to the internal surface of the activated carbon. The sulphur loads may reach 100% (by weight) of the activated carbon. The oxygen required for oxydation of the hydrogen sulphide is already contained in the landfill gas or the gas from water purification. In case of lower H2S contents below 1mg/m3 were recorded adsorber can be designed for an adsorption period of up to one year. In such cases, the loaded activated carbon is not regenerated in the plant but elsewhere, or rejected. For higher H2S concentration in the raw gas, a regenerative process with two fixedbed adsorbers was developed (Fig.2). One of said adsorbers is run on H2S removal while the other one undergoes thermal regeneration. For regeneration, the sulphur is desorbed by inert gas with activated carbon at a temperature of around 500°C. After regeneration, the activated carbon can be used again for H2S removal. 2.3 Halogenated hydrocarbons For removal of these halogenated hydrocarbons, adsorption processes using activated carbon are on hand. In contrast to the industrial exhaust gas streams, landfill gas exhibits concentrations of a number of individual components which are not in the 1000– 10.000mg/m3 range, but considerably lower (<100mg/m3). This should be catered for in design. The process layout will correspond to the solvent recovery technology wellproven since 50 years. Loaded activated carbon may be regenerated by adsorption with steam or hot inert gases. A modified process for halogenated hydrocarbons removal from landfill gases is under development at present.

Utilisation of activated carbon and carbon molecular sieves in biogas purification and methane recovery

Fig. 3.: BF-Pressure Swing Adsorption for Biogas 3. METHANE ENRICHMENT Biogases contain up to 30 or 50% (by vol.) of carbon dioxide which needs to be removed if SNG-quality gas is to be produced. After the preliminary purification steps described above, drying and methane enrichment can be run in a pressure swing adsorption plant developed by Bergbau-Forschung GmbH. A carbon molecular sieve CMSC produced by Bergwerksverband Essen, Federal Republic of Gernmany, is used. Its pore structure is adjusted in a way that carbon dioxide, nitrogen, oxygen and steam are adsorbed considerably faster than methane (4). Neither CO2 scrubbing nor membrane technology allow air and steam, equally undesired components, to be removed to the same extent as the CO2 concentration. Fig.3 shows a simplified scheme of a pressure swing adsorption plant, a very simple configuration just comprising a compressor, a vacuum pump, three adsorbers, and the not particularly marked valve gear. In these three or four adsorbers, the following steps are run: – adsorption (methane/SNG recovery) – pressure release – evacuation (CO2/N2/O2/H2O desorption) – pressure build-up Trials run in a pilot plant have shown that a product gas with a methane concentration of more than 87% (by vol.) (L gas/Netherlands), 91% (by vol.) (L gas/FRG) and of 99.5% (by vol.) (H gas/FRG) steam dew point below −20°C) is obtained. L gas could be recovered even from gases exhibiting an unwanted air concentration of up to 12% (by vol). In this case, the methane recovery exceeded 95%.

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REFERENCES

(1) HEDDEN, K., HEIKE, T., RAO, B.F. (1982). Die Rolle nichtfossiler Brennstoffe für die Gaserzeugung . (The importance of non-fossil fuels for gas production). gwfgas/erdgas 123, No.10/11, p.483/495. (2) DERNBACH, H. (1984). Korrosionsschäden an Gasmotoren in Deponiegasnutzungsanlagen aufgrund chlorierter Kohlenwasserstoffe. (Corrosion damge caused by chlorinated hydrocarbons on gas motors in plants for landfill gas use). Recycling International/Jahrbuch 1984, EF-Verlag für Energie- und Umwel ttechnik, p.262/267. (3) HENNING, K.D., KLEIN, J. and KNOBLAUCH, K. (1985). Schwefelwasserstoff-Entfernung aus Biogas mit einem Aktivkohle-Verfahren (H2S removal from biogas by an activated-carbonbased process). gwf-gas/erdgas 126 NO.1, p.19/24. (4) RICHTER, E., KNOBLAUCH, K. and JONTGEN, H. (1985). Mög-lichkeiten zur adsorptiven Methan-/Kohlendioxid-Trennung aus Biogasen (Possibi1ities of adsorptive methane carbon dioxide removal from biogases). gwf-gas/erdgas 126, No.1, p.10/14

MEMBRANE CLEANING OF BIOGAS FOR INJECTION TO PIPPELINES F.De Poli; M.Mendia; N.Migliaccio ENEA—dip. FARE; ENVIROGENICS Co; LASER s.r.l. Summary When using biogas in on-site system, to produce electri city and/or heat, more than 20% of its energy potential is dissipated. Biogas injection into pipelines permits, instead, a better utilization of its energy content. However for such purposes, as well as for on site automotive application, biogas needs to be purified from CO2 H2S, H2O and other components. An economical analysis is presented comparing physical and chemical absorption and reaction processes vs. sele ctive polymeric membrane separation. The latter has been found competitive for systems treating more than 250Nmc/h of biogas feed. Due to the higher content of CO2 in biogas landfill, mem brane separation is an even more adequate process.

1. INTRODUCTION The biogas has a valuable energy content because of its methane fraction. The best use of biogas is the direct combus tion for heating purposes. But where the production is relevant the thermal utilization point might be missing or too distant. Electricity generation with or without thermal co-genera tion is often used for on-site systems. But, because of the lag between the time constant energy production and the fluctuating energy utilization, overal dissipation may occur. In addition electricity generation is not so convenient when compared with electricity costs of the large distributors. By injecting the biogas into pipeline, instead, all biogas energetic content is available to the final users. In the locations that give the largest biogas production this system can be the best utilization. Depending upon its usage, biogas has to be purified. In the case of pipeline injection or engine combustion,biogas needs to be cleaned from inert diluents and from other compo nents that may cause damages to pipes or equipments. Many different methods of gas clean-up exist among them become recently available separation of biogas components by selective polymeric membranes. This system presents the advan tage of giving purified biogas stream while keeping the pres sure of the pressurized feed stream, allowing direct injection into pipelines or bottling with savings in recompression costs. Furthermore, membrane separation gives 90–95% recoveries of the feed methane content.

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An economical analysis has been done comparing, on the basis of biogas feed, two other purification processes vs. membrane separation. The data are based on detailed engineered designs finan ced by ENEA’s FARE dept. Experimental and pilot work will be soon conducted to verify the assumptions with field data. 2. BIOGAS COMPOSITION AND CLE AN UP REQUIREMENTS Biogas consists of a complex mixture of gases and entrai ned fluids. The major costituents are CO2 and CH4. Minor con stituents include H2S, H2, CO, N2, O2, as well as a wide ran ge of minor organic constituents, the exact nature and concen tration of which depends on the raw material being digested. In addition, table I shows biogas compositions as functi on of its origin i.e. whether sewage sludge digester or land fills.

TABLE I—BIOGAS COMPOSITIONS BIOGAS FROM

AV. DAILY PRODUCTION AV. COMPOSITION % VOL. CH4 CO2 H2O H2S N2

SEWAGE DIGESTER LANDILL

5.000 NMC 12.000 NMC

60 38, 8 50 39, 5

1, 0 0, 1 0, 1 7, 0 0,002 3, 5

The energetic content of biogas depends on its methane fraction. Both CO2 and N2 are inert diluents, lowering the calorific value of he gas. Biogas is potentially explosive and represents a health hazard because of the presence of H2S and CO2. When burned, biogas releases air polluting SO2 by oxidation of H2S: other sulphur containg biogas constituents may cause air pollution, too. H2O, H2S, O2, CO2 are corrosive for equipments or pipes, In table II are shown gas quality requirements as a fun ction of biogas use.

TABLE II –REQUIRED GAS QUALITY BIOGAS USE DIRECT COMPUSTION MOTIVE POWER BOTTLING PIPELINE

% VOL. REQUIRED OF COMPONENTS CH4 CO2 H2S N2 H2O 40~90 60~95 90 91

50~10 40~5 4 3

0,05 0,05 0.01 0,005

– 1 6 6

0,5 0,1 0.01 0.01

3. TRADITIONAL METHODS OF GAS CLE AN UP One of the most common treatment for biogas cleaning is absorption of H2S on solid masses. Solid mixture “bog-ore” is used as “laming mixture”. During the treatment of the gas sul phur accumulates around solid particles isolating them from gas contact. When the sulphur has reached 50% of the weight of reactive mas the solid has to be removed.

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Another purification system is absorption with water; other systems use chemicals, like amine, but the water system has large diffusion because of its lower costs and easier main tenance. 4. MEMBRANE SEPARATION PROCESS The purification sysstem presented herein is the separation by membranes. The process parameters arer: feed pressure, selectivity and permeability of the membranes. For maximum ef ficiency the geometry on the feed side is arranged so that there is no mixing of the feed from point to point on the mem brane. Furthermore the feed velocity at every point is kept high enough to minimize the excess concentration of the slower permeating species in the membrane surface boundary layer.

Fig. 1 –MATERIAL BALANCE IN MEMBRANE SEPARATION

Feed pressure ranges between 15–75 ATA (the minimum for sufficient driving force and the maximum to limit mechanical stresses of the membranes and modules). As shown in Fig. 2 the membranes are configured in spiral woud elements. These elements are either 2, 4 or 8in.in diam. 40 or 60in. in lenght and housed in steel pressure vessels. Minimum feed flow is 25Nmc/h when using 2in. modules. Economic analysis of membrane separation pro cess for biogass have demostrated that 40 ATA as optimal feed pressure

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Fig. 2 SPIRAL WOUD ELEMKNT

5. COSTS ANALYSIS FOR BIOGAS PURIFICATION Tab. III presents costs data for water and membrane separation processes for purification of biogas originated by sewage digesters (case A) and landfills (case B). Costs are indicated in It. lire; the capital costs are computed on the basis of 20 years pay-back time.

TAB. III—PIPELINE INJECTION COSTS OF ONE NMC CH4 Separation by WATER MEMBRANE Biogas from A B A B COSTS It. Lire Operating 35 Capital 12

40 12

27 14

28 16

Landfill biogas purification is more exspensive then sludge digestion biogas purification irrispective of the treatment process. This is due to the higher content of inerts in the first. By water treatment, operational costs differences between the two feed sources are larger because of the methane los ses in the water streams,while, with membrane treatment, reco veries up to 95% of the feed methane are achievable. Capital costs are, instead higher in the case of membrane systems and increase with the CO2/CH4 ratio, because of the need of pre-treating the whole feed stream. Still, membrane separation is overall more convenient, the economic advantage becoming really attractive for plant sizes from 250Nmc/h of feed stream, and beyond.

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Fig.3 ENERGY AND ECONOMIC UTILIZZATION SCHEME

*Distribution network losses represent the limited efficiency of the pipeline final users. Fig.3 reports the energy and economical flow diagrams of biogas, relative to domestic sewage sludges. Biogas economic value is considered pro portional to its methane fraction. The costs of the different phases of treatment and utilization have been computed. The comparison has been done between biogas desulphuration only and subsequent on-site usage for cogeneration and membrane treatment for pipeline injection. The latter appears at least 15% more convenient. REFERENCES 1) Ashare E. 1978 Fuel gas production from biomass; Ed. D.Wise C.R.C.Vol II 2) B.A.B.A. Digest 1980/83 Proceedings of workshop on biogas scrubbing 3) Cernuschi S. 1982 Ingegneria Ambientale 11/82 4) Cioppa O. 1968 Ingegneria Sanitaria 4/68 5) Jannelli G. 1981 Ingegneria Ambientale 3/81 6) Mazur W.H. and Chan M.C. 1982 A.J.Ch.E. Oct.82 7) Saltonstall C.W. et al. 1982 comunication by courtesy of Envirogenics Co. 8) Migliaccio N. 1984 Acqua Aria n°3/84

BIOMASS AND COENZYME F420 DISTRIBUTION IN ANAEROBIC FILTERS N.O’Kelly, P.J.Reynolds, A.Wilkie and E.Colleran Department of Microbiology, University College, Galway, Ireland Summary Laboratory-scale, random-packed anaerobic filters were utilised to investigate media related effects in upflow anaerobic filters. Using fired clay filters, operation in downflow mode was shown to be more stable and to allow higher COD conversion efficiency at high loading rates than operation in upflow mode. Clay was clearly superior to other support materials tested with respect to ease and quantity of biofilm development. This did not appear, however, to result in superior filter performance at higher loading rates. In both upflow and downflow units, the bulk of the COD removal efficiency was located in the sections closest to the feed inlet. Despite the build-up of VSS in the lower sections of downflow operated filters, it appeared to contribute little to the overall reactor performance. Treatment efficiency could not be correlated with either specific surface area or porosity.

1. INTRODUCTION The anaerobic filter or anaerobic packed-bed reactor belongs to the group of anaerobic digestion reactors known collectively as retainedbiomass reactors. The distinguishing feature of anaerobic filters is the presence of an inert packing material which retains the active microbial biomass both as an attached biofilm and in the form of entrapped flocs or granules in the interstitial spaces. Support media used in tests conducted to date have ranged from stone chips to a number of commercially available plastic and ceramic tower packings and have included more unusual materials such as fired clay, cloth, shells, coral, reeds and bamboo rings (1). The support material is fixed in a vertical bed which may be loose-fill, modular or channel-packed, is in a fully submerged state and is operated either in an upflow or downflow feed mode (2,3). The anaerobic filter has been successfully utilised at laboratory, pilot and full-scale for a variety of low to medium to high strength industrial, agricultural and domestic wastewaters, including distillery, food processing, pharmaceutical and chemical industry effluents as well as animal slurries, silage effluent, landfill leachate and domestic sewage. It may be expected that support media surface characteristics and media type, shape, porosity, void size, depth and placement geometry will influence both the distribution and activity of the retained microbial population within the anaerobic filter. To date, only a limited number of studies have attempted to identify and evaluate media-related effects in the operation of fixed-bed reactors. Waste flow direction is also likely to affect the degree

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of retention of the suspended population in fixed-bed reactors, yet few comparative studies have been carried out to date on the effect of feed flow direction on the biomass distribution within the fixed bed. The effect of effluent recirculation on the biomass distribution and on reactor performance has likewise received little investigation either at laboratory or pilot-scale. This paper deals with the effect of support matrix type, flow direction and effluent recirculation, on volatile suspended solids and F420 distribution in laboratory-scale, random-packed anaerobic filters. 2. MATERIALS Laboratory-scale filters were constructed from wavin sewer pipes and fittings to an external diameter of 156mm and a height of 1.2m as previously described (4). Support materials utilised included polypropylene cascade mini-rings of 38.50mm in diameter, fired clay fragments which passed through a 3.8cm and were retained on a 2.5cm sieve, mussel shells, ‘coral’ (a multibranched, calcareous alga known commercially as maerl) and PVC rings of 23mm internal diameter and 25mm depth. The total volume of each filter was 21.3l with a gas and feed distribution volume of 3.3l, giving a filter bed volume of 18l. The filters were seeded with sludge obtained from the effluent from laboratory filters treating pig slurry and silage effluent. The operating temperature was 33°±2°C. Pig slurry supernatant feed was obtained from an above-ground holding tank in a local piggery. The slurry utilised had undergone considerable liquefaction in underfloor tanks during the normal 2–3 week holding period and had been separated by gravity settlement prior to collection. The total COD of the slurry supernatant utilised in the different trials varied from 17,000 to 34,000mg.l−1, depending on the degree of dilution with wash and rain-water at different periods of the year. Silage effluent was obtained from a local farm and diluted to a total COD content of 11,000mg.l−1 before feeding. Measurement of TS, SS, VSS, COD and TOA was performed according to standard APHA or USEPA methods, as described previously (5). Methane percentage in the biogas was determined by gas liquid chromatography using a Poropak Q column. Individual volatile acids were determined by GLC using a chromosorb W-HP (80–100 mesh) column packing coated with 10% FFAP. Coenzyme F420 was determined using a modified version of the Delafontaine procedure (6). 3. RESULTS AND DISCUSSION The performance of four upflow filters containing cascade minirings, fired-clay fragments, coral and mussel-shells in loose-fill packing arrangement was monitored during start-up and operation at a variety of hydraulic retention times using a pig slurry supernatant feed. The trial was designed to evaluate the effect of porosity and specific surface area on start-up and performance at different loading rates. The porosities and specific surface areas of the support media were: clay, 69% and 119m2.m−3; coral, 71% and 490m2.m−3; mussel shells, 80% and 161m2.m−3 and plastic mini-rings, 94% and 179m2.m−3. The reactors were operated ab initio at a constant COD loading rate of 5kg COD.m−3.d−1 and a hydraulic retention time of 6 days during the start–up phase. Start-up

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was most rapid with the clay filter (c. 20 days) and was slowest with the mussel shell support. Irrespective of the time taken for start–up, the performance of the four filters at steady state at the HRT and loading rate specified above was similar, with COD removal efficiencies of 69–73 being attained. The loading rate was increased stepwise to 27.9kgCOD.m−3.d−1 by progressively decreasing the HRT from 6 to 3, 2 and 1 days. Treatment performance decreased for all four filters as the HRT was reduced from 6 to 1 day. At each loading rate, however, similar COD and VFA removal efficiencies were exhibited by the four filters, with marginally superior performance being noted for the clay filter at 6 and 3 day HRT. No correlation was obtained between treatment performance and either matrix porosity or specific surface area. Studies on COD and VFA profiles and on VSS distribution within the matrix bed showed that the bulk of the COD and TOA conversion took place in the lower section of the filters which also retained the highest proportion of both the attached and suspended volatile solids. The coral matrix was found to retain considerably higher attached and suspended VS at all loading rates tested but this was not reflected in the treatment performance obtained. The clay filter utilised in The above study was subsequently converted to downflow feed mode and operated at loading rates of 5.6 to 22.2kgCOD.m−3.d−1 and hydraulic retention times of 2 to day over a period of 184 days using a silage effluent feed (11,000mg.l−1COD). At the end of the trial period, the COD removal activity was shown to be located in the upper sections of the filter which also contained the highest levels of attached VSS. The content of VSS in the interstitial spaces increased towards the lower sections of the filter with maximum levels occurring in the dispersion volume beneath the filter bed. Although accumulation of microbial biomass at the bottom of a downflow filter is to be expected, the COD removal profile suggested that these cells did not contribute significantly to the performance of the filter. Two identical filters containing fired clay matrix in loose-fill packing arrangement were started up on a pig-slurry feed and operated for 300 days at 3 and 1 day HRT and at loading rates ranging from 6 to 17kgCOD.m−3.d−1. One filter was operated in upflow and the second in downflow feed mode. The start-up rate and steady-state performance at 3 day HRT for both reactors was essentially similar. At higher loading rates, the downflow reactor performed significantly better than the corresponding upflow unit and exhibited more stable operation and more uniform gas output. Within the matrix bed, the bulk of the VSS was shown to be attached as a biofilm to the matrix pieces in both the upflow and downflow reactors (Fig.1). A decrease in the attached VSS in the lower section of the downflow reactor was noted. Suspended VSS decreased towards the top of the matrix bed in the upflow unit and increased towards the bottom of the downflow reactor. Analysis of the coenzyme F420 content of the VSS showed that the specific F420 content of the suspended VSS was higher in the lower sections of the upflow filter than towards the top (Fig. 1). Although the F420 content of the attached VSS was consistently lower than that of the suspended VSS throughout the filter, nevertheless the higher level of attached VSS ensured that the bulk of the methanogenic population, particularly in the upper sections of the upflow filter, was contributed by the attached VSS. In the downflow reactor, the specific F420 content of both the attached and the suspended VSS was more uniform throughout the matrix bed (Fig. 1). When the relative levels of VSS were taken into

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account, it was evident that a higher proportion of methanogens was contributed by the attached VSS at all levels in the filter bed. The start-up procedure was varied using two further filters containing loose-fill PVC ring packing and operated in upflow mode on a pig slurry supernatant feed. One filter was started up at a high loading rate of 5kgCOD.m−3.d−1 ab initio, without recycle, and the loading rate to the second filter was increased incrementally from an initial

Fig. 1. Vertical distribution of the attached and suspended VSS and of their specific F420 content in upflow and downflow fired clay filters treating pig slurry supernatant.——Attached VSS;——Suspended VSS. loading rate of 0.5 to 5kgCOD.m−3.d−1, with effluent recirculation. The former procedure allowed the most rapid start-up but no difference was noted between the treatment performance of the two reactors at steady state. The level of attached VSS, in general, was almost an order of magnitude lower than that observed in the clay filter. In both the recirculated and non-recirculated reactors, the attached VSS decreased with increasing reactor height. The decrease was even more marked for the suspended VSS which was present in high concentration in the lower sections of both matrix beds. Clearly

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recirculation did not result in a more uniform distribution of either the attached or suspended VSS throughout the filter bed. Analysis of the F420 content again indicated a higher specific F420 content in the suspended VSS at all levels in both filters. A peak in specific F420 levels was noted for both the attached and suspended VSS in the middle section of the recirculated filter bed (Fig.2). It is clear from these studies that the support matrix type may greatly influence the relative distribution of the biomass in the matrix bed of anaerobic filters. Clay appears to provide a superior surface for attachment and this may be attributed to surface roughness and possibly also to the provision of inorganic nutrients, such as iron, which stimulate the growth and activity of the methanogenic population.

Fig. 2. Vertical distribution of the attached and suspended VSS and of their specific F420 content in upflow PVC ring filters operated with and without effluent recirculation on a pig slurry supernatant feed.——Attached VSS;——Suspended VSS. During operation in downflow mode, the bulk of the COD conversion takes place in the upper section of the filter and the biomass which settles in the lower sections appeared to contribute little to filter performance at the relatively high loading rates utilised. Effluent

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recirculation did not appear to alter filter performance nor did it significantly affect the VSS distribution in upflow feed mode. Ongoing studies with soluble substrates, such as silage effluent and sucrose wastewaters, may yield further information on the evidently complex media-related effects in anaerobic filter performance. REFERENCES (1) COLLERAN, E., WILKIE, A., BARRY, M., FAHERTY, G., O’KELLY, N. and REYNOLDS, P.J. (1983). One and two-stage anaerobic filter digestion of agricultural wastes. In Proceedings of 3rd International Symposium on Anaerobic Digestion, 285–302. Published by 3rd International Symposium on Anaerobic Digestion, Cambridge, Massachusetts.

KINETICS OF LANDFILL LEACHATE TREATMENT BY ANAEROBIC DIGESTION J.M.LEMA (*) and E.IBAÑEZ(**) (*) Departamento de Química Técnica. Facultade de Química. Universidade de Santiago de Compostela.-Galicia.-Spain (**) Departament de Química Tècnica. Facultat de Ciències. Universitat Autònoma.Bellaterra.-Catalunya.-Spain Summary The present contribution deals with the use of Anaerobic Digestion for the treatment of the leachates from the Garraf landfill, Barcelona.-Spain, where 500,000–600,000tn of solid wastes are deposited by year, producing 100–125m3/day of a highly polluted wastewater. The COD, 21000–23000 is mainly attributable to the presence of VFA and most of the remaining is from protein and hydroxyaromatics compounds. Laboratory anaerobic digesters were operated at HRT (equal to SRT) up to 35, 29, 24, 18, 15, 12.5, 8 and 5 days. Substrate samples were routinely analised for pH, ORP, COD, VFA, VSS, phosphate, protein and ammoniacal nitrogen. Gas composition of the produced biogas was determined by GC. In the digesters operating at HRT 15 or less, addition of phosphate was neccesary to keep the digester stable. The process was modelled using Chen & Hashimoto’s kinetic equation. Experimental data were fitted to the equation by means of a non-linear regresion computer program, getting a good correlation (deviation less than 5% in all cases). The value of the kinetic parameters were: µm=0.275; K= 0.465 and R=0.10, which indicate the presence of a refractory material. The methane production per volume of digester was also modelled using a experimental value of Y (1 CH4/kg COD removed) of 377. 1. —OBJECTIVES Without any doubt, of the various alternatives for treatment of urban solid wastes, the controlled landfill is the most common, due to its lower operational costs. One of the major problems associated with the landfills are the waters from the rain or from the waste original moisture that flow along the waste. These waters, leachates, generate a serious contamination problem, both of superficial and underground waters. A study to evaluate the perfomance of the anaerobic digestion of the leachates from the Barcelona urban solid waste landfill is presented in this paper. The landfill, located in Garraf (Barcelona, Spain) with a disposal area of 72 Ha., treats from 500,000 to 600,000

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tn/yr of waste. Its ground has been treated with a laver of gunnite, in order to avoid leaking. As an average 100–125m3 of leachates are collected from the landfill, with the characteristics showed in Table I. W pH COD SS %VSS Ac Pr Bu iVa nVa Ca P N 1 7.65 21480 390 2 8.39 23725 5840 3 8.44 22320 850

66 6300 1850 940 510 650 970 1340 1550 41 4010 700 1990 420 720 1700 2465 3000 68 3500 910 1810 360 570 1495 2000 4010

Table I W: sample of water COD: Chemical oxigen demand (mg/l) Ac: Acetic acid (mg/l) Pr: Propionic acid (mg/l) Bu: n-Butiric acid (mg/l) iVa: i-Valeric acid (mg/l) nVa: n-Valeric acid (mg/l) Ca: Caproic acid (mg/l) P: Phosphate (as o-) (mg/l) N: Ammoniacal nitrogen (mg/l)

As it can be seen they are highly polluted wastewaters. Its soluble COD is mainly attributable to the presence of volatile Fatty Acids (VFA), (60–75%), proteins and hydroxyaromatic compounds. It is worth to emphasize the amount of ammoniacal nitrogen present, being the cause for a slightly alcaline pH. 2. —EXPERIMENTAL A series of six digesters of 1 liter capacity, thermoestabilised at 37.0+0.1°C, with a input/output system, agitation and gas produced collection, have been used. The analysis conducted include: Gas (Gas Chromatography, TCD, Porapak Q 3m, 1/8”, Helium 20ml/min), VFA (Gas Chromatography, FID, Chromosorb WAW (Neopentyl adipate 25%, H3PO4 2%), 2.7m., 1/8”, nitrogen saturated with formic acid 20ml/min), SS, VSS, COD, phosphate, proteins, pH, ROP, and hydroxyaromatic compounds. The digesters were inoculated with sludge from a urban wastewater treatment plant. Their working hidraulic retention time (HRT) were 35, 29, 24 and 18 days respectively. Subsequently, once steady state was attained, the operation times have been diminished according to a step-change model up to 15, 12.5, 8 and 5.2 days. On a general basis HCl have been added to all of them to maintain their pH approximately neutral. A decrease in the efficiency of the treatment, with an accumulation of VFA, was observed after eight weeks of operation in the digester operating at 15 days. The cause of this poor performance could be associated with insufficient disposable phosphate (less than 20mg/l). In fact, if a reference value for the C/N/P ratio of 250/7/1 is taken, it would be neccesary about 60mg/l of phosphate. This same problem started to arise in the digester operating at 12.5 days. For this reason a continuous addition of phosphoric acid was decided to keep the phosphate level at 60mg/l in these two digesters as well as in the lower HRT digesters, resulting in a significant recovery of the efficiency of the system.

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3. —RESULTS The results refering to the steady–state regime for the various HRT are shown in table II. For HRT’s higher than 18 days an almost constant efficiency (around 80%) was attained. This feature can be reasoned by the presence of hardly biodegradable material (refractory material). To confirm this hypothesis a digester operating at HRT of 100 days has been started, concluding that, in fact, there is a refractory fraction, composed of hydroxyaromatic compounds (tannins) as its major constituent, the remaining being basically proteinic material. The results obtained have been adjusted to Chen & Hashimoto’s kinetic model (1), ST /STO=R+(1−R) K/(µmθ−1+K) – 1– where: ST and STO are the outlet and inlet concentration, respectively (expressed as COD in this study) µm: maximum growth specific rate θ: Hidraulic retention time K: kinetic parameter R=Sr/STo is the refractory coefficient, being Sr the refractory substrate. A non-linear regression computer program was used to adjust the experimental results, giving the following values for the model’s parameters: R: 0.10 µm: 0.275 days−1 K: 0.465 Water HRT %COD Gas Production (1/1 %CH4 Load HCl added removal digester.day) (kg/m3.day) (ml/l.day) 3 3 2 2 1 1 1 1

5.2 8.0 12.5 15.0 18.0 24.0 29.0 35.0

43.8 65.6 74.0 76.8 83.4 84.0 83.8 84.7

0.991 1.030 0.807 0.692 0.541 0.450 0.367 0.311

70 67 65 67 69 68 70 68

1.88 1.86 1.40 1.23 0.99 0.74 0.63 0.52

3.12 3.52 2.17 1.39 0.91 0.80 0.54 0.54

Table II The organic load removed per digester volume and day, also refered as the rate of substrate consumption, is given by: rS=(STO−ST)/θ – 2– The methane production rate is related to rS by:

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– 3– where YO is the stochiometric yield (CH4 produced/COD removed). The values of YO and Y (CH4 produced/COD feeded) are shown in table III for each HRT considered. A linear regression for Y and 1/θ , as suggested by (2), gives a value for YO=377l CH4/kg COD removed, with a correlation coefficient of 0,991. H.R.T. 1/θ Yo Y 5.2 0.1923 368 161.2 8.0 0.1250 374 245.3 12.5 0.0800 375 277.5 15.0 0.0666 377 289.5 18.0 0.0555 377 314.4 24.0 0.0417 409 343.6 29.0 0.0345 408 341.9 35.0 0.0286 407 344.7

Table III By combining equations 1 and 3 with 4 the rate of methane production, day) is obtained:

, (1 CH4/m3

– 4– Figure 1 shows the experimental values of compared with the values to be obtained by means of equation 5 (←), and the experimental values for the percentage COD removal: % COD removal=1−ST/STo – 5 compared with those obtained for equation (1) (→). The maximum removal rate (and maximum methane production) can be shown both graphically or analytically to occur for a HRT: θmax= (1+/K)/µm=6.1 days and the corresponding wash-out HRT would be: θmin=1/µm=3.64 days.

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4. —REFERENCES 1.—Chen Y. and Hashimoto A. (1980). “Substrate utilization kinetic model for biological treatment process”. Biotechnol.Bioeng. 22, 2081 2.—Chen Y. and Hashimoto A. (1978) “Kinetics of methane fermentation”. Biotechnol.Bioeng. Symp. 8, 269

BIOGAS RESEARCH IN AUSTRIA J.SPITZER, Joanneum Research Society Graz P.SCHÜTZ, Ministry for Science and Research W.HIMMEL, Technical University of Graz Summary A five year research program has been conducted in Austria with the goal to replace part of the fossile fuel used for domestic heating in rural areas by biogas. The results of the program, which concentrated on biological fundamentals and on operation of demonstration plants, show that the biological process is well understood and that plant economy depends on an economic solution of the problems associated with process energy demand, gas utilization and substrate flow. Possibilities to solve these problems have been demonstrated. With the expected future increase of energy prices, biogas may be a valuable source of energy in rural areas.

1. INTRODUCTION Austria must import 610 PJ (1982) of primary energy per year which amounts to two thirds of its total primary energy needs. of these imports 73% are crude oil, refined oil products and natural gas. Import reduction in particular and the use of locally available renewable energy sources in general are, therefore, primary goals of the Austrian energy policy. One of the possibilities to achieve these goals is the increased use of biomass in domestic heating where 55% of the energy demand is covered by heating oil and natural gas. To promote this possibility through the production and utilization of biogas in rural areas, a number of R & D projects on the biological fundamental s and on design and operation of demonstration plants has been carried out in Austria under public sponsorship since 1980. Industry participated in this effort with the design and construction of biogas demonstration plants. Three research groups at three locations were involved under the coordination of the Federal Ministry for Science and Research: The Joanneum Research Society in cooperation with the Technical University of Graz, the Agricultural School Edelhof in cooperation with the Agricultural University of Vienna and the Federal Institut for Agriculture at Wieselburg. Most projects will be finished during 1985 so that conclusions regarding the technical and economic feasibility of biogas plant operation in rural areas in Austria may be drawn (1). 2. BIOLOGICAL FUNDAMENTALS At the beginning of the investigations on the biological aspects of biogas production methods for determining the important parameters characterizing the performance of the

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digestion process had to be made available: In addition to accurate laboratory methods, suchs as gaschromatography for the determination of the volatile fatty acids and the composition of biogas, simple analytical methods for the measurement of the CO2-and H2S-content of biogas and the dry-matter content of the substrate were developed for the practical application at biogas plants. An anaerobic glove box with an inert gas supply, a roller-agar machine and a gas distribution system for compressed gas mixtures were used to study pure cultures of methane bacteria in pressurized flasks and tubes according to the method of BALCH and WOLFE. Over a two year period kinetic data, growth yield, intensity of fluorescence of Methanobacterium formicicum, Methanobacterium bryantii, Methanococcus vannielii and Methanosarcina barkeri were investigated. Methane bacteria from the biogas plants C and E in Fig. I were isolated (2). Batch digestion tests with different substrates (cow manure, pig manure, chicken manure and mixtures thereof) to examine digestibility, gas yield, gas composition and rate of degradation were performed in a simple and easily used batch digestion unit (3). Operation of the five agricultural demonstration biogas pilot plants described below has been continuously monitored by measurement of the following parameters: – amount and temperature of feed substrate – digestor temperature – gas production and composition – composition of feed and effluent substrate (TS, VS, VFA, Kj-N, COD, pH) Operating results of all five plants have shown that for agricultural substrates the digestor design (tank reactor versus plug flow reactor) is of minor importance: The measurement of the volatile fatty acid concentration in different zones of plant C revealed that a local separation between the acidogenic phase and the methanogenic phase does not take place (4). 3. DEMONSTRATION PLANTS The projects on the design and operation of biogas plants concentrated on five on-farm demonstration plants with digestor volumes from 20m3 to 90m3 designed by researchers but operated by farmers, thus providing realistic testing conditions. The design of the plants is such that variations of two important parameters may be investigated (Fig. I): Geometry of the digestor: – vertical cylindrical vessel (A, B, C) with a concentric inner chamber (B, C) – inclined cylindrical vessel (D, E) Stirring of substrate by: – injection of compressed biogas (B, C, E) – releasing trapped gas (A, D) – mixer (E) or circulating substrate by pumping (C) Investigations on the demonstration plants concentrated on the optimization of substrate flow and reduction of process energy demand.

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Substrate flow Since straw-bedding for feedstock is most frequently used in Austria, all digestors were originally intended for operation with straw-rich manure, so that particular care had to be taken to prevent floating layers and sedimentation. It was found that the floating of straw is mainly due to small adhering gas bubbles and may be sucessfully controlled either by frequent stirring of the substrate or by milling the bedding straw and keeping the dry matter content above 8% in which case the separation of the straw was prevented by the high viscosity of the substrate. Problems encountered with sedimentation were mainly caused by lignin remains of (milled) straw and by chicken feed residues (sand). A sedimentation chamber and a downflow digestor with a conical outlet at the bottom are recommended to avoid sedimentation problems. Process energy demand A large effort was placed on the reduction of process energy demand. Possibilities for thermal insulation, substrate heat recovery systems and heating systems were investigated. With respect to heat recovery it could be shown that only simple designs without mechanical equipment can be economically operated. The digestors B and D of Fig. I were equipped with an integrated serpentine heat exchanger (I) and a prechamber heat exchanger (II) respectively. Both heat exchangers operate batchwise. The integrated system has low investment costs and reduces digestor heat losses to the environment (T2
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electricity that is substituted by biogas in rural areas. This increase will ultimately lead to acceptable plant economy. Much effort was put into determining plant designs with minimized capital investment and maximized utilization of the biogas produced. Depending on how much of the existing farm building structure can be uti-lized for the plant and also on how much of the construction can be done by the investor himself, the capital investment for biogas plants in Austria ranges from 10.000 to 20.000 AS per m3 of digestor volume. No decrease may be expected since a safe and dependable plant operation does not allow further reduction of component costs and since it is not advisable to design and construct the plant completely without professional support. The energy demand in Austrian farms is such that biogas utilization is generally poor. In most cases domestic heating and hot water production represent the only demand so that a large portion of the annual gas production has to be wasted during the summer. Possibilities for supplying additional users with biogas were investigated in some detail. Since storage of biogas is generally not economical (in particular long term storage required to utilize excess gas produced during summers) only additional users with a continuous energy demand are of interest. While biogas as a fuel for tractors is not economical because of the high cost of compressed gas storage on the vehicle, the operation of small motor driven power generators (generally without waste heat utilization) seems to be a good possibility to utilize excess biogas throughout the year. A different approach to improve the economy has been investigated in some detail: cooperatively organized biogas production and utilization in rural areas by either transporting waste of several farms to one central biogas plant or connecting the biogas plants with a gas distribution system. Both investment cost and gas utilization may be Improved particularly if an industrial user of the biogas with a whole year demand can be found. 5. CONCLUSIONS From the results of five years of biogas research in Austria the following conclusions may be drawn: The biological process is well understood and does not represent any key problem for the operation of agricultural biogas plants. On the other hand, optimization of the biological processes will not contribute very much to overall plant economy. More important with respect to plant economy are those problems associated with substrate flow, process energy demand and gas utilization. Experience with demonstration plants has shown that much attention has to be given to the piping and stirring equipment to avoid pipe blockages, scum layers and sedimentation in the fermenter. With regard to process energy demand it was found that with optimum heat transfer equipment and an optimum fermenter insulation together with a heat recovery system, some improvement of plant economy can be achieved. The greatest potential for optimization lies in gas utilization and the reduction of capital investment for the plant. No generell recommendation for the overall optimization of the plant economy can be given since the ideal situation must be determined for each individual plant.

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Despite the fact that in Austria the total contribution to the primary energy supply probably lies below two percent, biogas may be a valuable source of energy for specific applications particularly in rural areas. REFERENCES (1) BRUNNER, N. et al. (1984). Erzeugung von Biogas aus landwirtschaftlichen Abfällen. Institut für Umweltforschung und Institut für Biotechnologie Graz. Research report, ifu-B-13–84. (2) SCHEUCHER, P. (1984). Isolierung und Untersuchung von Methanbakterien aus landwirtschaftlichen Biogasanlagen. Thesis, University of Graz. (3) PANHOLZER, M. (1983). Energiegewinnung durch Abfallbeseitigung: Biogas aus landwirtschaftlichen Abfällen. Thesis, Technical University of Graz. (4) HIMMEL, W.; LAFFERTY, R.M (1983). Operating Experience with a Double Chamber Digestor with Cattle Manure Containing Straw as a Substrate. Anaerobic Waste Water Treatment Proceedings 511–525, 23–25 Nov. 1983, Noordwijkerhout, Netherlands.

Figure I: Schematic views of five biogas demonstration plants for different substrates in agricultural applications: A—cattle (design: BVT Austria) B—cattle (design: MET Austria)

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C—cattle (design: Joanneum Research Society) D—cattle (design: P.Schütz) E—pigs and chicken (design: Joanneum Research Society) I, II—heat recovery systems for plants D and B.

MATHEMATICAL MODEL OF A REAL SCALE DIGESTER R.CHIUMENTI*, A.DE ANGELIS**, F.DE POLI,**A.TILCHE** (*) Università di Padova—Istituto di Meccanica Agraria—Via Gradenigo n. 6—PADOVA (**) ENEA (Italian Commission for Nuclear and Alternative Energy)— Dip. FARE-TER-COM-IBI—CRE Casaccia—C.P. 2400—ROMA. SUMMARY The analysis of the time series of different variables of anaerobic digesters in real scale shows that a high correlation exists between the output (biogas yield output solids), and input (input solids, digester tem perature, loading rate, etc.) if the cross-correlation is lagged at a calculated time t. ENEA researchers have applied cross-correlation at different times, up to HRT of the digester, to 5 cases of real scale digesters. The first case about the FOCHESATO Brother’s plant is shown. Using the more correlated variables at the lag times showing highest correlation, with a multiple regression program, we obtained a model of the form shown below. We found a model with a F value >5, which implies a level of significance between 0.01 and 0.025

THE FARM AND THE DIGESTER The Fochesato Brother’s barn shelters 150 cows in free stalls. Resting and feeding alleys are made in slotted floor, under which mechanical scrapers transfer the liquid manure outside the barn, where another scrabber conveys the product to the storage basin. A screw pump transfer the manure to the digester. The digester is a 200m3 self-built horizontal concrete tank. The mixing and heating system consists of two centrifugal pumps and a double pipe external exchanger. CROSS-CORRELATION Cross-correlation functions were calculated between different variables at lag times up to 15 days. Occasionally the lag used is not the best correlated one due to the fact that the crosscorrelation is between two variables, and the model is calculated on a larger number of

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variables (three in this case, but up to five in others). This calculatlon was made on 46 days of continuous monitoring, but the same model was tested for other periods on the same plant, with similar results. The autocorrelation of the yield (number 1) and the output TS (number 10) indicates a high value at lag zero, decresing day by day. Variable 1 Biogas Yield (m3/d) Variable 2 Loading (m3/d) Variable 3 Input PH Variable 4 Output PH Variable 5 Input Redox Potential (mV) Variable 6 Output Redox Potential (mV) Variable 7 Digester Temperature (°C) Variable 8 Input Total Solids (%) Variable 9 Loading Rate (TS Kg/d) Variable 10 Output Total Solids (%)

RESULTS In the graph 1 and 2 the comparison of the observed and the calculated values can be seen; the curve of calculated values begins after several days according to the highest lag time applied. Biogas yield (BY) depends on loading rate (LR) at a lag of the three days, and on digester temperature (DT) at a lag of eight days. As shown by the graphs, the calculated values are rather similar to the measured ones, also in the presence of a high variability. The F value is 5.009 (44df), 0.025, P>0.01. Output total solids (OS) depend on digester temperature (DT) at a lag of eight days and on input solids (IS) at a lag of nine days; also in this case the model has a highly significative correlation with the experimental data. The F value is 5.682 (44df), 0.025>P>0.01. BY(t)=K1+K2LR(t−3)+K3DT(t−8) OS(t)=K1+K2DT(t−8)+K3IS(t−9)

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ANAEROBIC TREATMENT OF HIGHLOAD INDUSTRIAL WASTE WATER BY MEANS OF FREE-CELLS FERMENTATION PROCESS O.ZUFFI, N.MILANDE, B.RAYMOND Société BERTIN & Cie Zone Industrielle 40220 TARNOS—FRANCE Summary The company BERTIN and Co, which proceeds from the begening of the seventies about energy and chimical products from biomass, is improving in the way of anaerobic waste water treatment, a set of processes about both the production and the use of biogaz on industrial place.

1.1. Présentation du procédé actuellement développé à l’échelle industrielle Le traitement par méthanisation d’effluents liquides fortement chargés en DCO et/ou en matière en suspension tels que les effluents d’élevage (lisier de porcs ou de bovins), de brasserie (trouble du moût, fonds de tanks, freintes de bières et éventuellement levures en excès), d’abattoir (effluent de l’atelier triperie-boyauderie, jus de pressage des matières stercoaires, lisier et sang) implique l’utilisation de procédés industriels capables de fonctionner avec des charges appliquées élevées sans entraîner pour l’utilisateur de contraintes importantes pour le suivi technique, l’entretien ou la maintenance. Dans ce but, la Société BERTIN a développé, d’abord à l’échelle pilote (3m3), puis à l’échelle industrielle, un procédé à cellules mobiles, initialement inspire du procédé “contact” classique (avec ou sans separation des phases d’acidogénèse et de méthanogénèse) avec optimation des conditions de fonctionnement hydraulique permettant d’obtenir le meilleur contact possible entre la biomasse (qui s’absorbe le plus souvent sur les M.E.S. du substrat) et l’ef-fluent à traiter. Ce procédé fait l’objet de plusieurs réalisations industrielles sur différents substrats. Le tableau ci-dessous donne quelques exemples des résultats obtenus à différentes échelles.

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RESULTS OBTAINED AT FULL INDUSTRIAL SCALE OR ON PROCESS DEVELOPMENT UNITS Origin of Piggery waste Brewery (beer Slaughter Dairy (whey) Pharmaceutical the effluent (without waste, wort house industry pretreament) waste, yeast waste) pilot plant Scale industrial pilot plant pilot plant pilot plant (30l) (3m3) plant (170m3) (3m3) (30l) industrial industrial unit industrial unit unit under under under construction construction construction specific load kg DCO/ m3/day Biogas production m3/m3 digestor/day Average CH4 gas content % vol DCO removal

6–10

12–16

5–8

12

5–6

2−3

4–6

1.5–2.4

4.5–5.5

–

74%

70%

70%

68%

80%

74%

90%

80%

80%

60%

1.2. Développement de technologies associées Bureau d’étude et de recherche spécialisée dans les transferts de technologie, la Société BERTIN a d’autre part développé un certain nombre de procédés technologiques associés au traitement de méthanisation, tels que: – procédé d’épuration du biogaz par contacteur gaz-liquide compact avec régénération continue du catalyseur, permettant d’atteindre des teneurs en H2S inférieures à 20ppm (V/V) – émulsionneur permettant, dans le cas du traitement d’effluents chargés en matière grasse (abattoir, laiterie, conserverie de viande ou de poisson, suiferie, huilerie), l’obtention d’une dispersion de ces matières en fines particules dans le fermenteur, dans le but d’augmenter leur surface d’attaque et d’obtenir ainsi une hydrolyse et une digestion plus rapides de ces matières grasses – mise au point d’automates programmables permettant le contrôle en continu d’installations industrielles de méthanisation et de leur équipement annexe.

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1.3 Travaux de recherche en cours Nos travaux de recherche actuels portent notamment: – sur l’étude, sur installation de laboratoire et sur installation pilote, du traitement anaérobie d’eaux usées urbaines à basse température (15–25°C) – sur la mise au point, à l’échelle pilote (300 litres) d’un procédé de méthanisation en fermenteur à lit fluidisé liquide-solide entièrement automatisé. REFERENCES 1. “Traitement anaérobie d’effluents de brasserie. Expérimentation sur pilote en site industriel”. N.MILANDE—B.RAYMOND—Séminaire des contractants AFME—Biomasse— Méthanisation—VALBONNE (1982) 2. “Contribution à l’étude du procédé contact anaérobie avec et sans séparation de phase. Application au traitement d’effluent de brasserie”. N.MILANDE—Thèse de Docteur—Ingéni eur (1983) 3. “Epuration du H2S contenu dans le biogaz”. B.RAYMOND—N.MILANDE—Séminaire contractants AFME—Biomasse—Méthanisation—ST REMY LES CHEVREUSE (1984) 4. “Méthanisation des effluents agro-industriels”. J.Y.DEYSSON—J.M. INDART— N.MILANDE—B.RAYMOND—Journées MEI (1984) 5. “Méthanisation d’effluent urbain à basse température”. O.ZUFFI—B.RAYMOND— N.MILANDE—(1985)—En cours de publication 6. “Méthanisation de l’effluent de l’usine X en fermenteur à lit fluidisé” C.STREICHER— N.MILANDE—B.RAYMOND—(1985)—En cours de publication.

CLONING AND ANALYSIS OF GENES INVOLVED IN CELLULOSE DEGRADATION BY CLOSTRIDIUM THERMOCELLUM P.BEGUIN, D.PETRE, J.MILLET, R.LONGIN, H.GIRARD, O.RAYNAUD, M.ROCANCOURT, O.GREPINET and J.-P.AUBERT. Institut Pasteur, Paris, France Summary Various genes of Clostridium thermocellum coding for cellulases were cloned and identified by the expression of cellulolytic activity in Escherichia Coli. For at least three of these genes, transcription and translation in E. coli appeared to be initiated at sites located on the cloned C. thermocellum DNA fragment, and two of the expressed cellulases were found to be partially transported to the periplasmic space. The endoglucanases expressed by three of the clones displayed different specificities toward cellodextrins of various degrees of polymerization. Some of the clones produced activity hydrolyzing methylumbelliferyl-βcellobioside, but not carboxymethylcellulose. We are presently checking whether they correspond to genes coding for cellobiohydrolases. One of the endoglucanase genes has been sequenced and the origin of the mRNA transcript determined by Sl nuclease mapping. The sites governing initiation of transcription and translation, as well as the signal peptide allowing protein secretion appear quite similar to the corresponding structures described in other gram-positive bacteria.

1. INTRODUCTION Cellulose is the most important renewable carbon source available from plant biomass. Hence, its conversion into products that could be used as petroleum substitutes for industrial chemicals or energy production has been the subject of numerous studies. Among organisms that can degrade cellulose, Clostridium thermocellum displays several interesting features. This thermophilic and anaerobic bacterium secretes a highly potent and thermostable cellulase complex (1–4), which is able to degrade crystalline cellulose efficiently. The degradation products are subsequently fermented into ethanol, acetic acid, lactic acid, hydrogen and carbon dioxide, ethanol being the component of interest for energy production (5–7). The rate of cellulose fermentation by C. thermocellum is limited by the degradation rate of the insoluble substrate. When grown on cellulose, the organism has a doubling

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time of 6 hours, as compared to 2 hours when grown on cellobiose. Yet it appears that properly engineered strains of C. thermocellum could be improved considerably in this respect. Comparative studies (4) have shown that similar levels of cellulolytic activity are present in culture supernatants of C. thermocellum and strains of Trichoderma reesei hyperproducing cellulase. However, C. thermocellum cellulase has a much higher specific activity, since C. thermocellum culture supernatant contains only 0.2mg/ml protein, as compared to 9.5mg/ml in the case of T. reesei. This high specific activity of C. thermocellum cellulase should allow to reach levels of total activity exceeding those achieved by the best cellulolytic fungi, for which further improvements are limited by the sheer amount of total protein that should be secreted. In the absence of any known mechanism of genetic transfer, classical genetics in C. thermocellum is limited to random mutagenesis. Furthermore, it is quite difficult to study the various components involved in cellulose degradation individually, since cellulolytic enzymes from C. thermocellum associate together in the culture medium to form a highly stable complex, termed cellulosome by Lamed et al. (3). Attempts to dissociate the cellulosome generally result either in incomplete dissociation or in inactivation of at least some of the components (3, P.Béguin, unpublished). The problem can be avoided by cloning the various cellulase genes individually and expressing their products in a non-cellulolytic host such as E. coli. This strategy also provides the opportunity to characterize the structure of these genes, including the regions controlling transcription and translation, which are poorly known in thermophilic bacteria. From a practical point of view, the insertion of the cloned genes into expression vectors of E. coli or B. subtilis should allow to produce high amounts of C. thermocellum cellulases. Finally, once it becomes possible to transfer genetic material into C. thermocellum or other ethanologenic thermophiles, the availability of a collection of cellulase genes will be helpful for the development of more efficient cellulose-fermenting strains. 2. CLONING AND EXPRESSION OF CELLULASE GENES Gene banks of total chromosomal DNA from C. thermocellum were constructed either by cloning partial Sau3A digestion fragments at the BamHl site of the cosmid pHC79 or EcoRI fragments at the EcoRI site of the plasmid pACYC184. Screening for endoglucanase activity was performed by using carboxymethylcellulose (CMC) either in viscosimetric assays (8) or in the Congo red plate test devised by Teather and Wood (9, 10). Six clones bearing different endoglucanase genes were isolated (8, Pétré et al., manuscript in preparation). The cloned fragments do not cross-hybridize and are not adjacent. The enzyme expressed by one of the clones was found to be immunologically identical with the Mr=56,000 endoglucanase, termed endoglucanase A (EGA), which had been previously purified in our laboratory from C. thermocellum culture supernatant (1); the corresponding gene was termed celA. The endoglucanases expressed by the other clones had not been characterized previously. They were termed endoglucanase B, C (EGB, EGC) etc., and the corresponding genes celB, celC etc. Three clones, bearing the genes celA, celB and celC, are now well characterized (10–12, Pétré et al., manuscript in preparation). The three genes have been subcloned, yielding fragments of 2.8, 2.7 and

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2.7kb respectively and endoglucanase expression in E. coli was found to be independent of cloning orientation, indicating that transcription was initiated within the DNA insert. The specific activity in E. coli crude extracts was 6–7 units/mg protein for EGA, 3–4 units/mg for EGB and 5–6 units/mg protein for EGC (10, Pétré et al., manuscript in preparation) (one unit of endoglucanase generates one µmole glucose equivalent/hour using CMC as a substrate). In the case of EGA and EGB, 50% and 30% respectively of the activity expressed in E. coli is translocated to the periplasm, the rest of the activity being found in the cytoplasm. In C. thermocellum cultures, total endoglucanase activity reaches 36 units/mg total protein (including cell protein) (10). Since it can be estimated from inhibition by antiEGA antiserum that EGA represents about 50% of this activity (i.e. 18 units/mg), the level of celA expression in E. coli would be about 30–40% of that measured in C. thermocellum. The cela gene was also cloned in both orientations in the E. coliSaccharomyces cerevisiae shuttle vector pG63–11. After transformation of S. cerevisiae, the gene was found to be expressed independently of its orientation at a level of 2 units/mg protein, i.e. 25–30% of that found in E. coli and 11% of that found in C. thermocellum (12). These results indicate that regions controlling celA expression have a remarkably broad specificity. However, comparison with the activity of the purified enzyme (2,000 units/mg protein) (1) indicates that, even in C. thermocellum, EGA hardly accounts for more than 1% of the total protein. Construction of adequate expression plasmids should allow to increase this figure by at least one order of magnitude. 3. PROPERTIES OF CLONED CELLULASES EGB and EGC have been purified from extracts of E. coli bearing appropriate plasmids (11, Pétré et al., manuscript in preparation). Antiserum directed against E. colisynthesized EGB was used to demonstrate that the corresponding protein was indeed secreted by C. thermocellum into the culture medium, where it was identified as a 66,000 dalton polypeptide by the “Western blot” technique (11). Since the molecular weight of E. coli-synthesized EGC is about 38,000, it appears that EGA, EGB and EGC are all different from the Mr=83−94,000 endoglucanase purified from C. thermocellum culture supernatant by Ng and Zeikus (2). EGA, EGB and EGC display different enzymatic specificities toward cellodextrins of various degrees of polymerization. While EGC hydrolyzes cellotriose, cellotetraose and cellopentaose, EGB has no activity toward cellotriose, but hydrolyzes cellotetraose and cellopentaose and EGA reacts with cellopentaose, but only poorly with cellotetraose and not at all with cellotriose (Longin et al., manuscript in preparation). Efficient hydrolysis of crystalline cellulose usually requires the synergic action of endoglucanases and cellobiohydrolases (14,15). The latter enzymes have little or no activity toward CMC (15,16) and cannot be detected using the Congo red test (17). However, methylumbelliferyl-β-cellobioside (18) and p-nitrophenyl-β-cellobioside (19) have recently been described respectively as fluorogenic and chromogenic substrates for cellobiohydrolases, and some of the clones we isolated recently display activity toward these subtrates, but not toward CMC. We are currently checking whether any of the encoded enzymes behaves like a true cellobiohydrolase by analyzing the products of

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hydrolysis of various cellodextrins by HPLC. In addition, studies are under way to find out possible synergistic interactions in the hydrolysis of native cellulose by the enzymes expressed in the various clones. 4. SEQUENCE OF THE CELA GENE The finding that genes from C. thermocellum could be expressed and transported to the periplasmic space in E. coli suggested that sequences controlling gene expression and protein secretion might be conserved between these organisms. A study of the DNA sequence of the celA gene of C. thermocellum (13) indicates that the regions controlling protein secretion and gene expression bear close similarity to the corresponding sequences found in E. coli and B. subtilis. The amino-terminal sequence determined for the mature protein purified from C. thermocellum culture supernatant is preceded by a signal peptide. This peptide displays features similar to those described for other secretory proteins from grampositive bacteria (20). It is rather long (32 aminoacids) and contains 4 basic residues among the first six aminoacids, followed by a stretch of hydrophobic residues. Translation is initiated at a GUG codon, which is preceded by an AGGAGG sequence closely matching the canonical ShineDalgarno sequence complementary to the 3’ end of 16 S RNA (21). With regard to transcription control sites, analysis of C. thermocellum mRNA by Northern blotting and S1 nuclease mapping indicates that transcription is monocistronic and that promoter and termination sites are closely related to those described for E. coli and B. subtilis (P.Béguin, unpublished data). An interesting feature of the deduced aminoacid sequence of EGA is that it contains a reiterated stretch of 23 residues near the carboxy-terminal end, which may be involved in binding two glucose residues of the cellulose molecule. 5. CONCLUSION The multiplicity of cellulases produced by C. thermocellum had already been determined by previous biochemical studies (3). Cloning of separate DNA fragments demonstrated that the various enzymes are indeed coded by different genes and not derived from each other by post-translational modification. It also proved an invaluable tool to separate the endoglucanases physically in order to study their enzymatic properties. In the future, insertion of C. thermocellum genes in expression vectors of E. coli and Bacillus subtilis should allow to produce thermostable cellulases in mass quantities. 6. REFERENCES 1. Pètre, J., Longin, R. & Millet, J. (1981). Biochimie, 63, 629–639. 2. Ng, T.K. & Zeikus, J.G. (1981). Biochem. J., 199, 341–350. 3. Lamed, R., Setter, E. & Bayer, E.A. (1983). Biotechnol. Bioeng. Symp., 13, 161–181. 4. Johnson, E.A., Sakajoh, M., Halliwell, M., Madia, A. & Demain, A.L. (1982). Appl. Environ. Microbiol., 43, 1125–1132. 5. Weimer, P.J. & Zeikus, J.G. (1977). Appl. Environ. Microbiol. 33, 289–297.

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6. Ng, T.K., Weimer, P.J. & Zeikus, J.G. (1977). Arch. Microbiol., 114, 1–7. 7. Cooney, C.L., Wang, D.I.C., Wang, S.D., Gordon, J. & Jimenez, M. (1978). Biotechnol. Bioeng. Symp., 8, 103–144. 8. Cornet, P., Tronik, D., Millet, J. & Aubert, J.-P. (1983). FEMS Microbiol. Letters, 16, 137–141. 9. Teather, R.M. & Wood, P.J. (1982). Appl. Environ. Microbiol., 43, 777–780. 10. Cornet, P., Millet, J., Béguin, P. & Aubert, J.-P. (1983). Bio/Technology, 1, 589–594. 11. Béguin, P., Cornet, P. & Millet, J. (1983). Biochimie 65, 495–500. 12. Sacco, M., Millet, J. & Aubert, J.-P. (1984). Ann. Microbiol. (Inst. Pasteur), 135A, 485–488. 13. Béguin, P., Cornet, P. & Aubert, J.-P. (1985). J. Bacteriol., in press. 14. Bisaria, V.S. & Ghose, T.K. (1981). Enzyme Microbiol. Technol., 3, 90–104. 15. Creuzet, N., Bérenger, J.-F. & Frixon C. (1983). FEMS Microbiol. Letters, 20, 347–350. 16. Bartley, T.D., Murphy-Holland, K. & Eveleigh, D.E. (1984). Anal. Biochem., 140, 157–161. 17. Gilkes, N.R., Langsford, M.L., Kilburn, D.G., Miller, Jr, R.C. & Warren, R.A.J. (1984). J. Biol. Chem., 259, 10455–10459. 18. van Tilbeurgh, H., Claeyssens, M. & de Bruyne, C.K. (1982). FEBS Letters, 149, 152–156. 19. Deshpande, M.V., Eriksson, K.-E. & Pettersson, L.G. (1984). Anal. Biochem., 138, 481–487. 20. Watson, M.E.E. (1984). Nucl. Acids Res., 12, 5145–5164. 21. Stormo, G.D. Schneider, T.D. & Gold, L.M. (1984). Nucl. Acids Res., 10 2971–2996.

NUCLEAR MAGNETIC RESONANCE APPLICATION IN STUDYING THE BIOLOGICAL PRODUCTION OF ETHANOL FROM SUGAR-CONTAINING MEDIA E.TIEZZI, A.LEPRI and S.ULGIATI Department of Chemistry, University of Siena, Italy Summary NMR spectroscopy has shown large application possibility for the study of biological systems. In this paper we present a 13C-NMR spectroscopy application to study fermentative processes of containing-sugar media in order to maximize ethanol production.

1. INTRODUCTION NMR spectroscopy has been extensively used for the study of biological systems, yielding several conformational and structural features as well as the elucidation of interactions between biomacromolecular constituents (1, 2). Morever, the high sensitivity of FT spectrometers has made possible to study low natural abundance and low sensitivity nuclei, such as 13C, 15N, 17O. In particular the combined use of 13C and 31P NMR have allowed the study of metabolic reactions in cellular systems “in vivo”, without interfering with their evolution (3, 4). NMR is in fact a non invasive technique, which allows the observation of metabolic reactions during their occurrence: as a consequence intermediate and final products can be detected and the kinetics of the processes and the ion transport dynamics can be studied (5). A better knowledge of fermentation processes is required for the aim of getting alcohol fuels from ligneo-cellulosic residues and thus of providing for future energetic requirements. Unfortunately 13C-NMR spectroscopy is limited by the low natural abundance of this nucleus (only 1%): this problem can be solved by using selectively 13C-enriched substrates. Such a method makes it possible to follow the metabolic pathway of individual carbon atoms, allowing the elucidation of different pathways and the evaluation of intermediate and final products. In the present investigation we fixed our attention to anaerobic metabolism of sugarcontaining media by a thermophilic bacterium (Clostridium thermocellum, ATCC 27405) fermenting cellulose, cellobiose and glucose and by a mesophilic yeast (Saccharomyces cerevisiae, KL-144A) fermenting glucose with high yields (6).

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In the first case, the mode of growing on glucose of Clostridium thermocellum and the influence of pH on the fermentative process were evaluated; in the second case, the influence of initial glucose concentration was investigated in order to specify the conditions for the hi-ghest yield and fastest kinetics of ethanol production. 2. EXPERIMENTAL 13

C-NMR measurements were performed at 50.288 MHz by using a Varian XL-200 spectrometer, equipped with a 10mm 13C probe. When investigating Clostridium thermocellum 13C spectra were acquired in steps of 20 minutes each (2000 transients); in the case of Saccharomyces cerevisiae the steps were alternatively of 5 minutes (400 scans) or 20 minutes 1800 scans) depending on the concentration of glucose. All 13C NMR spectra were proton noise decoupled. All chemical shifts were referred to tetramethylsilane. The resonances have been assigned on the basis of chemical shifts considerations and on the basis of the known metabolic pathways. Clostridium thermocellum, strain ATCC 27405, was grown at 60°C in a liquid medium containing, per liter, MgSO4.7H2O 0.2g, MnSO.4H2O 0.01g, FeSO4.7H2O 0.01g, p-aminobenzoic acid 0.001g, Biotin 2g, Thiamine. HCl 0.001g, KH2PO4 0.5g, K2HPO4.3H20 0.5g, L-Cysteine.HCl 0.5g. Saccharomyces cerevisiae, strain KL-144A, was grown at 31°C in a liquid medium containing, per liter, yeast exstracts 5g, peptone 10g. The pH was adjusted at the required values with HCl and NaOH. A density of 2.107 cells/ml was used for Clostridium thermocellum inocule; a density of 2.109 cells/ml was used for Saccharomyces cerevisiae inocule. |1−13C|−90% enriched glucose was purchased from Stohler Isotope Chemicals. Strains KL−144A and ATCC−27405 were obtained, respectively, from Dr. P.Valenti, Institute of Microbiology, University of Roma and from Prof. R.Longin, Institut Pasteur, Paris. 3. RESULTS AND DISCUSSION a) Clostridium thermocellum, strain ATCC 27405. The Clostridium thermocellum strain has been inoculated (2ml) into a 5g/l solution of |1−13C| -enriched glucose at pH=7.0. The evolution of the first 9 hours of fermentation was followed with NMR: a slow and continuous decrease of α & ß glucose signals as well as the appearance of a new signal in the frequency range between the glucose anomers are evident. The amount of degraded glucose in the first 9 hours was 15.4% of the initial concentration corresponding to the amount of the observed intermediate. After 9 hours no change was observed any longer, showing that the fermentation stops before producing a valuable amount of ethanol. When three different samples at pH=6.3, 7.0, 8.0 were inoculated with the same amounts of inocule and glucose, the behavior of the fermentation was the same (Fig. 1-a).

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Fig. 1: 13C-NMR spectra obtained on Clostridium therwocellum culture at pH=7 (Fig. 1-a) and pH=8 (Fig. 1-b), respectively. Only two differences could be considered in the sample at pH=8.0 (Fig. 1-b): the intermediate signal intensity decreased in respect of the previously observed values, while another signal appeared at a little higher frequency; moreover, new intense signals were appearing near 62–65ppm, suggesting that the fermentation stopped at a different stage in that case. The resonance observed at 64.71ppm have been assigned to C6 fructose-1,6 biphosphate (5). It has been consequently possible to ascertain, in this particular case, the final point of the cathabolic pathway. Work is in progress for an exact assignment of the other resonances and for the understanding of the reasons why the fermentation stopped. b) Saccharomyces cerevisiae, strain KL-144A. The same amount of yeast (2ml) has been inoculated into samples containing 20g/l (A), 85g/l (B), 200g/l (C), 250g/l (D) and 280g/l (E) of glucose in order to check the influence of the glucose concentration upon the kinetics and the final yield of the process as well as to observe the eventual appearance of inhibitory effects. Tab. n. 1 shows the evolution of the glucose metabolization process in the different samples. After three hours glucose degradation is nearly completed in the first sample, while in the last one only 80% of substrate has been metabolized after 18 hours.

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The comparison between samples C and E suggests that adding 80 g/l results into a degradation time twice longer, suggesting partial inhibition phenomena since the first steps of the fermentation.

TAB. 1 sample\time 3

6

9

12

15

18

A 96.76 100.0 B 38.32 72.45 97.04 100.0 C 29.01 57.51 80.16 100.0 D 15.69 32.66 55.80 72.21 84.63 88.50 E 14.26 31.39 46.73 63.34 76.08 81.26 —Degraded substrate after N hours (%)

TAB. 2 Sample Degraded glucose (g) Required time (hrs) A 16 2.5 B 68 7 C 160 9 D 200 13.5 E 224 17 —Time required for 80% glucose metabolization

Tab. n. 2 shows the situation in the samples when 80% glucose has been metabolized. Analysis of the data yields the metabolization rates of each sample, either in absolute value or in percent of the initial glucose concentration. Samples A and B have the highest metabolization rates, but they degrade a little amount of glucose in absolute value. On the contrary, the sample C degrades 17.8g/hrs, namely it degrades ten times more glucose than sample A in a time only 3.6 times longer, obtaining an high ethanol/degraded substrate rate. These and other data point out that 200g/l is the most suitable concentration of ethanol with a high degradation rate, a high conversion coefficient and in a short time, suggesting that the enzymatic system of the used strain reached the maximum of its activity. 4. REFERENCES 1) D.G.Gadian, “NMR and its applications to living systems”, Clarendon Press, Oxford (1982); 2) R.G.Shulman, “Biological applications of magnetic resonance”, Accademic Press, New York (1979); 3) J.den Hollander, K.Ugurbil, T.R.Brown and R.G.Shulman, “Phosphorus 31 NMR studies of the effect of oxigen upon glycolysis in yeasts”., Biochemistry, 20, 5871–5880 (1981); 4) R.G.Shulman, T.R.Brown, K.Ugurbil, S.Ogawa. S.M.Cohen and J.A. den Hollander, “Cellular application of 31P and 13C NMR”, Science, 205, 160–166 (1979); 5) T.Ogino, J.A.den Hollander and R.G.Shulman, “39K, 23Na and P NMR studies of ion transport in Saccharomyces cerevisiae”, Proc. Natl. Acad. Sci. USA, 80, 5185–5189 (1983);

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6) J.A.den Hollander, T.R.Brown, K.Ugurbil, and R.G.Shulman, “13C-NMR studies of anaerobic glycolysis in suspensions of yeast cells”, Proc. Natl. Acad. Sci. USA, 76, 6096–6100 (1979); 7) J.A.den Hollander and R.G. Shulman, “13C-NMR studies of in vivo kinetic rates of metabolic processes”, Tetrahedron, vol. 39 N. 21, 3529–3538 (1983), Pergamon Press Ltd. London.

BASIC TRIALS TO CO-IMMOBILIZE ALGAE AND YEAST FOR THE PRODUCTION OF ETHANOL I.MÜCKE and W.HARTMEIER Institute of Microbiology, RWTH Aachen, Worringer Weg, 5100 Aachen, Germany SUMMARY Six alga-strains (5 symbiotic and 1 free living) were investigated for excretion of fermentable sugars. Characterization of one strain, see-ming worth to be coimmobilized with a yeast to enable ethanol formation from sun light and carbon dioxide, is given. The influence of the yeast on excretion was investigated by an enzyme system (glucoamylase and glucose oxidase).

1. Introduction In the last decade, two depressions in oil supply led to a lasting shock in the world’s economy. In these years, strengthened search for alternative energy sources, namely by means of biotechnology, has been started in many laboratories all over the world. Using sun light as energy for heat winning the production of ethanol from cheap raw materials or the cultivation of special energy crops are some major projects in this area. The final goal of our investigation is to enable ethanol formation from sun light and carbon dioxide by means of an immobilized system comprising sugar synthesising algae and yeast cells fermenting the sugar to ethanol. 2. MATERIALS AND METHODS Organisms Besides mesophyll cells of BETA VULGARIS above all symbiotic algae, noted for transporting C-sources to their hosts in symbiosis, were investigated. The strains, which were examined, are listed in table 1.

Table 1: Algae examined in this investigation. Species

Strain

Type resp. source of selection

CHLORELLA FUSCA 211–8b* free living alga CHLORELLA SACCHAROPHILA 3.80* phycobiont from TRAPELIA COARCTATA CHLORELLA SOROKINIANA 211–40C* endosymbiont from SPONGILLA FLUVIATILIS CHLORELLA SPECIES 211–6* endosymbiont from PARAMECIUM BURSARIA

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CHLORELLA SPECIES 241.80* endosymbiont from PARAMECIUM BURSARIA CHLORELLA SPECIES Pbi+ endosymbiont from PARAMECIUM BURSARIA * obtained from Deutsche Sammlung fur Algenkulturen, D-3400 Göttingen + obtained from Dr. W.Reisser, University of Marburg, D-3550 Marburg

Analytical methods The first tests of fermentable sugars were made by thin-layer chromatography on silica gel or gelchromatography on Bio-Gel P2 (Bio-Rad). Quantitation of produced sugars were carried out by HPLC (Waters ALC 200) on the strong cation exchange resin Aminex HPX-87H (Bio-Rad) with a precolumn Aminex Q-150 S (Bio-Rad). The same column was used to quantitate acids. Photosynthesis Photosynthetic behaviour was followed by measuring the oxygen evolved with a CLARK-type oxygen electrode. Medium was the same as used for the determination of the excretion rates without a N=source (equimolar KCL for KNO3). Further conditions were: 25°C, pH 7, 1×107 cells/ml, 0.015M NaHCO3, 11000 lux ( 10.6nE/cm2·s; 4 Osram L 18W/25). Growth and excretion Growth and excretion measurements were carried out in a KNIESE-apparatus under 9.5nE/cm2.s; 5 Osram L 36W/25 following conditions: 25°C, 2% CO2, 10000 lux ( and 1 Osram Fluora 40W/77), 50 ml tubes with 30 ml medium. Growth medium was as given by KUHL (1962) enriched with 1g proteose-pepton, 500µg vitamin B1 and 5µg vitamin B12 per litre. Sugar excretion was investigated in the same medium, but 0.01M citrate buffer was used instead of phosphate buffer. To prevent shifting of the pH-value during photosynthesis, nitrate was substituted by urea as N-source. In the case of the algae-yeast coimmobilizate modelling system using glucoamylase and glucose -oxidase instead of the yeast the trials were carried out in 550ml tubes with 360ml KUHL-medium with nitrate as N-source and under pH-control. 3. RESULTS With the exception of CHLORELLA FUSCA 211–8b, all algae tested were able to excrete measurable amounts of sugar (see table 2). The amount of sugar excreted being highest with the CHLORELLA strains from PARAMECIUM. These three strains were selected for further trials. At last, CHLORELLA SPEC. 241.80 has been chosen for detailed investigation. Species Strain Sugar excreted CHLORELLA FUSCA 211–8b none CHLORELLA SACCHAROPHILA 3.80 traces of glucose CHLORELLA SOROKINIANA 211–40C traces of glucose CHLORELLA SPECIES 211–6 glucose, maltose, maltotriose, maltotetraose

Basic trials to co-immobilize algae and yeast for the production of ethanol

CHLORELLA SPECIES CHLORELLA SPECIES BETA VULGARIS

241.80 Pbi

739

glucose, maltose, maltotriose, maltotetraose glucose, maltose, maltotriose, maltotetraose traces of saccharose

Table 2: Sugar excreted by organisms tested. growth >pH5 maximal division rate (d−1) a. in urea-medium, pH 6 2.3 b. in nitrate-medium pH 6 (at the beginning) 2.2 maximal photosynthetic acti vity (measured as oxygen evo lution) pH 6.7–7 >11000 lux >15 mM NaHCO3 25°C best excretion conditions 25°C in N-free medium pH 5.5 in urea medium pH 6 heterotroph growth on glucose, saccharose galactose, glycerin

Table 3: Properties of strain 241.80 Table 3 shows some properties of the examined symbiotic alga strain 241.80. Excretion of sugars Figure 1 gives an example for sugar excretion by strain 241.80 in long time cultivation at pH 6 in urea containing medium.

Fig.1: Excretion of sugars by CHLORELLA SPEC. at pH 6 (

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glucose; maltose: total sugar)

maltotriose;

The sugar excretion proceeded up to a maximal concentration of nearly 2% in the culture medium. In the early phase, maltose was by far the main product of excretion. Approximating to a maximal value in the culture broth also considerable amounts of glucose and maltotriose appeared. The growth of the alga as well as the excretion of sugars were considerably influenced by the pH-value of the medium, by the type and ionic strength of buffer and by the nitrogen source. Figure 2 shows the pH-dependence of sugar excretion as maximal maltose excretion per day and table 4 gives the influence of the nitrogen source on excretion.

Fig.2: pH-dependence of daily maltose excretion rates of CHLORELLA SPEC. 241.80. Table 4: Relative sugar excretion rates in dependence of the nitrogen source Nitrogen source Relative excretion rates of maltose Ammonia Nitrate Urea

0.90 1.62 1.00

The best maltose excretion rates in the beginning of cultivation were 2.2g/l.d using nitrogen free medium. With nitrogen containing media only up to 1.3g/l.d were obtained in the beginning phase. This was due to increased growth of the cells which prevented the

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sugars assimilated from being excreted. After some days of cultivation the sugar excretion became very similar whether or not a nitrogen source was added. In long term experiments of more than 10 days nitrogen supplementation was necessary. Nitrate was found to be the best nitrogen source with regard to sugar excretion (see table 4). With increasing maltose concentration in the culture broth the excretion of further maltose showed a saturation behaviour (see figure 1). We succeeded in reducing this product inhibition by additional application of glucoamylase and glucose oxidase. Thus, maltose and other oligomers were hydrolized to glucose by the amyloglucosidase and subsequently converted to gluconic acid by the glucose oxidase. The system of algae with additional enzymes (figure 3) can be regarded as a model of the algae/yeast coimmobilizate envisaged for forthcoming investigations.

Fig. 3: Product formation with algae 4. CONCLUSIONS The alga strain found excretes fermentable sugars in an amount seeming worth to be coimmobilized with fermenting yeast, so that a system for ethanol formation from sun light and carbon dioxide could be achieved. REFERENCES KUHL, A. (1962) in: Dtsche Bot. Ges. (Hrsg.), Beiträge zur Physiologie und Morphologie der Algen, 157–166; Verlag Fischer, Stuttgart. CERNICHIARI, E., MUSCATINE, L. and SMITH, D.C. (1969): Maltose excretion by the symbiotic alga of HYDRA VIRIDIS.—Proc. Roy. Soc. B 173, 557–576.

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ZIESENISS, E. (1982): CHLORELLA Symbiose spezifische Synthese und Exkretion von Maltose durch CHLORELLA spec. aus PARAMECIUM BURSARIA.—Dissertation, Göttingen. ZIESENISS, E., REISSER, W. and WIESSNER, W. (1981): Evidence of de novo synthesis of maltose by the endosymbiotic CHLORELLA from PARAMECIUM BURSARIA.—Planta 153, 481–485. HARTMEIER, W., MÜCKE, I. and DÖPPNER, T. (1984): New approaches to produce base materials by means of biotechnology.—3. ECB München 1984, Vol II 503–510; Verlag Chemie, Weinheim 1984.

ACKNOWLEDGEMENT This research was carried out under Research Contract no. GBI-004-D (D) of the Biomolecular Engineering Program of the Comission of the European Communities.

ETHANOL FROM UNCONVENTIONAL SUBSTRATES USING YEAST COIMMOBILIZED WITH NON-YEAST GLYCOSIDASES W.HARTMEIER, U.FÖRSTER AND C.GIANI Institute of Microbiology, Technische Hochschule Aachen, D-5100 Aachen (Fed. Rep. Germany) Summary A new procedure to bind non-yeast enzymes closely around living yeast cells is described and characteristics of the co-immobilizates thus created are given. Using these biocatalysts in packed bed reactors unconventional substrates (e.g. lactose and cellobiose) could be continuously converted to ethanol. The half life of the co-immobilized biocatalysts was about three weeks.

1. Introduction Recent developments allow to combine living cells with enzymes from other cells by means of co-immobilization (Hahn-Hägerdal, 1983; Hartmeier, 1983). Thus, yeast cells can be enabled to ferment substrates being normally not metabolizable for these yeasts. A preferred method of co-immobilization comprises binding non-yeast enzymes to alginate and subsequent entrapping of the yeast cells with the enzyme-coupled alginate (Hägerdal and Mosbach, 1980). Typical beads of such co-immobilizates have a diameter of one to several millimeters. As an alternative to that method, we now evaluated a procedure leading to single yeast cells with additional enzymes bound closely to the cell walls. Coimmobilization of Saccharomyces cerevisiae with β-galactosidase and ß-glucosidase as non-yeast glycosidases are shown in this paper. 2. Method of Coimmobilization Yeast cells were coimmobilized with β-galactosidase from A. oryzae and with βglucosidase (cellobiase) from A. niqer according to the method schematically shown in figure 1. The yeast cells must be cautiously predried. Rehydration of these cells in an enzyme solution leads to sucking up the enzyme protein onto the cell surfaces where it gets fixed and crosslinked by the addition of tannine and glutaraldehyde.

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Fig. 1: Co-immobilization of yeast cells and additional enzymes. More details of the method to bind β-glucosidase and ß-galactosidase to yeast cells are given elsewhere (Hartmeier, 1981; Jankovic and Hartmeier, 1982). Further entrapment of the biocatalysts into alginate matrices has been carried out in certain cases. 3. Results 3.1 Characteristics of the Coimmobilizates The enzyme envelop around the cells can be made visible by using enzyme antibodies coupled with fluorescein. Figure 2 shows a mixture of yeast cells with and witout additionally bound enzymes; on the right side of this figure the bound enzymes are to be seen by their fluorescence.

Fig. 2: Native and enzyme-entrapped cells after addition of enzymeantibodies coupled with fluorescein.

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Table 1 illustrates that the viability and binding efficiency of the coimmobilized systems are considerably different from biocatalyst to biocatalyst. There is even a major influence of the specific strain of microorganism on these parameters, so that the data given in table 1 are only selected examples. Using six different strain of S. cerevisiae we found that the viability was between 20 and 93% and the remaining amyloglucosidase activity ranged between 5 and 19%.

Table 1. Viability and binding efficiency of different yeast/enzyme co-immobilizates. Yeast species

Non-yeast enzyme coimmobilized

S. cerevisiae amyloglucosidase S. cerevisiae β-glucosidase S. cerevisiae β-galactosidase

Enzyme source Rh. niveus A. niqer A. oryzae

Cell viability 90% 60% 70%

Binding efficiency 13% 50% 70%

3.2 Lactose Fermentation Figure 3 shows that the fermentation rate of the enzyme coated cells is considerably higher than the fermentation rate of the same biocatalysts additionally entrapped into alginate beads of 4 mm diameter.

Fig. 3: Batch fermentation of lactose in a stirred tank with free and alginateentrapped co-immobilizate.

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Fig. 4: Continuous lactose fermentation in a packed bed reactor. 4% lactose, pH 5, 30°C. A disadvantage of repeated batch fermentations using the enzyme-entrapped yeast cells freely suspended in the fermentation broth is a rapid decrease in β-galactosidase activity due to budding and shearing effects (Hartmeier et al., 1984). Applying the cell/enzyme co-immobilizates in a packed bed equipment this problem has been overcome. Thus, volumetric productivities of up to 10g/l·h and dilution rates up to D= 1h were obtained under complete use of the glucose set free from the lactose (see figure 4). Galactose remained unused due to catabolite repression. The half life of the system was about three weeks. 3.3 Cellobiose Fermentation Cellulose, a major component of plant material, is available in large and renewable quantities. Therefore, utilization of cellulosic material has gained much interest. However, cellulose being destined to be a durable structure constituent of plants its breakdown to oligosaccharides and glucose is rather difficult. Enzymatic hydrolysis of cellulose is considerably inhibited by its own intermediates and namely by the end product glucose. The main purpose of this investigation was to find out if coimmobilization of the ß-glucosidase with yeast cells could increase the reaction rate of cellobiose hydrolysis as last step of cellulose breakdown. Figure 5 demonstrates that, indeed, a considerable improvement of cellobiose degradation occurs when yeast is applied in addition to the β-glucosidase.

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Fig. 5: Cellobiose degradation with βglucosidase alone and with yeast coimmobilized with β-glucosidase. From figure 6 it can be derived that, depending on the amount of coimmobilizate applied, more or less quantitative conversion of the cellobiose to ethanol can be achieved. The hydrolysis of cellobiose to glucose and its conversion to ethanol is only the last step of cellulose breakdown. In order to convert nonsoluble cellulose to ethanol further procedures must be integrated into the process. Such a process could perhaps use the combined action of soluble cellulase in a membrane reactor and subsequent fermentation of the oligo- and disaccharides in a packed bed containing yeast/ß-glucosi-dase coimmobilizate.

Fig. 6: Continuous cellobiose fermentation with co-immobilizate.

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4. Conclusions Non-yeast glycosidases can be bound to yeast cells so that the substrate range of the yeast cells is enlarged. A realistic estimation whether or not co-immobilized yeast/enzyme systems are economically feasible is not yet possible. This new group of biocatalysts should be submitted to further investigation, since it sometimes opens new possibilities of synergistic action which cannot be obtained in the same extent by separately immobilized cells and enzymes. 5. References Hägerdal B, Mosbach K (1980) The production of ethanol from cellobiose using baker’s yeast coimmobilized with ß-glucosidase. In: Linko and Larinkari (eds), Food process engineering vol 2; Applied Science Publishers, London, pp 129–132. Hahn-Hägerdal B (1983) Co-immobilization involving cells, organelles and enzymes. In: Mattiasson (ed), Immobilized cells and organelles vol 2; CRC-Press, Boca Raton, pp 79–94. Hartmeier W (1981) Basic trials on the conversion of cellulosic material to ethanol using yeast coimmobilized with cellulolytic enzymes. In: Moo-Young (ed), Advances in biotechnology vol 2; Pergamon Press, Toronto, pp 377–382. Hartmeier W (1983) Preparation, properties and possible application of coimmobilized biocatalysts. In: Lafferty (ed), Enzyme technology; Springer-Verlag, Berlin, pp 206–217. Hartmeier W, Jankovic E D, Förster U, Tramm-Werner S (1984) Ethanol formation from lactose using yeast and bacterial cells co-immobilized with β-galactosidase. In: Biotech Europe 84; Online Publications, Pinner, pp 415–426. Jankovic E D, Hartmeier W (1982) Lactosevergärende Coimmobilisate aus Hefezellen und Schimmelpilzlactase, deren Herstellung und Charakteristika. In: Dellweg (ed), 5. Symposium Technische Mikrobiologie; Verlag VLSF, Berlin, pp 377–384.

Acknowledgement This research was carried out under contract no. GBI-004-D (B) of the Biomolecular Engineering Program of the Commission of the European Communities.

ETHANOL FROM PENTOSES AND PENTOSANS BY THERMOPHILIC AND MESOPHILIC MICROORGANISMS J.Wiegel* and J.Puls** *University of Georgia, Department of Microbiology, Athens Georgia 30602 USA **Institute of Wood Chemistry and Chemical Technology of Wood D-2050 Hamburg 80, Federal Republic of Germany Summary The conversion of xylans and xylooligomers from wood and annual plants to ethanol by thermophilic and mesophilic anaerobic bacteria is discussed. Although all of the investigated organisms reveal xylanolytic activity, ethanol production could be accelerated by prehydrolysis of the xylans during sterilization.

1. Introduction Processes have been developed to convert the carbohydrate portion of lignocelluloses into feedstock chemicals like ethanol. Before a microbial conversion the necessary liberation of the carbohydrates is performed by acid or enzymatic hydrolysis. Acid hydrolysis processes suffer from their low yields due to destruction of carbohydrates. Additionally the formation of degradation products raises severe problems for the following fermentation. Enzymatic hydrolysis needs a pretreatment to make the lignified cell wall accessible to enzymatic attack. Pretreatment can be performed by steaming at temperatures between 170 to 230°C. This treatment offers the advantage of hemicellulose separation. The steaming-extraction process has been described previously in detail (1, 2). Here we report studies on the bioconversion of the hemicellulose fraction obtained from wood by water extraction after steaming. The yeasts used in industrial production of ethanol cannot directly utilize xylose, xylans or cellulose to a significant degree. Also the mesophilic bacterium, Zymomonas mobilis, cannot ferment these substrates to ethanol? however, it has production rates above 250g ethanol per liter and hour when fermenting glucose (3). During the last years several fungi and yeasts have been described which can utilize pentoses, specially xylose after conversion to xylulose. Most yeasts, however, produce high amounts of xylitol or significant amounts of glycerol as byproducts, thus reducing the yield of ethanol. The conversion of xylose to ethanol has been extensively reviewed by Gong (4). The best yeast for the pentose conversion to ethanol seems to be Pachysolen tannophilus (5). However, the conversion rates are low, and the ethanol per xylose yields

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are not optimal. In general, if the process of ethanol production is to be economically feasible, the organisms have to convert directly pentoses, especially xylose to ethanol without the external addition of xylose isomerase. Wiegel (6) and Zeikus (7) have pointed out that thermophilic bacteria are potentially superior to mesophilic bacteria or yeasts for fermentation. In contrast to most yeasts many of these bacteria can use a wide range of substrates, including pentoses and hexoses. In addition they normally produce low amounts of biomass which decreases the amount of waste by-products and increases the yield of the fermentation product. 2. Steaming-Extraction Process The effect of steaming temperature on the chemical composition of the hemicellulose fraction is presented in Table 1. Both the xylose and total carbohydrate concentration in the extract increased with increasing temperature between 170°C and 200°C. However, raising the temperature to 210°C led to a substantial decomposition of xylose, which was reflected in the carbohydrate yield. Acid liberation caused a decrease in the pH of the extracts. Monomeric sugars comprised only a minor part of the total carbohydrates. After steaming at 170°C only 2% of the total xylose was obtained in monomeric form. The proportion of free xylose in the extract increased markedly only at 210°C. At this temperature is comprised about 28% of the total xylose-containing carbohydrates. Surprisingly steaming conditions had only little effect on the acetyl-substituents. Whereas 7 of 10 xylose units are substituted by acetyl side groups in the case of natural birchwood xylans, every 2nd xylose units remains substituted after steaming. The 4–0methylglucuronic acid side groups, however, are not so stable under steaming conditions. The uronic acid content is reduced from 0, 1 per xylose unit (natural xylans) to 0.01 (210°C steaming temperature). 3. Fermentations Thermophilic anaerobic bacteria have also been selected for hemicellulose transformation into ethanol because of their hydrolytic capacity. A differential utilization of the steaming extract by several thermophilic bacteria was determind. Clostridium thermocellum (60°C) first utilized the high molecular weight fractions. Xylose and xylooligomers were accumulated. In contrast to this, Clostridium thermohydrosulfuricum (70°C) utilized xylose first and then xylooligomers with n= 2 to 5 but oligomers with n greater than 6 were only slowly utilized. Thermoanaerobacter ethanolicus (70°C) utilized xylose preferentially. Xylooligomers with n=2 to 5 and n=6 and greater were apparently concomitantly utilized without significant differences. In contrast to C. thermooellum the other organisms grew during xylan hydrolysis producing ethanol, lactate, acetate, CO2, and H2. However, before the organisms really started to produce ethanol they needed a considerable time to create hy-drolytic enzymes. Sterilization in the presence of 100 mM phosphoric acid led to a mild prehydrolysis of oligomers and polymers. The resulting low molecular products were readily fermented to ethanol (Fig. 1).

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With T. ethanolicus substrate concentrations of 1% and conversion ratios of 1,4 mol ethanol per mol xylose used have been obtained. A mutant was derived which could utilize xylose at concentrations of up to 4% (w/v) which produced in continuous culture under cell recycling maximal 3 g ethanol per liter and hour from xylose. But the production rate from hemicellulose preparations did not exceed 1 g ethanol per liter and hour. The production rates of other mesophilic organisms are in the same range, however, the conversion ratios (ethanol:xylose) are lower. An advantage of T. ethanolicus is its simultaneous utilization of pentoses and hexoses. From a comparison of the known organisms, however, none of them is really superior over the others, so that an economic process on ethanol from pentoses could not be started yet. Since the fermentation capacity of the relevant organisms is not yet fully exhausted more basic work has to be carried out. Acknowledgement This research was financed by BMFT, project no. PLRC-98. 4. Literature 1. Dietrichs, H.H., Sinner, M., and Puls, J. (1978). Potential of steaming hardwood and straw for food and feed production. Holzforschung 32:193–199. 2. Wiegel, J. and Puls, J. (1983). Production of ethanol from hemicelluloses of hardwoods and annual plants. In: Energy from Biomass, 2nd E.C. Conference. Appl. Sci. Publ. London New York: 863–867. 3. Eveleigh, D. (1983). Biofuels from natural polymers. Proceedings of 3rd Int. Symp. on Microbial Ecology. East Lansing. 4. Gong, Ch.-S. (1983). Recent advances in D-xylose conversion by yeast. In: Annual reports on fermentation processes. Vol. 6 Chapter 10. Academic Press, Inc. New York-London. 5. Maleszka, R., Veliky I.A., Schneider, H. (1981). Enhanced rate of ethanol production from xylose using recycled or immobilized cells of pachysolen tannophilus. Biotechnol. Lett. 3:415– 420. 6. Wiegel, J. (1980). Formation of ethanol by bacteria. Experientia 36:1434–1446. 7. Zeikus, J.G. (1980). Chemical and fuel production by anaerobic bacteria. Ann. Rev. Microbiol. 34:423–464.

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Utilization of Xylooligomers obtained after Steaming Birchwood at 190°C for 10 min by anaerobic thermophilic Bacteria. Chromatographic Separation on Biogel P 4 and Fractogel TSK HW 50 (100×2, 5cm each).

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Chemical characteristics of the hemicellulose fraction of birchwood after steaming for 10 minutes at different temperatures (expressed as % of extract dry weight) Steaming pH Xylose Total carbohydrates 0-Acetyl 4-0-M-L-Glua temp, °C 1) 2) 1) 2) 3) 3) 170 4.3 38.5 0.9 58.4 180 3.8 51.3 1.5 60.8 190 3.6 53.2 4.0 64.9 200 3.6 54.5 5.9 66.4 210 3.5 48.0 13.2 58.7 1) after total acid hydrolysis 2) as monomeric sugars after steaming 3) per xylose units

10.4 6.5 10.8 12.3 22.5

6.5 0.6 8.5 0.58 8.7 0.57 7.8 0.5 7.2 0.53

3.8 3.3 1.9 1.5 0.7

0.07 0.05 0.03 0.02 0.01

RAPID DETERMINATION OF YEAST CONCENTRATION IN FERMENTATION BROTHS H.Niebelschütz and C.Boelcke Institut für Gärungsgewerbe und Biotechnologie and Technical University Berlin, Seestr. 13, D-1000 Berlin 65 Summary A novel method for estimations of biomass concentrations in fermentation broths is proposed. A rapid and simple calculation of biomass is possible from differences in electrical conductivities between fermentation sample? and correspondent supernatants in yeast concentration ranges from 10 to 150kg DW/m3 . Furthermore this presented method gives satisfactory results in processes with different microorganisms and also synthetic and technical media.

1. Introduction Computer-coupling of fermentation processes requires a direct determination of different process parameters, like substrates, products and biomass concentrations. An indirect estimation for biomass concentration is possible from mass balancing techniques, but application of these methods demand complex technical equipments and in addition, some very important assumptions about the stoichiometric relationships. Even measurements of optical density for biomass determination refuse in yeast processes with complex substrates. This presented method of measuring electrical conductivities in fermentation samples overcomes the mentioned difficulties for biomass estimation. 2. Materials and methods Electrical conductivities in biosuspensions and correspondent supernatants were measured with an electrical conductometer (Type PW 9501, electrode PR 9514, Philips Ltd.) at constant temperatures. Control measurements of biomass concentrations (Xexp) were carried out by normal analytical method, centrifuge, wash and dry. Biomass estimations were performed with different microorganisms and various process strategies as shown in Table 1.

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3. Results Microorganisms show a considerable influence on ionmovement in aqueous solutions: an increase in cell concentration exhibits a decrease in electrical conductivity. This effect is shown in Figure 1 for experimental data of Saccharomyces cerevisiae in different media, where a dimensionless electrical conductivity is plotted vs. cell concentration. From this linear relationship one obtains for calculation of biomass data the following equation

with χ and χ0 equal electrical conductivities of biosuspensions and correspondent supernatants. Figure 2 shows results of biomass determinations from yeast fermentation with molasses (III), where experimental data (Xexp,○) and calculated values (Xcal, ●) are plotted vs. fermentation time. Comparison of experimental (Xexp) and calculated (Xcal) biomass data for different termentation processes with Saccharomyces cerevisiae and furthermore with Candida utilis is shown in Figure 3. 4. Conclusions – rapid method for biomass determination with satisfactory accuracy (±15%) for 10<X<150 kg DW/m3 – simple technical equipment – no further informations required (substrate and product concentrations) – applicable for different fermentation processes – suitable for different microorganisms – insensitive to presence of inert particles (complex technical substrates) – on-line measurement and computer control easy to realize (see Figure 4)

Table 1 Organisms and media used organisms

yeast fermentation molasses synthetic medium

ethanol fermentation molasses

Saccharo- ceervisiae (10–300 1) III I III Candida utilis (10–300 1) II Medium composition [k kg/m3] I 14.3 (NH4)2 S O4; 2.3 (NH4)H2 PO4; 1.3 MgSO4* 7H 2O; 0.06 (NH4)2 Fe(SO4)2* 6 H2O II 80 Glc.; 20.4 (NH4)2SO4; 1.2 KH2PO4; 1.6K2HPO4; 1.2 MgSO4* 7H2O; 0.1 NaCl; 0.01 trace element solution III Molasses, final dilution 1:10

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Figure 1: Influence of cell mass on electrical conductivity

Figure 2: Fermentation curve of Sacch. cer. on molasses

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Figure 3: Comparison of experimental and calculated biomass concentrations

Figure 4: Computer coupling for direct biomass determination

UTILIZATION OF BAMBOO FOR THE PRODUCTION OF ETHANOL T.J.B.de MENEZES; C.L.M.dos SANTOS and A.AZZINI Instituto de Tecnologia de Alimentos—ITAL Summary Bamboo carbohydrates were saccharified with commercial amylolytic enzymes, and a cellulolytic broth obtained by submerged cultivation of a cellulolytic fungi. The reducing sugars released by this hidrolysis were fermented using Saccharomyces cerevisae, obtaining 160ml of ethanol per kg of bamboo, corresponding to a fermentation efficiency of 85% of the theoretical value. Although the addition of the fungal broth increased the hydrolysis efficiency, yielding a higher reducing sugar content, the majority of the bamboo components such as cellulose, pentosans and lignin, were only partially solubilised. The alcohol efficiency for the fermentation of cooked and noncooked mashes was about 85%.

1. INTRODUCTION Within the Graminae family a fibrous plant known as bamboo comprises 45 genera and several especies scattered all over the world. The majority of the epecies occur naturally, under a wide variety of climatic conditions and types of soil in the Continent of Asia. It is also found naturaly in Japan, Thailand, China and in some African countries. In South America, in the northern region of Brazil, bamboo also frequently occurs naturally. The utilization of this source of biomass for the production of ethanol could be considered as an interesting alternative to other raw-materials, mainly as a substitute for wood, showing some advantages in relation to the latter such as having a higher crop productivity, higher carbohydrate yield and lower lignin content. B. vulgaris, harvested at 3-yearly intervals in Trinidad, showed productivity values of 20t/ha/year of dry stems (1). In Brazil, after 4–5 years of cultivation of B.tulda production values of 90 to 120 t/ha on a wet basis have been reported (2). Most bamboo species grow very rapidly longitudinally, reaching maximum development within a few months. A growth of 120cm within 24 h. has benn reported for the bamboo species P.bambusoides (3). Furthermore, due to its extensive radicular system, bamboo can be cultivated in lands where the topography is uneven, wich are otherwise unadaptable for technological agriculture, releasing the fertile areas for food crop cultivation. After cutting, there is no need to replant the bamboo, since it produces new shoots very easily, resulting in economy of energy an labor. In order to make the utilization of this plant feasible achieving high alcohol yield, in addition to the high crop yield of the raw-material, it is necessary to maximise the carbohydrate conversion. For this an efficient carbohydrase system must be available, and a process for the complete conversion of these carbohydrates should be developed.

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2. MATERIAL AND METHODS The fungal cultures used for the production of the cellulolytic enzymes and xylanase were Basiodiomycete 50 F (4) and Rhisopus (5). Saccharomyces cerevisae was used to induce the alcoholic fermentation. The enzymes were prepared by submerged cultivation or using a mold bram process described previously (6). The enzymic fractions C1, Cx and β-glucosidase were determined using the methods of Mandels and Weber (7). One C1 unit is defined as the milligrams glucose produced per mililiter after 24 h. One Cx unit is defined as that releasing 1.0 umol glucose/min. One salicin β-glucosidase unit is defined as that releasing 1 umol glucose/min. The xylanase activity was determined by adding lml of enzyme solution to 2.5ml of 1% larchwood xylan solution and 2.5ml acetate buffer (pH 4.0), and incubating at 50°C for 15 min. One xylanase unit is defined as that amount of enzyme producing lmg of xylose in 15 min. The bamboo used in the experiment had grow for three years, its typical composition being showun in TABLE 1. Starch determinations were performed using the AOAC methods (8), pentosans by the Peter, Thaler and Taufel method (9) and the cellulose, lignin and ash by the trigol activited method (10).

TABLE I. Composition of bamboo. Components g/100g drymatter Starch Cellulose Pentosans Lignin Ash

33 35 17 12 3

The bamboo stalks were chopped into small pieces and the dried chips, containing about 7–10% moisture, were ground in a hammer mill with 0.5mm screen. Water was added to the powder to obtain 15 to 20% of solids, and about 1,250g of the resulting slurry cooked for 30 min under a high presure in a 2.0 liter PARR Presure Reaction apparatus. The resulting cooked and noncooked slurries were saccharified with commercial α-amylase and glucoamylase and in some trials the cellulolytic broth was also added as describe alsewhere (6). Samples were taken periodically and assayed for reducing sugar as glucose by the DNS method. The rate of saccharification was estimated by the reducing sugar produced in the course of conversion. The percent saccharification was expressed as the amount of reducing sugar produced from 100g of carbohydrate. Cooking and gelatinization were also performed in a 30 liter reator with a 16 liter working volume. The conditions for cooking and gelatinization were the some as before. A three vessel fermenter, each vessel with a capacity of 7.5 liters and a working volume of 4.5 liters was used for the fermentation of the hydrolysates. Temperature and agitation controls were also provided. The noncooked but gelatinized slurry from the 30 liter fermenter was distribuited between the three vessels after the addition of the glucoamylase. Fungal broth enzymes, yeast inoculum, and nitrogen, potassium and magnesium salts were added to one of the vessels. A second, which received only the fungal broth, served as a control for the

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evaluation of the sugar released. In the third vessel, sterilized distilled water replaced the fungal broth, and yeast inoculum and served to evaluate the cellulose and pentosans digesting enzymes. Using a 30 liter fermenter, fermentation was also induced in a slurry previously cooked at 121°C and subsequently saccharified for 48 hours. During the course of fermentation the ethanol content of the sample was determined from the specific gravity of the destillate and the reducing sugar produced, which was determined by the DNS method (11). After fermentation, the contents of the fermenter were removed and filtered. The recovered solids were washed, filtered and dried to constant weight, and then used for starch (8), cellulose (10) and pentosan (9) determinations. The loss of weight was calculated from the difference between these values and the initial values, and expresses the carbohydrate digestion. 3. RESULTS AND DISCUSSION In spite of the fact the addition of a misture of cellulose and hemicellulose degrading enzymes increased the rate of sugar formation in the noncooked slurry (FIGURE 1), the conversion of carbohydrates was not complete. The feasibility of alcohol production from starchy and cellulosic raw-material is dependent on the optimization of the liquefaction and saccharification steps. As shown in Figures 2 and 3 the higher the cooking temperature, the higher the rate of sugar formation, the rate being higher when a mixture of cellulolytic and hemicellulolytic enzymes were added. The higher values of reducing sugar at the end of saccharification, obtained when lower cooking temperatures were used, can be explained by enzyme impurities in the broth or in the commercial preparations. Since the hydrolysis of cellulose is inhibited by its product a better utilization of the carbohydrate would occur if fermentation were induced simultaneously with hydrolysis. TABLE 2, shows that the addition of enzyme extract increased the carbohydrate conversion as compared to the non addition of the extract. The higher consumption of starch by the enzyme contributed to the release of starch granules, which are bound to the lignocellulose complex of bamboo. It is interesting to note that in the sample which received only amylolytic enzymes (FIGURE 1 and TABLE 2) the other components were also reduced which can be explanained by the partial solubilization of the cellulose and pentosans and the incompleted autohydrolysis on account of the exposure of the lignocellulosic material to saturated steam (12). TABLE 2 shows that the production of ethanol in the noncooked slurry saccharified simultaneously with the fermentation was 10.3g/l, and the fermentation efficiency was 66% of the theoretical value after 70 hr. However, after 20 hr. of fermentation the production of ethanol reached 11.8g per liter corresponding to an efficiency of 86%. The maximum production was achieved after 27 hours with 12.6g of ethanol per liter of wine, wich corresponds to 100ml of ethanol per kg of bamboo. Fermentation after hidrolysis produces higher ethanol yields with the cooked slurry than with the noncooked slurry. With the noncooked slurry, 100ml ethanol were produced per kg of bamboo, whereas with the cooked slurry 160ml of ethanol were produced per kg of raw material.

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FIGURES 1, 2 and 3. Effect of cooking temperature and fungal broth on the rate of saccharification of bamboo slurry.

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Although the carbohydrate conversion did not reach its maximum potential, the hydrolysis efficiency could be increased by optimization of the cooking conditions, which could favour the action of the amylolitic and cellulolytic enzymes. The yield in ethanol can also be improved by recycling the residue to the reactor, in other to undergo a second enzymic treatment. Thus there are a number of possibilities that can be investigated in order to optmize the utilization of bamboo carbohydrates, from the preparation of the raw-material, to the fermentation step. The high carbohydrate content of bamboo and the other advantages already mentioned, undoubtedly justify further investigation. Concentration of solids in the slurry between 17–19%. ●–●—noncooked and without fungal broth; ■–■—noncooked and with fungal broth; ▲–▲—noncooked and added broth with twice the activity of the cellulolytic fractions; ○–○—without cooking; x–x—cooking at 120°C; □–□—cooking at 160°C; ∆−∆—cooking at 175°C. Carbohydrase concentration (units/g solids): C1=1.41; Cx=0.59; βglucosidase=0.27; xylanase=1.42.

TABLE 2. Conversion of bamboo components and fermentation of slurry simultaneouly with hidrolysis in 7.5l reactor. Final Fermentation % Digestion after 70hs ETOH Starch Cellulose Pentosans Lignin sugar Produced Theoretical efficiency % g/l g/l α-amylase 57 21 35 26 25 glucoamylase α-amylase 61 24 36 25 45 glucoamylase fungal broth α-amylase 67 28 44 43 0.5 10.27 13.3 66 glucoamylase fungal broth yeast inoculum Concentration of solids in the slurry was 16%. Activity of the enzymes (units/g solids): C1=1.51; Cx=0.36; β—glucosidade=0.20, xylanase not determined. a) Theoretical ETOH is the sugar consumed×0.5111.

REFERENCES (1) McCLURE, A.A. The bamboos, a fresh perspective. Harvard University Press., Cambridge, Massachusetts, 343p., (1966). (2) MEDINA, J.C. Plantas Fibrosas da Flora Mundial. Instituto Agronômico do Estado de São Paulo, Campinas, 913p., (1959). (3) UEDA, K. “Culture of bamboo as industrial raw-material”. Bulletin of Japan, no 2-A/68, (1968).

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(4) MENEZES, T.J.B.; de LAMO, P.R. and ARAKAKI, T. Col. Inst. de Tecnologia de Alimentos, 7:83, (1976). (5) MENEZES, H.C. Produção de xilanase por mutantes de Rhisopus induzidos por luz Ultravioleta. In; 28 Reunião da Sociedade Brasileira para o Progresso da Ciência. Brasilia, 1976. Simpósios, São Paulo, 1978, p. 134–136. (6) MENEZES, T.J.B.; dos SANTOS, C.L.M. & AZZINI, A. Biotechnol. Bioeng. 25, 1071, (1983). (7) MANDELS, M.; WEBER, J.; PARISEK, R. Appl. Microbiol., 21:152, (1971). (8) ASSOCIATION OF OFFICIAL ANALYTICAL CHEM., 11 ed., US-GPOS, Washington, D.C., (1970). (9) DIEMAIR, W. Laboratoriunsdbush für den lebensmittelchemiker—Verlag Von Theodor Steinkopff, Dresden um Leipizing, 8 Auflage, 804p., (1963). (10) EDWARDS, C.D.J. Sci. Ed. Agric., 24:381, (1973). (11) SUMMER, J.B.J. Biol. Chem. 62:278, (1924/25). (12) LEWIS, R.A.; MOREIRA, A.R.; MURPHY, V.G. and LINDEN, J.C. Kinetics of Hemicellulose Autohydrolysis for Wheat Straw. Paper presented at ACS Annual Meeting New York, N.Y., August 26, (1981).

ACKNOWLEDGEMENT T.J.B.de MENEZES would like to acknowledge the financial support by CNPq of Brazil with respect to his participation at this meeting.

CONTINUOUS CONVERSION OF LACTOSE TO ETHANOL USING ZYMOMONAS MOBILIS AND IMMOBILIZED ß- GALACTOSIDASE S.TRAMM—WERNER and W.HARTMEIER Institute of Mikrobiology, Technische Hochschule Aachen, Worringer Weg D 5100 Aachen (FRG) Summary ß-galactosidase (lactase, EC 3.2.1.23) from Aspergillus oryzae was crosslinked with glutaraldehyde. The enzyme was used simultanuously with a new flocculent strain of Zymomonas mobilis in a special upflow floc tower reactor for continuous ethanol production from lactose. Different from the parent strain the new flocculating strain, called TW 602, could be easily retained in a specially deviced fermenter, so that a cell dry weight of 49,9g/l was preserved. The specific productivity of the mutant was 4,1g/g×h, and therewith significantly higher than the productivity of the parent strain (3,2g/g×h). The bacterial flocs had nearly the same physical properties as the immobilized enzyme particles; both were kept back in the reactor up to a dilution rate of 5h−1. Using substrate with 18% lactose, a productivity of 7g/l×h (based on total reactor volume) resulted. While the glucose component of the lactose was nearly completely fermented, galactose remained unused. Due to the high dilution rates, the system was not susceptible to infections under non sterile conditions. It remained stable for at least 250 hours. Besides for lactose, the system was also practicable for maltodextrin.

1. Introduction Many attempts have been made to work out a process of technical interest for ethanol production with Zymomonas mobilis. In Germany, a plant of 80m -scale for the ethanol production from hydrolized B-starch is already in operation. For this process a volumetric productivity of 3,6g/l×h and a dilution rate of 0,06h−1 are reported (Bringer and Sahm, 1984). The advantages of flocculating growth characteristics have repeatedly been revealed as a method to optimize the volumetric productivity, since there is no need of filter— membranes or cell recycle to preserve high biomass concentrations (Rodriguez and Danley 1983; Strandberg et al. 1982).

Continuous conversion of lactose to ethanol using zymomonas mobilis and immobilized b-galactosidase

For industrial application it would in addition be interesting to broaden the substrate range of the organism, which can only ferment glucose, fructose and sucrose. It has recently been tried to insert the missmg hydrolytic capacity by means of genetic engineering, which led only to poor fermentation rates (Goodman et al., 1984) .Another possibility to add the missing hydrolizing capacity is the coimmobilization of the organism with an additional enzyme (Hägerdal 1980; Hartmeier 1981). In a preceeding investigation (Hartmeier et al. 1984) we could show that Z. mobilis coentrapped with ßgalactosidase from mould origin in alginate beads can be used for the fermentation of the glucose part of lactose. However, the productivity of this system, as calculated per total fermenter volume, was considerably decreased due to the space occupied by the nonproductive matrix material. The present study tries to combine the advantages of flocculating organisms and immobilized enzymes by using both for simultanuous hydrolysis and fermentation of non fermentable substrates in a special upflow floc tower fermenter. The fermentation of lactose was chosen as a first model substrate and compared with the direct con—version of glucose. 2. Material and Methods Organism. The flocculent strain was derived by UV-mutagenesis of Z. mobilis ATCC 10988. The irradiated cells were selected for flocculation in a specially deviced upflow fermenter(fig .3) by increasing the dilution rate continuously to a rate of 1h−1, where only flocculating cells were kept back in the reactor. Fermentation medium and culture maintamance: see Rodriguez and Callieri (1983); instead of 100 g/l sucrose 100g/l glucose, 180g/l lactose or 100g/1 maltodextrin were used. Beet molasses (from Pfeifer & Langen, Euskirchen, FRG) was diluted to a sucrose concentration of 5% and supplemented with the same mineral salts as the normal fermentation media. Instead of yeast extract 1% whey powder (from Milchversorgung Rheinland e.V., Krefeld, FRG) were added . Continuous fermentations. Trials were started with an inoculum of 600 ml with a dilution rate of 0,14h−1 for 24 hours. The tower fermenter consisted of two parts, a cylindrical glass column with 4 cm in diameter and 35 cm lengh, and a settler with variable working volume. The main stream of carbon dioxide was taken out by the inverted funnel, so that the overflow was located in a region free of turbulences and floccules; by this system a loss of bacterial flocs and enzyme particles along with the effluent was avoided. Medium and immobilized enzyme were introduced at the base, the temperature was regulated at 30°C by means of a water jacket, and the pH-value was kept at 4,5 by automatic addition of 1M NaOH. The tower fermenter (see fig.1) was constructed based on the experiences of Prince and Barford(1982) and Rodriguez and Callieri (1983). immobilization of the enzyme. The hydrolases were immobilized by crosslinking with glutaraldehyde according a method of Hartmeier et al. (1984). Analytical methods. Ethanol and glucose were determined enzymatically (test set no 176290 and 716 251 from Boehringer, Mannheim, FRG). Cell dry weight was determined after centrifugation, twofold washing of the cell suspension and drying at 110°C for 20 hours. The ß-galactosidase activity was determined on 0.5 M lactose in

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0.1M acetate buffer of pH 4.5 at 30°C for 10 minutes. The amount of glucose set free was determined enzymatically. 3. Results and Discussion Characteristics of Z. mobilis TW 602 A comparison of the growth and ethanol formation characteristics of Z. mobilis ATCC 10988 with those of the mutant strain Z. mobilis TW 602 is given in figures 2 and 3. it becomes obvious from these batch experiments that the newly Isolated mutant is more suitable to the requirements of ethanol production than the parent strain. Although the growth rate of the mutant at 30°C and 10% glucose was lower than that of Z. mobilis ATCC 10988 (0.23 respectively 0.28h−1), the specific productivitiey of ethanol formation was 4.1g/g×h. These productivity data are derived from the slope of the curves (fig. 2 and fig. 3) after 16h of batch fermentation. Ethanol production in the tower fermenter Results of the continuous fermentation carried out with 7.5g of the immobilized ßgalactosidase of Aspergillus oryzae on 18% lactose are given in figure 4. All the glucose set free by the enzyme was rapidly fermented by the bacteria. Hydrolysis of the lactose was obviously the rate limiting step of this system, especially because the enzyme is inhibited by the non fermentable galactose. Therefore, lactose is not at all an ideal substrate to be converted by the system presented. Nevertheless the volumetric productivity of 7g/l·h , reached when increasing the dilution rate to 0.33h−1, can well compete with the data found by other working groups (3.978g/l·h with Kluyveromyces coimmobilized with ß-galactosidase in alginate beads; Hägerdal, 1980). First trials with the simultanuous saccharification and fermentation (SSF) of dextrins with a system containing immobilized glucoamylase (Miles Kali Chemie, Hannover), show that this system will be even more effective, probably because the inhibiting product glucose does not accumulate (see table 1). For comparison, there are also given results on glucose-and sucrose media. Beet molasses had to be diluted to a sucrose concentration of 5%, since Zymomonas did not grow well with more concentrated molasses, probably because of the mineral content (Skotnicki et al. 1984). The addition of 1% whey powder instead of yeast extract led to a 16% increase of the ethanol yield. It was not possible to avoid a considerable amount of unused sugar in the effluent of sucrose and molasses fermentations. Even with reduced dilution rates the carbohydrate content never fell below 2%. These difficulties could be caused by an inhibitory effect of ethanol on the enzymes involved in sucrose hydrolysis (Lee et al. 1981). Thus, first trials show that it might be advantageous to add immobilized invertase to improve the fermentation of sucrose.

Continuous conversion of lactose to ethanol using zymomonas mobilis and immobilized b-galactosidase

Fig 1: Upflow tower fermenter

Fig. 2: Batch fermentation with the flocculating mutant Z. mobilis TW 602 on 10% glucose. (■) glucose, (×) ethanol, (o) cell dry matter .

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Fig.3: Batch fermentation with Z. mobilis ATCC 10988 on 10% glucose. (■) glucose, (x) ethanol, (o) cell dry matter.

Fig. 4: Continuous fermentation on 18% lactose. (■) glucose, (x) ethanol Table 1; Different fermentations with Zymomonas mobilis TW 602 in the upflow floc tower fermenter. substrate

concentration dilution rate productivity [%] [h−1] [g EtOH/l×h]

lactose

18

0, 19

7

Continuous conversion of lactose to ethanol using zymomonas mobilis and immobilized b-galactosidase

maltodextrin 10 molasses 5 sucrose 10 glucose 10

0,29 1,00 0,88 1,3

9,4 18 29,3 60

References Bringer S, Sahm H (1984) Continuous ethanol production from glucose with Zymomonas mobilis. In: 3rd Europ Congr Biotechnol vol 2. Verlag Chemie, Weinheim Deerfield Beach Basel, pp 339–343 Goodman AE, Strzelecki A T, Rogers P L (1984) Formation of ethanol from lactose by Zymomonas mobilis. J Biotechnol 1:219–228 Hägerdal B (1980) Enzymes co-immobilized with microorganisms for the microbial conversion of non metabolizable substrates. Acta Chem Scand 34:611–613 Hartmeier W (1981) Basic trials on the conversion of cellulosic material to ethanol using yeast coimmobilized with cellulolytic enzymes. In: Moo-Young M (ed) Advances in Biotechnology vol.3. Pergamon, Toronto, pp 377–382 Hartmeier W, Förster U, Tramm Werner S (1984) Coimmobilization of fermenting microorganisms and β-galactosidase for lactose fermentation. In: 3rd Europ Congr Biotechnol vol 2. Verlag Chemie, Weinheim Deerfield Beach Basel, pp 361–369 Lee K J, Skotnicki M L, Tribe D E Rogers P L (1981) The kinetics of ethanol production by Zymomonas mobilis on fructose and sucrose media. Biotechnol Lett 3: 207–212 Rodriguez E, Callieri D A S (1983) Conversion of sucrose to ethanol by flocculent Zymomonas sp. strain in a continuous upflow floc reactor. Europ J Appl Microbiol Biotechnol 18:186–188 Skotnicki M L, Warr R G, Goodman A E Lee K J, Rogers P L (1984) High productivity alcohol fermentations using Zymomonas mobilis. Biochem Soc Sympos 48:53–86 Strandberg G W, Donaldson T L, Arcuri E J (1982) Continuous ethanol production by a flocculent strain of Zymomonas mobilis. Biotechnol Lett 4:347–352

Acknowledgement This research was carried out under contract no GBI 004-D (B) of the Biomolecular Engineering Program of the Commission of the European Communities.

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NEW CONTINUOUS PROCESS FOR PRODUCTION OF ETHANOL USING IMMOBILIZED CELLS REACTOR MM.LEULLIETTE L.—HENRY M.—GROS D.— SGN: Société Générale pour les techniques Nouvelles 78184 SAINT QUENTIN EN YVELINES CEDEX—France Summary SGN has developed a continuous ethanol production process without external cell recycling. The work covered syrups with mineral salts, sugar beet juice, and molasses. The results obtained with the syrup and sugar beet juice have proved the feasibility of this process, low residence time and good productivity. On molasses, thanks to an aeration of 2 VVH it has been possible to maintain active cells in a reactor without having to extract them for regeneration.

1. Introduction SGN has developed a continuous sugared juice fermentation process to obtain ethanol. This process is called : “SGN Cell Concentration Process”. The reactor enables SACCHAROMYCES CEREVISIAE to concentrate and in certain parts, to reach a concentration higher than 100g/liters. This containment saves all cell recycling and, by giving a rapid ethanol synthesis, entails only a low residence time (4 to 5 hours). We have performed three types of experiments: – on syrup with a 50 liter pilot unit – on sugar beet juice with a 7 000 liter pilot unit – on molasses with 25 and 135 liter pilot units.

2. Objectives – To determine the maximal cell concentration in the fermentor. – To determine the minimal residence time needed to consume the sucrose. – To quantify the influence of low aeration on molasses fermentation. – To maintain the activity of the cell in the molasses reactor without having to regenerate them.

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3. Methodology – Culture medium: sugar beet juice (120 to 160g/l of sucrose), syrup (160g/l sucrose) or molasses (80 to 150g/l of sucrose). – Strain: distillery strain of SACCHAROMYCES CEREVISIAE isolated from industrial vessels and two strains of SACCHAROMYCES CEREVISIAE SPE. – Fermentation parameters: pH 3.2 for syrup and 4, 5 for beet juice and molasses. Temperature: 32°C. For molasses: aeration flow 2 VVH – Analysis: • Ethanol by gas chromatography. • Sucrose by Fehling method. • Biomass by dry matter and by centrifugation (%). • Bacteria by counting on microscop.

4. Results PILOT PLANT PREINDUSTRIAL FERMENTATION 50 (BEET JUICE) LITERS SYRUP+ MINERAL SALTS Residence time (h) Dilution rate (l/h) Residual sugar (g/l) Ethanol concentration (% V/V) Ethanol yield Yeasts (%) centrifugation Productivity (g/l/h) Aeration (VVH)

PILOT PLANT FERMENTATION 25 LITERS MOLASSES

3.5

7

8

0.3

0.14

0.12

<1

<3

<10

>9

9.5

(5) 6 to 9

0.60 to 0.63 55% (>100 g/l)

0.59 to 0.61 35% (>100 g/l)

0.60 30–40

>20

>12

>10

0

0

2

NOTA: For each experiment, the whole reactor was not systematically used, the fermentation was often completed in only a part of the reactor.

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5. Conclusions – Pilot plant fermentation 50 liters syrup+mineral salts • Obtention of a maximal cell concentration of 55% in the reactor. • Determination of a minimal residence time of 3.5 hours to metabolize the sucrose (160g/l) from syrup with mineral salts. • Preservation of 99% of the living biomass in the reactor. • Maximal reactor productivity reached: >20g/l/h. – Preindustrial (7 000 liters) beet juice • Residence time of 7 hours. • Relatively few contamination problems. • No biomass recycling and concentration of 40% (90–100g/l) yeasts in reactor. • Obtention of product at 9.5% V/V. – Pilot plant fermentation 25 liters molasses • An aeration (air+oxygen) of 2 VVH kept the cells confined in the reactor without the need for outside regeneration. • Maintaining active SACCHAROMYCES in the reactor for a minimum period of 10 days: 90% sugar was consumed for a residence time of 4 to 5 hours, with a yield of 62 liters ethanol for 100 kg of consumed sugar. • Obtention of a product at 9% V/V during 48 hours. – Finally, the process concept enables vinasses and effluents to be processed after distillation, by methanation and/or evaporation, each process scheme being economically optimized.

ACETONE BUTANOL FERMENTATION OF HYDROLYSATES OBTAINED BY ENZYMATIC HYDROLYSIS OF AGRICULTURAL LIGNOCELLULOSIC RESIDUES R.MARCHAL, M.REBELLER, F.FAYOLLE, J.POURQUIE and J.P.VANDECASTEELE Institut Français du pétrole 92506 Rueil-Malmaison (France) Summary IFP is developping a process of conversion of lignocellulosic substrates into butanol and acetone. This process includes steam explosion pretreatment of the substrates, enzymatic hydrolysis and acetone butanol ethanol (ABE) fermentation. Present results obtained for enzymatic hydrolysis and for ABE fermentation are discussed. They show the feasibility of the general process and point out the possibilities of improvement of the overall conversion yields.

1. INTRODUCTION IFP is developping a process for enzymatic hydrolysis and acetone butanol ethanol (ABE) fermentation of cereal straw and corn stover as part of a program for the production of substituted fuels. The general scheme of the process which will be experimented on a preindustrial scale in a plant under construction at Soustons in the Southwest of France, is shown in Fig. 1. Some recent results regarding the steps of enzymatic hydrolysis and ABE fermentation are presented below. 2. RESULTS Pretreatment is a key step for hydrolysis performance and for the economy of the process. The steam explosion pretreatment has been selected after a comparative evaluation of various techniques on the basis of cost and efficiency. The hydrolysis of lignocellulosic materials is carried out in batch conditions with the cellulase complex of T. reesei CL 847. This enzyme is produced by a batch fermentation process from a soluble substrate (lactose) (Warzywoda et al., 1983a, Warzywoda et al., 1983b). Substantial improvement of cellulase production (average enzyme titer: 22.5 FP

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units per ml) has been recently obtained by fed batch addition of lactose (Vandecasteele and Pourquié, 1984). A typical hydrolysis kinetics of steam-exploded corn stover with these enzyme preparations is shown in Fig. 2. Scheme of ACETONE-BUTANOL-ETHANOL PRODUCTION FROM CELLULOSIC MATERIALS BASIS 1t ABE

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Fig. 2. Hydrolysis kinetics of steamexploded corn stover with the Trichoderma reesei cellulase complex. Conditions: Corn stover has been pretreated by steam explosion (21 bars, 2 min.), Unwashed pretreated material has been enzymatically hydrolyzed by Trichoderma reesei CL 847 cellulases (180g/l (d.w.) of pretreated material, 10 FP units cellulase per g of substrate, 50°C). The sugars produced (glucose and xylose) are determined by HPLC. The sugars obtained are essentially glucose and xylose with very little cellobiose. The final sugar yield is about 34% with respect to the initial dry matter and 55% with respect to the potential sugars. Recent modifications in pretreatment conditions resulted in a spectacular increase of sugar yield (80–85% with respect to potential sugars) using the same hydrolysis conditions as above. Hydrolysates obtained from steam-exploded materials contain inhibitory compounds which considerably hinder or block the ABE fermentation. The characterization of these inhibitors is presently studied. Simple and efficient treatments of hydrolyzates which allow their fermentation into ABE have been found. Fig. 3 shows an exemple of such a fermentation.

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Fig. 3. Acetone-butanol fermentation of corn stover hydrolyzates obtained after steam explosion pretreatment. Conditions: The corn stover hydrolyzate (55g/l of glucose plus xylose) was supplemented with 3g/l (NH4)2SO4 and 3g/l corn steep liquor and sterilized after pH adjustement. The fermentation was performed at 35°C using C. acetobutylicum IFP 920. As illustrated in Fig. 3, xylose is commonly utilized more slowly than glucose by C. acetobutylicum as previously described by Ounine et al. (1983). Selection of better xylose-utilizing strains is under way and is expected to allow a significant improvement of the fermentation performance. Another point of interest is the simultaneous enzymatic hydrolysis and ABE fermentation of pretreated lignocellulosic substrates. Excellent performance for this onestep procedure has already been obtained in the case alkali-pretreated straw (Marchal et al., 1984). REFERENCES MARCHAL, R, REBELLER, M. and VANDECASTEELE, J.P. (1984). Direct bioconversion of alkali-pretreated straw using simultaneous enzymatic hydrolysis and acetone-butanol fermentation. Biotechnol. letters. 6, 523–528.

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OUNINE, K, PETITDEMANGE, H., RAVAL, G. and GAY, R. (1983). Acetone-butanol production from pentoses by Clostridium acetobutylicum. Biotechnol. letters. 5, 605–610. VANDECASTEELE, J.P., POURQUIE, J. (1984). Conversion de la biomasse en produits à usage de carburants par fermentation acétonobutylique. Proceedings of the 6th Symposium on alcohol fuels technology, Ottawa, Vol. 2. p. 227–233. WARZYWODA, M., FERRE, V., POURQUIE, J. (1983a). Development of a culture medium for large scale production of cellulolytic enzymes by Trichoderma reesei. Biotechnol. Bioeng. 25, 3005–3010. WARZYWODA, M., CHEVRON, F., FERRE, V., POURQUIE, J. (1983b). Pilot scale production of cellulolytic enzyme by Trichoderma reesei. Biotechnol. Bioeng. Symp., 13, 577–580.

ACID HYDROLYSIS FOR THE CONVERSION OF CELLULOSIC BIOMASS TO ETHANOL JOHN PAPADOPOULOS Forest Research Institute, Terma Alkmanos Athens 115 28, GREECE Summary The production of ethanol from lignocellulosic substrates requires the hydrolysis of cellulose to glucose and the fermentation of glucose by yeast to ethanol. In any of the lignocellulosic to ethanol proposed processes, all by-products should be considered for exploitation. In order to achive this objective the lignocellulosic substrates should be prehydrolysed for optimal recovery of the hemicellulosic components, followed by the main hydrolysis step aiming at high glucose and lignin yields. Birch wood was subjected to acidic treatments with various acids, namely dilute sulfuric acid, concentrated hydrochloric acid and anhydrous hydrogen fluoride. For both prehydrolysis and hydrolysis with dilute sulfuric acid,significant loses of xylose and glucose were observed as reaction time was prolonged. The optimum yields for xylose and glucose were 49 and 61 percent respectively. Higher yields of xylose and glucose were recorded, 93 and 87 percent respectively, by treating birch-wood with concentrated hydrochloric acid. Finally, hydrolysis with anhydrous hydrogen fluoride gave the highest yields for xylose and glucose, 91 and 93 percent respectively. The structureal changes occuring in lignin during hydrolysis with the various acids were also investigated. The HCl-lignin residues appear to be the least condensed and the HF-lignin residues the least hydrolysed.

1. INTRODUCTION Renewable resources in the form of forest products and agricultural residues have long been used as raw materials by a wide variety of industries, such as construction, pulping, textiles and so on. Because of projected future petroleum shortages, renewable reseources have gained considerable attention as an alternative source for the production of energy and chemicals. Wood as the most abundant renewable resource available, becomes the prime candidate for the conversion to fuel, solvents polymers, plastics, chemical intermediates and so forth (1,2). Although technologically feasible (3), the development of economically viable processes, was hindered either by the competition of largevolume, low priced petrochemicals or the non-competative economics focused in the

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production of a single product. It has been suggested that in any of the lignocellulosic to ethanol proposed schemes all by-products should be considered for exploitation, for the process to be economically successful. In order to achive this objective, optimal recovery of all wood components should be attained (4). The purpose of this paper is to give a systematic and comparative presentation of the various acid hydrolysis treatments of some economical interest, namely, dilute sulfuric acid, concentrated hydrochloric acid and anhydrous hydrogen fluoride, under reaction conditions permitting optimum recovery of the carbohydratics. The classical two-stages hydrolysis processes, namely the concentrated hydrochloric acid and dilute sulfuric acid, are energy consuming and lead to the formation of carbohydrate decomposition products which may hamper further biotransformations of the saccharide products to ethanol. As hydrolysis with anhydrous hydrogen fluoride takes place at ambient temperatures, the energy requirements of this process seams to be of limited importance. However, anhydrous hydrogen fluoride is a toxic and expensive chemical and it should be recovered quantitatively, for the process to be economically viable, In addition, both xylose and glucose are recovered as a mixture from the hydrolysis liquor and their separation is associated with additional cost. 2. HYDROLYSIS OF CARBOHYDRATES During the early stages of the development of wood hydrolysis processes, both hemicelluloses and celluloses were hydrolyzed in a single step. Because of its crystalline organization, cellulose requires more stringent conditions (high temperature or high acid concentration). Under the same conditions hemicelluloses are hydrolyzed much faster to the related momomers, followed by decomposition of the hydrolysis products. To overcome there limitations, the overall hydrolysis processes has been often designed as a two-step processes. For dilute sulfuric acid prehydrolysis of birch wood-meal was carried out with 0.5% sulfuric acid at 140° C, at various reaction times and hydrolysis with 0.5% sulfic acid at 180° C. From the figures 1 and 2 becomes apparent that under the reaction conditions employed only small yields of xylose and glucose can be obtained (49 and 61 percent respectively). That is because at the high temperatures employed, car-bohydrates degrate to products of non- saccharide nature. It seems likely that in order to achieve quantitative yields a continous hydrolysis process, should be developed (4). As in any chemical process, the amount of solvent used, in this case dilute sulfuric acid, is of considerable importance in the overall economic of the process. A continous process will require large amounts of solvent which must be recovered quantitatively. Because the hydrolysis with sulfuric acid employs very small concentrations of acid, the-refore large quintities of water, its recovery should be considered as non economical. For concentrated hydrochloric acid prehydrolysis was carried out with 30% HCl at 40° C and hydrolysis with 43% at 50° C (5). The highest yields for xylose and glucose were 93 and 87 percent respectively (Figures 3 and 4). The process is characterized from the moderate temperatures used and the high acid concentrations needed. Because of such high concentrations, a recovery above 95% should be achieved for the process to be economically viable.

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Hydrolysis with anhydrous hydrogen fluoride was carried out in one step at ambient temperature. Quantitative yields of xylose and glucose were achieved in relatively short times (Figure 5) (6). However, the process is associated with the use of an expensive and toxic solvent, which should be totally recovered and it should be probably considered as non economical Furthermore, the reaction products, namely xylose and glucose need to be separated. 3. RESIDUAL LIGNIN The potential from the utilization of lignin to the overall economics of any wood hydrolysis process was recognized only a few year ago and since then a considerable effort has been deyoted towards the development of integrated wood conversion processes (7). In its native form, lignin is a three dimensional, highly branched, anorphous macromolecule and appears to be insoluble in any common solvents. Although its detailed structure is not very well defined a considerable amount of knowledge about its structure has been accumulated over the years through biosynthetic or degradative invetigations. Since all the obtained lignin residues were insoluble, the differences in their structural characteristics was studied on the basis of very well defined depolymerization techniques. In the presence of acids, hydrolysis of lignin occurs resulting in the formation of lower molecular weight fragments (8). The liberated lignin fractions do not accumulate but react through self condensation to form higher molecular weight adducts. Condensation reaction of lignin become of particular importance since they, to a considerable extent govern further utilization of lignin in the degraded or macromolecular form (9). The extend of lignin condensation was estimated by nitrobenzene oxidation while the differences in depolymerization among the varioua lignin preparations were defined on the basis of the new functional groups generated and in particular, new phenolic hydroxyl groups. The extent of condensation of the liberated lignin fractions which as known leads to the formation of new carbon to carbon bonds can be determined indirectly by alkaline nitrobenzene oxidation. Thus the formation of new carbon-to- carbon linkages is followed by decrease in the yield of total aldehydes. The reaction conditions for the isolation of the various lignin residues were chosen so to enable optimum recovery of carbohydrates. Thus for dilute sulfuric acid, prehydrolysis was carried out with 0.5% sulfuric acid at 140° C for 1 hour and hydrolysis with the same acid concentration at 180° C for two hours. A two-stages hydrolysis was also employed for the treatment of birch-wood with concentrated HCl. Prehydrolysis was carried out with 30% hydrochloric acid for 90 minutes, followed by hydrolysis with 43% HCl at 50° C for two hours. Finally, hydrolysis with anhydrous hydrogen fluoride was carried out in one stage at ambient temperatures for 30 minutes. Table 1 shows that HCl-lignin residue is the least condensed while H2SO4 and HF lignin residues appear to condense at about equal rates. Con-sidering that hydrolysis with HCl and H2SO4 results also in the release of small amounts of acid soluble low molecular weight lignin in the hydrolyzates (11 and 7 percent respectively,) while HF does not, it is likely that HF lignin residues are the most condensed of the three.

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Table 1. Total aldehydes derivable from lignin residues. (expressed as molar percentage) Total aldehydes Birch Wood H2SO4, lignin HCl—lignin HF—lignin

42.6 19.3 25.5 19.8

In the presence of alkali and elevated temperatures lignin depolynerizes mainly via splitting of alkyl-aryl ether linkages with subsequent formation of new phenolis hydroxyl groups. Phenolic groups can be methylated by diazomethane and their increase can be indirectly determined by me-asuring the increase in methoxyl group. It becomes apparent from table 2 that HF-lignin shows the smallest methoxyl increase which indicates that HF-lignin residues contain small amounts of phenolic groups. This observation combined with the increase of the Ph-OH groups after alkaline hydrolysis,table 3, can lead to the postulation that aryl-alkyl ether linkages are not cleaved in the presence of anhydrous hydrogen fluoride (6). In contrast, hydrolysis of these linkages proceeds to a larger extent in the case of dilute sulfuric acid hydrolysis. The previous postulation is also suppoted by the molecular weight distribution curves observed, after alkaline degradation of lignin (Figure 6), where elution profiles showed that HF-lignin residues are the most degraded.

Table 2. Increase in phenolic hydroxyl as expressed by the increase in methoxyl content after methylation. Original Methoxyl content

Methoxyl content after methylation

H2SO4—lignin HCl—lignin HF— lignin

Methoxyl content increase

16.8 17.3 28.6

18.9

34.1 18.3 32.5 15.2 9.7

Table 3. Increase in methoxyl content of the HFlignin residues. Reaction time (min) Methoxyl content 0 60 120

28.6 38.3 40.9

REFERENCES (1) COLDSTEIN, I.S. (1975). Potential for Converting Wood into. Plastics. Science 189, 847–852. (2) COLDSTEIN, I.S. (1979). Chemicals from Wood. Unasylva 33 (125), 2–9.

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(3) OSHIMA, H. (1965). Wood Chemistry Process Engineering Aspects Process Monograph No 11, Noyes Development Corporation, New York, 1965. (4) COLDSTEIN, I.S. (1981). Intergrated Plants for Chemicals from Biomass, in Organic Chemicals from Biomass, I.S. Goldstein, Ed, CRC Press, Boca Raton F.L. Chap. 12. (5) PAPADOPOULOS, J. CHEN, C-L, and COLDSTEIN, I.S. (1983). Behavior of Sweetgum Wood Xylan and Lignin During Hydrolysis with Concentrated Hydrochloric Acid at Moderate Temperatures, Journal of Applied Plymer Sience, Applied Polymer Symposium 37, 631–640. (6) DEFAYE, J., GADELLE, A., PAPADOPOULOS, J. and PEDERSEN, C. (1983), Hydrogen Fluoride Saccharification of Cellulose and Lignocellulosic Materials Journal of Applied Polymer Science, Applied Polymer Symposium 37, 653–670. (7) FALKEHAG, I.S. (1975). Lignin in materials. Applied Polymer Science, Applied Polymer symposium 28, 847–852. (8) LAI, Y.Z. and K.V. SARKANEN (1971). In “Lignins” (K.V. Sarkanen andC. H. Ludwig, eds) Wiley-Inferscience, N.Y. Chapter 5, 185–186. (9) PAPADOPOULOS, J. (1983). Some strutural characteristics of Acid Hydrolysis Lignins, in Biomass Utilization (W.Côte, ed.) .Plenum Press, 299–307.

Fig. 1

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Fig. 2

Fig. 3

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NMR-ANALYSIS OF FERMENTATION PRODUCTS BY CLOSTRIDIUM ACETOBUTYLICUM C.ROSSI*, P.VALENTI, N.MARCHETTINI* and N.ORSI *Dipartimento di Chimica Università di Siena Istituto di Microbiologia Università di Roma Summary The utilization of glucose during anaerobic fermentation of Clostridium acetobutylicum has been studied by means of carbon-13NMR resonance. When [1–13-C] enriched-glucose is used as carbon source it is possible to investigate the distribution of 13-C labelled atoms among intermediate and final products. In the wild strain we have noticed several compounds of glucose utilization as intermediate and final products in addition to acetone-butanol-ethanol (ABE). On the contrary in butanol tolerant strain PV2 only ABE and their precursors are produced.

1. INTRODUCTION Recent studies pointed out that nuclear magnetic resonance (NMR) spectroscopy provides detailed information about kinetics of metabolic reactions, metabolic pathways involved in biosynthetic processes and physical chemical properties of macromolecules present as natural constituents of cell, organs and tissues (1–4). By using proton, carbon and phosphorus nuclear magnetic resonances many different cellular events can be analyzed by means of a “non invasive technique” (5–7). Intensity, chemical shift and relaxation time NMR parameters measured “in vivo” bacterial and yeast suspensions give information about the cellular behaviour at molecular level (8). By comparing NMR results obtained on different microorganisms it has been possible to have some information about: i–the metabolic rate and the end products yielded; ii–the presence of alternative metabolic pathways of a biosynthetic process; iii–the best condition to obtain higher yield in end products. In the present report we studied by NMR approach the glucose metabolism of a wild strain of Clostridium acetobutylicum 6445 and its mutant PV2. The comparison of both glucose metabolic process and efficiency of acetone, butanol and ethanol (ABE) conversion has been used to study the metabolism of the butanol-tolerant mutant strain. In order to obtain well resolved 13C-NMR spectra, 13C-enriched substrates were used by reason of 1% natural abundance of 13C. In this way, by selective 13C-enrichment of glucose molecules, it has been possible to study the total glucose catabolism by following

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the distribution of the 13C labels among different carbons of intermediate and end product molecules. 2. MATERIALS AND METHODS Selection of butanol-tolerant strains: The butanol-tolerant strain PV2 was derived from wild type C. acetobutylicum NCIB 6445 by an enrichment procedure. Parent strain cultures were inoculated under anaerobic conditions in a medium to which were added different concentrations of butanol. After 24 hours the grouwth was evident only in the control culture without butanol, but after 48 hours a similar optical density was obtained also in the culture with 10 g/l of butanol. This culture was transferred sequentially to fresh medium containing increasing amounts of butanol (up to 20 g/l of butanol). After the seventh transfer, a selected strain capable of growing in 20 g/l of butanol was obtained. Test conditions: the synthetic medium described by F. Monot et al. (9) was used. The glucose concentration was 2% plus lmg/ml of 1–13C enriched glucose. The inoculum of C. acetobutylicum was about 1%. Cultures were carried out at 30°C in a static condition. NMR Measurements: 13C-NMR spectra were recorded at 50.288 MHz by using a Varian XL-200 spectrometer equipped with a 10 mm 13C probe and operating in the Fourier transform mode by a Sperry Univac computer. The spectra were accumulated in 20 minute blocks (800 scans) with a repetition time of 1.5 s. All 13C-NMR spectra were broad-band proton decoupled by using low RF field in order not to alter the sample temperature. The measurements were obtained with a coaxial tube; deuterium NMR signal arising from 99.75% D2O was used as lock signal. All chemical shifts were referred to tetramethylsilane through the use of αC1 and ßCl glucose signals. The 13-C resonance lines were assigned on the basis of both chemical shift and metabolic considerations. 3. RESULTS Production of acids and solvents in synthetic medium The glucose utilization was studied after 24 hours of fermentation in order to analyze the production of butyric and acetic acids and after 48 hours to study the conversion of acids into solvents (ABE). A) After 24 hrs, similar to that observed in PV1 mutant (10), also PV2 grows faster than the parent strain and the culture pH is lower (pH=4.0 for PV2 and pH=5.0 for 6445). In figures 1A and 1B the 13C-NMR spectra of the supernatans obtained from wild and PV2 strains are shown. On the basis of the NMR results the following considerations can be made: i) in the first stage of fermentation both strains show a strong NMR signal due to butyric acid; ii) in the wild strain several compounds of glucose utilization are observed; on the contrary the mutant PV2 produces only butyric acid as NMR detectable compound. It is evident from these data that the efficiency of conversion from glucose –ABE precursor

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was higher in PV2 than in the wild strain in which glucose carbon atoms are utilized to yield several metabolites not directly involved in ABE production.

Figure 1: 13C-NMR spectra of Clostridium acetobutylicum supernatants after 24 hours from the inoculum. 1A the parent strain and 1B the PV2 mutant. B) After 48 hrs of fermentation the number of cells was the same (2×108) for both strains and the only difference was in the final pH of the culture with values of pH=3.5 for PV2 and pH=4.8 for the 6445 strain. As to the NMR spectra, the two strains (figure 2A and 2B) still showed some differences. In fact spectrum 2A obtained from the supernatant of the wild strain still shows butyric acid NMR signal and two unidentified NMR signals at 22.65 and 38.4 ppm respectively, due to ABE alternative metabolic production. The NMR analysis of the supernatant obtained from PV2 shows only ABE NMR signal whereas only one unidentified resonance at 38.04 ppm is evident. 4. CONCLUSION The fermentation performed in a synthetic medium showed differences in glucose utilization in parent and butanol-tolerant

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Figure 2: 13C-NMR spectra of Clostridium acetobutylicum supernatants after 48 hours from the inoculum. 2A the parent wild strain and 2B the butanol-tollerant mutant. strains. In particular the mutant strain showed a narrower pattern of fermentation products with a higher production of butyric acid after 24 hours and of ABE products after 48 hours. These data underline the importance of NMR for the study of metabolic characteristics of the mutants and for the understanding of glucose pathway in C. acetobutylicum. References 1) J.A den Hollander, T.R.Brown, K.U.Ugurbil and R.G. Shulman; Proc. Natl. Acad. Sci. USA 76, 6096 (1979); 2) L.O.Sillerud, J.R. Alger and R.G.Shulman; J.Magn. Res. 45, 142 (1981); 3) R.G.Shulman, T.R.Brown, K.Ugurbil, S.Ogawa, S.M. Cohem and J.A.den Hollander; Science 205, 160 (1983); 4) S.M.Cohen, P.Glynn and R.G.Shulman; Proc. Natl. Acad. Sci. USA 78, 60 (1981); 5) J.K.Barton, J.A.den Hollander, T.M.Lee, A.Mac Laughlin and R.G. Shulman; Proc. Natl. Acad. Sci. USA 77, 2470 (1980) 6) T.Ogino, J.A.den Hollander and R.G.Shulman; Proc. Natl. Acad. Sci. USA 80, 5185 (1983); 7) J.Gillies, K.Ugurbil, J.A.den Hollander and R.G.Shulman; Proc. Natl. Acad. Sci. USA 78, 2125 (1981); 8) L.O.Sillerud and R.G.Shulman; Biochemistry 22, 1087 (1983); 9) G.Monot, J.R.Martin, H.Petitdemange and R.Gay; Appl. Environ. Microbiol. 44, 1318 (1982);

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10) P.Valenti, P.Visca and N.Orsi; Proceedings of Third EC Conference Energy from Biomass, Poster n. 388 (1985).

Acknowledgements This work was supported by “PROGETTO FINALIZZATO ENERGETICA CNRENEA” Grant ENEA N. 32. We thank Miss Anna Lusini for her technical assistence.

ENZYMATIC HYDROLYSIS AND SCP PRODUCTION FROM SOLVENT DELIGNIFIED EUCALYPTUS GLOBULUS L. BIOMASS M.T.A.COLAÇO(*) and H.PEREIRA(**) (*) DTIA, LNETI—Laboratorio Nacional de Engenharia e Tecnologia Industrial (**) Centro de Estudos Florestais, Instituto Superior de Agronomia, Lisboa Summary Eucalyptus wood was solvent delignified with the ethanol: water (1:1) system. Delignification levels of 10% residual lignin could be obtained, corresponding to approximately 70% delignification yield. Enzymatic hydrolysis of ethanol pulped wood was fast and presented high yields. After 72h of hydrolysis, approximately 85% saccharification yield was obtained in relation to total polysaccharides. Growth of Geotrichum candidum and Saccharomyces cerevisiae on the solvent treated wood substrate after enzymatic hydrolysis allowed to obtain a SCP enriched biomass with approximately 40% protein content.

1.INTRODUCTION Enzymatic hydrolysis and microorganism growth on most native lignocellulosic materials can only be achieved in acceptable rates after substrate pretreatment to reduce crystallinity of cellulose, disrupt the lignin-carbohydrate complex and enhance microbial access. Different substrate pretreatments previous to enzymatic processes have been proposed and experimented, which included chemical, mechanical or physical-chemical methods [1]. Wood has attracted attention as a cellulosic substrate as a result of the potential biomass availability in both forests and residues from forest operations. However, cellwall chemical organization, high lignin content and crystallinity of cellulose prevent wood to be considered a ready substrate for sugar utilization: wood has poor rates in enzymatic processes and effective pretreatments are necessary to allow acceptable conversions. Solvent pulping has recently been evaluated as an alternative to conventional pulping as well as a substrate delignification pretreatment [2], One of the solvent systems which has received most attention is the system ethanol: water both in uncatalised and in acidic and alkaline media [3].

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Organosolv pulps show high susceptibility to enzymatic hydrolysis, as shown by experiments with butanol [4], ethanol [3] and methanol [5] delignification. Enhancement of single-cell protein production by solvent delignification of substrate has also been shown for butanol [6], Eucalyptus globulus L. has been previously investigated as a cellulosic substrate. Enzymatic hydrolysis of eucalypt wood showed a low saccharification rate of 10% of the substrate but delignification with ethanol significantly increased hydrolysis [7], Also hydrolysis after sodium hydroxide treatments achieved a 33% saccharification rate and SCP production on the hydrolysis syrups with Candida spp. corresponded to 50–60% of the reducing sugars [8]. 2. MATERIAL AND METHODS Experiments used Eucalyptus globulus L. wood with the following chemical composition: ash 1.0%, extractives 1.4%, lignin 23.0%, cellulose 57.0% and pentosans 21.7%. Solvent delignification of wood previous to enzymatic hydrolysis was made in a M&K digester by use of the solvent system ethanol: water 1:1 (by volume), on 300g samples of wood chips with a solvent: wood ratio of 4:1. Reaction was carried out at 165○C and 175○C, a heating time of 30min and with different reaction times. Yields and residual lignin of pulps were determined. Enzymatic hydrolysis used cellulase from Trichoderma reesei: 1g substrate was hydrolysed with cellulase 5U/ml in 50ml H2O and 50ml citrate buffer pH 4.8 at 50○C. Total reducing sugars were measured in the hydrolysis medium at different hydrolysis times by the DNS method and expressed as glucose [8], The hydrolysis medium (100ml) with 0.5g yeast extract and 0.5g ammonium sulfate was sterilised and inoculated with 25ml of a mixed culture of Geotrichum candidum and Saccharomyces cerevisiae 1:1, 2mg/ml. Fermentation was carried out at 30○C, 100 rpm, during 48h. The solids obtained were cebtrifuged, washed and vacuum dried. Crude protein content was determined by automatic Kjeldhal. 3. RESULTS AND DISCUSSION Ethanol pulping of eucalypt wood at 165○C and 175○C is shown in Figure I. Pulping and delignification present an approximate first-order kinetics with delignification rate constants of −1.03×10−2 min−1 (165○C) and −1.06×10−2 min’ (175○C) and bulk pulping rate constants of −2.03×10−3 min−1 (165○C) and −5.04×10−3 min−1 (175○C).

Enzymatic hydrolysis and scp production from solvent delignified eucalyptus globus l. biomass

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Figure I—Ethanol pulping of eucalypt wood. Bulk pulping yields as total solubilised material in % of initial wood, delignification yields as solubilised lignin in % of total initial lignin in wood (log scale) In ethanol pulping of eucalypt wood only delignification levels to 10% residual lignin could be attained, which correspond to delignification rates of approximately 70% (Table I). Delignification is accompanied by polysaccharide hydrolysis which increases with temperature: for 120 minutes pulping time, the ratio of hydrolysed hemicellulose to solubilised lignin was 0.86 at 165○C and 1.03 at 175○C. These results for the organosolv pulping behaviour of Eucalyptus globulus wood are in accordance with published work on pulping of hardwoods with uncatalyzed ethanol-water systems and without preconditionning [3,9]. TEMPERATURE PULPING TIME, MIN PULP YIELD RESIDUAL LIGNIN % OF WOOD % OF PULP 165○C

175○C

60 120 150 180 15 30 60 90

79.4 76.0 64.4 61.1 96.4 90.4 74.7 66.9

18.3 13.3 11.6 9.8 21.7 18.0 16.0 13.3

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120

66.9

10.0

Table I—Yields and residual lignin in ethanol pulps of eucalypt wood Enzymatic hydrolysis of ethanol pulped wood was fast and increased with hydrolysis time (Table II and Figure II). After 16h of hydrolysis, more than 5.00mg/ml reducing sugars (calculated as glucose) could be obtained from all lignocellulosic pulps studied; after 72h, approximately 85% saccharification yield was obtained in relation to total polysaccharides. Delignification degree did not appear to affect cellulose hydrolysis and very high yield pulps (95%) with only 10% delignification compared favorably to pulps of luch lower residual lignin. Considering that untreated eucalypt wood showeda saccharification yield of only 10% [7], it appears that ethanol greatly enhances enzyme access to cellulose by action on the cell-wall supramolecular structure. Growth of Geotridum candidum and Saccharomyces cerevisiae on the substrate after hydrolysis with different times was achieved in good yields and a protein enriched product could be obtained. Crude protein content of the SCP biomass was approximately 40% (Table III). REDUCING SUGARS, % OF SUBSTRATE HYDROLYSIS TIME, H 175°C, 15MIN 175°C, 30MIN 175°C, 90MIN 165°C, 120MIN 16 24 48 72

54.5 60.5 66.5 75.5

50.0 58.5 68.0

55.0 59.5 69.0 82.5

Table II—Enzymatic hydrolysis of ethanol delignified eucalypt wood Reducing sugars calculated as glucose, in % of the substrate (o.d.)

54.0 59.5 74.0

Enzymatic hydrolysis and scp production from solvent delignified eucalyptus globus l. biomass

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Figure II—Enzymatic hydrolysis of ethanol delignified pulps (Hydrolysis expressed as saccharification yields in relation to polysaccharides in substrate) SUBSTRATE 175○C, 30′ 175○C, 90′ 165○C, 120′

PROTEIN CONTENT, 16H HYDROLYSIS

% OF BIOMASS 40H HYDROLYSIS 40.1 36.4 39.6

40.8 39.5 41.5

Table III—Crude protein content of SCP enriched biomass 4. CONCLUSIONS Ethanol-water delignification produces pulps which are highly susceptible to enzymatic hydrolysis. Saccharification yields are not related to delignification level and approximately the same polysaccharide hydrolysis could be obtained for pulps with only 10% delignification (21.7% residual lignin). Growth of Geotrichum candidum and Saccharomyces cerevisiae could be made on previously enzymatically hydrolysed substrates and crude protein content in dried SCP enriched products was approximately 40%.

Energy from biomass

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Solvent treated eucalypt wood shows interesting promises as a substrate for enzymatic hydrolysis and for production of SCP-enriched products. 5. REFERENCES [1] MILLETT, M.A., BAKER, A.J. and SATTER, L.D., (1975), Biotechnol. & Bioeng. Symp. 5, 193–219 [2] SARKANEN, K.V., (1980), EUCEPA Symposium, Helsinki, 2–5 June 1980, 37–51 [3] SARKANEN, K.V. (1980), in: “Progress in Biomass Conversion”, Academic Press, NY, 127– 145 [4] HUMPHREY, A.E., (1979), Adv. Chem. Ser. 181, 25–29 [5] SHIMIZU, K. and USAMI, K., (1978), J.Japan Wood Res. Soc. 24, 632–637 [6] BELLAMY, W.D., (1976), presented at the 33rd General Meeting of the Society for Industrial Microbiology, August17 [7] PEREIRA, H. and M.T.COLAÇO, (1985), Biotechn. Lett., submitted for publication [8] COSTA, M.B., (1983), in: “Produção de Novas Proteinas e Utilização de Recursos Inexplorados. 12 Simpösio Nacional”, NOPROT 81, Lisboa, 160–163 [9] GOMIDE, J.L., (1978), Ph.D. Thesis, North Carolina State University

AKNOWLEDGEMENTS We aknowledge the help of Mário Filipe Oliveira, Isabel Miranda and Maria Rosa Resende in experimental work and of Baptista de Sousa in manuscript preparation.

ENHANCED BUTANOL-TOLERANCE IN MUTANTS OF CLOSTRIDIUM ACETOBUTYLICUM P.VALENTI, P.VISCA and N.ORSI Istituto di Microbiologia—Università di Roma “La Sapienza” P.le Aldo Moro 5–00185 ROMA (ITALY) Summary A butanol-tolerant mutant capable of growing in the presence of 20 g/l of butanol was obtained from Clostridium acetobutylicum. By comparison with the parent strain this mutant also gave a higher production of solvents in synthetic medium. Its morphological analysis showed a partial block of sporulation which appeared to be completely indipendent from ABE production.

1. INTRODUCTION Clostridium acetobutylicum is an anaerobic microorganism which in fermentation cultures normally produces acids and solvents. In the first step of the fermentation process the acids are synthetized and successively the conversion of acids to neutral solvents takes place (1). The solvents produced are represented by acetone, butanol and ethanol (ABE). As carbohydrate source, C. acetobutylicum can utilize corn mash and molasses but can also produce ABE from a great variety of carbon sources. The ratio of conversion to solvents varies between 20 and 40% (2). This low value of conversion is justified by the butanol toxicity and also by end-products. It is known that growth in the presence of alcohols produces a modification of cell structures and membrane associated enzyme activity (3). Fur thermore, it has been noticed that butanol produces on C. acetobutylicum a degeneration and lysis of swollen cigar shaped clostridial forms (4) which are associated with solvents production (5). The aim of this research was the selection of mutants of C. acetobutylicum NCIB 6445 capable of growing in higher concentrations of butanol.

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2. MATERIALS AND METHODS Strain and culture condition: C. acetobutylicum NCIB 6445 and its butanol-tolerant derivative, PV1, were grown under stringent anaerobic condi tions in an anaerobic glove box (Forma-Scientific, Mariettta, Ohio) at 30°C in a medium described by F.Monot et al. (2). The NCIB 6445 and PV1 strains were maintained at 4°C as freeze-dried spore preparations. Spores were activated by heat shocking at 75°C for 2′ followed by cooling on ice before inoculation. Selection of butanol-tolerant strains: the butanol-tolerant strain PV1 was derived from wild-type C. acetobutylicum NCIB 6445 by an enrichment pro cedure. Parent strain cultures were inoculated under anaerobic conditions in a medium to which were added different concentrations of butanol. After 24 hours the growth was evident only in the control culture without butanol, but after 48 hours a similar optical density was obtained also in the cultu re with 10g/l of butanol. This culture was transferred sequentially to fresh medium containing increasing amounts of butanol (up to 20g/l). After the seventh transfer, a selected strain capable of growing in 20g/l of butanol was obtained. Growth and morphology control: bacterial growth was measured in the liquid medium by optical density at 620 nm and by dilution plating method in TGY medium (tripticase 30g/l; yeast extract 20g/l; glucose 5g/l; agar 15g/l). During the fermentation process samples were taken at different times and microscopically examined for morphological characterization. Analysis of solvents: acetone, butanol and ethanol were determined by gas chromatography according to Barter et al. (6).

3. RESULTS Selection of butanol-tolerant mutants: butanol-tolerant mutants were obtained by the enrichment procedure described above. One of these mutants, strain PV1, was able to grow at the butanol concentration (20g/l) which was inhibitory to the parent strain. At the same temperature of growth (30°C) the maximum OD620 for PV1, at stationary phase, was higher than that obtained by the parent strain. Responce of C. acetobutylicum to butanol: fig. 1 presents results obtained with PV1 and parent strain in a medium with butanol added at different concentrations. It appears from this that the PV1 strain is more tolerant to the butanol toxicity and is able to grow up to 20g/l.

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Fig. 1: Growth of C. acetobutylicum 6445 (o) and PV1 (●) in presence of dif ferent concentrations of butanol. Production of solvents in synthetic medium: the production of solvents by both strains is shown in Fig. 2a and 2b. It can be noticed: –

the higher biomass produced by PV1 mutant strain

– the lower value of pH in the culture of mutant after 18 hours – the higher concentration of solvents produced by PV1 – the prolonging of the stationary phase of PV1 before the lysis. Effect of glucose concentration on production of solvents: different concentrations of glucose (2%; 4%; 6%; 8%; 10%) were added to the synthetic medium.

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Fig. 2: Production of solvents by C. acetobutylicum 6445 (A) and PV1 (B). Butanol (o), aceton (x), ethanol , pH (∆), biomass (●). The data obtained are summarized in fig. 3a and 3b and show that the efficiency of conversion of glucose into solvents was the same up to 4% of glucose for the parent strain and up to 8% of glucose for the mutant. Furthermore, the maximal production was obtained with the parent strain between 72 and 96 hours and between 24 and 48 hours for the mutant.

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Fig. 3: Efficiency of conversion of glucose to solvents by C. acetobutylicum 6445 (A) and by PV1 (B). Morphological characterization: the morphological aspects of both strains were monitored during batch fermentations. Significant differences in clostridial stages were not observed, but clostridial forms of mutant showed a later degradation and lysis. Moreover, the cultivation of both strains in sporulation medium (7), showed differences in the production of spores, PV1 beeing partially blocked as shown in fig. 4a and 4b.

Fig. 4a: C. acetobutylicum 6445

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Fig. 4b: C. acetobutylicum PV1

4. CONCLUSIONS By successive selection in synthetic medium plus butanol it was possible to isolate a PV1 tolerant mutant strain characterized by the following properties: – a higher biomass production – a higher and faster production of solvents – a more rapid decrease of the culture pH – a later degradation and lysis of clostridial forms. The data obtained with this mutant confirm that solvent production is connected with clostridial forms and suggest that a partial block of sporulation does not affect ABE production. ACKNOWLEGMENTS We thank dr. Vito Pignatelli, dr. Quinta Tardella, Mr. Lino Di Giuseppe and Mr Franco Sturba for chemical analysis and technical assistance. This work was carried out and supported by “Progetto Finalizzato Ener getica” CNRENEA GRANT ENEA N° 32.

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REFERENCES 1) B.Atkinson and F.Mavituna (1983): Biochemical engineering and biotechnology handbook p. 308–314. The Nature Press (USA and Canada). 2) F.Monot, J.R.Martin, H.Petitdemange and R.Gay (1982): Acetone and butanol production by Clostridium acetobutylicum in a synthetic medium. Appl. Environ. Microbiol. 44:1318–1324. 3) M.Fletcher (1983): The effects of methanol, ethanol, propanol and butanol on bacterial attachment to surface. J.Gen. Microbiol. 129:633–641. 4) A.Van der Westhuizen, D.T.Jones and D.R.Woods (1982) Autolytic activity and butanol tolerance of Clostridium acetobutylicum. Appl. Environ. Microbiol. 44:1277–1281. 5) D.T.Jones, A.Van der Westhuizen, S.Long, E.R.Allcock, S.J.Reid and D.R.Woods (1982): Solvent production and morphological changes in Clostridium acetobutylicum. Appl. Environ. Microbiol. 43; 1434–1439. 6) J.M.Barber, F.T.Robb, J.R.Webster and D.R.Woods (1979). Bacteriocin production by Clostridium acetobutylicum in an industrial fermentation process. Appl. Environ. Microbiol. 37:433–437. 7) S.Long, D.T.Jones and D.R.Woods (1984): Sporulation of Clostridium acetobutylicum P262 in a defined medium. Appl. Environ. Microbiol. 45: 1389–1393.

INFLUENCE DE LA NUTRITION AZOTEE SUR LA CROISSANCE ET LA PRODUCTION D’HYDROCARBURES DE L’ALGUE UNICELLULAIRE BOTRYOCOCCUS BRAUNII F.BRENCKMANN, C.LARGEAU, E.CASADEVALL et C.BERKALOFF Laboratoire de Chimie Bioorganique et Organique Physique—UA CNRS 456 E.N.S.C.P, 11, rue Pierre et Marie Curie—75231 PARIS CEDEX 05— FRANCE. Laboratoire de Botanique-Cytophysiologie Végétale—LA CNRS 311 E.N.S, 24, rue Lhomond—75005 PARIS—FRANCE. SUMMARY The influence of nitrogen nutrition on growth and hydrocarbon production of the green unicellular alga Botryococcus braunii was examined. It appears that nitrogen starvation is not an obligatory condition for a high hydrocarbon production ; in fact the highest productivities were observed during exponential growth. The initial nitrate concentration allowing a maximal hydrocarbon production, from air-lift batch cultures, was determined.

1. INTRODUCTION Grâce à un contenu élevé en hydrocarbures (1) l’algue verte unicellulaire Botryococcus braunii apparaît, a priori, comme un agent efficace de transformation de l’énergie solaire en énergie chimique (2,3). Dans le but d’optimiser les conditions de culture nous avons examiné, ici, l’in-fluence de la nutrition azotée sur la croissance de B. braunii et sur sa production d’hydrocarbures. 2. MATERIELS ET METHODES Une souche axénique (souche A) fournie par l’algothèque d’Austin (University of Texas) a été utilisée. La preparation des inocula; les cultures standard (batch air-lift); la détermination de la production de biomasse et du temps de doublement en phase exponentielle; l’analyse qualitative et quantitative des hydrocarbures ont été effectuées

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comme décrit précédemment (3, 4). L’analyse des nitrates du milieu a été réali-sée par HPLC (colonne Ionospher A Chrompack). La qualité de l’inoculum joue un rôle important dans l’évolution de la culture. Des tendances identiques, sur l’influence de l’azote, ont été observées à partir de divers inocula; cependant, seules des cultures menées en parallèle a partir d’un même inoculum sont strictement comparables. 3. RESULTATS ET DISCUSSION Les courbes de croissance de B. braunii pour trois concentrations initiales différentes en nitrate et les caractéristiques de la phase exponentielle de croissance (fig. I, Tab. I) suggèrent que le nitrate est l’élément potentiellement limitant des cultures en conditions standard (NO3− 200mg/1).

TABLEAU I—Caractéristiques de la phase exponentielle de croissance pour différentes concentrations initiales du milieu en nitrate (a). Concentration initiale NO3−mg/l

Durée de la phase exponentielle (j.)

200 (b) 6 1000 9 et+ 3000 9 et+ (a) Moyenne de deux expériences. (b) Concentration en nitrate des cultures standard.

Temps de doublement de la biomasse (j.) 1.88 2.07 2.06

On observe en effet que la durée de la phase exponentielle croît avec l’augmentation de la concentration initiale en nitrate du milieu. La durée de cette phase semble toutefois identique pour les deux concentrations en nitrate les plus élevées. Etant donné que les temps de doublement sont voisins, ceci indique que pour la concentration la plus élevée, le nitrate n’est plus l’élément responsable de l’arrêt de la phase exponentielle, arrêt qui pourrait être dû à un autre élément devenu à sont tour limitant, à moins qu’il ne s’agisse d’un métabolite rejeté dans le milieu et ayant atteint une concentration toxique. Il est important de noter que des concentrations aussi élevées que 3000mg/l ne sont pas inhibitrices pour la culture. Afin d’apporter la preuve formelle que l’azote constitue bien l’élé-ment limitant dans les conditions de culture standard, l’évolution en fonction du temps de la concentration des nitrates du milieu a été suivie pour une durée de culture de 24 jours. Les résultats montrent (fig. II) que l’absorption des nitrates se poursuit régulièrement et jusqu’à total épuisement du milieu pour 200 et 1000mg/l de concentration initiale. Pour 200mg/l, l’arrêt de la phase exponentielle coïncide (au temps 8 j.) avec l’apparition de la carence en nitrate. Bien que ceci soit moins net pour 1000mg/l, car le nombre limité de mesures possibles n’a pas permis de déterminer avec une grande precision ni le temps d’arrêt de la phase exponentielle, ni celui de l’épuisement du milieu, on peut cependant dire que dans ce cas les deux évènements se produisent dans la même zone de temps. Pour 3000mg/l, il

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est bien evident que l’arrêt de la phase exponentielle ne résulte pas d’une carence en nitrate. A l’issue de cette étude il est possible de dire que l’azote est bien pour les conditions de culture standard le facteur limitant, c’est-à-dire celui dont l’épuisement est responsable du ralentissement de la croissance. Cependant, après la disparition des nitrates qui détermine l’arrêt de la phase exponentielle la biomasse continue encore de croître; le poids de cette dernière atteint en effet en phase stationnaire une valeur 2 à 3 fois plus forte qu’à la fin de la phase exponentielle. Il est connu (5) que si la croissance est contrôlée en premier lieu par la concentration dans le milieu de culture d’un élément limitant, elle subit également le contrôle de la concentration intracellulaire (quota intracellulaire) de cet élément. Le taux de croissance en phase de ralentissement pour des cultures limitées en azote, et la durée de cette phase de ralentissement sont fonction du quota intracellulaire en azote. Le tableau II qui rapporte les teneurs en azote de la biomasse respectivement pour la phase exponentielle et pour la phase stationnaire montre que l’arrêt total de la croissance intervient lorsque cette teneur s’abaisse à 1 %. On notera que les teneurs intracellulaires en azote, aussi bien en phase exponentielle (5%) qu’en phase stationnaire (1%) sont faibles par rapport à celles rapportées pour d’ autres microalgues (Shifrin (6) enregistre pour 26 espèces de microalgues testées, des teneurs moyennes en azote de 8 % en phase exponentielle et de 2,5% en phase stationnaire). Cette particularité de B. braunii est à relier à ses teneurs élevées en hydrocarbures, ainsi qu’à l’importance de sa paroi externe qui ensemble constituent approximativement en phase exponentielle de 25 à 30% du poids sec de la biomasse.

TABLEAU II—Teneurs en azote organique de la biomasse pour différentes phases de la culture. Phase exponentielle N % poids sec Phase stationnaire ‘N % poids sec 5±1 Conditions de culture standard (concentration nitrate 200mg/1).

1.0±0.2

Cette étude fait ressortir l’importance très grande à la fois de l’azote externe (milieu) et de l’azote interne (cellulaire) sur la production de biomasse chez B. braunii. Il apparaît clairement (tableau III) que l’augmentation de la teneur initiale en nitrates permet d’accroître la quantité finale de biomasse produite.

TABLEAU III—Poids de biomasse finale (mg/l) pour des milieux de cultures a différentes concentrations initiales en nitrate (30 jours de culture). Concentration initiale KNO3 (mg/l) Poids de biomasse mg/l (a) 200 2700 1000 4800 3000 4500 (a) Moyenne de six experiences comportant chacune 2 cultures.

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Pour ce qui est des hydrocarbures il apparaît (tableau IV) que durant la phase exponentielle (7 j.) quelle que soit la concentration initiale en nitrate du milieu, la teneur en hydrocarbures se situe autour de 11%. Cette teneur croît ensuite et est d’autant plus élevée, après un même laps de temps, que la concentration initiale en nitrate est faible.

TABLEAU IV—Teneurs en hydrocarbures pour différentes concentrations initiales du milieu en nitrate et pour différents temps de culture. Concentration initiale en KNO3 (mg/l)

200 1000 3000

% hydrocarbures de la biomasse Expérience I (a) Expérience II (a) après 7 j. après 34 j. après 7 j. après 19 j. 9 11.6 13

19 17 13

12.5 12.5 11

17.5 13.5 11

(a) Moyenne de deux cultures.

Si l’on considère la production d’hydrocarbures (tableau V) en fonction de la concentration initiale du milieu en nitrate, il apparaît que les fortes concentrations conduisent à des productions d’hydrocarbures plus élevées. Ceci provient du fait que dans ces conditions la production de biomasse est plus importante et que même si la teneur en hydrocarbures est plus faible on obtient néanmoins, globalement, un gain en production d’hydrocarbures.

TABLEAU V—Production d’hydrocarbures (mg/l) pour différentes concentrations initiales du milieu en nitrate après un même temps de culture. Concentration initiale en KNO3 Expérience I (a) (après 34 Expérience II (a) (après 19 (mg/l) j.) j.) 200 1000 3000

470 598 592

234 265 249

(a) Moyenne de deux cultures.

Si l’on traduit ces résultats en terme de productivité (mg. d’hydrocarbures/g. de biomasse/jour) il apparaît que les productivités maximales en hydrocarbures s’observent pour la phase exponentielle et sont identiques (62mg/g/j) pour les concentrations initiales testées (pendant la durée de cette phase, l’azote n’est encore limitant pour aucune des cultures). Cette productivité baisse ensuite progressivement mais plus lentement que la productivité en biomasse. Ces résultats montrent que la synthèse d’hydrocarbures est plus importante en phase de croissance active quand les nitrates sont abondants dans le milieu, mais aussi qu’une carence en nitrate affecte moins la synthèse des hydrocarbures que celle des autres composants de la biomasse. Ceci se traduit au cours de la phase de deceleration de croissance par une augmentation de la teneur en hydrocarbures de la biomasse alors que la productivité en hydrocarbures baisse brusquement. (Un tel

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comportement est vraisemblablement assez général chez les microalgues pour lesquelles des accumulations de lipides en carence d’azote sont observées. Voir à titre d’exemple les données rapportées récemment (7) qui permettent de tirer les mêmes conclusions). Or, le seul chiffre significatif lorsqu’on a pour objectif la production d’hydrocarbures est celui de la productivité. Il est donc important de maintenir le plus longtemps possible la culture en phase exponentielle de croissance (productivité maximale) et donc d’utiliser des concentrations initiales en nitrate élevées. Pour les conditions de cultures expérimentées, cette con centration est de l’ordre de 1g/l (0.01 mole) de nitrate. REFERENCES 1) MAXWELL, J.R., DOUGLAS, A.G., EGLINTON, G. and Mac CORMICK, A. (1968) Phytochem. 7, 2157. 2) LARGEAU, C., CASADEVALL, E. and DIF, D. (1980) Energy from Biomass p.653 3) CASADEVALL, E., DIF, D. , LARGEAU, C., GUDIN, C., CHAUMONT, D. and DESANTI, O. (1985) Biotechnol. Bioeng. 27 (in the press). 4) LARGEAU, C., CASADEVALL, E., BERKALOFF, C. and DHAMELINCOURT, P. (1980) Phytochem. 19, 1043. 5) DROOP, M.R. (1973) J. Phycol. 9, 264. 6) SHIFRIN, N.S. (1980) Ph. D. Thesis (MIT). 7) PIORRECK, M., BAASCH, K-M. and POHL, P. (1984) Phytochem. 23, 207.

FIGURE I Courbe de croissance NOTA: A la difference des rapportés dans le III qui sont la de plusieurs

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expéri-ces courbes représen-les données d’une seule différente de celdont les résultats figusur les tableaux IV et V.

FIGURE II Evolution de la concentration en nitrate au cours de la culture Remerciements: Ce travail a été finance en partie par le programme Energie Solaire de la C.E.E. (Projet E “Energy from Biomass”) contrat n° ESE-R-022 F.

INFLUENCE OF LIGHT INTENSITY ON HYDROCARBON AND TOTAL BIOMASS PRODUCTION OF BOTRYOCOCCUS BRAUNII. RELATIONSHIPS WITH PHOTOSYNTHETIC CHARACTERISTICS F.BRENCKMANN, C.LARGEAU, E.CASADEVALL, B.CORRE and C.BERKALOFF* Laboratoire de Chimie Bioorganique et Organique Physique, UA CNRS 456, ENSCP 11 rue Pierre et Marie Curie, 75231 PARIS, Cedex 05, France *Laboratoire de Botanique-Cytophysiologie Végétale, LA CNRS 311, ENS, 24 Rue Lhomond, 75005 PARIS, France Summary “Air lift” batch cultures of the hydrocarbon-rich alga Botryococcus braunii were carried out under different light intensities. The influence of illumination on total biomass, hydrocarbons, cell ultrastructure , pigments and photosynthetic activity was determined. Adjustement in light intensity provides, in this type of cultures, a large improvement in hydrocarbon production.

1. INTRODUCTION The green unicellular alga Botryococcus braunii exhibits unusually high hydrocarbon levels (1) and values as high as 44 % were observed from laboratory cultures (2,3). This alga was generally considered (4) as a slow growing species (mean generation time one week); however, “air lift” cultures (2,3) afford a large improvement in growth rate (generation time ca 2 days). A systematic examination of the influence of various parameters on hydrocarbon production was therefore undertaken from “air lift” batch cultures. In the present work we examined the influence of light intensity on the productivity and the photosynthetic characteristics of B.braunii. 2. MATERIALS AND METHODS An axenic strain (strain A) supplied by the Austin Culture Collection (University of Texas) was used in this work (It provides fairly large productivities (5,6) under unoptimized “air lift” conditions). Air lift batch cultures were carried out, using a CHU

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13 modified medium, as previously described (3). All the reported results correspond to cultures which remained axenic. Variations in biomass; determination of doubling time; identification and quantitative analysis of hydrocarbons; pigment analysis; measurement of 02 evolution under saturating light and CO2; ultrastructural examination using tramission electron microscopy were carried out as previously reported (3,7). Light intensity within culture vessels was determined using a LI 183B Quantum Radiometer Photometer, fitted with a LI 193SB spherical sensor. The quality of the inoculum, obtained by unaerated and unshaked cultures (3), is important for the evolution of the batch. Identical trends, regarding the influence of light intensity, were observed from various inocula; however, only parallel cultures started from same inoculum can be strictly compared and afford a high degree of reliability. 3. RESULTS 3.1. Biomass Biomass production strongly depends on light intensity during “air lift” batch cultures (continuous illumination) (Fig.I). No exponential growth is observed with I4; in fact a linear increase in biomass takes place, after a short lag phase, during all the experiment. An exponential growth occurs in the other cultures but the mean biomass doubling time increases lightly when light intensity is enhanced: I3 (2.1 days), I2 (2.3 days), I1 (2.55 days). The differences in biomass production between these three cultures are therefore fairly low in the first days; but after they increase considerably, especially from day 15, since I1 is then characterized by an important lowering in biomass while I2 and I3 are still actively growing. 3.2. Hydrocarbons Light intensity does not affect the structure of the hydrocarbons synthesized by B. braunii (mainly C27, C29 and C31 alkadienes); however large quantitative variations are noticed (Table I). The highest production and the highest hydrocarbon level relative to total biomass are achieved with I3. Under high intensity (I1) a large decrease in the amount of hydrocarbons recovered from the algal biomass occurs at the end of the culture; a low hydrocarbon level is also obtained at this stage. With low intensity (I4) a regular but slow hydrocarbon production is observed; I4 cultures are characterized by a low hydrocarbon level. 3.3. Cell ultrastructure (Fig.II) I1 cells show a small and disorganized chloroplast (C) with very few starch grains; the cytoplasm contains numerous vacuoles (V) and hydrocarbon inclusions (IH); lysis or complete disorganization is observed in many cells. I2 and I3 cells exhibit a larger and more organized chloroplast containing starch grains (S); vacuoles and cytoplasmic inclusions are still important; a large amount of external hydrocarbons (EH) is noticed in outer walls (TLS) of I3. I4 cells contain a well developed chloroplast with a high degree

Energy from biomass

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of organization and few starch grains; vacuoles, hydro carbon inclusions and external hydrocarbons are less important. 3.4. Pigments I1 cultures become rapidly yellowish and a nearly complete bleaching occurs at the end of the batch, while I4 cultures are still deep green. Quantitative extraction of B. braunii pigments is difficult because of the presence of outer walls; pigment content was therefore estimated from in vivo OD measurement at 678 nm (chl a) and 655 nm (chl b). With high light intensities (I1 and I2) the total amount of chl a tends to decrease during the last stages of the culture (Fig.III), especially in I1. On the contrary a continuous rise is noticed in I3 and I4. When chl a level relative to biomass is considered (Fig.IV) a maximum appears, for I1, I2 and I3, during the exponential stage; afterwards a sharp decrease, lightly more important in I1, takes place. With 14 a high level is maintained during all the experiment. The same general features are obtained from chl b. In fact, for a given culture the chl a/chl b ratio does not significantly varies during the batch. When chl relative abundances are compared in the different cultures it appears that reduction in light intensity is associated with decrease in chl a/chl b ratio revealed by lowering in the OD 678/OD 655 ratio: I1 (1.32), I2 (1.22), I3 (1.13), I4 (1.08). On the other hand low intensity cultures (14) are characterized by considerably higher pigment levels at any stage of the batch (Fig.IV) while only small differences are noticed between I1, I2 and I3. 3.5. Photosynthetic activity Chl photosynthetic capacity (02 evolved.min−1 amount−1 of Chl) was determined, under saturating light (see Methods), at various stages of the batch. With I1, I2 and I3 this activity markedly decreases after day 6 (table II) ; on the contrary high values are always maintained in I4. For a given culture time the capacity is enhanced when light intensity is reduced. 4. DISCUSSION Light intensity plays a major role on total growth of B.braunii; the orientation of the agal metabolism (hydrocarbon and chl levels relative to biomass) is also strongly affected. Light is limiting in 14, as shown by the lack of exponential phase and by prolonged linear growth. However, adaptation of B.braunii to light limitation occurs: total biomass and hydrocarbon productions after 21 days are only about three times and four times smaller, relative to I3, while energy supply was divided by five. This adaptation is more efficient for total biomass than for hydrocarbons. Adaptation to light limitation is associated with increase in chloroplast size and organization. The amount and the photosynthetic capacity of chl are also enhanced relative to I1, I2 and I3, especially during the last stages of the batch. (The former feature was generally observed (8,9) while the latter was only noticed (9) in few species). Owing to these two increases, the

Influence of light intensity on hydrocarbon and total biomass production of botryococcus braunii

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photosynthetic capacity of the cultures (O2 evolved.min−1l−1 of culture under saturating light) shows a considerable enhancement in I4. Such a property is important in view of growth under natural light: during low intensity periods the algae will build a highly efficient photosynthetic apparatus, so that a very important photosynthesis will take place as soon as the cells will be submitted to high light (photoinhibition will be then observed only if prolonged illumination≥11 occurs) . A large photoinhibition takes place with I1 after few days of culture; the detrimental effect of this high intensity is still more pronounced for hydrocarbon production than for total biomass. Moreover, important decreases in biomass and hydrocarbon are observed at the end of the cultures, associated with cell lysis. Many cells exhibit also small and disorganized chloroplasts. Due to degradation by photooxidation, chl total amount and level relative to biomass sharply decrease at the end of the culture; in addition low chl photosynthetic activities are achieved. Photoinhibition, however less marked, also occurs with I2. I3 is optimum both for total biomass and hydrocarbon production. In spite of the thick colony matrix surrounding B.braunii cells, this optimal value is close of the one recently reported for various unicellular algae (9). I3 affords the largest amount of hydrocarbonrich biomass; adjustement of light intensity provides therefore an important improvement (ca×2.3) in hydrocarbon production relative to I2 (intensity generally used in previous unoptimized “air lift” batch cultures). ACKNOWLEDGMENTS. This work was supported by the EC Solar Energy Program, Project E “Energy from biomass, contract number ESE-R-022 F. Influence of light intensity on “air lift” batch cultures of B.braunii. 11 (740µEm−2s−1,——); I2 (intensity generally used in previous unoptimized cultures, 470µE m−2s−1, …); I3 (235µE m−2s−1,—); 14 (47µE m−2s−1,—·—·).

Figure I: biomass.

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Figure III: total amount of Chl a.

Figure IV: Chl a level relative to biomass.

Influence of light intensity on hydrocarbon and total biomass production of botryococcus braunii

Intensity

815

Hydrocarbon content (mg.l of culture) Hydrocarbon level (% of total biomass) A B A B

I1 I2 I3 14

103 165 147 53

42 310 710 175

13.0 13.7 12.8 7.7

7.0 15.0 29.0 9.5

Table I: Influence of light intensity on hydrocarbon production of B.braunii during “air lift” batch cultures. Cells harvested after 8 days (A) and 21 days (B) of culture Intensity I1 I2 I3 I4

chl photosynthetic capacity (n moles O2.min−1chl−1) 1 2 3 27.0 32.2 31.6 44.0

24.2 26.1 28.0 53.7

3.6 11.0 13.5 47.7

Table II: Variation in chl photosynthetic capacity during “air lift” batch cultures. Cells harvested after 6 days (1), 9 days (2) and 16 days (3) (678 nm OD was adjusted at 0.1 before measurements).

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Figure II: Transmission electron microscopy; cells harvested after 13 days of culture under I1 and I4.

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References 1. MAXWELL, J.R., DOUGLAS, A.C., EGLINTON, G. and MAC CORMIKC, A. (1968). Phytochem, 7, 2157. 2. LARGEAU, C., CASADEVALL, E. and DIF, D. (1980). In Energy from Biomass (PALZ, W., CHARTIER, P. and HALL, D.O. Ed), 653. 3. CASADEVALL, E., DIF, D., LARGEAU, C., GUDIN, C., CHAUMONT, D. and DESANTI, O. (1985). Biotechnol. Bioeng. 27 (in the press). 4. BELCHER, J.H. (1968). Arkiv. Mikrobiol. 61, 335. 5. CHIRAC, C., CASADEVALL, E., LARGEAU, C. and METZGER, P. (1982). C.R. Acad. Sci. Paris, 295 III, 671. 6. CHIRAC, C., CASADEVALL, E., LARGEAU, C. and METZGER, P. (1985). J. Phycol. (in the press). 7. LARGEAU, C., CASADEVALL, E., BERKALOFF, C. and DHAMELINCOURT, P. (1980). Phytochem. 19, 1043. 8. FALKOWSKI, P.G. and OWENS, T.G. (1980). Plant Physiol. 66, 592. 9. RICHARDSON, K. and BEARDALL RAVEN, J.A. (1983). New Phytol. 93, 157.

SCREENING OF WILD STRAINS OF THE HYDROCARBON-RICH ALGA BOTRYOCOCCUS BRAUNII. PRODUCTIVITY AND HYDROCARBON NATURE P.METZGER* , E.CASADEVALL* , A.COUTE** and Y.POUET* Laboratoire de Chimie Bioorganique et Organique Physique—UA CNRS 456 E.N.S.C.P. 11, rue P. et M.Curie—75231 PARIS CEDEX 05—FRANCE. **Laboratoire de Cryptogamie—LA CNRS 257 Museum National d’Histoire Naturelle 12, rue Buffon—75005 PARIS Summary New strains of the hydrocarbon-rich microalga, Botryococcus braunii were isolated from various samples collected in Australia, France, IvoryCoast, Morocco and West Indies. On the basis of the nature of the hydrocarbons produced, this screening establishes the existence of two races in B. braunii. Each race produces a well-defined hydrocarbon class all along the growth: straight-chain alkadienes and trienes, odd numbered from C23 to C31 (the A race) or triterpenic hydrocarbons of general formula CnH2n−10, 30≤n≤37, termed botryococcenes (the B race). For a same race and depending on the strain origin, variability occurs for the composition of the hydrocarbon mixture: cis-trans isomerism and presence of trienes for the A race, various botryococcene compositions for the B race. The hydrocarbon content of these new strains (A and B races) is very high, from 20 to 52% of dry wt. With the adjustement of some factors (nitrate supply, size of the inoculum) an hydrocarbon content of 1.35 g/l for a 120 1 culture was obtained with a B strain cultivated under semi-protected conditions.

INTRODUCTION On the basis of observations carried out on samples collected in nature, some authors suggested that the colonial alga B. braunii could produce two different types of hydrocarbons at different stages of the growth (1). Unbranched linear alkadienes and trienes, odd-numbered from C25 to C31 would be produced by green cells during active growth, when triterpenic hydrocarbons of general formula CnH2n−10, with 30≤n≤37, termed botryococcenes would originate from orange resting state cells. Up to now the

Screening of wild strains of the hydrocarbon-rich alga botryococcus braunii

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strains available from culture collections derive from a same sampling (Scotland); whatever growth state, they produce only alkadienes. The present screening was undertaken from wild samples so as to isolate botryococcene-producing strains and to test the productivity of new strains grown in laboratory. MATERIAL AND METHODS The origins of the samples are given in tables I, II and III. When sampling was performed during blooms, enough biomass was obtained to analyze directly hydrocarbon content (Australia, West Indies and France—Sanguinet; B.braunii colonies accounted for more 90 % of the biomass). When colonies were in too low number relatively to the whole phytoplankton of the sampling, only isolation (on agarized CHU 13 medium) and culture were carried out (2) (Ivory-Coast, France-Morvan and Morocco strains). Isolation of unialgal and fungus free B. braunii colonies fell with the Australian and Sanguinet samples. The composition of the culture medium, the batch air-lift conditions, the determination of biomass concentration, the extraction and the purification of hydrocarbons and their GC/MS analyses have been previously described (2). For the 120 1 cultures, an aquarium of the following dimensions was employed: width 0.2 m, length 1.3 m, height 0.6 m. Aeration vas performed with air−1 % CO2 filtered on Millipore prefilter, at a rate of 10 1.h−1 per liter of medium; temperature 27°±1; continuous illumination (470 µ.E.m−2.s−1). RESULTS AND DISCUSSION 1—Considering the type of compounds up to now produced in laboratory cultures, the algae were separated into two categories: those yielding botryococcenes (table II) and those yielding unbranched alkadienes (table III). No variation of the hydrocarbon type was observed neither along the growth, nor in resting state. Moreover, West Indies strains continue to produce botryococcenes, as in nature (table I). So it must be concluded that two races of B. braunii exist, each synthesizing a well-defined type of hydrocarbons. 2—For a same race, some variabilities in hydrocarbon composition were observed, depending on the strain origin, both in nature (table I) and in laboratory culture (tables II and III). For the A race, table III, the Grosbois strain showed the particularity to synthesize, beside cis alkadienes, trans isomers never detected up to day in B. braunii extracts (isomerism occurs on the double bond located into the chain), when the other strains produced only cis hydrocarbons; number and amount of trienes depended also on the strain origin. For the B race a very large variability was observed. So the West Indies strains produced C33 and C34 hydrocarbons in nature (table I) when they yielded essentially C34 hydrocarbons in laboratory cultures (table II); the Ivory-Coast strain exhibited a predominance of C32 and C33 hydrocarbons in laboratory culture. Then, it appears that for a same race, different genetical populations exist and at the least for the B race, that physicochemical factors are also at the origin of chemical variations.

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3—After three weeks of growth and with the same culture conditions, the Ivory-Coast and Morocco strains gave the highest biomass production. Nevertheless, the Martinique strain was the most productive (1.05 g of hydrocarbons/1), with a level near 38 % of dry wt., value similar to those noticed for collected samples in this study and by most of the authors (3). 4—The relative slow growth of B. braunii (mean doubling time of 2.3 days for the two races (2), during the exponential phase), and thereafter an unfavounable concurrence in open air of fast growing microorganisms appeared for some authors the major disadvantage to use B. braunii as hydrocarbon producer (4).

TABLE I—GC/MS analyses of botryococcenes from collected B. braunii samples. Origins and dates of the samplings. C H

n 2n−10 Australia Darwin n= November 1981

France Sanguinet August 1983

West Indies Martinique La Guadeloupe Manzo May Chateaubrun May 1982 1983

C31 19.1 C32 78.7 0.8 39.8 36.3 C33 C34 48.3 52.4 44.6 C35 2.6 35.7 4.3 5.9 C36 C37 11.3 0.4 2.4 n.i* 1.3 2.2 3.1 10.8 % of dry 29.2 34.5 35.8 24.1 wt. *n.i.: compounds not identified owing to a poor resolution of the GC peaks; nevertheless their retention times are different from those of alkadienes and trienes.

TABLE II—GC/MS analyses of botryococcenes extracted from cultivated B. braunii strains, dry biomass and hydrocarbon productions CnH2n−10 Ivory-Coast Taabo West Indies n= Guadeloupe Chateaubrun Martinique La Manzo C30 C31 C32 C33 C34 C35 C36 C37

1.0 1.2 41.1 54.7 2.0

0.5

2.7 86 0.6 10.1 0.6

81.3 15.2 3.0

Screening of wild strains of the hydrocarbon-rich alga botryococcus braunii

Dry biomass g/l Hydrocarbons g/l % of dry wt.

3.50 0.70 20

821

2.30 0.85 37.2

2.8 1.05 37.6

TABLE III—GC/MS analyses of alkadienes and trienes extracted from cultivated B. braunii strains from various origins; dry biomass and hydrocarbon production. CnH2n−2 CnH2n−4

E (Morv \ France (Morvan) Chaumeçon Grosbois

C23H44

0.6

C25H48

2.0

C27H52

13.0

C27H50 C29H56

2.0 67.5

C29H54 C31,H60 Dry biomass g/l Hydrocarbons g/l % of dry wt.

3.5 11.4 1.40

Morocco (Atlas) …j Oukaimden

0.3; 0.6 (trans) 2.3; 8.8 (trans) 4.1; 18.0 (trans)

Culture -,—.. Collection Austin— Texas USA

traces

traces

traces

1.0

9.7

11.0

1.1 75.9

62.0

11.1 1.5

6.3 7.0 3.75

1.0 25.0 2.80

0.73

0.375

0.75

0.56

52.1

25.0

20.0

20.0

25.1; 29.7 (trans)

TABLE IV—Growth of a botryococcene-producing strain for a 120 1 culture in a batch air-lift system (semi-protected conditions) . Hydrocarbon production and content. Culture duration (days) Extra KNO3 supply Dry biomass Botryococcenes mg/1 mg/1 mg/1 % of dry wt. 0 1 3 6 8 10 13 15 *Initial concentration 200 mg/1.

*

100 200 200

343 428 782 1347 1740 2155 2800 3000

116 282 443 660 812 1110 1350

27 36 33 38 38 40 45

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In sharp contrast, data concerning the culture of the most productive strain (La Manzo) in a 120 1 system are very promising for its culture in semi-protected conditions. In a first experiment, the culture was conducted f rom a low initial biomass concentration (50 mg/1) , and without extra nitrate supply. In these conditions, contamination of the culture medium by blue-green algae and Chlorella appeared detrimental after a six week period (hydrocarbon production: 0.5 g/l). The second experiment (table IV) was initiated with an high biomass concentration in the inoculum (initial biomass of the culture: 0.34 g/l) and nitrate was added when the medium was depleted. So, contaminations were negligible and a content of 1.35 g of botryococcenes per liter of culture could be achieved after 15 days (biomass concentration 3.0 g/l; hydrocarbon level 45%). An exponential phase was observed up to 4 days with a mean doubling time in biomass of c.a 2.5 days; then the growth was linear up to 13 days. CONCLUSION The screening of B. braunii wild samples has demonstrated that this alga consists of two physiological races, each producing either alkadienes or botryococcenes. The two races exhibit a very large chemical variability, depending on the geographical origin of the samples. Moreover recent developments show that other new strains can produce compounds as different as long chain fatty alcohols or polyterpene derivatives. This variability could broaden the use of the algae as new material and oil producers. Concerning the possibility of growing B. braunii in view to economical prospects, the results obtained in laboratory with a 120 1 batch air-lift system show that B. braunii culture in open air is not unrealistic. REFERENCES 1. BROWN A.C., KNIGHTS B.A. and CONWAY E, Hydrocarbon content and its relationship to physiological state in the green alga B. braunii (1969) Phytochem. 8, 543–547. 2. METZGER P., BERKALOFF C., CASADEVALL E. and COUTE A, accepted for publication in Phytochemistry (1985). 3. WAKE L.V. and HILLEN L.W, Nature and hydrocarbon content of blooms of the alga B. braunii occuring in Australian freshwater lakes, (1981) Aust. J. Mar. Freshwater Res. 32 , 353– 367. 4. WOLF F.R., B. braunii an unusual hydrocarbon-producing alga (1983) Appl. Biochem and Biotechn. 8, 249–260.

CHROMATOGRAPHIC STUDIES OF CRUDE OILS FROM WOOD D.MEIER, R.DÖRING and O.FAIX Federal Research Center for Forestry and Forest Products, Institute of Wood Chemistry and Chemical Technology of Wood Summary Product oils derived from the direct thermochemical conversion of wood have been analyzed and characterized using one liquid and two gas chromatographic methods. High Performance Gel Permeation Chromatography (HPGPC) was applied to achieve a separation according to molecular size. Capillary gas chromatography was used for the separation and quantification of single components in the crude oil. A packed column was used to determine the boiling point distribution. All methods applied turned out to be suitable for the chemical comparison of oils from different feedstocks and processes.

1. INTRODUCTION Wood can be converted to an oil using reducing gases (carbon monoxide, hydrogen), high temperatures and pressures as well as suitable catalysts. The product oil is always a complex mixture of degradation products of the different wood components: cellulose, hemicelluloses and lignin. The most common methods used to characterize biomass or fractions of them have been GC/FID or GC/MS (1–3). SESC-fractionation and gel permeation chromatography have only been used to a less extent (4). No standard methods are available for the characterization of the biomass oils. Hence, the results of different working groups are difficult to compare. Therefore, in this study three chromatographic methods, from which one works in the liquid phase and two in the gas phase, were studied to improve the chemical characterization of product oils from biomass feedstocks. 2. LIQUID CHROMATOGRAPHY The effectivity of the thermochemical treatment of biomass can be measured by the determination of the molecular weight (MWt) distribution of the oil produced. The lower the molecular weight the better the degree of degradation which is an important parameter for the further processing of the oil. Figure I shows the MWt’s of different biomass oils which were produced under the same conditions and demonstrates the influence of the starting material.

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3. GAS CHROMATOGRAPHY High resolution capillary gas chromatograph (HRGC) is a very suitable method to separate and quantify single components of oil fractions. Figure II demonstrates the separation of the phenolic fraction of two biomass oils. The chromatographic data of the reference phenols can be used to calculate the amounts of each component. A packed GC column was used to determine the boiling point distribution according to ASTM-method D 2887–73. This method, primary developed for the analysis of petroleum products, has been proven in this study to be also practicable for oils from biomass. An example is shown in Figure III, where the influence of different catalysts on the boiling point distribution curve is demonstrated. ACKNOWLEDGEMENT This work was financially supported by the Federal Ministry of Food, Agriculture and Forestry, project number 81 NR 006. REFERENCES (1) RUSSELL, J.A., MOLTON, P.M. and LANDSMAN, S.D. (1983). Chemical comparisons of liquid fuel produced by thermochemical liquefaction of various biomass materials. Alternat. Energy Sources 1980, 3, 307. (2) SCHIRMER, R.E., PAHL, T.R. and ELLIOTT, D.C. (1984). Analysis of thermochemicallyderived wood oil. Fuel, 63,368. (3) BOOCOCK, D.G.B., KALLURY, R.K.M.R. and TIDWELL, T.T. (1983). Analysis of oil fractions derived from hydrogenation of aspen wood. Anal. Chem., 55, 1689. (4) DAVIS, H.G. (1983). Direct liquefaction of biomass, final report and summary of effort 1977– 1983. Lawrence Berkely Laboratory, LBL16243.

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Figure I Standardized MWtdistribution curves of oils from different lignocellulosic feedstocks

Figure II Capillary gas chromatograms of phenolic reference substances and

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phenols of the oils from straw and lignin

Figure III Influence of catalysts on the boiling point distribution curves of oils from beech wood which were produced under similar reaction conditions

METHYL ESTERS OF TALLOW AS A DIESEL COMPONENT D.W.RICHARDSON, R.J.JOYCE, T.A.LISTER and D.F.S.NATUSCH Liquid Fuels Trust Board, wellington, New Zealand Summary A series of investigations has been undertaken to assess the viability of including the methyl esters of tallow as a component of New Zealand’s diesel fuel. The investigations show that there is a surplus of tallow available for this use; that the monoglyceride content of the resulting ester must be limited to very low concentrations; and that the fuel properties of a 10% v/v blend are essentially the same as those of the diesel component of the blend. The costs of producing tallow methyl esters as a blendstock are considered to be comparable to those for the production of conventional diesel fuel, provided that a large scale esterification plant is established and that a good return is received for the co-produced glycerol. Preliminary engine test results indicate that 10% and 20% v/v blends will perform as well as neat diesel fuel, but endurance testing and lubricant quality aspects are yet to be determined. The ignition quality of blends is significantly better than that of diesel. Overall it would appear that the use of tallow methyl esters as a diesel extender, at 10% v/v in the diesel, could be attractive in countries where large amounts of tallow are produced and where cold temperatures (less than −10 degrees C) are not encountered.

1. INTRODUCTION The production and use of alternative diesel fuels is particularly pertinent to New Zealand since, to date, all the alternative fuels which have been introduced (CNG, LPG and Mobil synthetic petrol) are essentially petrol alternatives. Thus there is a potential imbalance between the supply of fuels for refined petrol and diesel. A great deal of attention has been given, worldwide, to the possibility of using plant oils and animal fats as diesel fuel replacements or extenders. Such usage is seen to be attractive in many countries because these materials are locally available and are an essentially renewable resource. Because New Zealand’s agriculture is largely based on animal production (meat and wool) rather than on crop production, animal fats are the only significant triglyceride resource available for potential use as a diesel substitute or extender.

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In order to establish the feasibility of utilising tallow to extend diesel supplies, the Liquid Fuels Trust Board has implemented a programme designed to: 1. Establish the availability of tallow. 2. Identify an appropriate technology for the esterification of tallow. 3. Define the performance characteristics of diesel engines fuelled with tallow ester/diesel blends. 4. Identify strategies for the introduction of tallow esters into the nation’s diesel supply. The results of this programme, which is due for completion in 1986, are discussed in the following sections. 2. THE TALLOW RESOURCE 2.1 TALLOW PRODUCTION New Zealand currently exports about 85,000 tonnes of inedible tallow per annum. This is equivalent to about 7% of the current national automotive gas oil demand. Improvements in tallow recovery methods and an increase in the proportion of trimmed meat produced by the meat processing industry, is expected to increase the available inedible tallow to about 12% of the equivalent diesel demand by the end of this decade (1). 2.2 TALLOW QUALITY There are eight identifiable grades of tallow produced in New Zealand. These are: edible tallow, margarine grade tallow, three bleachable inedible tallows, and three unbleachable inedible tallows (1). The bulk of the inedible tallows, which are the tallows most likely to be utilised for tallow ester production, are produced in three grades (two bleachable and one unbleachable), amounting to about 80% of total tallow production. These inedible tallows, in aggregate, have weighted averages of 3.3% Free Fatty Acids; 0.9% unsaponifiables; and an Iodine Value of 47. These are suitable qualities for esterification. 3. PRODUCTION OF TALLOW ESTERS 3.1 ESTERIFICATION The process chosen for the production of tallow methyl esters can be divided into a number of steps. The raw tallow is first treated with sodium hydroxide solution to neutralise the free fatty acids which are then removed by centrifuging. A two stage base catalysed esterification process, with glycerol removal at the end of each stage, is then carried out. Dry ingredients are used and the reaction is carried out at methanol reflux temperature. A 2x excess of methanol is used. The crude ester product is heated under vacuum to remove the excess methanol, which is then recycled. The product is then washed three times to remove water soluble

Methyl esters of tallow as a diesel component

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contaminants (glycerol, catalyst residues, soaps, and methanol). It is then bleached, with an acid activated Fuller’s earth to remove mono and diglycerides, colouring matter, and some of the unsaponifiables. The product is finally filtered and sent to store. The mono and diglyceride content of the finished ester is less than 0.05% w/w. The resulting crude glycerol by-product is then processed to remove water, methanol and other contaminants. 3.2 PRODUCTION COSTS Production cost estimates (2) have been developed for two plant sizes; a 1,000 litre/hour plant annexed to an existing meat works, and a 10,000 litre/hour centralised plant in a stand alone configuration. Capital costs are estimated to be NZ$4.7 and NZ$17.4 million respectively. The capital and operating costs of production from these plants, including a glycerol by-product credit, are shown in Table II. To be competitive with diesel fuel costs (NZ$510/te), the delivered cost of tallow must be less than NZ$325 and respectively. All the above costs are in 1983 dollars. It is apparent from these figures that only the larger plant could produce tallow methyl esters at a cost competitive with that of diesel. Furthermore it is clear that the economic viability of tallow ester manufacture depends critically on the value of the by-product glycerol. Tallow prices are however not stable and long term averages will probably need to be used to measure the viability of the use of esters as diesel extenders. 4. PROPERTIES OF TALLOW ESTER/DIESEL BLENDS 4.1 PROPERTIES OF TALLOW ESTERS Table I lists typical inspection data from six batches of tallow ester. The concentrations of water, methanol, alkali metals and monoglyceride content were specified at maxima of 0.1%, 0.1%, 1.0 ppm, and 0.05% respectively. 4.2 PROPERTIES OF TALLOW ESTER/DIESEL BLENDS Table I also lists the inspection data of the esters with a typical winter grade diesel fuel and with 10% and 20% v/v blend of ester in diesel fuel (3). Blend volatility, low temperature properties and stability are discussed below. 4.2.1 Volatility. The distillation data (3) of the ester/diesel blend demonstrates the bulking effect that the ester has on the diesel. Thermogravimetric analysis (4) of both the ester and the blend damonstrates that there is a gradual but continuous loss of residue, to approximately zero, with rising temperature (to 300 degrees C). These analyses suggest that long term crankcase lubricating oil dilution and general engine fouling could occur (4).

Energy from biomass

830

4.2.2 Low temperature properties. The low temperature properties of the blends (3), as indicated by Cloud Point and Cold Filter Plugging Point, are concentration dependant. These inspection data are given in Table III. 4.2.3 Blend clarity. The initial samples of ester used in blending tests were not limited in monoglyceride content. Since monoglycerides are only sparingly soluble in diesel fuel they precipitate if present at concentrations greater than about 0.005% monoglyceride in the ester/ diesel blend (5). [Bleaching the ester with acid activated Fuller’s earth reduces the monoglyceride content of the ester to less than 0.05% w/w (6).] 4.2.4 Blend stability. Tests are currently under way to determine appropriate concentrations of anti-oxidant, biocide and low temperature flow improvers which will enable stored blends to achieve similar storage properties to those of conventional diesel fuel. 5. ENGINE TESTING 5.1 COMBUSTION PERFORMANCE OF BLENDS 5.1.1 Cetane Number. The cetane number (ignition delay) of the neat tallow esters and of 10% and 20% v/v blends of ester in diesel fuel have been measured using a single cylinder version of the Perkins 4.236 engine (4). The results are shown in Table IV. An improvement in ignition delay is apparent. 5.1.2 Cylinder pressure analysis. The improved ignition delay associated with ester/diesel blends results in a reduction in the rate of pressure rise within the cylinder. This leads to a corresponding decrease in combustion noise. A reduction in peak cylinder pressure is also noted. The differences between engine performance with diesel fuel and with the blends are not great, and lie within the accuracy limits of the measurement procedures. These test bench results indicate that the tallow ester/diesel blends give an improvement in combustion performance compared with diesel. However the differences may not be large enough to be distinguishable under normal operating conditions. 5.2 ENGINE PERFORMANCE 5.2.1 General. Power output, fuel consumption and emissions were measured over a wide range of loads, speeds and injection timings. The results showed that power output and fuel consumption figures are similar for the blends and for diesel fuel. Only in the case of the neat ester is there a clear trend towards higher fuel consumption. The neat ester has a net calorific value about 10% lower than that of diesel fuel, but for the 10% and 20% v/v blends the calorific value is only 1% and 2% lower respectively, and is unlikely to be noticeable under normal operating conditions. The sensitivity of the engine to injection timing changes was not noticeably altered by the use of the blends. A general trend towards a reduction of HC, CO, NOX and smoke emissions with increasing ester content of the test fuel was observed. however only in the case of neat ester fuelling are such differences significant. Emissions under idling conditions are not noticeably different for the blends and diesel.

Methyl esters of tallow as a diesel component

831

5.2.2 Cold start performances. A vehicle application version of the Perkins 4.236 engine was used to compare the cold start performance of 10% and 20% v/v blends of ester with diesel. Difficulties were experienced during the cold start tests and no firm conclusions on cold start behaviour can be reached. It is concluded that further work should be undertaken. 5.3 CRANKCASE OIL DILUTION Dilution rates and the effects of dilution in the crankcase oil when using the 10% and 20% v/v blends, have been compared with diesel fuel, using the single cylinder Perkins 4.236 engine. A range of engine operating conditions was investigated and the worst case conditions for dilution with the blends have been identified. These conditions are high speed, light load, steady state operation with low oil and coolant temperatures. Under these conditions the 20% v/v blend caused the viscosity of crankcase oil to reduce faster than it would have done with diesel fuelling, but this is not expected to cause lubrication problems within normal oil change periods. 5.4 ENDURANCE TESTING Two 300 hour endurance test runs are currently being conducted using a 20% v/v blend. Engine stripdown and component inspection will take place at the end of each run. The 20% v/v blend has been chosen so as to accentuate the amergence of any detrimental effects which might arise from the use of a 10% v/v blend. 5.5 FIELD TRIALS Plans are well advanced for approximately 30 vehicles, which include omnibuses, town carriers, long haul freighters and farm vehicles, to operate in New Zealand using a 10% v/v blend of tallow esters with diesel. It is anticipated that a total operating time of 10/000 hours, or approximately 500,000 km, will be achieved. 6. DISCUSSION It is apparent from the foregoing remarks that New Zealand produces sufficient tallow to substitute for a significant portion of the national diesel demand in the form of methyl esters of tallow. The economics of such production are, however, vitally dependent upon the value of the by-product glycerol produced. Also it is recognised that tallow esters may have a greater value as oleo chemical feedstocks than as a diesel extender. However the properties of tallow esters are such that their inclusion in diesel does not require any modification of engine operating parameters or fuel distribution systems. Consequently it would be possible to market tallow esters in such a way as to achieve their greatest value while still enabling their periodic use as a diesel extender to provide a base market. The properties of tallow ester blends with diesel fall outside the normal diesel specifications used in New Zealand for blends greater than 10% v/v. However combustion performance improves as the concentration of tallow ester increases up to

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20% v/v (and probably beyond this). In particular the cetane numbers of blended fuels are significantly greater than those of pure diesel which leads to reduced engine noise and offers the prospect of being able to blend with a lower quality diesel fuel and still maintain an acceptable cetane number. Overall tallow ester blends with diesel up to 10% v/v result in a marginal improvement in engine performance over that for pure diesel. There is, however, a possibility that lubricant degradation and engine fouling resulting from the use of tallow ester blends may be greater than for the case of pure diesel fuel. Preliminary indications are, however, that neither of these problems is likely to be so great as to limit the use of the tallow ester blends. CONCLUSIONS 1. The economic viability of extending diesel with tallow esters depends upon the long term cost of the tallow being less than about NZ$525/ tonne, the glycerol by-product value remaining above about NZ$1800/ tonne and the operating economies of a large scale processing plant. 2. Processing tallow to tallow ester requires good post-esterification processing to reduce the monoglyceride content of the ester to below 0.05% w/w. 3. The low temperature properties of tallow ester diesel blends are concentration dependent. A 10% v/v conforms with standard New Zealand diesel specifications. 4. The engine performance using tallow ester/diesel blends is similar to that for diesel fuel, however the presence of esters improves the diesel fuel ignition properties. 5. The use of blended fuels appears to offer exciting prospects for use within New Zealand.

REFERENCES (1) “Availability, quality, location and prices of tallow for the production of a diesel fuel substitute”; Liquid Fuels Trust Board Report No. 2032; wellington, New Zealand. 1983. (2) “Manufacture of tallow esters—cost estimates”; Liquid Fuels Trust Board Report No. 2033; Wellington, New Zealand. 1983. (3) “The Properties of tallow ester/diesel blends”; BP Oil New Zealand Limited; (Report to the Liquid Fuels Trust Board 1983). (4) “Engine validation tests in tallow ester/diesel blends”; Perkins Engines Limited; (Interim report to the Liquid Fuels Trust Board 1985). (5) “Research on tallow ester manufacturing techniques”; G A Strange; Department of Scientific and Industrial Research, Lower Hutt, New Zealand; (Report to the Liquid Fuels Trust Board 1984). (6) “The removal of monoacyl glycerides from tallow esters”; ICI New Zealand Limited; (Report to the Liquid Fuels Trust Board 1985).

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FIGURE 1: TALLOW ESTER FUELS-IGNITION DELAY

TABLE I: PROPERTIES OF ESTERS, DIESEL FUEL AND BLENDS Typical Tallow Tallow N.Z. Winter 10% v/v 20% v/v Ester Range Ester Grade Diesel Blend Blend Density Distillation: Initial Boiling Point

Kg/l @ 20°C °C

.870−.875

.870

.816

.821

.825

302–323

302

178

176

175

Energy from biomass

10% recovered at 50% recovered at 90% recovered at Final Boiling Point Flash Point, P.M.C.C. Viscosity

834

°C °C °C °C °C

323–326 328–332 334–336 345–349 >100

323 329 346 349 176

202 232 286 304 64.5

203 238 326 335 68

204 245 328 337 75

cSt @ 40°C °C °C

4.5–5.5

4.83

1.98

2.10

2.32

N/A N/A

N/A N/A

−3 −4

0 −3

+2 −1

0.02–0.05(1)

0.026(1)

0.14

0.05

0.05

0.05–0.10 0.05–0.10 <1.0 <0.10

0.054 <0.05 <0.2 0.003

0.004 Nil <1.0 N/A

0.009 <0.01(2) <1.0 (2) <0.02(2)

0.015 <0.01(2) <1.0 (2) <0.02(2)

<0.05 17–20

<0.05 17–18.5

N/A N/A

N/A N/A

N/A N/A

Cloud Point Cold Filter Plugging Point Carbon Residue, % w/w Ramsbottom water, Karl Fischer % w/w Methanol % w/w Alkali metals, A.A.S. p.p.m Free Fatty Acid, as % w/w Oleic Monoglyceride % w/w Melting Point °C (1) Carbon residue on neat ester (2) Calculated

TABLE II: COSTS FOR TALLOW ESTER MANUFACTURE NZ $ (1983) per tonne of ester 1,000 1/hr plant 10,000 1/hr plant Capital and Operating costs Glycerol credit Net production cost Diesel price Needed Tallow Price

336.60 –161.50 175.10 510.00 334.90

149.70 –175.30 –25.60 510.00 535.60

TABLE III: LOW TEMPERATURE PROPERTIES OF ESTER/DIESEL BLENDS Vol % Ester in Diesel Fuel Cloud Point Cold Filter Plugging Point °C °C 0 5 10 15 20

–3 –1 0 +2 +2

–4 –3 –2 –1 –1

Methyl esters of tallow as a diesel component

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TABLE IV: CETANE NUMBERS OF TALLOW ESTERS AND BLENDS Fuel BS2869 Class A2 gas oil NZ automotive gas oil 10% v/v ester in A2 gas oil 20% v/v ester in A2 gas oil Tallow ester (neat) * By IP41/60

Cetane Number * 47 47 50 54 70

PRODUCTION OF HYDROCARBONS FROM BIOMASS W.Held and M.Peters Volkswagenwerk AG, Research Division, 3180 Wolfsburg, FRG C.Buhs and H.H.Oelert Inst. of Petroleum Res., 3392 Clausthal-Zellerfeld, FRG G.Reifenstahl and F.Wagner Inst. of Biochem. and Biotechnol., Techn. Univ., 3300 Braunschweig, FRG Summary The main object of the research project was to convert biomass and organic waste materials to an energy rich liquid which may be suitable as diesel fuel. Several procedures were tested, such as fermentation of yeast and bacteria for lipid production, cultivation of the algae Botryococccus braunii, extraction of hydrocarbon producing plants (Euphorbia lathyris) and liquefaction of lipid containing yeast, Euphorbia, algae, sewage sludge, bagasse, and black liquor. Liquefaction experiments were run in aqueous phase at high CO pressure in a batch stirred reactor. The analysis of products of extraction and liquefaction processes shows, that hydrocarbons are produced. This route of biomass conversion, however, is not yet economical.

1. Introduction High priced crude oil and shortage of oil initiated research on use of renewable energy resources. Volkswagen research is mainly interested in fuels for transportation or stationary engines. Ethanol from starch or sugar and biogas from manure are suitable for use in passenger car engines, as demonstrated in different countries especially in Brazil. However, a substantial decrease of crude oil consumption in those countries will only occur after substituting diesel fuel, too. Therefore investigations were made to find out to what extent different feedstocks are candidates for the production of liquid hydrocarbons suitable as diesel substitute. 2. Objective of the project Many proposals were made for producing hydrocarbons from biomass. Main routes are

Production of hydrocarbons from biomass

837

* use of hydrocarbon-rich biomass * liquefaction and/or hydrogenation of biomass Hydrocarbon-rich biomass in this project means all plants and microorganisms containing hydrocarbors, lipids or fatty acids. After extracting these components the residues as well as other organic waste material is liquefied by thermal processes. Biomass shows a H/C ratio which is similar to that of hydrocarbons. The oxygen content of the biomass, however, is to be reduced during liquefaction. Some routes for biomass conversion are shown in figure 1. The objective of the project was to find out the feasibility of producting hydrocarbons from different feedstocks. 3. Feedstocks Different types of feedstocks were used in the research program: * lipid-rich yeast and bacteria, algae containing hydrocarbons (Botryococcus braunii) * Euphorbia lathyris and Synadenium grantii as examples for hydrocarbon formation by plants * biomass (residues and waste) e. g. bagasse, cellulose, sewage sludge, extracted plant material, black liquor, yeast, algae, euphorbia Yeast (Rhodosporodium toruloides, ATCC 10 788) and bacteria (Arthrobacter sp. AK 19, ATCC 27 779) were grown under optimal conditions for lipid production. The plants were cultivated in a greenhouse. For the experiments fresh and dried plant material was used. The algae Botryococcus braunii was grown in a bioreactor under lighting. Residues and waste were obtained from different sources. 4. Processing of feedstocks Figure 2 shows the processing of different types of biomass. All experiments were laboratory-scale. For extraction experiments the following solvents were used: Acetone, Chloroform, Ethanol-Water (80:20), n-Hexane, and n-Heptane. The samples were extracted in a Soxhlet apparatus. Extracts were fractionated by liquid chromatography and characterized by GC-MS analysis. Many processes for the hydrogenation and liquefaction of biomass are published. Because of the high water content of residual biomass we tried to avoid costly drying of the biomass. Therefore we run most experiments in a batch stirred reactor in aqueous phase at high CO pressure. In some experiments the reductant was H2 in the presence of a catalyst (Co Mo). The volume of the reactor was 251) ml. Maximum temperature was about 350 °C at a pressure up to 300 bar.

Energy from biomass

838

5. Results An objective of the project was to screen a great variety of feedstocks under different processes for hydrocarbon production. Some results of this screening are. shown below. Extraction of Euphorbia lathyris Euphorbia lathyris was extracted with n-Hexane and n-Heptane. The total hydrocarbon fraction was from 3% to 10% of dry matter. After liquid chromatography the n-Alkane fraction was analyzed in detail (figure 3). These hydrocarbons are about 2% of the biomass (dry weight). Liquefaction and hydrogenation experiments Microorganisms were grown under conditions for increased lipid production. The oxygen content of lipids is low as shown in figure 1. Therefore lipid-containing yeasts are thought to be a suitable feedstock for decreasing the 0/C ratio by Jiquefaction at CO pressure. The results show, that the H/C ratio remains constant at 1,8 and the 0/C ratio is decreased from 0,3 to 0,1. In the extract free fatty acids were measured. However, a hydrogena-tion of C=C bonds did not occur. The algae Botryococcus braunii, known as a hydrocarbon-producing organism, was liquefied in aqueous phase. After separation of water the crude was analyzed. The nHexane soluble fraction (about 30% of total product) contains n-Alkane (C27: C29: C31=5:35:60). About 50% of the crude is a mixture of différent types of olefin and silane. Liquefaction of fresh Euphorbia lathyris resulted in branched hydrocarbons from C20 to C31 (figure 4) in contrast to the extracted latex, which showed C12 to C20 n-Alkanes. In the biocrude some olefins as well as thiophene, phenone and alcohol were detected, too. The reason for the different types of hydrocarbon is not clear. We think that silicate from the plant material acts as a catalyst and thus hydrocarbors were cracked and recombined again to form branched molecules. Sewage sludge is an example for biomass which is produced in large amounts in sewage-treatment plants. The Idea was to use sewage sludge for liquefaction experiments to fird out whether an energy-rich crude is formed. This would be a desirable way to diminish the problem of sewage sludge handling. Sewage sludge was treated twice. First the aqueous sludge was liquefied at CO pressure in a flow reactor. The biocrude was extracted and hydrogenated in a second step. This experiment was run in a batch reactor at H pressure and with a Co Mo catalyst. The product shows different types of hydrocarbons (C12−C25) and phenolic compounds (figure 5). In general, all tested feedstocks are convertible up to a certain degree to hydrocarbons. The molar weight of the products is in the range of 400 g/mol to 200 g/mol. The lower molar weight is reached after the hydrogenation step in the case of sewage sludge. In comparison, the average molar weight of diesel fuel is about 170 g/mol. The heating value of the biocrude is in the range of 30 000 kJ/kg to 42 000 kJ/kg. Again, the twice treated sewage sludge shows the highest heating value. The viscosity of this product is very low, too.

Production of hydrocarbons from biomass

839

6. Conclusion The different feedstocks and procedures tested showed that it is possible to get products of low viscosity, low molar weight and high heating value. The potential of these products to substitute diesel fuel has not yet been tested. However, up to now the yield is too low and the liquefying process consumes so much energy, that this procedure as a whole is not yet economical. The financial support of this project (No. C086, C087, C088) by Bundesministerium für Forschung und Technologie is gratefully acknowledged.

FIGURE 1: ROUTES FOR BIOMASS CONVERSION

FIGURE 2: PROCESSING OF BIOMASS

Energy from biomass

840

FIGURE 3: HYDROCARBONS EXTRACTED FROM EUPHORBIA LATHYRIS

FIGURE 4: HYDROCARBONS FROM LIQUEFIED EUPHORBIA LATHYRIS

Production of hydrocarbons from biomass

841

FIGURE 5: HYDROCARBONS FROM HYDROGENATED SEWAGE SLUDGE

RENEWABLE HYDROCARBONS AND INDUSTRIAL CHEMICALS FROM KENYAN PLANTS A.Ng’eny-Mengech and S.N.Kihumba Department of Chemistry, University of Nairobi, P.O. Box 30197, Nairobi, Kenya. Summary Indigenous Kenyan plants of the families Euphorbiaceae, Moraceae and Asclepiadaceae have been screened for their hydrocarbon, oil, phenolic, sugar, protein and fibre content. Each species is then evaluated as a potential multipurpose crop for fuel, chemical feedstock and fodder production. The method has been applied to whole plant material, dried stem latex and to the new terminal leafy growth of fast-growing trees. The species selected for analysis are primarily from the semi-arid regions of Kenya, but also include potential fuel/fodder trees from the high-potential zone. Heats of combustion and spectroscopy of all plant fractions has been undertaken.

I. INTRODUCTION Considering the fact that many developing countries are presently spending up to 40– 50% of their foreign exchange earnings on the importation of crude petroleum, and individual families as much as a quarter of their income for domestic fuel, it is wise to reexamine the role that agriculture can play in meeting the energy requirements of the Third World. The expertise required to produce potential energy crops is already extant in the indigenous peasant population of most of these largely agrarian societies. Biomassderived energy is appropriate for both domestic and industrial applications, and at the same time biomass can provide many of the feedstocks for emergent chemical industries. In order to discover previously unexploited sources of energy and raw materials, our group at the University of Nairobi have undertaken a screening programme of plants growing in Kenya. Using a combined solvent extraction/ partitioning scheme developed by Buchanan and co-workers at the U.S. Department of Agriculture (1), the dried plant material is divided into four major fractions each of potential industrial importance. Each fraction has been evaluated for its heat values and detailed chemical analysis of some species is underway in order to identify any high-value chemical components. The plants analyzed fall into two major groups: plants that grow in the semi-arid regions of Kenya (comprising over 2/3 of the total land area) and those trees and shrubs with easily harvestable new foliage. Species from the families Euphorbiaceae, Moracea

Renewable hydrocarbons and industrial chemicals from kenyan plants

843

and Asclepidaceae have been selected for analysis first because of their generally high latex (hydrocarbon emulsion) content. Screening is intended to cover resin-producing species at a later stage. The Figs (Ficus Spp) are common to the African and Asian tropics, and have been used traditionally as a source of fodder for animals, for medicinals, and as a source of natural rubber. Ficus elastica (the rubber tree) was a commercial crop until Hevea braziliensis proved to be a superior rubber source. The propagation of figs is easily done by cuttings, and many species, such as F. benjamina (the “weeping fig”) are sufficiently fast-growing to allow regular harvesting. Other trees of interest are the resin-producing Commiphora which are widespread in the semi-arid regions. A scenario for the utilization of such species could involve an initial solvent extraction for the removal of fuel and high-value chemical components, followed by use of the leafy residue for animal feed or fibre. Among the xerophytic species, the Euphorbia are an important group in Kenya, with over 200 representatives scattered in even the driest arid regions. Euphorbia species thus far analyzed range from herbaceous types to medium-sized shrubs (E. tirucalli, E. gossipina) to large woody specimens (E. candelabrum, E. nykae, E. grandicornis) to name but a few. Smaller specimens might be harvestable as the whole plant, whereas larger species could possibly be tapped. Euphgrbia have been exploited in the past as sources of medicinals, hydrocarbon fuels (E. tirucalli, E. resinifera) and waxes (candillila). The milkweeds (Asclepiadaceae) are another common family in the semi-arid zones; Calotropis procera is widely distributed throughout Asia and Africa. This multipurpose plant has already been used commercially as a source of bast fibre, seed floss, textile fibre, and medicinals. Its development as an oil or hydrocarbon crop is being currently investigated by several groups. Results of the analysis of a few selected species are reported below. II. METHODS The plant material was collected from the wild. In most cases, the entire aerial parts were analyzed, although in the case of the Ficus species reported, only the new leafy growth and stems were harvested. After drying, the material was ground to a fine powder and extracted in succession first with acetone, then with cyclohexane, the latter producing the hydrocarbon (HCF) fraction; the fibrous residue remaining after the extractions was saved for sugar, protein and crude fibre and sugar analysis. The initial acetone extract was then partitioned between aqueous ethanol and n-hexane to give, respectively, the “polyphenol” fraction (PPF) and the whole plant oil fraction (WPOF). The yield of each fraction was determined as a percentage of the dry plant weight (Table I). IR and ‘HNMR spectroscopy of the fractions was performed, and the heats of combustion determined in a bomb-calorimeter (Table II). The WPOF was decolorized over charcoal and the iodine and saponification numbers determined (Table III).

Energy from biomass

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III. RESULTS AND DISCUSSION Whole Plant Oil The percentage yield of whole plant oils of ten selected species is shown in Table I. Oil yields were generally higher during the dry season and from semi-arid zone plants. Saponification and iodine numbers of a few oils are shown in Table III. The high percentage of unsaponifiable matter of some species (e.g. Euphorbia nykae and Calotropis procera leaves) suggests that a substantial component of these particular oils are not simple waxes or glycerides, but may be steroidal or terpenoid type compounds. The heat of combustion of this fraction averaged about 42–43 MJ/Kg, which is slightly higher than seed oils. HPLC analysis of the WPOF constituents is in progress, so as to identify any unusual or valuable fatty acids present. Fatty acids in particularly high demand by industry are short-chain acids (for detergents); long-chain acids (for polymers, lubricants, plasticizers); hydroxy fatty acids (for polymerization); epoxy fatty acids (coatings, plastics); conjugated and unusual unsaturated acids (for chemical intermediates, drying oils, low-temperature lubricants). Other useful components of the WPOF are rosin acids and other terpenoid compounds which can substitute for naval stores rosin, a subject reviewed by Hoffmann (2), who has envisaged a scenario for the arid lands involving an integrated energy plantation providing naval stores based on the xerophytic plant, Grindelia camporum. Polyphenol Fraction This fraction contains relatively polar plant components such as polyphenols, tannins, complex lipids, flavonoids, etc. Polyphenol yields from the lactiferous species are not particularly high when compared to such high-tannin sources as the Acacias. The heats of combustion of this fraction were generally lower, averaging around 34 MJ/Kg, which is to be expected from its higher oxygen content. The use of this fraction as a chemical feedstock is probably the best option. The value of plant phenolics as raw materials for adhesives and aromatics production has been estimated at 3–11 times their fuel value. Hydrocarbon Fraction (HCF) The heats of combustions of the HCF generally range from 44–47 MJ/Kg, which compares favourably to fuel oil and gasoline (48.2 MJ/Kg). This fraction is therefore an obvious source of combustable fuel, although at present the economics of large-scale extraction methods are not competitive with petroleum refining if the “biocrude” is the sole energetic product. Euphorbia lathyris has been critically assessed as a potential hydrocarbon-producer by the University of Arizona (23) , who concluded that the plant requires too much irrigation and fertilizer in the Arizona climate. The same species produced more hydrocarbon (5.92%) when grown near Madrid, however, closer to its Mediterranean origins (4) . In Kenya, plantings of Euphorbia tirucalli await a final evaluation of their feasibility as a hydrocarbon source. The yield of hydrocarbons from the 10 species reported in Table I varied between 0.1% to over 6%. Buchanan et al (1) consider a yield of 2% to be the minimum for a potential hydrocarbon crop. IR and NMR of this fraction has shown that in some cases, isoprenoids are the major components. Species with lower heats of combustion (e.g. Calotropics procera) have a higher wax (ester) component. Gel permeation

Renewable hydrocarbons and industrial chemicals from kenyan plants

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chromatography is planned to assess the molecular weight characteristics of the constituent hydrocarbons. The hydrocarbon fraction is of interest as a potential source of natural rubber and terpenes. Lower molecular weight hydrocarbons can be used as extenders and plasticizers for rubber, and if the molecular weight is sufficiently low direct use as diesel fuel is a possibility, as in the case of the Brazilian Copaifera trees publicized by Calvin (5). Fibrous residue The fibrous residue remaining after the solvent extraction consists primarily of sugars, complex carbohydrate, protein and crude fibre. Soluble sugars can be removed by a further extraction step with methanol, for possible fermentation to alcohol to supplement the energy yield from a given plant. Protein analysis of Ficus leaves has shown some species to compare favourably with alfalfa hay at 16% protein. Crude fibre analysis is sufficiently high in some cases to suggest utilization as a fibre source for paper or board manufacture. Stem bast fibre from Calotropis procera has been used traditionally for fishing ropes by East African fisherman. This species and other milkweeds have been evaluated by Tideman and Hawker in Australia (6) and Erdman & Erdman in Puerto Rico (7) as hydrocarbon sources, without consideration of their fibre potential. IV. CONCLUSIONS Most economic analyses of potential liquid fuel producing plant systems have concluded that under present market conditions, the extraction of hydrocarbons and oils alone is not a viable proposition. A multipurpose crop for the simultaneous production of a higherpriced commodity, such as rubber, rosin or medicinals favourably affects the economics, but generally not to the point of profitability. In future, however, the issue will not be competitiveness with current crude oil prices, but a matter of simple availability of liquid fuels. The screening of the enormous variety of higher plants (estimated at greater than 300,000 species) is in its most formative stages, but is an essential exercise, nevertheless, if new industrial and/or energy crops are to be developed for the time when the oil runs out. V. ACKNOWLEDGEMENTS This research has been sponsored by the National Council for Science and Technology, Kenya. REFERENCES (1) Buchanan, R.A., J.M.Cull, F.H.Otey and C.R.Russel, Economic Botany, 32, 131–145 (1978); ibid, 146–153. (2) Hoffmann, J.J. CRC Critical Reviews in Plant Science, 1(2), 95–116, 1983. (3) Kingsolver, B.E. Biomass, 2, 281–298, 1982.

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(4) Tenorio, J.L., P. Ventas, E. Funes and L. Ayerbe Bio Energy 84, Book of Abstracts, p.69. Göteborg, Sweden, June 1984. (5) Calvin, M. Science, 219, 24-26, 1983. (6) Tideman J. and J.S. Hawher. Search, 12, 364-365, 1981. (7) Erdman, M.D. and B.A. Erdman, Economic Botany, 35, 467–472, 1981.

TABLE I: YIELDS OF EXTRACTABLES FROM 10 KENYAN PLANTS (calculated as % Dry Weight) whole polyplant oil phenolics Euphorbia nykai 3.1 4.5 E. lubecii 3.7 7.0 F. gossipina 2.8 8.2 E. leucocephalia 4.5 7.3 E. cotinifolia 4.3 5.6 Calotropis 2.1 3.5 procera leaves Ficus benjamina 5.4 4.5 F. glumosa 2.4 5.6 F. volgelii 2.1 9.3 F. capensis 1.0 7.1 As % of meal after methanol extraction

hydrocarbons methanol extractables

protein+ in crude+ meal fibre

1.9 1.8 2.2 1.2 2.9 6.3 3.5 1.31 0.5 0.1

2.7 4.6 3.1 3.9

10.3 – 11.7 13.7

39.0 – 27.2 19.4

TABLE II. HEATS OF COMBUSTION OF PLANT FRACTIONS IN MJ/KG PLANT

Whole Plant Oil

Hydrocarbon Fraction

Polyphenol Methanol Fraction

Euphorbia nykai Calotropis procera leaves Ficus benjamina F. glumosa F. volgelii F. capensis

42.5 41.5

41.1m 39.0

35.5 31.0

41.5 41.5 41.6 43.3

48.1 46.6 44.6 46.8

36.1 36.4 27.5 36.1

20.3 19.0 26.0 21.0

TABLE III. WHOLE PLANT OIL ANALYSIS FROM SOME KENYAN PLANTS PLANT Eurphorbia nykai Calotropis procera leaves Ficus benjamina F. glumosa F. volgelii

Saponification number Unsaponifiable matter Iodine number 48 75 190 233 229

68.0 85.0 37.5 25.0 30.0

110 106

Renewable hydrocarbons and industrial chemicals from kenyan plants

F. capensis Coconut oil Sunflower oil

161 254 192

28.6

Reference fuels - Heat of Combustion in MJ/KG Anthracite coal

30.1

Crude oil

44.1

Fuel oil

45.2

Gasoline

48.2

847

90 10 130

CORN DRYING CEREAL STRAW COMBUSTION HARVEST AND ENERGETIC VALORIZATION OF CORN COBS Xavier GAUTIER Association Générale des Producteurs de Maïs (A.G.P.M.) Summary: Researches engaged as far as biomass use is concerned are applied in maize drying field : by the end of 1984, more than 40 installations were recorded. Combustibles can be either cereal straw or corn cob. The straw bales from 20 to 500 kg in weight are burnt in ovens from 500 to 900 therms/hour. This allows the drying of 500 to 1 300 tonnes of maize a year for each installation. The harvest of 80% corn cob is realized with a combine harvester. Cob is mixed with grain in the tank. Thanks to a rotary cleaner, cob is first separated from grain in order to be used finally, for maize drying. If dry, corn cob will burn easily in ovens having inclined, rotary or fixed grates. The oven thermic power fluctuates from 600 to 5 000 therms/hour. If moist, a previous drying is necessary before its burning generally to prejudice to the installation thermic yield. In most cases, invests remains high and even if the overcost is redeemed by the 2 or 5 following years, these technics are developing slowly.

1. INTRODUCTION The first corn dryer using renewable energy was built in 1976. From then up to 1982, the drying cost in co-operatives increased by 20% each year. This was due essentially to the fuel oil and gas rising cost. Energy represented till 70% of the total drying cost. In such a context, researches have been engaged as far as biomass use is concerned. For 6 years, about 30 corn dryers have been using cereal straw as an energy source and more than 10 plants have been using corn cobs. These drying systems require obviously more labour. For 2 years, the rise of corn drying cost has been limited from 5 to 6% per year that minimizes the interest for biomass use. That is the reason why A.G.P.M. goes on studying these systems with a view to improve them. Researches engaged intend to prepare the application of this technology as soon as possible and according to better social and economical factors. As a result, today in France, biomass uses for corn drying represent 1 000 tuns of oil that is to say 0.3% of national energy consumption for drying.

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2. CEREAL STRAW COMBUSTION Principle: In France, in a northern area called Bassin Parisien, farmers are used to grow wheat and corn. Wheat produces from 3 to 3.5 tuns of straw per hectare which can be collected without, however, impoverishing organic matter content of the soils. 2.5kg of straw contain the same energetic power as one litre of fuel oil. Corn produces from 8 to 8.5 tuns of moist grain per hectare that must be dried to 15%. 3 hectares of straw are required to dry 1 hectare of corn. Straw collecting system does exist. Its cost fluctuates from 150 to 250 F per tun according to straw conditioning (small or big bales). To be kept dry, straw has to be stored up. Wheat straw allows generally an easier use as far as its handling is concerned. About 30 plants in 1984: Because of transport costs, all the furnaces are built in farms : they can dry from 500 to 1 300 tuns per year. In 1980, 3 systems were studied but only one, a cylindric and vertical boiler, is used today. The primary combustion takes place at the top, the second one under the grate. It’s a reversed combustion. Then, the combustion gases go through the exchanger before their final expulsion in the air. Thanks to the length of the alimentation system, only two loadings per day are required. Using small bales, the latters are carried one by one to the boiler. If big ones are used, they have to be destroyed beforehand and then conveyed to the furnace. Alimentation system is automatic. There are two models existing: 600 or 1 000 KW. The oven efficiency can reach 70%. Ash level doesn't exceed from 4 to 5% of the straw weight. Ashes have to be taken off once a day. For 1984, estimates concerning straw boiler users who dried 1 000 t of maize, show a saving of 115 000 F. Generally, the overcost is redeemed by 2 to 4 years. However, since 1982, high invests and unfavorable conditions reduce the development of such a drying system. 3. CORN COB COMBUSTION Cob, the central part of the ear, has got a high moisture content when harvested : from 60 to 65% SH. Its calorific power is about one therm per kg of wet cob. So it’s necessary to reduce Its moisture to 15% in order to ensure a good combustion. If 100 kg of dry grain are harvested, from 12 to 18 kg of cobs are supposed to be collected too, according to the varieties. On the one hand, corn drying with cobs represents a high interest as it is shown that cob contains enough energy to dry its grain. On the other hand, both energy and grain are produced at the same time.

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Cob harvest If corn is harvested in ears, in the traditional way, cob is collected with grain. However, this system remains unusual as just 20% of corn production is concerned. An amount of 300 000 tuns of cobs collected this way, is entirely used. That's the reason why, since 1981, A.G.P.M. endeavours to find out other cob harvest processes. The most efficient one, today, consists in fitting out a combine harvester in order to ensure the harvest of cob and grain mixed in the tank. Some adjustments are required as it's shown on the following schema: Fittings realized on a combine harvester to collect cob mixed with grain.

1. Threades are cut off at the concave exit. 2. Partial suppression of the threshing cylinder clip. 3. Important perforations of the straw walkers. 4. Grate with big perforations. Experimentations show that, thanks to this system, 80 % of cobs were collected without spoiling grain commercial quality. Time spent to harvest is obviously longer than usually as the combine harvester speed doesn't exceed 4 km/h and the transport volume increases by 20 to 30 %. Trials concerning the sorting of the corn cob mixture were conducted with two types of machines : a sorter with horizontal screen and a rotary cleaner. The second one gave the best results. Consequently, the output dwindled without, however, any vulnerable points noted. Thus, the feasibility of such an operation has been proved. In 1985, a similar experimentation will be undertaken on a larger scale in farms. Furnaces using dry cobs In France, 11 furnaces use dry cobs. The total thermic power averages 30 000 KW. 7 furnaces are used by cornseed producers to dry the ears (from 1 500 to 5 000 therms/hour per furnace). The latters have been dried at a low temperature before being shelled in order to extract the cob. One furnace produces steam in an maize process industry and 3 smaller boilers of 700 KW each operate in farms. Most of them have got inclined grates. The cob is conveyed from the tank into the furnace by the top. Then, it burns away progressively on the grates.

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There is another type of furnace existing with rotary grates on which cob is burnt too. Finally, cylindric boilers operates in smaller farms ; their conception can be compared with the one used for straw combustion. In any cases, big amounts of cobs are available closed to the plants as they’re issued from seed ears or ears stored in grain dryers. Their cost fluctuates from 0 to 140 F/t. Furnaces for moist cobs Only two plants using moist cobs have been recorded. Their conception remains the same as for dry cobs, except the smokes issued, dilued at 60–100°C, are used to dry cobs before their burning. However, some problems arise with regard to cob dryers: either concerning security if smokes are not filtered or thermic yield which is not sufficient enough and reduces the total plant efficiency. Using his own cob production, a farmer will run his furnace autonomously if his grain moisture content doesn’t exceed 30–32%. The overcost of these plants can be redeemed by 3 to 5 years according to their size. However, as straw combustion, these systems are developing slowly. 4. CONCLUSION Drying corn with biomass is possible today as 40 plants using cereal straw or cobs have been registered. In the next coming years, improvements will be realized to get best performances even if labour needs remain a vulnerable point. The seasonal use of such material to dry corn is a problem too. These techniques will develop if they show an obvious drop as far as drying cost is concerned in comparison with fossil energy. That’s why the researches have to be promoted in order to simplify and lower price of biomass plants.

WOODSTOVES IN THE NETHERLANDS, ENVIRONMENTAL AND SOCIAL IMPACTS P.A.OKKEN Centre for Energy and Environmental Studies (IVEM) State University, PO Box 72, Groningen, the Netherlands Summary In the Netherlands natural gas is the dominant fuel for space heating. In recent years however, the use of woodstoves has become popular again. This might save energy and increase airpollution. In order to asses the energy and environmental impacts of this sudden revival and to determine the possibilities for public information programs, a questionaire was sent to 1300 woodstove users. Clean dry seasoned wood appears to be the most important fuel. Yet, painted or impregnated wood is also used, wich increases airpollution. Lignite, coal, waste paper and packages are also used to some extent. In general the stoves have too much heating capacity, and conseqeuntly they must be operated with little air-supply, wich gives airpollution. Stoveoperation and fuel supply were analysed in relation to usersattitude, by means of several statistical techniques. Three different patterns of usage were detected. Important is the “loot pattern” in wich frequent use of waste fuels is correlated with a natural lifestyle friendly to energy and environment, without recognition of adverse impacts on nature or landscape. The detected patterns of usage might play an important role in public information programs.

1. INTRODUCTION, WOODSTOVES IN THE DUTCH ENERGY CONTEXT In the Netherlands woodstove sellings have made a recent progress. However, woodstoves can have unfavourable environmental impacts. At State University Groningen, faculty of IVEM, environmental effects of woodstoves are investigated and the actual usage of woodstoves is surveyed by means of questionaires and interviews. This interdisciplinary research is done by K.Altena, P.Okken and B.Stoop, sponsored by the Dutch Ministry of Housing Planning and Environmental Control (VROM). In former days wood was an important fuel in the Netherlands. After periods in wich peat, coal and oil were used; natural gas has been the most important fuel for heating houses since 1970. Nowadays 97% of the Dutch houses are connected to the nationwide natural gas network. Gas heating appliances are stoves, boilers and furnaces.

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In recent years approximately 200.000 woodstoves are sold in the Netherlands, equivalent to 4% of the Dutch houses. This is a remarkable comeback. In 1983 IVEM sent a questionaire to two independant groups of woodstove users: 300 users who responded to a request in a Dutch consumers magazine, and 1000 users whose adresses were given by local woodstove sellers. The overall questionaire response was 49%. Some results are discussed below. Woodstoves are usually (90%) found in houses wich also have gas heating. The stoves are traded in the Netherlands as woodstoves, multi-fuel stoves or solid-fuel stoves. Different types are illustrated in figure 1. Most common is the modern Danish stove. This is a typical multi-fuel stove. Another important type is the frontloader from Norway or the USA. This is an original woodstove. Less common types are the traditional Dutch potbelly the fireplace-insert and the Franklin stove. Relatively few ceramic stoves are sold. These are common in landclimate Central Europe.

Figure 1: Woodstoves in the Netherlands. Percentage share in recent sellings

2. FUELS AND WOOD SUPPLY The fuel usage as questionaired is summarized in table 1. Wood appears to be the most important fuel. Some wood was characterized as cast-off wood from house breaking. Fuels used to some extent are lignite, packages/wrappings, coal and waste papers. Lignite, coal and a part of the fuelwood are bought in shops or at forestries. The other fuels are collected from waste or at work by the woodstove user.

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The Netherlands is densily populated. There is few inland wood available. Only 8% of the country’s surface is covered with forests and trees. As a consequence 90% of the nation’s wood demand has to be imported. Woodpulp for paper is imported from Sweden, hard woods for building materials are imported from tropical countries. The amount of woodwaste in the Netherlands potentially available for stoves and masonry fires, is 1100 thousand tons a year. More than half of this is cut-off wood from building and furniture industries. The rest is wood left behind in inland tree and forest cutting. The precarious woodbalance is reflected in wastepaper recycling. More than 50% of all wastepaper is collected and re-used in paper industries, up to 1050 thousand tons a year. In the Netherlands recycling of woodwaste or wastepaper is energetically preferable to burning in a woodstove. For instance: when wastepaper is recycled it costs 24 GJ fossil energy/ton. When wastepaper is burned in an efficient woodstove it saves 16 GJ fossil energy /ton (otherwise needed to heat the house) on the one hand, but on the other hand it costs 36 GJ fossil energy and 18 GJ wood energy to make a ton of new paper. Hence, when recycling is the alternative, burning wastepaper in a woodstove costs 38 GJ/ton (=36+18−16), while recycling costs 24 GJ/ton. If woodstoves compete with existing recycling streams (woodwaste and wastepaper recycling), a further expansion of woodstoves is undesired.

Table 1: Fuel usage in woodstoves in the Netherlands (1983) Which fuel is used? "Often" "Sometimes" "Never" (% of respondents) coal wood, seasoned wood, less than 1 yr old wood briquettes lignite peat straw briquettes paper briquettes plastic waste paper packages/wrappings fresh wood/clipwood dead wood treated wood petrol-cokes work wastes cast-off wood leather/rubber other

8% 64 31 1 11 0 0 2 0 6 9 4 7 3 0 4 23 0 0

16% 25 46 8 28 7 0 12 2 31 25 28 34 38 2 9 48 2 9

75 10 23 91 62 93 100 86 98 63 67 69 59 59 98 86 30 98 92

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3. ENVIRONMENTAL IMPACT Risk is a negative environmental impact. Woodstoves hold fire-risks and can cause indoor airpollution and give risks in woodcutting. Wood is a renewable energy source, this is a positive impact. Particular attention has been given to airpollution. In the Netherlands the potential airpollution is quite clear because natural gas, the dominant fuel, gives only minor airpollution. The gaseous emissions are dependant of fuel, stovetype and operation. Some of the woodfuel is characterized as cut-off wood or treated wood. This wood can be painted or impregnated. By burning such wood, special compounds can be emitted into the atmosphere, for example lead (from paint) and arsenic or dioxins (from impregnates). This increases airpollution. Most woodstoves are fitted with an adjustable air supply. We have found that 70% of the woodstoves are operated with the air supply closed as much as possible. This is felt necessary, because most woodstoves are too great for Dutch houses. Mean woodstove capacity found was 12 kilowatt, while a maximum of 5 kW should be enough. In consequence stoves are operated with little air supply in order to temper the heat output. The wood is burned at starvedair conditions in a smoldering fire. This incomplete combustion increases airpollution. Carbon monoxide, particulates, polycyclic aromatic hydrocarbons, aldehydes, ketones, etc are emitted, wich can give health problems. Carbon monoxide emission figures, as compiled from hundreds of published measurements from normal woodstoves burning seasoned wood, in dependence of air supply, are summarized next.

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4. PATTERNS OF USAGE In the Netherlands wood availability is limited, woodstoves can have negative environmental impacts, and most woodstove users have also another heating appliance fueled by natural gas, wich is clean, easy, safe and relatively cheap. One may ask: why do people use woodstoves? Most respondents spontaneously replied they want to save energy and they like the nostalgic comfort the stove offers. To clarify this question further, all respondents were asked to judge 22 arguments. For example: “wood burning is a sport”, “it makes me think of the old days”,“it is a solution to the problem of wastes”, “when many people use woodstoves there will not be enough wood”. These 22 arguments were catagorized by means of factor analysis. This is a common technique in social sciences. People can be classified according to their agreement with the following four “attitudes” (A1–A4): A1 Natural, energetic and environmental lifestyle. The woodstove is

involved in a natural and lifestyle, in wich one is environmental conscious of energy problems.

A2 Inconvenience. The woodstove user suffers nuisances and rubbish. A3 Degradation of nature and landscape. Too much woodstoves can destroy

woods (“nature”) and affect landscape.

A4 Proper usage of woodstoves is difficult, some people are not able to

do so.

The question is how these attitudes combine with actual usage of woodstoves From an environmental point of view important parameters of woodstove usage are: Frequency and time of the day the woodstove is used. Air supply to the stove. Chimney cleaning. Fuel. The use (see table 1) and acquisition of fuel, as reported by the respondents, were catagorized by means of factor analysis. Three “fuel styles” (F1–F3) were found: F1 Fuel looting. Free fuel is used as much as possible. Fuels are cast-off wood, treated wood, waste paper, packages/wrappings, etc. These are collected from waste or at work. In ultimate circumstances this might be called “looting”. F2 Plastic and rubber are used as fuel. This is a rarity, see table 1. F3 Fuel buying. Fuels, mostly lignite and coal, are bought in shops.

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The patterns in wich attitudes combine with actual usage of woodstoves were detected by means of a canonic correlation analysis. This is a common technique in social sciences. The results are summarized in table 2. Three different patterns of usage of usage (P1–P3) were detected: P1 The first most important pattern is the so called “loot pattern”. As can be seen from table 2 a natural, energetic, environmental lifestyle without recognition of nature and landscape degradation is combined with frequent stove-use and fuel looting. This is striking because the looted fuels can be characterized as unfavourable (more airpollution less energy saving). One might argue this “loot pattern” reveals a misunderstanding among woodstove users in the Netherlands. This could be attributed to commercial advertising by woodstove sellers and also to promotion of “natural” woodheating by some environmentalistic groups. P2 The second pattern (table 2) is evident: Fuel looting is inconvenient and (so) it is not done by proper woodstove users. P3 The third pattern is difficult to interprete. It seems to reflect an easy usage. However, this pattern is statistically not very important.

As can be seen from table 2 air supply to the stove, wich is an important determinant for airpollution, has no correlation. This could be expected: air supply is dictated by the size of the stove one owns, and not by ones attitude. The detected patterns of usage can play an important role in public information programs, designed to reduce airpollution and environmental problems. Information is more likely to be accepted when attitudes and actual patterns of usage are adressed. For example: dissuading from looting fuels can be accompanied by showing energy- and environmental advantages of recycling, with reference to proper woodstove users who don’t loot. On the other hand, the best way to avoid stove operation with little air supply is to inform aspirant woodstove users about the best fitting size of the woodstove. key-words: airpollution, attitude, waste, woodstoves, woodsupply. The author wishes to thank A.F.L.Slob(Ministry VROM, the Hague), K.Altena, J.Boersema and B.Stoop (IVEM); H.Goedhart and R.Okken. Reports: Altena, K, P.A.Okken, L.A.M.Stoop. The usage of solid-fuel stoves. IVEM, Groningen, august 1984. Okken, P.A. Environmental impacts of woodstoves and masonry fires. IVEM, Groningen, oct.1982. Both reports written in Dutch.

Table 2: Woodstove patterns of usage, as detected by canonic correlation. Canonic weight patterns of usage P1 P2 P3 ATTITUDES Al Natural energ.env. lifestyle A3 Degradation nature landscape A4 Proper use A2 Inconvenience ACTUAL USE

.69 −.48 .32 .41

.56 .69 −.66

−.49 −.63

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No frequent use −.60 F1 Fuel looting .48 −.83 Not use at evening .74 Not use at night .48 F3 Fuel buying .33 Air supply Chimney cleaning F2 No use in daytime Canonic correlation .50 .29 .18 Chance .00 .00 .01 Note: canonic weight maximum is ±1.00. Only weights more than 0.25 are presented in table 2. Hight weights are more important in a pattern of usage. When a negative sign is given, the denial counts.

FLUIDISED BED COMBUSTION OF BOTH LIGHT AND WET BIOMASS B.WILTON, University of Nottingham J.F.WASHBOURNE, Energy Equipment Co. Ltd. Summary Although combustion of coals in a fluidised bed of sand is recognised as being a particularly efficient way of using poor quality fuel there has been little work on the fluidised bed combustion of biomass. Problems of elutriation of fuel and sand may be encountered in fluidised bed units so to minimise these effects intermittant fluidisation and under-bed feeding is being used, together with a large expansion chamber in which some centrifugal treatment of the flue gases will be possible. It is expected that moist biomass will be able to be used and this should be an attractive feature as it will reduce the need to store and/or dry biomass before use. Fluidised bed combustion should also produce flue gases that are less polluting than those given off by other methods of combusting biomass. When compared with most other fuels biomass is at best less convenient, while at worst it can be almost impossible to use. It is less energy-dense than oil, coal or fuel gases, it will not flow through narrow pipes (although it can be conveyed in fluids through large ones) and biomass harvesting, handling and storage can all present problems. Despite all these drawbacks it undoubtedly has a part to play in helping to meet the world’s energy demands. Two further major problems with biomass are that it can be extremely variable and in some cases it can be very wet. In general dry biomass fuels are utilised by combustion or gasification, whereas the only sensible way of using some of the wettest ones is by fermentation: as so often happens it is the in-between moisture content materials which cause problems. Another feature of biomass that has to be considered is that the period of availability can vary considerably. Some materials are produced more-or-less continuously: if they happen to be wet, like waste animal slurries, then fermentation is obviously the most promising pathway to follow. If they are produced annually it is likely that there will be an optimum season for collection and this will almost invariably be followed by storage to even out the supply. It may also be found necessary to dry the material to some extent to prevent deterioration in store. Perennial crops or their by-products are different: they can often be taken at more-orless any season, however once again they will normally need to be dried either before or during storage

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It would be useful to have available methods of rapidly extracting energy from moist biomass materials without the need to dry and store or ferment them. This would allow collection (harvesting) and utilisation to be consecutive operations, thus tending to minimise cost. Moist fuels can be used in gasification plants and in very large furnaces, however the cost of these appliances is high, so in the current work at Nottingham the aim is to develop a fairly small, and reasonably cheap unit capable of using these intermediate moisture content fuels. The method selected - to use a fluidised bed combustion unit - is also expected to minimise the risk of producing polycyclic aromatic hydrocarbons in the flue gases. This is an important factor in biomass combustion because of the carcinogenic properties of these compounds. The addition of limestone or dolomite to the bed will also retain much of the sulphur present in the fuel. With the exception of pulverised fuel combustion systems, it is usual in conventional combustion equipment for the fuel to be fairly static in the combustion zone; in such conditions moist fuel will dry out only slowly. In fluidised bed units, however, the rate of heat transfer between particles is high; moist fuels should dry out quickly, their volatile components should be given off rapidly and combustion of the non-volatiles should be achieved in a short time. One of the chracteristics of the fluidised combustion of coal is that of carryover of ash and, in some designs of plant, of the elutriation of the bed material. Some biomass materials have relatively finely divided components, for example leaves and pieces of fibre, so elutriation of these fractions could cause a problem. The longer that such materials can be retained in the bed the better, so it was decided to feed the fuel into the bed below the surface rather than adopt the simpler approach of dropping it onto the bed (see Figure 1). Several other design features should minimise the problems of elutriation and moist fuel; these include (i) having a slotted fuel feed tube which runs through the bed, (ii) using a fluctuating velocity air supply to the bed so that for several periods of a few seconds duration each minute the bed is not quite fluidised, and (iii) having a large expansion chamber above the bed, with secondary air being introduced tangentially to encourage centrifugal separation of particles entrained in the flue gases. There is very little published work in this area and a large number of materials and design features need to be studied. Among the materials that will be used first are chopped cereal straw, freshly produced wood chips and bagasse pith: once the preliminary work on these three widely differing potential fuels has been started, work on mixtures of biomass fuels may well be undertaken.

Fluidised bed combustion of both light and wet biomass

Figure 1

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DEVELOPMENT OF A DOMESTIC FIREWOOD BURNER FOR COOKING S.G.MUKHERJEE Professor of Thermal Engineering Indian Institute of Technology, Kharagpur 721302 INDIA. Summary Combustion of wood is becoming increasingly important as a source of energy serving a rural population of 520 million people (1). Any improvement in efficiency in burning has considerable effect in saving country’s forest resources threatening ecological balance. The environmental pollution aspect of combustion of wood, is of importance because of the fact that firewood makes up more than the two-thirds of domestic fuel even in cities in India. Studies have been confined to a single oven, two ovens and three ovens burner and its efficiency is approximately 30%. The gaseous products are monitored using gas chromatography and a chemiluminiscent analyser and the particulate products are monitored using a smoke density monitor. A transmission electron microscope has been used to analyse the size and shape of the soot particles. The results confirm that the amount of pollutants products released are considerably less than the primary fossil fuels and that oxygen-rich conditions reduce the amount of carbon monoxide.

1. INTRODUCTION Because of poor quality of coal/coke and its trans-portetion problems, heavy drainage of foreign exchange for import of crude petroleum and difficulties with the nuclear energy programs, considerable attention has been directed towards renewable energy sources, of these, much attention has been given in the last few years to the use of biomass as a truly renewable energy source. of these, various ways in which biomass can be utilised, the simplest and most direct is by combustion of wood. Wood is, of course, not a new fuel and until about 1800 (2), combustion of wood formed the major source of energy in the world particularly in African and Asian countries. The rising demand of fuel wood for domestic and industrial use has been cited as being largely responsible for the increasing deforestation in India at over a million hectares a year. Firewood meets over 62 per cent of the energy needs of the rural areas and its present rate of consumption, is some 76 million tons a year, the bulk of which comes from Government controlled forest lands. The gathering of firewood for domestic use has been a full time occupation since long in many parts of the country and fuel wood shortage has been identified as a major obstacle to rural development. According to a survey by the National Commission on Agriculture,

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the present rate of wood production would leave a shortfall of over 50 million tons a year by the turn of the century. Since the demand in the country as a whole greatly outstrips supplies and the gap is widening, four times the current consumption of 133 million tons of firewood is likely to be required by the end of century. Rural families have no longer easy access to adequate quantities of firewood for cooking. Rainy season aggravates the situation. The present work is to develop a domestic firewood burner for a family of four members for the rural poor taking into account their food habits and customs with particular emphasis on the efficient use of firewood. Studies have been confined to a single oven, two ovens and three ovens burner. The pollution aspect of wood burning particularly in the formation of smoke and other pollutants have been investigated together with efficient use of firewood. Wood as a fuel must have certain special characteristics. Because it is based on cellulose it has a high oxygen content, therefore a low calorific value and this imposes a weight penalty if wood has to be transported any distance before it is utilised. Wood also has a low sulphur content and therefore gaseous pollutants produced are relatively sulphur-free. However, the major problem which arises from the combustion of wood is that it results in the formation of smoke and without the use of specially designed equipm-ent, smoke production is the main problem. 2. EXPERIMENTAL TECHNIQUL 2.1 Wood burning unit: An experimental burner was developed for investigation. It has an output of 10kJ hr−1 and a flue diameter of 10mm. The amount of combustion air entering the combustion chamber was controlled by adjustable door. The combustion of wood could be conveniently observed through a glass window. The main door had to be opened when more wood was added, which made it difficult to keep the air/fuel ratio constant all the time. Two litre capacity cooking vessel with water was used as a calorimeter and then subsequently food was cooked. 2.2 Wood samples used: Two types of wood were used as fuel—soft wood and hard wood. The wood was placed inside the combustion chamber in 50mm length. A complete analysis of a sample of soft wood was carried out to obtain its calorific value, moisture content, ash and volatile matter (3,5). 2.3 Analytical methods: Samples of flue gas were analysed using gas chromatography for carbon monoxide, carbon dioxide, and oxygen and using a chemiluminiscent analyser for nitrogen oxides. The smoke density was calculated using a smoke indicator which measured the transmitted light passing across the flue. The indicator consisted of a light beam projector

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and a photocell receiver. The light beam from the projector was aligned across the flue and attenuation upto a maximum of 100% could be measured. Smoke was collected from wood burner for examination in a transmission electron microscope. A copper electron microscope grid with a farmvar (polyvinyl formal) support film was inserted carefully into a metal probe. The probe was placed in the wood burner above for about twenty seconds. After removal of the probe, the grid was examined in the electron microscope to analyse the particle size and shape (4). 3. EXPERIMENTAL RESULTS 3.1 Analysis of wood: The soft wood was analysed and the following results were obtained: calorific value 2.26×104 kJ/kg−1 moisture content 7.4% ash content 0.15% volatile matter (−H2O) 80.9% 3.2 General behaviour of wood combustion and gas analyses: In the first experiment a known amount of soft wood was burnt firstly with the air door fully open and secondly with the air door half open. Its behaviour during combustion was observed. In the second experiment the soft wood was added at three intervals of time during combustion and another experiment was performed on batch process. The mean observed concentration of smoke was 1.7mg l−1 of flue gas. 3.3 Calorimeter experiment: By using cooking vessel as a calorimeter and thermopile, heat used was computed and it was found that out of the total calorific value, only 30% was utilised for cooking purposes. 4. DISCUSSIONS 4.1 General nature of wood combustion: Wood is normally burnt either in the open, in open fire places or in single stage-closed combustion units as used here. It could also be used in two-stage combustion units in which any carbonaceous material is burnt out in the second stage. Although the latter is preferable but the poor rural people can hardly afford it because of its complexity, cost and poor maintenance. The studies undertaken here were carried out with excess air. With limited amounts of air, the results are relevant to both direct combustion and to partial combustion i.e.

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gasification. The important variable that affects the value of wood as a fuel is its moisture content, Some aspects of the composition and combustion properties of wood are compared with those of LPG gas in Table 1. Tables 4 (a) and (b) give theoretical concentration of combustion products, taking NOX as negligible from hard wood and soft wood with different amounts of air present.

TABLE 1. Combustion properties of wood gas & natural gas (dry basis)7 Property

Wood gas Natural gas

Flammable limits in air (volume %) Lower 12 Upper 74 Composition ( volume % ) Methane 1 Ethane – Carbon dioxide 6 Nitrogen 50 Carbon monoxide 30 Hydrogen 10 Tar and oil vapours 3 Heat content ( kJ- kg−3) ) 1.08×104 Approximate flame temp K 1760 m3 dry air / m3 gas 1,59 kJ kg−3 of gas-air mixture 4.15×103 m3 combustible flue gas products/m3 gas 1.83 kJ kg−3 combustible flue gas products 5.86×103

4.8 13.5 96.0 3.0 0.2 0.8 – – – 5.38×104 1927 9.65 5.18×103 10.6 5.20×103

5. CONCLUSIONS 1. Efficiency of burning can be increased and the burner may be supplied to the rural poor to save wood. 2. Wood is a relatively clean fuel apart from particulate material which is released. 3. In rainy season, the rural poor are put into difficulties of burning wood as the moisture content of wood is more resulting in great loss of calorific value.

6. REFERENCES 1, World energy supplies 1972–76 statistical paper J21, United Nations, New York 1978. 2. Berry R.I. An ancient fuel provides energy for modern times—Chemical Engg., 1980 (21 April), 87, No.8, 73–76. 3. SHAFIZADEH P and DEGROOT W.F. Thermal analysis of forest fuels, in fuels and energy from Renewable Resources ed. Tillman DA, Sarkanen K.V. and Anderson L.L. Academic Press, London 1977, pp 93–114.

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4. BOYDE A. Qualitative photogrammetric analysis and qualitative stereoscopic analysis of SEM images, J. of microscopy, 1973, 98, pt 3 p 452–471. 5. AROLA RA. Fuel definition and analysis, in wood energy ed. Hiser M.L. Proc. 1977, Gov. William G.Milliken’s Conf. Ann Arbor Science, pp 43–52.

JOINT ENTERPRISE AND UTILIZATION OF A BRIQUETTING PLANT FOR STRAW M.BRENNDÖRFER Kuratorium für Technik und Bauwesen in der Landwirtschaft e.V. 6100 Darmstadt, Federal Republic of Germany Summary Combustion of cereal straw as bales or loosened material brings along some serious disadvantages: low bulk density, handling difficulties while charging the furnaces, technical problems with combustion and high emissions. By using high compression to make briquettes, cobs or pellets out of straw it was expected to solve these difficulties. Briquetting plants are expensive however. This is why nine agricultural and one non agricultural partners formed a cooperation for the joint operation and use of a briquetting plant. Its purpose is to cover their own energy demand and to sell briquettes to external customers, also to the non agricultural users. According to present operation experience the operating reliability can be considered as good. Cost for producing briquettes depend on the rate of utilization, organization and preparation. At an optimal utilization rate of about 1000 hours/year the production cost amounts to about 145DM/ton of briquettes with 40% subside and 180DM/ton without subside. Combustion of these briquettes resulted in very low emissions (dust content), which are fully in accordance with the emission standards of the Federal Republic of Germany.

1. Introduction In 1982 a cooperation for the joint operation and use of a briquetting plant was founded by nine farmers and a non agricultural partner in Aarbergen-Panrod near Wiesbaden, Germany. The objective for this joint enterprise was: – the common purchase at equal shares – the common installation and – the common use of a straw-briquetting plant. This plant was subsidized by the Hessian State with 40 percent. The straw briquettes are used for the individual house heating. By using high compression to make straw briquettes it was expected to solve the difficulties which exist in combustion, air pollution and handling. Briquettes are one particular type of stampings. Their characteristics are shown in table 1. In comparison to other types of fuel briquettes have advantages as well as disadvantages:

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advantages:

– high volumetric density and energy density – advantageous transport and storge – marketable fuel – good combustion characteristic, low emissions – applicability of serial furnaces disadvantages: – high investment and energy input for briquette production – riquette quality depends on density, species and humidity of straw – poor ignitability – marketing organization is not yet available – unsufficient experience in the field of combustion.

Table 1: Characteristics of stampings stampings diameter mm lenght mm bulk density kg/m3 Briquette Cobs Pellets

40–100 15–30

50–250 1)

300–450 400–600 450–600

6–12

1) Length differs according to cooling track and purpose

Table 2 presents important characteristics of straw briquettes in comparision to other briquettes.

Tab. 2: Physical criteria of different fuel briquettes in comparision Heat/value 1) kWh/kg

Density kg/m3

Bulk density kg/m3

Storage requirement m3/t

Energy concentration MWh/m3

3,3 2) 2,5 3) 2,0 4) 4,0–4,6f 4, 3 3,5–4,5 4, 0 5,4–9,2

800–1400 800–1400 800–1400 1 000– 1350 ~1000

300–450 300–450 300–450 600–800

2,2–3,3 2,2–3,3 2,2–3,3 1,3–1,6

0,99–1,48 0,75–1,13 0,6–0,9 2,58–3,44

650–750

1,3–1,5

2,6–3,0

Coal 1000–1700 1) air-dried fuel 2) oil/straw ration 1:3 (theoretical) 3) oil/straw ration 1:4 4) oil/straw ration 1:5

700–820

1,2–1,4

5,11–5,98

Form of briquette Straw

Wood Peat

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2. Technique of briquetting straw The working principle of the employed type consists of a piston unit with fly wheel drive. Presently there are 7 briquette plants of this principle in operation in Germany. A unit consists of the following parts: – chopper and mill with blower for straw bales – container, feed unit, dust filter – press with one or two extrusion tracks – cooling unit – switch and control box – electric motor – trailor with licence when used on different farms. The drive power needed is relatively high. In addition the chopper and straw mill have a high energy consumption.

Tab. 3: Drive power of a briquetting plant one tracks two tracks chopper and mill for straw 1) feed unit, dust filter press unit cooling unit TOTAL 1) in stationary use

22 2 19,1 0,5 46,6

22 2 38,2 0,5 62,7

Figure 1: Schematic layout of a press unit

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3. Organization All members are permitted to act according to theirs possibilities and needs. All decisions are made commonly by all members, one of them acts as a representative. All members have free access to the plant and can operate it with a special, personal identity key. The operation time is registered by an hour counter. This avoids any abuse or taking advantage. There is a special meter for service briquetting. Maintenance and repair is carried out by the members. To avoid defects in maintenance some operations are automized. The operating procedure can be arranged very flexible. This is why at the beginning as long as there existed a reduced electricity night rate briquetting often was carried out at night. To a certain extend a higher rate of utilization can result in lower electricity cost. Transportation of straw and briquettes are performed individually by each member, as members are briquetting for their own needs only. As the distances from the farms to the plant differ one can only calculate the transport capacity for the indivdual case. The everage distance is 2,7km. 4. Operating experience and results The operation of the plant was started in August 1983. In the first year the technical function was satisfactorily. The results of the first years are shown in table 4.

Table 4: Consumption of straw, briquette output and electricity consumption month

straw bales briquettes kg electricity kWh

August 1983 2 500 28 944 September 1983 730 7 299 October 1983 1 335 10 170 November 1983 2 210 10 150 December 1983 1 595 14 340 January 1984 2 353 21 383 February 1984 310 2 835 March 1984 2 230 22 725 July 1984 250 2 650 TOTAL 13 513 129 496 these of service briquetting 665 (4,9%) 6 895 (5,3%)

3 216 811 945 1 970 964 2 527 545 2 984 264 13 326

For the 129,5 tons of briquettes 404 operating hours were needed or 320kg/hour. The average energy or electricity cost amounts to 0,42DM/kWh and thus are relatively high. Only by means of a monthly maximum rate of utilization a minimization of electricity cost can be achieved.

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Measurements of emission at working condition showed a dust content of 76 to 294mg/m3 flue gas. Thus all emission results are in accordance with the emission standards of the Federal Republic of Germany. From the technical and funtional point of view the briquetting plant can be considered satisfactorily. The same applies to emission quality which results from burning of straw briquettes though existing and non specialized furnaces were used. So far the high investment cost (up to 200 000DM/ton of capacity per hour) and the economy of operation are still a problem. An input-output calculation of the first year of operation gives the following results:

Table 5: Calculation of cost Purchase Price

DM

76552,00 147000 (with subside) (without subside) 11482,80 22050

Fixed cost 15% DM (depreciation, interest, insurance) Utilization h/year 404 (1983/84 first operation period) Optimal utilization h/year 1000 1000 Fixed cost DM/h 28,42 11,48 22,05 Cost of current DM/h 13,96 1) 13,96 13,96 Repair, Maintenance DM/h 0,11 0,2 0,2 Labour cost DM/h none 2) none 2) none 2) Total cost DM/h 42,49 25,64 36,21 Output of the plant kg/h 320 320 320 Cost of briquetting DM/100kg 13,28 8,01 11,32 Cost of straw DM/100kg 6,50 3) 6,50 3) 6,50 3) Total cost DM/100kg 19,78 14,51 17,8 1) 0,43DM/kWh 2) briquetting for own consumption 3) local price

At cost of about 200DM/ton straw briquettes are in general compatible with brown-coal briquettes (260DM/ton) but there exist handling disadvantages. By increasing the rate of utilization cost can be reduced further. This can be achieved most effectively when a non agricultural customer with a high and continuous demand of briquettes can be found. 5. Literature (1) BOSSEL, U. (Hrsg.); Brikettieren und Pelletieren von Biomasse. SOLENTEC Fachbuchverlag, Adelebsen, 1983 (2) BEWER, E.; Technische Daten und Betriebserfahrungen zur Herstellung von Strohbriketts. Agrartechnische Berichte Nr. 17, Hohenheim, 1983 (3) BEWER, E., K.KAMM, K.-H.RÖHM; Verfeuerung von Strohbriketts in Kleinanlagen. Landtechnik 40 (1985), H.1, S.38 (4) BRENNDÖRFER, M.; Hat die Strohbrikettierung Zukunft? Lohnunternehmen 39 (1984), H.3, S.171–176 (5) Verschiedene Autoren; Brikettierung von Stroh zur Wärmeerzeugung. KTBLArbeitspapier 88, KTBL, Darmstadt, 1984

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(6) KAMM K., K.-H.RÖHM; Ermittlung von Emissionsfaktoren bei der Verbrennung von Strohbriketts in Zentralheizungsanlagen. Bericht der Landesanstalt für Umweltschutz BadenWürttemberg, Karlsruhe, 1985

PELLETIZATION OF STRAW C.WILEN & K.SIPILÄ Technical Research Centre of Finland Laboratory of Fuel Processing and Lubrication Technology SF-02150 Espoo, Finland P.STÅHLBERG & J.AHOKAS State Research Institute of Engineering in Agriculture and Forestry SF-03450 Olkkala, Finland Summary In Finland, heating with straw has been impeded by the lack of cheap and well-operating heating equipment suitable for straw combustion, in addition to abundant firewood and peat resources. Heating costs can be reduced by processing the straw to compressed products. The ratio of cost cut-down to the cost of compression is a decisive factor with regard to competitiveness. In Finland, the use of straw pellets as fuel has been the main object of research on compressed straw products. The present techno-economic study based on production experiments in practice concerns the production of straw pellets with a portable pelletizing unit. Studies of heating equipment have been focused on the operation of screw-fed solid fuel burners. Combustion of straw pellets with the solid fuel burners is hampered by the high ash content of straw and by the low melting temperature of ash. To guarantee a smooth operation, the burners must be equipped with ash handling equipment. The best results have been obtained for a burner with a moving step grate. In the size class of one-family houses and farms, heating with straw pellets is competitive with oil heating at the price of 330–580FIM/t. The production costs of straw pellets are 250–350FIM/t, if the raw material is delivered from the consumer’s own farm. If the raw material must be bought, the production costs are 350–430FIM/t.

1. INTRODUCTION With regard to increasing the use of straw, the use for energy is the most potential alternative. The energy use of baled straw is restricted by the lack of cheap small boilers suitable for straw combustion. The straw burns poorly in boilers designed for other indigenous fuels. This is due to a considerably lower energy density, a high proportion of ash and melting properties of ash. Baled straw can be effectively used for energy production only in boilers designed especially for this purpose. The price of these boilers is so high that their use is not economic unless the heat consumption exceeds 60 MWh/a. A more effective use of straw

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for energy production requires processing to compressed products. When using compressed straw products, the costs of combustion equipment, boiler room, fuel storage and heating work are lower. Hence, the costs of the actual compression compared to the benefit obtained are the decisive factor in the production of compressed straw products and in the costs of heating. 2. THE ENERGY CONTENT OF STRAW In Finland, the annual straw harvest is 1600–3000kg/ha with the present harvesting methods, the moisture content being 25%. The energy content is 5.5–10MWh/ha. Finland’s total annual utilizable straw harvest is about 2.2 mill. t. 15–20% of this is used mainly as litter and fodder. Only about 0.5% is used as fuel. The rest, about 80%, is either ploughed in the soil or burnt in the field. The energy content of this disposed amount is about 0.7Mtoe, which is calculatory sufficient to substitute totally for the light fuel oil used for heating houses and other buildings on Finland’s farms. About 70–75% of straw is produced in Southern and Western Finland. In these regions, the straw may locally be a very significant energy reserve, as there are no significant amounts of other indigenous fuels available. The low energy density of straw results in higher storage and heating costs and in part also in higher capital costs of the boiler and the boiler room. These costs can be reduced by processing the straw to fuel briquettes or pellets. The production costs of these products are the decisive factor with regard to the total costs. 3. PRODUCTION OF COMPRESSED STRAW PRODUCTS Two different compression techniques can be used: pelletizatlon or bri-quetting. In pelletization, ring or flat die presses are used. The material is extruded through a perforated breaker plate, and the products are small cylinders 6–20mm in diameter. Screw or piston presses are used in their manufacture. The processing of straw to pellets represents a more modern technique, which is fairly well developed for wood and peat. Pelletization and briquet-ting methods are compared with each other in Table 1. When the straw is compressed to briquettes or pellets, the bulk density of straw increases to 5–10-fold compared to that of baled straw. The moisture content of these products is 10–15%, density 450–650 kg/m3 and heat value 4–4.3kWh/kg, i.e. 1.8– 2.8MWh/m3.

Table 1. Comparison of pelletizatlon and briquetting methods. Pelletization

Briquetting

Moisture content 10–20 % Moisture content 10–15 % Maximum output of press 4–6 t/h Maximum output of press 1–1.5 t/h Energy consumption (chopping, Energy consumption (chopping, pressing) 80–90 kWh/t pressing) 40–50 kWh/t

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Straw must be chopped fine. Longer straw can be used. The size of the product is small , The same combustion systems as for automatized systems can be used. sod peat and wood can be used.

4. EXPERIMENTS ON THE PRODUCTION OF STRAW PELLETS Experiments on straw pelletization have been carried out by the Laboratory of Fuel Processing and Lubrication Technology of the Technical Research Centre of Finland and by the State Research Institute of Engineering in Agriculture and Forestry. The experiments were made with a portable pelletization unit constructed especially for this purpose. The intention was to study pelletization properties of straws of different cereals and to produce pellets from different straws for combustion experiments. The straws were pelletized without thermal drying. The portable pelletization unit consisted of a straw chopper, to which small bales could be fed, feeding equipment for chopped straw, and a flat die press. After the pelletization the pellets were cooled on a belt cooler. The portable pelletization unit is shown in Figure 1. It can also be used for pelletizing other raw materials. The output of the unit is 0.5–1t/h depending on the raw material used. The test equipment does not include a power source of its own.

Figure 1. Portable pelletization unit. There were no significant differences in the quality of rye, barley, wheat and oat straw pellets. The quality of pellets produced from turnip rape straw and from rush was significantly better than that of pellets produced from the other species. The strength of straw pellets is somewhat lower than that of peat and wood pellets.

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Table 2 presents the mechanical properties of straw pellets compared to peat pellets. The compression strength was determined with a compression strength gauge of Amandus Kahl type and the drum strength with a square tumbling can. These strength tests are generally used in fodder industry. The output of large presses is for straw 3–5t/h according to the manufacturers. It is technically possible to construct a portable straw pelletization unit with the output of 3t/h. The investment on such an unit with a diesel aggregate has been estimated at 1.3million FIM. The electricity consumption of the unit would be 80–90kWh/t, of which about a half would be used for straw chaffing.

Table 2. Mechanical properties of straw and peat pellets. Moisture % Bulk density kg/m3 Compress. strength kp Drum strength % Straw pellets Peat pellets

10–12 18–20 14–16 30–35

550 470 750 650

30 11 35 18

90 85 95 90

5. STRAW ASH In addition to the low energy density, other factors impeding combustion are the high ash content of straw and the melting behaviour of ash. The ash content of barley, rye and oat is about 5% and that of wheat 6–7%. The melting temperature of wheat ash deviates fairly clearly from those of the other cereals. In addition, the melting temperature of straw ash is affected by the soil and by fertilization. The ash melting temperatures of different cereals are presented in Table 3. The melting of ash at low temperatures results in difficulties in the operation of grates and ash handling equipment. The compression does not change melting properties of ash, and hence, the melting behaviour of straw ash should be considered in the design of boilers and stokers fired with compressed straw products.

Table 3. Melting temperatures of straw ash. Stage of melting Wheat

Temperature range, °C Rye Oat Barley

Initial deformation 900–1050 800–850 750–850 730–800 Hemisphere 1300–1400 1050–1150 1000–1100 850–1050 Flow temperature 1400–1500 1300–1400 1150–1250 1050–1200

6. COMBUSTION OF COMPRESSED STRAW PRODUCTS Compressed straw products can be burnt by stoker burners, the burner head of which is equipped with ash handling equipment. In the size class of <50kW the best results with straw pellets were obtained with a screw stoker, where the ash is removed with the aid of

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a moving step grate. The grates are powered by the fuel feed screw. The cost of a combustion equipment of this kind is about 500FIM higher than that of a wood chips burner with the same output. It is of significance to the operation of the burner head that the ratio of the length and frequence of grate movements to the rate of fuel feed is suitable. In the combustion experiments in the laboratory, a TP 30 burner was connected to a TULI 30 boiler, which is designed especially for stoker use. The results of efficiency tests carried out with barley straw pellets are given in Figure 2. The moisture content of the pellets was 13–15%. All the tests presented in the table were carried out at the same values of regulation. Hence, the adjustability of the equipment can be considered very good. An efficiency of >60% is achieved at the boiler load of >1.8 kW and that of >70% at the load of >2.8kW. This indicates that it is possible to achieve an annual efficiency of >65% in practice too. The moving step grate can also be used in burners with a higher efficiency, but it is difficult to estimate the upper limit of efficiency at this stage of research. 7. PRODUCTION COSTS OF STRAW PELLETS The production costs of straw pellets vary within a wide range in respect to both the production of raw material and the actual compression. As regards the raw material, it is of significance how the capital costs of the harvesting equipment are regarded in the price of the compressed product. When the consumer of the compressed straw product delivers the raw material and pays only for the compression, the costs of raw material are 100– 200 FIM/t if the harvesting equipment is used in a reasonable way. The purchase price of straw is 200–280FIM/t. The production costs of straw pellets with the portable pelletization unit were evaluated. The pellets would be produced in a pelletization unit of 3t/h. The unit would be in operation 9 months per year and it would be used in two shifts, i.e. the operation time would be 3200h/a. As the effective operation time is 70% and about 30% of the time is used for transports, starts, etc., the annual production of pellets is about 7000t. On this basis, the compression costs of straw pellets are about 150FIM/t. The production of pellets can be organized so that the pelletization unit stays 1–2 weeks in each village and the local farmers bring their straw for pelletization. If the unit can be connected to the electricity network of the village, the price of electricity is essentially lower and the compression costs of pellets are about 120FIM/t. Alternatively, the unit can be moved from one large farm to another, but in this case the amount of pellets should be about 100t/farm. The production costs of straw pellets are 250–350FIM/t when the consumer delivers the raw material. If the raw material must be bought, the production costs amount to 350– 430FIM/t. The costs of straw pellets produced with the portable unit are about 10% lower than those of pellets made in a stationary unit.

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Figure 2. Efficiencies of the TP 30 burner and the TULI 30 boiler with straw pellets and at different boiler loads. In the size class of <50kW, heating with straw pellets is competitive with oil heating at the price level of 330–580FIM/t. The situation is most unfavourable to the straw pellets, if new facilities must be built for the heating unit, a short period of repayment and a high rate of interest are used. The straw pellets are competitive with oil in such a situation when the heating unit is placed in an existing building and the use of indigenous fuel is supported by subventions and by loans at a low rate of interest. 8. CONCLUSIONS When straw is processed to a compressed product, considerable savings are obtained in the costs. At farms, compressed products can be burnt with solid fuel burners equipped with ash handling equipment. The equipment and heating costs are of the same magnitude as for the other solid fuels. The storage costs are lower due to the high density, although a better storeroom is required for the straw pellets due to their poor weather resistance. On the basis of production costs the straw pellets are in certain cases a competitive fuel compared to oil.

CHARCOAL AS FUEL: NEW TECHNOLOGICAL APPROACHES J.F.GOUPILLON CEMAGREF B.P. 121 92 164 ANTONY Cedex (France) Summary Charcoal is widely utilized in the world to meet household needs (cooking) and handicraft needs (forges…) because it is easy to use and to store. Moreover, it is known to gasify readily which makes possible the setting up of reliable and easy to maintain plants. It derives from these characteristics a marked superiority when it comes to decentralised production of mechanical energy from biomass in developing countries. Direct applications are electricity generation, water pumping and transport. CEMAGREF has lately developed highly satisfactory plants to meet these needs, taking into account as much as possible local technical conditions. How can a wider distribution of this equipement be attained? – by greatly improving the production and the economic of wood carbonization, – by utilizing many other vegetable products, crop residues and energy crops, – by developing compact gas generators to better suit vehicles and machines of all sizes. In these three fields, CEMAGREF has developed equipment and techniques which are described in this presentation. – coal dust pelletization and compaction device, – small size multi-product carbonizer for straw and grass in particular. – medium size biomass gasifiers for the production of both purified gases and charcoal. – compact charcoal gasifier with separate feedstock tank for vehicles. This equipement will permit-and already partly does- the development of complete technical processes, more or less decentralized, which will economically produce charcoal for traditional use on the one hand and as a substitute for fossil fuels on the other.

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1. INTRODUCTION Charcoal is a fuel widely utilized worldwide, especially in developing countries to meet household needs such as cooking (in towns mainly) and handicraft needs such as forging (for the manufacturing of agricultural tools…) Charcoal is a low-cost fuel with the following advantages: – long proven manufacturing techniques, – high heating value, – ease of storage and transport, – clean combustion. Moreover, it is known to gasify readily and produce a gas that can be used in engines without requiring sophisticated nor costly systems. Developing countries nowadays urgently need decentralized mechanical energy for electrification, pumping, irrigation and transport purposes. We wish to illustrate that plant charcoal derived from biomass can be of interest for such countries. We will elaborate later on the conditions needed for this process and the solutions proposed by CEMAGREF. No one has get satisfactorily met the strong demand for techniques leading to biomass conversion into mechanical energy through gasification, especially for small gas producer-engine systems. Research has only borne on antiquated, complex and unreliable processes, unable to make the most of the more widespread feedstocks. Upgraded and increased by the development of new techniques, charcoal production will no doubt enable major breakthroughs to be made. Let’s underscore that the basic feedstock is agricultural. Agriculture in developing countries could make use of untapped potentials provided that it has energy, at least for irrigation. Hence, its energy production will greatly exceed its own needs. Conversely, under prevaiting economic conditions, developing countries cannot become major food producers unless agriculture helps them generate their own energy. But feedstock conversion remains a problem area. 2. NATURE OF THE FEEDSTOCKS Apart from wood which will still be plentiful in some countries, feed-stocks include straw, rice hulls, coffee husks and grass. In the near future, energy crops such as giant reeds will join them. We are not in a position to process these materials efficiently because they must be aggregated into briquettes. This is expensive and the performance of gasifiers are uneven. How about producing charcoal? The resulting material would be small coals and coal dust whose pelletization with a “ball-making machine” or an extruding press is easy and inexpensive. The pellets would then be used in a simple, reliable and light gasifier. We have already tested it. Charcoal must now be produced.

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To this end, we are aiming at two objectives: – mobile carbonization using agricultural raw materials such as straw (rice straw mainly), grass. We built a mobile unit to carbonize bundles of straw and stalks, capable of producing about 300kg of charcoal per hour. – stationary carbonization using factory by products like rice hulls, husks (coffee, groundnuts…) We are now working on the total supsension process for this type of feedstock. Moreover, we developed a gas/coal production process with a fixed-bed gasifier with gas recycling. It allows stationary plants to produce gas and charcoal, charcoal to be used in small decentralized plant. Therefore, we could soon offer a whole range of equipment capable of using most of the more widespead feedstocks. Yet, current pelletization techniques can greatly increase the efficiency of conventional wood carbonization in the forest by making use of small coals. About 30% of the coal is wasted, mainly on the spot and partly during transport. It has been shown in Sudan that the cost of a pelletization plant installed at the retailer’s can be recouped in less than one year. There are also gas generation plants. The engines must then work properly. Their performance must be satisfactory and they should not require a permanent operator. In short, performance must match that of Diesel units as regards: – reliability, – performance stability, – ease of management. To this end, certain fonctions of lean gas engines, that is air/gas mixture ratio and ignition timing, must be automated, as is already the case on petrol and Diesel engines. Owing to the characteristics of lean gas and fuel supply (LCV, air/gas ratio, varying pressure and composition), the systems available with petroleum fuels cannot be used. But it is possible to develop a standard system f rom automative components suited to gasifiers and producer-engine systems as for is air/fuel ratio and ignition timing (or pilot injection) are concerned. The components used are those of the latest electronic injection systems, namely mass flow meters “λ” and speed sensors. The management microprocessor will be the only system to be specific for lean gases. It will enable a given engine to work with any gasi fier without any previous adjustment. CEMAGREF”s most urgent goal is twofold: – develop expertise to utilize the most common feedstocks, – fit engines with the necessary automation systems. In the medium term, coal gasifiers can be made more compact in order to be rationally mounted on small size machines. The active portion of a coal gasifier is very limited. Most of the volume is occupied by the feedstock tank which is an idle portion, as opposed to wood gasifiers whose feedstock tank is used for feedstock drying and carbonization. The tank can be separated from the furnace for design simplification. The heating value of pelletized coal is very high. Therefore the tank can be small (only twice as big as a Diesel tank instead of 6 times with

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wood coal lump gasifiers for the same autonomy). On the other hand, the furnace volume can be dramatically reduced (6 times smaller) by injecting air through a grate of the right shape. Such a furnace was satisfactorily tested at CEMAGREF. As a result, these new techniques help reduce the size, the weight and the cost of gasifiers. In conclusion, we are emtilled to assert that carbonization is the prerequisite for the development of biomass gasification. Then, developing countries’ specific needs for calorific and, most of all, mechanical energy could be met. Carbonization could be centralized or decentralized. Simple, reliable and easily managed gasifiers could be utilized, provided that engines can be efficiently adjusted.

MOBILE PYROLYSER FOR STEM SIZE PRODUCTS

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RESULTS FROM RESEARCH WORK IN HEAT GENERATION FROM WOOD AND STRAW Dr. A.Strehler TU—München Bayer. Landesanstalt für Landtechnik D-8050 Freising Summary Research work on energy from biomass in Weihenstephan began 1974. First the fuel straw was characterised by determining its calorific value, taking into consideration moisture content, storage conditions, species, varieties, growth conditions and fertilization. Other characteristics of the strawsuch as percentage of volatiles and chemical elements, demand for combustion air and specific fuel gas volume—were determined. Measurements were made with commercial furnaces; through-burning types, under-burning types and furnaces with automatic charging systems. Test runs were also carried out on prototype furnaces of different systems. A special heat generation system has been developed together with the industry. Different types of furnaces were constructed, using pressure bales, roto bales, wood pieces and wood chips. Economic calculations show that straw and wood waste are cheap fuels under certain conditions. The main problems in straw and wood combustion are: – combustion quality – costs – efficiency – material (thermal and chemical stability). – workload

Combustion quality has to be improved in all types of furnaces, mainly in case of straw.

1. INTRODUCTION Large quantities of surplus straw and wood waste are available as an energy resource in the Federal Republic of Germany and other countries. The heat demand of most farms could be meet completely with these biomass fuels in some regions. In certain wood or cereal producing regions, biomass is generally produced in surplus. In this case, the transport of biomass is necessary to supply consumers in other regions. In FRG 5 Mio t of straw could be available for heat generation. Resources of wood are much higher, but the present non-utilized quantity of fuel wood is in a range of 2–3 Mio t/a. Additionally there will be a tremendous quantity of fuel wood as a result of the wood dying in the next

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years. Another resource can be seen in energy plantations, which might be available in future years in order to reduce the problems of financing the EEC agricultural market. Rape, other oil plants and short-rotation forests are good options. Rape for example could deliver oil, fodder (pressing residue) and straw (bales and briquettes). On the basis of the available and future resources, research work has been carried out in Weihenstephan since 1974 on the production of energy from cereal straw and, since 1978, also from wood waste. Sponsors are the Commis-ion of European Communities, Research Ministery, Bonn and the Agricultural Ministeries in Bonn and Munich. Measurements were made at the testing facilities in Weihenstephan (Figure 1) and during practical application in farm dwellings.

Figure 1: Boiler test unit in Weihenstephan This research work was done with following types of fuel: – straw – small and big straw bales – sawdust – short and long wood logs – bark briquettes – wood chips. – pellets

Types of furnaces investigated: single stoves, boilers with bottom-burning and through-burning systems of various capacity with discontinuous charging; boilers and furnaces with automatic charging Important criterion for investigations: fuel moisture content; temperatures in fuel, boiler water, flue gas, ambient air; flue gas quality: CO, CO2, O2, CnHm, dust+tar. Work load for charging and service power, efficiency, ash quality thermal and chemical stability of material in hot parts of the furnace.

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2. SELECTED RESULTS 2.1 STRAW BRIQUETTES IN STOVES In hot stoves the combustion quality was better than in cool boilers. Slag was observed when boilers or stoves had temperatures of more than 900° C in the fuel itself. Single stoves had CO2 contents mainly between 8 and 12% with extremes of 2–16%. Gas temperatures in the stove were from 700–800°C, flue gas temperatures 300–400°C, fuel temperatures 300–700°C. Table I shows individual results for two types of stoves

Table I: Test results of straw briquette combustion in different stoves type of stove/ combustion system

Koppe KK Koppe KH 56 Koppe KH 56 Koppe KK 400/UB A/DB A/DB 400/UB straw briquettes straw briquettes straw briquettes coal briquettes (diameter diameter 80mm) (diameter 80mm) (stone coal) 80mm)

duration of test 6.73 h (hours) fuel: – density (kg/dm3) 0.900 – total inweight (kg) 15.8 – consumption (kg/h) 2.35 – number of charges 2 results from to CO content in flue 0.01 1.4 gas (%) CO2 content in flue 1.3 14 gas (%) temperature (°c) – flue gas 285 700 – ember bed 552 912 – sec. comb. chamber 302 708 211 233 dust emission soot (BACCHARACH scale) efficiency nominal power (kw) measured power (kW)

1

9

7.75 h 0.900 26.2 3.25 7 from to 0.55 0.22

6.76 h

2

6.5

1.4

435 721 483 217

480 570 440 762 581 839 860 1034

5

1

7.8 55.9 43.2 17.2 5.8 0.8 5.6 4.4 2.5

0.935 29.0 4.29 8 from to 1.8 0.01

17.2 12.2

3.05 h

2

3.6

12

9.04

501 390 782 575 812 661 597 497 1630 1260 62

628 898 890 121

532 858 800 89

2

2

65.2 54.4 14.9 56.7 41.1 33.9 61 7.0 7.0 9.9 8.4 2.6 10.2 7.4 3.5 6.3

59.3 5.8 6.1

9

2 13.7

– 3.6 0.93 1 from to 1.7 0.07 0.83 0.245

525 615 735 947

427

563

8

1

9

8.9

7

1

Conclusion: Efficiency too low; combustion quality has to be improved with emissions below 150mg/m3.

Results from research work in heat generation from wood and straw

887

2.2 STRAW BRIQUETTES IN SMALL BOILERS Test results are shown in Table II.

Table II: Test results of straw briquette combustion in bottom-burning furnaces (density 0.935kg/dm3, diameter 50mm) firm/type

Fischer GA 32 HDG 43 A Sieger FBU 28

nominal power (kW) 37 duration of test (hours) 4.35 fuel inweight (kg) 38 number of charges 2 results from to CO content in flue gas (%) 0.09 0.98 CO2 contains in flue gas (%) 7 12 temperatures (°C) – flue gas 225 255 – ember bed – sec. comb. chamber 629 870 scot (BACCHARACH scale) 5 8 498 951 dust emission

43 28 5.28 5.67 59 48 2 2 from to from to 0.32 0.06 1.2 0.32 0.08 1.18 0.38 10 7 16.5 11.5 6 13 9.57 239 230 300 255 827 782 931 850 887 1 8 627 312 530 401

efficiency (%) measured power (kW)

80.8 28.9

195 988 720 1 466

78.1 35.8

327 522 382 6 674

258 838 592 601 75.8 26.3

Conclusion: Flue gas temperatures are slightly high; too much emission. Design has to be improved. 2.3 STRAW AND WOOD IN LARGE BOILERS Tests with different fuels in a large bottom-burning boiler with wood, bales and straw briquettes show better results than small furnaces (Table III).

Table III: Test results of wood and straw combustion (bottom burning furnace) fuel

wood logs

straw (HD- straw briquettes (80 straw briquettes (50 bales) mm diameter) mm diameter)

– density (kg/m3) 0.045 0.900 – total inweight (kg) 61.45 108.00 82.45 number of charges 1 3 1 duration of test 4.80 5.68 4.80 (hours) from to from to results from to CO content in flue 0.04 1.22 0.1 0 2 0.32 0.06 1.2 gas (%) CO2 content in flue 6.20 16.2 11.0 0 16 6.00 6.00 17.0

0.935 92.30 1 5.92

0.25

from 0.06

to 1.7

0.35

11.00

2.70

14.5

10.20

Energy from biomass

gas (%) temperatures (°C) – flue gas – ember bed – sec. comb. chamber dust emission soot (BACCHARACH scale) efficiency (%) measured power (kW)

888

293 370 330 270 400 328 714 978 852 650 911 451 702 1066 906 688 1020 822

274 837 716

392 990 1026

341 899 866

246 527 718

399 1082 966

330 820 873

17 178 96 370 586 478

184

253

212

150

618

344

4

1

6

3

1

8

4

66.9 50.0

53.0 39.0

75.0 55.5

71.9 53.2

31.6 20.2

73.6 47.0

71.8 45.9

1

9

6 76.2 42.5

2

9

Conclusion: The combustion quality is better than the furnaces shown in Table I and II but not good enough. It is necessary to change the furnaces to attain less emission. The improvement of furnaces is done together with manufacturers. 2.4 WOOD COMBUSTION IN LARGE BOILERS In special boilers, dry wood is utilized meanwhile with good success; the efficiency is high enough, the combustion quality good enough to meet strict regulations. Figure 2 shows a furnace for big wood logs, developed together with a manufacturer. The bottomburning system with well-adapted secondary combustion chambers and a large heat exchanger, guarantee a high efficiency with low emission and small work load, when the boiler is connected to a large heat store (water tank).

Figure 2: Boiler with bottom-burning system

Results from research work in heat generation from wood and straw

889

2.5 COMBUSTION OF WOOD CHIPS Wood chip combustion is well developed with many systems. The newly constructed prefurnace with a movable grate also allows a high efficiency and low emission with chopped straw, even without slag problems (Figure 3).

Figure 3: Prefurnace with movable grate 2.6 LABOUR COSTS Figure 4 demonstrates the dependence of combustion system, power, specific price, saving of fuel oil, quantity and labour costs.

Energy from biomass

890

Figure 4: Labour costs in combustion of straw and wood

BASIC OF THE COMBUSTION OF WOOD AND STRAW M.Hellwig TU—Munich Bayer. Landesanstalt für Landtechnik D—8050 Freising Summary The fuels wood and straw are characterised by a low carbon content (50%), a high oxygen content (up to 44%) and a large percentage of volatiles (up to 85%). More than 2/3 of the heat content of these fuels can be stored in the volatiles. These products burn in the gaseous phase and produce large flames. The reaction products must be completely combusted before leaving the chamber. This requirement is not met in many practical cases, and thus the emissions with wood and straw are much higher than with fossil fuels.

1. FUEL CHARACTERISTICS The chemical and physical properties of wood and straw are important and influence the design of combustion systems. The elementary chemical composition and calorific value of the dry matter is essentially the same for all types of wood and straw, regardless of whether its conifers or deciduous trees or what type of cereal straw. From Table I, it can be seen that in comparison, wood and straw have relatively little carbon and very much oxygen. The biomass fuels contain hardly any nitrogen and sulfer. The high oxygen content leads to a high reactivity at normal combustion temperatures and thus a rather rapid combustion.

Table I: Ultimate analysis and heating value of solid fuels

Fuel Type

Ultimate Analysis % (Dry Basis) C 0 H N S

Wood 50 44 6 – – Charcoal 90 7 3 – – Straw 51,9 41,4 6,1 0,5 0,1 Peat 55,5 37,5 5,8 0,9 0,3 Brown Coal 63–74 16–26 5–6 0,9–1,9 0,3–3,9 Coal 81–92 1,4–10 4–5 1,2–1,7 0,6–1,4 Coke 90–98 0,5 0,3–3 0–0,9 0,6–1,2

Net Heating Value (Wet Basis) kJ/kg 15200 31300 14200 13500 13600 29500 25900

Energy from biomass

892

The immediate analysis gives concrete results on the behavior of the fuel within the combustion chamber. Information is obtained on the moisture content, ash content, volatiles and the solid carbon content. From Table II it can be seen that wood and straw are the richest in volatiles. The moisture content is one of the most important combustion parameters, which greatly influences the calorific value as well as the quality of combustion. A high moisture content reduces the combustion temperature which in turn hinders a total combustion of the reaction products.

Table II: Proximate analysis of solid fuels (wet basis) Fuel Type Moisture (%)

Ash (%)

Volatile Matter Fixed Carbon (%) (%)

Wood (dry) – 0,5 85,5 14,5 Wood 12..15..40 0,2..0,5..0,8 70..75..78 5..10.. 15 Charcoal 2..4..8 0,5..2,0..3.5 10..15..25 65..80.. 85 Straw 8..10..14 4.. 5 .. 6 63..65..67 15..20..25 Peat 20..25..35 1..2..3 50..55..60 5..12..20 Brown Coal 12–25 3–15 40–60 15–30 Coal 1–6 3–15 10–35 50–80 Coke 3–15 9–17 0–10 70–90 * Moisture+Ash+Volatile Matter and Fixed Carbon=100%

The volatiles are those products which are set free when the fuel is brought to the combustion temperature. These gas products influence the combustion process and the design of the combustion chamber. 2. COMBUSTION OF BIOMASS The burning process of a fuel rich in volatiles, e.g. wood and straw, is illustrated schematically in Figure 1. When heat is applied, the fuel is initially dryed and the moisture completely driven off. Above 150°C, the thermal reaction begins and proceeds slowly up to 200°C. At 275°C, the reaction acceferates rapidly and an exothermal process starts which suddenly sets the volatiles free. The volatiles consists largely of hydrocarbons (CnHm), carbon dioxide (CO2), carbon monoxide (CO) and hydrogen (H2) along with tar residues and water vapor, which burn as gas products in the flame. Solid carbon remains which burns slowly and without flame in the embers.

Basics of the combustion of wood and straw

893

Figure 1: Stages in woodburning Figure 2 shows how the released heat is distributed in the two-phase combustion of wood and straw. With these fuels, over 2/3 of the calorific value is released through the combustion of volatiles. Thus it is necessary to supply combustion air at two points; primary air for the solid carbon and secondary air for the gas products. Calculations show that 66% of the stoichiometric air supply is needed as secondary air. Theoretically the solid carbon can first be converted to CO and then out-side the bed, burnt to form CO2. Here, the secondary air can be increased to 83%. These results are shown in Figure 3.

Figure 2: Distribution of the heat of the combustion of wood and straw fuels

Energy from biomass

894

Figure 3: Relationship between primary and secondary combustion air for wood fuel 3. COMBUSTION PRODUCTS When the combustion of biomass is complete, the flue gas contains only CO2, H2O, N2 and O2. The relation between combustion products and combustion air supply (air excess) can be shown in a simple way graphically. Figure 4 illustrates the combustion triangle for wood. From this, the quality (completeness) of the combustion can be determined easily and clearly.

Figure 4: OSWALD-combustiontriangle for wood fuel

Basics of the combustion of wood and straw

895

During biomass combustion, however, a number of intermediate arise, especially in the combustion of the volatiles. The by-products CnHm, CO, tar and soot can occur. When not completely combusted, they cause harmful and noxious components in the flue gas. Incomplete combustion occurs under the following conditions: 1. General or local combustion air deficiency. 2. Sudden cooling of the fire gases or flame, e.g. on water-cooled surfaces or through the supply of cold secondary air. 3. Poor mixing of the combustible products with air. 4. Delay time of the combustible gases in the chamber is too short. 5. Temperature in the reaction zone is too low. Harmful emissions such as SO2, NOX and fly-ash can also anise. Due to the low sulfer content and low combustion temperature, only very small concentrations of SO2 and NOX occur. The fly-ash concentration however can be appreciable, especially with straw which has a high ash content. Figure 5 shows the intermediate and gasification products of wood by incomplete combustion. The amounts depend on how the fuel is prepared, the combustion chamber and the combustion characteristics.

Figure 5: The combustion products of wood and straw fuel

Energy from biomass

896

A comparison of emissions can be made after analysis the flue gas of furnaces with various biomass and fossil fuels. Average values for the emissions are given in Table III. It can be seen that in comparison, wood and straw have a higher solids content and higher CO and CnHm concentrations.

Table III: Typical average concentration of pollutants released during combustion of various fuels in home heating units Wood Straw Brown Coal Coal Coke 011 Gas Particulates (g/GJ) 500 600 350 300 70 B (9/GJ) 8000 14000 5000 5000 6000 30 (9/GJ) 150 1500 200 400 10 15 (g/GJ) 20 20 20 40 70 40 (g/GJ) 0 500 5500 900 900 150 Source: Davids 1977, Cooper 1980 and own measurements

1 30 15 30 10

4. CONCLUSIONS An improvement of the combustion quality and thus the reduction of emissions can be achieved with combustion systems optimised for the given fuel. The following three rules are to be observed: 1. The fuel should be fed continually into the reaction zone (continuous feeder or underburner systems). 2. The combustion air should be well mixed with the fuel and gas products. 3. The combustion products should remain in the combustion chamber for a long time at a high temperature.

REFERENCES: (1) GUMZ, W.: Kurzes Handbuch der Brennstoff- und Feuerungstechnik, 3. Auflage.—Berlin: Springer 1962, 749 S. (2) HOFSTETTER, E.M.: Feuerungstechnische Kenngrößen von Getreidestroh, Dissertation, Technische Universität München.—Freising-Weihenstephan, 1978. (3) DAVIDS, P., GLIWA, H.: Emissionsfaktoren für Feuerungsanlagen für feste Brennstoffe, Nr. 98, Heft 3, 1977, S.58–68. (4) COOPER, J.A.: Environmental impact of residential wood combustion emissions and its implications.—In: Journal of the Air Pollution Control Association, Vol. 8, No. 8, 1980, S.855– 861. (5) WAGNER, W.: Berechnung von Holzfeuerungen für Wärmeträgeranlagen.—In: Wärme Band 85, Heft 4/5, 1978, S.77–82.

TEST RESULTS FROM PILOT PLANTS FOR FIRING WOOD AND STRAW IN THE FEDERAL REPUBLIC OF GERMANY U.Kraus TU-München Bayer. Landesanstalt für Landtechnik D—8050 Freising Summary Pilot plants for wood and straw combustion in the Federal Republic of Germany are intended to provide valuable knowledge on the function, energy efficiency, environmental hazards, operations and the economy of such systems. Financial support for the construction of the plants and the scientific supervision is provided by Federal and State Ministeries. Woodchips furnaces are technically well developed; the combustion quality is good, the emissions are far below the legal regulations for environmental protection. Depending on the particular design and capacity, the costs lie between 200 and 580DM/kW of treat generated. The costs per kWh are 9.7–12.1 Pfennig depending on the operation. Plants for firing straw show partially good combustion qualities, however the efficiency needs to be improved and the emissions further reduced. The investment costs run up to 200DM/kW of heat generated for hand-fed plants and up to 440DM/kW for systems with automatic feeders. 1. INTRODUCTION The Bay. Landesanstalt für Landtechnik supervises wood and straw pilot plants, whose construction and scientific personnel is supported by various Federal and State Ministeries. In particular, the granting agencies were the Federal Ministery for Nutrition, Agriculture and Forests, the Federal Ministry for Research and Technology as well as the Bavarian State Ministry for Nutrition, Agriculture and Forests. With the help of the pilot plants, the goal is to gain practical experience with new technologies for firing wood and straw and to communicate the results to manufacturers and potential users. The Scientific supervision includes the planning of the plant and usually an extensive program of measurements. Data is collected on the flue-gas composition (CO, CO2, O2), flue-gas and combustion temperatures, solids emission, heat input and output, the necessary auxiliary energy for plant operation and fuel preparation as well as the labour required for fuel collection and combustion. 2. MAIN RESULTS FROM THE WOODCHIP PLANTS The 16 woodchip plants with capacities from 30 to 500kW are used to heat farm dwellings and public buildings. These consist of 9 pre-furnace plants (see Fig. 1), 3

Energy from biomass

898

Stoker systems, 1 underfeed unit for fine woodchips and 3 bottom-burn boilers (see Fig. 2) for larger chips from forest wastes.

Figure 1: Pre-furnace for fine woodchips (system Hansen) with boiler

Figure 2: Boiler (bottom-burning) with automatic feeder for coarse woodchips (system Kopo)

Test results from pilot plants for firing wood and straw in the federal republic of Germany

899

The measurements for all plants show a good combustion quality (Tab. I). At high combustion temperatures around 1000°C, the CO2 content in the flue gas is 12–13% (combustion air excess=1.7) and the CO content 0.07–0.38%. Thus a firing efficiency of over 85% was reached and with the stoker system, a boiler efficiency of 85%. Prefurnaces result in a partial radiation loss, which accounts for large differences between the firing and the boiler efficiency. The solids emission in the flue-gas was in the range (at 12% CO2), which is far below the allowed value of 300 in the Federal Republic of Germany. The energy consumption in producing woodchips corresponded to about 1% of the wood’s heating value in two tests for both fine and large chip sizes. Depending on the method, the labour for producing chips can be given as 3 to 6m3 per hour per man.

Table I: Essential results of measurements on woodchip firing plants (full load operation)— Preliminary results Title Columm 1 Number of plants measured Length of test CO2 content flue gas(ave.) CO content flue gas(ave.) Flue gas temperature Ember bed temperature Flame temperature Solids emission Firing efficiency Boiler efficiency

Unit

Pre-furnace system 3

Stoker system 4

Under-burning boiler (coarse chips) 5

6

1

2

h %

1–3.5 7–12.2

2–2,6 11.75–12.5

1,3–3,2 11–13

%

0.07–0.2

n.e.

0.2–0.38

°C °C

190–390 850–ca. 1000

220–320 n.e.

195–370 880–ca. 1000

ca. 900 84–162

850–890 84–167

n.e. −85

83–85.4 n.e.

2

°C 800–950 mg/m3 flue 43–142 gas % bis 85.6 % 67.4–72 (only one plant)

The purchase price of the firing unit was between 27 and 74% of the total investment costs. Extensive installations (up to 57% of total costs) or construction measures (up to 37% of total costs) are often necessary. The price for the firing unit and fuel bunkers with feeders lie between 585 and 235DM/kW and are independent of the various firing systems. The price is mainly determined by the heat performance of the plant and the size of the bunker. The costs for the heat generated lie between 9.7 and 11.7 Pfennig per kWh and are influenced largely by the cost of the plant, woodchip consumption and the cost of woodchip production. In comparison to a heating oil system, the woodchip combustion systems are economical when the oil price is more than 0.68 to 0.82DM per liter (Tab. II).

Energy from biomass

900

Table II: Investment costs and the economics of woodchip burners for selected examples Title Columm 1

Unit 2

Pre-furnace systems 3

4

5

Stoker systems 6

7

8

Coarse woodchip systems 9

Heat capacity kW 30 50 93 116 50 60 46 Volume of m3 0,8 1,5 35 18 2.2 1.5 1,5 bunker Total DM 23.700 46.700 105.500 73.100 33.200 52.600 36.000 Investment costs made up of: DM(%) 17.600(74) 16.800(36) 43.700(42) 43.600(60) 22.700(68) 14.100(27) 15.000(42) Firing systems Installation DM(%) 2.100(9) 18.000(38) 40.400(38) 11.000(15) 3.500(11) 30.600(58) 7.500(21) Constructions DM(%) 4.000(17) 11.900(26) 21.400(20) 18.500(25) 7.000(21) 8.200(15) 13.500(37) measures Specific costs DM/kW 586 336 470 375 454 235 326 per kW (Firing system) Specific costs DM/kW 796 934 1 134 630 664 876 738 per kW (total Investment) Costs per Pf/kW 11,7 11.4 9.7 11,4 11,4 10,9 10.6 kWh of used heat* Economically DM/1 0.82 0.80 0.68 0,80 0,80 0,72 0,74 favorable for heating oil price* * partically preliminary data

3. MAIN RESULTS FROM THE STRAW FIRING PLANTS The 11 plants for firing straw with capacities between 70 and 1 000kW include 2 handfed bottom-burning boilers for high pressure bales (Fig.3) 1 bottom-burning boiler for big bales (see Fig. 4) as well as 8 mechanically fed plants with de-balers for high-pressure and big bales.

Test results from pilot plants for firing wood and straw in the federal republic of Germany

901

Figure 3: Bottom-burning boiler for straw (system Loibl)

Figure 4: Straw combustion plant for big bales for warmwater production, capacity: 1160kW (system PSW) Through-burning boilers display a relatively low CO2 content; at the same time, high CO emissions arise due to unburnt gasification products and high solids emission, which can be up to at 12% CO2 (see Tab. III).

Energy from biomass

902

Table III Essential results of measurements on straw firing plants (full load operation)— Preliminary results BottomUnderPre-furnace burning boiler- burning with de-baler High pressure boiler-Big for big bales bales bales Columm 1 Test length (h) CO2 content (%) Flue gas temperature (°C ave.) Ember bed temperature After-burning temperature (°C) Solids emission Boiler efficiency Aux. energy (electri-city) as percent of heat generated * combustion efficiency

Airinjection firing system

Throuohburning boiler for hp-bales

2 2 8.5 210

3 2–3 10.8 190–210

4 4 6 ca. 300

5 3.5 11 250

6 1,5–3 5 230

bis 850

1000–1150

ca. 500

n.e.

n.e

830

1080

bis 830

n.e.

n.e

317–708

n.e.

143–310

315–428

380–1640

n.e. n.e.

65 1.3

47 2

59.5 5

56* –

Bottom-burning boilers for high pressure and big bales as well as mechani-cally fed systems show very reasonable values, although the solids release is often above the legally allowed and requires the use of filters. At high temperatures in the ember bed (800°C), slag was observed in the ash. This can cause the grate to become clogged, less combustion air is available to the fuel and the combustion performance is reduced. With the use of movable grates and an automatic ash removal system, these problems can be alleviated. An uniform fuel input is important with automatic feeders to obtain a continuous high-quality combustion. Further, the straw should be collected and stored in a dry condition, since moisture contents above 15% can cause break-downs of the debaling and feeder systems and negatively effect the combustion quality. The required energy for de-baling and the systems operations is between 1.3 and 5% of the generated thermal energy and depends on the efficiency of the plant and the degree to which the straw is chopped. The cost of the plant range between 100 and 430DM/kW, whereas hand-fed units and large capacity systems have a better price-performance ratio. The costs for heat generation can be given as 10.4 to 22 Pfennig per kWh and depend on utilization load of the plant, the efficiency of the boiler and the fuel price. Thus for the implementation on individual farms, straw firing plants become economical at heating oil prices above 0.54–1.15DM per liter (Tab. IV).

Test results from pilot plants for firing wood and straw in the federal republic of Germany

903

Table IV: Investment costs and the economics of straw firing plants for selected examples Through-burning Bottomboiler, burning highpressure boiler, high bales pressure bales

AirBottom- Pre-furnace injection burning with deboiler, big baler for big firing with bales de-baler bales

Column 1 2 3 4 5 6 Heat capacity (kW) 70 50 350 93 145 Buffer storage (1) 7 000 4 500 40 000 – 10 000 Total investment 42 200 44 100 136 000 64 400 100 600 costs (DM) Costs, firing system 7 700 (18) 10 400 (24) 58 800 (43) 40 400 (63) 38 500 (38) (%) Installation costs(%) 19 500 (46) 21 300 (48) 52 200 (39) 16 400 (25) 50 200 (50) Construction 15 000 (36) 12 400 (28) 25 000 (19) 7 600 (12) 11 900 (12) costs(%) Specific costs, firing 110 208 168 434 265 system (DM/kW) Specific costs, total 603 882 328 692 694 investment (DM/kW) Costs of. used heat 11.2 17 22 10,4 11 (DM/kWh)1 Economically 0.65 1.02 1.15 0.75 0.54 favorable for heating of 1 price (DM/1)2 All costs without VAT and without governmental subsidies 1) For the annual heating demand of the farm operation. Comparison costs for oi1 heating: 12 to 16 Pf/kWh 2) For actual operating conditions considering replacement investments. 80 % efficiency assumed for oil heating.

BIOMASS-FUELED FURNACE COUPLED TO GREENHOUSE HEATING AND CROP DRYING SYSTEMS R.M.Sachs, D.Roberts, K.M.Sachs, B.Jenkins, G.Forister, J.Ebeling, D.W.Fujino. Departments of Environmental Horticulture and Agricultural Engineering, University of California and Woodland Power Company, Davis, CA 95616 Summary The furnace, heating a 167m2 glasshouse, operated according to specifications when clean, dry wood particles (pits, shells, pelletized residues, shavings or chips) of 20% moisture or less were used; greenhouse air quality met the health standards required for a work environment and the even more stringent standards for flower crop production, but the aromatic materials were objectionable to al 1 personnel polled. When moisture content exceeded about 20% (wet basis) furnace temperatures fell below that required to direct furnace air into the greenhouse and bridging of fuel also became a serious problem. At these times the furnace air was directed to the bin dryer. Densified fuels flowed without bridging but their current prices, nearly $100.00/tonne, eliminated the economic advantage to using the furnace. The furnace can save ca. $1.00/hr of operation at peak load conditions when replacing a natural gas fueled system with wood fuels at $33/tonne. The furnace tested is available at $7,500–8,000 suggesting a payback in three years assuming interest rates of 10–14%. Costs associated with fuel storage and drying operations, or a heat exchanger if that were required to eliminate aromatics released to the greenhouse, are not included.

Introduction Natural gas, one of the preferred fuels for crop drying and greenhouse heating in California, may cost in excess of $6.00/GJ for commercial enterprises (1). With over 13km2 of greenhouse space, and an average annual consumption of approximately 1.6×103MJ/m2 vegetable, flower and foliage plant growers are among the largest agricultural consumers of natural gas in California (2); they are very dependent upon uninterrupted supply for commercial survival. In addition, crop drying operations consume almost 4.6×109MJ annually. Wood chips and related biomass fuels are available at approximately $33.00 per dry tonne, or about $1.80/GJ assuming 19MJ/kg of wood. The development of alternate fuels and heating systems for greenhouses and crop drying

Biomass-fueled furnace coupled to greenhouse heating and crop drying systems

905

represents protection against interrupted supplies of fossil fuels and has now become an economically attractive prospect. Results of studies on a prototype wood-fueled furnace retrofitted to a greenhouse and bin-type dryer on the UCDavis campus are reported in this paper. Furnace Specifications and Controls. Actual fuel consumption was 6.8kg/hr of wood (design capability is 11.3kg/hr), providing 130×l06 J/hr to the greenhouse or crop dryer. Greenhouse heating requirements for an entire heating season were not determined in this study but we believe this output is adequate to heat the 167m2 single-paned, glass greenhouse used, maintaining a 15°C differential between ambient and greenhouse environment (3). A 77kg fuel hopper was located above the furnace auger feed system with a motor-driven agitator to reduce. Fuel bridging is a problem for this and other wood-fueled systems when relatively moist, irregularly sized particle fuels are used (4). Since the furnace is not equipped with an automatic slag removal system, high ash fuels lead to rapid accumulation of slag in the refractory with consequent decline in furnace operating temperature and diversion of air away from the greenhouse. Dirt-free, low ash fuels are essential for this type of combustor. The furnace is ignited by an electric glow plug inserted through the refractory and into the fuel bed. An air blower is turned on 2 minutes before the auger feed motor. Electrical consumption for operation of auger and agitator motors, ignitor, air blowers and electrostatic air precipitator is about 500watts. Furnace air is directed through a gated box directing air either to the greenhouse or bin dryer. Air can not pass into the greenhouse until the furnace is at or above 900°C and the greenhouse thermostat calls for heat. Prior to entering the greenhouse, stack gas from the furnace is mixed with air recirculated from the greenhouse. The mixture passes through a fiber filter and electrostatic precipitator (Model 0902, Emerson Electric Co., St.Louis, MO) and then into a sealed plastic duct held 2.4m above the greenhouse floor, vented bilaterally at 0.3m intervals. The thermostat controlling the furnace is placed 1.2m off the floor near the center of the greenhouse . Analysis of Furnace Combustion Gases and Determination of Excess Air. Combustion gases were analyzed to determine furnace performance and concentrations of major and minor constituents. Results are listed in Table 1. The results of the gas analyses indicate that the furnace was operating with approximately 200% excess air. Excess air was determined by balancing the combustion reaction for an empirical mole of wood using the elemental composition of pine and fir (7). At 200% excess air theoretical combustion gas concentrations major constituents (Fig 1) agree closely with the measured concentrations. The predicted flame temperature at 200% excess air is close to the average flame temperature of 1370K measured by thermocouples inserted in the furnace combustion chamber. Air Dilution in the Greenhouse. Before entering the greenhouse the combustion gases are mixed with air. The amount of dilution was determined from the measured CO2 content of the combustion gas (6.51%) and air mixture (0.52%). Assuming a background level of 300ppm CO2, the dilution ratio is 12.2 volumes of air per volume of combustion gas. During recyccling of air from the greenhouse, additional fresh air is as a result of uncontrolled leaks surrounding the main blowers, leading to a further dilution of combustion gases. Concentrations of CO2 in the greenhouse after 5 hours of furnace

Energy from biomass

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operation have been measured at 0.35% which suggests that the air added on recycling is somewhat in excess of 30% of the total circulated. Toxic Gas Analyses. The expected levels of the trace constituents, CO, NOx, and CH4, in the combustion gas were determined by direct GC analysis and by an equilibrium analysis for combustion of wood using the IBM-PC disk version of the STANJAN equilibrium composition model developed by Reynolds (8). This model was run for combustion at the stoichiometric air-fuel ratio (no excess air) and at 200% excess air. Results of both analyses for product water not condensed (Table 2) indicate that at high levels of excess air the reaction is virtually complete. Low levels of CO are expected at 200% excess air, particularly after dilution of the combustion gases. NOx emissions may be fairly high in the combustion gas (240ppm) and after dilution be about 20ppm in the

Table I. Gas concentrations in the furnace combustion gases Concentration Constituent % by Volume ppm CO2 6.77 14.11 O2 H2O* 2.01 77.10 N2 CO or NOx 448 *after cooling to saturation

Table II. Equilibrium gas concentrations for combustion of pine (computed from STANJAN model (8)) Constituent CO2 O2 H2O N2 CO NOx CH4 H2 Adiabatic Reaction Temperature

% by Volume Stoichiometric 200% Excess Air 15.5 0.94 12.33 67.94 2.14 0.34 -0.34 2,324K

6.51 13.35 4.74 75.37 -0.024 (240ppm) --1,249K

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Fig. 1. Combustion Gas Concentrations

air mixture entering the greenhouse. Virtually all NOx should be NO, which by itself is not highly toxic to plants. When NO is reacted with ozone in the presence of ultraviolet radiation, peroxyacetyl nitrate, a highly phytotoxic compound, is formed (9). NO2 at 6ppm would damage some greenhouse plants, but NO does not constitute a hazard owing to low ozone, UV radiation and hydrocarbons in the greenhouse environment. At 200% excess air hydrocarbon levels in the combustion gases should be low and were not detected. Sulfur oxides were not detectable. Ethylene analyses in the less than 100ppb range were performed on a gas chromatograph equipped with a photoionization detector and alumina column. Greenhouse air samples were taken in a 250ml vacuum tube with septum-ports for syringe sampling. Spot analyses for ethylene in the approximately 40ppb, with fluctuations up to 800 and down to 17ppb. greenhouse, during 4hr furnace heating runs, detected an average of Carnation flowers placed in the greenhouse showed no “sleepiness” (petal reflexing) symptoms. Owing to the extreme sensitivity of carnation flowers to ethylene (5) it is probable that ethylene levels remain below 40ppb for the major portion of the greenhouse heating periods. Tomato seedlings showed no epinasty, the primary response to ethylene (5), during 5 consecutive trials of one week each. Aroma. Although toxic gases were below the levels permissible for human safety, greenhouse personnel objected to the aroma in the greenhouse during combustion. Levels of aromatic gases were below the limits of detection of the gas chromatographic equipment used but most personnel on the project readily detected their presence.

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Particulates were 0.031mg/m3 for carbon in a total of 0.270mg/m3 fine matter, and 1.087mg/3 for coarse matter, this is above the levels for radiant heated greenhouses but below the 2 to 10mg/m3 levels permitted for industrial safety (6). Particulates in the greenhouse due only to fly ash passing through the cyclone/fi1ter bag/electrostatic precipitator system can be reduced without increasing air flow resistance by adding to the electrostatic precipitator plate area. The precipitator tested reduced particulates passing through the fiber filter by 90%. Fuel Combustion Efficiency. Indirect calculations from char collected in the ash bin as well as direct weighing of fuel inputs and ash residues agree quite closely . The higher heating value of the char measured 30.3 MJ/kg, indicating a large fraction of unreacted fixed carbon. The ash content of the wood fuel was 0.11% and that of the char was 9.1%. If we assume that the char collected in the ash bin at the base of the cyclone provides an adequate sample of the total products of combustion, then the enrichment of ash in this residue is a good measure of combustion. Since the char contained 9.1% ash, we can assume that 0.11/.091×100, roughly 99%, of the fuel was combusted. Five mass balance determinations on 77kg fuel loads confirmed that 99+% of the fuel was combusted. A direct heating system such as the one used can exploit the higher heating value of the fuel supplied since the heat required for vaporization of the water formed during combustion can be recovered by condensation of this water on the cool surfaces of the greenhouse. Plant Growth Studies. Tomato seedling growth in the furnace-heated greenhouse was equal to or greater than that in companion greenhouses using standard radiant heating. We expected some increased dry weight gains for plants in the furnace-heated greenhouse due to the augmented carbon dioxide levels during the first daylight hour; however, the increases measured were not statistically significant. A hot water heat exchanger will be fitted to a similar furnace and a hot water storage system utilized for greenhouse heating; cool furnace exhaust gases can be injected into the greenhouse in the daylight hours and hot water can be circulated when greenhouse heating is required (rarely in the daytime in California except on overcast days). If the objectionable aroma of the stack gases is eliminated in the cooling process, this latter system may provide sufficient increased daytime CO2 to increase productivity of most crops (depending on the ventilation requirements for the greenhouse). References (1) Price quotations from Pacific Gas and Electric Co., San Francisco, Calif. for January 1985. (2) CERVINKA, V., W.J.CHANCELLOR, R.J.COFFELT, R.G.CURLEY, and J.B. DOBIE (1974). Energy requirements for agriculture in California. Published by California Dept. of Food and Agriculture. Sacramento, CA (3) JENKINS, B.M. (1985). Greenhouse model for evaluating alternative heating systems. Proceedings of the 57th Annual Rural Energy Conference, University of California, Davis, Calif. 95616. (4) WILLIAMS, R.O., J.R.GOSS, J.J.MELSCHAU, B.M.JENKINS, and J. RAMMING (1978). Development of pilot plant gasification systems for the conversion of crop residues to thermal and electrical energy. pp. 142–162. In:ACS Symposium Series, No. 76 “Solid Wastes and Residues” American Chemical Society, Washington, D.C.

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(5) MASTALERZ, J.W. (1977). The greenhouse environment. John Wiley and Sons, New York, NY. (6) CAL-OSHA (Aug. 1983). Airborne contaminants. General Industry Safety Order 5155. Publication S-100. CAL-OSHA Communications, 525 Golden Gate Ave., San Francisco, CA 94102. (7) JENKINS, B.M. and J.M.EBELING (1985). Correlation of physical and thermochemical properties of terrestial biomass with conversion. In: Proceedings of “Energy from Biomass and Wastes, IX.” Inst. Gas Tech., Chicago, IL 60616. (8) REYNOLDS, W.R. (1984). STANJAN Program. Dept. Mechanical Engineering. Stanford University, Stanford, CA. (9) Air Pollution Injury to Vegetation (1970). Publication AP-71. Superintendent of Documents. U.S. Govt. Printing Office, Wash. DC 20402. (10) California Air Resources Board. Evaluation Report. No. C-83–086. Evaluation Test of a Wood Chip Fired Furnace Used for Greenhouse Heating, Filed 18 July 1984. Air Resources Board. 1102 Q St. PO Box 2815, Sacramento, CA 95812.

Acknowledgments Partial funding provided by Universitywide Energy Research Group (UERG), University of California, Berkeley, California, U.S.A.

QUALITY OF DENSIFIED BIOMASS PRODUCTS J.CARRE, J.HEBERT, L.LACROSSE Centre de Recherche Agronomique de Gembloux (Belgique) (1) Pierre LEQUEUX Directorate-General for Development Commission of the European Communities (2) Summary Six different kinds of biomass have been densified by six industrial processes, including three basic systems (piston, pellets and conical screw presses). Specific qualification tests were carried on the densified products: density, friability, moisture content under different atmospheric conditions, dimensional stability in water and in wet air. In addition, tests were applied to assess the behaviour of the products to be used in Lowpower gas producers (<100kW). The results mainly show that the properties of the densified products depend on the system of densification, the specific process, and the raw material. The variations in quality are very large and cannot be determined by only one property. The main properties are the mineral content, the cohesion during gasification and moisture resistance. Many results are need to determine with precision the Limits to the use of the densified products.

1. FOREWORD In 1983 the Community sponsored an R & D programme entailing a critical analysis of dry processes for using ligneous matter as a source of energy in South-East Asia. The results pinpointed technologies and processes for converting ligneous matter into alternative solid fuels (e.g. briquettes, pellets and plant charcoal) and potential applications for fuels of this type as a source of energy in the home, in craftmen’s workshops and in industry (e.g. improved burners, gasifiers and carbonizations furnaces). The programme faced complex problems due to the: (i) wide variety of: (a) resources (wood, by-products of agriculture and of the associated industries, animal dung, energy crops, etc.); (b) technologies (ranging from traditional direct uses to sophisticated processes for manufacturing synthetic motor fuels); (c) application (from rural areas to modem sectors);

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(ii) competition with respect to Land and resources (i.e. whether they should be used for energy or non-energy purposes) and related products (e.g. gas from coal or digester gas); (iii) the Lack of an adequate technical and, above all, economic basis for selecting technologies and applications for appropriate programmes. The aid for cooperation on biomass projects mirrors this dichotomy. In the face of the growing demand from the developing countries, the support remains extremely limited for want of any clear definition of the market concerned or of the type of measure to be given priority. This programme not only fits in with the Community’s general approach to development cooperation but also marks the first step in this field in tune with the recommendations made at the 1981 Nairobi Conference. To a large extent the findings can be applied to other regions of the Third World too. What is more, this research could also help Europe’s biomass industry to adapt to those countries’ needs. Part of the programme was carried out by the Centre de Recherche Agronomique (CRA) at Gembloux. This enabled us to propose various test methods and quality standards for the fuels and equipment, and in particuLar for densified products. This report sums up some of the tests conducted. 2. ANALYSIS OF THE RESULTS It is impossible to give all the many results made here (3). Only the most important aspects are mentioned below. 2.1. Physical and mechanical tests 2.1.1. Friability test The friability test was conducted in a trommel 593mm in diameter and revolving at 21 revolutions per minute. The test Lasted 30 minutes, with measurements taken in the interim to monitor the kinetics of the crumbling process as a function of the number of revolutions made (see Fig. 1) 2.1.2. Density Since the weight and volume of the ligno-cellulosic matter both vary with relative humidity, both the density and moisture levels of the briquettes had to be measured after stabilization and in different atmospheres at controlled temperature and moisture levels.

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TABLE I Density and equilibrium moisture of the beech briquettes as a function of the airconditioning and of the type of press Conditioning, over 21 days, at 20°C and Type of Press 35% 65% 95% Firm (1) relative humidity reltive humidity relative humidity D (2) E (3) D E D E A P 1169 7.2 1241 7.8 1096 13.9 B RP 734 6.4 698 10.5 crumbled 22.4 C RP 1010 8.3 1086 12.0 689 17.8 D RP 1015 6.8 924 10.1 crumbled 21.5 E CS 1187 5.3 1226 8.8 847 18.3 F CS 1238 5.7 1 139 7.8 831 20.6 (1) P=pelletizing press; RP=ram pelleting press; CS=conical screw press (2) D=density (3) E=equilibrium moisture (% dry matter by mass)

Table I gives a representative picture of the trends observed in the materials treated and brings out the following points in particular: (i) the density of the product obtained from any one raw material varies considerably depending on the process used; (ii) the moisture equilibrium rates for any given raw material also depend closely on the densification processes used; (iii) the density of the densified products falls as the moisture content rises, bringing with it considerable variations in size. Comparison of the findings for beech with those for the other raw materials shows that the nature of the raw material also has an appreciable impact on the density of the products obtained from each of the processes. Consequently, density is extremely variable and depends on: (i) the raw material (nautre, initial density and grain size); (ii) the process used (e.g. ram pelleting press, conical screw press, etc.); (iii) the temperature and relative humidity of the ambient air; (iv) the physical properties of the densified products. It therefore follows that density cannot be taken as the only criterion for judging quality. 3. PHYSICAL PROPERTIES The dimensional stability of the densified products also varies considerably, depending on the type of press, on the maker, on the equipment and on the raw material. By way of example, Figure 2 traces the stretching of different beech briquettes in a humid atmosphere (20°C and 95% relative humidity).

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4. USABILITY TEST A series of combustion tests in open and closed hearths showed that the different types of briquettes behaved very differently from each other. Some held together throughout the combustion process and could therefore be regarded as suitable substitutes for wood charcoal. The degree to which the densified products crumble during combustion depends closely on the physical properties of the briquettes. Further tests demonstrated much the same phenomena during gasification too. Some of the products were excellent fuels whereas others crumbled and brought the generator to a standstill. 5. CONCLUSIONS The densified products vary considerably depending, in particular, on: (i) the type of press (ram pelleting press, conical screw press, etc.) and on the type of process; (ii) the raw material; (iii) the temperature and relative humidity of the air to which the briquettes are exposed between manufacture and burning (i.e. during storage). It is therefore clear that no single criterion can be applied to define the quality of the densified product but that a set of different properties must be used instead. If they are to satisfy the users, the fuels must be properly suited to the intended use (i.e. for heating in the home, as a substitute for wood charcoal or as a feedstock for gasifiers, etc.). If densification is to spread successfully throughout the developing countries, it is therefore imperative to carry out a technical analysis of each specific case first. In this way it should be possible to avoid the mistakes made all too often in practice.

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Figure 1: Friability of the six different types of briquette, as a function of the type of press, of the air-conditioning and of the raw material. The friability curve shows the percentage of uncrumbled matter as a function of the number of revolutions made by the trommel (N).

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Figure 2: Stretching of densified industrial products in humid air (20°C and 95% relative humidity), as a function of exposure time, of the densification process and of the raw material. The stretching is expressed as a percentage of the initial Length, as measured after conditioning at 20°C and 65% relative humidity. REFERENCES (1) Centre de Recherche Agronomique (CRA) 23, avenue Maréchal Juin—5800 GEMBLOUX (Belgium) (2) Commission of the European Communities—DG VIII 200, rue de La Loi—1049 BRUSSELS (Belgium) (3) The full study can be obtained on request from Mr P.LEQUEUX

ON THE TESTING OF WOODBURNING COOKSTOVES P.Bussmann*, K.Krishna Prasad* and F.Sulilatu** * Department of Applied Physics, Eindhoven University of Technology, Eindhoven, The Netherlands ** Division of Technology for Society, TNO, Apeldoorn, The Netherlands SUMMARY This paper is a contribution to the ongoing debate on the testing of stoves. A practical test procedure needs to be simple, reliable and useful. It is shown that these three requirements place conflicting demands on the test procedure. Thus a hierarchy of testing is necessary. The Arlington procedure prescribes such a hierarchy. A critique of this procedure is given whereafter an ideal procedure is postulated. The outcome of the exercise is that compromises among competing demands are essential for designing an effective test procedure.

1. INTRODUCTION Testing a device is invariably carried out to assess its performance in relation to the task it is expected to carry out. Additional restrictions are placed on the equipment since it has to be operated by a human being. These restrictions come in the form of safety to the operator. It is customary to demand stringent safety requirements from household appliances since these are operated by a large and diverse population. The equipment therefore must be regularly tested by independent institutes. The present paper considers woodburning cookstoves for domestic applications. Woodburning cookstoves are usually made by many manufacturers and in a competitive environment. Until recently these devices were never tested. With the growing interest in improved stoves the call for a test methodology becomes louder. The main reason being public funds are spent on stoves in order to alleviate the distress caused by the fuelwood scarcity. Attention primarily was given to the reduction of the wood use. This is also reflected in the test methodologies designed so far. 2. THE ARLINGTON TEST PROCEDURE A typical example of the methodologies mentioned is the Arlington test procedure (1). The procedure has three levels of testing. The first level is a water boiling test, a simple simulation of a standard cooking procedure. The results are expressed in the standard specific consumption, SSC, which is the ratio between the water vaporized and the wood

On the testing of woodburning cookstoves

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used. The second level is the controlled cooking test which involves the cooking of a selected meal. The results are expressed in the specific consumption, SC, defined as the ratio between the wood used and the food cooked. The third level is the kitchen performance test which measures the relative rate of fuel consumed by two stoves as they are used in the normal household environment. The results are expressed in the specific daily consumption, SDC, which is the ratio between the wood use per day and the family size. The problems with the test procedure are: 1. The definitions of the SSC, the SC and the SDC do not relate with each other. Without additional information it is impossible to use the results from one test level at other levels. 2. The procedure specifies only how to perform a test but does not specify how to evaluate the results. No standards are given against which the performance of the stoves can be assessed. 3. Safety aspects are completely ignored. 4. The procedure is not sufficiently clear to enable an experimenter to

Figure 1. measured boiling times.

Standard

deviation

in

obtain reproducible results. This can be illustrated in figure 1 in which the standard deviation in the boiling times is plotted. The IVE data (2) covers 130 boiling tests, 10 tests with each stove. Wouters (3) tested 4 stoves and Strasfogel (4) 2, covering in total 20 and 28 experiments respectively. 3. THE IDEAL TEST PROCEDURE The ideal test methodology for woodburning cookstoves presented in this paper is based on the test methodology for gas ranges (5). This means first of all that water boiling tests

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have to be performed, in order to measure the efficiency (n) of the stove at power level (P). Secondly it means that the maximum power (Pmax) of the stove must be determined. Thirdly the turn down ratio (r=Pmax/Pmin) must be measured and fourtly it must be examined whether the stove meets the safety requirements. The size of the pan used in the tests is chosen according to the power rating. The thumb rule for gas ranges is to have a power density at the pan bottom equal to 7W/cm2 (figure 2). This value seems too low for woodstoves because of their lower efficiency. That is why the x-axis in the figure has three different scales, representing power densities of 7W, 10W and 17.5W per cm2 bottom area at efficiency standards of 50%, 35% and 20% respectively. The data gathered with the ideal test procedure make it possible to calculate the time to cook and the specific consumption (SC) for any given meal (6). For this the cooking task must be modelled which is done through the water equivalent of the food to be cooked, MW and the simmer time, ts, (7). It is assumed that steam production is an inevitable, albeit useless,

Fig. 2. Pan diameter and content versus power output (5). part of the simmering process. Thus one must start with a quantity of water larger than the final quantity, MW: In addition there is sufficient evidence available to suggest that the efficiency of a stove is not a strong function of the power and the mass of food cooked. Moreover dT=75K and Cp=4.2kJ/kgK. The formulas for the SC and the boiling time then become:

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The equations show that a reduction in SC can be achieved by: increasing the heating value B; increasing the efficiency n; decreasing the power rating of the stove P; increasing the mass of food cooked MW; reducing the simmering time ts and increasing the turn down factor, r. The methodology for testing gas ranges gives clear standards for the CO content in the flue gases. In testing woodburning cookstoves this problem has nearly completely been neglected although Smith (1983) clearly showed the seriousness of the problem. As an indicator of the toxicity of the combustion gases, the CO-CO2 ratio is used. In the table the norms applied in the Netherlands for different burners are given. Essential is that the power is specified too. Stove type Power CO-CO2 ratio gas appliances Pmax kerosene burners Pmax anthracite burners Pmax domestic space Pmax heaters using wood* Pmax/2 * Proposed standards

<1.0% <1.2% <2.0% <4.5% <9.0%

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Figure 3. CO2 concentration versus time. 3a: charge weight varied; 3b: charge time varied. No data whatsoever has been reported on other safety aspects like the stability, wall temperature and combustion gas leakage. The authors believe that these aspects will become much more important in the near future. 4. WATER BOILING TESTS Water boiling tests are performed to measure the efficiency at different power levels. In case the pan choice and cooking task is not restricted by the stove design, they are chosen according to figure 2. Therefore Pmax needs to be determined first. Each test lasts for about 1 hour. Evaporation is not considered to be a loss, which has led to some

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confusion. Bringing to boil successive pans might overcome this problem (8). During the boiling test the CO-CO2 ratio is measured. The results are averaged over the whole experiment. 5. THE POWER OUTPUT In using the stipulated theory it is necessary to have a steadily burning fire. One way of obtaining such a fire is by adding small quantities of wood at short time intervals. Needless to say this is a cumbersome procedure. However, the stove can be considered to burn in a steady periodic way when wood is added in bigger charges at larger time intervals. The power in that case is defined as: P=(dMf* B)/dt. where dMf is the charge weight, B the combustion value of wood and dt the the charge interval time. A big advantage of adding the fuel in charges is that it leads to experimental results which are highly reproducible. This is shown in figure 1. The standard deviation in the boiling times measured by THE/TNO is small. However, adding the wood in charges creates some unexpected problems. Changing dMf or dt in order to vary P has completely different effects on the fire behaviour. This is illustrated in figure 3 where the CO2 content in the flue gases is given as a function of time. In figure 3a the charge weight is varied and the peak values of the CO2 concentration curve change accordingly. In figure 3b on the other hand the charge time is varied but the peak values in the CO2 concentration do not change. A problem of a different nature arises due to the build-up of charcoal on the fuelbed. The weight of the fuelbed is mportant as it determines the time the water keeps on boiling after the last charge has been added. Since the end of the experiment is defined to be the moment of time the water stops boiling, it raises the question whether it is not better to use a power definition based on this time. The discussion so far showed the problems in defining the power output. On top of this, criteria have to be found which make it possible to rate the power of a stove. The criterion used so far is the excessive build-up of the fuelbed. Only recently the criterion of the excessively high CO-CO2 ratio came into the picture. Many more experiments to collect data in this field are needed. Criteria also have to be evolved which determine the minimum power or the turndown factor. The question to be answered is whether the minimum power is controlled by the stove or by the task to perform. This task is to balance the convection, radiation and evaporation heat losses from the pan when simmering. Assuming that the pan is not enveloped in hot flue gases, the convection heat losses from the pan wall and lid can be calculated using the Nusselt number relations for free and forced convection (9). Radiation losses from the pan depend on the emissivity factor of the pan surface. The losses vary from nearly 0 W/m2 (brigth shining aluminium surface) to 680W/m2 (black sooted pan). The evaporation heat loss at boiling point from a cylindrical, 28 cm diameter pan without lid in a laboratory environment is approximately 900W which is 6 times the expected convection and radiation losses. The importance of using lids is clear. When evaporation is prevented, only about 10% of the maximum power needs to be supplied A

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turn-down factor of 10 is required which is 3 times the value the existing designs show! Thus the minimum power seems to be controlled by the stove.

Figure 4. CO-CO2 ratio versus power; data from stoves with different combustion chambers. However, recently designed stoves are able to separate the volatiles and charcoal combustion. The charcoal is then used during the simmering period leading to much lower power levels than can be reached with wood. So far it is not clear how this can be taken into account in determining Pmin. 6. THE CO-CO2 RATIO In figure 4 the CO-CO2 ratio is shown as a function of the power for three similar stoves with a chimney but with combustion chambers of different size. In the figure also the standards from the table are given. The stoves are good from an efficiency point of view in comparison with many other designs. But the index of toxity is too high for the whole power range which shows the necessity for including the CO-CO2 measurements in the test methodology. 7. CONCLUSIONS The problems in using the Arlington test procedure lie in the fact that results obtained at different test levels do not relate with each other; that no standards are given; that safety aspects are ignored and that the procedure gives an impression to be very accurate while

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in fact the reproducibility of results is poor. The ideal test method suggests that the fuel consumption can be calculated once the power-efficiency curve is measured. However, laboratory results from the THE/TNO showed that the understanding of processes in woodburning cookstoves is still at such a level that clear definitions cannot be given of the power output, the maximum/minimum power in particular. Testing at different levels is therefore needed which includes controlled cooking tests. Moreover, at the time being only approximate standards can be given. REFERENCES (1) VITA, (1982), Testing the efficiency of woodburning cookstoves, VITA, Arlington. (2) I.V.E., (1983), Etat de développement technique des foyers améliorés en Haute-Volta, I.V.E., Ouagadougou. (3) Wouters, F., (1984), Personal communications. (4) Strasfogel, S., (1984), Programme regional foyers améliorés, C.I.L.S.S. Ouagadougou. (5) V.E.G., (1968), Standards for domestic gas appliances, V.E.G.-Gasinstituut, Apeldoorn. (6) K. Krishna Prasad et al., (1983), Test results on kerosene and other stoves, prepared for the Energy Assessment Division, Energy Department, World Bank, Washington D.C. (7) Verhaart, P., (1983), On designing woodstoves, in Wood Heat for cooking, Indian Academy of Sciences, Bangalore. (8) Micuta, W., (1982), Paper prepared for the Arlington meeting on testing procedures, VITA, Arlington. (9) Kreith, F. and Black, W., (1980), Basic heat transfer, Harper and Row, New York.

AIR POLLUTION FROM BIOMASS HEATED BOILERS COMPARED WITH THAT FROM WASTE INCINERATION AND OIL COMBUSTION C.BENESTAD, M.MØLLER, A.OSVIK, T.RAMDAHL, G.TVETEN Center for Industrial Research, P.O. Box 350 Blindern, 0314 OSLO 3, NORWAY Summary The amount of polycyclic aromatic hydrocarbons (PAH) and mutagenicity were measured in emission samples from combustion of wood, wood- and bark pellets, municipal waste and oil. A great variation in the PAHcontent and the mutagenicity was found. According to this study wood heated boilers are less favourable and need further improvement. Preliminary results indicate considerable PAH emission from small, older oil heaters as well.

1. INTROOUCTION Incineration of biomass is becoming a potential substitute for oil heating in many residences. The increased use of biomass as solid fuels especially peat, wood and straw as well as domestic waste has led to a growing concern about the environmental impact from combustion emissions. Oil combustion has been a common source of heat not only because of economically reasons but also because it is simple and clean in use. To be able to compete with oil combustion the biomass incinerators must not only be cheap and handy to use but also the emitted air pollutants must be in the same order of magnitude as those from oil combustion. In this study polycyclic aromatic hydrocarbons (PAH), some of which are known carcinogens, and mutagenicity is measured in emission samples from combustion of various types of biomass: wood, pellets of bark-and-wood chips (50% bark—50% wood) and municipal waste. The results are compared with corresponding emission values from oil combustion. 2. MATERIALS AND METHODS Samples: Samples were collected from the stack gas of four wood heated boilers (Max. effect 20–75kW) under different combustion conditions and from the stack gas of two

Air pollution from biomass heated boilers compared with that from waste incineration and oil combustion

boilers (Max. effect 20kW and 100kW) constructed for combustion of wood pellets. Stack gas samples were also collected from three smaller (capacity 0.5–1t/h), discontinuous municipal waste incinerators, all of them with heat recovery, and from oil heated boilers one of which is a small residential heater (Max. effect ~20kW) and the other a large 5-MW-plant. All these incinerators are located in Norway. Sampling: The stack gas samples were removed with a quartz glass probe. The particles were collected on a Gelman glass fiber filter, held at approx. 120°C to avoid condensation of gaseous species. The stack gas was cooled and the condensate collected in several impingers cooled gradually from 0°C to −60°C. Finally the dried gas was passed through a column containing an adsorbent (Amberlite XAD-2). Chemical analysis: The filter and the adsorbent were extracted with methylene chloride in a Soxhlet apparatus for 16–24 hours. The condensate was liquid-liquid extracted with methylene chloride. The extracts were purified and the PAH were quantified by gas chromatography (GC/FID) according to the method described by Bjørseth (1). Mutagenicity test: The extracts of the filter, the adsorbent and the condensate were tested in Ames Salmonella microsome assay (2) using the bacterial strain TA98 in the absence as well as in the presence of the liverenzyme S9. 3. RESULTS The results of this investigation is shown in Table I.

Table I PAH and mutagenicity in emission samples form combustion of wood, wood- and bark pellets, municipal waste and oil Wood Wood pellets Waste Oil (20–75kW) (20–100kW) (900–2400kW) (20–5200kW) PAH (µg/m3) PAH (mg/kg fuel) Mutagenicity (rev/kg fuel, TA98 +S9) Mutagenicity (rev/kg fuel, TA98 −S9) Particles (mg/m3 CO (ppm)

900–185000 10–1500 0.6–6·106

20–90 0.7–2 0.8–1·106

10–1960 0.2–1 .5 0.02·106

<0.01–50 <0.002–11 0.004–2·106

0.3–35·106

1–2·106

0.01–0.2·106

0.003–3·106

60–310 200–15000

15–70 70–>1000

70–800 100–1400

2–150 10–220

The results show a great variation in the amount of PAH and mutagenicity emitted from combustion of various types of biomass and oil combustion. Regarding these two emission parameters wood combustion is the less favourable of them all. The PAH content and the mutagenicity in stack gas from wood heated boilers very much depend on the combustion conditions such as the time spent of the stack gas in the combustion zone, secondary air supply and humidity of the fuel. However, the PAH

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amount emitted from wood heated boilers is high and further improvement of these types of incinerators is needed. The PAH content in stack gas from combustion of wood- and bark pellets is considerable lower than that from wood combustion. However, the mutagenicity is somewhat higher than the mutagenicity in the stack gas from a efficient wood combustion. The analyses of the stack gas samples from the waste incinerators indicate that PAH emission is not the main problem even if considerable amounts (approx. 1000µg/m3) can be emitted during the starting period of the incineration. However, the emission of heavy metals, hydrochloric acid and chlorinated organic compounds may give cause to more concern. Small amounts of PAH and a low content of mutagenicity is found in emission samples from oil combustion in big plants of MW-size. However, preliminary results of analysis of stack gas from a small (~20kW), older residential oil heater indicate PAH emission in the same order as that of a efficient wood heated boiler. Also the mutagenicity of the stack gas was considerable. 4. CONCLUSIONS Based on this study we conclude: – that improvement of boilers for wood combustion is needed – that PAH emission is not the main problem with municipal waste incineration – that boilers heated by combustion of wood pellets can compete with that of oil combustion as far as the emitted PAH and mutagenicity is regarded

5. REFERENCES 1. Bjørseth, A: Anal. Chim. Acta 94. 21 (1977). 2. Ames, B.N., McCann, J., Yamasaki, E.: Mut Res. 11. 347 (1975)

KINETICS OF WOOD TAR PYROLYSIS P.MAGNE, A.DONNOT and X.DEGLISE Université de Nancy I, BP 239, 54506 VANDOEUVRE Les Nancy Cedex—FRANCE Summary The production of tar in all types of biomass gasifier being hindering for a good working, it is advisable to remove it, and the best way is to use flash pyrolysis. Using a two reactor apparatus, we tried to determine some kinetics data on the flash pyrolysis of tar from pine bark pyrolysis. Assuming that tar pyrolysis is a first order reaction, a curve was constructed of the time necessary for complete pyrolysis of tar versus temperature for the homogeneous reaction and for the reaction catalysed with sand and with dolomite. The activation energies of these reactions, the catalytical efficiencies of sand and dolomite and the heating values of the gases produced were determined. The use of dolomite as catalyst of tar pyrolysis can increase the heating value of the gases to a significant extent.

1. INTRODUCTION We have collaborated with the TNEE Company (a subsidiary of St Gobain) in the development of a new process for pine bark pyrolysis (circulating fluidized bed) (1), in order to obtain a gas of medium heating value. All the processes involving thermochemical transformations of biomass in order to obtain alternatives to fossil fuels produce gas char and tar. Tar carried along by gas, condenses as soon as the wall temperatures decreases. It is therefore advisable to remove it, and the best way is to use flash pyrolysis. Consequently, we are interested in determining certain kinetic data relating to the pyrolysis of tar from biomass pyrolysis in particular. As the results obtained by previous workers (2,3) are inadequate for the design of a gasifier, we tried to obtain some accurate data with and without catalysts in order to facilitate such a design. These data are the residence time (the time necessary for tar to be completly decomposed or, in kinetics terms, the reaction time of tar pyrolysis) and the activation energy. The changes in gas composition and heating values were also studied. 2. EXPERIMENTAL Apparatus (fig.1) shows the laboratory apparatus used for the experiments. It has already been described in details (4).

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Procedure: Tar vapours were always formed in the same way. Pine bark particles (1– 1.25mm in diameter) dropped at a constant flow-rate (0.35g/min) freely into the pine bark pyrolysis reactor-2-maintained at 650°C. Part of the gas and tar vapours, the whole volume of gas or tar vapours diluted with helium could be directed to the tar pyrolysis reactor. In the reaction cell of this reactor, three types of experiments were carried out under the following conditions: (1) empty reaction cell; (2) reaction cell filled with the sand used in the fluidized bed process developed by the TNEE Company; and (3) reaction cell filled with dolomite. The principles of calculation have been already explained (4). The catalysts used were sand and dolomite (4). 3. RESULTS AND DISCUSSION Fig.2 shows the variation of the residence time necessary for tar to be completely pyrolysed. Curve I corresponds to the empty reactor. Curve II corresponds to the reactor filled with 187g of sand, the total surface area of which is about 139m2. Curve III corresponds to the reactor filled with 128g of dolomite the total surface area of which is about 114m . Before starting the reaction and for each temperature, dolomite was decarbonated by heating it at 900°C in a current of air up to a total disappearance of CO2. The modification of surface area that followed was not taken into account. , The respective activation energies are 21.5, 18.4 and 11 kcal.mole−1 As expected, the higher the catalytic efficiency, the smaller is the activation energy. As the surface areas of sand and dolomite available for the catalytic reaction in the reactor are of the same order of magnitude (134 m2 of sand and 114 m2 of dolomite), it is possible, from the curves in Fig.4 to compare the catalytic efficiencies of sand and dolomite with respect to the empty reactor reaction for different temperatures, and to compare the catalytic efficiency of sand with that of dolomite (table I).

Table I: Comparison of catalytic efficiencies (V=reaction rate with sand as catalyst) Temperature (°C) 600 644 700 800 4.2 3.4 3.2 2.4 126

90

70

41

22

17

11 26

Kinetic of wood tar pyrolysis

929

8.2 3.2

The comparison of gas from the pyrolysis of tar, either the tar pyrolysis reactor empty or filled with sand, is analogous to the gas composition of lignocellulosic materials pyrolysed at the same temperature. The results were completely different when decarbonated dolomite filled the tar pyrolysis reaction cell (Figs. 4 and 3). The first interesting observation is that there is no longer any CO2; however, the composition of the other gases is not what one could expect from only the effect of CO2 absorption on decarbonated dolomite, as the contents of H2 and CH4 are much higher and the contents of C2H4, C2H6 and CO are much smaller than expected. This confirms the favourable effect of decarbonated dolomite on the formation of CH4, as already pointed out by EKSTROM and al (3). When the temperature of decarbonated dolomite increased, the gas composition became slightly closer to that from pine bark pyrolysis, except for CH4, the content of which continued to increase. When dolomite was recarbonated and its temperature was 650°C, there was always a compositional modification, but much smaller: H2 and CO were modified in the same way as with decarbonated dolomite, but all the other constituents remained almost unchanged. The heating values of gases from pine bark pyrolysis and tar pyrolysed either in an empty reactor cell or in a reaction cell filled with sand do not differ from those of gases from pine bark pyrolysis only (Fig.5) A maximum seems to be reached around 500°C. The results obtained with decarbonated dolomite are more interesting (Fig. 6). The heating values are distinctly superior to those obtained for gases crossing the sand or the empty reactor : more than 18.7MJ m−2 instead of 15.6MJ m−3 . They seem to reach a maximum at around 650°C. CONCLUSION Common siliceous sand slightly increases the decomposition rate of tar from pine bark pyrolysis. On the other hand, decarbonated dolomite and even carbonated dolomite have significant catalytic efficiencies (see table 1). However, it seems difficult, if not impossible, to use them as heat carriers in a pyrolysis process such as that at present under development because they are too soft and would be quickly transformed into dust and carried along with the gases or the smoke. It is of interest to note that the mixture of molecules which compose the dolomite is a very effective catalyst, and this may constitute a starting point in the search for an efficient catalyst that will also meet all the other required qualities.

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REFERENCES (1) French Patent Pending (2) CHEMBUKULAM , S.K., DANDGE, A.S., KOVILUR, N.L., SESHAGIRI, R.K., VAIDYESWARAN, R., Ind. Eng. Chem. Proc. Res. Dev., (1981) 714–719.20 (3) EKSTROM, C., LINDMAN, N., PETTERSON, R., The Royal Institute of Technology, Stockholm (Private Communication) (4) DONNOT, A., RENINGOVOLO, J., MAGNE, P., DEGLISE, X., J. Anal. and Appl. Pyrol. (1985) (under print)

Fig. 1. Experimental apparatus

Fig. 2. Residence time for tar to be completely pyrolysed vs. temperature

Kinetic of wood tar pyrolysis

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Fig.3. Variation of gas composition with temparature of the tar pyrolysis reaction cell (filled with decarbonated dolomite) ; ; ; gases from carbonated dolomite

Fig.4. Variation of gas composition with temperature of the tar pyrolysis reaction cell (filled with decarbonated dolomite) C2H6; ; C2H4; gases from carbonated dolomite

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Fig.5. Highest heating value of gases produced vs. temperature of pyrolysis for pine bark : size 0.63–0.8mm size 0.8–1.25mm

Fig.6. Highest heating value (298K) of gases having crossed decarbonated dolomite vs. dolomite temperature

AN INTERMEDIATE CAPITAL INTENSIVE PYROLYSIS SYSTEM APPLICABLE TO DEVELOPING COUNTRIES J.W.Tatom Kofi B.Bota Atlanta University 223 James P.Brawley Drive, S.W. Atlanta, Georgia 30314—USA Summary The main point of this paper is that time is running out for pyrolysis of agricultural and forestry process wastes in LDCs. If the byproduct marketing problems it faces cannot be resolved quickly, then other technologies requiring only a fraction of the process wastes and serving only the local , immediate needs of process plant operators will take over, rendering the vast majority of these residues economically unavailable as fuels. This is bad news for many LDCs who need every available energy source. The Indian experience with coal carbonization teaches many lessons that can be applied to this situation and, in LDCs where coal deposits are available and undeveloped, suggests the Integration of soft coke and charcoal production and marketing. The paper argues that since the private sector lacks the means to establish a viable carbonization industry, government must temporarily intervene on the demand side to encourage utilization of the char and oil products potentially available. In addition, the paper discusses some unresolved questions of carbonization plant production scale and technology. A brief review of recent technical developments in moving-bed, partial-oxidation pyrolysis technology in the Philippines and in Thailand is presented. It is argued that while technical improvements can clearly be made, the basic Intermediate Capital Intensive design is reliable, appropriate and economical in LDCs, and is ready for commercialization. Finally it is observed that the same pyrolysis technology, with minor modifications, is applicable to the carbonization of coal. This reinforces the argument for integrating these two industries where applicable.

1. THE PROMISE OF PYROLYSIS The promise of pyrolysis in Lesser Developed Countries as a technology for converting the vast quantities of agricultural and forestry process wastes available into clean fuels

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has not yet been realized. In spite of the technical developments of the last ten years, there are few, if any, commercial uses of this technology being made in the developing world—even though it can be shown to be economically viable. While successful pilot scale pyrolysis systems have now been built in Ghana, Indonesia, Papua New Guinea, Costa Rica, the Philippines and Thailand at government and university laboratories (1–4)1 under programs sponsored by a variety of private, government and international organizations,2 there has been little private sector involvement. Why is this so? Clearly the 1

Numbers in parentheses refer to citations listed on the References, See (4) for a review of these project experiences and the associated technical and non-technical problems. 2

need for renewable, clean burning, indigenous fuels has not disappeared. The need is only increasing, and the recent tragic events in Africa portend that it will get much worse. In contrast, during the same period other conversion technologies such as direct combustion and gasification have aroused considerably greater commercial Interest at a variety of installations, Including process plants. This is understandable to some degree since there are many valid applications of these technologies in LDCs. But are they best suited to supply the energy needs of processing plants? Typically, processing plants produce a waste stream having an energy content many times the energy demand of the facility. To illustrate: (1) the energy value of wood residues from a sawmill may be ten to fifty times the mill energy needs—even after the inefficiencies of thermal and mechanical conversion are included. (2) A study of one hundred randomly selected rice mills out of the 12000 in the Philippines (5) revealed that 84 percent produced more waste than required to run the plant, with an average producing four times the break even energy. (3) Peanut hulls in piles six feet deep line the roads for miles around Dakar, Senegal, a graphic testimony of the quantity of residue available beyond that needed to fire the ancient, Inefficient boilers that power the peanut oil mills. Therefore, from a national perspective, neither direct combustion nor gasification, with a few exceptions, offers the best means for utilizing process residues, because neither requires but a small fraction of the waste stream to supply the plant energy needs. The great majority is thus unused, leaving a massive waste disposal problem. Thus in this one very important arena, i.e. utilization of process wastes, direct combustion and gasification, in the long term, are simply not the most attractive technologies from a social and an environmental view, regardless of their level of development though they presently may provide a superior alternative to imported fuel consumption. One important reason for the commercial Interest in residue burners and gasifiers is the fact that they are designed to supply the immediate needs of an individual boiler or engine. This has given them a strong marketing advantage, since the boiler operator or gas producer is his own customer, and thus completely controls the economies and logistics of the situation. In contrast, pyrolysis produces a variety of products; i.e. char, oil and gas, all of which is not needed to fuel the plant and tberefore must be sold to second parties—if the unit is to be economically viable. Typically these products,

An intermediate capital intensive pyrolysis system applicable to developing countries

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especially the char and oil, represent commodities for which there is no present market demand, even though that demand is latent. And therein lies the problem. If there were long term solutions to the energy problem of LDCs that could avoid complete, efficient use of the great quantities of process wastes available, the pyrolysis story would probably end here—at least for the near future. However, it becomes clearer every day that for the developing world to survive the imminent, painful transition to wood as the fuel of the future will require taking draconian measures. Therefore, every energy source available must be brought forth to fill this critical period—while we wait for the trees to grow. This undoubtedly will necessitate the full use of process and other wastes, and it additionally will most certainly require the exploitation of any available indigenous fossil fuels; e.g. coal, which is available in underdeveloped deposits in a surprising number of LDCs. The recognition that coal and/or lignite must play a part in this transition is not surprising, nor is it new. In fact India embarked on such an effort at a national scale almost 25 years ago, and today is beginning to see the fruits of its labors. Moreover, the growing urbanization of the developing world, which will result in a 45 percent urban population by the year 2000, makes vital the development of clean burning fuels to avoid further contamination of the environment. Awareness of this need led the Indians to develop coal carbonization technology, which in turn exposed them to the associated problems of marketing soft coke and coal tar. This experience was painful, though educational, and has been recently reviewed (6) with the idea of transferring the concept to other LDCs. of special signifi-cance is the fact that this experience is not only relevant to the carbonization of coal, but also to the carbonization of biomass residues, and therefore teaches a number of lessons, especially in the marketing of new fuel products. Because of the Inescapable need for additional, clean burning energy sources, there can be little doubt, therefore, that pyrolysis must emerge as a basic technology in the developing world. In countries where both coal and process wastes are present, an integration of the coke/char/tar production and marketing efforts is strongly indicated. How can this transition to pyrolysis be promoted? We believe that to facilitate rapid growth of a viable carbonization Industry, there is no alternative but for government Involvement to guarantee and stabilize demand for the pyrolysis products until the Industry has reached a critical threshold where commmercial and domestic needs generate a self-sustaining market. The Indians recognized the role of government in their coal carbonization Industry, but approached the problem on the supply rather than the demand side with the formation of subsidized, state-owned corporations. This was not entirely successful. For this and other reasons, we believe the wisest course is to derive a system of government policies and, if neces-sary, a temporary price support system to encourage willing entrepreneurs to enter into this activity. For example, the government Itself could buy fuel from the carboniza-tion industry. Further, it might add a tax on imported fuels for which carbonization by-products could be substituted, and it might offer tax incentives to those who utilize these products. In heavy Industry, such as cement, where huge quantities of energy are required and which have the flexibility of burning a variety of fuels with little conversion costs, use of these by-products would have the effect of establishing a price-demand floor at a national level. This would almost certainly stabilize the fledgling carbonization Industry.

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We believe that governments and international organizations must recognize their role in the development of a carbonization Industry in LDCs and Implement programs and policies to facilitate Its growth. Moreover, because the process plant owners in LDCs are beginning to utilize biomass burners and gasifiers in significant quantities, the time may soon come when these technologies have taken over, and thus it is economically impractical to Install pyrolysis plants, or any other conversion equip-ment3, to any significant extent. Thus, it is Important for high level government decisions regarding this question to be made as soon as possible. But the needs do not end there, for many technical Issues remain 3

In passing it should be noted that most of the arguments presented above should also apply to other methods for full utilization of process wastes, a fact which ought to. double the pressure on governments to take immediate action.

unresolved. One is production scale, another is the level of technology and the degree of capital intensity used. The experience of the Indians and the experience to date in biomass carbonization in LDCs indicates that large scale, highly mechanized, technically complex systems are not appropriate. However, they also teach that very small scale, highly labor intensive, rudimentary carbonization plants are also undesirable. Therefore, we believe that a medium scale, Intermediate Capital Intensive approach using technology, components and materials available in-country is most appropriate for many LDCs. Implicit in this approach is the assumption that labor saving machines are economical in any society, if they are locally manufactured of indigenous materials. While considerable progress has been made to develop biomass carbonization systems using this approach (4), and while substantial work has been accomplished in perfecting a partial-oxidation, moving bed pyrolysis system which minimizes the need for imported components, there is still much to be done. Therefore development organizations might well evaluate this approach and either support it or offer a superior alternative, since there is little time to waste before the crisis level in the developing world deepens to more tragic levels. 2. RECENT TECHNICAL DEVELOPMENTS To illustrate some of the latest work in the development of movingbed, partial-oxidation pyrolysis systems, Figure 1 is presented. The figure shows an overall view of a drierconvertor-condenser-off gas burner system designed by Tatom and Associates and constructed in 1982 at the PNOC—Renewable Energy Center at Quezon City, Philippines under UNIDO sponsorship. A detailed description of this facility and the partial oxidation process it uses is presented in (5). Fabrication, material and bought out equipment costs for the system, which is designed to process 100kg/hr dry feed, totaled (US) $15211. This includes (US) $3778 for imported components. Installation of the system was largely accomplished by the operating crew, although some outside support was also required for this work. This overall system resembles that built in Costa Rica in 1981 (4), but it includes a number of incremental technical developments such as an improved drier design, a

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locally built vane feeder system, and an upgraded off-gas burner. It is encouraging and of interest that the cost of this system was so close to the one installed in Costa Rica, a fact which suggests that rough estimates of pyrolysis unit costs in other LDCs may be made using these data as a reference. Another, simpler pyrolysis system, without a drier, was constructed in 1983 at the Thailand Institute of Scientific and Technological Research in Bangkok unader USAID sponsorship. Again the unit is basically similar to that of (4). However, in this program the exigency of time forced a number of procedural and operational changes that allowed substitution of several previously imported components, including the 1000:1 Airgitator gear reducer, with locally fabricated equipment, and thus demonstrated that foreign exchange requirements can be reduced to about (US) $2000. This was also a very encouraging development, and suggests that further reductions can be made in the future when more time can be given to the effort. Regarding future work, there is a growing interest in the production of soft coke from low grade coal as a smokeless domestic fuel source in LDCs. The varied technology used in India for coal carbonization includes several partial-oxidation designs, operating in. a basically similar manner to those described above. While minor modifications in the design would need to be made, there is no reason why these plants could not also operate on coal. Indeed, coal may be preferable to biomass as a feedstock because of its higher density and more free flowing characteris-tics. Therefore considering the experience to date with this design, there is no reason why it cannot be successfully commercialized to utilize either biomass residues and/or coal. While improvements in the unit are constantly being made, the basic system has demonstrated its reliability and efficiency and is thus ready for introduction into the marketplace. 3. REFERENCES 1) Tatom, J.W., et.al. “Third World Applications of Pyrolysis of Agricultural and Forestry Wastes,” Proceedings, American Chemical Society 1979 Meeting, Washington, D.C. September 1979. 2) Tatom, J.W., et al. “Pyrolysis Experience in Developing Countries”, Proceedings, BioEnergy ‘80 Conference Atlanta, April 1980. 3) Tatom, J.W., et. al. “Pyrolysis of Waste Biomass in Developing Countries,” Proceedings, Third International Conference on Energy Use Management, West Berlin, 1981. 4) Tatom, J.W. “Pyrolysis of Waste Biomass in Developing Countries; Costa Rica,” Proceedings, Second EC Energy from Biomass Conference, West Berlin, 1982. 5) Tatom, J.W. “Assistance to Energy Production from Biomass Waste Materials,” UNIDO Technical Report, DP/ID/SER.A/397 11 November 1982. 6) Schwartz, M. and Tatom, J.W. “Study of Coal Carbonization Processes in India for Domestic Fuels, United Engineers Report for USAID, June, 1982.

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Figure 1: Overall view of Philippine pyrolysis system.

GASIFICATION OF AGRICULTURAL RESIDUES IN A DOWNDRAFT GASIFIER LEIF LIINANKI, The Royal Institute of Technology, S-100 44 Stockholm, Sweden PER-JOHAN SVENNINGSSON, The Beijer Institute, S-104 05 Stockholm, Sweden GÖRAN THESSEN, Energiteknisk Utveckling AB, S-150 13 Trosa, Sweden SUMMARY The use of agricultural residues for production of producer gas has become of interest specially in areas with scarcity of wood. The special fuel properities, low bulk density, high ash content and low melting temperature for the ashes necessitate a new design of the gasifier suitable for agricultural residues. The studies at the Royal Institute of Technology have been focused on defining the design criteria for a gasifier for agricultural residues. Different types of modifications of a down draft wood gasifier have been studied, Test have been carried out with gasification of coir dust, cotton stalk and wheat straw. A design of the gasifier with a rotating grate was proved to be very suitable for gasification of these fuels.

1 INTRODUCTION 1.1 GENERAL BACKGROUND Producer gas has become of interest again as a consequence of the increased petroleum prices during the last decade. The basic idea is that the price differential between cheap biomass fuels and diesel or gasoline, in some cases can be high enough to compensate for the extra investment and operating costs associated with a gasifier. An isolated village with an abundancy of wood and extremely high transportion cost for petroleum fuels is the typical example when producer gas may be economically very attractive. Unfortunately, a more common situation is characterized not only by expensive liquid fuels, but also by a scarcity of fuelwood. If wood-based producer gas units are introduced under such circumstances, the already difficult wood supply situation may become absolutely disastrous. With charcoal gasifiers the danger is even worse, taking the low efficiency of charcoal production into account. One way of preventing this adverse effect of producer gas introduction is to use some other kind of organic fuel, the obvious choice is agricultural residues.

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1.2 DESCRIPTION OF THE FUEL The residues from agricultural production are of many different forms, e.g. straw, leaves, hulls, etc. In some cases, the residues are incorporated in the soil to make use of their nutritive value. In other cases, the residues are a by-product from agricultural process industries and not used for any useful purpose. A common feature for almost all agricultural residues is their low density. The calorific value is similar to wood, calculated on a dry, ash-free basis. The ash content is however higher than for wood, in some cases considerably higher, This results in a lower, “practical” calorific value, which combined with the low density makes the residues some what difficult to use as fuelwood substitute. When agricultural residues are used as a fuel, it is normally in industrial boilers as an integrated part of the process. Some agricultural residues have been used with success in gasifiers. The most notable example is coconut shells. Other residues have proved to be extremely difficult, or impossible to use in normal producer gas units. The difficulty is due to the density and structure of the residues, which can create fuel flow problems, and from the ash which can create slagging problems. Densification of the fuel, i.e. briquetting or pelletization, is a way of converting the residues into something more easily handled. The fuel flow problems in the gasifier, as well as general handling and storage, can thus be made easier but at a significant cost. Slagging can hardly be taken care of through fuel preparation, even though there are some ways of increasing ash melting points with chemical additives. 2 DESCRIPTION OF THE EXPERIMENTAL APPARATUS The experimental equipment consists of a downdraft gasifier with a gas cleaning and cooling system, and a 3600cc V8 Volvo engine coupled to the gasifier, fig 1. The gasifier, manufactured by Gotland Gengas, was originally equipped with a shaking grate but has now got a rotating grate.

Fig. 1. The experimental gasification system

Gasification of agricultural residues in a downdraft gasifier

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A. Gasifier B. Cyclone C. Filter D. Gascooler, watercooled E. Engine F. Torque indicator G. Compressor pump H. Start-up fan I. Start-up gascooler J. Rotating grate 2–22. Temperature measurements 23. Gas analysis (CO, CO2, H2, O2) 24. Gas samples for hydrocarbons and tar analysis 25. Gas flow measurements, Pitot static tube 26. Gas flow measurements, Roots pump 3 FUELS TESTED Four different types of fuels, wood, coir dust, cotton stalks and wheat straw have been tested extensivly in the gasifier. Some other fuels; bagasse and charcoal have also been tested at a limited scale. The chemical composition and the fuel properities are shown in table 1. The analyses on coir dust and cotton stalks are made on a sample from one briquette. There was a rather big variaty in ash content for different briquettes of the same fuel, probably depending on higher sand content for some briquettes.

Table 1. Fuel properties for the tested fuels Type Ultimate analysis Proximate Calorimetric Ash Bulk of fuel (dry and ash free) analysis dry basis heat value fusion density C H O N VCM* Ash FC* MJ/kg Temp°C kg/m3 Birch wood

47.6 5.9 46.3 0.2

79.6 0.5 19.9

18.9

Particle size

605 50×50mm

Energy from biomass

Coir 52.1 5.6 42.0 0.2 dust Cotton 48.2 5.7 45.2 0.9 stalks Wheat 48.3 6.0 45.5 0.2 straw * VCM=Volatile Carbon Matter

942

62.3 4.8 32.9

19.8

1145

73.0 5.1 21.9

18.2

1230

73.1 5.9 21.0

18.5

1310

FC=Fixed Carbon

1100 Briquettes D=70mm 1020 Briquettes D=60mm 710 Briquettes D=50mm Pellets D=12– 16mm Cubes 40×40mm

4 DESIGN OF THE GASIFIER Four different types of design of the gasifier have been studied, fig 2a-d.

Fig 2a-d. Different design of the gasifier

The original design, type A had a choke plate, diameter 90mm and a shaking grate. The air was injected to the oxidation zone by 5 air nozzels. This type of gasifier worked, as expexted, very well with wood blocks as fuel. With cotton stalk and straw briquettes there were problems with bridging of the fuel in and above the pyrolysis zone. The briquettes expanded when they were heated up, specially the loose compressed straw briquettes. The expansion in combination with the humidity in the fuel hopper caused formation of bridges which stopped the fuel flow. With type B and type C design there were still problems with bridging and slag agglomeration. It was obvious after these tests that the gasifier had to be redesigned to solve the problems with – material flow in the fuel hopper

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– slag formation in the oxidation and reduction zone A double conical inset was used in the fuel hopper to get space for the fuel to expand when it was heated up. That kind of inset has earlier been succesfully used with wood chips as fuel (1). There are principally two ways to solve the problems with slagging. – decreasing the temperature below the slag melting point – Zoutfeeding of the formed slag particles before large agglomerates built up In practical operation it is very difficult to keep the temperature below the slag fusion temperature without additional cooling i.e. steam injection. A lower temperature also gives a higher tar content in the gas which is unfavourable for a gas to an internal combustion engine. In our opinion the slagging has to be solved by outfeeding of the slag particles to the ash hopper before large agglomerates built up. A rotating grate was installed in the gasifier. The grate has an eccentric movement to transport the slag-char mixture into the ash hopper. 5 RESULTS AND DISCUSSION The results of the tests with type D gasifier are presented in tab 2.

Tab.2 Operating data and results of gasification tests in a down draft gasifier Fuel

Hood Cotton Coir dust “– “– “– “– “– “–

Fuel input kg/h

Air/Fuel Temp

Gas composition %

ratio

CO CO2 H2 CH4 N2 Nm3/h MJ/Mm3 g/Nm3 η

29.0 26.3 28.3

1.79 2.17 1.92

28.7 32.6 27.7 32.8 27.0 33.0

1.89 2.01 1.89 1.91 1.98 1.94

throat °C

1000 21.5 11.0 19.0 1.4 47.1 975 17.4 13.2 15.4 1.15 52.9 936 23.0 10.9 18.4 1.32 46.4 907 21.2 956 23.4 883 21.8 914 23.4 883 21.5 911 23.3

11.8 18.6 9.4 18.1 11.5 19.5 10.7 19.3 11.8 19.6 10.6 19.4

1.34 47.1 1.34 47.8 1.01 46.2 0.96 45.6 0.87 46.2 0.77 45.9

Gasflow LHV

Tar

Effic.

68.3 66.6 72.4

5.21 4.23 5.30

0.61 75.6 65.7 75.6

71.4 84.6 70.1 85.1 71.5 86.3

5.11 5.33 5.17 5.33 5.08 5.25

0.16 72.8 77.0 0.34 72.7 74.3 0.31 73.1 75.1

An energy balance over the process gives a total gasification efficiency to cold gas of 72– 77% calculated on the lower heating value. At the test with cotton stalk briquettes the grate was rotating during the whole run which gives an increased carbon loss and thereby a lower efficiency. Normally the grate had to be rotated only a few minutes every hour. The measured tar content was in all tests below 1g/Nm which is the highest value that can be accepted for a producer gas for internal combution engines.

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REFERENCES 1. “Producer gas as fuel for motor vehicles”. Överstyrelsen for ekonomiskt försvar, Stockholm, Sweden 1974.

ACKNOWLEDGEMENT The authors are appreciative of the financial support for this work granted to The Beijer Institute and the sub-contractor The Royal Institute of Technology by the Swedish International Development Authority. We also acknowledge important contributions to this work by Dr Björn Kjellström and Kjell Alfvengren.

SOME KINETIC ASPECTS ON THE PYROLYSIS OF BIOMASS AND BIOMASS COMPONENTS C.Koufopanos, G.Maschio, M.Paci and A.Lucchesi Dipartimento di Ingegneria Chimica, Università di Pisa, ITALY Summary An experimental and theoretical study on the pyrolysis of various biomass species and of their major components is presented. Experimental runs were carried out with the use of several thermogravimetric techniques. The obtained results indicate as the most significant parameters of pyrolysis the temperature, the solid residence time, the chemical composition of the material, the size and the shape of the tested particles. A lumping modelling approach is suggested for the intrinsic kinetics of the pyrolyzed particles. The biomass pyrolysis rate was related to the individual pyrolysis rate of the biomass components. For each component a reaction scheme involving three consecutive and competitive reactions was used.

1. INTRODUCTION Pyrolysis is a step necessarily involved in a thermochemical conversion process of biomass (combustion, gasification, liquefaction). In order to optimize the whole thermochemical process it is useful to describe the pyrolysis using simple mathematical models for the intrinsic and global kinetics. We studied the effect of the most important parameters on the pyrolysis rate and especially the effect of the chemical composition of biomass on the charcoal formation. A first attempt to correlate the pyrolysis rate with the biomass chemical composition is presented. 2. EXPERIMENTS We follow the progress of the pyrolysis measuring the weight-loss of single particles heated within a controlled temperature environment in an inert atmosphere (Nitrogen). Thermogravimetry Analysis (TGA) runs at a heating rate of 20°C/min were carried out in a CAHN thermobalance. In order to avoid either the heat and mass transfer phenomena effects the samples, we used in the above runs, had the form of a thin (lmm) layer of sawdust

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Isothermal mass-change determination runs were carried out in a special designed apparatus, which is described in detail elsewhere (1). We tested particles with different sizes (1–8mm) and shapes (spheres, cylindrical pellets). Flowing nitrogen was used in order to entrain the producted gas and eliminate, thus, the probable gas/solid secondary effects. Several lignocellulosic materials with a variant composition were tested (table I).

TABLE I: CHEMICAL COMPOSITION OF TESTED MATERIALS ( % of dried basis) Material Hemicellulose Cellulose Lignin Extractives Ash Cotton;(2) 0.6 99.3 - 0.1 Lignin(3) 94.0 - 6.0 Olive-husks 21.1 22.2 45.0 8.1 3.6 Beech-wood 12.7 50.5 29.6 5.3 2.0 Hazel-nuts 24.1 27.5 40.7 3.9 1.0 (1): organic components soluble in alcohol-benzene solution (2): practically it can be considered as pure cellulose (3): lignin separed in our laboratories from olive-husks, by using the Klason method,

3. EXPERIMENTAL RESULTS AND DISCUSSION The obtained experimental results suggest that the most significant pa rameters of biomass pyrolysis are: the temperature, the solid residence time, the chemical composition of biomass, the shape and the size of the particles. The differences on the behaviour of the major biomass components and of the various biomass species are cleary presented in the TGA results (fig.1,2). Cellulose is the component that, after a sudden decomposition, gives the lowest yield of charcoal, meanwhile lignin gives the highest yield. The various biomass species have an intermediate behaviour. We consider that the pyrolysis behaviour of the several biomass species can be attributed to the variant content of their principal components: cellulose, lignin, hemicellulose, extractives. So, olive-husks and hazel-nuts, species with rather high lignin content (table I), have a behaviour closer to the lignin one, meanwhile wood, a specie with cellulose as the dominant component, behaves in a manner more similar to the cellulo se one. Hemicellulose, the less stable and variant in the several biomass species component (2), ought to be responsible for the initial part of the biomass decomposition. Isothermal mass-change determination runs with cellulose, lignin, wood and lucerne tend to confirm the above considerations (fig.3). The isothermal curves in fig.4 present cleary the strong effect of the operation temperature on the pyrolysis rate and on the conversion level. At temperatures higher than 400°C the degradation is almost completed in a brief time period (smaller than 2min). The pyrolysis continues then with a very slow rate until the final conversion is attained.

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The variances in the pyrolysis curves, especially in the initial part, of particles with different size (fig.5) indicate the presence of heat transfer phenomena effects. This is also confirmed from the fact that, in the case of the larger particles, the temperature inside a pyrolyzed particle arrives at the operation temperature after a noticeable time period (1). 4. KINETIC MODEL We suggest a model describing the intrinsic kinetics of the biomass pyrolysis. We consider that the intrinsic kinetics is reflected in the weight-loss curves of the fine particles (<1mm). For the larger particles a different kinetic scheme involving also the transport phenomena effects must be taken into consideration (1), (3). As the lignocellulosic materials are extremely heterogeneous and the pyrolysis products involve a large number of substances, it is useful to represent the kinetics in terms of lumped components. We choose as reactant lumps the principal components of biomass: cellulose, lignin, hemi-cellulose and extractives, and as product lumps: the charcoal, the volatile and the gaseous products. We consider that each product lump of biomass pyrolysis is the sum of the corresponding lumps which are yielded from the pyrolysis of the principal components of biomass. Each component contributes to the products formation proportionally to the corresponding contribution to the virgin biomass composition. The above consideration assumes that the biomass components act during the biomass pyrolysis in the same way as the isolated components react. The following kinetic scheme for the pyrolysis of the biomass components is suggested:

where:A represents the virgin material, B* an active intermediate, C charcoal, G the gaseous and V the volatile products. The reaction 1 follows a zero-order and the reactions 2 and 3 a first-order reaction low. Their kinetic constants are represented by Arrhenius’ law. We fitted the above scheme on the TGA curves we have obtained for cellulose and lignin (fig.1). In the case of hemicellulose and extractives as it was not possible to have a representative experimental curve, we fitted the scheme on an hypotetical curve that was formed from the difference of the TGA curves: (Olive-husks)—(Cellulose+Lignin). The system of the non-linear ordinary differential equations that describe the kinetic scheme, was solved using a 4th kind Runge-Kutta technique and the best values of the parameters (table II) were estimated using a deepest descent algorithm and a least-square criterion.

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TABLE II: KINETIC CONSTANTS Component

k1 E1 k2 E2 k3 E3

Cellulose 109 123 109 119 109 129 Lignin 108 75 104 63 107 103 Hemicellulose +Extractives 108 75 106 73 109 110

The results of our model are in good agreement with the experimental ones (see for example in comparison the experimental and theoretical results for the pyrolysis of hazelnuts in the fig.6). 5. CONCLUSION The above study shows that the intrinsic kinetics of the various biomass species pyrolysis can be analyzed in terms of the pyrolysis of the major biomass components. A reaction scheme of three simultaneous reactions are suggested for the pyrolysis of each component. This scheme, with the addition of a fourth reaction describing the continuous devolatilization of charcoal at the higher than 500°C temperatures, can evaluate sufficiently the overall pyrolysis rate. A more precise description of the biomass pyrolysis can be obtained if we take also into consideration the probable physicochemical interactions between the biomass components. ACKNOWLEDGEMENT The reported work makes part of the Ph.D.Dissertation of C.Koufopanos, grantee of the Commission of the European Communities, which is gratefully acknowledged. NOTATION ki: frequency factor of the ith reaction, (min−1). i:1,2,3. Ei: activation energy of the ith reaction, (KJ/mol). REFERENCES 1. C.KOUFOPANOS, Report, period: 12.04. 1983–30. 11.1984 of the C.E.C grant No XII/355/82 E. 2. A.STAMM, E.HARRIS, “Chemical Processing of wood” Chem.Publ.Co,Inc, NY 1953. 3. D.PYLE, C.ZAROR, “Heat transfer and kinetics in the low temperature pyrolysis of solids” Chem. Eng. Sci., Vol.39,1 pp.147–158, 1984.

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NOTE: the weight W* in the following figures represents the ratio: (weight—ash)/(initial weight—ash).

Fig. 1: TGA Curves for cellulose, lignin, olive-husks. Heating rate=20°C/min.

Fig. 2: TGA curves for hazel-nuts, olive-husks and beechwood. Heating rate= 20°C/min.

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Fig.3: Isothermal mass-change determination curves for cylindrical pellets (1×10mm) of cellulose, lignin, beech-wood and lucerne. T=400°C.

Fig.4: Isothermal mass-change determination curves for cylindrical pellets (1×10mm) of beech-wood at various temperatures.

Some kinetic aspects on the pyrolysis of biomass and biomass components

Fig.5: Isothermal mass-change determination curves for beech-wood spheres. T=450°C.

Fig.6: Theoretical and experimental results for the pyrolysis of hazel-nuts at a heating rate of 20°C/min.

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WOOD PYROLYSIS: A MODEL INCLUDING THERMAL EFFECT OF THE REACTION R.CAPART, L.FAGBEMI, M.GELUS Department of Chemical Engineering University of Compiègne (FRANCE) Summary The pyrolysis of wood cylinders with diameters up to 22mm is investigated with a simple device, which allows to measure in the same experimental conditions the weight loss of wood as well as the change of the temperature at the surface and inside the sample. Evaluated by differential scanning calorimetry, the heat of pyrolysis appears to be slightly endothermic (+30cal/g). A good representation of the overall pyrolysis can be given by a mathematical model which includes the kinetics of reaction, the heat transfer by diffusion and the heat generation.

1. INTRODUCTION Irrespective of the type of gasifier (designed for the production of synthesis gas or of feed gas to a combustion engine), pyrolysis is an important stage in the gasification of wood, and can account for up to 50% of the total volume of gas collected. As a result, a knowledge of the rate of pyrolysis is useful especially when the gasifier feed consists of relatively thick wood chips. BAMFORD et al (1) were the first to develop a mathematical model describing the thermal devolatilisation of wood. Their model requires a knowledge of the thermal diffusivity of wood and also of the heat of reaction of the pyrolysis process, which is assumed exothermic (−86cal/g). Heats of reaction in the litterature are very variable depending on the author. The most reliable method of their determination, the differential scanning calorimetry technique, has been employed recently by Havens (2) ; this author showed that the heat of pyrolysis is in fact endothermic and relatively small: 47cal/g in the case of pines, and around 25cal/g for oak wood. 2. EXPERIMENTAL PROCEDURE This consists essentially in measuring the weight loss of a wood cylinder sample in inert atmosphere, by means of a thermobalance whose furnace temperature is preset at a reference value (between 500° and 600°C). In the case of wood cylinders similar to those

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used in thermogravimetric experiments (12cm long, 1.5 and 2.2cm in diameter), two thermocouples were used to record simultaneously the evolution of the temperatures of the surface and centre of the wood cylinder. Differential scanning calorimetry (DSC) measurements were performed using an apparatus “THERMOANALYSER 990” of DUPONT de NEMOURS, on about 10mg wood samples, in inert atmosphere, and using a temperature ramp of 20°C/mm. 3. EXPERIMENTAL RESULTS Figures 1 and 2 show typical examples of the evolution of the mass, and of the centre and surface temperatures, of a wood cylinder (pine wood) rapidly plunged in the furnace, at 540°C. The gradient of the temperature at the centre of the cylinder remains practically small between 360°C and 400°C, and then rises sharply above 400°C. On the other hand, it’s only at the end of pyrolysis that the surface temperature of the cylinder attains that of the nitrogen gas stream present inside the tubular furnace. A DSC analysis on the char (cf. figure 3) shows very clearly the existence of an endothermic peak whose maximum is situated at 380°C. For the pine wood used, the heat of reaction of the pyrolysis process which is a function of the area of the shaded region is estimated at+30cal/g. 4. MATHEMATICAL MODEL OF THE PYROLYSIS PROCESS This model is developped from heat and mass balance equations on the wood sample. Heat balance In the transient regime, the heat balance equation can be written, in cylindrical coordinates, as follows:

with: T—temperature

t—time

r—radius

λ—thermal conductivity

Q—heat of reaction

ρ—density of wood

Cp—specific heat capacity of wood.

The boundary conditions are: r=0 (axis of cylinder)

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T(rmax, t)=Ts(t)

Ts(t) being the surface temperature, measured using a thermocouple. Mass balance Considering that pyrolysis is mere thermal decomposition, the mass balance concerns only the term describing the rate of decomposition. Among all the existing kinetic models, that Tang (3) best describes our experimental results. This model considers a 2stage decomposi-tion process, the temperature limit between stages being 325°C. The model equations are as follows:

ρf being the density of wood char after pyrolysis; it’s estimated at around only 20% of the initial density ρ0(ρf =0.2ρ0). 5. APPLICATION OF THE MATHEMATICAL MODEL AND DISCUSSION The temperature inside the wood chip was calculated by a finite difference resolution technique of the heat balance equation. The simplifying hypothesis were as follows : – the ratio Q/ρCp is constant and is independant of the state of transformation of the wood, – the size of the wood sample doesn’t change during the pyrolysis. Below the threshold temperature of 390°C, wood is not completely pyrolysed and the thermal diffusivity (a=λ/ρCp) is assumed constant and equal to 27×10−4cm2/s. Above 390°C, the thermal diffusivity attains a much higher value : 120×10−4cm2/s. The change in thermal diffusivity corresponds to the abrupt jump in the rise of the temperature at the centre of the wood cylinder. This discontinuity is observed as from 390–400°C, temperature above which wood is supposedly completely transformed into char. On the other hand, as shown on figure 2, the temperature profile is correctly simulated, taking a heat of reaction of +30cal/g. Once the model’s kinetic and thermal constants are calculated by integration with respect to time of the kinetic equations, it then becomes possible to determine the density, ρ(r, t), which is a function of the cylinder radius and of the time of pyrolysis. The average density is obtained from integration of the following expression:

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There’s good agreement between the experimental and calculated curves of mass loss, as can be seen on figure 1. 6. CONCLUSION The profile of the enthalpy-analysis curves, as well as temperature measurements inside the mass of wood, show the existence of a threshold temperature at 380°–390°C above which the wood is profoundly transformed the mass loss is practically invariant and heat diffusion is much more rapid. The mathematical model recommended is similar to that of Bamford. With calculated values of thermal and kinetic parameters, the rate and time of pyrolysis of relatively thick wood samples can be predicted. The model, by taking into account the endothermicity of the pyrolysis process, shows that the effect on the rate of heat penetration inside the wood, is negligeable. REFERENCES (1) BAMFORD C.H., CRANK J., MALAN D.H. Proc. of Cambridge Phil. Soc. 42, 166–1946 (2) HAVENS J.A. “Thermal decomposition of wood” Ph.D thesis, University of Oklahoma—1970 (3) TANG W.K. U.S Forest Service Research Paper, FPL 71–1967

FIG. 1: RESIDUAL MASS Vs TIME (DIAMETER=22MM)

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FIG. 2: TEMPERATURE Vs TIME (DIAMETER=22MM)

FIG. 3: DSC CURVE FOR PINE SAWDUST

PLATFORM TESTS OF BIOMASS COMBUSTION AND GASIFICATION EQUIPMENT Miss Martine REYNIEIX C.E.M.A.G.R.E.F. B.P. 121 92 164 ANTONY Cedex (FRANCE) Summary Owing to its various research work on energy production from agricultural wastes, C.E.M.A.G.R.E.F. is carrying out platform tests on biomass combustion and gasification equipment. Tests financed by A.F.M.E. (Agence Française pour la Maîtrise de l’Energie) should provide a better knowledge of specifications and performance of the available equipment with a view to helping users. Tests carried out mainly deal with home furnaces and with wood and charcoal low and medium power gasifiers. The tests of home straw furnaces were carried out on manual and automatic feeding systems (bales, chopped straw, pellets) from 10 to 100KW. Test runs of gasification plants concerned the whole system, including gasifier—filters—engine (generating set) from 20 to 150KW power. The results obtained together with the lessons that can be drawn from the tests for developing combustion and gasification equipment are presented in this paper.

1. INTRODUCTION Development of energy production from biomass led the French manufacturers to take an interest in the market. As a result, a lot equipment was developed in both combustion and gasification fields. To provide a better knowledge of the specifications and performance of the available equipment, a test-programme (on site and on testing bench) was set up and financed by A.F.M.E. These operations should make distribution of reliable equipment easier in France as well as abroad, especially in developing countries. As part of this programme, owing to its research work on energy production from biomass, CEMAGREF was in charge of the platform tests on home straw furnaces and on low and medium-power gasification plants. 1 Tests on home straw furnaces: Tests were carried out on manual and automatic feeding systems (bales, chopped straw, pellets, etc.) ranging from 10 to 100KW. The procedure of tests which is based on the French standard NF 31–361 was jointly worked out by CEMAGREF and CETIAT (Centre technique des industries aerauliques et thermiques).

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The following features were determined for each equipment : – general specifications: conformity to plans and directions for use, size, materials, ease of utilization and maintenance, fire resistance, safety. – performance at different running rates: power, efficiency, autonomy, pollution control. The testing bench on which the furnace was settled was a hydraulic open circuit, equipped with measuring and recording devices required for drawing up matter and energy balances (direct method and loss method). Measurements were made on stabilized rate, without using control systems. * Results: Tests, confirmed by on site tests, showed that furnaces could be classified into three main types: – manual furnaces, Efficiency is low (40 to50%); frequent loading is necessary; it is impossible to control the combustion, thus giving rise to high losses into the smokes (high temperatures and volatile matters). However, this equipment is cheap and can use a raw material readily available on the farm. – automatic feeding systems Efficiency is higher (55 to 65%), problems of loading and autonomy are solved with the conveyor length but the ash-system is still handoperated. These units are often noisy, need space; they are expensive and they are only suitable for meeting high thermal requirements (>100KW) – automatic feeding systems with pellets Efficiency is similar to that of conventional fuels (70 to 80%). These furnaces can burn a wide range of pellets (straw-wood-urban wastes). Regulation of combustion is easy, as well as slow running regulation. The major handicap in the development of this technique is the cost of pelletization. After these tests, modifications and improvements appeared on equipment towards a better quality of combustion, regulation and safety. 2. Tests on gasification plants; Several French firms are interested in energy production from biomass gasification. While the follow-up of the big gasification plants is made on site, a platform test was set up in CEMAGREF to test low and medium power gasification plants. Tests carried out jointly with CEEMAT (Centre d’Etudes et d’experimentation du machinisme agricole tropical) concern the whole system, mamely gasifier, filters, engine (generating set), from 20 to 150KW, running with wood, charcoal or vegetable wastes (coconut husks, etc..) During the tests, the followings features were determined: – general specifications of the whole system: conformity with plans, size, materials, ease of utilization, maintenance, safety; – performance at different loads (low and full loads): gasifier energy efficiency, generating set efficiency, electrical power, feedstock consumption.

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Emphasis was particularly laid on the constraints and efficiency of the gas filtration and cooling system, before induction into the engine. *Results: Tests were mainly carried out on downdraft gasifiers combined with generating sets. Gasifier energy efficiency is in a range of 60 to 80% and generating set efficiency 15 to 25%. The electric power is below 5KW by liter of cylinder volume. Tests prove to be an improvement in the design of the gasifier, but two points are still unsatisfactory: – gas filtration: system maintenance is time and labour consuming, and systems are not enough efficient; too many impurities are still found at the engine induction level – engine air/gas regulation is very sensitive, making it difficult to achieve running stability at high loads. Before these deficiencies, improvement and research efforts must be carried on in order to come up with more flexible, reliable and efficient equipment.

BATCH CARBONISATION OF COCONUT SHELL AND WOOD WITH RECOVERY OF WASTE HEAT G.R.BREAG, A.P.HARKER and A.E.SMITH Tropical Development and Research Institute Culham, UK Summary In small scale batch charcoal production, some two thirds of the calorific value of the feedstock is lost as waste heat. This paper describes technology whereby this waste heat can be recovered for use in associated processes, such as drying. Information is given on the development, application and economics of the technology. Work started using coconut shell as feedstock and following pilot plant trials to prove the technical viability of the system, a prototype unit was developed. Subsequently the prototype was installed, commissioned and operated at a Desiccated Coconut Mill near Negombo in Sri Lanka during October- December 1983. The Unit was connected to an existing furnace/heat exchanger system modified for operation on the gases evolved during the carbonisation process. The field trials demonstrated that the Unit as designed has a maximum capacity of 1.5 tonnes of dry coconut shell and yields 0.5 tonnes of saleable charcoal. The trials also showed that the system as operated, produces charcoal and simultaneously generates process heat equivalent to approximately 180 litres of fuel oil per 10 hour operation with the virtual elimination of obnoxious fumes emitted during the traditional carbonisation process. Technical data of this system are presented and discussed; and the scope for application of the technology in the Coconut Industry in Sri Lanka is reviewed. Subsequently the system has been adapted for use with wood as a feedstock. The basis of the adaptation is described and preliminary findings outlined and discussed.

1. INTRODUCTION In small scale batch carbonisation of charcoal, some two thirds of the calorific value of the feedstock is lost in waste heat. TDRI work on the introduction of improved charcoal production methods in developing countries led to consideration of the possibility of recovering this waste heat generated through the combustion of gases and tars evolved during the carbonisation process. Scope for the potential widespread application of a waste heat recovery system in providing process heat is recognised. Among the specific

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drying applications for which this system might be suitable are those for coconut products, timber, tobacco, tea, coffee, cocoa, spices and in the food industry generally. The potential economic gains to industries in developing countries afforded by carbonisation waste heat technology units are considered later. However, to put the potential into perspective, some global figures of wood and charcoal production are presented. Some 60% of the world’s roundwood is produced in developing countries and it is estimated that some 250 million tonnes per annum of wood residues, excluding sawdust and bark, were produced as a result of commercial timber felling and sawing. A large proportion of these residues is wasted and yet the energy situation in some timber producing countries is critical. The production of fuelwood in developing countries in 1981 was estimated by FAO at nearly 1,500 million cubic metres. Most of this was used for household consumption but, even so, the industrial use of fuelwood is considerable—in 1975, Earl estimated the proportion at about 20% of total consumption (1). If only a small proportion were converted to char-coal, the gains would be considerable. The 1981 FAO estimate of charcoal production in developing countries was about 17 million tonnes and, again, if only a small amount of the heat lost during conversion could be utilised for industrial purposes, the saving could be well worthwhile. The advantages of, and reasons for, converting biomass to charcoal are discussed in detail elsewhere (2). It is important to note that charcoal production should be carried out under the guidance of a Forestry Department or similar government body, to prevent the uncontrolled exploitation of woodlands. Coconut production worldwide in 1981 was around 37 million tonnes, representing in the order of 9.25 million tonnes of shell. The world market for coconut shell charcoal for activated carbon has grown steadily to reach about 80,000 tonnes annually in the early 1980s. At a 30% yield, the weight of shell to produce this total is about 270,000 tonnes, which is only a small fraction of the shell produced globally. Currently, there is a shortage of coconut shell charcoal and the European charcoal trade is actively seeking new sources of supply. Therefore, there would appear to be scope for a technology for the conversion of shell, at present being burned for copra drying or other purposes, into charcoal and for using the heat thereby generated for industrial applications. 2. DEVELOPMENT IN UK: COCONUT SHELLS The potential for the application of this technology in the coconut industry having been recognised, pilot plant trials using a vertical kiln were carried out to determine the correct method for producing coconut shell charcoal of consistently high quality and yield. Various designs of gas burners were then fitted and optimum conditions for maintaining steady combustion determined. In the trials it was shown that the “kiln gases” produced during the carbonisation of the coconut shells were combustible during 80% of the run and that the heat evolved remained fairly uniform during the process, apart from the initial and final stages. Thermal balances of the data collected suggested that the process was technically feasible and that further investigation of the process at plant scale was warranted (3). The unit’s

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potential for supplying process heat for desiccated coconut manufacture in associated furnace/heat exchanger systems was also recognised. It was therefore decided that further work on the development of a 1–1.5 tonne capacity coconut shell carbonisation unit with waste heat recovery be carried out in the UK. Chemical engineering design of the system proceeded and the carbonisation unit was manufactured and developed (4). The main findings of trials using imported Jamaican coconut shells were that the developed unit afforded a technically feasible system for the utilisation of approximately 75% of the heat evolved during the carbonisation cycle whilst making charcoal with a fixed carbon content of 76% and a yield of 25% (of dry weight of shell used). The heat evolved was found to be about 10×106kJ and accounted for 44% of the heat in the feedstock. A further 41% was contained in 270kg of charcoal produced from each batch operation. The remainder was lost to the surroundings. In addition, the trials showed that the kiln gas could be efficiently burnt for approximately 95% of the 9–10 hour carbonisation cycle. The heat balance is illustrated in Figure 1.

Figure 1: Average Heat Distribution of Shells

3. FIELD TRIALS IN SRI LANKA In collaboration with the Coconut Development Authority, (CDA), Sri Lanka, the TDRI carbonisation/waste heat recovery system was installed, commissioned and operated at Mahandraghamula Desiccated Coconut (DC) Mill in Sri Lanka during OctoberDecember 1983. The kiln was connected to an existing wood-fired furnace system which had a heat input of approximately 750,000 kJ/hr. The furnace was specially modified for operation on “kiln gas” and the front end of the gas burner/ furnace was designed and fabricated in UK and subsequently fitted. The furnace supplied heat to a semi-automatic dryer used to desiccate pared and milled coconut meat.

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Figure 2: TDRI Carbonisation/ Waste Heat Unit on Field Test in Sri Lanka Prototype kiln (see Figure 2): coconut shell carbonisation with the waste heat unit (WHU) consisted of a vertical kiln connected to a burner furnace system complete with fans for primary and secondary air. Primary air is that admitted direct with the fuel gas prior to combustion at the burner mouth, whereas secondary air is drawn through the furnace face behind the burner. The cylindrical metal kiln (1) for carbonising the coconut shells had an approximate capacity of 8m (see Figure 3). Two hatches (2) and (3) were provided, one on top of the kiln for loading the coconut shell charge, and the other near the base of the kiln for discharging the charcoal. The charcoal was supported by removable rods (4) that formed a grid over the gas outlet port. Six ports (5) were equispaced around the circumference of the kiln for lighting the charge. These flanged ports were hinged so that right-angled bend pipes, fitted with dampers to control finely the flow of air into the kiln, could be swung into position after lighting.

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FIG. 3 WASTE HEAT RECOVERY UNIT

FIG. 4 GAS AND AIR FLOW SCHEMATIC Metal mesh cages (6) were fitted at the inlet of the bends. These bends were used to direct any “blowback” downwards and to contain the flame or hot char which might be ejected. The gas outlet was located at the base of the kiln (7), connected by a pipe (8) to the burner via a damper (9), a condensation trap (10) and a flame trap (11). The damper’s function (9) was to control kiln gas flow to the furnace.

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Air supplied by the primary air fan (12) was mixed with kiln gas prior to ignition in the burner and the flow of primary air was controlled by an iris valve (13). In the kiln/furnace heat exchanger system (Figures 2, 3 & 4), the kiln was connected to the specially modified wood-fired furnace/heat exchanger and the hot “kiln gas” was ignited by a thimble (14) of burning charcoal inserted through the roof of the furnace. The secondary air passed through the slots on the front of the furnace (not shown in Figures 2, 3 & 4). Each slot was fitted with sliding plates to control the ingress of secondary air. The draw of combusted gases was adjusted by means of a damper (15) located in the outlet of the exhaust gas line from the furnace (16). This line was then connected to a centrifugal exhaust fan (17). The hot combusted gases passed on the shell side of the 84-tube heat exchanger/dryer system, shown schematically in Figure 4. Ambient air was drawn through the tubes heated by the gases of combustion into the semiautomatic dryer. The drying air was then exhausted via a centrifugal paddle fan. The semi-automatic dryer consisted basically of a chamber fitted with perforated trays through which pared, sterilised and shredded coconut meat cascaded counter-currently to the flow of drying air which entered at approximately 100°C. The output of the dryer ranged from 80 to 100kg/hr of desiccated coconut. 4. RESULTS AND COMPARISON WITH UK DATA Following the commissioning trials, further runs were carried out to establish a standard method of operation. In these early trials a ratio of 7 parts “copra shells” (half shells) to 3 parts “DC shells” (broken shells) by weight was used to simulate, as far as possible, the trials carried out in the UK using Jamaican shells which had a lower bulk density than the Sri Lankan “DC shells”. Once a repeatable method of operation, which suited the furnace/heat exchanger system of the semi-automatic dryer, had been established, the ratio of “DC shells” to “copra shells” was gradually increased until the feedstock consisted of “DC shells” only. The particle size and higher density of the “DC shells” affected operation and gave a different set of results from those obtained in the UK. The carbonisation of the higher density Sri Lankan shells tended to proceed more rapidly than that experienced with the Jamaican shells and therefore required a very careful watch to be kept on the rate of gas production of the kiln. Having established a standard pattern of operation and control of the process, measurements were taken of the following: quantity of feedstock; charcoal yield; the flowrate and temperatures of both gas and air streams in various parts of the system; furnace, kiln and dryer temperatures. A few readings of exhaust gas oxygen levels were also taken and the rate of DC production measured. Moisture contents of the feedstock were determined on site and samples of feedstock and charcoal were taken for analysis on return to the UK. Typical results are given in Table I.

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Table I: Charcoal Quality. Runs 1–10 Moisture content % (wet basis) 5.0 Volatile content % (wet basis) 18.2 Ash content % (wet basis) 1.1 Fixed carbon content % (wet basis) 75.7 Gross calorific value kJ/kg (dry basis) 31.510 Hydrogen content % (dry basis) 2 Carbon content % (dry basis) 78 Oxygen content % (dry basis by difference from ash, hydrogen and carbon) 19

From the data collected, heat and mass flows through the system were estimated and are summarised in Figures 5 & 6. The flow charts give a mean of the last 10 runs when a standard method of operation had been fully established (see Table II). The amount of heat accounted for, based on the net calorific value of the feedstock, is approximately 82%*. The remainder is attributed to heat losses, experimental error and heat required to raise the temperature of the system up to operational levels.

Table II: Table of Results. Runs 1–10 Copra DC Shells Shells %(1)

%(1)

Average Total Dry Charcoal Yield Dry Saleable Moisture Weight of Chaircoal/Dry Charcoal Dry Content (wb) Charge Charge Char-coal/Dry Charge % % % %

Flame Time Hours

15 85 12.5 841 44.7 35.3 6.9 15 85 12.4 1116 39.4 28.9 8.6 25 75 12.1 939 37.7 30.3 7.5 0 100 13.0 948 32.6 28.0 7.5 20 80 10.6 1355 33.7 25.6 11.0 25 75 12.5 918 36.3 30.7 7.0 25 75 10.6 974 33.5 30.4 7.9 25 75 10.5 914 33.7 28.7 7.5 25 75 10.3 963 34.6 28.9 7.1 15 85 12.2 1425 35.2 12.1 (1) nominal It must be noted that the heat and mass flow values given in this report are estimates and do not represent absolute values.

Batch carbonisation of coconut shell and wood with the recovery of waste heat

967

Figure 5: Average Heat and Mass Flows on an Hourly Basis

Figure 6: Average Recovery Efficiency. Runs 1–10

The hourly heat output from the combusted gases evolved during the carbonisation was approximately 600,000kJ/hr whereas that obtained from the plant operated in the UK was

Energy from biomass

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900,000kJ/hr. This difference is accounted for by the increase in yield of charcoal obtained with the Sri Lankan shells which was approximately 35%† compared with 25% recorded in the UK trials. It can be seen from Table II that the “flame time”-ie period during which combustion of the gases was sustained-ranged from 6.9 hours to 12.1 hours. The longer time was obtained by filling the system to capacity. In addition, it should be noted that extended operation of the unit could be carried out at the expense of yield; however, it would be best if considering a small increase in the capacity of the kiln to extend the height of the cylinder. Overall, it was concluded that the TDRI Carbonisation/Waste Heat Recovery Unit as designed has a maximum capacity of 1.5 tonnes of dry “DC shell” and yields approximately 30% by weight of saleable charcoal. It was also demonstrated that the system could be operated in tandem with a modified wood-fired furnace/heat exchanger semi-automatic dryer system with virtual elimination of the problem of obnoxious fumes which are evolved using the indigenous coconut shell pit charcoal method. 5. POTENTIAL APPLICATION OF THE UNIT There is clearly scope for the widespread application of the technology in coconut producing countries. In Sri Lanka alone there are over 60 desiccated coconut mills in which the unit could be used to fire a number of dryers and supply heat for the sterilisation process. Whilst there is insufficient heat evolved during the carbonisation of coconut shells to meet the entire heat requirements for processing the associated amount of coconut meat for DC manufacture, the efficiency of the system tested in Sri Lanka shows that the impact the technology could have on meeting these needs is considerable. In addition to the use of the technology in DC production, there is scope for the application of the system in the copra industry. An indication of the likely economic benefits is given in the examples in Tables III & IV, based on the operation of the WHU in Sri Lanka. The principal benefit made possible by the use of the WHU in Sri Lankan DC mills consists of the substitution of coconut shell for fuelwood. A semi-automatic dryer with a throughput of about 80kg of DC an hour requires about 750,000kJ per hour. A furnace system which burns around 800kg of wood (fresh weight) each working day (sufficient for this dryer) and could be replaced by a WHU using 1.5 tonnes of coconut shell daily as its feedstock. In Sri Lanka, wood is becoming increasingly scarce and therefore relatively costly to use. In using coconut shell, the DC mill owner has a material readily to hand at virtually no cost, the shell being a by-product of the industry. Income from the shell stems from its conversion into charcoal and this would continue unchanged as the charcoal yield from the WHU is more or less equivalent to that from the traditional pit method of charcoal production (30% w/w). There is thus no opportunity cost involved in using shell in the WHU. Moreover, a high quality charcoal is produced for which the activated carbon manufacturers in Sri Lanka are prepared to pay a small premium. In addition to the increased revenue for higher quality, no fees are payable to charcoal making contractors as is currently the case and, as the charcoal is made on the DC site, the need to trans-

Batch carbonisation of coconut shell and wood with the recovery of waste heat

†

969

The yield of saleable charcoal was approximately 30%, see Table II.

port the shell to the pit is obviated. A minor benefit is from the incidental production of liquor during the charcoal process which could have wood preserving properties. The annual cost savings and gains in revenue from the operation of the WHU installed in Sri Lanka at 1983 prices are shown in Tables III & IV and the estimated net benefit from the introduction of the unit is indicated in Table V. The calculations exclude any benefits from increase in DC throughput or improvements in DC quality. Nor are social benefits, such as diminished pollution or ecological advantages, quantified; nor are any benefits to the national economy, such as foreign exchange gains, incorporated.

Table III: Annual Savings and Gains in Revenue from the Operation of a WHU in Sri Lanka, at 1983 Prices $

$

1. Cost savings from replacement of wood-fuelled system: Wood (164 tonnes annually) 3,800 Wages for furnace operation 300 Ash disposal 50 4,150 2. Charcoal production cost savings and increased revenue: Charcoal contractors’ fees 300 Transport of shell to charcoal pits 450 Quality premium on charcoal price 450 Tar by-product for wood preservation (450 1. annually) 100 1,300 5,450

Table IV: Financial Analysis of the Operation of a WHU at a Desiccated Coconut Mill in Sri Lanka, at 1983 Prices $

$

(1)

Capital costs: amortisation on 10% pa over 15 years 1,050 Annual operating costs: Labour 1, 900 Production materials 800 Maintenance 300 Miscellaneous costs, overheads and contingencies 600 Annual cost savings and gains in revenue from installation of a WHU (1) Total capital costs were $8,100, including contingencies. The simple rate of return

4,650 5,450

is about 16%.

The application of the WHU for copra drying has not yet been tested, but it is likely that very substantial gains could result. The principal benefit from replacing smoke-drying systems would be from the production of a higher quality copra, so attracting a higher

Energy from biomass

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price for the producer. The other main benefit would be the production of charcoal from the coconut shell which is consumed for drying purposes. The quantity of shell now being used in Sri Lanka as the heat source for drying copra is assessed at around 40% of the total shell available for copra production. However, to generate sufficient heat for indirect drying, it is estimated that the coconut shell charcoal yield would have to be reduced to about 25% using the WHU technology. The following table sets out the potential net benefits from converting one Sri Lankan producer’s smoke-drying system to the WHU method. The present annual copra output of 300 tonnes could be dried using a single WHU in around 250 days. The price differentials between smoke-dried and hot-air dried copra were those obtaining in November 1983 and will vary according to market conditions.

Table V: Potential Net Benefits from the Application of a WHU in Sri Lanka to Drying 300 Tonnes of Copra Annually $ A. Added value on present output: Price premium of $82 per tonne on 255 tonnes Price premium of $98 per tonne on 45 tonnes B. Saving on contractor’s labour C. Increased production of charcoal: 25.5 tonnes @ $109 per tonne

20,910 4,410 1,700 2,780 29,800

Less production costs as in Table IV(1) Less 5% reduced yield on existing charcoal production

830 24.320 (1) It is assumed that the costs of adapting the copra drying shed for WHU operation are similar to those for adapting the DC system for WHU drying.

From this table, it is clear that even if the price differentials between smoke-dried and hot-air dried copra were to narrow considerably, significant gains would still accrue. Moreover, the production of charcoal from those shells which are now simply being burnt during the copra process would be a net gain to the national economy and potentially a valuable source of foreign exchange. 6. WORK ON THE CARBONISATION OF WOOD WITH WASTE HEAT RECOVERY Based on the experience gained with the coconut shell carbonisation with the waste heat recovery unit, work recently commenced on developing a similar system for wood using sawmill off-cuts and slab-wood. Initial trials were carried out using the TDRI 15 m masonry kiln which had been developed for charcoal production purposes only. For further details on the TDRI masonry kiln see (5). Based on the above kiln volume; a wood density of 500kg/m (dry basis); a packing density of 0.6; wood with a feed moisture content of 30% and a net

Batch carbonisation of coconut shell and wood with the recovery of waste heat

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calorific value of 17,500kJ/kg (dry basis); a charcoal yield of 25% by weight (dry basis); charcoal calorific value of 30,000kJ/kg and a heat loss of 20% of heat input to the kiln, the potential energy available in the gas was estimated at 29×10kJ. this is equivalent to 730 litres of oil of calorific value 40,000kJ/kg. To date initial tests with the masonry kiln using roundwood as feed-stock with 25– 35% moisture content (wet basis) have shown that a high yield -approximately 30–35% (dry basis)—of good quality charcoal can be obtained using an induced draught; but the gases evolved during the process were not easily combustible except for intermittent periods of to one hour at the latter stages of the run. The gases were analysed during the entire process and the results showed that the net calorific value of the gases was relatively low and ranged between 0 to 2,800kJ/m3 on a dry basis. Various methods of packing the timber in the kiln have been explored and it has been concluded that the method of operation and the geometry of the system need to be altered before the 29×10kJ of potential energy calculated, or part of this, could be harnessed for application in associated heat exchanger/furnace systems. Designs of the modified system are underway and are aimed primarily at improving the control of air entering the system with a view to promoting the production of a readily combustible higher calorific value gas paying due regard to the yield and quality of charcoal. In addition, steps will be taken both to study the effect of varying moisture content and size of the feedstock, and to condense out the majority of the moisture evolved during the carbonisation process prior to combustion. Preliminary calculations have shown that at the scale of operation of 456-tonnes of wood per week per kiln and assuming that approximately 29× 10kJ per batch of energy evolved in the gases can be used for process heat, this technology could be a viable economic proposition. Further details are not presented here as the plant still needs to be proven to be technically feasible. However, it must be stressed that in making any assessment of viability, costs and revenues will vary widely from location to location and the waste heat technology will need to be assessed on a site specific basis. REFERENCES (1) EARL, D (1975). A renewable source of fuel. UNASYLVA Vol. 27, No. 110, pp21–26. (2) SMITH, A.E. (1985). An analytical approach to the economics of small scale charcoal production in developing countries. Tropical Science, 25(1), 29–39. (3) BREAG, G.R. and HARKER, A.P. (1979). The utilisation of waste heat produced during the manufacture of coconut shell charcoal for the centralised production of copra. Report, Tropical Products Institute, Gl27, IV+22pp. (4) BREAG, G.R., HARKER, A.P., PADDON, A.R. and ROBINSON, A.P. (1984). The design, construction and operation of a unit for the carbonisation of coconut shell with recovery of waste heat. Report of the Tropical Development and Research Institute, Gl82, IV+18pp. (5) PADDON, A.R. and ROBINSON, A.P. (1984). The construction and operation of charcoal kilns built with locally manufactured bricks. Rural Technology Guide, Tropical Development and Research Institute, 25(1), 29–39.

FAST PYROLYSIS OF CELLULOSE R.G.GRAHAM, B.A.FREEL, M.A.BERGOUGNOU, R.P.OVEREND* AND L.K.MOK Engineering Science, The University of Western Ontario London, Ontario, Canada N6A 5B9 *National Research Council of Canada Ottawa, Ontario, Canada K1A OR6 Summary A fast pyrolysis process, termed Ultrapyrolysis (UP) has been developed at The University of Western Ontario to achieve the high heating rates, short residence times, high temperature and rapid quenching which are required to produce valuable non-equilibrium chemical intermediates (i.e. ethylene, acetylene, light organic liquids, etc.) from carbonaceous feedstocks. Hot solids and/or hot inert gas are used to carry and transfer heat to particulate carbonaceous feedstocks (i.e. wood, cellulose, lignite, coal, etc.) in a very turbulent vortical contactor (THERMOVORTACTOR). This turbulence creates an ideal environment for fast thorough mixing and rapid heat transfer. Preliminary trials with cellulose (Avicel PH102), lignin and wood powders were extremely encouraging and gave rise to the current cellulose pyrolysis kinetics studies conducted at temperatures between 750 and 900°C and residence times of 40 to 700 milliseconds (ms). Data and the resulting kinetic parameters for a first order decomposition model are reported at 800 and 900°C.

1. INTRODUCTION The fast pyrolysis of biomass has exhibited promising yields of high quality chemical intermediates (i.e. ethylene, acetylene, light organic liquids). Fundamental research has indicated that olefin yields of 10 to 15% by mass of the biomass feedstock can be realized and that little or no char need be formed under conditions of short vapour residence times (>500 ms), high temperatures (>700C), rapid heating rates (>1000°C/s) and rapid quenching of the reaction products (1,2,3,4,5,). A complete characterization of fast pyrolysis and an outline of its advantages with respect to product quality and selectivity over the more conventional conversion processes, have been presented previously (1,2). At the University of Western Ontario, the first phase of a fast pyrolysis program (Ultrapyrolysis) was conceptualized with the intention of engineering a continuous process which would successfully demonstrate the chemistry of fast pyrolysis. The heart of this primary objective was the development of a new ultra-rapid fluidized bed (URF) reactor design in order to exploit and optimize fast pyrolysis product yields. The preliminary results were encouraging and are reported, along with details of the design, in a report to the Canadian Federal Government (1). Upon completion of the first phase of the project, the system was modified to enhance operation for kinetics modelling, and

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was reinstalled in a larger laboratory. At the time of writing, nearly 200 kinetics experiments had been conducted using Avicel cellulose at temperatures between 700 and 900 C and at residence times of 40 to 700ms. This paper briefly outlines the current Ultrapyrolysis process flow scheme and the experimental operating procedure. Quantitative results are summarized for cellulose pyrolysis trials at 900 and 800C, and kinetic parameters are reported for a first order decomposition model. 2. ULTRAPYROLYSIS FLOW SCHEME The major components of the current Ultrapyrolysis (UP) process are illustrated in Figure 1. Rapid mixing and heat transfer are carried out in two conical vessels known as vortical contactors or Vortactors. The first has been termed a Thermovortactor and allows heat to be transferred from a hot “thermofor” stream (i.e. gaseous nitrogen, suspended particulate solids, or a combination of the two) to the biomass. The second is a Cryovortactor and allows fast quenching of the products by the direct transfer of heat to “cryofor” (i.e. cryogenic nitrogen). The Thermovortactor has two opposing tangential inlets for the thermofor. One tangential stream effectively destroys the momentum of the other causing severe turbulence. Biomass feedstocks are then injected from the top of the Thermovortactor through an air cooled tube into the turbulent region where mixing occurs within 30ms. The hot gaseous product is rapidly cooled (i.e. <30ms) by the injection of a single tangential stream of cryogenic nitrogen. The fast pyrolysis of biomass is initiated in the Thermovortactor and continues in a plug-flow entrained bed downflow reactor. The reactor is simply a one meter length of Inconel pipe which is housed in an electrical oven. The mixture of hot gases and biomass passes from the Thermovortactor, through the entrained flow reactor, to the Cryovortactor. With the insertion of cylindrical inserts to reduce the reactor volume and by manipulating thermofor/biomass flowrates, the residence time (i.e. the time from the heating of the biomass to the exit from the reactor) can be set between 30 and 900 ms. Reactor temperatures can be set in the range of 700 to 1000C. The UP flow scheme is described in greater detail in a previous publication (6). 3. EXPERIMENTAL In preparation for an experiment, the system is purged with nitrogen. The furnaces are then turned on and allowed to reach their setpoint temperatures. When the desired temperatures are reached, cryogenic nitrogen is injected into the Cryovortactor. Thermofor gas is then introduced into the system and the cryogenic nitrogen flowrate is adjusted to ensure that the Cryovortactor temperature is less than 350C. During this startup period the stream exiting from the Cryovortactor is sent to a bypass filter assembly and vented. The biomass feeder is activated and its feedrate is verified by directing the biomass flow to a collection device mounted on a balance. Immediately prior to the actual steady state experimental run, the thermofor/cryofor stream (which is exiting from the Cryovortactor) is switched from “bypass” to the mass balance filter. The biomass is directed to the Thermovortactor and the actual fast

Energy from biomass

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pyrolysis experiment is thereby initiated. Products are initially quenched in the Cryovortactor while additional cooling (approaching room temperature) is carried out in a water-cooled coiled tube heat exchanger. Solids and condensibles are deposited in the filter, and the entire non-condensible product gas is collected in the gas collection bags. For extremely short residence time trials (when the yield of “condensibles” increases), an electrostatic precipitator unit can easily be integrated in the downstream gas line. The steady state experiment continues for 3 to 10 minutes. Static samples are taken from the gas collection bags and analyzed after the run is completed. Gas analysis is accomplished ished using a Carle (Model 111-H/197A) gas chromatograph. Condensible products are extracted with a solvent and recovered in a rotary evaporator. RESULTS AND DISCUSSION The results of the fast pyrolysis experiments conducted at 900 and 800C using Avicel PH102 cellulose (a 100µm microcrystalline powder from FMC) are summarized in Table I. Representative curves of the mass yield (%) of total gas and ethylene vs residence time (ms), are given in Figures 2 and 3, respectively. The shape of these curves (i.e. an initial rapid rate followed by a tapering off to a constant maximum yield) is typical for all of the individual components identified in Table I. For example, the total gas production rate (i.e. the slope of the curve) at 900C is extremely rapid up to 100ms and then tapers off, giving a maximum yield of 81% (by mass) at 150ms (Fig.2). The gas yield then remains constant at least until 400ms, which is the longest residence time studied at this temperature. At 800C, however, the gas production rate does not taper off until about 200ms and the mass yield remains constant at about 78% after 350ms. These trends are also observed for the individual components. The maximum yields of ethylene (Fig.3) are 7.2% and 6.5% (by mass) at 900 and 800C, respectively. The maximum yields of total hydrocarbons and total unsaturates are 16% and 11% (by mass) respectively, at 900C. Corresponding values at 800C are 16% and 10%. A consideration of the equilibrium composition of the water-gas shift reaction (H2O+CO—H2+CO2) at 900C, and the fact that the CO, CO2 and H2 yields remain constant, leads to the conclusion that the shift reaction does not play an important role in the early pyrolysis reaction mechanism (i.e. at least up to 400ms at 900C). In addition, the yield curves for “crackable” hydrocarbons (i.e. such as ethylene, acetylene, ethane) indicate that no net thermal decomposition of these hydrocarbons occurs over the residence times studied. Therefore, primary pyrolysis appears to consist simply of the “unzipping” of the biomass polymer followed by rapid thermal fragmentation of the monomer units. There seems to be a lag time before additional gas phase reactions, such as the inevitable water-gas shift or thermal cracking of the hydrocarbons, occur to any extent. A simple and convenient approach to kinetic modelling assumes that cellulose decomposes directly to each individual gas component by a single independent pathway and that the kinetics of the decomposition can be represented by a unimolecular first order reaction. This approach has been widely used in representing the kinetics of the fast/flash pyrolysis of biomass and coal (4,7). The following rate equation is thereby derived: V=V*[1–exp(–kt)]

Fast pyrolysis of cellulose

975

where V is the mass yield of a component at time ‘t’ and temperature ‘T’, V* is the maximum attainable yield of the component at temperature ‘T’ and long residence times, and k is the Arrhenius rate constant (k=ko exp [−E/RT]). Best fit values for the kinetic parameters (V* and k) were estimated for all major components at 900 and 800C using a least squares non-linear regression procedure. The regression curves are indicated by solid lines in Figures 2 and 3, while the experimental values are illustrated with appropriate symbols. The values of V* and k for the rate of total gas production are 81.0% and 74.6s−1 at 900C, respectively, and are 78.4% and 10.4s−1, respectively, at 800C. Corresponding values for the ethylene production rate are 7.15% and 21.6 s−1 at 900C, and 6.55% and 9.55s−1 at 800C. Upon completion of the experiments over the entire temperature range (700 to 900C), the activation energies (E) and pre-exponential constants (Ko) will be estimated for each component. The mass balance calculations are not detailed in this report. However, after the recovery procedure (solvent extraction and subsequent filtration and rotary evaporation) was carried out for several selected experiments, between 95 and 105% of the input mass was accounted for in the product mass. This included the product water which was determined by Karl-Fischer titration methods. Similar pyrolysis experiments have been conducted at 700, 750 and 85C using cellulose (Avicel) as the feedstock. The data will be published at a later date along with kinetics equations for the rate of primary pyrolysis. REFERENCES 1. BERGOUGNOU, M.A. et al. (1983). Ultrapyrolysis of Cellulose and Wood Components. Enfor C-147. Environment Canada. 2. GRAHAM, R.G., et al. (1984). Fast Pyrolysis of Biomass. J. Anal. Appl. Pyrol. 6(2):95–135. 3. DIEBOLD, J.P. (1980). Gasoline from Solid Wastes by a Non-Catalytic Thermal Process. In Thermal Conversion of Solid Wastes and Biomass. Jones and Radding (Editors). Amer. Chem. Soc. Washington, D.C. 4. HAJALIGOL, M.R. et. al. (1982). Product Compositions and Kinetics for Rapid Pyrolysis of Cellulose, IE&C Proc. Des. Dev. 21:457–465. 5. DIEBOLD, J.P.: editor (1980). Specialists’ Workshop on Fast Pyrolysis of Biomass. Solar Energy Research Institute. Golden, CO. 6. MOK, L.K. et al. (1985). Fast Pyrolysis (ULTRAPYROLYSIS) of Cellulose and Wood Components. J. Anal. Appl. Pyrol. (In Press). 7. ANTAL, M.J. et al. (1980). Kinetics of Cellulose Pyrolysis in Nitrogen and Steam. Comb. Sci. Techn. 2:141–152.

TABLE 1.: SUMMAY OF KINETICS EXPERIMENTS: ULTRAPYROLYSIS OF CELLULOSE AT 900 AND 800 C. EXPERIMENT REACTOR RESIDENCE YIELD OF NON-CONDENSIBLE GASEOUS TOTAL NUMBER TEMP. COMPONENTS (% BY MASS) TIME GAS (C) (ms) Hydrogen Carb Ethylene Acyteylene Methane Carb Other* YIELD (% by Diox Monox mass) 12 900 204 1.9 5.3 6.9 1.7 5.1 59.4 1.6 81.9 14 201 1.8 5.3 7.1 1.5 4.5 56.1 1.8 78.1

Energy from biomass

15 21 22 23 24 25 26 27 28 33 35 36 76 77 78 80 81 82 138 139 140 37 38 42 43 44 45 46 47 48 49 50 51 52 53 54 71 72 73 121 122 124 125

800

198 1.8 155 1.5 151 152 79 82 92 83 91 150 151 349 322 203 108 333 198 199 45 46 39 208 206 200 208 110 114 107 162 160 160 274 236 259 243 359 343 340 263 79 82 54 60

* Includes Ethane and C3+ hydrocarbon

1.5 1.5 1.3 1.4 1.4 1.4 1.2 1.4 1.4 1.6 1.6 1.5 1.3 1.6 1.6 1.6 0.9 1.0 0.9 10 1.3 1.1 1.1 0.8 0.7 0.7 1.0 1.0 1.1 1.3 1.1 1.3 1.2 1.4 1.3 1.1 1.3 0.6 0.6 0.5 0.5

5.4 5.5 5.6 5.4 5.1 5.0 5.1 5.9 5.2 5.4 5.4 5.4 5.5 5.7 5.2 5.5 5.7 6.0 4.2 3.7 3.5 5.0 5.2 4.3 4.8 3.5 3.2 3.4 4.3 4.1 4.1 5.0 5.2 5.0 5.1 5.3 5.0 5.0 5.3 3.0 3.0 2.9 2.6

6.7 6.8 6.6 6.9 5.9 6.1 6.2 5.9 6.2 7.0 7.0 7.0 6.9 7.0 6.8 7.1 7.1 7.2 4.8 4.7 4.3 5.9 6.1 5.5 5.9 4.4 4.0 4.1 5.4 5.2 4.9 6.1 6.2 5.9 6.0 6.5 6.0 3.6 6.1 3.3 3.1 2.8 2.9

976

1.5 2.0 2.1 2.3 2.2 2.1 1.9 2.0 2.2 2.5 2.4 2.5 2.0 2.0 2.3 1.9 2.1 2.2 1.7 1.5 1.5 1.4 1.2 1.2 1.5 1.1 0.9 1.1 1.2 1.1 1.2 1.3 1.4 1.4 1.4 1.3 1.2 1.1 1.3 0.8 0.8 0.7 0.7

5.1 4.7 4.4 4.5 3.2 3.6 4.0 3.4 3.6 7.8 5.2 5.8 5.3 4.7 4.3 5.5 5.1 5.1 2.5 2.7 2.0 4.4 4.6 2.8 4.1 2.5 2.4 2.3 3.3 3.4 3.2 4.5 4.1 4.5 4.1 4.9 4.5 3.8 4.3 1.8 1.4 1.4 1.3

59.5 56.1 55.3 55.8 48.8 49.1 51.9 49.2 51.5 57.6 55.8 58.0 56.5 56.5 54.2 56.2 56.7 59.1 40.1 39.8 35.8 56.0 54.0 48.9 52.7 39.1 35.6 36.5 46.7 47.0 45.3 53.7 54.3 54.5 51.8 55.8 52.3 48.5 53.7 31.2 29.9 29.0 26.

1.8 2.3 2.2 2.4 2.1 2.0 2.3 2.2 2.3 1.7 1.9 1.6 1.8 1.9 2.2 2.1 2.2 2.2 1.4 1.8 1.8 2.3 2.3 2.3 2.5 2.0 2.0 2.0 2.4 2.5 2.5 2.3 2.7 2.4 2.4 2.3 2.4 2.1 2.6 2.1 1.8 2.1 1.9

81.9 78.9 77.7 78.8 68.6 69.3 72.8 69.0 72.5 80.6 79.1 81.9 79.6 79.3 76.3 79.9 80.5 83.4 55.6 55.2 49.8 76.0 74.7 67.1 72.6 53.4 48.8 50.1 64.3 64.3 62.2 74.2 75.0 75.0 72.0 77.5 72.7 67.2 74.6 42.6 40.6 39.4 36.7

Fast pyrolysis of cellulose

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FIGURE 1: ULTRAPYROLYSIS FLOW SCHEME

Figure 2 Cellulose Pyrolysis Kinetics (900 and 800°C):

Energy from biomass

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Figure 3 Cellulose Pyrolysis Kinetics (900 and 800°C): Ethylene vs Residence time

CONTRIBUTION TO THE EXPLOITATION OF RECOVERED WOOD THROUGH THE DEVELOPMENT OF CARBONIZATION AND ACTIVATION PROCESSES G.SAVOIA, G.BARBIROLI, A.GATTA, R.OSTAN, G.PASQUALI Azienda Regionale Foreste Emilia Romagna—Carbolisi S.p.A.Università di Bologna Summary Much quantity of wood, residual from coppices or forest—trees harvesting, or from orchards pruning, is available in Emilia Romagna and might be upgraded, to higher value products, in accordance with a project started by the “Azienda Regionale delle Foreste” and with the cooperation of some industries (Carbolisi, Cooperative, A.S.O.). A positive and economic possibility refers to the production of charcoal and its consequent activation under Carbolisi’s technological principle. A carbonization process has been developed, which allows the variation of the operative conditions according to the woody raw material quality and the desired end products. Many woody species may be used, whose commercial and technological characteristics have already been detected (black pine, white fir, maple, white and black hornbeam major and minor ash-tree, beechtree, chestnut-tree, neapolitan alder, locust-tree, several oak species, elm, orchards prunings). For temperature, pressure and residence time different conditions are requested for each woody essence to obtain the charcoal highest yield. The involved plant is really versatile though great attention must be paid to the pyrolytic gases and other by products. In the activation field, the qualitative characteristics have been defined for the active carbons, in order they meet the best performances and the lowest costs throughout their applications. Significant woody materials quantities, rotational or disposable in Emilia Romagna do exist, suitable for transformation into derivatives, which, due to their intermediate added value, their applied technologies, and their involved activities, assume an highly economic importance of productive, energetic, and environmental nature. As a reference the following data may be considered: Total wood availability 920.000 Tons/Year – from orchards pruning 720.000 Tons/Year – from harvesting inside the forest or from outside wood workings 200.000 Tons/Year

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A recent feasibility report establishes the principal phases for the best valorization of the woody materials in the Region. Considering the economical and technological maturity of the transformation systems, in Italy and abroad, the possibility appears for a differentiated program to be immediately started to reach the appropriate rentability during each step of a modern industrial utilization of the non merchantable woody materials. The development must be gradual and the greatest attention must be paid to the collection of these normally spread materials, in order its heavily negative conventional incidence be conveniently reduced. Precisely the program includes: – placement of one or more carbonization plants (Carbolisi process) and consequent addition of the activation units; – placement of one or more ethanol production plants (Inventa or Gulf processes) by acid hydrolysis; – installation of a pilot plant for the extraction and refining of the wood essential oils (in connection with the “aromatic” plants project” of the Azienda Regionale delle Foreste); – development of a new technology for the cellulose enzymatic hydrolysis; – development of cellulose aerobic degradation with microorganisms for proteic feeding stuffs production. Among the above initiatives the first and the second might be immediately implemented with technical and economical validity, whilst the other are still under trials and must be implemented. The carbonization and activation processes too, in spite of their technological maturity, have to be started and conducted to be consequently improved by the suggestions coming from a continuous working and adequate proofs plan. Particularly, with regards to the conversion efficiency, the carbonization times, the charcoal and byproducts quality, it can be said that the operative conditions have already been properly fixed for each wood essence. In fact the commercial and technological analysis of the principal species available in the Region (black pine, white fir, maple, white and black hornbeam, major and minor ashtree, beech tree, chestnut-tree, neapolitan alder, locust tree, several oak species, elm, together with several orchards prunings) show significant differences, and that leads to different carbonization modalities (temperature, pressure, residence time). The different species and their composition are two important elements for determining the technical and productive choice: it is useful to know the content of: cellulose, lignin, essences, pigments, resins, and water of course. Samples of different kinds, typical from Emilia Romagna hills, drawn from different parts of the tree, have been tested using the conventional and official analysis methods. The analytical results show relevant variations among the tree species, with reference to the benzene/ethanol extraction, for essences, resins and pigments. The highest percentage is coming from the barks. The richest extraction contents belong to the major and minor ashtree (29% w.), to the white fir (25%w.) and to the black pine (23%w.). The other kinds do contain inside the bark a quantity of extractable substances in a range between 3 and 7%w.; the same applies to the trunks of any species and dimension. Very interesting is the composition for lignin and cellulose as reported for different species. Lignin inside the barks: black pine (36% w.), white fir, oak (31% w.), black

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hornbeam, beechtree, ashtree (major), neapolitan alder, white hornbeam chestnut-tree (18–20% w.), ashtree (7–8%w.). Lignin inside the trunks and branches: black pine (28%w.), white fir (25%w.), others (14–15%w.). Cellulose inside the barks: white hornbeam (65%w.), maple (63%w.) beechtree, white hornbeam, chestnut-tree (60%w.), white fir, major and minor ashtree, oaks (55–57%w.), black pine (38%w.). Cellulose inside the trunks and branches: maple, black hornbeam, minor ashtree, locusttree, red oak, white hornbeam, chestnut-tree, neapolitan alder (78–82%w.) black pine, white fir (68–72%w.). The fixed carbon varies between 22–25%w. inside the barks and 14–19%w. inside all the trunks and branches. The mineral substances are highly present inside the barks: red oak, locust-tree, minor ashtree, white hornbeam, maple (10–13%w): They are reduced inside the trunks and branches (0,3 0,5%w.) independently from the wood essence. Inside the leaves high contents of proteins have been found: locust-tree, maple (25– 27%w.), major ashtree, neapolitan alder (23%w.), white and black hornbeam (19%w.), other kinds (7–13%w.). The cellulose content inside the leaves (oven dry) is relevant too: red oak, white fir, major ashtree (21–24%w.), all others (13–18%w.). The accuracy of the results is good, because for all the samples two analyses gave coincident values, and it may be observed that the woods, where two or more different samples were available, presented a high homogeneity with reference to the cellulose, lignin, extractable substances and fixed carbon percentages. (1) Although the wood carbonization may be considered as a relatively simple technology, to obtain economical results an optimization of several interfacing parameters must be done, and a greater attention must be devoted today than it was before, especially as a function of the consequent activation phases, which offers a valorization of the wood greater than the charcoal production alone. The carbonization process involves the following operations: – Special containers loaded with wood pieces, of suitable dimensions and moisture, are introduced into a furnace (U Type), formed with two parallel tunnels, connected by a common wall. This furnace (called reactor) includes consequentially the zone for: wood preheating and drying, containers transferring from a tunnel to the other, wood carbonizing, charcoal cooling. The heat is furnished to the wood indirectly in the carbonization zone by a proper heat exchanger, and directly in the drying and preheating ones, by combustion fumes obtained in an adjoining combustion chamber. The moisture free wood is separately extracted from the drying zone, and this leads to have a more concentrated pyrolytic liquid from the carbonization zone. The incondensable pyrolytic gases, generated by the carbonization mechanism, are burnt, in the said combustion chamber, to produce the heating fumes. Out of the pyrolytic vapours stream, coming from the carbonization zone, products are condensed, as the vegetal tars, and the watery pyrolytic liquid from which, if required, in a separate unit acetic acid, raw methanol, distilled water, and phenolderivates by fractionation might be obtained. The containers transferring zone, between the wood drying and the wood carbobonizing ones, operates as a cleaning room, because it prevents qualitatively different easeous fluids from mixine

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in the above mentioned zones. Out of the charcoal cooling zone the containers with the charcoal are automatically unloaded; then, loaded with wood, they are ready to start the process again. (2) The process influencing parameters are: temperature, residence time, reactor pressure, type, dimensions and moisture content of the wood. As the carbonization temperature inreases the pyrolytic products (liquid and gas) yield increases and the charcoal one decreases. The temperature variations also influence the composition of the products, including “the charcoal”. Pratically, as it is expected, higher the temperature higher is the fixed carbon content, being all the other conditions the same. Some indications are given in table 1(beechtree). T°C Yield %w. on d. wood Charc. Compos. %w. Charc. Moist. % Yield Fix C%w. CHAR. LIQ. GAS FIX. C VOL. ASH 450 550 650 750

33 28.5 27.5 27

43 46 46.5 46

24 25.5 26 27.5

75 87 89 90.5

21 9.5 8 6.5

4 3.5 3 3

4 3 2.5 2

23.76 23.92 23.74 23.94

The figures show that the complexive charcoal yield decreases as the temperature increases, but with a significant and proportional increase in the fixed carbon content, in such a way that the yield referred to this last is pratically constant. Generally speaking a production of charcoal at higher carbon content is preferable, but this means a significantly higher energy requirement. Because the fixed carbon content increases by about 7%w. only, between 550 and 1000°C it is really questionable whether operating at so high temperatures is interesting or not from the economic point of view, unless one wants to prepare in this way the charcoal for the possible following activation step. The combination in the process of the temperature combustion fumes at their inlet with their quantity, the heat exchange coefficient, and the internal speed of the pyrolytic emissions from the carbonizing wood, leads to variable temperature diagrams along the axis of the carbonization zone and these contribute to know how to improve the qualitative and quantitative yields of charcoal and pyrolytic byproducts. The inclinations of the temperature diagrams, (temperature versus combustion zone length), correspond to different heating velocities, which influence the results already discussed. With reference to the physical properties of the wood essences, those with less bulk density and softer are more suitable to the carbonization and activation processes, although the more economical production of the charcoal alone is preferably made with hard woods at higher bulk density. Relevant influence is represented by the moisture, chosen around 30%w. and by the thickness which conveniently must not exceed 20 cm. Indicatively the economical profile of the proposed carbonization process may be summarized: process investment US. Doll. 1.000.000 logistic investment US.Doll. 300.000 TOTAL US.Doll. 1.300.000 (1 US. Doll—Lit. 2.000)—Capacity 6.000 Tons/Year, turnover on Italian basis US.Doll. 1.650.000.= wood consumption 3,8 Ton/Ton, energy consumption 100 Kwh/Ton; Costs: wood US.Doll. 627,000, labour US.Doll. 210,000; others (utilities, maintenance, general expenses, commercial expenses, working capital interest, a.s.o.) US.Doll. 200,000, Depreciation 10 year and capital interest 18%/year US.Doll. 356,000; Total costs US.Doll. 1,393,000—Gross profit US. Doll. 207,000, Net profit US.Doll. 124,000—Net profit+Depreciation US. Doll. 284,000,

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Gross R.O.I. (including working capital the invested money is US.Doll. 2,000,000,=), 10.35% year; Pay Out Time less than 6 years. The true valorization of the process, from the thermodynamic and economic point of view, is the possibility to reach immediately the charcoal activation step in a separate unit by using the exceeding energy from the carbonization byproducts. This relevant aspect must be emphasized, and studies and trials must be continuously conducted to improve the activation modalities to produce the best qualitative range of “Active carbons”, whose performances must meet cheaply and competitively the applications requirements. First of all researches have been oriented to the identification of the commercial and technological characteristics necessary to the market, of the several poisons adsorbers from industrial and civil waste effluents, of the drinking water treatment, of the chemical purification and so on. Great internal surface area, high adsorptive capacities, appropriate densities, good pores distribution, adequate distributive handling are problems connected with a second and more sophisticated program of research, which includes the production cost reduction of course. The raw material pretreatment before the two processes is also important, and interesting results are coming out from the daily coordinated work. BIBLIOGRAPHY: (1) BARBIROLI G., MAZZARACCHIO P., Studio di fattibilità sulla valorizzazione di materiali ligno-cellulosici come materie prime nella produzione di combustibile e derivati chimici. “L’utilizzo delle risorse forestali in Emilia Romagna”. Monografia dell’Azienda Regionale delle Foreste—Bologna 1984. (2) OSTAN R., Sistemi energia 1982, Busto Arsizio—Descrizione dell’Impianto di carbonizzazione Carbolisi di Mortara (PV).

RESULTS OF TESTS WITH DIFFERENT GASIFIERS FOR FARM USE L.BODRIA and M.FIALA Institute of Agricultural Engineering, University of Milan G.SALVI Fuel Research Station, S.Donato Milanese Summary Air gasification is one of the more promising energy generation technologies for the farm. The results of an exhaustive campaign on plants having different technical characteristics, mostly funded by ENEA, are given.

FOREWORD Rational application of renewable energy sources on the farm requires careful evaluation of the quality and quantity pattern of the farm’s energy demand. In fact, since the cost of all renewable energy sources is significantly higher than that of conventional energy of fossil origin, the energy supply should closely match the demand pattern so as to maximize utilization without expensive storage systems. With specific reference to electricity generation, the many experiments made in the past few years highlighted insoluble problems of plant complexity when solar energy is used to power Rankine-cycle engines, while photovoltaic cells and windmills are very expensive and therefore scarcely competitive. Instead, the technologies at present having a more favourable cost/ benefit ratio are biogas production from animal waste and vegetal byproduct gasification. The former specifically finds its optimum utilization when the electricity demand is sufficiently constant with time and therefore matches biogas supply. When, as is often the case on a farm, energy demand swings widely during the day or during the year, a gasifier fuelling an electric generating set undoubtedly makes better sense. In this case, in fact, energy is stored as biomass, which is much easier and cheaper to store than other forms of renewable energy, and the plant can be run only when energy is actually needed. Based on the above, exhaustive experiments were run on gasifiers of various types, having different technical and operational characteristics, to evaluate their performances and assess their actual usefulness to agriculture.

Results of tests with different gasifiers for farm use

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1. PLANT DESCRIPTION The plants tested break down into three main groups: downdraft gasifiers, updraft gasifiers and fluidized bed gasifiers. Specifically, their characteristics are: 3 a) Downdraft gasifier, output 45 m3/h approx., feeding an electric generating set of 13– 14kW electric output. The fuel is small-to medium size wood (50×50×50mm approx.), maize cobs, briquetted byproducts (grape seeds, sawdust, nutshells, etc.). The gasifier is manually stoked. b) Gasifier as above, with twice the output (100 m3/h gas, 25–28kW). This plant is technologically more sophisticated, being equipped with a pneumatic filter-cleaning system, forced draft gas cooling and automatic stoking system with a load cell carrying the reactor, which controls fuel supply from a storage hopper. c) Updraft gasifier, gas production 20 m3/h, fed with charcoal and charcoal derivates (briquettes prepared from coal dust and scrap under pressure with the aid of a binder), to fuel a 5 to 6kW engine. d) Downdraft gasifier and direct gas combustion for hot air production, output 200,000kcal/h (5,000–6,000 m3/h of air at 150°C). e) Fluidized inert bed gasifier, gas production 30 m3/h, fuelling special burners (total output 35,000kcal/h), bulk-fed with dust and granules of olive residue, rice chaff, ground grape seeds, sawdust, etc., smaller than 2mm). The above plants represent different approaches, since types (a) and (b) are of medium to high technological level; (c) is a simplified plant, suitable to exploit the significant mass of currently non-utilized charcoal waste in the emerging countries; (d) is suitable for large heat demand, and (e) can be bulk-fed with any small-sized byproducts from food processing (oil residues, rice chaff, etc.) or from wood working, and which could not be used in a downdraft or updraft gasifier without expensive briquetting processes. 2. RESULTS Protracted operation (some 200h) of the five prototypes led to the following conclusions concerning utilization and typical problems. Gas quality: with the four updraft and downdraft gasifiers, gas composition and heat value scarcely vary with the type of fuel, provided the latter is of a lignocellulosic nature and its moisture content does not exceed 15% by weight. Load variations and consequent air intake rate variations of the reactor are of limited influence, provided they are kept within the design data. Heat value swings from 900 kcal/Nm3 under anomalous operating conditions to 1,250–1,300 kcal/Nm , which should be considered the maximum for this type of gas. Gasifier efficiency: specific fuel consumption at 10–15% moisture, and for the biomass types mentioned above, varies from 2.2 to 1.3kg/kWh, depending on the load; when running at 20–30% of maximum rated load, consumption lies around 2kg/kWh, while it drops to some 1.3kg/kWh at 90–100% of maximum rating. Gaslfier efficiency at full load is 68–70% for small (5–6kW) plants, and attains 75–78% for plants above 200 Nm3/h output, especially when the process air is preheated by waste heat.

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Char build-up: it depends on biomass type and size; with wood of optimum size for the gasifier, char drops to a minimum (2–3%), and increases with nutshells and the like (4– 5%). Generator set efficiency: the efficiency of the gas-electricity conversion ranges from 13% minimum to 23% maximum when the load goes from 25–30% to 90–100% of rated load; when accounting for gasifier efficiency, the overall efficiency (electric power output/biomass energy input) lies between 9–10% minimum and 19–20% maximum, with low moisture, optimum size biomass. Some problems were encountered in setting the speed regulator of the motor-alternator set, with consequent instability at variable load. Tar and oily matter build-up: with the downdraft technique, build up of heavy oily matter (mostly of a phenolic nature) is significantly reduced. In fact, the vapours and volatile matter that distill from the biomass under the effect of heat (pyrolysis) immediately flow through the red-hot bed in correspondence with the biomass air-oxidizing zone, where they are cracked and converted into permanent gases. With the updraft technique instead, and when the biomass has high volatile, lignin-rich matter content, a large amount of watery and oily vapours rich in acid, alcohol and phenolic compounds forms, originates difficult to control mists upon gas cooling and causes operating problems. Therefore, the results confirm that the updraft technique (gasifier “c”) is especially suitable for the gasification of charcoal having low volatile matter content (6–8% against 70–75% of usual biomass). Because of the low pyrolysable matter content, the gas is relatively clean. When air is fed under the stoker, the ashes come in contact with highly oxidizing gas and the metals of the salts contained in the ashes (sulphates, silicates, carbonates, bicarbonates, etc.) remain in the oxidized (maximum valence) state and have high melting temperature. With the downdraft technique instead, the ashes are in permanent contact with strongly reducing gas; the salt metals tend to go over to a lower valence (sulphates to sulphides, oxides to metals), and form low-melting eutectics, mostly consisting of alkaline salts, with consequent softening and caking of the gasification residues, which tend to clog the air path. Efficiency of the purification and cooling system: all the downdraft and updraft gasifiers tested posed some operating problem concerning gas purification. None behaved regularly, without clogged filters, scrubber cyclons or bags and consequent, sometimes large increase of pressure drop of the gas flowing through these devices. Further, with nitrogen-rich biomass such as briquetted grape seeds, corrosion sets on in the wet coolers due to the build-up of ammoniacal condensates that attack metals other than stainless steel. Remarks on fluidized bed gasifier operations: the temperature profile within an inert fluidized bed is very uniform (the maximum variation was some tens of degrees from spot to spot) as compared with the downdraft gasifier, in which the temperature can swing by as much as 300 to 400°C, also in the air inlet areas. This uniform temperature is due to the large heat exchange generated by the rapidly moving solid particles and does away with the harmful hot spots occuring in downdraft or updraft gasifiers. However, the mean bed temperature is at least 200°C lower than that obtainable in the downdraft system, and the esothermal reactions developing CO and H2 are not as strong, with consequent larger amount of inert gases in the gaseous phase.

Results of tests with different gasifiers for farm use

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For equal combustion air/fuel ratios, owing to the lower temperature, the biomass yields 10–20% less gas, and a corresponding quantity of residues build up in and tend to swell the bed. The gas has .slightly poorer quality, Its heat value is lower (some 1,000kcal/Nm) and density greater. The heat value can be raised to 1,200–1,300 kcal/Nm3 by running at lower air/fuel ratios so that the gas is enriched by high energy content hydrocarbons formed by the cracking of the primary breakdown products of biomass in an airless environment. In this case however, the combustion residues grow to some 15% of biomass, with a further negative effect on the gasification efficiency. 3. CONCLUSION Notwithstanding the problems encountered, which show further development work to be needed, the operating characteristics of the plants tested prove gasification to be of viable interest. During the tests the plants showed fair overall efficiency, and, when fed with the proper fuel, ran reliably and without interruption. In particular, electricity generating plants of 25–30kW rated power appear to be sufficiently suitable for farm use. Other aspects to be considered are the design of rational chains to feed the plants with biomass of suitable physical and dimensional characteristics and a study of the time required for plant operation and maintenance under continuous service conditions. The fluidized bed type instead is of greater manufacturing and operating complexity and is better suited for large power plants. MAIN REFERENCES (1) GARRETT D.E., (1978), Biomass gasification process development unit Symposium on biomass and wastes, Washington D.C., 8. (2) GARRETT D.E., (1979), Conversion of biomass materials into gaseous’ products—6 Biomass thermoconversion contractors’ meeting, Tucson, Arizona, 1. (3) REED T.B., (1979), Survey of biomass gasification (voll. I, II, III) –S.E.R.I., Golden, Colorado, 7. (4) SAKAI J., SHIBATA Y., (1982), Alternative gas-fuel producer for driving gasoline engine— A.M.A., Winter. (5) SIREN G., (1979), Wood fuel production experiments in Sweden—Proc. Conf. Biomass for energy, London, 7.

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Specific biomass consumption versus electric power in plant A and B.

ENVIRONMENTAL ASPECTS OF BIOMASS GASIFICATION Dr. P.Schulze Lammers Technische Universität München Bayer. Landesanstalt für Landtechnik Vöttingerstr. 36 D-8050 Freising Summary In the gasification of biomass, two steps in the process should be examinated with respect to their environmental acceptability. Liquid byproducts are produced during gasification, which could represent a severe environmental burden. Noxious substances are also released into the atmosphere by the exhaust of producer gas engines. The liquid condensate can be rendered harmless to the environment, however, the technology is expensive. The active slime method should be considered for large amounts of condensate. Smaller amounts can be disposed of in a harmless and energetically efficient way by heating it to approximately 900°C. The CO and NOx emission from a producer gas engine are less those from a diesel engine.

1. RELEVANT ENVIRONMENTAL ASPECTS OF GASIFICATION The thermochemical gasification of plant material is accompanied by the release of condensable components. The condensate contains water resulting from the moisture in the feedstock as well as that formed by partial combustion, and chemical reaction byproducts from the plant material. The amount and concentration of noxious substances in the condensate varies according to gasifier type (downdraft, updraft, fluidized bed), however, it is expected that the condensate will have to be treated and disposed of in all gasifiers. The problem of contaminated-water treatment and disposal will always occur when the raw producer gas is cleansed with gas scrubbers. In the framework of a R+D project supported by the German Ministry for Research and Technology, a counter-current gasifier was investigated in collaboration with the M.A.N.-Neue Technologie, Munich. With grain straw and wood as feedstocks, the results reported here were obtained in a series of measurements. The condensate from the counter-current gasifier contains water and chemical components. The amount of water was determined through elementary mass balances. Figure 1 shows that in addition to the water resulting from the moisture in the fuel, water is also formed chemically. The chemical components are shown in Table 1. The component with the highest concentration is acetic acid at 26g per liter of condensate. More important for the

Energy from biomass

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environment, however, is the presence of phenols and cresols due to their toxic effects. The total contenct of organic carbon (TOC), representing the amount of unidentified components, is also included in Table 1 along with the biochemical (BSB) and chemical (CSB) oxygen demand. The latter values are especially important when employing the active slime method for disposal. Investigations (1,2) have shown that the oxygen demand can be reduced by approximately 95% with the active slime method. A second possibility is heating or combusting the condensate.

Figure 1: Condensate production versus fuel consumption (wet) for wood Table 1: Concentration of the relevant condensate components (CSB=chem. oxygen demand, BSB=biochem. oxygen demand, TOC=total organic carbon) Average Variation pH Value Phenol (g/l) Cresol (g/l) Acetic acid (g/l) Methanol (g/l) CSB (g/l) BSBE (g/l) TOC5 (g/l)

4,2 2,4 1,3 26,0 4,1 107,0 60,0 47,0

0,5 0,7 0,4 13,0 2,2 33,0 19,0 23,0

Environmental aspects of biomass gasification

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Figures 2 and 3 show the dependence in the amount of the most important combustion products (CO and CxHy) on the furnace temperature. At 900°C, the flue-gas is nearly free of contaminates. From Figure 4, the amount of condensate (in relation to the consumed fuel), which can be injected into the combustion chamber, can be deduced. To guarantie complete combustion at sufficiently high temperatures (900°C), a maximum of 0,4kg condensate per kWh of producer gas as fuel should be burned. This is the case when the oxygen content in the flue-gas (excess combustion air) is to be held very low.

Figure 2: CO-emission of the furnace with condensate injection

Figure 3: CxHy-emission of the furnace with condejnsate in jection

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Figure 4: Combustion chamber temperature versus O2-yield of exhaust from condensate combustion ENVIRONMENTAL ASPECTS OF GAS UTILISATION 2. Gasification serves the conversion of a solid fuel into a gaseous fuel. The greater technological effort compared with simple combustion is justified when subsequently, a more valuable end-energy can be generated. Producer gas, therefore, appears predistined for an application in engines. The exhaust can be a relevant factor effecting the environment. The Figures 5 and 6 give the results of an exhaust gas analysis for a producer gas engine (125kW, 12.5:1, 211).

Environmental aspects of biomass gasification

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Figure 5: CO-emission of the engine (97kW) at various ignition points versus air mixture The nitrogen oxide content rises sharply when the ignition is advanced and the air mixture reduced. The CO emission, on the other hand, has its minimal value at=1.15. Compromises in the reduction of harmful emissions have to be made when tuning a producer gas engine, just as is the case for internal combustion engines with other fuels.

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Figure 6: NOX-emission of the engine (97kW) at various ignitions points versus air mixture REFERENCES: (1) SCHULZE LAMMERS, P.: Kenngrößen der thermischen Gegenstromvergasung von Weizenstroh und ausgewählter Holzbrennstoffe, Diss. TU-München-Weihenstephan, 1984 (2) LEUCHS, M.; P. SCHULZE LAMMERS: Vergasung von Biomasse und Nutzung des Gases zum Antrieb von Motoren, Endbericht zum F+E-Vorhaben 03E-4469B des BMFT

MODERN EQUIPMENT FOR THE GENERATION OF PRODUCER GAS OUT OF BLOCK WOOD AND GRANULAR WOOD WASTE Author: Dipl.-Ing. Kurt W.Jaster FRITZ WERNER Industrie-Ausrüstungen GmbH D-6222 Geisenheim, West-Germany Summary In view of the fact that the supplies of crude oil will soon be exhausted and due to increasing oil prices technologies of alternative energy generation gain new significance. The well-known technology of wood gasification was taken up, and modern applications of the fixed-bed gasifier with co-current gasification is described. The future will show the introduction of the fluidized-bed gasification and it will indicate the construction of a prototype plant.

1. INTRODUCTION Technological processes often have a habit of reappearing in a modified form many years after the original invention was first presented. However, there must be an economic necessity if the reincarnation is to be successful. The generation of combustible gas out of wood and biomass similar to wood is a wellknown technique. However, to be applied in our present era it must correspond to the state of modern plant development, and it must be more economical compared with common processes for the generation of energy. In the years from 1930 to approximately 1950 gasifiers for lump wood were widespread due to well-known reasons. The units were manufactured in massproduction, and since liquid fuels were scarce, they were largely used on vehicles. The gasifiers were inexpensive. However both, the gasifier and the engine supplying power, had a short servicelife. During those years this fact did not really matter for badly driven was still better than a good brisk walk. Due to the substantial increase in cost of crude oil, and being under the spell of the fact that these energy resources will soon be exhausted, scientists and engineers began to be reminiscent of technologies able to replace oil, and if possible, able to dispose of waste materials. It is small wonder that in this context the wood gasifier of the thirties and forties was taken into serious consideration. This particular unit used to replace oil then. Therefore,

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the question rises whether it should not be capable of regaining similar importance in our present era. Reminiscences transfigure and the disadvantages of the gasifiers are slightly superseded upon reflection. Forgotten are the extensive maintenance, the substantial reduction of the engine output, the bad load change behaviour and the bulky fuel. Virtually forgotten is also the black slop of condensate which was disposed of underhand, a fact which still sends shivers up the spine of eco-activists. It can easily be understood that a modern wood gasifier only stands a chance if it can surmount the disadvantages of historical units. The characteristics of the modern, ideal gasifier are: – mostly automatic operation – low maintenance – first class gas cleaning – excellent load change behaviour – minimizing of the condensate – different fuels must be tolerated – high efficiency. Unfortunately there is no ideal gasifier, and every scientist and engineer is forced to make compromises. Thus however, to successfully approach the ideal requirements, FRITZ WERNER is busy with the development of gasifiers by two different procedures: – co-current gasification in the fixed-bed – fluidized-bed gasification. The following chapters shall provide a close description of these units. 2. THE CO-CURRENT GASIFICATION IN THE FIXED-BED The co-current gasification in the fixed-bed is a development which applies the process of the famous down-stream gasifier but it has hardly any resemblance with the WW II model. The fuel supply (lump, dry wood) can still be done manually, however, it is usually arranged automatically. The biggest problem to be solved was the level sensing in the hot generator vessel as it sends out the signal to the conveying system filling the hopper. The next step was to solve the problem of the gas tight fuel charger. The valves must be gas-tight, and by no means should they be covered with wood tar. Step three is the gas flow in the gasifier. The gas flow must guarantee the cracking of all long-chained hydrocarbons; thus only carbonmonoxide, carbondioxide, hydrogen, methane in small quantities and nitrogen result. Step four comprises a gas cleaning of high quality so that modern engines with their low mechanic tolerances are not damaged. Step five is the conception of the gas cooling with dew point regulation; thus only a small amount of condensate must be disposed of. All five problems have been solved and FRITZ WERNER is in a position to offer gasifier for an output range of 20, 40 and 60kWe.

Modern equipment for the generation of producer gas out of block wood and granular wood waste

997

These units work in suction operation. Therefore the gas flow occurs due to the suction stroke of the gas engine. Unfortunately it was not possible to design these units as light and as small so that they could still be fitted onto vehicles. Their exceptional application is the stationary generation of mechanical (electrical) and/or thermal energy. The gasifiers described above are still equipped with a charcoal bed in the reduction zone which must be renewed regularly. Experiences have shown that according to the properties of the wood the charcoal bed must be replaced every 50 to 100 operating hours. However, the larger charcoal pieces may be reapplied. For an output range of 200 to 300kWe a unit was built in the course of development which no longer requires the renewal of the reduction zone. The essential changes compared to the smaller models are: – the gasifier operates in pressure operation – the gasification air is supplied as upper and lower air – the resulting ashes are disposed of via a turning grate – the inside of the gasifier is equipped with refractory lining. The unit is designed for continuous operation and high availability. The units described comply largely with the ideal gasifier mentioned at the beginning of this report. Their only restriction is the fuel. Only lump wood with a moisture content of 20% dry-basis is acceptable. A higher fuel tolerance cannot be obtained in the chosen gasification principle-cocurrent in the fixed-bed. New methods had to be found to avoid this handicap. 3. THE FLUIDIZED-BED GASIFICATION The main goal of this development is to reach a high fuel tolerance and to obtain outputs up to 2MWe or 10MW thermal. Granular biomasses such as saw dust, wood shavings and tree bark but also agricultural residues like chopped straw, peanut shells, rice husks etc. shall be applied. The first step of development shall exceptionally serve to use wood wastes. The agricultural materials which due to their low ash melting point are quite problematic will be dealt with in a second step. The fluidized-bed was chosen as gasification principle since the fixed-bed has failed. Furthermore it was stipulated that no carrier media such as sand to stabilize the fluidized-bed shall be applied to simplify the process. So far experiments with pilot plants were conducted which have shown encouraging results. This was also the reason that a prototype of almost commercial size was tackled. Test runs with test plants have been conducted. However in the course of these tests it was realized that a stepwise scale-up will be necessary as usually in process development. The next step will be the construction and operation of a 200–300kWel pilot plant equipped with all items which may be critical. Details of the fluidized-bed process are given in the joint data and flow sheets.

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FV 100/20 FV 200/40 FV 300/60 FV 500/300

998

DATA SHEET FIXED-BED GASIFIER GASIFIER

GAS ENGINE GENERATOR SET Energy Sensible Gross SENSIBLE Content of Heat from output HEAT GAS FUEL the cold gas gas at from from OUTPUT CONSUMPTION (calor. cooling clamp cooling exhaust value) water gas m3 (i.N)/h kW kWth kg/h kWe kWth kWth 70

90

5

26

20

20

15

140

180

10

52

40

40

30

210

270

15

78

60

60

45

770

990

55

280

220

220

165

Fig.1. 40MWE fixed bed gasifier in Indonesia

Modern equipment for the generation of producer gas out of block wood and granular wood waste

999

GASIFICATION OF BIOMASSES BY HTW-GASIFICATION PROCESS H.Teggers, H.J.Scharf and L.Schrader Rheinische Braunkohlenwerke AG, Köln, FRG. Summary The High-Temperature Winkler (HTW) process is developed by the Rheinische Braunkohlenwerke AG (Rheinbraun) in cooperation with the engineering contractor Uhde GmbH (Uhde) on basis of the atmospheric Winkler process. By increasing pressure and temperature an improvement of carbon conversion and gas quality and an essentially higher gas output could be reached in a 25t/day pilot plant on stream since 1978. On basis of these good results a large demonstration plant for gasification of Rhenisch brown coal to about 300 million m3 synthesis gas per year is under construction and will go on stream in mid-1985. The Rheinbraun HTWprocess is also further developed for other carbonaceous materials. In a small process development unit of about 40kg/h throughput various types of coal as well as wood and peat have been tested. Peat additionally successfully has been tested in the a.m. pilot plant.

1. INTRODUCTION Rheinische Braunkohlenwerke AG (Rheinbraun) has been developing the HighTemperature Winkler (HTW) process for fluidized bed gasification of Rhenish brown coal and other carbonaceous materials. The HTW development is based on the successful operation of two atmospheric Winkler gasifiers at Union Rheinische Braunkohlen Kraftstoff AG (URBK), Wesseling, a subsidiary of Rheinbraun (1). The development to the HTW process resulted in three additional achievements of economical importance: – Recycle of coal fines which are entrained from the fluidized bed increased the carbon conversion rate from about 90% to more than 95%. – The increased pressure lead to higher reaction velocities and a higher specific gas output per cross-section unit. – Increased temperatures of the raw gas leaving the gasifier resulted in a reduced methane content and an increased carbon conversion rate and thus in a higher yield of syngas.

Gasification of biomasses by htw-gasification process

1001

2. DESCRIPTION OF THE HTW PILOT PLANT Basic design and operating data for the HTW pilot plant which was started up in mid1978 have been obtained from the operating results of a process development unit (PDU) located at the Rheinisch-Westfälische Technische Hochschule (RWTH) at Aachen. The engineering partner of Rheinbraun for the design and construction of this plant was Uhde GmbH, Dortmund. The main design data were as follows: – Feed (dried brown coal) Up to 1,300kg/h – Gasification Agent Oxygen/steam or air – Raw Gas Production Up to 2,200m3/h – Gasification Pressure Up to 10bar – Gasification Temperature Up to 1 100°C

Figure 1 shows a simplified flow scheme of the pilot plant (2).

FIGURE 1: FLOW SCHEME OF THE PILOT PLANT FOR THE HIGH TEMPERATURE WINKLER PROCESS

3. RESULTS OF THE HTW PILOT PLANT TESTS By the end of 1984 in the pilot plant about 18 300 metric tons of dry brown coal have been gasified in various programs. The average availability of the unit reached about 65 to 70% during the last years. The longest continuous operating period was seven weeks.

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Table 1 shows a comparison of operating results of the HTW pilot plant with conventional Winkler gasifiers using oxygen/steam as gasification agent. It can be seen that the carbon conversion rate is increased from 91 to 96%. The synthesis gas yield of nearly 1 600m3 (STP) per tonne of dry brown coal calculated moisture and ashfree (maf) corresponds to 95 percent of a maximum synthesis gas yield of approx. 1 650m3 (STP) per tonne of brown coal (maf) as theoretically calculable at temperatures of about 950°C. Compared to the atmospheric Winkler gasifier, it was possible to more than triple the specific synthesis gas yield to nearly 7,000m3 (STP) CO+H2 per m2 of gasifier cross-section and hour by increasing the pressure and temperature.

TABLE 1: COMPARISON OF OPERATING RESULTS OF GASIFICATION WITH OXYGEN AND STEAM (bc=brown coal) Winkler gasifier HTW gasifying conditions temperature °C pressure bar gasifying agents oxygen m3 (STP)/kg*bcmaf steam kg/kg*bcmaf spec. yield (CO+H2) m3 (STP)/t*bcmaf spec. output (CO+H2) m3 (STP)/ m2·h C-conversion % * bc=brown coal

950 1,2

1000 10

0,42 0,18 1462 2122 91

0,40 0,33 max.1580 max.6825 max.96

In late 1981, a water scrubbing system and CO shift conversion were commissioned for part of the raw gas flow in order to gather experience for a rather large HTW demonstration plant with an adjustment to a H2 to CO ratio of approx. 2.3 to 1 required for methanol synthesis. Before feeding the raw gas into the conversion stage its dust content has to be reduced to less than 5mg/m3. This was carried out in a water scrubber system with success, i.e. values of 1–2mg/m3 were reached. On the basis of the test results of the HTW pilot plant, Rheinbraun started a program for the design, construction and operation of a demonstration plant for the gasification of brown coal. This demonstration plant comprises one HTW gasifier and all gas purification units to produce some 300 million m3 (STP) per year of methanol syngas. The plant is under construction and will be ready for operation mid-1985. The syngas from the demonstration plant will replace crude residue-derived syngas and shall be utilized for the production of methanol in an existing plant at URBK in Wesseling.

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4. FEEDSTOCKS FOR THE HTW PROCESS (3) (4) So far Rhenish brown coal has been processed mainly in the pilot plant. However, a great variety of other carbonaceous materials is also suitable for the gasification applying the HTW process. Feedstocks should have sufficiently high reactivity at gasification with oxygen/steam or air at temperatures below an ash fusion point not higher than 1 100°C and should have low caking tendency. A lot of tests and project studies have already been performed for customers all over the world, e.g. wood (Brazil, Sweden, Kenya), peat (Finland, Sweden, USÁ), lignites (USÁ, Canada, Greece), bituminous coals (South Africa, Australia) and coke from the hydrogasification of rhenish brown coal. From these laboratory tests and PDU tests carried out by Rheinbraun in close cooperation with RWTH at Aachen resulted that carbon carriers with high volatile contents and reactive coke can easily be gasified at low temperature and high reactor throughput rates. Consequently the ash fusion characteristics are not critical. It was further observed that the ash content of these feedstocks is often quite low. Therefore the HTW process is well suited for the gasification of biomasses. However, tests showed also that less reactive feedstocks, such as, subbituminous coals could be gasified with high reaction rates provided the ash fusion behavior allowed the operation at the required higher temperatures. The coal throughput per cross-section unit of the reactor is of course lower than in the case of reactive biomass. However, this effect will partly be compensated by a higher production of CO+H2 per tonne of feedstock (see Table 2).

TABLE 2: COMPARISON OF EFFICIENCY DATA FOR DIFFERENT FEEDSTOCKS FOR THE HTW PROCESS DEVELOPMENT UNIT Gasification pressure: 1 bar, C-conversion: 95%. Wood Peat Rhenish Brown Coal Specific feedstock throughput

1.12 0.89

Specific synthesis gas yield

1020

Specific synthesis gas output

1140

Hard Brown Coal (Lignite)

0.73

052

1 170

1 370

1590

1 040

1000

830

Gasification pressure: 1bar. energy loss. 10%. C-conversion 95%

The feedstock preparation is an essential part of the whole process, especially for biomass feedstocks. Wood, for example, has a fibrous structure and therefore shows quite different flowing characteristics in the solids handling systems than coal. Very fibrous feedstocks, such as

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wood branches and shrubs, but also some types of peat, can be utilized for the HTW process by proper feed preparation such as shredding or pelletizing. Additionally to the tests in the process development unit also tests in the a.m. pilot plant are necessary to prove the suitability of the feedstock for the HTW process. Such tests have been performed successfully for peat from Finland in two phases from February to April and from July to August 1984. The carbon conversion rate with 93% was satisfactory, the synthesis gas yield with 1 100 to 1 200m3 (STP)/t feedstock, (maf) due to the higher oxygen content of the peat was lower than for Rhenisch brown coal. Originally there were some problems with ash deposits especially in the second dust cyclone which could be avoided, however, by several measures. The content of trace matter, especially hydrocarbons and phenols in the crude gas was satisfactorily low, no tars were observed in the waste water. So it resulted that Finnish peat can be gasified to a synthesis gas according to the HTW-process. A further optimization of gas quality and efficiency data in a gasifier adapted to the special feedstock should be possible. Additional tests for better preparation of the peat to the conditions of the HTW fluidized bed gasification are going on. REFERENCES (1) SCHRADER, L.: Theis, K.A.; Recent Results of the Rheinbraun High-Temperatur Winkler (HTW) Process for Brown Coal Gasification. ICCR-Conference London, 04.10.– 08.10.1982. (2) TEGGERS, H.: Theis, K.A.; Scharf, H.J.: The Rheinbraun High-Temperature Winker (HTW) Gasification Process. ECE, Seminar on Chemicals from Synthesis Gas; Geneva, Switzerland, 27.06.–01.07.1983. (3) BELLIN, A.; Nitschke, E.: Schrader, L. and Will, H.: Biomass as Feed for the Rheinbraun HTW-Gasification Process. IGT-Conference on Energy from Biomass, Buena Vista, Fla, USA; 30.01.–03.02.1984. (4) BELLIN, A.; Scharf, H.-J.; Schrader, L. and Tegger, H.: Application of Rheinbraun HTWGasification process to biomass feedstocks. Bio Energy World Conference 84, 18.06.– 21.06.1984.

SYNGAS PRODUCTION FROM WOOD BY OXYGEN GASIFICATION UNDER PRESSURE G.CHRYSOSTOME and J.M.LEMASLE FRAMATOME—Division Creusot-Energie Summary The research developped during the past four years led to the conception of a two steps process. The first one is composed of a fluidized bed gasifier where wood chips are continuously converted in a steam and oxygen stream at 700–800°C. The gas leaving that first stage of gasification mainly contains CO, H2, CO2 and H2O but also significant amounts of CH4 and higher hydrocarbons; such a gas is not suitable for methanol synthesis. In the second step, the raw gas leaving the fluidized bed gasifier reacts with additional oxygen into a partial oxidation reactor; methane and higher hydrocarbons are cracked at 1 300°C and converted into CO, H2, CO2, H2O. An atmospheric pilot has been operated at Le Creusot since 1980, at a wood capacity of 400kg/h. Long duration runs since the end of 1982 have confirmed expected results in terms of methanol yield (a potential production of 0,5kg methanol per kg dry wood gasified has been experimentally achieved). Effective methanol synthesis has been performed, with the syngas produced, at the Lurgi Gmbh Company, Frankfurt. A pressurized pilot unit based on the same process will be implemented at Clamecy (department of Nievre—France) with the financial help of the A.F.M.E. (“French Agency for Energy Savings”) and the E.E.C. The nominal capacity of this unit will be 60 tons per day (dry basis) of wood under a 15 bars pressure. Preliminary testings of the pilot plant of Clamecy should begin in 1986.

1. INTRODUCTION The “New Products” Service of CREUSOT-ENERGIE extended its activities four years ago to the development of new gasification and combustion processes. Within this service, the Laboratory of Energetic Testings was erected in 1980. First, an atmospheric pilot unit was built for the experimentation of the oxygen gasification of wood in a fluidized bed in order to generate a syngas (for methanol production). That research has been led with the financial support of the A.F.M.E. (“French Agency for Energy Savings”) and the European Communities (DG XII, in the “methanol from wood” program).

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The construction of the atmospheric pilot plant has been achieved by the end of 1980. Since that date, experiments on various materials have been run on wood, straw pellets, pine bark, sugar cane bagasse pellets. 2.DESCRIPTION OF THE PILOT

Figure I: CREUSOT-ENERGIE Process Schematic diagram of the atmospheric pilot plant (400kg/h wood) The pilot is composed of a 500mm in-diameter fluid-bed gasifier and a 800mm indiameter secondary reformer. The gasifier is made of a steel casing with outside insulation. At the bottom, a fluidizing grid ensures the injection of an oxygen-steam mixture. The height of the gasifier is 5m. In the upper part of the gasifier, a 700mm indiameter disengaging height ensures lower velocities of gases and so lower fine particles elutriation. Wood chips (50×20×10mm max.) are fed by a semi-continuous feeding system into a 0,7m3 charge hopper, then fed into a variable rotating screw feeder for adjustable feedrate. Wood chips then fall down into a rotary valve and finally are fed into a second screw feeder at a high rotating rate for rapid transfer towards the hot zone of the reactor.

Syngas production from wood by oxygen gasification under pressure

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The gasifier is equipped on its whole height with 18 thermocouples (chromel alumel). The pressure above the fluidized bed and in the overall pilot is regulated just below the atmospheric pressure. The dry gas composition is measured with an infrared analyser for CO and CO2, a paramagnetic analyser for O2, a gas chromatograph for CH4, C2H4, C2H6, H2, N2, Ar. An argon tracer is injected, at a controlled flow-rate in the gasifier, allowing to determine the dry gas flow-rate produced by the installation and so, to perform mass and energy balances. The raw gas leaving the fluidized bed gasifier enters into the secondary reformer where oxygen is also injected. The secondary reformer is a 5m height vertical cylinder, refractory lined, allowing to work at temperatures greater than 1 300°C. Temperatures in that reactor are measured with six thermocouples (Pt—Pt.Rh). As at the outlet of the fluid bed gasifier, gases are analyzed. The gas leaving the secondary reformer is then cooled into a scrubber, sucked up by an exhauster and incinerated at the flare. The wood feed-rate is measured by accurate weighing of each charge fed into the hopper. At the beginning of each test, preheating of reactors is performed by natural gas combustion. 3. EXPERIMENTAL RESULTS The main set of results has been obtained during 3 long duration runs (100 hours each in stabilized gasification conditions) which were performed in november 82, december 82, march 83. Also, a 24 hours long duration run has been realized, at a 400kg/h wood feed-rate, in march 84, at a wood moisture of 15% on a wet basis. That last run was the guarantee run performed for the C.E.C. The following table I presents this set of experimental results and their comparison with the expected results of the pressurized pilot plant of Clamecy. Atmospheric pilot (Le Pressurized pilot Creusot) (Clamecy) Status PROVEN ESTIMATED Wood moisture (%) Fluid bed T (°C) Secondary reformer T (°C) O2 total/wood (kg/kg dry) Steam/wood (kg/kg dry) Carbon conversion (%) Dry gas production (Nm3/kg dry wood) Composition (% vol./dry gas) CO H2 CO2 CH4

15 700–750 1 210–1 450 0,57 0,08 99,3 1,35

15 700–750 1 300 0,60 0,40 100 1,34

43,0 32,4 23,9 0,7

38,8 30,9 27,4 3,0

Energy from biomass

Thermal yield (%) LHV gas/LHV wood Tons potential methanol per ton dry wood

1008

69

69

0,49

0,44

Table I: Experimental results 4. PRESSURIZED UNIT OF CLAMECY The second phase in the development of the syngas from wood production process of CREUSOT-ENERGIE has been starting up in early 1984. The A.F.M.E. brought its financial support to the engineering and construction of the pressurized pilot plant of Clamecy (department of Nievre) . The aim of the project is to built and to experiment a pressurized gasification unit, of a 60t/day dry wood capacity. The main equipments of the pilot will be : – the fluidized bed gasifier fed with wood chips, oxygen and steam – the secondary reformer fed with the raw gas coming from the gasifier and with secondary oxygen, to convert methane and higher hydrocarbons, – the gas treatment (scrubbing-cooling…) allowing to burn the gas in a boiler. The operating pressure should vary between 10 and 25 bars. The wood moisture will be about 15%. The schematic bloc-diagram of the unit is represented on figure II. The nominal operating conditions of the pilot are: – pressure: 15 bars – dry wood feed-rate: 2 500kg/h – moisture: 15% – 02 flow-rate: 1 490kg/h – steam flow-rate: 1 000kg/h The expected characteristics of the syngas which is delivered at the battery limits are: – raw gas flow-rate: 3 700Nm3/h – dry gas flow-rate: 3 350Nm3/h – dry gas composition (% volume): • CO: 39 • H2: 31 • CO2: 27 • CH4: 3 For this project, CREUSOT-ENERGIE and the A.F.M.E. are associated in a pool of Economic Interest named ASCAB, which means “Association for the development of substitute motor-fuels from wood gasification”. The demonstration unit of Clamecy will be operational in 1986.

Syngas production from wood by oxygen gasification under pressure

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Figure II—Schematic diagram— Demonstration unit of Clamecy CREUSOT-ENERGIE syngas from wood gasification process

temperature de pyrolyse isotherme soit atteinte le plus rapidement possible de façon que la fraction restante, au moment où l’équilibre est atteint, soit suffisante. De même pour la mesure non isotherme il est important que la temperature mesurée représente la temperature de l’é-chantillon. Les mesures isothermes ont eu pour objectif essentiel de se placer dans des conditions permettant de comparer le comportement thermique d’un bois de sapin et de son écorce en fonction des paramètres principaux suivants: • teneur en oxygène du milieu de 0 à 20% • temperature de 290°C à 400°C • taille de l’échantillon de 50 à 1000µm. Compte tenu de l’ imprecision sur la mesure de la temperature de l’échantillon au cours de la pyrolyse, les mesures isothermes ne permettent pas d’accéder aux paramètres cinétiques des reactions de pyrolyse. Les mesures effectuées en dynamique dans des conditions où le contrôle de la temperature de l’échantillon est satisfaisant, permettent de déterminer les paramètres cinétiques du bois et de l’écorce de sapin, de la cellulose et d’apprécier notamment les energies d’activation des diverses étapes de la pyrolyse. I. ETUDE THERMOGRAVIMETRIQUE ISOTHERME La thermobalance utilisée* permet de suivre la perte de poids d’échan-tillons pulvérulents places dans une coupelle en acier inoxydable de 3cm de diamètre suspendue

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a une balance électronique. La temperature du milieu est mesurée en plusieurs points proche de l’échantillon au moyen de thermocouples Pt/Pt Rh 10%. Le debit de gaz circulant dans le réacteur permet d’assurer une vitesse linéaire dans le tube de reaction voisine de 0,5m/s. (N.T.P.). Ces conditions sont proches de celles susceptibles d’être rencontrées dans des chaudières domestiques ou industrielles. Le choix des temperatures de pyrolyse a été fait de façon a mettre en evidence, pour chaque atmosphere de degradation et chaque échantillon, le rôle fondamental que joue la temperature autout d’une valeur critique qui sépare nettement une dévolatisation lente d’une dévolatisation rapide. Cette façon de procéder a pour objectif d’indiquer, dans des conditions réalistes de reaction, la temperature au dessus de laquelle il est néces-saire de se placer pour obtenir une vitesse de degradation compatible avec l’alimentation d’un foyer. Ainsi comme l’indique la figure 1, pour le bois de sapin en presence d’air et pour une taille de particule comprise entre 500 et 1000µm., 70% environ de la masse initiale est gazéi-fié au bout de 400 secondes a 320°C; pour le même temps de contact seul 23% de la masse initiale a été gazéifié a 306°C. Des courbes analogues, quoique moins marquées ont été obtenues pour le bois et l’écorce de sapin en presence d’azote. On admet généralement que le regime qui contrôle la decomposition thermique des matériaux cellulosiques est fonction du rayon des particules r soumises a degradation. Ainsi MAA (3) a montré que pour r<0,1cm la reaction chimique contrôle le processus alors que pour r>3cm le transfert de chaleur dans la particule est l’étape limitative. Nous allons voir a partir des résultats expérimentaux suivants l’influence de la taille de la particule sur le taux de degradation des échantillons de sapin places dans les conditions exposes précédemment. Les figures 2, 3, 4 montrent en fonction de l’atmosphère réagissante, l’influence de la taille de l’échantillon sur le taux de degradation. * Les experiences a temperature isotherme ont été effectuées au cours d’un séjour en Finlance (VTT laboratory Jyväskylä); la description du dispositif experimental figure dans (2)

THERMAL DEGRADATION OF FIRWOOD AND FIRBARK INFLUENCE OF SIZE AND GAZEOUS ATMOSPHERES J.R.RICHARD and C.VOVELLE C.N.R.S.—Centre de Recherches sur la Chimie de la Combustion et des Hautes Temperatures 45045 ORLEANS CEDEX Summary Thermal degradation of firwood, firbark and cellulose has been investigated by thermogravimetric analysis. The experimental device allowed to work with a 1–10g powdered specimen and a carrier gas flow rate equal to 40 l/min. This flow rate corresponds to a linear velocity close to .5m/s. This velocity simulates the conditions prevailing in domestic or industrial boilers. Classical thermogravimetric conditions (temperature increasing at a rate equal to 5°C/min) as well as isothermal conditions have been used. The main objective was to compare the kinetics of thermal degradation of heart and bark when some key parameters of the experiment were varied: • the temperature of the isothermal experiments; • the oxygen content (between 0 and 20%); • the size of the powdered sample (in the range 50–1000µm). The effect exerted by each parameter on the maximum rate on the extent of the thermal degradation are described in the paper. A simulation model has been used to calculate the kinetic parameters of firwood, firbark and cellulose from the experiments performed with a temperature increasing linearly. In the case of wood, various constituents can be taken into account. In particular, it has been possible to show that the maximum mass loss rate can be calculated with the kinetic parameters obtained for pure cellulose.

1. INTRODUCTION La pyrolyse des composes cellulosiques a été très largement étudiée au moyen de techniques diverses. Parmi celles-ci les méthodes d’analyse thermogravimétriques sont les plus courantes. Dans ce travail deux méthodes thermogravimétriques ont été utilisées

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• une méthode isotherme; elle implique la determination de la variation de la perte de poids en fonction du temps a temperature constante. • une méthode non isotherme souvent appelée dynamique; elle implique la variation de perte de poids en fonction du temps pour une augmentation de la temperature préalablement déterminée. Chacune de ces méthodes présente des avantages et inconvénients (1). Ainsi pour obtenir des données cinétiques, il est indispendable que la

Fig.1—Influence de la tempéra-ture, coeur de sapin, air, 500, 1000m

Fig.2—Influence de la dimension de l’échantillon, écorce de sapin, N2, T=400°C On peut constater qu’en. presence d’azote, il faut attendre 1200s. environ avant que le taux de degration de l’écorce de sapin de taille comprise entre 500 et 1000µm soit identique a la degradation obtenue pour des échantillons inferieurs a 63µm. Pour 10% d’oxygéne, l’influen-ce de la taille des particules est encore importante puisque comme 1’indique la fig.3, 80% du matériau est gazéifié pour un échantillon de taille inférieure a

Thermal degradation of firwood and firbark influence of size and gaseous atmospheres

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63m au bout de 1000 s.alors que pour ce même temps 55% environ de la masse d’echantillons de taille comprise entre 500 et 1000µm a été gazéifié.

Fig.3—Influence de la dimension de l’echantillon, ecorce de sapin 10% de O2, T=350°C

Fig.4—Influence de la taille de l’échantillon, écorce de sapin, air, T=306°C

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Fig.5—Influence de la nature et de la dimension de l'échantillon, 10% de O2, T=350°C La fig.5 montre le comportement du bois et de l’écorce de sapin; on note qu’après 600 s, 80% de la masse des échantillons de 63µm sont gazéifiés alors que seul 55% le sont pour des échantillons de 1000µm. Commentaires et discussion Si l’on se reporte aux diverses courbes rendant compte de l’influence de la dimension des particules sur la perte de masse des échantillons, certains résultats peuvent paraître surprenants. En particulier il nous faut chercher une explication aux differences de taux de gazéification observe pour des tailles différentes de particules en atmosphére d’azote. Cette question est importante car un grand nombre de modèles de pyrolyse de particules de grande dimension utilise les résultats obtenus avec des matériaux pulvérulents: les particules de grande dimension sont souvent considérées comme une reunion de petites particules qui sont chauffées différemment en fonction de leur position a l’intérieur de l’échan-tillon. La production locale de matière volatile est obtenue en intégrant la somme de la matière volatile de chaque particules plus petite. On suppose ainsi que la vitesse des reactions de pyrolyse est “infinie” mais que “l’équilibre de densité” instantané depend de la temperature locale instantanée. Les differences observées sont elles dues a la cinétique ou au transfert de chaleur? Le transfert de chaleur vers la surface de la particule est dû a l’effet combine de la convection des gaz et du rayonnement des parois du four. Or les mesures de temperature sont effectuées dans la couche gazeuse et non a la surface de l’échantillon; bien que ce phénomène ne soit pas très important il est possible que l’absorptivité du rayonnement soit plus grande pour la couche de petites particules. Dans les experiences décrites, l’épaisseur de la couche de particule est voisine de 3 mm; avec les échantillons de diamètre proche de 1 mm, la couche ne peut pas être considérée comme un continuum et il est vraisemblable que la conduction de chaleur dans la couche composée de grosses particules est plus faible. Ainsi RAO (4) a montré que le flux de chaleur dans l’état stationnaire était la moitié de celui calculé pour un continuum. La conduction transitoire dans la couche engendre un délai dans la pyrolyse et l’échantillon n’est plus chauffé de façon isotherme. Si l’on

Thermal degradation of firwood and firbark influence of size and gaseous atmospheres

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suppose que λ/ρc=0,18m2/s et l’épaisseur de la demi-couche d’échantil-lon voisine de 2mm, le nombre de Fourier devient pour t=60 s, Fo=at/ R2=2,7. Cet ordre de grandeur signifie que la conduction transitoire a un certain effet ajouté a celui de la cinétique. Autour de 350°C la pyrolyse atteind son maximum et elle est très sensible a une petite variation de temperature (5), il est possible qu’une variation de la conduction de chaleur de la couche de particules cause un changement dans la temperature moyenne de l’échantillon et cette variation de temperature peut engendrer un changement important dans la variation de la masse de l’échan-tillon, comme l’indique pour l’air la fig.1. Ce sont là quelques unes des raisons susceptibles d’expliquer les differences observées; il n’est pas possible pour le moment de quantifier les différents effets énumérés. Ces résultats expérimentaux permettent d’apprécier les differences de comportement du bois et de l’ écorce de sapin dans des conditions de temperature susceptibles d’être rencontrées dans certaines parties de gazéifieur ou de foyer. II. ETUDE THERMOGRAVIMETRIQUE DYNAMIQUE ET SIMULATION Les techniques de calcul généralement utilisées pour déterminer les paramètres cinétiques de degradation thermique d’un matériau solide ne prennent en compte qu’une reaction globale. Dans le cas du bois, qui comprend plusieurs constituants cette procedure conduit souvent a une dispersion importante des valeurs obtenues selon la fraction du thermogramme retenue pour les calculs (6). Au cours de ce travail, nous avons utilise une procedure différente pour la determination de ces paramètres. Elle repose sur l’utilisation d’un programme de simulation qui calculé la vitesse de perte de masse d’un matériau à partir de données d’entrée:vitesse de montée en temperature et paramètres cinétiques des reactions de la degradation thermique du matériau (5). Les valeurs de ces paramètres sont ajustées pour obtenir un accord optimum entre le thermogramme experimental et la courbe de perte de masse calculée. Le principal avantage du modèle de simulation est de prendre en compte plusieurs constituants et pour chacun, plusieurs reactions. Dans le cas du bois en particulier le modèle fait ressortir que le maximum de vitesse observe expérimentalement correspond a la cellulose. La fig.6 montre que la degradation thermique de la cellulose peut être représentée par une seule reaction d’ordre 1. La loi de variation de la vitesse de perte de masse est du type d/dt=ko exp(−E/RT.,=mo−m/mo−mf désignant le degré d’avancement de la reaction (mo: masse initialemf: masse du résidu final). La courbe calculée correspond aux valeurs ko=2,2 1022 s−1 et E=292kJ/mole.

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La fig. 7 représente les résultats obtenus pour l'écorce et le coeur de sapin. 3 constituants ont été considérés (lignine, hemicellulose, cellulose). Un bon accord entre résultats calculés et expérimentaux a été obtenu en utilisant une reaction pour chaque constituant. Toutes ces reactions sont d’ordre 1 et les paramètres k ,E et résidus sont donnés. bois composition initiale résidu final ko(s−1) E(kJ/mole) sapin écorce cellulose: 30% hemicellulose: 30% lignine: 40% cellulose: 40% sapin hémicellulose: 30% coeur lignine: 30%

30% 4.1018 50% 1,5.105 50% 3 30% 8.1018 40% 1.105 40% 5

250 82 42 250 82 42

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Les paramètres cinétiques obtenus pour la cellulose pure permettent de rendre compte du maximum de vitesse observe expérimentalement. REFERENCES (1) WENDLANT, W, Thermal methods of analysis, John WILEY and Sons, 1974. (2) SAASTOMOINEN, J. AHO, M., The simultaneous drying and pyrolysis of single particles Int. Symp.on alternative fuels. Oct.84 TULSA, OKLAHOMA. (3) MAA, P.S., Comb. and Science Technology 1973,7, pp 257–269. (4) RAO, S.M. et al. Ind. Eng. Chem. Fundamental 1984, 23, 294–298. (5) VOVELLE C. et al., 19th Symp. on Comb./Comb. Institute 1982, 797–805. (6) VOVELLE C. et al., Kinetics of thermal degradation of wood and cellulose by T.G.A. Comparison of the calculation Techniques, A.C.S. Annual Meeting, Washington, 1983.

GASIFICATION OF RICE HUSK IN A SMALL DOWNDRAFT MOVING BED R.Manurung* and A.A.C.M.Beenackers**, Twente University of Technology, The Netherlands Summary The design and operating characteristics of a new and simple continuous downdraft gasifier for rice husk gasification are presented. With this gasifier all the notorious problems with respect to solids flow, that prevented application of downdraft gasification for rice hulls at a small scale up till now, have been solved. Features are: no throat or other obstacles that may hamper solids flow; open air suction over the whole cross section to avoid hot spots; continuous ash removal by a rotating grid. The construction is simple and cheap and can be done locally. Reactor capacity tested is 10–25 kg per hour which suits the gasifier for small scale rural applications in developing countries. Operating data are presented in the paper.

1. INTRODUCTION Up till now a number of problems related to the properties of rice husk, prevented the application of simple downdraft gasifiers for rice husk gasification at the 10–50kg/hr scale which is the relevant capacity for the major part of attractive rural applications in developing countries (rice mill powering, water pumping, etc.). These problems are [1– 5]: – poor flow due to low density and swelling in the pyrolysis zone – poor oxygen distribution due to small particle size – sintering arising from oxygen distribution – lack of a well designed continuous ash removal system. Recently, an important investigation on small continuous moving bed rice husk gasification was published by Kaupp (1). However, after construction and operation trials of four prototypes, Kaupp had to abandon the concept of a continuous moving bed rice husk gasifier with a locally fixed fire zone. So, for a start, we tried to solve the problems that so far hampered the reliable operation of a small scale moving bed gasifier at a capacity scale of 5–10 HP. With the gasifier we ultimately developed all problems mentioned above indeed have been overcome. It has the following features: – no throat or other obstacles that may hamper solids flow – open air suction over the cross section to avoid hot spots – continuous ash removal by a rotating grid.

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* Present address: Institute of Technology Bandung, Dept. TK, Bandung, Indonesia. ** Present address also for correspondence: Groningen University, Dept. Chemical Engineering, Nijenborgh 16, Groningen, The Netherlands.

Such a rice husk gasifier with an internal diameter of 0.45 m has been tested at a range of specific loads. The first results are presented in this paper. 2. PROCESS PRINCIPLE The process principle basically is not different from that of the conventional downdraft moving bed gasifier but the design has been thouroughly adapted to allow for a smooth and continuous gasification of rice hulls at a small scale. The rice husk is introduced continuously at the top of the gasifier and flows downward by gravity only. The present design is open at the top. It is not an essential feature but it adds to the simplicity of the design and to reduce investment costs. Essential new features to allow for a smooth flow of the rice husk are the absence of a throat, which is typical for a conventional downdraft gasifier, and the installment of a rotating scraper for continuous ash removal which is usually not found in conventional downdraft designs. It is essential however in continuous gasification of particles which keep their shape upon gasification as is the case with rice husk. Air is sucked from the open air into the bed all over the cross sectional area of the bed surface. The absence of any type of nozzles for air introduction is another feature of the present design. It is essential for gasification of rice hulls, to avoid hot spots and by that to keep away from sintering problems that may hinder solids flow. More over, a uniform introduction of air over the entire cross sectional area generates a uniform oxidation zone over the same area with a rather constant radial temperature profile, low enough to avoid sintering and high enough to convert the major

FIG 1 SET-UP OF GASIFICATION SYSTEM

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part of the tar components originating from the pyrolysis zone. Additionally, conventional nozzles generate caves with poorly flowing solids like rice husk and cause a higher backmixing of pyrolysis products upstream the pyrolysis zone thus initiating swelling in that region which is another reason for the experimentally observed hampered solids flow in rice husk gasification with conventional downdraft reactors. Ash is collected in a conventional water seal from which it can be removed either periodically or continuously by conventional techniques. A special problem is that sinking of the particles depends on char burn out. Therefore a special device is installed in the water seal to cope with floating particles. This new feature of the design consists of a rotating screw which transports also low density particles to the bottom in the direction of ash outlet. The rotation rate ratio between the ash scraper and the rotating screw essentially is a constant, independent of reactor load, so that, for improved simplicity, both devices can be driven by one single engine with a variable gear.

FIG. 2 DOWNDRAFT RICA HUSK GASIFIER WiTH ASH REMOVAL SYSTEMS Downstream gas treating is conventional and needs no further description. Figure 1 shows the total set-up whilst Figure 2 shows details on the design of the new gasifier.

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3. EXPERIMENTAL RESULTS The operating conditions tested are shown in Table I. The maximum specific load was limited by the capacity of the downstream equipment rather than by the gasifier proper. The rice husk properties are given in Table II. The experimentally observed air-dry fuel ratio, the gas production per kg fuel and the gasification efficiency are all given in Figure 3. Favourable gasification loads are in the order ot 100–150kg/m2.hr or higher. A further improvement of the gasification efficiency can be expected from a better isolation of the gasifier. The composition of the solids residue is given in Figure 4 and the tar content of the gas in Figure 5, all as a function of reactor load.

Table I. Operating variables of 0.45m continuous downdraft rice husk gasifier. Fuel :Northern Italy rice husk Moisture content :0.115–0.125kg water/kg wet material Feed rate 10–25kg/hr :10–25kg3/hr Producer gas flow rate :11.5–40Nm/hr Peak bed temperature :700–1000°C bed height 0.5m :0.5m Pressure :atmospheric (open system)

Table II rice husk properties (d.a.f. basis; wt%) Origin C Italy

H

O

N

Ash LHV kJ/kg Bulk density kg/m2

0.514 0.055 0.424 0.007 0.195 15300

100

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FIG.3 HUSK TO GAS ENERGY CONVERSION EFFICIENCY, AIR REQUIREMENT, AND VOLUMETRIC GAS PRODUCTION PER kg DRY FUEL AS A FUNCTION OF GAS PRODUCTION The LHV as a function of the gas flow rate varies from 4370 to 4770kJ/Nm and it reaches a maximum within the measured range of gas flow rates. The initial increase in LHV with increasing flow rate is due to increased efficiency. The latter decrease in LHV correlates with disappearance of CH4 and C2 by improved partial oxidation of the pyrolysis products with increasing temperature in the oxidation zone. In all cases the LHV is sufficiently high for combustion in an internal engine. Tar cleaning, however, is essential for that purpose. 4. CONCLUSIONS Problem free continuous operation of this new device has been proven. The gas has a good calorific value for en- 40 gine applications and the design is sufficiently cheap and simple to justi- 30 fy a pilot implementation project in developing countries. Additional data will be published [6].

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ACKNOWLEDGEMENT; The financial support of the Netherlands Ministry of Foreign Affairs in carrying out this research programme is acknowledged.

FIG.4 ULTIMATE CHEMICAL ANALYSIS OF THE RESIDUE APTER GASIFICATION AS A FUNCTION OF PRODUCT GAS FLOW RATES

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FIG 5 PRODUCT GAS TAR CONTENT AS A FUNCTION OF PRODUCT GAS RATES REFERENCES 1. Kaupp, A. Gasification of Rice Hulls, Theory and Practice; German Appropriate Technology Exchange, Fed. Rep. of Germany, 1983 2. Beenackers, A.A.C.M. and Van Swaaij, W.P.M. “Gasification of Biomass, A state of the Art Review” A.V. Bridgwater, Thermochemical Processing of Biomass, Butterworths, (1984) 91– 136. 3. Aarsen, F.G. van den, Beenackers, A.A.C.M. and Van Swaaij, W.P.M. “Performance of a Rice Husk Fuelled Fluidized Bed Pilot Plant Gasifier” Producer Gas 1982, The Beyer Institute, Stockholm (1983) 383–391. 4. Beenackers, A.A.C.M. “Development of a Small Moving Bed Rice Hull Gasifier by ITB and THT"; one year Research Proposal for Robert Manurung. Twente University, Enschede, The Netherlands, March 1983. 5. Susanto, H., Beenackers, A.A.C.M. and Van Swaaij, W.P.M. “Moving Bed Gasifier with Internal Recycle of Pyrolysis Gas”. Producer Gas 1982, The Beyer Inst., Stockholm (1983) 317–334. 6. Beenackers, A.A.C.M. and Manurung, R., Producer Gas 1984, The Beyer Institute, Stockholm, in press.

FUEL-AND SYNTHESIS GAS FROM BIOMASS VIA GASIFICATION IN THE CIRCULATING FLUID BED P.MEHRLING and R.REIMERT LURGI GmbH, D-6000 Frankfurt/Main Summary Gasification of biomass yields a most universally applicable intermediate or final product gas. LURGI selected the Circulating Fluid Bed principle (CFB) for its new biomass gasification process. This process principle has been applied very successfully in other industries (calcination, combustion) for more than one decade. The applicability of CFB to wood gasification has been demonstrated in several pilot plant test runs. Test results corroborated the expected process advantages, e.g. tar-free gas, high specific throughput, good partload behaviour, broad range of feed particle sizes. Based on the pilot plant data on the one hand, and on the extensive experience with pressure gasification, gas cleaning and gas processing plants on the other, plant concepts were established for co-production of power and process heat and for methanol production. Cost estimates show under which conditions these processes are economically attractive.

1. CFB Reaction System Biomass have become more and more interesting as a fuel or as a raw feed material for synthesis processes. To comply with clients’ requests and demands, LURGI decided to develop a wood gasification process considering that gasification offers most general utilization patterns (1). A gasification process working according to the Circulating Fluid Bed principle (CFB) promised to fulfill the following requirements: – handling a broad spectrum of biomass – allowing for a high throughput in the range of 10–100MW thermal – producing a synthesis gas feasible for routing it directly into LURGI methanol synthesis without further reforming – avoiding highly complex machinery. The CFB reactor may be placed in the transition range between the stationary bubbling bed with defined surface and the forced pneumatic transport reactor (Figure 1) (2). The CFB system is characterized by an almost uniform distribution of solids over the total reactor height with high amounts of solids recycled via the recycle cyclone making this a permanent constituent of the reactor system. The external circulation is accompanied by an inner recirculation of material due to constantly changing densly packed strands and clusters, causing particles to sink countercurrently to the upstreaming gas.

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Sponsored by EC, GD XII, and by BMFT of Germany

The CFB operates with optimum effect in the range of maximum possible slip velocity for the given particle spectrum. This creates extremely good heat and mass transfer which enables a rapid heating of the feed material, combined with an excellent reaction rate at constant temperature in the circulating fluidized bed system as a whole. LURGI’s experience with CFB goes back into the sixties, when this development started. Up to now, more than 35 industrial plants have been installed for different endothermic heterogeneous gas-solids reactions working according to the CFB principle. Furthermore, since mid 1982 one CFB combustion plant is in operation, three other plants are currently under construction. 2. Experimental program During several test runs totalling about 1 700 operating hours including two long runs of 100 h and very recently of 200 h, the feasibility of CFB-Biomass gasification was proven and a set of design data established. The gasification experiments have been conducted in LURGI’s two pilot plants in Frankfurt. The existing pilot plant with a thermal capacity of 0,5 MW could advantageously be used after some modifications to perform most of gasification tests. Additionally a long duration test with airblown wood gasification has been performed in LURGI’s 1,5 MW thermal pilot plant. Table I summarizes the parameters varied during these tests.

Table I Test parameters varied during CFB-pilottests Kind of wood

Beech-, Pine-, Poplar-, Spruce-Wood

Grain size 0–30 (70) mm Gasification agent Oxygen/steam, air Temperature 630–800°C Pressure Atmospheric Bed Material Wood-char, sand, Al2O3 Throughput Up to 250 kgdaf/h (in 0,5 MW plant)

The first column of Table II gives typical results of air blown gasification. The figures indicate a high efficiency of the CFB process and a gas suitable to be used as a fuel gas with a HHV of 5 800 kJ/m3n. When combusting the gas, the SO2 emissions are far below any level set by environmental protection rules. In contrast oxygen blown gasification produces a gas comprising high amounts of CO plus H2, a moderate amount of methane and C2–C3 hydrocarbons, indicating that this gas can be used,for example,for methanol synthesis. High values for cold gas efficiency and carbon conversion are common for both modes of operation. The low figures for H2S and CnHm and the fact that the gas is absolutely free of tar are beneficial for the further use of the raw gas.

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In addition to the evaluation of test results at optimum operating conditions, the influence of the most important parameters determining the gasification behaviour were studied as well.

Table II CFB Biomass Gasification Test results and extrapolated figures

TEMPERATURE °C PRESSURE BAR FEED MATERIAL H2 Vol% CO Vol% CO2 Vol% CH4 Vol% CnHm Vol% N2 Vol% H2S PPM RAW GAS m3n/kgdaf OXYGEN CONS. m3n/kgdaf AIR CONS. m3n/kgdaf COLD GASEFFICIENCY% CARBON CONVERSION%

AIR BLOWN OXYGEN BLOWN Pilot tests Calculated Pilot tests Calculated 750 750 750 800 ambient ambient ambient 30 beech any type beech any type 15,4 17,8 15,5 2,9 0,9 47,5 5 2,45

20,7 21,4 12,6 3,0 0,8 41,5 5 2,41

1,5 78 98

1,3 96

32,3 32,4 25,7 4,7 1.6 3,3 10 1,4 0,32

33,8 34,0 25,6 4,2 1.8 0,6 10 1.3 0,26

87 99

96

Temperature, moisture or steam addition and specific heat “losses of the plant were found to be of major influence. Type and size of the wood are rather less important. Heat losses are, of course, something very specific for the individual plant. However, since heat losses have a strong influence on raw gas composition, they had to be carefully examined for the sake of data extrapolation. Extrapolated data based on pilot test results are given also in Table II. Qualitatively, the test results can be summarized as follows: – Wood gasification in a CFB reactor is feasible. – High carbon conversion results in favourable specific consumption and production figures. – High specific throughput allows for high-capacity plants. – Small amount of methane makes gas suitable for direct routing into synthesis processes without previous or simultaneous reforming. – Tar-free gas indicates a high environmental acceptability of the CFB gasification process. – No inert bed material needs to be added.

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3. Commercial application With the comprehensive pilot tests presented above, a sound basis was attained for commercialisation of CFB Biomass gasification. Potential fields of commercial application of fuel gas is the direct heating of goods in kilns and the cogeneration of power and heat. Examples are lime kilns in pulp and paper industry, tunnel furnaces in brick industry, furnaces in glass industry, etc. Usually the sizes of such plants range from 10 MWth to 50 MWth, a size which fits the CFB-system ideally. If wood wastes are available, the fuel gas can advantageously be used to retrofit boilers, which are presently fueled with oil or natural gas. Fuel gas costs depending on wood price are shown in Figure 3 (3). A scheme of a fuel gas production plant (case A, figure 2) or for the cogeneration of power and heat (case B, figure 2) can be seen in Fi-gure 2. Based on German conditions, electric energy can be generated via a diesel engine at costs between 0.1–0.25 DM/kWh depending on the plant size and the price of wood. Whereas the fuel gas production plant is rather simple and straight forward in design, a synthesis plant requires more complex technologies (4, 5). However, all the additional process units are well known and commercially available. Moreover, in a test campaign for the Commission of the EC the synthesis of Methanol from Wood-gas, obtained and recovered during the tests described above, has been demonstrated in LURGI’s pilot facilities. Whereas in these tests a chemical grade methanol has been produced, it can be taken from the gas analysis, especially from the H2/CO-ratio, that the gas derived from wood is very well suited for the newly developed fuel methanol process (6). Here, no shift conversion is necessary anymore and the thermal efficiency is hence increased. Based on a price of 30 US dry wood, most evaluations taken from the literature lead to methanol production costs of 250–300 US (6, 7), applying the CFB gasification results in costs at the lower end of this range. Those production costs compare fairly well with data obtained on the basis of the gasification of cheap US Western coals. Literature 1) Mehrling, P.; Reimert, R.; VDI Annual Meeting, Munich 1984 2) Reh, L.; Erdöl Kohle Erdgas Petrochemie 32, (1979), 12, 560–566 3) Knoche, R.; Eckert, G.; Conference CTP Grenoble, 27.02.1985 4) Reimert, R.; Lindner, Chr.; Mehrling, P.; Bio Energy World Conf., Gothenborg 1984 5) Reimert, R.; ISPRA Course “Synthetic Fuels”, May 7th—11th 1984, Commission of the European Communities, Joint Research, Centre ISPRA, Italy 6) Supp, E.; AICHE Spring Meeting, Anaheim, May 1984

Fuel- and synthesis gas from biomass via gasification in the circulating fluid bed

Figure 1 Basic System for gas/solids reactors for fine grained solids

Figure 2 Block Flow Diagram of CFB gasifier to fuel production plant for direct combustion and power generation via diesel engine

1029

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Figure 3 Costs of fuel gas via CFBgasification depending on woodprice

METHANE FROM BIOMASS—PROCESS OPTIMISATION A V BRIDGWATER Chemical Engineering Department Aston University Birmingham B4 7ET D H SMITH John Brown Engineers and Constructors Ltd 20 Eastbourne Terrace London W2 6LE Summary A robust computer package has been produced to simulate all operations in a complete process to thermochemically convert biomass to methane and other products. The technique is modularised on a process step basis with mass and energy balances and cost estimates of all possible steps in a complete process starting with wood chips and ending with SNG. The paper presents details of the results for a representative base case that would apply in a European situation, together with a range of sensitivity analyses around this base cost to account for variations in process sequence, and process step performance.

INTRODUCTION The intensive activity in thermochemical biomass conversion around the world has led to substantial demonstration projects in many countries, including four in Europe. Almost all of the R&D effort has been devoted to the reaction system with little attention paid to its integration into a complete process, nor the trade-offs between different process sequences, nor any form of process optimisation. In order to provide an evaluatory methodology for examining thermo-chemical biomass processing systems, the first phase of a project to simulate all the possible steps in a complete process to thermochemically convert biomass to a range of useful products has just been completed (1). The resultant program is an integrated, and fully consistent computer package that permits detailed and comparative assessment of any process to produce a range of products (currently methane and methanol), from any biomass feedstock, and through any process configuration. The objectives of the project include: – Fully consistent and comparative mass and energy balances and cost estimates for all derived processes. – Identification of preferred reactor gas composition for any given product and sensitivity of product cost to gas composition (see(2)).

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– Forecast of likely production costs of a range of products from any proprietory reaction system. – Identification of minimum cost and maximum yield process sequences. – Detailed exmination of the trade-offs between different combinations of process steps. – Identification of sensitive steps in terms of product yield and cost. A description of how the program works and the extent of technical detail considered has already been published (2). This paper describes some of the early results and identifies the opportunities for both utilis ation of the package and further development. REFERENCE CASE STUDY A preliminary structured set of tests was applied to the total model. Cost and performance results for a reference case were first derived, then variations around this base case were examined. The reference case was defined as follows: –ZScale of operation

:300 dry tonnes/d

–Pressure of gasifier

:ambient

–Type of gasifier

:downdraft

–Gasification agent

:oxygen

–Moisture content of wood to gasifier

:20 per cent (dry wood basis)

–Cost of Raw Wood

:£20/t (dry wood basis)

–Product

:methane

–Sequence of steps

:see Figure 1

Figure 1 illustrates the chosen process sequence for the reference case, which is a battery limits plant with all utilities bought in at market prices. There are 116 items of input data required for the reference case, for some of which the user has to exercise judgement based upon knowledge of the processes involved. Default values are available. The variations examined were:– Scale of operation – Type of gasifier – Pressure of gasifier – Moisture content of wood entering gasifier – Cost of raw wood – Sequence of process steps There is both a very large number of combinations of variables as well as other variables which might be examined using the model. There has not yet been sufficient time for full testing, evaluation, and validation which is planned for phase 2.

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OUTPUT The output consists of the following: – Summary of input – Mass balance for each stream for each of the 22 components in mass and molar terms – Energy balance over each stream – Utility imports and exports for each utility in each step – Step-wise capital costs and labour requirements – Overall itemised operating costs and production cost – Products, performance and cost summary – Equipment listing To illustrate the detail of output available, Table 1 provides a range of summary results for the Reference Case. DISCUSSION AND CONCLUSIONS Lack of validation and testing inhibit drawing definitive conclusions at this stage of development, although the primary objective of constructing a working computer simulation of a biomass conversion process has been conclusively achieved. Some of the conclusions that can be drawn are: – The overall simulation model demonstrably works and gives results that, with only a few exceptions, are entirely plausible. Some results of the sensitivity analysis are shown in Figure 2. – The cost analysis of the base case shows that energy cost is apparently an unreasonably high proportion of total production cost. There is considerable scope for analysis, and particularly utilities and energy integration. Provision of in-plant utilities will give significant cost savings and improve overall energy efficiency. – The model is very flexible in permitting any scale of operation. In reality there are, in fact, constraints on size of equipment or process step. The constraints are more likely to have a significant effect on processes with low throughputs. Such limitations will need to be built into the model for more robust results to be produced from a wider scope. – The model is also flexible in permitting any sequence of process steps, although logical sequencing rules have not yet been formulated. Only one main process stream may be accommodated currently, with no side streams, byproducts or recycle: there is, however, no reason why any of these should not be incorporated into the model at a later stage of development. – The program structure has been designed to be readily extended in many directions including adding more steps, and providing alternatives to existing steps, as well as the other developments already described. Having demonstrated both the feasibility and opportunity of such a model there is considerable scope for extension.

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REFERENCES 1. John Brown Engineers & Constructors, “A Technical and Economic Optimisation Study of Wood Gasification and Conversion Processes”, Report to the Energy Technology Support Unit, UKAEA, October 1984. 2. Bridgwater, A V et al “Simulation of Complete Biomass Conversion Processes”, BioEnergy 84, Gothenberg, Sweden, June 1984.

ACKNOWLEDGEMENTS This paper is based on work carried out for the UK Department of Energy. The views expressed in this paper are the opinions of the authors and do not necessarily reflect the views of the Department.

Table 1 Summary Outputs for Reference Case Study A. Capital Cost, Utilities and Manpower Summary Process Step Installed £×103 cost % Utility £×103 cost/y % Labour men Reception Screening Drying Gasification Gas clean-up Compression Heat exchange H2S removal Heat exchange Compression Shift Heat exchange CO2 removal Heat exchange Methanation Heat exchange Compression Water treatment TOTALS

860 174 590 4217 648 975 25 13 27 5106 982 18 4118 119 619 23 181 903 19610

4.4 0.9 3.0 21.5 3.3 4.9 0.2 0.1 0.2 26.0 5.0 0.1 21.0 0.6 3.2 0.1 0.9 4.6 100

7 0* 260 850 40 60 440 0* 3 270 170 2 160 5800 5 4 2800 0* 10710

-* -* 2.4 7.8 -* -* 4.0 0 -* 2.5 1.5 -* 1.5 52.7 -* -* 25.5 -* 97.9

B. Utility Cost and Raw Material Cost Summary Utility £/y Raw Materials £/y. Cooling water 22 Dry wood Boiler feed water 33 Syngas Steam (L.P.) 160 D.E.A. Electricity 3100 Zinc oxide

2000 0 0* 95

5 0 4 4 4 4 0 4 0 4 4 0 4 0 4 0 4 0 45

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Air (dry oil-free) 2 Reformer catalyst 0 Oxygen 850 Shift catalyst 62 Fuel gas 6400 Methanol catalyst 0 Wood fines 140 TOTAL 2159 TOTAL 10707

C. Operating Costs Summary Direct Costs

£/y Indirect Costs

£/y

Raw materials and reagents 2160 Rates 390 Utilities 10710 Insurance 290 Labour (direct operating) 450 Overheads 210 Supervision 110 Research 1300 Payroll 280 Distribution and selling 1300 Maintenance 2000 Sub-Total 2 3490 Operating supplies 160 Laboratory 20 Royalty 200 Sub-Total 1 16390 Sub-total 1 brought forward 16390 TOTAL OPERATING COST (without contingency) 19880

D. Production Cost Summary Cost Element Capital Charges Raw Materials Utilities Labour and Related Cost Maintenance Other Costs TOTAL

Annual cost % of total (£x103/y) 3330 2160 10710 840 1960 3700 22700

14.7 9.5 47.2 3.7 8.6 16.3 100

E. Process Summary Wood feed 300 t/d (daf basis) Methane product 71.71 t/d (with CO, CO2, and H2O) Mass conversion efficiency to methane 0.24 Energy conversion efficiency (without utilities) 0.71 Energy conversion efficiency (with utilities) 0.39 Total operating cost £ 19 880 000/y Total capital cost (battery limits) £ 19 610 000 Total production cost £ 22 700 000/y Total methane production cost £ 960/t or £ 17/GJ

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FIGURE 1 REFERENCE CASE PROCESS SEQUENCE

FIGURE 2 METHANE COST Vs PRESSURE AND SCALE OF OPERATION

SENSITIVITY OF THEORETICAL GASIFIER PERFORMANCE TO SYSTEM PARAMETERS J M Double and A V Bridgwater Chemical Engineering Department, Aston University, Birmingham B4 7ET, UK Summary A robust equilibrium model of biomass gasification has been developed and subjected to a thorough sensitivity analysis across a wide range of parameters. Some of the significant results are graphically presented. The theoretical performance is compared with practical results so as to better understand the thermal processes involved; develop more robust predictive models; and hence construct reliable design models.

INTRODUCTION Despite extensive experience with many operating gasifiers, there is still poor understanding of the effect of changes in operating conditions on gasifier performance and product quality. A first step towards a better understanding is to examine a thermodynamic model of a gasifier assumed to operate with all products in thermodynamic equilibrium. The point at which solid carbon just disappears (i.e. the solid carbon boundary) represents the optimum operating point as in an ideal downdraft gasifier or ideal fluidised bed gasifier. Some attention has already been paid to deviations from ideality (1, 2), and further results from comparisons of ideal and real performance are included. THERMODYNAMIC MODEL A themodynamic model of a C—H—0 system may be constructed to represent three situations of declining carbon concentration in the gas phase (2): with solid carbon present as occurs in pyrolysis; the unique point at which the solid carbon just disappears; and with an excess of oxygen, which is the region in which most gasifiers operate with typically a 30–50% excess of oxygen over that required to operate on the solid carbon boundary. Generalised studies on the C—H—O system are restricted to ideal gas mixtures with families of curves at different temperatures and proportions of C, H and O (eg 3). A sensitivity analysis to explore the effects of changes in any operational parameter in a

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gasifier starts from the base case summarised in Table 1 with the variations in parameters studied. RESULTS Only a few results can be shown graphically. Figure 1 compares real and predicted ideal performance under identical conditions, while Figures 2–7 show some results of the sensitivity analysis with gas higher heating value, gasification temperature, and composition of outlet gas. The base case is marked on each curve by an “o”. The comprehensive results include the alternative base cases of air and oxygen gasification, with a selected range of the above parameter changes. Real processes will, of course, operate with many, if not all, of the variables deviating from ideality and the base case conditions, and this effect is shown in Figure 1. CONCLUSIONS These results, while purely theoretical, are a valuable aid in predicting trends in real systems under different conditions. A further application is in generating plausible predictive models of gasifier performance. REFERENCES 1. Belleville, P and Capart, R; in “Thermochemical Processing of Biomass” Edited by A V Bridgwater, Chapter 13. (Butterworth 1984). 2. Shand, R N, and Bridgwater, A V; Ibid. Chapter 14. 3. Baron, R E, Porter, S H and Hammond, O H. “Chemical Equilibria in C H O Systems”, MIT Press, 1976.

ACKNOWLEDGEMENT We are grateful to the Science and Engineering Research Council for their support of J M Double.

Table 1 Gasification Base Case and Variations for Sensitivity Analysis Parameter

Base Case

Biomass: feed C1.0 H1.5 °0.7 ash 1% daf moisture 25% daf Gasifying reagent: air ambient

Variations H:C ratio 1.0–2.0; 0:C ratio 0.5–1.0 0–50% 0–100% dry basis 10–100% mol O2; preheated 25°–500°C

Sensitivity of theoretical gasifier performance to system parameters

Oxygen H2O CO CO2 H2 CH4 Pressure Heat loss

1039

ambient O2 preheated 25°–500°C none steam(15 bar): air or O2 ratio 0–0.5 none 0–80% mol none 0–80% mol none 0–80% mol none 0–80% mol 1 bar abs. 1–30 bar abs. 5% HHV of feed 0%–20%

Figure 1 THEORETICAL GASIFIER PERFORNANCE AGAINST ACTUAL PERFORNANCE

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Figure 2 THEORETICAL GASIFIER PERFORMANCE AGAINST MOISTURE CONTENT OF BIOMASS AIR GASIFIER

Sensitivity of theoretical gasifier performance to system parameters

Figure 3 THEORETICAL GASIFIER PERFORMANCE AGAINST MOISTURE CONTENT OF BIOMASS OXYGEN GASIFER

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Figure 4 THEORETICAL GASIFIER PERFORMANCE AGAINST GASIFIER PRESSURE OXYGEN GASIFER

Sensitivity of theoretical gasifier performance to system parameters

Figure 5 THEORETICAL GASIFIER PERFORMANCE AGAINST GASIFYING OXYGEN MOLE FRACTION AIR GASIFIER

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Figure 6 THEORETICAL GASIFIER PERFORMANCE AGAINST GASIFYING AGENT CO MOLE FRACTION OXYGEN GASIFER

Sensitivity of theoretical gasifier performance to system parameters

Figure 7 THEORETICAL GASIFIER PERFORMANCE AGAINST INLET GAS STEAM MOLE FRACTION OXYGEN GASIFER

1045

WOOD LIQUEFACTION: TOTAL MASS AND ENERGY BALANCES X.DEGLISE, D.MASSON, H.KAFROUNI, A.LADOUSSE Laboratoire de Photochimie Appliquée, Université de Nancy I BP 239–54506 VANDOEUVRE Les Nancy Cedex—FRANCE Summary Beech wood is converted to an oil, water soluble products and gases if heated in the presence of water, alkaline catalyst and carbon monoxyde in a rocking batch reactor. The higher heat of combustion of oil increases with the reaction temperature but the highest oil yield (43%) and energy recovery in oil (63%) are obtained for the reaction temperatures around 300°C. If the reaction is carried without CO, the conversion and the oil yield are lowered of about 4% at all temperatures.

EXPERIMENTAL The wood liquefaction reaction was carried out in a 500 cm shaked batch autoclave. The reaction vessel is charged with 40 g of beech wood (moisture content 10%), 250g of water and 4g of catalyst (Na2CO3, 10 H2O). The reactor is flushed out and then pressurized with carbon monoxide to the selected starting pressure (0 to 10M Pa), after which it is heated to the desired temperature (230 to 340°C). The system is then held at this reaction temperature during 30mn. The autoclave is cooled to room temperature. The total amount of the gas resulting from the reaction is measured and then is analysed by gas phase chromatography. The aqueous phase is decanted and weighed. A part of organic products dissolved in this phase is extracted by dichloromethane. The oil phase adhers to the wall of the reactor and is recovered by dissolving in acetone. After solvent evaporation, oil is weighed, a part is used for carbon and hydrogen analysis and the higher heat of combustion is measured on an other part.

The residual solid phase is removed by filtration of the acetone dissolved oil phase and then washed with acetone and weighed. The relative conversion (%) is defined as:

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ROLE OF THE CO PRESSURE At a reaction temperature of 300°C, neither the conversion nor the oil yield are increased when the initial pressure of CO is higher than 1,5–2,0M Pa. (table 1). The CO pressure does not have any significant effect on the oil composition. For these reasons, all the experiments reported so far have been carried out at an initial CO pressure of 1,5M Pa. Figure 1 shows that the conversion and the oil yield are about 4% lower when the reaction is carried without CO. The presence of CO does not have a significant effect on the oil composition and highers heat of combustion.

Table 1: role of the CO pressure Initial pressure Conversion (%) Oil yield (%) Oil composition (M Pa) C% H% 0% 0 1.0 1.5 2.0 7.0 10.0

93 92 93 96 96 95

39 42 44 44 41 40

69.2 – 67.8 69.8 68.1 –

6,1 25 – – 6.3 24 6.3 23.9 6.2 23.5 – –

T=300°C

RESIDUAL SOLID PHASE The conversion increases with temperature to reach 95% at 270°C. Wood is almost completely transformed in oil, gas and water soluble products at a reaction temperature higher than 280°C (Figure 1). The composition and the higher heat of combustion of the residual solid produced at the lowest reaction temperatures (230 and 250°C) are close to these of wood. The higher heats of combustion of the solid residues obtained at reaction temperatures higher than 270°C change very few with temperature (table 2).

Table 2: residual solid phase T (°C)

230 250 270 280 290 300 320 330 340 350

C 46.2 49.1 67.6 70.0 70.0 70.2 73.6 72.3 73.2 73.7 mass % H 6.1 6.1 5.3 5.4 5.3 5.5 4.7 4.9 5.2 5.1 0 45.5 42.3 24.7 21.8 22.2 22.3 17.9 17.3 17.6 17.7 H.H.C. (kJ/g) 18.4 – – 30.0 30.0 30.2 30.3 30.3 30.0 30.3

OIL Figure 1 and table 4 show that the oil yield has its highest values (43%) for the reaction temperatures around 300°C. It decreases when the reaction temperature increases.

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Carbon and hydrogen contents of oil and consequently its higher heat of combustion increase with the reaction temperature (table 3)

Table 3: oil T (°C)

230 250 270 280 290 300 320 330 340 350 C 65.5 67.2 68.1 69.4 68.0 70.3 72.4 73.0 72.6 75.4

mass %

H 5.9 5.9 6.2 6.5 6.4 6.5 6.7 6.7 6.8 7.3 0 26.7 25.7 24.6 23.0 23.0 22.3 20.5 19.4 18.9 16.9 H.H.C. (kJ/g) 25.3 27.8 28.8 29.5 29.3 29.8 30.4 31.4 32.2 33.2

GAS PHASE The total mass of the gas phase increases with the reaction temperature (table 4). This mass augmentation proceeds mainly from the increase of the CO amount when the CO amount decreases (fig.2). AQUEOUS PHASE The mass of water and water soluble products does not change significantly with the reaction temperature (table 4). 30% of this phase are extracted with dichloromethane. The higher heat of combustion of the so obtainedproduct is 26 000kJ/kg.

Table 4: mass recovery T°C

mass (g) oil solid phase aqueous phase gas phase

270 14.7 2.6 13.1 300 15.0 2.0 12.5 340 11.6 1.7 13.8 initial mass: dry word: 36g, CO: 4,6g

10.2 11.1 13.5

ENERGY RECOVERY For a typical run, the higher heat of combustion of the reactant (36g of wood and 4,63g of CO) is 766kJ. After the liquefaction reaction, this energy is recovered in the heats of combustion of the reaction products and in the heat of reaction.

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Table 5: energy recovery Higher heat of combustion (kJ) QR T(°C) oil solid phase aqueous phase gas phase Σ (kJ) 280 290 300 320 340

454 451 447 416 376

54 76.5 60.5 54.5 51

200 188 221 209 209

20 26.5 25.5 24.5 30

728 38 742 24 754 12 704 62 666 100

Table 5 shows that the higher heat of combustion of oil decreases with the reaction temperature and represents 63% of the initial energy at 280°C and less than 50% at 340°C. The experimental determination of the aqueous phase combustion enthalpy is not very accurate (±10%) and then the calculated heats of reaction show only a slight exothermicity of the reaction around 300°C. CONCLUSION In our experimental conditions, the best oil yield and energy recovery in oil are obtained for a reaction temperature of 300°C. 44% of the initial wood mass are then converted into an oil whose highest heat of combustion is 30000kJ/kg and which contains 63% of the initial energy of the wood. When the reaction is carried without CO, these yields are lowered of about 4% but the oil caracteristics (composition and H.H.C.) are the same.

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Fig.1 Role of the reaction temperature on the oil yield and the conversion

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Fig.2 Role of the reaction temperature on the gas phase composition

STUDY OF THE DIRECT LIQUEFACTION OF WOOD IN THE PRESENCE OF IRON ADDITIVES C.BESTUE-LABAZUY, N.SOYER, C.BRUNEAU, A.BRAULT Laboratoire de Chimie Organique et de l’Environnement, Ecole Nationale Supérieure de Chimie de Rennes, Avenue du Général Leclerc, 35000 RENNESBEAULIEU—FRANCE, avec la collaboration des: – C.E.A. (C.E.N. Saclay, Dpt/SPIN, 91190 Gif-sur-Yvette, France) – CEMAGREF (Parc de Tourvoie, 92160 Antony, France) – TOTAL (C.F.P., 5, rue Michel Ange, 75016 Paris, France) Summary The catalytic activity of several iron additives was investigated during the liquefaction of poplar wood in water at 340°C. Among all the additives that were tested, iron powder exhibited a catalytic effect towards the production of oil. A systematic study of the influence of the initial pressure (in the range 1–40 bars) and the volumetric composition of the gas phase (hydrogen-helium mixtures) was also made. A mathematical model was established that pointed out the fact that only the initial pressure had an influence on the yield of oil and that the reaction of liquefaction was not favoured towards the yield of oil by the presence of initial hydrogen. So a yield of product soluble in acetone of about 45 % was obtained from a starting pressure of an inert gas (40–60 bars; helium) with a percentage of iron equal to 14wt% on dry wood. A stoichiometric equation for the liquefaction reaction is proposed which agrees with experimental results regardless of the initial gas composition.

1. INTRODUCTION La liquéfaction thermochimique du bois par des procédés utilisant des catalyseurs métalliques a déjà été développée et a conduit a des résultats encourageants (1)(2)(3). La recherche d’additifs métalliques moins onéreux nous a conduit à tester l’activité de plusieurs composes a base de fer. Pour une approche du mécanisme de la reaction de liquéfaction, l’étude de l’in-fluence de la pression initiale du gaz et de la nature de ce gaz, hydrogène ou gaz inerte, a été entreprise lors d’expériences réalisées dans l’eau a 340°C.

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2. PARTIE EXPERIMENTALE Dans une experience type, 70g de bois de peuplier (Robusta+I 222) sous forme de sciure séchée a l’air (~10% d’humidité), 300g d’eau et le catalyseur étaient mélangés puis introduits dans un réacteur de 1 litre. L’autoclave était pressurise a la pression requise d’hydrogène (1–63 bars). Les liquéfactions effectuées en l’absence d’hydrogène initial étaient réa-lisées sous pression initiale d’hélium; ce gaz inerte était choisi pour cette étude fondamentale, en raison de sa compatibilité avec le système chromatographique de détection des gaz et de son comportement thermique assez voisin de celui de l’hydrogène. La temperature était amenée a 340°C±5° en une période de 1,5h. Cette temperature était maintenue 30mn puis la temperature était abaissée rapidement par une circulation d’eau dans un réfri-gérant interne. Les gaz récupérés, essentiellement CO2, CH4, CO et H2, étaient analyses par chromatographie en phase gazeuse. L’huile formee était extraite de la phase aqueuse avec 1,2 L de CH2Cl2, les goudrons adhérant aux parois de l’autoclave étaient récupérés avec 0,8 L d’acétone, et les produits solubles dans la phase aqueuse étaient extraits en continu avec de l’éther éthylique. La distillation des solvants d’extraction conduisait, à partir de la fraction CH2Cl2, à une huile noire légèrement fluide a la temperature ordinaire (viscosité a 100°C: 10–25 cSt) et quasiment anhydre (<1%); la fraction acétone donnait des goudrons non fluides. Le solide récupéré par filtration (résidu ferreux+charbons) était analyse par dif- fraction de rayons X selon la méthode Debye-Scherrer. 3. RESULTATS ET DISCUSSION 3.1. Examen de plusieurs additifs a base de fer Plusieurs composes a base de fer (FeSO4, FeCl3, FeCl2,4H2O, Fe2O3, l’hydroxyde ferrique, Fe3O4, l’oxalate de fer et la poudre de fer) ont été testés comme catalyseurs dans des experiences de liquéfaction réalisées avec une pression initiale d’hydrogène de 63 bars. Les résultats (4) indiquent qu’un catalyseur est nécessaire pour obtenir des rendements en huile acceptables; sans additif, le rendement en huile n’est que de 17,6%. Parmi les composes testés, la poudre de fer (15g) donne les meilleurs rendements avec un taux de conversion supérieur a 96 % (Fe150µm (0,04m2/g): 38,5%; Fe10µm (0,3 m2/g): 34,8%). Aucune difference significative n’est apparue entre les comportements de ces deux qualités de fer (même utilisées en faibles quantités) ce qui écarterait l’hypothèse d’un effet catalytique de surface. 3.2. Influence de la pression initiale et de la fraction molaire d’hydrogène Après avoir remarqué que la quantité d’hydrogène récupéré après les liquéfactions réalisées en presence de poudre de fer était supérieure ou égale a celle fournie au départ de la reaction, des experiences sous pression initiale de gaz inerte ont été envisagées. Elles ont été réalisées selon un plan factoriel d’essais comprenant deux variables: la pression initiale et la fraction molaire d’hydrogène (dans des mélanges hydrogène-

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hélium), dans les domaines respectifs de 1–40 bars et 0–1, et avec 15g de poudre de fer (150µm). Le facteur de réponse mesuré expérimentalement était le pourcentage d’huile [(g d’huile soluble dans CH2Cl2/g bois anhydre× 100)]. La deviation standard pour le facteur de réponse, calculée a partir des experiences réalisées aux points moyens (pression initiale: 20,5 bars et fraction molaire d’hydrogène: 0,5) était de 1,3 %. Les résultats de 11 experiences ont permis d’établir un modèle mathématique valide. Le calcul sur ordinateur des différents coefficients a conduit a l’équation quadrati que: Rendement en huile%=30,7–1,8 PO–2,5 XH+0,77 PO2+3,95 X2H P: Pression initiale; XH: fraction molaire d’hydrogène. Aucune interaction significative n’était trouvée entre les deux paramètres. Compte tenu du taux de reproductibilité du rendement en huile, il ressort que, dans le domaine étudié, ce rendement est peu influence par la fraction molaire d’hydrogène, mais qu’il est par contre favorisé par une forte pression initiale. Des experiences réalisées avec une pression initiale de 63 bars, c’est–à–dire une pression supérieure à celles du domaine choisi pour le plan factoriel, conduisent en presence ou en l’absence d’hydrogène initial, à des rendements en huile du même ordre de grandeur que ceux obtenus a 40 bars. Il apparaît donc que la reaction de liquéfaction n’est pas défa-vorisée vis–à–vis du rendement en huile par l’absence d’hydrogène initial, et que dans nos conditions, les meilleurs rendements sont obtenus pour des pressions comprises entre 40 et 60 bars. C’est aussi pour ces mêmes pressions que les rendements en goudron sont les plus faibles. 3.3. Rôle du fer Si la quantité de fer est comprise entre 5 et 15g, le pourcentage total des produits solubles dans l’acétone (huile+goudrons) demeure pratiquement constant et égal a 44,5±1,5% quel que soit le gaz initial (Figure I) . Cependant la qualité des produits obtenus varie, dans la mesure où le pourcentage d’huile diminue en même temps que la quantité de fer, et ceci plus rapidement pour les reactions effectuées en presence de gaz inerte. Si la quantité de fer est fortement augmentée (20g) alors le rendement en huile atteint 40%, et celui des produits solubles dans l’acétone (huile+goudrons) est égal a 48,7%. Pour les experiences correspondant a la Figure I, le fer a toujours été récupéré sous forme de Fe3O4 avec seulement des traces de fer. Un recyclage de ce résidu a confirmé le fait que sous forme oxydée Fe3O4, le pouvoir catalytique n’existe plus. C’est au début de la reaction de liquéfac-tion, avant 300°C, que doit s’exercer l’activité catalytique du fer. En effet une experience arrêtée a 275°C, pendant la période de chauffage, a fourni un melange de fer métallique et de Fe3O4, par contre a 300°C c’est presque essentiellement du Fe3O4 qui a été recuoéré. En l’absence de bois, dans nos conditions expérimentales, le fer n’était pas modifié et aucune trace d’hydrogène n’était détectée. On peut faire l’hypothèse que cette oxydation en Fe3O4, au cours de la liquéfaction du bois, serait le résultat de reactions du fer avec des radicaux oxygénés très réactifs provenant de la pyrolyse du bois, qui en l’absence de fer, conduiraient a des goudrons par des reactions de condensations et de polymerisation.

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Figure I: Influence de la quantité de fer sur les rendements en huile et en (huile +goudron). (Po=63 bars, ▲H2, oHe; bois: 70 g; H2O: 300g; 30 mn a 340°C). 3.4. Equation stoechiométrique Il a été remarqué que les formules chimiques des huiles obtenues a partir des experiences se rapportant a la Figure I étaient toujours voisines, comme l’étaient aussi celles des goudrons et celles des produits extraits de la phase aqueuse. Les quantités respectives de produits de la phase aqueuse, de dioxyde de carbone, d’hydrogène et d’eau étant pratiquement constantes pour toutes les reactions, une equation stoechiométrique unique pouvait être proposée. Elle permet de rendre compte a la fois des experiences effectuées avec une pression initiale d’hydrogène et une quantité de fer ≥5g, etde cellesréalisées en partant d’une pression initiale d’hélium avec une quantité de fer ≥9g, qui doivent se dérouler selon des mécanis-mes réactionnels voisins:

α=masse de fer/55,85; X varie entre 1,25 et 1,47 et Y entre 0,47 et 0,17.

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Dans cette equation ont été négligées la masse de résidu charbonneux (~2g) ainsi que les contributions en C, H et O des produits non extraits de la phase aqueuse et celle du methane (~0,1g) et du monoxyde de carbone (~0,5g). 4. CONCLUSION Cette étude exploratoire fondamentale montre que la poudre de fer favorise la formation d’huile lors de reactions d’hydropyrolyse du bois a 340°C. L’équation stoechiométrique proposée pour les experiences effectuées indique que le mécanisme réactionnel doit comprendre avant tout une destruction thermique du bois avec production de CO2 et d’eau dont les quantités demeurent constantes quelles que soient la nature du gaz initial et la quantité de fer. Le presence d’hydrogène initial n’est pas nécessaire, des rendements en huile identiques sont obtenus en operant avec une pression initiale de gaz inerte. Dans nos conditions opératoires, les meilleurs rendements en huile sont obtenus avec une pression initiale comprise entre 40 et 60 bars et un pourcentage de fer au moins égal a 14% par rapport au bois anhydre. L’analyse chimique des huiles est en cours d’étude; la composition de la fraction analysable par chromatographie en phase gazeuse est identique a celle obtenue en utilisant le nickel de Raney comme catalyseur (5). 5. REFERENCES (1) BOOCOCK, D.G.B., MACKAY, D. and LEE P. (1982) Wood Liquefaction: Extended Batch Reactions Using Raney Nickel Catalyst. The Canadian Journal of Chemical Engineering. Vol. 60, p. 802–808. (2) FREDON, C., SOYER, N., BRUNEAU, C. and BRAULT, A. (1983). Chemical Study of the Thermal and Catalytic Liquefaction of Poplar Wood, in Energy from Biomass, 2nd E.C. Conference, STRUB, A., CHARTIER, P. and SCHLESSER, G. Eds., Applied Science Publishers, p. 930–934. (3) BURTON, A., de ZUTTER, D., GRANGE, P., PONCELET, G. and DELMON, B. (1983). Catalytic Liquefaction of Wood Material, in Energy from Biomass, 2nd E.C. Conference, STRUB, A., CHARTIER, P. and SCHLESSER, G. Eds, Applied Science Publishers Ltd., p. 935–939. (4) BESTUE-LABAZUY, C. (1984). Liquéfaction directe du bois de peuplier en presence de fer finement divisé. These Université de Rennes I,n° 47. (5) SOYER, N., FREDON, C., BRUNEAU, C. and BRAULT, A. (1983). Chemical Study of the Oils of Liquefaction of Poplar Wood, in Comptes Rendus de l’Atelier de Travail sur la Liquéfaction de la Biomasse, Sherbrooke, Canada, Septembre 29–30, 1983, NRCC 23 130 National Research Council of Canada, Ottawa, p. 184–190.

REMERCIEMENTS: Nous remercions le Prof. M. MAUNAYE (E.N.S.C. Rennes) pour sa précieuse assistance apportée dans l’analyse des résidus ferreux par diffractométrie R.X.

DIRECT THERMOCHEMICAL LIQUEFACTION OF PLANT BIOMASS USING HYDROGENATING CONDITIONS D.MEIER, D.R.LARIMER and O.FAIX Federal Research Center for Forestry and Forest Products, Institute of Wood Chemistry and Chemical Technology of Wood Summary The direct liquefaction by means of catalytic hydrogenation has been investigated using different lignocellulosic feedstocks as well as their constituents: holocellulose, cellulose and lignin. The following input materials were converted to an oil using palladium as catalyst: spruce and birch wood, spruce and birch holocellulose, cellulose, pine bark spruce and bagasse organosolv lignins, and birch Willstätter lignin. The liquid products were separated into water, acetone- and dichloromethane soluble (oil) fractions. The oils obtained were characterized and separated into neutral, weakly and strongly acidic fractions. The calorific values were calculated from the results of the C/H-analysis.

1. INTRODUCTION The direct conversion of lignocellulosic materials into liquid organic products is one of the alternatives to make use of renewable raw materials. The oil produced could serve as a source for chemical feedstocks or as a fuel. Principally there exist two routes for the direct conversion which have been mainly investigated. Based on the early studies by Appell (1) several groups have treated lignocellulosic feedstocks with aqueous alkaline solutions using pressurized carbon monoxide at temperatures around 350 C (2–4). Other experiments were carried out with pressurized hydrogen and transition metal catalysts in the presence of aqueous and non aqueous mediums at similar temperatures (5, 6). Wood has been mainly used as input materials for the conversion processes. Little is known about the lique-faction of annual plants and the components of the lignocellulosic material: carbohydrates and lignin. Therefore, in this study the liquefaction of different biomass feedstocks and constituent components was systematically researched to get more information about the behaviour of plant biomass during liquefaction. 2. EXPERIMENTAL WORK A wide variaty of biomass types was selected for our experiments: spruce wood (Picea abies L.Karst), birch wood (Betula spp.), bagasse from sugar cane (Saccharum officinarum L.), barley straw (Aordeum vulgare L.), pine bark (Pinus sylvestris L.), cellulose (MN 300 HR MachereyNagel), isolated holocellulose from spruce and birch, isolated organosolv lignins from spruce and sugar cane bagasse, and isolated Willstätter

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lignin from birch. All of the biomass samples were ground to particle sizes from 0.1 to 0.5mm and then mixed with water to form aqueous slurries. After adding the catalyst (1% Pd based on o.d.wood) the slurry was filled into 25ml stainless steel autoclaves and an initial hydrogen pressure of 6C bar was established. After reaching the maximum reaction temperature of 375 C within 15 minutes the reaction was immediately stopped by quenching the autoclaves under running water. The liquid products were separated into water, acetone- and dichloromethane soluble (oil) fractions. The results are presented in Table I. Additionally the oils were fractionated into neutral, weakly and strongly acidic fractions. The liquid-liquid extraction procedure used for this analytical step is illustrated by Figure I, and yields on each fraction are shown in Table II. Furthermore, the elemental composition was determined of the starting materials and of the product oils on a Carlo Erba 1104 elemental analyser. The results are presented in Table III. 3. RESULTS AND DISCUSSION As Table I shows the highest oil yields were obtained from spruce and bagasse organosolv lignins (64,0% and 60.7%, respectively). In comparison to the condensed Willstätter lignin, which yielded only 33% of an oil, the high oil yield of the organosolv lignins can be attributed to their low molecular weight and better solubility. Oil yields of the carbohydrate feedstocks were obtained in the range of 29 to 31%, whereas the wood materials yielded 46% (spruce) and 41% (birch) of an oil. The higher lignin content in the softwood seems to be responsable for the higher oil yield. The annual plants yielded 41% oil, while pine bark yielded only 20,7% of an oil indicating that this feedstock is an unsuitable material for liquefaction under the conditions applied. As Table I shows, the acetone fractions originate predominately from lignin degradation products. The water soluble products, on the other hand, are formed to a large extent out of carbohydrate degradation products. The amount of solid residue formed was for most of the feedstocks very low. The high yield of charred residue from pine bark corroborates that this feedstock is not suitable for liquefaction. The results of the liquid-liquid extraction of the oils, presented in Table II, demonstrate that the bulk of the extractable compounds have a weakly acidic and neutral character. As was expected weakly acids (phenols) are derived from lignin. The strong acid fraction is formed to a large extent from degradation products of carbohydrates. Although the yield balance is negative this extraction method is convenient for the characterization of oils from different feedstocks or processes. As can be seen from Table III the oils produced have much higher heating values than their corresponding feedstocks. Since the calorific value of the lignin oils does not increase significantly it seems not recommendable to liquefy lignin for energetic purposes. Furthermore, the total energy balance is negative in spite of the very favorable increase in heating values of the oils in comparison to their starting materials.

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ACKNOWLEDGEMENT This work was financially supported by the Federal Ministry for Food, Agriculture and Forestry, project number 81 NR 006. REFERENCES (1) APPELL, H.R., FU, Y.C., FRIEDMAN, S., YAVORSKY, P.M. and WENDER, I. (1971). Converting organic wastes to oil, a replishable energy source. US Bureau of Mines, RI 7560. (2) DAVIS, H.G. (1983). Direct liquefaction of biomass, final report and summary of effort 1977– 1983. Lawrence Berkeley Laboratory, LBL16243. (3) SCHALEGER, L.L., FIGUEROA, C. and DAVIS, H.G. (1982). Directlique-faction of biomass.Biotech. and Bioeng. Symp. 10,3. (4) EAGER, R.L., MATHEWS, J.F. and PEPPER, J.M. (1982) Liquefaction of aspen poplar wood. Can.J.Chem.Eng.60,289. (5) KRANICH, W.C. and WEISS, A.H. (1980). Oil and gas from cellulose by catalytic hydrogenation. Can.J.Chem.Eng.58,735. (6) FREDON, C., SOYER, N., BRUNEAU, C. and BRAULT, A. (1983). Chemical study of the thermal and catalytic liquefaction of poplar wood. Proc. 2nd Internat.Conf. on Energy from Biomass, Apl. Sci. Publ. Ltd. London-New York, 930.

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Figure I Liquid-liquid extraction scheme for products oils Feedstock

Oil (%)*

Acetone soluble (%)*

I Spruce wood Birch wood

46,0 41,0

II

Watersoluble Σ (%)*. non volatile III+IV volatile III

4, 1,5

IV 12,5 10,5

2,2 7,0

Solids (%)*

Σ I–V

V 14,7 17.5

1,4 0,9

66,6 60,9

Direct thermochemical liquefaction of plant biomass using hydrogenating conditions

Sugar cane bagasse Barley straw Pine bark Cellulose Spruce holocellulose Birch holocellulose Spruce organosolv lignin Bagasse organosolv lignin Birch Willstätter lignin

1061

41,5 40,3 20,7 29,3 31,0 31,0 64,0

4,0 2,7 17,7 3,7 10,5 1,0 29,3

14,5 15,7 5,7 11,3 13,0 13,5 2,0

4,9 4,4 1,7 1,8 3,2 6,8 1,0

19,4 20,1 7,4 13,1 16,2 20.3 3,0

4,2 0,7 29,9 1,5 0,5 0,8 6,8

69,1 63,8 75,7 47,6 58,2 52,2 103,1

67,7

31,0

4,3

0,8

5,1

3,1

99,9

33,0

50,7

5,0

0,8

5,8

4,1

93,6

Table I Percentage yield of liquefaction products * based upon dry feedstock + titrated and calculated as acetic acid Feedstock

Spruce wood Birch wood Sugar cane bagasse Barley straw Pine bark Cellulose Spruce holocellulose Birch holocellulose Spruce organosolv lignin Bagasse organosolv lignin Birch willstätter lignin

Weak acids Neutrals Strong acids (NaOH(NaOHsolubl) solubl.) (%) S=1,7 (%) (%) S: 1,4 S=3,8 I II II

Σ I– Precipitate Σ I–IV III (%) S: 5,3 (%)S: 8,1 IV

27,5 24,5 19,5 17,7 24,3 11,3 19,0 16,0 41,0

18,5 28,0 30,5 33,7 18,0 28,0 28,5 27,5 14,7

8,5 7,5 8,5 8,0 13,0 15,0 18,0 13,0 5,3

54,5 60,0 58,5 59,4 55,3 54,3 65,5 56,5 61,0

24,0 22,5 22,5 19,7 32,7 12,0 6,0 12,0 20,3

78,5 82,5 81,0 79,1 88,0 66,3 71,5 68,5 81,3

32,7

14,3

8,3

55,3

13,3

68,6

27,0

11,5

10,5

49,0

18,5

67,5

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Table II Percentage yield of “liquid-liquid extraction produc based upon feedstock oil Feedstock

Feedstock Oi1 calorific value of the oils C H O C H O Feedstock oil % % % % % % (MJ/kg)

Spruce wood 49,9 6,2 43,9 73,1 6,7 20,2 Birch wood 48,0 6,1 45,9 71,9 6,7 21,4 Sugar cane bagasse 45,5 5,8 48,7 72,1 7,3 20,6 Barley straw 46,7 5,9 47,4 72,7 7,0 20,3 Pine bark 55,9 5,5 38,6 71,0 7,2 21,8 Cellulose 43,7 6,4 49,9 75,9 6,7 17,4 Spruce holocellulose 47,1 6,0 46,9 67,7 7,0 25,3 Brich holocellulose 45,4 6,0 48,6 73,5 7,6 18,9 Spurce organosolv lignin 66,7 5,9 27,4 69,8 6,0 24,2 Bagasse organosolv lignin 64,8 5,7 29,5 66,2 6,1 27,7 Birch Willstätter lignin 61,3 5,8 32,9 66,0 6,3 27,7

18,0 16,9 15,1 15,9 20,8 15,1 16,2 15,3 26,2 24,9 23,3

30,8 30,2 31,3 31,1 30,5 32,3 28,5 32,5 28,0 26,3 26,5

Table III Elemental composition and calorific value of feedstocks

LE PRETRAITEMENT, L’HYDROLYSE, LA PYROLYSE ET LA LIQUÉFACTION DE LA BIOMASSE; VERS UNE APPROCHE UNIFIEE par Ralph P.Overend Conseil National de Recherches Ottawa, Canada, KlA OR6 et Esteban Chornet Université de Sherbrooke Sherbrooke, Qué., Canada, JlK 2R1 Summary Historically, liquefaction approaches have tried to transform lignocellulosics into organic liquids via integral routes. The net result is the non-selective solubilization of the different macromolecular compounds initially present. The products thus obtained are of little value as fuels and require extensive deoxygenation. Moreover, the rheological constraints inherent to the continuous processing of lignocellulosic are seldom considered in the integral routes when studied at the laboratory level. Recent advances in the knowledge of ultrastructure and macromolecular degradation of the polymeric constituents of biomass permit to envisage a sequential approach by means of which defibration and defibrillation precede the necessary depolymerization to achieve solubilization. By proper choice of temperatures, solvents, and mechanochemical effects, the fractionation of lignocellulosics can be achieved and a de-facto selective separation of polymeric families is then possible. This paper presents the arguments in favor of a sequential approach to liquefaction and tries to unify the pretreatment with subsequent thermal decomposition and acid-base (hydrolysis) steps which are closely related to liquefaction.

1. INTRODUCTION La valorisation de la biomasse par voie de sa conversion en produits liquides susceptibles d’être utilisés soit comme combustibles ou carburants de substitution, soit comme produits chimiques particuliers est connue sous le nom générique de liquéfaction.

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Dans les schémas classiques la liquéfaction est conçue comme la transformation thermochimique de la biomasse en présence d’un solvant aqueux ou organique. Le concept traditionnel peut être résumé comme suit:

Il est à noter que ce schéma a été appliqué depuis plusieurs années sans tenir compte de deux caractéristiques essentielles de la biomasse: son “ultrastructure” et sa “nature polymérique identifiable”. L’importance de ces deux caractéristiques de la biomasse est capitale aussi bien en ce qui concerne les aspects relies au génie de procédés (i.e. propriétés de transfert) que pour un choix des approches thermo-chimiques a adopter visant l’obtention de produits chimiques valorisables. 2. ÉTAPES LORS DE LA LIQUÉFACTION Les étapes suivantes sont présentes lors de la liquéfaction: (i) Désaggrégation structurelle→défibration Cette étape consiste essentiellement en la destruction de la lamella intermédiaire et la libération des cellules (i.e. fibres) résul-tantes. La lignine et les hemicelluloses composant la lamella sont ainsi solubilisées. (ii) Défibrillation La paroi primaire et les parois secondaires sont altérées par action thermomécano-chimique ce qui permet l’ouverture du réseau microfibrilaire qui enferme les macromolécules cellulosiques. Lors de cette action, les hemicelluloses présentés entre les espaces fibrillaires sont solubilisées même a des temperatures relativement faibles (~180–220°C) (iii) Dépolymérisation Les différentes macromolécules constitutives sont dépolymérisées par actions thermique, chimique ou mécano-chimique. Il est a noter que le “contrôle” de ces dépolymérisations est crucial pour obtenir une distribution voulue ou adequate des produits. Lors de la dépo-lymérisation, une solubilisation accrue accomplie. (iv) Déoxygénation En augmentant la temperature du traitement ou par action catalytique la déoxygénation des produits dépolymérisés est progressivement accomplie. C’est ainsi que la décarboxylation et la déshydration sont observées. Par action hydrogénante ultérieure, les composants oxygénés résultants lors de la solubilation (alcools, aldehydes, cétones, etc.) peuvent être progressivement réduits a un coût toutefois élevé en hydrogène compte tenu des exigences stoechiomé-triques.

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Les étapes (i) et (ii) constituent le prétraitement et sont importantes dans les domaines biotechnologiques car elles permettent une accessibilité accrue aux enzymes lors de la désaggrégation de l’ultrastructure cellulosique. L’étape dépolymérisante peut être accomplie par action thermique (i.e. pyrolyse), par action thermo-chimique (i.e. hydrolyse ou solvolyse catalytique) ou par action thermomécano-chimique (i.e. en présence de régimes fluidodynamiques appropriés). Le problème essentiel de toute liquéfaction est que les familles polymériques constituantes majeures de la biomasse (i.e. les hemicelluloses, la lignine et la cellulose) ont des réactivités différentes (voir Tableau ci-dessous) lors des étapes (iii) et (iv) et le contrô1e de la réactivité et surtout de la sélectivité lors de leur transformations représente un défi considérable si la solubilisation des trois familles est voulue dans une seule étape de liquéfaction intégrale. Le Tableau ci-joint présente un sommaire des conditions réactionnel-les type associées à la liquéfaction. Composant Pyrolyse Hydrolyse OrganoDeHydrogénation Hydrocrackage des des structures (OH−) (H+) solvolyse oxygénation (Neutre Thermique monomères condensées ou H+) Hemicel luloses Cellulose Lignine

≤160°C rapide rapide facile

facile (CO2↑) 150–200°C

>350°C

<260°C lente

difficile (−H2O) difficile (−OMe)

150–200°C

>350°C

180–350°C

>350°C

lente très difficile <320°C rapide lente difficile

3. PRODUITS DE LIQUÉFACTION Des multiples travaux de caractérisation ont eu lieu traitant soit de produits de liquéfaction par pyrolyse ou par action solvolytique (ou hydrolytique) en présence ou non de catalyseurs. Deux phases liquides sont a considérer: – une phase aqueuse, provenant des reactions de déshydratation et riche en composants oxygénés de faible poids moléculaire (acides, aldehydes et alcools derives essentiellement des fractions hydrates de carbone) – une phase organique, les huiles, fortement aromatique et qui dans le cas de liquéfaction intégrale par voie solvolytique présente la composition suivante (Elliott et Davis): 0–6%

hydrocarbures saturés

1–20%

hydrocarbures aromatiques polaires

5–45%

monophenols

5–55%

phénols substitués

5–35%

polyphenols

1–3%

inconnus hautement oxygénés

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inconnus de poids moléculaire élevé

Les produits organiques solubles dans la phase aqueuse représentent 15 à 25% de la biomasse anhydre initiale alors que la phase organique (i.e., les huiles) peut varier entre 30 et 60% de la biomasse anhydre initiale dépendant du degré de dé-oxygénation voulu. 4. PERSPECTIVES DU MARCHÉ ÉNERGÉTIQUE POUR LES PRODUITS DE LIQUÉFACTION Sur une base de contenu énergétique équivalent, les produits issus de la liquéfaction et susceptibles d’être utilises comme combustible (i.e. les huiles) ont un coût de production qui, en moyenne, représente deux fois le prix du brut pétrolier (en $ fin 1984). Aussi, et sur une base de composition chimique, les produits de liquéfaction sont excessivement phénoliques et trop fortement oxygénés pour être considéres comme possible substituts aux gasolines ou aux carburants diesel actuels. Un raffinage coûteux, et encore a être quantitativement prouvé, devra être mis au point avant de pouvoir considérer les produits de liquéfaction raffinés comme possibles substituts aux carburants dérivés du pétrole. 5. STRATÉGIE ALTERNATIVE Compte tenu des contraintes imposées par la constitution même de la biomasse une alternative de valorisation doit être développée en partant de la reconnaissance des contraintes ultrastructurelles ainsi que de la nature polymérique des constituants majeurs. Cette constatation nous amène a considérer une approche séquentielle visant la séparation des familles macromoléculaires constituantes afin de minimiser la sévérité des procédés de conversion ainsi que maximiser la valeur ajoutée des produits issus de chaque étage de fractionnement. Une approche unifiée peut être envisagée ainsi:

REMERCIEMENTS Les auteurs sont reconnaissants au CRSNG, CNRC, EMR-Ottawa, MER–Québec et le programme FCAR pour des subventions concernant les projets liquéfaction.

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REFERENCES (1) CHORNET, E. et OVEREND, R.P. (1985). “Biomass Liquefaction: An Overview” dans Fundamentals of Thermochemical Biomass Conversion, Elsevier, 967–1002. (2) YOUNG, R.A. et Davis, J.L. (1985). “Thermochemical Fractionation and Liquefaction of Wood” dans Fundamentals of Thermochemical Biomass Conversion, Elsevier 121–142. (3) CHORNET, E. et OVEREND, R.P. (1985). “Biomass Liquefaction: Prospects and Problems” dans Proc. Bioenergy 1984, Goteborg, Sweden, in press. (4) ELLIOTT, D.C. (1985). “Analysis and Comparison of Products from Wood Liquefaction” dans Fundamentals of Thermochemical Biomass Conversion, Elsevier, 1003–1018. (5) DAVIS, H.G. (1983). “Direct Liquefaction of Biomass”, Report LBL No. 16243, Final Report and Summary, prepared for US-DOE, Contract No. DE-ACO3–76SF00098, 82 pages.

A TECHNO-ECONOMIC COMPARISON OF BIOMASS THERMOCHEMICAL LIQUEFACTION PROCESSES Y.SOLANTAUSTA and P.J.McKEOUGH Technical Research Centre of Finland 02150 Espoo Summary A techno-economic comparison of thermochemical processes for producing both fuel oil and gasoline substitutes from biomass is presented. Direct liquefaction processes (high-pressure hydrogenation, pyrolysis), which are at an early stage of development, seem to be competitive with the more established processes (indirect liquefaction involving gasification). Direct processes have higher thermal efficiencies and they may be more adaptable to small scale production. At present the products of these processes can not, however, compete economically with conventional liquid fuels.

1. INTRODUCTION Liquid fuels can be produced from biomass by various thermochemical methods. Processes based on these methods are at different stages of development. Some of the processes are at a rather advanced level of development (indirect liquefaction involving gasification) whereas others are only at the bench scale level (most of the high-pressure hydrogenation and pyrolysis processes). In this study, techno-economic assessments of the various processes have been carried out. Process concepts, based on the available experimental data, were first compiled. Then the material and energy flows of a 1000dry t/d plant were calculated, followed by equipment sizing, investment cost estimation, and comparison of the production costs of the liquid fuels. Also a technical comparison of the processes was made. This type of study can be used not only to compare the relative merits of different processes under development, but also to focus future research onto the most important problems. 2. PROCESSES EVALUATED The comparison of the processes was primarily done on the basis of the equivalent fuel oil production costs. This does not mean that fuel oils are the desired end products, but rather emphasizes the fact no other proper way of comparison was available. Not a lot is known about the upgrading of the primary oils.

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A total of 9 processes were evaluated, six producing fuel oil substitutes (primary oils, methanol) from both peat and wood, and three producing gasoline from wood. Note that the data base available for the evaluation of the gasoline processes was very limited. Production of primary liquids Wood feed 1. PERC/W. High-pressure hydrogenation in recycle oil (wood as feedstock), based on the process originally developed at the Pittsburg Energy Technology Centre (PERC), USA. 2. FLASH/W. Flash pyrolysis of wood based on the process being developed at the University of Waterloo, Canada. 3. MEOH/W. Pressurized fluidized bed gasification of wood, methanol synthesis. Peat feed 4. H-PEAT/P. High-pressure hydrogenation in recycle oil (peat as feedstock), based on the concept evaluated at VTT, Finland. 5. FLASH/P. Similar to concept 2, but employing peat as feedstock. 6. MEOH/P. Similar to concept 3, but employing peat as feedstock. Production of gasoline from wood 7. PERC/G. Catalytic hydrogenation of the primary oil produced by concept 1. 8. FLASH/G. Catalytic hydrogenation of the primary oil produced by concept 2. 9. MTG/G. Catalytic conversion of methanol to gasoline according to the process developed by Mobil. Simplified block flow diagrams of concepts 1–6 are presented in figures 1–3. Full details of the designs are provided in references (1) and (2). Table I summarizes the main material flows of the processes. In order to compare the different primary products they were first classified into one of the grades of fuel oil defined by ASTM (3). Then on the basis of their energy contents and the corresponding fuel oil prices their values were determined. Most of the data required for calculating the material flows was obtained from laboratory scale experiments. However, for some cases (PERC, MEOH, MTG) data from larger experimental units (PDU, pilot) was available. 3. COMPARISON OF THE PROCESSES, PRIMARY LIQUID FUELS The overall thermal efficiencies of “the processes are presented in table I. The highest efficiencies can be obtained with the high-pressure hydrogenation processes, PERC and H-Peat, 70% and 60% respectively. Also wood pyrolysis yields a higher efficiency than indirect liquefaction (60% compared to 50%). Total capital requirements for the process concepts presented range from 60–106 USD to more than 200–106 USD, the lowest for flash pyrolysis and the highest for H-Peat (table II). For a plant processing biomass a low capital requirement is a distinct advantage because of the widespread nature of biomass resources and their low energy density.

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The lowest primary liquid production cost can be obtained with the flash pyrolysis processes. The cost-value ratio of the products (production cost divided by equivalent fuel oil value) is around 1,5 for these processes, and approaches 1,0 at low raw material prices (fig. 4). 4. GASOLINE PRODUCTION FROM WOOD (fig. 5) An attempt was also made to compare processes producing gasoline from wood. It should be noted, however, that less is known about the upgrading of the primary oils from pyrolysis and hydrogenation (direct liquefaction) compared to methanol conversion to gasoline (MTG-process). It appears that higher efficiencies can be obtained with the direct processes (table III). Also the gasoline production costs appear to be lower for these processes. It should be noted that a slight decrease in the cost-value ratio occurred when the upgrading step was added to the PERC process (from 2.1 to 2.0), whereas for the flash pyrolysis process the ratio increased (from 1.6 to 2.2). Thus in the latter case the further upgrading step actually decreased the competitiveness of the process. All the options appear to be uneconomic at the present time (but insufficient data precludes any firm conclusions being drawn). 5. CONCLUSIONS It appears that both higher thermal efficiencies and lower liquid fuel production costs can be obtained with flash pyrolysis and highpressure hydrogenation processes than with the more established indirect liquefaction processes involving gasification. More research is required to exploit the potential for improvement offered by the newer processes. 6. ACKNOWLEDGEMENTS This study is in part based on results obtained in an international co-operative project organized by the International Energy Agency. The sponsors of this project were National Research Council of Canada, Ministry of Trade and Industry, Energy Department (Finland), National Energy Administration (Sweden) and Department of Energy (USA). The rest of the study is part of a separate research project financed by the Finnish Ministry of Trade and Industry, Energy Department. REFERENCES (1) McKeough, P. et al., Techno-economic assessment of selected biomass liquefaction processes. Stockholm 1983. IEA Co-operative project D l (BLTF). Final report, vol. 5. Publ. National Energy Administration, Sweden.

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(2) Elliott, D.C., Analysis and upgrading of biomass liquefaction products. Stockholm 1983. IEA Co-operative project D l (BLTF). Final report, vol. 4. Publ. National Energy Administration, Sweden. (3) Solantausta, Y. and Asplund, D., Methanol from peat. Technical and economic aspects in Finland. Symposium on Peat as an Energy Alternative, December 1–3, 1980, Arlington, Virginia, USA.

Fig 1. Block diagram of a flash pyrolysis process (Flash/W, Flash/P), production of primary oil.

Fig 2. Block diagram of a highpressure hydrogenation process (PERC, H-Peat), production of primary oil.

Fig 3. Block diagram of an indirect liquefaction process (MeOH/W, MeOH/P), production of methanol.

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Fig 4. Effect of the price of raw material on the cost-value ratio, primary liquids. basis as table II.

Fig 5. Effect of the price of raw material on the cost-value ratio, gasoline. Basis as table II.

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Table I. Overall material and energy flows of the process concepts, primary liquid fuels. Concept PERC

Feed Feed Electricify Liquid material in t/h demand MW product Wood

83.3

FLASH Wood

83.3

MEOH Wood H-PEAT Peat

83.3 83.3

FLASH Peat

83.3

MEOH Peat 1) excess char

83.3

Liquid Byproduct Overall thermal product t/h efficiency % out t/h (LHV)

12.2 Primary oil 9.0 Primary oil 20.6 Methanol – Primary oil 4.0 Primary oil 20.6 Methanol

19.2

–

72

29.6

–

60

23.7 11.2

– –

51 60

13.8

9.41)

43

24.7

–

49

Table II. Comparison between process concepts, primary liquid fuels, as of January 1984 Gulf coast. Plant capacity 1000dry t/d, service life 20 a, rate of interest 8% (annuity 0.1019). Wood cost 30 USD/wet t, milled peat 16 USD/wet t. Concept

Total capital requirement 106 USD

PERC/W 120 FLASH/W 60 MEOH/W 170 H-Peat/P 220 FLASH/P 60 MEOH/P 175 1) production cost/ equivalent fuel oil value

Operat ing cost 106 USD/a fixed variable 10.5 6.8 14.9 17.3 5.9 15.2

Production cost USD/GJ (LHV)

25.3 23.6 29.5 11.2 12.3 20.2

Cost-value’ ratio

10.0 9.5 16.3 13.6 8.1 13.5

2.1 1.6 2.4 2.0 1.5 2.0

Table III. Comparison between process concepts producing gasoline from wood, as of January 1984. Basis as table II. Concept Overall thermal efficiency % (LHV) PERC/G FLASH/G MTG/G

50 46 42

Product cost Cost-value ratio USD/GJ USD/t 17.5 19.2 21.0

760 830 910

2.0 2.2 2.4

WHAT FUTURE FOR THE THERMOCHEMICAL LIQUEFACTION OF BIOMASS ? Catherine ESNOUF CEMAGREF B.P.121–92160 Antony Cedex France SUMMARY The bulk of research carried out for producing liquid fuels (including engine fuel) was analyzeds, except for conventional acid hydrolysis and biological processes. The main conclusions of this survey are presented: – In the study of direct liquefaction including chemical reactants, the alkaline CO-steam process (Process Develpment Unit at Albany— USA), and its recent developments, were taken into special considaration, because the extent of the results obtained allows to point out the reasons for its failure. In particular, a complete chemical reactional mechanism for biomass components can be built, so that one can select which chemical conditions are liable to lead to much better results, through a reduction and stabilisation of low molecular weight depolymerisation products. – Some thermal processes (pyrolyses) lead to promising results: the vacuum pyrolysis, the solvolyses (liquid or super-critical solvents), the pyrolysis in water under pressure with a very rapid heating and quench, as means of global treatment; as for a separate use of the hemicellulose/cellulose/lignin fractions, the supercritical extraction (ethanol: water) and the sequential extraction with water. The analysis of the results obtained, through a correlation with the conventional schema of pyrolysis reactions, enables to understand which physical parameters are important to enhance the quantity and quality of the liquid product, but also permits to determine the limits of such thermal processes. – In conclusion, such an investigation allows to select which physical and chemical reactional conditions may lead to interesting processes, and what produts might thus be obtained.

1 —INTRODUCTION “Thermochemical liquefaction” as a direct process leading to liquid fuels production is mainly concerned with depolymerization and deoxygenation of biomass. The research works carried out in this field were studied and 14 results were selected. The conclusions

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drawn up are presented in this report: are there promising tracks in new processes especially for the production of vehicular fuels? 2. —MAIN PROCESSES AND RESULTS The reacting conditions and main results are listed in Table I. The processes can be classified into three types, according to the operating conditons: – a direct liquefaction including chemical action: the solid biomass is severely treated in one step for liquefaction and reduction; the product obtained is partially upgraded if necessary, in order to mainly yield hydrocarbons. The PERC process is to be considered, as well as Nickel or Iron catalyses, oralkalinereac-tion without reducing gases. – a two-step liquefaction involves firstly a cheap step for biomass depolymerization, i-e solvolysis or pyrolysis, and secondly, an upgrading of the crude liquid or its cuts, leading to hydrocarbons, alcohols, and phenols. The pyrolysis may be a conventional carbonization, or may be carried out to enhance liquid production, i-e, a rapid, flash, or vacuum pyrolysis, or a “hydropyrolysis” which is a rapid pyrolysis of biomass in water under pressure. The only solvolyses considered there (for their good results) are specific ones : either supercritical extractions, or the UDS process which includes a mechanical defibration pretreatment (severe depressurization) and high heating rates (2). – a separation of biomass polymers: The solid biomass is partially depolymerized to yield separate cuts: 1—carbohydrates derived species in a solvent (cellulose and hemicellulose), leading to sugars by a hydrolysis or a thermolysis; a final hydrogenation of fermentation yielding alcohols. 2—polyphenols in a solvent (lignin), giving phenol, guaiacol and similar species, either used as chemical products, or hydrogenated to BTX. Numerous processes folow this general schema; we have only considered two original ones: an elution in water at two temperature levels with very controlled kinetics, and a supercritical extraction with an ethanol: water variable ratio solvent. RESULTS: – Pyrolyses (excluding hydropyrolysis) are characterized by a high char yield (at least 10%)—the oils obtained have a high water content, i-e high fluidity and oxygen content—their chemical composition, organic acids (10–20%), ketones, aldhydes, furans, phenols and methoxyphenols mainly, explain their thermal instability; the upgrading attempts have therefore failed so far (except perhaps for heavy tars of conventional carbonization). So their only use would be as burning fuel. For the most interesting process (flash pyrolysis), the estimated cost is similar to that of fuel n• 6, taking their difference in energetic value into account (Biomass: 30 /maft in all cases). Considering their low heating value and high corrosivity, they should be used only as mixtures with petroleum fuel or coal, and thus can be expected in two cases:

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– for refuses or sewage sludge disposal, when cheaper than burning, – as a by-product of carbonization, when charcoal is economic, thus considering only over-investment for condensation and storage of liquids. – Liquefaction under pressure (including UDS process), possibly with a chemical action, have a low char yield (<3%). As compared with pyrolysis, the oils have a lower water content, i-e a higher viscosity and lower oxygen content. It should be noted that the oxygen content of dry oils is always the same, except under efficient reducing conditions. The main interesting point is that, thanks to both their chemical composition (phenols and polyphenols, methoxyphenols, naphtols, cyclic ketones, <5% acids) and thermal stability, the oils can be upgraded to 50% hydrocarbons through a’catalytic hydrogenation (300°C, CoMo+S). The estimated cost for these final products in a PERC (2) (3) is 3 to 4 times that of gasoline, but only 1,2 times that of other substitutes from biomass, i-e Methanol+MTG Mobil or vegetable oil esters. Anyway, new proesses like the UDS can be cheaper than PERC and thus give economical gasoline. – Supercritical solvolyses have not proved yet feasible because of solvent incorporation into the product, leading to a high cost. – Hydropyrolysis has given only limited results, but as far as we know, it is similar to liquefaction under pressure for one part (lowchar yield) and to pyrolyses for another (chemical composition of the oil). This latter point suggests that a global hydrogenation would be difficult; but a the chemical species are in limited number in the product (phenolics from lignin and sugars or their degradation products from cellulose), the operating conditions would be well adapted to a separation process as described above. – Separation processes yield an interesting rate of non-degraded sugars but are not to be used as yet: the sugars are diluted in one case and the loss of ethanol is unknown in the other.

3— INTERPRETATION The analysis of these results allows us to determine which operating conditions can give valuable products at reasonable costs. The results are not affected by the process type i-e: direct or 2 step liquefaction but they mainly depend on the two following criteria: a) chemical conditions: the mechanisms probably involved in different reactions are shown in fig.I. In all cases, the depolymerization of biomass is obtained. But, to yield low molecular weight deoxygenated products, the condensation of primary products by a reduction should be stopped: a Hydrogen transfer through catalyst (metal complexes in water?) or H. donor polar solvents recycled (alcohols, hydroxyaromatics?). This chemical action may take place in-situ or in a second step: anyway it must be rapid and efficient, the intermediates being very reactive. b) physical conditions: When comparing the results with the classical model of biomass pyrolysis mechanisms, various alternatives to enhance liquid production can be pointed when selecting the operating conditions: heat and mass transfer possible with a large granulometry; a delayed quench and low dilution; a localisation of chemical

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reactants for an optimum efficiency (protect catalysts from solid particles poisoning, limit hydrogen consumtion by avoiding aromatic cycle saturation,…).

4— CONCLUSION a) What products can be obtained? – a low-grade burning fuel by pyrolysis in a specific economic context – vehicular fuel: *aliphatic and aromatic hydrocarbons through hydrogenation of phenolics and cyclicketones (direct liquefaction under pressure) * alcohols through reduction of sugars and intermediate products of cellulose degradation + hydrocarbons fromthe lignin fraction hydrogenation. b) What priorities for research? Concentrate the efforts on processes taking the above criteria into account especially a reduction strictly adapted to depolymerization/condensation kinetics, in one or a few steps, but involving a separation of biomass polymers if the kinetics appear as incoherent. Therefore, the following points schould be studied: – optimization of reaction kinetics and solvents – adapted configuration for hydrogenation (in situ with a special design or upgrading), – integration of such elementary steps in a flobal biomass separation process, – concurrent economic evaluation.

REFERENCES (1) ESNOUF (C.) 1985—Thermochemical Liquefaction of biomass: A Review submitted for publication. (2) CHORNET (E.) & OVEREND (R.) 1984—Biomass liquefaction: Prospects and Problems. Bionergy 84 conference—Göteborg-Sweden. (3) WILHELM (D.J.) & al 1981—Transportation fuel from biomass by direct liquefaction and hydrotreating. SRI International.

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Fig.II

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IMPROVEMENT OF THE ETHYLENE GLYCOL WATER SYSTEM FOR THE COMPONENT SEPARATION OF LIGNOCELLULOSES D.Gast and J.Puls Institute of Wood Chemistry and Chemical Technology of Wood D-2050 Hamburg 80, Federal Republic of Germany Summary Kinetic data for the delignification of birchwood were determined for the ethylene glycol-water system at 180, 190, and 200°C. Delignification occurs in two distinct phases according to first order reactions. The activation energies for the first and the second delignification phases were found to be 81.2kJ/g—mole and 135.5kJ/g. mole respectively. Upscaling of the process from the laboratory to the 10l scale yielded products for further investigations on possible applications. The chemical composition of pulps and the adhesive strengths of phenolic resin-lignin mixtures are discussed.

1. Introduction Chemical pulping processes such as kraft and sulfite involve high capital costs and pollution problems. The development of alternative technologies has therefore been pursued for a long time. Organosolv pulping has been proposed as an option. In most cases low boiling alcohols such as methanol, ethanol or butanol were tested as delignifying agent. Kleinert (1) proved, that mixtures of ethanol and water were more effective than ethanol alone. The use of ammonium sulfide in aqueous methanol solutions was proposed by Chiang and Sarkanen (2). The MD-organosolv process is based on the use of methanolwater-sodium hydroxide solutions (3). Phenol pulping is an example for pulping with a high boiling solvent under atmospheric pressure (4). We have compared the pulping efficiencies of customary low- and high boiling alcohols in mixture with water and found ethylene glycol among the high boiling alcohols to be even more effective than the commonly used low boiling alcohols (5). Organosolv systems using high boiling solvents offer some advantages concerning the process conditions. The pressure in the system corresponds to the partial pressure of water at the required temperatures, losses of solvent and danger of fire on account of the volatility are drastically reduced. Our interest concentrated on the development of a non-toxic, sulfurfree pulping process without using greater amounts of inorganic chemicals. Ethylene glycol seemed to meet the requirements for such a process and therefore was chosen as solvent for further investigations on time and temperature effects and for upscaling experiments.

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2. Experimental Batch delignification studies for kinetic data aquisition were conducted according to (6). Cooks in the semi-technical stage were performed in a quasi continuous digester system. The system consisted of four 10l autoclaves with electronically regulated heating jackets and a pump, connected by pipes and valves in such way, that each combination was possible. After preheating in the first autoclave the pulping liquor (10l ethylene glycolwater 1:1v/v) was pumped into the second autoclave containing approximately 2,5kg of fresh wood chips preheated to about 100°C. In this way the heat up period could be diminished to 10min. The pulping liquor was then continuously whirled round the wood loaded autoclave. After attainment of the desired pulping time, the liquor was drained through a valve into a vessel, containing a small amount of water for precipitation of lignin. For adhesive preparations the lignins were mixed with commercial phenolic resin (BASF Kauresin 260) in the desired proportions (Table III), 10% of NaOH, 10% of paraformaldehyde and 10% of filling material were added and the preparation was diluted to a solids content of 50%. The adhesives were tested on 5 mm thick beech plates. The adhesive spread was 200g/mm2. The pressures for pre-pressing and hot-pressing were 0.98N/mm2 and 1.47N/mm2 respectively. The shear tests were conducted in accordance with German standard DIN 53 254 (7) and the test specimens were tested in accordance with test groups B1 and B4 of DIN 68 602 (8). Samples of the fibre materials were hydrolyzed with H2SO4. The sugars in the hydrolysates were determined according to (5). 3. Results and Discussion In accordance with previous findings of other authors (9, 10), kinetic data in ethylene glycol-water pulping result in two first order reaction curves for each temperature applied (Fig. 1). Initial fast delignification is partly ascribed to the breakdown of lignincarbohydrate and intermolecular lignin linkages with following extraction of the solubilized lignin molecules (9, 11). Lower accessibility of the residual lignin and condensations reactions of dissolved lignin molecules also with hemicellulose degradation products are assumed to be responsible for the sharp decrease in delignification in the second stage (11). The rate of delignification can be expressed by a first order equation of the form: In L=In Lo−kt (a), where L is the residual lignin in pulp after the cooking time t, Lo is the content of lignin in the original wood and k is the rate constant (1/min). Table I presents the values for the rate constants, activation energies, and frequency factors. Kleinert (9) in his kinetic study on aqueous ethanol pulping found a value of 117.6kJ/g · mole for the slow part of delignification, and reports overall values of 134.4kJ/g · mole for caustic soda pulping and 135.2kJ/g · mole for kraft pulping. In semi-technical pulping chips from birch, beech, and spruce were used as raw material. The analytical data of the pulps shown in Table II indicate that most of the hemicelluloses were removed. Apparently the pulps may be good substrates for chemical conversion processes. Investigations concerning this field are currently in progress. The delignification rate of spruce is still insufficient and needs further optimization. The lignins were tested as extenders in phenolic resin adhesives. The bonding strength of the adhesives are specified in Table III. If 50% of the phenolic resin is replaced by lignin, the

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shear strengths of the test specimens exceed the minimum shear strengths required by the German standard DIN 68 602 (10N/mm2 dry- and 4N/mm2 wet testing). 4. Conclusion Sufficient delignified pulps can be obtained in semitechnical ethylene glycol-water pulping of hardwoods. The lignins produced show promising results as extenders in phenolic resin adhesives. The next steps will include investigations on the practical applicability of the fibre material as dissolving pulp and the improvement of softwood delignification. Acknowledgement This research is financed by EEC, project no. BOS-012-D (B) References 1. Kleinert, T.N. (1974). Organosolv pulping with aqueous alcohol. TAPPI 57 (8): 99–102 2. Chiang, V.L. and Sarkanen, K.V. (1983). Ammonium sulfide organosolv pulping. Wood Sci. Techol. 17: 217–222 3. Edel, E. (1984). Das MD-Organosolv-Zellstoffverfahren. DPW, Dtsch. Papierwirtsch. 1: 39–45 4. Sachetto, J.-P., Armanet, J.-M. Tournier, H., Michel, J.-P. Johansson, A.A., Roman, A. (1981). A method for the delignification of wood and other lignocellulosic products. European Patent Application EP 0 043 342 A1 5. Gast, D., Ayla, C. and Puls, J. (1982). Component separation of lignocelluloses by organosolvtreatment. In: Energy from Biomass, 2nd E.C.-Conference. Appl. Sci. Publ. London New York: 879–882 6. Gast, D. and Puls, J. (1984). Ethylene glycol-water pulping Kinetics of delignification. In: Anaerobic Digestion and Carbohydrate Hydrolysis of Waste. Appl. Sci. Publ. London New York: 450–453 7. German Standard, DIN 53 254. (1980). Testing of wood adhesives and glued wood joints, Determination of shear strength of lap joints 8. German Standard, DIN 68 602. Evaluation of adhesives for joining of wood and derived timber products; strain groups, strength of bond 9. Kleinert, T.N. (1975). Ethanol-water delignification of wood—rate constants and activation energy. TAPPI 58 (8): 170–171 10. April, G.C., Kamal, M.M., Reddy, J.A., Bowers, G.H. and Hansen, S.M. (1979). Delignification with aqueous-organic solvents. TAPPI 62 (5): 83–85 11. Lora, J.H. and Wayman, M. (1978). Delignification of hardwoods by autohydrolysis and extraction. TAPPI 61 (6): 47–50

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Fig. 1 Logarithm of residual lignin in fibre material RATE CONSTANTS AND ACTIVATION ENERGIES IN ETHYLENE GLYCOLWATER PULPING Temp. °C I II Rate const.×10−3 min−1 Frequency factor Ao Activ. Energy E kJ/gm-mole

180 190 200

26,2 2,4 47,8 7,2 69,7 15,2 1,85×107 1,18×1013 81,2 135,5

Table I Ethylene glycol-water pulping Fibre material from semi-technical pulping—Analytical data* Raw Yield Carbohydrates Klason Accessibility material Mannose Xylose Glucose lignin % enzym. degr. % % % % % % % Birch 49.0 0.5 9.2 84.1 93.8 Beech 49.5 1.1 9.3 82.0 92.4 Spruce 66.8 2.7 3.6 67.1 73.4 All values based on fibre material *) Ethylene glycol: Water 1:1, 190°C, 90min

6.9 11.5 25.3

68.6 60.8 8.8

Table II Ethylene glycol-water lignins as extenders in phenolformaldehyde (PHF) resins

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Ratio Lignin: PHF

Shear Test Tested dry* Tested wet** Strength W.Failure Strength W.failure N/mm2 % N/mm2 %

75:25 10.4 40 3.5 20 Birch 50:50 11.5 100 5.3 33 Beech 50:50 10.4 80 4.4 30 Spruce 50:50 10.3 94 4.4 68 Pressing temp.: 150°C *After condition**After 6 hours boiling Pressing time: 10min ing at 20°C/ Pressure: 1.47N/mm2 65% rel. humidity

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HYDROTHERMOLYSIS OF SHORT ROTATION FORESTRY PLANTS G.BONN, W.SCHWALD, O.BOBLETER Institute of Radiochemistry, University of Innsbruck, Austria V.I.BENEA Statiunea Experimentala Silvica Cornetu, Bucuresti, Romania SUMMARY Hydrothermolysis is a newly developed method to obtain low molecular substances from plant biomass (1–3). In this process the hemicellulose is solubilized at approx. 200°C, the cellulose is converted to oligomeric and monomeric carbohydrates as well as further degradation products such as hydroxymethylfurfural (HMF) and furfural at approx. 280°C, and lignin is degraded at temperatures above 300°C by the use of water only as elution medium. The possibility of employing short rotation forestry plants (poplar wood) for this purpose was investigated.

EXPERIMENTAL Hydrolysis Apparatus and Reaction Conditions The hydrothermolysis was carried out in an apparatus consisting of a 10ml volume reaction vessel (4). A high-pressure pump delivered water through a preheating unit into the electrically heated reaction vessel. The pressure in the reaction vessel was adjusted by a metering valve to ensure that the water remained in the liquid phase during the experiment. Analysis The analyses of the wood samples were carried out using the TAPPI Standards. The gluco-oligomers were analyzed using GPC (5), monosaccharides and further degradation products by HPLC (6–9). RESULTS AND DISCUSSION Hydrothermal degradation experiments were carried out with poplar wood as starting material, which was supplied from a Romanian short rotation forestry culture. From chemical assays, conclusions were drawn regarding degradation characteristics and carbohydrate yields. Apart from dry weight and ashes, the following determinations were carried out in compliance with familiar analysis procedures: benzene/alcohol extract, holocellulose, α-cellulose and lignin content. Table I gives the chemical raw material

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analysis of Populus deltoides without bark, first from a biennial, then from a four-yearold sample.

TABLE I Chemical raw material analysis of Populus deltoides 2 years 4 years humidity (%) ash (E atro) (%) benzene/alcohol extract (%) holocellulose (%) α-cellulose (%) lignin (%)

6.1 1.3 3.9 84.8 45.2 16.3

5.6 0.6 3.3 86.0 46.4 18.8

Hydrothermolysis of poplar wood (Populus deltoides) To investigate what influence is exerted by the age of the fast-growing wood types just described, two- and four-year-old samples with and without bark were subjected to hydrothermolysis at different degradation temperatures. At a temperature of 277°C and a flow rate of 10 ml/min the maximum recidence time of the dissolved material inside the reaction vessel is about 1 minute. The degradation came about shown in Fig.1 for a fouryear-old Populus deltoides without bark, and in Fig.2 for the same material, at a reaction temperature of 287°C. The maximum concentrations of xylose and glucose obtained in the main fraction are specified in Table II. The follow-up reactions that lead to furfural and HMF from xylose and glucose were also determined quantitatively and are depicted in Figs.1 and 2. From degradation and analysis data obtained by GPC and HPLC several parameters characteristic of the hydrothermal process can be derived, making allowance for the age of the wood samples used. Fig.3 shows the main fraction of the hydrothermal degradation of poplar wood (4-year-old) without bark and Fig.4 the same species with bark. In Fig.4 the molecular components first eluted probably originate from the soluble portion of bark. A further significant difference is obvious in the oligomer distribution and the monomeric sugar yield. Barkless material upon hydrothermolysis yields more glucose than wood material containing bark. In Fig.5 the reaction course of the characteristic hydrothermolysis products using HPLC is shown. Apart from the gluco-oligomers, cellobiose, glucose, xylose, fructose, glyceraldehyde, 1.6-anhydro-ß-D-glucose as well as the heterocyclic sugar degradation products HMF and furfural are detected. From most of the degradation series, it was ascertained that, in all, more solid dissolves when barkless wood is used. The time at which maximal solid concentrations appear in the eluate is dependent on how much bark was present in the wood samples. Four- and two-year-old species with bark produce roughly the same glucose yields. These experiments showed that the two year old poplar wood yielded lower sugar concentrations than the four year old specimens. As expected the barkless samples gave higher sugar yields than those with bark. In preliminary experiments it was proved that the overall yield can be considerably increased by low temperature hydrothermolysis (at approx. 200° C) with an additional enzymatic saccharification.

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Fig.1 Hydrothermolysis of 4-year-old poplar wood without bark at a degradation temperature of 277°C

Fig.2 Hydrothermolysis of 4-year-old poplar wood without bark at a degradation temperature of 287°C.

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TABLE II Hydrothermolysis of Romanian poplar wood without bark (4-year-old) degradation temperature residue (%) dissolved solid (%) maximum solid matter concentration (mg/ml) max. glucose concentration (mg/ml) max. xylose concentration (mg/ml)

277°C 287°C 11.3 84.6 37.5 1.6 1.1

5.8 86.5 39.6 3.4 1.2

Fig.3 GPC chromatogram of a hydrothermally degraded poplar wood sample (4-year-old) without bark. Column, Bio-Gel P-2; flow rate, 0.12ml/min; detection, RI. 1…glucose, 2–8…gluco-oligomers, 9…xylose, 10…HMF

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Fig.4 GPC chromatogram of a hydrothermally degraded poplar wood sample (4 year-old) with bark. Column, Bio-Gel P-2; flow rate, 0.12ml/min; detection, RI. 1…glucose, 2–9…gluco-oligomers, 10…HMF

Fig.5 HPLC chromatograms of the main fractions (7,8,9) from hydrothermolysis of poplar wood without bark at a reaction temperature

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of 284°C. Column, u Spherogel×7.5 Carbohydrate and ion exclusion microguard (cation H); mobile phase, water; flow rate, 0.6ml/min; column temperature, 85°C; detection, RI; 1…glucose, 2…cellobiose, 3…DP 3 (DP=degree of polymerization), 4…xylose, 5…fructose, 6…glyceraldehyde, 7…1.6-anhydro-ßD-glucose, 8…HMF, 9…furfural ACKNOWLEDGEMENT The authors are indebted to the Bundesministerium fuer Wissenschaft und Forschung (Vienna) for their financial support. REFERENCES 1. BOBLETER, O. and PAPE, G. (1968). Verfahren zum Abbau von Holz, Rinde oder anderen Pflanzenmaterialien. Austrian Patent 263661 2. BOBLETER, O., BONN, G. and CONCIN R. (1980). Hydrothermolysis of biomass-production of raw-material for alcohol fermentation and other motor fuels. Alternative Energy Sources III, Vol 3, p 323, Ed.: Veziroglu, T.N., Hemisphere Publ.Corp., Washington, USA 3. BONN, G., CONCIN, R. and BOBLETER, O. (1983). A new process for the utilization of biomass. Wood Sci. Technol., 17:195 4. SCHWALD, W. and BOBLETER, O. (1984). Recycling durch Hydrolyse von Rohbaumwolle und Baumwol1-Gewebeabfä1len. Chemiefasern/Textilind., 34/86:527 5. SCHWALD, W., CONCIN, R., BONN, G. and BOBLETER, O. (1985). Analysis of oligomeric and monomeric carbohydrates from hydrothermal degradation of cotton-waste materials using HPLC and GPC. Chromatographia 20/1:35 6. BONN, G. and BOBLETER, O. (1984). Analysis of biomass degradation and fermentation products by ion exchange HPLC. Chromatogram-Beckman, 5/2:8 7.BONN, G. and BOBLETER, O. (1984). HPLC-Analysis of plant biomass hydrolysis and fermentation solutions. Chromatographia, 18:445 8. BONN, G., PECINA, R., BURTSCHER, E. and BOBLETER, O. (1984). Separation of wood degradation products by high-performance liquid chromatography. J.Chromatogr., 287:215 9. BONN, G. (1985). HPLC—elution behaviour of oligosaccharides, monosaccharides and sugar degradation products on series-connected ion-exchange resin columns using water as mobile phase. J.Chromatogr., 322/3:411

SYNTHESIS OF SEVERAL ALCOHOLS FROM BIOMASS GASES WITH ZEOLITE CATALYSTS J.C.GOUDEAU*, A.BENGUEDACH**, L.JULIEN* *Université de Poitiers Groupe de Recherches de Chimie Physique de la Combustion, Domaine du Deffend Mignaloux Beauvoir 86800 Saint Julien l’Ars France ** Institut de chimie Université d’Oran Es Senia, Oran Algérie Summary From synthesis gases (CO, H2) we have studied catalytic synthesis of homologous alcohols with catalysts prepared from zeolites: principally 13X and modernite associated with some transition metals like copper and zinc. Synthesis is realised in a dynamic reactor under pressure (50 bar) and under temperatures from 250°C to 400°C. We have obtained interesting results for some catalytic compositions. Synthesis is principally oriented to butanol with a selectivity of 70%, and a conversion rate of carbon monoxide of 20%. These results depend from several parameters: nature of the zeolite, nature and concentration of metals presents in the zeolite, reduction conditions of catalyst, crossing time on gases of the catalyst, gases compositions.

1. INTRODUCTION Des efforts de recherche considérables ont été consentis pour dévelop-per des procédés de transformation de gaz de synthèse en carburants ou intermédiaires de synthèse. La synthèse Fischer-Tropsch, développée durant la seconde guerre mondiale en Allemagne n’a continué à être utilisée que dans les rßgions où les circonstances locales étaient favorables. D’autres procédés existent, on citera notamment la synthèse isobutylique, aboutissant principalement à la synthèse d’alcools dont le nombre d’atomes de carbone ne dépasse pas 6; un certain nombre de réactions parasites interviennent également de façou notable (cokéfaction, formation de CO2). Il est important de souligner que ces réactions nécessitent à la fois des pressions et des températures élevées (300 à 400 bar, 350 à 500°C). Pour rendre ces réactions intéressantes sur le plan technique et éco-nomique, il est nécessaire de mettre au point des catalyseurs fonctionnant à des pressions et températures abordables et permettant de bons rendements. Ces catalyseurs doivent être sélectifs thermiquement et mécaniquement stables.

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De l’ensemble des catalyseurs utilisés pour la réaction d’hydrocondensation du monoxyde de carbone orientée vers la synthèse d’alcools, on retiendra principalement les deux couples CuO—ZnO et ZnO—Cr2O3. Notre laboratoire a mis au point un catalyseur particulièrement actif pour la synthèse du méthanol à partir du couple Cu, Zn. Les tests catalytiques sont effectués dans une unité fonctionnant sous pression en régime dynamique (1) (2). Le présent travail est relatif à là mise au point d’un catalyseur à base de zéolithe (type 13X) et à l’exécution de tests catalytiques. 2. PREPARATION DU CATALYSEUR La préparation du catalyseur se fait selon un schéma classique: la zéolithe est soumise à un échange ionique à partir des métaux suivants: Cu, Zn, Th, Ce. Une fois le taux d’échange limite atteint (déterminé par spectrophotométrie de flamme), la solution est filtrée, le filtrat est lavé puis calciné à l’air libre à une température portée de 150°C à 400°C par paliers horaires de 50°C. L’échantillon est laissé à 400°C pendant 10 heures, ensuite broyé, tamisé et pastillé. L’échantillon de précurseur ainsi obtenu est ensuite réduit à l’aide d’un mélange contenant 8% d’hydrogène dans de l’azote avec un débit de 50 litres par heure à une température de départ de 120°C. La température est progressivement portée à 500°C où le catalyseur est maintenu pendant 72 heures. La faible teneur en hydrogène du mélange réducteur et la lente montée en température sont rendues nécessaires par l’important dégagement de chaleur engendré par la réaction. 3. TESTS CATALYTIQUES Les alcools primaires sont obtenus d’après l’équation générale cidessous:

A partir de notre catalyseur, on obtient principalement le butanol selon l’équation équilibrée ci-dessous:

Compte tenu de l’exothermicité de la réaction, nous avons effectué une approche thermodynamique en vue de: – déterminer la quantité de chaleur dégagée dans nos conditions opéra-toires et prévoir l’évacuation de cette chaleur. – prévoir les limites de conversion dans nos conditions opératoires. Les paramètres expérimentaux suivants ont été successivement envisagés: rapport molaire H2/CO, temps de passage du gaz de synthèse sur le catalyseur, température de synthèse. L’analyse des produits condensés a permis de mettre en évidence la présence de méthanol, éthanol, isopropanol, isobutanol, eau, dimethylether et cetones diverses. La

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concentration en isobutanol de la phase condensée dépasse 40%, la somme des concentrations des autres alcools n’excède pas 8% ce qui représente une sélectivité en isobutanol supérieure à 80% lorsque l’eau est éliminée. Les effluents gazeux sont également analysés et sont principalement constitués d’hydrocarbures saturés CH4, C2H6 et C3H8 et également de H2 et CO n’ayant pas réagi. Les résultats expérimentaux concernant la conversion du monoxyde de carbone en isobutanol pour un rapport molaire H2/CO=3 sont réunis dans le tableau suivant: Température(°C)\Temps de contact (seconde) 0,4 0,8 1,2 1,6 180 4 5,6 6,9 8,4 200 5,6 7,9 10 13,0 210 8,1 10 11,9 15,7 220 10 11,3 14 17,8 240 15 16,1 17,5 23 260 12,0 12,5 15,2 20

La figure N° 1 représente les variations de la conversion du monoxyde de carbone en fonction de la température pour différents temps de passage. Les courbes ont des allures en cloche très caractéristiques. On constate un maximum de conversion voisin de 250°C et que pour un temps de passage de 1,6 seconde, les valeurs de la conversion sont voisines des valeurs à l’é-quilibre. La figure N° 2 représente les variations de la conversion du monoxyde de carbone en isobutanol en fonction du temps de passage pour différentes températures.

Figure N° 1

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Figure N° 2 Les variations du rapport H2/CO ont également été envisagées (figure N° 3).

Figure N° 3 La conversion croit avec le rapport H2/CO; il nous est apparu inté-ressant d’utiliser le rapport 3 pour l’essentiel de nos tests. Ce rapport permet en effet une augmentation relative importante de la conversion.

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4. CONCLUSION Nous avons ainsi pu mettre au point un catalyseur à la fois actif et sélectif pour la synthèse de l’isobutanol. Les conversions du monoxyde de carbone atteint 20% et la concentration de l’isobutanol dans la phase liquide dépasse 80% (en dehors de l’eau). Ce catalyseur présente une activité catalytique très stable dans le temps puisque nous n’avons observé aucune chute de conversion notable même. après 500 heures de fonctionnement. La mise au point de catalyseurs de même type est susceptible d’être étendue à d’autres types de supports et avec d’autres éléments de transition en proportions variables, ceci en vue d’orienter la sélectivité vers d’autres alcools. En outre, notre dispositif expérimental est susceptible d’être utilisé avec deux lits catalytiques successifs ce qui peut également permettre l’élargissement des possibilités de synthèse, à partir du mélange CO, H2 vers la production d’hydrocarbures notamment. REFERENCES (1) MASSON, C., BOURREAU, A., LALLEMAND, M., SOUIL, F.et GOUDEAU, J.C. (1980). 1st Conference “Energy from Biomass”, Brighton, Nov 80. (2) GOUDEAU, J.C., BOURREAU, A.et KABBARA, N. (1982). 2nd Conference “Energy from biomass”, Berlin, sept 82.

INVESTIGATIONS ON METHANOL CATALYTIC SYNTHESIS FROM BIOMASS GASES: OPTIMIZATION OF THE PROCESS ON A NEW CATALYST A.BOURREAU, J.C.GOUDEAU, L.JULIEN, A.NEMICHE, F.SOUIL Université de Poitiers Groupe de Recherches de Chimie Physique de la Combustion Domaine du Deffend Mignaloux Beauvoir 86800 SAINT JULIEN L’ARS FRANCE SUMMARY The research began several years ago on methanol catalytic synthesis from biomass gases has permitted to us to test some catalysts under a pressure of 50 bars with gases mixtures containing impurities (1), (2). Interpretation of obtained results has permitted to optimize conditions of methanol synthesis with a catalyst prepared in our laboratory. The new reactor was realised with two successive catalytic beds and we have studied the following parameters: stability of the catalyst with temperature and during the time, influence of preheating of synthesis gases on conversion rate principally molar ratio [H2]/[CO]. From results obtained we have entered kinetic study of the reaction to precise some steps of the catalytic reaction.

1. INTRODUCTION Le méthanol peut être obtenu à partir d’un gaz de synthèse par la réaction:

La gazéification est un procédé et une possibilité de transformation de la biomasse pour la production de gaz de synthèse. Diverses réactions interviennent et donnent des mélanges gazeux dont les constituants principaux sont le monoxyde de carbone (CO), l’hydrogène (H2), le dioxyde de carbone (CO2), le méthane (CH4) et éventuellement d’autres hydrocarbures, l’azote lorsque cette gazéification est effectuée à l’air. Les gaz de synthèse ainsi obtenus peuvent être utilisables pour la synthèse de combustibles liquides tel que le méthanol. Nous nous sommes intéressés à ce problème et divers travaux ont été réalisés au GRCPC, notamment la mise au point d’un catalyseur pour la synthèse à basse pression, l’étude de l’influence de certains gaz sur les paramètres de la synthèse, comme l’azote, l’ammoniac, le méthane et divers hydrocarbures (1) (2) (3).

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A la lumière de ces travaux, nous avons mis au point une installation expérimentale nous permettant: – de mener les études de la synthèse en l’absence de l’influence des diffusions externe et interne – d’optimiser la conversion du monoxyde de carbone en méthanol

FIGURE N° 1: Schéma de l’installation MD.CO=Manomètre détendeur CO R1=Réacteur 1 MD.H2=Manomètre détendeur H2 S1=Manomètre sortie réacteur 1 E.V.CO=Electrovanne CO REC.1=Recette réacteur 1 E.V.H2=Electrovanne H2 E2=Manomètre entrée réacteur 2 C=Capillaire R2=Réacteur 2 DB.CO=Débimètre CO S2=Manomètre sortie réacteur 2 REC.2=Recette réacteur 2 DB.H2=Débimètre H2 V.D.CO=Vanne de débit CO DB.H2+CO=Débimètre mélange H2CO

Investigations on methanol catalytic synthesis from biomass gases

V.D.H2=Vanne de débit H2 MEL.=Mélangeur V1,V2,…V10,V11=Vannes E1=Manomètre entrée réacteur 1

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R.P.=Régulateur de pression

– de réaliser une étude de l’influence du préchauffage du gaz d’alimentation et une éventuelle utilisation de la chaleur de réaction pour ce pré-chauffage. 2. CONDITIONS EXPERIMENTALES L’installation de synthèse mise au point au laboratoire fonctionne en régime dynamique sous une pression maximale de 60 bar, et permet divers modes de fonctionnement (fig 1). Pour ces études, le mélange gazeux est constitué de monoxyde de carbone et . d’hydrogène dont le rapport molaire Les pressions partielles du monoxyde de carbone et de l’hydrogène ainsi que la pression totale sont maintenues constantes (Ptotale=50 bar). Nous avons étudié l’influence de la température et du temps de passage sur le taux de conversion du monoxyde de carbone en méthanol avec le catalyseur type MC 1 mis au point au laboratoire. L’étude de la stabilité du catalyseur en fonction du temps a montré que, si la température reste inférieure à 350°C, pratiquement aucune perte d’activité du catalyseur n’est observée bien que le temps de fonctionnement soit très long (250 heures). Par contre, un fonctionnement de 5 heures sous 350°C suffit pour provoquer une désactivation importante. L’intervalle de température considéré pour cette étude est 230–320°C. Dans le but d’optimiser la conversion, nous avons envisagé deux modes opé-ratoires différents: l’étude de la synthèse avec deux lits catalytiques successifs et l’influence du préchauffage du gaz d’alimentation. 3. SYNTHESE DU METHANOL SUR DEUX LITS CATALYTIQUES SUCCESSIFS Dans les mêmes conditions de température et de temps de passage, nous avons comparé les résultats expérimentaux obtenus avec un seul réacteur et ceux obtenus avec deux réacteurs en série avec refroidissement intermédi-aire. Ces résultats montrent les variations du taux de conversion en fonction de la température pour différents temps de passage du mélange gazeux sur la catalyseur (fig 2).

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FIGURE N° 2 Nous avons pu mettre en évidence que l’utilisation de deux réacteurs en série améliore la conversion du monoxyde de carbone en méthanol par rapport à l’utilisation d’un seul réacteur. Ces résultats sont en parfait accord avec les calculs théoriques pré-alables. L’augmentation relative de la conversion est de l’ordre de 70% pour une température de 250°C et un temps de passage de 0,5 seconde. Cette augmentation relative diminue avec le temps de passage (fig 3). Pour les températures supérieures à 290°C, les taux de conversion obtenus avec un seul réacteur et deux réacteurs en série tendent à s’égali-ser (on est proche de l’équilibre thermodynamique). 4. INFLUENCE DU PRECHAUFFAGE DE GAZ D’ALIMENTATION Cette étude est réalisée pour une éventuelle évaluation de l’économie de l’énergie consommée pour le chauffage du gaz avant son contact avec le catalyseur. La méthode utilisée consiste à envoyer le gaz d’alimentation préala-blement préchauffé à travers le lit catalytique chauffé à la température de réaction.

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FIGURE N° 3

FIGURE N° 4 Nous constatons que le préchauffage de gaz d’alimentation n’a pratiquement pas d’influence sur le taux de conversion du monoxyde de carbone en méthanol si la température de préchauffage ne dépasse pas 200°C. Pour une température du lit catalytique fixe et égale à 260°C, la conversion du monoxyde de carbone, en fonction de la température du pré-chauffage des gaz d’alimentation et pour différents temps de passage, augmente légèrement jusqu’à 200°C. Mais au-delà de cette température, la conversion chute très vite. Cette baisse rapide peut être attribuée à la surchauffe du grain du catalyseur qui provoque une désactivation de celuici (fig 4).

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Il est donc envisageable d’utiliser la chaleur dégagée par la réaction pour préchauffer les gaz d’alimentation, la température du préchauffage ne devant toutefois pas dépasser 200°C. 5. CONCLUSION Nous avons ainsi abordé dans cette étude l’optimisation de la synthè-se catalytique du méthanol sur un catalyseur à base d’oxydes de cuivre et de zinc mis au point au laboratoire. Les synthèses ont été conduites sur des mélanges exclusivement composés de gaz purs: monoxyde de carbone et hydrogène. Le montage expérimental réalisé qui comprend deux réacteurs en série permet de négliger toute influence macroscopique sur la réaction de synthèse. Après une étude paramétrique portant sur les facteurs suivants: temps de passage, température du lit catalytique, rapport stoechiométrique H2/CO, nous avons envisagé successivement deux modes de fonctionnement de notre dispositif expérimental. D’une part, le fonctionnement avec deux lits catalytiques successifs identiques, étude qui nous a permis d’augmenter la conversion du monoxyde de carbone de façon très importante, et, d’autre part, le fonctionnement avec préchauffage du gaz de synthèse. L’optimisation de cette réaction de synthèse sera poursuivie par l’é-tude des différents modes de fonctionnement non encore testés dans le but d’aboutir à une meilleure connaissance de la réaction: approche du méca-nisme réactionnel notamment. REFERENCES (1) MASSON, C., BOURREAU, A., LALLEMAND, M., SOUIL, F.et GOUDEAU, J.C. (1980). 1st Conference “Energy from biomass”, Brighton, November 1980. (2) GOUDEAU, J.C., BOURREAU, A.et KABBARA, N. (1982). 2nd Conference “Energy from biomass”, Berlin, September 1982. (3) GOUDEAU, J.C., BOURREAU, A.et SOUIL, F. (1983). Alternative Energy Sources. Vol. V.Elsevier, Netherlands.

THE SOLID-LIQUID TRANSFER PROCESS IN A SLIGHTLY HYDRATED HETEROGENEOUS MEDIUM: AN ORIGINAL WAY TO SYNTHETISE ORGANIC CHEMICALS FROM BIOMASS M.E.BORREDON, L.RIGAL, M.DELMAS and A.GASET Laboratoire de Chimie Organique et d’Agrochimie, Ecole Nationale Supérieure de Chimie, Institut National Polytechnique 118, route de Narbonne, 31077 TOULOUSE Cédex, France Summary The plant polymers constituent the principal part of biomass can be readily valorizated in new chemicals with high yields and very good selectivity after primary breakdown using the solid liquid transfer process. The reactions proceed in a heterogeneous medium which involves a solid alcaline hydroxide or carbonate, an organic solvent, the substrates and a small quantity of water which acts as catalyst.

INTRODUCTION The value of biomass as a source of mid weight capacity chemical products lies in the fact that it provides specific products which can not be created through petrochemistry. These products such as 2-furancarboxaldehyde, 5-hydroxymethyl 2-furancarboxaldehyde, dianhydrohexitols, phenolic aldehydes readily available from hemicellulose, hexoses, polyholosides and lignins are of great interest for their intrinsic qualities. Traditional synthetizing techniques in organic chemistry using a carbonyl function applied to biomass extracted aldehydes such as furfurol, hydroxymethylfurfurol or phenolic aldehydes give poor results in terms of reactivity and selectivity. For these reasons, such techniques are not useful on industrial scale. Furthermore, the furanic cycle through obviously interest, presents particular antibacterial and fireretarding characteristics within its inner structure. This dictates that, for each transformation to be considered, new synthetizing techniques must be defined in relation to the specificity of the biomass extracted molecules.

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RESULTS AND DISCUSSION We report herein on the reactions realized in slightly hydrated heterogeneous solid-liquid medium. This new synthetizing technique uses a solid base (alcaline, hydroxide or carbonate), a liquid organic phase, usually a mixture of an organic solvent and the reagent issued from biomass, with a carefully controlled amount of water. The water molecules localized at the interface of the two phases play an unexpected and critical rol, similar to a phase transfer catalyst. In this way new alkenes, oxirans, unsaturated nitriles and ethers are synthetized under very mild experimental conditions. The 5-hydroxymethyl-2 furancarboxaldehyde used in the experiments is obtained according to our original process (1) which involves a triphasic system created with D-fructose as model substrate, a cation exchanger and extracting solvent. The system was applied to the processing of plant materials extracts like inulin from Jerusalem artichoke (1). Alkenes The Wittig reaction carried out under solid liquid phase transfer conditions using an alkaline carbonate usually yields high amounts of the corresponding alkene (table 1). The stereochemistry of the double bond depends of the protic or aprotic character of the solvent in relation to the solvation effect of the hydroxyle function on the intermediate betaïne or oxaphosphetane. The potassium carbonate avoids the Cannizzaro and the aldolic reaction and does not promote any elimination reaction form the phosphonium salt used in slight excess.

Table 1

R1

R2

Solvent Yield % Z/E Ref.

H Furyl 1,4 dioxane CH2 (CH2)2CH3 Furyl 1,4 dioxane Ethanol CH2(CH2)3CH3 Furyl H Hydroxymethyl-5 furyl 1,4 dioxane *H3(CH2)7 CH3(CH2)12 1,4 dioxane CH3CH2CH2 p-hydroxyphenyl Méthanol * Pheromone Diptera musca domestica.

92 94 65 89 73 88

– 80/20 30/70 – 82/18 19/81

(6) (3) (4) (8) (5)

The operation of the Wittig reaction in solid-liquid heterogeneous sligh-ty hydrated medium therefore appears as a process that can readily be transported on a larger scale and is thus liable to make easier the synthesis of furyl, phenolic or longchain alkyl alkenes (2–7).

The solid-liquid transfer process in a slightly hydrated heterogeneous medium

1103

Unsatured esters The so called Wittig-Horner reaction using potassium carbonate in a slightly hydrated organic solvent allowed the synthesis of a new class of furyl and phenolic α β unsaturated esters (table 2) (10,11).

Table 2

R

Yield (%) Ref.

Furyl 5-hydroxymethylfuryl p-hydroxyphenyl CH3(CH2)4CH2

90 90 88 95

(11) (11) (11) (11)

The reactions are selective and show a particularly high conversion rate of E-ethylenic esters especially with regard to furyl aldehydes which is the essential difference between this and other previously reported procedures concerning such molecules. The reaction’s stereoselectivity can be attributed to the marked stabilization of the intermediate oxyanion which thus promotes the existence of a stable form precursor of the E isomer. Oxirans The condensation reaction between furfural or terpenyl ketones and a sulfonium salt (table 3) using the solid-liquid phase transfer process in the presence of an excess of potassium hydroxide (alkaline carbonates are ineffective) led selectively and quantitatively to the corresponding oxiran.

Table 3

R

R’

R” Yield Ref.

Furyl H H Furyl Butyl H Furyl H Methyl Menthyl H 5-hydroxy-méthylfuryl H H

92 95 70 89 85

(8) (8) (8) (8) (8)

The use of polar solvents such as acetonitrile together with the control of the hydratation rate of the reaction medium promoted the formation of the oxirans at the expense of the Cannizzaro or aldolic reactions. In this way the first direct synthesis of 2-furyloxiran from furfural was realized (8).

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Unsaturated nitriles Unlike the oxiran synthesis the reactivity of acetonitrile with potassium hydroxide is worked to give unsaturated nitrile after reaction with 2-furancarboxaldehyde. The reaction was generalized to numerous aldehydes (table 4). Ethers The solid-liquid transfer process applied to etherification of hydroxyle function involves the reaction of dimethylsulfate or an alkyl bromide in the presence of solid potassium hydroxide 1,4-dioxane or DMSO and a small quantities of water (table 5).

Table 4

R

Yield Z/E

Furyl 98 25/75 Phenyl 98 20/80 Anisyl 90 18/82

Table 5

R

R’

X

Solvent Yield

Furylmethyl CH3 SO4CH3 triglyme Isosorbide CH3 SO4CH3 1,4 dioxane SO4CH3 1,4 dioxane Phenol CH3 Isosorbide CH3(CH2)4 Br 1,4 dioxane Isosorbide CH2-CH-CH2 0 Br 1,4 dioxane Yield in diether

85 97 98 92 88

The reactants are used in stoechiometric amounts. The work up is very easy. Dimethylisosorbide was thus obtained for the first time in a quantitative yield (12). CONCLUSION The easy an efficient synthesis of numerous compounds, new for the most part, corroborates the major interest of solid-liquid phase transfer processes in the functionalization of the molecules originating from the primary breakdown of plant polymers. The biomass can be considered as a source of starting materials that are liable to be used on a large scale since they can lead to various and valuable applications.

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The promising economical aspect, as a result of the simplicity and of the low cost of the processes and materials involved, opens new prospects for this kind of molecule in polymer chemistry as well as in fine chemistry. REFERENCES (1) RIGAL L. and GASET A. (1983). Biomass, 3, 151. (2) LE BIGOT Y., DELMAS M. and GASET A. (1982). U.S. Patent 4.346.040. (3) LE BIGOT Y., DELMAS M. and GASET A. (1982). Synthetic Communication, 12, 107 and 1115. (4) LE BIGOT Y., DELMAS M. and GASET A. (1985). U.S. Patent 4.501.910. (5) LE BIGOT Y., DELMAS M. and GASET A. (1983). Tetrahedron Letters, 24, 193. (6) AREKION J., DELMAS M. and GASET A. (1983). Biomass, 3, 59. (7) LE BIGOT Y., DELMAS M. and GASET A. (1983). J. Agric. Food. Chem., 31, 1096. (8) BORREDON M.E., DELMAS M. and GASET A. (1983). European Patent n° 83 200686 2. (9) BORREDON M.E., DELMAS M. and GASET A. (1983). Biomass, 3, 67. (10) LE BIGOT Y., DELMAS M. and GASET A. (1983). European Patent, n° 83 15753. (11) MOULOUNGUI Z., DELMAS M. and GASET A. (1984). Synthetic Communication, 14, 701. (12) ACHET D., DELMAS M. and GASET A. (1985). Synthesis (in press).

BIOCONVERSION OF ORGANOSOLV LIGNINS BY DIFFERENT TYPES OF FUNGI A.HAARS, A.MAJCHERCZYK, J.TROJANOWSKI and A.HÜTTERMANN Forstbotanisches Institut der Universität Göttingen Büsgenweg 2, 3400 Göttingen, F.R.G. Summary Organosolv lignins from a pilot plant were incubated with fungi from different ecological types and the bioconversion rates were compared to results obtained for 14C-labelled organosolv lignins prepared by the same pulping procedure. The data obtained by the radiorespirometric method were in accordance with the findings for the technical lignins: 1.) White-rot fungi were capable to convert the lignin by splitting the arylether linkages. 2.) A water-soluble acid-precipitable polymerizate (WSAPL) was formed, part of which had humin-like properties, e.g. not soluble in organic solvents after drying. The amount of humin-like substance was dependent on extracellular phenoloxidase activity. 3.) The molecular weight distribution and the phenolic hydroxyl content of WSAPL as determined by IPSEC (Ion pair size exclusion chromatography) was markedly changed after fungal attack depending on the type of fungus.

1. INTRODUCTION The organosolv process, among other novel technologies, is con-sidered to have the best economical prospects because the pulp is of satisfying quality and the sulfur-free (!), low molecular weight lignin can be separated in a more or less unchanged structure. Compared to the sulfur containing byproduct lignins (kraft lignin and lignosulfonate) these properties are supposed to facilitate microbial access of organosolv lignin. Therefore, the purpose of our work was to evaluate the bioconversion reactions of fungi from different ecological types (white- and brown rot, soil fungi, mycorrhizal fungi etc.) on lignins obtained by organosolv pulping. The problem was approached using two different methodologies: 1.) Using 14C-labelled organosolv lignin, prepared by pulping 14C-labelled wood from beech saplings 1, as substrate for mycelia of white-rot fungi and protoplasts 2 of

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Heterobasidion annosum, and measuring the 14CO2-release by the radiorespirometric method and 14C-labelled soluble and insoluble fractions in the culture fluid. 2.) Using technical organosolv lignins 4, kindly supplied by the MDNicolaus Comp., Munich, as substrate for several fungi and measuring the bioconversion to soluble, insoluble and mycelium-bound fractions quantitatively by gravimetry and UVspectroscopy and monitoring molecular weight changes by IPSEC (Ion pair size exclusion chromatography 5. Results and Discussion 1.) The most prominent linkages in lignin are the aryl-ether linkages which connect the C-2’-position of the side chain of one monomer unit with the aromatic ring of another unit. The capacity of fungal cultures to split the aryl-ether linkages in 14corganosolv lignin is indicated by the 14CO2 release from 14C-2’-(side chain) carbons (Fig. 1). Heterobasidion annosum and Pleurotus florida as well as the isolated protoplasts, were also capable to convert the 14C-organosolv lignin to water-soluble and high polymeric products which could be fractionated in a dioxane-soluble and a dioxane-insoluble (humin-like) fraction. The surprising high conversion activity of protoplasts towards organosolv lignin meke them interesting as a f irst step in developing an “in vitro” ligninconverting system.

Fig. 1. Degradation of 14C-2’-(chain) of organosolv lignin by mycelia 2.) Seven representative fungi of the types listed in Tab. 1 were incubated as liquid stationary cultures with 1% suspensions of technical organosolv lignins. After an appropriate cultivation period the biomass yield and phenoloxidase (PO; E.C.1.14.18.1) activities were tested and the bioconversed lignin was fractionated into water-soluble acid-precipitable lignin (WSAPL), acidsoluble low molecular weight mterial (AS), water-insoluble dioxane-soluble lignin (WIL) and mycelium recovered lignin (ML). Uninoculated lignin cultures (C1) served as controls. All fractions were quantitatively weighed and tested by UV-spectroscopy and IPSEC.

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The results obtained by the radiorespirometric method for H.a. are in accordance with the data presented in Tab. 2: two wite-rot fungi (H.a. and I.b.) solubilize a considerable part of the lignin (WSAPL-S), whereas in all other cultures the WSAPL-content decreased, possibly due to metabolization or acidification of the medium by secretion of organic acids 6.

TAB 1 FUNGI SPECIES

ABBREVIATION TYPE

HETEROBASIDION ANNOSUM (=FOMES ANNOSUS) PLEUROTUS FLORIDA POLYPORUS VERSICOLOR POLYPORUS PINSITUS SCHIZOPHYLLUM COMMUNE SPOROTRICHUM PULVERULENTUM GLOEPHYLLUM TRABEUM CENOCOCCUM GEOPHILUM

H. A.

WHITE-ROT F.

P. F. P. V. P. P. S. c. S. P. G. T. C. G.

″″ ″″ ″″ ″″ ″″ BROWN-ROT F. MYCORRHIZAL F.

TRICHOLOMA AURANTIUM BOTRYTIS CINEREA

T. A. B. c.

FRUIT-AND LEAF ROT F. SOIL F.

The organosolv lignins induced high PO activities in cultures of P.v., P.f., H.a. and I.b., Oxidative polymerizing reactions in these cultures led to marked decrease in the phenolic hydroxyl content of WSAPL-S (67% lower than in C1-WSAPL) and to the formation of a “humin-like”-substance (WSAPL-H), which after drying was no more soluble in dioxane or other organic solvents. In cultures of C.g. and S.p. containing no and negligible amounts of extracellular PO activity, respectively, the phenolic hydroxyl content remained unchanged and no or barely detectable amounts of humin-like substances were formed. The concentration of low molecular weight aromatic substances decreased in all cultures. The remaining portion contained also newly formed substances which were released into the culture medium as response to the presence of lignin (evaluated by Sephadex LH2O GPC and TLC (data not shown). Changes in the molecular weight distribution of the bioconversed lignin fractions were monitored by IPSEC. Lignin samples were chromatographed on PSM 60S and 1000S columns (Dupont) in THF as mobile phase containing an alkylammoniumchloride as solubilizer for the bioconversed part of lignin insoluble in organic solvents (humin-like substance) and to prevent adsorption and aggregation effects 5. Fig. 2 shows that considerable changes occurred in the region 2000–30 000 Daltons of WSAPL depending on the type of fungus and PO activity, whereas WIL remained nearly unchanged. For straw and kraft lignins it was also found that the water-soluble fractions are better degraded than the crude preparation 7.

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Fig. 2 IPSEC elutlon diagrdms of different organosolv Lign in fractions from spruce before and after fungal attack. Numbers In the areas of Mw 1000 ■ 10 000 and 10 000* JO 000 are percentages of lignin amount in the Mw-region. The mycelium bound lignin seems to be an intermediate between WSAPL (compare the peak at Mw 6000, which is present in WSAPL also) and WIL (compare the high amount of lignin in the molecular weight region 10 000–30 000 Dalton). As was demonstrated before 8, active lignin degraders are not only found among basidiomycetes of the white-rot type: C.g.—an ectomycorrhizal Deuteromycete which was found to be an active decomposer of 14C-ring-labelled DHP was more active than our strain of S.p.. REFERENCES (1) CRAWFORD, D.L., CRAWFORD, R.L. and POMETTO, A.L. (1977). Preparation of specifically labelled 14C-lignin and 14C(cellulose)-lignocelluloses and their decomposition by the microflora of soil. Appl. Environm. Microbiol. 33, 1247. (2) TROJANOWSKI, J., HÜTTERMANN, A., HAIDER, K. and WESSELS, J.G.H. (1985). Degrdation of lignin and lignin related compounds by protoplasts isolated from Fomes annosus. Arch. Microbiol. 140, 326–330.

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(3) HAIDER, K. and TROJANOWSKI, J. (1975). Decomposition of Specifically 14C-Labelled Phenols and Dehydropolymers of Coniferyl Alcohol as Models for Lignin Degradation by Soft and White Rot Fungi. Arch. Microbiol. 105, 33–41. (4) EDEL, E. (1984). Das MD-Organosolv-Verfahren. Sonderdruck “Innovationen im Zellstoffkocher”, dpw Deutsche Papierwirtschaft 1/1984. (5) MAJCHERCZYK, A., HAARS, A., TAUTZ, D. and HÜTTERMANN, A. Manuscript in preparation. (6) CHEN, C., CHANG, H. and KIRK, T.K. (1982). Aromatic acids produced during degradation of lignin in spruce wood by Phanerochaete chrysosporium. Holzforschung 36, 3–9. (7) JANSHEKAR, H., HALTMEIER, T. and BROWN, C. (1982). Fungal degradation of pine and straw alkali lignins. European J. Appl. Microbiol. Biotechnol. 14, 174–181. (8) TROJANOWSKI, J., HAIDER, K. and HÜTTERMANN, A. (1984). Decomposition of 14Clabelled lignin holocellulose and lignocellulose by mycorrhizal fungi. Arch. Microbiol. 139, 202.

THE FRACTIONATION OF LIGNOCELLULOSIC SUBSTRATES BY STEAM EXPLOSION AND THE SUBSEQUENT CONVERSION OF THE VARIOUS COMPONENTS TO SUGARS, FUELS AND CHEMICALS J.N.Saddler, E.K.C.Yu, M.Mes-Hartree, N.Levitin and H.H.Brownell Biotechnology and Chemistry Department, Forintek Canada Corp. 800 Montreal Road Ottawa, Canada, KlG 3Z5 Summary Several years ago we evaluated various chemical and enzymatic methods of converting lignocellulosic residues to fermentable sugars and reactive lignin. We have focused on the use of hydrofluoric acid and organosolv pulping, and cellulases from Trichoderma species as the best respective methods for chemically and enzymatically hydrolysing lignocellulosic substrates. Although relatively high concentrations of sugars could be obtained by the chemical hydrolysis methods, the liberated sugars proved difficult to ferment while the lignin component appeared to be much more condensed than that obtained from steam exploded wood. Steam explosion was the preferred method of pretreatment for enhancing enzymatic hydrolysis because of the relatively low pretreatment costs and because of the ability to fractionate the substrate into three product streams. Water extraction of steam treated aspenwood chips removed over 75% of the hemicellulose. This pentosan rich stream was hydrolysed by mild H2SO4 or fungal cellulases then fermented to butanol by Clostridium acetobutylicum or butanediol by Klebsiella pneumoniae. The water extraction step also removed inhibitory materials which were produced during the pretreatment step. Subsequent mild alkali extraction of the pretreated aspenwood removed over 75% of the original lignin. This left a cellulose rich residue which could be used as the substrate for growth and enzyme production of various cellulolytic fungi and which could be readily hydrolysed to fermentable sugars.

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1. INTRODUCTION Most of the current research into the conversion of renewable, biomass resources was motivated in the past by escalating oil prices. Although this concern has been alleviated to a large extent by the current oil glut there should still be a general concern that oil is a diminishing resource and that the price will invariably rise in the long term. Canada is in the fortunate position of having vast resources of timber on which much of its economy and trade are based. This resource was originally advocated as the lignocellulosic substrate on which a bioenergy industry could be established. However much of the needed technology has proven more difficult to achieve than was originally planned while the traditional forestry based industries have not been convinced of the validity of this whole approach. The industry does recognise however that there are problems with residue utilisation and that the productivity of the forest has to be greatly enhanced. As approximately 40% of the tree is not utilised for the more traditional structural uses of wood, such as lumber, composite board, pulp and paper, etc., a substantial amount of material exists which is either burned or treated as a waste problem. Our approach has been that unless a use for the three, cellulose, hemicellulose and lignin, components can be found, any bioconversion process is unlikely to be economic. This assumption is also based on the fact that lignocellulosic residues are a potential substrate primarily because they should be cheaper than comparible starch substrates. As cellulose constitutes about 50% of the substrate, the true value of the feedstock for glucose based fermentation processes is actually double the perceived value unless uses can be found for the hemicellulose and lignin components. In this paper we have briefly described the various approaches we have taken to converting wood residues to fuels and chemicals. 2. RESULTS AND DISCUSSION When we initiated our biomass conversion programme several methods of enzymatic and acid hydrolysis were examined to see what yields of glucose and xylose could be obtained and to also characterize the different types of lignin derivatives that were obtained. We found that dilute sulphuric acid hydrolysis resulted in the liberation of approximately 60% of the cellulose component as glucose, which was similar to the values obtained by other workers (Saeman, 1982). In contrast, we have found that hydrolysis with hydrogen fluoride resulted in high sugar yields with very low levels of sugar decomposition. The effect of various parameters such as hydrolysis time at 0°C and at 20°C, HF/wood ratios of 10:1 and 5:1 and water content of the HF on glucose and xylose yields are shown in Table 1. Highest glucose yields were obtained with an HF/wood ratio of 5:1 after a reaction time of 45 minutes at 0°C. The presence of 10% water in the HF did not appear to adversely affect the glucose and xylose yields. We are presently comparing enzymatic and mild acid post hydrolysis methods of fractionating the soluble oligosaccharides obtained by HF hydrolysis as well as ensuring that the liberated sugars are readily fermented. This work has been paralleled by a similar approach which has used organosolv pulping as the means of solubilising the cellulose and hemicellulose components which have been further hydrolysed by enzymes or mild acid hydrolysis. Preliminary results indicate that a more desirable lignin is obtained by

The fractionation of lignocellulosic substrates by steam explosion

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this latter method as the lignin obtained from HF treated aspenwood appears to be highly condensed. We have found that lignin obtained by the alkali extraction of steam exploded aspenwood also appears to be highly reactive and has many potential applications such as an adhesive used for composite wood construction (Calve & Shields, 1982). Steam explosion appears to be an excellent method for pretreating lignocellulosic substrates as it enhances their enzymatic hydrolysis and permits the fractionation of wood into its different components. A schematic representation of our bioconversion process based on steam explosion and enzymatic hydrolysis is shown in figure 1. We have found that approximately 10% of a pretreated wood substrate is required to “generate” enough cellulase to hydrolyse the remaining 90% to glucose. This ratio varies depending on the nature of the cellulase system and the type of lignocellulosic substrate which is being hydrolysed. After an extensive screening of cellulolytic fungi we have found that various Trichoderma species seem to be among the most cellulolytic microoganisms (Saddler, 1982). Trichoderma harzianum produced a complete cellulase complex, after growth on steam exploded wood fractions, which was able to hydrolyse most of the cellulose and hemicellulose of various steam exploded wood fractions to their component monosaccharides (Saddler et al, 1982a), Previously we had shown (Saddler et al, 1982b) that a combined hydrolysis and fermentation (CHF) approach to converting pretreated wood to ethanol was advantageous as it reduced the incidence of contamination and reduced end product inhibition of the enzymes by the continuous fermentation of the liberated sugars to ethanol. As other workers had indicated that ethanol was inhibitory to T. reesei cellulases (Ghosh et al, 1982) we wanted to ensure that this was not the case with cellulases from T. harzianum. It was apparent (Table 2) that none of the cellulase activities were greatly affected while xylanase activity seemed to be enhanced when the enzyme reactions were supplemented with increasing concentrations of ethanol. Previously we had shown (Saddler et al 1982a) that approximately 75% of the hemicellulose component of steam exploded aspenwood could be extracted by a further washing with mild alkali. Although the hemicellulose rich water soluble fraction contained inhibitory material which restricted enzyme hydrolysis and fermentation of the sugars this material has been successfully used as a substrate for butanol and butanediol production (Yu et al, 1984). We are currently assessing different applications for the various lignin types that are obtained after the fractionation of pretreated lignocellulosic substrates. It would appear that the bioconversion of lignocellulosic residues to fuels and chemicals can be a valid proposition, providing the cost of the substrate is inexpensive. If this technology is to achieve full commercial viability, development at the pilot plant level must be complemented by continued research into the fundamental mechanisms of the bioconversion process. REFERENCES (1) CALVE, L. and SHIELDS, J.A. (1982). Proc. Fourth Bloenergy R & D Seminar, March 29–31, Winnipeg, Canada pp. 403–407. (2) GHOSH, P., PAMMENT, N.B. and MARTIN, W.R.B. (1982). Enzyme Microb. Technol. 4 425–430.

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(3) SADDLER, J.N. (1982). Enzyme Microb. Technol. 4 414–418. (4) SADDLER, J.N., BROWNELL, H.H., CLERMONT, L.P. and LEVITIN, N. (1982a) Biotechnol. Bioeng. 24 1389–1402. (5) SADDLER, J.N., HOGAN, C., CHAN, M.K.-H. and LOUIS-SEIZE, G. (1982b). Can. J. Microbiol. 28 1311–1319. (6) SAEMAN, J.F. (1982). Proc. Roy. Soc. Can. Symp. on Ethanol from Biomass, Winnipeg, Canada pp. 231–246. (7) YU, E.K.C., DESCHATELETS, L. and SADDLER, J.N. (1984). Biotechnol. Lett. 6 327–332.

Table 1. Effect of various parameters on glucose and xylose yields after the hydrolysis of aspenwood by liquid HF HF Anhydrous ″ ″ ″ ″ ″ ″ ″ 90%

Temp. Time HF/Wood Glucose (°C) (min) ratio % o.d. wood 0 0 0 0 20 20 20 0 0

15 30 45 60 15 30 60 45 30

10/1 10/1 10/1 10/1 10/1 10/1 10/1 5/1 10/1

43.9 43.3 49.6 43.2 39.3 42.1 47.4 51.2 45.3

Xylose % o.d. wood 13.8 15.8 14.5 14.7 21.7 18.2 11.0 16.8 17.3

Glucose Xylose Lignin Recovery Recovery % o.d. % % wood 81.3 80.1 92.0 80.0 72.7 78.0 87.6 94.8 83.8

71.5 81.7 75.1 76.0 – 93.8 56.9 87.0 89.6

Table 2. Effect of increasing ethanol concentration on the cellulase activity of culture filtrates derived from T. harzianum grown on 1% Solka Floc Ethanol Conc % 0.0 0.5 1.0 2.0 3.0 4.0 5.0

Enzyme activity (% of original) Endoglucanase β-glucosidase Filter Paper Xylanase 100 98 99 102 98 99 94

100 100 98 96 97 96 96

100 91 90 108 93 93 92

FIGURE. Process Scheme for Conversion of Aspenwood to Ethanol.

100 103 113 110 106 113 113

17.4 20.4 24.5 22.4 21.9 22.0 20.9 22.5 20.6

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CHEMICALS FROM SUGAR INDUSTRY WASTE PRODUCTS M.G.KEKRE and A.TAHA Department of applied chemistry and chemical technology University of Gezira Wadmedani, Sudan Summary The potential of Agricultural wastes as renewable source of energy is wellknown. The Sudan boasts of worlds biggest integerated sugar industry the K.S.C. (Kenana Sugar Co.), and biggest agricultural co-operative (Gezira scheme), and yet no attempt seems to have been made to tap the vast potential of its agricultural waste products. The paper describes the results of preliminary study about the chemicals that could be obtained from the wastes of above mentioned sugar industry and Sudan as a whole. The authors wish to show that in present circumstances in most of the developing countries it is the only way to obtain chemicals and energy rather than from expensive and advanced petroleum based technology (suitable for industrialised countries only).

INTRODUCTION Biomass has received increasing attention (1–2) as a possible source of chemicals. Production of ethanol from biomass is already established and no doubt will grow in future. However until recently the potential of biomass for commodity chemicals was not clear because of the cost factor. It is to be emphasised here that a clear distinction is to be made between the industrialised and the developing countries in Africa, Asia and far East. It is not only the cost factor but the balance of payments situation which counts. A recent I.M.F. report (3) states that most of the African countries are under heavy debts. In case of Sudan the same report says that up to 90% of export earnings could go for debt service. Thus the whole approach to chemical and energy production in developing countries (in Africa) must change. The bitter fact is that they simply do not have either the technology or the resources for purchase of chemicals or fuels based on expensive petroleum (4). The only hope for these countries is to go for biomass both for chemicals and energy.

Chemicals from sugar industry waste products

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AGRICULTURAL WASTE UTILIZATION IN SUDAN The Sudan has both natural resources and conditions neccessary for growing sugar cane and other agricultural products e.g. oil seeds (ground nuts, cotton seeds, sesame). In fact it has such vast fertile land, and water from two Niles that there have been plans for developing it into a food basket for Middle East. The Kenana sugar factory, one of the largest integerated sugar factories in the world along with other five sugar factories is expected to produce about 600,000 tons of sugar. The byproducts of these sugar industries if utilised could result in considerable foreign exchange savings and a wide range of industries with the chemicals from byproducts as feedstock. Although there are many chemicals that could be produced from sugar industry waste it is recommended that an immediate start should be made with production of ethanol and furfural which could then serve as a basis for wide range of industries. The Sudanese case becomes even more stronger because as mentioned in a recent article (5) the factors favouring byproduct utilization are (a) single integerated unit having minimum one million tons of crushing capacity, (b) stringent foreign exchange position of the country and (c) end use of the chemicals produced. The Sudan has a large vegetable oil industry and a petroleum refinary where furfural could be used. In addition there is potential export market in Middle East countries. The alcohol produced from molasses (54 million litres) could all be consumed locally. In fact, there is market for 80 million litres per annum for alcohol used as fuel (gasohol) alone. In fact, there is market for much more alcohol when we consider the whole range of chemical industries possible with ethanol as feedstock. The proposed scheme for immediate implementation is given in Table 1. It is to be emphasized further that in these times of low sugar prices, proper byproduct utilization could considerably effect the economics of sugar industry and at the same time help Sudanese economy. Conclusion The Sudan has tremendous potential for chemicals from biomass (from sugar and vegetable oil industries). It is an irony that inspite of lack of fossil resources and plentiful biomass, no attempt has been made to use the biomass for chemicals. There is an urgent need for formation of group to study and advice on proper use of biomass, perticularly from sugar industry. Depending upon the financial resources being made available pilot plant studies for byproduct utilization for chemical production would be taken up. An urgent step towards this is neccessary as the interest in sugar industry is fast waining because of heavy losses due to sugar price fluctuations.

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Table 1 Proposed Scheme for Sugar Industry Waste Utilization (Production of Furfural and Ethanol) Product 1) Bagasse 2) Molasses 3) Furfural

Quantity/Cost/Revenue/annum 300,000 Tons 105,000 Tons 24,000 Tons (total production possible but proposed plant size 5,000 Tons) 26,000 Tons (35 million litres)

4) Ethanol 5) Cost of the plants a) Furfural 5 million US. dollars b) Ethanol 15 million US. dollars 6) Revenue from sales a) Furfural 2 million US. dollars b) Ethanol 10 million US. dollars 7) Expected returns 16–17% (profits) Note: Production figures above are for K.S.C. alone, the figure could be doubled for Sudan as a whole.

REFERENCES (1) KLAUSMEIR, Chemicals from biomass, proceedings of fifth symposium on biotechnology for fuels and chemicals May 21–25, 1984, editor Charles D.Scott, John Wiley (ISBN 0572-6585). (2) Regional Investment Promotion Meeting, sponsored by, UNIDO, Khartoum, 4–8 March, 1985. (3) ARAB NEWS (Saudi Arabia), 18 February, 1985. (4) Same as (1) (5) PATRAU, J.M., By-products of the cane sugar industry, Second Edition (1982), Elsevier (New York).

NEW PROCESS FOR THE FABRICATION OF ETHYL ESTERS FROM CRUDE VEGETABLE OILS AND HYDRATED ETHYL ALCOHOL R.STERN, G.HILLION, P.GATEAU and J.C.GUIBET Institut Français du Pétrole Summary The objectif of the research was to see if it is possible to prepare, easily and economicaly, ethyl esters from various vegetable oils by using a hydrated ethyl alcohol and crude oil which may be very acidic. The esters produced are intented to be used as diesel oil substitutes in engines equipped with direct injection which means that a high degree of purity must be attained. The process described comprises different steps and reaches 98% or more purity of the ester, a very low degree of acidity and a yield of 96 to 97% on a one-ton pilot-plant scale or more. The alcohols may contain up to 30% water and the oils the same amount of free acid. Examples are given with cotton-seed oil, palm oil, palm kernel oil, rapeseed oil and coconut oil. Some esters were tested on a bench for engines before experimentation with tractors. The different parameters of the process are considered.

1. Introduction The high price of the vegetable oils prevents from planning production of gasoil substitutes with them. But in some circumstances, this production becomes of actual interest -when there is overproduction of oil in a remote country as for example in Africa or a small island where gasoil is expensive to deliver -when big amounts of toxic oils are growing -when it remains in an oil factory a cheap fraction of an oil, such the solid fraction of a palm oil or the so called “fatty acids” coming from the refining. In these cases the only problems are technical as we must generally be able to produce the gasoil substitutes without big investments. The objectives are given below. 2. Detailed objectives a) The fabrication of ethyl esters on a small scale such as cooperative, farm, village or plantation.

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b) The goal is to use the esters as a substitute for diesel oil in all engines, even those equipped with DI injection. c) The raw materials come directly from an extruder or a small press and can be very acidic. d) The alcohol may be very hydrated with a titer of 96%, 92%, 80% or 50%. e) All the chemicals and absorbents should be readily available. f) The process equipment should be standard but corrosion resistant. g) The alcohol should not be evaporated at the end or reused, which means that it cannot be used in great excess. h) The yield of ester should attain at least 95 weight % but if possible more than 100%. i) The purity should exceed 97% with by products not dangerous for the engine. j) The glycerine produced should be easy to handle or to purify. k) No water whasing should be required should be required to prevent pollution. Finally, the problem has to be solved in the light of economic ecological and technical consideration to obtain a process on a “soft” technology basis. 3. Method used Reaction 1 and 2 show that for a good conversion water and glycerine have to be eliminated.

The reaction proceeds through a 5-step process where every step is important but simple. A. In the first step the oil and alcohol react to produce an ester with 80–90% conversion in the presence of an acidic catalyst. After 3 to 6 hours, depending on the type of alcohol used and the temperature, nearly 90% of the glycerine and some times more for the water are removed in a separate phase. The interesting feature of this step is that previous drying of alcohol or refining of the oil is not necessary. B. The second step consits in esterifying the free acid present in the ester. This is done by simply heating the solution of ester and alcohol with the catalyst that has not been eliminated in the glycerine phase. After 1 or 2 hours we reach a concentration of acid lower that 1% if at the same time we eliminate the water. C. We can now introduce an alkali catalyst to obtain 96 to 98% conversion for the ester. By adding 1 to 2 weight % of water we obtain a glycerine phase that contains traces of the acidic catalyst used before, together with all the glycerine, some of tha alcohol, water and fatty acid salts. D. In another repeating step a quantitative conversion and purification is ensured.

New process for the fabrication of ethyl esters from crude vegetable oils and hydrated ethyl alcohol

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E. Finally the last traces of alkali are eliminated by passing the esters containing from 5 to 10% alcohol through an absorbent column. Eventually to get more than 100% yield of esters we can remove the acid and ester which had been carried away in the basic glycerine phases and, after neutralisation, recycle them in the oil. FLOW SHEET

4. RESULTS Raw products

Alcohol

Purity oil

Palm oil, 5.2% acid

7% water

97.8

Palm oil, 5.2% acid

30% water

97.5

Palm oil, 5.2% acid

50% water

96.

Palm oil, 30% acid

7% water

98.

Rapeseed oil degummed

7% water

97.

Rapeseed acid, 44% oil

7% water

94.

Palm kernel oil, 7% acid

7% water

98.

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Coconut oil 3.5% acid

7% water

98.7

Cottonseed oil 3.1% acid

7% water

97.6

Frying oil used 0.5% acid

7% water

92

a) Purity is checked after evaporation of the alcohol by the refractive index method and by weight of a distilled ester and Glc analysis of residue. b) The ester generally contains less than 1% acid, 1% monoglycerides. c) The Conradson value on 10% residue is generally lower than 0.5%. d) The presence of alcohol in the ester at that end improves the quality of the esters though the cetane number is reduced from 52 with, for example, pure palm ethyl ester to respectively 50.5, 42, 35 and 23 with 10, 20, 30 and 50% ethyl alcohol (93%). e) In 10 hours from 1t palm oil, 0.33t ethyl alcohol (93%) 0.01t catalyst and 0.04t water we can produce 1.1t ester+alcohol and 0.28t of a glycerine phase. The only products consumed are the catalysts and 40 liters of water, besides energy. This work has been done with the financial aid of AFME (Agence Française pour la Maîtrise de l’Energie).

BIODEGRADATION OF NATIVE CELLULOSE F.ALFANI, L.CANTARELLA, A.GALLIFUOCO, L.PEZZULLO, M.CANTARELLA Department of Chemical Engineering, University of Naples, P.le Tecchio, 80125 Naples, ITALY. Summary The effectiveness of enzymatic saccharification of cellulose is improved carrying out the reaction with mixtures of two cellulases from different sources, such as T. viride and A. niger. In fact the yield of cellulose conversion becomes 40% higher than the maximum value reached with a single enzyme and glucose selectivity attains a level close to 90%. The hydrolysis of olive husks and straw was investigated in the present study. Moreover, the residual oligosaccharides can be conveniently converted to glucose in a second reactor throughout the catalytic action of A. niger immobilized in a gel layer of polyalbumin onto the surface of a membrane. The reaction obeys a combined diffusional and kinetic mechanism of control and enzyme thermal deactivation is prevented up to 45°C. Finally, product and substrate inhibitions, which limits βglucosidase activity, were studied.

1. INTRODUCTION The results discussed in the present communication refer to an experimental investigation which is part of a wider project on the development of a two step process for the enzymatic hydrolysis of lignocellulosic raw materials. In the course of former studies the following conclusion was reached. In spite of the numerous biomass pretreatments suggested in the Literature (1), native cellulose cannot be completely degradated to glucose in a single step by the action of the actually available cellulase complexes, and a further conversion of the oligosaccharides, catalyzed by a preparation rich in β-glucosidase is advisable. On the other hand, among the cellulase enzymes, the β-glucosidase component is the most difficult to handle since it is thermally unstable and its activity is curtailed by product inhibition. The research in progress aims to prove the advantages of immobilizing this enzyme in membrane reactors. The biocatalyst is physically entrapped in a gel layer of a natural polymer, a technique which was successfully tested with other enzymes and is very simple to be adopted. In order to avoid costly operations for the extraction and purification of the β-glucosidase from the complex, which unavoidably would increase the costs of glucose production, a crude cellulase complex has been immobilized. In this experimental work cellulase from Aspergillus niger was tested.

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Moreover, since the relative presence of amorphous and well organized regions in the cellulose structure, their mutual physical and chemical interactions, the degree of polymerization of the cellulose chains, and the resistances induced by the presence of other components, mainly hemi-cellulose and lignin, largely vary in the raw materials, it is impossible to find a cellulase which exhibits satisfactory well balanced activity of the exo- and endo-glucanases towards a large category of native substrates. of course, it would be in theory possible to produce in laboratory very specific cellulase complexes, throughout the adaptation and mutation of microorganisms or the balancement of extracted and purified enzymes, but again these techniques require time and money, which cannot be usually borne in a process for the formation of a low added value product, such as a sugar syrup. Therefore, our study was oriented to investigate the possibility of improving yield and selectivity during cellulose hydrolysis, simply by using mixtures of crude cellulases. 2. MATERIALS AND METHODS The experiments have been performed in a stirred and thermostated reactor, equipped with ultrafiltration membranes, Amicon PM 10, molecular weight cut off 10.000 Dalton, and under nitrogen pressure. Reactor volume was 72 ml and the total amount of enzymes was 3 mg. Cellulases from Tricoderma viride and from Aspergillus niger were obtained from Miles (USA) and Sigma (USA), respectively. The insoluble substrates, Avicel, olive husks and straw were directly charged into the reactor at the beginning of the run, whereas CMC was solubilized in advance, stored in a reservoir, and continuously forced to flow into the reactor. Microcrystalline cellulose, Avicel, was supplied from Machery Nagen (FRG), carboxymethyl-cellulose (CMC) was from Schuchard (FRG), whereas olive husks and straw were collected in different olive oil plants and fields in Southern Italy respectively. Olive husks were purified by extraction with CCl4 at the atmospheric boiling point and ball milled for 1 hour. Straw was cut for 5 minutes in a vortex. Both biomass were then sieved; the 48 mesh fraction was used in the present study. According to the method described in (4), the biomass was first pretreated for 3 hours at 90°C in aqueous solutions of 1% w/v sulphuric acid and then for 6 hours at 80°C in aqueous solutions of 0.8 N sodium hydroxide. At the end, most of the extractive compounds and hemicellulose, and part of the lignin are removed, and the remaining biomass contains roughly 50% by weight of cellulose. The tests of saccharification were always performed at 45°C in 50mM Na acetate acetic acid buffer pH 4.8, using 1g of Avicel, 0.5g of biomass and 0.1% w/v CMC aqueous solutions. Total reducing sugar concentration was measured by Nelson’s method (5) and glucose concentration was determined with the GOD-Perid reagent kit of Boerhinger Biochemia (Italy), modified by the addition of 10 mM δ-gluconolactone of Schuchard (FRG), a specific inhibitor of the β-glucosidase which contaminates the glucose oxidase of the assay kit.

Biodegradation of native cellulose

1125

3. RESULTS AND DISCUSSION Cellulase from T. viride is more active than cellulase form A. niger towards the saccharification of both commercial and native cellulose. Therefore, mixtures of these two complexes should exhibit an average activity between those of the two enzymes, as shown by the dotted line of Fig.1. On the contrary, cellulose conversion, X, µmoles of reducing sugar per mg of substrate, is higher working with enzymic mixtures and the curve presents a maximum for a composition which ranges between 2:1 and 1:1 ratio of T. viride to A. niger. This behaviour might be dependent on the improvement of the synergistic action of C1 and CX, the percentage of which in the two cellulases is different. An other point deserves a comment. Generally, a minor attention is devoted to determine product distribution during cellulose hydrolysis and efforts are mainly done to improve reaction yield. However, sugar

Figs.1,2—Saccharification yield, X, and Glucose selectivity, S %, vs. wt % of A. niger in the enzymic mixture. ●—Avicel; —CMC; ▲—Olive husks; ■—Straw polymers cannot be fermented and therefore glucose concentration in the products must be maximized. The data of Fig.2 indicate that, depending on cellulase source, glucose selectivity S, µmoles of glucose per µmoles of total reducing sugar, varies with enzyme percentage, but never reaches 100% in the range of cellulase composition which gives raise to the highest production. Therefore a second step of reaction is necessary for converting the oligosaccharides. This could be performed with either a soluble or an immobilized enzyme since substrates are small and water soluble molecules. Moreover, it would be also possible either to concentrate firstly the sugar solution up to 100–110g/l, which is a minimum economical value for carrying out the subsequent fermentation, or to work with the dilute solution which flows out from the first reactor. For the reasons specified in the introduction an A. niger complex instead of purified βglucosidase (5) was used in this study. Firstly the reaction was carried out with soluble

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enzyme, but the experimental evidences were negative. The enzyme is thermally unstable, its half life ranges between 316 hours at 30°C and 34 hours at 50°C. The kinetics of enzyme deactivation obeys a first order rate equation and its activation energy is 21.100cal/gmole. Moreover, a non competitive product inhibition takes place and substrate inhibition significantly occurs at cellobiose concentration greater than 10mM, which corresponds to roughly 3.5g/l. The following rate equations were derived for cellobiose hydrolysis at 30°C and 45°C in different ranges of operational conditions which allow to neglect cellobiose and glucose inhibition respectively : Product inhibition

Substrate inhibition

where I and S represent glucose and cellobiose concentrations (mM), E is the enzyme amount (mgE) and rG is the reaction rate of glucose production (µmoles/h mgE). Therefore, in a second phase of the investigation, the kinetic behaviour of the immobilized A. niger was tested. The cellulase was physically entrapped in a gel of polyalbumin following the procedure described in (7). The immobilized enzyme, see Fig.3, is very stable in the whole range

Fig.3—Thermal stability of the βglucosidase component of A. niger at different cellobiose concentration

Biodegradation of native cellulose

1127

of investigated temperature and cellobiose inhibition becomes evident at higher concentration, 20mM. The extent of product inhibition remains comparable with the corresponding value of the free enzyme. Moreover, the data of Fig.3, were plotted in a Lineweaver-Burk diagram and the calculated value of the apparent Michaelis constant, Km, was 2.14mM, greater than the corresponding one of the free enzyme, 1.98mM. Furthermore the activation energy decreases from 10.310cal/gmol for the soluble cellulase to 8.940cal/gmol for the immobilized one. Therefore, working with A. niger entrapped in polyalbumin a combined kinetic and diffusional mechanism of control takes place and the enzyme thermal stability is good for a prolonged process time. However, since product and substrate inhibition continue to play an important role, it would be better to concentrate the solution after the second step of reaction. Finally, experiments were carried out to determine the optimal length of cellulose saccharification process. The specific rate of glucose production r per mg of enzyme at different substrate concentration is plotted versus process time in Fig.4 and indicate that the conversion of amorphous cellulose is very rapid and almost 90% of the asymptotic biomass conversion occurs in 20 hours.

Fig.4—Saccharification yield vs. reaction time ●—Avicel; —CMC; ▲—Olive husks; ■—Straw To sum up, the body of experimental results suggests the following process layout: a) hydrolysis of biomass with a mixture of T. viride and A. niger, in soluble phase using a membrane reactor in order to limit product inhibition, b) subsequent conversion of unreacted oligosaccharides with an immobilized cellulase rich in β-glucosidase, such as A. niger, c) final ultrafiltration of sugar solutions for increasing the glucose concentration.

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REFERENCES (1) LADISCH, M.R. (1979). Process Biochemistry, 21–25 (2) ALFANI, F., CANTARELLA, M., SCARDI, V. (1983). J. Membrane Sci. 16, 407–16. (3) ALFANI, F., CANTARELLA, M., SCARDI, V. (1984). Energy form Biomass, Series E, 5, Palz W. and Pirrwitz eds, 336–43. (4) ALFANI, F., CANTARELLA, M., ERTO, L., SCARDI, V. (1982). In “Energy from Biomass”, Proceedings 2nd E.C. Conference, Strub A., Chartier P. and Schlesser G. eds., 1000–1006. (5) NELSON, N. (1944). J. Biol. Chem., 153, 375–80. (6) GIANFREDA, L. and GRECO, G. jr. (1982). Energy from Biomass, 3, Grassi G. and Palz W. eds., 260–65. (7) SCARDI, V., CANTARELLA M., GIANFREDA, L., PALESCANDOLO, R., ALFANI, F. GRECO, G. jr. (1980). Biochimie, 62, 635–43.

STUDY OF ENZYMATIC HYDROLYSIS OF ALKALI PRETREATED ONOPORDUM NERVOSUM C.MARTIN, M.J.NEGRO, M.ALFONSEL, F.SAEZ, R.SAEZ and J.FERNANDEZ División de Biomasa, Programa de Energías Renovables, Junta de Energía Nuclear. Madrid. Spain Summary The effect of a pretreatment by alkali on the enzymatic hydrolysis of biomass of Onopordum nervosum is studied. The optimum values of pretreatment parameters were experimentally determined in order to maximize the availability of cellulose fraction to enzymatic hydrolysis. Treatments were carried out at alkali concentration, temperature and reaction time ranging from 0% to 2%, 25°C to 150°C and 0 to 90 minutes respectively. Enzymatic hydrolysis of pretreated and unpretreated substrates was studied at 2 and 48 hours using a cellulase preparation from T. reesei QM9414 at a final FP activity of 18 IU/g of substrate. The higher cellulose conversion yield (about 78%) and saccharification efficiency (50%) were obtained when O. nervosum biomass was treated with a 1% alkali solution at 100°C for 10 minutes.

1. INTRODUCTION Biodegradation of lignocellulosic materials has become one of the most promising processes in the biotechnology field. The possibility obtaining this renewable resource in larges quantities, as well as the fast development of the technology for enzyme production and fermentation, permit the forecast of enzymatic hydrolysis of lignocellulosics as a feasible process from an economical and technical point of view. However, the characteristics of lignocellulosic biomass, mainly the crystallinity of native cellulose and its association with lignin makes the pretreatment of this material necessary to increase its susceptibility to enzymatic hydrolysis. Many physical and chemical treatments have been described in the last few years (1). Results reported by some of these show the effectiveness of the use of alkali to pretreat lignocellulosic materials with a similar composition to O. nervosum (2) (3). This endemic plant of the Iberian Peninsula can be considered an interesting lignocellulosic biomass source for its transformation to fermentable sugars due to its high crop productivity (20Tn/Ha) hardiness and composition (30–35% of cellulose, 65–70% of holocellulose and 15–19% of lignin) (4).

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The aim of this work is to determine the most effective conditions for a maximum cellulose recovery of solid residue after alkali pretreatment of O. nervosum biomass, as well as an optimum glucose yield in the enzymatic hydrolysis of this residue. 2. MATERIAL AND METHODS The dried thistle was hammer milled and sieved through 2mm. diameter. Pretreatments were performed at 100°, 120° and 150°C in a silicone bath using 1% or 2% NaOH solution with a final substrate concentration of 5%. Reaction times ranged from 0 to 90 minutes. Substrate composition, in cellulose and lignin, was determined by total hydrolysis with H2SO4 (5). Enzymtic hydrolysis was carried out at 50 C in 0.05M citrate buffer (pH 4.8) with a 5% substrate concentration. A cellulase preparation from T. reesei QM9414 was added to an enzymatic activity for each 100mg. substrate of 1.8UI (filter paper activity) and 4nKat ( β- glucosidase activity). Reducing sugars were analyzed by Nelson-Somogyi method and glucose by an enzymatic test (Boehringer Manheim) 3. RESULTS AND DISCUSSION The thistle, O.nervosum, used in this work contains 30% cellulose, 50% reducing sugars, 17% lignin, 10% ash and 7.8% proteins (other components have not been analyzed). The effect of different pretreatment conditions on solid residue recovery and reducing sugars, glucose and lignin content in the residue after treatment is summarized in Fig. 1. The yield of solid residue decreases sharply when substrate is treated at high alkali concentrations, with a maximum solubilization taking place during the first 30 minutes. Temperature also increases the extent of solubilization mainly when short reaction times are studied. Lignin fraction is more solubilized than hemicellulose or cellulose, although with severe pretreatment conditions even 50% of cellulose (Table I and Fig. 1d) can be removed. Under mild conditions (i.e. 100°C, 1% NaOH and 10 minutes) 30% of the total lignin and 35% of reducing sugars are removed, leaving 64.5% of solid residue with a glucose recovery of 77.5% (Fig. 1b). The relative enzymatic hydrolysis rate (at 48 hours) of the pretreated thistle is shown in Fig. 2 and Table I. Saccharification efficiency and cellulose to glucose conversion have been plotted versus alkali concentration for the different temperatures and reaction times used. Saccharification efficiency (SE) (6) and cellulose conversion (CC) have been calculated as follows: SE(%)=Gy/Gt CC(%)=100 (Gy/Gr) Gy=Percentage of glucose obtained in the enzymatic hydrolysis of pretreated substrate. Gt=(Cellulose content (expressed as glucose percentage) of untreat. subs.)/ /(Percentage of solid residue after pretreatment). Gr=Cellulose content (expressed as glucose percentage) of pretreated substrate

Study of enzymatic hydrolysis of alkali pretreated onopordum nervosum

1131

When the pretreatment was carried out at 25°C and 90 minutes the relative enzymatic hydrolysis of solid residue (evaluated at 48 hours) increases when increasing alkali concentration. At the highest concentration, saccharification efficiency and cellulose conversion were respectively enhanced, 1.6 and 2.4 times based on the corresponding values for unpretreated thistle (Fig. 2a). However, for 100°, 120° and 150°C, no significant differences were observed when alkali concentration was increased from 1% to 2%. Increments obtained for these temperatures reached values of 2.3 (SE) and 3.6 (CC) times based on unpretreated thistle (Fig. 2b and 2c). The effect of the pretreatment time depends on the severity of the other treatment parameters. For 100°C an increment in the reaction time produces a slight enhancement of the enzymatic hydrolysis rate. However, when higher temperatures are considered (120°C and 150°C) the effect is rather different (Fig. 2c, 2d and Table I). As can be seen in Fig. 2d a drastic decrease of enzymatic conversion takes place when times higher than 10 minutes are studied, with values for cellulose conversion and saccharification efficiency at 150°C and 30 or 90 minutes being even lower than that obtained for unpretreated thistle. This

Fig 1: Yield of reducing sugars, glucose, lignin and solid residue of alkali pretreated thistle based on original weight.

Energy from biomass

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Fig 2: Cellulose conversion (based on potential glucose in original material) after 48h. of enzymatic hydrolysis. behavior is difficult to understand taking into account the high delignification extent as well as the glucose recovery rate in the pretreated residue observed in these cases (Fig. 1d). The highest relative extent of enzymatic hydrolysis at 48 hours has been found when pretreatment was run under mild conditions (i.e. 100°, 120° or 150°C for 10 minutes and an alkali concentration 1%). Under these conditions saccharification efficiency and cellulose conversion reached values of about 50% and 78% respectively. Values for relative enzymatic conversion at initial rates (2 hours) reveal the same profile as that obtained at 48 hours (these results are not shown here).

TABLE I.- Influence of pretreatment of O. nervosum biomass in: glucose—yield based on potential glucose in original material (G); conversion of cellulose to glucose by enzymatic hydrolysis at 48 hours (CC); saccharification efficiency (SE) and Kg. of glucose after enzymatic—hydrolysis/Ton of dry thistle (G/Ton). Treatment G (%) CC (%) SE (%) G/Ton t T\NaOH 1% 2% 1% 2% 1% 2% 1% 2% 25°C – – – – – – – – 100°C 75 85 65 48 50 51 155 127 120°C 70 70 56 56 39 39 121 121

Study of enzymatic hydrolysis of alkali pretreated onopordum nervosum

150°C 25°C 100°C 120°C 150°C 25°C 100°C 120°C 150°C Untreated

65 90 65 55 65 75 66 62 66

58 – 64 62 44 67 60 54 5 100

78 18 61 69 19 38 68 29 7

69 – 58 33 4 53 78 54 6 22

50 16 40 38 12 29 45 18 5

1133

40 155 124 – 50 – 37 124 115 20 118 62 2 37 6 36 90 112 47 140 146 29 56 90 3 16 9 22 68

4. CONCLUSION From these results it can be concluded that alkali pretreatment under mild conditions greatly improves the enzymatic hydrolisis of thistle (the yield of glucose/Ton of dry thistle could be increased from 68Kg. for untreated substrate to 155Kg. under the most effective conditions studied) without a high economic and energetic input in the process balance. Due to the low β—glucosidase activity used in the experiments, further work with an improved enzymatic activity is necessary in order to opmitize the efficiency of hydrolysis. REFERENCES (1) CHANG, M.M., CHOU, Y.C. and TSAO, G.T. (1981). Structure, Pretreatment and Hydrolysis of Cellulose. Adv. Biochem. Eng. Vol. 20 15–41. (2) MACDONALD, D.G. et al. (1983). Alkali Treatment of Corn Stover to Improve—Sugar Production by Enzymatic Hydrolysis. Biotechnology and Bioengineering. Vol. 25 2067–2976. (3) GHARPURAY, M.M., FAN, L.T. and LEE, Y.H. (1983). Wood and Agricultural—Residues. Published for Isoltes by Ac. Press. (4) FERNANDEZ, J., MANZANARES, P. and MANERO, J. (1985). Onopordum nervosum boiss as a Potential Energy Crop. Published in these Proceedings. (5) DUNNING, J.W. and LATHROP, E.C. (1945). The Saccharification of Agricultural Residues. Ind. Chem. Vol. 37 24–27. (6) GOULD, J.M. (1984). Alkaline Peroxide Delignification of Agricultural—Residues to Enhance Enzymatic Saccharification. Biotechnology and—Bioengineering. Vol. 26 46–52.

THE ROLE OF MICROORGANISMS ISOLATED FROM FUNGUS-COMBCONSTRUCTING AFRICAN TERMITES IN THE DEGRADATION OF LIGNOCELLULOSE Dr. Harry Osore, B.Pharm. Ph.D.MPS., MIUPhar Chemistry and Bioassay Research Unit ICIPE Research Centre P.O.Box 30772, Nairobi, Kenya. Over recent years it has increasingly dawned on many Governments, that they cannot continue to rely on petroleum as a stable economical raw material to fulfil the demand for energy. The finite capacity of the liquid fuel reserves has accelerated research into new and renewable sources of energy (BLanch and Wilke, 1982). Both cellulose and hemicellulose are potential raw materials for the production of ethanol and other chemicals. However, efficient bioconversion processes for biomass, need to be developed before it can be considered as a challenging and suitable energy alternative to petrochemically-based materials. It has clearly been demonstrated that acid attack on Lignocellulose to yield fermentable sugars for conversion to liquid fuels gives rise to undesirable products (Crawford, 1981), and that enzymatic hydrolysis using microorganisms may represent a better alternative. Enzymatic saccharification is non-polluting and total saccharification can be achieved (Freer and Detroy, 1983). The major problem in this research still remains the release of bound cellulose from the lignin matrix (Osore, 1983). Lignin is a recalcitrant substance that encrusts cellulose that is more useful for conversion to fuels and chemicals. Studies of lignin decomposition therefore pose a serious challenge. This paper describes on-going studies at the ICIPE Research Centre, on the possible use of fungi associated with fungus-comb-construct ing higher African termites, for biodelignification of lignocellulose and as a source of high levels of cellutolytic enzymes for efficient saccharification of cellulose into sugars for ethanol production. We have grown species of Fusarium, Aspergillus, Trichoderma, and Termitomyces in a variéty of liquid media using different lignocelluloses and monomeric and dimeric lignin substructure model compounds. Fragment accumulation patterns of these carbon sources have been determined by analysing degradation products using HPLC and GC. A variety of enzymes involved in the cleavage of specific bonds in the lignin molecule have been assayed and their relative importance in the decomposion of the molecule assessed. Enzymes considered include Polyphenoloxidases, Cellobioxe Quinone Oxidoreductase, Cellobiose oxidase, and

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Oxygenases, such as H2O2– dependent Ligninase, as well as Cellulases and ßglucosidase. C-labelled Substrates have also been used to assess the pattern of evolution of 14CO2 and the degradation path-ways. The results so far point out that the fungus Termitomyces may represent a good industrial source of lignocellulose decomposing enzymes. The ability of different fungi to produce enzymes capable of cleaving lignin Linkages and for producing cellulose saccharifying enzymes will be discussed, with particular emphasis on the Lignin degraders. REFERENCES 1. BLanch, H.W. and Wilke, C.R. (1982). Sugars and Chemicals from cellulose. Rev. Chem. Eng. 1:71–119. 2. Crawford, D.L. (1981). Microbial conversion of lignin to useful chemicals using a Lignindegrading streptomyces. Biotechnology and Bioengineering Symp. No. 11. 275–291. 3. Freer, s.n. and Detroy, R.W. (1983) Characteristization of cellobiose fermentation to Ethanol by Yeasts. Biotechnology and Bioengineering 25: 541–557. 4. Osore, H. (1983). “Mission-oriented Research on the Biology and Biochemistry of microorganisms from African termites for improved biomass degradation”, Annual Report, ICIPE (1983).

III. IMPLEMENTATION (a) Developed Countries (b) Developing Countries

A BIOMASS PROJECT (GASIFICATION AND PYROLYSIS) FOR LOWER AUSTRIA DR.GEORG SCHÖRNER FORSCHUNGSINSTITUT FÜR ENERGIE- UND UMWELTPLANUNG The Austrian Research Institute for Energy and Environmental Planning Summary In the course of a research project for the Government of Lower Austria (the biggest province of Austria; 1.4 mill. inhabitants; with a considerable quota of forest and agriculture) our institute calculated in which way the forest and waste products could be used for energy purposes. Two processes are estimated to give the best results: gasification and pyrolysis. Today this could be the best way for conversion of biomass to fuel (gas, pyrolysis oil and solid fuels). By using in engines electricity is produced and heat for domestic purposes. Our institute worked out the following topics during our research work for this study: Capacity of biomass in Lower Austria for each village (agriculture residues, energy crops, wastes from household and industries; wood and wood products; regional distribution; temporal disposition etc.); Szenarios 1990 and 2000; Detailed international registration of the stateof-the-art-systems (gasification and pyrolysis); Computerized optimation models for regional distribution and application of such small (and possible mobile) units; Investment and operational costs, cost-benefitszenarios, planned state assistance and subsidies.

1. BIOMASSE Die Ausführungen und Berechnungen haben eindeutig gezeigt, daß in Niederösterreich, dem größten österreichischen Agrarland, ein beachtliches Potential an Biomasse bereitsteht, das heute nicht oder nur sehr unvollständig genutzt wird. Da selbst bei unveränderten Rahmenbedingungen mit einer Steigerung der Ernteergebnisse bis in das Jahr 2000 gerechnet werden kann, scheint es angebracht, dieses Energiepotential nutzbringend zu verwenden. Stellt man sich außerdem ein geändertes Anbauverhalten vor (mit Forcierung des Anbaus von Biomasse), so kann mit einem steigenden Biomassepotential gerechnet werden. Rund 36% des Energiebedarfes der niederösterreichischen Haushalte könnte mit Energie aus heimischer Biomasse abgedeckt werden.

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Daß hiebei mehr Arbeitsplätze im ländlichen Raum geschaffen werden und der Landbevölkerung Mehreinnahmen zufallen würden, ist unverkennbar und sollte auch aus dieser Sicht Ansporn sein, in diesen Bereich ein größeres Schwergewicht zu legen (abgesehen noch von der volkswirtschaftlichen Bedeutung für den Staatshaushalt und hinsichtlich von Deviseneinsparungen). 2. TECHNISCHE VORAUSSETZUNGEN Es gibt einige Bereiche, Biomasse (Feld- und Weingarten-biomasse, forstliche Biomasse usw.) in nutzbare Energie umzuwandeln. In der besprochenen Arbeit wurde auf der technischen Seite ausschließlich der Bereich Pyrolyse und Vergasung besprochen und abgehandelt. Energieumwandlung bzw. Gewinnung nutzbarer Energiemengen geht leider meistens mit der Abgabe von Schadgasen einher. Die Problematik des rapide anwachsenden Waldsterbens hat jedoch jedem deutlich gezeigt, daß unsere Luft nicht weiter belastet werden kann, bzw. wir danach trachten müssen, die bestehenden Belastungen zu reduzieren. Auf diesen Aspekt gilt es bei der Suche nach neuen Verfahren besonders Bedacht zu nehmen. Hiebei scheinen höhere Stufen der Verbrennung (Pyrolyse und Vergasung) bessere Bedingungen für den Umweltbereich zu bieten. Weiters sollen neue Verfahren auch die Möglichkeit bieten, vielfältige Inputprodukte (wie Biomasse, Müll, Sägenebenprodukte usw.) zu verwenden. 3. NUTZUNGSGRAD UND WIRTSCHAFTLICHKEIT Niederösterreich ist ein großflächiges Agrarland mit in vielen Teilen qeringerer Siedlungsdichte. Daher kommen Großkraftwerke ansatzweise nicht in Frage, da einerseits die Transportkosten für das Ausgangsmaterial zu groß sind und die umgewandelte Energie zu weit verteilt werden muß. Zu klein sollten die angestrebten Anlagen auch nicht ausgelegt werden, da sonst die Energieumwandlungsprozesse nicht optimal gewährleistet erscheinen (siehe auch der Problemkreis: Zunahme der Schadgasbildung bei der Einzelofenheizung). Daher erscheint das dezentrale Kleinkraftwerk die ideale Form zu sein. Zur Frage “Wärme oder Strom”? hat die Studie an Hand verschiedener Bereiche die Möglichkeit gezeigt, Landes- oder Gemeinderäume mit der Kraft-Wärme-Kopplung energetisch zu versorgen. Daß dies in gewissen Teilen des Landes nicht ganz oder nur teilweise geht, schmälert nicht das große Potential, das hier in dieser Versorgungsart liegt. Strom als alleiniges Endprodukt sollte nicht in Erwägung gezogen werden, da man hier lediglich auf einen Wirkungsgrad von maximal 35 bis 40% kommt. Eine Wärmegewinnung ohne Stromerzeugung kommt nur dort zum Zuge, wo in Räumen ein gesicherter Absatz an Nah- und Fernwärme gewährleistet ist. Da die rasche Ausbreitung Von Fernwärme durch nicht vorhandenen Anschlußzwang bzw. durch die hohen Investitionskosten der “klassischen Leitungsnetze” (am Rande der Rentabilitätsgrenze)

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nicht gegeben ist, zielt die Richtung hin zu einer Kombination von Stromerzeugung und Rest- bzw. Abwärmenutzung. Dadurch ergeben sich Standorte für eventuelle Anlagen in der Nähe von größeren Siedlungsräumen, um die Ab- bzw. Restwärme in möglichst kurzen Leitungen zu verwerten. Aus der Sicht des Stromes ergeben sich keine spezifischen Standorte, da die Einspeisungsmöglichkeit ins Netz an vielen Stellen gegeben ist bzw. leicht geschaffen werden kann. Die Transportkosten das Ausgangsmaterials stellen einen Kostenfaktor dar, haben aber durch die relativ kurzen Wege nicht das Gewicht, wie man bisher vermutet hatte. Eine Transportflotte steht heute im ländlichen Bereich bereit und könnte durch einen Einsatz in der “toten Zeit” zur größeren Rentabilität der bäuerlichen Betriebe genützt werden. In der Studie wurden verschiedene Verfahrensmöglichkeiten hinsichtlich des Einsatzes von Vergasungs- und Pyrolyseeinrich-tungen untersucht. Aus der Sicht der Volumensbewältigung können bewegliche oder halbstationäre Anlagen als ideal bezeichnet werden, in der Lage zu sein, den Erfordernissen zu entsprechen. So wäre es etwa möglich, ein transportables und somit speicherbares Zwischenmedium zu erzeugen oder den Strom direkt lokal ans Netz abzugeben. Zwar ist ersteres aufgrund verschiedener Schadstoffanteile noch nicht als ausgereift zu betrachten, so könnton aber in den Folgejahren (falls es zu einer Realisierung der beweglichen Biomasse kommt und somit ein Transport des Biomasseausgangsmaterials praktisch nicht mehr notwendig ist) diese Umwandlungsprodukte ebenfalls in bestehende Anlagen eingebracht werden. Derzeit scheinen die besten Möglichkeiten in der Kraft-Wärme-Kopplung zu liegen, bei Anlagen, die auf Basis Biomasse betrieben werden. Der Standort dieser kleineren Anlagen sollte am Rande größerer Siedlungen sein, um die anfallende Wärme zu nutzen, wodurch ein Gesamtnutzungsgrad bis zu 90 % entsteht. Bei der Erzeugung eines maximalen Strompotentiales könnte das Abnahmeproblem der Restwärme minimiert werden, um somit eventuelle Rohrnetze klein und kostengünstig auszulegen. Abschließend soll erwähnt werden, daß die Ausgangsbedingungen, wie die Studie gezeigt hat, als überaus gut zu bezeichnen sind, Biomasse zur großvolumigen Energieerzeugung heranzuziehen. Bei der Forcierung des Bereiches sollte jedoch eine ausführliche Planung vorgezogen werden, die die Energienutzung mit dem Umweltgedanken verbindet (da das eine mit dem anderen als uhtrennbar angesehen werden sollte). Die Wirtschaftlichkeit einiger Varianten eines Planungs-beispieles war erstaunlich hoch und wurde in der Studie ausführlich diskutiert.

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NEW DOMESTIC RENEWABLE ENERGY THROUGH HIGH TECHNOLOGY OF BIOGASES O.Kuusinen NESTE OY ESPOO, FINLAND Summary My poster deals briefly with a “new”, also internationally so, especially powerful possibility of energy. Biogases, which already nowadays are produced from nearly all organic materials in kilowatt and increasingly bigger megawatt effects, offer great readiness, when rapidly taken in use, in the generation of e.g. electricity, cooling, heating, drying, hydraulics and pneumatics. This energy is gained from home-produced raw materials or all their wastes, and can be produced in most countries. Microbiologically obtained, economical also in large-scale processes, biogases proper containing 60–80 % methane burn more effectively than different kinds of thermochemical (biomass—etc) gases in burner and boiler or engine systems. We can therefore talk about biogas economy and multiple power plants run by “molecular power stations”. References can be found in very many countries. In this way solar energy can be harnessed by a natural accumulator for known and absolutely reliable end uses.

1. DEFINITION In using the general term of “biogases”, we include here all gaseous fuels Which are either obtained microbiologically (biotechnically) from different organic materials, or thermochemically from biomasses. Even though the previously mentioned forms are produced in nature, it is possible to speed-up the process of splitting the molecules. When speaking of this substance, we are mainly referring to marshgas and other anaerobically produced gases which contain methane, such as those found in refuse dumps and mines, or those which come from sewage sludge digesters, even though the general term “biogas” would be more salable. Both the carbon monoxide and hydrogen contained partially oxidized gases, and the pyrolyzed gases represent the thermochemical group. 2. SOURCES As in nature, we also can produce biogases from plant and animal wastes in completely oxygen-free circumstances and under various temperature conditions. In addition, we can use biomasses which have been cultivated for this purpose. In our processes all these

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organic carbon-containing substances are fed into suitable reactors after they are ground, and the produced gases are further purified if deemed necessary. Because energy transfer in the form of gas is cheaper than in the form of heat/users can be situated far from reactors/particularly if the gas is in enriched form, or there are huge amounts in question. 3. APPLICATIONS Even though biogases differ from one another chemically, they can be burned in mostly the same ways: e.g. in boilers or in combustion engines (including gas turbines, Stirling etc). At present, the best possible method is the dual-fuel system. If, for some reason,the supply of biogas is disrupted, or if it is from the beginning more economical to build a plant of more suitable size, it is possible to use for example petroleum products or natural gas as a second fuel. A correctly built burner or engine adaptation shifts automatically to use the reserve (and ignition) fuel. Besides producing heat, both adaptations can be combined with electricity production, hydraulics, pneumatics or heatpumping. This means again cooling and drying possibilities and, if needed, additional heating. 4. MARKETING Biogas potential has already been partially charted in Finland and it appears to be very large. Its use is mainly connected to agriculture, the home and organically-based industries. Biogas reactors can be found in all of those sectors in Nordic Countries, in addition to those that are sold under international licences. All the equipment, also the small sized, will become less expensive as the choice of materials grows. In most cases we obtain the biogas (nearly) free of charge, from for example water protection processes. In the Federal Republic of Germany, there operates a large 10MW biogas heatpump, which takes the heat from the same place after the waste water is purified. Because the time of “molecular power stations”, multiple energy plants and biogas economy has begun, I urge the formation of the “International Biogas Society” in order to speed-up all development in this field. 5. FINLAND 1984 General The oldest sewage plant in our capital Helsinki has been producing biogases by the anaerobic method since 1932. This plant was the first one to do so in the Nordic Coutries. In addition to some fuel experiments conducted on cars in the 1940’s and ‘50’s, biogases from the newer reactors (digesters) have been continuously used when necessary, especially to rotate 200–1000kW electric generators. The increase in the price of oil has also led to some use of biogases for heating in agricultural, domestic and industrial sectors. In the same way, the use of air compressors with a combustion engine and “cost free” biogases at a sewage plant has been found to be so economical that more are planned, in spite of cheap nuclear power. The rotation of the cold compressor (the main

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component of the heatpump system) has also been taken into our calculations; the same sewage flows usually contain raw materials for the biogases as well as heat for the heatpump. In addition to sewage, the first experiments to collect biogases from refuse tips and marshes are just about to commence in Finland. The anaerobic gasification of the biomass cultivated for this purpose has also been planned, in addition to the three different types and dissimilar sizes of pyrolize-gas plants already existing. Types of Biogas Reactors So far, there are some 14 biogas plants in use in the 84 towns in Finland. In addition to this, 6 biogas reactors are also in use in industry, and 7 in agriculture. The larger biogas plants in the towns are most frequently concrete constructions built on the spot, whilst those used in the food and forest industries are made of steel. Smaller steel constructions (of approximately up to 150m3) mainly suitable for the thicker domestic and agricultural sludges are produced industrially in shorter series. There are about 10 of these in use in Finland/and a similar number, or licences, have been sold to neighbouring Sweden, Denmark and the Soviet Union. Because biogas yields are high and production costs low from those reactors, many enquiries about them are now also being received from overseas. Uses and equipment The boilers for the burning of biogases are mainly Finnish made, as is the world’s smallest 15kW dual-fuel burner. When the gas supply is disrupted for some reason, the burner switches over automatically to burn for example light fuel oil and then back again when the normal supply is resumed. Motors of a corresponding dual-fuel type (e.g. gasdiesel) have only been used in the larger sizes. However, because of the aforementioned reliability and efficiency, attempts are now being made to choose smaller ones too for the same reasons. With the dual-fuel possibilities there is no need to store gas, and storage is used only in large town plants. Until now purification of the biogases is limited. In spite of our cold climate it is not even dried for the short underground transfer by plastic pipe. 6. COLLABORATION Our company is already in collaboration with many Finnish and foreign experts and manufacturers, in order to rapidly and vigourously develop biogases for the benefit of everybody.

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NEW DOMESTIC RENEWABLE ENERGY THROUGH THE HIGH TECHNOLOGY OF BIOGASES

Both the burner and/or engine shift automatically to the back-up fuel when necessary DUAL FUEL SYSTEMS: • Guarantee operations in the case of biogas disruption • Enable optimum plant dimensioning even during initial phase when biogas supply is limited • Safe also in the event of possible fluctuations in CH4 content of biogas COSTS: • Biogas almost free of charge as a by-product of water protection processes • Storage for fuel oil is cheaper than for biogas

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• Biogas transport is more economical than transport of hot or cold water (or steam) in district heating or cooling systems • Prices for reactors and equipment will go down as development proceeds t is time to form an “INTERNATIONAL BIOGAS SOCIETY”! WHERE: The biogas system is feasible almost every-where when YOU want more “molecular” power stations”, multiple energy plants, and biogas economy.

PROSPECTIVE METHODOLOGY ADAPTED TO GLOBAL BIOMASS PROJECT CHOICES AND INTEGRATION. (MODELISATION OF A BIOMASS VALORIZATION PROCESS) P.MATARASSO and J.P.TABET Laboratoire Mixte CNRS-AFME “Modèles d’économie physique et de prospective” Summary An agrosystem modelisation is proposed which takes into account technical, ecological and financial equilibriums. This methodology, illustrated by a case study dealing with substitution of imported fuels and electricity by biomass, is more adapted to a real productive system representation than classical econometric models. It can be an answer to many problems met during global productive system design and management. The model used has been implemented on an interrelated local and big computers system.

1. INTRODUCTION The design, assessment and planning of a biomass project requires the handling of a very complex situation in which agricultural, technical, economical and ecological choices have to be made and carefully matched together. These problems and more generally any problem related to the development of renewable resources or to the improvement in man-made ecosystems have led us to the definition of global models devoted to integrated development policies studies [1,2]. Theses models are built around a representation of complex global productive systems which attempt to unify concepts used in ecological modelisation and macroeconomy [3,43. The methodology is based on the representation of the main physical and financial balance-sheets equilibrium. That is to say : – annual production and consumption balances for different circulating goods transformed within the agrosystem (energies, materials, agricultural goods, etc…) – periannual balances related to these goods (storages). – periannual balances related to the modification of the productive equipments (building, dismantling or transformation of the equipments required by the transformation activities).

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– annual and periannual financial accountancy balances concerning each sector. It should be emphasized that, at a given level of technology and “external world”, these equilibriums are a peremptory necessity, no matter what the choices of the human collectivity are. 2. THE MODEL In a very simplified way, it can be said that these models represent the technical and financial coherences and equilibriums through a five different nomenclatures series: – a list of goods represents the aggregates of produced or consumed objects; – a list of activities represents the aggregates of productive acts ensuring the goods consumption and production; – a list of equipment sets defines the activities requiring special equipments which have to be built, transformed or destroyed in order to modify the productive system structure; – a list of sectors enables the modelisation of institutional or geographical activities grouping by means of the specified exchanges which are allowed between sectors; – a list of financial operations introduces monetary exchange circulations between sectors. This model enables: (1) to represent all goods circulations and transformations within the different activities, taking into account the different levels of equipments for a present productive system. (2) to forecast this productive system through linear programming taking into account new technologies, introducing new external constraints (for instance outside prices…) and researching various types of optimisation (minimal energy dependence research, maximisation of the population sustained by the agrosystem, best external trade balance…). The model is then used as a representation for future productive systems. (3) to compute feasible transitions from the present to the future system, specifiying what is the state of the productive system period by period (activities, transformations, financial variables). This methodology has been tested on a numerical model which outlines the different typical problems met in the rural areas of both developped and developing countries. We present here a simulation of rural micro region transformations, going from a strong energy dependence to a complete autonomy (thanks to different biomass crops and conversion devices). 3. DESCRIPTION OF THE EXPERIMENTATION Though the exemple presented here does not correspond to a localised territory, it can be regarded as realistic and representative of the French rural districts situation.

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The initial system can be described as a 20000 hectares rural area which are divided into 14000 hectares of agricultural land and 6000 hectares of forest inhabited by 14000 people. Though this population is almost totally self-sufficient as for agricultural products, it imports most of its manufactured goods and all its energy. These imports are counter-balanced by exports, mostly agricultural products. Specifications of the numerical model are the following ones: – 86 circulating goods (agricultural, energy related and metallic manufactured goods, goods related to the available equipments, goods necessary for the construction of the different equipments, etc.) – 73 productive activities (agricultural, energetical, semi-industrial ones…), 32 of whiwh use a special set of equipment – 60 transformations (construction and dismantling of the equipments) – 4 different types of financial operations (loans, etc…) – 2 sectors (the first one represents the studied system, the second one the ouside world). The purpose of the experimentation was to reach energy self-sufficiency through the use of flat-plate solar collectors and a better land valorisation via biomass production. This result was achieved through a five annual period evolution under a maximisation of savings criterium during the transformation. The agricultural structure and energy systems of the initial and final systems can be compared by the following arrays (Fig. 1, 2, 3). Some details of the transition are given on Fig.4 . 4. CONCLUSION We have tried to build a model based on a systematic and unambiguous structure of concepts which allows a dynamic representation of any productive system. The experimentation undertaken has proven that this can be done at a limited computer cost: for the proposed example. with around 1200 variables and 950 constraints, we needed 3 minutes of CPU time for 2100 iterations of the MPSX code running on IBM 3081-D.

Fig.1

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Figure 4: Evolution, during the 5 years long tranformation, of some energy productive and industrial equipment sets. REFERENCES [1]—P.COURREGE, J.DEFLANDRE, P.MATARASSO (1982) “Modèles macroéconomiques pour la prospective libre”, report available at the documentation center of CNRS. [2]—P.COURREGE (1985) “ATHEMA: Modèle macroéconomique pour la prospective libre”, manuscript submitted to publication. [3]—J.DEFLANDRE (1984) “Prospective et modèles de developpement”, 4• Seminar on Solar Energy, Trieste (10–21 September 1984). [4]—P.MATARASSO, F.VALETTE (1984) “Analysis of systems adapted to rural development”, 8* Seminar on Agriculture and Management of Natural Resources, Milan (17–18 April 1984).

AN ECONOMIC ANALYSIS OF THE ENERGY VALORISATION OF CEREAL STRAW IN FRANCE V.REQUILLART National Institute for Agronomic Research Rural Economics Laboratory 78850 Thiverval-Grignon (France) Summary The notion of an available straw vein, although it may provide an approximate idea of the scope [5 million metric tons for France], is nevertheless insufficient. Indeed, it gives no indications as to the cost of access to the resource. The latter, depending on whether or not there is intra-consumption, varies between 30 and 50 French francs and between 100 and 120 French francs respectively. From the point of view of energy valorisations, straw has a certain number of points in its favour, and the economic interest of the course is fairly considerable. Schematically, utilisation on farms is of considerable interest from the economic point of view, and utilisation off the farm is possible in certain cases, although the economic interest is then more limited. The production of pellets seems to be possible in lucern and pulp dehydration factories. In spite of these economic advantages, development in the field is slow [in 1983, approximately 100 000 metric tons of straw were used in France for producing energy]. Analysis of the behaviour of the various parties participating right along the course makes it easier to understand the slowness of this development. The main delaying factor is the insignificance of the individual economic stakes involved, which stems from the atomisation of the resource.

INTRODUCTION Cereal straw has a great many advantages insofar as concerns its valorisation in the energy field. It is an agricultural by-product, dry when harvested [maize canes are excluded in this context], and is available in large quantities; access and harvesting are easy. However, in spite of these advantages, one cannot fail to observe that the development of these utilisations has been extremely slow. It is estimated that, for 1983, approximately 100 000 metric tons of straw were used for producing energy. For this reason, after having set out the economic interest of the various courses for valorising straw, we will analyse some of the delaying factors which oppose their development.

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1. The supply of straw In 1980, the surface area planted with cereals was 7.6 million hectares [approximately 18.6 million acres], which represents an average produce of approximately 26 million metric tons of straw. This produce is distributed between about 600 000 farms. Such dispersion over a very large number of economic participants is one of the main characteristics of the vein. Obviously, part of this produce is already used, mainly for stock farming purposes [see table 1]. of these 26 million tons of straw produced on average, about 5 million tons are available for new uses, without in any way competing with traditional utilisations. This evaluation is an average value which may vary enormously from one year to the next, and concerning which the medium term development is not known. Also, this value gives no information at all on the cost of access to the biomass. For this, supply graphs must be drawn in order to obtain a ratio between the price and the quantity available. The drawing up of supply graphs at regional level reveals the revenue phenomena—on the one hand the differential rent resulting from the various production conditions of the different farmers and, on the other hand, the absolute rent corresponding to the acquisition by the producer of a revenue without labour. In this way, the economic behaviour of the farmer will not be the same if he uses straw at its mineral value (at about 30 to 50 francs per ton, depending on the species), whilst if he sells it, the price will rarely be less than 100 francs per ton, which represents an acquisition of an income amounting to approximately 50 francs per ton. 2. The economic interest of courses valorising straw for energy 2.1. A few definitions From the point of view of the producer of straw, the threshold cost of straw represents the minimum selling price of the resource (below this value, the sale would lead to a loss for the seller). From the point of view of the utiliser, the interest price represents the maximum purchase price of the resource (beyond this value, the purchase would lead to a loss for the utiliser). The difference between the interest price and the threshold cost, after deduction of packing and transport costs, represents the economic surplus produced by the course. 2.2. Results The main results are set out in tables 2 to 4. They can be summarised as follows: – On the farm, the courses are highly profitable. Indeed, on the one hand, the cost of the resource is low (70 francs per ton in a great many cases) and, on the other hand, the cost of competitive energy is high. Finally, one participant only intervenes, which means that he will acquire the total amount of the surplus. – Off the farm, the courses are generally less profitable. On the one hand, the cost of the resource once it has reached the utiliser is amplified by transport costs and by rents. On the other hand, the competition of the other energy vectors such as heavy fuel, natural

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gas, coal and electricity, is extremely severe. The surplus provided by the course is thus less reliable and, further, this surplus must be shared between the various participants. – The “straw pellet” course should also be mentioned. Indeed, whilst the threshold cost of pellets produced in a specific factory may at present be too high, the same does not apply to pellets produced by lucern and pulp dehydration factories, which can manufacture pellets at marginal cost. Consequently, it would appear possible to create, around dehydration plants, poles of utilisation for fuel pellets, both at individual and at small collective levels. Nevertheless, in spite of the micro-economic interest of the courses, the development of energy utilisations for straw is fairly slow. In order to explain this situation, the economic behaviour of the parious participants who intervene right along the courses must be examined. 3. The economic behaviour of the participants 3.1. Farmers Mobilisation of farmers for these courses has been weak, and the reasons for this are various: The resource is atomised into several hundred thousand farmers, which means that there is no monopolisation of the resource. Consequently, whilst the overall economic stake may be high, the individual stake is low. The energy valorisation is not the only possible valorisation; competition is considerable, especially with certain zootechnic utilisations which are developing fast. The economic behaviour of farmers differs according to whether there is intraconsumption or sale. If there is sale, the desire to acquire an income leads to an increase in the costs of the resource, and this slows down the development of the collective courses. If there is intra-consumption of the straw, certain techniques [such as household heating stoked manually with bales of straw] may seem archaic. In any case, these courses demand more work than other forms of heating. Also, for such utilisations, wood represents very strong competition. Finally, the professional bodies and farmers’ unions have has a reserved attitude towards the energy valorisation of straw because of the possibilities of competition with straw for stock farming. 3.2. Utilisers Utilisers, when they are not farmers, seek excellent security of procurement. Given the characteristics of the vein [see § 1], procurement security in this case is weaker than that ensured by other forms of energy. Utilisers do not favourise straw on the pretext that it is a national resource obtained from the biomass and, it must be remembered, the competition exerted by other forms of energy [and upheld by powerful companies] is very strong.

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The use of straw in general is more stringent than the use of traditional forms of energy, which means that the economic interest must be sufficient to justify the extra workload. Investments made to use straw are generally higher than those required for using other vectors. During periods when capital is short, this state of affairs in no way facilitates penetration of the straw vector. 3.3. Companies The big companies in the energy field have had an extremely reserved attitude and have hardly been innovational in this field. Only a few small or medium-sized firms, which did not always have sufficient financial means, have attempted to conquer this market. Overall, companies have not, as could have been hoped, acted as a driving force in developing this field. CONCLUSION Delaying factors in the development of the energy valorisation of straw have thus been extremely numerous, and have come into play at all levels of the course. Amongst these delaying factors, the main one has been the low level of the individual economic stakes involved [globally, the stakes are very high, and the foreign exchange economy resulting from the valorisation of 1 million tons of straw pellets comes to approximately 460 million French francs]. On account of these, in case of a voluntanst policy, an objective of 600 000 tons of “straw energy” by the mid eighteen nineties would appear to be reasonable. The courses to be favourised are utilisation on farms [heating and drying], the use of pellets close to dehydration units, and certain collective utilisations in regions where competition from other vectors is less severe. In relation to other agricultural by products, straw was a priori the most well suited from the point of view of energy valorisation. The complete analysis which has been made of the course thus leads one to adopt a reserved attitude insofar as concerns the short-term development of the energy utilisation of other agricultural by-products. Bibliography REQUILLART Vincent 1984—La valorisation énergétique des pailles de Céréales. Pyc.Editions— AFME—Paris. 157 p. SOURIE Jean-Claude 1981—Production de paille de céréales comme source de combustible et produits associés. Etude n° 2: Méthodologie micro-économique CCE—DGRSE—projet E contrat n° 326–78–10 ESF, 38 p+annexes.

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Table 1—Straw utilisation in France – Production=28 Mt – baled 18 MT – Animal bedding: • cattle 14.5–15 Mt • ovine 1.3 Mt • horses 1.5 Mt – Others: • mushroom 0.15 Mt • feed (pellets) 0.1 Mt • feed [NH3 treated] 0.1 Mt • energy 0.1 Mt • exportation 0.1 Mt – non harvested 8 MT – burnt 1 Mt – soil incorporated 7 Mt

AVAILABLE FOR NEW USES=5 Mt

Table 2—Straw in bales—on Farm uses Use

Straw required Alternative proposal

Animal feed straw 10kg/day treated by NH3 Domestic heating – manually stocked 15–20t/year – automatically stocked 15–20t/year Maize drying 100t for 800t of maize [*] for new installations [**] marginal cost

Treshold cost of straw FF/t

Interest price [*] FF/t

hay

70 (**)

200–500

oil oil liquefied gas

70 70 150

550 250 350

Table 3—Straw in bales off farm uses Use Maize drying

Straw required

Alternative proposal Treshold cost of straw Interest price FF/t FF/t FF/t

320t for – natural gas 270t of maize – liquefied gas Dehydratation 6000t for {1 ucern— 10000t of – coal sugar beet pulp) l ucern – heavy fuel oil Col lective 5–8t/ – oil heating accomodation – coal District heating – – coal

>150 >250

250 [275]* 250 [375]

>250

250–300

>250 >300 >300 >300

450 350 0–50 300–350

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* with grants

Table 4—Straw pellets Use

Straw required

Al ternative proposal

Interest price FF/t

Animal feed – l ucern 600–700 Individual heating 10–12t/year oil 500–650 Collective heating 5t/accomodation heavy Fue 1 oi1 450 – the price of pellets is ≥ 600FF/t – treshold cost of straw pellets produced in dehydratation factories is minor than they are produced in specific Factories.

INTEGRATION AND ASSESSMENT OF BIOMASS RESEARCH INFORMATION BY USE OF SYSTEM ANALYSIS J.W.Mishoe Professor of Agricultural Engineering University of Florida Gainesville, Florida 32611 USA Summary The Institute of Food and Agricultural Sciences (IFAS) at the University of Florida, in cooperation with the Gas Research Institute is operating a research program to develop an econonically feasible system to produce and convert biomass to methane for use as energy. The research methodologies include using systems modeling and computer simulation to aid the researchers in setting research priorities and to assess the impact of new information on the performance of the system. The interactive systems model, BIOMET, consist of process oriented models for the crops of Napiergrass and waterhyacinth and we are currently including reactor driven conversion models. In addition, biomass transportation, biomass harvesting, economics and energetics are included to produce simulated outputs of systems economics, energetics, methane yield and biomass yield as influenced by management and environmental conditions. Simulation studies indicate that water-hyacinth yields vary from 37t/ha to 63t/ha in response to harvest schedule. Transportation cost for Napiergrass contribute significantly to gas cost, however by increasing yields on fields sites close to the conversion facility can help reduce the total cost.

1. INTRODUCTION Biomass is a source of energy that can provide an important contribution to the energy supply in developed countries with regions having a favorable climate. Feedstocks can be derived from various sources including waste and biomass grown specifically for energy production. Options exist that combine biomass production with other necessary operations such as using waterhyacinth to aid in cleanup of waste water or eutrophic lakes by growing the crop directly in the enriched water. The resultant biomass can then be converted to high quality energy by the use of anaerobic digestion for methane production. The University of Florida in cooperation with the Gas Research Institute is conducting a research program with the goal of developing a commercially viable system for the

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production and conversion of biomass feedstocks to pipeline quality methane gas (4). As part of the research program a systems analysis project was implemented to assess the cost sensitive parameters to allow priority research to focus on areas with the greatest potential of reducing gas cost. Members of the systems teams consist of engineers, economists, statisticians, and computer specialists working with the experimentalists. The system under study consists of a central conversion system with biomass produced on a regional basis and transported to the conversion facility after harvest. The components of the system can be defined as the biomass production, harvesting, transportation, and conversion. To analyze the system we have defined the economic and energetic characteristics of each component and in the case of the crop production and the conversion, we also model the performance of the component in response to component design, management, and environmental inputs. The objective of this paper is to describe the approaches and methodologies used by the systems group and to present selected preliminary results of the analysis. 2. METHODOLOGY The component models have been integrated into an overall system level model called BIOMET (3). The first operation in the interactive model BIOMET is to define the configuration of the system to be simulated. The options include crop selection, field size and location, conversion reactor type, harvester type and size, transportation type and size, costing parameters, economic parameters, and gas demand (Figure 1). BIOMET uses this information to select the number of trucks and harvesters needed and to estimate a harvest demand schedule. With this configuration the simulation begins and the ability of the system to preform as demanded is determined. If any component becomes limiting, the appropriate economic and energetic factors are recorded. The output reports summarize the actual performance of the system, reporting biomass and gas yields and the respective costs. BIOMET differs from essentially all analysis procedures found in the biomass literature in that the simulation of the physical and biological processes are included in the analysis. This capability is important because it allows for the analysis of various management factors that cannot be considered otherwise. For example, variations of sequential management inputs such as fertilizer application, harvest rates, planting density, etc. can be used to determine the resultant crop growth because the crop model can integrate the accumulative effects of weather and management. Currently BIOMET includes crop models for Napiergrass and water-hyacinth. Each crop model consist of component models to maintain the growing medium balance for nitrogen and water and for carbon, water, and nitrogen balance of the plant. Each of the crop models are different based upon the functional and parametric changes necessary to accurately describe each crop, however the basic carbon balance structure of the model can be expressed in a generic format. For each crop (1) where dw/dt is the rate of biomass accumulation, Pg is gross photosynthesis, Ro is the are the conversion coefficient of maintenance respiration, W is the total biomass,

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efficiency terms and S is the rate of biomass loss form the crop due to senescence. For a given crop type, the coefficients can be defined as a function of crop stage and environmental temperatures. Pg is defined as a function of light interception and the crop stresses. This takes the form of Pg=K R fNfWfTfL (2) where K is a crop coefficient, R is the ambient solar radiation and fN, fW, fT, and fL are functions ranging in value from 0 to 1 that are related to plant nitrogen, plant water, air temperature, and crop light interception, respectively. Figure 2 compares waterhyacinth model simulations to measurements of waterhyacinth growth for the conditions used in the simulation.

Figure 1. Block diagram summarizing available menu selections from the BIOMET program The simulation of the conversion process in the current example analysis is limited to an overall efficiency of the conversion system based upon the quantity of biomass input. The conversion type and size was held constant and the economics were based upon the utilization of the selected facility. In BIOMET an estimator model uses the monthly gas

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demand to determine the total annual biomass requirements. From the biomass demand and the user-supplied monthly gas demand, a monthly biomass demand is computed. Once the simulation begins, if biomass demand cannot be met the gas output is reduced and the variable cost are computed based upon the actual throughput. The BIOMET cost model calculates the initial investment (for biomass feedstocks and methane production) prior to simulation based upon user-defined scenarios, and then accumulates the variable costs during simulation. The levelized cost model uses these costs to calculate the levelized-cost-of-service price. Initial investment and variable cost are calculated separately for Napiergrass production, harvesting, and for conversion. Waterhyacinth costs are based on a winch-boom design (5). The user is limited to a choice of four sizes estimated to produce feedstock for 0.1, 0.5, 1.0, and 3.0 10BTU/year conversion plants. Capital investment and variable cost are estimated based on the usersupplied geometry, size, and operating parameters. Napiergrass production, harvesting, and transportation costs include both capital investment and variable operating costs. Components of the initial capital investment include: harvester, trucks, and initial land rental, crop management (fertilizer, pesticides, etc.), labor, fuel, and machine operating maintenance.

Figure 2. Example simulation using the waterhyacinth model from BIOMET (Data collected by Reddy (1)). 3. RESULTS AND DISCUSSION To examine the cost sensitivity of biomass due to transportation, BIOMET was used to simulate a 3200ha farm with the conversion cost, numbers of harvesters, and production cost held constant. In Table 1 only the number of trucks varied to meet the distance requirements. The biomass cost increased from $2.11 $/10BTU using six trucks to 4.63

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$/10BTU using 70 trucks with to distance was changed from 0.1km to 100km. In the second example the distance was help fixed at 20km and the number of trucks were varied from 9 trucks to 31 trucks (Table 2). Below 19 trucks the transportation was limiting and above this excess trucks were available. Because capital cost are a minor part of the total production cost results indicate that capital intensive transportation that reduce variable cost can reduce total transportation cost. From a cost viewpoint it is important not to allow transportation to limit the system.

Table 1. A 3200ha Napiergrass farm various distances from the conversion site (2). DISTANCE TRUCKS DISTANCE TRAVELED CAPITAL1 COST VARIABLE1 COST Km 103km —$/106 BTU— 0.1 10 30 60 100

6 12 25 44 70

60 1212 3540 7031 11686

0.12 0.12 0.15 0.18 0.21

1.99 2.24 2.73 3.46 4.42

Table 2. Simulations of a 3200ha Napiergrass system 20km from the conversion site (2). NUMBER BIOMASS OF TRUCKS HARVESTED t/ha

DISTANCE TRAVELED 103km

CAPITAL1 VARIABLE1 SYSTEM2 COST COST COST 6 —$/10 BTU—

9 13.5 567 0.12 12 20.1 1102 0.12 15 26.3 1778 0.13 19 31.9 2376 0.14 31 31.9 2376 0.15 1. The capital and variable cost included are for biomass production. 2. Includes a constant cost of 4.39 $/10BTU for conversion.

4.05 3.06 2.60 2.48 2.49

10.04 8.23 7.32 7.01 7.03

The development of BIOMET is an on going activity that has not been completed. It however is a very useful tool for integrating new research information and determining the impact on the overall performance of the system. Results indicate that methane produced from biomass can be cost competitive with other energy sources. It however will require the continuation of focused research efforts to develop the necessary technologies and the procedures to manage these technologies. 4. REFERENCES 1. Lorber, M.N., J.W.Mishoe and K.R.Reddy. 1984. Modeling and analysis of waterhyacinth biomass. Ecol. Modeling 24:61–77. 2. Mishoe, J.W., W.G.Boggess and D.W.Kirmse. 1984. BIOMET: A simulation model for study of biomass to methane systems. Proceeding of the IGRC. Washington. D.C. USA. 10 pages.

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3. Mishoe, J.W., M.N.Lorber, R.M.Peart, R.C.Fluck and J.W.Jones. 1984. Modeling and analysis of biomass production systems. Biomass 6: 119–130. 4. Smith, W.H., P.H.Smith and J.R.Frank. 1982. Biomass feedstocks for methane production. In: Proceeding of 2nd EC Conference on Energy from Biomass. Applied Science Publ., New York, USA. pp122–126. 5. Warren, C.S., etal. 1984. Evaluation of the lake apopka natural gas district task report. RSH, 6737 Southpoint Dr. S., Jacksonville, Fl.

CONVERSION OF LIGNOCELLULOSIC MATERIAL TO ETHANOL INFLUENCE OF RAW MATERIAL YIELD AND HEMICELLULOSE UTILIZATION ON SALES PRICE OF ETHANOL J.Felber, M.Schiefersteiner and H.Steinmüller VOEST-ALPINE AG, P.O. Box 2, 4010 Linz/AUSTRIA Summary In the late 70’s an Austrian Consortium consisting of the STEYRERMÜHL-PAPIERFABRIKS- und VERLAGS AG, the VOESTALPINE AG and the Universities of Graz was formed to develop a new process for the production of monosaccharides from renewable carbohydrate sources, in particular lignocellulosic material. After detailed examination of various hydrolytic processes it was decided to intensify work on enzymatic hydrolysis. The composition of this group brought the great advantage that it could focus not only on one problem but could also research into the total process. This included pretreatment, enzyme production, hydrolysis, by-product utilization and energy supply. The raw materials studied most thoroughly in our program were waste paper and wheat straw, since these lignocellullosics are available in large quantities in Austria. Until now all endevour to produce ethanol out of lignocellulosic biomass on an industrial scale failed due to uneconomical production. Thus it is evident that the economy of such a process is very dependent not only on the yield of sugar, which is strongly affected by the respective pretreatment, but also on the utilization of the hemicellulose. Summarizing it can be said that the cellulose has to be degregated to a high extent and that the hemicellulose must be utilized to reach a feasible project.

GENERAL DESCRIPTION The raw materials studied most thoroughly in our program were waste paper and wheat straw, since these lignocellulosics are available in large quantities in Austria. From the wide range of possible materials we also tested rice husks, sugar cane bagasse, palm oil residues and cotton stems. The theoretically possible quantity of sugars obtainable from waste paper and wheat straw—as estimated by our standard method (Esterbauer et al, 1982) is:

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(per 100gr dry matter rice husk waste paper wheat straw Glucose Mannose xylose Galactose Arabinose

38,3 4,0 18,5 1,2 2,7

48,0 11.4 4,9 1,4 0,9

42,00 0,38 25,50 1,90 4,30

Our program has now reached a stage where the available data can be used for a feasibility analysis of a full scale industrial plant based on wheat straw. This plant is designed for the daily production of 80,000litres of ethanol and single cell protein, furfural or furfurylic alcohol. The necessary enzymes are produced by the fermentation of hydrolysis residue with Trichoderma reesei SVG 22, a residue adapted mutant of QM 9414. The following picutures show the linkage of the respective processing areas:

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The main sugars in the biomass fibres are glucose in the form of cellulose and xylose in the hemicellulose fraction. In considering the economics of a process it is important to have exact information with respect to the potential available sugars of the raw material under consideration. If one takes MSW for example: In the USA it usually contains more than 50 % cellulose, however, MSW from Austria has only about 25 % cellulose. Thus it is evident that the economy of such a process is very dependent not only on the sugar yield, which is strongly affected by the respective pretreatment, but also on the utilization of the hemicellulose. Effect of pretreatment on glucose yield from wheat straw and newspaper. The pretreated material (100 g/l) was treated with cellulase enzyme (2 g/l) for 72 h. Theoretical yield 42 g (wheat straw) and 48 g (newspaper) per 100 g dry matter. wheat straw newspaper treatment glucose % of treatment glucose % of th. th. soaked in NaOH, steamed at 180– 200°C hydrothermolysis 180–200°C steamed at 180–200°C autoclaved, 200°C cutter reflection plate mill Wiley mill hammer mill no pretreatment

73–95

diagonal knife refiner, CaO

73–78

90 80 65 38

disk refiner reflection plate mill hammer mil1 soaked in NaOH, steamed at 235°C cutter steamed at 235°C hydrothermolysis 190°C no pretreatment

70–73 72 60 30–45

29 21 18 16

48 34 34 17

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In summary it can be said that when using a raw material with a high content of hemicellulose (cereal straw, hard wood, etc.) the utilization of xylose is indispensible, since it contributes up to 30% of the dry matter, Xylose can be converted by known chemical procedures to furfural and its consecutive products. The fermentation of xylose is not as well developed as glucose fermentation, with the exception of a few processes, e.g. the production of single cell protein. It is expected that

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future research in this area will improve the yield and productivity of xylose fermentation procedures. Assumptions for the feasibility calculation of a largescale industrial plant:

Results: Return on Investment: Break-even point:

17% (10 years of production) 80% of nameplate cap.

For further reduction of production cost in the near future our main activities will be to improve the enzyme production and recovery and to optimize the energy supply.

BIOENERGY IN REGIONAL ENERGY SYSTEMS—A CASE STUDY FROM HADELAND IN NORWAY A.LUNNAN Department of Forest Economics Agricultural University of Norway Box 44, N-1432 As-NLH, Norway Summary Up to now biomass in Norway is mainly used non-commercially as firewood in households and as mill residues in the forest industry. There are on the market commercial bioenergy systems that should be economically feasible. The hypothesis is that there exist institutional barriers that make a further development at the commercial bioenergy sector difficult. The Hadeland project studies this problem on a regional level. A regional bioenergy commission consisting of representatives from the most important interest groups serves as reference group for the project. The commission tries to establish press contacts, to inform local politicians and to stimulate potential bioenergy investors. The research project consisting of a systems study and a study of the work in a bioenergy commission, is planned to be completed by the end of 1985. Preliminary figures show that there exists a large unused bioenergy potential in the region. The systems study will hopefully identify feasible projects to utilize a part of this potential. The work in the commission has so far been fruitful and it seems that at least some of the barriers initially discussed could be overcome through cooperation and discussion between the interest groups at the bioenergy sector.

1. INTRODUCTION Bioenergy is not likely to play a major role in the national energy system in Norway. On the regional level, however, the impact of bioenergy might be considerable. Up to now biomass is mainly used non-commercially as firewood in households and as mill residues in the forest industry. What possibilities does biomass have as a commercial energy source? After five years of bioenergy research in Norway we have some technical and economical knowledge about bioenergy systems. We also think that some of these systems are competitive in the market. When starting the project we identified the most important barriers for commercial bioenergy utilization to be: 1. Bioenergy is a complex field which involves forestry (or agriculture), industry, energy sector and consumers. There has been limited contact between the sectors.

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2. The electric utility sector has up to now looked upon bioenergy as a competitor, not as a challenge. In the Hadeland project we want to study what we can do to decrease these barriers. Another aim of the project is to identify the social and environmental impacts of increased use of biomass as an energy source. 2. DESCRIPTION OF REGION To study the problems described initially we decided to make a case study in Hadeland, a region in Southern Norway (see map).

Figure 1. Map of Hadeland 3. REGIONAL REFERENCE GROUP Without local involvement from the beginning such a study would be meaningless. We therefore contacted some selected “resource people” and it was decided to set up a “Hadeland bioenergy commission”. The commission has six members representing: electric utility sector, technical division in the communes, forest owners, forest industry (saw-mills), forest and agricultural extension service and a forest engineer serving as secretary for the group. The Department of Forest Economics, Agricultural University of

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Norway serves as an engine in the commission and we also work with special analysis such as resource base, systems analysis and market analysis in cooperation with the commission. The secretary of the commission is responsible for press contact and we have already got good public relations in Hadeland. Politicians and local population start to be aware of the commission and this is important for our political contacts in the next phase of the project. To get acquainted in the bioenergy field the commission has arranged study tours in Norway and above all to Sweden. Financial support for these tours has been given by the communes, electric utility sector, industry, banks, forest owners federation and some other local organizations. Most study tours are reported in the local press. 4. RESULTS SO FAR; RESOURCE BASE

Table 1. Primary energy consumption Hadeland Electricity 300 Gwh 82% oil 36Gwh 9% Bioenergy Firewood 23Gwh Sawmill residues 12Gwh 35Gwh 9% Total (excl. transport) 371Gwh 100% of this as heat 231Gwh 62%

Table 2. Bioenergy potential in Hadeland. (Net energy, losses due to combustion, distribution etc. are included) Forest industry residues 35Gwh Forest residues 37Gwh Straw 33Gwh Manure 11Gwh Urban refuse 18Gwh Total 134Gwh —Consumed today 35Gwh Bioenergy potential 99Gwh

Tables 1 and 2 show that it should be possible to provide more than 50% of Hadeland’s demand for heat energy from biomass. It should be added that the forestry figures in table 2 are preliminary and conservative estimates, most probably they should be higher. 5. FURTHER WORK We are these days working with a market study which will be completed in May 1985. A rough systems study of different ways to convert biomass to energy is also underways. This study will give us cost and employment data. We can already today identify some five interesting projects to continue with. Different members of the commission have

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their own fields of responsibility and they provide us with valuable information for the final report. The final report from the project is going to be written in autumn 1985. We then plan press conferences and meetings with local politicians and population. The next phase of the project will then be concrete work with special projects. This is of course a task for the investors in question. It is not yet decided if the commission shall continue its work in phase 2. 6. PRELIMINARY EXPERIENCES AND CONCLUSIONS The project is not yet completed, but our experiences so far have been good. We are now making a snow-ball, time will show whether it will be rolling. The expected conservatism in the electric utility field has not been present and we have had very fruitful discussions in the commission. We have created enthusiasm and hopefully this will lead to results. We will also try to make some guidelines for the work of a bioenergy commission in a region. This would be of some interest for the bioenergy work in other parts of the country.

POSSIBILITIES OF RELIEVING THE EEC AGRICULTURAL MARKET THROUGH ENERGY PRODUCTION E.G. RAPE AND SHORT-ROTATION FORESTRY R.Apfelbeck TU—MUNICH Bayer. Landesanstalt für Landtechnik D—8050 Freising Summary In the European Community, an excess of 10–16mio ha of farmland for agricultural production is expected by 1990. Presently, the expenditures for regulating the market due to overproduction run at 850–1300DM per ha of equivalent export land. The production of energy sources, both short-rotation forestry and rape cultivation can result in net savings of more than 700DM/ha only if the energy is utilised locally by the producer. The overproduction of agricultural products is continually becoming a larger problem in the European Community. In 1984, the Community harvested 150mio t of grain, which represents a degree of self-sufficiency of 130%. The calculatory overproduction of wheat is 24mio t. On the other hand, the annual consumption of about 400mio t of crude oil is almost completely imported. The production of biomass on excess land could partly replace the energy imports. According to HEIDRICH’S calculations, an equivalent import surface of 5.8mio ha for food production was still required in 1973 for self-sufflciency, while in 1982 an excess of 4.2mio ha already existed. From Figure 1 it is clear that by 1990, the overproduction will represent 10–16miot. The production increases have led to continually increasing subsidues derived from the Community budget (see Fig. 2), such that the expenditures will soon exceed incomes.

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Figure 1: Trend and projected values of the supply situation in the EEC-9 converted to surface equivalents (according to HEIDRICH) In Figure 3 it can be seen that a subsidy of 850–1300DM per ha of surface equivalent already arises; for sugar beets up to 4.100DM.

Figure 2: Development of expenditures of the common market listed according to purpose.

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Figure 3: Producing area, export area and market subsidies in the EEC-9 (according to HEIDRICH) These expenditures reach a level, which corresponds to a half to one gross margin. As a possible alternative to reduce the overproduction, the cultivation of biomass crops is to be discussed. If biomass could be produced on the entire agricultural area at 2t of crude oil equivalent per ha, 40% of the crude oil imports could be substituted. The percentage of bioenergy on agricultural excess lands would be max. 5%. Apart from ethanol production, rape cultivation and short-rotation forestry can be considered, since the products produced could be used directly at the farm site. SHORT-ROTATION FORESTRY With this alternative, 10.000–12.000 poplar slips are planted per hectare. After 2 years of weeding and annual fertilization, the entire wood material is harvested in 5 year-intervals as chips. The lifetime of such a system is estimated at 15 years. At the Hessischen Forstlichen Versuchsanstalt, Hann. Münden, the average annual dry-weight growth was 10–15t per ha in the period 1979–83. The best varieties even reached 25–30t (dry matter). The advantages of this production method: – Wetland sites are possible (high precipitation, pastures) – Reduced use of weed killers – Soil erosion is hindered – Harvest time in the winter months

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These are offset by the disadvantages: – Production techniques in trial stage – Storage and drying not yet determined – Large transport capacities required – Extended capital binding, liquidity problems – Market introduction as a product necessary In Figure 4, the expenditures are illustrated for a 1ha short-rotation forestry plot. The initial costs in the first year are about 8.000DM, harvest costs 100DM/t (dry matter) and the costs for ventilation drying are 25DM/t (dry matter). An interest rate of 7% for debts and 5% for credits is assumed. As a substitute for oil, the wood chips are to be used at the farm site and the cost is set at 260DM/t (dry matter).

Figure 4: Simplified balance sheet for a short-rotation forestry plot of 1 ha over 15 years With the above assumptions, a satisfactory income or savings can be expected only if the initial productivity is above 15tdry matter/ha annually. Cost reductions are possible in the harvesting and drying processes. Detailed results from the test plantings should be awaited. RAPE CULTIVATION The cultivation of rape is well known. Figure 5 shows the composition of the plant and its uses.

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Figure 5: Composition and the possible uses of rape The method has the following advantages: – Production techniques known – Fuel production for vehicular power (substitute for diesel) – Production of protein-rich fodder Disadvantages are: – Rape oi1 usable only in special engines – Production restricted to arable land If rape oil is not chemically treated (trans-esterification), only few diesel engines can be considered (Elko, KHD). Rape straw can substitute heating oil and rape meal can be fed to livestock. Figure 6 shows the range of possible substitution or saving values with the use of rape as an energy crop.

Figure 6: Economic evaluation of the energetic use of rape at the farm site

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Depending on market situation and the given farm operation, net savings of 700– 1200DM/ha are possible with the local use of rape products at the farm. Further investigations of both energy crops are necessary for an exact economic analysis. Even under more unfavourable conditions as considered here, a transfer of market subsidues into energy crops can lead to savings in the EEC budget. With a change of direction toward energy production, however, considerable organizational problems are also to be expected. REFERENCES (1) BATEL, W.: Pflanzenöle für die Kraftstoff- und Energieversorgung, Grundlagen der Landtechnik, Bd. 30, Nr. 2, 1980 (2) BUSCH: Mündliche Mitteilung, 1985 (3) DIMITRI, L.: Schriftliche Mitteilung, 1984 (4) ELSBETT, L.: Prospektmaterial, 1984 (5) v.GELDERN, W.: Rund neun Mio. Tonnen Weizen nicht absetzbar, Süddeutsche Zeitung, 09.01.1985 (6) HOFSTETTER, E.M.: Feuerungstechnische Kenngrößen von Getreidestroh, Dissertation, Weihenstephan 1978 (7) KHD-Information: Prospektmaterial 1984 (8) SCHÄFER, R.; E.HEIDRICH: Einfluß und Nutzung von Biomasse als Energieträger auf die arbeitswirtschaftliche Lage, die Energiesituation und die Agrarmarktprobleme der Europäischen Gemeinschaften, Endbericht zum Vorhaben ESE-R-065-D (B), Studie 2/1, 1984 (9) WEISGERBER, H.: Klonvergleichsprüfungen bei Schwarz- und Balsampappeln im Kurzumtrieb, Vortrag auf Tagung “Ad-hoc Committee on Biomass Production System in Salicaceae, Ottawa, Kanada, 1984

THE ECONOMICS OF THERMOCHEMICAL ROUTES FROM WOOD TO LIQUIDS L.A.MICHAELIS Cambridge Energy Research Group Cavendish Laboratory Madingley Road Cambridge, UK CB3 OHE Summary Several research groups and companies are working on the technologies for converting wood to liquid fuels. The technologies include those for producing synthesis gas followed by methanol, gasoline or FischerTropsch liquids, as well as direct liquefaction using a solvent and catalyst. Process yields, capital costs and running costs have been predicted, with varying degrees of confidence. Most predictions suggest that at the present price of fuels from petroleum, none of the technologies is likely to be economic. Central estimates for the best developed, indirect methods give fuel costs at around $11/GJ, which compares with a price of around $5/GJ for internationally traded gasoline. Improvements in processes seem unlikely to reduce costs below $8/GJ. A simple spreadsheet programme designed for comparative assessment of fuel conversion technologies in developing countries is applied here to liquid fuel production. It is seen that countries with foreign exchange problems—either an overvalued currency or worsening terms of trade— may find these technologies attractive. Discounted cash flow analysis is used to compare the effects of technology improvements with those of the economic environment on fuel cost. The results make clear the attractiveness of a direct liquefaction process, if one was developed to a commercially viable stage.

1. INTRODUCTION Evaluation of fuel conversion technologies hinges on the economics. The normal method used is discounted cash flow analysis, giving the product price needed to pay for the project costs. Several organisations have made assessments of wood conversion technologies. These indicate that the cost of transport fuels from wood is likely to be two or three times the price of internationally traded fuels from oil (now about $5/GJ). For this reason much attention is being paid to finding ways of reducing the cost. As capital comprises 50% of the conversion cost for most processes, most attention is paid to this

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factor. Process efficiency is also extremely important. Plant costs depend almost entirely on the amount of wood processed, not on the output level, so product cost is inversely proportional to yield. While lowering costs brings forward the time at which these products can compete with fuels from oil in affluent countries, some may already be attractive in countries experiencing severe economic difficulties. In order to facilitate assessment of different technologies in diverse economic climates, a spreadsheet programme has been written using cost-benefit analysis. The programme calculates the price of internationally traded oil for which the product is a desirable substitute. It allows for variations in capital costs, wage rates and so on, as well as for different rates of escalation of wages, energy prices, plant costs etc. This paper demonstrates the kind of results obtained when such analysis is used on four technologies producing transport fuels from wood. 2. THE TECHNOLOGIES The technologies considered here are; 1) Gasification of wood in a Winkler or Westinghouse type fluid bed gasifier, followed by methanol synthesis by the ICI or Lurgi low pressure process. 2) Methanol production as in 1), followed by conversion to gasoline by the Mobil process. 3) Gasification followed by Fischer-Tropsch synthesis in a liquid phase reactor, and then upgrading to transport fuels. 4) Direct liquefaction of wood by the PERC process. Capital costs and efficiencies are given in table I. The technologies are reviewed in detail in ref.(1), except Fischer-Tropsch synthesis which is reviewed in ref. (6).

TABLE I: Investment and Product Yields for Reference Technologies Technology:

Methanol synthesis Gasoline synthesis Fischer-Tropsch PERC process

Investment (1984$m) Feed rate (TJ/day) Product (TJ/day): Methanol Gasoline Diesel LPG Chemicals Total Product Efficiency (h.h.v.) *1000 dry tonnes wood/day

125 18.5*

150 18,5*

150 18.5*

8.28

4.55 2.90 0.47 0.66 8.58 46.4%

120 18,5*

10.5

1.45 10.5 56.8%

9.73 52.6%

10.4

10.4 56.2%

Methanol synthesis is the best established process, and although as a whole it is not in commercial use, gasification and methanol synthesis are practised at a commercial level. The literature is extensive, and only three references (1–3) are given here. There is broad agreement about capital costs; the figure of $125m (1984 US$) used here is representative of values obtained after extensive use of the Chemical Engineering Plant

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Cost Index, and scaling plant size to 1000 t/d. (Ref. 4 shows that investment is related to output Q by I=IoQ0.8.) The Methanol-to-Gasoline process is less well established, and not yet commercially proven. Capital costs are estimated (1) at around 17% on top of methanol synthesis costs. The efficiency of the MTG process is high, and heat recovery allows the loss of thermal efficiency in the overall process to be as low as 2% (5). The cost and efficiency used here are representative of values from the literature. Fischer-Tropsch synthesis has been considered less for wood because of high capital cost and low efficiency. However the process is commercially established for the conversion of coal in South Africa. The presence of deisel fuel in the product may be an advantage in some countries. There are several versions of the process, which catalytically converts synthesis gas to hydrocarbons. The version used here is the liquid phase process. This has several advantages over the Synthol and Arge processes used in South Africa, including a low H2:CO requirement in the synthesis gas, lower capital cost and higher selectivity in the product. The data used here is based on ref. (6), and data for wood gasification on ref.(1). Refining of the product is about 50% of the cost, although this might be reduced by refining the product from several plants at a central refinery. The PERC process is at a very early stage of development, and costs and yields are correspondingly uncertain. Although the figures used here from ref. (1) imply excellent yields and low cost compared with other processes, there are several technical difficulties which may be costly to overcome. The process, like coal liquefaction, involves slurrying wood in recycled oil, which acts as a solvent while the wood is reduced at high CO pressure. The product is high in oxygenates and low in hydrogen, and upgrading comprises 50% of capital costs. The product is diesel or jet fuel, which would be preferable to methanol or gasoline in many countries. Running costs for the processes vary between sources. Operation and maintenance charges are normally assumed to cost a percentage of plant investment per annum. Labour and feedstock costs are dependent on location and vary by an order of magnitude. The base values used here are given in table II.

TABLE II: Assumptions for D.C.F. Calculations Construction period 3 years Plant life 20 years Discount rate 10% Load factor 80% Annual costs: Materials 4% of Investment Utilities 2% of Investment Catalysts 1% of Investment Labour @ $50/shift; $0.79m/annum Feedstock cost $25/dry tonne @18.5 GJ/tonne

3. ECONOMICS Table III gives the results of discounted cash flow calculations for projects using the four technologies.

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TABLE III: Breakdown of Product Cost: 1984$/GJ (%) Technology Methanol synthesis Gasoline synthesis Fischer-Tropsch PERC process Capital O&M Feedstock Labour Total

5.21 2.58 2.28 0.26 10.33

(50.5) (25.0) (22.0) (2.5) (100.0)

6.72 3.34 2.45 0.29 12.80

(52.5) (26.1) (19.2) (2.3) (100.1)

7.61 3.78 2.78 0.33 14.50

(52.5) 5.00 (49.9) (26.1) 2.48 (24.7) (19.2) 2.29 (22.8) (2.3) 0.26 (2.6) (100.1) 10.03 (100.0)

It is seen that capital costs comprise about 50% of product cost for each process. Capital related costs, including maintenance materials etc., comprise 75% of the total. Feedstock cost is relatively unimportant and direct labour costs are very small. Product cost is determined mainly by the plant investment and process efficiency. Capital costs are highly uncertain. Ref. (1) estimates the range in the region of −20 to +50% for untried technologies, with an additional ±20% due to location (for freight etc.). This range is larger than that of central estimates for different technologies. For this reason sensitivity analyses are given for just one base case investment. Table IV shows the results of some sensitivity tests. Also shown are the effect of varying feedstock and labour costs together, and capital cost and yield together. The first is significant as low labour costs will lead to labour intensive forestry and low cost wood. Improvements in processes are likely to give both lower capital costs and higher efficiencies; for instance, the use of steam gasification, with combustion in a separate reactor, can eliminate the need for oxygen generation in methanol synthesis. The result is lower cost and higher efficiency. 20% reduction in capital and 10% increase in yield probably represents the best case attainable.

TABLE IV; Sensitivity of Product Cost Base case; Plant investment $125m Product 10 TJ/day Labour $0.79m/yr Discount rate 10% Feedstock $25/t Base case cost $10.83/GJ Item varied Product cost $/GJ Capital Discount rate Feedstock Labour Labour & feed

−20% to +50% 9.2 to 14.9 5% to 15% 9.0 to 13.0 −50% to +50% 9.6 to 12.0 $0.1m to $4m 10.6 to 12.0 $0.1m & −50% 9.4 to $4m & +50% to 13.2 Yield 11 to 9TJ/dy 9.8 to 12.0 Yield & capital 11TJ/dy & −20% 8.4 For comparison; cost of gasoline from oil is currently $5/GJ

Discounted cash flow analysis can be modified for government projects, to take account of influences other than simple cash benefits on the investment decision. Shadow wages, prices and exchange rates can be used to reflect the true value of each item to the decision

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maker. Allocation of shadow prices is subjective and complex, and this paper only attempts to illustrate the results from such allocation. For a full discussion see ref. (7). Table V shows the effect of different shadow exchange rates, and also of different benefits from the products. Some countries are experiencing worsening terms of trade and large foreign debts. In many cases this leads to an overvalued currency. The effect of discounting domestic expenditure in the project by an appropriate factor is shown. Process plant is assumed to be imported, but civil engineering costs are treated as domestic, as are feedstock and labour. Where a country can produce its own plant the product cost will be reduced in proportion to the discount factor, so a factor of 2 would make the project viable. The combination of improvements in technology and a discount factor of 1.6 could also make the technology viable in such a country. The effects of worsening terms of trade are also shown. These have the effect of increasing the cost of future oil imports, as well as some of the process running costs. Shadow pricing also has to take account of the value of the product to the economy. Diesel, which is used for freight and public transport, is of more value than gasoline, which is used for private cars. Methanol can only be used in blends of up to 3% in gasoline in unmodified engines. LPG can only be used in modified engines. Modifications are only likely to be worth-while for heavy users, such as light goods vehicles. Differential taxes are unlikely to reflect the differences in costs adequately (i.e. through higher gasoline prices) because of the strength of the private motoring political lobby, To account for this the benefit from gasoline sales is discount-ed relative to diesel by different amounts in table V.Fischer-Tropsch synthesis becomes more attractive than the MTG process if the discount is more than 30%, but both processes become increasingly unattractive. Methanol would become even less attractive than MTG because of the cost of engine modifications and changes in distribution infrastructure. Although the PERC process appears extremely attractive by comparison, the figures used for efficiency and cost were speculative, and rely on successful development of the process.

TABLE V: Economic Influences on Cost “Cost”* $/GJ Domestic currency discounted by 2 to 4 8.1 to 6.7 Terms of trade deteriorate 1, 2, 3%/annum 9.9, 9.0 or 8.2 Domestic currency discounted by 1.5 and terms of trade deteriorate 1, 2%/annum 8.2 or 7.5 Gasoline discounted 10, 20, 30, 40% effect for; MTG 14.0, 15.4, 17.2, 19.4 Fischer-Tropsch 15.3, 16.2, 17.2, 18.4 PERC 10.0, 10.0, 10.0, 10.0 *Oil import price at which government backed project becomes viable

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4. CONCLUSIONS While liquid fuels from wood are likely to cost twice as much as oil products in the forseeable future, the technologies may still be desirable in certain circumstances. Improvements in technology could make them viable in countries with foreign exchange problems able to build their own plant. Although the PERC process appears the most desirable in this analysis it is not sufficiently developed, and the data is too uncertain, for the results to be meaningful. The results do show that successful commercialisation of the process would be beneficial. The overall effects of a project on the economy need to be taken into account in its assessment. This paper illustrates the effect such consideration can have. A proper assessment requires extensive evaluation of these effects. REFERENCES 1.) U.S.DOE. “Technical & Economic Evaluations of Biomass Utilization Processes; Technical Report no. 1” Sept. 1980. DOE/ET/20605-T4. 2.) Wan E.I., Simmons J.A., Price J.D., “Economic Evaluation of Indirect Biomass Liquefaction Processes for Production of Methanol & Gasoline” in Energy from Biomass & Wastes VI, Florida Jan. 1982, 3.) Brandon O.H., King G.H., Kinsey D.V. “The Role of Thermochemical Processing in Biomass Exploitation” in Thermochemical Processing of Biomass ed. A.V.Bridgwater. Butterworths 1984. 4.) Reed T.B. “Biomass Gasification: Principles & Technology” ch. 13. SERI Golden, Colorado. 5.) Lurgi Express Information. “Gasoline Production from Natural Gas or Coal” presented at KTI Symposium, Nov. 1980, Los Angeles. 6.) Holmes J.M., Hemming D.F., Teper M. “The Cost of Liquid Fuels from Coal Part II: FischerTropsch Liquids” IEA Coal Research Nov. 1984. 7.) Squire L., van der Tak H.G. “Economic Analysis of Projects” The World Bank 1975.

CHEMICAL INVESTIGATIONS IN THE SWEDISH AGROBIOENERGY PROJECT O.THEANDER Department of Chemistry and Molecular Biology Swedish University of Agricultural Sciences P.O. Box 7016, S-750 07 UPPSALA, Sweden Summary The chemical characterization of a series of crops from the Swedish Agrobioenergy Project—including cereals, sugar beets, fodder beets, Jerusalem artichoke, Salix clones, lucerne and garden orach—and of botanical fractions such as grain and straw or residues after biogas production, is presented. The chemical composition and yield per hectare of individual chemical components within a type of crop show a large variation between varieties, cultivation site and time of harvesting. We have, for instance, found starch values in the grain of winter wheat varieties to vary between 63–73% of dry matter. For ash, cellulose, hemicellulose and Klason lignin in straws from wheat, barley and oats the ranges are generally 3–11, 33–40, 29–33 and 16–21%, respectively. The yields of straw from these experimentally cultivated cereals have varied between 8.6 and 16.9 tonnes dry matter/ha. This indicates a great potential for increasing and controlling the yields of various chemical components in the future by plant breeding and suitable choice of variety and cultivation system. In connection with the project new improved methods have been developed for the analytical determination of sucrose (in beet crops), starch and the lignocellulose components in various plant materials. We have, for instance, found that the conventional automatic method for sucrose analysis of sugar beets, based on optical rotation, gives too high values when applied on fodder beets.

1. THE ANALYTICAL METHODOLOGY When we work with chemical characterization of plant materials in connection with animal and human foods or with crops or fractions from agriculture or forestry of interest as raw products for fuels or other technical products, we generally follow the fractionation—analysis scheme summarised in Fig. 1. For the extraction with aqueous ethanol or acetone and the organic solvents we have found that ultrasonic treatment (at <30°C) is not only effective but also more convenient and harmless for some thermolabile components than the conventional refluxing (1). This treatment is done in a centrifuge tube, where the sample can be retained during the various extraction-,

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washings- and centrifugation steps. For removal or analysis of starch we have found that a combined gelatinization/starch hydrolysis with the heat-stable α-amylase Termamyl 120L (Novo A/SJ) and amylo-glucosidase (EC 3.2.1.; Boehringer and Mannheim)—is very effective and reproducibled(1, 2).

Fig. 1. Procedure for fractionation and analysis of plant materials. Gas-liquid chromatography on capillary columns (GC) is an excellent method for efficient separation and accurate determination after derivatization of, for instance, fatty-, resin- or phenolic acids, low-molecular sugars or the neutral polysaccharide constituent sugars released by hydrolysis. On the other hand, high-pressure liquid chromatography (HPLC) offers an alternative convenient procedure, where derivatization generally is not necessary, with increasing improvements and applications. The decarboxylation method, which we use for determination of the uronic acid content of pectins and acid hemicelluloses, does not suffer from interference by other components as occurs in colorimetric methods and is very accurate and reproducible (1, 3).

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2. THE CHEMICAL COMPOSITION OF DIFFERENT PLANT MATERIAL Sucrose-, starch-, lignocellulose and protein sources Based on the analytical methods discussed above, Fig. 2 shows some examples from our chemical characterization of some typical plant materials rich in sucrose, starch, lignocellulose (fibre) or protein being studied in the Swedish Agrobioenergy Project (compare the paper by U.Wünsche). Sugar beets or fodder beets are the main sucrose crops in Sweden and for some years we have compared the sucrose production of a series of cultivars grown in different parts of the country (for an example, see Fig. 3). Although the main technical use or potential for sucrose is for production of ethanol and other fermentation products or chemical conversion products such as sugar alcohols, esters and ethers, the pulp residue with its high pectin content also has an interesting technical potential.

Fig. 2. Chemical composition of some plant materials. Potatoes and cereal grains are the main Swedish sources of starch, with also lignocellulose and, in particularly in grains, protein as interesting fractions. Potatoes are already an important raw material in Sweden for production of industrial starch and starch derivatives and other products. For an increasing utilization of starch for such products, however, and in particular for ethanol production (in combination with various side-products), we consider the most interesting sources to be wheat and barley. Straw and the Salix clone from the Swedish Energy Forestry Project represent plant sources rich in lignocellulose with the three giants in the globally produced biomass, namely cellulose, hemicellulose and the phenolic polymer lignin as the predominating

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components. Besides the utilization of such materials for solid fuels, animal feed, paper, textiles and building materials, they have also a great future potential via various pretreatments, fractionation and hydrolysis processes now being intensively studied all over the world for production of ethanol and various chemicals and polymers. Lucerne, finally, represents a crop with a more even distribution of the three main fractions lignocellulose, protein and extractives (mainly low-molecular weight compounds, extractable with water and/or organic solvents). Other examples with several main fractions are rapeseed and other oil-seeds and the overground part of Jerusalem artichoke. Studies on wheat Table 1 shows some examples of the yields of straw and grain from the Swedish trials with different high-yielding winter wheat varieties in different years and at different localities. Although these cereals were experimentally cultivated (with stubble height=5cm) the results clearly indicate that the total yield of biomass can be quite impressive for several of the cultivars at a locality (near Uppsala) which can be considered as reasonably average for Sweden as a whole. Based on our chemical studies, the yields in Table 1 indicate that a future production under our conditions of about 5 tonnes/ha of both starch and cellulose, 4 tonnes of hemicellulose and 3 tonnes of lignin might be possible. The starch values in the grain of these winter varieties have varied between 63 and 73% of dry matter. For straw from wheat, barley and oats we have generally found the ranges 3–11, 33–40, 29–33 and 16–21% for ash, cellulose, hemicellulose and Klason lignin respectively (4). In the hemicellulose fraction xylose is the major component, considerable amounts of uronic acids, arabinose and acetyl groups are also present, and the sugar units mannose and galactose as well as two phenolic acids represent minor constituents.

Table 1. Yields of harvested straw and kernels from different winter wheats; Ultuna, Sweden (given as dry matter tonnes/ha) Variety Holme Alcedo Brigand Ural WW 28020 WW 28204 SvU 75630 Sv 76477 LP 468971 Folke

Straw Grain 1982 1983 1982 1983 15.1 8.6 8.6 10.0 13.8 16.9 15.3 12.3 11.6

10.8 11.2 8.7 10.7 12.6 11.1 12.0 11.1 11.7 11.2

6.3 5.7 5.7 6.5 6.4 6.4 6.8 6.5 6.0

5.7 5.9 6.5 5.3 5.7 5.4 5.1 5.9 6.1 5.9

Studies on sugar- and fodder beets, Jerusalem artichoke, lucerne and garden orach

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Finally, I will present some glimpses from the chemical investigations on some other crops in the project. Fig. 3 shows the yields of sucrose per hectare from a series of beet crops cultivated near Uppsala (not a normal district for growing sugar-beets, which are normally cultivated in the south of Sweden). We have made a critical study of methods for analysis of sucrose in beet crops (5) and have found HPLC to be particularly specific and convenient. However, if the conventional automatic analysis based on optical rotation is used, as in the sugar industries, without taking into account the difference in dry weight between sugar beets and fodder sugar beets, the sucrose production of the latter will be strongly over-estimated (indicated in the figure).

Fig. 3. Production of sucrose from beet crops cultivated near Uppsala, Sweden.

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Fig. 4. Chemical composition (in % of dry matter) of four crops before (A) and after (B) biogas production. Fig. 4 illustrates our studies on biogas production f rom high biomass-yielding crops such as Jerusalem artichoke, lucerne or a more unconventional crop such as garden orach (6). It shows the chemical composition of the residues (calculated on the original material) after the anaerobic digestion in comparison with that of the fresh crop. Studies on ruminants indicate that these residues have a potential primarily as nitrogen supplements to diets low in nitrogen. REFERENCES (1) THEANDER, O. and WESTERLUND, E., in “Handbook of Dietary Fiber in Human Nutrition” (ed. G.E. Spiller) CRC Press, Inc., in press. (2) SALOMONSSON, A.-C., THEANDER, O. and WÉSTERLUND, E. (1984). Swedish J. Agric. Res. 14, 111–117. (3) THEANDER, O. and ÅMAN, P. (1979). Swedish J. Agric. Res. 9, 97–106. (4) THEANDER, O. (1985), in “New Approaches to Research on Cereal Carbohydrates” (eds. R.D.Hill and L.Munck) Elsevier, Amsterdam, 217–230.

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(5) MALMBERG, A., MALMROS, O., THEANDER, O. and TJEBBES, J., Proc. Bioenergy, in press. (6) LINDBERG; J.E., MALMBERG, A. and THEANDER, O. Submitted to Animal Feed Science and Technology.

ENERGETIC OPTIMIZATION OF BIOMASS IN THE FARMING SYSTEMS OF MARGINALISED AREAS—LABOUR AND CAPITAL RESTRICTIONS ECONOMIC ANALYSIS J.P.CHASSANY Institut National de la Recherche Agronomique Economie et Sociologie Rurales—Montpellier (FRANCE) Summary The economic survival of farmers in marginalised mountain regions implies a diversification of activities. Moreover the isolation means heavy fuel consumption. In order to reduce their energetic dependance and to optimize their surplus labour force a group of breeders from the southern French Alps produce biogas by methanisation of manure to supply domestic needs and to supply fuel for their cars. Production of fuel requires a methane compression at 300 bars. Strict regulations force the promoters (CUMA des Sources—La Bâtie des Fonts, and IRCHA— CNRS Montpellier) to remove completely SH2 and H2O from the gas. The tests show that methane fuel can be obtained on the farm in absolute safety. On the other hand the use of too old dry and strawed manure results in mediocre production. The working of the installation requires long working periods especially for the preparation and Introduction of the organic substrates. The micro-economic calculation shows that payment for work is guaranteed provided that 50m3 of gas is obtained per day and that a too high profitability of capital is not given priority. Finally this development proved to be a social apprenticeship for the parties involved which resulted in delays, overcosts and a fall in efficiency as far as the introduction into the system of initial activities is concerned.

1. THE CONTEXT The process of marginalisation in mountain regions is familiar and thus needs no further introduction. In the Haut-Diois, this marginalisation takes the form of a very noticeable trend in agricultural abandon and a serious population drain. The foreseeable increase in the cost of energy may yet worser the situation (1). Situated in the south of French Alps, in the Diois, which is the severest and most difficult region, the GAEC exploitations, which set up a methane fermentation system using sheep and goat manure, had to cope with various serious restrictions:

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– geographical environmental restrictions: altitude higher than 1,000m, very difficult climate which makes the shelter of the flocks necessary throughout the winter, a relatively overgrown terrain and low fodder productivity; – restrictions linked to socio-economic problems: isolation, difficult access, problem of children’s schooling, an active aged population which is dying out, difficult access both to property and to use of the land, foreseeable variation in the price of mutton following Great Britain’s entry in the EEC, difficulties in marketing goats’ cheese; – restrictions linked to the exploitations themselves: problems of balancing the cultivated surfaces for the feeding of the flocks and the pasture surfaces in such a way as to limit as much as possible the intermediate consumption; problems of growth and modernisation of the exploitations where the breeding houses in particular were no longer workable; the valorisation of labour which has little to do during the winter; problems of controlling spontaneous woody vegetation in pasture areas. All these restrictions are characteristic of the agricultural production systems studied in disinherited mountain areas where ovine and caprine breeding dominate. A positive economic balance sheet can only be reached by guaranteeing a winter-time maximal selfsupply of animal foodstuffs, which causes a late lambing in the spring and restricts the staggering of production throughout the year. However the passage of flocks on its own is not enough to control the vegetation on non-cultivated land and thus entails improvements which are expensive in energy and fertiliser. All this together with low production and uncertainties linked to marketing, weaken the production system. In these conditions, the exploitations in these areas have to diversify their activities in order to increase their incomes and to allow a relative accumulation. Thus, in the beginning two breeding concerns (350 meat ovines and 70 milk and meat caprines) made up from the Common Agricultural Exploitation Group (GAEC) with a third, came together to manage a group of lands distributed in the following way: Terrain Cultivable Lands Pastures Moors Woods Total GAEC 1 GAEC 2 Aire d’Anjai

23 70 225 114 432 36 0 20 3 59 6 30 20 25 81 Ha 65 Ha 100 Ha 265 Ha 142 Ha 572

64% of the lands are in quasi ownership, 46% being tenant farming (23% written lease, 23% spoken lease). A sheep enclosure was built in 1981 and cheese dairy installed and this, together with the direct sale to Nice and Valence allowed a better valorisation of the goat milk production. A scheme to install a modern goat enclosure was completed in 1984. A sawmill allows the valorisation of the vast wooded areas and supplies the wood needed. Thanks to the knowledge acquired, a construction SICA has been created and soon a scheme for a country at Valence will be completed, which will allow the sale of farm produce. A part-time job is guaranteed at the GPO. Full time work for 9 manpower units is thus projected. The scheme for the installation of a methanic fermentation unit was an extra element in the diversification plan. Due to the foreseeable increase in fossile energy prices, it also

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aimed at reducing the energetic dependance of the exploitations by supplying the fuel necessary for different vehicles—tractors, lorries, cars; the breaking of isolation being a major problem in this area—and for the sawmill which currently uses electricity. Some of the gas produced is also used for domestic needs as well as for the cheese dairy. Finally, the compost from the methanic fermentation makes an excellent nonpathogenic fertiliser: logically this should cause doubts about manuring policy in these exploitations (cultivated and non-cultivated lands) and be taken into account for the final balance sheet. It thus can be seen that the project is being introduced into a complex and diversified system, which brings a regular supply of biomass to the fermenters, a relatively continuous use of the energy produced by the different members of the CUMA and an efficient follow-up of the biogas production by one of the GAEC members. The butane, petrol and diesel savings have been worked out to 19tep/year (11 for vehicles). 2. INSTALLATION FEATURES To bring about this project a CUMA (Cooperative for the Use of Agricultural Equipment) was implemented between the Carabes GAEC, the Près GAEC, Aire d’Anjai, and a local breeder. Created by the IRCHA-CNRS (P. BROUZES) and the CUMA with a high selfconstruction rate for the shell—22 % of the total costs apart from studies and research— (COMES Ref.: 373–374, IRCHA Ref.: A9059), the installation comprises a 145 m3 digester, a gas purification unit to eliminate CO2 and especially SH2 (contents lower than 7mg/Nm3, or a purification to 99.94%) and to dry gas so that the H2O dew point at 200 bars is at −10° and corresponds to 11.79mg/Nm3 (elimination: 99.96 %). The purified gas is stored temporarily in a 38m3 concrete container. A compression at 300 bar is provided for the methane fuel stocked in bottles and a 3 bar compression for domestic uses of the biogas (in order to take into account load losses in tubings due to the dispersion of uses). Tests carried out in April and May 1983 show that an average production of 78 m3/d can be obtained for crude gas, producing 53.5m3 of purified gas for 1 tonne of fresh manure introduced every day while the digester is designed for a supply of 1.5t/d. The reheating of the digester consumed 20m3/d but this has little significance as the thermic balance was not reached. The manure used proved to be of poor quality (too old and dry) in comparison to forecasts. Thus the preparation of the substrate (crushing, humidification, pumping, and introduction in the digester) took a long time. Due to lack of automation, an average half a manpower unit is needed for the methane activity. 3. SOME MICROECONOMIC ELEMENTS In order to calculate the economic viability of the installation, the model developed by the INRA-Grignon Economy Laboratory (J.C.SOURIE team) was used by J.Ph.RIOLLET, at INRA-ESR in Montpellier (2). This allows the calcultation of the

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average annual profit made taking into account the inflation rate, the sliding price of displaced energy, the usual taxes, and eventually the labour costs. Laboratory tests and the digester test itself after various raodifications (gas agitation, preparation and substrate pumping) show that a net production of 50m3/d is neither too pessimistic nor too optimistic provided that the digester is steadily supplied. Two possibilities are envisaged: the first (“real situation”) takes into account the actual investment of which the amount is calculated, item by item, according to real costs (bills, working hours, etc.) and of which the means of financing is the same as for the CUMA (loans at low interest rates for development plans, a large subsidy (60% to 70%) linked to the experimental nature of the project). However the calculation programme assumes that the renewal of used equipment costs no more than the initial price in constant francs (no fluctuation due to change of series or technical progress) in the same financial conditions as those calculated at the time of building the installation. Now, the initial cost is weighted by the overcosts linked to errors, dysfunctions or “start-up” problems. Thus the renewal costs can be thought to be lower. Elsewhere, the financial means for renewal will probably be a loan under normal market conditions. This is why a second possibility has been studied, which corresponds to what this installation would be if it had to be reproduced today, taking into account the acquired knowledge of those who created it. They themselves estimate the total investment cost would be reduced to FF 450,000 (1983). It has been assumed that a 8% loan over 7 years could be obtained to finance 70% of the installation (“reproduction” hypothesis). The interest in envisaging this second possibility is twofold: – together with the first possibility, it allows the setting up of a range of results within which the real results of the installation are likely to be expected; – it allows the evaluation of the economic interest of the chosen technical solutions, outside of an experiment and subsidised context. By making the actualisation rate in constant francs grow, a greater place is glven to the profitability of capital which is considered to be a rare factor, and the relative weight of working expenditure is weakened. Methanisation at the farm (high investments with low working expenses—except for labour) is thus penalised in favour of more conventional installations. If this is to be compared with other types of investments (e.g. goatfold), it is necessary nevertheless to keep a high actualisation rate. The value generally adopted is about 8%. The featured table shows that when labour is not taken into account, the up-to-date average annual profit is positive especially in the “subsidised” situation with deadlines of around 7 to 13 years. The agricultural income increases, but pays the labour force little. Values of average actualised annual profit (francs) and recovery time limit (years) Rate of updating Without taking Labour Costs into Labour Costs counted with a 2% account bying power growth in constant Francs Actual Reproduction Actual Reproduction subsidised subsidised Situation Situation FF year FF year FF year FF year −4,7%

62,708

13

54,301

7

18,290

22

9,883

13

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−1,9 0 1,9 4,7 7,5

56,350 52,181 47,715 40,921 34,168

13 13 13 13 13

47,763 43,079 38,214 30,733 23,240

1194

7 7 7 7 7

13,287 9,721 6,014 299 −5,493

22 22 22 22 22

4,521 620 −3,484 −9,889 −16,420

13 13 13 13 13

General hypothesis: 6% inflation rate per year, 2% sliding of fossile energy prices in constant francs—labour 1/2 manpower unit at FF/h 20+ welfare contributions+usual taxes on fuel. If the payment of the labour force is introduced at an acceptable level of 20 francs/hour plus welfare contributions, which is the CUMA des Sources major objective, a lower actualisation rate must be considered satisfactory. On the other hand, the reproduction situation (i.e. with little aid) gives even less favourable results. 4. THE MAIN LESSONS This experiment on a real size shows that: – production, perfect purification of the biomass and its compression are possible with no risk at the farm; –success in methanic fermentation of strawed and dry manure (since it has been removed from enclosures at long intervals of time) is one of the most difficult to obtain. The preparation of the substrate, crushing and humidification are one of the most delicate points. The members of the CUMA envisaged are considering the installation of their goat breeding on gratings in order to obtain semi-liquid manure which can be introduced directly by pumping; –in the current system, the working charges are higher than expected which reduces the labour forces’ pay; –as the installation is one of the first of its kind, administrative complications, conflicts between inexperienced official services have resulted in costly delays (at least 18 months), since for security reasons the digestor had to be moved, which resulted in a less rational installation. This cas be considered as a painful social apprenticeship for the people involved which resulted in problems very difficult to solve; –this development has allowed the members of the CUMA to acquire skills which may be put to good use for other installations of the same kind.

REFERENCES (1) CHASSANY J.P., Energie de la biomasse en zones marginalisées. Notes et Documents, N° 55, INRA-ESR, Montpellier, 1984, 48 p. (2) SOURIE J.C., La fermentation méthanique des déjections animales. Aspects microéconomiques, INRA-ESR, Grignon, 4/1981, 27 p.

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Biomass as an energy source in the French context, promises and constraints THE ECONOMIC DILEMMA OF BIOMASS IN TWO GRAPHS J.C.SOURIE National Institute for Agronomic Research Rural Economics and Sociology Station 78850-GRIGNON FRANCE Summary The various economic and social obstacles to the energy valorisation of biomass were analysed in a recent article [1]. One of these, which appears essential to us today, will be developed here. It is a matter of understanding why the economic surplus disappears as soon as the energy valorisation of biomass is removed from the subterranean economy field and placed in that of trading economy. This disappearance of the surplus stems both from an amplification of costs due to collection, and from a reduction in the utilisation value of the biomass on an enlarged scale.

1. OBSERVATION : IN FRANCE, SUBSISTANCE FARMING TODAY IS STILL THE MAIN MEANS BY WHICH BIOMASSES ARE VALORISED. In 1973, about 2 Mtoe of wood were used on farms for heating. In 1985, approximately 10 years after the first oil crisis, 4 Mtep of dry by-products were used by farmers and by wood transformation industrialists. In spite of the considerable increase in the price of oil since 1973, subsistance farming of dry by-products is still the main means by which biomasses are valorised, whilst trading valorisation is having difficulties in developing. What are the reasons for this? This is what we are going to try to explain by economic considerations. 2. SUBSISTANCE FARMING AS A CREATOR OF ECONOMIC SURPLUS (Graph I). Biomass does not set the lead price of energy. If it is to develop, it has to be cheaper than its competitors and, above all, cheaper than coal. This leads to a utilisation value. The latter depends on the price of the fossil vectors which are replaced and on the costs involved by the transformation of the biomass into final energy. The biomass demand

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curve [D] is the result of the utilisation values. If the cost of the biomass is in zone A, the fossile vectors are more economical and will meet energy demands at a lesser cost. If it is in zone B, the situation is reversed. Curve [0] is the supply curve in a situation of subsistance farming. It is obtained from the individual supply curves which are in turn based on the marginal cost of the resource. In this situation, the cost is generally low. Indeed, on the one hand the cost of transporting and packing the biomass is frequently small and, on the other hand, the route will very frequently operate using fixed production factors at a zero opportunity cost. In this way, the recovery of the biomass will often make it possible to valorise permanent and under-employed manpower and equipment at certain times of the year. Under such conditions, with the utilisation value frequently greater than the cost, a surplus (which is represented by the area between curves [0] and [D]) is obtained by the producers, who are also the utilisers. Requillart [2] has estimated this surplus for the combustion of cereal straw. 3. TRADING EXCHANGES AND DISAPPEARANCE OF THE SURPLUS (Graph II) With subsistance farming, only a small quantity of resources can be used under suitable economic conditions. Energy self-sufficiency, or the valorisation of all a producers resources, is not necessarily justifiable from an economic point of view. This means that, if the resource is to be exploited more completely, a market must be set up between the producers and the utilisers. In this case, however, the surplus disappears because of the coming into play of two phenomena which reinforce it: amplification of the costs of the biomass leads to an upward movement of the supply curve; reduction of the utilisation values is expressed by a downward movement of the demand curve. How to explain this scissor effect which causes the surplus to disappear? Insofar as concerns the supply, transport and packing costs lead to a first cost increase but, contrary to what is commonly assumed, these are not the only factors which do so. Two other mechanisms influence the increase. In the first place, the producer’s behaviour will change. To start with, he will want to obtain remuneration from all the production factors employed, including the available fixed factors which had not previously been monetarised on account of their availability. After this, the decision to sell assumes that the individual stakes will be too small on account of the risks undergone and the organisational stringencies. Since each producer owns a small quantity of the resource because of the parcelling of the production structures, a sufficiently attractive price must be proposed by the purchaser to incite the producer to make the exchange. This phenomenon has been measured by Cochin [3]. Secondly, costs will also be increased by rents. The purchaser, faced with a multitude of different bidders, will have to line up his purchase price on the proposal made by the last bidder necessary to attain the quantity required. This last bidder, qualified as marginal, sets the price which is imposed on all. Under such conditions, differential rents will fall to the best-placed bidders. The utilisation value will diminish simultaneously to this. Several phenomena are at the basis of this reduction: on an enlarged scale, biomass undergoes very heavy

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competition from fossil vectors which are even cheaper (natural gas, heavy fuel and coal). Also, a legitimate desire for reliable supply will lead any biomass utiliser to equip himself with a bi-energy system. This slows down the scale effects. Finally, the rate of return of the capital will be that of industry which, on average, is greater than that of agriculture. 4. CONCLUSIONS For the reasons set out, the valorisation of biomass is limited to the field of subterranean economy, and it almost exclusively concerns dry by-products. as for the exploiting of energy cultures, this makes all the surplus disappear on account of the production costs and the competition for allocating the land. The economic constraint described is of a durable nature because, fundamentally,

GRAPH I

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GRAPH II

it stems from the atomisation of the production structures, structures which develop extremely slowly, as we know. This is one of the essential reasons why the growth in the production of energy from biomass will remain so slow. In [1], additional production of 2 Mtoe is anticipated for the nineties. This is the dilemma which must be solved if biomass is to become an energy in its own right. State aid cannot suffice today. Increased productivity on the one hand and the increase in the price of oil, inevitable at long-term, on the other, should make it possible within a time which is difficult to predict, for trading exchanges of biomass to emerge, no doubt in connection with a synergy between food and industrial valorisations organised around various industrial poles. The organisation of short trading circuits, especially with one finality only, does not appear today to meet the demands of the industrial valorisation of biomass, which are competitivity and security.

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REFERENCES [1] SOURIE, J.C., and JAYET, P.A.—Les valorisations énergétiques des biomasses. Difficultés et promesses. Revue de l’ENERGIE, Oct. 1984, n° 367, Paris, pp.643–652 [2] REQUILLART, V.—Valorisation énergétique des pailles de céréales. PYC Edition, 1984, Paris, 157 p. [3 COCHIN, B.—Un modèle économique de filières de récupération des pailles. INRA Economie Rurale, GRIGNON, 110p. 1977.

FUEL ETHANOL IN BRAZIL AND THE IMPLICATIONS FOR CONTROL OF LEAD ADDITIVES IN THE EEC COUNTRIES F.Rosillo-Calle Technoloy Policy Unit University of Aston, Gosta Green, Birmingham, UK Summary Nearly 30 countries, industrialized and developing ones, have or are planning alcohol fuel programmes. This world-wide attention stems from oil price increases in the 1970s, foreign exchange considerations, boosting properties of alcohols, the fact that it can be produced locally, and the minimum adjustment requirements of many engines now designed to run on petroleum fuels. In the U.S. alcohol blends now contribute between 4.5%–5.5% of the US gasoline market. But it is Brazil who has the world’s largest alcohol fuels programme aimed at substituting fossil fuels. From 1975–1984 Brazil has produced 39.1×109 litres of alcohol, mostly for fuels (fig.I). About 1.8 million vehicles are alcohol-fuelled; the rest, circa 8m., run on 20–3/80–77% ethanol/gasoline blends. In 1984 c.90% of all vehicle sales were powered by alcohol (fig.II). It is possible that 11–14 million cars will be fuelled by alcohol by the year 2000; consumption estimates put it at 28–60×109 litres if alcohol was to replace diesel oil in Brazil. The growing demand for unleaded gasoline has further highlighted interest in alcohol fuels. The ProAlcool has enabled Brazil to accumulate much experience and technological know-how in alcohol fuel technology. This paper will examine the utilization of alcohol in cars and heavy vehicles, alternatives to diesel oil under study, the properties of ethanol as booster, emissions control and its relevance to Western Europe (WE).

1. Innovations During the first years of the ProAlcool preference was given to the passenger car which has reached already a maturity stage. A more recent development has been the utilization of ethanol in trucks and tractors which represents a new phase of ProAlcool (fig.III). By 1987 the sugar and alcohol industries would be using exclusively ethanol fuelled equipment with special allowances for reduced quantities of diesel oil and dual-fuelled engines. There are already various engine systems ready to enter this market. (A) Ottocycle, alcohol engines which includes: (i) original petrol engine design; (ii) original

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diesel engine design; (iii) specifically designed engines for alcohol. (B) Diesel-cycle alcohol engines, this includes: (i) additives+alcohol; (ii) pilot-ignition. As for tractors, the world’s first commercial alcohol-powered tractor—the CBT-3000, was launched in May 1980 and today all major manufacturers have alcohol models. Almost 55% of Valimet sales and 36% of Massey Fergusson’s in early 1984 were alcohol models. In just a few years Brazil has been able to transfer 60 years of experience with the gasoline engine on to the alcohol engine, though experiments with the alcohol car go back to the 1920s. Four major features can be distinguished in the history of the modern alcohol-fuelled vehicle. (A) From 1975–1979 it consisted mostly of an experimental fleet and major R &. D efforts. (B) 1979–80 when government and industry signed the first agreement for mass production of alcohol cars; significant fuel improvements were achieved. (C) The 1981– 82 period sees the rapid expansion of sales. (D) 1983 onwards, consolidations of the alcohol vehicles, commercially and technically. Though the first model consisted basically of minor modifications, it is a new mechanical concept with 300 engine parts, different to the conventional gasoline engine. The Otto-cycle alcohol engine has a thermal efficiency of 36%–38% against 27% of the equivalent gasoline (25% in Brazil) and could be further improved to c.42%, that will more than compensate for the lower calorific value of ethanol. Although many innovations need to be incorporated, particularly microelectronics, most technical problems caused by the alcohols have been solved. The most serious problem concerns diesel fuel substitutes, for which a diversified policy is being pursued. 2. ProOleo This programme commenced in 1979 with the aim of finding a solution to Brazil’s diesel problem. The results have not been entirely satisfactory for economic and political reasons rather than technical ones. Firstly there have been conflicting priorities and objectives between Federal Government and the heavy vehicle manufacturers. Government demanded that the diesel-cycle engine should be modified to accommodate the fuel whilst manufacturers maintained that a new fuel more suitable to existing engines should be found because of the high investment required for engine modification. A compromise between these two views seems to be emerging. Secondly the large amount of vegetable oil required, in addition to the high demand for cooking oil and the high price in the international market, makes this option politically unattractive. Hence a number of alternatives are being pursued: (a) changing the refining cracking system so as to produce the maximum possible amount of diesel oil from a barrel of petrol; (b) use of ethanol as diesel oil substitute, and for which there exist four major alternatives: (i) additivated ethanol; (ii) dual-injection motor—this involves the use of a small amount of diesel to ignite combustion by adding a second ignition pump; this can replace 85% of diesel; (iii) glow plug used as temperature control, a 20%–22 increase in fuel efficiency has been achieved; (iv) substitution of the Diesel-cycle by the Otto-cycle engine. This option is being promoted by the sugar-alcohol industry;2 (c) use of vegetable oil in increasing quantities, depending on price and availability; (d) use of additives either to ethanol or diesel; (e) diesel+methane in 60%-100% blendings, under investigation including methanol. (f) development of a new engine or modifying significantly the

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diesel-cycle engine. We shall consider the two most important options, vegetable oils and additives. 3. Vegetable Oils Despite all the difficulties this option remains one of the most promising. The alternatives investigated include: (a) direct use of vetable oil. This includes (i)utilization of 100% vegetable oil; (ii) vegetable oil+diesel; (iii) vegetable oil + diesel+ethanol; (iv) diesel+additives; (b) chemical modification of vegetable oil which includes (i) oil catalistic cracking; (ii) thermal cracking (fig.IV)3 4. Additives This is becoming increasingly important in many countries like the United States and Western Europe due to regulatory steps to reduce the use of organic lead compounds in gasoline. Important replacement candidates for tetraethyl lead and tetramethyl lead are ethanol, methanol, methyl butyl ether (MTBE) among others. In Brazil many tests have been carried out to establish the validity of ethanol as an octane enhancer and gasoline extender (fig.V). These findings demonstrate: (i) a lower fuel consumption due to an increase in engine efficiency; (ii) lower cost in the refinery process which use less refined oil; (iii) non-use of tetraethyl lead as an octane booster. A 20% ethanol blend increases the MON to a minimum of 80.3–84.3, depending on the composition of basic gasoline. The use of unleaded gasoline in Western Europe by 1987 will demand significant changes in fuel, engine, refining process, etc. A complete changeover to 95 RON unleaded gasoline will require additional investment of $2.7bn. Unleaded gasoline will add 4% extra cost and 5% fuel increase—due to exhaust emissions control—to a typical motorist, and diesel fuel quality will deteriorate with cetane number dropping 3–5 points by 1995. Most of these problems could be partly avoided if an ethanol blend is used in Western Europe. Brazil’s experience demonstrates the advantages of using ethanol as an octane booster and for emissions control. Other important additives include the tetrahydrofurfuryl nitrate (THFN) and tri-ethylene glycol dinitrate (TEGDN) which can be obtained from renewable raw materials. The THFN is produced from furfuryl obtained from sugar cane bagasse, but can be obtained from straw, cotton seed, corn cobs, industrial fibrous waste, etc. The TEGDN is produced from ethanol via ethane and subsequent nitration by conventional means. Both are excellent boosters, particularly with diesel oil blends. 5. Emissions Numerous studies have confirmed the effectiveness of ethanol in reducing emissions, particularly in U.S. and Brazil. Fig.VI shows the main findings by CETESB, in Sao Paulo, after eight years of research. It is particularly positive with CO, HC and COx emissions, the main pollutants associated with vehicles. Aldehydes emissions are much

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higher, but it is less serious. Other data with regard to 100% alcohol cars shows a 66% lower CO, 25%-79% HC; 11% in NOx when compared with gasoline, while experiments in Ford Brazil 1980 models 20%/80% ethanol gasoline blends, shows a 57% reduction in CO, 30% in HC and 15% increase in NOx.7 6. Economics There exist two main and simple ways of exploiting the properties of ethanol (i) by producing low octane gasoline; (ii) by increasing the octane value of all motor fuels so that compression ratios can be increased. Though there exists uncertainty in the amount of premium fuel that can be saved at the refinery by using ethanol as a boosting additive, estimates range from zero to 60,000 BTU/gal of ethanol used, depending on the gasoline pool, the octane boost achieved from ethanol etc. The OTA estimates on energy saving of 0.4 gal. of gasoline equivalent for each gallon of ethanol used, based on an average of a good octane requirement of 91.8 Conclusion Brazil’s experience demonstrates the validity of ethanol as octane booster and for lowering emissions. The EEC will need large investment to change over to unleaded gasoline. Italy is already considering the ethanol option. Brazilian know-how and experience could easily be transferred since major European companies are involved. Hence the utilization of ethanol gasoline blend in the EEC should be recommended because (i) its effectiveness as octane booster and less environmentally hurtful fuel, has been largely demonstrated; (ii) a proportion of ethanol can be obtained within the EEC, particularly from agricultural surpluses. Eliminating sugar beet surpluses will also assist Third World sugar cane producing countries whose markets for sugar have been eroded by heavily subsidised EEC exports; (iii) large energy savings in the refining process are possible. Buying unleaded gasoline is not only more expensive, but would further increase external vulnerability; (iv) ethanol cost can be greatly reduced, production costs in the US are much higher than in Brazil; (v) Brazil has an enormous potential for ethanol production and already is looking for alternative markets for its large surpluses. References 1. Bindell, H.W. (1984) Implementation experiences with MWM PID Diesel Engines burning Alcohol as Main Fuel; Proceed. IV Intern. Sympos. of Alcohol Fuels Technology, Canada May 21–25:56–62. 2. Ventura, M. et al (1982). First Results with M.Benz DI Diesel Engines Running on Monoesters of Vegetable Oils; Int. Conf. on Plant and Veg. oils as fuels, Fargo, N.Dakota. US. 3. Mercedes Benz do Brasil. 4. Anon. EEC Lead ruling a boost for oxyginated uses, European Chem.News, 73(1145) 20 Sept.1984. Road Transport Fuels in W.E., Chemical Systems International Report. 5. O Estado de Sao Paulo,, 15 Sept, 1984 p.70.

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6. ACT. Conselho Nacional do Petroleo (C.N.P.) Feb/1984. 7. Celestino Rodriques, E. (1983), Solucao Energetica, Editoras Unidas, S.Paulo. 215ff 8. OTA (1980) Energy From Biological Processes, Vol.II, Technical and Environ, Analysis: 204– 207. 9. Hall, D (1984) Photosynthesis for Energy. Advances in Photosynthesis, Vol.II, Martins and Junk Publishers, The Hague.

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Fuel ethanol in brazil and the implications for control of lead additives in the eec countries

Source: CETESB

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RESIDUE BRIQUETTING IN DEVELOPING COUNTRIES S.Joseph and D.Hislop, Intermediate Technology Development Group SUMMARY Briquetting projects in developing countries have largely -failed. Equipment is often large scale, expensive, energy intensive and difficult to maintain and rapair. Planners rarely match the briquettes produced to user needs, or consider the need for stove modifications, or for marketing or distribution requirements. The paper indicates a systematic approach to briquetting projects, and outlines recent developments in raw material treatment. These dramatically reduce energy requirements for briquetting and widen technology choice, especially in small scale briquetting.

1. BACKGROUND The experience of briquetting in developing countries is not encouraging, especially at the small scales which would allow the use of de—centralised sources of residues and create employment in rular areas. The few viable plants tend to be medium to large scale, using residues from agricultural processing plants to which they are linked. There are several reasons for this. First, briquetting equipment is usually designed in and for developed countries. It uses high pressures, and production is often affected by the lack of technical skills, spares (especially of dies), and the lack or high cost of diesel or electric power. Second, supplies of residues are often unreliable because of fluctuations in crop production, other uses of residues closer to their source, and transport problems. Third, although the briquettes may be suitable -for industrial use, in domestic stoves they are often inconvenient, inefficient, or give off unpleasant smoke and fumes: user acceptance in a number of well-documented cases has been minimal. Careful study of user requirements and re-design of stoves can overcome these problems, but this is often a major undertaking, and one rarely acknowledged by those proposing or undertaking briquetting projects. 2. EXAMPLES OF BRIQUETTE PROJECTS. An example of a briquetting project which failed to take into account some of these issues comes from the Gambia. In 1980 the manufacture of charcoal was banned, and a briquetting plant was installed at a large groundnut shelling plant near the capital, Ban jul. Briquettes was manufactured successful ly, but they were accepted neither by the existing -fuel marketing and distribution systems nor by consumers. Retailers did not have adequate storage space and had to travel to obtain supplies; existing charcoal stoves would not burn the briquettes efficiently, and produced an acrid smoke that tainted food

Residue briquetting in developing countries

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and irritated eyes and lungs. After a year of production the sophisticated control mechanism of the briquetting plant broke down and could not be repaired locally: production ceased. However, given the shortage of wood, it was clearly necesary to remedy matters. A survey of consumer stove and briquette requirements was carried out (1), and on the basis of the data obtained ITDG worked with local metal workers on the design and manufacture of an appropriate stove. To eliminate smoke problems ITDG tested the stove at its research centre at Reading using gas analysis techniques. Careful positioning of primary and secondary air holes reduced CO and unburnt hydro—carbon emissions to less than 0.1% and gave stove efficiencies of about 30% (2). Sixty improved stoves were manufactured in the Gambia in 1983 and tested in households. The briquette plant was repaired and a more effective distribution network developed, and over 1000 stoves wre built and sold until production stopped on the death of the plant owner. A second example is the Sudan, where ITDG was asked to carry out a feasibility study of ground-nut shell briquetting. There were similar problems to the Gambia, with the additional one that the prospective raw material was in increasing demand as fertiliser and fodders evaluation of the project suggested that -from a national economic point of view it would be a retrograde step to use the shells for briquettes. 3. THE NEED FOR NEW APPROACHES TO BRIQUETTING. These and other projects reviewed by ITDG and other groups in Africa and Asia indicate that four major issues must be addressed before viable small scale briquetting operations can be developed. (i) Residue availability. Residue production and existing end—uses must be determined for each proposed project location, to ensure that sufficient residues are actually available for briquetting at acceptable financial and opportunity costs. (ii) Technology choice for briquette and for briquette end-use. The size and shape of briquettes, and the type of furnace or stove acceptable to users and capable of burning the briquette efficiently, must be matched: development work wi 11 often be needed for this. (iii) Technology choice for briquetting. The range of briquette production technologies needs to be expanded and developed: the choice of technique within this range must take account of the characteristics of the proposed briquette, of the local production environment, and of the local power supply situation. (iv) Marketing and distribution requirements need to be taken into account at an early stage of project consideration. While in its project activities ITDG is concerned with all these issues, the object of its technical work is to widen the technical options available for briquetting: it; is with this issue that the rest of the present paper is concerned. 4. EXISTING TECHNOLOGY CHOICES FOR BRIQUETTING. Existing briquetting technologies almost all derive from European or American technologies, and are of the following types. Screw extruders force the raw material to flow along the passageway of the screw as it revolves within a cylinder. High

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temperatures and pressures are generated, and bonds the particles into briquettes produced in continuous lengths or into disks. Screw extruders produce 300–750kg per hour and require 70–80kWh of energy/tonne of briquettes. Piston presses compress the material with a ram driven by a flywheel, the correct amount of material being fed into the cylinder at each stroke. Partial compression during the feeding process can increase briquette quality. Capacity of large piston presses is about 2 tonnes/hour, with an energy requirement of 25–30kWh/tonne and pressures of 100–300Mpa. Rol 1 presses consist of two rolls, with rows of holes machined in them, which rotate against each other in opposite directions. The holes line up in rows, and material -fed between the rolls is compressed in them. Capacity is 1–50 tonnes/hour, with energy requirements of 2– 16kWh/tonne at pressures of 300–500Mpa. With very few exceptions, powered briquetting equipment is capital intensive, manufactured from high quality steels, requires continuous maintenance, and is difficult to repair in developing countries. A number of hand powered presses have been developed. The simplest are based on the CINVA ram, which is a box, a lid attached to a lever arm and a bottom that can be levered up to remove the briquette. Pressures and outputs do not exceed 1Mpa and 200kg/hr respectively. Binders are always required. More sophisticated human or animal powered presses have been developed by VITA and IIT Delhi, using pressures of up to 15Mpa and outputs up to 150 kg/hr. The data available suggests that human or animal powered briquetting systems are not viable because of the need For binders and/or the relatively low rates of output. 5. WIDENING THE TECHNICAL OPTIONS AT THE SMALL SCALE. To counter the disadvantages of existing briquetting technologies, ITDG has investigated more efficient and lower cost methods of briquetting, especially on the small scale. The work of the Shell Research Centre in Amsterdam and of Reed (3), suggested that grinding or pre-heating the raw material might reduce the power required for briquetting, allow higher quality briquettes for a given energy input, lower wear on dies, or a combination of these. The principle is that as particulate ligneous biomass materials are heated at about 220C thermal decomposition begins. Initially, water and CO2 are given off, and then the volatiles. As this happens the Fibres begin to soften, the energy required for a given degree of compaction is greatly reduced, and the volatiles act as a binder. Reed (3) suggested that briquettes with a density of 1–1.1 tonne/cu. metre and shelf lives of at least one month could be produced -From ligneous materials preheated to certain temperatures for certain periods of time at pressures of 15–30 MPa, with energy inputs of less that 10kWh/tonne. In response to a request for small scale papyrus briquetting technology in Kenya, ITDG is investigating the use of preheat with papyrus. A cylindrical press has been used to find the minimum pressure, and degrees of preheat and shredding required for the production of briquettes with a density of 0.9–1.1 tonnes/cubic metre and a shelf life of at least one month. Shelf life is tested using the technique developed by the Centre de Recherche Agronomique, Gembloux (4) which measures briquette elongation, first at 20C and 95% humidity for one month, and then when placed in water. Load/contraction curves have been generated for ground and preheated, and for unground and unheated

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samples of papyrus briquettes (density=1.15 tonnes/cu. metre), for pressures up to 40Mpa for heated and up to 180MPa for unheated samples.

Figure 1. Load/Contraction Curves for Papyrus Briquettes.

Preliminary results are presented in figure 1. Papyrus briquettes were produced at pressures of 25–30Mpa with pre-heat, compared to pressures of approximately 180Mpa without pre-heat. So far shelf life has been measured for two weeks at 95% humidity and 20C, giving elongation of 6%. If shorter shelf life can be tolerated, or if storage is in dry conditions, pressures as low as 15Mpa can be used. Similar results are expected from other ligneous residues. More detailed tests will be reported by the middle of 1985. The implications of these results are as -follows. First, existing briquetting plant modified for pre-heat should operate at lower pressures, wear rates and power requirements: in turn, simpler, lower cost machinery can be developed for, and manufactured in, developing countries. Second, lower power requirements and the need for preheat make combined heat/power operation an attractive option. Preliminary estimates suggest that 8–13% of the raw material would provide the necessary heat, depending on whether the plant is steam, diesel or producer gas powered. of particular importance is the fact that steam powered briquetting plant could be totally independent of external energy sources. Third, the level of output at which economies of scale operate is reduced: small briquetting plant able to take advantage of de-centralised sources of raw materials becomes more viable. Fourth, in areas of low humidity or short shelf life requirements, human or animal power becomes more feasible. The IIT Delhi animal

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powered press and the VITA foot press (5) are two examples. Where humidity is higher or longer shelf life is required, a human or animal powered hydraulic press may be necessary. 6 ECONOMIC VIABILITY. So far full scale plant to utilise the new processes has not been built. However, estimates based on experimental work and on data for existing briquetting plant suggest that in Kanya a steam driven plant with a capacity of 1000 kg/hr of papyrus briquettes could be manufactured locally for US$ 8000. It would be economically viable at a capacity utilisation of 50%. Estimates for human powered groundnut-shell briquetting in Gambia using an adapted VITA foot press suggest that at a capital cost of $5OO a plant would be viable at an output of 81 tonnes per year (46 kg/hr) tonne. Ownership of small briquetting plant with de-centralised sources of raw materials and unreliable supplies is a difficult issue, and innovative forms of ownership may be necessary. Small mobile units are one option, as are cooperative units. In either case the plant might purchase raw materials, or operate on a custom basis with payment in cash or kind. REFERENCES. (1) Von Bulow D. Evaluation of Groundnut Shell Briquetting in Gambia. Hoff and Overgaard, Copenhagen, 1978. (2) Joseph S and Loose J. The Design of Groundnut Shell Briquette Stoves for the Gambia. ITDG, London, 1983. (3) Reed T et al. Biomass Densification Energy Requirements, in Thermal Conversion of Solid Wastes. ACS Symposium Series, Washington DC, 1980. (4) Centre de Recherche Agronomique, Gembloux, Belgium. Upgrading Ligneous Raw Materials into Useful Fuels. EEC, Brussels, 1984. (5) Lippert J.R. Briquetting. Volunteers in Technical Assistance, Langley, Virginia, USA. 1984.

AN ECONOMIC PROCESS FOR THE PRODUCTION OF A DIESEL FUEL SUBSTITUTE FROM EDIBLE OIL FRACTIONS H.P.Kreulen, H.C.A.van Beek, E.van der Drift, G.Spruijt Summary This paper is a presentation of a study to investigate the reaction variables of the transesterification of high melting palm oil fractions with ethanol and to determine the economic viability of the production of mono-esters as a diesel fuel replacement in developing countries.

1. INTRODUCTION The research into the performance of vegetable oil esters as alternative diesel fuels has made considerable progress in recent years. The reports given at the International Conference on Plant and Vegetable Oils as Fuels in Fargo, August 1982 (1), 73th AOCS Annual Meeting in Toronto, May 1982 (2), and 74th AOCS Annual Meeting in Chicago, May 1983 (3) show promising results as demonstrated in various types of diesel engines. A main limiting factor for further development is the high price of vegetable oils related to petroleum products. Tropical countries, where the oil palm is grown have the advantage of the highest yielding oil producer. Harvests of 4,500kgs/ha annually are common. The world market price for palm oil, which is one of the less expensive oils, is about US$ 550 per ton; about twice the import price of diesel fuel. Furthermore vegetable oils are primarily considered as a food product in these countries. It is possible however to separate palm oil by selective fractionation into a liquid edible oil and a solid product with a melting point of 56°C, which is unsuitable for human consumption. Ethylesters were made from the low value fraction and alcohol produced from sugar cane molasses. Cost price calculations indicate that the diesel fuel substitute can be produced for approximately US$ 210 per ton. The authors are: H.P.Kreulen, Senior Consultant, HVA-International BV, Amsterdam, The Netherlands. H.C.A. van Beek, Professor, E.van der Drift en G.Spruyt, graduate students, Laboratory of Chemical Technology, University of Technology, Delft, The Netherlands.

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2. THE PROCESS 2.1 Recovery of the High Melting Palm Oil Fraction In the majority of the tropical countries where palm oil is produced, the oil is separated into a liquid and a solid fraction by a single fractionation process. (4) The liquid fraction with a melting point of 21°C has a yield of approximately 60 per cent. This yield can be improved to a level of 70–75 per cent by double fractionation. In this process palm oil is cooled to a temperature of 20°C., where after the solid fraction is separated by filtration from the liquid oil. The solid fraction is, after heating, cooled to 38°C. The solid part with a melting point of 56°C is separated by filtration from the liquid part, which is recycled to the entering palm oil for fractionation at 20°C. Diagram 1 shows the material balance of the double fractionation process.

Diagram 1 Process for double fractionation The solid fraction, separated at 38°C, representing 25–30 per cent of the palm oil, contains 70 per cent palmitic and stearic glycerides. The fat is unsuitable for human consumption by reason of the melting point of 56°C. It can therefore be considered as a by-product, that only can be exported to industrialized countries at a low price. The fat is suitable for the production of monoesters. 2.2 Ethanol Ethanol is a common product in tropical countries, produced from the by-product molasses of cane sugar factories. The production of absolute alcohol as a substitute for gasoline in automobiles is included in the energy programs of many developing countries. It is worthwhile to investigate the dehydration step to absolute alcohol with a hygroscopic solution of potassium-carbonate in glycerol, described by Mariller. Glycerol is a by-product of the transesterification process.

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Since ethanol is easier to produce than methanol in developing countries, the authors have a preference for the application of ethanol as reacting agent. 2.3 The Transesterification Process The transesterification of triglycerides with lower alcohols has been studied extensively. Several papers review recent findings. (1) The Palm Oil Research Institute of Malaysia will start in 1985 the research on the production of palm oil monoesters with methanol in a plant with a capacity of 20,000 litres per day. It was the objective of the study to test the principles of the reaction with high melting fractions of palm oil. 3. EXPERIMENTAL The conversions of the saturated triglycerides obtained from palm oil into the ethylesters were carried out in a flask of 500ml equipped with a stirrer, thermometer and a reflux condenser. The air inlet of the equipment contained a CaCl2. O aq de-siccatortube to exclude atmospheric moisture. Palm stearin (100g; 0.12mole) present in the flask was heated to 75°C. A solution (85ml; 1.45mole) of KOH in absolute ethanol in varying concentrations was added. The mixture was stirred and heated to the reflux temperature (88–93°C). At different reaction times samples (1ml) of the solutions were taken. The samples were neutralised with hydrochloric acid, diluted with ethanol and analysed by a GLC (Packard 438, 3% SE-30 chrom WAW) column, using temperature programming (200–260°C, rate 6°C min−1), calibrated with standard samples. The catalyst concentration used varied between 0.1–1.0g KOH per 85ml of ethanol. It was found that a high conversion takes place in very short reaction times (5– 10min.). After this period no further conversion was observed up till reaction times of 120min. The yield of the conversion, however, increased when increasing amounts of catalyst were used. The data concerned are presented in table 1 together with the values of the specific gravity, viscosity and refractive index of the ethylesters, which were isolated from the reaction mixture. Separation of the ethylesters was carried out by distilling the excess of ethanol at 80°C, diluting 40ml of the residue with 200ml 50% ethanol in water, containing 1g sodiumchloride and 200ml. n. hexane and separating the resulting organic layer from the aquous layer. Distillation of the former then yielded the ethyl-esters, while from the latter glycerol can be isolated by distillation.

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Table 1. Conversion rates and properties of palm oil ethylesters KOH gram

conversion %

0.10 0.25 0.50 1.00 Literature 80–99

80 82 84 94

specific gravity g.ml.−1

kinematic viscosity cSt 40°C

0.864 0.852 0.847 0.856 0.870

refractive index

4.4 – 4.6 – 4.5 1.4439 4.6 1.4447 4.4 1.4552–1.4530

4. DISCUSSION From the results obtained it can be concluded that conversion of high melting palm oil fractions into ethylesters by transesterification in ethanol using KOH as a catalyst proceeds rapidly at 80°C and results in a high yield. The fact that this yield increases with increasing catalyst concentration must be ascribed to the fact that part of the catalyst is inactivated during the process. This inactivation is probably due to the presence of small amounts of water which causes hydrolysis of the esters and results in the formation of fatty acids. The latter can react with the catalyst to form the corresponding inactive potassium salts. This implicates that the highest yield found can also be obtained with the lower concentration of catalyst if more rigourous exclusion of water is applied. High conversions are of importance for economic reasons but also because the product then has a low residual fatty acid triglyceride concentration. The high reaction rates obtained even with the lowest catalyst concentration indicates that the process can be very effective and is probably also suitable for continuous operation. The ethylesters obtained were found to possess similar specific gravity, viscosity and refractive index as the corresponding esters produced from other vegetable oils. The conclusion can therefore be drawn that those esters can also be suitable for substitute diesel fuels. 5. ECONOMY In Table 2 the estimated costs for the processing of 6,000 tons of diesel oil substitute per year are detailed. The revenue for the by-product glycerol is not included in the calculations. Estimated Costs for Processing 6,000 Tons of Diesel Fuel Substitute per year. (Table 2) Capital investment of a 6,000 tons per year Diesel Fuel Substitute Facility: US$ 1 million Raw Material US$ US$ 6,000 tons palm oil fraction

(a) 600,000

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1,050 tons ethanol (b)

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231,000 831,000

Labour Utilities (c) Chemicals (d) Maintenance/Repair (e) General Costs (f)

65,000 40,000 50,000 91,000 50,000

Depreciation (g) Interest (h)

91,000 59,000

296,000

Total Cost of Production Cost per Ton: US$ 213. a. Hard palm oil fraction US$ 100 per ton b. Ethanol (99% vol) US$ 220 per ton c. Steam, Electric Power d. Catalyst, Hexane, Chemicals

150,000 1,277,000 e. Maintenance/Repair, 5% Equipment, 2% Buildings f. Insurance, Sundries g. Depreciation 10% equipment 4% buildings h. Interest (14%) over loan (60% of investment)

6. CONCLUSIONS The economic evaluation indicates that the process deserves consideration for its development in countries where palm oil is produced and which suffer of a shortage of foreign currency to import their petroleum products. References (1) Papers from the International Conference on Plant and Vegetable Oils presented at Fargo, North Dakota, August 1982. ASAE publication 4–82. (2) Papers from the Symposium on Vegetable Oils as Diesel Fuels presented at the 73th AOCS Annual Meeting, Toronto, Canada, May 1982, JAOCS 60:1557 (1983). (3) Papers from Symposium on Vegetable Oils as Fuel Alternatives presented at the 74th AOCS Annual Meeting, Chicago, Illinois, May 1983, JAOCS 61: 1609 (1984) (4) Kreulen, H.P., JAOCS 53: 393 (1976). (5) Freedman, B, Pryde.E.H. Mounts.T.L, JAOCS 61: 1638 (1984) (6) Graille.J, Lonzano.P, Geneste.P, Oleagineux 37: 421 (1982) (7) Kusy. P.F, ASAE publication 4–82: 127 (1982).

THERMOCHEMICAL PROCESSING OF LIGNOCELLULOSIC RESIDUES: ALTERNATIVES IN THAILAND D.L.PYLE & C.A.ZAROR Department of Chemical Engineering, Imperial College, London SW7 2BY ABSTRACT The feasibility of using solid residues depends critically on local conditions. This work examines residue availability in Thailand—based on field work studies—and then compares options for thermochemical processing on the basis of economic and non-economic indicators. The methodology and the detailed results should be of interest to other applications.

I) INTRODUCTION Enormous amounts of solid residues are generated yearly in many Third World countries. They are often inadequately utilised although potential products may be in demand. The current economic climate and the need to develop local industry make it urgent to seek efficient uses for such resources. However, the question of residue utilisation involves technical, economic, social, and political issues, and complete assessment of alternative uses is lengthy and costly. We outline here a methodology for preliminary selection. The discussion of the method is illustrated by evaluating alternative uses (for energy) of residues in Thailand. II) PRELIMINARY ASSESSMENT OF RESIDUE USE: LIGNOCELLULOSICS IN THAILAND Figure 1 outlines a method for selecting the most attractive options for development or investment. The first stages are concerned with generating a set of technologies which are technically and economically feasible. Decisions must reflect the uncertainties in the procedure; options are only rejected if clearly unfeasible. The final stage is to produce a qualitative decision matrix on which the attributes of the technologies are displayed on a simple ordinal scale. The procedure is discussed very briefly here, together with the summary results of our study on resource use in Thailand. a) Assessment of resources: A complete survey of resource availability needs extensive fieldwork; for preliminary assessment, production statistics supplemented by selected visits should suffice. The exclusion of non-commercial production from statistics is often a source of error;

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estimates of residues available will be very approximate. Agriculture accounts for about a quarter of Thailand’s GNP and occupies more than three quarters of its population, considerable solid residues are generated at harvest and industrial processing. Table 1 shows estimates of some principal cellulosic residues and their energy content. The net availability of residues depends on current use: data-especially on noncommercial use—is often very poor. It is however necessary for estimating net availability and opportunity costs; the latter is discussed in more detail below. In Thailand, some residues, (eg. wood wastes, bagasse, rice husks) are important fuels; others, e.g. rice straw, are used as feed or fertilizer. Coconut and palm shells are concentrated near processing centres, and are underutilised. Some are used domestically; due to corrosion they are not favoured industrially. More data is needed to translate Table 1 into estimates of net availability. b) Markets for potential products. A wide range of products can be obtained from agricultural residues fuels, feedstuffs, fertilizers, and chemicals. Preliminary assessment does not need detailed market study; potential demand can be estimated from import/export, and consumption statistics, or from basic needs. Potential end uses include: import substitutes, on-site use, and new products. We focus on products from thermochemical processes. Charcoal is currently imported into Thailand and sells at ; is widely used as a domestic and industrial fuel in Thailand; of f icial estimates are of 400,000 Tonne charcoal per year; other sources report figures 8 times larger than this (USAID (1979)). Other condensed pyrolysis products are also imported, representing a total cost of . Current prices for liquid pyrolysis products are: Tar, Acetic Acid, wood spirit. Activated carbon is imported at an import price of . c) Technology assessment. Biomass resources mainly comprise cellulose, hemicellulose, lignin, starch, sugars, and minerals. The number of process options for resource recovery is large (Table 2). Reviews of the technologies include Earl (1975), Pyle & Zaror (1983), Foley & Barnard (1983), Rehm & Reed (1982)). Here we concentrate on thermal processes leading to the formation of charcoal, pyrolytic gases and liquids, and activated carbon, and combinations of each. Small and large operations are considered. The product distribution from pyrolysis depends on the conditions and raw material. Low temperatures and slow heating rates favour charcoal and liquid formation. Typical yields, based on dry charge, are: charcoal=15–40%w/w, liquids=15–50%w/w, gas= 0– 30%w/w. Activated charcoal is obtained from charcoal above 800°C in the presence of steam and/or CO2. (Soltes & Elder (1980), Pyle & Zaror (1983)). The high free carbon content of pyrolysis charcoal from shells makes it attractive for activated carbon production.

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For rational choices information is needed on technical parameters (eg. energy inputs, product yields, labour inputs), capital costs, the ‘relative advantage’ for local operation and development of the technology, and environmental impact. d) Financial/Economic assessment. A simplified method may serve for preliminary economic filtering. We use the breakeven capital investment (i.e. to give Net Present Value= 0). Assuming constant annual flows of operating costs (C) and revenues (B), constant prices and discount rate (i), and infinite project lifetime, the breakeven capital investment (K) is (Pyle & Zaror (1984)): K=(B−C)/i This can be compared with values of the capital requirements for the particular technology (K′) (obtained from literature or by short cut estimation). For R=K/K′>>1 the option is promising; for R<<1 the option is unattractive. Intermediate values indicate that further study might be justified. Finer ranking will depend on the accuracy of estimates. The sensitivity of the net revenue to costs should always be inspected; this is quantified as the percentage change in breakeven capital investment per unit variation in input and output. When markets exist appropriate prices can be used, accounting for taxes or subsidies. Where commodities are not marketed, opportunity costs can be estimated given alternative uses and competing products. Estimation of the value of crop residues is controversial (Lockeretz (1981)). Two sets of costs are involved: those in collecting and delivering the residues; and their opportunity costs. The procedure can be adapted to include social costs and benefits. The availability and cost of the residues are crucial in the studies here. Some are conveniently available and underused; many however, are dispersed and their uses (and opportunity costs) unknown. In practice, estimating opportunity costs is a major problem due to the uneven patterns of use, and the lack of data on the effects of farm size and location. For simplicity we take two values for the opportunity cost: a) zero, b) 500Baht/tonne dry matter (around half the average price of fuelwood) . e) Assessment of environmental impact. Amongst the issues to be analysed are: the current environmental benefits/costs of residues and wastes and their treatment; environmental effects of the new technology and products (eg. new sources of pollution). These must be studied in the light of legislation, existing abatement procedures etc. The complete study (Pyle & Zaror (1984)) discusses these issues in detail. They are generally more relevant to the disposal of liquid wastes. III) Assessment and Conclusions. A complete report is beyond the scope of this paper. Here we report only part of a wideranging study (Pyle and Zaror (1984)): the assessment procedure concentrates mainly on

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economic viability. Table 3 summarises the results. In all cases, feasibility improves with larger scales. Charcoal production is very sensitive to the opportunity cost of the raw material: it is non-feasible for non-zero values. A clear improvement is seen when charcoal making is combined with recovery of saleable liquids, and, more so, when 50% of the charcoal is turned into activated carbon. Activated carbon production alone (case 4) is the least sensitive to the residue cost and performs well under the conditions reported here. The degree of complexity of the technologies considered differs considerably. Charcoal is produced using fairly simple and inexpensive technologies. Case 2 implies the condensation of troublesome liquids; the technology is more sophisticated and capital intensive, but experience in Brasil shows that relatively inexpensive and simple designs can be used. This would require a major R&D effort in Thailand. Cases 3 and 4 require high temperatures and tight control, and are unlikely to be suitable for village industry; investments, skills and technical support requirements are high. Although Case 4 is the most attractive, the technology would have to be imported, with increased burdens on the balance of payments.

FIGURE 1. GENERATING A DECISION MATRIX

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TABLE 1: AGRICULTURAL RESIDUES IN THAILAND. Production Year 1981/82 AMOUNT (103Te) YIELD (Te/ha) ENERGY CONTENT (106GJ)

RESIDUE (*) Rice Straw Sugar Cane Residues Rice Husks Various Stalks Nuts Husks & Shells Wood Residues Other Residues Animal Manure (dry)

26,658 10,268 3,554 16,787 471 4,220 1,992 11,580

2.75 17.18 0.38

224.3 106.3 49.0 93.9 4.8 76.0 17.1 127.4 698.8 161.2 473.2

Energy Content of Imported Petroleum Product (1982) National Energy Consumption from fossil & hydro sources (*) Non dry basis, as left after harvesting.

TABLE 2: OPTIONS FOR CROP AND AGROINDUSTRIAL WASTE UTILIZATION Processes: Products: SOLID FUELS LIQUID FUELS GAS FUELS FEEDSTUFFS CHEMICALS & OTHERS

THERMOCHEMICAL BIOCHEMICAL CHEMICAL EXTRACTION X X X

X X X X

X

X

X

X

TABLE 3: Comparison of alternative uses COMPARISON OF ALTERNATIVE USES OF SOLID RESIDUES SMALL SCALE. 0.50 Tonne Residue/day

Currency=‘000 BAHT LARGE SCALE. 10.00 Tonne Residue/day

CASE No. 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 Baht/Te Res.: 0.0 500 0.0 500 ANNUAL: 1 1 1 1 OP.COSTS 56 199 124 114 123 267 191 182 392 1290 1027 1196 1742 2640 2377 2546 REVENUE 73 267 279 486 73 267 279 486 1458 5346 5589 9720 1458 5346 5589 9720 NET REV. 17 68 155 372 −50 0 88 304 1066 4056 4562 8524 −284 2706 3212 7174 K,106B 0.1 0.5 1.0 2.5 0 0.6 2.0 7.1 27 30 57 18 21 48 R <1 >1 >1 >1 >>1 >>1 >>1 >1 <1 <1 <1 <1 >>1 <1 <1 <1 SENSITIV H. H. M. L. H. V.H. H. M. L. L. L. L. V.H. M. M. L. KEY: Dasc.Rate=15%, 270 days/year, V.H.=Very High, H.=High, M.=Moderate, L.=Low Case 1=Charcoal, Case 2=Charcoal+Liquids, Case 3=Charcoal+Activ. Carbon, Case

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4=Activ. Carbon Te Prod./Te Residue: Charcoal=0.3, Liquids=0.12, Activated Carbon=0.1 Product Prices ′000 Baht/Te: Charcoal=1.8, Liquids=12, Activated Carbon=36

REFERENCES Earl D.E. (1975), Forest Energy & Economic Development, Clarendon Press Oxford Foley G. & Barnard G. (1983), Biomass Gasification in Developing Countries, Earthscan, Techn. Report No.1, IIED, London Lockeretz W. (1981), Energy in Agriculture, p. 71, vol. 1, no.1 Pyle D.L. & Zaror C.A. (1983), ‘Pyrolysis of Biomass’, Proceedings of the Indian Academy of Sciences, Section C, vol.5, Pt.4, Dec. 1982. Pyle D.L. & Zaror C.A. (1984), Agroindustrial Wastes in Thailand: A Survey and Assessment of Treatment Methods, TISTR Report, ASEAN/EEC Scientific and Technological Cooperation Program, London/Bangkok. Rehm H. & Reed G. (1982), Biotechnology, 8 vols., Verlag Chemie, Weinheim, Florida-Basel. Soltes J.E. & Elder T.J. (1981), Chapter 5 in “Organic Chemicals from Biomass”, ed. by I.S.Goldstein, CRC Press Inc., Florida. USAID (1979), Project Paper for Renewable Non-Conventional Energy, Proj. No. 493–0304, USAID/Thailand, May 1979.

ENERGY FROM BIOMASS (PROGRAMME & POLICIES) D.P.Vimal & N.P.Singh Dept. of Non Conventional Energy Sources Ministry of Science & Technology, New Delhi Summary Biomass in its various forms offers potential scope to meet energy needs on a decentralised basis. With a view to bridge over fuelwood shortage and explore substitutes for fossil fuels, a number of programmes have been initiated by the Dept of Non Conventional Energy Sources (DNES) which include: establishment of biomass research centres under different agro-climatic regions, briquetting of agricultural and forest residues, alcohol production from energy crops, gasification of biomass, production of petrocrops and their conversion into petroleum hydrocarbons and development of a self-reliant energy system in agro industries. National Project on Biogas Development (NPBD), Community Type Biogas Plants (CTBP) and National Project on Improved Chulhas (NPIC) are some of the extension programmes initiated by the Department. During the Seventh Five Year Plan (1985–90), it is to meet local needs in the domestic, agricultural, industrial and transportation sectors to a significant extent.

Scope and Objectives of Biomass Programme Wood and agricultural residues have been in use since times immemorial but it is only recently that serious thought has been given to the problems of biomass conservation, production, conversion and utilisation on a rational and scientific basis. There are a variety of sources, diversity of technological options and a multiplicity of limiting factors: thus the whole problem has to be viewed in the form of ‘management issue’ so as to innovate different systems to deal specifically with the local conditions. The following are the main objectives of the biomass programme: – Conservation of biomass (wood, residues) through popularisation of improved chulhas; – Production of woody biomass on sub-standard soils; – Improvement of fuelwood yielding plants through cytogenetical, physiological and cultural practices; – Assessment of both terrestrial and aquatic biomass available in the country; – Minimisation of energy needs in agriculture through recycling of organic wastes; – Finding alternatives to diesel fuel through the use of non-edible oils and bio-solar fuels.

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– Development of producer gas technology based on wood and agricultural residues for electrification, lift irrigation and in automobiles; – Reducing transportation costs and increasing efficiency of fuels through briquetting and pyrolysis of agricultural and forestry residues; – Emphasis on microbial biomass as a source of energy; – Development of self-reliant energy systems in agro-industries through heat exchanges, steam engine, fluidized bed combustion, steam-turbine, gas turbine and other technological developments for power generation.

Energy Plantation for Power Generation and Other Local Needs Establishment of small power generation stations based on woody biomass is one of the main thrust areas under the biomass programme. During the Seventh Plan, it is proposed to cover about 1.5 million ha of sub-standard soil with quick growing species. Coupled with power generation units, this programme will help to generate power to the tune of 4500MW, of which 1560MW would be installed by the end of the Seventh Plan and the balance of the Eighth Plan. This includes 435MW of power from the existing plantations. The programme will also provide about 6 million tonnes of fuelwood per year for direct burning. Once the energy plantations are established, these would serve as a regular source of feedstock for power generation. This programme would help not only to ensure availability and reliability in power supply but also avoid transmission losses which is a chronic problem in thermal power generation plants. At the same time, it will help to provide biomass cover on denuded land and also provide and generate employm-nt in the planting and subsequent phases. Thus, this programme would meet several basic objectives of the planned production of power, preservation of the environment and generation of employment. These plantations will be undertaken particularly on the following types of substandard problem soils: Saline alkaline soils

Shifting and dunes

Water-logged soils

Laterite & lateritic soils

Hilly soils

Block soils

Ravine lands

Coastal alluvium

Biomass Based Gasifier Programme There are a variety of applications where this technology can have far reaching impact, i.e., thermal applications, diesel replacement in existing diesel engines, water pumping and power generation. Adequate supply of water is one of the major limitations to boost up food production and afforestation programmes. With fast growing tree species, irrigation can triple production to that obtained under rainfed conditions. The ground water potential in the country offers good scope for the installation of 120 lakh pumpsets. During the next two decades, the requirement of electrical energy will increase by about

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3 times the present value. The increase in the amount of diesel fuel required in pumping will also be about 65 more than the present level of consumption. This approach of biomass production and gasification will result in many benefits—waste land utilisation, energy supply for irrigation and employment potential. Establishment of Biomass Research Centres It has been estimated that demand of fuelwood in India would be about 225 million tonnes in 2000AD. No reliable data is available on the total fuelwood production and the likely deficit after a period of about 16 years. However, taking this shortfall of the order of 137 million tonnes, it is evident that nearly 34 million ha of the land would be required on the basis of about dour oven dry tonnes of wood per ha/year. Keeping in view the present land use pattern and per capita areas in deficit states, the only alternative under this situation lies in emphasising upon the concept of energy plantation. This programme concerns with the selection of species having high calorific value, fast growing, good cropping, high adaptability, use of establishment, nitrogen fixing ability with multiple uses particularly suitable as animal feed. Recognising the need for augmentation to strengthen the R&D efforts to generate research information on potential species in various agroclimatic zones so that these could be tested on specific location. The success of firewood plantation depends, however, on proper selection of site, optimisation of cultivation practices—see germination, nursery practices, maintenance, spacing and tree density. Much of the techniques currently used in agriculture will have to be employed in energy foresty if tree productivity is to be maximised. During the Seventh Plan, it is proposed to establish 12 biomass research centres in addition to 3 already functioning at NBRI Lucknow, MKU, Madhurai and Garhwal University, Srinagar. Solid Fuel Programme Briquetting of farm residues and forest wastes offers potential scope to provide a substitute for solid non renewable fuels like coal and renewable sources like wood to meet fuel shortages both in the domestic and industrial sectors. Therefore, several processes are available for briquetting wastes/ residues but no information is available on the comparative economic and energetics of these options. In order to make this proposition of commercial value, it is essential to investigate the effect of different types of binders, moisture content, pressure and temperature of competlètion on briquetting of residues as well as the energy requirements per unit output of briquetted fuels. Bio-Solar Fuel Programme Shortage of bio-solar fuels is one of the main limitations in large scale use for motive power. It has been estimated that the total requirement of alcohol by 1990 will be about 1610 million litres per annum but alcohol from molasses would hardly provide 950m litres, thus a gap of 650m litres. This calls for tapping of non-convetional sources of

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energy sugar/starch like cassava, sugarbeet, sweet sorghum palrah palm and date palm are potential sources of alcohol, but their competition as a source of food is one of the main limiting factors’ in making use of these crops as a source of energy. Intensive efforts on increasing their productivity can help to meet both the needs, consistent with creation of agro-industrial complexes and generation of employment potential in these areas. During the Seventh Plan, it is proposed to increase the production potential of energy rich crops, setting up pilot plant facilities for alcohol production, and utilisation of these fuels in small utility 2 stroke S.J. engine, multicylinder automobile engines, small utility multifuel C.I. engines, and for gas turbine applications. Petro-Crops In order to search for alternative liquid hydrocarbon materials of about the same aggreate chemistry as the current petroleum products, a collaborative project entitled “introduction, screening and cultivation of potential petrocrops and their conversion to petroleum hydrocarbons, was initiated jointly at NBRI, Dehradun. During the first phase a list of 186 species belonging to six laticiferous families, viz, Euphorobiaceae, Asclepiadaceae, Urticaces, Apocynnceae, Convolvulaceae and Sapotaceae was prepared. Wide distribution, sufficient latex content and selecting the species. The second phase of this project relates to techno-economics of cultivation of promising species, building up of Germplasm Bank of Latex bearing plants, development of agrotechniques for maximum biomass production of prospective plant species; standardisation of techniques for hydrogeneration/determination of composition of the products as well as their evaluation. The work of hydrocarbon plants is in a nascent stage and needs intensification from various aspects. Exploration and Survey on Availability of Biomass Despite the fact that a large number of institutions are working on energy from biomass in the country and significant developments have taken place for product development from wastes/residues; but no reliable data is available on quantitative basis. This calls for collection of information on the following aspects; estimates of their potential and actual availability cropwise/industrywise, seasonwise and spatial distribution, existing utilisation pattern technological developments for using surplus residues/byproducts and identification of opportunities for seeting up new projects. Future Plan up to 2000AD During the Seventh Plan, it is proposed to develop a multi-dimensional biomass programme convering all the five components, viz—availability, production conversion, utilisatisation and conservation particularly in the field of improved chulhas, energy plantations, biomass gasification solid fuel production and manufacture of alcohol from

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non-conventional energy crops. R&D efforts will be stepped up so as to provide scientific and technological basis to the promotional and developmental activities. The following are the main achievements expected at the end of the Seventh Five Year Plan: – Signficant awareness on the conservation of biomass through maximum and efficient utilisation of improved chulhas. – Management practices for the production of biomass and sub-standard soils in differnt agro-climatic zones. – Use of gasifiers based on wood and residues for stationary and mobile applications in agricultural and transportation sectors. – Establishment of decentralised energy generation systems in various agro-industries, viz, rice milling, sugar industry, oilseed processing industries, dairies, sawmills, etc. – Pilot plant production of alcohol from ligno-cellulosic materials and energy crops. – Commercial manufacture of solid fuel based on residues and forest biomass, with and without briquetting. – Biomass-based substitutes to diesel fuel and petroleum based lubricants. – Information on the availability of biomass-organic residues, aquatic biomass, forest biomass, energy trees and shrubs in different locations. – Pilot plant production of biological hydrogen. – Accelerating the pace of development in selected priority areas through foreign collaborative programmes. – Establishment of advanced centres for biomass energy studies. Thus by the year 1990, it is hoped that the stage will be set to make biomass programme—a peoples’ movement where all activities relating to production, conversion, utilisation and conservation of biomass will be taken up on decentralised basis to meet local needs in the domestic, agricultural, industry and transportation sectors to a significant extent. Acknowledgment The authors are thankful to Shri Maheshwar Dayal, Secretary, Dept of NonConventional Energy Sources for giving permission to publish this paper.

DEVELOPMENT OF BIOMASS IN MALAYSIA K.S.ONG Mech. Eng. Dept., University of Malaya Kuala Lumpur 22–11, Malaysia C.F.LAU Shell (M) Trading Sdn. Bhd. Kuala Lumpur, Malaysia Summary A biogas plant operating under local conditions was investigated. Performance characteristics such as gas production rate, pH level, carbon dioxide content and temperatures were obtained. Chicken droppings and palm oil effluent were used separately as raw material for the digesters. Batch as well as continuous slurry feed operations were employed. The results of these preliminary investigations are presented.

1. INTRODUCTION The development of biogas in Malaysia was initially slow and limited to a few interested individuals and research organisations with a few scattered digester plants installed throughout the country mainly for lighting and cooking in pig farms. Lately however, with the advent of the energy crisis and a public awareness towards agricultural waste pollution in the country attention was focussed on the treatment of palm oil sludge. The traditional practice of discharging waste effluent into nearby rivers and streams have resulted in the destruction of aquatic life. For the more ecology-minded mills effluent discharge was made into holding ponds prior to release into the rivers. In fact, these ponds were nothing more than providing an open-pit type of digester with the biogas thus generated being allowed to freely mix with the surrounding air and hence producing the familiar stench associated with such a system, The anaerobic digestion of palm oil sludge is presented in Quah (1). With the potential and ability to supply electricity to the National grid all eyes are now focussed on this future development, At the University of Malaya, studies were made (2, 3) to investigate the performance characteristics of a biogas plant operating under local conditions with a primary view to obtain the optimum operating conditions, Chicken droppings and palm oil effluent were used. In both the investigations, solar heated water was used to heat up the slurry in an attempt to improve the rate of production of the biogas.

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2. EXPERIMENTAL EQUIPMENT AND PROCEDURE The experimental set-up illustrated in Fig. 1 consisted basically of a digester, a gas receiver and a solar water heater. The digester was essentially two concentric circular cylinders forming an external water jacket and fitted with a manually-operated screwtype slurry feeder, a manually-operated multi-paddle blade-type agitator, valved outlets for gas discharge, scum discharge and slurry discharge, The gas receiver consisted of a closed end cylinder inverted over another water-filled cylinder. Counter weights attached to the inner cylinder allowed the pressure of the gas generated to be varied. Other important features included a gas trap and a safety valve at the top of the gas receiver. The solar water heater was of the conventional flat plate type operating under thermosyphon flow conditions to supply heated water at around 35°C to the water jacket. The following outlines the general procedure followed in the operation of the plant: (i) Fresh slurry was injected into the digester via the screw-feeder while digested slurry was discharged from the discharge pipe at the bottom. (ii) Biogas generated in the digester flowed from the top of the digester tank to the gas receiver tank via a plastic hose. The gas receiver tank rises as the volume of gas generated increased. The gas pressure was controlled using the counter weights. (iii) Gas from the gas receiver was discharged for testing via the gas trap through a plastic tube. The plant was operated for 2 years. In the first year, chicken droppings were used as raw material and palm oil effluent in the second year. Slight modifications were made to the plant during year 2 to improve handling aspects of the palm oil effluent, Results are shown in Fig, 2. 3. RESULTS WITH CHICKEN DROPPINGS AS RAW MATERIAL Fresh chicken droppings were mixed with water in the ratio of 1:1.25 by volume and introduced in batches into the digester via the slurry feeder until it overflowed from the scum discharge pipe. The scum discharge valve was then closed, the gas outlet valve opened and the slurry was agitated regularly. Total slurry content was 0.2m3 per batch, The gas production rate, carbon dioxide content of the gas, pH of slurry and temperature of slurry were measured over a 40 day observation period, Results showed that the daily gas production rate reached a maximum of 0.18m3 on the third day of digestion, Towards the eighth day, gas production rate was 0.10m3 with 43% carbon dioxide content, This gas was combustible. On the tenth day, gas was produced at a rate of 0.16m2. After this time, the gas production rate showed an overall decreasing trend with a few minor upswings down to about 0.015m3 after thirty-five days, The total volume of gas produced over 28 days was 3,14m3 which amounted to 93% of the volume expected from the 0.085m3 of chicken droppings used. However, the incombustible gas produced during the first seven days was 25% of the total volume of gas produced. Hence the total volume of usable gas produced was about 0.065m3, The carbon dioxide content of the gas rose to a maximum level of 63% on the fifth day. The carbon dioxide content began to decrease after six days until it was at about

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25% after about thirty days, The pH level dropped to a minimum value of 5.6 from 7 after about seven days. After this, it began to increase to a near constant value of between 7, 5 to 8 after thirty days. It was observed that carbon dioxide content increased as pH level decreased. The slurry and water jacket temperatures could not be controlled and they were observed to vary by ±3°C dependent upon ambient conditions. It was not possible to conclude qualitatively the effects of temperature to gas production rates. However, from preliminary studies, it was found that temperatures of 35°C were more favourable for gas production than say 30°C. 4. RESULTS WITH PALM OIL EFFLUENT AS RAW MATERIAL Batch and continuous digestions of palm oil effluent were tested over a total period of months, Anaerobic fermentation of organic fibres in palm oil effluent is quite complex and it would be beyond the scope of the

FIG. I ILLUSTRATION OF EXPERIMENTAL BIO-GAS PLANT

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FIG. 2 BIO-GAS PLANT PERFORMANCE UTILISING BATCH DIGESTION OF CHICKEN DROPPINGS AND PALM OIL EFFLUENT SEPERATELY present study to make a thorough study of the biodegradation process. Further, as up-todate results are available only typical results are presented here. For the batch digestion, maximum gas production rate of 0.15m3 was reached after about 14 days. The carbon dioxide content decreased to about 20% while the pH level rose to about 7.5. For continuous digestion, a regular feed of 18ℓ every 3 days was introduced into the digester. The results showed that fresh effluent feed resulted in higher gas production rate. The pH level was very nearly constant at about 7.8 for fresh effluent

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and 7.3 for retained effluent, The average calorific value of the gas was found to be about 2.31×104kJ/m3 and the gas combustibility was good in both cases. 5. GENERAL OVERALL VIEW FOR DEVELOPMENT From these preliminary results it is difficult to say whether batch or continuous digestion method is preferred. Much would also depend upon the practicality of operating the plant. The main criteria being to educate the user to control the mixture composition and regulation of pH and temperature levels. More work would have to be done by biochemists to identify and to determine the optimum operating characteristics for maximum gas production. Once these are known, Engineers can then design the plant to suit these conditions. Agricultural extension workers could then dessiminate the information and to assist in setting up actual plants in the rural areas. Financiers would have to be brought into the scene to finance the programme as rural farmers are not able to afford them no matter how low the capital costs are. In short, a general strategy would have to be formulated by the local Government or an International Agency in order to promote the use of biomass as an alternative energy resource. 6. CONCLUSIONS The preliminary results obtained provided useful data for the design and planning of future biogas plants using chicken droppings or palm oil effluent in Malaysia. Mixture composition, pH level and digester temperatures are important controlling factors. Further work should be performed to study the fermentation processes for optimum plant performances. REFERENCES (1) QUAH, S.K. and GILLIES, D. (1981). Practical experience in the production and uses of Biogas. Workshop on Palm Oil By-Product Utilization, PORIM-MOPGC, Kuala Lumpur. (2) NG, K.C. and WONG, K.W. (1979). Biogas plant design, construction and test. Thesis Report, Mechanical Engineering Department, University of Malaya, Kuala Lumpur. (3) CHAN, J.H. and GOH, P.S. (1980). Biogas plant for palm oil effluent. Thesis Report, Mechanical Engineering Department, University of Malaya, Kuala Lumpur.

THE BIOMASS ROLE IN THE BRAZILIAN ENERGY BALANCE I.GOCHNARG, BsCHE, MsCHE G.L.GROSZMANN, BsCE, MBA INSTITUTO DE PESQUISAS TECNOLÓGICAS IPT—CIDADE UNIVERSITÁRIA 05508—SÃO PAULO—SP BRAZIL This paper characterizes the Brazilian energy problem, describes the strategy conceived to solve it and the role played by biomass energy car riers within this strategical framework. Position data on the Brazilian ethanol, firewood/charcoal and vegeta ble oils programs is furnished. 1. THE BRAZILIAN ENERGY PROBLEM Brazil with a population of 130.000.000 inhabitants and an area of 8.512.000Km2 was among the ten major economies of the western world in 1983, with a GNP estimated around 220 billion US$. Historically the Brazilian economy has been penalyzed by inflation ra tes around 25% a.a. (5) but the 1973 oil crises and the 1979 oil shock, combined with the higher interest rates of the early 80’s, besides trig gering an ever increasing inflation rate (211% a.a. in 1983) (4) have con tributed for the Brazilian balance of payments chronic deficit and conse quently for the country increasing indebtedness. Being one of the main causes of the Brazilian ever growing indebteness the petroleum account was recognized by the Brazilian government, in 1979, as being one of the most important tools to loosen the foreign constraints affecting the country’s economy. Within this framework the Brazilian energy problem was characterized as being a typical imports substitution problem. Typical but prior once that the expediture with energy importation was the one that offered the greatest potential for substitution on a medium term basis and conse quently could play a major role in the relieve of Brazil’s international debt burden. 2. THE BRAZILIAN ENERGY STRATEGY The Brazilian energy strategy aims to reduce the country’s petroleum account by appropriate implementation of governmental programs in the following areas:

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– energy conservation – national oil production – petroleum substitution The results of the implementation of this strategy may be seen in Ta ble I. that reflects the evolution of the Brazilian energy demand by car rier as well as in Table II. that presents the evolution of the Brazilian net expenses (CIF) with petroleum importation. 3. THE BIOMASS ROLE As per the Brazilian Ministry of Mines and Energy data,almost 31% of the Brazilian energy demand in 1983 were met by biomass derived fuels. Their contribution to the national energy balance in 1983 reached almost 41 million toe; figure that represents 88% of the Brazilian consumption of petroleum derivates in that year. Table III. sinthesizes the Brazilian biomass program rationale. A brief description of the stage of development and contribution of the main biomass energy carriers is furnished below. 3.1 ETHANOL On November 1975 the Brazilian government launched the PROALCOOL Pro gram (National Alcohol Program). Counting on a strong technical and eco nomic support this program is already in its third stage with a produc tion goal of 14.3 billion liters per year by 1987. Until August 1984 the Executive Commission of the Brazilian Alcohol Program (CENAL) has approved 541 alcohol plant projects; 236 of these units are annexed plants and 305 are autonomous ones. Almost 100% of both kinds of plants run solely on sugarcane. (3) The production capacity already approved by CENAL reaches 11.5 bil lion liters per year and the real out-put for the 84/85 crop is estimated at 9,4 billion liters. (3) Ethanol is being consumed in three basic ways: – as gasoline extender (anhydrous alcohol) – as gasoline substitute (hydrated alcohol) – as chemical feedstock Nowadays Brazil runs a fleet of almost 8 million vehicles on gasohol (78% gasoline+22% ethanol) and almost 1.800.000 vehicles on straight ethanol. 600.000 alcohol powered vehicles are expected to be added to the pure ethanol fleet in 1985. Table IV. presents data on the evolution of the Brazilian ethanol and gasoline consumption. Besides its use as fuel ethanol is also being used to displace petro leum as chemical feedstock. In 1983 four hundred million liters of etha nol were consumed by the alcoholchemical industry. (1) Two complementary energy carriers are being obtained as by-products of the ethanol program: bagasse and methane.

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The amount of bagasse produced in 1983 was equivalent to 9,367.103 toe. 20% of this total was used for non-energy purposes, 44% was consumed by the ethanol producing system and 36% was emploied as fuel oil substi tute by the industry. (1) For a long time methane could be obtained by stillage biodigestion but just now this route became economically feasible with a technological breakthrough on the biodigestion process developed by IPT. With a residence time of 18 hours, instead of the usual 20 to 30 days, IPT process allows the implantation of biodigestion systems that maKe economic sense. For instance, a system for a 120.000l/d ethanol plant, treating 1,500m3 of stillage per day, allowing the displacement of 1.930m3 of diesel per crop, would require an investment of 1,400,000 US$ that covers the biodigestion system (450,000 US$) and the methane purifi cation, compression and storage facilities (950,000 US$). 3.2 FIREWOOD AND CHARCOAL Firewood and charcoal play an important role in the Brazilian energy balance. As presented in Table I their contribution for the energy supply in 1983 reached almost 24,200.103 toe. This figure is almost 6.5 times the ethanol share in the 1983 Brazilian energy balance. Reforestation is an important activity for the continous contribution of these energy carriers. In this sector Brazil occupies the 5th place in the international ranking of reforestation activities (more than 400.000 ha were reforested in 1980) and Brazilian private companies are among the ones with best Know-how on short rotation sivicultural practices. 3.3 VEGETABLE OILS Brazil has been studying the use of vegetable oils in Diesel engines since 1978. A huge research and experimentation program concluded in 1984 (OLVEG), coordinated by the Brazilian Ministry of Industry and Trade, has demostrated the technical feasibility of using transestherified vegetable oils as Diesel extender or substitute in cargo and public transportation systems. The main sources of oil considered were: soybean, sunflower, palm and macauba. Although technically feasible this route is not economically sound for the time being. It may be implemented on a short term notice in case of severe supply crisis. 4. FINAL REMARK With a contribution of almost 41 millions toe/year, no one can deny the important role that biomass energy is playing in the Brazilian econo mic struggle. Although Brazil’s privilegsd endowment for energy from biomass pro grams much of the Brazilian experience may be useful/suitable for other developing countries.

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REFERENCES (1)—MME—Balanço Energético Nacional—1984 (2)—Eduardo Celestino Rodrigues—Unpublished Paper (3)—MIC—CENAL: Relatório JUL/AGO/84 (4)—FGV: Conjuntura Econômica (5)—Y.NaKano: Inflação e Recessão

TABLE I—BRAZILIAN ENERGY DEMAND EVOLUTION PER CARRIER (103 toe) (1) 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 Natural Gas Coal Firewood Diesel Fuel Oil Gasoline LPG Naphta Kerosene Gas Coke Electricity Charcoal Ethanol Bagasse Others Non-Energy Products Petroleum Derivates and Natural Gas Par ticipation Others SubTotal TOTAL

117 348 378 61 105 124 19467 19824 20182 7937 8800 9822 10338 11749 12475 10370 10745 10978 1764 1879 1965 909 1027 997 1526 1642 1724 463 465 552 1257 1283 1571 15928 17871 19772 1941 2418 2897 407 370 353 3587 3557 3208 673 1017 1033 4176 4386 4274

435 91 21289 11375 14336 10860 2155 1061 1901 680 1835 22489 2613 320 3654 1220 4749

879 170 20882 12231 14544 10049 2269 1191 1966 775 2426 25217 2572 731 4962 1335 5262

715 208 20670 13329 15823 10259 2511 1600 2024 820 2623 28176 2570 1342 5208 1731 5425

783 306 20463 14433 16556 10028 2764 1900 2288 891 2999 31589 2988 1860 5657 1878 6253

923 508 20367 15447 16243 8684 3005 1950 2153 923 3157 35259 3555 2273 6233 1785 5777

822 846 20458 15053 12817 8264 3160 2403 2310 839 2603 35966 3257 1990 6741 1535 5722

1174 1586 1279 1453 20404 20257 15512 15187 10262 9770 7875 6734 3517 3642 2870 3577 2327 2251 935 1080 2801 3308 38067 41069 3558 3956 2809 3828 7614 9367 1693 2059 5587 4817

36620 39943 42273 46388 47215 51557 54926 53986 49935 49542 46855

44301 47541 50032 54675 60246 63477 68703 74256 74891 79942 87133 80921 87484 92305 101063 107461 115034 123629 128242 124826 129484 133988

TABLE II—EVOLUTION OF THE BRAZILIAN PETROLEUN NET ACCOUNT (2) YEAR

1972 1974

NET NETPETROLEUN EXPENSES IMPORTATION IF 106 US$ (1000 boe/day] 514 668

538 3,137

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1979 1980 1981 1982 1983 1984

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1004 872 844 737 622 467

6,639 9,811 10,335 9,301 7,246 5,400

TABLE III—BRAZIL’S BIOMASS PROGRAM RATIONALE RAW-MATERIAL

CARRIERS

DISPLACES

ETHANOL GASOLINE SUGAR-CANE BAGASSE FUEL OIL METHANE LPG/DIESEL FIREWOOD FUEL OIL CHARCOAL FUEL OIL TAR DISEL/FUEL OIL WOOD WOOD GASES LPG/DISEL/FUEL OIL ETHANOL GASOLINE METHANOL DIESEL PALM TREE RAPESEED SUNFLOWER VEGETABLE OILS DISEL PELLETS FUEL OIL RESIDUES CHARCOAL FUEL OIL METHANE LPG/DIESEL

TABLE IV—EVOLUTION OF THE BRAZILIAN ETHANOL AND GASOLINE CONSUMPTION (2) CONSUMPTION (1061) OIL % As YEAR DISPLACEMENT ETHANOL EXTEDER GASOLINE 1000 bep/day ANHYDROUS HYDRATED 1979 1980

13.426 11.438

2.217 2.253

18 429

14,2 16,5

33,5 39,2

1981

10.943

1.146

1982

10.439

2.017

1.392

9,5

34,6

1.674

16,2

51,2

1983

8.694

2.174

2.940

20,0

69,4

1984

7.734

2.061

4.391

21,0

87,0

SMALL STEAM SYSTEMS FOR THE THIRD WORLD D.Hislop & S.Joseph, Intermediate Technology Development Group SUMMARY. Rural development in the Third World urgently requires small power systems operating on renewable resources. Little impact has as yet resulted from work in solar, wind, producer gas, stirling engines, biogas or other power technologies. The paper describes recent developments in small steam plant, offers initial operating cost comparisons with other renewable energy technologies, and indicates how combined heat and power systems can be used in gur production in Bangladesh.

1. BACKGROUND. Rural development in the Third World urgently requires small power systems, using renewable energy resources, to substitute -for expensive and unreliable supplies of diesel fuel and grid electricity for irrigation, agricultural processing and similar uses. Considerable resources have been devoted to the development of technologies to supply this power, including micro—hydro, wind, solar, producer gas, biogas and biomassderived liquid fuels. Few have had a significant impact. Micro—hydro is appropriate only for a strictly limited range of locations. Solar and wind technologies are beginning to be adopted on a limited scale for domestic and animal water supplies, battery charging and similar tasks, but can rarely be used for irrigation (except for high value crops) or to provide power for rural industries. Of the biomass fuelled technologies, producer gas is un-proven below shaft outputs of about 20–25kW, even when using charcoal, the fuel for which operation is most trouble—free (1). On wood and agricultural residues, and especially below 10kW shaft output, the scope for producer gas at present appears, at best, confined to areas where there are ample supplies of high grade charcoal and of low cost diesel engines. New forms of stirling engine are being developed: if technically and economically viable, these could play an important role. However, their future is still very uncertain. Biogas technologies have had limited success except in China, and to a lesser extent in India and Nepal: while the scope for biogas in domestic and institutional cooking is considerable, in power production it is limited. ITDG believes that there is considerable potential for small steam power, and has, in conjunction with the Thames Steam Launch Company, undertaken the development of suitable systems, based on early, proven designs. Funds have been provided by the Overseas Development Adminstration and the Hilden Charitable Trust. The aim has been to develop systems of 0.5kW to 15kW shaft output, and where possible to use combined

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heat and power systems to make maximum use of the available fuels. Marine end uses have considerable potential. The plant is to be safe, simple, robust and tolerant of abuse; easily operated and maintained; low cost and capable of manufacture in as many countries as possible; and capable of operating on a wide range of biomass fuels. Where appropriate, ITDG also intends to encourage the use of steam systems in conjunction with and as a stimulus to wood or other biomass fuel production projects, especially where steam plant can provide the power for irrigated fuel production. 2. THE SYSTEM. Initially, ITDG and Thames Steam Launch have developed a 5kW shaft output system which is easily scaled down to 2.5kW or 0.5kW, or up to 10kW, with up to 400kW of heat. The main components of the system are as follows. Furnace. Furnaces suitable for wood, straw and coconut shells have been designed, built and tested with Thames Steam Launch Company boilers (see below). One range, based on shell furnaces, is made of horizontal sections built or cast from simple refactory materials. Fuel to steam efficiencies have been obtained of up to 65% on wood, 60%. on coconut shells and 50% on straw. A second range—larger, easier to operate and less sensitive to fuel size and feed rates—provides 50% efficiency using wood. Both efficiency figures will increase significantly with the use of feed water heaters. Furnaces for rice husk and other particulate fuels are being developed. Boiler. A mono—tube boiler was initially preferred. However, problems of cost and control of steam conditions led to the choice of a proprietary water—tube design by the Thames Steam Launch Company (TSL) of Chiswick, UK. Designed for amateur boat enthusiasts, it is extremely simple, robust and safe, consisting of steel top and bottom drums, joined by copper tubes expanded into the drums, the end plates being held in position with stay bolts. The absence of welding in the joints between tanks and tubes much reduces the safety problems associated with poor welding, and eliminates them if seamless tube is used for the drums. If the locked safety valve is tampered with and pressure builds up, or if the water level becomes too low, the expanded joints will act in a manner similar to that of fusible plugs, the water leaking into the combustion zone to dowse the fire. Cleaning access is simply obtained by removing the stay bolts and end plates. The boiler has been used on untreated river water, and any sludge is usually deposited in the bottom tank, from where it can easily be removed. It has been cleared for insurance purposes by National Vulcan, an internationally recognised inspection agency, for pressures of 8.7 or 14.5 atmospheres, and it conforms to British Boiler Standards. More than 40 units are in operation, mainly in the UK, but also in Switzerland, Germany, the US, and Australia. Other small boilers are under development to match specific end— uses and materials availability. Engine. TSL has developed a very low cost, low speed (300–600rpm), twin cylinder oscillating engine. Valves are not needed, as the entrance and exit of the steam is through ports in the engine and cylinder blocks, and is controlled by the oscillation of the cylinder blocks. The engine, based on Victorian designs, has been modernised mainly by the use

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of high grade cast iron for the engine and cylinder blocks, providing very low friction sliding faces at the junction of the blocks. Self—aligning bearings greatly simplify manufacture. It has very few moving parts, and is extremely robust. Minimal lubrication is needed: the bearings can be sealed for life, and the sliding cast iron faces need little lubrication, especially when the engine is run on wet steam. There is no steam cut-off, and the expected thermal eff iciency was much lower than that of a conventional engine with cut-off. However, at these small sizes, the difference in efficiency is less significant, especially as the mechanical efficiency of the oscillator is very high. Early engine tests at the South Bank Polytechnic show efficiencies of over 5.2% (shaft output to steam enthalpy) at an output of 5.8kW, at 5.4 atmospheres, using estimated 94% dry steam. Eff iciencies of over 6% are expected using super-heated steam and optimised porting. A single cylinder version is now in operation, and future developments include an oscillator with steam cut—off to give higher efficiency, a conventional piston—valved column engine, and a high speed engine for electricity generation. Control. A conventional centrifugal governor can be used when engine speed is the only control required. For electricity generation, an electronic controller with load dumping will be used. ITDG has access to a well—proven model developed for micro— hydro by Evans Engineering/GP Electronics of the UK: this can be adapted to provide electro-mechanical steam control when necessary. 3. COSTS AND ECONOMICS. UK ex—factory cost of a 5kW shaft output system is US$ 3750–6000 for one off, depending on furnace type, ancillaries, etc. At the higher levels of production expected within a short period, costs will be very much lower. Detailed cost estimates have been undertaken in Bangladesh, where the one off production cost of a 5kW shaft output system is expected to be less than US$ 750. Costs for India and Indonesia have been estimated at US$ 800–1200. In 1983 a costing study for 5kW shaft power plant was undertaken (2) comparing the operational costs of steam, grid electricity, diesel, producer gas (both new and retro-fit to diesel), wind and solar. Under the given assumptions steam provides the lowest annual operating costs for many locations. Only electricity in countries where its price is low shows a significant cost advantage over steam: wood fuelled, retro-fitted producer gas units have the same costs, and wind shows a small cost advantage in some of the countries covered. In all other cases, steam appeared to be the lowest cost technology. The validity of these comparisons is limited by the lack and poor quality of field data. In the case of small diesel plant, surprisingly little is known of real field operating costs. Manufacturers of small diesel plant often quote efficiency figures of more than 30%, but there are increasing reports that in rural Africa and Asia, efficiencies are often little more than half this. The lack of efficiency data for small diesel engines puts important contraints on comparisons between steam systems and producer gas systems based on diesel engines. Comparisons on the basis of diesel units’ rated output are suspect, as in rural areas many diesel engines are over-sized, while the conversion of a diesel engine to a producer gas plant results in a variable degree of down-rating.

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The cost of fuel for biomass powered plant is also an area of considerable complexity. Market prices of traded biomass fuels vary between locations and seasons: some biomass fuels, especially agricultural residues, are often not at present traded within the cash economy. In other instances, fuel for biomass plant will be supplied on a communal basis, or grown by the owner, In all these cases, estimates of the cost of fuel to the plant are likely to be extremely unreliable until considerable experience of operations in the field has been obtained. The comparisons were based on market wood and charcoal prices, and on ready diesel availability at normal market prices. In many areas diesel or electricity is not readily available, or, with diesel, not at these prices, while wood produced specifically for power plant may be available at lower costs than the market price. Here, the case for steam (and to a certain extent producer gas) relative to diesel is even more favourable. Similarly, in some areas residues will be available at low or even zero costs, which cannot be used for producer gas plant, thus improving the case for steam relative to both diesel and producer gas. 4. STEAM FOR GUR MANUFACTURE IN BANGLADESH. The case for steam is greatly enhanced when it can be used in combined heat/power mode. Field trials are due to take place in Bangladesh in October 1985, where steam will provide heat and power for the manufacture of gur, an unrefined sugar product of which about 360,000 tonnes is produced per year. Small farmers hire bullock-powered cane crushers to extract cane juice, and the waste cane (bagasse) is dried and then used as a fuel to evaporate the water out of the juice to produce gur. Pressure on land has reduced fodder supplies, so that the cost of owning or hiring bullocks has increased, and their supply decreased, to the extent that small farmers are now often not able to process cane (3). This is particularly serious as the Government moves towards a policy of upgrading cane growing to provide higher yields. Steam plant provides a low cost answer to this problem. A TSL boiler will be fitted to the existing bagasse furnace. Steam raised in the boiler will power an engine to drive the crusher; the exhaust steam will pass through a calandria and undertake two thirds of the required juice boiling, while being condensed back into boiler feed water. The partly boiled juice passes into the boiling pan on the furnace, to have the final evaporation in the traditional manner. Project appraisal shows that steam plant will provide the same returns to the farmer as bullocks, and somewhat higher returns than diesel, the only alternative available in most rural areas. For the plant owner, steam shows much greater advantages: for a crushing season of three months the costs (capital, labour, fuel/fodder and maintenance) of the steam plant are approximately 25% below those of bullock and diesel plant. For this reason the project is designed to provide cooperative ownership of the plant by farmers or landless workers. Steam has an additional advantage: under present practice some bagasse is surplus to the requirements of Juice evaporation. It is a valuable fuel for domestic or industrial use, as in most of Bangladesh there is a growing shortage of biomass fuels. Using steam for most of the juice evaporation is more fuel efficient that the traditional methods, and is likely to provide a considerable increase in the bagasse

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surplus. A number of similar applications, including rice and coconut drying and processing, are being explored. 5. PRESENT STATUS. Furnace development for wood, straw, coconut shells and similar fuels has been completed: development work on furnaces for rice husk and other particulate fuels is continuing. The present boiler is a tested and commercially available unit: future developments may include the use of steel tubes. The 5kW engine has completed over 1500 hours of boat trials, and is now undergoing laboratory trials and optimisation at the Polytechnic of the South Bank in London. Trials of the complete system are now taking place in the UK, and long term life trials will begin in the second quarter of 1985. An engine and boiler are being shipped to Papua New Guinea for trials in saw-milling in April 1985. REFERENCES. (1) Coovattanachai, N. Producer Gas Prospects in Developing Countries. BioEnergy in Developing Countries, (Special Seminar at BioEnergy-84 World Congress), Swedish International Development Authority, June 1984. (2) Hislop, D.W. Design and Development of a Multi-Fuel Furnace for a 2–5kW Steam Plant: Part One—Costing Study. Intermediate Technology Development Group for the Overseas Development Administration. April 1983. (3) Hislop, D.W. Upgrading Gur Production in the Non-mill Zone, Cane Producing Areas of Bangladesh. Interim Report, ITDG, Rugby, March 1984.

BIOMASS ENERGY AND RURAL DEVELOPMENT IN COASTAL ECUADOR M.McKenzie Hedger Department of Social and Economic Studies Imperial College London SW7 2PG UK Summary Some new and improved techniques to produce energy from biomass have been considered to have potential for rural development. An assessment was made to see which of these were suitable for introduction in coastal Ecuador. The study was undertaken as a locally-based case study in two dry and humid tropical areas. It was found that the role of biomass energy was limited, being largely confined to the use of wood and charcoal for cooking. Moreover, households are changing to gas and kerosene, particularly in urban areas. However, despite its seemingly residual role, biomass energy is still a vital part of the daily life strategies of the poor. Introduction of technical changes was found to be inhibited by the social and economic structure. In addition the state policy framework serves to undermine the supply of biomass energy in a number of ways. It is concluded that biomass energy policy interventions are required and dependent on changes at national level. These policy interventions need to be specifically related to users and producers as part of integrated approaches to rural poverty.

1. INTRODUCTION Some improved techniques to produce energy from biomass are regarded as having potential for employment in rural development (1). An assessment was made as to which techniques were suitable for introduction in coastal Ecuador against a background of existing usage of biomass energy. Particular attention was paid to: improvements in wood supply, from existing forests by management, the establishment of community woodlots and the introduction of fast growing tree species; improved wood stoves; charcoal production and supply improvements. A central aim of the study was to identify the constraints in the social and economic context and political framework which inhibit the introduction of technical changes. This approach has particular relevance in view of the lack of a national biomass energy policy and the absence of a coherent programme of action and support for biomass energy technical innovations. The project was established as a locally-based case study. Two study areas were selected in Los Rios and Manabi provinces in Ecuador, in moist forest and thorn woodland/dry forest ecological life zones respectively (which span the range of

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conditions found in coastal Ecuador) (2). An examination was made of: the existing role, use and users, producers and distributors of biomass energy. It can be noted that this investigation principally related to the use of wood and charcoal for cooking. The investigation was undertaken in selected urban and rural communities and in different crop systems. In addition, an analysis was undertaken of agricultural, forestry and energy policy as it affected biomass energy supply. 2. ROLE AND SIGNIFICANCE OF BIOMASS ENERGY It is possible to identify the following main features of significance which need to be considered in relation to existing and future use of biomass energy: a. Limited role of biomass energy In the early stages of the study it was found that the limited industrial and agro-industrial processing sectors of the study areas inhibited the introduction of new biomass fuels and the small-scale decentralised industrial plant for which they have been considered particularly suitable. The economic structure of Ecuador has led to an industrial pattern which is concentrated in the metropolitan centres of Quito and Guayaquil. Moreover the subsidised prices of fossil fuels has meant that their use has pene trated through the economy, including certain crop production systems. b. Variations in the use of biomass energy It was found that considerable variations existed in biomass energy patterns of use for cooking. The proportion of households which used wood ranged from 12% to 93% in different communities. For charcoal the range was 0% to 63%. Variations were found not only between urban and rural areas but within urban and rural areas. Various factors were examined to see which affected use and it was found that the situation was complex. Use and non-use of biomass energy was related to place of residence, socio-economic group and the exercise of personal choice. The residential factor was closely associated with supply problems. There are supply problems not only of wood in urban and some rural locations, but charcoal and also gas in some rural locations. Future biomass energy use will clearly be related to changes in residential patterns, demographic structure and in come, in addition to wood and charcoal production. c. Inefficient use of biomass energy On average, wood-using households used 11.4GJ person/year compared to 1.7GJ person/year for gas. Whilst it might seem that there is considerable potential for improvements in wood stove efficiency, this requires careful examination as those still using wood or charcoal are generally unable or unwilling to invest in a stove for kerosene or gas. An improved wood stove which involved expenditure and an unfamiliar technology could not be expected to be readily acceptable.

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d. Changing role of biomass energy It has been indicated that communities vary in their patterns of usage of biomass energy. These variations result from changes that many households, principally in urban locations, had made in fuel use, in the previous 5 years. The changes are mainly from biomass energy to fossil fuels, although biomass energy may continue to be used as a supplement. Households have changed to gas or kerosene because they are more convenient fuels and/or because of wood supply difficulties. e. Significance of biomass energy Despite the changes noted above, for the majority of households in rural areas, and a significant minority in urban areas, change to fossil fuels is not necessarily possible when biomass supply problems are faced. The households which comprise this majority group in rural areas are the small landowners, agricultural labourers and unskilled workers. It can be noted that in the Manabi study area over 80% of these household groups are still exclusively dependent on the use of wood and/or charcoal. Households in all income groups expressed positive reasons for using wood and charcoal which relate to their qualities for food preparation and the ease with which they can be used on a simple home constructed stove. The use of biomass energy by the rural poor justifies public policy intervention strategies which should be adopted. 3. EXISTING SUPPLY OF BIOMASS ENERGY When wood and charcoal supply systems are examined it is clear that whilst there are increasing difficulties, there is some potential for improvements. The real problem arises from the inadequacy of the existing policy framework to develop supply potential to provide for requirements. a. Supply problems (i) Fuelwood supply In coastal Ecuador fuelwood supply problems are recent in origin with the acceleration of colonisation in the past 25 years and the conversion of forest areas to agriculture. Supply problems are now occurring principally because of the agricultural development supported by national policy des-export crop productivity.igned to increase food and (ii) Charcoal supply Wood for charcoal production in both study areas derives partly from other areas and is often a residual product when timber is extracted on conversion to agriculture. A large part of this forest resource is wasted and there are increasing timber supply problems as the remaining forest areas of the Guayas basin are converted to agriculture. (iii) Charcoal production

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Charcoal production takes place both at sawmills and in rural areas. In both cases simple earth kiln production is involved with low levels of efficiency. Whilst charcoal production at sawmills is semi-permanent and offers some scope for production improvements, the structure of the industry militates against such changes since charcoal makers possess no capital and the sawmill owners are preoccupied with more profitable investments. (iv) Environmental problems In both study areas, the substitution of trees by seasonal crops is already causing soil erosion. b. Potential (i) Forest resource Considerable opportunity is provided by the forest resource, both in those areas where stands of primary forest are extant and in the residual secondary growth where generated. The species diversity has not yet been fully defined, recorded or classified. In particular, no attention has been paid to native fuelwood producing trees. During the study it was found that many of the native legumes were fast growing and produced good fuelwood, notably several species of Inga and these deserve the attention which has hitherto been concentrated on exotics. (ii) Local knowledge Considerable knowledge is held by wood users and charcoal makers about the varying qualities of trees for fuelwood and charcoal production. (iii) Agro-forestry systems Due both to the comparatively recent origins of coastal agriculture and to the characteristics of many of the small and medium farming operations, many shade, fruit, timber, fodder and wood trees are found within cropping systems. These systems are virtually undocumented, most research being concentrated on separate crops. In particular, production of wood from shade trees of perennial tree crops was found to be vital and viable. However, shade is often regarded negatively from the viewpoint of agricultural production. c. Inadequacies of present policy framework There is no formal biomass energy policy and it is clear that a number of state policies actually undermine the supply and production of biomass energy. (i) The subsidisation of fuel prices inhibits the development of new biomass fuels as well as more efficient production and distribution of existing fuels. (ii) Colossal investments are made in mega-projects in conventional energy, such as the expansion of refining capacity for derivatives, and in prestigious hydro-electric projects. This strategy diverts attention and resources away from non-commercial energy sources such as wood and charcoal.

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(iii) Rural electrification is effectively the rural energy policy but is costly and cannot be extended through all areas. Even when supplies exist, many households cannot afford to connect. (iv) Apart from a small number of special projects, the development of agriculture is largely the limit of state intervention in rural development. Intervention is focussed on productivity increases, supported by technical advice, to medium and large farmers on a crop by crop basis. (v) Through agrarian reform and colonisation legislation the state has allocated or sold most of the state lands. Cooperative formation has been a tactical way of obtaining land and most have disintegrated without support afterwards. There is virtually no communal land or tradition of com-raunal working in the coastal zone which could be used to resolve biomass energy problems. (vi) Furthermore, during the colonisation process forestry has not been regarded as a viable operation, so that much of the forest resource has been rapidly removed to help establish title. (vii) Forestry policy is now comprehensive with many strongly committed officials: the problem is that the Directorate is under-resourced and policy is not implemented. 4. DISCUSSION AND CONCLUSIONS It is possible to identify a number of wood and charcoal supply improvements which have potential for introduction (3). However, it is evident that implementation of such improvements is likely to be ineffective in the absence of changes in the policy framework. Moreover, the scope for the introduction of changes such as new biomass fuels and small-scale, biomass-fuelled industrial plant was considered to be limited at the outset of the study, due to basic structural features (low fossil fuel prices and the concentrated industrial and processing structure). It has been indicated that whilst the state is formally little involved in biomass energy policy, indirectly its actions are critical. Thus the study, which started at local level, has identified that nationally and centrally originated changes are necessary. It is possible to explore the implications for institutional change within the Ecuadorean context, tentatively and pragmatically. Unless both latent and manifest impacts of policy are acknowledged it will not be possible to evolve an integrated approach. At present biomass energy is a rural energy problem with origins and solutions outside rural energy policy. It has been suggested that the existence of fuel markets in the domestic sector will stimulate biomass energy supply improvements and that this should be encouraged by the subsidisation of fossil fuels (4). However, the Ecuadorean experience suggests that this “commercialisation” strategy in itself is not an effective way of generating change and stimulating biomass supply and efficiency improvements. For many years gas and kerosene prices have been subsidised but biomass energy still has a critical and not a marginal role. Many cannot afford gas and kerosene stoves. Small brick-makers and bakers who use wood for fuel, use it in rudimentary ways and inefficiently but they use wood as no complicated and expensive machinery is involved. Private investments in biomass supply and conversion for energy are unprofitable. Meanwhile, state resources

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are focussed on maintaining fossil fuel supply systems involving imports of fuels and technology and no significant effort is invested in biomass energy supply despite increasing problems. Concerted intervention by the state on the forest resource is increasingly becoming necessary for environmental reasons. The situation is complicated in much of coastal Ecuador by the absence of state forests or communal land which could be used as the basis of supply strategies. There is a need to work through the agricultural system. In considering forms in which this intervention could take the practice of rural development requires examination. In theory, the concept can provide a framework for the reconciliation of conflicting demands on rural resources at local level and is thus sensitive to differing conditions and requirements, essential for biomass energy problems. Hitherto, however, the provision of electricity supply to a rural development project has been the beginning and end of the relationship of rural development and rural energy policy. The use of biomass energy with the hard, unhealthy work it involves, raises a basic dilemma for rural development policy. Biomass energy use is part of the rural poverty and misery that rural development attempts to replace, with improved living conditions such as are represented by the use of kerosene and gas. However, conventional approaches to rural development have not provided incomes to support the use of fossil fuels and buy the stoves necessary for their use. If no action is taken it is clear that the rural poor will lose out most as they are the main users of biomass energy. Biomass energy is thus a valid concern in rural development and can only be tackled in the context of “integrated rural poverty” (5). Change is required, perhaps facilitated by creating an extension service farmer-orientated to provide the focus for the development and support of multi-cropping and agro-forestry systems which can accommodate food and fuel production. REFERENCES (1) HALL, D.O., BARNARD, G.W. and MOSS, P.A. (1982) Biomass for Energy in the Developing Countries, pp. 115–126. Oxford: Pergamon Press. (2) HOLDRIDGE, L.R. et al. (1971) Forest Environments in Tropical Life Zones. Oxford: Pergamon Press. (3) HEDGER, M. (1984) The Potential of Energy from Biomass for Rural Development in Ecuador. Unpublished Report to the Overseas Development Administration. (4) FOLEY, G. (1982) Rural Energy Planning in Developing Countries: A New Framework for Analysis. Lecture at Beijar Institute, Sweden, December 1981. (5) CHAMBERS, R. (1983) Rural Development: Putting the Last First, Chapter 5, pp. 103–139. London: Longman

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ACKNOWLEDGEMENTS I am extremely grateful to my supervisors, Dorothy Griffiths and Leo Pyle for their continuous help and advice during the course of the research. This paper draws on research which was supported by the Overseas Development Administration but the views expressed are the author’s.

DISSEMINATION OF ENERGY TECHNOLOGIES: STOVE AND FORESTRY PROJECTS IN GUJARAT M.M.SKUTSCH Technology and Development Group Twente University of Technology Enschede, Netherlands Summary This paper presents preliminary findings from a survey of improved woodstove and social forestry programmes which was undertaken in Gujarat in January and February 1985. The purpose of the research, which was financed by the Indo-Dutch Programme for Alternatives in Development, was to analyse programmes in terms of their strategic management, and by a series of comparisons between programmes, arrive at general conclusions about success and failure in programme management. In this, the intent was particularly to distinguish strategies which were effective in reaching the poorest 40% of the population. The major findings were that different dissemination strategies used in promoting stoves led to differences in numbers of stoves distributed, numbers surviving after a period of time, and proportion taken up by the poorest 40%. This was partly due to differences in the design of the stoves, itself resulting from the requirements of particular organisational set-ups and dissemination strategies; and partly due to differences in training, supervision and incentives for the stove builders. The range of social forestry programmes is much more limited as the field is dominated by Forestry Department activities; in this case, success in terms of numbers of trees planted was found but it seems unlikely that this will result in the expected solution to the rural firewood problem, since this shortage is not a general one but restricted to the landless and very poor.

STOVE PROGRAMMES IN GUJARAT In Gujarat there are at least 15 programmes on-going for dissemination of “improved woodstoves”, many of them financed from government sources but implemented through NGOs. Space does not permit a description of each of these programmes individually but their goals do differ. Early programmes were set up to reduce smoke in houses, a health precaution against lung, throat and eye diseases. Cleanliness of the dwelling was often also a key point. It is only since “the other energy crisis” has been recognised that fuel

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efficiency has also been adopted as a goal. Some agencies have taken up stove programmes for still other reasons, e.g. because stoves offer a reasonably simple technology with which to involve village people, so that they may later have confidence to participate in other rural development programmes, or alternatively for political expediency in a situation in which the energy crisis is seen as the problem of the day by government and sponsors. For yet others, stoves offer one of the few technologies with chance of positive impact on women. Inpractice however almost all agencies measure their success in terms of numbers of stoves built and not in terms of these underlying objectives. Further the stove programmes differ in their strategic management with respect to (1) choice of stove (2) participation of the user in the stove design (3) type of stove builders, their training and system of reward (4) quality control. (1) type of stove. All stoves were of the two hole smokeless chula type (with chimney), but they varied with respect to materials of construction, from solid cement to a pre-fabricated concrete slab supported on bricks, to several all-mud models. Many differences in detail such as dimensions, dampers, baffle, pot hole size etc. were taken into account. (2) participation of user. In some programmes the participation of the user consisted of a small payment for the stove (all were subsidised to a greater or lesser extent). Other programmes offered stoves gratis however with no user participation expected at all in any sense. A few programmes committed the users through requiring them to bring materials to the construction site or to bring their own cooking pots to allow exact size of pot holes to be established. None offered the adopter a choice of stoves. (3) type of stove builders, their training and reward system. Four basic strategies were identified among the 15 programmes: (1) The camp system. 30 volunteer students from universities and colleges camp for two weeks in a village, march, sing and build demonstration stoves under guidance of a fieldworker. People “motivated” by this come and ask for stoves to be built for them immediately. Training is on the spot and apart from food & lodging which is provided by the village as a whole, no payment is received by the students. (2) The departmental quota system. Stove building is taken on as part of normal work and distributed by quota among officers who train subordinates often by a pyramidical series of training camps. Usually the number of stoves each final trainee is supposed to build is small (3 to 5), and no reward is given for this. (3) The integrated artisan system.

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Artisans are trained by the organization and hired to build stoves when required on a piecework basis. Relationships between artisan & organisation are cordial and long term. (4) The salaried stove builder system. Stove builders are trained by the organisation and paid both on a piecework basis and a nominal salary for continued work in maintaining and repairing stoves in a certain area, thus becoming in effect staff members themselves. (4) quality control. Most programmes had some monitoring system but action on this was not always forthcoming. In a few cases however follow up was institutionalised. MEASURING SUCCESS AND FAILURE Success of a programme could be measured in a variety of ways but here three methods are used: (1) the number of stoves built This criterion reflects the viewpoint and self-evaluation in practice of the implementing agencies (2) the number of stoves surviving after some period of time This criterion reflects the difference between the agency’s view of what stoves should be like and the user’s, assuming that dissatisfied users will abandon their stoves. (3) proportion taken up by the poorest 40% of the population. This criterion reflects the view of the research sponsor that this group is the most in need of access to technology for basic needs. RESULTS OF THE DIFFERENT KINDS OF PROGRAMMES Success in terms of numbers built was best achieved in programmes using the camp and department system for recruiting, training and rewarding the stove builders. About 60.000 stoves were so constructed since 1973. Usually associated with this, was a stove built of pre-fabricated parts (concrete pre-cast slab and bricks), which is structurally unsound and often breaks. This choice was necessitated by the choice of inexperienced builders with no long term committment to the programmes, and by the scale on which the programmes are intended to run. Participation of users is virtually nil although in some cases a small payment is made (5 rupees). Monitoring was carried out in these programmes but did not result in changes (e.g. in the choice of the materials), and quality control was impossible because of the pyramidical structure of the dissemination process. Success in terms of survival rates was found to occur most in programmes implemented using the trained artisan and salaried stove builder systems where survival

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was about 85% on average. These were also generally the programmes in which locally available materials (mud and dung) were the chief construction materials. Here builders were mainly selected from the village themselves, and were often of low caste; they were able to involve the users in the design at least as far as prefered pot hole size is concerned. They also required a small fee for every stove built, said to promote the value of the stove in the eyes of the user. These stove builders were able to monitor, and to repair stoves when necessary. Related to this good communication system however is the very small scale on which such programmes necessarily operate. Success in terms of proportion of stoves going to the poorest people was not always more in the case of small scale, intimate programmes, as one might have expected. Some of the camp system programmes were linked by their financial sources to low income housing areas (e.g. the House Improvement Scheme) and built 100% of their stoves there, finding a good acceptance rate among the landless labourers for a no-cost stove. Lack of participation in this dissemination progress did not seem to hinder the programme. The small artisan and salaried stove builder programmes had mixed success in reaching this group of poorest people, and on average distributed stoves to all strata in the villages in approximate proportion to their size. GENERAL OBSERVATIONS 1. The strategic elements in programme management are not independent but mutually bound together; the choice of a particular dissemination strategy necessitates a certain type of stove and a certain approach to training and supervision, and results in a certain attitude to quality control. 2. Although efficiencies of all the stoves were said to be in the range 18–26% almost none of the programmes had done serious testing in the laboratory let alone in the field, since many of them were motivated by quite different goals. 3. In practice efficiency varied more from user to user than from stove type to stove type; it was noticable that poor people, using poor grade, small diameter crop residues found efficiency to be low in their improved stoves while richer people using standard firewood approved of the efficiency of the same stove. 4. In any case stoves were rarely abandoned by their users on grounds of poor efficiency. Breakage was the main reason for drop out. 5. The smokeless character of the stoves was said to be of major value to the users and the cleanliness of the house was also appreciated. 6. Very few of the users would have agreed to have stoves had they had to pay the full cost. On the other hand there was no evidence that users who did pay valued their stoves more than users who did not. 7. This section of the paper has examined delivery system only. The real impacts in terms of wood saving, smoke reduction and job creation were also examined in the study and are reported elsewhere.

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SOCIAL FORESTRY. Social forestry, or rather a combination of farm forestry, village woodlots, road and canal side planting and a number of other minor schemes, was introduced in Gujarat more than ten years ago and received a boost with World Bank support from 1980 on. The programme is run by the state forestry department; a number of NGOs have also tried to involve themselves, often in co-operation with the state programme. The aims of the programme were to increase the proportion of land in the state covered by forest as this was well below the national target of 33%, and to provide wood as fuel for households to preserve existing forest and reduce drudgery. The strategy was to provide free seedlings and train large numbers of extension workers who were attached to the programme ,and in terms of numbers of trees planted, targets have in most cases been greatly exceeded. A full review of the success of the programme is shortly to be produced by FAO and will not be attempted here. However from the point of view of strategic management a number of important observations can be made: 1. Tree planting has been taken up on a massive scale by farmers (690m seedlings planted by a rural population of about 25m.) and to a lesser extent in village woodlots. It is profitable, and fulfils farmers’ need to diversify cash crops. Marginal farmers though present to some extent are underpresented in the programme, and landless families cannot plant trees themselves. 2. So far not many trees have been harvested but both farmers and village panchyats fully intend to sell the crop to sawmills and do not envisage firewood as an end product. 3. The firewood shortage is localised in some dry districts, where there is also less social forestry; elsewhere landless and marginal farmers (together 40% of the population) suffer; farmers with 3 or more acres gather all their requirements from indigenous trees on their field boundaries, plus their crop residues. 4. There is a very limited market at present for firewood which is purchased only by a few very wealthy people in rural areas. The poor cannot afford to buy even the small margin of social forestry wood that might be offered as firewood. 5. Some NGOs have cooperated in the programme in a few small areas, often with the intention of involving the marginal farmers to a greater extent but their net impact in this respect has been small.

FUELWOOD SCARCITY IN RURAL INDIA: PERCEPTIONS AND POLICIES S.Mathrani and D.L.Pyle Department of Chemical Engineering, Imperial College, London SUMMARY Fuelwood scarcity in rural India is severe and worsening with increasing deforestation. India’s forest land is 22.8% of its land area, (CFC 1981) but only about half is under tree cover. Deforestation rate is prpbably over 1m ha/year [CSE, 1982); there is acute firewood scarcity in the Indian mountains and deficits in the Indo-Gangetic Plain and in S. India. This paper examines perceptions of fuelwood shortage and its causes. it discusses the implications, for rural fuelwood supply. of population pressures. rural and urban firewood demand, commercial pressures, large development schemes and the Government-backed social forestry programme.

Methodology. The work is based on field visits in India, a postal questionnaire of 13 case-studies and an extensive literature review. (Mathrani 1983). Perceptions of fuelwood scarcity The case-studies reveal interesting perceptions of fuelwood scarcity. The Director, ATDA, Lucknow, U.P., notes that while firewood is crucial to over 80% of the 100 million population in the Indo-Gangetic plain, there is no perceived overall shortage because people can substitute wood with crop residues and do not yet go without food for lack of cooking fuel. The Forest Dept. of Goa, claims there is no overall shortage of firewood in Goa. despite estimating that collecting firewood takes, on average 2– 4h/day/nousehold and up to 6h/day. Similarly, Mr. V.Panwalkar (TISS) feels that villagers in the Shirota area, Maharashtra, are not specially aware of firewood shortages. The time needed for firewood collection is only one factor in the struggle to provide for basic needs which becomes more difficult with worsening poverty. In other words, rural people do not generally separate energy from other problems, rooted in poverty and unemployment: e.g. for them firewood is scarce because they cannot afford kerosene (Barnett, 1982). People in poverty may suffer great hardship and inconvenience before perceiving an overall fuelwood shortage. Definitions vary with quality of life, and locally accepted conditions. In the Atmakur taluk (Kurnool A.P.) for example the population depends on firewood, and over 75% obtain most of their wood by smuhgling. The

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respondent, Dr Ratnaswamy, notes that those most severely affected by shortages are low paid workers with no time to smuggle firewood. Causes of rural firewood scarcity Respondents to the written questionnaire were asked to identify the cause(s) of fuelwood scarcity in their area. In many instances multiple causes were important, as seen by the summary below: Causes of Rural Fuelwood Scarcity No. of Respondents Subsistence agriculture/population pressures 10 Inability to afford fuel 8 Industrial expansion 7 Urban expansion 7 Dam building 6 Felling for urban demand 5 Restricted access to forests 4 Corruption and illegal felling 3 Unscientific forest management 1 Unsuitable tree species 2 Lack of village market 1 Improper distribution of land 1 Inaccessible terrain 1 Shifting (jhum) agriculture 1 Total number of respondents=13. These causes are discussed below.

Subsistence agriculture and rural population pressures These are often assumed to be major causes of fuelwood scarcity, as shown by more than half the case-studies. In some areas new planting is insufficient for the rate of population increase. However the importance of this influence is disputable since migration to towns is significant before population pressures exceed forest capacity. (Dr N.Desai, Adviser Planning Commission and Mr. S.Kothari Lokayan Research Project). In the Kumaon hills of U.P., commercial monocropping of chir-pine, rather than traditional agriculture, has caused soil depletion and deforestation, Bandhopadhyaya (1979). Shifting (jhum) cultivation in the N.E. has caused rapid environmental deterioration, (Ramakrishnan, 1978). Often this is because commercial interests force jhum cultivators onto smaller forest areas and shorter fallow cycles. Rural and Urban Fuelwood demand The rural poor are highly dependent on fuelwood but they mostly use ‘lops and tops from trees cut for timber and seldom fell trees themselves. From official figures (NCAER

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1979) twigs form 66% of firewood and 74% of the rural consumption, and do not contribute much to longterm wood scarcity. Tree felling for urban demand, however, is important. In six of the case-studies firewood supply to the vast urban market is the main source of income for the rural poor. Moulik (I.I.M.Ahmedabad, Gujarat) estimates that Madras city demands over 35m.t. of firewood annually, and Bombay between 60 and 80mt., most felled deliberately. Mahableshwar, a tourist resort in Maharashtra renowned for its lush forests, shows deforestation on a large scale. because of wood cut to supply the tourists and the resident population (Cabral e Sa, 1983). The tribal (adivasi)—among the poorest—do not benefit from this. They feel that their rights to forest land were taken away, first by the British and then the Indian Government. They are reduced to landless labourers, alienated from the forests, which no longer sustain them. Illegal felling continues but tribals are rarely allowed their limited rights to forest produce, and are exploited by forest officials (Anklesaria, 1983). The Chief Conservator of Forests, Gujarat State comments: They are interested only in short term gains for themselves’. We conclude that change is needed in official attitudes to forest ownership. A wider concept of co-operative ownership, combined with an organised supply of fuel to urban areas is urgently needed. Commercial pressures Forests in India are viewed primarily as a commercial resource, and revenue source. In 1980–81, the forest revenue surplus was Rs 1547 mill.1 (CSE, 1982) (Rs10=$1). India’s forest land is mainly state owned. Over half is ‘reserved’ for cattle grazing and grass cutting. About one-third is ‘protected’ allowing lopping tree branches, and gathering dead wood and fallen timber. In both, a fee is charged. Forests are policed. State Governments’ desire for revenue, and high Industrial timber demand have led to over-extraction, worsened by poor management and influential political interests. Questionnaires from Rajasthan speak of powerful local groups exploiting forests for personal profit, and isolate illegal felling and smuggling as the main cause of wood scarcity and deforestation. Jha (1981) reports up to 30 times the marked trees are felled. It is readily acknowledged that illegal felling by contractors (with governmental connivance) is widespread. Industrial timber demand in 1980 was about 20mt (CSE, 1982) whereas the official estimate is ca. 11 mt (CFC, 1981). Yet forest-based industry expands, e.g. rayon and paper. In Ranchi, Bihar, 200 sawmills now operate where previously there were 10. Besides illegal felling, more forests are being ‘reserved’ or ‘protected’ to fulfil contracts thus increasing harassment of villagers. Orient Paper Mills, (the largest in the country) are supplied with monocultured eucalyptus which replace rich mixed natural forest (Vidushak Karkhana, 1982). Eucalyptus is unsuitable for fuel but is valuable for fibre and paper: its use may destroy rural fuel and fodder resources. In Kurnool, local industries now accept lower quality wood from secondary species. It is good that forest industries are becoming less wasteful, but these trends diminish rural fuel resources.

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Large development schemes River valley projects have a most significant effect. In the case-study area of M.P., 1–2% of the net forest area is being submerged annually for dams. In Gujarat, submergence is the most important pressure on forests. Eighty projects are underway in the Narmada Valley alone. By 1979, there were 1554 large dams in India (CSE, 1982) whose environmental costs have largely been ignored. Severe unpredicted deforestation accompanies calculated submergence. For example, the Dholbaha Dam (Kandi, Punjab) irrigates 680ha, while 700ha of forests were submerged. Deforestation in the catchment and around roads was so great that in 1978 Kandi received World Bank funding to reforest 18,000 ha. Badly planned resettlement can compound the problem: in the Kali H.E.P. project this took place more than four years after the site (previously reserved) was cleared and had become eroded. This also increased reservoir siltation (Gadgil, 1979). Deforestation also occurs with the influx of labour, with no provisions for fuel supply, or temporary shelter, at any dam site, for the thousands of labourers. Dams often open up forest areas to encroachment and smuggling. The Idukki dam approach road was built 13 years before construction and agricultural encroachment led to soil erosion. Later, the encroachers were housed on cleared forest land (KSSP. 1979). Large dams disrupt the rural environment, while transferring benefits elsewhere: electrical energy for the urban sector diminishes fuelwood resources for the rural poor. Social Forestry Social Forestry programmes aim to meet peoples’ fuel, fodder and timber needs whilst involving them in the process (CSE, 1982). All 22 States have taken up such programmes, with target success rates between 100%–190% in 17 of the States (Bapat, 1983). Social forestry is increasing and apparently successful. Its two main components are farm forestry on private land by farmers, and extension forestry on wastelands and common lands. Ninan (1983) reports that in U.P. farm forestry had overshot its target by 3430% while village woodlots had fallen short by 92%. What are the successes and failures of social forestry, given different perceptions of its aims?. Moulik, (I.I.M, Ahmedabad, Gujarat) summarises the commonest criticism: that it is generally not social but commercial. In Gujarat over 30% of the schemes replace agricultural land to provide wood, mostly eucalyptus. for pulp and paper and building. Large farmers are interested because the companies supplied also harvest the wood, so saving labour to the farmer as well as yielding high profits. In the process, labourers not only lose their livelihood but also their former fuel-agricultural residues. Vinage woodlots often fail when ‘wastelands’ are owned and used exclusively by the village elders and landowners. In Gujarat seedlings were free thus subsidising large farmers whilst enhancing the projects image. It is also argued that the proliferation of eucalyptus monoculture was unnecessary and had caused land to deteriorate. Social forestry has not alleviated rural fuelwood scarcity, nor is it likely to do so. Official views stress the success in afforestation, regardless of original aims. Gujarat, for example, is often considered a model. It was emphasised by officials that officials often saw the planting of any tree as a step forward. Farm forestry should not use good

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agricultural land, but the Forest Department cannot prevent it. We conclude that ‘Social Forestry’ is a misnomer: programmes do not fulfil their aims; often they worsen the situation of the poorest. Government Policies and Involvement Official poilcy statements (6th Five Year Plan (Govt. of India, 1981)) disapprove of clear felling, of diverting forests to other uses, look for local involvement and the elimination of exploitation of tribals. The Plan, however, also looks to develop the Hydro (HEP) programme and open up regions for paper and pulp. The draft Indian Forest Bill (1980) has been criticised for assuming that the rural and tribal poor are mainly responsible for deforestation, and that its regulations discriminate further against tribals. Reserved forests become virtually prohibited; punishments are very harsh, and Forest Officials are given almost unlimited powers of arrest. Although the Government notes the importance of conservation, the massive Tehri Dam (U.P.) was over halfway completed in 1982, but watershed management had still not begun (Sharma, 1982) There are many other examples of conflicts with conservation policy, (e.g. Times of India, July 1983). In February 1983, restrictions on paper exports were lifted, although India produces under 15% of its needs (Cardozo 1983). Packing case manufacturers obtain concessional timber. With UNDP/F.A.O. assistance, the Government is attempting to minimise wastes, without providing for the rural poor who formerly used them. Some negative official aspects of schemes were demonstrated on a visit to an aerial seeding and eco-development project in Maharashtra, which aimed to seed 3000ha with mixed local tree species. The local people doubted its value, resented their lack of involvement, the failure to include their needs for fresh water and a road, and the obstructive bureaucracy. In contrast, the Bharatiya Agro Industries Foundation (BAIF) at Uruli Kanchan, Pune shows the importance of local involvement. As an established rural development centre, BAIF started to popularise the planting of subabul (Leucaena Leucocephala), a good fodder, fuel and timber species. After intensive campaigning by the local schoolmaster, schoolchildren and parents responded enthusiastically. The wasteland that surrounded the Institute is now densely forested. Headloads of wood are provided preferentially to the poor, at a quarter of the market rate; seedlings are free. Conclusion Policy contradictions can worsen rural fuelwood scarcity and deforestation. Clear policies needed include: establishing co-operative control of parts of forests by forest dwellers; afforestation of areas felled for industries and for catchment; developing micro and mini hydel sources; using barren rather than agricultural lands for social forestry; promoting mixed plantations of local species and not eucalyptus; involving local institutions in afforestation; developing oranised fuel supplies to urban areas: subsidising wood and charcoal for the rural poor.

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Rural fuelwood scarcity is one manifestation of poverty and rural unemployment. The rural poor have to compete for fuel with powerful pressures on forests, and are losing the struggle. Until these factors are recognised and understood at the highest level, and unless explicit steps are taken to protect the weakest sections of society, the severe fuelwood crisis in rural India will worsen rather than improve. BIBLIOGRAPHY Anklesaria, S. 1983, “Colonial Pol icies Leave us Denuded”, Imprint, Feb. Bandyopadhyaja, J 1979, Economic and Political Weekly, 13 Oct. 1979 Bapat, S. 1983, “Social Forestry: it lacks Vitality,” Economic Times, 6 Aug. Barnett, A. et al 1982, “Rural Energy and the Third World”, Pergamon Press. Cabral e Sa, Mario 1983, “Rape of the Ghats”, Business Standard, 29 May Cardozo, N. 1983. “Social Forestry Neglects People”, The Daily, 29 April. Central Forestry Commission (CFC) Min. of Agriculture, Govt. of India, Aug. 1981, “India’s Forests 1980” F.R.I. Press Centre for Science and Environment (CSE), 1982 “The State of India’s Environment 1982: A Citizen’s Report”. Gadgil, M. 1979, “Proc. Indian Acad. Vol. C2, 3, Sci., 291–303. Government of India, 1981, “Sixth Five Year Plan”. Jha, P.S. 1981, “Reforesting the Himalayas: Causes of Denudation”. TOI, 5 Oct. K.S.S.P. July 1979, “The Silent Valley Hydro Electric Project”. Mathrani, S. 1983, “The Causes of Fuelwood Scarcity in Rural India” M.Sc. thesis, Imperial College of Science and Technology. London. Ninan, S. 1983. “Social Forestry Misused” Indian Express, 4 July NCAER, (National Council of Applied Economic Research), 1979, “Domestic Fuel Survey” (unpublished). Sharma, R. 1982, “Rethinking Big Dams (II)” Centre for Science and Environment. Times of India 30th June 1983, “New Township in Kerala at Expense of Forest” Vidushak Karkhana “Planning the Environment” Report to Dept. of Science and Technology, New Delhi, Jan. 1981. Ramakrishnan, K. ‘Slash and Burn Agriculture in NE India’; Proc. Conf. “Fire Regimes and Ecosystem Properties” Dec. 11–15, 1978.

Acknowledgements During this work Ms Mathrani was attached to the Centre for Environmental Technology, Imperial College. We acknowledge with thanks financial support to SM from the SERC in the form of a postgraduate studentship and travel funds for the field work in India.

Implementation of Wood Gasifiers And lheir Use within The Project “Solar Village Indonesia” G.Hoffmann, U.Ohrt, H.Pitzer TUEV Rheinland, Institute for Energy Technology and Environmental Protection P.O. Box 10 17 50, 5000 Cologne, FRG Summary The “Solar Village Indonesia” project was carried out within the frame work of a cooperation agreement in the field of scientific research and technological development between the governments of the Republic of Indonesia and the Federal Republic of Germany (1). The overall aim of the project is to develop and qualify techniques for the utilization of solar energy and biomass resources in an effort to improve the living conditions of the population in rural areas. In this case two wood gasifiers have been installed in order to find out which kind of cooling and cleaning system is the best one, because the purity of the burnable gas and the reduction of condensate production with phenole is important for a sufficient operation of the gas engines.

The Field Test Station Picon is a small agricultural village with approximately 360 inhabitants. The area of the rice fields surrounding Picon is about 60 hectares. There was no irrigation network. The water level of a river near the fields is between 8 to 12m under the level of the fields. Therefore, the rice fields could only be cultivated once a year during rainy season. Considering the situation in Picon, the main objective of the project was to Improve the rice production by use of an irrigation system so that it is possible to get a second harvest. To obtain energy for pumping facilities and solve the problems an integrated energy supply system with wood gasification units biogas plant photovoltaic system has been installed, tested and improved. The two installed fixed bed gasifiers convert wood into burnable gas. This gas is used to generate electric energy by means of a combustion engine coupled to an electric generator.

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Each gasifier has an electric power output of approximately 44kW and is operating independently from the other. The generated electricity is used to drive 10 irrigation pumps with a total waterdelivery capacity of about 600m3/hour and facilities for wood processing, rice processing and a small workshop (see Figure 1). Two gasifiers have been installed in order to find out which kind of cooling and cleaning system is the best one, because the purity of the burnable gas and the reduction of condensate production with phenole is important for a sufficient operation of the gas engines. The two installed systems consist of: 1st system

2nd system

Gasifier

Gasifier

Cyclone

Cyclone

Cork Filter

Water cooled Gas Cooler

Air cooled Gas Cooler

Electric Preciptator

Gas Air Mixing Unit

Gas Air Mixing Unit

Engine

Engine

Figure: 1 Energy Flow Diagram of Picon

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Results Both gasifier systems have been operated with an average operating time of 7h/d and a specific wood consumption of 1.47kg/kWh under the same technical and environmental conditions. Due to the use of the general electric energy pumps it was possible to have a second harvest of rice in 1984. To reduce the production of condensate and hence the formation of phenoles modifications were made to a gasifier. The gasifier so modi-fied (Figure 2) was provided with a hot gas hose filter instead of a cyclone separator and a cork filter. In addition to this the gas temperature was maintained at 55°C by means of a speed regulated air cooler. The result brought about by this temperature control was that the production of condensate and equally the formation of phenole could be reduced from 995ml/h at a gas temperature of 45°C to 50ml/h at 55°C (2).

Figure: 2 Scneme of the modified wood gasifier From the technical point of view we could now say that the cleaning and cooling principle of the modified system is working successfully and reduces the maintenance time to a minimum. From the economical point of view we have made several calculations to compare a wood gasifier system with a diesel generator. The calculation was carried out on the price basis of Indonesia (3).

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Figure: 3 Profitability of Wood Gasifiers as a Function of the Location (rate of interest 14%/a; rates of price increase: electric energy 10%/a; wood 5%/a; fuel 14.5%/a) Figure 3 shows the break-even curves comparing a wood gasification system with a diesel generator. In general, we could say that an economic use of such a system is a function of the place of installation and the availability of wood and its price. In this case the wood gasifiers will have a good prospect for developing countries, where so many remote areas and islands have huge amounts of wood waste available. References (1) Agreement on Cooperation in Scientific Research and Technological Development Concluded in Jakarta, March 20th, 1979 (2) Status Report of BPP-Teknologi, Jakarta, December 7th, 1984 (3) Indonesian Market Price given by BPP-Teknologi, Jakarta, January 20th, 1985

1.4 AND 4.8 MW WOODGAS POWER PLANTS IN OPERATION R.SONNENBERG, W.O.ZERBIN, T.KRISPIN IMBERT Energietechnik GmbH & Co. KG Bonner Str. 42 5354 Weilerswist Federal Rep. of Germany Summary In Loma Plata, the Chacco of Paraguay, IMBERT, Germany installed in 1983 an 1.4MW power plant based on wood gasification. The plant consists of two down-draft gasifiers with 1,800Nm3/h woodgas production each. The gasifiers feed three Waukesha L 7042G gasengine-alternator sets with appr. 465kW of electricity each. This energy is sufficient to satisfy the requirements of a private agricultural cooperative. Up to now the plant has run more than 15,000 hours. In the Sawmill Mabura Hill, Guyana, IMBERT installed in autumn 1984 the world’s largest wood gasification plant: a woodgas power plant with 4,800kW electricity generation. The plant consists of 7 gasifierlines 1,800Nm3/h woodgas each and 7 gasengine-alternator-sets with 685kWe each.

1. 1.4 MW POWER PLANT IN PARAGUAY 1.1 FEEDSTOCK PREPARATION It is necessary for the gasification process to use clean wood-fuel without stones and clay, otherwise the ash in the gasifier becomes slag and disturbe the gasification process. Therefore for the feedstock preparation an area with a hard floor near the gasification plant is arranged. It is recommended that trunks of wood are first cut to lenghts from 1.50m up to 2.50m for easier preparing and handling in the wood fuel comminution system. To accelerate the drying process it is an advantageous to split the stems at the open air. A simple hydraulic splitter has been delivered. The wood residues must then be reduced in sizes to less than 7cm lengths and 150cm3 volume per piece. A drum chipper driven by a woodgas engine is used. The drum chipper runs appr. 3 hours per day producing the required wood fuel for 24 hours gasifier operation. From the chipper the wood chips are transported to a feedstock buffer with conveyor. The wood chips are loaded from the buffer into the feed hopper of the gasifiers. The feed hoppers are equiped to use the exhaust gas from the gas engines to reduce the

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moisture content of the wood. Connecting pipes from the engines to the feed hoppers are installed. 1.2 PLANT LAYOUT The IMBERT Power Plant in Loma Plata, the Chacco of Paraguay, consists of two downdraft gasifiers with 1,800Nm3/h woodgas production each. The gasifiers are fed by means of hoppers with conveyors, which are installed at the front of the gasifiers in an underfloor pit. The fuel is transported from the hopper to the gasifier automatically to match the gasifiers consumption to balance the gas requirement of the engines. The IMBERT Wood Gasifiers thus operates at negative pressure which results from the suction of either the gas engine or a gas blower. The total height of the 1,800Nm3/h-Gasifier is 7.5m and the outer diameter appr. 2.1m. The special construction of the IMBERT Gasifiers with gasifier hearth includes an automatic and rapid adjustment of gas production to the operating conditions so that only that gas required by the engine is produced. The wood descends through the gasifiers by gravity. At start-up, charcoal is loaded in and below the hearth with wood on top. Lighting is very simple: it is done by hand with some straw or some paper and a match. After start-up it only takes about five minutes for gas production to begin, because the charcoal reacts very quickly with the air in the hearth. The total time of appr. 40 minutes is needed to achieve gas production capacity. The air intake is provided by a system of pipes and nozzles, with preheating of the air by the heat in the gas produced. Heat conservation is aided by insulation on the outer jacket. In the continuous gasification process, the solid fuel dries, carbonizes to charcoal and is gasified with air without external heat. In the gasification process the charcoal partly oxidises with the incoming air to carbon monoxide—CO—a combustible gas and also partly to incombustible carbon dioxide—CO2—. However, some carbon dioxide is reduced in the high temperature charcoal bed to CO which increases the amount of the combustible gas, because during the down-draft gasification process the CO2, the steam from the drying zone and the products from the pyrolysis zone must pass through the high temperature charcoal bed. The gasifier is designed such that even 25% of design throughput, sufficiently high temperatures are produced that cracking of the most of heavy hydrocarbons is essentially complete, giving a gas practical free of tar. At such high temperatures the steam partly reduces to hydrogen—H2—and oxygen—02−. The released oxygen combines with carbon C to CO. In addition a small part of methane—CH4—is released. The resulting hydrogen, the carbon monoxyde and the methane are the combustible components of the woodgas. The gas components CO2 and nitrogen—N2−, also the ash are incombustible products. For the start-up of the gasifiers, starting blowers with flares and automatic electric ignitors are used and only a short time is needed to get product gas. The time varies with the size of the gasifier. If operation of the gasifiers is interrupted or terminated, the engines has to be turned off. If an appropriate temperature has already developed inside the gasifier, gasification re-starts immediately after restarting the suction blower, even after long breaks.

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The gas composition varies according to fuel wood and the load of the IMBERT Gasifiers and consists approx. of the following volume percent on a basis: CO=20–23%, H2=18–15%, CH4=1.5–2.5%, CO2=10–15%, N2=47–52%. The lower calorific value of the gas when using air-dried wood is between 4,830–5,460 kJ/Nm3 or 1,150–1,300 kcal/Nm3, depending on the moisture content of the wood and the load on the gasifiers. The ash content of wood is approx. 1% by weight, according to the dry substance. In the gasification process a part of the ash is discharged with the gas flow. Most of the ash and also some fine charcoal fall down into the ash collection chamber, through the lower grate of the gasifier. Normally the grate is moved from time to time by mechanical means to facilitate the removal of the ash. The ash is readily removed through a gastight service opening with an automatic ash removal system. After the gasification process the product gas flows through a dust separator. The precleaned gas passes through a washer and the temperature falls below the dew point. Most of the constituents which might pollute the environment have been removed during the gasification process. Only a small quantity of condensate and ash have to be discharged. An electrostatic filter provides final cleaning of the gas. In this equipment all tiny water drops and any fine dust entrained by the gas flow are nearly completely removed. The reduction of the moisture content in the gas increases the calorific value and the removal of fine dust has an advantageous effect on the life of the combustion engine. Suitable instrumentation and control devices guarantee a continuous and mainly automatic operation. 1.3 WOODGAS-ENGINES To achieve satisfactory operation, correct carburetion is important. With the usual quality of gas from IMBERT Gasifier, a pressure of 5.6 bars is generated over the piston in the engine under European conditions of operation, i.e. up to 500 m above sea level, ambient temperature 20°C and air humidity up to 60%. With IMBERT Gasifiers the power of engines can be calculated with the information in the following table: Engine speed piston pressure PE in HP performance per 1,000 kW output per 1,000 suction engine bar (1 bar =14.5 lbs/m2) cm3 stroke volume cm3 stroke volume 1,000 rpm 1,200 rpm 1,500 rpm 1,800 rpm

5.40 5.35 5.30 5.25

6.0 7.15 8.85 10.0

Turbocharged with intercooler: 1.000 rpm 1.200 rpm 1.500 rpm 1.800 rpm

10.00 11.34 8.33 10.00 13.60 10.00 10.00 17.00 12.50 10.00 20.40 15.00

4.40 5.25 6.50 7.35

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In Paraguay IMBERT installed three Waukesha L 7042G gasengine-alternator sets (12 cylinders, 115.4 Liter/7,040cu. in. cylinder displacement, 1,000 rpm). IMBERT adapted these gasengines on woodgas: Construction of woodgas/air mixer, installation of special spark plugs, adaption of engine control on woodgas etc. The engine power output with natural gas is 554 kWe, with woodgas appr. 465 kWe. 1.4 PLANT EXPANSION Up to now (March 1985) the IMBERT Woodgas Power Plant in Loma Plata, Paraguay runs more than 15,000 hours. Because the produced electricity is only partly sufficient to satisfy the requirements of the customer, the extension of the plant is planed: with a further installation of one gasification line and the installation of turbochargers with intercoolers for the 3 existing engines. 2. 4.8MW POWER PLANT IN MABURA HILL, GUYANA 2.1 PLANT LAYOUT In the Sawmill Mabura Hill, Guyana, IMBERT installed in autumn 1984 the world’s largest wood gasification plant. The plant starts operation in April 1985. The sawmill is located appr. 100km south from Georgetown in the tropic forest region. There is no electricity connection to the grid and diesel transportation to the sawmill will be expensive. Due to lack of water with good qualitiy steam production burning wood waste is impossible. The sawmill will log 94,000m3 lumber per year. The output of the sawmill (sawn lumber Walaba and Greenhart) will be 42,000m3 yearly. To satisfy the power requirements of the sawmill and the township, IMBERT delivered a woodgas power plant with 4,800kW electricity generation. The plant consists of 7 gasifier-lines 1,800Nm3/h woodgas each with the same layout as the Paraguay Plant (see pictures 2–1 and 2–2). But IMBERT installed in Guyana MWM (Motorenwerk Mannheim, Germany) engines G 441BV 16 with appr. 685kWe each (speed 900rpm, 16 cylinders, bore 230mm, stroke 270mm, cylinder displacement 179.48 1, compression ratio 10:1). Two gasification lines and two gasengine-alternator-sets had been tested in the IMBERT works in Weilerswist and reached the required performance. The yearly fuel wood consumption will be 17,000 tons. This wood waste is equivalent via gasification to appr. 10,000 tons of diesel oil or 7,000,000DM foreign currency. The plants in Paraguay and Guyana show that local available wood waste can be turned into necessary energy and the valuable crude oil is saved. Energy from biomasses is both economical and reliable.

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Pict.2–1: IMBERT Gasifier

Pict.2–2: 7 MWM Gasengine Alternator Sets

THE BAMBOO: RAW MATERIAL FOR PAPER INDUSTRIES OR FERMENTATION INDUSTRIES T.TSHIAMALA, A.MOTTET, L.FRAIPONT, P.THONART, M.PAQUOT Département de Technologie FACULTE DES SCIENCES AGRONOMIQUES DE L’ETAT B 5800 GEMBLOUX, BELGIUM Summary In opposition to softwoods which are important raw materials in paper industries, bamboo sylviculture and needs in tropics are well known for a long time. Bamboo can provide rapidly a good homogeneous ligno-cellulosic stock. Different bamboes species have been characterized and treated in order to obtain differents types of pulp. These pulps have been used for paper making or sugars production. Pretreatment such as sulfate or sulfite cooking are very convenient for both applications. At the opposite sight, lime and thermomechanical processes can not be used for such application.

PURPOSE OF THE WORK In opposition to softwoods which are important raw materials for paper industries, bamboo sylviculture and needs in tropics are well known for a long time- Bamboo can provide rapidly a good homogeneous ligno-cellulosic stock. The work aims testing the bamboo aptitude for the development of two major industries: paper industries by using bamboo’s fibres or fermentation industries after cellulose hydrolysis. METHOD OF APPROACH Different bamboes species have been characterized at an anatomical point of view. The bamboes have been treated in order to obtain different kinds of pulp. The main difference of these pulps results from their chemical composition, especially lignin content. The different pulps have been used for paper making and sugars production by cellulose hydrolysis. Materials and methods have been published previously (Thonart et al, 1979; Tshiamala et al, 1984 a; Tshiamala et al, 1984 b).

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SIGNIFICANT RESULTS Different analysis has been done to characterize the pulp: chemical composition, fiber length,…(Table 1) Lime and thermomechanical processes give pulp with a high lignin content (more than 20%). The pulp are difficult to test and not well hydrated. They can not really be used for paper making or cellulose hydrolysis. The situation is different with sulfate pulp and sulfite pulp (figures 1,2 and 3). Good quality papers, especially mechanical strengh are obtained with these pulps (eg. Breaking length: 6000m, tear: 120, bursting strengh 4,0 Kg/cm2). Moreover, these cellulosics substrates are easily hydrolysed by enzymes. Using Trichoderma reesei QM 9414 (0,2U.I.) cellulase complemented by Aspergillus niger βglucosidase (6U.I.), one can obtain hydrolysis yields about 50%, with regard to the whole bamboo (Table 2). These results show that the dissociation of the lignin carbohydrates complex is sufficent to obtain important hydrolysis yields. CONCLUSION Bamboo may be a raw material for paper industries or fer mentation industries. Sulfate or sulfite cooking are very convenient for both applications. PULPS ASH LIGNIN PENTOSANS α-CELLULOSE FIBER LENGTH* Sulfate 1,2 3,2 Sulfite 1,2 11,5 Lime 2,3 23,7 Thermomechanical 0,8 24,1 Fraction (%) retained on 50 mesh

14,3 15,2 15,7 16,4

87,9 78,5 63,3 62,1

75,9 69,8 72,0 53,7

Table 1: Bamboo pulps characterization. TIME OF HYDROLYSIS (h) SULFATE SULFITE LIME THERMOMECHANICAL 1 3 5 24 48 72

7,3 15,0 17,9 35,4 42,7 49,0

8,8 17,0 21,8 31,3 38,1 46,9

2,9 5,1 6,5 10,9 13,1 13,8

Table 2: Hydrolysis yield for different bamboo’s pulps (hydrolysis percentage with respect to the whole bamboo). REFERENCES

0,8 1,6 1,6 3,1 3,9 3,9

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THONART, Ph., PAQUOT, M., MOTTET, A. (1979). Hydrolyse enzymatique de pâtes de papeterie—Influence des traitements mécaniques de préparation. Holzforschung, 33, 197–202. TSHIAMALA, T., THONART, Ph., PAQUOT, M., FRAIPONT, L. et A.MOTTET. (1984a) Hydrolyse enzymatique des pâtes de Bambou: Influence des modes de cuisson et des traitements mécaniques. Holzforschung, 38, 343–351. TSHIAMALA, T., FRAIPONT, L., PAQUOT, M., THONART, Ph. et A.MOTTET. (1984b) Etude comparative des pâtes de Bambou. Holzforschung, 38, 281–288.

Figure 1: Evolution of breaking length in comparison with freeness for bamboo’s pulps : sulfate pulp : sulfite pulp : lime pulp •: thermomechanical pulp

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Figure 2: Evolution of tear index in comparison with freeness for bamboo’s pulps. : sulfate pulp : sulfite pulp □: lime pulp •: thermomechanical pulp

The bamboo: raw material for paper industries or fermentation industries

Figure 3: Hydrolysis yield of bamboo’s pulps. (5’ beating) : sulfate pulp : sulfite pulp : lime pulp •: thermomechanical pulp

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ISSUES RELATED TO INTRODUCTION OF ENERGY-CANE TO LATIN-AMERICA P.JAWETZ and G.SAMUELS Consultants on Agriculture and Energy Policy 235 E. 54 St., New York, N.Y. 10022, USA Summary Energy-cane is sugar cane managed for high biomass yield—fermentable juice for fuel alcohol and combustible solids for electricity. Latin America grows sugar for domestic consumption and for export to favorably priced sugar quota markets; the excess is sold to a depressed world market. Switching from excess sugar production to energy-cane will enable the use of alcohol for domestic fuel needs and for exports of ethanol octane boosting additive to gasoline needed because of lead plase-out in the United States and in Europe. Quantities of ethanol produced on these “excess” lands, that is without expanding cane agriculture, could reach 3.6 billion liter of fuel ethanol in Brazil alone. The fiber or woody residue of the energy-cane (the bagasse) can be used for boiler fuel for domestic electrical production eliminating imports of fuel oil.

1. INTRODUCTION Columbus brought sugar cane to Hispaniola. Eventually cane became a source of food and a major export crop for most of Latin America. Now, increased population and higher living standard requirements cause increasing pressure on governments and on the land calling to provide more food, clothing, shelter and energy; energy being supplied now mostly by importa-tion of oil. Energy-cane is sugar cane managed for high biomass yield—total fermentable juice for fuel alcohol and combustible solids for electricity rather than for crystallizable sucrose. Policy problems at government planning levels, in the field and in the sugar factory surface when introducing energy-cane management of sugar cane in traditional sugar cane growing areas. The problems vary with location but certain common features exist. The object of this paper is to present issues related to the introduction of energycane to Latin America and to suggest possible solutions. 2. THE ENERGY-CANE CONCEPT When sugar cane is grown for crystallizable sugar, high sucrose varieties are used and agronomic efforts include restricting nitrogen fertilizer application, limiting irrigation near harvest to enhance maturity, and harvesting when the cane reaches its maximum

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sucrose content. The fields are usually burnt prior to harvest to reduce cane trash (tops of the cane stalk and leaves). The sugar cane factory is geared to extracting as much sucrose from the cane stalk as economically feasible using all of the bagasse as a boiler fuel. The main product at the sugar factory is raw and/or refined sugar with final or black-strap molasses as a residual product. The energy-cane concept is a management rather than varietal concept although work with some varieties was more successful than with others. The agronomic practices are selection of high tonnage varieties, improved land preparation, increased fertilization especially nitrogen, adequate irrigation at all times, maximizing growth up until harvest and inclusion of cane tops and leaf trash in the final tonnage. The energy-cane concept was developed by the Biomass Division of the Center for Energy and Environment Research (CEER), University of Puerto Rico (1), in work that started in 1977; green biomass yields up to 300 metric tons (MT) per hectare, in a 12month crop, were obtained. 1.25MT whole energy cane (the whole unburnt cane stalk including leafy tops and attached dried leaves) gives one MT of commercial millable cane (stalk only). The cane stalk, the tops, and the trash, provide the combustible fiber (bagasse). One MT of bagasse (6% moisture) has a caloric value of 17.4×109J which in turn has an electrical equivalent of 4.384KWh or a fuel equivalent of 437liters of fuel oil. The cane juice, if not used for sugar, can be fermented directly to alcohol giving 65liters ethanol per MT cane. If sugar is extracted the fermented final molasses yield 0.37liters ethanol per liter of molasses. About 60 percent of the sugar can be extracted in the first crystallization (“A” sugar) of the cane juice. Molasses remaining after the first sugar extraction are richer in fermentable sugars and bring a better price for ethanol or rum production. In the energycane concept, the cane itself is not as high in sucrose as most conventional sugar cane; however, much more cane per hectare is produced, giving a higher sugar production per hectare. Where sufficient fiber for year-round boiler operation is not available from bagasse or cane tops and trash, tropical grasses such as Napier (Pennisetum purpureum) can be grown as a supplementary boiler fuel (1). 3. ADOPTING THE ENERGY-CANE CONCEPT Six alternatives for products’ schemes when adopting energy cane for a particular situation are listed, some examples follow Case 1:

Sugarcane—sugar—final molasses

Case 2:

Sugarcane—sugar—molasses/alcohol

Case 3:

Sugarcane—sugar—molasses/alcohol—cane trash/ electricity

Case 4:

Energy-cane—“A” sugar—“A”molasses/alcohol—bagasse and cane trash/electricity

Case 5:

Energy-cane—“A” sugar—“A” molasses/alcohol—bagasse, cane trash and energy-grasses/electricity

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Energy-cane—cane juice/alcohol—bagasse, cane trash, energygrass/electricity.

3.1 Sugar Importing Countries. In six Latin American countries sugar production has not been sufficient in recent years to satisfy domestic needs requiring imports: Ecuador with 1983/84 sugar production of 37% of domestic sugar consumption, Uruguay (40%), Venezuela (52%), Mexico (84%), Peru (86%) and Paraguay (96%). Mexico and Venezuela, before the discovery of oil were sugar exporters. At present, due to growing population but lacking sufficient farm labor, they must import sugar. Adopting energy-cane as in case 5 could provide Mexico, Peru and Paraguay sufficient sugar for domestic consumption on the land now used for sugar cane. Ecuador, Uruguay and Venezuela would still not be able to produce enough sugar for local consumption with present land areas using energy-cane as the only sugar source. Case 3, continuing to grow sugar cane but using the molasses for alcohol and cane trash for electric power (0.25 tons cane trash usually burned at harvest, can be obtained for one MT of millable cane) would provide for 27% of present electric needs of Ecuador, Peru 17%, Mexico 16%, Venezuela 9%, Uruguay 1% and Paraguay the astonishing figure of 64%. For this case the ethanol production from molasses would be 358 million liters for Mexico, Peru 95, Venezuela 60, Ecuador 12, Paraguay 8 and Uruguay 7. (One liter of final molasses produces 0.37 liters ethanol). 3.2 Sugar Exporting Countries. In November 1974, sugar traded at over 50 cents per pound, while in November 1984 it was less than five cents. The U.S., the leading importer of Latin American sugar, initiated a quota import system and price regulations. The U.S. sugar quota import price at present is 21 cents per pound (2). Similarly, the Lome Treaty allows quota preferred sugar imports to the European Common Market for Barbados, Belize, Guyana, Jamaica, and Trinidad. Except for the sugar quota sales sugar production has become a burden to Latin American economies; this at a time that the oil import bill has grown from billion in 1973 to over billion in 1983 (3). Brazil, looking for an alternative, is using fuel ethanol from sugar cane, as replacement for gasoline and will produce about 10 billion liters of ethanol in 1985. Argentina, Costa Rica, El Salvador, and Colombia initiated projects for domestic use of ethanoí-gasoline blends (4). While the U.S. market for sugar is sluggish, the demand for ethanol was spurred by U.S.Environmental Protection Agency regulations on lead phase down in gasoline. The U.S. corn-ethanol manufacturers will not be able to meet the ethanol needs and this offers Latin American sugar producers an export market (5) if no artificial barriers to such imports are established. Energy cane has two major energy products: ethanol for motor fuel and bagasse or fiber for boiler fuel or electrical power. A large potential is present if the excess land now in sugar cane (for which there is no ready sugar market for domestic consumption or quota exports) where to be planted energy-cane solely for energy production (Case 6). The energycane juice could render ethanol quantities ranging from 27 million liters for

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Costa Rica to 3.6 billion liters for Brazil from these lands alone. Table 1 provides figures for this restricted use of energy cane. Electrical production from the energy cane, bagasse and trash is sufficient for the Dominican Republic and Guatemala to supply all of their electrical needs. For the other Latin American countries there is also significant potential. Estimates cannot be prepared for Cuba, because sugar export fi-gures are not available. However, calculation have shown that Cuba has a potential to produce more than five times its electrical needs from energy-cane production from all of its land planted sugar cane (7). Additional biomass for electricity could be obtained from sugar cane trash on land now in sugar cane for domestic sugar and export quotas. 4. DISCUSSION A favorable picture is obtained of the use of energy-cane in Latin America without major changes in labor or land and without interfering with production of food. Long-range usage of the complete energy concept will be dependent on the exhaustion of oil reserves for Mexico and Venezuela. The sugar exporting countries can make excellent use of the energy-cane concept in providing for their energy needs and still maintain favorable domestic sugar and quota exports. Ethanol production for domestic consumption and export will improve the balance of trade. Brazil and Argentina are leading candidates for ethanol production for export. The Brazilian autonomous sugar cane alcohol complex, with no production of sugar, lends itself most readily for the energy-cane concept (Case 6). Increased tonnage per hectare will bring more production of ethanol per hectare even though energy-cane varieties may be somewhat lower in total sugars per cane. However, use must be made of the bagasse produced for additional boiler feedstock for electricity. Although Brazil does have cheap hydropower it nevertheless can make use of energycane electric power in its remote agricultural-industrial areas. Perhaps not in the near future, the use of cane cellulose for production of simple sugars for ethanol feedstock (5) will benefit the energy-cane concept. Additional land for energy-cane growing may be available in certain Latin American mainland countries beyond those lands now in sugar cane production (8). The Dominican Republic is investigating the utilization of cane tops and leaf trash for electrical production, rather than going to full energy cane (9), despite their need for both ethanol and electricity to lower imports of oil, Jamaica, participating in an AID project for production of electricity from cane trash and bagasse, has chosen to continue extracting all the sugar from its energy-cane and use the molasses for the rum industry in a proposed modified energy-cane project at Monymusk (9). It should not be expected that countries can approach the use of the energy-cane concept in the same manner. REFERENCES (1) ALEXANDER, A.G. et al. (1982). Production of sugarcane and tropical grasses as a renewable energy source. Final Report to DOE, Years 1–5. (2) ANONYMOUS, (1983) Sugar, molasses and honey. Foreign Agriculture Circular, USDA. Foreign Agriculture Service, Washington D.C. FS 2–18, November.

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(3) RIVERO, N. (1985) The sugar industry: The challenge of change. Sugar y Azucar, vol. 80(1) 20–26, January. (4) ANONYMOUS, (1985), New Sugar Projects. Sugar Journal, Vol. 47(8)27. January. (5) ROTSTEIN, J. (1983) Brazilian Alcohol in The American Gasoline. Center for Strategic & International Studies, Georgetown Univ., Washington D.C. (6) JAWETZ, P. (1980), The Economic Realities of Alcohol Fuels. Sugar Journal Vol. 42(8), pp. 13–16. (7) SAMUELS, G. (1984), Potential production of energy- cane for fuel in the Caribbean. Energy Progress, Vol. 4(4), 249–51, December. (8) JAWETZ, P. and SAMUELS, G. (1983). Energy as an agricultural output in the production of fermentable fuel ethanol. Lecture Book, Int. Symposium-Workshop on Renewable Energy Sources, 18–22 March, Lahore, Pakistan, Clean Energy Research Inst. Univ. Miami, Coral Gables, Florida. (9) SAMUELS, G. and JAWETZ, P. (1984) . Policy issues in the transfer of energy cane to the Caribbean. Southeast Industrial Biomass Energy Exposition, Technical Review Sessions, Atlanta, GA. Nov 28–29.

Table 1 Potential Electric and Ethanol Production from Energy-Cane Grown on Land Now Devoted To Sugarcane For Non Secure Markets. Country

Land for Electrical Production Energy Cane from energy Domestic Needs from Ethanol from “The Excess” cane Production Energy Cane Energy Cane 1) 2) 3) 4) 5) Ha×103 KWh×106 KWh×106 % L×106

Dominican 100.6 4,578 2,763 166 654 Rep. Costa Rica 4.2 191 1,800 11 27 El Salvador 0 0 0 0 0 Guatemala 29.9 1,360 1,290 105 194 Honduras 6.1 278 701 40 40 Nicaragua 14.9 677 1,180 57 97 Panama 12.4 564 1,260 45 81 Argentina 78.4 3,567 35,200 10 510 Bolivia 8.2 373 1,320 28 53 Brazil 544.4 25,225 137,300 18 3,604 Colombia 18.2 1.250 14,343 8 178 1) Total land in sugarcane production minus land in sugarcane for domestic consumption and U.S. quota, 1983–84 (2). 2) Based on an assumed whole energy cane (stalk, tops and leaf trash) production of 125MT/ha (except Colombia where present production is already double other Latin American countries)/ thus energy cane production is assumed at 188 MT/ha where whole energy cane fiber produces 364KWh/MT or 45,500KWh/ha. 3) From data by Bonnet Jr. J.A., director of CEER, Puerto Rico. 4) Potential electrical production from energycane divided by domestic electrical production. 5) One MT whole energy cane produces 52liters ethanol from cane juice times 125MT/ha whole cane or 6,500liters/ha.

THE POTENTIAL FOR ALCOHOL AS A FUEL FOR SPARK IGNITION ENGINES IN TANZANIA J.S.CLANCY and G.RICE Department of Engineering, University of Reading, Reading, U.K. RG6 2AY and S.KAWAMBWA Institute for Production Innovation, University of Dar-es-Saleem, P.O.Box 35075, Dar-es-Salaam, Tanzania Summary Tanzania experiences restrictions on liquid fuel availability. In the rural areas this has considerable implications for irrigation and for small scale industry. This paper describes work currently in progress on a systems study to assess the potential contribution that locally produced alcohol could make to national fuel self-sufficiency, in particular for stationary spark ignition engines in rural areas, and its impact on agricultural production. In an attempt to overcome the problem of competition of fuel crops for agricultural land it is proposed that the raw material for ethanol production should be market fruit wastes, which at present constitute a disposal problem. A 4-stroke single cylinder 2.2 kW Briggs and Stratton spark ignition engine is currently being tested with fuel of different ratios of ethanol to water to assess its power output and performance. Stationary engines are generally over-rated for their application so that it is expected that a loss of power-output should not be detrimental to the end-use. The higher the percentage of water the engine is able to run on without too great a loss in performance has considerable significance for the economics of the alcohol production. An optimisation of these parameters is being undertaken.

1. INTRODUCTION Agriculture is the key sector in the Tanzanian economy providing 90% of total employment and 80% of exports (1). The Government is currently placing emphasis on agricultural development to increase food production. When considering suitable strategies for adoption the low level of mechanisation would make this appear a priority. However, this has considerable implications for imports, particularly equipment and fuels.

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The University of Reading, in conjunction with the Institute of Production Innovation, has been assessing the potential for small scale irrigation using spark ignition engines with locally produced enthanol as the fuel. Irrigation is not commonly practiced in Tanzania and so a properly implemented scheme should make a major contribution to increased productivity. Such a system could have additional benefits. Increased food outputs not only provides more for local consumption, reducing dependency on imports and food aid but also increases incomes in the rural areas. Local small scale production of ethanol should also provide jobs which should help to stem urban migration. This paper is a synopsis of work recently completed for an MSc thesis (2). The conclusions from this work were promising and are forming the basis of continuing work in the two institutions. 2. A SYSTEM OF IRRIGATION APPROPRIATE FOR TANZANIA Irrigation projects in Africa do not appear to have been a major success. The main criticisms have been levelled at large scale dam schemes and those notable successes appear to have been primarily with small scale schemes using ground water or lift irrigation (3). Small scale projects would prove to be more compatible with the average Tanzanian land holding . (4). When choosing a power source for lift irrigation the authors believe that small engines provide amore flexible option since they are more easily transported than some of the other renewable energy options. Their operation is also less subjected to climatic conditions. The choice of engine is usually based on fuel cost, which means diesel (compression ignition or CI) engines are selected in preference to kerosene (spark ignition or SI) engines. However, SI engines are lighter and therefore can be employed for other purposes at other locations within a farm or village. Although their life time is less than CI engines they have a lower capital cost. The use of magneto ignition helps to keep down the system cost. In the past they were originally widely used for stationary purposes and small boat propulsion. Today several countries still employ them for water pumping e.g. Guyana (5). The need is primarily for a much cheaper fuel. SI engines operate as well on ethanol as petrol. The major problem is a loss of power output, which can be compensated for by using high compression ratios. There is some concern about the poor lubrication properties of ethanol. This could be overcome by using a 2 stroke engine, with a suitable vegetable oil (e.g. Castor oil, locally available in Tanzania) as a lubricant. 3. CONSTRAINTS (i) Feedstock The fear that prime agricultural land may be diverted to fuel production is understandable. To overcome such criticism, the authors therefore are proposing the use of fruit waste from markets and farms as a suitable feedstock for ethanol production. The additional advantages to this source are that its availability is not restricted by

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geographical distribution, or seasonal variation, and it provides a solution to a disposal, and a possible health, problem. The potential from cashew apples alone(a non-food source in Tanzania) has been estimated by IPI as 30 to 50 million/ℓ per annum. From this it is possible to estimate that 5,000 to 25,000ha of arable farm plots could be irrigated (using parameters of 2ha irrigated area at 7m head requiring 60m3 per day per ha (6)). (ii) Production Large scale production systems have the advantages of economy of scale. However, in a country like Tanzania, the high cost capital equipment would place a heavy burden on foreign exchange. Also large systems require a well organised transport system which will use large quantities of diesel oil, and form a significant part of the ethanol production costs. However, if a smaller system is used, based on the quantities of feed stock available at the end of local markets, the problem of transporting the feedstock have been overcome and the cost can be neglected. There is a need to devel-op small p-oduction and storage systems from appropriate materials available in Tanzania. Also more data is required on the costs and energy balances IPI are currently developing a still which produces . (iii) Locally available skills The SI engines currently available are optimised for running on petrol, and to achieve the same power output from ethanol would require modification. This requires a certain degree of skills access to appropriate equipment etc. In Tanzania the number of skilled mechanics is rather small and they tend to be concentrated in the towns. However, familiarity with minor repairs and servicing of small engines is often found in rural areas. These are important skills to build upon rather than immediately trying to introduce a new technology. The authors, recognising this constraint, are optimising their system based on minimum engine modifications which require only those skills available in Tanzania. 4. ENGINE TESTS We have investigated the performance of a Briggs and Stratton single cylinder 4 stroke 2.2kW SI engine, on both absolute alcohol and alcohol with various % of water. The initial test results have been presented in more detail elsewhere (2, 7). Representative curves of the data so far obtained are shown in Figs. 1 and 2. The results so far obtained are in agreement with those given in the literature i.e. a reduction in power output matched by a corresponding increase in fuel consumption as the amounts of water in ethanol increases. Enlargement of the main fuel jet to give a similar power output to that using gasolene would certainly be possible in Tanzania.

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5. CONCLUSIONS The system proposed of small scale irrigation powered by SI engines using a locally produced fuel would appear initially to be promising for use in rural Tanzania. A programme of work is continuing to compare 4 and 2 stroke engines, using alcohol as a fuel, when matched to a suitable pump. It is noted that there is considerable need for the development of small scale fermentation and distillation systems appropriate to Tanzanian conditions. 6. ACKNOWLEDGEMENT One of us, S.Kawambwa, would like to thank the German Academic Exchange (DADD) for financial support to attend the MSc course in Alternative Energy in Developing Countries at the University of Reading, for which the work reported in this paper formed the basis for his MSc thesis, S.Kawambwa would also like to thank his employers, the Institute of Production Innovation, University of Dar-es-Salaam, Tanzania for granting study leave. 7. REFERENCES (1) The Courier, Sept/Oct. (1983). (2) KAWAMBWA, S.J.M. (1984). The Potential for Alcohol as a Fuel for Stationary SI Engines in Tanzania, MSc Thesis, University of Reading. (3) CARRUTHERS, I.D. (ed) (1983). Aid for the Development of Irrigation, OECD. (4) HYDEN, G. (1980). Beyond Ujama in Tanzania. Heinemann Educational Books Ltd., London. (5) JORDON, L.A. (1984). Feasibility Study of a Low Lift Pump for Guyana’s Costal Agriculture. MSc Thesis, University of Reading. (6) HALCROW, Sir William and Partners, in association with IT Power Ltd., (1983). Small Scale Solar-Powered Pumping Systems: the technology, its economics and adcancement. UNDP Project GLO/80/003. (7) CLANCY, J.S., KAWAMBWA, S.J.M. and RICE, G. (1984). The Potential for Alcohol as a Fuel in SI Engines in Rural Tanzania. Proceedings of Conference on Small Engines and their Fuels, University of Reading, Sept. 1984. Pub. Institute of Energy, London.

The potential for alcohol as a fuel for spark ignition engines in Tanzania

Figure 1 Constant throttle power-speed characteristic Throttle position 1

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BIOGAS AS FUEL: THE ADAPTION OF A TRACTOR DIESEL ENGINE AND A SMALL SPARK IGNITION ENGINE TO BIOGAS OPERATION J.FANKHAUSER, M.RUDKOWSKI, E.STADLER, K.EGGER and A.WELLINGER BIOGAS PROJECT, Swiss Federal Research Station for Farm Management and Agricultural Engineering, CH-8355 Taenikon Switzerland 1. INTRODUCTION The economic feasibility of an anaerobic digester depends in many instances on the extent that the produced biogas can entirely be used within the farm. The easiest way is to burn the gas for space heating and hot water production. However, in sommer usually excess gas is produced. An attractive alternative to just flare the gas off is to burn it in a engine either to run a tractor if enough gas is available, or with smaller quantities to drive a generator or to power agricultural machinery such as a ventilator for hay aeration. All of the three posibilities were subject of major or minor projects of our group during the last three years and will be shortly discussed in this paper. 2. CHANGE OF A TRACTOR DIESEL ENGINE TO DUAL FUEL OPERATION Adaption of the tractor: The major problem of using biogas as a tractor fuel is its low energy density. In order to carry an adequat amount of gas on the tractor, it has to be compressed to 200bar which corresponds to the upper “limit allowed by law in Switzerland. The space for gas bottles is limited. The best solution found for our Deutz D6507 test tractor was the fixation of four bottles of 401 each along both sides of the hood and a fifth bottle at the side below the drivers cabin (Fig.1). This set-up allowed an equal distribution of the weight and an optimal protection of the bottles without impeding the driving. The total amount of gas (60% CH4) of 60m3 (STP) corresponds to about 40litre of diesel and allowed an operation of 3.5 hours at full load or about 7 hours at 40% load, an average power output to be expected under Swiss farming conditions.

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Fig.1: Dual fuel (biogas/diesel) test tractor To fuel the engine, the gas was expanded to 2millibar underpressure by the aid of a reduction valve developped in Italy (Tartarini) for cars running on natural gas. The valve is thought to be heated by the engine’s cooling water circuit. With the test tractor beeing air cooled, the valve had to be placed in the hot air stream in order to avoid freezing of the CO2 while the gas was expanded. Adaption of the diesel engine: Biogas is an excellent fuel for engines with spark ignition, thanks to its high knock resistance quality. Today however, the predominant part of the agicultural tractors are powered by diesel engines. For their use with biogas the dual fuel system is a very acceptable solution because it has the capability of running entirely on diesel oil if the gas supply fails. The major problem we have been concerned with when we converted the motor, was the control of the amount of diesel injected to ignite the air/gas mixture which should preferably remain constant over the whole range of engine speed. A simple blocking of the control rod at a fixed position was not possible, because with a fuel pump in row the oil delivery increases with increasing rpm’s. For an engine speed correlated adjustment of the control rod, a pneumatic reset device was installed which was regulated by the underpressure of the air intake manifold. In a first set-up this same reset device was also used for starting the dosage of the oil injection when the engine operation was changed from diesel to dual fuel (Fig.3). This purely mechanical regulation worked fine however, it was very difficult to install due to the limited space available and the adjustment of the control rod was rather delicate. A simpler, but slightly more expensive solution was found with an electric relay allowing to place the pneumatic device closer to the fuel pump (Fig.2 and 3).

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Fig.2: Dual fuel engine with mechanical regulation of gas flow and pilot spray injection. The power regulation of the engine in the dual fuel mode i.e. the regulation of the gas inlet valve was in a first construction electrically controlled. In the final design however, the mechanical speed regulator of the tractor was used to control the gas valve, as it was recommanded by Tartarini (Fig.3).

Fig. 3: Modifications with the “Tartarini-Kit” changing the diesel into a dual fuel engine.

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A. Mechanical regulator Bosch EP/RSV B. Pneumatic regulator C. Gas regulation valve d. Control rod e. Arc lever to guide control rod: switched on and of electromagnetically x. Gasline from reduction valve y. to Venturi z. to intake manifold Test results: On the test stand the engine was adjusted in such a way, that during diesel and dual fuel operation the same torque respectively brake power characteristics were obtained (Fig. 4). Except for a short power brake, the engine could easily be switched from one mode of operation into the other. At full load the same efficiencies were achieved in dual fuel

Fig. 4: Torque and brake power characteristics during diesel and dualfuel operation. operation as with diesel alone, whereas at partial load, diesel alone was superior. While at nominal performance the diesel consumption amounted to 220g/kWh in full diesel operation, 30g/kWh of diesel was required in dual fuel operation in addition to the 400l/kWh of biogas. The savings of diesel fuel thus amounted to about 86%. At a 40% load and an engine speed of 1’400 rpm (the average load condition of agricultural tractors in Switzerland), the consumption of the diesel operation amounted to 250g/kWh and for the pilot spray operation to 80g/kWh at a gas consumption of 600 l/kWh (Fig. 5) The saving of the diesel fuel thus amounted barely to 70%.

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Fig. 5: Specific diesel oil (A) and biogas consumption (B) during dual fuel operation in g/kWh respectively l/kWh. The performance of the biogas tractor in the field tests essentially confirmed the results of the test stand experiments. The tractor was to drive like a regular diesel tractor except, that it was sometimes difficult to keep a constant engine speed at low partial load around 900 to 1100rpm. As the farmer said, it was like driving a tractor built in the fifties or the early sixties 3. A SMALL SPARK IGNITION ENGINE OPERATED ON BIOGAS On Swiss farms quite often small petrol engines are in use to run emergency generators or agricultural machinery. One of the most widespread one-cylinder, air-cooled, four stroke engine (MAG 1045SRL) was converted to run either on biogas or on petrol. The system was equipped with a 3-phase generator of 5kW maximal power with an efficiency of 78.5% as Indicated by the distributor. The motor run at a speed of 3000±50rpm with a constant power of 10.5HP (7.73kW). To fuel the engine with biogas, a venturi jet with a diameter of 32mm supplied with 6 gas inlet holes of 3.5mm diameter each was installed between the air filter and the carburator. A constant gas flow was maintained with a two-chamber pressure regulator designed by our group. A first valve opened at very low underpressure when the motor run at idle, and gave way to a gas line which by-passed the venturi and entered the air intake manifold behind the throttle. The main valve opened with the throttle. The motor was loaded by an increasing number of lamps and the power of the entire system determined by a three-phase current meter. The maximal power output of the generator registered was 4.25kWh. Prior to the gas test, the original efficiency of the engine running on petrol at a generator power of 3.25kW was improved from 16.6% to 24.5% by reducing the size of the carburator nozzle. During the operation with biogas (63% methane) the efficiency of the system was by 1% to 3% lower than with petrol over the whole power range (Fig. 6). At 3.25kW the engine eficiency was 23.5%, hence still better than the original set-up. An even higher efficiency and power output (25.2% resp.

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3.7kW) was achieved when the orifice of the gas regulator was slightly decreased however, the engine speed could not be kept

Fig. 6: Efficiency and brake power of the spark ignition engine runing either with petrol or biogas. constant anymore. In the upper power range the gas consumption was about 1m3 per kWh. Because the motor was equipped with a cable starter, the few piston strokes did not allow the formation of an ignitable gas mixture. Hence, the engine was allways started with petrol and switched to gas later on.

THE USE OF GAS FROM BIOMASS IN ENGINES—EXPERIENCES E.Nolting, M.Leuchs M.A.N.-Neue Technologie, Munich, Germany Summary Up to now the only suitable way to get power out of biomass (up to about 1MW) is by applying internal combustion engines. In almost all cases the fuel is gaseous being produced in anaerobic digesters or thermal gasification or pyrolysis-systems. Experiences with engines running on gaseous fuels from biomass have reached a considerable level. This report will summarize experiences gained with gas from sewage water treatment plants, anaerobic digesters of agricultural wastes, landfills and thermal gasification plants. As a result one can state, that a successful performance of gas engines is given in all cases. The essential premise for flawless operation is a gas sufficiently cleaned from dust (less than 5µm and 0,6mg/m3) and corrosive, oil spoiling gases like H2S, fluoric and chloric hydrocarbides.

1. General remarks Adapting internal combustion engines to different gaseous fuels, several points have to be observed: – The gas heating value and the ignition property of the gas-air-mixture have to be sufficient in the sense, that conventional ignition systems can initiate the combustion. – The knocking quality of the gas has to be determined or interpolated from experience in order to adjust the compression ratio of the engine. – The gas-air mixing device has to be adjusted to the specific air/gas ratio needed. In some cases the device has to be able to follow changes of gas quality. – The influence of the gas quality on power-output and efficiency of the engine has to be considered (Tab.I and Tab.II). For gases from biomass discussed in this paper (gas from sewage water treatment plants, anaerobic digesters for agricultural wastes, landfills and thermal gasifiers) all of these problems are solved. The gas engine is ready for application in the field of gaseous fuels from biomass. We can state this, because we have gained a lot of experiences in different plants.

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2. Specific experiences 2.1 Gas from sewage water treatment plants The gas quality of sewage water treatment plants is in general well suitable for gas engines, because the methane volume is about 60%. Only the corrosive component H2S has to be considered carefully. For flawless operation the engine manufacturers like M.A.N. allow 0, 15% (volume) of H2S. This corresponds to the sulfur content in heavy fuels. The sewage water treatment plant at Großlappen has long term experiences with gas engines being used for heat and power or heat and compressed air. There are eight engines installed with a total capacity of 6,200kW. They are in operation since the mid of the sixties with more then 40,000 running hours. At the Soest sewage water treatment plant a highspeed gas engine (1500rpm, 155kW) is running on sewage gas or natural gas. The switch over is done automatically. The cogeneration modul is used as emergency set as well and running since 1980 more than 20,000 hours. 2.2 Gas from anaerobic digesters The gas from anaerobic digesters is basically the same as that from sewage water treatment plants. There are differences, though. The purpose of sewage water treatment plants is to clean waste water and anerobic gas production is only one part, while anaerobic digesters for agricultural wastes are optimized for gas production. For the gas engine these differences are of minor importance. Usually the gas from sewage water treatment plants has to be cleaned from H2S more carefully. The plant, of which we can report successful performance, has been installed in 1982 in Ismaning. The anerobic digester—two containers of 500m3 each—was built as a testplant with federal money. The biomass is a mixture of cattle and pig manure and vegetable wastes. The engine installed is capable of producing 85kW electric and 140kW thermal power. The farm is separated from the public grid, whenever the engine runs during working hours (about 10 hours every working day). The heat of the engine available at 90°C is partly needed for the digester to keep the temperatur at 35°C and used for other heating purposes. Engine related problems have been H2S corrosion in gas supply components like pressure governers. A H2S filter had to be installed. A total of 4000 running hours has been reached by today. 2.3 Gas from landfills Gas from landfills originates from anaerobic processes in oxygen free zones within a landfill site. Gasproduction usually starts a few month after the deposit and lasts about 20 years. The gas quality is less steady, because of less specific conditions of the gas production. The range of the methane content is between 30% and 60%, because of an important amount of nitrogen and a few percent of oxygen. The nitrogen is the leftover of the air, which was included in the deposited materials and the oxygen of which has been

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used up by aerobic processes. Air, which is sucked through leaks in the landfill and the gas wells, is responsible for the oxygen. Depending on the kind of waste, which has been deposited, traces of further gas components create problems for engines. Besides H2S, which can be handled by filters and by the material, traces of cholorine and flourine in hydrocarbons up to several hundred mg/m3 have been found. It looks like contents up to about 50–100mg/m3 can be tolerated in gas engines. To handle higher contents of corrosive gas components, research is concentrating on new materials and oil additives for the engine. We can report about two plants, one in Ludwigsburg (Stuttgart) and one close to Biberach: At the Ludwigsburg landfill “Am Lemberg”, the KAWAG utility installed two gensets with sparkfired gas engines and induction alternators. An automatic air-gas-mixture device was implemented or the first time in Germany. The plant is in operation since 1982 and both sets reach about 8000 operating hours per year. An average chlorine content of about 20mg/m3 has been measured. In a 20 feet container M.A.N. designed a 240kW power unit with a 12 cylinder turbocharged engine (Gas-air-mixture turbocharging). The container was installed at the landfill “Reinstetten” by the EVS utility. Since September 1984, the unit runs 3600 hours. In both cases, no complete heat recovery has been installed, since no user is close enough to the site. Only part of the heat is used for gasdrying and space heating on the site. Both engines are able to follow changes in methane concentration automatically. We govern the oxygen concentration of the exhaust gas; the level is adjusted at 2,5% oxygen. It is measured with ZiO2; the governor opens and closes a butterfly valve in the gas supply pipe. 2.4 Gas from thermal gasifiers The quality of gas from thermal biomass gasifiers differs considerably from the above mentioned gases (Table I). The low heating value of the gas is responsible for a heating value of the gas-air-mixture, which is about 25% less than that of the other gases. Therefore an engine running on woodgas has only about 75%–80% of the power it has with natural gas (Fig.I and Fig.II). The low methane number, due to the 10–15% of hydrogen in the gas, has been considered in the design of the M.A.N.-gas engines E 25. Our experience has been gathered in a three years research project together with the Bayerische Landesanstalt für Landtechnik Freising with an updraught gasifier, where we reached 550 running hours, and with an engine—also using gas from an updraught gasfier—, which since June 1980 completely supplies a small saw mill in Morbach with electricity. There is no connection to the public grid and the engine up to now has run 14,000 hours and produced 520,000kWh. The gasifier uses sawdust with about 30% moisture content. The waste water problem, which is a very big one for updraught-gasifiers, in this case has been solved with a small aerobic treatment plant. The gas is cooled and sufficiently cleaned by a huge filter box (2×2×4m), which is filled with sawdust. The electric nominal power output of the engines in both cases is 125kW (80% of natural gas power output). In the sawmill part of the waste heat is used for space heating of the storehouse.

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3. Final remarks a) Generally the technology of engines is ready to run on gaseous fuels from biomass. b) There are many ways to use the power and heat of engines. A lot of types of cogeneration plants, heat pumps, compressors or other machinery can be supplied with power. The technology is known from systems using natural gas and diesel fuel as energy source. c) It is our view, that the remaining technical problems are solvable. The economical problems still seem very big. The costly part beeing on the side of gas production and cleaning, where further progress is necessary. Not much cost reduction can be expected for the power units. d) Application of the technology using gas from biomass will strongly depend on following points: – Biomass must be available cheap or the cost for its deposition should be a credit item. – The cost of conventional energies have to be high. This is the only way, the high capital costs of bio-energy systems can balance the economics against conventional energy supply systems. ORIGIN OF THE MAJOR HEATING VALUE METHANE GAS GASCOMPONENTS RANGE MJ/m3 NUMBER SEWAGE WATER ANAEROBIC DIGESTERS LANDFILLS THERMAL GASIFIERS

CH4, CO2 CH4, CO2

19–21 19–23

130 130

CH4, CO2, N2, O2 H2 CO, CH4, CO2 N2, O2,

12–21 4–6

110–130 70

Table I: Some properties of gases from biomass. ORIGIN OF THE GAS SEWAGE WATER ANAEROBIC DIGESTERS LANDFILLS THERMAL GASIFIERS NATURAL GAS

STOCHIOMETRIC AIR HEATING VALUE OF CONSUMPTION STOCHIOMETRIC m3A/m3G MIXTURE (MJ/m3)

ENGINE POWER OUTPUT (% of NATURAL GAS ENGINES)

5,7

3,2

95

5,7

3,2

95

4,7 1,0

3,1 2,5

91 75

10,0

3,4

100

Table II: Heating value of stochiometric gas-airmixtures and engine power output (natural gas=100%)

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Fig.I: Engines with a cylinder volume VH. Schematic drawing of the volume share of air and fuel. Remember, that about 60% of the wood gas are not burnable.

Fig.II: Engine power output for different fuels and varying λV (=real air volume/stochiometric air volume), setting the diesel engine with λV=1.35 equal to 100%.

AQUATIC BIOMASS PRODUCTION AND PISCICULTURAL WASTE STABILIZATION PRODUCTION DE BIOMASSE AQUATIQUE, EPURATION D’EFFLUENTS DE PISCICULTURE ET ESSAIS D’AQUACULTURE C.LE FUR, C.SIMEON, M.SILHOL, Ph.BLACHIER Commissariat à l’Energie Atomique, IPSN/DPS/GETA BP 171, 30205 Bagnols sur Céze Cedex (France) Résumé Le présent travail entre dans le cadre des recherches entreprises par le Commissariat à l’Energie Atomique sur la valorisation des eaux basse température provenant du complexe industriel Eurodif-Cogema de Pierrelatte. La démarche suivie peut se décomposer en trois parties: – épuration: évaluation des possibilités de dépollution des eaux de rejet d’une anguilliculture par des macrophytes aquatiques (jacinthe d’eau et laitue d’eau). Les abattements observés en 4 jours sont de l’ordre de: NH3: 95%, NO2: 94%, NO3: 47%, PO4: 85%, DCO: 90% – biomasse: détermination de la capacité annuelle de production végétale. Les résultats sont respectivement de 46t/ha/an (M.S.) pour Eichhornia crassipes et 39t pour Pistia stratiotes. – aquaculture: essai de recyclage d’une fraction de la biomasse produite dans l’alimentation de poissons macrophytophages (Tilapia Zillii)

1. INTRODUCTION Les premières recherches du Centre d’Etudes Nucléaires de la Vallée du Rhône sur les possibilités d’utilisation de l’eau de refroidissement de l’usine de séparation isotopique (Eurodif) ont débouché en 1976 sur la construction de 4 ha de serres maraichères pilotes. Depuis 1984, 40ha de serres et 2 ha de pisciculture sont fonctionnels. 2. MATERIEL ET METHODES Les caractéristiques de la station expérimentale utilisée ainsi que les conditions climatiques de la région de Pierrelatte ont déjà été décrites (1), (2). La pisciculture fonctionne avec 55 bassins. Les eaux rési-duaires représentent 1 000m3/h. Seule une

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fraction de l’eau brute (eau de surverse+eau de nettoyage des bassins) alimente les 10 canaux du pilote biomasse. L’essai d’aquaculture s’est déroulé en deux temps. La reproduction a eu lieu dans un canal en terre à une température moyenne de 25°C (système en eau verte). Les fingerlings ont été transférés en aquarium de: 60 1, 600 1 ou 5m3: température régulée à 27°C. 3. EPURATION Expériences de lagunage (été). Deux essais ont été pratiqués dans un canal clos pendant 25 j (A) puis 14 j (B). Les conditions climatiques étaient sensiblement identiques, pH: 7,58 et température de l’eau 17,1°C (A), 20°C (B). Les teneurs de départ en sels dissous en mg/l étaient: (A) NO2-N: 0,14, NO3-N: 2,86, PO4-P: 0,49 Figure 1 (B) NO2-N: 0,11, NO3-N: 1,9, PO4-P: 0,22 L’évolution de l’azote est identique pour (A) et (B). Pour NO absorption importante les 2ers jours (80% à 95%) puis relargage: 0,262mg/l (A); 0,09mg/l (B). Pour NO3 disparition de 95% en 2 à 4 jours respectivement pour (B) et (A) puis relargage: 1,5mg/l (A); 2,18mg/l (B). Le cas du phosphore est plus complexe. Les phénomènes observés sont identiques à ceux décrits par Florentz (3) dans le cas de boues activées. La présence de NO3 bloque (ou freine considérablement) le relargage de P. Ce dernier ne se produit avec ampleur que si la concentration en PO4 est suffisamment faible, ici voisine de 0,2mg/l et en milieu anoxique. Enfin l’absorption de PO4 est d’autant plus rapide que le relargage a été important: 1,2mg/l éliminé totalement en 10 jours (B). Si l’on compare l’entrée, le milieu et la sortie du canal l’importance des relargages de N et P est bien corrélée à l’épaisseur des boues de décantation: intensité plus forte à l’entrée qu’à la sortie. L’importance du rôle des boues sous une couverture de jacinthe est déjà signalée par Mc Vea (4). Expérience en débit régulé (automne). Trois temps de séjour (1–2 et 4j) ont été étudiésdans un canal alimenté en eau brute (eau de surverse essentiellement) par une pompe immergée. Les teneurs moyennes (mg/l) de départ sont: NH3-N=1,44; NO2N=0,078; NO3-N=2,1; PO4-Pt=0,17; D.C.O.=11; NK-N=3,7. Les pourcentages d’abattement obtenus en 4j sont respectivement de: 94%, 98%, 47%, 86%, 90%, 24%. Les phosphates organiques sont inexistants. Toutes les valeurs trouvées sont inférieures aux normes imposées quant aux rejets de l’anguilliculture.

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4. BIOMASSE Les études de production se sont déroulées en 1984 en deux étapes. Du 15 avril au 16 août à partir de rejets fournis par des plants ayant passé l’hiver dehors dans le canal, sous le vent de la serre. Le 16 août la culture a été remplacée par des plants plus petits afin de continuer le protocole d’étude: hauteur des plants 20cm, récolte à 50% suivant l’axe longitudinal du canal lorsque la surface de culture atteignait 100% (120m2) ce qui correspond à une biomasse moyenne de 12kg/m2 (P.H.). La 2ème plantation fut envahie immédiatement par des pucerons (Aphides). La chute de la courbe de production est significative. Figure 2. La production réelle obtenue en 1984 est de 46t/ha/an (M.S.). Les essais 1984 ont été réalisés dans le même canal que celui récolté à 75% en 1983. L’influence du vent de N.W. est soulignée par la chute de production obtenue dans le canal 50% (1983) perte de 25% environ. 5. AQUACULTURE La seule espèce disponible pour les études de nutrition à base de jacinthe était T. zillii. Une soixantaine de poissons d’un poids moyen (p.m.) 25g ont été déversés le 4 juin dans un canal de terre alimenté par l’eau de rejet de l’anguilliculture additionnée d’eau chaude pour maintenir une température moyenne de 25°C (valeurs extrêmes 18°C-30°C). Entre le 19 juin et le 31 août, la production fut supérieure à 12 000 alevins. Les études de nutrition se poursuivent actuellement. Les premières données concernent un aliment du commerce à 27% de proteïnes végétales. Deux lots de 1 100 et 2 500 poissons (p.m. 5g) ont atteint 19g (p.m.) en 2 mois, en bassin de 5m3. Un lot de 25 poissons (p.m. 5g) en aquarium de 60 1 nourris exclusivement avec des feuilles de jacinthes a une croissance nulle au bout de 5 mois: seul le métabolisme de base est assuré.

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FIGURE 2 6. CONCLUSION6. La fiabilité et le dimensionnement d’un ouvrage d’épuration d’eaux résiduaires de pisciculture par un lagunage axé sur l’utilisation de la jacinthe d’eau après décantation (traitement Iaire) nécessite des essais préliminaires dans les conditions climatiques identiques à celles de son lieu d’utilisation (influence de microclimats: rayonnement solaire, température de l’air, vent dominant). Il est nécessaire d’autre part de prévoir un équipement de traitement phytosanitaire. La production moyenne envisageable à Pierrelatte se situe aux alentours de 55t/ha/an (M.S.) pour une culture allant du 15 avril au 15 novembre.

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REFERENCES (1) SIMEON, C., SILHOL, M. and LE FUR, C. (1984). Simultaneous waste water stabilization and macrophyte production for temperate countries. Symposium Energy from biomass and Wastes VIII., 30/01–03/02/84, Lake Buena Vista, Florida. Published by I.G.T., Chicago, Illinois. 163– 192. (2) SIMEON, C., LE FUR, C. and SILHOL, M. (1984). Aquatic biomass and waste treatment. Symp. Bio Energy 84, June 18–21, 1984, Gothenburg, Sweden. (3) FLORENTZ, M. (1982). Contribution à l’élimination du phosphore des eaux usées par voie biologique. Thèse, Univ. Nancy I, France. (4) Mc VEA, C., BOYD, C.E. (1975). Effects of water hyacinth cover on water chemistry, phytoplankton and fish ponds. J. Environ. Qual, 4(3): 375–378.

UNDERSTANDING REFUSE DECOMPOSITION PROCESSES TO IMPROVE LANDFILL GAS ENERGY POTENTIAL D J V CAMPBELL1, E R FIELDING2 and D B ARCHER2 AERE Harwell, Oxfordshire, UK1 and AFRC Food Research Institute, Norwich, UK2 Summary Understanding refuse decomposition processes in landfills is an important prerequisite in achieving maximum yields of abstracted gas for use as an energy resource. Refuse core samples were taken from a number of different landfill sites and incubated in the laboratory. Gas production rates were measured and the samples were analysed chemically and microbiologically. Techniques for the identification and enumeration of methanogenic bacteria in landfill samples are being developed so that, for the first time, data from the field can be compared with information gained in the laboratory on the chemical and microbiological composition of landfill samples. We show that landfill operational methods, particularly those which affect temperature and moisture content of the refuse, influence the development of appropriate microbial communities which, in turn, control the degradation processes.

Introduction Landfill gas is produced by the microbial degradation of organic matter present in deposited wastes in landfill sites. The dramatic increase in interest, in harnessing valuable energy resources, over the last few years, has resulted in the implementation of various gas abstraction and utilisation projects around the world. The current number of operational and proposed projects is probably approaching one hundred, representing a substantial commitment, by many different organisations to the realisation of the potential viability of the technology. This is most notably so in the United States, where the technology was initially developed and has now become a major growth industry(1). Although many of the engineering aspects of gas production are now well understood, less attention has so far been given to understanding the mechanisms of waste decomposition. This understandiang is essential if control of gas production, and/or maximisation of potential yields of gas are to be achieved. The majority of current projects are operating at large sites but future site assessments and evaluations will include an increasingly large number of smaller landfills. These assessments will require a more detailed understanding of waste decomposition processes and the various factors

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which control them, which in turn are related to site operational and management strategies. The development of such strategies, including progressive restoration of sites and controlled waste deposition conditions optimised for gas production and collection, will also limit potential environmental pollution problems associated with leachate production from the site and gas migration/odour release. This paper describes the initial results of a research programme aimed at improving our understanding of waste decomposition processes by carrying out chemical and microbial analyses of waste samples extracted from landfill sites of various types. Experimental procedures Refuse core samples were extracted from known depths of various landfill sites and transferred, in a nitrogen atmosphere, to the laboratory for microbial and chemical analyses. Fractions of each sample were examined for moisture content by air drying at 105°C, with analysis of interstitial fluids obtained by extraction of liquid from the waste using a high speed centrifuge. The organic content (cellulose, lignin) of wastes was determined, and small samples (0.5–1.0kg) incubated under similar field temperature and moisture conditions to measure the rates and yields of gas produced over periods of about 300 days. An integral part of the study is to identify and enumerate the numbers of methanogens present in the samples obtained from the field and to relate the results to chemical measurements. Identification of methanogenic bacteria has been carried out by employing enrichment techniques utilising either trimethylamine, acetate, H2/CO2 or methanol as an energy source. Numbers of methanogens utilising either H2/CO2 or acetate as energy sources have been estimated using ten-fold dilution series methods. An alternative method of estimating the density of methanogenic bacteria is also being developed. This assay uses reversed-phase high performance liquid chromatography with fluorescence detection of coenzyme F420 which is found in all methanogens(2). Results and Discussion Typical chemical analyses carried out on samples from various depths of Site C are presented in Table 1. (Identification of sites has been withheld until the work is completed and the site operators approval has been given)(3). The interstitial fluid analyses are more relevant to an understanding of microbial degradation processes than normal leachate analyses would be, because they indicate the immediate chemical microenvironment within waste where microbial activity is occurring. The observed concentrations of the species found in these samples are typical of those likely to be observed in ‘fresh’. refuse (in the case of Site C the waste is <2 years old). In particular the high Total Organic carbon (TOC) concentrations reflect high organic acid concentrations produced as a result of the initial hydrolysis and anaerobic fermentation of waste. As a consequence leachates with low pH values are produced and these conditions are not usually conducive to rapid methanogenesis.

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Table 1. Chemical analyses for site C core samples at various depths and variation with depth of methanogens growing on H2/CO2 in site C. Interstitial fluids organic content highest Core sample Depth dilution Moisture 1 + pH Cr SO4 · NH4 TOC cellulose Lignin temperature producing (m) content (C) (%) (%) µg/ml µg/ml µg/ml µg/ml methane (%) 0.9 5.9 3.0 5.5 5.0 5.7 7.0 6.2 9.0 6.6 11.0 5.3 12.5 5.6

1900 2100 1900 1050 3500 2700 570

1400 2200 1500 1200 2100 1800 520

570 1100 720 440 3200 2800 200

27,000 34,000 30,000 23,000 47,000 47,000 8,000

10.0 19.2 15.7 14.7 10.0 11.8 11.8

23.0 38.0 15.5 42.1 46.0 13.8 29.0

6.9 7.1 5.4 7.6 8.4 6.5 8.5

28 27 26 24 24 23 18

103 103 104 103 103 101 101

Site C primarily received municipal waste where the organic content would commonly represent about 60% of all waste. However as the analyses in Table 1 indicate substantially lower values were obtained (cellulose and lignin content analyses). Similar observations were found for all samples from other sites at various depths (values were often below 30%). Such low values are a reflection of refuse sampling techniques in the field where extracted material contains a higher percentage of soils and ‘fines’ than is contained in municipal waste as deposited. Drilling methods will frequently push solid matter outside the core sampler and only collect small particle sized material. These factors have important implications for the interpretation of gas production rates and yields obtained from the samples incubated in small jars in the laboratory. The number of methanogens present in the same Site C samples (growing on H2/CO2) are indicated in Table 1. This data when related to measured parameters of moisture content and refuse temperature indicates that increasing values of both are important in achieving good rates of methanogenesis. It is commonly believed that high moisture contents are required for high microbial activity but measured values in Site c samples are little different from ‘typical waste’ (as deposited) moisture contents. It is also surprising that methanogenic activity is significant in a waste environment containing liquid with pH values ranging from 5.5 to 6.5. A number of methanogenic species have been isolated in monoculture from the waste samples from various sites. Isolates of Methanobacterium spp., Methanococcus spp. and Methanosarcina spp. have been obtained. Numbers of methanogens present in samples which grow on H2/CO2 are apparently greater than those which grow on acetate, as shown in Table 2.

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Table 2. Examples of various landfill site conditions and the numbers of methanogens growing on H2/CO2 or acetate.samples (g−1 wet weight) at depths specified. Landfill site (sample depth) Site A (4m) wet waste, <3 years old Site B (7.3m) dry waste, <2 years old Site C (7m) dry waste, <2 years old Site D (4m) wet waste, <3 years old Site E (2–3m) dry waste, >5 years old

Landtillea waste Highest dilution Highest dilution temperature (°C) producing methane from producing methane from H2/CO2 acetate ~40

106

104

32

106

104

24

103

101

20

101

101

23

107

105

The acetate-using methanogenic species are, however, known to aggregate—which would result in an artificially low value for their numbers. An independent estimation of numbers is required before conclusions regarding refuse degradation processes are inferred from relative number of H2/CO2 and acetate—using methanogens. As the data from a variety of landfill types and ages indicates, increasing temperature would seem to be an important parameter for increased microbial activity. It is however not entirely clear to what extent increased waste temperatures result from, or cause, increased activity. It is however apparent that operational methods at a site affect waste temperatures in the early stages after deposition (aerobic decomposition) and one might expect that higher initial waste temperatures are likely to encourage the initiation of more rapid anaerobic degradation processes. The average rates of gas production (in cm3/kg/day) from refuse samples (0.5–1.0kg) incubated in the laboratory under field moisture content and temperature conditions are shown in Table 3. Conclusions Landfill samples which, when incubated in the laboratory, produced methane at the highest rates, contained the highest numbers of methanogenic bacteria. Enhanced microbial activity, which leads to increased methane production rates, is a result of achieving elevated waste temperatures together with controlled moisture content Temperature and moisture content can be controlled in the field by landfill management procedures. For example, elevated temperatures may result not only from prevailing weather conditions but also from the extent of aerobic decomposition of the refuse which is permitted to occur before the onset of anaerobic decomposition. The hydrolytic and fermentative stages of anaerobic digestion are generally less sensitive to perturbations

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such as low pH and low temperature than the methanogenic stage(4) and, consequently, if the methanogenic bacteria are inhibited by low pH or falling temperature, gas yields will be reduced and acid leachates produced. our laboratory ethanogenic stress the importance of optimising the activities of the methanogenic bacteria in landfills and indicate suitable approaches to landfill management which require field assessment.

Table 3. Maximum rates of gas production from incubated samples at depths and refuse age as indicated. Landfill site (sample depth) Site A (refuse >5 yers old) Site A (refuse <3 years old) Site B (refuse <2 years old) Site C (refuse <2 years old) Site D (refuse <3 years old) Site D (refuse >5 years old) Site E (refuse >5 years old)

Maximum gas (CH2+CO2) production rates (cm3 kg−1 day−1)

(7.5m)

300

(4.0m)

2500

(5.0/10m) (7.3m) (9.0m) (0.9m) (5m) (9m) (12.5m) (4m) (16m) (8m) (20m) (2–3m) (5–6m) (8m) (10m)

150 300 400 25 8.9 31 18 42 5 86 127 143 215 6 4

Acknowledgements The Authors wish to acknowledge the Department of the Environment who are funding this project and the assistance of others in the collection and analysis of samples. References 1. “Methane from landfills 1984”. Brochure produced by the American Gas Association, April 1984. Catalogue No. F 00758.

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2. Keltjens, J.T. and Vogels, G.D. 1980. Novel enzymes of methanogens. In: ‘Microbial Growth on E1 Compounds’. pp.152–158. Ed. H. Dalton, Heyden, London. 3. Data taken from a series of site reports currently being prepared for the Department of the Environment. 4. Archer, D.B. 1983 The microbiological basis of process control in methanogenic fermentation of soluble wastes. Enzyme and Microbial Technology 5, p.162–170.

ENVIRONMENT PROTECTION AND ENERGY RECOVERY— DECOMPOSITION GAS FROM THE BERLIN-WANNSEE MUNICIPAL WASTE DISPOSAL SITE J.SCHNEIDER Hahn-Meitner-Institut für Kernforschung Berlin GmbH Glienicker Str. 100, D-1000 Berlin 39, FRG Summary Berlin’s biggest municipal waste disposal site is located in Berlin-Wannsee, close by the Hahn-Meitner-Institut. From 1954 to 1980 more than 11 million tons of household waste were accumulated there. The site covers an area of about 500,000 squaremeters. A former gravel pit has been refilled up to 40 meters above the surrounding ground. The surface of the site is completely covered with a layer of soil. Decomposition gas, a mixture of methane (58%), carbondioxide (40%), and more then three hundred different compounds, is produced in the hill as a product of the chemical and bacteriological decomposition of the organic part of the waste. This combustible gas moves through the surface of the site and into the surrounding soil, causing problems regarding the recultivation of the area, and public safety. A feasibility study, based on data from a pilot gas withdrawal plant, proposes the recovery of the gas by a withdrawal system and it’s utilization in a co-generation plant for the production of electicity and heat. Thus the gas flow across the surface will be reduced by about 70%, and a potential energy source will be used. A co-generation plant, based on internal-combustion engines with a total electric power output of 4,000 kilowatts, and a thermal power output of 6,500 kilowatts is planned to be built in 1985/86.

1. INTRODUCTION Disposal in big landfill sites is the common way of handling municipal waste. The greater part of the waste is garbage, a more or less organic material. When dumping the waste, bacteria immediately start decomposing the organic substances. In modern landfill operation, the waste is compressed by heavy maschines to get an maximum of waste into the limited space. Aerobic bacteria reduce the content of oxygen in the porous media, and due to the compression, no further air can get into the waste. With the decrease in

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oxygen, anaerobic bacteria start decomposition of the organic material. Parallel to the activity of bacteria, different chemical processes take place. After a period of about one year, the processes reach a stable state in the dumped waste, and a major part of the decomposition products are gaseous ones. This gas is a mixture of methane (58%), carbondioxide (40%), hydrogen, nitrogen, and more then three hundred different compounds as impurities. The sum of all impurities is less than 0.1% in weight. Nevertheless, attention has to be paid to the impurities, because some of them are dangerous chemicals, such as vinylchloride, hydrogensulphide, chlorobenzene, etc., and some are corrosive ones. The usual path taken by the gas is through the surface of the landfill into the atmosphere. Gas production is high in newly dumped waste with a decrease to zero within some decades. This leads to an oxygen-free zone inside of the landfill, which extends close to the surface. If waste dumping starts beneath the surrounding ground level, e.g. when a former pit is refilled, the gas moves into the surrounding soil too. Plant and tree roots cannot stand an oxygen-free environment for a long period of time. Therefore, it is hard to recultivate a former landfill, and a lot of trees die if they grow close to a landfill. Methane and some of the impurities are combustible gases. The net caloric value of the gas mixture is about 20,000 kilojoule per cubicmeter. On the one hand, this combustible potential often causes problems regarding landfill operations, and public safety. On the other hand, it could be an additional source of energy. 2. WASTE DISPOSAL SITE The Berlin-Wannsee municipal waste disposal site was closed in 1980. Starting in 1954 a former gravel pit with an average depth of 10 meters was refilled, and a hill with a max. height of 40 meters was formed. The area of the landfill covers 50 hectares (500,000 squaremeters). The total dumping space amounts to about 11 million cubicmeters. Domestic garbage or comparable waste is up to 65% of the content. The landfill site will become a public recreation area in the near future. Therefore, the landfill has been covered with a layer of at least 1 meter of soil, mostly clay and sand. Recultivation work was begun in 1965 and will be completed in 1985.

Figure: The Berlin-Wannsee site from the north.

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The basic area depicted is 1,560 meters by 710 meters. 3. HAHN-MEITNER-INSTITUT The Hahn-Meitner-Intitut (HMI) is located about 400 meters from the landfill. HMI is a scientific institute with some 700 employees. Main work is done in basic research of nuclear physics, and solid state physics. On average the institute’s basic requirement in electric power is 2.5 megawatts. The maximum demand is up to 3.6 megawatts, and the maximum requirement in heatenergy is up to 4 megawatts. During summertime the heat-energy requirement is about 0.5 megawatts. Close to the HMI there are some apartement-houses, which are potential customers in a heat transfer system. 4. GAS WITHDRAWAL PILOT PLANT A first rough calculation of decomposition gas production in the landfill, done in 1980, showed a volume of about 8,000 cubicmeters per hour. This means thermal power of about 40 megawatts, based on 50% of methane in the gas mixture. The energy potential of the landfill is much greater than the requirement of HMI. Therefore, in 1982 a gas withdrawal pilot plant was constructed, to acquire data about the recoverable gas volume, and gas quality, about the efficiency of the withdrawal system, and about the optimal depth, and distance of the vertical suction wells. Additional research has been done in identifying and quantifying the impurities in the gas mixture. 10 gas suction wells have been contructed on a 2.5 hectares section of the landfill by drilling vertical holes of 0.6 meter in diameter, and 12 meters in depth into the waste. A perforated pipe has been put into the center of each hole, and the upmost 4 meters of the hole have been sealed with clay. Pipes made of hard polyethylene connect each suction well with a common blower. The concentration of methane, carbondioxide and oxygen has been measured in each suction well as well as the gas flow. Measurement of methane concentration in the soil has shown the gas flow reduction through the surface. Partially the gas flow decreases to zero. Modell--calculations have been done to assess the time dependent volume of gas production over the next 15 to 20 years, and the recoverable volume of gas.

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Figure: Time dependent volume of recoverable gas (47% methane) and the potential co-generation power, regarding internal-combustion engines. A feasibility study, based on the data from the pilot plant, and taking into account the local conditions has shown, that the gas utilization in a co-generation plant of about 4,000 kilowatts electric power output will be energetically the most useful and economically the best solution to the problem of gas treatment. 5. DECOMPOSITION GAS AS AN ENERGY SOURCE Parallel to the construction of the pilot plant, a pipeline was constructed from the pilot plant to the heating center of the HMI. A former oil-fired boiler was reconstructed with a special burner for landfill gas. Since May 1983 about 65% of HMI’s yearly requirement of heatenergy is produced by burning decomposition gas from the landfill. That means a saving of about 850,000 liters of oil per year. The results of the feasibility study, the positive experience with the pilot plant, and the necessary safety of people and vegetation led to the decision to construct a large-scale decomposition gas withdrawal and treatment system. The Hahn-Meitner-Institut and the local electricity company BEWAG made an agreement to construct and to run a large-scale gas recovery and utilization plant. Detailed engineering is now in progress.

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The decomposition gas will be collected by a system of about 120 vertical gas suction wells with single flow-regulation each to optimize the gas recovery in respect of gas quality and gas flow through the surface. A system of underground pipes will connect the suction wells with the compressor station on the landfill site. The compressed gas will be transported through the existing pipeline to the HMI site. There, a co-generation power plant will be constructed, based on 3 to 5 internal-combustion engines. The total output of the plant will be 4,000 kilowatts electric and 6,500 kilowatts thermal power. The electric power will be generated by synchronousgenerators at 10,000 volts, and fed into the HMI, and into the public grid. The thermal power will be used as much as possible in the buildings of the HMI and in the apartement-houses in the neighbourhood of the HMI. Regarding to the environment protection aims on the landfill site, restricted levels in noise and flue-gas emission of the power plant have been formulated by HMI and BEWAG. This led e.g. to the necessity of technically reducing the nitrogenmonoxide and the nitrogendioxide in the flue--gas of the co-generation plant. Today calculations show a necessary investment of about 15 million Deutsch Marks for the construction of the gas recovery system and co-generation plant. The repaymenttime for that money will be at least 15 years. The actual timetable is as follows:—construction commencing in autumn of 1985,— start of operation in winter 1986/87.

PRODUCT DEVELOPMENT NEEDS OF WASTE MANAGEMENT P.VILPPUNEN Energy Laboratory, University of Oulu, Finland Summary The objective of the research “Product development needs of the waste management” is to find out R&D needs by which the factors that prevent the energy economical utilization of municipal waste can be diminished. The partial objective is to develope by a separation-handling system producing refuse derived fuel. The system is based on two-phase separation of municipal waste: at source and centralized, as well as on the refining of the separated combustible fraction of the waste into fuel. The research includes: * deepening prestudy * selection of alternative separation-handling methods * technical-economical comparison of the different choices * spesification of the selected method and product development basis. The method can be used when developing the energy economical utilization of solid municipal waste in the energy and waste management of the community and also when developing the recovery of the raw materials in the refuse at source or in centralized separation plant.

1. BACKROUND The energy economical utilization research of waste in Finland consists mainly of the collection of experiences of municipal waste used in other countries. In addition has been studied the suitability of fluidised bed technology and the research method needed for the quantity and quality study of the waste. The preliminary results show that the separation of the combustible and other fractions from the municipal waste significantly influence in the energy economical possibilities of utilizing the waste. The sorted municipal waste enables the preparation of more homogeneous waste fuel and so it increases the possobilities to use the waste with other combustibles in ordinary burning plants. 2. OBJECTIVE The objective of the researh is the selection of a waste fuel producing separation and handling system based on technical-economical study. The system is founded on two-

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phase separation of municipal waste: at source and centralized, as well as on the refinig of the separated combustible fraction of the waste into fuel. With the system is achieved the production of waste fuel which could be used as wide as possible in the existing heating centres of the communities and the industry.

Picture 1. Separation-handling system as a part of energy economical utilization of the solid municipal waste. 3. RESEARCH REALIZATION The research is divided into following partial stages: 1) deepening prestudy 2) selection of alternative separation-handling methods 3) technical-economical comparison of the different choices. In the comparison are taken into account: * technical conditions * economical conditions * environmental conditions * public opinion conditions 4) specification of the selected method and product development basis.

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1) Prestudy In the prestudy is analized the following information: * quantity and quality of the waste (household, office, commercial and similar industrial waste) by considering for example the different structure of the communities, year season and the changes caused by consumption variations * selection of different locations 500000h., enough waste for burning even as unique fuel in a waste combustion plant 100000h., central heating plants burning peat and many solid fuel district heating plants in the surrounding communities—waste fuel transportation to the vicinity.

Dispersed dwellings or small towns where are possibilities for the use of refuse derived fuel. 2) Selection of alternative separation-handling methods For the basic alternatives of comparison are chosen two systems in which one separates the waste already at source (for example the households) wet food and similar wastes from dry combustible and recoverable waste. The other basic alternative is the existing system without separation at source. 3) Technical-economical comparison of the different choices The basic factors are technical, economical, environmental and the public opinion conditions and demands. The comparison is done for * I-stage i.e. separation at source * handling the separated-unseparated waste before II-stage * II-stage i.e. centralized separation handling * production and utilization of waste fuel. On the ground of the comparison is chosen a method to be developed for two-phase waste fuel producing separation-handling system. 4) Specification of the selected method and product development basis The selected method is specified for example by adjusting the necessary prehandling stages. At the same time are determined those changes needed when using the method in different kind of communities (100000–500000h. dispersed dwellings). 4. RESULT UTILIZATION Research result

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1) Application area * Energy economical use of solid municipal waste in the energy and waste management of the communities (waste fuel production). * Raw material recovery from waste at source and with centralized separation. 2) Applying method * Technical-economical estimation of the method (product proposal) for further development to the manufactures. 3) Users * The authorities directly or indirectly responsable of the waste and energy management in the communities, designers, manufacturers and industry. 4) Energy economical signifance * The method increases directly the possibilities to use native solid fuels (wood, peat and municipal waste) in combination. * Indirectly the method increases the energy quantity recovered from organic waste by anaerobic digestion (the separation of organic matter at source improves the base for biogas production). 5) Other significances * The method decreases the charge for environmet caused by incineration (more homogeneous fuel—less emissions) * The method increases the recovery degree of the recoverably raw materials (twophase separation) * The method improves the realization of the long term planning of the waste management (for example decreases the need of landfills).

SEWAGE SLUDGE AS ENERGY SOURCE H.P.ZWIEFELHOFER UTB UMWELTTECHNIK BUCHS AG, 9470 Buchs/SG Switzerland Summary Practical experiences with newly developed sewage sludge treatment processes like pre-pasteurization or aerobic-thermophilic pre-treatment, followed by anaerobic-mesophilic stabilization were studied at full scale operation. The thermal conditioning effect of pre-pasteurization and, in the case of aerobic-thermo-philic pre-treatment, the combined effect of temperature, mechanical and bacteriological hydrolysis have proven to be of great cost-saving on sludge treatment plants. Intensified anaerobicmesophilic digestion and the exothermic thermal energy-production in the case of the aerobic-thermophilic pre-treatment minimized energy costs and allow safe sludge recycling by agricultural use.

1. INTRODUCTION In Switzerland each year over two million cubic meters sewage sludge are disposed of in land application for agriculture. At an average dry solids content of about 6.4%, of which about 42% are volatile solids (VS), a representive digested sludge contains the following fertilizing matter per ton of dry matter: 40kg (N), 70kg (P2O5), 3kg (K2O), 70kg (Ca), 7kg (Mg) The Swiss Federal Research Institute for Agricultural Chemistry and Environmental Hygiene (Liebefeld/Berne) calculates the sludge’s value as fertilizer at an average of SFr. 8.40/m3 liquid sludge or about 20 Million Sfr. (1$=2.8 SFr.) (1). These figures show why the Swiss Authorities encourage development of new technologies and processes to condition and hygienize sewage sludge; thus the land recycling of this product under controlled conditions is a declared aim of Swiss environmental policy. Stringent Swiss laws assure the protection of soil, humans and cattle. The Swiss Ordinanance of 8 April 1981, concerning the disposal of sewage sludge for agriculture, dictates conditioning and hygienization technologies, process minimum requirements, limits for hygiene, maximum heavy metal contents, method, quantity and time for using sludge in agriculture. 2. UTB TWO-STAGE TREATMENT: 1st Stage Aerobic-thermophilic Conditioning-and Hygienization, 2nd Stage AnaerobicMesophilic Stabilization

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This process was developed and first applied at the sewage treatment plant of Wartau/St. Gallen (7’000 population equivalents). The Wartau plant was commissioned in 1978 as a mechanical/biological/chemical (phosphate-precipitation) plant. To stabilize the sewage sludge, a conventional anaerobic digestion was installed. To hygienize digested sludge, a pasteurization plant was built but never used. Consequently, farmers were very reluctant to use the waste-sludge since it was not hygienized. Early in 1982 it was decided to install an aerobic-thermophilic sewage sludge conditioning/hygienization plant (AEROTHERM) as a process-stage in sludge treatment prior to the existing anaerobic digestion. This decision was taken, after the perfoirmance and security of the process had been demonstrated to the responsible authorities in a two year test run.

Description of the AEROTHERM Process. Raw sludge from primary clarifiers and the biological and chemical secondary stage treatment (phosphate-elimination) is thickened statically (1) from 98–99% water content to 95–97% and pumped (3) through a comminutor (2), in which textiles, Q-tips, plastic-parts, etc., which have passed the barscreen at the entry of the sewage treatment plant, are reduced to acceptable particle sizes, into the aerobic-thermophilic conditioning/hygienization plant (AEROTHERM). Sludge is mixed very intensively in the AEROTHERM-reactor (7) and air/oxygen is introduced in a specially designed injector (9). In the well insulated reactor, aerobic microorganisms digest organic matter with simultaneous heat generation. This exothermic reaction heats the reactor content up to a temperature of over 60°C. Temperature rise varies between 0.5 to 1.5°C per hour, depending on several parameters such as volatile solids concentration, pH, etc.. The shorter the aeration time, the lower is the elctrical energy consumption. Biogas, produced in the following anaerobic digestor, is used in gas-burners and/or gas-engines to the the aerobic sludge through a heat-exchanger (12). Excess heat, not necessary for the operation of the above anaerobic mesophilic stage (working at about 32–40°C) is recovered by means of a sludge/sludge heat exchanger that preheats the raw sludge (4).

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After 24 hours retention time at 60°C in the AEROTHERM-reactor, the sludge is mechanically, thermally and bacteriologically conditioned, sludge is pumped (5) into the anaerobic digestor (13). Anaerobic bacteria in the digestor further digest volatile solids and produce biogas. The sludge is further stabilized: salmonella, worm eggs, enterobacteriacea are destroyed; and the reinfection of sludge with salmonella, much feared with pasteurization plants, is impossible. The hydrolizing effect of the AEROTHERM-stage and the resulting performance of the 2nd (anaerobic) stage summarized lead to overall reduction of investment and operating costs (2). 3. SUMMARY OF THE PRACTICAL EXPERIENCES SINCE 1982 Effects on Hygiene. The process above guarantees results within the limits of the Swiss Federal Ordinance on Sewage Sludge of the 8 April 1981 regarding hygiene (max. 100 enterobacteriacea per gram at the point and time of transfer to the transport bringing it to farmers and no reinfection capacity). Tests (2) have proven the safety of the process with regard to the destruction of enterobacteriacea, salmonella (3) and worm eggs (4). Effects on energy balance. The biological heat-generation in the aerobic system substantially contributes to a favourable energy balance for the sewage treatment plant as a whole. For every kWh electrical power input, the heat-output is approx. 3kWh. Total energy costs being approx. 3–5–12kWh/m3 raw sludge at 4% TS, depending on retention time and plant size. For circumstances existing prior 1980 at the Wartau plant, a very unfavourable relation between raw sludge and the quantity to heat lost from the digestors was found, since the whole lower part of the digestor had been placed without insulation in a ground water flow. Thermal hygienization of the sludge would have resulted in a massive increase of fuel consumption. However, with the AEROTHERM-process, the total fuel oil consumption including heating for the building and warm water production was reduced from ca. 8t/year (without hygienization) down to ca. 3t/year (with hygienization). An additional measure which will be taken soon is the installation of a gas-motor capable of waste heat recovery. Effects on consolidation, dewaterability. Due to the conditioning of the sludge before its anaerobic digestion, consolidation and dewatering properties were significantly improved. Dry substance contents of 12–20%, compared with 6–8% in earlier years, in the storage tank, are now standard. Current structure is responsible for maintained “pumpability”. At Wartau this effect brought a reduction of over 50% of the volume of sludge to be disposed of. Consequently, there are no more problems with sludge disposal even in winter since the former digestor II now serves as a storage/consolidation tank. Tests on site have also shown that the perfomance of mechanical dewatering equipment has improved. Relatively high dry solid contents can be reached. Using polyelectrolyte (PE), 35–40% TS were reached with belt filters and 48–53% TS in filter presses. This means an increase in dry solids content of about 5–10 percentage-points compared to average digested sewage sludge and a considerable reduction in polyelectrolyte consumption per ton of dewatered dry solids.

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4. FINAL CONCLUSIONS The UTB-AEROTHERM process is presently used at five sewage treatment works. By the end; of 1985, twelve plants will be in use with capacities from 4–140m3 sludge per day. Further plants in Europe are under construction. So far, the positive results on the first plant (Wartau) have been wholly confirmed on the other plants and by a process evaluation on the Unterterzen plant by the Department f or Technical Biology of the Swiss Federal Institute for Water Resources and Water Pollution Control, Dübendorf (EAWAG). In most projects for performance-improvement or adaption of liquid sludge treatment facilities to meet new regulations, the aerobic-thermophilic process is now considered as the most cost/effective alternative. References (1) FURRER, O., Agricultural use of sewage sludge. PHOENIX 2/1983 (2) ZWIEFELHOFER, H.P., IWTUS-Symposium 1984 at Ittingen/Switzerland (3) Institute for Veterinary-Medicine. University of Zürich/Switzerland (4) Institute for Parasitology. University of Zürich/Switzerland

FLAME DEVELOPMENT IN SPARKIGNITION ENGINES BURNING LEAN METHANOL MIXTURES R A Johns and A W E Henham University of Surrey, Guildford, England Summary Small diesel engines may be readily converted to spark-ignition to burn alcohols. The highly turbulent pre-chambers in these engines are ideally suited to burning lean mixtures, thereby improving fuel economy whilst reducing exhaust emissions. This paper describes the application of a diagnostic engine computer combustion model to the analysis of flame development in such an engine. The results exhibit characteristic features of flame development; a period of heat transfer to the unburnt gas between the spark plug electrodes, Instantaneous self-ignition and a period of decelerating flame propagation. These characteristics were modelled for use in engine computer simulations.

1. INTRODUCTION Alcohol fuels, either methanol, produced from indigenous deposits of natural gas, or ethanol, produced from biomass, offer attractive alternative fuels to oil. With RON of 114 and 111 respectively, they are well suited as fuels for high compression spark-ignition engines. Evaluation programmes are already in progress; mainly with captive vehicle fleets which are largely independent of extensive fuel distribution systems. On the other hand, both these oxygenates have extremely low cetane numbers and are, therefore, difficult to ignite by compression ignition, particularly at loads below 25% of the engine rating. The small stationary diesel engines, in common use for power generation and pumping in remote areas may, however, be easily converted to spark ignition to burn the locally produced alcohol fuels. The high compression ratios and highly turbulent combustion chambers in these engines are ideal for the combustion of lean alcohol mixtures. Such an engine, a single cylinder 7.5kW diesel with a spherical pre-chamber, was converted to spark-ignition and performance tests with lean methanol mixtures indicated that stable operation could be extended further into the lean burning regime than was possible with the baseline fuel, isooctane (1). Analysis of the cylinder pressure readings using a computer engine combustion model showed the existence of four different types of burning cyles (2) which included cycles with partial burning. The period of initial flame development was found to have a significant influence on subsequent flame development. Complete combustion with high maximum burning rates

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resulted from a short period of flame development, whereas the partial burning cycles were a consequence of a long flame development period. The purpose of this work was to apply the engine computer combustion model in a diagnostic manner to analyse the experimentally acquired cylinder pressure data to identify the characteristic features of flame development in spark-ignited lean methanol mixtures. 2. EXPERIMENTATION The conversion of the diesel engine to an alcohol fuelled spark-ignition engine and a description of the associated data acquisition system is given in reference 1. Experimental pressure data were analysed using the shifting equilibrium combustion model of Krieger and Borman, with heat transfer rates determined from the empirical relationship of Woschni, as detailed in reference 2. Here the combustion chamber is divided into two zones; a burnt zone containing a uniform composition of products and an unburnt zone containing a homogeneous mixture of reactants. The First Law of Thermodynamics is applied to each zone at 1° intervals of crank angle to compute a mass of reactants burnt that is just sufficient to cause the measured pressure rise. The flame propagation velocity was computed assuming a spherical flame front propagating from the ignition source and intersecting the cylinder geometry. The laminar flame speed was calculated from the computed adiabatic flame temperature and unburnt gas temperature using the empirical relationship of Koda et al (3). Corrections were included for lean equivalence ratios and for cylinder pressure:

The engine was run on M100 fuel at 1000rev/min with equivalence ratios in the range 0.61<Φ<1.01. and an airflow of 11.9kg/h. 3. ANALYSIS The computed curves of propagation velocity and mass fraction burnt during initial flame development exhibited four distinct characteristic features: A. A period of heat transfer immediately following spark discharge during which the cylindrical column of gas between the electrodes was heated to the self-ignition temperature. B. Instantaneous self-ignition of the cylindrical column with a correspondingly high instantaneous value of flame progagation velocity. C. A period during which the flame kernel was consolidated and established. Here unburnt gas was entrained into the small expanding kernel with a cooling action that resulted in a decrease in the value of propagation velocity with time. Quenching could occur if the entrainment rate continuously exceeded the burning rate. D. Establishment of a self-propagating turbulent flame with an accelerating flame front.

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Mean values of the time elapsed from spark discharge to ignition of an unburnt volume of mixture between the spark plug electrodes, together with the associated standard deviation in time plotted as bars on the mean values are shown in Fig 1. The heat transfer period increased with an inverse power law as the mixture strength was reduced, with the index being a function of compression ratio: τht/τhtΦ=1=(SL/SLΦ=1)0.22ξ−2.54. Cycle-to-cycle variations in the heat transfer period increased with reductions in equivalence ratio although less markedly with the higher compression ratio. The high instantaneous value of flame propagation velocity, resulting from the ‘explosion’ of the unburnt gas between the electrodes (Fig 2) varied from a mean value of 35ms−1 with stoichiometric mixtures to 18ms−1 with mixture strengths approaching the lean misfire limit. The compression ratio had little influence on this parameter and the results indicated a relationship of the form:

where a=18m/s, b=6s/m and n=2. Immediately after self-ignition the flame front decelerates as cooler unburnt gas is entrained into the developing kernel until a turbulence controlled flame propagation is established. The computed results were in general agreement with Chiomiak (4), who reported an inverse relationship between propagation velocity and time for the period immediately following self-ignition. Cycle-to-cycle variations in the index were significant, particularly at the higher compression ratio; typically the cyclic dispersion was 0.32 at an equivalence ratio of 0.81. The flame kernel may be considered to be established when the flame front accelerates immediately following the period of decreasing propagation velocity. Generally the total period between spark discharge and a positive rate of change of propagation velocity increased with reductions in mixture strength. With stoichiometric mixtures the onset of an accelerating flame front was clearly discernable but with lean mixtures it was difficult to specify the exact time at which the flame could be said to be established. Typically at an equivalence ratio of 0.69 the propagation acceleration varied between positive and negative values from 5° BTDC to 7° ATDC. A comparison between the period of flame establishment, defined by dSp/dt becoming positive, and the time elapsed from spark discharge to a mass fraction burnt of 1% is shown in Fig 3, with a resolution of 1°CA superimposed. The cyclic dispersions in propagation acceleration and in a mass fraction burnt of 1% is given in table I. For equivalence ratios between 0.8 and 1.0 there was good agreement between dSp/dt becoming positive and the corresponding time to 1% mass burnt. The problem of ascertaining flame establishment from dSp/dt becoming positive became increasingly more difficult with equivalence ratios less than 0.8. For this reason a definition of 1% burnt was adopted. The variation in this period with laminar flame speed is shown in Fig 4. The relationship took the form of a power law: τ1%/τ1%Φ=1=(SL/SLΦ=1)n where n was evaluated as a function of compression ratio:

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n=0.22 ξ−3.0

Fig.1 Variation in heat transfer period with laminar flame speed.

Fig.2 Variation in instantaneous propagation velocity with laminar flame speed.

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Fig.3 Comparison of flame establishment definitions.

Fig.4 Variation in flame establishment period with laminar flame speed. Table I: Cyclic dispersion in flame establishment period. Compression ratio Equivalence ratio dSp/dt+ve °CA 1% burnt °CA mean dispersion mean dispersion 9:1

0.65 11.1

0.297 23.3

0.155

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0.69 12.1 0.74 8.2 0.81 9.8 0.94 5.9 1.01 7.3 0.56 8.9 0.61 7.6 0.77 8.2 0.81 6.4 0.97 8.1

0.256 0.280 0.245 0.136 0.178 0.236 0.276 0.171 0.203 0.160

20.6 16.0 11.9 6.6 6.8 16.6 15.9 10.0 8.8 8.4

0.155 0.156 0.160 0.152 0.162 0.157 0.157 0.160 0.159 0.167

4. CONCLUSIONS The period of flame establishment in the divided-chamber methanol engine exhibited four characteristic features which were related to the laminar flame speed and could be modelled for use in engine computer simulations. Flame establishment was difficult to ascertain in terms of the onset of a propagation acceleration with lean mixtures below an equivalence ratio of 0.8 and a definition in terms of a mass fraction burnt of 1% was considered to be more definitive. This technique of employing diagnostic engine combustion models provides an inexpensive method of analysing engine combustion performance with alternative fuels. REFERENCES (1) Johns RA and Henham AWE, The performance of a divided chamber single cylinder engine with lean methanol mixtures, Conference on small engines and their fuels for developing countries, University of Reading, September 1984. (2) Johns RA, The analysis of the combustion of methanol in the lean-burning regime using an engine combustion model, VIth International Symposium on Alcohol Fuel Technology, Ottawa, May 1984. (3) Koda S et al, Burning characteristics of methanol—water—air mixtures in a constant volume combustion vessel, Combustion and Flame 46: 17–28. (4) Chomiak J, Flame development from an ignition kernel laminar and turbulent homogeneous mixtures, 17th Symposium on Combustion, pp 255–263, 1978.

RUBBER SEED OIL FOR DIESEL ENGINES IN SRI LANKA P.D.DUNN and E.D.I.H.PERERA Department of Engineering, University of Reading, U.K. Summary In addition to rubber latex very considerable quantities of rubber seed are also produced in the Sri Lankan rubber estates. A small proportion of the seed is now used in the paint and soap industry, but most of the crop is wasted. This paper considers the possible application of oil, extracted from the seed, for use as an alternative to diesel oil in the rubber industry. The relevant fuel properties are presented and compared with those for diesel oil. The results of some primary engine tests using pure rubber seed oil (RSO) and blends with diesel oil are also given.

1. INTRODUCTION 1.1 Rubber Seed Oil as a Natural Resource Sri Lanka is the fourth largest producer of natural rubber (Hevea Braciliensis). Several attempts have been made during the last few decades to exploit the thousands of tonnes of rubber seed which are allowed to go to waste on rubber estates. It is only recently that some measure of success has been achieved. The main commercial product obtainable from the rubber seed is its oil. It has been estimated that about 4,500 tonnes of rubber seed oil (RSO) and 7,000 tonnes of high protein rubber seed cake may be obtained annually from the 250,000 acres of rubber land from which seed could be readily harvested. The average crop of seed is around one tonne for ten acres and the yield of oil is 17% by weight. (1) At present the main potential use of RSO in Sri Lanka is in the paint industry. Currently it is used for the production of alkyd resins used in emulsion paints. RSO has also been considered as a substitute for coconut oil in the soap industry. (2) The largest percentage of the resource however has not been utilized. Since the rubber seed is a byproduct of the natural rubber plantation industry, the cost of production of oil seed is negligible. The inedible RSO can easily be extracted from the seeds and this paper considers the possible application of this oil as a fuel for diesel engines. RSO is an oil having a composition somewhat similar to linseed oil (Table I).

Table I—Composition of RSO and Linseed Oil Acid Carbon Atoms Double Bonds RSO Linseed Oil Palmatic

16

0

11

5

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Stearic Oleic Linoleic Linolenic

18 18 18 18

1330

0 1 2 3

12 17 36 24

2 20 18 55

Oil is obtained from the rubber seed either by an expeller process or by a solvent extraction process. The yield of oil from rubber seed is somewhat variable and depends mainly on the time factor between seed fall and collection, and drying and expressing. Rubber seed cake, left after the extraction of oil from the rubber seed kernel, could be used as an animal feed or as a nitrogenous fertilizer. (2) 1.2 Collection, Storage and Milling of Rubber Seeds One of the most important items that could influence the feasibility of extracting RSO economically is the cost of seed collection. This in turn is controlled by many factors such as seasonal variation in total seed fall, presence of surface vegetation cover making collection difficult, topography of the estate and the type of labour employed for collection. Under the climatic conditions prevailing in Sri Lanka it is desirable to ensure that seed collection takes place on an average of once in four days and at regular intervals throughout the period of seed fall. (2) Since fresh seeds contain about 35% moisture, it is not possible to store them in this condition without rapid deterioration. The seeds become mouldy, susceptible to insect attack and permit a rapid increase in free fatty acid content due to an enzymic action. (2) Rubber seeds which cannot be processed immediately should be sun-dried to reduce the moisture content. Another method of treatment is to heat the seeds for over an hour at a temperature of 120°C. (2) The rubber producing areas are rather scattered and a new large central factory for processing the entire crop of rubber seed would be impracticable in view of the transport difficulties. Therefore any new factories for milling should be in the form of small units sited in the rubber growing areas themselves. RSO may be extracted in existing oil mills, or alternatively in small units attached to pale crepe factories. The use of an expeller or a hydraulic screw press have been recommended for such small operations under estate conditions. The seeds are disintegrated and cooked before passing through an expeller or a press. The harvest is seasonal, the greater proportion of the crop falling within a short period, usually during the months of July to September. The secondary seed fall which occurs at the commencement of the winter season, January—February, is less important compared with the main crop. Hence storage of the oil or seed will be required. 1.3 Aim of the Project The main aim of this study is to evaluate the suitability of RSO as a diesel fuel substitute for engines used in the rubber plantation industry. There are a considerable number of diesel engines (both stationary and mobile) used in the rubber plantation industry itself. Large stationary diesel engines are employed in non-electricity grid connected rubber estates to drive a horizontal shaft through which the power for milling coagulated rubber

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is supplied to different types of rollers. Diesel tractors are used to transport rubber latex and rubber products in and out from the main factory. Therefore a large proportion of the power requirement of the rubber plantation industry is generated from diesel fuel. The present work on RSO concentrates on its potential as a fuel for diesel engines, particularly used in the rubber plantation industry in Sri Lanka. An advantage of this application is that any special engine maintenance operation requirement due to the use of RSO can be ensured since only in-house staff will be involved. 2. FUEL RELATED PROPERTIES OF RSO The following fuel properties of RSO were measured and the results are given in Table II. ASTM specification for No. 2 diesel oil are also given in Table II for comparison. It can be seen that the cetane rating of RSO is close to ASTM minimum of 40 for No. 2 diesel oil.

Table II—Fuel Properties of RSO Fuel Property

RSO

ASTM Specif ications for No. 2 Diesel Oil

Cetane No. Viscosity C.st @ 40°C Density g cm−3 @ 20°C Heat value MJ kg−1 Distillation temp. C (90% point) Pour point, °C Cloud point, °C

40 29 0.92 39 Cracking

40 (min.) 1.9–4.1 – – 282 (min.), 338 (max.)

+9.0 +13.0

Carbon residue % Ash by weight % Sulphur, copper corrosion Sulphur, by weight % Water and sediment

1.3 0.54 la 0.003 0.05

– 6°C above 1/10 percentile minimum ambient temperature 0.35 (max.) 0.01 (max.) No. 3 (max.) 0.5 (max.) 0.05 (max.)

RSO is extremely viscous with viscosity of ten times greater than the viscosity of No. 2 diesel at 40°C. Variations of the viscosity of RSO and blends of RSO with diesel oil with temperature are shown in fig. 1. When ASTM Test D 86 was used to distil RSO, it cracked into a two-phase distillate, showing its thermal instability. Comparisons with properties of No. 2 diesel oil indicate that RSO meets the ASTM limits for total and active sulphur, water and sediment and fails to meet the ASTM limits for ash content, carbon residue, reflecting the crude nature of the sample tested. (Sample was not refined). RSO has higher cloud and pour points than diesel fuel. These low temperature characteristics are not important for tropical countries like Sri Lanka where the ambient temperature hardly drops below 20C.

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It can be seen that the heating value of RSO is 87% of diesel oil on a mass basis and 94% on a volume basis at 25C, since RSO is slightly heavier than diesel oil. 3. ENGINE TESTS The engine tested was a single cylinder, four stroke, air cooled, naturally aspirated Petter (Model AC 1) engine giving 4.9kW (6.5php) at 3600rev/min. The slightly unusual feature of the engine is its Lavona air cell combustion chamber. Tests were carried out at different loads with the engine running on diesel oil, RSO and blends of RSO with diesel oil at constant speed setting of 2600 rev/min. Three blends were used having 25%, 50% and 75% of RSO by volume. Figure 2 shows the variation of specific fuel consumption (SFC), brake power (BP), brake thermal efficiency and exhaust temperature with brake mean effective pressure (BMEP) for the fuels diesel, RSO and corn oil and 2600rev/min. As far as the above performance parameters are concerned the corresponding values for RSO and corn oil show a considerable similarity to those of diesel oil. It can be seen that the SFC is slightly higher for vegetable oils due to their low heating value. In most cases the thermal efficiency for vegetable oils is slightly higher. Our results do not show a significant difference in exhaust temperature, although Sims (1981) and Imato (1980) reported higher exhaust temperatures with vegetable oils. Plots of variation of SFC, thermal efficiency and BP with BMEP obtained with the blends of RSO and diesel oil were used to produce fig. 3. This shows the variation of SFC, thermal efficiency and BP with the percentage of RSO in a RSO/diesel oil blend at 2600rev/min. There has been a general trend of a slight increase in SFC and thermal efficiency as the percentage of RSO is increased. 4. CONCLUSION Among the fuel properties tested, higher viscosity of RSO must be considered as the crucial factor, since high viscosity of vegetable oil is known to affect the characteristics of the fuel spray and thereby cause a number of detrimental effects such as rapid coking up of the injector nozzle. From the test results it is apparent that RSO and blends of RSO with diesel oil behave like petroleum-based diesel oil in short-term engine performance tests. SFC is higher with RSO, reflecting its lower calorific value than diesel oil. The thermal efficiency, however, is slightly higher with RSO. Although no significant increase in exhaust temperatures with RSO was observed, higher carbon monoxide emissions are evident. Carbon deposits on engine components with RSO were found to be heavier than those with diesel oil.

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ACKNOWLEDGEMENTS The authors gratefully acknowledge the authorities at BP Research Centre, Sunbury-onThames, UK, particularly Mr. E.Marshall who determined most of the fuel properties of RSO presented in this paper. FIGURES 1. Viscosity Vs temperature for RSO and diesel blends 2. Performance of diesel, RSO and corn oil at 2600rev/min 3. Variation of SFC, thermal efficiency (TE) and BP with composition of the blends at 2600rev/min

REFERENCES (1) NADARAJAH, M., ABEYSINGHE, A., DAYARATNE, W.C. and THARMALINGAM, R. (1973). The potential of rubber seed collection and its utilisation in Sri Lanka. Paper pub. by Ministry of Plantation. (2) NADARAJAPILLEV, N. and WIJEWANTHA, R.T. (1967). Productivity potential of rubber seed. Rubber Research Institute of Ceylon bulletin, vol. 2, nos. 1 & 2, pp 8–12. (3) PERERA, E.D.I.H. (1984). An initial appraisal of the potential of rubber seed oil as a fuel for diesel engines with specific relation to Sri Lanka. M.Sc. thesis, University of Reading, UK.

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Fig. 1

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Rubber seed oil for diesel engines in Sri Lanka

Fig. 2

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Energy from biomass

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NEW DIRECT INJECTION DIESEL ENGINE DEVELOPMENT FOR USING VEGETABLE OIL AS A FUEL K.Elsbett, G.Elsbett, L.Elsbett Elsbett-Konstruktion Summary A new engine technology is described for the use of vegetable oil as a fuel. The oil can be used as it is extracted and cleaned without any further processing. Large scale consumption requires large scale production of vegetable oils. An example is shown describing possibilities for the recultivation of desert areas. Under these conditions food production for men and vegetable oil fuel production for the engine are in no way a contradiction. In the contrary the production of vegetable oil fuel can be a basis to in future solve the problems with starvation, environment and unemployment.

1. INTRODUCTION The preprogrammed explosion of human population goes together with three disasters: lack of food, environmental problems, unemployment. If we cannot care for considerable improvements in technology and economy, countless armed conflicts between nations and social classes are unavoidable. The constant trend of the increase in population has only been possible due to the unscrupulous depletion of the earth’s resources by technical means. This trend has led to an intercine war against the hydrocarbon resources of the earth, no matter whether fossil fuels or the expansion of the deserts is concerned. The withdrawal of fossil fuels from the earth and oxygen from the air produces 26 billion tons carbon dioxid per year. This decisive interference in the geological development can only be justified if this huge mass of CO2 is used to create the preconditions for life in future. This task can only be accomplished if the withdrawal of fossil resources and the production of biomass resources in form of plants and humus are equilibrated. Vertile soil instead of deserts is the most appropriate measure against starvation, unemployment and damaged environment. Humus on the surface of the earth is even better than coal and crude oil below.

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2. THE DUOTHERM ENGINE FOR VEGETABLE OIL FUEL Per liter, vegetable oil fuel has almost the same heat value as gasoline. It has the important advantage to be suitable for d.i. diesel engines which are superior in efficiency to other engines in a ratio of 40 to 27%. This fact results in a lower fuel consumption of 1:1.5 (refer to Fig. 1). If gasoline is supplied by the oil refinery for 0.80DM/L, vegetable oil fuel could even cost 1.20DM/L to keep the fuel cost the same. As all by-products of the vegetable oil fuel production can be sold at a good price, already today the gradual change to the use of vegetable oil as a fuel can be considered as a solution for the present agricultural surpluses of the EC. If for rapeseeds or sunflowers a yield of 3 tons/ha of oil fruits is assumed instead of 5 tons/ha of grain, the oil fruits must yield 750DM/ton instead of 450DM/ton as it is the case for grain. If 40% of the yield are used as engine fuel for 1.20DM/L and 60% as feeding stuff for 800DM/ton this will bring in 440DM for oil and 480DM/ton for the oil cake. These are 920DM/ton, i.e. 170DM/ton remain for marketing. Fig. 2 shows the cross section of the vegetable oil fuel engine equipped with the Duotherm combustion system according to Fig. 1. The most important characteristics are described in the following: 1. The whole engine is now made in iron and steel. Neither aluminium nor ceramics nor expensive electronics are required. The injection system is integrated in the cylinder head, anyway only three instead of five cylinders have to be operated. Thus the vegetable oil fuel engine is in design not more expensive than the gasoline engine. 2. As the combustion system is heat insulated, the piston design is so that hardly any heat flows to the cylinder. Therefore the articulated cast-iron piston has its largest diameter and contact area to the liner already above the piston rings. Consequently the rings are protected from the combustion gases and leftovers. 3. A single jet injection system is used with a pintle nozzle instead of a hole-type nozzle. This is required for the operation on vegetable oil fuel due to the risk of nozzle clogging. 4. With the Duotherm combustion the heat remains in the working air and more energy is released to the piston and the turbine so that also small engines can be turbocharged effectively. The harmful products of HC transformation can largely be avoided, even when using vegetable oil as fuel. 5. The heatflow to the cylinder liner is reduced in a ratio of 2 to 1. Therefore it is possible to change from the external water cooling to the internal cooling by a jet of lubricant oil. Only at the top the liner is cooled by an outer oil coat. From there the oil flows to the cylinder head, where, by means of bores, only the nozzle and the valve bridge are cooled. With this design, the thermal stresses in the cylinder head are much reduced compared to water cooling, and sufficient temperature is maintained to avoid lacquer deposits from vegetable oil fuels. This shows that the vegetable oil engine has no disadvantages. Whether it can be as reliable as conventional engines was evaluated by a 100,000km road test with a Duotherm engine installed in an Audi 100. First only salad oil from the grocery shop filled in bottles was used as fuel, then our own oil press supplied sufficient unrefined rapeseed and sunflower oil. The road test was

New direct injection diesel engine development for using vegetable oil as a fuel

1339

only carried out with 100% vegetable oil. Also the oil was not chemically treated or esterized but only cleaned by a centrifuge and a settling basin. Also oils from warmer regions such as soybean, castor, physic nuts, peanuts etc. were tested. After every run the combustion chamber was examined and in no case was there any difference to the operation on 100% diesel fuel. 3. LARGE SCALE PRODUCTION OF VEGETABLE OIL The slogan “Bread for the world by vegetable oil for the engine” of course not only touches the problems of the engine development. It touches many matters that today makes man do the most inconsidered things. If the mineral oil industry spends 10 billion DM for erecting one single bore island in the North Sea, they also know, that they can amortize even such high amounts because of the diminishing crude oil reserves. However, the thousands of billion DM spent for armaments to secure the access to all crude oil sources and the financial aid for countries having no foreign exchange to buy crude oil, lastly makes fossil fuel too expensive. Already 10 billion DM suffice to start the recultivation of North Africa as it is shown in Fig. 3 and Fig. 4. Europe’s climate is influenced by North Africa in so far as the air masses coming from the west to Europe are sucked in by the extreme heat ge-nerated over the Sahara and then blown away westwards. This air current, as shown in Fig. 3, gives us the possibility to enrich the air masses, streaming land-inwards with 24,000m3 water per second (10 times the water quantity of the Rhine) by humidification plants installed along 3,500km of the Mediterranean coast. One of the 8000 humidification plants having a water output of 3m3/sec is shown in Fig. 4. These humidification plants are called fog producers because the water ejected from the rotating self-supporting 200m long wings is carried away for a little while as fog, until it is dissolved by the sun rays. The water is evaporated and transported by the sun. The salt left over flows back to the sea. The evaporation performance of such a line of humidification plants can replace a forest of 200km in width. It is sufficient to provide every year an additional rain quantity of 100mm on an area of 3 million km2. At the latest when the humid air reaches the central Sahara mountains rain will fall during the night. When sufficient vegetation and humidity have been reached the humidification devices can be removed. North Africa, however, could regain the agricultural importance it had in the Roman days, which would not be disadvantageous to Europe. Engine endurance tests have been run with oil from physic nuts (lat.: jatropha curcas). These grow in African regions with far less than 100mm rain. 50% of the nuts are oil and although the remaining dry material is slightly poisonous when consumed, it is an excellent natural fertilizer. The high efficiency of this fertilizer is due to the fact that contrary to chemical fertilizers it does not sink into the groundwater but remains effective on the surface for years. When calculating the profitability of vegetable oil production the byproducts such as food for men and animals or environmentally safe compound fertilizer have to be

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considered as a decisive factor in so far as they yield at least as much as can be obtained by the oil production. 4. DRIVING WITH VEGETABLE OIL FUEL The fuel economy of the low emissions’ Duotherm engine is such that even more expensive fuels become economically attractive. For instance with the old Audi Quattro and its drag coefficient of 0.42 plus four-wheel drive it was possible to reduce fuel consumption compared to other diesel powered cars as shown in Fig. 5. Cruising at average speeds of 150km/h was nontheless possible. Future cars with a drag coefficient of 0.3 will thus certainly be within the fuel consumption area 2. A legal fuel consumption limit would thus be the correct way to obtain even better cars combined with even lower pollution of the air. Fig. 5 shows that at 120km/h it is possible to reduce fuel consumption from 9L to 5L per 100km. The cost of a year’s supply of fuel for the average 13,000 driven km at a liter price of DM 1.31 would thus be only DM 850 with a Duotherm engine. Indeed the price of vegetable oil could be as high as DM 2.36 per liter and the yearly fuel cost of the car with a Duotherm engine would be not higher as today’s cars using mineral fuel. Apart from that one could save the cost of the catalyst that is reliably estimated at DM 450 per year, when the Duotherm engine is used and at the same time substantially improve on the environmental value of the engine with catalyst. It is also an established fact that the high price of fuel is better accepted by automobilists than such bother and interference as catalysts and speed limits are. If the state wants to effectively protect the environment it should, in conformity with the rule that the causer of damage has to pay, eliminate the fuel tax when vegetable oil is used as fuel, instead of eliminating the road tax for cars with catalyst as these cars use the roads as much as others. The fuel tax is called mineral oil tax, and vegetable oil as it happens is no mineral oil. More important vegetable oil does not cause the environmental damages that justify the mineral oil fuel tax. Today, European governments pay to the EC amounts as high as the tax on mineral fuels because the EC has to buy huge quantities of agricultural surpluses that would not exist if the farmer, instead of producing excess quantities of food, would produce the required quantities of fuel. The new situation created with the introduction of the vegetable oil engine has been recognized by governmental agencies. For instance the Bavarian “Oberbergamt” has given effective financial support to the further development of this engine. The customs authorities that are responsible for the levy of the mineral oil tax in Germany do not tax vegetable oil as long as it is used without any addition of mineral oil. The Duotherm engine requires no addition of mineral oil, and also runs on vegetable oil without any chemical transformation such as esterification. Developing a combustion system and engine components suitable for the use of vegetable oil as a fuel makes much more sense than adapting all fuels to the needs of today’s engines. Chemical transformation of vegetable oil implies organisational and financial difficulties that could block the introduction of vegetable oil as a fuel for engines.

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Pure vegetable oil can be stocked, the same way as salad oil could be, in a container holding a year’s supply of fuel. Such a container could be kept in the garage and filled after each harvest as used to be the case for a family’s potato container. Modern cars have a tank of 50 to 90 liters that according to Fig. 5 is sufficient to drive 1,000 to 1,500km. Thus on average a car’s tank would have to be filled no more than 10 times per year. Oil esters apart from being environmentally less save would also require production and distribution facilities that would still have to be created. 5. CONCLUSION The consumer is able and willing to do something for the environment, and as the vegetable oil engine is now technically feasible, the consumer can see to it that both the engine and its fuel are produced and made available to the public. Also relief and help for developing countries of the third world, for instance in the Sahel, is at least as urgently needed as environmental measures in the developed countries. This help can be supplied with a program that could be entitled “Food production for men by vegetable fuel production for the engine”. The produced food would for instance be valuable soybean protein produced as a byproduct of the soybean oil production. The first recultivation of the deserts consumes about as much CO2 as is released during one year by the combustion of fossil fuels. With each following year so much humus is produced from the roots and all other parts of the plants not used as fuel or food that gradually new hydrocarbon resources develop on the surface of the deserts which can cover the energy demand of the world even better than fossil resources of coal and crude. Anyway, mining of fossil energies will cease when the regrowing oils become cheaper. The CO2 value of the air would again drop to the natural normal basis. More food than ever before would be available for men especially since the crop is harvested and processed by efficient engines and not by herds of cattles.

Energy from biomass

Fig.1

Fig.2

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New direct injection diesel engine development for using vegetable oil as a fuel

Fig.3

Fig.4

Fig.5

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OPTIMISATION OF THE SPARK ADVANCE IN BIOGAS ENGINES B.LEDUC, P.LADRIERE Institute for Applied Mechanics University of Brussels Summary The purpose of this study is to develop an electronic system for adapting the spark advance of internal combustion engines feeded with biogas. Optimal brake effective power and efficiency can be reached when gas composition changes due to the fermentation process evolution.

I. Introduction All small internal combustion biogas engines are spark ignited. An important regulation parameter of those engines is the spark ignition advance angle. The advance angle is the number of crankshaft degrees between ignition and the top dead center. In fact, if the combustion was instantaneous, the spark would appear exactly at the top dead center. As the flame front advances with a finite speed, spark must appear earlier in order to release maximum energy around the top dead center. The engine efficiency and its brake effective power are influenced by the choice of ignition timing (fig. 1). The optimal ignition point depends on the working conditions of the engine: – fuel nature – rotation speed – position of the throttle valve – equivalence ratio – ambiant conditions (temperature, pressure, humidity) For some fuels, if the speed and the load remain constant, typical values of advance angles are given in table I. biogas méthane LPG gazoline 40

30

20

15

table I: typical Spark advance Generally, engines ignition systems are equipped with centrifugal advance weights and vacuum advance mechanism in order to set the advance angle as a function of the engine rotation speed and the throttle valve position (fig. 2). The chemical composition of the biogas (mainly CH4, CO2) depends on the fermentation conditions. If the CO2 concentration is changing in time, the performance of

Optimisation of the spark advance in biogas engines

1345

the engine, depending on the heat capacity of the gas, and the optimal choice of the parameters are modified. In order to preserve for each biogas composition the optimal performance level, it is necessary to use an advance correction system taking into account the CO2 concentration (fig. 3). Several ways can be followed: – purely mechanical system – electromechanical system – electro-electronic system The last one has been developed at the Institute for Applied Mechanics. II. System description (fig. 4). II.1. General description The circuit is usable for all engines with a classical magneto ignition system. The produced voltage signal (A) is detected (B) and used in a triggering circuit (C) in order to set the reference advance angle by delaying the spark apparition (D and E). II.2. Advantages – High accuracy and reliability. – High sensitivity. – Binary coded reference angle: the system is so easily usable in a computer feedback loop. – easy use: the operator chooses himself the advance angle. – Automatic cut-off of the inlet gas flow in case of unexpected stop. II.3. Disadvantages – Relatively high price – Maintenance and repair request a qualified technician.

Energy from biomass

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Fig. 1. Influence of the spark advance on the BMEP

Fig. 2. Influence of the speed and the load on optimal spark advance

Optimisation of the spark advance in biogas engines

1347

Fig. 3. Influence of CO2 on the brake effective power

Fig. 4. IAM electronic system for varying spark advance

AUTHOR INDEX AHOKAS J, 778 ALBAGNAC G, 510, 516, 537, 542, 547 ALFANI F, 989 ALFONSEL M, 994 ALLIRAND J M, 315, 321 AMMASSARI G, 23 APFELBECH B, 1034 ARCHER D B, 1151 ARLIE J P, 45 ARNOUX M, 594 AUBART C, 489 AUBERT J-P, 651 AUCLAIR D, 274 AVEZZU F, 572 AYERBE L, 422 AZZINI A, 679 BAADER W, 567 BACHER R, 458 BALDELLI C, 164 BARATAKANWA V, 589 BARBE J, 379 BARBIROLI G, 865 BAZILE F, 552 BECKER J J, 350 BEENACKERS A A C M, 120, 900 BEGUIN P, 651 BENEA V I, 953 BENESTAD C, 819 BENGUEDACH A, 959 BERGER A, 403 BERGOUGNOU M A, 860 BERKALOFF C, 717, 722 BESTUE-LABAZUY C, 924 BHUMIRATANA S, 532 BIONDI S, 441 BLACHIER Ph, 1146 BOBLETER O, 953 BODRIA L, 869 BOELCKE C, 675 BONALBERTI E, 158 BONFANTI P, 430 BONN G, 953

Author index

BORIES A, 552, 557 BORREDON M E, 968 BOTA K B, 827 BOURREAU A, 963 BRAULT A, 924 BREAG G R, 849 BREGOLI M, 617 BRENCKMANN F, 717, 722 BRENNDORFER M, 773 BRIDGWATER A V, 910, 915 BROUERS M, 387 BROWNELL H H, 978 BRUNEAU C, 924 BUHS C, 744 BULLY F, 489 BUSSMANN P, 814 CALLAGHAN T V, 109, 412 CAMPAGNA R, 496 CAMPBELL D J V, 1151 CANTARELLA M, 989 CANTERELLA L, 989 CAPART R, 842 CARRE J, 809 CASADEVALL E, 717, 722, 727 CATHALA N, 557 CECCHI F, 572 CESCON P, 572 CHARTIER M, 315, 321 CHASSANY J P, 1049 CHASSANY DE CASABIANCA M-L, 407 CHIUMENTI R, 645 CHORNET E, 933 CHRYSOSTOME G, 889 CLANCY J S, 1131 CLARK A, 288 CLEGG J M, 334 COLACO M I A, 707 COLLARD F, 369 COLLERAN E, 630 COMINETTA G, 594 COMPAGNION D, 589 CORRE B, 722 CORTELLINI L, 599 COUTE A, 727 COX D J, 448 CROATTO U, 158, 577 CUADROS S, 506 CUTAYAR J, 527 DAWSON W M, 264

1349

Author index

DE ANGELIS A, 645 DE MENEZES J B, 679 DE POLI F, 625, 645 DECLERCK M, 310 DEGLISE X, 822, 920 DEL MEDICO G, 496 DELANNOY B, 547 DELMAS M, 968 DEMUYNCK M, 146 DONNOT A, 822 DORING R, 732 DOS SANTOS C L M, 679 DOUBLE J M, 915 DUBBE D R, 354 DUBOURGUIER H C, 516, 542 DUJARDIN E, 369 DUNN P D, 1172 DUVIGNAU M, 557 EBELING J, 804 EGGER K, 453, 1136 EL-HOUSSEINI M, 458 ELSBETT G, 1177 ELSBETT K, 1177 ELSBETT L, 1177 ESNOUF C, 942 EVANS M C W, 117 FAGBEMI L, 842 FAIX O, 732, 929 FALLOWFIELD H J, 398 FANKHAUSER J, 1136 FAYOLLE F, 692 FDZ-POLANCO F, 464 FELBER J, 1025 FERNANDEZ R, 506 FERNANDEZ J, 330, 994 FERRARI D, 617 FIALA M, 869 FIELDING E R, 1151 FINK J D, 510 FLORENZANO G, 584 FONTES A G, 393 FORISTER G, 804 FORSTER U, 665 FRAIPONT L, 1122 FRANK J R, 323, 484 FREDERICK D J, 288 FREEL B A, 860 FUJINO D, 804 FUNES L E, 422

1350

Author index

GALLIFUOCO A, 989 GARCIA A J, 506 GARCIA P, 464 GARRETT M K, 398 GARVER E G, 354 GASET A, 968 GAST D, 949 GATEAU P, 985 GATTA A, 865 GAUTIER X, 756 GELUS M, 842 GEYER W A, 269 GHERI F, 164 GIANI C, 665 GIRARD H, 651 GIRAUD A, 6 GOCHNARG I, 1088 GOMA G, 458, 510 GOSSE G, 66, 315, 321 GOUDEAU J C, 959, 963 GOUPILLON J F, 783 GRAHAM R G, 860 GRASSI G, 164 GREPINET O, 651 GROS D, 689 GROSZMANN G L, 1088 GUERRERO M G, 393 GUIBET J C, 985 HAARS A, 973 HALL D O, 387 HARKER A P, 849 HARTMEIER W, 660, 665, 684 HAYES T D, 484 HELLWIG M, 793 HELD W, 744 HENHAM A W E, 1167 HENNING K-D, 621 HENRY M, 689 HERBERT J, 809 HILLION G, 985 HIMMEL W, 640 HISLOP D, 1064, 1093 HOFFMANN G, 1113 HORTON L, 288 HUMMELL F C, 90 HUTTERMANN A, 973 IBANEZ E, 635

1351

Author index

JASTER K W, 879 JAWETZ P, 1126 JAYET P A, 479 JENKINS B, 804 JOHNS R A, 1167 JOSEPH S, 1064, 1093 JOYCE R J, 735 JULIEN L, 959, 963 JUNTGEN H, 621 KAFROUNI H, 920 KAHNT G, 339 KANDLER O, 474, 609 KAWAMBWA S, 1131 KEKRE M G, 982 KIHUMBA S N, 749 KLOCK G, 374 KNOBLAUCH K, 621 KOGL H, 84 KOUFOPANOS C, 837 KRAUS U, 799 KREULEN H P, 1069 KREUZBERG K, 374 KRISPIN T, 1117 KUNTZEL U, 604 KUUSINEN O, 1006 LA ROVERE E L, 207 LACROSSE L, 809 LADOUSSE A, 920 LADRIERE P, 1182 LAMMERS P S, 874 LARGEAU C, 717, 722 LARIGAUDERIE A, 403 LARIMER D R, 929 LARKIN S B C, 334 LAU C F, 1084 LAWSON G J, 109 LAWSON G J, 412 LE FUR C, 1146 LEDUC B, 1182 LEGROS A, 369, 584 LEIBLE L, 339 LEMA J M, 635 LEMASLE J M, 889 LEPRI A, 655 LEPRINCE P, 45 LEQUEUX P, 809 LESCURE J P, 547 LEUCHS M, 1141

1352

Author index

LEULLIETTE L, 689 LIINANKI L, 832 LISTER T A, 735 LONGIN R, 651 LOSADA M, 393 LUCCHESI A, 837 LUNNAN A, 1030 MAGNE P, 822 MAINWARING A M, 412 MAJCHERCZYK A, 973 MANERO J, 330 MANURUNG R, 900 MANZANARES P, 330 MARCHAL R, 692 MARCHETTINI N, 702 MARTINDALE L P, 343 MARTIN C, 994 MASCHIO G, 837 MASSON D, 920 MATARASSO P, 1010 MATERASSI F, 584 MATHRANI S, 1108 MAZZAGARDI M, 384 MCELROY G H, 264 MCKENZIE HEDGER M, 1098 MCKEOUGH P J, 937 MEGALOS M A, 288 MEHRLING P, 905 MEIER D, 732, 929 MEINHOLD K, 84 MELICHER M W, 269 MENDIA M, 625 MES-HARTREE M, 982 METZGER P, 727 MICHAELIS L A, 1039 MICHELOT E, 552 MIGLIACCIO N, 625 MILANDE N, 648 MILLET J, 651 MIRANDA U, 164 MISHOE J W, 1020 MISSONI G, 384 MITCHELL C P, 300 MOK L K, 860 MOLETTA R, 510, 516 MOLLER M, 819 MORENO J, 393 MOREL J Y, 594 MOTTET A, 1122 MOULINEY M, 527

1353

Author index

MUCKE I, 660 MUKHERJEE C, 768 NATUSCH D F S, 735 NAUGHTON G G, 269 NAVEAU H, 146, 369, 584, 589 NDAYISHIMIYE J, 589 NDITABIRIYE D, 589 NEENAN M, 278 NEGRO M J, 994 NEIBELSCHUTZ H, 675 NEMICHE A, 963 NG’ENY-MENGECH A, 749 NICOLINI S, 614 NIYIMBONA P, 589 NOBLE D H, 334 NOLTING F, 1141 NUTTALL D R, 448 NYNS E-J, 146, 369, 584, 589 O’KELLY N, 630 OELERT H H, 744 OGGIONNI C, 594 OHRT U, 1113 OKKEN P A, 760 ONG K S, 1084 OORTHUYS F M L G, 522 ORSI N, 702, 714 ORSORE H, 999 ORTMAIER E, 348 OSTAN R, 865 OSVIK A, 819 OVEREND R P, 178, 860, 933 PACI M, 837 PAPADOPOULOS J, 697 PAQUOT M, 1122 PASQUALI G, 865 PEARCE M L, 292 PELKONEN P, 417 PELLIZZI G, 99 PEREIRA H, 707 PERERA E D I H, 1172 PERRIN L, 30 PETERS M, 744 PETRE D, 651 PEZZULLO L, 989 PHILLIPS D R, 288 PICCININI S, 599 PICKEN D J, 493 PIERONI M, 496

1354

Author index

PITZER H, 1113 POSTMA H J W, 522 POUET Y, 727 POURQUIE J, 692 PRASAD K K, 814 PRATT D C, 354 PRENSIER G, 542 PRICE R, 214 PULS J, 670, 949 PYLE D L, 1074, 1108 RADLEY R W, 334 RAMDAHL T, 819 RAYMOND B, 648 RAYNAL J, 552 RAYNAUD O, 651 REBELLER M, 692 REDONDO L J, 464 REIFENSTAHL G, 744 REIMERT R, 905 REQUILLART V, 1015 REYNIEIX M, 847 REYNOLDS P J, 630 REZNICZEK G, 374 RICE G, 1131 RICHARD J R, 894 RICHARDSON D W, 735 RICHTER E, 621 RIETVELD F A J, 579 RIGAL L, 968 RINGBLOM U, 151 ROBERTS D, 804 ROCANCOURT M, 651 ROLOT D, 589 ROMAN J, 310 ROSILLO-CALLE F, 1058 ROSSI C, 702 ROY J, 403 RUDOWSKI M, 1136 SAARIKKO E, 427 SACHS K M, 804 SACHS R M, 804 SADDLER J N, 978 SAEZ F, 994 SAEZ R, 994 SALVI G, 869 SAMAIN E, 542 SAMUELS G, 1126 SANZ I, 464 SAUZE F, 364

1355

Author index

SAVOIA G, 441, 865 SCHARF H J, 884 SCHIEFERSTEINER M, 1025 SCHNEIDER J, 1156 SCHORNER G, 1002 SCHRADER L, 884 SCHUTZ P, 640 SCHWALD W, 953 SCOTT R, 109, 412 SCULLY J J, 33 SELIGMAN R M, 15 SEMENZA C, 430 SILHOL M, 1146 SIMEON C, 1146 SINGH N P, 1079 SIPILA K, 778 SIRONVAL C, 369 SKUTSCH M M, 1103 SMETS J, 310 SMETS Ph, 310 SMITH D H, 910 SMITH E A, 849 SMITH W H, 222, 323, 484 SOLANTAUSTA Y, 937 SONNENBERG S, 1117 SOUIL F, 963 SOURIE J C, 1054 SOYER N, 924 SPITZER J, 640 SPRUIJT G, 1069 STADLER E, 1136 STAHLBERG P, 778 STEINER A, 474 STEINMULLER H, 1025 STERN B, 985 STREHLER A, 60, 788 STRUB A S, 3 STURMER H, 348 SULILATU F, 814 SUPAJUNYA N, 532 SUTTER K, 453 SVENNINGSSON P J, 832 TABARD P, 283 TABET J P, 1010 TAHA A, 982 TANTICHARDEN M, 532 TATOM J W, 827 TEGGERS H, 884 TEMPER U, 609 TENORIO J, 422

1356

Author index

TESSIER-DU-CROS E, 305 THEANDER O, 1044 THESSEN G, 832 THOMA H, 348 THONART P, 1122 TIEZZI E, 655 TILCHE A, 599, 645 TORMALA T, 427 TRAMM-WERNER S, 684 TRAVERSO P G, 572 TREDICI M R, 584 TROJANOWSKI J, 973 TROSSERO M A, 296 TSHIAMALA T, 1122 TVETEN G, 819 UGLIATI S, 655 UTITHAM T, 532 VALENTI P, 702, 712 VAN BEEK H C A, 1069 VAN DER DRIFT E, 1069 VAN SWAAIJ W P M, 120 VANDECASTEELE J P, 692 VAPAAVUORI E M, 417 VARGAS M A, 393 VENTAS P T, 422 VERRIER D, 537, 547 VIGLIA A, 614, 617 VILPPUNEN P, 1160 VIMAL O P, 1079 VISCA P, 712 VOVELLE C, 894 VUILLOT M, 379 VUORINEN H, 417 WAGNER F, 744 WASHBOURNE J F, 765 WEILAND P, 562 WEISMANN A F, 37 WELLINGER A, 453, 1136 WENMAN C M, 172 WIEGEL J, 670 WILDENAUER F X, 469, 474, 609 WILEN C, 778 WILHELMSEN G, 54 WILKIE A, 630 WILTON B, 765 WINTER J, 469, 609 WOHLMEYER A F J, 74 WU WEN, 228

1357

Author index

WULFERT K, 562 WUNSCHE U, 359 WURSTER R, 501 YEBOUA AKA F, 458 YU E K C, 978 ZAROR C A, 1074 ZAUNER E, 604 ZERBIN W O, 1117 ZUBR J, 435 ZUFFI O, 648 ZWIEFELHOFER H P, 1163

1358

SUBJECT INDEX Acetone butanol fermentation 692 Acid hydrolysis 697 Advanced gasification 120 African termites 999 Agricultural markets 1034 Agricultural residues 832 Agriculture 66, 84, 350 Agrobioenergy 1065 Air pollution 819 Alcohol 959, 1131 Algae 158, 369, 374, 384, 393, 398, 564, 577, 614, 660, 717, 727 Alkali treatment 994 Ammonia 387 Anaerobic bacteria 537 Anaerobic digestion 448, 474, 489, 501, 522, 537, 572, 614, 617 Anaerobic fermentation 594 Anaerobic filters 630 Anaerobic sludges 516 Anaerobic stabilization 469 Anaerobic treatment 527, 648 Animal feed 369 Animal slurry 398 Animal wastes 522 Anoxal process 527 Aquatic biomass 1146 Aquatic systems 379 Arable crops 315 Austria 73, 640, 1002 Bamboo 679, 1122 Bark 894 Bioconversion 973 Biodegradation 989 Biogas 228, 411, 453, 532, 577, 625, 640, 1002, 1136 Biogas digester 567 Biogas engines 1141, 1182 Biogas technologies 506 Biological treatment 496 Biomass valorization 1110 Biomethanation 146, 458, 479, 547, 552, 562, 564, 589 Boilers 819 Botryococcus braunii 717, 722, 727

Subject index

Brazil 207, 1058, 1088 Briquetting 773, 1064 Broom (C. scoparius) 283 Butanol-tolerance 712 Butyrates 516 Canada 178 Cannery wastes 532 Carbonisation 849, 865 Cassava residues 501 Catalysis 959, 963 CEC 3 Cell immobilization 660, 665 Cellulose 860, 989 Cellulosic biomass 697 Charcoal 783 Chemicals 978, 982 China 228 Chromatography 732 Circulating fluid bed reactor 905 Cloning 651 Clostridium acetobutylicum 702, 712 Clostridium thermocellum 651 Coconut shell 849 Combustion 793, 847 Common Agricultural Policy 33 Continuous process 689 Cooking 768 Coppice 264, 269, 274, 292 Corn cobs 756 Corn drying 756 Crop drying 804 Cropping 359 Crude wood oils 732 Cyanobacteria 393 Densified biomass 809 Developing countries 589, 827 Diesel engines 1136, 1172, 1177 Diesel fuel 735 Diesel fuel substitute 1069 Distillery waste waters 552, 562 Domestic firewood burner 768 Downdraft gasifier 832, 900 Downflow anaerobic filter 547 EC pilot plants for syngas 120 Economics 484, 493, 937, 1015, 1039, 1049 Ecuador 1098 Edible oil 1069 EEC 348, 350

1360

Subject index

1361

Eichhornia crassipes 407 Energy balance 920, 1088 Energy crops 323, 330, 435, 604 Energy valorisation 1015 Energy-cane 1126 Environment 760, 874, 1156 Enzymatic hydrolysis 692, 707, 994 Ethanol 339, 655, 660, 665, 670, 679, 684, 689, 697, 1025, 1058 Ethyl esters 985 Ethylene glycol 949 Eucalyptus globus 707 Euphorbia lathyris 422 Expanded bed reactors 464 FAO 296 Farming systems 1049 Fast pyrolysis 860 Feedstocks for alcohol 151 Fermentable sugar 339 Fermentation 151, 374, 675, 702, 1122 Fluidised bed combustion 765 Fixed bed reactor 562 Fixed film reactor 594 Food processing industry 448 Forest research 300, 305 Forestry 90, 178, 441, 1103 France 1015, 1054 Free-cell fermentation 648 Fuel 435, 978 Fuel alcohol 172 Fuelwood 1108 Fungi 973 Fungus-comb 999 Furnaces 804 Gas cleaning 579, 621, 625 Gas fired equipment 579 Gas production 579 Gas purification 453 Gasification 832, 847, 869, 874, 884, 900, 905, 915, 1002, 1113 Genetics 651 Germany 37, 799 Glycosidases 665 Greenhouse heating 804 Hardwoods 288 Heating 74 Hemicellulose use 1025 HTW-process 884 Hydrated heterogeneous medium 968 Hydrocarbons 717, 722, 727, 744, 749

Subject index

1362

Hydrogen 387, 510 Hydrogenation 929 Hydrolysis 933 Hydrothermolysis 953 Immobilized cells 689 Immobilized cyanobacteria 387 Immobilized β-galactosidase 684 Immobilized systems 537, 552, 557 India 1079, 1103, 1108 Indonesia 1113 Industrial biogas projects 599 Industrial chemicals 749 Industrial effluents 527 Industrial regions 60 Industrial waste waters 557, 609 Industrial wastes 496 INRA (France) 305 Integrated food-energy 207 Iron additives 924 Italy 564, 599 Jerusalem artichoke 339 Kenyan plants 749 Kinetics 458, 635, 822, 837 Lactose 684 Landfill gas 1151, 1156 Landfill leachate 635 Latin America 1126 Lead additives 1058 Lean burn 1167 LEBEN project 164 Light intensity 722 Lignocellulose 557, 692, 949, 978, 999, 1025, 1074 Liquefaction 933 Liquid fuels 348, 1039 Malaysia 1084 Marginal lands 1049 Mass balance 920 Mesophilics 670 Methane 369, 474, 479, 484, 496, 557, 604, 609, 617, 621, 910 Methanogenic ecosystems 510 Methanogenic sludge 537, 542 Methanol 963 Methanol mixtures 1167 Methyl esters 735 Micropropagation 427, 441

Subject index

Modeling 645, 842, 1010 Molecular sieves 621 Moving bed gasifier 900 Municipal wastes 572 Mutants 712 Natural vegetation 109 Netherlands 760 Nitrogen 393 Nitrogen fixation 387 NMR 655, 702 Nordic countries 54 Northern Ireland 264 Norway 1030 Nutrients 717 Onopordum nervosum 330, 994 Organic chemicals 968 Organosolv lignins 973 Oxygen gasification 889 Paper 1122 Pelletization 778 Pentosans 670 Pentoses 670 Petrol substitution 45 Photobiology 117 Photointerpretation 430 Photosynthesis 403, 435 Phragmites 321 Pig manure 489 Pipeline gas 621, 625 Piscicultural waste 1146 Plant nutrients 412 Platform tests 847 Producer gas 879 Proprionate 516 Pyrolysis 822, 827, 837, 842, 933, 1002 Rape 1034 Refuse 1156 Refuse decomposition 1151 Regional energy 1030 Research information 1020 Residues 99 Rice husk 900 Rubber seed oil 1172 Rural development 1098 SCP production 707

1363

Subject index

Semi-arid lands 310 Sewage 464 Sewage sludge 1163 Short rotation forestry 264, 278, 953, 1034 Slaughterhouse wastes 474 Small steam systems 1093 Social impacts 760 Solid-liquid transfer 968 Solvent delignification 707 Southern US 222 Spark-ignition engines 1131, 1136, 1167 Sri Lanka 1172 Steam explosion 978 Stoves 1103 Straw 334, 343, 773, 778, 788, 793, 799, 1015 Straw combustion 756 Sugar 978 Sugar industry waste 982 Sugar waste waters 547 Sunflowers 417 Sweden 1065 Sweet sorghum 339 Syngas 889, 905, 959, 963 Synthesis 968 System analysis 1020 Tallow 735 Tannery wastes 617 Tanzania 1131 Temperature stress 422 Thailand 1074 Thermal degradation 894 Thermochemical conversion 1039 Thermochemical liquefaction 929, 937, 942 Thermochemical processing 1074 Thermophilic digestion 609 Thermophilics 670 Trees 54 Two phase digestion 562 UK 300, 334, 343 USA 354, 484 Vegetable oils 985, 1177 Venice lagoon 384, 614 Volatile fatty acids 516 Waste heat recovery 849 Waste incineration 819 Waste management 1160

1364

Subject index

Waste treatment 577 Waste water 407, 648 Wastes 99, 214, 469 Water hyacinth 364, 403 Water stress 422 Water treatment 364, 379 Wetlands 354 Willows 264, 417, 427 Wood 54, 788, 793, 799, 849, 865, 879, 889, 894, 1039 Wood liquefaction 920, 924 Wood stoves 760, 814 Wood tar 822 Wood waste 879 Wood-based energy 296 Woodgas power plants 1117 Yeast 660, 665, 675 Yields 323 Zeolites 959 Zimbabwe 172 Zymomonas mobilis 684

1365

LIST OF PARTICIPANTS ALBAGNAC G, INRA, Villeneuve d’Asq, France. ALBERTSSON N, HB Nydo Energi, Stockholm, Sweden. ALEXANDRIAN D, CREMAGREF, Aix-en-Provence, France. ALFANI F, Dept. of Chemical Eng., Univ. Naples, Italy. ALLIRAND J-M, INRA, Thierval Grignon, France. ALTDORFER F, Science Policy Office, Brussels, Belgium. AWIRANTE B, Inst. di Meccanica agraria, Bari, Italy. AQUILANI R, Palazzo Uffici, Milano, Italy. APFELBECK R, Bayerische Landesanstalt f. Landtechnik Freising, Germany. ARNOUX M, INRA, Montpellier, France. ARNOUX, Ste.S.G.N. Montigny le Bretonneux, France. ASPLUND D, Tech. Res. Centre, Jyvaskyia, Finland. AUCLAIR D, INRA, Olivet, France. AXELSSON L-E, Pulp & Paper Assoc., Stockholm, Sweden. AYERBE L, INIA, Madrid, Spain. BALDELLI C, CASMEZ, Roma, Italy. BALLONI W, CSMA CNR, Firenze, Italy. BARRETO DE MENEZES T, Ital, Campinas-SP, Brazil. BEAUMONT O, Elf Aquitaine, St. Symphorien d’Ozon, France. BECKER J J, CEMAGREF, Antony, France. BENNACKERS A A C M, Groningen Univ., Boekelo, The Netherlands. BEETS W C, ICRAF, Nairobi, Kenya. BEGUIN P, Inst. Pasteur, Paris, France. BELLAMY J-J, Assoc. Bois de Feu, Aix-en-Provence, France. BELLETTI A, A. Biotec, Forli, Italy. BENESTAD C, Centre for Industrial Res., Blindern, Norway. BENGTSSON G, Bepolkemi AB, Ornskoldsvik, Sweden. BENN R, UMIST, Manchester, UK. BENTE Jr P, Bio-Energy Council, Arlington, USA.

List of participants

1367

BERGGAMASCHI P, Conphoebus soc. cons., Catania, Italy. BEVAN C, Alsthom Atlantique, La Courneuve, France. BINI SMAGHI B, CEE, Bruxelles, Belgium. BISCEGLIA D, Regione Puglia, Bari, Italy. BODMER R, E. Basler+Partner, Zurich, Switzerland. BODRIA L, Inst. Agr. Eng., Milano, Italy. BOELCKE C, Inst. Fermentation und Brauwesen, Berlin, Germany. BOLHAR-NORDENKAMPF H, Inst. f. Pfanzenphysiologie, Wien, Austria. BOILLOT M, Electricite de France, Chaton, France. BOMBELLI V, EIVEA, Roma, Italy. BONAIUTI R, Libevo professioniste, Milano, Italy. BONAMOUR A-M, AFNE, Paris, France. BONICEL A, CEN, Grenoble, France. BONOMI E-M, FAC Ingegnema—Roma, Roma, Italy. BORIES A, INRA, Barbonne, France. BOU J, Catalana de gas y electricidad s.a., Barcelona, Spain. BOUISSOU O, AFME, Paris, France. BRANDELS L, Nat. Energy Administration, Stockholm, Sweden. BREAG G R, Tropical Development Res. Inst., Culham, UK. BREEZE P, Modern Power Systems, London, UK. BRENNDORFER M, KTBL, Darmstadt, Germany. BRIDGWATER A V, Univ. of Aston, Birmingham, UK. BROCHIER J, Brochier Agro Cons., Castries, France. BRUGGINK J C, NERF, Le Petten, The Netherlands. BRUNEAU C, ENSCR, Rennes-Beaulieu, France. BULLY F, BIOMAGAZ/Groupe EMC, Cernay, France. BURIAN-HANSEN P, Crone & Koch, Viborg, Denmark. BUSSMANN P, Univ. of Tech., Eindhoven, The Netherlands. BUSCH H P, Forschungsinstitut f. schnellwachsende, Hann Munden, Germany. CACERES A, CEMAT, Guatemala City, Guatemala. CAIRE B, VALORGA, St Jean de Vedas, France. CAIREN S, Nat. Energy Aministration, Stockholm, Sweden.

List of participants

1368

CALL H P, Inst. for Biology RWTH, Aachen, Germany. CALLAGHAN T, Inst. of Terrestrial Ecology, Grange—over—sands, UK. VALBIRISSI F, Eniricerche, Monterondo, Italy. CAMPAGNA R, Ist. Guido Donegani, Novara, Italy. CANNAZZA G, European Energy & Environmental Eng. Ltd, Dietikon, Switzerland. CANTARELLA M, Dpto di Ingegneria Chimica, Univ. di Napoli, Italy. CANTARELLA L, Dpto Ing. Chimica Fac. Ing., Univ. di Napoli, Italy. CAPART J, Univ. de Compiegne, Compiegne, France. CARBONE D, Conphoebus Soc. Cons., Catania, Sicily. CARRE J, AFNE, Paris, France. CARRE J, CRA, Gembloux, Belgium. CARRIERI C, IRSA—CNR, Bari, Italy. CARVALHO NETO C C Fund. de Tec. Ind., Lorena, Brazil. CASADEVALL E, CNRS—ENSCP, Paris, France. CATANZAO G, Cassa per il Mezzogiorno, Roma, Italy. CATHELINAUD Y, OCDE, Paris, France. CELEOTTI S, CAVIRO, Faenza, Italy. CETINCELIK M, Energy Word, Ankara, Turkey. CHALFONT G, BP Chemicals Ltd, London, UK. CHARTIER P, AFME, Paris, France. CHASSANY de CASABIANCA M L, CNRS, Montpellier, France. CHASSAING, European Energy & Environmental Eng. Ltd, Dietikon, Switzerland. CHESINI R, Verona, Italy. CHIESA G, SpA Castagnetti, Cascine Vica/Rivoli, Italy. CHRISTENSEN J, Inst. of Agr. Econ., Copenhagen, Denmark. CISSE I, CRES, Paris, France. CLANCY J S, Energy Group, Univ. of Reading, UK. COGLIATI G, AGIP, Roma, Italy. COLLERAN E, Dept. of Microbiology, Univ. College, Galway, Ireland. COOMBS J, Bio-Services, London, UK. CORELLA J, Univ. di Zaragoza, Spain.

List of participants

1369

CORTELLINI L, CRPA, Reggio Emilia, Italy. COX D J, Polytechnic of South Bank, London, UK. CRIME D, INRA, Grignon, France. CUEL J, Beghin—say, Paris, France. CUTAYAR J, L’air Liquide, Les Loges en Josas, France. DAWSON M, DANI, Loughgall, UK. DE BENOIST H, AGPB, Paris, France. DE BOER W Gist-Brocades nv, Delft, The Netherlands. DECLERCK M, Tractionel, Brussels, Belgium. DE LATOUR P, Univ. of Paris-Dauphine, Paris, France. DEL CAMPO F, Univ. Autonoma de Madrid, Spain. DELTOUR L, INIEX, Liege, Belgium. DENOROY P, INRA, Paris, France. DE PIERREFEU A, IRCHA, Vert-le-Petit, France. DE POLI F, ENRA, Roma, Italy. DE SILGUY C, APCA, Paris, France. D’ESTAIS F, CGB, Paris, France. DEVAUX P, AFME, Paris, France. DE WAART J, CIVO-Analyse-TNO, He Zeist, The Netherlands. DINH VAN T, Fichtner Cons. Eng., Stuttgart, W. Germany. DOAT J, CTFT, Nogent sur Marne, France. DOSIK R, World Bank, Washington DC, USA. DOUBLE J, Univ. of Aston, Birmingham, UK. DUBBE D R, Univ. of Minnesota, USA. DUBOURGUIER H-C, INRA, Villeneuve d’Asq, France. DUJARDIN E, Liege Univ., Sart-Tilman, Belgium. DYNESEN C, H Moller Andersen Aps, Frederiksberg, Denmark. EDEN P, Barclays Bank plc, London, UK. EHLE J, Hofspiegelberg, Salzhemmendorf, W.Germany. EL-HOUSSEINI M, INSA, Toulouse, France. ELSBETT K, Elsbett—Konstruktion, Hilpoltstein, W.Germany. EMRICH W, Carbon Int. Ltd, Neu-Isenburg, W.Germany. ENGSTROM S, Dept. of Chem. Tech., Univ. of Stockholm, Sweden.

List of participants

1370

EVANS M C, King’s College London, UK. FAIX O, Ist. of Wood Chemistry & Chem. Tech. of Wood, Hamburg, Germany. FALLOWFIELD H J, West of Scotland Agr. College, Ayr, UK. FANTINI P, Univ. La Sapienza, Roma, Italy. FARINA G L, Foster Wheeler Italiana, Milano, Italy. FAUL W, KFA Juelich, Juelich, Germany. FELBER J, Voest Alpine, Linz, Austria. FERRENCZY G, Haustechnik Plannunsgesellschaft, Gmuend, Austria. FERNANDEZ-POLANCO F, Fac. de Ciencias, Valladolid, Spain. FERNANDEZ J, Junta Energia Nuclear, Madrid, Spain. FERRERO G L, CCE, Bruxelles, Belgium. FIEVET B, CESTA, Paris, France. FINCK J D, Elf Bio Recherches, Castanet Tolosan, France. FIORAMONTI S, INRA, Castanet Tolosan, France. FLORENZANO G, CMA-CNR. Firenze, Italy. FLYNN B, Applied Power Technology, Menlo Park, USA. FONTES G, Facultat de Biologia y CSIC, Sevilla, Spain. FOO ENG LEONG, Karolinska Inst., Stockholm, Sweden. FRANK J, Gas Res. Inst., Chicago, USA. FRANZONE V, Consorzio ASI-ENNA, ENNA (Sicily), Italy. FUCHS K, Inst. of Wood Chemistry & Chem. Tech. of Wood, Hamburg, Germany. GAGNAIRE-MICHARD J, CEA, Grenoble, France. GAHAN H, BCTIS, Dublin, Ireland. GALLIFUOCO A, Dipartimento Ingegneria Chimica, Univ. Napoli, Italy. GALVAGNO A, Consorzio ASI-ENNA, ENNA (Sicily) , Italy. GARCIA BUENDIA A, ENADIMSA, Madrid, Spain. GARCIA M, GDE, Lisboa, Portugal. WEICKMANS M, CIBE, Paris, France. GARSIA W-G, AGIP SPA, Milano, Italy. GASET A, ENSC, Toulouse, France. GAUTIER E, SES SPA, Rome, Italy.

List of participants

1371

GAUTIER X, AGPM, Serres Castet, France. GELUS, Univ. de Compiegne, France. GEYER W, Kanas State Univ., Kansas, USA. GHERI F, Grassina Firenze, Italy. CHILARDOTTI G, AGIP, Milano, Italy. GIRAUD A, CGE, Paris, France. GLAUSER M, Univ. de Neuchatel, Switzerland. GLYNN P, EEC, Bruxelles, Belgium. GOCHNARGE I, IPT, Sao Paulo, Brazil. GOEBEL O H, Cora Eng., Chur, Switzerland. GOLDSTEIN I S, North Carolina State Univ., Raleigh, USA. GOSSE G, INRA, Grignon, France. GOUDEAU J-C, CNRS Poitiers, St-Julien L’Ars, France. GOUDRIAAN F, Shell, Amsterdam, The Netherlands. GOUPILLON J-F, CEMAGREF, Antony, France. GRAHAM R, Univ. of Western Ontario, Canada. GRASSI G, CEC DG XII, Bruxelles, Belgium. GRAUBY A, CEA CEN Cadarache, France. GRECCHI M, Settore al problemi Energetici, Milano, Italy. GROOP S, State Power Board, Vallingby, Sweden. GUARELLA P, Ist. di Meccanica agraria, Bari, Italy. GUINARD O, Agro-Developpement, Paris, France. GURUMURTI K, Forest Res. Inst., Dehravun, India. HAARS A, Inst, f. Forstbotanik, Gottingen, W.Germany. HADZIC M, Projectni Zavod, Beograd, Yugoslavia. HAEFFNER E, Innovation Inst., Stockholm, Sweden. HALL D O, King’s College, London, UK. HARME P V, Min. of Trade & Ind., Helsinki, Finland. HAVE H, Royal Vet. & Agr. Univ., Tasstrup, Denmark. HAYAT G, Foster Wheeler, Paris, France. HEDUIT M, MNE, Paris France. HELD W, Volkswagenwerg AG, Wolfsburg, Germany. HELLWIG M, Landesanstalt f. Landtechnik, Freising, Germany.

List of participants

1372

HENHAM A, Univ. of Surrey, Guildford, UK. HENNING K D, Bergbau Forschung, Essen, Germany. HILTUNNEN J, Neste Oy, Porvoo, Finland. HISLOP D, ITDG, London, UK. HOBAUS P, NCAR, The Hague, The Netherlands. HOFFMANN G, TUEV Rheinland Inst. ETEP, Koeln, Germany. HOFFMANN J, Office Arid Lands Studies, Tucson, USA. HOLISTER M, UNESCO SC/TER, Paris, France. HORDIJ K, CDP Consultants, Utrecht, The Netherlands. HULSCHER W, Twente University, Enschede, The Netherlands. HUMMEL F, Consultant, Guildford, UK. JAMES R, EDG, Cheltenham, UK. JARGSTORF B, DDE-CI, Bad Homburg, W.Germany. JASTER K, Fritz Werhner Industrie GmbH, Geisenheim, W.Germany. JAUNEAU E, AFME, Paris, France. JAWETZ P, Consultant, New York, USA. JOLY J, AFME, Paris, France. JOSEPH S, BEST, Saratoga, Australia. JUNET R, Gaz de France, St. Denis, France. KAWAMBWA S, Univ. of Reading, UK. KEKRE M, Univ. of Gezira, Wadmedani, Sudan. KINGSOLVER B, Univ. of Arizona, Tucson, USA. KISGECI J, Inst. Field & Vegetable Crops, Backi Petrovac, Yugoslavia. KI-ZEBO J, Dakar, Senegal. KLEIN M, Kraftwerk Union, Offenbach, Germany. KOCSIS K, FAO, Roma, Italy. KORFF J, URBK, Wesseling, Germany. KOUFOPANOS C, Dept. of Chem. Eng., Univ. Pisa, Italy. KRAUS U, TUMW, Freising, Germany. KREULEN H P, HVA Int. BV, Amsterdam, The Netherlands. KREUZBERG K, Inst. of Botany, Univ. Bonn, Bonn, Germany. KROLIKIEWICZ M, AMC-STITEUR, Frankfurt, Germany. KUUSINEN O, Neste Oy, Espoo, Finland.

List of participants

1373

LAFONT S, Technip, Paris, France. LARIGAUDERIE A, CNRS, Montpellier, France. LARKIN S, Silsoe College, Bedford, UK. LATRAVERSE S, Gaucher Pringle Cons. Ltd, Montreal, Canada. LAUFER P, AFME, Paris, France. LEATHER T, Shell Int. Petroleum Co Ltd, London, UK. LEBRE LA ROVERE E, FINEP, Rio de Janeiro, Brazil. LEDUC B, Univ. of Brussels, Brussels, Belgium. LEFEBVRE L, Rhonealpenenergie, Lyon, France. LEIBLE L, Univ. Hohenheim, Stuttgart, Germany. LEINERT S, Leinert-Forest Consult, Dreieich, Germany. LEMA J, Dpto. Quimica Tecnica, Univ. Santiago, Spain. LEMASLE J M, Framatome, Le Creusot, France. LEPRI A, Dipartamento di Chimica, Univ. Siena, Italy. LEPRINCE P, Inst Francais du Petrole, Rueil-Malmaison, France. LEQUEUX P, CEC, Brussels, Belgium. LEROUDIER J P, AIBA, Paris, France. LEROY F, IEGSP, Charleroi, Belgium. LEULIETTE L, SGN, Saint-Quentin Yvelines, France. LINDBLOM A, Vattenfall, Vallingby, Sweden. LINNEBORN J, Wiesbaden, Germany. LJUNBLOM I, Bio Energy, Stockholm, Sweden. LISTER T, LFTB, Wellington, Australia. LONGCHAMP D, Inst. Francais du Petrole—CEDI, Vernaison, France. LUBINSKA A, Journalist, Brussels, Belgium. LUCCHESI A, Dept of Chemical Eng., Pisa, Italy. LUCCONI E, CNCD, Roma, Italy. LUMBROSO R, NEFAH, Herzlia, Israel. LUMME I, PSTL, Univ. of Oulu, Finland. LUNNAN A, Dept. of Forest Economics, N1432 AS, Norway. LUO Z-F, Inst. of Energy Conv., Guangzhou, China. MACDONALD I, Liquid Fuels, Wellington, New Zealand. MACEDO I, Copersucar, Sao-Paulo, Brazil.

List of participants

1374

MCKENZIE HEDGER M, Imperial College, London, UK. MAGNE P, Univ. de Nancy, Vandoeuvre, France. MAHIN D, Bioenergy Project, USAID, Front Royal, USA. MALASHENKO Y, Inst. of Micro. & Virology, Kiev, USSR. MANNERMAA J, Energy Laboratory, Univ. Oulu, Linnanmaaa, Finland. MANZANARES SECADES P, JEN, Madrid, Spain. MARCHAL R, Inst. Francais du Petrole, Rueil-Malmaison, France. MARATA R, FINAM SRA, Roma, Italy. MARKOVIC M, Projektini Zavod, Zahumska, Yugoslavia. MARTINO C, ENEA, Roma, Italy. MASCHIO G, Dpto di Ingegneria Chimica, Univ. Pisa, Italy. MASSON D, Univ. de Nancy, Vandoeuvre, France. MATARASSO P, Equipe technique de Base du Pirsem—CNRS, Meudon, France. MATERASSI R, CSMA-CNR, Firenze, Italy. MEHRLING P, Lurgi GmbH, Frankfurt/Main, Germany. MEIER D, Inst. Wood Chemistry, Hamburg, Germany. MENGECH A, Nairobi, Kenya. MERIAUX S, INRA, Paris, France. METZGER P, ENSCP, Paris, France. MICHAELIS L, CERG, Cambridge, UK. MICHALET D, GIE Lait-Viande, Lyon, France. MIGLIACCIO N, Soc. Laser Coop. r.l., Napoli, Italy. MILANDE N, Bertin & Cie, Plaisir, France. MILLET F, Agro Developpement, Paris, France. MIRANDA U, CEC, Bruxelles, Belgium. MISHOE J, W, Univ. of Florida, Gainesville, USA. MISSONI G ,AGIP, Rome, Italy. MITCHELL C P, Forestry Dept., Univ. Aberdeen, Scotland. MIYACHI S, Inst. of Applied Micro., Tokyo, Japan. MOLETTA R, INRA, Barbonne, France. MOLLE J-F, CEMAGREF, Paris, France. MONCRIEFF I D, Perkins Engines Ltd, Peterborough, UK.

List of participants

1375

MONTAGNAN G, Dpto di Energetica—Fac. Ing., Pisa, Italy. MORAND P, CNRS, Sevres, France. MORANDINI R, ISS, Arezzo, Italy. MORAZZO S, TEAM, , Rome, Italy. MOREALE A, CEC, Bruxelles, Belgium. MORILLA I, Proser SA, Madrid, Spain. MOULINEY M, L’Air Liquide, Champigny-sur-Marne, France. MUKHERJEE S, Indian Inst. Tech., Kihpragpur, India. MULDER A, Gist-brocades nv, Delft, The Netherlands. NABER J E, RDSL, Amsterdam, The Netherlands. NATIVEL F, Inst. Francais du Petrole, Rueil Malmaison, France. NATUSCH D, Liquid Fuels, Wellington, New Zealand. NAVEAU H, Unit of Bioengineering, Cathol. Univ. Louvain, Louvain la Neuve, Belgium. NEGRO A, Junta de Energia Nuclear, Madrid, Spain. NEMICHE A, CNRS, St Julien L’ars, France. NEWKOME G R, State University, Louisiana, USA. NIEBELSCHUTZ H, Inst. f Garungsgewerbe, Berlin, Germany. NICOLAY D, CEC, Luxembourg. NILSSON A, Lantbrukarnas Riksforbund, Stockholm, Sweden. NOH E-R, Inst. of Forest Genetics, Kyonggido, Republic of Korea. NOLTING E, MAN, Munchen, Germany. NOVAIS J, LNETI, Lisboa, Portugal. NYNS E-J, Unite GEBI, Cathol. Univ. Louvain, Louvain La Neuve, Belgium. OHRT U, Tech. Uberwachnungsverein Rheinland, Koeln, Germany. OKKEN P A, Ivem State Univ., Groningen, The Netherlands. OLLEY G, Elsevier Applied Science Publishers, Barking, UK. ONG K-S, Univ. of Malaya, Kuala Lumpur, Malaysia. OSORE H, ICPE, Nairobi, Kenya. OVEREND R, NRCC, Ottawa, Canada. OVSIANOVSKI, Deutsche Gesellschaft f. Tech. Zausammenarbeit, Eschborn, Germany. OSZUSZKY T, Elekrit, Austria.

List of participants

1376

PALMBERGER B, NEA, Stockholm, Sweden. PALZ W, CEC, Brussels, Belgium. PAPADOPOULOS, Min. of Agr., Athens, Greece. PAQUOT M, FSAE, Gembloux, Belgium. PARISI F, Univ. di Genova, Milano, Italy. PARSBY M, Inst. of Agr. Econ., Kobenhavn, Denmark. PAYNE F A, Clemson Univ., Clemson, USA. PEDERSEN T, Royal Vet. & Agr. Univ., Copenhagen, Denmark. PEGURET A, CERN, Paris, France. PELKONEN P, Univ. of Joensuu, Finland. PELLIZZI G, Inst. of Agr. Eng., Milano, Italy. PEREIRA H, CEF, Lisboa, Portugal. PERERA E D I H, Reading Univ., Reading, UK. PERLOT P, Ste. Beghin-say DRD, Paris, France. PERRIN L, Paris, France. PEUPIER L, SGN, Saint Quentin Yvelines, France. PICCININI S, CRPA, Reggio E, Italy. PIRRWITZ D, CEC, Brussels, Belgium. PLODER W, OeMV ALV, Schwechat, Austria. POTTER W G, SERC, Swindon, UK. PRASAD K, TH Eindhoven, Eindhoven, The Netherlands. PRATT D, Univ. of Minnesota, USA. PREBOIS J-P, IRCHA, Vert-le-Petit, France. PREWORI P, SIDI, Parma, Italy. PRICE R, ETSU, Didcot, UK. PRIER J B, Biomasse Actualites, Paris, France. PYHALTO R P, TRCF, Jyvaskyla, Finland. PYLE L, Imperial College, London, UK. QUADFLIEG H, TUV Rheinland, Koln, Germany. RANGER J, INRA-CNRF , Seichamps, France. RANTA R, CFBT, Helsinki, Finland. REIMERT R, Lurgi, Frankfurt/Main, Germany. REQUILLART V, INRA, Grignon, France.

List of participants

1377

REYNIEIX M, CEMAGREF, Antony, France. RICHARD J-B, CNRS-CRS CHT, Orleans, France. RICHARDSON D, LFTB, Wellington, Australia. RICHTER E, CIBA-GEIGY, Basel, Switzerland. RIEDACKER A, AFME, Paris, France. RIETVELD F, Veg-Gasinstituut NV, Apeldoern, The Netherlands. RINGBLOM U, Alfa-Laval AB, Tumba, Sweden. RINGGER H, Tages Anzeige Redaktion, Zurich, Switzerland. ROBERT P, IDF, Paris, France. ROSILLO-CALLE F, Aston Univ., Birmingham, UK. ROMAN J, Tractionel, Brussels, Belgium. ROSOLIA F, Luwar srl, Azzate, Italy. ROUET P, L’air Liquide, Champigny-sur-Marne, France. ROUSSEAU M, CFP, Paris, France. ROZZI A, Fare-Ter/com—Cre-Casaccia, Roma, Italy. RUEGGER J, European Energy & Environmental Eng., Zurich, Switzerland. RUGG B A, Fac. of Arts & Science, New York University, New York, USA. RUHLE W, Fichtner Cons. Eng., Stuttgart, Germany. SACHS R, Univ. of California, Davis, USA. SADDLER J, Forntem Canada Corp., Ottawa, Canada. SAEZ-ANGULO R M, Junta de Energia Nuclear, Madrid, Spain. SAHRMAN K, TRCF, Jyvaskyia, Finland. SANNA P, Eniricerche, Roma, Italy. SCARAMUZZI G, Soc. Agr. e Forestale, Roma, Italy. SCARZELLA L, Thermoforestali, Savona, Italy. SCHELLER W, Univ. of Nebraska, USA. SCHIEFERSTEINER, Voest Alpine, Linz, Austria. SCHLEISS K, ADER, Montherod, Switzerland. SCHNEIDER J, Hahn-Meitner-Inst., Berlin, Germany. SCHOENSTEIN R, AEES, Laxenburg, Austria. SCHOENER G, RIEEP, Wien, Austria. SCHORGHUBER F, Nied. osterr. Landesregierung, Wien, Austria. SCHORRY R, Lehrstuhl f. Bodenkunde, Munchen, Germany.

List of participants

1378

SCHRECK M, Thyssen, Essen , Germany. SCHULZE LAMMERS P, Landesanstalt f. Landtechnik, Freising, Germany. SCHUTZ P, Wien, Austria. SCHWALD W, Inst. f. Radiochemie/Univ. Innsbruck, Austria. SCULLY J, CEC, Bruxelles, Belgium. SEIDELMANN E, Tullner Zuckerfabrik AG, Wien, Austria. SELIGMAN M, European Parliament, Bruxelles, Belgium. SHANAHAN Y, ITDG, Reading, UK. SILI C, CSMA-CNR, Firenze, Italy. SIMEON C, CEN—VALRHO, Bagnols sur Ceze, France. SINGH, New Delhi, India. SIRONVAL C, Univ. of Liege, Sart-Tilman, Belgium. SKUTSCH M, Twente Univ. of Tech., Enschede, The Netherlands. SMITH D, Eng. and Conserv. Ltd., London, UK. SMITH W, Univ. of Florida, Gainesville, USA. SNOEK H, Grontmij NV, Zeist, The Netherlands. SOLANTAUSTA Y R J O, TRCF, Espoo, Finland. SONNENBERG R, Imbert-Energietechnik, Weilerwist, Germany. SOURIE J-C, INRA, Grignon, France. SOYER N, ENSCR, Rennes-Beaulieu, France. SOZEN Z Z, Studsvik Energieteknik AB, Nykoping, Sweden. SPITZER J, Inst., for Env. Res., Graz, Austria. STERN R, Inst. Francais du Petrole, Rueil-Malmaison, France. STINSON J, TVA, Muscle Shoals, USA. STOCKER, Kernforschunganlage, Julich, Germany. STOLFI N, CREAA, Roma, Italy. STREHLER A, TUMW, Freising, Germany. STRUB A S, CEC, Brussels, Belgium. STURMER H, Tech. Univ. Munchen, Freising, Germany. SULILATU F, TNO-Apeldoorn, The Netherlands. TABARD P, INRA, Clermont Ferrand, France. TAHA A, Univ. of Gezira Wadmedani, Sudan. TANISLY P, Copersucar, Sao Paulo, Brazil.

List of participants

1379

TANTICHAROEN M, King Mongkut’s Inst. of Tech., Bangkok, Thailand. TARDELLA Q, ENEA, Roma, Italy. TATOM J W, Atlanta Univ., Atlanta, USA. TEDESCO M, Consorzio ASI-ENNA, Sicily. TEGGERS H, Rheinische Braunkohlen WERGE AG, Koeln, Germany. TEISSIER—DU—CROS E, INRA, Olivet, France. THEANDER O, Dept. of Chem. & Mol. Biol., Uppsala, Sweden. THEOLEYRE M A, MNE, Paris, France. THONART P, FSAE, Gembloux, Belgium. THOSTRUP P, Crone & Koch, Viborg, Denmark. TILCHE A, ENEA, Bologna, Italy. TOURLIERE S, UNGDA, Paris, France. TRANCHET C, SFFO, Bern, Switzerland. TROSSERO M A, FAO/UN, Roma, Italy. VACCARI M, UNITAR, Roma, Italy. VALENTE, Univ. of Napoli, Italy. VALLINE G, Ersdania 2N, Ferrare, Italy. VALANDUYT E, ACEC Charleroi, Belgium. VAN SWAAIJ W P M, Twente Univ. of Tech., Enschede, The Netherlands. VARAGNAT F, GRET—GERES, Marseille, France. VARGA I, Ministere de l’Indusrie Hongrie, Budapest, Hungary. VASQUE-DUHALT R, Univ. de Geneve, Switzerland. VELLUTI-ZATI S, Confagricoltura, Roma, Italy. VERMANDE P, INSA—LCPAE, Villeurbanne, France. VERRIER D, INRA, Villeneuve d’Asq, France. VIANELLI L, APRE SPA, Roma, Italy. VIGLIA A, AGIPGIZA SPA, Reggio Emilia, Italy. VILPUNNEN P, Energy Laboratory, Univ. of Oulu, Finland. VINCENZINI M, CSMA-CNR, Firenze, Italy. VLITOS A J, WSRO, London, UK. VON SONNTAG C, Max-Plank Inst., Ruhr, Germany. VUILLOT M, CEMAGREF, Lyon, France. WALTER H, Essen, Germany.

List of participants

1380

WANG Z-X, Inst. of Energy Conv., Guangzhou, China. WEILAND P, Inst. Techn. f. Landwirtschaft, Braunschweig, Germany. WEISKOPF H-J, Buse Anlagenbau GmbH, Linz/Rhein, Germany. WEISMANN A F, Bundesministerium f. E, L & F, Bonn, Germany. WELLINGER A, SFRS AG Eng., Taenikon, Switzerland. WIEDENROTH H, VS Zuckerrubenanbauer, Wurzburg, Germany. WIJERATNE M, Agr. Univ., Wageningen, The Netherlands. WILDENAUER F X, Messerschmitt Bolkow Blohm Gmbh, Munchen, Germany. WILHEMSEN G, Agr. Res. Council. of Norway, Norway. WILKENING C L, Kraul & Wilkening & Stelling KG, Hannover, Germany. WILSON H T, Foster Wheeler PP Ltd, London, UK. WILTON B, Univ. of Nottingham, Sutton Bonington, UK. WINTER P, Biomass Energy Inst., Winnipeg, Canada. WOHLMEYER H, AAAR, Wien, Austria. WONGKAEW W, Seameo Biotrop, Bogor, Indonesia. WOOD T, Rowett Res. Inst., Aberdeen, UK. WU WEN, Guangzhou Inst. of Energy Conv., Guangzhou, China. WULFERT K, Inst. Techn. f. Landwirtschaft, Braunschweig Germany. WUENSCHE U, Dept. of Plant Husbandry, Uppsala, Sweden. WURSTER R, EAT Systemtechnik GmbH, Ottobrunn, Germany. ZAID BIN ISA, State Univ. of Ghent, Ghent, Belgium. ZANCHI R, AGIPIZA SPA, Reggio Emilia, Italy. ZAUNER E, Inst. Techn. f. Landwirtschaft, Braunschweig, Germany. ZEEDIJK H, Univ. of Tech., Eindhoven, The Netherlands. ZALMAN P, Nefah. Kibbutz Ind. Assoc. Herzlia, Israel. ZEIMES M, Thyssen Stahl Aktiengesellschaft, Duisburg, Germany. ZGAJNAR A, Inst. za Gozdno in Lesno gospodarstyo, Ljubljana, Yugoslavia. ZIJP T, Twente Univ., Enschede, The Netherlands. ZOBOLI R, Nomisma SPA, Bologna, Italy. ZUBR J, The Royal Vet. & Agr. Univ., Copenhagen, Denmark. ZWIEFELHOFER H P, UTB AG, Buchs, Switzerland.