Energy application of biomass

ENERGY APPLICATIONS OF BIOMASS

The proceedings of the National Meeting on Biomass R & D for Energy Applications held 1–3 October 1984 at Arlington, Virginia, USA.

ENERGY APPLICATIONS OF BIOMASS Edited by

MICHAEL Z.LOWENSTEIN Solar Energy Research Institute, Golden, Colorado, USA

ELSEVIER APPLIED SCIENCE PUBLISHERS LONDON and NEW YORK

ELSEVIER APPLIED SCIENCE PUBLISHERS LTD Crown House, Linton Road, Barking, Essex IG11 8JU, England This edition published in the Taylor & Francis e-Library, 2005. “To purchase your own copy of this or any of Taylor & Francis or Routledge’s collection of thousands of eBooks please go to www.eBookstore.tandf.co.uk.” Sole Distributor in the USA and Canada ELSEVIER SCIENCE PUBLISHING CO., INC. 52 Vanderbilt Avenue, New York, NY 10017, USA WITH 43 TABLES AND 96 ILLUSTRATIONS © ELSEVIER APPLIED SCIENCE PUBLISHERS LTD 1985 British Library Cataloguing in Publication Data Energy applications of biomass 1. Biomass energy I. Lowenstein, Michael Z. 662′.6 TP360 Library of Congress Cataloging in Publication Data National Meeting on Biomass R & D for Energy Applications (1984: Arlington, Va.) Energy applications of biomass. ‘Proceedings of the National Meeting on Biomass R & D for Energy Applications, held 1–3 October 1984 at Arlington, Va.’ Includes bibliographies and index. 1. Biomass energy—Congresses. I. Lowenstein, Michael Z. II. Title. TP360.N278 1984 662′.8 85–25259 ISBN 0-203-21085-9 Master e-book ISBN

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FOREWORD

The National Meeting on Biomass R&D for Energy Applications was supported by the Council of Biomass Energy Technology Sponsors (CBETS) and was organized and hosted by the Solar Energy Research Institute (SERI). The Biomass Energy Research Association (BERA) provided technical assistance. CBETS was founded on July 14, 1983, as a forum for communication and cooperation among managers of the major biomass energy programs in the United States, including various federal and state government organizations, industry institutes, and associations. Council membership includes the American Public Power Association; the Electric Power Research Institute; the Gas Research Institute; the Hawaii Natural Energy Institute; the Legislative Commission on Minnesota Resources; the National Rural Electric Cooperative Association; the New Mexico Energy Research and Development Institute; the New York State Energy Research and Development Authority; the North Carolina Alternative Energy Corporation; the Tennessee Valley Authority; the U.S. Department of Agriculture; and the U.S. Department of Energy. The Council’s affiliate members include the American Gas Association; the BioEnergy Council; the Biomass Energy Research Association; the Fiber Fuels Institute; the National Wood Energy Association; the Renewable Fuels Association; and the Wood Heating Alliance. CBETS has two primary objectives: programmatic coordination to maximize the value and usefulness of biomass energy research and development activities sponsored by Council members; and timely and effective transfer of the results of biomass energy technology advances to industry and other interested parties. The national meeting held in Arlington, Virginia, on 1–3 October 1984, was one of CBETS’s continuing efforts aimed at achieving the goal of timely technology transfer. Attendees represented industries, colleges and universities, federal and state governmental agencies, and foreign countries. Each of the three sections in the following Proceedings has a specific focus. Section 1 contains discussions of issues important to the various sectors of the biomass energy community; Section 2 discusses in detail the research interests of biomass energy sponsors; and Section 3 provides highlights of significant biomass energy research efforts.

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The organizers thank all the authors for having contributed their reports and the CBETS members for initiating and assisting with the planning that led to the success of the meeting. Golden, Colorado M.Z.Lowenstein August 1985

CONTENTS

Foreword

SECTION I: ISSUES OF IMPORTANCE TO BIOMASS ENERGY RESEARCH 1.

Renewable Resources for Fuel and Materials M CALVIN (University of California, Berkeley, USA)

2

2.

What is the Biomass Energy Resource Base and at What Price? E S LIPINSKY (Battele Columbus Laboratories, USA)

10

3.

Biomass for Food or Fuel : a World Problem? D O HALLP J de GROOT (King's College, London, UK)

17

4.

A Federal-State R & D Partnership : Cooperative State and Federal Support for Regional Technology I L WHITE (New York State Energy Research )

30

5. Biomass for Energy in the Forest Products Industry 36 J L KULP Weyerhaeuser Company, Tacoma, Washington, USA SECTION II: RESEARCH INTERESTS OF BIOMASS SPONSORS 6.

Bio-Energy Programs at the US Department of Energy M GUTSTEIND RICHARDS

46

7.

TVA Biomass Fuels Program J M STINSON

55

8.

Overview of USDA Energy Policy Perspectives E E GAVETT

63

9.

The Forest Service’s Woody Biomass Program F B CLARK

66

Energy-Related Activities of the Canadian Biomass Research Program S HASNAINR P OVEREND

75

10.

ix

11.

The Brazilian Alcohol Program L C MONACO

89

12.

Progress in the California Energy Commission Biomass Demonstration Program R TUVELL

100

13.

New York State Biomass Energy Research J B HOLLOMON

114

14.

GRI’s Program on Methane from Biomass and Wastes P H BENSON

120

15.

Public Power Research in Bioenergy M K BERGMAN

130

16.

The Use of Biomass for Energy Production at America’s Rural Electric Systems W PRICHETT

135

SECTION III: BIOMASS ENERGY RESEARCH PROJECTS 17.

Intensive Microalgae Culture for Production of Lipids for Fuel R MCINTOSH

140

18.

Technology for the Commercial Production of Macroalgae J H RYTHER

147

19.

The Integration of Biogas Production with Wastewater Treatment T D HAYESD P CHYNOWETHK R REDDYB SCHWEGLER

158

20.

Review of Biomass Conversion Technology Research D L KLASS

169

21.

Conversion of Lignocellulosic Biomass to Ethanol L J DOUGLAS

185

22.

Comparison of Alternatives for the Fermentation of Pentoses to Ethanol by Yeasts T W JEFFRIES

197

23.

Novel Developments in Bioreactor Design and Separations Technology C D SCOTT

219

24.

Diesel Fuel Via Indirect Liquefaction

229

x

J L KUESTER 25.

Thermal Conversion of Biomass: Progress and Prospects G F SCHIEFELBEIN

240

26.

Installation of a 3-MW Wood Burning Gas Turbine System at Red Boiling Springs, Tennessee J T HAMRICK

255

27.

Scale-up of a High-Throughput Gasifier to Produce Medium-BTU Gas from Wood H F FELDMANM A PAISLEYH R APPELBAUM

266

List of Attendees

275

SECTION I Issues of Importance to Biomass Energy Research

RENEWABLE RESOURCES FOR FUEL AND MATERIALS M.CALVIN* *University of California, Berkeley

SYNOPSIS As a result of the depletion of our supplies of oil and gas, which were created by the process of photosynthesis, it is now necessary to develop renewable fuels for the future because of the environmental problems associated with the expanding development of coal and oil shale, particularly the carbon dioxide problem. The most immediate source of renewable fuels is annually growing green plants, some of which produce hydrocarbons directly. We can select new plant sources that have high potential for production of liquid fuels and chemicals. Suggestions are made for the modification of both the product character and the productivity of the plants. Ultimately a totally synthetic device will be developed for the conversion of solar quanta into useful chemical form, completely independent of the need for arable land. 1 INTRODUCTION We are here largely because of the awakening that occurred in 1974–75 as a result of the action of the OPEC nations, and we are now more conscious of energy problems than we once were. American energy use for 1983 (Fig. 1) still emphasized fossil fuel energy (natural gas, coal, and oil) as the major sources. These are basically the products of ancient photosynthesis when plants were laid down and converted from primarily carbohydrate into carbon, hydrocarbon, and gas. The other energy sources (nuclear, geothermal, and hydro) are relatively minor. How long can we expect fossil fuel energy to continue as a major source? One of the simplest ways of answering that question is to examine the energy costs of finding and extracting a barrel of oil. One way of expressing that cost is to determine the number of barrels of oil per foot of well drilled, which was 35 in 1945 ; this quantity in 1975 was less than 18. Another way of expressing these same data is to say that the energy cost today for finding and extracting that barrel of oil has risen, and we are very close to the edge of energy economy. A

RENEWABLE RESOURCES FOR FUEL AND MATERIALS 3

barrel of oil contains 6 million Btu, and when drilling and exploration uses more energy than the energy content of the barrel itself, it becomes questionable economically to sell that barrel of oil (Ref. 1). 2 ECOLOGICAL CONSTRAINTS Major coal producers in the three major coal-producing countries of the world (the Soviet Union, China, and the United States) consider that coal is a viable energy source to replace petroleum and natural gas, and it is likely that in the planned economies, at least, coal will become the major energy source. A reason for concern is that even today, when coal represents less than 25% of the total energy usage, our biosphere cannot absorb the carbon dioxide at the rate of injection that burning fossil carbon in all its forms produces (Refs. 2, 3). Today the C02 is removed from the atmosphere at roughly half the rate at which it is injected. If coal production increases markedly, the removal of C02 from the atmosphere will be a still smaller fraction of what we inject, meaning that the rate of rise of the CO2 concentration in the atmosphere will double. The C02 concentration has risen from 295 ppm in 1880 to 330 ppm in 1980, and if the use of coal greatly increases, the C02 concentration will rise at an even more substantial rate. The amount of C02 produced from the combustion of coal is roughly twice that from petroleum or natural gas because combustion of coal burns carbon only, and not carbon and hydrogen. The rising C02 level produces the greenhouse effect as a result of the peculiar properties of the C02 itself. Concomitantly, the temperature measured at various places on the earth’s surface has also been rising in the last 100 years, increasing about 0.4¼C from 1860 to 1980, which represents a very large rise (Ref. 4). One of the best ways to show the result of this increase in temperature is to examine the satellite photographs of the South Polar ice cap. One can estimate the amount of ice that has disappeared in the last 20 years as about 1.2 million km2 from an approximate total of 12 million km2 (Ref. 5). Thus the global mean sea level has been rising about 2 to 3 mm per year during the last 50 years, compared to about 1 mm per year during the previous half-century (Ref. 6). A recent report by the Environmental Protection Agency (Ref. 7) projects a global rise of sea level between 144 cm (4.8 ft) and 217 cm (7 ft) by the year 2100, with the low estimate of 56 cm (1.9 ft) and high of 345 cm (11 ft). Also, along most of the Atlantic and Gulf Coasts of the United States, the predicted rise will be more than the global average; i.e., 18 to 24 cm (0.6 to 0.8 ft). It is therefore obvious that to alleviate the trend of rising C02 concentration and its subsequent problems, an alternate energy source must be found (Refs. 8, 9). The best annually renewable source of energy is the green plant, and we are looking for green plants that can produce hydrocarbons from carbohydrates. There are many such plants, in several different families, and they are found all over the world.

4 ENERGY APPLICATIONS OF BIOMASS

3 BIOMASS FOR RENEWABLE ENERGY As you know, the primary productivity of biomass is carbohydrate (sugar, starch, and wood) which must be converted into a much more concentrated form, such as hydrocarbon. One of the first efforts has been made in Brazil where sugar cane has been used directly as an energy source as well as a source of carbohydrate. In 1983, 4.3 x 109 L of fermentation alcohol were produced from sugar cane on the autonomous sugar cane plantations. This fermentation alcohol is used directly in automobiles and is a chemical feedstock for Brazilian industry. In Puerto Rico an energy cane has been developed that can be used not only for its sugar content but also for its total energy content to fire the boilers in heating plants on the south coast of Puerto Rico (Ref. 10). Some plants, such as Euphorbia lathyris, a member of the Euphorbiaceae family, produce hydrocarbons directly from C02. Plantations for E. lathyris have been developed not only in the United States (Ref. 11) but in Spain as well (Ref. 12). Euphorbia produce 8% oil and 20$ sugar upon extraction of the whole plant. Another species, Asclepias speciosa (milk-weeds) , produces approximately the same combination. That species has been studied extensively in Utah (Ref. 13). The seed oils are also being developed (Ref. 14). For example, sunflower seeds produce an oil that can be used directly in a mixture as a diesel fuel or easily converted by transmethylation to a diesel fuel without any additives by replacing the glycerine of the triglyceride with methanol. The best commercial seed oil producer is the palm, which is being grown on a large scale in Brazil and Malaysia as a source of oil for fuel and materials. The processing sequence to recover oil (terpenoids) and fermentable sugars from E. lathyris (Fig. 2) was worked out in the laboratory and is calculated here for 1000 dry ton/day of material, which would yield 80 ton of crude oil and 200 ton of fermentable sugars that could produce 100 ton of alcohol (Refs.15, 16). About 500 ton of bagasse are used to run the process, with a resulting 200 ton of bagasse that could be used to distill the alcohol. The fermentation alcohol that is a by-product is, of course, a starting point for an entire petrochemical industry. The whole process is self-contained. Studies of E. lathyris have shown that while it is possible to crack the material from this plant, it might be more economical to determine whether this species and its products contain more useful materials for chemical feedstock production (Ref. 16). The crude oil from the E. lathyris has been converted, using special zeolite catalysts, to the usual products such as olefins, paraffin, aromatics, and nonaromatics. This confirms the desirability of the products of E. lathyris as possible raw materials to substitute for crude oil. It now appears that a price of $100/barrel for the oil from E. lathyris, only 2.5 times more than the 1982 OPEC price per barrel of crude, might be a realistic projection. The price will almost

RENEWABLE RESOURCES FOR FUEL AND MATERIALS 5

certainly turn out to be less when larger-scale energy agriculture operations are commenced. The plant chemicals that constitute the black oil are mostly triterpenes (C30), sterols, and sterol esters, which can be cracked to make desirable products. The biosynthetic route to the terpenes in plants such as E. lathyris has not been completely determined, but it is probably similar to that for rubber biosynthesis except that the end products from the E. lathyris are lower molecular weight compounds. The route is from sugar via the glycolytic cycle to pyruvate, which then builds up to mevalonic acid and goes on to give isopentylpyrophosphate (IPP). The IPP polymerizes into a variety of isoprenoids, and in E.lathyris the material goes through the isoprenoid biosynthetic pathway to squalene (C30), which is then folded up to make the C30 terpenoid (steroidal) alcohols that are the greater percentage of the oil. We also looked for trees that might produce oil directly when they were tapped or had fruits extracted. Such an agronomy would conserve soil and water. One tree in Brazil, the Copaifera multijuga of the family Leguminosae, does exactly this. It grows in the Amazon area of Brazil, and the material from the tree can be used directly in a diesel engine. It is tapped twice each year and produces 20 L of cyclic sesquiterpene oil per tap. The Brazilians are now beginning plantation experiments with these trees to improve yields of oil (Ref. 17). Another family of trees, the Pittosporaceae, has representatives in various parts of the world. In the Philippines the fruit of the Pittosporum resiniferum is used by the natives for illumination and for its oil content. The fruit, about the size of a prune, contains about 50% terpenes of three different components—myrcene, alpha-pinene, and limonene (Ref. 18). These three components can be used almost directly as cracking stock or fuel. A species that grows in California, Pittosporum undulatum, has smaller fruits with slightly different oil content. Another tree, Jatropha curcas, which is a member of the Euphorbiaceae family, is being cultivated on a large scale in Thailand; this tree is closely related to the castor bean. Another type of plant that does not involve agricultural land directly and which produces hydrocarbon is the microalga Botryocoocus braunii, which can grow in either fresh or salt water. The algae secrete an oil that is roughly 50%– 70% of the dry weight and is mostly C30, which can be cracked in the same way as crude oil (Ref. 19). The energy yields for different plants are shown in Table 1. It is clear that the most important component in the table is the energy in liquid fuels as hydrocarbons in millions of Btu per acre per year per inch of water. There is no question in my mind that it would be possible to introduce into the United States a substantial energy agriculture, if there were the right type of economic incentives for such a biomass production (Ref. 20). The projections for energy use in the United States for the year 2000 (Fig. 3) for the first time include biomass as a significant component of the total, representing about 6% of the total energy requirement. This is an important

6 ENERGY APPLICATIONS OF BIOMASS

indication of what is perceived to be realizable in the next 20 years. I believe that biomass will represent a greater component than the 6% projected. One way to encourage this process would be to have farmers set aside a part of their land to grow a plant that produces a fuel of the correct type to run agricultural machinery. This would be a return to the practice of 100 years ago when farmers used part of their farms to produce the energy needed, mostly as carbohydrate (grass) for animal feed.

TABLE 1

XBL 849–3892 ACKNOWLEDGEMENTS The work described in this paper was supported, in part, by the Assistant Secretary for Conservation and Renewable Energy, Office of Renewable Energy, Biomass Energy Technologies Division of the U.S. Department of Energy under Contract No. DE-AC03–76SF00098.

RENEWABLE RESOURCES FOR FUEL AND MATERIALS 7

REFERENCES 1. 2. 3. 4. 5. 6. 7.

8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20.

Hall, C.S., and Cleveland, C. J. Science, vol. 211, 567, 1981. Clark, W.E. (ed.). ‘Carbon dioxide review: 1982’, Oxford University Press, New York, 1983. National Academy of Sciences. ‘Changing climate’, Report of C02 Assessment Committee, Washington, D.C., 1981. Smagorinsky, J., (ed.). ‘Carbon dioxide and climate: a second assessment’, National Academy of Sciences, Washington, D.C., 1982. Kukla, G. and Gavin, J. Science, vol. 214, 321, 1981. Gornitz, V., Lebedeff, S. and Hansen, J. Science, vol. 215, 1611, 1982. Hoffman, J.S., Keyes, D. and Titus, J.G. ‘Projecting future sea level rise: methodology, estimates to the year 2100 and research needs’, Environmental Protection Agency, Washington, D.C., 2nd ed., 1983. Calvin, M. Science, vol. 219, 21, 1983, and references cited therein. Calvin, M. J. Appl. Biochem., vol. 6, 3, 1981. Alexander, A.G.‘The energy cane alternative to sugar planting’, report, 1983. Calvin, M. BioScience, vol. 29, 533, 1979. Ayerbe, L., Tenorio, J.L., Ventas, P., Funes, E. and Mellado, L. Biomass, vol. 4, (5), 37, 1981. Adams, R.P. and Mc Chesney, J. D. Econ. Bot., vol. 37, 207, 1983. Princen, L.H. ‘Fuels and chemicals from oil seeds: technology and policy options’, Econ. Bot., vol. 37, 478, 1983. Nemethy, E.K., Otvos, J.W. and Calvin, M. J. Amer. Oil. Chem. Soc. vol. 56, 957, 1979. Nemethy, E.K., Otvos, J.W. and Calvin, M. Pure Appl. Chem., vol. 53, 1101, 1981. Calvin, M. Die Naturwissen., vol. 67, 525, 1980. Nemethy, E.K. and Calvin, M. Phytochem. vol. 21, 2987, 1982. Wolf, F.R., Nemethy, E.K., Blanding, J.H. and Bassham, J. A. Phytochem., in press. Calvin, M. Pure Appl. Chem., vol. 50, 407, 1978.

8 ENERGY APPLICATIONS OF BIOMASS

Fig. 1. American energy use in 1983

Fig. 2. Conceptual processing sequence to recover oil and fermentable sugars from Euphorbia lathyris

Fig. 3. Projections for energy flow in the United States for the year 2000

RENEWABLE RESOURCES FOR FUEL AND MATERIALS 9

WHAT IS THE BIOMASS ENERGY RESOURCE BASE AND AT WHAT PRICE? E.S.LIPINSKY* *Battelle Columbus Laboratories

After more than ten years of study, by numerous organizations, that have led to reports that must weigh tons, the size of the U.S. biomass resource base still is largely unknown and estimates are highly uncertain. The reason for this ambiguity is not difficult to trace. Unlike fossil fuel resources that are discovered, biomass resources are manufactured by photosynthesis. The principal resource base is land of appropriate quality. But such land can be used for other purposes. Furthermore, the quantity of biomass resource that can be produced on a given land (or aquatic) area varies with the technology employed to grow the biomass. For these reasons, the size of the resource base cannot be known with a great degree of precision or accuracy. Despite the uncertainties, the size of this resource base is important for decisions to be made by governments and industrial organizations. If the biomass resource base were barely sufficient for food and fiber production, it would be improper to divert some of this precious resource to fuel and chemical use. On the other hand, if the resource base is likely to be underutilized and low prices are likely to prevail because of farm surpluses, an additional set of major uses could strengthen the entire biomass system. 1 BIOMASS RESOURCE ABUSE Certain syndromes are caused by abuses of biomass; they need to be confronted and banished so that the potential of biomass can be measured. The abuses are more serious than they sound. 1.1 Quadromania Biomass energy systems tend to be small compared with nuclear and coal-based energy systems. This is one of the advantages of biomass. Quadromania is insistence on multiple quad output from all biomass energy systems. Quadromania is unrealistic and impedes progress because it encourages rampant extrapolamania.

WHAT IS THE BIOMASS ENERGY RESOURCE BASE AND AT WHAT PRICE?

11

1.2 Rampant Extrapolamania Not only government officials and private sector executives have biomass abuse problems. Those engaged in both technological and economic research and development activities must share the blame for biomass abuse. Rampant extrapolamania takes on many manifestations. Here are a few examples. Hyperyieldemia. The researcher obtains a high yield with a small plot that is tended regularly by graduate students who water it, weed it, and remove every insect that approaches it. This same high yield is extrapolated to all farmland that is considered to be appropriate for growing the crop at all. The yield estimate should be reduced as the quantity of land to be devoted to the crop is increased. Hyperareomania. Hyperareomaniacs find a crop with good yield and project a large number of quads of energy from the crop by using every plot of land that they can in the United States to grow the crop, even if the land area is needed for food, paper products, highways, and cities. Liebnitz’s Syndrome.Liebnitz stated that the world was getting better and better. The comparable biomass abuser takes relatively low yields and/or high costs and extrapolates to unproven improvements to obtain a rosy future. Bunyan’s Syndrome.Many of those who extrapolate the use of forest residues for biomass energy production forget that substantial transportation obstacles impede delivery of these products to central plants for efficient production of fuels or chemicals. These biomass abusers assume that Paul Bunyan’s free time and energy is going to carry the forest residues to the central location. Chronoverleukemia. New biomass technologies may take 5 to 15 years of steady development before the first commercial facility is built. Then, companies tend to observe the success or failure of the first one or two plants for years before rapid construction of an entire industry ensues. The time required for initiating such an industry frequently is overlooked. 2 PRICE/VOLUME RELATIONS Realistic estimates of biomass resource size need to begin and end with estimates of realistic prices. Recent Gas Research Institute studies, (Refs. 1, 2) indicate that: • The gas industry is seeking to have gas available from biomass for approximately $6.00/106 Btu in the year 2000 (1984 $). • Approximately half of the gas cost is likely to be consumed in processing the biomass to methane, leaving about $3.00/10 Btu for biomass cost.

12 ENERGY APPLICATIONS OF BIOMASS

These price considerations are not to be considered permanent, but they provide broad guidelines as to what constitutes biomass resources that are likely to be exploited versus those that are likely to be ignored. Given the energy content of a crop (10 Btu per ton), the crop’s likely yield in a given geographical area (tons/year), and the guidelines for what gas companies might pay ($/ton), an estimate of revenues for farmers or forest managers can be derived ($/acre year). This revenue can be compared with agronomic or silvicultural costs of managing the land for this purpose; in agricultural circles this comparison is known as a “crop production budget,” which is the sum of the cost of the seed, fertilizer, and other inputs plus the cost of land and capital plus a reasonable charge for labor and profit. If the revenue to be obtained by selling biomass is likely to exceed the crop production costs, biomass production for fuels or chemical applications becomes interesting. It still may not win out over alternatives such as growing crops for food or fiber applications. However, any positive value for revenue over crop production budget costs is likely to receive attention at this time when agricultural profits are not outstanding. 3 AN EXAMPLE: CORN/SOYBEAN LAND AS A BIOMASS RESOURCE BASE More than 150 million acres now are devoted to production of corn and soybeans in the U.S. grain belt. Most of the corn/soybean farmers are making small profits at best, and enough have been losing money consistently to cause widespread alarm. Therefore, corn/soybean farmers could be quite interested in production of alternative crops for energy production. Applying the simple relationships suggested in the previous section of this paper, the following conclusions can be drawn. • Crop production budgets indicate that corn/soybean farmers need about $300 per acre of revenue, preferably more. • If the biomass energy buyer plans to convert the biomass into methane that has value of $3.00/10 Btu of methane allocated for biomass, and if each ton of biomass provides 10×106 Btu of methane, then one ton of biomass is worth $30 to a natural gas utility. • Given that the farmer needs $300 of revenue and will get $30 per dry ton, then the required biomass yield is 10 dry tons per acre per year. A yield goal of 10 dry tons per acre in the grain belt is higher than yields obtained with conventional corn grain or silage corn; however, sweet sorghum can produce such yields in at least part of the grain belt. Therefore, this “back of the envelope” calculation helps to clarify the type of crop that might be useful on current corn/soybean land for biomass fuel purposes.

WHAT IS THE BIOMASS ENERGY RESOURCE BASE AND AT WHAT PRICE?

13

One of the reasons that such a high yield is required for natural gas production is that the lignin contained in the biomass makes no contribution to natural gas production. This constraint does not apply to biomass grown for combustion to generate steam and electricity. Because these buyers might purchase low-sulfur coal instead of biomass for approximately $2/10° Btu, they might not be willing to pay $3 for biomass. However, many forms of biomass produce approximately 15 x 106 Btu/ton. At $2.50/106 Btu, the allowable biomass cost would be $37.50/ ton. With the needed revenues set at $300/acre, a yield of 8 tons/acre year could be tolerated. A much greater percentage of grain belt land could yield 8 tons/acre year than could yield 10 tons/acre year. The preferred crop might be a variety of sorghum, but silage corn or other crops also may be appropriate. The size of the biomass resource base that would be created by diverting part of the corn/soybean land to energy crops is difficult to estimate for several reasons. As land is diverted from corn and soybeans to energy crops, their price will rise and thus reduce the attractiveness of producing energy crops. On the other hand, gas and electric utilities could offer long-term contracts to farmers that could free them from the vicissitudes of the corn/soybean business. Considering the volatility of the corn/soybean prices, 10%–20% seems to be the maximum that might be diverted to energy crops and 5%–10% appears to be practical in a non-energy-crisis situation. The quantity of biomass thus made available would be on the order of 120 million tons per year, which is equivalent to about 1.8 quads. 4 OVERALL BIOMASS POTENTIAL Using methods that are analogous to those described for corn/ soybeans, the overall biomass potentials shown in Table 1 were derived. The entries other than corn/soybean land need to be explained briefly. Table 1: Overall biomass potential

Corn/soybean land Diverted cropland Latent farmland Agricultural residues Forest biomass Total

106 tons/yr

input quads

120 100 100 50 200 570

1.8 1.5 1.5 0.8 3.0 8.6

• Diverted cropland is defined as the acreage that farmers are paid to leave fallow so that prices of grains and other major commodities will not be reduced too much. This land is good cropland but generally not quite as good

14 ENERGY APPLICATIONS OF BIOMASS

as the land in production. In recent years the diverted cropland has ranged from about 16 to 80 million acres per year, and the program costs taxpayers billions of dollars per year. Production of 100 million tons per year of biomass on this land could save taxpayers money and reduce the federal budget deficit. • Latent farmland is land that currently is in pasture, rangeland, or forests. This land is reasonably level and is of sufficiently high quality to be reclaimed as farmland. However, it is less likely to be used because it may not be controlled by those interested in energy crops. • Agricultural residues total approximately 450 million tons/year, but only a small fraction is believed to be concentrated enough in its availability to be worth collecting, especially considering the potential for soil erosion when it is removed. The degree of geographical concentration of this residue is illustrated in Fig.1. The forest biomass resource potential appears hugh because the inventory is growing every year in all geographical areas in the United States except for the Pacific Coast (Table 2). Furthermore, substantial percentages of the trees that currently are harvested are not managed or put to good use. In addition, considerable progress has been made in recent years in developing silvicultural plantations that have potential for high yields of biomass on a sustainable basis. When relatively conservative discounts Table 2: Growing stock inventories of trees (million dry tons) region

1976

North 2,850 South 3,230 Rocky Mountain 1,497 Pacific Coast 3,552 United States 11,130 Source: USDA—Forest Service 1982.

1990

2000

3,603 4,003 1,615 3,124 12,346

4,030 4,435 1,693 3,043 13,201

are taken for the numerous problems that are involved in growing, collecting, and transporting forest biomass, there still appears to be an opportunity for 200 million tons per year, or approximately 3 quads. A major issue arises as to whether it is legitimate to add together the items shown in Table 1 to obtain a total energy potential of almost 9 quads. In the opinion of this author, using the total of these possibilities would be a form of biomass abuse. Only an extreme energy crisis could or should mobilize this overall biomass potential. It is more likely that one, two, or three of the alternatives will prove to be viable and will gain the attention and interest of

WHAT IS THE BIOMASS ENERGY RESOURCE BASE AND AT WHAT PRICE?

15

Fig. 1. Number of states with indicated annual production of agricultural residues

those developing biomass energy. The others will remain latent until the economics or technology changes. Currently, there is considerable pressure to reduce the federal budget deficit and to help corn/soybean farmers. Therefore, the “corn/soybean land,” “diverted land,” or possibly both (which are interrelated in any event) could be mobilized. The forest products industry is making considerable progress in making its own energy by managing its biomass resource steam and electricity for captive use (Ref. 3). The momentum thus gained may be extrapolated into sale of more electricity to the grid on a commercial basis in areas that have high avoided electricity costs and large biomass resources. 5 CONCLUSIONS This author believes that biomass has considerable potential as a source of fuels and chemicals. The overall potential is the sum of many financially small and local decisions—a situation that may be frustrating for government planners but is actually an assurance of ultimate success. We all need to recognize that government agencies strive for large-scale and widespread use of results, biomass researchers strive for high yields, industry strives for profits, and bankers strive for safety of capital. Pursuit of these goals is not biomass abuse but being blinded by these goals is the source of biomass abuse.

16 ENERGY APPLICATIONS OF BIOMASS

6 ACKNOWLEDGEMENTS The author thanks the Gas Research Institute and Electric Power Research Institute for partial support of the research described in this paper. REFERENCES 1.

2.

3.

Mishoe, J.W., Boggess, W.G. and Kirmse, D.W. ‘Biomet: A simulation model for study of biomass to methane systems’, Preprints of the 1984 International Gas Research Conference, 459–463, Aug. 1984. Lipinsky, E.S., Young, B.A., Sheppard, W.J. and Jenkins, D.M. ‘Review of the potential for biomass resources and conversion technology status’, Preprints of the 1984 International Gas Research Conference, 440– 450, Aug. 1984. Lipinsky, E.S. and Anson, D. ‘Research and development opportunities’, in Proceedings: EPRI/TVA Workshop on the Use for the Generation of Electric Power, EPRI AP-3678, Sept. 1984.

BIOMASS FOR FOOD OR FUEL: A WORLD PROBLEM? D.O.HALL and P.J.DE GROOT* *Kings College, London

The overuse and undersupply of biomass is currently a serious problem and potentially a greater long-term danger than ready lack of food. Today 14% of the world’s primary energy is derived from biomass (including fuelwood)— equivalent to 20 million barrels of oil/day. Predominant use is in the rural areas of developing countries where half the world’s population lives; e.g., Nepal and Ethiopia derive nearly all, Kenya 75%, India 50%, China 33%, Brazil 25%, and Egypt and Morocco 20% of their total energy from biomass. A number of developed countries also derive a considerable amount of energy from biomass; e.g., Sweden 15%, Canada 5%, and the United States and Australia 3% each. European-wide studies have shown that about 5%–10% of Europe’s energy requirements could be met from biomass by 2000. An especially valuable contribution could be in the form of liquid fuels, now so prone to fluctuating price and supply and to large import costs. The success of alcohol fuel schemes in Brazil and Zimbabwe, for example, with their net energy and economic benefits, needs to be closely analysed. Worldwide government expenditure on biomass energy systems is over $2 billion a year, while the costs and subsidies of surplus food production are over $60 billion a year. The world currently produces 10%–20% more food than is required to feed its 4.5 billion people an adequate diet. Over the last 30 years per capita food production has increased by 0.8% per annum worldwide. The only decrease has occurred in Africa. In North America and Europe, the main problem with food is its easy overproduction and general overconsumption. And surpluses may increase because of economic and political factors and other trends such as changes in Western diets, substitution of commodities such as sugar, and rapidly increasing productivity of plants. New diets and other biotechnical changes will have long-term socioeconomic consequences. However, there are now an estimated 450 million undernourished people, mostly in Asia and Africa. Simplistically, if either the available food production was increased by 1.5% (equivalent to about 25 million t of grains) and this food was distributed equitably to those who need it, or only 10% of the developed countries’ grain production was diverted away from animals to humans, there would be no undernourished people in the world.

18 ENERGY APPLICATIONS OF BIOMASS

The biomass resources available, the potential for greatly increased productivity, the effect of large agricultural surpluses, especially in North America and Europe, and other factors such as food and land use competition, subsidies, changing diets away from animal products and sugar, which will influence biomass energy schemes worldwide, are hotly debated. But the essential question is how to achieve both food and biomass fuel production locally and on a sustainable basis. Both are required—thus planning provisions of the appropriate infrastructure and incentives must be provided. Increased support of research and development, training, and firm establishment of top priority to agriculture and forestry are essential in many countries of the world— if necessary, with significant help from abroad. 2 WOODFUEL According to the FAO, in 1978 woodfuel provided over 20% of all the energy used in the developing countries, and 5.4% of world energy consumption (15×106 TJ from a global consumption of 257×106 TJ). Woodfuel accounted for 60% of all timber use, not including industrial wastes recycled for energy. More people now rely on woodfuel than in the past. Some 1160 million people, more than half of those who are totally dependent on biomass, were using up fuelwood at a faster rate than it was being replaced, and even then often failing to meet their minimum requirements (Ref. 1). In the rural areas women and children have to devote an ever increasing amount of time to collecting wood, time that could be spent tending crops. If 3,000 million people are not to suffer a severe shortage or a deficit of woodfuel in 15 years, 50 million hectares of trees will have to be planted. This will cost $50,000 million. If government and aid agencies can keep to their present targets, between 5% and 10% of this amount will be planted (Refs. 2, 3, 4). The initial response of concerned international agencies and governments has been to spend money (estimated at $1 billion) unwisely in order to show some visible sign of action. Long-term requirements have often been neglected, and there has been a disregard for the future implications of any action that has been taken. What is required is sustained high-level funding, not short-term spurts of short-sighted activity. Agroforestry could play an important role in helping to end the woodfuel crisis. The aim is to devise a combination of woody shrubs or trees and agricultural crops and/or animals that will give the highest sustainable production that the land and the local climate will support. This multi-cropping approach is useful in regions with fragile soils that are susceptible to degradation and erosion, but it has been successfully employed on fertile land. Basic research is urgently required on the usefulness of various trees in different localities and on the economics of different agroforestry systems, as perceived by the local people. The developement of agroforestry systems is held back precisely because it is

BIOMASS FOR FOOD OR FUEL : A WORLD PROBLEM? 19

involved with “peasant agriculture” and therefore retains very low status, meagre funds, and inadequate research (Refs. 2, 4, 5). 3 FOOD PRODUCTION The amount of energy the world obtains from food and fuel in a year represents only about 10% of the annual photosynthetic energy storage. In other words, photosynthesis already stores ten times as much energy as the world requires (90% of it in trees)—an amount equivalent to our proven fossil fuel reserves (Refs. 6,8). Human croplands represent only 0.53% of all standing phytomass and currently occupy 11% of all land area. The world’s flora has over 1 million species, but only 10 annual grains (rice, wheat, corn, sorghum, millet, rye, barley, common bean, soybean, and peanut) now provide 80% of the plant nutrients we consume, and 75% (dry matter) of annual food production (Ref. 5). Between 1950 and 1980 world food production doubled. The rate of increase in grain production per capita slowed since 1970, reaching a peak in 1978, then actually declining for two years. For the most part this was due to governments in Canada and North America paying farmers not to grow grain in an effort to maintain world prices, to bad weather, and to poor harvests in Russia. Since 1980, when world stocks of grains stood at 186.7 million t, the trend has actually been a steady increase. World grain stocks will be around 206.9 million t in 1984–85. The grain harvest for 1984 is expected to be 1600.9 million t with record and near record crops in the United States and the European Economic Community (EEC) (Refs. 14, 7). Despite the increases in agricultural production in the developing world— 120% since the early 1950s—the average per capita increase in food has been modest, while in Africa (except white South Africa) there has actually been a continued decline in food supply of around 15% (Refs. 7, 8). Because of its more modest population increases, the developed world has seen a substantial upward trend in per capita food production. Crop yields expanded at three times the rate of those in the developing world. Figures for both corn and wheat yields in the United States in the past 30 years have seen threefold increases. Despite increased production, maize farming took up 6.7 million fewer hectares in 1980 than it did in 1940. UK wheat yields increased by 98% and barley by 62% between 1954 and 1981; and they are still climbing. In India, the 1982 rice yields, although variable throughout the country, were 3.3 t/ha, a 99% increase since 1960. And the 1984 crop was 58.5 million t–27% higher than in 1982–83. Even so, potential rice yields in the tropics are far higher, around 13–15 t/ha. Wheat yields have risen from 0.65 t/ha to 1.85 t/ha in the past 30 years (Refs. 9, 10, 11, 12, 13, 14).

20 ENERGY APPLICATIONS OF BIOMASS

A recent study by the FAO (Ref. 17) estimated the size of population that most third world countries could support using three levels of analysis: low-level inputs, approximately equivalent to subsistence farming; high-level inputs, approximately equal to Western farming technology; and intermediate inputs, halfway between these two farming systems. The result was surprising. Even with low levels of input, the less developed countries could support about one and one-half times their projected population (3600 million people) at the end of the century. At the highest level of input, Africa could theoretically support 16 times the population estimated for the year 2000, and South America 3 times. However, these figures relate to an egalitarian world, where rich and poor eat the same, mostly vegetarian, minimum diet. There was no provision for nonfood crops, woodfuel, or fruit; about 66% of the tropical rainforest would have to be felled, and every available acre of cultivatable land would be utilized. Taking these factors into account it is reasonable to reduce the estimate of potential global food production by at least one-third. And when the area most likely to be under cultivation is taken into account, by 2025 only Asia will be able to support its population with low inputs, while Africa will only be self-sufficient for 40% of its people. Central America would have to go beyond intermediate levels to feed its people— unlikely following present trends—while even at highest levels the Middle East would only be able to feed about 65% of its population (Refs. 17, 40). Some countries, mostly in central Africa and South America, have brighter prospects. The point to be emphasized is that this FAO study indicates that the planet could support the predicted 10 billion world population of the future. It suggests some practical ideas on how to cope with the problem: for example, conservation measures alone could reduce the number of critical African countries by seven; and growing crops more suited to the soil and climate of a particular area could increase Africa’s food production by 58% without any extra inputs. About 400 million people—a tenth of the world’s population—are malnourished; and this figure is probably still increasing. Another 600 million live constantly on the brink of undernourishment. Fifteen million children die each year from starvation. Forty million human beings die from hunger and its related diseases every year (Refs. 6, 4). This misery is avoidable even now. The world grows sufficient food that, if equally distributed, would provide a nutritious diet for everyone. For the developed countries this would mean the consumption of more basic staples and considerably less animal protein. Effective distribution of food within a country is essential, as is dramatically illustrated by Sri Lanka’s long life expectancy (66 years in 1975, 39% higher than would be predicted from world norms) and infant mortality (67% lower than would be expected) as results of such a programme (Ref. 15). One of the most expensive food distribution projects ever undertaken, its beneficial effect is emphasized when compared to the situation in India. In 1973–74, although enough food was produced to provide an adequate

BIOMASS FOR FOOD OR FUEL : A WORLD PROBLEM? 21

diet for all Indians, 38% of the population had a deficit in daily calorie intake; the poorest 5% had a deficit of 1100 calories per day (Ref. 16). On average, a person in the developing world gets about 188 calories per day from animals; the figure is 1073 calories in the developed countries. About 40% of all cereals produced—and 90% of the soya bean production—goes into feeding livestock; and in the richer countries it is nearer 75% (90% in the United States) . “Diverting only one quarter of the world soya bean harvest from feed use to direct human consumption would provide 5 kg per year of high protein food (750 kcal per day) for everyone in the world.” But the situation is not so simple. Most feed use of cereals occurs in the developed countries. Even if many people are desperately short of food, not using cereals as livestock feed would not mean they would reach the needy. The actual situation is thus very complex, but the world’s food problem is really a political one, and essentially one of irradicating poverty. “The money required to provide adequate food, water, education, health and housing for everyone in the world has been estimated at $17 billion a year. It is a huge sum of money…about as much as the world spends on arms every two weeks” (Refs. 18, 5). 4 BIOMASS The realisation that the production of power alcohol from sugar and starch crops is the quickest means of introducing a new liquid fuel source is receiving worldwide recognition. Individual countries such as Brazil, the United States, the Philippines, Malawi, Kenya, and Zimbabwe have made substantial investments in fuel alcohol production. Worldwide, yearly government expenditures on power alcohol schemes are over $2 billion. The largest programme is in Brazil, where the government currently spends around $1.3 billion on subsidizing the production of fuel alcohol, mostly from sugarcane. The aim is to increase production from the 2.4 billion L produced in 1978 to 10.7 billion L by 1985, and reaching 14 billion L—which would replace 75% of the 1978–79 consumption of gasoline—by 1987. If, as seems likely, the 1985 target is met, the alcohol produced will mean a 60% saving on petrol (Ref. 19). Over 1 million cars now run on hydrated alcohol in Brazil, with the remaining 7 million or so using a 20% alcohol blend. In 1983 the number of pure-alcoholfueled cars produced accounted for 75% of vehicle production and 90% of all sales. Recently a new policy has been initiated to make alcohol production more self-sufficient. Between 1976 and 1982 the land used to grow sugarcane increased by around 1.2 million hactares and if the 1985 target of 10.7 billion L of ethanol is to be met, a further 1.6 million hactares will have to be planted in relation to the land area planted in 1982. But in 1980 sugarcane accounted for only 5.4% of the approximately 48 million ha of cultivated land, and only 28% of the total sugar crop went directly to produce alcohol. A more serious source of competition for

22 ENERGY APPLICATIONS OF BIOMASS

agricultural land came from the ever—increasing area devoted to cash crops, which from 1976 and 1982 was between 2.2 and 2.6 million ha. Soybeans alone took up 50% more land than did sugarcane. Industrial crops have increased by some 46%, while food crops only accounted for 18% of this new agricultural land and have actually decreased from 64% to 59% of the total area cultivated (Ref. 19). The potentially cultivatable land (between 226 and 268 million ha) is more than enough to accommodate the extra 4.8 million ha required to meet the 1989 alcohol production target. And by increasing both the yield and sugar content of sugarcane, and making more efficient use of the distilleries, the yield of alcohol from a tonne of sugarcane could be improved by about 45%—from 65 L to 90 L/ t and productivity from 3600 L to 7200 L/ha—an improvement of 100% (Ref. 20). Production costs for alcohol are about $50–$55/bbl of petrol replaced. Petrol made from imported oil costs $41/bbl at the refinery. Taking the considerable foreign debt and the interest charges into account, alcohol production in Brazil can be justified on purely economic grounds (Ref. 19). Zimbabwe’s alcohol production began in 1980 in a plant designed to produce 120,000 L/day, or 10 million L/year, about 12% of the country’s petrol requirements. In 1983–84, there were approximately 34 ,000 ha of cane planted, producing some 410,406 t of sugar. The area of land needed to grow cane to provide alcohol for all liquid fuel requirements plus all domestic sugar needs (but not for export) would be about 52,000 ha—less than double the present area. Land is relatively plentiful, so there would be little competition with food (Ref. 21). Production of alcohol reduces foreign exchange earnings. However, because the price for sugar on the international market is notoriously variable, and a considerable strategic advantage is gained from greater self-sufficiency, plus the fact that alcohol is a renewable resource, the balance is more than in favour of home alcohol production for Zimbabwe (Ref. 21). Since U.S. alcohol production comes largely from surplus grains, its future will depend on technological developments, economics, and considerations concerning the provision of food for the hungry Third World. A present U.S. food aid stands at around 5 million t, about 5% of exports, and about the limit that the government or the public seems willing to accept. In theory, the United States could convert its export grain (around 123 million t) to alcohol, with no effect on the domestic market. This would produce 11.5 billion gal of ethanol, around 10% of the annual petrol consumption, replacing 164 million bbl of oil and saving 7.1% of the annual oil imports. However, in 1980 prices, the ethanol produced would be worth $6.6 billion, while the value of the exported corn alone was worth $7.7 billion (Ref. 22). The U.S. alcohol industry now produces about 500 million gal from a total of 65 plants (80% from only 8 of these plants). Assuming a 10% blend, the potential demand is 6 billion gal of ethanol, or 12 times the present capacity. However, it is expensive to produce, with corn accounting for 50% of the price. Ethanol currently costs $1.70 to make, so that a subsidy of 80 cents/gal to bring

BIOMASS FOR FOOD OR FUEL : A WORLD PROBLEM? 23

the price down to the production cost of gasoline is essential to the survival of the alcohol industry. But the production of ethanol has to be seen against a backdrop of economic, strategic, and political factors. In 1983, the cost of policing the sea routes to ensure uninterrupted supplies of oil amounted to double the market price of the oil actually exported from those areas. And in the same year, the cost of maintaining a strategic oil reserve was five times the amount of tax relief given to the alcohol industry (Ref. 41). Consumption of power alcohol has risen from almost nothing in 1979 to 455 million gal in 1983. But what would be the impact of alcohol production on U.S. agriculture? The production of a small amount, 2.5 billion gal requiring 1 billion bushels of corn, would have little effect on food prices. The main problem would seem to be the moral one of turning so much food into (relatively) so little fuel. If 10 billion gal of ethanol were produced, the required 4 billion bushels of corn would need an additional 41 million acres, while the soybean crop would be reduced by 25 million acres. Corn prices would go up by between 20% and 40% (Refs. 22, 23, 24). The United States, and more especially Brazil, have developed alcohol programmes on the strength of agricultural surpluses. Is Europe in a position to do the same with the substantial surpluses produced by the CAP (Table 1)? Table 1: Self-sufficiency in certain agricultural products (%). product

EEC 10 (1)

USA (2)

Wheat 118 315 Rice 83 250 Sugar 124 64 Grain maize 62 160 Soy beans — 185 Skimmed milk powder 126 199 Butter 118 121 Cheese 106 99 Beef/veal 102 93 Poultry 108 106 Eggs 101 104 Pork 101 98 Cotton 11 265 EEC self-sufficiency for concentrated milk was 154, whole milk powder 337, barley 112, and rye 107 . (1) crops, average for 1978–79, 1979–80, 1980–81; animal products, average for 1978, 1979, 1980. (2) sugar and animal products, average 1981–82; crops other than sugar: average 1981– 82, 1982–83. Source: Ref. 25.

24 ENERGY APPLICATIONS OF BIOMASS

Although these agricultural surpluses are substantial, they are very small compared to the volume of the oil market. Between 1978–81 the potential quantity of alcohol that could be (expensively) produced from unmarketed fruit and wine averaged at 223 million L, some 204,000 tons of oil equivalent (toe), or only 3% of total oil demand. And converting 35% of the export sugar would really only amount to a nonpayment of subsidies. Before production of agricultural alcohol becomes viable, new lower cost feedstocks will have to be found. At present there is no concerted programme for producing fuel alcohol, or even blending with petrol (Ref. 24). Unproductive agricultural land in the United States could produce between 19. 7 and 32.9 billion L of alcohol. And if 30.1 million acres that farmers were paid not to grow crops on in 1984 were used to produce ethanol from corn, between 20.3 and 40.6 billion L of alcohol could have been produced. More intensive cultivation could increase the quantity of alcohol produced to replace around 10% of the current petrol consumption. An EEC study suggests that by shifting 8% of the agricultural land to grow sugar beets for conversion to alcohol, between 6% and 8% of the projected petrol consumption for 1990 could be met (Ref. 24). Elimination of dairy surpluses in the EEC would release no less than 1.4 million ha that could be used for energy crops and also reduce the import bill for animal feeds and grains. In 1980 the United States over-produced an equivalent in milk of around 5.8 million t. Removing this surplus would release 510,400 ha from grainlands, and a further 406,000 ha from land cultivated to grow feed crops (Ref. 24). Table 2: Recoverable potential energy production of the main agricultural residues and wastes country

crop residue animal waste total

% of total energy requirement

Canada 2.3 1.8 4.1 1.9 United States 20.2 5.0 25.2 1.4 Japan 0.4 1.2 1.6 0.4 Finland 0.4 0.2 0.6 2.4 France 5.2 2.4 7.6 4.0 Germany 2.2 1.6 3.8 1.4 Italy 2.5 0.9 3.4 2.5 Sweden 0.8 0.2 1.0 2.0 Switzerland 0.1 0.2 0.3 1.2 United Kingdom 1.3 1.3 2.6 1.2 Note: Figures are an average of 1978–1980 and are in million toe. Source: Ref. 24.

Another source of potential biomass energy is from agricultural wastes and residues, summarized in Table 2.

BIOMASS FOR FOOD OR FUEL : A WORLD PROBLEM? 25

In the United States by the year 2000, agricultural residues and wastes could provide up to 30.64 million toe annually, and animal waste could contribute 7.1 million toe annually. In the EEC, the total net energy potential for animal wastes is 11.5 million toe, and for crop residues is 12.5 million toe (Refs. 24–27). The U.S. timber industry now gets 50% of its energy requirements from wood residues. By 2000, wood could provide 235.7 million toe per year (OTA). In 1979, Germany had the potential to provide 6.2 million toe from forest waste and industrial residues, Finland 8.6, France 6.1, Sweden 10.4, and Canada 32.1. France has reserves of coppice that could provide between 1.5 and 2 million toe per year. Finland has stands of unproductive hardwoods that could give some 1. 01 million toe per year, and forest thinnings would be worth 0.8 million toe/year (Refs. 26, 27). In the EEC, by 2000, forestry and short rotation plantations could provide 28 million toe net. And in the United States, herbaceous plants and short-rotation forestry combined could provide 117.9 million toe in 15 years with a value of $26,390 million in 1984 prices. The United Kingdom produces enough wastes to produce, with the current technology, about 5.7 million toe, currently worth $1, 215.4 million. The United States could, by 2000, obtain between 5% and 15% of its total energy requirements from biomass, some 141.4–391.3 million toe/year. In the same period the EEC is estimated to be able to produce 85.8 million toe from biomass (Refs. 24, 39). 5 SUBSIDIES In the United States in 1983 agricultural subsidies came to around $19 billion in payment-in-kind (PIK) and cash payments, to which must be added indirect subsidies, tax concessions, and support grants, etc. PIK will not operate in 1984– 85. Direct government payments are forecast to be $8–10 billion in 1983 and $6– 10 billion in 1984. Price support and direct payments to farmers in the United States went up by 792% between 1970 and 1982. It is projected to rise by a further 115% to $68 billion by 2000. In the EEC in 1983, agricultural subsidies amounted to some $15 billion. The projected total cost of EEC subsidies in 1984 is a colossal $23.83 billion. The cost of EEC farm policies to the UK consumer in 1979–80 came to an astounding £3,350 million or nearly £13,000 for every farmer, while the gross product of British agriculture was then only £5,420 million (Refs. 13, 14, 28, 25). 6 RESEARCH The green revolution has enabled crop yields to be increased dramatically, but the high yield varieties used respond to expensive inputs, limiting their use to richer farmers in more favoured areas. With dwindling reserves of fertile soils,

26 ENERGY APPLICATIONS OF BIOMASS

attention will have to be directed to potential cropland in more marginal lands. It is essential to develop crop varieties with the genetic capacity to thrive in conditions of drought stress (affecting 5454 million ha of marginal land in LDCs), infertile soils lacking in trace elements (3272 million ha), a tolerance to high acid levels (2273 million ha) , or an ability to withstand toxic levels of soluable aluminium (3000 million ha). By adjusting certain soil deficiencies and using toxic-resistant varieties, yields of rainfed rice in large areas of potentially suitable land could be raised from 0.80 t/ha to 1.5–2.0 t/ha (Ref. 29). To maximise the net energy gain, research and development on energy crops will have to emphasize the highest outputs for the lowest inputs, requiring higher reliance on genetic improvements than hitherto. For example, one energy-cane hybrid gives exceptionally high yields of 253 million g ha-1 , but even these yields could be improved. R&D should also be directed toward crops that can provide greater or cheaper supplies of valuable commodities. Under the right conditions, the perennial palm can produce 6 t/ha each year, but it is known that the capacity of individual palms is much greater (Ref. 31). Guayule (Parthenium argentatum) can be used as a source of rubber with a quality similar to that obtained from the rubber tree. There is a pilot plant producing one tonne a day in Saltillo, Mexico, with a 50 tonne a day plant in the offing (Ref. 32). And the alga Botryococcus braunii has been shown to yield 70% of its extract as a hydrocarbon liquid closely resembling crude oil (Ref. 6). Agricultural research and development should be a top priority. Not the least of the problems is lack of money—of the $150 billion spent annually on research and development, only 3% is spent on agriculture, with most of this being used in developed countries. Cost benefit analysis suggests that 2% of the value of agricultural product should be spent on research and development; among developing countries, particularly in Asia, less than 0.5% is currently being allocated. And in industrialized countries such research is often seen as a soft target for cuts in times of economic recession (Refs. 33, 34). 7 CASH CROPS Although $5 billion were devoted to agricultural projects in Africa between 1973 and 1960 (more than in Asia or Latin America), there was no sizable increase in food crop production. The benefits were seen in the higher yields of many export crops such as cotton, tea, and tobacco. Today more than one quarter of the cultivated land in the developing countries is devoted to cash crops; and it is often the most favourable for agricultural production. The pressing need for foreign currency makes it difficult for governments to break out of this deplorable situation, as do the funding policies of international organisations, which often provide farmers with inputs and services, but only if they produce cash crops (Refs. 35, 36).

BIOMASS FOR FOOD OR FUEL : A WORLD PROBLEM? 27

The problem is compounded by plummeting commodity prices and escalating oil prices, an essential import for many developing countries (Fig. 1). 8 NUTRITION The evidence suggests that the diets of a health-conscious public are tending to change. In the United Kingdom between 1971 and 1981 milk consumption went down by 43.2% to 3.94 pints per week. Weekly meat consumption dropped by 17.6%, butter by 33.2% to 3.6 oz, sugar by 28.9% to 11.08 oz, and eggs by 21% to 3.68 oz. Similarly, between 1980 and 1982, U.S. meat consumption decreased by around 4.5 kg per person per year, and is projected to fall to 63 kg by 2000. Animal oil intake went down by 15% to 2.9 kg, while intake of vegetable protein has increased by almost 18% (Refs. 11, 13, 38). 9 CONCLUSIONS There are excesses of both food and energy in the world at present. Many countries with food shortages could, with long-term planning, greater political and financial recognition for agriculture, and more research and development raise their crop production dramatically. Of greater concern, in our opinion, are the more serious consequences of overuse of biomass as a source of energy. The quality of planning and control required to manage and/or change biomass use is generally lacking where it is most needed. The very great potential yield increases possible for energy production, and the realization that forestry can also involve a contribution of trees to agriculture, are reasons for optimism. The greatest impediment now to the application of forestry techniques to the problem is the lack of trained personnel due to previous near total neglect by planning authorities. Both food and biomass energy production must be interlinked to problems of rural development and poverty. REFERENCES 1. 2.

3. 4. 5.

de Montalembert, M.R. and Clement, J. ‘Fuelwood supplies in the developing countries’, FAD forestry paper No. 42, Rome, 1983. Kristoferson, L., Bokalders, V. and Newham, M. ‘Renewable energy for developing countries: a review’, Vol B.Biomass Energy-Production, Conversion, Utilisation, The Beijer Institute, Stockholm, 1984. Bhagavan, M.R. ‘The woodfuel crisis in the SADCC countries’, Ambio, vol. 13, No. 1, 25–27, 1984. ‘Agriculture: Toward 2000’, FAO, Rome, 1981. Pimental, D., Dazhong, W., Eigenbrode, S., Lang, H., Emerson, D. and Karasik, M. ‘Food and biomass energy for socioeconomic development’, in press, 1984.

28 ENERGY APPLICATIONS OF BIOMASS

6.

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11. 12. 13. 14. 15. 16.

17. 18. 19. 20. 21.

22. 23.

24. 25. 26. 27. 28.

Hall, D.O.‘Biomass: fuel versus food, a world problem?’, Economics of Ecosystems Management, Eds., D.O.Hall, N.Myers, and N.S. Margaris, 207–225, Dr. W.Junk, publishers, Dordrecht, 1985. Pimental, M. ‘Food for the people’, Food and Energy Resources, Eds., D. Pimental and C.Hall, Academic Press, Inc. (London) Ltd., 67–90, 1984. ‘Gaia, an atlas of planet management’, General Ed., N.Myers, Anchor Press/ Doubleday & Co., New York, 1984. Borlaug, N. ‘Feeding the world during the next doubling of the world population’, Chemistry and World Food Supplies: The New Frontiers, Chemrawn II, Perspectives and Recommendations, IRRI, Los Banos, Laguna, Philippines, 133–158, 1982. Odhiambo, T.R. ‘Biological constraints on food production and on the level and efficient use of chemical inputs’, Chemistry and World Food Supplies: the New Frontiers, Chemrawn II, Perspectives and Recommendations, Eds., G.Bixler and L.W.Shemilt, IRRI, Los Banos, Laguna, Philippines, 65–88, 1982. Body, R. ‘Agriculture: the triumph and the shame’, Temple Smith, London, 1983. Body, R. ‘Farming in the clouds’, Temple Smith, London, 1984. ‘Cornucopia Project Newsletter’, Vol. 4, No. 2, Rodale Press, USA, Fall 1984. ‘Agricultural outlook’, USDA, July 1984. Berg, A. ‘Malnourished people, a policy review’, Poverty and Basic Needs Series, World Bank, Washington, June 1981. Parikh, K. and Rabar, F. ‘Food problems and policies: present and future, local and global’, Food for All in a Sustainable World: IIASA Food and Agricultural Program, IIASA, Laxenburg, 1–42, 1981. ‘Potential population supporting capacities of lands in the developing world’, FAO, Rome, 1984. Barr, T.N. ‘The world food situation and global grain prospects’, Science, vol. 214, 1087–1095, 1981. Geller, H. ‘Ethanol from sugarcane in Brazil: an investigation of some critical issues’, Annual Review of Energy, in press. Calle, F.R. ‘Food as fuel’, PhD Thesis, 1984. Wenman, C.M. and Tannock, J. ‘Ethanol as a fuel additive in Zimbabwe’, Proc. Communications VI Int’l. Sym. on Alcohol Fuels Technology, vol. 1, 406–410, 1984. Hudson, W.J. ‘Biomass energy and food—conflicts?’, Food and Energy Resources, Academic Press Inc., London, 207–236, 1984. Head, E.O. and Christensen, D.A. ‘Potentials in producing alcohol from corn grain and residues in relation to prices, land use and conservation’, Food and Energy Resources, Academic Press Inc., London, 237–256, 1984. “Biomass for energy’, OCDE, Paris, 1984. ‘The agricultural situation in the community’, 1983 Report of the Commission of the European Communities, Brussels, Luxembourg, 1984. ‘A guide to federal programs in biomass energy’, U.S. Department of Energy, Washington, D.C., Sept. 1984. ‘Biomass energy technology research program summary’, U.S. Department of Energy, Washington, D.C., 1984. ‘Filling granaries, not stomachs’, Economist, 57–58, Sept. 1, 1984.

BIOMASS FOR FOOD OR FUEL : A WORLD PROBLEM? 29

Fig. 1. Purchasing power index of petroleum and cash crops exported by developing countries in terms of imported manufactures, 1971–82. 29.

30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41.

Sanchez, P., Nicholaides, J. and Couto, W. ‘Physical and chemical constraints to food production in the tropics’, Chemistry and World Food Supplies: the New Frontiers, Chemrawn II, Perspectives and Recommendations, IRRI, Los Banos, Laguna, Philippines, 89–106, 1982. Rockwood, D.L. ‘Genetic improvement potential for biomass quality and quantity’ , Journal Series paper No. 5478, Florida Agriculture Experiment Station, 1984. Jones, L.H. ‘The oil palm and its clonal propagations by tissue culture’, Biologist, vol. 30, 181–188, 1983. ‘Development of new crops: . needs, procedures, strategies and options’, Council for Agricultural Science and Technology, Report No. 102, Oct. 1984. Chambers, R. and Ghildyal, B.D. ‘Agricultural research for resource poor farmers: the farmer-first-and-last model’, in press, 1984. ‘An assessment of the United States food and agricultural research system’, OTA, Washington, D.C., Jan. 1982. Lipton, M. ‘The place of agricultural research in development of sub-Saharan Africa’, IDS, University of Sussex, Nov. 1984. Twose, N. ‘Cultivating hunger’, WFA, Nov. 1984. ‘Commodity trade and price trends 1982/83 edition’, World Bank, John Hopkins Press, Baltimore and London, 1984. Nature, vol. 304, No. 5922, 103, July 14, 1983. ‘The Great Britain/East Europe centre symposium on biomass’, London, Oct. 15– 17, 1984. Harrison, P., ‘Trapped in the food maze’, Guardian, Oct. 11, 1984. Schwandt, W.R., ‘Political, economic & technical aspects of the U.S. fuel ethanol program’, The World Biotech Report 1984, vol. 1, Europe, Online Publications Ltd., 519–528.

A FEDERAL-STATE R&D PARTNERSHIP: COOPERATIVE STATE AND FEDERAL SUPPORT FOR REGIONAL TECHNOLOGY I.L.WHITE* *New York State Energy Research and Development Authority

1 INTRODUCTION When the Reagan Administration took office, it brought with it the view that government’s role in research and development (R&D) should be quite limited. Specifically, with the exception of defense and space, government should support only the most fundamental research. The application of research results should be left to the private sector. While not yet “born again,” the Administration has, in practice, been much more pragmatic than its ideology would suggest. In some areas it has gone beyond its strictly defined limitation. But when it has, it has done so as an ad hoc activity without any clearly defined overall program for attempting to ensure that federal R&D expenditures produce new industries, new products, greater efficiencies, or other potential benefits. The thesis of this brief paper is that this problem must be addressed in a more pragmatic, nonideological way. It is maintained that a federal-state energy R&D partnership should be established to help ensure that national energy R&D programs produce meaningful, tangible benefits at the state and local levels. Given the U.S. Department of Energy’s (DOE) proposed $25 million expenditure for technology transfer, it is essential that this partnership be established as soon as possible. 2 BACKGROUND Effective linkages between those who acquire knowledge and those who apply it have always been essential for knowledge and new technologies to be translated into widespread, productive applications. No era illustrates this better than the 1950s and 1960s, a period of extraordinary success in realizing the tangible benefits of R&D in the United States. During those decades, the research contract and research grant mechanisms developed during World War II were used to establish linkages among

A FEDERAL-STATE R$ D PARTNERSHIP : COOPERATIVE STATE 31

government, universities, and industry. Government provided large-scale funding and, in areas such as defense and space, was itself both customer and consumer. Universities and other research institutions conducted the research and trained the scientific and technical workforce, usually combining the two activities. Industry employed this workforce and applied the resulting knowledge to produce products, either for government as customer/ consumer or for the marketplace. During this period, the United States employed what Princeton Prof. Robert Gilpin calls a “Broad Front” strategy (Ref. 1). That is, ours was a frontal assault on the entire frontier of science. Upon examination, it is striking though not surprising that most of the science and technology supported by the federal government during this period was mission-oriented. Over the two decades, the major mission was defense. Beginning in the late 1950s and early 1960s, space ranked second. But older missions also survived, and in some cases were actually expanded; for example, R&D in agriculture, health, and commerce-related mission areas such as meteorology, geodesy, and oceanography, to name but a few. Descriptions of the period point to the contrast between pre- and post-World War II. Prior to the war, science and government shared a mutual distrust. But postwar, the two became partners—science having become “big science,” and scientists needed “big bucks.” And government, meaning both career and elected officials, had become convinced that science and the application of knowledge could contribute significantly to the achievement of high-priority national goals. The operating assumptions of both, and of society more generally, were that (1) any and all investments in science and technology would eventually be socially beneficial, and (2) no problem was beyond the capabilities of scientists and engineers to resolve. 3 THE PRESENT SITUATION A good bit has happened since the 1960s that affects these assumptions as well as the linkages among government, universities, and industry. For one thing, it has become more difficult to pursue a Broad Front strategy, both because of the increasing breadth of science and the enormous resources that would be required. As Vannevar Bush suggested, science has proven to be an “endless frontier” (Ref. 2). Our success in the application of science has also now been challenged. For example, other countries, particularly Japan and several Western European countries, have become quite successful, actually surpassing us in a number of areas. Who would have expected this outcome during those heady days in the 1950s and 1960s when we were in a class by ourselves? We have also been somewhat perplexed by our lack of success in making those linkages work in new R&D areas such as energy. It is commonplace to

32 ENERGY APPLICATIONS OF BIOMASS

point out that in many of these new areas, including energy, government is neither the customer nor the consumer. It is also true that other countries have certain “advantages,” such as newer, more modern plants and lower labor costs. Some of these changes are probably significant. But whether taken separately or together, they do not provide an altogether satisfying explanation of the limited success of our national R&D programs in these new areas. I believe a major part of the problem in energy R&D is that in most publicly supported energy R&D programs, “government” has meant only the federal government. But the federal government is not the level of government best equipped to bridge the gap between national-level programs and actual applications. The latter always takes place at specific locations at the state and local levels. Effective promotion of applications based on generic, national-level R&D requires a detailed knowledge of specific local conditions and needs. And it is regional and state level rather than national organizations that have this knowledge and know best how to use it effectively to produce tangible results. 4 THE PROPOSAL Thus a federal-state energy R&D partnership is needed. In particular, DOE and regional and state energy R&D organizations, such as those in the Northeast and in California, North Carolina, New Mexico, and New York, should jointly plan, fund, and implement energy R&D programs in selected areas. Such a partnership would draw on the strengths of both DOE and regional and state energy R&D organizations. Briefly stated, the successful application of knowledge gained in large-scale national research programs is much more likely to occur when regional and state-level organizations sensitive to local needs, opportunities, and conditions are involved. These organizations have closer, more direct relationships with private sector energy and energy technology consumers. The proposed partnership would incorporate an approach emphasizing: • An overall program rather than an individual project orientation • Joint planning and joint funding in specific program areas of mutual interest to DOE and individual regional/state energy R&D organizations • Effective utilization of the full range of regional/state-level resources in technology transfer • Results that lead to new industries, new products, greater efficiencies, and other potential benefits. With few exceptions, cooperative research involving DOE and regional/ state energy R&D organizations is undertaken on a project-by-project basis. Such efforts tend to be ad hoc and identified for the most part on a target-ofopportunity basis. A much more rational approach would be to identify specific program areas of mutual interest to DOE and a regional/ state organization, have

A FEDERAL-STATE R$ D PARTNERSHIP : COOPERATIVE STATE 33

DOE and the regional/state organization jointly identify R&D needs in these areas, and then jointly develop and fund an R&D program designed to meet these needs. Such an approach would provide a mechanism for making more efficient and effective use of scarce energy R&D sources than is likely to occur using the current approach. An important measure of the effectiveness and efficiency of energy R&D is whether results are translated into beneficial applications. At the regional and state levels, effective applications mean that new industries are established, new products are produced, greater efficiencies are achieved, and other potential benefits are realized. For this to happen, technology transfer cannot stop with published reports, conferences and workshops, videotapes, and traveling roadshows. Slick public relations won’t do it. Someone has to be an effective communicator/translator/ promoter at the regional, state, and local levels. A broad range of economic development and technical assistance capabilities already exists at these levels, and regional and state energy R&D organizations know how to mobilize the delivery of these services. They know how to identify the individuals and firms likely to benefit from energy R&D results, and they know how to help these potential users apply these results at specific places to meet specific needs and to take advantage of specific opportunities. 5 THE BIOMASS EXAMPLE Biomass is an area ripe for the proposed federal-state partnership. In this case, the resource base itself varies regionally. The overall national research program would benefit from the direct participation of regional and state energy R&D organizations. But the more compelling point is that there will not be much of a payoff from biomass R&D unless regional and state-level R&D organizations are a part of the program. Comprehensive knowledge about supply and technologies for either converting or utilizing biomass resources will produce few practical results unless local needs, opportunities, and conditions are taken into account. Quite apart from the standard questions about technical and economic feasibility usually addressed by R&D projects, a myriad of other factors stand between knowledge and application; for example, the effects of state and local laws and regulations, attitudes, and business conditions. Under the leadership of the Coalition of Northeastern Governors (CONEG) and the New York State Energy Research and Development Authority (NYSERDA), a biomass partnership is developing in the Northeast. The CONEG program, funded by DOE, is devoted largely to the promotion of wood energy through studies and various information dissemination activities. Specifically, the program supports wood energy expertise in state governments, analyses of environmental and economic impacts of expanded utilization of wood for energy, and development of workshops and printed material designed to bring the advantages of wood fuel to the attention of potential users. This attempt at

34 ENERGY APPLICATIONS OF BIOMASS

technology transfer is useful but not sufficient to bring new technology to the marketplace. NYSERDA’s regional biomass effort, on the other hand, is an example of the kind of program being proposed here. It transcends the traditional boundaries of government contract R&D, and it directly involves users at an early stage of technology development to address in advance the broad spectrum of practical problems connected with implementation. Several examples illustrate how the program works. Two research projects are being conducted in conjunction with private developers to establish the basis for investment decisions to construct innovative facilities that would produce fuels, energy-intensive chemicals, and possibly food by-products from wood. NYSERDA’s direct wood-to-energy conversion efforts include not only research but also coordinated technical assistance and financial aid to innovators. To ensure long-term biomass supplies, a formal program involving NYSERDA, the Gas Research Institute, and a consortium of New York based utilities sponsors research in fast-growing hardwoods. The knowledge and technical capability created by this type of research has enabled NYSERDA to organize separately a commercial tree cultivation demonstration at a manufacturing facility in the northern part of New York State. The program is regional both in its outlook and its institutional support. Much of the work we support addresses opportunities applicable to the Northeast as a whole and takes place outside New York State with support from other states or private organizations. For example, NYSERDA, the Commonwealth of Massachusetts, and several New England gas utilities are sponsoring a methanefrom-sewage sludge project in Salem, Mass. A number of other states are also involved with NYSERDA in a project to take place in Pittsfield, Mass., designed to contribute to better control of dioxin emissions from municipal waste combustion. What is lacking in this Northeastern effort is program support from DOE. Such support would help DOE be more effective in its technology transfer efforts. 6 A CALL TO ACTION While we are all interested in and support research undertaken to produce knowledge, we also want to reap the benefits of actual applications of this knowledge. The reality is that knowledge and new technologies do not get applied automatically. We all know that potential users of knowledge and new technologies need to be involved at an early stage so they can help shape R&D products to meet their needs. But even then, they often need encouragement, if not a hefty push or pull to actually apply these research products. Providing encouragement and a boost through technical assistance and risk-sharing programs is something that seems to be done best by regional and state

A FEDERAL-STATE R$ D PARTNERSHIP : COOPERATIVE STATE 35

organizations. This is why we propose that DOE and regional and state energy R&D organizations combine forces. A partnership is needed to ensure that our federal and state R&D expenditures produce the maximum possible meaningful, tangible benefits. And it is needed now! REFERENCES 1. 2.

Gilpin, R. ‘Technological strategies and national purpose’, Science, vol. 169, 441–448, July 31, 1970. Bush, V. ‘Science, the Endless Frontier; a report to the president on a program for postwar scientific research’, National Science Foundation, Washington, DC, 1960.

BIOMASS FOR ENERGY IN THE FOREST PRODUCTS INDUSTRY J.L.KULP* *Weyerhaeuser Company, Tacoma, Washington

SYNOPSIS The forest products industry utilizes residual material from trees to processes. The trend is toward replacement of natural gas, oil, and coal by produce steam, hot air, electricity, and combustible gas for its various wood-derived biomass as well as self-generation of the electrical requirement. This trend suggests a doubling of wood biomass use from 2 to 4 quads from 1980 to 2000. It will be shown that in a managed conifer plantation system at steady state there is a slight excess of energy over production requirements. Technology improvements in harvesting and energy production make residual biomass the vehicle of economic choice in most instances. In the United States, short-rotation hardwood plantations may eventually be used by the industry as a source of pulp chips, but not primarily for energy. 1 INTRODUCTION My assignment is to put in perspective the utilization of biomass for energy in the forest products industry in the United States. I will not address biomass for other potential energy uses such as municipal electric generation, ethanol production, or residential heating. In the forest products industry, the biomass of interest is really phytomass, i.e., tree tissue, and normally consists of bark, foliage, limbs, sawdust, and other residues. This material is called energy fiber to distinguish it from pulp fiber. A less sophisticated term is wood waste. This energy fiber is combusted to produce hot air, low energy content gas, steam, and, by cogeneration, electricity for mill processes. Table 1 compares the use of wood (trees) with other biomass material and the total U.S. energy use in 1980 with that projected for 2000. The doubling of the use of wood is a conservative estimate, for it does not include the probable increase in the number of pulp mills but only the replacement of fossil fuels by energy fiber in current mills.

BIOMASS FOR ENERGY IN THE FOREST PRODUCTS INDUSTRY 37

Table 1: Biomass energy in the United States source

Wood Agricultural wastes Municipal solid waste U.S. total energy use

quads (1015 Bt tu or 109 GJ/yr) 1980

2000

2.2 0.1 0.2 75

4 0.5 1 95

2 TRENDS IN THE INDUSTRY For the past decade, the amount of fossil fuel and purchased electricity per ton of product has been steadily decreasing as a result of conservation technology and replacement of these fuels by biomass. As a result, the energy self-sufficiency of pulp, paper, and lumber mills has been increasing (Fig. 1). In terms of biomass (energy fiber) use, it has increased from 15 to 31 million tons per year (Table 2). This quantity of wood is equivalent to nearly 2×10 barrels of oil per year or about 40 days of current U.S. imports. The reduction in the use of fossil fuel is even more impressive when it is realized that total production of pulp and paper increased by 24% during the same period. For the 1972–82 period, the energy use per unit of output (Fig. 2) is seen to decline due to conservation. Further, the biomass contribution increases in absolute terms and the fossil fuel use declines in both absolute and relative terms. By 1990, it is estimated that the total will drop to 26 million Btu/ton and the biomass component use to 18 million Btu/ton. By 2000, the ultimate conservation effort may result in about 20 million Btu/ton, with 90% or more being supplied by tree biomass. Table 2: U.S. pulp and paper industry biomass use year

106 ton

1972 1976 1980 1984

15 19 25 31(est.)

A specific example of the future plans in the industry is shown in Table 3. Starting with a base in 1981, a Weyerhaeuser mill consumed about 1.2×10 equivalent barrels of oil in its production. Increases in capac ity projected through the 1980s would require another 0.1×10 equivalent barrels. This total of 1.6×106 equivalent barrels will be essentially eliminated by 1990 by our plans, which include conservation, efficiency improvement in black liquor combustion,

38 ENERGY APPLICATIONS OF BIOMASS

and, most important, replacement of fossil fuels in the boilers and lime kilns by energy fiber. Table 3: Weyerhaeuser mill (2400 t/day) boiler and lime kiln areas 103 bbl oil equivalent 1981 fossil fuel consumption Planned production increases Planned fossil fuel reductions conservation more steam from black liquor replacement by biomass 1990 fossil fuel consumption

1166 427 242 174 1137 0

3 STEADY-STATE PLANTATIONS In the lands owned by the forest products industry, the relatively slow-growth native forest or marginal farmland is being converted to scientifically managed high-yield tree plantations. These plantations will be thinned, harvested, and replanted on the most economic schedule. At steady state with present technology, an average pine plantation in the coastal plain of the southeastern United States will yield about 18 m3/ha yr (or 8 dry ton/ha yr) over a 30-yr rotation. Each tree will be broken down to yield the highest value; i.e., the maximum lumber will be first priority followed by the maximum pulp chips. The residue is assigned to energy fiber. Table 4: Loblolly pine plantation system Assumptions Average S.E. U.S. plantation site (18 m3/ha yr, 8 dry ton/ha yr) 30-yr rotation—two thinnings—all above-ground biomass Each part of biomass to highest value 1,000 ton/day pulp mill, lumber mill to match Result 1.45×105 ha plantation 21-km radius (15 km < average), 100% ownership Products 8.4×105 dry ton/yr chips 1.5×105 dry ton/yr lumber 2.9×105 dry ton/yr energy fiber Energy self-sufficiency (steam and electricity)

A plantation (wood basket) scaled to match the raw material requirements of a 1,000 ton/day pulp mill, and assuming that (1) 50% of the pulp is made into paper and (2) a lumber mill is sized to utilize all the suitable sawlogs, would

BIOMASS FOR ENERGY IN THE FOREST PRODUCTS INDUSTRY 39

produce the resultant products listed in Table 4. The energy fiber produced in this flow is more than sufficient to meet all of the steam, gas, and electrical requirements of the mill processes. This is displayed quantitatively in Table 5. The total available energy exceeds the demand by 1.6×106 GJ. Table 5: Energy balance

Total annual requirement 350,000 ton/yr paper 150,000 dry ton/yr lunber Electrical requirement Total sources Energy fiber Black liquor Total available Excess energy (average day)

GJ×106

kWh×106

6.4 0.7 7.1 2.0 9.1

316 35 351

4.1 6.6 10.7 1.6

1 ECONOMICS The availability of enough energy fiber from a steady-state plantation system does not, however, ensure its utilization. This is determined by the economics of production and delivery of the material. The value of energy fiber is compared with coal and oil at representative 1984 costs and also with higher valued wood products in Table 6. From these data, it is clear that wood that will produce clean pulp chips will not be used for energy. It also follows that for a delivered cost to a boiler of coal at $60/ton (average for Weyerhaeuser mills), energy fiber must be delivered at $33/dry metric ton or less to be competitive. Since coal is readily available anywhere in the United States, it, not oil, sets the standard for allowable wood cost at any given mill site. Table 6: Relative value of wood—1984 $/dry metric ton (delivered to mill) Energy fiber Aspen flakes—OSB Pulp chips Loblolly pine

33 at $60/ton coal 75 at 30/bbl ($l80/m3) oil 40 60±10

40 ENERGY APPLICATIONS OF BIOMASS

$/dry metric ton (delivered to mill) Douglas fir Saw logs Small logs Large Douglas fir

70±5 70±5 90±10

The cost of the energy fiber delivered to a mill using best available technology from loblolly pine plantations on flat or rolling land is analyzed in Table 7. It has three components: stumpage, harvesting, and transportation. The stumpage value of a plantation is the total cost of establishment and silvicultural management over the life of a stand treated as a capital investment that must earn 6%–8% compounded net of inflation. Harvesting is the cost of cutting and moving the whole tree (above-ground portion) to the landing, and breaking it down into its components: sawlogs, pulp chips, and energy fiber. Transport includes loading and unloading and movement to the pile at a mill site. Depending on various accounting assumptions and the distance to the mill, a reasonable upper and lower bound on the delivered cost of energy fiber can be given for 1984 technology. Table 7: Cost of energy fiber from loblolly pine plantations factors

$/dry ton

high

Low

Stumpage (Cost weighted by product value) (No cost for waste-energy fiber) Harvesting (Stump-to-truck equal for all products) (No cost for waste-energy fiber) Transportation 50 km 15 km Total

6 –

– 0

14 –

– 0

13 – 33

– 7 7

4.1 Stumpage First the total stumpage value per hectare of the entire plantation is calculated. Then the part attributable to energy fiber is determined either by calculating its weighted relative value (high case) or by assuming it to be zero on the basis that

BIOMASS FOR ENERGY IN THE FOREST PRODUCTS INDUSTRY 41

the plantation was grown for the sawlogs and pulp chips and the energy fiber is waste (low case). 4.2 Harvesting The high case is calculated by dividing the total cost per hectare for cutting, moving, and separating the three products at the landing by the total biomass processed. The low case again treats the energy fiber as waste and hence assigns no cost. 4.3 Transportation A well-planned plantation “wood basket” for a scalp pulp mill (1,000 ton/day) would normally have an average distance from the landing to the mill that did not exceed 50 km (high case). If the wood basket consisted of the minimum required land (100% ownership) completely surrounding the mill, the average transportation distance would be about 15 km (low case). If these numbers are added, it is seen that with current technology the cost of energy fiber would be between $7 and $33/dry ton and therefore would be competitive with coal at a delivered cost of $60/ton. Further technology advances in silviculture and harvesting, coupled with ultimate pressure on coal suppliers and higher oil prices, should continue to widen the gap and make tree biomass for energy the fuel of economic choice in most instances. In the case of a native forest that is being clearcut, the ratio of energy fiber to lumber and chips is higher than in plantations due to the extra defective, dead, and small trees and unutilized species. Therefore, in all forests in the temperate zone that are being cut for lumber or pulpwood, the mills can be self-sufficient using biomass for their energy requirement. The costs of harvesting the energy fiber as a “come-along” residue from natural forests on steep ground will be higher than for level plantations and in some cases may then exceed the cost of coal. 4.4 Short-Rotation Hardwood Plantation In recent years, a great deal of effort has been directed toward the development of short-rotation hardwood plantations as a possible source of biomass energy. Yields as high as 20–30 dry ton/ha yr have been claimed for small experimental plots. The combined cost of stumpage, harvesting, and transportation for this energy fiber does not appear to be competitive with coal in the near term. However, as technology advances, such plantations may have high value and utility as raw material for pulp chips to produce fine paper.

42 ENERGY APPLICATIONS OF BIOMASS

5 SUMMARY The forest products industry is, and probably will remain, the prime user of biomass for energy in the United States. Its use of wood residuals for energy fiber will probably double by 2000 in replacement of fossil fuel and purchased electricity. Beyond 2000, use of biomass will continue to grow with the total production of pulp and paper. It is unlikely that the forest products industry will install short-rotation hardwood plantations for energy, but it may well adopt this tree technology to provide raw material for fine paper and composite boards as well as simultaneously providing the energy fiber to manufacture these products.

BIOMASS FOR ENERGY IN THE FOREST PRODUCTS INDUSTRY 43

Fig. 1. U.S. pulp, paper, and paperboard industry

44 ENERGY APPLICATIONS OF BIOMASS

Fig. 2. Pulp and paper industry energy use per unit of output

SECTION II Research Interests of Biomass Sponsors

BIO-ENERGY PROGRAMS AT THE U.S. DEPARTMENT OF ENERGY M.GUTSTEIN* and D.RICHARDS* *Chairman, DOE Bio-Energy Coordinating Committee +Science

Applications International Corporation

SYNOPSIS The purpose of this paper is to describe the U.S. Department of Energy (DOE) Bio-Energy Coordinating Committee (BECC), an organization for information exchange and communication among the DOE offices involved in bio-energy, and to provide a brief overview of bio-energy programs and activities conducted by DOE. 1 THE DEPARTMENT OF ENERGY’S BIO-ENERGY COORDINATING COMMITTEE The Bio-Energy Coordinating Committee (BECC) is an internal DOE committee comprising representatives of all organizations involved in bioenergy. The purposes of BECC are: • to achieve effective coordination of DOE’s bio-energy research and development (R&D) programs; • to assure optimum use of DOE’s existing expertise in bio-energy R&D; • to provide a way for industrial and other users to access information rapidly on DOE bio-energy programs/technology; and • to achieve rapid communication within DOE of new developments, opportunities, and problems in bio-energy research and technology development. The committee was originally established in 1980 as the Biomass Energy Coordinating Committee. However, in July 1984, “bio-energy” was substituted for “biomass energy” to expand the scope of the committee to encompass all areas of biotechnology that play a role in the production, conversion, and use of energy resources. The impetus behind this decision was the realization that a common technology base in biochemistry and genetics was being applied independently in a number of DOE programs involving both biomass and

BIO-ENGERGY PROGRAMS AT THE US DEPARTMENT OF ENERGY 47

nonbiomass energy resources. The committee agreed that BECC could provide a much needed forum for communication among and coordination of these diverse programs. Currently, the following DOE organizations are represented on BECC: • Office of Renewable Energy – Biomass Energy Technology Division – Energy from Municipal Waste Division • Office of Conservation – – – – –

Building Equipment Division Waste Energy Reduction Division Improved Energy Productivity Division Office of Vehicle Engine Research and Development Division of Energy Conversion and Utilization Technologies

• Office of State and Local Assistance Programs • Office of Energy Research – Office of Basic Energy Sciences – Program Integration Division – Ecological Research Division • Office of Fossil Energy – Office of Planning and Environment • Office of Policy, Safety, and Environment – Office of Policy Integration – Office of Environmental Analysis • Office of Information Administration – Nuclear and Alternate Fuels Division A list of BECC members is included in the Appendix. 2 DOE BIO-ENERGY R&D PROGRAMS Bio-energy R&D programs are supported by the following DOE offices:

48 ENERGY APPLICATIONS OF BIOMASS

• • • • •

Renewable Energy Conservation Energy Research Fossil Energy Bonneville Power Administration

The following paragraphs describe the bio-energy R&D activities directed by these offices. 2.1 Office of Renewable Energy The Office of Renewable Energy’s Biomass Energy Technology (BET) and Energy from Municipal Waste (EMW) Divisions collectively represent DOE’s largest effort in bio-energy R&D. The goal of these programs is to provide a technology base for the use of biomass and municipal wastes for energy such that private industry will invest in these technologies. BET supports programs in the following areas: • biomass feedstock production research – short-rotation woody crops – herbaceous crops – aquatic species • biomass feedstock conversion research – biochemical – Zthermochemical EMW supports R&D to convert municipal wastes to fuels and energy through mechanical, biochemical, and thermochemical technologies. 2.2 Office of Conservation The Office of Conservation supports several bio-energy related programs that are aimed at the development of technologies for producing and utilizing fuels and chemicals from renewable resources that are cost-competitive alternatives to nonrenewable fuels and chemicals and that enhance national energy security. The following are the major technical thrusts of the Office of Conservation’s R&D in bio-energy: • wood-fired space heating systems

BIO-ENGERGY PROGRAMS AT THE US DEPARTMENT OF ENERGY 49

• use of industrial and agricultural wastes for fuels and chemicals • use of alcohol fuels for transportation • biocatalysis in the production of chemicals from biomass and nonbiomass feedstocks. 2.3 Office of Energy Research The Office of Energy Research (OER) conducts basic research aimed at increasing the understanding of fundamental principles and mechanisms related to biomass production and conversion and energy-related biotechnology. OER’s major technical thrusts in bio-energy include: • • • • •

photosynthetic energy conversion and plant productivity microbiology and genetics of anaerobic microorganisms bioconversion of cellulose to alcohol kinetics of enzyme-catalyzed reactions physiological ecology, including investigation of metabolic pathways and adaptation and tolerance to stress. 2.4 Bonneville Power Administration

The Bonneville Power Administration conducts R&D in bio-energy using ratepayer funds and the support it receives from DOE’s Biomass Energy Technology Division for managing the Alaska and Pacific Northwest Regional Biomass Energy Program. These R&D activities are aimed at the development of biomass as an integral part of the region’s electric energy resources. BPA’s major technical thrusts include biomass conversion technology for the electric utility industry and the identification and mitigation of adverse environmental impacts associated with using biomass for energy. 2.5 Summary of R&D Programs Figure 1 summarizes the R&D activities conducted by each DOE office in terms of the major categories, feedstock production, and conversion. Note that of all the technologies shown, biochemical conversion research is being performed universally by all of the DOE offices active in bio-energy R&D. The technology areas addressed by DOE’s bio-energy R&D effort are summarized in Fig. 2. In addition to heat, electricity, and fuels derived from biomass feedstocks, DOE’s bio-energy research interests also include applications in the manufacture of chemicals and in environmental assessment and protection.

50 ENERGY APPLICATIONS OF BIOMASS

The stage of DOE’s R&D effort in various bio-energy technologies and applications is summarized in Fig. 3. It shows that R&D is being conducted by DOE at almost every stage for all bio-energy technologies and applications. The primary exceptions are those of basic research in thermochemical conversion and process development in the manufacture of chemicals. Figure 4 presents the approximate funding for bio-energy R&D by office for FY 1984. The Department spent about $45 million on bio-energy research during that fiscal year. 3 DOE NON-R&D BIO-ENERGY ACTIVITIES The following DOE organizations have bio-energy-related responsibilities that do not involve R&D: • Office of State and Local Assistance Programs • Office of Alcohol Fuels • Office of Energy Research – Program Integration Division • Office of Policy, Safety, and Environment – Office of Policy Integration – Office of Environmental Analysis • Energy Information Administration The Office of State and Local Assistance Programs supports information and technology transfer activities that involve bio-energy, including the EnergyRelated Inventions Program and the National Appropriate Technology Assistance Service. The Office of Alcohol Fuels is authorized under Title II of the Energy Security Act to make loan guarantees to assist in the construction of commercial-size fuel ethanol production facilities. The Program Integration Division is responsible for coordinating the Office of Energy Research’s bio-energy R&D effort. The Office of Policy Integration in the Office of Policy, Safety, and Environment (OPSE) oversees the development of DOE policy regarding bioenergy issues. The Office of Environmental Analysis is responsible for reviewing the environmental implications of DOE bio-energy R&D efforts. The Nuclear and Alternate Fuels Division of the Energy Information Administration collects data on the consumption of wood in the industrial, residential, commercial, and utility sectors. Figure 5 summarizes the non-R&D activities in bio-energy at DOE.

BIO-ENGERGY PROGRAMS AT THE US DEPARTMENT OF ENERGY 51

APPENDIX DOE BIO-ENERGY COORDINATING COMMITTEE MEMBERSHIP AND REPRESENTATIVES

A list of the members of the DOE Bio-Energy Coordinating Committee is included below. For further information on any of the programs described in this paper, please contact the appropriate organization using the telephone number shown, or at the following mailing address using the mail stop code indicated: U.S. Department of Energy 1000 Independence Avenue, S.W. Mail Stop——— Washington, DC 20585 MEMBER ORGANIZATION Office of Conservation and Renewable Energy Biomass Energy Technology Division Energy from Municipal Waste Division Building Equipment Division Waste Energy Productivity Division Improved Energy Productivity Division Office of Vehicle Engine R&D Energy Conversion and Utilization Technologies Division Office of State and Local Assistance Programs Office of Alcohol Fuels Office of Energy Research Office of Basic Energy Sciences Program Integration Division Ecological Research Division Office of Fossil Energy Office of Planning and Environment Office of Policy, Safety, and Environment Office of Policy Integration Office of Environmental Analysis Energy Information Administration Nuclear and Alternative Fuels Division

MAIL STOP TELEPHONE NO.

CE-321 CE-323 CE-112 CE-121 CE-122 CE-13 CE-112

(202)252–6741 (202)252–8021 (202)252–9130 (202)252–2898 (202)252–2455 (202)252–8055 (202)252–1484

CE-20

(202)252–9104

CE-80

(202)252–1277

ER-17 ER-32 ER-75

(301)353–2873 (301)353–4355 (301)353–5778

FE-13

(301)353–2773

PE-15 PE-26

(202)252–6296 (202)252–4760

EI–Z-53

(202)252–9775

52 ENERGY APPLICATIONS OF BIOMASS

Fig. 1. DOE B&D by bio-energy technology

Fig. 2. DOE R&D in bio-energy applications

BIO-ENGERGY PROGRAMS AT THE US DEPARTMENT OF ENERGY 53

Fig. 3. Stage of DOE R&D in various bio-energy technologies and applications

Fig. 4. FY 1984 funding for DOE bio-energy R&D

54 ENERGY APPLICATIONS OF BIOMASS

Fig. 5. Summary of DOE’s non-R&D bio-energy activities

TVA BIOMASS FUELS PROGRAM J.M.STINSON* *Tennessee Valley Authority

SYNOPSIS Biomass offers an alternative to fossil fuels and hence an opportunity for the United States and the Tennessee Valley region to become less dependent on imported petroleum. While biomass can meet only a portion of the fuel requirements, it has potential to make valuable contributions. Biomass also offers potential for less centralized energy production relative to electrical generation, petroleum refining, and pipeline distribution systems as a strategy in the unfortunate event of war. Moreover, biomass relies on renewable energy supplies rather than on mining a depletable (stock) resource. The southeastern United States, of which the Tennessee Valley region is an integral part, has substantial biomass potential because of the relatively long growing season, abundant rainfall, and underutilized land and forest resources. However, research and development activities are needed to transform these potentials into realities. 1 PROGRAM The Tennessee Valley Authority’s (TVA) Biomass Fuels Program is designed to develop information to assist industry in commercializing the use of renewable resources—primarily for energy purposes. This would reduce dependence on foreign oil and hence provide for improved national defense and balance of payments; it would improve resource use; and it would provide economic development, especially for rural areas. The program emphasizes the use of underutilized hardwood resource of the region with a focus on development of an efficient and economical process for producing liquid fuel from wood. Significant amounts of underutilized (marginal) land also exist. Avenues are being pursued to develop this resource into possible renewable energy production, thereby providing potential to increase farm income without adverse impacts on the environment and food production.

56 ENERGY APPLICATIONS OF BIOMASS

While the program has several integrated facets designed primarily for Valley conditions, the technologies and concepts have national and international applications and implications. Activities in the program include: (1) forestry resource assessments, (2) forestry management studies, (3) forestry harvesting techniques, (1) development of technologies for conversion of biomass (both woody and nonwoody) primarily into energy products, (5) technical monitoring of the U.S. Department of Energy’s (DOE) loan guarantee program, (6) management of the Southeastern Regional Biomass Energy Program (SERBEP) for DOE, (7) technical assistance to the Agency for International Development (AID) of the U.S. Department of State in developing and implementing a bioenergy program for less-developed countries, and (8) transfer of technology. 2 RESOURCES POTENTIAL The Tennessee Valley has an abundant and currently underutilized hardwood resource. Over 50% of the 58.5 million acres of land in the valley is forested, and 80% of the forests is hardwoods. Even before the recent recession, which was particularly deep in the forest industry, only about one-third of the annual growth of hardwoods was harvested each year. Preliminary estimates indicate that with current forest management practices the wood supply available for biomass fuel uses in the Tennessee Valley area is sufficient to (1) displace nearly one-third of the oil and natural gas currently used for space heat and process steam in commerce and industry, and (2) replace one-fifth of the current automobile fuel needs of the valley region. TVA foresters carry out activities for the Biomass Fuels Program in the areas of wood availability, cost of harvesting and transporting wood for energy, management of forests for energy, and technical assistance to industry. In addition to the forestry resource, nearly 2 million acres of underutilized open lands exist in the Valley, some of which may be suitable for producing energy crops. The Tennessee Valley is one of the best suited regions of the nation for biomass production because the relatively warm climate allows a long growing season, which is complemented by high annual rainfall (40–65 in.); the heavy rainfall, however, does pose concerns in terms of soil erosion. Agriculturists have addressed some of the questions related to land availability for fuel energy crop production. 3 EXPERIENCE TVA has a history of work in biomass activities dating back to the late 1940s; and, of course, work in forestry and agriculture was organized soon after the formation of the agency. The U.S. government constructed a wood hydrolysis plant at Springfield, Ore., in the 1940s based on research improvements to the

TVA BIOMASS FUELS PROGRAM 57

Scholler acid hydrolysis process. This plant was not as successful in its technical performance as had been anticipated, and combining this with changing political and economic situations led to its abandonment. The Forest Products Laboratory (FPL-Madison, Wis.) of the U.S. Department of Agriculture (USDA) then asked TVA to further develop the research by scaling up a proposed modified process (commonly referred to as the “Madison” process). Subsequently, TVA constructed and operated a pilot plant at Muscle Shoals. In this pilot plant, wood was hydrolyzed to sugars via a percolation acid hydrolysis route. The sugars (primarily C6 since the process tended to degrade C5 to furfural) were successfully concentrated to a blackstrap molasses substitute. When molasses prices declined substantially shortly thereafter, interest vanished and further development was discontinued. Numerous other joint research projects were conducted with the FPL over the next three decades, including development of fire retardant materials, which are now widely recommended and used throughout the United States. The 50 successful years of experience in research, development, and technology transfer of TVA’s National Fertilizer Development Center provide a solid foundation for TVA’s biomass technology development and transfer program. About three-fourths of the commercial fertilizers used in the United States have been developed or improved at TVA’s National Fertilizer Development Center. The mechanism for similar results in the biomass area is already in place, with a comprehensive program ranging from basic research through bench-scale, pilot-plant, and technology-transfer activities. TVA also is charged with aspects of national defense, valley programs for reforestation, land use, and economic development, which complement biomass program objectives. 4 PROJECTS SUPPORTED BY CONGRESSIONAL APPROPRIATIONS Growing interest in and concern for fuel energy and resource development led TVA to organize a formal biomass effort in 1980. The emphasis is on the underutilized hardwood resource, which has potential to provide liquid fuel, our nation’s real energy need. With FPL’s and TVA’s cooperative efforts reestablished, a two-stage, short retention time, acid hydrolysis concept was adopted for research and development. A Swedish scientist, Karl Cederquist, had envisioned this process following his association with FPL representatives at the Springfield, Ore., wood hydrolysis plant. Research to develop an efficient and economical process for converting hardwoods to liquid fuels became the core of the program, with work on developing the “Cederquist” concept receiving the primary emphasis. The improved concept for production of alcohol from hardwood, which includes greater utilization of all cellulosic components, is being studied in TVA laboratories. This concept involves two-stage hydrolysis of wood with short

58 ENERGY APPLICATIONS OF BIOMASS

hydrolysis retention times, explosive release to physically disrupt the wood, and use of dilute sulfuric acid to form solutions of predominantly five-carbon and sixcarbon sugars, respectively, from the two stages (Fig. 1). These sugars are then available for fermentation to ethanol. Design work is in progress, and equipment for a 2-ton-per-day, pilot-plant facility is being purchased at this time. To improve the economics for commercial use of woody biomass, TVA’s forestry program’s talent and experience are employed to develop practical techniques to reduce the cost of woody biomass, transfer technology to industry and private ownership, and assure wood availability, as well as other management and marketing aspects. Improved harvesting systems specifically designed for hardwood fuels use are being tested for technical, economic, and environmental acceptability. Study is under way to determine methods to most economically and efficiently remove trees from the forest under various conditions; demonstrations of the techniques will be used to transfer this information to industry and landowners. These are all important aspects to successful commercialization of an ethanol-from-wood or other energy-fromwood process and must be developed in parallel to the conversion technology. This phase of the Biomass Fuels Program is supported by direct appropriations from Congress. Activities supported by TVA power program funds that directly replace electricity and hence peak loads, such as the residential wood heater project, are not part of the Biomass Fuels Program per se; hence no funds from TVA power revenues are used in the Biomass Fuels Program. 5 PROJECTS SUPPORTED BY CONTRACTUAL ARRANGEMENTS The appropriated funds have been supplemented by contract work. Contracts exist with DOE and AID. 5.1 U.S. Department of Energy TVA’s Office of Agricultural and Chemical Development has been conducting contract work with DOE since 1980 on small-scale technology for converting alternative agricultural crops to ethanol. A contract has also been executed to provide technical monitoring assistance for the DOE loan guarantee program. TVA manages SERBEP for DOE and is just beginning work on improved harvesting equipment for wood for energy. 5.1.1 Office of Alcohol Fuels: In the loan guarantee program, DOE will guarantee loans for construction of privately owned plants to produce ethanol from corn or molasses. Plant sizes range from 15 to 20 million gallons per year. DOE incurs a liability only if the firms default on the loans; hence, technical assistance is necessary to ensure that the plants are properly constructed and

TVA BIOMASS FUELS PROGRAM 59

effectively operated. TVA engineers provide this service for DOE. The National Fertilizer Development Center has provided assistance to the fertilizer industry in plant construction and startup and therefore has demonstrated experience in this general area as well as knowledge of alcohol production technology. The New Energy plant at South Bend, Ind., is nearing completion; it is a 50million-gallon-per-year facility. Tennol, Inc. has completed final preconstruction requirements with DOE and is beginning construction of a 25-million-gallon-peryear plant. Consideration is being given also to construction of plants in Louisiana, Maine, Minnesota, and Nebraska. 5.1.2 Ethanol from Agricultural Materials: DOE has, through the Solar Energy Research Institute (SERI), funded research at Purdue University on the conversion of agricultural residues (such as corn stover and wheat straw) to ethanol. A concentrated sulfuric acid hydrolysis process employing low temperatures and pressures is used. DOE then asked TVA to modify an existing small-scale pilot plant (previously built with DOE funds) to test this process. The modification consists of addition of the following process steps: grinding the agricultural residues, converting the hemicell-ulose and alpha cellulose fractions to fermentable sugar solutions (principally C5; and C6, respectively), and separating the lignin fraction. Communications among SERI, Purdue University, and the staff of TVA have resulted in the design of an experimental facility as a front-end modification of the existing 10-gallon-per-hour ethanol unit built by TVA to obtain benchmark data on grains and numerous alternative starch and sugar crops. The equipment is installed and shakedown tests are being conducted. Figure 2 is a flowsheet for the process. 5.1.3 Southeastern Regional Biomass Energy Program (SERBEP): Regional programs have been established by DOE in four sections of the country, and TVA was assigned responsibility to manage the program in the southeastern part of the United States—an area covering Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Missouri, Mississippi, North Carolina, South Carolina, Tennessee, Virginia, and West Virginia. A purpose of the program is to promote effective use of regional biomass resources to meet regional energy needs. The focus is on information development/ transfer and technology transfer for a broad range of biomass resources, conversion technologies, and end uses. Much of the effort is carried out under competitive contracts selected with the assistance of key representatives of industry, academia, and government. Specific objectives include (1) establishing the availability of biomass resources within the defined regions through resource assessment studies, (2) enabling industry to match local resources with conversion technologies that will permit private sector investments in biomass energy technologies, (3) transferring results of research and development to the private sector, and (4) establishing a partnership with industry through cost-shared projects that will build private sector confidence in adopting biomass energy technologies.

60 ENERGY APPLICATIONS OF BIOMASS

5.1.4 Harvesting of Woody Biomass: TVA has recently agreed with representatives of DOE to conduct activities to develop/improve technology for harvesting wood for energy. The focus is on equipment for harvesting shortrotation intensive tree crops and other small-diameter energywood (such as from rights of way and tree crowns from traditional forest harvest operations). 5.2 Agency for International Development The Agency for International Development (AID) has requested TVA to provide technical assistance for its bioenergy program, which assists less-developed countries (LDCs). In effect, TVA serves as a contractor acting under the direction of AID. The request was to help establish and implement an effective program for bioenergy development in LDCs. A small staff of TVA employees assigned to the AID offices in Washington, D.C., coordinates the work, which entails planning, coordination, training, and literature reviews. It also includes travel to LDCs to assess bioenergy resources, suggest applicable conversion technologies, and recommend energy development strategies. Projects have been undertaken or considered in many countries including Costa Rica, India, Indonesia, Jamaica, and the Philippines. 6 COORDINATION In addition to the FPL linkage and contractual work with DOE and AID, TVA has emphasized coordination on a national and international basis. Many organizations have been contacted in an attempt to avoid duplication of effort and to seek cooperation and exchange of information.

TVA BIOMASS FUELS PROGRAM 61

Fig. 1. Ethanol from wood concept

62 ENERGY APPLICATIONS OF BIOMASS

Fig. 2. Low-temperature, low-pressure, two-stage, acid hydrolysis concept for conversion of nonwoody feedstocks to ethanol

OVERVIEW OF USDA ENERGY POLICY PERSPECTIVES E.E.GAVETT* *Office of Energy, U.S. Department of Agriculture Washington, D.C.

Yesterday, Department of Energy (DOE) Under Secretary Pat Collins reviewed Administration policy as stated in the fourth National Energy Policy Plan. That policy identified renewable resources as offering a vast potential source of energy. Another Administration report submitted to Congress in October 1983 was the joint USDA-DOE Biomass Energy Production and Use Plan for the United States. 1983–1990 required under the Energy Security Act (ESA). The biomass plan had two basic policy recommendations: (1) allow market forces to determine the types and quantities of biomass energy to be produced and consumed; and (2) support selected longer term biomass energy research and development. The Biomass Energy Production and Use Plan forecasts that some 4 quads of biomass energy could be produced annually by 1990, with the bulk of it coming from direct combustion of wood and wood residues. This suggests that biomass will produce about 5% of our 1990 energy mix. The Department of Agriculture (USDA) has two major energy concerns relative to agriculture: 1. Energy must be available at the time, place, and in the form and amount needed. Agriculture is a biologically based industry, with timing of some operations critical. Once an enterprise is initiated, energy must be provided within narrow time slots, or livestock may die, crops may wither, or yields may be lost. Also, with most of agriculture at the tail end of the petroleum distribution system, shortages of fuel appear first in rural areas where the adverse impact is greatest. 2. The energy used by farmers needs to be available at reasonable prices. Energy accounts for 7.5% of total farm production costs. Because energy is essential to most operations, energy price increases reduce net farm income. This is of particular concern at this time because American farmers in recent years have been receiving the lowest net farm income in decades as worldwide surpluses of commodities depress prices.

64 ENERGY APPLICATIONS OF BIOMASS

Our farmers are unable to market all of their crops; therefore, government programs to idle portions of cropland have been maintained. If we can develop energy crops that are economically competitive with fossil fuels, we could use those excess acres for productive gain to the farmers and reduce government program costs to the nation. Two weeks ago, at the Washington Conference on Alcohol Fuels, Secretary Block restated his continued support for biomass energy. “I am proud that alcohol production has gone from 40 million gallons of alcohol production in 1980 to over 400 million gallons projected in 1984 using close to 200 million bushels of grain. I’m proud that our alcohol fuel production capacity has increased fourfold since 1980. “I am proud that the production of other biomass including wood has greatly increased over the last four years. “Without question, continued growth in the domestic ethanol industry will have a major impact upon U.S. agriculture. Increased demand for ethanol as an octane enhancer will increase the demand for corn we are using. In turn, this will increase the price, profitability, and utilization of corn. That means jobs and economic activity for America. “Our policy was—and still is—to allow market forces to determine the types and quantities of biomass energy produced and consumed. We also feel that the tax exemption has been very helpful in helping develop an alcohol fuels industry. “We shall continue our research and development activities for biomass energy. The goal shall be to improve conversion technologies and lower production costs that will allow biomass energy to someday be substituted for liquid, gaseous, or solid fuels. “We believe this research is vital to reducing the costs of biomass energy so it can compete head to head in the marketplace with conventional fuels. “In line with that effort, we will be conducting a forum next month to look into new uses for farm products. This is the second in a series of what I call ‘challenge forums’—to address some of the major issues facing agriculture. “This two-day session will focus on bringing together the public and private sectors for an in-depth look at new products, new uses, and new markets for agricultural products. “We have, at least temporarily, excess production capacity in our agricultural plant. Farmers want to produce. We can use the jobs. Let’s put these resources to work. “The transformation of crops into energy for fuel offers an exciting opportunity for agriculture to serve this country in a nontraditional, but new and very vital, way.” For those engaged in forestry, fuel production is not a new venture but it has renewed emphasis. We now use in excess of 2.6 quads of wood energy. The forest products industry consumed over 1.6 quads of wood residue as fuel in 1983 • About 1 quad was used as household fuel in stoves for space heating.

OVERVIEW OF USDA ENERGY POLICY PERSPECTIVES 65

The USDA policy is to maintain biomass energy research and development even though other fuels currently are plentiful and energy prices stable. The USDA Biomass Energy Research and Development program has been funded in excess of $20 million per year for the past several years. Within USDA, Biomass Energy Research and Development is performed by three principal agencies— Forest Service (about $10 million), Agricultural Research Service (about $6 million), and Cooperative State Research Service (almost $1 million). While changes in program emphasis are occurring, our interest in developing competitive energy crops from renewable resources shall continue.

THE FOREST SERVICE’S WOODY BIOMASS PROGRAM F.B.CLARK* *Associate Deputy Chief for Research, Forest Service, U.S. Department of Agriculture, Washington, D.C.

The use of woody biomass is becoming increasingly important to each of the three major management areas of the Forest Service—National Forest System, State and Private Forestry, and Research. The National Forest System is responsible for managing more than 150 national forests throughout the country. An important goal of forest managers is multiple use management of these forests to obtain maximum benefits for all U.S. citizens. Timber harvesting and utilization are important components of this goal, but a profusion of low-value woody biomass in many forests makes this task difficult. For instance, low-value hardwoods of poor form or from low-value species are difficult to harvest and use profitably. Yet, if these cull trees are left on the land, they interfere with the establishment and care of more desirable tree stands. The problems are much the same with softwoods killed by insects and disease in different parts of the country and mortality of trees from natural destruction such as fire, high winds, or even a volcanic eruption as on Mount St. Helens. The National Forest System has long had a fuelwood use program through which homeowners are issued permits for cutting of firewood to provide fuel for heating their own homes. This has always provided some assistance in removing undesirable material from the forest, but it has become much more significant since the oil crisis of 1973. Firewood gathering is now a major activity in many forests. In the past, most firewood-cutting permits were issued at no cost. However, in 1983, a nominal minimum fee was instituted. Thus, in 1983 there was a slight dropoff from 1982 when nearly 5.6 million tons (4.7 million cords) were removed. The National Forest System also has demonstration projects with industrial fuelwood users based on innovative approaches to tinter sales. In one example, removal of firewood from a saw timber sale earns a timber purchaser credit for cleanup that can be applied toward brush cleanup responsibilities. In California, to prepare for more intensive utilization, a biomass inventory of national forests is under way. The State and Private Forestry section of the Forest Service is concerned with assistance to private forest landowners and state and local governments. One program, Cooperative Forest Management, has wood-energy specialists to assist

THE FOREST SERVICE'S WOODY BIOMASS PROGRAM 67

in setting up local wood-energy programs. As part of this program, a procedure has been developed to provide a relatively fast method for ascertaining the feasibility for an industry to replace a fossil-fuel burning energy system with a wood-burning one. The preliminary economic analysis may also be used to compare the economics of alternative systems where no energy system exists. The State and Private Forestry section also provides management assistance to produce wood for energy on nonindustrial private lands. The third area of emphasis in the Forest Service, Research, provides the main focus for my presentation today. We have 79 research work units in which some portion of the work is energy related. Of these projects, the main thrust of 36 is silviculture; 6 are in tree genetics; 19 are in forest products utilization; 4 involve harvesting and forest engineering; 9 are concerned with resource evaluation; 9 work in economics, marketing, and taxation; 2 are concerned with fire behavior and air quality; and 3 are tied to the impacts of insects and disease on forests. Three silviculture projects that are heavily energy related are SEAM (Minelands Restoration) at Berea, Ky., with an energy interest of 100%; Mineland Reclamation at Logan, Utah, with an energy interest of 70%; and Mine Spoil Reclamation at Albuquerque, N.M., with an energy interest of 50%. Restoring strip-mined lands and mine-spoil banks to productivity with tree plantations is important to reduce adverse environmental impacts from coal mining and, possibly, to provide a new source of fuel from the trees that are planted. A project on pinyon-juniper woodland management and ecology at Reno, Nev., has a 50% energy interest; and a project on pinyon-juniper ecosystems at Flagstaff, Ariz., has a 10% energy interest. Pinyon-juniper production for energy and other purposes offers the potential for more effective use of arid lands. A major project for increasing production of trees for energy and fiber is under way at Rhinelander, Wis., and is 50% energy-related. We are cooperating here and in other locations with the major U.S. Department of Energy effort to produce high yields of tree biomass in short rotations. Other intensive culture Forest Service projects are located in Olympia, Wash., and Charleston, S.C. Other silvicultural research projects can provide increased production of wood for energy through improved natural stand management. Table 1 lists natural stand management projects and other silviculture research work units. Table 1: Silviculture energy-related research projects in the Forest Service, September 1984 number

title

location

energy interest (%)

INT-1603 INT-1753

Mine land Reclamation Pinyon/Juniper Woodland Management and Ecology Ecology and Management of Great Basin Range land

Logan, UT Reno, NV

70 50

Provo, UT

10

INT-1703

68 ENERGY APPLICATIONS OF BIOMASS

number

title

INT-1752

Shrub Improvement and Revegetation NC-1103 Silvics of Northern Conifers and Aspen NC-1109 Silvics Oak/Hickory NC-1112 Intensive Culture for Fiber and Energy NE-1103 Culture of Appalachian Hardwoods NE-1104 Management of Birch, Beech, Maple NE-1151 Culture of Spruce/Fir NE-1152 Management of Appalachian Map le /Oak NE-1351 Management and Measurements of Eastern Hardwoods NE-1601 Nutrient Depletion NE-1605 SEAM (Mineland Restoration) PNW-120 1 Reforestation Systems

location

energy interest (%)

Provo, UT

10

Grand Rapids, MN

20

Columbia, MO Rhinelander, WI

10 50

Parsons, WV

20

Durham, NH

15

Orono, ME Warren, PA

15 15

Delaware , OH

15

Durham, NH Berea, KY Corvallis, OR

20 100 20

Table 1: Silviculture energy-related research projects in the Forest Service, September 1984 (concluded) number PNW-1207

title

Intensive Culture of DouglasFir PNW-1601 Soil Stability and Water Quality PSW-1201 Silviculture of Sierra-Nevada Forests PSW-125 1 Timber and Watershed Management in Hawaii PSW-1252 Pacific Islands Forestry PSW-1207 Establishment and Maintenance of Regeneration for California Forests RM-1252 Multiresource Management RM-1603 Control of Wind-Transported Snow RM- 165 1 Mine Spoil Reclamation RM-1751 Management in the High Plains RM-2152 Pinyon/Juniper Ecosystems

location

energy Interest (%)

Olympia, WA

30

Wenakhee, WA Redding, CA

10 20

Honolulu, HI

25

Honolulu, HI Redding, CA

25 20

Fort Collins, CO Laramie, WY

20 25

Albuquerque, NM 50 Rapid City, SD 50 Flagstaff, AZ 10

THE FOREST SERVICE'S WOODY BIOMASS PROGRAM 69

number

title

location

energy Interest (%)

RM-2251 SE-1102

Trees for the Plains Stand Development of Appalachian Hardwoods Management of Piedmont Hardwoods Intensive Management Assessment Intensive Culture of Southern Pines Silviculture of Southern Pines (Gulf) Integrated Resource Management Regeneration and Management of Southern Hardwoods Control of Vegetation Management of Small Properties

Lincoln, NE Asheville, NC

10 20

Clemson, SC

25

Gainesville, FL

25

Charleston, SC

15

Alexandria, LA

15

Sewanee, TN

10

Stoneville, MS

20

Auburn , AL Monticello, AR

10 25

SE-1118 SE-1153 SE-R&D SO-1102 SO-1105 SO-1110 SO-1116 SO-1117

Table 2 lists tree genetics energy-related projects in the Forest Service. Genetics can play a major role in the selection of hybrids and superior trees to obtain maximum biomass production and other desired traits, such as disease resistance. Clones of hybrid poplar trees developed at our northeastern station are commonly used in plantations to produce biomass for energy in the northern United States. Table 2: Tree genetics energy-related projects in the Forest Service, September 1984 number

title

location

energy interest (%)

NC-1401 NE-1401 PNW-1401 PSW-1401 SE-1499 SO-1401

Genetics of Northern Trees Genetics of Northeastern Trees Genetics of Douglas-Fir Genetics of Western Trees Genetics of Forest Trees Genetics of Southern Pine

Rhinelander, WI Durham, NH Corvallis, OR Berkeley, CA Raleigh, NC Gulfport, MS

15 15 15 15 15 15

Table 3 lists wood utilization energy-related research. Utilization of wood for energy and conservation of energy through more efficient use of wood in numerous other consumer products are important goals in 19 of our research projects. Much of our energy-related wood utilization research is conducted at the Forest Products Laboratory in Madison, Wis. Madison is also the headquarters

70 ENERGY APPLICATIONS OF BIOMASS

for a National Energy from Wood Research, Development, and Application program. Our research on the conversion of wood to fuels ranges from solid wood fuel to charcoal and fuel alcohol from wood. In 1980, the Forest Products Laboratory began work on a two-stage hydrolysis process first proposed by the Stora Kopparberg Company in Sweden about 1944. The two-stage process is particularly appropriate for hardwoods, since it facilitates recovering both fiveand six-carbon sugars from wood particles. Single-stage processes concentrate mainly on six-carbon sugars, but the five-carbon sugars are a significant fraction in hardwoods. They may be used as raw materials for valuable chemical products. The use of higher temperatures and less liquid in the new process requires about 25% less capital investment, and energy costs are reduced about 40%. The research is now being adapted for the design and construction of a pilot plant by the Tennessee Valley Authority. Table 3: Wood utilization energy-related research projects in the Forest Service, September 1984 number INT-3251

title

Improving Wood Resource Utilization INT-R&D Intensive Timber Utilization (STEM) NC-3201 Processing Hardwoods NE-3102 Grade and Quality of Northeastern Trees NE-3201 Hardwood Utilization PNW-3101 Quality and Product Yield PNW-2107 Forest Residues and Energy SE-3101 Utilization of Southern Timber SO-320 1 Processing of Southern Woods FPL-3204 Improved Adhesives Systems FPL-3212 Protection of Wood Used in Adverse Environments FPL-3214 Improvements in Drying Technology FPL-3306 Criteria for Fiber Product Design FPL-3308 High-Yield Nonpolluting Pulping FPL-3309 Fiber Process and Product Development FPL-3403 Improved Chemical Utilization of Wood FPL-34 10 Microbial Technology in Wood Utilization

location

energy interest %

Missoula, MT

30

Missoula, MT

30

Carbondale, IL Delaware, OH

45 10

Princeton, WV Portland, OR Portland , OR Athens, GA Alexandria, LA Madison, WI Madison, WI

40 25 40 25 20 30 20

Madison, WI

20

Madison, WI Madison, WI Madison, WI

30 20 15

Madison, WI

30

Madison, WI

30

THE FOREST SERVICE'S WOODY BIOMASS PROGRAM 71

number

title

location

energy interest %

FPL-34 11

Energy and Chemical Production from Wood (RD&A Program) Engineered Wood Structures

Madison, WI

100

Madison, WI

20

FPL-3506

We are particularly optimistic about research that may lead to fermenting fivecarbon sugars to ethanol. This could bring about a doubling of the ethanol yield by acid hydrolysis of hardwoods that are currently in large surplus in the eastern United States. Another prospect for increasing the ethanol yield from wood is through research on enzyme hydrolysis. We have some strong research and development programs to improve the processing of wood to various products. Improvements in processing go hand in hand with energy conservation. Based on past experience, we can signifi cantly increase future processing efficiencies. For example, recent Forest Products Laboratory research on the press drying of paper has resulted in a new process that can reduce the total energy consumed in making paper from hardwoods by 19%. At the Forest Products Laboratory, renewed emphasis is being given to research on combustion and gasification of wood. Researchers have obtained information on the kinetics of wood combusted in suspension that may be used to design more efficient wood-burning equipment. Fundamental work on wood combustion is an essential step toward increasing efficiency above the best levels now attainable. We hope that some new research efforts on pyrolysis and gasification of wood will also result in a more favorable position for wood fuel in comparison with gas, oil, and coal. Because of changed building construction practices as a result of rising energy costs, more building insulation is being used and air leakage in buildings is greatly reduced. These factors can combine to create moisture problems within walls, floors, and roofs of wood-frame homes. Researchers at the Forest Products Laboratory are working to ensure that moisture accumulation does not become a major problem. A theoretical model, which considers the effect of air leakage, has been developed to analyze moisture movement through walls. Data on seasonal moisture changes in walls have been obtained with field experiments. Manufacturers of siding and insulation materials are using results of these studies in their recommendations to builders. At other research stations researchers are working on more intensive utilization of local species and are evaluating the effects of more intensive removal of biomass from forests on soil nutrients and soil erosion. Utilization researchers are also working on the assessment of existing biomass. Traditionally, timber inventories have provided information only on the availability of wood for high-value uses such as lumber, veneer, poles, and pulpwood, but equations are now being refined to accurately determine total tree biomass from timber inventory data.

72 ENERGY APPLICATIONS OF BIOMASS

Table 4 lists four harvesting and forest engineering energy-related research projects. Harvesting wood for energy has some unique problems. Normally wood for energy is composed of smaller trees and trees that are crooked, decayed, or otherwise defective. Even though smaller and defective trees are less valuable, they are often more expensive to harvest. Researchers at the Intermountain Station field tested and evaluated several harvesting systems that handle small trees more efficiently than conven tional harvesting. The researchers found that the most effective systems incorporated feller-bunchers, grapple skidders, wholetree chippers, and equipment to load skidders and transport logs and chips. The benefits are a clean logging site with no residue, utilization of all material harvested, and recovery of both logs and chips to obtain maximum value. Table 4: Harvesting and forest engineering energy-related research projects in the Forest Service, September 1984 number

title

location

energy interest (%)

NC-3701 NE-3701 PNW-3701 SO-3701

Mechanical Harvesting Systems Hardwood Harvest Systems Logging Steep Terrain Engineering Systems for Intensive Management

Houghton, MI Morgantown, WV Seattle, WA Auburn, AL

30 20 25 25

Southern Station research engineers have evaluated several recently developed machines to thin southern pine forests. The results of these studies provide information on production rates, costs, and physical impacts on the soil and residual trees. Several southern forest products companies are using the information in trials of plantation thinnings. Resource evaluation research (Table 5) is concerned with better documentation of the total forest resource. Biomass is included in periodic forest inventories as required by a new Resource Planning Act. A new inventory system is being used in Alaska to survey the natural resources on 32 million acres of the Tanana River Basin in Alaska, an area as large as Alabama. The system uses imagery from satellites, small- and large-scale aerial photography plots, and a newly developed field plot system. Projects on economics, marketing, and taxation (Table 6) also include energyre la ted research. A maple syrup and wood-energy project in Vermont is heavily energy oriented. Wood fuel is used in evaporators to process the maple syrup. Table 5: Resource evaluation energy-related research projects in the Forest Service, September 1984 number

title

location

energy interest (%)

INT-4101

Renewable Resource Evaluation

Ogden, UT

20

THE FOREST SERVICE'S WOODY BIOMASS PROGRAM 73

number

title

location

energy interest (%)

NC-4101 NE-4101 PNW-4101 PNW-4103 RM-4101 RM-1102 SE-4101 SO-4101

Resource Evaluation Resource Evaluation Resource Evaluation of PNW Resource Evaluation of Alaska Analysis Techniques Inventory Techniques Resource Evaluation Resource Evaluation

St. Paul, MN Broomall, PA Portland, OR Anchorage, AK Fort Collins, CO Fort Collins, CO Asheville, NC Starkville, MS

10 20 10 10 15 20 20 20

Table 6: Economies, marketing, and taxation energy-related research projects in the Forest Service, September 1984 number

title

location

energy interest (%)

NC-4203 NC-4252

Economic Analysis of Demand Method for Evaluating Forest Management Forest Economics Increasing Supply of Hardwoods Marketing Maple Syrup and Wood Energy Economics of Management for Multiproducts Land, Taxation, and Economics National Timber and Wood Products Requirements and Utilization Economics

Duluth, MN St. Paul, MN

20 10

Broomall, PA Princeton, WV Princeton, WV Burlington, VT Durham, NC

10 20 20 75 20

New Orleans, LA Madison, WI

10 10

NE-4201 NE-4204 NE-4206 NE-4207 SE-4203 SO-4202 FPL-4151

The Forest Products Laboratory, aided by the University of Wisconsin Survey Laboratory, surveyed U.S. households to learn about residential wood burning and about sources of fuelwood. They found that fuelwood use increased to 42 million cords or 3–4 billion ft in 1981. This was one-fourth the amount used for all other wood products. The survey also showed that about one-fourth of all U.S. households burned fuelwood. In rural areas, one-half of the households burned wood. Half of all wood burners used fireplaces and burned one-fourth of all fuelwood. The other half of all wood burners burned wood in stoves or furnaces and consumed three-fourths of all fuelwood. Fuelwood cut from woodlands was salvaged mostly from dead or down trees and logging residue. Only 28% of the fuelwood came from standing live trees. The estimated value of the wood sold commercially to household wood burners was $620 million during 1981. Fire and atmospheric sciences research (Table 7) is concerned with energyrelated components of fire prevention, hazard reduction, and prescribed burning.

74 ENERGY APPLICATIONS OF BIOMASS

Modeling of wildfire behavior and evaluation of particulate emissions from open fires provide basic information that may be applied to attain greater efficiency in the controlled burning of wood. Modeling also provides guidelines on the potential for improving air quality through the combustion of wood for fuel rather than through incineration at the forest site. Table 7: Fire and atmospheric sciences energy-related research projects in the Forest Service, September 1984 number

title

location

energy Interest (%)

INT-2103 RM-2110

Fire Behavior Air Quality

Missoula, MT Fort Collins, CO

10 70

Insect and disease research projects (Table 8) provide technology for controlling infestations in tree plantations. We hope to find ways to conserve trees that would otherwise be rendered unavailable for energy and other uses. Table 8: Insects and disease energy-related research projects in the Forest Service, September 1984 number

title

location

energy interest (%)

NC-2203 NC-2205 NE-2210

Insects of Forest Plantations Diseases of Forest Plantations Diebacks and Declines

East Lan sing, MI St. Paul, MN Hamden, CT

15 10 10

Continuation of Forest Service projects with energy components will provide solutions to many of the problems and constraints to wider fuelwood production and use. The greatest constraints today are harvesting and transportation costs, resistance by traditional wood users to new outlets for raw material, deficient technology to convert wood to gaseous and liquid fuels, environmental pollution, and lack of infrastructure for handling wood fuels. It will take creativity and imagination to work against these constraints and other adverse economic. factors to use wood for energy. Our goal is to use wood for energy when that is the highest and best use of the resource. Attaining this goal will help to achieve good forest resource management.

ENERGY-RELATED ACTIVITIES OF THE CANADIAN BIOMASS RESEARCH PROGRAM S.HASNAIN* and R.P.OVEREND* *National Research Council, Ottawa, Ontario, Canada

SYNOPSIS The Canadian Government program on Biomass R&D is a reflection of a policy decision to increase Canadian energy independence by substituting a renewable resource for imported petroleum-based fuels and feedstocks. The challenge was to mount an integrated and coordinated R&D program on problems as diverse as the genetic engineering of bacteria for the biological conversion of lignocellulosics, environmental impact assessment, and thermochemical liquefaction of wood—a diversity matched by the number of government departments and agencies that have related jurisdictional mandates. Since the program began, notable progress has been made in programs such as resource assessment, setting of standards for combustion equipment, gathering of data for the improvement of efficiencies and emissions from large industrial boilers, development and commercial demonstration of a high rate anaerobic reactor, development of fluidized-bed gasification technology, a successful bench-scale flash pyrolysis process for wood liquefaction, and a plantation tree harvester. Currently the major elements of the Canadian program are changing considerably. Most of the biomass inventory questions have been answered; we have completed a major techno-economic assessment of forest biomass conversion technologies, and based on this assessment it is clear that the nearterm Canadian biomass opportunities are with combustion applications in the forestry and related industries. There are, however, continuing R&D requirements in emissions and regulatory aspects of combustion as well as in forest residue recovery and new harvesting concepts. A major portion of the bioenergy R&D effort has been toward the supply of liquid fuels. In thermochemical conversion, one concept—the pressurized O2, fluidized-bed reactor—is being demonstrated while the prospects for direct liquefaction have been recognized as being longer term in the light of an IEA study. In the area of the application of biotechnology for lignocellulosic conversion to liquid fuels, it has become apparent to us and to other countries that

76 ENERGY APPLICATIONS OF BIOMASS

economics will continue to be a barrier for some time, particularly if the present forecasts for oil prices hold true. At the National Research Council (NRC), the biotechnology strategy for bioenergy is heavily dependent on the development of multiple uses for the product streams produced from our major lignocellulosic resource base. Central to this concept are the fractionation concepts that are being extensively evaluated in our program along with downstream processes such as fermentation, separation, and waste treatment. 1 INTRODUCTION In Canada the majority of renewable energy other than conventional hydroelectricity is derived from forest biomass. Climate and geography dictate that the major biomass production is in the form of forests. Agricultural biomass production takes place on less than 1% of the land mass and is primarily aimed toward a large export of wheat on the world markets. The zone of productive forest biomass in Canada is spread along its southern latitudes. Above the productive zones there is a gradation of marginal boreal forest, tundra, and, in the extreme north, ice and rock. Agricultural zones occupy a relatively small share of the total land mass. The area of highest forest productivity is found along the western coast ranging from a timber density of about 175 m3/ha to over 420 m3/ ha, equivalent to a biomass mean annual increment of approximately 2–4 ovendried metric ton per hectare (ODt/ha). The major portion of the productive forest zone has a timber density of 70–175 m3/ha equivalent to a mean annual increment of about 1–2 ODt/ha of standing biomass. These values are for natural forest stands and do not take into account the potential gain that could be realized through silviculture, intensive breeding programs, and clonal forestry. An example of what could possibly be achieved in Canadian forestry is illustrated by the clonal plantations of hybrid poplar in Eastern Ontario. Yields of 7–10 ODt/ha have been reported, approximately five times the yield of natural forest poplars. Intensive management would easily double the yield of Canadian forests (Ref. 1) without improvements in the genetics of planting stock. However, a recent study by Forintek Canada (Ref. 2) has shown that the fibre of fast-grown trees through intensive management is inferior to mature trees in a natural stand. But since the quality of a tree is genetically determined (Refs. 3, 4), it is clear that intensive management must be integrated with intensive breeding for varieties that will make optimum use of the silvicultural inputs and at the same time possess other desirable characteristics such as fibre quality, yield, and disease resistance. Clonal forestry through vegetative propagation (using cuttings and, in particular, tissue culture) is the only means for a rapid exploitation of the full genetic gain achieved in a breeding program (Refs. 3, 4, 5, 6). With the state of forestry in Canada deteriorating rapidly, and projections of impending shortages of suitable fibre at the right price (Refs. 7, 8), it is imperative that tree improvement and

ENERGY RELATED ACTIVITIES OF THE CANADIAN BIOMASS RESEARCH PROGRAM 77

breeding programs be accelerated and the full potential of their genetic improvement be exploited through clonal forestry. The relevance of forest productivity to bioenergy is a direct relationship. Nearly 80% of biomass used today in Canada is derived from conventional forestry operations. Increase in forest yield, therefore, will lead to yield increases both for forest products and biomass for energy. At present the forest industry is reluctant to accept increased fibre use even in the form of residues for energy purposes other than its own internal requirements. While at a time of stable oil prices this may be justified, clearly in the long term with rising energy prices there will be increased pressure to find alternatives to fossil fuels. Since it will make strong economic sense to integrate energy and forest products production, effort should be doubled to increase forest productivity to avert potential shortages of low-cost fibre for the industry and to ensure an adequate supply of a cheap feedstock for fuels and chemicals. From a different angle, case studies have shown that integrated pulpwood and energy wood harvesting strategies are economical and simultaneously accomplish the first step in the silvicultural process of forest regeneration (i.e., removal of diseased and low value material) (Ref. 9). 2 FOREST BIOMASS AVAILABILITY AND PRICE Current estimates show that forest biomass represents 4.9% of the total primary energy demand. This is equivalent to 445 PJ (1015 joules). Of this total, 210 PJ are from pulping liquors, 135 PJ are from wood residues, and approximately 100 PJ are from combustion of roundwood for residential space heating, not including fireplaces. Compared to 1976, the beginning of federal government programs to increase biomass utilization, biomass use has increased by 150 PJ, equivalent to an oil saving of 25 million barrels of oil equivalent per year. About one-third of this increase can be directly related to federal incentive programs and federal/ provincial demonstration programs. A conservative estimate suggests biomass will contribute 1 EJ of Canada’s primary energy demand by 2000. Figures 1 and 2 show the 1990 supply/price projections for biomass in Canada. It is now apparent that the share suggested for short rotation forestry (SRF) plantations will not be realized. This is mainly because of a drop and a stabilization in the price of fossil fuels and a serious downturn in the economy, leading to a slower pace of research, development, and demonstration than originally anticipated and, therefore, a slower rate of plantation establishment. Mill residues (Fig. 1), which represent some of the lowest price biomass available, will make up about 15% of the forest biomass. Most of this will be used for energy by the forest industry directly, particularly since it is expected there will be a greater integration of lumber production with pulp and paper. Salvage, merchantable surplus, and logging residues generate the bulk of available

78 ENERGY APPLICATIONS OF BIOMASS

biomass with almost equal proportions of 25% each, while stand conversion for regeneration will contribute about 10%. The price for this biomass (Fig. 2) has a broad range, from almost zero to above $100/ton (Canadian), moisture- and ashfree (maf). Most of the mill residues (about 12 million tons) range from $0 to $15/ton. Another 8 million tons consisting of mill residues and a mix of material from salvage, surplus, stand conversion, and logging residues range from $15 to $30/ton. The bulk of material (almost 40 million ton) consisting of the above mix will cost between $30 and $15/ton, while another 20 million ton will cost as much as $60/ton. The present demand for biomass from forest operations is about 16 million ton (maf), not counting domestic space heating. This suggests that even with a doubling of biomass use through combustion and gasification, almost 30 million ton would still be available for chemicals or liquid fuels production, for a theoretical yield of about 3 billion gal (U.S.) of ethanol. Note also that since substantial amounts of material from salvage operations (fire and disease killed) and collection of logging residues and stand conversion can be extracted at a rather favourable cost, this should give added incentive and generate greater profitability in Canada for a more substantial forest regeneration effort. 3 AGRICULTURAL BIOMASS The existence of a major grain export industry based on the prairie, a region of low population density having relatively low-cost energy available as natural gas, has resulted in only minor use of grains for motor fuel in contrast to the U.S. gasohol program. In consequence, the research emphasis has been based on crop residues such as straw, chaff, stover, and potato culls or on animal residues and manures, especially intensive husbandry of beef and pork. Preliminary investigations of straw availability by Agriculture Canada showed that, in the main cereal grain areas of the prairie provinces, soil tilth and moisture concerns demand the replacement of all the straw into the soil. This is neither practiced nor physically possible with conventional machinery, and thus some controversy continues. However, with a possible increase in no-till methods in the future, a substantial quantity of straw could be available for local energy use, probably only for combustion purposes. Considerable work has been undertaken to hydrolyze the inulin and ferment the fructose in Jerusalem artichokes. Near-term predictions would suggest that liquid fuels from Jerusalem artichokes will not be economical but that it may be profitable to produce a high-fructose syrup instead. In fact, due to the suitability of the crop to land used for growing tobacco, it is possible that farmers may grow it as a replacement crop due to a diminishing tobacco market.

ENERGY RELATED ACTIVITIES OF THE CANADIAN BIOMASS RESEARCH PROGRAM 79

4 HISTORY OF BIOMASS R&D IN CANADA A number of federal government departments and agencies are involved in R&D funding for bioenergy (Fig. 3). Since the beginning of the federal program, the Canadian Forestry Service of Environment Canada, through the ENFOR program, received the majority of contract R&D in silviculture, mechanization, pretreatment, materials handling, resource and environmental assessment, and conversion (including thermochemical and biological processes). On April 1, 1984, the management of the conversion projects was handed over to the Department of Energy, Mines, and Resources. EMR’s primary function is setting energy policy for the country. They have some inhouse projects in combustion of biomass, but most of their biomass R&D activity is subcontracted. Some of these projects are large in terms of dollars because the activities are close to demonstration and commercial application. One is the boiler test program which has turned out to be very successful. It points out major inadequacies in boiler design from the point of view of efficiencies and emissions. In most cases minor modifications have caused considerable savings and improvements. The information being generated is transferred to the boiler manufacturer and is helped by direct involvement of the Canadian Boiler Manufacturers Association in the project. Three other major projects are managed by EMR. The Iotech/ Monenco 1 ton of wood/day plant that uses steam explosion, enzyme hydrolysis, and fermentation to ethanol will come on line early in 1985. The gaseous HF solvolysis process, originally started by Canertech, is now being managed by EMR. Issues that still need to be addressed are reprocessing and recycling of HF and toxicity to the microbes. The lignin is unfortunately highly modified and is expected to be used as fuel. The other is the Biosyn project—a $21 million 10 ton/hour oxygen-blown, fluidized-bed gasifier for MJV gas. Researchers will optimize parameters such as moisture content of feedstocks, operating pressure, and oxygen. It is expected that after cold tests this winter, full testing will begin in 1985. The Natural Science and Engineering Research Council (NSERC) is a federal government agency that grants university R&D funding. They have identified the strategic importance of biotechnology and energy production. In these two categories there are a number of projects of interest to bioenergy development. Through NSERC and a number of in-house projects at NRC, some badly needed basic research is ongoing. It is our feeling that all basic research is in real jeopardy in Canada for very much the same reason as the U.S. “Quadromania syndrome” in biomass R&D as mentioned by Dr. Lip insky. NRC is the prime research agency of the government. The NRC Bioenergy Program does not have its own laboratory facilities but funds projects in our other NRC laboratories such as Chemistry and Biological Sciences. The major R&D effort is, however, subcontracted to universities, provincial research agencies, and the private sector including Forest Engineering Research Institute of Canada

80 ENERGY APPLICATIONS OF BIOMASS

(FERIC) and Forintek. The R&D interests of the NRC Bioenergy Program span a wide spectrum from the use of tissue culture for producing superior trees to downstream processing by reverse osmosis. Agriculture Canada has parallel R&D interests to forest biomass on agricultural residues, energy crops, and biogas. Overall, coordination among all of these interest groups has worked reasonably well. Part of the reason has been that the funding has come from a special envelope that is distinct from the “A” base funds of any department. This has allowed each department to be an equal partner in the relationship. Figure 4 shows the total Bioenergy R&D expenditure trend, starting in 1977 with less than $1 million to about $14 million at the end of FY 1983– 1984. The second oil shock occurred three years after the beginning of the program. At this point, preliminary results of the ENFOR program justified the expansion of Bioenergy R&D in 1980, leading to an increase in the budget for conversion, energy crops, and resource assessment and development. This expansion is also illustrated in Figure 5, which shows the diversification of the program in a comprehensive Bioenergy R&D effort with the greater involvement of other departments along with Environment Canada. This diversification is further illustrated in Figure 6, which reflects the development of the major areas of bioenergy R&D over the last 7 years. In this analysis, the projects related to environmental assessment have been grouped under silviculture. 5 RESOURCE ASSESSMENT As shown in Figs, 4 and 6, resource assessment has been a significant activity for locating the quantity of forest biomass from coast to coast. The work includes conversion of existing volume data on timber to actual mass data on the whole tree and the identification of biomass in relation to specific geographic location and by groupings of type and species. It will also be possible to determine how the quantity of biomass available for energy varies with harvesting methods and wood utilization and to determine the accessibility of the resource. This ENFOR activity, in cooperation with in-house work on new inventories of unsensored areas, is close to completion, and trials have already started in some regions of the country to determine the reliability of data. The last two years have seen an increased effort by Agriculture Canada. Much of this is associated with the assessment of residue availability and crops specifically suited for energy production, in conjunction with both existing agriculture and the cultivation of underutilized land. The purpose of this longterm program is to identify energy crops through planned cropping trials, observation of existing plant stands, and development of agronomic practices.

ENERGY RELATED ACTIVITIES OF THE CANADIAN BIOMASS RESEARCH PROGRAM 81

6 SILVICULTURE Projects under this title could suitably be subtitled “Forest Management for Biotnass Production in an Environmentally Sound Manner.” Two areas are achieving prominence: the growth of energy plantations, and the use of computer simulation to evaluate the consequence of different management and silvioultural practices. The former is the subject to considerable federal/ provincial collaboration, and participation in the IEA has resulted in significant attention being paid to this new area of silviculture. The computer model FORCYTE (FORest nutrient Cycling and Yield Trend Evaluator) developed under ENFOR is an ecologically based forest management simulation designed to estimate the long-term consequences of intensified biomass production and harvesting. Several versions of the model have been developed, calibrated, and tested; although originally designed and calibrated for Douglas fir ecotypes, the model is now being calibrated for and applied to other Canadian forest ecotypes through a series of ENFOR projects. The model has attracted considerable scientific interest worldwide and is now being tested in several countries. It is likely that in Bioenergy R&D, silviculture will maintain its relative share of both budget and priority as the program evolves. 7 HARVESTING AND PLANTATION TECHNOLOGY Considerable effort has been concentrated in this area. Under ENFOR and NCR there have been several prototype systems constructed and evaluated in conjunction with Forest Energy Research Institute of Canada (FERIC) and the private sector. Highlights include: • RECUFOR. For collecting and preprocessing logging residues that remain after short-wood harvests. A prototype was constructed and field-tested; the concept and general design features are considered proven. Its large size and high cost may restrict its application. • Logging Residue Processor (LRP; previously Recufor S). For collecting and processing (fully) logging residues accumulated along roads and at landings during full-tree harvests. Prototype was field-tested in summer 1984. • Crabe Combine. This machine, a much modified Canadian version of the Finnish Palari Brush Harvester, is for swath harvesting and chipping brush and small trees. The high cost and very heavy carrier may limit the potential of this machine to special applications such as clearing rights-of-way. • Separator Shear. For chunking large pieces and separating biomass and debris that accumulates in West Coast log sortyards. Prototype has been constructed and successfully tested.

82 ENERGY APPLICATIONS OF BIOMASS

Early field evaluations of existing methods of recovering forest biomass residuals in Newfoundland and New Brunswick have contributed directly to their utilization on a commercial basis. At the same time, the machinery development program has started to fill in some of the productivity short-comings of existing machinery. The development of plantation machinery is being pursued at NRC in conjunction with the government of Ontario’s hybrid poplar program. A complete system based on agricultural machinery is evolving to cover the cycle from field clearance through planting and tending to final harvest. Three machines have already completed one year of successful field testing. One is a continuous harvester/buncher designed for 5-year hybrid poplar plantations. It is an attachment for existing agricultural tractors and has a productivity of 1000 trees per hour at a ground speed of 2.5 km/h. The other two include a unique grapple skidder and a front-end loader for forwarding and loading the bunched trees. 8 TECHNO-ECONOMIC ASSESSMENT The major foundation of the ENFOR program was the InterGroup 1977 study, which received nearly 30% of the program expenditures in that year. Since that time, techno-economie assessments have become a diminishing proportion of the budget. The current major techno-economic assessment is “A Comparative Assessment of Forest Biomass Conversion to Energy Forms,”which assesses the different unit processes in biomass conversion ranging from pretreatment, drying, and chipping to alcohol production. The six data books are being released. 9 THERMAL CONVERSION Thermal conversion, especially gasification and pyrolysis, was a major element of the early program since combustion was considered to be a “mature” technology. The program evolution has led to the diminished share of thermal conversion and has become more involved with performance evaluations of large-scale hog fuel boilers and of small residential heating units. In some respects the program elements have evolved in three directions: 1. Technical service in support of FIRE (an incentive program to increase biomass utilization for energy by industry and institutions) and demonstration activities (mainly combustion and gasification). 2. Transfer of technology at the demonstration phase as with the Lamb Cargate Wet Cell/Lime Kiln at Port Alberni or, as in the case of gasification, a fullscale demonstration under construction in Quebec referred to as BIOSYN. 3. Return to fundamental studies as exemplified by the direct liquefaction work.

ENERGY RELATED ACTIVITIES OF THE CANADIAN BIOMASS RESEARCH PROGRAM 83

10 PRETREATMENT This area covers research from physical size reduction to lignocellulosic fractionation prior to cellulose hydrolysis. In terms of technology development, it is a curious hybrid of commercial processes, such as the Bioshell process, demonstration activity such as the Iotech/Monenco 1 ton/day steam explosion process for a wood-to-ethanol plant, Weston’s Biohol extrusion process, and R&D such as the University of Sherbrooke thermomechanical procedure for lignocellulosic fractionation. Increased effort in fractionation of lignocellulosics into lignin, cellulose, and hemicellulose is justified in terms of potential value added to the separated fractions. 11 BIOTECHNOLOGY AND BIOGAS These two areas have shown consistent growth within the funding envelope for Bioenergy R&D. The scope of effort ranges from genetic engineering of yeasts to enable them to simultaneously saccharify cellulose and utilize the sugars, to the operation and monitoring of 400-m3 fixed-film anaerobic digesters. The anaerobic digestion program is an example of the time scale that is required to develop a laboratory system for a commercially viable process. It is also a useful model for future bioenergy development since it illustrates the economic environment in which a bioenergy process is likely to be viable. Figure 7 shows the pattern of program support since 1976. Prior to 1976, NRC had maintained a program looking at the treatment of food processing wastes. This served as the basis for the development of the Down Flow Stationary Fixed Film (DSFF) concept. Up to 1980, the majority of the work was in the laboratory, though a number of early demonstration and pilot projects were undertaken by Agriculture Canada. The early demonstrations, with the exception of the Roslyn Park Farm, were technical or economic failures (or both) . The early failures of bulk anaerobic digesters brought into focus the developments called for in creating a viable technology. NRC, Agriculture Canada, and the private sector have worked together to bring the DSFF and other advanced concepts to full scale. From one successful operating STR (Roslyn Park) in 1980 there are now 11 advanced systems under construction or operation. These use both animal manures and industrial wastes such as cheese whey. Economically, the animal systems are successful if both energy is produced and protein is recovered. The increased emphasis on energy/protein recovery and environmental improvement makes such advanced digesters economic for farms with 100–150 animals. The NRC DSFF technology has been scaled up from 50 cm3 working volume to 400 m3, while a mobile trailer with a 1-m3 unit is being used to test the different industrial wastes in eastern Canada. The current demonstration units are

84 ENERGY APPLICATIONS OF BIOMASS

likely to be evaluated before major new demonstrations are undertaken. The funding by sponsors in the Biogas program is also a measure of the maturing of a technology as it is transferred from the laboratory to the private sector. During the scale-up and demonstration of the DSFF reactor concept, laboratory work at NRC has continued on developing the next generation of advanced systems. A hybrid sludge blanket and filter bed reactor have given the highest rates of methane production achieved to date at NRC, equivalent to 10 m3 of methane per m3 of reactor volume per day, a substantial improvement over the 1 m3 that was common in the early 1970s. 12 THE FUTURE The major Canadian biomass resource is the lignocellulosic resource, forest biomass, while agricultural plant stalk materials such as straw and stover make up the rest. The growth of the bioenergy program during 1976–84 has been paralleled by the upswing of interest in biotechnology. The bioenergy R&D program has in a sense provided what could ultimately be the basis of a new resource-based industry providing fuel, fibre, food, and chemicals. The resource assessment has established a raw material base in excess of 50 million ton per hectare of forest biomass available at a cost of $45/ton delivered to a processing plant. A wide range of options are available for this wood biomass. Clearly, in site-specific circumstances saccharification using dilute acids or liquefaction and pyrolysis could be economical. Such circumstances will almost certainly only occur where extremely low-cost process residues are available. The required value added to justify large-scale use of a $45/ton resource will have to come from fractionations such as organosolv and aqueous steam extraction followed by value maximization of the cellulose, hemicellulose, and lignin streams. The new biotechnologies will play their role through a process that will optimally utilize each of these streams. Biotechnology is also likely to play a role in rapidly developing new varieties of biomass species engineered or bred for specific qualities or even chemical composition. Today’s forestry and agriculture are optimized for the production of long fibres for pulp and specific strength and density characteristics for solid products and foodstuffs. New conversion processes could call for more biomass production per unit area and for modified properties such as in the ratios of hemicellulose to cellulose and lignins as well as their composition. The early work in cloning and macropropagation of Populus and Salix is an encouraging example of the significant productivity gains that could be achieved not only for hardwoods but also for softwoods with the application of concerted breeding programs. For the future, the potential is even greater if we can bring to bear the full array of plant tissue culture biotechnology on biomass productivity.

ENERGY RELATED ACTIVITIES OF THE CANADIAN BIOMASS RESEARCH PROGRAM 85

Fig. 1. Forest biomass souree and distribution as a percentage of the total available in 1990 for energy and chemieals

REFERENCES 1. 2.

3. 4.

5. 6. 7. 8.

9.

Devitt, W.J.B. ‘Investment constraints in Canada’s forests: transition to management’, B.Sadler, ed., The University of Calgary Press, 41–50, 1983. Barrett, D. and Kellog, R.M. ‘Strength and stiffness of second growth Douglas fir dimension lumber’, prepared for the Science Council of British Columbia, March 1984. McKeand, S.E., and Weir, R.J. ‘Tissue culture and forest productivity’, J. For., vol. 82 (4), 212–218, 1984. Smith, D.R. ‘Micropropagation of forest trees: Pinus radiata in New Zealand as a model system’, in Micropropagation of Fruit and Forest Trees, U.P.S.Bajaj, ed. In press, Springer Verlag, Berlin, 1984. Farnum, P., Timmins, R. and Kulp, J.L. ‘Biotechnology of forest yield’, Science, vol. 219, (4585), 694–702, 1983. Libby, W.J. and Rauter, R.M. ‘Advantages of clonal forestry’, For. Chron., vol. 60, 145–149, 1984. Anonymous. ‘Canada’s threatened forests: a statement by the Science Council of Canada’, Ottawa, March 1983. Armson, K.A. ‘Canadian Forestry Association brief to the Royal Commission on the Economic and Development Prospects for Canada’, Thunder Bay, Ontario, October 19, 1983. Ellingsen, J. ‘Integrated pulpwood and biomass harvesting’, in Fifth Canadian Bioenergy R&D Seminar, S.Hasnain., ed., Elsevier Applied Science Publishers, London, 1984.

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Fig. 3. Percentage of year total expenditures 1977–1983 (in dollars of the year)

Fig. 2. Supply/price curve for forest biomass availability in 1990

ENERGY RELATED ACTIVITIES OF THE CANADIAN BIOMASS RESEARCH PROGRAM 87

Fig. 5. Program evolution by sponsor (in dollars of the year)

Fig. 4. Bioenergy program development (in dollars of the year)

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Fig. 7. Biogas R&D expenditures (in dollars of the year)

Fig. 6. Program evolution by area

THE BRAZILIAN ALCOHOL PROGRAM L.C.MONACO* *Secretariat of Industrial Technology, M.I.C., Brasilia, Brazil

The National Alcohol Program (PROALCOOL) is an integral part of the Brazilian efforts to substitute biomass energy for nonrenewable energy sources. During the 1983–84 campaign, 7.6 million m3 of alcohol will be produced; 0.4 million m3 will be used in the chemical industry, 3.6 million m3 as fuel for allethanol cars, and 2.1 million m3 as octane booster for gasoline for more than 8 million vehicles. The PROALCOOL goal for 1986–87 is to produce 10.7 million m3, aiming at the substitution of 170,000 barrels of petroleum per day, which represent about 15% of the forecasted oil consumption in that year. Recently this goal was raised to 14.3 million m3. Launched in 1975, PROALCOOL is the result of the adoption of an appropriate strategy to reduce imported petroleum using the prevailing conditions at that time. Petroleum products accounted for about 42% of the energy consumption, of which more than 80% was imported (Fig. 1). The sharp increase in oil prices had a strong effect on the balance of payments. Although a significant reduction has been observed, it should be remembered that, in 1980, it stood at more than $11 billion (U.S.), or about 50% of the export earnings (Fig. 2). Because of such dependence, the Brazilian government established a strategy to (1) increase the domestic petroleum production (Fig. 3); (2) promote energy conservation; (3) stimulate the use of new and renewable sources of energy, and (4) modify the refining profile in order to adjust the products to the existing alternatives (Fig. 4). It should be stressed that the main energy restriction in Brazil is related to liquid fuels, since more than 70% of the transportation is by vehicles (Fig. 5). Local conditions led to the definition of ethanol as an alternative energy to replace gasoline within the comprehensive energy program: (1) the extensive sugar cane plantations, which were stimulated by the high sugar prices in the international market, and (2) previous experience in using alcohol as fuel. In 1975, the Secretariat of Industrial Technology funded several research projects on the development of all-ethanol Otto cycle engines, as well as the evaluation of the best percentage of alcohol to be used as gasoline extender. Initially the alcohol production was planned to be used in blends of 20% of anhydrous ethanol to gasoline. This target was achieved in 1979, when a new

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structure of the program and new targets were approved, extending the use of neat alcohol in cars. 1 ORGANIZATION It was established at the beginning that alcohol production would be undertaken by the private sector. The government role has been to promote PROALCOOL through long-term loans, to coordinate its implementation to achieve proper production in the areas of high demand, to assure equal opportunities for ample participation of the society to define regulatory policies, to enforce adequate land use, to prevent environmental impacts by the effluents, and to guarantee social benefits for the rural areas. The policy-making body is the Alcohol National Council (CNAL), which is made up of the Minister of Industry and Commerce (Chairman), the SecretariesGeneral of the Ministries of Mines and Energy, Agriculture, Interior, Labor, Planning, and Finance, the Director for Technology of the Joint Staff of the Armed Forces, and representatives of the private sector. The Executive Secretariat of the National Alcohol Commission (CENAL) implements the policies defined by CNAL. CENAL is chaired by the SecretaryGeneral of the Ministry of Industry and Commerce, and composed of the President of the National Petroleum Council, the President of the Alcohol and Sugar Institute, the Executive Secretary of the Industrial Development Council, and the Secretary for Industrial Technology. 2 OPERATIONAL ASPECTS Great effort was made to avoid establishing new institutions. Existing government agencies performed the appraisal and follow-up of the projects. To shorten the time between the application and the contract of the loan, the project proposal submitted to CENAL is sent for technical and economic appraisal simultaneously. The technical aspects of alcohol-producing units based on sugar cane are evaluated by the Sugar and Alcohol Institute (IAA). For other raw materials, the technical evaluation is carried out by the Secretariat of Industrial Technology. The economic analysis is conducted by the financing agencies. Official investment and commercial banks or private investment institutions approved by the Central Bank of Brazil participate in the lending operation. The financing conditions stimulate the participation of the private sector in PROALCOOL and prevent undesirable impacts on land use. Up to December 1980, any sugar-cane-based distilleries would receive up to 80% of the total industrial investment, and the units using other raw materials or cooperative or farm association would be entitled to 90% of the total investment. Recently, these values were reduced to 70% and 80%, respectively. The loans are

THE BRAZILIAN ALCOHOL PROGRAM 91

repayable in 12 years with a 3-year grace period. The interest rate was a fraction corresponding to 10% of the government bonds indexed to the inflation rate and a fixed interest rate, which varies from 3% to 5% depending both on the new raw materials that the government decided to promote and on regional necessities. For instance, in the depressed northeastern region, the interest rate is 3%. Recently, however, these requisites were altered, particularly regarding indexing, which has reached 85% plus interest. The financing of the agricultural sector presently uses the same rate applied to other major crops. 3 PRODUCTION CAPACITY OF PROALCOOL The operational system described above has contributed significantly to reaching the goals established by the Brazilian government. By last October, 86 new projects had been approved, corresponding to a producing capacity of 10.8 million m3 which is slightly above the target established in 1979. Additional projects are being evaluated in order to meet the recently established target of 14. 3 million m3 . Individual distillery capacity ranges from 30,000 to 1,000,000 L of alcohol per day; however, most units have a capacity of about 120,000 L/day. Small units with a capacity of 1000 to 5000 L/day are under evaluation. 4 STORAGE AND COMMERCIALIZATION OF ETHANOL Since liquid fuel production is under government administration, the alcohol production program was established according to regional demand. The National Petroleum Council defines the program for alcohol delivery and pays for the products according to an ex-factory price. The retail price includes additional costs for transportation and commercial return. The storage facilities are concentrated mainly in the producing units. The present commercialization procedures establish that 1/12 of the total production has to be removed monthly from the distilleries. For autonomous distilleries, 1/9 of the total production is delivered monthly to the fuel distributors. In addition, regional storage facilities are controlled by oil companies, which subsequently distribute the product. Anhydrous alcohol is received by Petrobras, which is the only company responsible for its blending with gasoline. A well-planned distribution network minimizes transportation costs. 5 ALCOHOL QUALITY The conditions in which alcohol is produced vary from region to region and among distilleries. Consequently adequate quality control is required to

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guarantee proper running of engines as well as to reduce corrosion problems. According to Brazilian norms, carburant hydrated alcohol must have 96°GL, whereas anhydrous alcohol must have 99.4ºGL. To facilitate quality control by the consumer, the use of densimeters on alcohol pumps is required. 6 ALL-ETHANOL CARS To stimulate the demand for carburant alcohol, several steps were taken to increase confidence in all-ethanol cars. A countrywide network of technological centers was established to provide technical assistance for engine adaptations in new cars as well as for conversion of existing gasoline-powered cars to hydrated alcohol. Minor cylinder head modifications, a fuel preheating-system, cold-start facilities, calibration of the carburetor, and replacement of the components in the fuel system are required. The system adopted proved to be efficient in the transfer of technology to small entrepreneurs who are converting motors. More than 500 small enterprises have been approved, with a capacity to convert about 20,000 vehicles per month. The protocols signed with car manufacturers and industrial associations established the production of 250,000, 300,000, and 350,000 new allethanol cars and the conversion of 80,000, 90,000, and 100,000 gasolinepowered cars from 1980 to 1982. The success of the new car can be evaluated by more than 1,000, 000 new cars released. Actual demand for conversions was less than expected. Favourable consumer reaction to the all-ethanol cars was also obtained after the establishment of special incentives. Besides the lower price of the fuel (alcohol cannot cost more than 65% of the gasoline price), the annual registration fee was reduced by 50%, and installment payments for alcohol cars were extended to 24 months instead of the usual 12 months for gasoline cars. More than 85% of the cars produced in Brazil are now alcohol powered. The car industry had to invest large sums to guarantee the quality and performance of the alcohol car. A protocol was signed with the car industry to assure progressive reduction of the alcohol consumption. 7 SOCIAL ASPECTS PROALCOOL was established not only to reduce the external petroleum dependence and to improve the balance of payments but also to transfer other benefits to society. For this reason, efforts are being made to assure that the program will not adversely affect living conditions or lead to displacement of food-producing areas, but will offer new job opportunities and improve income distribution. Taking into account the number of distilleries so far installed, about one new direct job is created for every 20,000 L of alcohol produced. Besides direct

THE BRAZILIAN ALCOHOL PROGRAM 93

employment in the industrial sector, demand for manpower is growing in the agricultural sector. More than 300,000 new jobs have already been created by PROALCOOL. Much attention has been given to the environmental impact of distillery effluents (vinasse), mainly in water basins. The stillage has a high BOD and COD; however, due to its high mineral content, particularly potassium, it has been shown to be an excellent fertilizer. It may also be used as feeding stock, converted into methane, or employed as substrate for single-cell protein production. The distribution of the stillage on the soil as fertilizer has proved to be at present the best economical solution. Application of 50–100 m3 on ratoon crops led to a 50% increase without any additional fertilizer requirement. 8 PERSPECTIVES OF PROALCOOL The evolution of PROALCOOL has proved its potential not only to produce liquid fuel but also as a driving force to foster technological development in the production and use of alcohol as carburant or feedstock for the chemical industry. The Brazilian government in 1979 created an alcohol fund, which is used to support research and development in this area. This program, which is under responsibility of the Secretariat of Industrial Technology, has been receiving funds corresponding to 3% of the total annual investment of the PROALCOOL. The actual demand for research and development was established at a number of meetings held with equipment suppliers, engineering firms, sugar cane and alcohol producers, scientists, and government officials. The priorities thus identified are helping to strengthen existing R&D groups and to stimulate new scientific personnel involvement in basic and applied research. Great emphasis on biomass fuels is being given to improving sugar cane and cassava as well as other raw materials suitable to be converted into ethanol. Improvements in the process and equipments used in the conversion of sugar, starch, and cellulose into ethanol are also being supported. Particular attention is being paid to the development of more efficient engines and to the study of the emission pattern in all-ethanol cars and in vehicles powered with gasoline-alcohol blends. The proper utilization for the process residues is being intensively investigated. These efforts are necessary to further expand the alcohol production and to improve its competitiveness with other liquid fuels. There are enough natural resources for increasing the alcohol production without actually affecting the total food production. The use of alcohol as a substitute for gasoline brought as a consequence the need to replace the corresponding diesel and fuel oil fractions. It should be pointed out that because of alcohol production, the refining cracking pattern has been altered to increase the diesel production. The production of medium distillates was raised by more than 20%. As a result, replacing petroleum distillates for biomass products has also led the Brazilian government to prepare

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two new programs: vegetable oils to extend diesel oil and forest energy products to reduce the fuel oil demand. In conclusion, the success of the alcohol program has to be viewed within the framework’ of the Brazilian social and economical conditions. It may, however, be possible that our experience in the biomass utilization might serve the planning and launching of other alternative energy programs, particularly in developing countries, notwithstanding the site specificity of any energy from biooass project.

Fig. 1. Brazil—Movement of the overall consumption of primary energy sources (1970– 1980)

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Fig. 2. Petroleum and Brazilian debt (1981 dollars)

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Fig. 3. Brazilian oil supply (1973–1981)

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Fig. 4. Guidelines of the Brazilian energy policy

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Fig. 5. Development of fuel consumption In transportation

PROGRESS IN THE CALIFORNIA ENERGY COMMISSION BIOMASS DEMONSTRATION PROGRAM RAY TUVELL* *Biomass/Cogeneration Office, California Energy Commission

SYNOPSIS This paper presents the status and progress of the Biomass Demonstration Program created by the State Agricultural and Forestry Residue Utilization Act (SAFRUA) of 1979. The paper highlights the 17 projects that have received SAFRUA funding to date and discusses various aspects of the program, including economics, financing, risk sharing with industry conversion technologies, and resource potential. The paper also explains how to participate in the program. To accelerate the development of biomass resources, the state legislature established the Biomass Demonstration Program”…to promote the immediate development and implementation of residue conversion as an energy generating technology, and to provide funds to encourage the development and demonstration of residue conversion.” The state has recognized that converting biomass residues to energy is instrumental in reducing industry’s dependence on costly, nonrenewable resources. Biomass is a low-cost energy source compared to natural gas and oil. For the industrial sector, abundant supplies of biomass fuels were available at costs ranging from $0 to $2.50 per million Btu (1983 dollars) while costs of distillate fuel oil and natural gas prices were $5.80 and $5.75 per million Btu, respectively (1983 dollars). Biomass energy projects generate jobs and revenues and have created a fledgling industry in California. The $8.8 million provided by the SAFRUA account is supported by private industry commitments of $45.6 million. The 17 SAFRUA projects are estimated to generate $54 million in capital invest ment, $244 million in gross sales, $73 million in gross income, and over 3600 jobs. SAFRUA projects also enable seasonal operations in the agriculture and forest industries to extend productivity, produce fuel, and preserve jobs.

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1 DEMONSTRATION PROGRAM: PROJECT STATUS The California Energy Commission (CEC) originally focused on funding projects that would demonstrate collection equipment and three major energy conversion technologies: direct combustion, methane fermentation, and gasification. Emphasis was placed on projects that would be technically successful and easily duplicated at other sites. As the program progressed, projects that proposed designing and building new prototype biomass equipment were included. Of the 17 projects in the SAFRUA program (see Table 1), three are completed and have repaid $270,000 in SAFRUA loans. Five projects are in the final shakedown stage and operating successfully. Four projects are experiencing shakedown problems, and special consultants have been brought in through the CEC’s technical support contract to identify and resolve the problems. Five projects are in the engineering, design, or construction phase. As a result of the state’s effort over the past four years, a biomass energy industry is slowly emerging in California. In addition to the 17 SAFRUA projects, many other biomass systems are under construction or in operation throughout the state. But without further demonstration of some technologies, many privately funded projects will not be constructed. To ensure the growth of a healthy biomass industry in California, the state must continue to assist in the demonstration of new and risky biomass energy projects. 2 BIOMASS ENERGY DEVELOPMENT IN CALIFORNIA Many of the 17 SAFRUA projects are the first in California to convert agricultural and forestry residues to energy. Today California leads the nation in the development of biomass energy as a result of technical and economic data gained from the demonstration of these projects. Collecting, processing, and converting biomass residues to energy will keep dollars in the state’s economy, creating jobs and revenues. Figure 1 shows the typical annual generation and current energy use of biomass residues in California. There are major costs, uncertainties, and unique technical problems associated with converting biomass residues to energy. Orchard and vineyard prunings were the first agricultural crop residues to be used for fuel due to the high costs of current disposal practices. California’s agricultural crop residues with the greatest energy potential—cotton and corn stalks and rice, wheat, and barley straws— have not been demonstrated due to collection and energy conversion difficulties. Some agricultural industry residues, such as shells and fruit pits, are currently being used as fuel in biomass energy systems throughout California. Others, such as rice hulls and gin trash, have substantial problems that must be overcome. Each year in California, over 2 million tons of animal manures are collectible for

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Table 1: SAFRUA project summary

energy conversion. However, each dairy or feedlot requires a specially designed system that considers animal type, operation size, manure-handling system, and climate. Further work is required to develop and commercialize off-the-shelf designs and small-scale equipment. The forest industry has been converting sawmill wastes to energy for over 40 years. These residues are generated and used on site, making their use as fuel highly cost effective. These wastes have high energy potential and few combustion difficulties. The use of forest residues and chaparral for energy has only recently received attention. Collection on flat terrain appears to be feasible and is being tested. However, equipment must be developed to gather forest residues from steep slopes to achieve maximum use. Since SAFRUA was established in 1980, many new biomass facilities have been built, the majority of which have been stimulated by the success of the SAFRUA projects (see Table 2). With continued use of the state’s abundant residues, California will continue to reduce its reliance on oil and natural gas and sustain the growth of a new biomass industry.

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Table 2: Number of constructed facilities by type as of December 1983 Technology Agricultura Agricultur Manure Forestry l Crop al Industry Residual

Forestry Industry

Direct 4 (2) 10* (5) 1 (1) 0 97* (3) Combustio n Methane N/A 1 5 (3) N/A N/A Fermentati on Gasificatio 0 1 N/A 0 0 n Collection 10 (5) 0 N/A 0 N/A ** Note: N/A Indicates “not applicable.” * Indicates number of boilers. ** Includes combustion projects using agricultural crop residues. ( ) Number of projects in SAFRUA program. Source: CEC staff calculations

Chaparral and Urban Residues 2

N/A

1 4

3 ECONOMIC BENEFITS California’s agriculture and forest industries offer the greatest opportunities for biomass energy investments. Energy costs and availability are dominant factors affecting a firm’s ability to produce products competitively. As electricity, oil, and natural gas prices increase, finding new methods for controlling energy costs and selecting more reliable, cost-effective energy sources become increasingly important. Several firms have found it economical to modify existing boilers or install new boilers to use biomass as a primary energy source. A cost comparison of various biomass and conventional fuels is illustrated in Fig. 2. Residues such as manures can be generated and used on-site at little or no cost. The cost of energy from biomass is influenced by the type of conversion technology, feedstock cost, project location, and ownership structure. The economic benefits are twofold in projects where biomass that was previously hauled away at a cost for transportation and dumping is now being used to generate energy and revenues. The economics of biomass energy projects are improved considerably when electricity is generated through cogeneration because overall system efficiency is greater when compared to generating electricity and process heat separately. Firms can either use the electricity in-house, thereby achieving significant cost savings by deferring the cost of purchasing electricity from the local utility, or sell all or a portion of the generated power to a utility at published “avoided cost” prices.

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The industrial sector can produce electricity from biomass at a lower cost than purchasing electricity from the utility. Figure 3 shows the projected prices of electricity and natural gas to the industrial users and the approximate cost of producing electricity in a biomass-fueled power plant. As the cost of purchased electricity increases, more industrial energy users will develop biomass energy projects. Biomass energy facilities could also locate in industrial parks to meet several end-users’ steam and electricity demands. A mutually beneficial arrangement allowing the energy producer to receive a reasonable payment for electricity and still charge the industrial user less than the cost of electricity purchased from the utility has the added benefits of increasing energy selfsufficiency and stimulating the local economy through economic growth and jobs. Figure 4 displays the economic benefits resulting from the SAFRUA program’s $55 million investment in biomass energy projects. 4 A STEP TOWARD SELF-SUFFICIENCY Heavily dependent on conventional energy sources, forest and agricultural operations can be jeopardized by disruptions in energy supplies. This risk, coupled with rising electricity costs, makes using biomass resources for energy conversion an attractive alternative in California. California produces 50 million dry tons of biomass residues each year. However, only 17 million dry tons are available for energy purposes, and only 10% of this amount is being used. While the energy equivalent of nearly 17 million barrels of oil is available annually from biomass, the forest and agricultural industries of California used a total of 53 million barrels of oil equivalent in 1980. These industries generate a variety of biomass residues annually, including straws, stalks, and prunings; fruit pits, nut shells and hulls, gin trash, and other processing wastes; animal manures; thinnings, slash, and culled logs; edgings, shavings, bark, trim, and sawdust; and chapparal and other woody residues. Industry residues are more economical to convert to energy than crop residues or forest slash because they are centrally located. The agricultural and forest industries will benefit greatly from biomass energy development because of the increasing uncertainty of conventional energy costs and supplies. These industries are also burdened with high residue disposal costs and environmental disposal problems. Figure 5 illustrates that both the agriculture and forest industries can be energy self-sufficient. The 17 SAFRUA projects displace many forms of conventional energy used by the forest and agricultural industries. Five of the projects cogenerate; five produce only electricity; three produce only process heat or steam; and the remaining four involve fuel collection or fuel cleaning and handling. The annual energy that the SAFRUA projects produce is equivalent to 622,000 barrels of crude oil—enough energy for 60,000 homes. All five cogeneration projects—Farmers Cooperative Gin, Superior Farming Company, Big Valley

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Lumber Company, Jaoudi Industrial and Trading Corporation, and Koppers Company, Inc.—can be energy self-sufficient (see Fig. 6). 5 ENVIRONMENTAL BENEFITS Using biomass residues as fuel can solve many current disposal problems. The nine SAFRUA projects that use straws and agricultural prunings are reducing air pollution and wasted energy. These residues, previously burned in the fields and often ignited using gasoline and propane, are now burned under controlled conditions in bioroass conversion facilities that generate energy and are in compliance with California’s stringent air pollution regulations. The removal of vineyard prunings for fuel minimizes plant disease caused by degrading prunings. The use of forest residues reduces fire hazards and disease problems. Each year the California Department of Forestry, the U.S. Forest Service, and private landowners pile brush and forest slash and burn it to reduce the risk of forest fires that destroy valuable timberland. Both government and private industry support projects that will remove these residues and convert them to useful energy. Five projects convert animal manures to energy and in the process reduce fly and odor problems. Improper disposal of manure on site can contaminate underground water supplies. Using manure for energy production offers an environmentally sound alternative to manure disposal while at the same time generates energy as a revenue source for the farmer. The process by-products are used for animal bedding, animal refeed, fertilizer, and soil amendment. Table 3 summarizes reductions in emissions and landfill attributed to existing biomass projects in California. Table 3: Environmental benefits to California (reductions in tons/year) pollutant

CEC projects

other California biomass projects

Air pollution TSP RHC NOx CO Solid waste

1,500 1,700 550 18,000 37,400

14 ,000 16,000 5,900 183,000 321,000

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6 RISK SHARING WITH INDUSTRY The advantages of biomass energy are weighed against the costs and availability of conventional fuels, the competing uses of biomass resources, and the capital investment for conversion facilities. Because biomass energy is relatively new, potential users and investors are uncertain of the advantages and risks involved with constructing and operating a biomass facility. To accelerate the near-term applications of energy-from-residue technologies, the state legislature established the SAFRUA program to pro vide technical support through staff expertise and outside consultants to resolve problems that may occur. The industry’s commitment of over five dollars to every state dollar invested demonstrates the success of the program. The $8.8 million encumbered by the SAFRUA program has been matched by $45.6 million in industry investments. Not only is the money providing short-term financing for projects that will result in net benefits to investors of almost $180 million during the estimated 20-year life of the projects, but most of the $8.8 million will return to the SAFRUA program for reinvestment in additional biomass projects. Money is not the only support that the SAFRUA program provides. The CEC offers technical assistance through staff engineering, troubleshooting, and financial and marketing expertise. Over the longer term, SAFRUA’s success will be measured by the extent of further applications of biomass energy technologies by commercial enterprises—using their own capital. 7 TECHNOLOGY TRANSFER The state’s ability to develop a biomass energy industry depends on more than providing money for demonstrations, and developing a successful biomass project takes more than just seeing a similar project in operation. Since the state funds only a few projects compared to the total potential for biomass energy applications in California, the CEC must market successful demonstrations to achieve widespread technology development. Marketing is the state’s way of communicating with the private sector, which finances and constructs “spinoff” biomass energy projects. These spinoff projects represent the force behind the creation and sustenance of a biomass energy industry in California. The CEC markets biomass energy in several ways. For instance, SAFRUA demonstrations are developed into showcases that encourage others to invest in similar projects. Staff members prepare brochures on the technical, economic, and environmental aspects of each project. Workshops and press conferences, held near the completion of a project’s shakedown, enable potential users, manufacturers, consultants, utility representatives, government officials,

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legislators, the media, and others to discuss what has been learned and how future projects can be improved. The CEC also sponsors innovative equipment demonstrations. In 1982 and 1983 collection equipment demonstrations for forest slash, precommercial thinnings, and chaparral attracted over 500 people. The CEC prepares reports, handbooks, and other written information on a variety of subjects. The CEC prepared an investment prospectus, which was sent to banks, lending institutions, and potential investors outlining the financing options, tax incentives, and the overall economics of biomass energy projects. Project developers need information on biomass fuel suppliers and users, financing, feasibility studies, economic and technical data, and resource availability. Advertising the success of SAFRUA-funded demonstration projects will stimulate private industry investment in other biomass energy projects. 8 BIOMASS ENERGY TECHNOLOGY The three major biomass energy conversion technologies are direct combustion, methane fermentation, and gasification. Technologies to collect and process biomass residues are also important, since most of California’s biomass is in fields or forests. Direct combustion converts biomass—composed primarily of carbon and hydrogen—to useful heat. Examples of direct combustors include incinerators, kilns, and fluidized-bed or suspension-fired burners. Direct combustion of woody residues is well demonstrated. Agricultural residues that contain high concentrations of ash, nitrogen, and moisture, such as rice straw, make combustion difficult and have only recently received developmental and commercialization attention. In methane fermentation, organic matter in the absence of oxygen is biologically broken down into organic acids and carbon dioxide, which are then bacterially converted to biogas—primarily methane and carbon dioxide. The biogas is burned in systems that typically use natural gas to produce space heat, process steam, or electricity. Methane fermentation is a mature technology in municipal wastewater treatment but is not fully developed using biomass as a feedstock. Like direct combustion systems, gasification systems involve combustion of biomass, but in an oxygen-deficient environment. They are designed to produce a combustible gas rather than to release heat immediately. The gasification process produces a “product gas” that can be converted into process heat, steam, electricity, or liquid fuels. Gasification has potential for small-scale electric generating systems less than 1 megawatt (MW). In California, gasification systems that will be used with boilers are currently in shakedown operation. Gasification systems to be used with engines have not yet been demonstrated as commercially feasible. Because gasification is cost-effective for special

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applications such as irrigation pumps and can utilize large amounts of residues, the CEC has emphasized gasification in its current project solicitation. Technologies to collect and process forest slash, agricultural crop residues, and orchard prunings have not been developed extensively. This, coupled with the dispersion of these residues, is an impediment to more widespread use of biomass for energy. Funding collection systems will help identify and resolve uncertainties such as hardware, operational management, and economics. In the future the CEC also will focus on demonstrating projects that integrate biomass collection with energy conversion technologies. 9 HOW THE BIOMASS DEMONSTRATION PROGRAM WORKS The CEC seeks biomass demonstration project proponents through the Request for Proposal (RFP) process, including bidders’ conference and public workshops. Before selecting a proposal, the CEC analyzes project-specific information on the biomass resource base, system design and engineering, environmental impacts, and technical and economic feasibility. The CEC staff works with the project proponent to obtain permits and financing and resolve other barriers as they occur. During the construction, shakedown, and operation phases of the projects, the SAFRUA program is supported by technical experts who are called upon when problems occur. Funding from the SAFRUA account is accomplished by “purchase/buyback” agreements between the state and the project proponents. The state provides up to 50% of project funding for the purchase of biomass energy equipment. Once a project meets performance criteria established during contract negotiations (see Table 4), the project proponent is obligated to “buy back” the equipment within 90 days. If a project does not meet the performance criteria, the state may secure the equipment for resale; otherwise a reduced repayment, in proportion to the degree to which the project meets specifications, can be negotiated. Once repayment is accomplished, the monies are returned to the SAFRUA account to be used for other projects. SAFRUA provides the project proponent with short-term capital corresponding to the cash flow requirements of a project during its construction and shakedown phases. The funding also provides a demonstrated system for a financial institution to evaluate prior to financing its further commercialization. TABLE 4 CRITERIA FOR SELECTING SAFRUA PROJECTS IMPACT ON TECHNOLOGY COMMERCIALIZATION •

Converting underutilized residues with the greatest energy potential.

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IMPACT ON TECHNOLOGY COMMERCIALIZATION •

Demonstrating technologies with the potential for widespread adoption throughout California. • Promoting the use of cogeneration or other methods to increase end-use energy efficiency. • Reducing environmental impacts from current residue disposal. • Near-term technical feasibility. MERITS • Substitution for oil and natural gas consumption (cogeneration preferred). • System predictability with regard to technical performance, economics, and environmental impacts. • Estimated “investment payback period” and “return on investment.” • Length of time until state funds will be repaid. Qualifications of project personnel. • Financial strength and extent of financial participation of project applicant. • Degree of innovation. • Ability to obtain a secure fuel supply.

Fig. 2. Forecast average energy prices in California for 1985

Fig. 1. Residues generated, available, and used for energy (million dry tons)

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Fig. 3. Energy cost comparison, biomass vs. conventional

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Fig. 4. Economic impacts and benefits of Safrua program (Investment of $55 million)

Fig. 5. Agriculture and forest Industry

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Fig. 6. Electricity balance for three Safrua cogeneration projects

NEW YORK STATE BIOMASS ENERGY RESEARCH J.B.HOLLOMON,* *New York State Energy R&D Authority, Albany, New York

The biomass program of the New York State Energy Research and Development Authority (NYSERDA) encompasses a wide range of topics in resource development, direct conversion, production of fuels and chemicals, and resource recovery. In the following paper, I will outline the underlying philosophy and rationale that tie together what would seem to be a disparate collection of activities, and then I will report on some recent progress in five major program elements. 1 PHILOSOPHY AND RATIONALE Biomass research and development sponsored by New York State fills a gap left between the activities of the U.S. Department of Energy (DOE) and those of private institutions. This work bridges Congressman Fuqua’s river between the federal promotion of long-term, high-risk technologies for the benefit of the nation as a whole and the pursuit by private investors of shorter-term, limitedrisk opportunities that promise a high return. NYSERDA accepts greater risks at earlier stages of technology development than private corporations can on their own, but we are not restricted to high-risk technologies that must be justified in terms of potentially very large contributions to national energy supplies. States are also in a position to be more sensitive to local needs and opportunities than a federal agency is likely to be; they are also motivated by a broader range of public interests than business profits alone. From a national perspective, our program represents a medium for technology transfer, while at a local level, potential adopters of new energy technology view us as a resource for innovation. Our role is some what analogous to that of industry consortia like the Electric Power and Gas Research Institutes, but it is defined in terms of geography rather than industry sector. Some of the apparent technical diversity of our program is the result of following a “market pull” as distinct from a “technology push” paradigm of R&D management. While federal programs sometimes begin by developing a technology that appears promising to the research community and then attempt to commercialize it afterward, our approach seeks first to identify a need and then

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to support the innovation required to meet it. For this reason, the unifying concepts in our program revolve around classes of users and applications rather than categories of technologies to be applied. Based on NYSERDA’s energy experience, states are uniquely suited to facilitate traffic in technology between the public and private sectors. Aware of local needs, state officials can better pursue solutions to identified problems in contrast to seeking applications for identified technologies. Also, smaller, less minutely compartmentalized agencies are more capable of devising approaches that would involve many separate jurisdictions and missions at the federal level. Unfortunately most states, especially smaller ones, are without the means to support individual R&D programs. To overcome this limitation, NYSERDA has attempted to enlist other states in the Northeast to pool resources in a joint biomass endeavor based on several common interests: heavy oil dependence, similar forest and agricultural resource characteristics, like climatic conditions, interdependent economies, incidences of rural poverty throughout the region, and a shared natural environment and common coastline. Benefits would include elimination of gaps and duplications through joint planning and coordination, improved capacity to sponsor worthwhile projects too large for individual states to support separately, reduction of technical risk through diversification, and more efficient utilization of the specialized capabilities of research institutions within the region. 2 PROGRAM OVERVIEW The NYSERDA biomass and waste programs are composed of five elements, funded at annual levels of approximately $0.5 million each. This amount is leveraged two to three times through cofunding arrangements with other institutions. The elements, organized by market application, are resource development, direct conversion, production of fuels and chemicals, resource recovery from municipal solid waste, and energy from sewage treatment processes. Research in resource development is designed to increase the availability of suitable biomass raw materials over the long term and to minimize the environmental and economic costs of exploiting them as an energy source. Direct conversion technologies permit generation of useful heat and mechanical power, primarily from wood in small- to medium-sized installations located where the biomass grows. Production of high-valued fuels and chemicals provides transportable and marketable substitutes for products now refined from petroleum and natural gas. Finally, the municipal solid waste and sewage treatment process R&D is designed to reduce the cost of environmentally acceptable disposal through generation of energy as a revenue-producing byproduct. The following discussion details progress made within the past year and planned future actions in each of these areas.

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2.1 Resource Development We agree that surplus wood is sufficient, at least in New York and throughout most of the Northeast, to support foreseeable biomass energy applications for the next several years. We are also concerned that the resource may eventually become limited either through expansion of the traditional forest products industry or through new uses of trees. For this reason, our resource development research addresses potentially large sources of supply for the next decade and beyond. Recent accomplishments include the expansion of the State University of New York College of Environmental Science and Forestry’s research into the suitability of different hybrid poplar varieties for intensive energy farming under soil, climate, and pest conditions prevalent in New York. The data and expertise resulting from NYSERDA-supported work will provide a unique resource for organizations considering raising fast-growing trees for energy. The Reynolds Metals Company in Massena, which now has approximately 200 acres in cultivation, is an example of the type of audience that receives these research results through technical bulletins and workshops, as well as formal reports. In addition to working to develop fast-growing trees, we are cooperating with several other institutions to evaluate the mechanisms of possible forest decline and the effects of atmospheric deposition on forest nutrient cycles and tree metabolic processes. The knowledge generated from this activity may help to preserve the existing forest resource for all uses, including energy. After several years of research supported by NYSERDA and the gas industry, the State University of New York at Stony Brook has established a successful test farm for promising seaweed species in Long Island Sound. Data from the farm will form part of the basis for an evaluation of the economic prospects for maricultural energy, and future work, if warranted, could be expanded to include processes for converting seaweeds to fuels and chemicals. The growing and processing of seaweeds represent a potential new industry for coastal communities as well as a source of energy. NYSERDA also has completed a survey of the prospects for energy from herbaceous (nonwoody) plants in several regions of New York. The study evaluated the advantages and disadvantages of growing 49 different species, and although this resource is generally costly compared to surplus wood today, the report will be useful for future developers of energy farming concepts. Finally, within the past year the Authority began to build upon an earlier statewide survey of peat resources by assessing the technology, economics, and environmental impacts of exploiting peat as a fuel in New York. This multiyear project, managed with the advice of a formally constituted panel of representatives from relevant state agencies and interested institutions to assure that the analysis is objective and thorough, will enable the state to formulate policies that balance energy benefits with environmental costs and will provide

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future peatland developers with known technologies for mitigating adverse impacts. 2.2 Direct Conversion Concentrating on innovative, near-term applications of biomass to meet needs for heat and mechanical power, the direct conversion component of the program consists principally of technology transfer. Within the past year, reports were completed on the safety of wood stove installations in New York and on the performance of different conventional and advanced wood stove designs. NYSERDA carried out a major television and radio consumer education campaign throughout the state and organized meetings with cognizant state agencies to call attention to the frequent incidence of potential fire hazards in New York wood stove installations. For the commercial/industrial sector, NYSERDA published a generic assessment of the commercial potential for wood gasification in New York State. The result was two reports—one for technical and another for general audiences —identifying opportunities for energy consumers to substitute wood for conventional fuels. The Authority also secured DOE funding through the Coalition of Northeast Governors for a wood-energy component of the State Energy Office’s Energy Advisory Service to Industry. One of the barriers to implementation of cost-effective industrial and commercial wood-energy technologies is uncertainty about the performance of newly developed equipment. NYSERDA has instituted a risk-sharing program under which it will underwrite the cost of certain equipment to be used in innovative wood-energy systems. NYSERDA will be repaid by the developers on the condition that the systems perform according to specifications agreed upon in advance. 2.3 Fuels and Chemicals Edward Lipinsky has discussed the wisdom of producing biomass substitutes for energy-intensive chemicals, not only to burn as fuel, but also to use for other purposes. The value added in the conversion process is greater in the case of many nonfuel chemicals, and the fossil energy required to make commodity petrochemicals can exceed a given product’s heat of combustion by a factor of 2 or 3. Wood’s constituents are each suitable for different applications, such as papermaking, chemical production, and energy conversion. NYSERDA is pursuing a promising concept by helping a new New York firm test the suitability of wood-derived intermediates for a variety of industrial applications. The results, if favorable, will contribute to an investment decision to construct a

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$20 million facility in the state to process 630 tons of wood per day. This type of plant will make possible the production of fuels and energy-intensive chemicals as other downstream conversion technologies emerge. Ethanol (ethyl alcohol) has the advantage that it can be derived from biomass and blended readily with gasoline for motor vehicles. Although ethanol for fuel blending is now generally made from grain, it also can be produced from wood, which is abundant in the Northeast. NYSERDA completed an investigation last year into the most promising near-term technology for conversion of wood to ethanol and identified the Brink acid hydrolysis approach as closest to commercial application. As a result, the Authority is sharing the cost of a testing and evaluation project designed to lead to construction of a $25 million installation to produce 2.75 million gallons of ethanol per year and a variety of coproducts at a site in Franklin County. A longer-term wood-to-ethanol prospect is being evaluated in a site-specific design and feasibility study for a facility employing enzyme hydro lysis at a location in Jefferson County. The project, jointly sponsored by NYSERDA and DOE, will explore the potential for commercial adoption of a technology advanced in part through federal programs. The next stage of development, if warranted by the study’s fundings, is likely to be supported by NYSERDA and a private industrial concern, with diminished dependence on DOE. Another milestone in our petrochemical substitutes program was the completion of the first phase of a laboratory effort at Rensselaer Poly-technic Institute, cost shared by two industrial concerns, to perfect a process for converting sugars derived from wood to useful chemicals that could substitute for petroleum- or natural-gas-derived materials. The initial results indicate that fermenting 2, 3-butanediol from glucose is feasible and economically promising. Planned subsequent work will examine xylose as a raw material and will attempt to produce glycerol and succinic acid as additional products. 2.4 Municipal Solid Waste(MSW) One of the principal barriers to further construction of MSW combustion installations is the public concern over dioxin emissions. In addition to cosponsoring a national workshop to standardize dioxin sampling and testing protocols, NYSERDA is supporting one project in Albany and organizing another in Pittsfield, Mass, to ascertain the relation of emissions of dioxins and similar substances to the operating characteristics of MSW-fired boilers. The results will be useful for improving system design, introducing more effective operating procedures to control emissions, and informing the public on resource recovery facility siting. Other projects within our program involve pretreatment processes for MSW. At one facility we are testing a slow speed rotary shear shredder in a side-by-side comparison with an existing hammermill. At another site, a novel rotary drum air

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classifier design is being tested with both shredded and unshredded municipal waste. After completing several projects on landfill gas recovery and utilization, NYSERDA and the Gas Research Institute are conducting trials of leachate and condensate recycling as means to accelerate gas production and to mitigate environmental impacts. The project, located near Binghamton, should result in better ways to design and operate landfills from the perspective of economical gas production as well as environmentally acceptable waste disposal. 2.5 Sewage Treatment Processes NYSERDA supports a wide range of activities that contribute to improved energy recovery from sewage. Two research projects are designed to enable improved management of anaerobic digestion processes. One involves the use of pure starter cultures to establish optimal microbial populations. The second is exploring parameters other than temperature and acidity that could provide early indications of process upsets and eventually form the basis for improved feedback control. In part to addressing the unique problems associated with disposal of sewage sludge contaminated with chromium from tannery wastes, NYSERDA, the Commonwealth of Massachusetts, and gas companies from New York and New England are supporting construction of a pilot plant that employs the Institute of Gas Technology’s two-stage anaerobic digestion process. The plant will provide the design basis for a possible full-scale installation at Salem, Mass., and at other communities, in New York and elsewhere, faced with similar sludge disposal problems. Our new program of sewage treatment plants as total energy systems contributes to solving immediate problems at New York municipal installations on a cost-shared basis. Projects initiated at various locations this year include oxygen compressor modifications, new process air blowers, fume incinerator heat recovery, improved sludge dewatering and incineration, and wastewater coupled heat pumps.

GRI’s PROGRAM ON METHANE FROM BIOMASS AND WASTES P.H.BENSON* *Gas Research Institute, Chicago, Illinois

SYNOPSIS The Gas Research Institute’s (GRI) Program on Methane from Biomass and Wastes was originally an initial high-risk, long-term project to achieve a large quad impact from a marine biomass feedstock. The program evolved to a more comprehensive yet integrated effort to produce low-cost gas from wastes and biomass/waste blends in the near- to midterm, and cost-competitive gas from the much larger biomass resource base in the longer term. A systems approach is utilized to develop and integrate the multidisciplinary technologies to provide supplemental supplies of natural gas in the near term and to meet long-term gas demands in the future. Emphasis has been placed on the development of regional biomass and waste to methane programs to provide the gas industry with the flexibility to scale methane production systems up or down in response to local energy demand. Participation and cofunding by regional entities are measures of success of these programs and have been encouraged to further leverage GRI’s R&D dollar and promote earlier market penetration by alternative energy systems. 1 INTRODUCTION Baseline projections of U.S. energy supply and demand indicate that approximately 8 quadrillion Btu (quads) of gas per year may be required to supplement diminishing supplies of natural gas after the turn of the century. Researchers have estimated that roughly 25% and 40% of the U.S. gas supply will be from supplemental sources by the years 2000 and 2010, respectively (Ref. 1). Supply technologies under development are expected to provide lowcost gas within this timeframe to the mutual benefit of the gas consumer and the gas industry. One of the three supply options being investigated by GRI is the production of methane from biomass and wastes. GRI’s Methane from Biomass and Wastes Program has evolved from an initial high-risk, long-term project using a marine

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biomass feedstock to a study of low-cost gas from wastes and biomass/waste blends in the near- to midterm and cost-competitive gas in the longer-term. Accordingly the program has been divided into a near- to midterm component, Methane from Wastes, and the longer-term component, Methane from Biomass. GRI developed a regional approach to implementing its biomass and wastes program. The purpose of this paper is to briefly discuss the rationale for the nearterm and long-term components and highlight some specific projects. 2 THE PROGRAM Figure 1 shows that 10 quads of methane could be produced from biomass and wastes by the year 2020. Cost-competitive methane from landfills is presently commercial. By improving processes and utilization of the resource base, more low-cost gas can be expected from other wastes, such as municipal solid wastes (MSW), and waste/biomass blends in the near-to midterm. Eventually, after the year 2000, terrestrial energy crops and ultimately marine biomass feedstocks will play a significant role. By implementing a multidisciplinary effort (Fig. 2) GRI brings together specialists from many areas to integrate the appropriate technologies, particularly biomass production and biomass conversion. Production includes such tasks as planting, crop management, harvesting, and feedstock transportation. Conversion includes feedstock storage and pretreatment, reactor design, inocula development, digester effluent, and residue post-treatment and gas-cleanup. Although most waste feedstocks lack a production element, both biomass and waste have many common physical/chemical characteristics and undergo similar steps in conversion to methane. The utilization of wastes for energy production often has the added benefit of alleviating a waste disposal problem. This nearterm component will be discussed first. 3 METHANE FROM WASTES The overall objective of this project is to develop and integrate processes to produce low-cost methane from various municipal, industrial, and agricultural waste feedstocks. Many waste feedstocks are ubiquitous across the country; however, agricultural and industrial wastes, being more region-specific, are addressed in that manner. Projects are under way in this area to: • Develop landfill gas enhancement techniques to improve methane generation rates and yields and significantly increase the resource base • Develop baseline biomass production and conversion data for converting water hyacinth/waste mixtures to methane

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• Demonstrate the feasibility of producing low-cost methane from MSW and sludge blends in single- or two-phased anaerobic digestion systems • Identify and document the potential industrial and agricultural waste resource base • Develop small-scale, cost-effective gas cleanup systems for application to wastes and biomass to methane systems. The activities in the methane-from-wastes area are designed to provide low-cost methane from landfills in the near-term and from MSW and other wastes in the mid-term. Presently methane generated from landfills is being injected into the pipeline at a cost that is competitive in today’s energy market. The data base for making price projections of pipeline quality methane from landfills estimates costs at $4 to $5/106 Btu ($3.86 to $4.82/GJ). The cost of methane from waste feedstocks could be lower with modest improvements in conversion technology and the development of cost-effective gas-cleanup systems as small as 1 million standard cubic feet or less of methane per day. Such waste conversion systems could be operated by municipal or distribution companies and the local waste disposal industry. Because of their relatively small size, methane from waste systems can be implemented locally in a relatively short time, which is a further benefit in their regional application. The utilization of wastes for energy production is also facilitated by integrating gas production with waste treatment/disposal systems. This synergism of an existing waste treatment infrastructure with methane gas production is exemplified by a GRI project, methane from a water hyacinth sewage treatment system, under way at Walt Disney World. This program is discussed in detail by Tom Hayes elsewhere in this proceedings. A prelim inary technical and cost analysis of this system indicates that if gas generated is sold at a levelized cost of $2.50 to $5/106 Btu ($2.41 to $4.82/GJ), depending on the size of the wastewater treatment facility, the costs of achieving secondary wastewater treatment standards are the same as or lower than those of a conventional secondary wastewater treatment facility (Ref. 2). In 1983 GRI became involved in another major waste treatment/energy production project with the U.S. Department of Energy (DOE) and Waste Management, Inc., in Pompano Beach, Fla. At this facility, processed MSW and sludge blends are fed directly into an anaerobic digester to produce methane and significantly reduce solids disposal. The numerous front-end processing problems that had been previously plaguing this operation were resolved and the original plan—to load the digester at different rates to steady state—is being accomplished. Results to date indicate that RefCoM digester performance equals or surpasses bench-scale experiments, and system and cost analyses look most promising (Ref. 3).

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4 METHANE FROM BIOMASS The objective of this component is to develop the technology base to produce low-cost methane from biomass through the application of engineering and agricultural sciences. To meet this objective, we are addressing research and development sensitivities in biomass-to-methane systems to yield low-cost gas by the year 2000, and applying advanced biotechnologies to biomass production and conversion systems to reduce the cost even further. Presently applied R&D is focused on conversion of sorghum, napier grass, and water hyacinth, and on high- and low-solids anaerobic conversion systems. By 1990, one crop and the appropriate conversion system will be selected to demonstrate the component parts of a biomass-to-methane system. The technical and economic feasibility of this system will be established and if warranted a subsequent development effort will be supported to bring an integrated system to the point of commercialization by the year 2000. In a second parallel effort, longer term R&D will be conducted to apply advances in biotechnology to further reduce the cost of methane by improving plant yields while reducing energy inputs such as fertilizer and water addition, and by increasing bioconversion rates and yields. 5 REGIONAL METHANE FROM BIOMASS AND WASTE PROGRAMS GRI has adapted a regional strategy to develop the technologies to produce methane from biomass and wastes and to foster the necessary infrastructure to eventually commercialize such systems. This approach, involving local institutions, researchers, agricultural organizations, and gas companies through cofunding and participation in the R&D, benefits both the gas industry and the regional participants. A local supply of energy provides socio-economic benefits, can be utilized at a relatively small scale, requires less risk capital, and has a relatively short time frame for facility implementation. Estimated capital costs of biomass and wastes systems are in a range affordable to municipalities and other local entities as well as individual industries. The R&D dollars required for demonstration and scale-up are also less than those required for most other supply options. 5.1 The GRI/IFAS Southeastern Regional Program This pioneering regional program, cofunded by GRI and the State of Florida through the Institute of Food and Agricultural Sciences (IFAS) at the University of Florida, was initiated in July 1981. Florida consumes 2.5 quads (2.6×10 GJ)

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of primary energy, of which 0.1 quads (4.1×10 GJ) is methane. Only 10% of this amount is from in-state gas wells, which are being rapidly depleted. Florida’s number one industry is agriculture; there is a plentiful supply of biomass and an environment that is conducive to year-round biomass production. As a result, research on biomass energy systems was under way at many of IFAS’s 22 research centers and in 18 academic departments at the University of Florida’s Gainesville campus prior to the GRI/IFAS regional program. Much of this existing expertise was brought into the GRI/IFAS regional program by refocusing existing projects and initiating new projects with the common goal of producing low-cost, pipeline-quality methane. An initial objective was to examine a variety of energy crops to determine their potential for methane production and to define energy crop management techniques to maximize biomass production. Over 250 varieties were evaluated. In many cases biomass yield could clearly be doubled simply by close-spaced planting for energy, which is not permissible for food or fiber crops. Napier grass and water hyacinth were selected as model feedstocks on which to focus R&D for an integrated biomass-to-energy system. Other promising biomass feedstocks are still being pursued as part of a longer-term research effort. Growth and production models developed for napier grass and water hyacinth exhibited an excellent fit to actual field data. In accordance with the solids content of the two feedstocks, both high- and low-solids bioconversion systems are being developed. Emphasis was placed on a high-solids type conversion system in the IF AS program, and a series of large bench-scale units are being used to test a two-phase leachate bed/packed bed conversion system with highsolids feedstocks such as napier grass. This work is supported by other highsolids conversion studies being conducted at Cornell University as part of the Northeast Regional Program and low-solids work which is being conducted primarily at the Institute of Gas Technology (IGT) in Chicago. As part of the longer-term, more advanced portion of the program, work on tissue culture propagation and genetics is under way. Somatic hybridization and other genetic approaches are being applied to produce new plant strains, and fluidized gel seeding techniques for planting tissue culture embryos are being developed. New strains of methanogenic bacteria have been isolated that have both cyst-like and disaggregated stages in their life cycles. The importance of these bacteria to methane generation is being studied. Work on cellulases has isolated and characterized cellulase mRNA and cDNA. This work is being focused on the important cellulytics found in anaerobic digesters. A site-specific study conducted in the Lake Apopka Natural Gas District located near Orlando revealed that the preferred approach at this site was a dedicated energy farm to grow either napier grass or water hyacinth (Ref. 4). Economies of scale indicated that for pipeline quality gas, a facility size of at least 10 Btu/yr would satisfy most of the gas needs of the local gas district. Land or lake requirements for energy crop production to supply this need were available. The study also examined the cost of methane production using state-of-

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the-art, baseline technology and technology advanced through a modest R&D program; baseline gas costs needed to be reduced by one-half to be costcompetitive by the year 2000. Sensitivity analyses indicated that by obtaining napier grass and water hyacinth biomass yields of 20 and 33 dry ton/acre-yr, respectively, and by developing a two-phase, high-solids conversion system for napier grass and an automated harvesting system for water hyacinth, costcompetitive gas could be produced without major technology breakthroughs. Napier grass yields of 14–27 dry ton/acre-yr have been obtained with varying fertilizer and harvesting strategies at a number of small test plots in central and northern Florida. Water hyacinth yields of 22–26 dry ton/acre-yr have been achieved in water from Lake Apopka in 1/4-acre test ponds with yields up to 50 dry ton/aore-yr in smaller tanks with nutrient addition. Yields up to 35 dry ton/acreyr have been achieved in parallel experiments at Walt Disney World growing water hyacinth in treated sewage effluent. The next step is to demonstrate that higher yields can be sustained in larger test plots with intensified crop management and harvesting schedules. As part of the GRI/IFAS program, a review panel has been formed to ensure that industry is informed of the program and that industrial interests are recognized. This panel consists of leaders from the state’s gas and agricultural industries and representatives from the governor’s office. 5.2 The GRI/Texas A&M Energy Sorghum Program This program focuses on producing one feedstock: sorghum. As with napier grass and water hyacinth, the work with sorghum is providing a model for methane production that could be utilized with other crops in other regions of the United States. Sorghum is not restricted to any particular region, although Texas is the largest sorghum producer in the United States, producing over half of the 13 million acres/yr (5.8 million ha/yr) grown in the United States. Conducted at Texas A&M University, this program is cofunded by the Texas A&M Research Foundation and GRI. Texas A&M is a world leader in sorghum breeding and the development of new uses for sorghum. They have extensive previous experience as a multidisciplinary team in developing sorghum-toalcohol production systems. Their team approach to research involves agronomists, plant physiologists, agricultural engineers, and economic and systems analysts. Sorghum varieties are being developed based on their biomass yields, bioconvertibility to methane (yield and rate), pest resistance, fertilizer and water requirements, and harvestability. Plants are also being developed to allow the producer several options, i.e., traditional grain production, grain production plus forage conversion to methane, or total plant conversion to methane. If the entire plant is utilized, tilth, fertility, and organic matter levels in the soil and harvest intervals become important and must be considered in the overall system.

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Biomass yields of hybrid sorghum grown in small test plots are twice those for commercial grain sorghum, 16 versus 8 dry ton per acre-yr (35.8 versus 17.9 dry metric ton/ha-yr) . Some of these high-energy sorghums are also low in lignin, which significantly improves bioconversion to methane as illustrated in Fig. 3. High methane yields, 5.0 to 6.4 ft3/lb (0.3 to– 0.4 m3 /kg) volatile solids (VS) have been obtained with some of these varieties. The theoretical maximum is 7.5 ft3/lb (0.46 m3/kg) VS. This indicates that plants such as Brown Mid Rib can be tailored for maximum methane production. A reduction in volatile organic matter of 94% is also possible with sorghum, the highest observed to date for any biomass energy crop. Economic and technical sensitivities are being determined and incorporated into a system model to evaluate various sorghum production/ conversion system configurations. Analyses indicate that feedstock costs and methane yields have greater impact on total costs than does methane production rate. To obtain maximum methane yields from the feedstock, a conversion process that provides a long solids residence time is desired. Consequently a simple, low-cost conversion system for methane production and upgrading to pipeline-quality gas is being developed. 5.3 The GRI/NYSERDA/NYGAS Northeastern Regional Program A third regional program has been recently established in the northeastern United States, which depends on imported oil at the rate of about $20 billion/yr to meet the bulk of its energy needs. About 0.5 quads/yr (5.2×10 GJ/yr) of energy is derived from biomass in the Northeast, mostly from the direct combustion of wood. Researchers estimate that this quad impact could be increased fourfold simply by utilization of the area’s 73 million acres (29.2 million hectares) in forest land resources (Ref. 5). The northeastern region of the United States also has one of the highest rates of gas usage per capita. The development of a regional supply of gas could be particularly important in winter months when localized gas shortages can occur. While the goals of this regional program are similar to those of the other regional programs, the structure and development of the program are quite different. This program arose from the recognition that several projects being cofunded by GRI, New York State Energy Research and Development Authority (NYSERDA) , and the New York Gas Group (NYGAS) would be best integrated into one R&D program. The management structure of the program is based on the cooperative efforts of these three funding organizations, none of which conducts in-house R&D. Projects for inclusion into this program come from unsolicited proposals or solicitations, and the three participants must agree on new projects. The northeastern program began in 1983 as a collection of existing projects, and is evolving into a more focused and structured program. The projects initially addressed included landfill gas recovery, woody and marine biomass

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production, high-solids bioconversion, and small-scale, modular gas cleanup. Additional projects recently included in the program are an innovative benchscale, gas-cleanup system and woody biomass bioconversion research. The program will focus on a biomass feedstock and conversion system in the future. 6 SUMMARY GRI’s Methane from Biomass and Wastes Program is focused on the production of pipeline-quality, low-cost gas in the near to long term. Consequently the program consists of two major components: a near- to mid-term methane-fromwastes component and a longer-term component to produce methane from biomass. These technologies can have an impact on supplemental supplies of gas according to their economic competitiveness and future supplies of natural gas. Because of the regional nature of biomass feedstocks and wastes and the benefits that can be derived from a local feedstock supply, emphasis has been placed on the development of regional programs to convert biomass and wastes to methane. GRI has pioneered such regional efforts to provide the gas consumer with a secure supply of low-cost gas and the gas industry with the flexibility to adjust methane production in response to local energy demand. Cofunded and comanaged regional programs, which utilize a systems approach to develop and integrate the appropriate multidisciplinary technologies, have been established in Florida, New York, and Texas for this purpose. The participation and cofunding by regional entities, industrial cosponsors, and others are measures of the success of these programs and are encouraged by GRI. Through closely coordinated R&D efforts, the specific requirements and energy resources of the United States can be effectively addressed, and the cost for the research, development, demonstration, and implementation of the technology can be reduced. REFERENCES 1.

2.

3.

4.

Holtberg, P.D., Woods, T.J., Ashby, A.B., Dryfus, D.A. and Hilt, R.H. ‘GRI baseline projection of U.S. energy supply and demand 1983– 2010’, Gas Research Insights, 1984. Bird, K.T. and Ashby, A.B. ‘Recent economic results of converting biomass to methane’, Symposium Papers, Energy from Biomass and Wastes VIII, Institute of Gas Technology, January 1984. Wilkey, M.L. and Edwards, G.N. ‘An economie analysis of the biological gasification of municipal solid wastes—sludge blends by the RefCoM process’, Energy from Biomass and Wastes IX, January 1985. Warren, C.S. et al. ‘The methane from biomass and wastes program task 1: Evaluation of the Lake Apopka Natural Gas District’, Gas Research Institute Topical Report, GRI 84/0015.1, 1984.

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Fig. 1. Potential quad impact by resource and possible year of commercialization

Fig. 2. An integrated biomass and waste to methane system 5. 6.

7.

CONEG. ‘Coalition of Northeastern Governors Northeast Regional Biomass Program briefing documents’, 1984. Benson, P.H., Frank, J.R. and Isaacson, H.R. ‘Gas Research Institute programs on methane from biomass and wastes’, Symposium Papers, Energy from Biomass and Wastes VIII, Institute of Gas Technology, January 1984. Gas Research Institute. ‘Methane from biomass and wastes research: renewable resources for localized energy production’, GRI Brochure, 1984.

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Fig. 3. Bioconvertlbility of sorghum varieties based on ABP bioassay

PUBLIC POWER RESEARCH IN BIOENERGY MICHAEL K.BERGMAN* *Director of Energy Research, American Public Power Association, Washington, D.C.

Uncertainty resulting from markedly changed circumstances has caused many electric utilities to rethink conventional approaches to power generation and supply. Rising energy prices and increasing reliance on foreign energy supplies have created impetus for improved energy efficiency. Concerns over environmental quality and retention of energy-related expenditures in the local economy have focused attention on the use of local energy resources. These factors—in addition to many others—are especially important to the nation’s 2200 publicly owned electric utilities. The American Public Power Association (APPA) and its members have therefore been active in the past decade in promoting new energy technologies and energy resources and the means to integrate them at the community level to achieve the highest overall efficiencies. Bioenergy research has been a particularly active area of attention. In addition to highlighting bioenergy projects and technologies in publications and at technical meetings, APPA has devoted a substantial part of its research funding to biomass projects and will continue to support increased federal funding. Although estimates for prospective contributions of biomass to national energy requirements appear small in comparison to conventional sources, the contribution of biomass can be quite substantial at the local level. In particular, the use of bioenergy retains energy expenditures in the local economy, can lead to extremely low fuel costs, may reduce volumes of waste that would require disposal, lessens sulfur dioxide control requirements, and may often require minimum modifications in existing equipment. As a result, APPA has devoted 15% of its R&D budget to bioenergy projects over the past decade. Thirty-five installations or projects are now active within public power systems. Because of the diversity that characterizes bioenergy projects, a case study approach has been taken to describe these activities. The following case studies describe 12 projects undertaken by public power systems.

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1 CASE STUDIES Case Study Number 1

Palo Alto, Calif., is adapting its water treatment plant’s incineration process to decrease natural gas required for incineration. Methane from the city’s landfill adjacent to the plant will also be recovered and used for supplemental power generation. The project reduces natural gas requirements by 50% (41,250 therms) and provides about 2.2 MW of capacity and 17,600,000 kWh of energy. Total project cost is estimated to be $5 million. Case Study Number 2

Feedlot operators in Lamar, Colo., have designed a large-scale bioconversion facility that can produce methane gas from the manure of approximately 50,000 feedlot cattle. Through anaerobic digestion, about one million cubic feet of gas could be produced daily. Present natural gas prices do not now justify the project. However, Lamar has donated a small-scale bioconversion facility to the local community college and is assisting in the development of an alternative energy curriculum. The course work will cover biomass, gasohol, wind power, and solar energy. Case Study Number 3

The municipal utility at Lakeland, Fla., has been harvesting cattails and water hyacinth used for tertiary water treatment as a supplemental fuel supply at its coaland-garbage-fired, 364-MW McIntosh No. 3 Generating Unit. The utility is also test burning peat and wood chips as supplementary fuels. Case Study Number 4

Researchers in Tallahassee, Fla., are studying replacement or conversion of gas- and oil-burning utility boilers to those that burn biomass as the primary fuel. A fuel availability study indicates an adequate local biomass fuel supply. Researchers are conducting a technical and economic feasibility study to be completed by October 1984. Case Study Number 5

Minnesota municipalities are very active in bioenergy research. For example, Grand Marais was awarded a state grant to study district heating. The city, which has no district heating system of its own, is using its $20,000 grant to fund a preliminary study on burning municipal waste and wood in a new district heating project. Researchers in Grand Rapids are studying the feasibility of building the city’s first district heating system, possibly fueled by wood or municipal waste. Under

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scrutiny are systems involving a downtown area, providing process steam or hot water to commercial users, or the option of cross-connecting a coal-fired, cogeneration facility run by a paper company. Hibbing has been selected by the Iron Range Resources and Rehabilitation Board—an agency of the State of Minnesota—as its prime site for a wood products park. Hibbing was not only the most suitable for immediate construction, but the utility could use the wood residue to fire one of its boilers. Hibbing will also extend its district heating system to provide both heating and process heat to the new industrial park. Both Wood Industrial Park and Hibbing Utility customers will benefit from lower fuel costs and expanded utility use. The first phase of the wood products park would include a high-efficiency, small-log sawmill to meet regional demand, a lumber concentration yard for upgrading, a dry kiln, a planner mill, a hog mill, a chemical mixing plant to supply regional processors with formulations for wood stabilization and preservation, and a wood dip-treating facility. The first phase of construction will require approximately $5 to $6.5 million. Funding will be provided through a combination of grants, loans, and bonds from the Iron Range Resources and Rehabilitation Board, industry, and financial institutions; tax increment financing from the City of Hibbing; and industrial revenue bonds. The 180-acre Hibbing Industrial Site, known as Agnew #3, owned by the city and purchased for industrial growth, will be totally dedicated to the Wood Industry Development. Researchers working for the City of Virginia are cooperating with the Minnesota Department of Energy and Economic Development to test use of peat, a sizable state resource, as a fuel in conventional boilers for production of electric and thermal energy for district heating systems. The researchers hope to prove peat’s value and determine maximum sustainable capacity of the boiler relative to its design capacity using peat and peatcoal mixtures, boiler efficiency, and gas and particulate emissions from the boiler. Three test burns have been used to determine the feasibility of using peat as a boiler fuel or fuel extender in a power plant. The utility burned a mixture of 25$ peat and 75% coal during the first test, 50% peat and 50% coal in the second test, and 75% peat and 25% coal in the third. Also, the Virginia utility is cooperating with local suppliers to examine the feasibility of using wood wastes as an alternative fuel extender in their conventional boilers to produce electric and thermal energy. Case Study Number 6

Endicott, N.Y., has committed to the construction of a peaking plant that will burn methane gas produced by the village’s sewage treatment plant. The plant will be an adjunct of the sewage plant and will store methane gas for use during the peak winter months. The 750-kW facility will also serve as an emergency back-up power supply for the treatment plant. Gas produced during off-peak months will be stored in stationary tanks adjacent to the plant. A feasibility study —completed under grants from the Appalachian Regional Fund and APPA’s

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DEED program—indicated that the village could save $500,000 over a 20-year period if the plant is built. Case Study Number 7

The utility in Eugene, Ore., is operating a wood-fired district heating system. Eugene is also collaborating with the Weyerhauser Company to generate 51.2 MW from steam supplied by boilers fueled with a by-product of the pulp and paper process. Eugene has had steam district heating in downtown areas since 1906; since 1941 the thermal energy has come largely from combustion of wood waste. The district heating network, which presently serves 150 customers, is now expanding to serve the load of a major new convention center and hotel. Twenty-two acres of greenhouses are heated by recovered energy. Case Study Number 8

The utility in Watertown, S.D., is utilizing biomass pellets to produce steam for its district heating system. The project, initiated in 1979, has resulted in the savings of over 2.1 million gallons of No. 2 fuel oil. The biomass consists mostly of flax shive pellets produced locally, although some sunflower hull and wood waste pellets have also been used. Case Study Number 9

In Burlington, Vt., the 50-MW wood-burning McNeil Generating Station was dedicated in March 1984. Designed for intermediate and peak generation, the plant burns 1300 metric tons per day of wood chips harvested within a 100-km radius of the city. The commitment for the plant resulted from earlier success with a 10-MW facility. Delivered power costs between 6¢ and 7¢/kWh. Burlington has also established a tree farm family program to help supply wood chips for the McNeil Station. The utility provides professional forest management service to landowners with 10 or more acres of woodland. In turn the landowners guarantee wood chips for the electric department. Burlington will supervise harvesting by selective thinning to ensure that only undesirable waste wood is removed. The Burlington utility has been using wood chips from forest residue since 1977 to fire its 10-MW plant. The utility is also considering the use of municipal solid waste, wood, and methane from landfill in an electric generator. Finally, Burlington expects to have access to an increased supply of low-quality wood for the McNeil Station as a result of a computerized forest inventory system that will enable landowners to predict timber yield on their land over many years. The computerized method is expected to improve the accuracy predicting future revenues. The system eventually will be available through computer terminals at county forestry extension service offices. Case Study Number 10

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Researchers at Benton County PUD, Kennewick, Wash., are evaluating a biomass gasification system with Pyrenco Inc., of Presser, Wash., and the Bonneville Power Administration. The system produces electrical energy in an internal combustion engine generator system. Virtually no ash or tars are created in the gasifier, resulting in a clean syngas stream. Biomass substances to be used include apple pomace, grape pomace, mint hay, and wood chips. Peat and municipal solid wastes may also be used. Case Study Number 11

A final report has been completed on a five-year evaluation of factors affecting growth of red alder and black cottonwood in biomass plantations in the Seattle area. Red alder appears to perform better than black cottonwood in the climate and soils available in the Northwest. Researchers are now evaluating other fuel supplies, such as hardwood stands slated for conversion to conifer plantings and logging residues. Feasibility studies are under way to determine siting, size, and fuel supplies for a wood-burning power plant. Case Study Number 12

The utilities in Sturgeon Bay, Wis., have adopted an innovative energy system involving heat pumps on a newly constructed sewage treatment facility. The facility won Wisconsin’s State Award for Engineering and Energy Conservation and honorable mention in the same category at the national level. Methane gas is produced in anaerobic digesters to heat the digester and stand-by generators. A heat pump system using heat from the sewage effluent heats treatment plant buildings. Two 350-kW generators that operate on natural gas and methane were installed; each is large enough to operate the entire wastewater treatment plant. Generators are also installed in parallel with the electric system for peak shaving. 2 CONCLUSIONS Experience from these projects and recent developments points to future initiatives that include controlled breeding programs to enhance biomass production; recovery of plant oils as replacements for petroleum; and the use of genetic engineering to enhance methane production by anaerobic bacteria, to recover resources from wastes, to control pollution, and to create synthetic systems for photosynthesis. With locally available bioenergy resources, appropriate load characteristics, favorable institutional climates and a lower cost of money, and community energy requirements wellscaled to smaller generating facilities, the nation’s publicly owned electric utilities have proved that they can economically convert biomass to energy.

THE USE OF BIOMASS FOR ENERGY PRODUCTION AT AMERICA’S RURAL ELECTRIC SYSTEMS W.PRICHETT* *Alternative Energy Specialist, National Rural Electric Cooperative Association, Washington, D.C. The National Rural Electric Cooperative Association (NRECA) is the service organization/trade association that serves the rural electric systems in the United States. Approximately 1000 of these small, consumer-owned electric utilities exist, serving some 70% of the land area and 10% of the load in the United States, in the rural areas where no other utility wanted to serve. The potential for the use of bioenergy in rural America is enormous because bioresidues that can fuel energy production schemes can be found in these areas. In 1973 our nation experienced an oil embargo that made everyone aware that we can no longer be assured a steady supply of energy in the future. Rural electric systems together with other segments of the utility industry contributed in the search for new energy sources in the ensuing years. At its peak in 1980, this effort was represented in more than 200 alternative energy projects at rural electric systems in the United States (some of which were financed by the NRECA Research Fund). Since 1980, with the Reagan administration and the decline in the growth rate in energy consumption, a gradual decrease in interest in developing new sources of energy (including biomass) has occurred. The efforts at rural electric systems are now much less than what they were four years ago. There are, of course, a few far-thinking individuals who are sustaining an effort in the area of developing alternative energy and more specifically biomass resources. The following discussion takes a look at some of these projects. The projects are listed alphabetically by the state and rural electric system where the project is taking place, and no particular significance should be attached to the order in which the projects are discussed. The Alabama Electric Cooperative in Andalusia, Ala., has an old coal-fired, three-boiler, steam-electric power plant with a capacity of 10 MW. The plan is to use one or more of the boilers at the plant to produce steam to distill alcohol produced from local grain. The plant production capacity is estimated at 20 to 40 million gal/yr, and the stillage from the fermenting process would be used as a high-grade cattle feed supplement. The alcohol would be used to produce high octane unleaded gasoline (gasohol). The cooperative has purchased 40 acres next to the power plant and is seeking a partner (an oil or chemical company) to cofinance the project.

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In the late 1970s at the Alaska Village Electric Cooperative (serving some 40 villages all over Alaska), the cost of fueling their diesel generators was becoming prohibitive. The manager of the cooperative began to search for an alternative. Together with the State of Alaska, the cooperative financed the construction of a wood-waste-fueled biogas production unit that could be hooked up to a diesel generator and, with modifications, fuel that generator. The 150-kW gasifier was produced by a company in California and moved to Anchorage for test operations. Tests proved to be successful, and the cooperative, together with Marenco (a local engineering firm) and the State of Alaska, is now working on a 250-kW unit. At Walton Electric Membership Corporation in Monroe, Ga., the rural electric system, together with the Georgia Institute of Technology and a local dairy farm, has built a manure-to-methane, electric-generating operation. At the Mathls Dairy, which has approximately 100 cows, the manure is collected and slurried to an underground digester tank. The gas produced is burned in a modified 50kW Waukeshau gas-spark-ignition engine, and the electricity is used on the premises to run milk chillers and other equipment. Anoka Electric Cooperative in Anoka, Minn., together with an engineering firm, Perennial Energy, Inc., of Oakbrook, Ill., is mining the local landfill for methane, and the mined gas is burned to 2 Minneapolis Moline 160-HP gasspark-ignition engines with 105-kW generators attached to each. Since beginning operation in January 1984, the two generator sets have produced nearly 600,000 kWh (a plant factor in excess of 70%). Problems with the occurrence of poisons (chlorinated hydrocarbons), which can reduce the lifetime of the engine have been reported, but the project is considered a success. The Goodhue Electric Cooperative in Zambrota, Minn., and a local dairy farmer with a 50-cow herd have also built an anaerobic digestion system and are using the methane produced to generate electric energy. The digester is a converted “Butler” silo, and the engine generator is a natural gas internal combustion engine with 10-kW generator attached. Along the same lines, at a chicken farm in Rushford, Minn., with the encouragement of the Tri-County Electric Cooperative, the chicken manure from more than 50,000 chickens is anaerobically digested to produce methane gas. The gas is then burned to produce heat for the chicken house and an alcohol fuels plant next door. On a much larger scale, at Dixie Electric Power Association in Laurel, Miss., a local paper pulp mill has installed 2×25 MW wood-waste-fired cogeneration units that supply the local mill and the rural electric system with power at offpeak times. The mill, which has a 1000 ton/day pulp dryer, is now 95% energy self-sufficient. At Boone Electric Cooperative in Columbia, Mo., together with the University of Missouri Agricultural Engineering Department, the U.S. Department of Agriculture, and a local hog-feed-lot operator, an operation has been set up where the hog manure is anaerobically digested to methane gas and the methane

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gas is burned in a modified engine generator set to produce electricity for onfarm use and thermal energy for an alcohol still next door. The digester is a converted grain bin that handles 510 kg of manure per day, producing 285 m3 of 55% methane, 408 kWh of electricity, and 3 GJ of thermal energy each day. At North Carolina Electric Membership Corporation (NCEMC) in Raleigh, N.C., there has been an interest in using local peat resources to fire a power plant (much as is being done in Finland, Iceland, and Russia) for some time now. Considerable experimentation with harvesting technologies has been done, and NRECA and the Electric Power Research Institute of Palo Alto, Calif., performed a study of the suitability of this concept. The study, which has been released, found that the proposed site was the most desirable (in terms of drying climate and peat quality) in the United States for such a plant and that the economics are competitive with a coal-fired plant of the same size. Presently, NCEMC is awaiting developments on their potential access to the peat resources in question before they proceed with additional development. Basin Electric Power Cooperative (with its headquarters in Bismarck, N.D.) also has an old, inefficient, small, coal-fired power plant. One of the major crops in the area is sunflower seeds. The process of producing sunflower oil and other products from these seeds produces a great deal of hulls, which are waste materials. Basin, in 1979, decided to test the feasibility of using these hulls as a supplemental fuel in the generating station. The tests showed that the hulls had good handling characteristics and almost as high a Btu content as the lignite coal the plant was using as a primary fuel. Basin accepted a proposal from a sunflower processor in 1980 to build a sunflower processing plant next to the power plant. The power plant is providing the processor with waste heat from its boilers and, in exchange, is receiving sunflower hulls as a supplemental fuel. At Minnkota Power Cooperative in Grand Forks, N.D., bordering North Dakota and Minnesota, there is a great deal of interest in the use of local agricultural surpluses to produce useful liquid fuel as substitutes to expensive imported oil. There is an effort under way, spearheaded by several private developers and supported by Minnkota, to build a number of grain-to-alcohol fuels plants in their service territory. This effort has picked up speed during the last year with the pending ban by the Environmental Protection Agency of lead additives as octane enhancers for gasoline and the increasing interest by the major refiners in ethanol to fill that role. The first of these plants is already up and operating. The plant at Walhalla, N.D., is a great local success. It uses 5 million bushels of barley per year to produce 11 million gallons of ethanol fuel per year. The plant was designed by Ultrasystems, Inc. of Irvine, Calif. At Verendrye Electric Cooperative in Velva, N.D. (where sunflowers are a very large local crop) , a substantial amount of sunflower oil is available. The cooperative, remembering the oil embargo of 1973 and the importance of the continuity of agriculture and ensuring a supply of fuel for the local farm machinery, has been involved with and is helping to finance a project at North

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Dakota State University in Fargo to fuel tractors and other farm machinery (which normally run on diesel) on sunflower oil. Results so far are encouraging. The sunflower oil seems to be almost as high an energy content fuel as diesel and can be readily produced on a small scale by local farmers with a press and filter. However, it has a much higher viscosity than diesel oil in cold weather and can produce problems on cold start in the winter. Testing is continuing on what impact sunflower oil has on the long-term life of a diesel engine. Preliminary results indicate no excessive buildup of deposits on the cylinder walls, piston rings, or other critical ports. The National Rural Electric Cooperative Association in Washington, D.C., and East River Electric Power Cooperative in Madison, S.D., have for a number of years been supporting a project to produce alcohol from waste materials at South Dakota State University in Brookings, S.D. The process involves breeding special bacteria that break down the cellulose in materials like old newspapers, corncobs, grain chaff, etc., by converting the cellulose to starches and sugars. These materials can, in turn, be fermented into alcohol. These projects are actually just a sampling of bioenergy projects at rural electric systems all over the United States. The trend is away from rural electric system involvement moving toward third party development and interconnection under the Public Utility Regulatory Policies Act (PURPA). Rural electric systems will probably continue toward their trend of investing in large nuclear and coal-fired power plants, and the abundant biomass resources in their service areas will be developed by third party entrepreneurs who will sell the power produced back to them under PURPA.

SECTION III Biomass Energy Research Projects

INTENSIVE MICROALGAE CULTURE FOR PRODUCTION OF LIPIDS FOR FUEL R.Mclntosh* *Solar Energy Research Institute, Golden, Colorado

SYNOPSIS The worldwide energy shortage and Arab oil embargo of the early 1970s encouraged many nations to look for new sources of oil, electricity, and gas. Renewable resources such as biomass were often highlighted as a long-term solution to the energy problem because of their nondepletable, renewable nature. While the first biomass sources considered were the readily available ones such as corn or wood, it was apparent that new biomass sources should also be developed, among them aquatic species. The purpose of the SERI/DOE Aquatic Species Program is to improve the productivity, conversion to fuels, and cost efficiency of aquatic plant culture technology. The emphasis of the program is on developing a mass culture technology for cultivating lipid-yielding microalgae in the American Southwest (Fig. 1). It was determined that fuels from microalgal lipids presented better options than converting the microalgal biomass to either alcohols or methane. All lipids can potentially be catalytically converted to gasoline, or the fatty acids can be converted to substitute diesel fuels. The Southwest has the necessary lowcost resources available for this technology, including large expanses of flat, underutilized land, and carbon dioxide available from either natural deposits or flue gas from industrial plants. The amount of saline water available will probably determine how much fuel can be produced from aquatic species. This question should be answered during 1985. 1 THE AQUATIC ALGAE RESOURCE Aquatic algae may be divided into two groups: macroalgae and microalgae. Macroalgae range in size from small filamentous forms to very large complex forms such as Macrocystis. Various concepts have been developed for culturing several species of macroalgae for biomass. The giant kelp Macrocystis is being cultivated in near-shore areas off California in less than 20 meters of water. Floating or benthic species such as Sargassum or Gracilaria have been cultured

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in semitropical areas of Florida and Hawaii. The primary storage product of macroalgae is carbohydrate, which can be converted to either methane or ethanol. Microalgae are small unicellular plants that range in size from 1 to 5 micrometers (Fig. 2). Historically, microalgae have been grown in mass culture mainly for food production and waste treatment. Initial efforts at mass culture of microalgae were concerned with food production, but the hope of producing an abundant, low-cost source of protein has not yet been realized. However, the most promising early results of mass culture have been in the field of sanitary engineering, where microalgae are used to treat wastewater in oxidation ponds. This wastewater technology has been expanded to include protein production and treatment of irrigation water. More recently, the possibility of using algae as a source of energy received widespread attention as a result of the energy crisis during the 1970s (Fig. 3). 2 THE PROGRAM The SERI/DOE Microalgae Program was initiated in 1979 with the benefit of several early technology assessments. Research initiated by the Carnegie Institute on growing microalgae in outdoor mass culture (for food) in the early 1950s resulted in one of the most comprehensive early reports an algal growth, physiology, and biochemistry. This work led to expanded efforts by German and Israeli researchers to commercially produce various species of microalgae for both wastewater treatment and animal feed protein. The SERI/DOE program has directed emphasis toward the production of lipids from microalgae for two reasons. First, microalgae are among the few photosynthetic organisms that directly produce and are known to accumulate storage lipids in great quantities. Second, plant lipids have been postulated to be among the best biomass feedstocks for production of renewable, high-energy liquid fuels. In 1945, it was first proposed that plant lipids could be refined to replace some petroleum-derived products. Microalgae are presently being grown in Israel, Australia, Mexico, and the United States for high-value products for the health food market, including the alga Spirulina ($10,000/dry ton) and the vitamin beta-carotene ($60,000/dry ton). The main application of algal mass culture in the United States has been for oxidation ponds used in wastewater treatment. Of increasing importance is the cultivation of microalgae as a food source for culturing fish and shellfish and as a soil conditioner. A nascent industry in the southwestern United States produced over 50 tons of microalgae in 1984. The value of these microalgae, which are converted to high-value health food products, exceeds $10/lb. Microalgae under normal growth conditions contain a high proportion of carbohydrate, polysaccharide, and protein. The lipid content in growing cells was generally reported to be between 5% and 20% of the total dry weight, but in

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1980 Shifrin reported that microalgae under nutrient stress could accumulate up to 72% of their weight as lipids. Even though large accumulations of lipids are found only under stress conditions of nutrient limitation or salinity, certain microalgae are obviously metabolically capable of producing these high-energy compounds in large quantities. The heat of combustion for a typical algal mass is in the range of 8,000–10,000 Btu per pound dry weight, but it is strongly affected by the low heat of combustion of nonlipid products. The specific heat of combustion for algal oils and lipids is approximately 16,000 Btu per pound, and for the purpose of energy or fuel production by microalgae, it is desirable to increase lipid content of these organisms. Microalgae lipids can be classified as polar, membrane lipids or non-polar, storage lipids, such as hydrocarbons and triglycerides. Storage lipids, which accumulate when microalgae cells are stressed, offer the most potential since they more closely resemble petroleum-derived compounds. Imposing stresses, such as nitrogen limitation, increases the percentage of storage lipids. Further initiative for emphasizing lipids for fuels was provided by reports of the direct synthesis of hydrocarbons by various microalgae. Specifically, large quantities of C-30 hydrocarbons were identified in the freshwater species Botryococcus, an organism that is postulated to be responsible for present petroleum reserves. It was initially assumed that hydrocarbons extracted from such organisms could be readily processed by the existing petrochemical industry and used to produce gasoline, although no process evaluations were performed to verify this hypothesis. 3 SITING CONSIDERATIONS Most biomass production technologies require a large, inexpensive resource base to be economically competitive with conventional (mined) fuel sources. The advantages of microalgae are that they can grow in any climatic region of the world, since they require only light and nutrients, and that they are renewable and therefore not limited to fixed deposits like oil, coal, and natural gas. Development of a biomass technology that can exploit the underutilized, marginal resources of the Southwest—flat land, saline water, and high incident solar radiation—offers potential for the production of a high-value energy feedstock from microalgae. This concept has unique characteristics, few competitive impacts, and enormous potential for displacement of exhaustible conventional energy resources. Arizona, New Mexico, Southern California, West Texas, and parts of Nevada, Utah, and Colorado have abundant lands that support relatively little conventional biomass productivity. Resource assessment studies completed in 1983 estimated that up to 25 million acres may be highly suitable for microalgae cultivation, but the definition of criteria was too gross to provide definitive estimates of total resource availability (Fig. 4). The abundance of available saline

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water has also become an issue. While scarce fresh water in this region limits conventional agricultural possibilities, saline and brackish waters are known to exist in large underground aquifers, and large quantities of agricultural drainage waters are present in existing irrigation canals. These water resources are typically underutilized because of their marginal quality and characteristics. In some cases, such as irrigation runoff, they are an economic nuisance that is costly to alleviate. A wide variety of microalgal species can grow in highly saline desert waters. Therefore, despite the fact that desert saline waters differ from marine waters because of different ionic ratios of bicarbonate, calcium, magnesium, and sulfate, these differences may not preclude adaptation of abundant marine microalgae to desert waters. Thus, the natural variability of both marine and desert species may prove to be useful in developing species for desert mass cultivation. There is no doubt that many areas of this technology will need long-term development before a barrel of lipid oil is economically produced and converted into a liquid fuel. The current estimate of the state-of-the-art cost is between $250 and $350 per barrel. To compete by the year 2000, it is estimated that the cost will need to be reduced to $60-$85 per barrel. Although the development of the technology is mid-term, it provides a potentially valuable source of renewable high-energy liquid fuels. 4 RESEARCH ACCOMPLISHMENTS During 1984, research was carried out under three tasks: biological, engineering, and analysis. Biological research was aimed at improving photosynthetic efficiencies and lipid yield of species that can be cultivated using mass culture technologies operated in the American Southwest. Emphasis has been placed on screening for productive species, developing culture and management techniques for growing desirable species, and understanding photosynthetic and lipid physiology as it applies to increasing yields. Engineering research focused on the development and analysis of harvesting schemes applicable to species of microalgae that grow in saline waters. Three system designs and analyses were initiated in 1984, and these designs will be completed in 1985. The analysis task is designed to support technology development through the determination of cost goals, assessment of resources, and evaluation of emerging technologies. A comprehensive technical and economic evaluation was completed during 1984, and this analysis and assessment provided insights into where program emphasis should be placed for the next ten years.

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Fig. 1. Artist’s concept of microalgae fuel farm in the American Southwest

Fig. 2 Micrograph of algal cell

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Fig. 3 Feedstock composition and product distribution

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Fig. 4 Computer-generated map of overall suitability for microalgae culture

TECHNOLOGY FOR THE COMMERCIAL PRODUCTION OF MACROALGAE J.H.RYTHER* *Harbor Branch Foundation, Fort Pierce, Florida

SYNOPSIS The ocean is an ideal environment for the production of energy crops, because it represents 70$ of the earth’s surface and is not heavily used for other purposes. Its plant life, particularly the macroalgae (seaweeds), is highly productive and readily converted to fuel at high efficiency. With few exceptions, such plants are not in demand for other purposes such as food or fiber. Because they are not widely used, seaweeds have not been grown commercially in most parts of the world. The technology for their large-scale cultivation, particularly in the open sea, is therefore lacking. Exceptions are found in the Orient and Southeast Asia, where certain macroalgal species are used locally for food or worldwide for their gelatinous polysaccharides (agar, alginic acid, carrageenin). Such species are grown near shore, usually in protected embayments or impoundments, in commercial culture, using technologies that are, for the most part, both crude and labor intensive. Examples that are discussed and illustrated include Porphyra (nori) culture in Japan, Laminaria (kelp) culture in China, Gracilaria culture in Taiwan, and Eucheuma culture in the Philippines. Culture methods are described and biomass yields are summarized for each species. 1 INTRODUCTION The use of terrestrial plant crops as biomass for fuel is complicated because such products are generally worth more as food or fiber; in addition, the land on which energy crops might be grown could be used to produce the more valuable food or fiber crops (Ref. 1). The growing world demand for food and the current existence of famine conditions that affect a significant fraction of the human race make the concept of energy crops not only economically but also morally questionable. The oceans, however, are virtually unused by man for the production of crops of any kind. Yet marine algae are highly productive, capable of yields as great as

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the best terrestrial crops (Ref. 2) , and such plants are also among the most efficient for conversion to fuel (Ref. 3). Marine algae that are unused for food or other purposes by most human societies could be grown as energy crops without competing for demand for their use or for the area in which they might be grown. There is no well-developed or widely used technology for the commercial cultivation of seaweeds. However, in the Orient and Far East, a few species are now grown for food or for their chemical products, principally the polysaccharides, agar, alginic acid, or carrageenin. For the most part, the existing seaweed cultivation practices may be characterized as low-technology, low-yield, and labor-intensive. Cultivation is successful only because of the low cost of labor and the high value of the product. Despite their primitive nature, however, several sizable industries have developed. They provide a useful background of information for any future consideration of seaweed production systems for energy. The present discussion will be restricted to four of the larger commercial seaweed culture systems currently in operation in the world: Porphyra (nori) culture in Japan, Laminaria (kelp) culture in the People’s Republic of China, Eucheuma farming in the Philippines, and Gracilaria culture in Taiwan. Technical aspects of each culture system will be reviewed briefly, along with the small amount of information that is available on production and economics. 2 Porphyra (NORI) CULTURE IN JAPAN Several species of the red algae genus Porphyra have been grown in Japan, where it is commonly known as nori, as a highly prized food since the seventeenth century. The large sporophyte Porphyra plant (the edible stage) is an irregularly shaped, flat, deep red blade that may grow to a foot or more in length, depending on the species and growing conditions. The Japanese crop comes primarily from P. tenera and P. yezoensis but includes at least four other species. It matures in late fall and may be harvested several times throughout the winter by cutting back the thallus without destroying its attachment. In 1978, 60,000 hectares (ha) of sea surface produced 21,150 dry tons of nori that had a value of $540 million (U.S.), by far the most economically important seaweed crop in the world (Ref. 4). Originally, cultivation of Porphyra consisted of driving leafless tree branches into the sea floor just above the mean water level along the open coastline in the fall of the year. The nonmotile monospores of Porphyra settled on the branches, which were moved to more nutrient-rich habitats at the mouths of or within estuaries. The attached monospores developed into leafy sporophyte thalli, the edible stage and portion of the plant, which was harvested by cutting throughout the winter.

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The branches have been replaced by man-made nets as spore-collecting devices. Typically, these are made of synthetic twine 3 to 5 mm in diameter with 15-cm2 mesh openings about 1 m wide and from 18 to 45 m long. The nets are suspended from bamboo poles driven into the sea floor so that the flat surface of the net is parallel to the water surface. Traditionally in Japan, the nets are placed in the intertidal zone where they are uncovered at low tide. Nori can withstand exposure to air and direct sunlight that kills or inhibits the growth of many of the other epiphytic algae, which may smother or degrade the quality of the nori. In China, in less eutrophic regions where fouling is not a serious problem, the nets and bamboo frames are not driven into but merely rest on the sea floor at low tide. The whole structure then floats to the surface at high tide, and the algae receive better exposure to sunlight, particularly where large tidal amplitudes and high turbidity shade the bottom at high tide. The Chinese also grow Porphyra in deeper water on nets tied to permanently floating bamboo frames. The Japanese nori industry was revolutionized in 1949 with the discovery of the complete life cycle of Porphyra by the British botanist K.M. Drew. Drew’s discovery revealed that monospores are released from an entirely different stage in the life cycle of the plant, the conchocelis, a small, red encrusting form that attaches to mollusc shells and that was previously thought to be an entirely different species of alga. The conchocelis, in turn, is produced from fused sexual spores (carpogonia and spermatia) that are released from disintegrating thalli of the large, leafy sporophyte plant. Now, at the various prefectural aquaculture facilities in Japan, tanks of conchocelis, growing on scallop shells suspended on strings, are maintained throughout the summer months. When the monospores are released in the fall, the large culture nets are suspended in the tanks to ensure a far more complete and successful spore attachment than was achieved by the more haphazard method of suspending the nets in the natural environment. A further refinement of the technique is to produce extra nets with attached spores that may be frozen, thus maintaining the spores in a state of suspended animation from which they may be revived by slow, controlled thawing if replacements are needed for losses due to fouling, predation, storm damage, or other causes. The productivity or yield of Porphyra is not usually given in the literature that describes its cultivation. A rough estimate (Ref. 5) placed mean production at 0. 75 dry ton/ha/yr. A similar calculation may be made from the data on total area farmed and total annual production for 1978 reported in Ref. 4; that figure is 21, 150 ton produced over 60,000 ha for an average of 0.35 dry ton/ha/yr. Both figures are probably conservative, and higher values are certainly achieved, but the culture method apparently does not permit high yields of the alga. However, Japanese culturists are much more concerned about quality than they are about quantity. The nori with the best thickness, texture, toughness, taste, and absence of fouling organisms is worth several times the value of poor quality material,

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and the highly labor-intensive practice is economically more favorable if directed toward high quality rather than high yield. 3 Laminaria CULTURE IN THE PEOPLE’S REPUBLIC OF CHINA In many parts of China, the inhabitants are subject to chronic goiter, a disease caused by iodine deficiency. The consumption of brown seaweeds rich in iodine is a prophylactic measure to prevent that disease, and the small kelp, Laminaria Japonica, therefore is an important item in the Chinese diet. As its name implies, Laminaria japonica is indigenous to the coldwater environment of Hokkaido, the northern island of Japan, from which some 3000 ton/yr were formerly exported to China. Now it is grown in over 18,000 ha of China’s coastal waters, and in 1979 more than 275,000 dry tons were produced that were worth about $300 million (U.S.). This annual rate of production has far exceeded the local demand for direct use of the seaweed as food. Part of the Chinese crop is now exported back to Japan, where production has declined, and part is processed in China for its hydrocolloid, alginic acid that is used in the food, medical, and other industries. C.K.Tseng (Ref. 5) has reported that Laminaria yields range from about 10 to 20 dry ton/ha/yr. Data from Ref. 4, 275,000 dry tons grown in the kelp year 1978–1979 over 18,000 ha, show an average of 15 dry ton/ha/yr. One of the 15 kelp nurseries in northern China observed by the author consisted of two large greenhouses (5200 m2) containing shallow tanks through which fertilized, refrigerated (5° to 8°C) seawater is circulated. Roughly one-half million gal/day pass through each greenhouse; three-quarters of that amount is recirculated and one-quarter is discarded and replaced. As the seawater passes through the chiller, it is enriched with 4 mg/L nitrate-nitrogen and 2 mg/L phosphate-phosphorus. The greenhouse glass is painted white to permit a maximum solar intensity of no more than 4000 lux. In the spring, the shallow (10-cm deep) tanks in each nursery are filled with 10,000 wooden frames, each roughly 10×60 cm; 40 m3 of rough, 0.5-cmdiameter string are wound around the frames. Mature sporophyte plants of Laminaria are briefly sun dried to stimulate the release of zoospores and are then spread over the wooden frames, which are laid out flat in the nursery tanks. The zoospores are shed from the sporophyte plants and attach to the string frames (spore curtains) within two hours. There the complex life cycle of the Laminaria is completed. The spores develop into microscopic male and female gametophytes (the sexual form of the alga), which quickly mature to produce sperm and eggs, the motile sperm swims to and fertilizes the egg which germinates to produce the sporeling that eventually grows into the large mature, asexual sporophyte—the familiar, obvious seaweed plant.

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All of these stages in the life cycle, from the shedding of the zoospores to the development of the young sporelings, take place in the nursery between June and October. When the outside water temperature falls below 20°C, in mid to late October in Tsingtao but in late September to early October in the more northern Dalien area, the spore curtains are taken off their wooden frames and moved to the ocean, where they are suspended between parallel rows of large buoyed and moored ropes. At this point, the sporelings are 2 to 4 cm long, and there are some 50,000 of them per 50-m spore curtain. When they are small, the sporelings are tended daily. Each spore curtain is lifted from the water, the sediment and attached plants and ani mals are meticulously brushed from each plant, and the entire curtain is immersed into a tub of concentrated liquid fertilizer. When they reach the size of about 10 cm, after 25 to 30 days in the ocean, the entire young crop is harvested, manually stripped off the strings to which they are attached. Bundles of four sporelings are inserted into the weave of larger, 5-cm-diameter, coarse, loosely woven ropes that are again tied across the parallel suspending lines. The bundles remain in these ropes until they are harvested over a six-week period beginning in early June. The plants are no longer individually tended after they are transplanted, but the crop is usually fertilized. Formerly, this was done by attaching to the ropes ceramic containers of fertilizer through which the nutrients could diffuse slowly. Now liquid fertilizer is sprayed daily over the kelp beds. In Tsingtao, where the growing season is 230 days, the kelp reach a length of about 3 m at the time of harvest. Yields average 12 dry ton/acre/yr. In the colder Dalien region, the season is perhaps one month longer. The kelp plants there reach a length that may exceed 5 m, and yields of 20 dry ton/acre/yr are reported. The mature kelp plants are harvested in the late spring by manually hauling the lines with plants attached into a fleet of rowboats each manned by three to four workers. 4. Eucheuma CULTURE IN THE PHILIPPINES Eucheuma is a multiple-branched, fleshy red alga that is utilized for its polysaccharide, carrageenin. Originally harvested from wild stocks in Southeast Asia, such supplies were cut off by political upheavals in the 1950s, which led to the development of cultivation methods for the species by the joint efforts of Marine Colloids Inc. (Rockland, Maine), M.S.Doty (University of Hawaii), and the Philippine Bureau of Fisheries and Aquatic Resources. Unlike Porphyra and Laminaria culture, which require tending throughout all stages of their complex life cycles, Eucheuma is grown purely vegetatively by “planting” fragments of the fleshy thallus, allowing them to increase in size, and simply breaking or cutting off the new growth. Initially, the Eucheuma was grown on nets closely resembling those used for Porphyra farming in Japan. These nets

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also are suspended off the bottom and parallel to the water surface by tying them to bamboo stakes. Eucheuma fragments are tied to the nylon mesh intersections. Typically a family Eucheuma farm consists of four modules of 200 nets covering an area of about 2500 m2; the total farm occupies 1 ha (Ref. 7). More recently the net system has been replaced by the use of monolines, 10-m lengths of nylon monofilament staked 0.5 m apart. Eucheuma propagules are tied every 2.5 m along the line. The monoline method provides easier access to the plants and accommodates as many as 100,000 plants per hectare (Ref. 8). Like Porphyra culture, Eucheuma farming is a highly labor-intensive operation, with constant tending of the plants, manual removal of epiphytes and predators, mending the nets and repairing the moorings, and harvesting the plants as they grow (Ref. 9). Siting of the farm is also critical because the alga requires a vigorous exchange of seawater for rapid growth. Thus favored sites are highenergy areas such as behind fringing reefs, but the surf should not be so violent as to break off the seaweed from the nets or otherwise damage the operations. Two species of Eucheuma, E. cottonii and E. spinosum, are farmed in the Philippines. These contain, respectively, the different chemical isomers kappa and iota carrageenins, which have different gelling properties and hence different commercial applications. Productions increased from a few hundred dry metric ton during the 1960s to a peak of 6590 ton in 1974. At that time nearly half the harvest remained unsold, the price dropped almost tenfold, and many farmers dropped out of the market. Since then there has been gradual recovery of the industry, with about 400 E. spinosum and 600 E. cottonii farms in operation in 1977 producing more than 4000 ton of dried seaweed. 5 Gracilaria CULTURE IN TAIWAN Growing the red seaweed Gracilaria in southern Taiwan was first attempted in 1962, using ponds that were originally constructed for fish culture. The Graeilaria is used locally or, after preliminary processing, is shipped to Japan for the extraction of agar. Although Gracilaria normally grows attached to rocks or other substrata and undergoes the complex alternating life cycle between sexual and asexual reproduction that is typical of red algae, certain species may grow unattached, in a drifting mode, on the bottoms of shallow ponds and estuaries. Such plants are usually sterile and grown entirely vegetatively, larger clumps breaking up into smaller fragments by the action of waves, current, and other forms of natural turbulence. The milkfish ponds in which Gracilaria is now grown in Taiwan are usually rectangular, 1 to 10 hectares in area, and about 1 m deep when filled to capacity. The pond bottoms are hard, sandy loam, since a soft mud bottom is undesirable for both growth and harvesting. The ponds are located adjacent to estuaries so that they may be filled and drained by tidal exchange, assisted as needed by

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pumping. Water exchange is required to regulate salinity and to provide a new supply of nutrients from the normally enriched estuarine waters. Additional enrichment of the ponds with broadcast inorganic fertilizers or fermented pig manure is carried out irregularly between water exchanges; the farmer judges the need by the clarity of the water. The best growth of the seaweed occurs in the temperature range of 20° to 25° C. Growth stops below about 12°C, but the plants can tolerate temperatures as low as 8°C. In southern Taiwan, where virtually all of the Gracilaria is grown, the normal water temperature range in the ponds is from about 10°C in winter to about 30°C in the summer. Pond depth is carefully regulated seasonally to control both temperature and the intensity of sunlight that penetrates to the seaweed on the pond bottom. The ponds are 60 to 80 cm deep in the summer and 30 cm deep in the winter. Several species of Gracilaria are cultured in Taiwan, often together in the same pond. The most popular appears to be that identified by the government biologists as G. confervoides. Cuttings or torn fragments of the seaweed, purchased from other farmers, are used for seed stock and are introduced to a new farm at a density of 3 to 5 kg wet weight/m2 . The plants are evenly spread over the pond bottom and grow there vegetatively throughout the year. When the population has roughly doubled in density and biomass, half the crop is harvested by a crew of 10 to 20 women; half rake the seaweed into rows on the pond bottom, and the other half dip the plants out of the water into large bamboo baskets on wooden barges. The remainder of the crop is then spread evenly over the pond bottom. The netted seaweed is shaken in the water to remove sediments, epiphytic diatoms, snails, and other animals that live in the plants. They are then spread out on flat earthen or concrete surfaces to dry and are turned once to hasten the drying process. There are usually seven to eight harvests per year, each of 1 to 3 dry ton/ha, primarily between June and December. Little growth occurs during the late winter and very early spring, and the stocks are sometimes held in deep, protected areas during the coldest part of the winter, using the covered shelters originally designed for milkfish culture. Some farmers harvest smaller crops more frequently during the growing season (every 10 days or so), but annual yields are approximately the same whatever the harvest routine. Yields range from 10 to 20 dry ton/ha/yr and average about 14 ton/ha/yr. There is some problem with epiphytes, principally the filamentous green algae Enteromorpha and Chaetomorpha, growing on the Graoilaria. This is controlled by stocking 500 to 1000 herbivorous milkfish/ha (150-g or larger fish) that graze on the epiphytic algae. After the seaweeds are thoroughly cleaned of the epiphytes, however, the milkfish will turn to the Gracilaria itself for nourishment, so the fish must be taken out after they have performed their cleaning service.

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The other chronic problem in Gracilaria culture is maintaining the even distribution of the culture on the bottom. Ponds are usually oriented with their long axis perpendicular to the prevailing wind, and there is often a windbreak of trees or other vegetation planted on the upwind side of the pond. Despite this, strong winds will often pile up the loose plants along the downwind side of the pond, and considerable labor is required to spread them out evenly again. Additional income is often obtained by the Graeilaria farmer through the simultaneous rearing of shrimp or crabs with the seaweeds. These animals obtain their nutrition from animals that occur naturally in the ponds. Some of the food organisms grow as epizoa on the Gracilaria, so the secondary crop also cleans the seaweeds. The farmers may realize up to 10% to 20% of the pond’s income from such ancillary crops. 6 PRODUCTION AND ECONOMICS Parker (Ref. 9) estimated the annual production of Eucheuma at a pilot farm on Taapan Island, Philippines, from six months of harvest data during 1971–1972, at 13 dry metric ton/ha/yr. The annual depreciation cost of equipment and supplies, primarily nets, was $364 (U.S.) for a four-module, one-hectare farm which Doty (Ref. 7) states could be managed by one “enterprising family.” Labor costs are not included in Parker’s economic analysis of this cottage industry, nor is the size of Doty’s enterprising family. If one estimates, from other information in Parker’s report, an annual minimum wage for agricultural labor of $200 (U.S.), total cost of operation of a one-hectare Eucheuma farm employing four laborers would be $1164, making the cost of production $89/dry ton. Shang (Ref. 10) gives a somewhat more detailed economic analysis of a onehectare Gracilaria farm in Taiwan that does include the cost of labor— $1382/yr for a crop of 10 dry metric ton, or $138/ton. Parker’s estimate did not include such costs as seed stock, taxes, or land leasing, and his extrapolated yield for a pilot project was perhaps somewhat generous for mean commercial production. Shang’s yield data, on the other hand, were somewhat lower than those reported to the present author during a visit to the Taiwanese Graeilaria farms in 1978 (10 to 20 metric ton, averaging about 14 metric ton/ha/yr). Thus, differences between costs and yields of the two practices are probably not significant—about $100 (U.S.)/dry ton. If Eucheuma. like Gracilaria. contains about 60% of its dry weight as volatile solids (Ref. 11) and both yield about 6 ft3 of methane/pound of volatile solids (0. 4 1/g) (Ref. 3) from their anaerobic digestion, the cost of methane/1000 ft from seaweeds produced by the two practices, not including transportation or processing of the seaweed to methane, would be $12.63. While the cost is not competitive with the current well-head price of natural gas, it is surprisingly reasonable for such a crude and primitive industry.

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The low cost of land, labor, and other factors make the above examples economically irrelevant to potential U.S. practices, but the yields of 10 to 20 dry ton/ha/yr for three of the four cases described, all simple, nonintensive farming practices, are encouraging. More sophisticated cultivation methods, including genetic improvement of stocks, better nutrition, and mechanization of seeding and harvesting practices can be expected to increase yields several times. Smallscale, experimental yields of Gracilaria using highly intensive culture methods have already exceeded the equivalent of 100 dry ton/ha/yr (Ref. 2). Modern cultivation technology in agriculture has evolved slowly, over centuries. Yet current yields from farming the land average no more than about twice those now achieved from the seaweed culture methods that have been in practice for no more than a few decades (Table 1). Farming the sea, while in its early infancy, thus shows sufficient promise to merit further investigation. By the time a world shortage in fossil fuel has developed, marine biomass could, with its available resource base, make up much or all of the deficiency with only a modest annual investment in research and development effort in the intervening years. Table 1: Annual yields of agricultural crops (total plant) (from Ref. 2) and of seaweeds (this report) crop Temperate Zone Rye grass Kale Sorghum Maize

Potato Sugar beet Wheat (spring) Subtropical Zone Alfalfa Sorghum Bermuda grass Sugar beet Potato

country

yield (metric ton/ha)

U.K. U.K. U.S. (Illinois) U.K. Canada (Ontario) Japan U.S. (Iowa) U.S. (Kentucky) U.K. Netherlands U.K. U.S. (Washington) U.S. (Washington)

23 21 16 17 19 26 16 22 23 22 23 32 32

U.S. (California) U.S. (California) U.S. (Georgia) U.S. (California) U.S. (California)

33 47 27 42 22

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crop

country

yield (metric ton/ha)

Wheat Rice Maize

Mexico U.S. (California) Egypt U.S. (California)

18 22 29 26

Tropical Zone Napier grass

El Salvador Puerto Rico Sugar cane Hawaii Oil palm Malaysia Sugar beet Hawaii (2 crops) Cassava Tanzania Malaysia Maize Thailand Peru Rice Peru Mean (all crops, all countries) Median (all crops, all countries) Seaweeds Laminaria China (Ref. 4) Eucheuma Philippines (Ref. 9) Gracilaria Taiwan (Ref. 10) (Ryther, personal observation)

85 85 64 40 31 31 38 16 26 22 31 26 15 13 10 14

REFERENCES 1. 2. 3.

4. 5. 6. 7.

Greely, R.S. ‘Land and freshwater farming’, Proc. Conf. on Capturing the Sun through Bioconversion, Wash. Center for Metropol. Stud., vol. 197, 1976. Lapointe, B.E. and Ryther, J.H. ‘Some aspects of the growth and yield of Gracilaria tikvahiae in culture’ , Aquaculture, vol. 15, 1978. Fannin, K.F., Srivastava, V.J. and Chynoweth, D.P. ‘Unconventional anaerobic digester designs for improving methane yields from sea kelp’, Symp. Papers Energy from Biomass and Wastes IV, Lake Buena Vista, Fla., January 25–29, 1982. Tseng, C.K. ‘Commercial cultivation’, Chap. 20 in The Biology of Seaweeds, C.S. Lobban and M.J. Wynne, eds., Bot. Monogr. 17., U. Cal. Press, 1981. Bardach, J.E., Ryther, J.H. and McLarney, W.O. ‘Aquaculture’, Wiley-Interscience, 1972. Tseng, C.K. Personal communication. Doty, M.S. ‘Farming the red seaweed, Eucheuma, for carrageenins’, Micronesia, vol. 9, 1973.

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8. 9. 10. 11.

Hansen, J.E., Packard, J.E. and Doyle, W.T. ‘Mariculture of red seaweeds’, Cal. Sea Grant College Prog. Publ. T-CSGCP-002, 1981. Parker, H.S. ‘The culture of the red algae genus Eucheuma in the Philippines’, Aquaculture, vol. 3, 1974. Shang, Y.C. ‘Economic aspects of Gracilaria culture in Taiwan’, Aquaculture, vol. 8, 1976. Hanisak, M.D. ‘Recycling the residues from anaerobic digesters as a nutrient source for seaweed growth’, Bot. Mar., vol. 24, 1981.

THE INTEGRATION OF BIOGAS PRODUCTION WITH WASTEWATER TREATMENT T.D.HAYES, D.P.CHYNOWETH, K.R.REDDY, and B.SCHWEGLER* *Gas Research Institute, Chicago, Illinois

1 INTRODUCTION For more than two decades, aquaculture systems employing plants grown on sewage have been proposed as alternatives to conventional wastewater treatment processes. In addition to removing pollutants, some of these systems can provide biomass in substantial amounts for conversion to methane. This concept requires the integration of at least three technologies: (1) anaerobic digestion; (2) biomass management for achieving maximum yields; and (3) aquaculture treatment of wastewater to meet federal, state, and local standards. Previous investigations of hyacinth sewage treatment have mainly emphasized removal of BOD5 and suspended solids (secondary treatment) and reduction of phosphorus and nitrogen (tertiary treatment) (Refs. 1–5). Hyacinth treatment of sewage is usually conducted in shallow ponds or channels less than 1 m deep. Pilot-scale hyacinth treatment systems have typically achieved removals of 75% to 95% of BOD5 and TSS under sewage loadings of 20 to 150 kg/ha day (Refs. 4 , 5), but hyacinths in these studies, however, were not managed and harvested to maximize biomass production. This paper describes the status of research in progress to develop a system that combines methane production with a wastewater treatment concept that produces a high-yielding crop of water hyacinths from sewage. This integrated concept has the potential to provide a stable source of low-cost methane while offering the community a cost-effective process for wastewater treatment and water reuse. 2 APPROACH The general approach used by this project has been to concentrate research on an integrated field test facility at Walt Disney World, near Orlando, Fla., while relying on systems analyses and engineering trade-offs to direct R&D toward process performance goals that achieve cost-competitive methane. The system concept, depicted in Fig. 1, consists mainly of water hyacinth channels for

REVIEW OF BIOMASS CONVERSION TECHNOLOGY RESEARCH 159

secondary and tertiary treatment of wastewater, hyacinth harvesting and processing equipment, and an anaerobic upflow solids reactor (USR). As effluent from the primary settler is passed through the water hyacinth channel, the hyacinth roots and bacteria coating the root mass remove organic pollutants (BOD5) and nutrients such as nitrogen and phosphorus. Hyacinths growing on the wastewater are periodically harvested, combined with sewage sludge from the primary settler, and introduced to the anaerobic digester. As the feed passes through the digester, bacteria convert complex organic matter to biogas, a mixture of methane (60% to 65%) and carbon dioxide, which can be upgraded to a product gas (97% methane) suitable for introduction into the pipeline. In developing the biomass wastewater treatment energy conversion scheme, the hyacinth project has emphasized the three technical objectives, described in Fig. 2, which are aimed at reducing the cost of methane produced from a blend of hyacinths and sludge. These objectives are covered under the work of three research organizations participating in the project: the Institute of Food and Agricultural Sciences (IFAS) of the University of Florida, the Institute of Gas Technology (IGT), and several subsidiary companies of Walt Disney Productions. Much of the cost analysis and systems evaluation support is provided by Black and Veatch, an architectural and engineering (A&E) firm. The current sponsor is the Gas Research Institute (GRI). Previous sponsors have included United Gas Pipeline, the U.S. Environmental Protection Agency, and the U.S. Department of Energy. 3 A&E EVALUATION In 1982, a preliminary economic feasibility analysis was conducted by Black and Veatch on a conceptual secondary treatment hyacinth system employing conventional anaerobic digestion and gas upgrading to pipeline quality. The results indicated that a significant amount of methane could be generated with this concept (methane production from a 50-million-gal/day facility, for example, was projected at about 640 GJ/day) and that methane could be produced from such a facility at a cost of $2.35 to $4.50/GJ at plant sizes of 50 to 10 million gal/day corresponding to city populations of 500,000 and 100,000 people (Ref. 6). This cost range was based on the assumptions that through research: hyacinth yields of 110 dry metric ton/ha yr could be achieved, methane yields of 0.28 m3/kg volatile solids (VS) added could be maintained, and hyacinth channels could be designed to handle sewage loadings up to 210 kg/ha day while still meeting secondary effluent standards for BOD and TSS removal. These assumptions became the implicit R&D goals of the project as summarized in Fig. 3.

160 ENERGY APPLICATIONS OF BIOMASS

4 WASTEWATER TREATMENT Hyacinth wastewater treatment studies and hyacinth productivity research were conducted in five 0.1-ha hyacinth test channels, each with dimensions of 8.8 m×110 m×0.35 m deep, constructed of reinforced concrete blocks and lined with 20-mil PVC sheet. Previous studies on these channels showed that secondary effluent standards could be achieved under low sewage feed rates (BOD5 loadings) typically applied to aerobic ponds without hyacinths, amounting to about 70 to 90 kg BOD5/ha day. In 1983 and 1984, four channels were fed with primary sewage (obtained from the Walt Disney World wastewater treatment settling basins) at loadings of 55, 110, 220, and 440 kg BOD5/ha day corresponding to hydraulic retention times of 24, 12, 6, and 3 days, respectively. The technical objective of this study was to measure channel BOD5 and TSS removal efficiencies under high loadings that would stress the system’s treatment capabilities. Wastewater treatment data collected from the channels included influent and effluent BOD5, suspended solids (SS), pH, temperature, dissolved oxygen, and various forms of nitrogen and phosphorous. Results from this study over a 9-month test period (from November 1983 through July 1984) indicate that a single hyacinth channel is capable of removing 72% to 90% of the BOD5 (81% average) and 70% to 90% of the SS (80% average) in wastewater at loading rates as high as 440 kg BOD,-/ha day [(3 day hydraulic retention time (HRT)] . Average steady-state data for BOD5 and SS removals are presented in Table 1. Average effluent BOD5 and SS concentrations from the hyacinth channels met federal standards for secondary treatment at loadings up to 220 kg BOD5/ha day during all but two of the coldest months of the test period; during that time, secondary effluent standards were met at the 110 kg BOD5/ha day loading rate. A statistical analysis of influent and effluent data as well as channel profile measurements taken over the past four years is in progress to allow more accurate correlations between treatment performance and hyacinth channel operating conditions (e.g., loadings, temperature, retention time, hyacinth density). Preliminary analysis of the performance data for the four channels suggests that treatment efficiencies may be only marginally improved by extending retention time and that it may be costeffective to use staging of the unit processes to achieve a high compounded removal efficiency at an equivalent retention time as opposed to increasing the hydraulic retention time of a single-stage channel. Experiments with a highthroughput, two-stage hyacinth system are under way.

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Table 1: Hyacinth wastewater treatment performance summary sewage loading (kg/ HRT (days) ha day) BOD5

average percentage of removals*

SS

55 110 220 440

24 89 71 12 87 72 6 84 83 3 81 80 *Based on a 9-month operation from November 1983 through July 1984 and an influent BOD5 concentration of 200 to 260 mg/L.

5 WATER HYACINTH PRODUCTION Maximum growth yields of water hyacinth are desirable in the sewage channels because rapid growth is associated with efficient wastewater treatment and results in larger quantities of biomass available for conversion to methane. Numerous factors can influence hyacinth yields, and the most important are temperature concentration of CO2, sunlight capture, nutrient availability, and planting density (or current rate). Of these, the most controllable parameters studied thus far include, nutrient availability and planting density. Hyacinth productivity experiments have been conducted in the hyacinth channels (0.1 ha) and in small field test units (1.7 m2). Measurement of biomass yield in each channel was performed using 10 m2 Vexar™ mesh baskets placed about 18.3 m apart. The methods and results of this work are described in more detail in Ref. 7. The large channels were used to observe the effects of sewage loading, channel retention time, seasonal temperatures, and sewage treatment efficiency on hyacinth yield. The small experimental systems were used to optimize hyacinth production by controlling parameters such as nutrient availability, plant density, and aeration. Hyacinth productivity under unoptimized conditions ranged from 45 to 58 kg/ ha yr. The use of a harvesting schedule that provides an optimum planting density of 36 kg/m2, however, has increased hyacinth yields to 60 to 70 dry metric ton/ha yr. Preliminary tests in small field units suggest that still further yield increases of 30% to 50% are possible through the discretionary use of aeration. 6 ANAEROBIC DIGESTION PROCESS DEVELOPMENT Anaerobic digestion was selected for the processing of mixtures of water hyacinth and primary sludge since it produces methane as the principal product (60% to 65%) and since the process is compatible with the conversion of

162 ENERGY APPLICATIONS OF BIOMASS

feedstocks with a high water content. The technical objective of this R&D effort is to develop a data base for the design and operation of an optimized system for biogasificatlon of the hyacinth and sludge, and to integrate this process with the hyacinth wastewater treatment facility. 6.1 Laboratory Studies A number of experiments were conducted to evaluate the performance of a continuous stirred tank reactor (CSTR) and an upflow solids reactor (USR) designed to promote long solids retention times under high hydraulic load-ings. A schematic of the USR is shown in the diagram of the digester of Fig. 1. This reactor employs little or no mixing. Influent is fed at the bottom of the tank, and effluent is removed near the top of the liquid contents. The laboratory USR and CSTR units were fed with a 3:1 blend of hyacinth and primary sludge at loadings between 1.6 and 6 .4 kg VS/m3 day (corresponding to HRTs between 31 and 8 days). Steady-state data plotted in Fig. 4 show that in side-by-side tests, the USR consistently achieved 10% to 25% greater methane yields over a wide range of HRTs. The superior performance of the USR was attributed to the reactor’s ability to increase the solids and microorganism residence time significantly above the HRT through sedimentation of particulate solids. Thus, the USR reactor achieved greater methane production with substantially less mixing. These results provided the basis for the selection of the USR design for testing at the experimental test unit (ETU) scale. 6.2 Biogasification Experimental Test Unit In 1983, a 4.5-m3 (160 ft3) upflow solids ETU was designed and constructed, located beside the five existing hyacinth channels at Walt Disney World. The technical objective of the first phase of the ETU study was to evaluate reactor performance, scale-up, and materials handling parameters at several different loadings of hyacinth/sludge blends. The ETU facility is capable of processing up to 910 kg or 1 ton of a wet hyacinth/sludge feed bl’end (5% total solids) each day. The ETU is sized to ensure that the demand for biomass feedstock does not exceed the availability of hyacinth from the channels during the coldest months of the winter when hyacinth pro-ductivity is at its lowest. Major components of the facility include two feed tanks for short-term storage of sludge and chopped hyacinth, a feed blend tank, an upflow solids reactor (4.5 m3), an effluent storage tank, and gas compression and storage. The ETU was initially tested as an upflow solids reactor test facility, though it is designed to allow flexibility in simulating and testing other reactor designs as well. The current testing phase of the ETU is expected to provide:

REVIEW OF BIOMASS CONVERSION TECHNOLOGY RESEARCH 163

• Verification of laboratory observations under actual field conditions and determination of the effects of scale-up on process performance • Flexibility in testing feed-processing, solids harvesting, and digestion configuration at a scale sufficient to delineate the best overall process design • Field-scale evaluation of process control problems • Information on maintenance and operating requirements Following shakedown and successful startup in 1984, the ETU was fed a 2:1 blend of chopped hyacinth and sludge at an initial loading of 1.6 kg VS/m3 day, which was gradually increased to the current loading of 3.2 kg VS/m3 day. The test plan for the ETU includes operation of this reactor at several loadings between 1.6 and 6.0 kg/m3 day with 2:1 and 1:1 blends of hyacinth and sludge. These blend ratios were selected because they bracket the composition of solids mixtures expected from a secondary hyacinth wastewater treatment plant. At each feed condition, the steady-state performance of the ETU is evaluated according to the parameters listed in Table 2. Fed with a 2:1 blend at a loading of 3.2 kg/m3 day (16-day HRT), the ETU achieved a methane yield of about 0.29 m3/kg VS added, which is approximately 60% of theoretical, and about 15% higher than the methane yields obtained from a parallel bench-scale CSTR control. This ETU methane yield also compares favorably with the performance observed with a bench-scale USR unit that produced 0.28 m3 methane/kg added on the same 2:1 feedstock mix. Table 2: ETU evaluation parameters performance parameters

engineering parameters

Methane yield Methane production rate Gas composition Volatile fatty acids Temperature pH Alkalinity Organic matter reduction

Materials balance Solids Carbon Nitrogen Phosphorus Energy balance Materials handling Scale-up of laboratory performance

Results from the second ETU steady-state condition illustrate the effect of feed blend composition on methane yield. When feed conditions were shifted from a 2:1 to a 1:1 blend of hyacinth and sludge at a constant HRT (16 days) and loading (3.2 kg/m3 day), the methane yield was increased from 0.29 to 0.39 m3/ kg VS added. These results are consistent with previous batch reactor tests which indicated that the ultimate methane yield of hyacinth (0.30 to 0.37 m3/kg VS added) is lower than that of sewage sludge (0.40 to 0.45 m3/kg VS added). A higher sludge content in the ETU feedstock mix should therefore result in higher

164 ENERGY APPLICATIONS OF BIOMASS

methane yields. Although the month-to-month hyacinth productivity of the channels can greatly affect the carbon feed rate to the reactor, fluctuations in methane output can be dampened by the higher methane yields achieved from the lower hyacinth/sludge ratio. It is evident from laboratory results (Ref. 8) that the establishment of an extended solids retention time (SRT) is essential to the efficient breakdown of the water hyacinth fraction of the feedstock. 7 FUTURE DIRECTIONS During 1985, experiments will continue to test the effectiveness of process improvements and to resolve key technical uncertainties that can be addressed at this scale. Testing of the ETU on 1:1 and 2:1 hyacinth/sludge mixtures will determine the effects of scale-up on upflow solids reactor performance and will provide some useful information on solids handling and management that can be applied to future system designs. In addition, aeration and nutrient management methods used to maximize hyacinth productivity in small field units will be tested in the larger hyacinth channels. Other channel operating techniques employing two-stage processing, frost control via intermittent spraying, and harvesting schedules that optimize hyacinth densities will also be investigated to achieve further improvements in hyacinth productivity and wastewater treatment. Beyond the current R&D effort, the development of a nutrient film technique aquaculture system that utilizes cold-tolerant plants would extend the integrated methane generation concept to a wider portion of the United States. Equally important, the development of a reactor system capable of converting municipal solid wastes (MSW) added to aquaculture biomass/sludge blends would allow a municipality the option of producing 5 to 6 times the methane expected from a hyacinth/sludge digestion operation. For a city of 500,000 residents served by a 1.9×105 m3/day (so-million-gal/day) plant, methane production could be potentially increased from 640 to over 3700 GJ/day (0.6 to 3.5×106 ft3/day) if available MSW were added to the feed mix. This increased methane output can amount to 15%–20% of the residential natural gas demand. These and other areas are included in the future R&D plans for this project to further enhance the prospects for community acceptance and commercial success of methane-fromwaste technology. 8 CONCLUSION Results to date indicate that the hyacinth project has made good progress toward goals that can lead to the production of cost-competitive methane from a hyacinth wastewater treatment system. This project is complementary to pilot tests conducted by a growing number of municipalities to evaluate hyacinth

REVIEW OF BIOMASS CONVERSION TECHNOLOGY RESEARCH 165

aquaculture for use in wastewater renovation. By the end of 1985, an information base from the GRI project should be available to support a decision of whether methane generation from a hyacinth facility is sufficiently attractive for municipalities and gas companies to pursue at a commercial scale. If the economics appear promising, construction of a full-scale plant could begin in the late 1980s. GRI will actively seek the participation of municipal and county governments, gas companies, waste disposers, and developers in this research and development project as it proceeds. It is expected that this research will ultimately benefit the gas consumer and the public by providing a low-cost supplemental source of pipeline-quality gas while offering a cost-effective wastewater treatment alternative. REFERENCES 1.

2.

3. 4.

5. 6.

7. 8.

9.

Tchobanoglous, G., Stowell, R., Ludwig, R., Colt, J. and Knight, A. ‘The use of aquatic plants and animals for the treatment of waste-water: an overview’, in Aquaculture Systems for Wastewater Treatment/MCD 67, available from General Services Administration, Denver, CO, Document No. EPA430/9–80–006, p. 35, 1979. Reed, S., Bastian, S. and Jewell, W. ‘Engineering assessment of aquaculture systems for wastewater treatment: an overview’, in Aquaculture Systems for Wastewater Treatment/MCD-68, available from General Services Administration, Denver, CO, Document No. EPA 430/9–80–007, p. 1, 1980. Wolverton, B.C. and McDonald, R. ‘Upgrading facultative wastewater lagoons with vascular aquatic plants’, Jour. Water Poll. Control Fed., vol. 61, 305, 1979. Kruzic, A.P. ‘Water hyacinth wastewater treatment system at Walt Disney World’, in Aquaculture Systems for Wastewater Treatment/MCD 67, available from General Services Administration, Denver, CO, Document No. EPA 430/9–80–006, p. 35, 1979. Dinges, R. ‘Upgrading stabilization pond effluents by water hyacinth culture’, Jour. Water Poll. Control Fed., vol. 50, 833, 1978. Smith, M.D., Filard, R.E., Curran, G.M., and Miller, G.R. ‘Economics of methane from hyacinth wastewater treatment systems’, Proceedings of the International Gas Research Conference, Government Institutes, Inc., Rockville, MD, in press, 1984. Reddy, K.R. ‘Water hyacinth biomass production in Florida’, Biomass, vol. 6, 167, 1984. Chynoweth, D.P. et al. ‘Biogasification of water hyacinth and primary sludge’, Proceedings of the International Gas Research Conference, Government Institutes, Inc., Rockville, MD, in press, 1984. ‘Wastewater Engineering’, Metcalf & Eddy, Inc., McGraw-Hill, 1972.

166 ENERGY APPLICATIONS OF BIOMASS

Fig. 1. Schematic of the integrated hyacinth wastewater treatment methane generation concept

Fig. 2. Project objectives

REVIEW OF BIOMASS CONVERSION TECHNOLOGY RESEARCH 167

Fig. 3. Project goals based on A&E analysis

168 ENERGY APPLICATIONS OF BIOMASS

Fig. 4. Methane yield performance vs. hydraulic retention time for bench-scale USR and CSTR units operated on a 3:1 hyacinth/sludge feed blend

REVIEW OF BIOMASS CONVERSION TECHNOLOGY RESEARCH D.L.KLASS* *Institute of Gas Technology, Chicago, Illinois

Numerous conversion processes can be used to produce energy or gaseous, liquid, and solid fuels from biomass and wastes. In addition, chemicals can be produced by a wide range of processing techniques. Table 1 is a summary of the major feedstock, process, and product variables usually considered to develop a synfuel-from-biomass process. There are many interacting parameters and many possible feedstock-process-product combinations, but from a practical standpoint, not all are feasible. For example, the separation of the small amounts of metals present in biomass and the direct combustion of high-moisture content algae are technically possible, but energetically unfavorable. Most bioconversion processes can be classified by process type— combustion; thermochemical and biological gasification; and natural, direct and indirect thermal, and biological liquefaction. Research continues on improving all of these processes, although in varying degrees because some are already well-established commercial technologies. 1 COMBUSTION The two major direct biomass and waste combustion technologies contributing to primary energy in North America are wood combustion for residential, industrial, and utility applications, and combustion of municipal solid wastes (MSW) for simultaneous waste disposal, energy production, and recovery of recyclable materials such as ferrous metals. Table 1: Summary of feeds, processes, and products feed stock

primary conversion process

Land-based biomass Trees

Separation Combustion

primary energy products

Thermal Energy

Steam

170 ENERGY APPLICATIONS OF BIOMASS

feed stock

primary conversion process

Plants Grasses

Pyrolysis Hydrogenation Anaerobic Solid fuels fermentation Aerobic fermentation Biophotolysis Partial oxidation Steam Gaseous reforming fuels Chemical hydrolysis Enzyme hydrolysis Other chemical conversions Natural processes

Water-based biomass Single-cell algae Multicell algae Water plants

Organic wastes Municipal Industrial Agricultural Forestry

primary energy products

Electric Char Combustibles

Methane (SNG) Hydrogen Low-Btu gas Medium-Btu gas Light hydrocarbons

Methanol Liquid fuels

Ethanol Higher hydrocarbons Oils

Chemicals

1.1 Wood Fuels Residential firewood usage is greatest in the urbanized areas of the Northeast and North Central States; according to a recent study, 9% to 11% of U.S. space heating input is from firewood. For example, during the 1978– 1979 heating season, about 34.7×106 cords of wood were burned in residences. Wood now accounts for 33.8% of all residential heating in Vermont, and more than 3.3×10 cords were burned in New York State during the 1980– 1981 heating season. At an energy equivalency of 3.9 bbl oil/cord of wood, this consumption level corresponds to the heating value of 12.9 million BOE. From the New York State study we concluded that wood is a major heat source in 707,000, or 18%, of the state’s households, excluding metropolitan New York City and Westchester County, and that the direct and indirect economic impacts of solid fuel use are of

CONVERSION OF LIGNOCELLULOSIC BIOMASS TO ETHANOL 171

tremendous importance to the New York citizens. Estimates indicate the sales of wood heating units are about 1–1.5 mlllion/yr in the United States; this correlates with increased fuel’-wood consumption. Greater residential fuelwood consumption has increased the accompanying pollution, resulting in legislation to control fuelwood pollution. A number of the resulting ordinances and laws are quite severe. For example, new stoves sold in Oregon after 1986 will have to purge particulates and carbon monoxide from the smoke with devices such as dual-combustion chambers or catalytic converters. Aspen, Colo., has an ordinance that allows only one traditional fireplace per new structure, even for apartment buildings. To facilitate future large-scale increases in fuelwood usage for residential space heat, the following parameters must be addressed in detail: fuel availability, form, and cost; certified combustion systems and installation methods; fuel storage; health and safety; and the development of low-cost automated feeding and combustion control systems. Some research work is under way to examine these issues on an integrated basis, but much more must be done to open residential fuelwood markets and attract new users. The use of fuelwood in residences is now too labor-intensive for most areas of the United States. Direct wood combustion is used by only a few utilities for supplemental electric power production. Table 2 lists power plants currently on standby or in operation that use mill residues (bark, sawdust, shavings, slabs, hogged bark, and other mill residues) as fuel. The largest system, the Washington Power Company plant, is used for peaking purposes. The largest wood-chip-fueled power plant is the 50–MW plant in Burlington, Vt., which was placed on-line in June 1984. The 10–to 50–MW, wood-chip-fueled plant to be operated by California Power and Light Corporation in Madera, Calif., is still in the permitting stage, but construction was expected to start in 1984. About 85% to 90% of the total biomass contribution to U.S. primary energy consumption, about 2.6 quads, is derived from wood and wood wastes. The major consumer is the pulp and paper industry, while the electric utility industry currently uses less than 0.1 quad of wood to generate power. Although the technology for power generation in wood-fueled steam-electric plants is well developed, the only economic wood-fueled power plants in the United States are the larger plants. A catch-22 situation results because if a plant is larger than 50 MW, the wood must be transported for distances often greater than 50 to 75 miles, thereby increasing fuel cost. Thus, 50 MW seems to be the maximum size at the present time. Table 2:

172 ENERGY APPLICATIONS OF BIOMASS

Utility power plants using mill residues as fuel location

operator

period

size (MW)

comments

Cowlitz, WA

Cowlitz County Public Utility District

1923–60, 1970s-present

27.5

Dixville, NH

New Hampshire Electric Cooperative, Inc.

—

1.9

Eugene, OR

Eugene Water and Electric Board

1941–80

33.8

Kettle Falls, WA

The Washington Power Co.

Dec. 1983

42.5

1979-present

25–30 from wood

Steam produced now for Weyerhauser Company One of 3 generators (totalling 1.9 MW) on line, but down because of fire Steam-electric plant now down because of reduced demand $82.5 million plant uses 450, 000 ton/yr of wood residues Cofiring of wood and coal

1981-present

—

Lake Superior District, WI

Lake Superior District Power Co. Red Wing, MN North States Power Co.

Cofiring with 20% wood residues, 80$% coal Note: Mill residues defined as bark, sawdust, shavings, slabs, hogged bark, and other mill residues. This tabulation may not include all U.S. utilities that convert mill residues to power, and does not include the plants operating on wood chips.

The Republic of the Philippines is developing a nationwide program of woodfueled, 3-MW power plants, each of which is supplied by a tree plantation of about 2,500 acres of Leucaena. The goal is to have 210-MW total capacity (6% of the total electrical requirement) by 1987; 27 plantations were established by the end of 1981 and 20 additional plants are under construction. A direct combustion technology that may make smaller plants more economical uses pressurized combustion of wood, clean-up of the combustion gas with cyclones to remove particulates, and passage of the gas through a gas turbine (Aerospace Research Corporation). Initial studies with a 375-kW system indicated satisfactory performance and no turbine blade erosion. A 3-MW plant being constructed at Red Boiling Springs, Tenn., to test the system on a larger scale will consume 100 ton/day of green wood, and the power will be sold to TVA.

CONVERSION OF LIGNOCELLULOSIC BIOMASS TO ETHANOL 173

The most recent wood-fueled cogeneration plant to go on-line in the United States, Dow Corning Corp.’s $35-million steam (275,000 Ib/h) electric (22.4 MW) plant in Midland, Mich., reached design operating conditions in March 1983. Company officials have predicted that this plant will reduce Dow’s energy costs at this site by about 25%, or $2 million. 1.2 Municipal Solid Waste Direct energy-producing technologies for MSW are limited to mass burning of raw MSW, usually without shredding or preparation, and combustion of refusederived fuel (RDF) alone or in combination with oil or coal (cofiring) . The question, then, is whether to produce and burn RDF or to mass-burn MSW, that is the question. Despite all of the research that has been done and the commercial projects that have succeeded or failed, this question still cannot be answered with certainty, particularly for electric power production; but mass burning seems to have the edge. In electric utility systems, cofiring RDF has generated a broad range of problems concerned with erosion, corrosion, slag formation, efficiency, and reliability in several but not all cases. Burning MSW or RDF in a dedicated boiler, which cannot be operated at too high a temperature because of slagging and corrosion, produces steam at a lower temperature and pressure than that of a conventional utility. A recent survey of 37 planned and 86 operational or discontinued MSW resource recovery plants showed that about 55% use mass burning; the larger scale systems use waterwall incinerators and the smaller plants use modular units. Table 3 indicates the approximate distributions of design and total capacities for the mass-burning and RDF plants. Six RDF plants have been closed (mainly because of technical difficulties) , but many new plant starts can be expected in the coming years. No mass-burn plants have closed. Massburn methods such as that used at the 1500-ton/day plant at Saugus, Mass., seem to be the most successful. Table 3: Summary of energy-from-MSW plants in United States plant type

number

status

design capacity range (ton/day)

total capacity (ton/day)

Mass burning, waterwall Mass burning, waterwall Mass burning, waterwall Mass burning

9

Operating

240–1600

6,250

15

Negotiation/ Construction Planning

600–3000

24,110

>500

17,060

200–500

NA

15

Numerous Planning

174 ENERGY APPLICATIONS OF BIOMASS

plant type

number

status

design capacity range (ton/day)

total capacity (ton/day)

Mass burning, starved air Mass burning, excess air RDF RDF

28

Operating

20–240

2,912

26

Operating

50–500

6,301

11 9

200–3000 1000–3000

19,500 14,300

RDF

6

Operating Negotiation/ Construction Closed

500–2000

7,400 97,833

Note: Compiled from Argonne National Laboratory reports.

1.3 Dioxin For energy-from-biomass-and-waste combustion processes, the dioxin issue continues to attract extensive media coverage, although human exposure to dioxin has been scientifically linked to only a few health problems. The symmetrical isomer, 2, 3, 7, 8–tetrachlorodibenzo-p-dioxin, referred to by most scientists as dioxin, is apparently one of the most toxic of 75 possible isomers, and has one of the lowest LD50’s of those determined to date. Extensive research is in progress to develop data and information on the toxicity of dioxins as related to human health. The importance of the subject for energy-from-biomass-and-waste technology is that evidence now being accumulated indicates combustion processes fueled with biomass and wastes can form dioxins. In addition to formation as a trace contaminant in the manufacture of the insecticide 2, 4, 5–trichlorophenoxyacetic acid (2, 4, 5–T), which has been banned from most agricultural uses, dioxin is formed on combustion of materials containing chlorinated phenols and its precursors. For example, wood-fueled stoves produce dioxins in the soot because the natural chlorine content of wood, about 14–84 ppm, reacts with the lignins. Dioxins also form in trace amounts in the fly ash and soot from industrial and municipal incinerators supplied with municipal solid wastes. The hazards associated with these emissions are not known with certainty. But presuming some toxicological conditions exist because of the highly toxic nature of dioxins, the problem is clearly not severe because of the broad distribution of biomass- and waste-fed combustion systems. This apparent lack of hazard may be caused by the strong affinity of dioxins for solid adsorbents such as fly ash and soils, and the fact that some biomass combustion equipment is operated above the thermal decomposition temperature of the dioxins, or 750°C. The hazards of dioxins appear to be minimal in biomass and waste combustion

CONVERSION OF LIGNOCELLULOSIC BIOMASS TO ETHANOL 175

systems, but developers of the technology should be aware of the potential emissions and the control methods that can be used. 2 GASIFICATION 2.1 Thermochemical Gasification Research Research on gasification fundamentals and the development of advanced processing concepts for biomass has continued in many areas. Some of the more interesting reports in 1983 include those on development of a predictive model for stratified downdraft gasifiers that should allow estimating useful quantitative behavior of gasifier performance; start-up of an 11.5-in.-ID, steam-oxygen, fluidized-bed gasifier that will permit gasification experiments to be carried out up to 980°C, 500 psig, and 1,000-lb/h feed rates; research on the rapid pyrolysis of biomass using an innovative heat transfer technique that permits 100-ms residence times at temperatures up to 1000°C in a vertical reactor; development of new basic data on the flash pyrolysis of wood in gaseous reactive (H2 and CH4) and unreactive (He) environments at 600°-1000°C and 20–1000 psi; achievement of 90% carbon conversion to 500 Btu/ft3 gas at throughput rates up to 1860 Ib/h ft2 in an entrained, fluidized-bed gasifier having high turbulent mixing zones; and studies with an entrained-flow, cyclonic reactor for biomass that can provide heat-up rates as high as 500,000°C/s at the surface of the biomass. The trend of much of the advanced biomass gasification research in progress is toward rapid heat transfer rates, high reactor temperatures, short residence times, and short cool-down rates, all of which tend to maximize the yields of higher energy density products such as olefins and higher hydrocarbons; a higher energy product gas is formed. For example, in recent work on the fast pyrolysis of pure cellulose at 900°C and residence times of about 15 ms, 96% of the product mass was accounted for in the non-condensable gas fraction; the gas had a heating value of 403 Btu/ft3 . Similar results were reported for wood flour in an entrained-flow, fast pyrolysis reactor operated at 718°C and a residence time of 0.76 s with a steam-to-biomass ratio of 5.0. About 92.8% of the wood flour was converted to noncondensables and C4+ hydrocarbons. An interesting economic study of various biomass gasification processes for methanol production was reported in which the analysis was internally consistent to permit direct comparisons of different processes to be made. Capital costs for a 1070-bbl/d methanol plant ranged from $39.12 to $56.73 million, and methanol costs ranged from $0.88 to $1.16/gal. Interestingly, the lowest capitalcost process, the Thagard process, which operates at 1760°C, resulted in the highest methanol cost, due to the high operating cost necessitated by electrical

176 ENERGY APPLICATIONS OF BIOMASS

heating of the reactor (electric power was priced at $0.04/kWh for all processes). The Omniful fluidized-bed gasification process, which has not yet been operated at elevated pressure as assumed in the economic analysis, afforded methanol at the lowest cost, $0.88/gal. This system also turned out to have the highest overall thermal efficiency. In all cases, however, the total production cost of methanol, including capital charges, was not competitive with natural gas derived product. Certain sites with special attributes that help to reduce the cost might therefore be needed to make biomass-derived methanol competitive using current technology. These site-specific characteristics might include lower feedstock and electric power costs, as well as good markets for by-products such as C02. The authors of this analysis concluded that the profitability of the various plants is clearly related to the $0.40/gal federal tax subsidy, and that inclusion of the subsidy would make several of these systems show a net after-tax income. Without the subsidy, the per-gallon operating costs of most plants would somewhat exceed the initial market prices of methanol. It should be noted, however, that the federal tax subsidy if applicable is actually a tax forgiveness in that it is not collected by anyone in the marketing sequence. Therefore, it does not reduce the manufacturing cost. 2.2 Anaerobic Digestion Research Laboratories throughout the world are continuing research on anaerobic digestion (or methane fermentation) to increase knowledge of microbial processes and biochemical mechanisms, to evaluate different types of waste streams and biomass feedstocks as substrates for various reactors, and to develop processes with improved reaction kinetics and methane yields. New information has been reported on the mixed obligately thermophilic cultures, originally cultured from 350°C waters along the East Pacific Rise, that were reported last year to be capable of growth at 100°C and 1 atm to produce CH4, CO, and H2 in mineral media. These complex communities of thermophiles are capable of chemolithotrophic growth at pressures of 265 atm and temperatures of at least 250°C. A gas sample from a culture at 300°C contained 9.6% CH4 (presumably mol %), 2.2% H2, and 0.1% CO. The balance of the gas was not stated, but it was probably water or CO2. Doubling times were 8, 1.5, and 0.67 h at 150°, 200°, and 250°C, respectively. These findings open up the possibility that bacteria may exist and grow within the earth’s crust at temperatures exceeding 250°C, and that microbial growth is limited not by temperature, but by the existence of liquid water, assuming all other conditions necessary for life are provided. The investigators also concluded this work greatly increases the number of environments on earth where life can exist. However, it should also be noted that this work supports the possibility of microbial methane formation from minerals within the earth at depths where the pressure-temperature relationships are such as to maintain water in the liquid state. It will be very interesting to determine the

CONVERSION OF LIGNOCELLULOSIC BIOMASS TO ETHANOL 177

methane-forming characteristics of these bacteria with inorganic and organic substrates since the generation times are so short and the lag phase is zero. In other studies of the microbiology of anaerobic digestion, conventional highrate digestion rates of the acetate-to-methane step of 2–4 g/L day have been exceeded 20-fold by careful control of the nutrients, their concentrations, and availabilities (Drexel University). The trace metal requirements for Co and Ni, which is an obligate requirement, and possibly Mo, W, and Se, can be satisfied relatively easily. But Fe and sulfide, both of which are required by methanogens in much more than trace concentrations, tend to precipitate in digester environments and are difficult to provide in solution. “Syncopated pulsing” at different time intervals of these nutrients was the most effective way to satisfy the methanogen’s need for both. An on-line feedback device to measure and supply nutrients in solution is now being developed by these investigators. In similar work, com bined addition of Fe and Co nutrients appeared to be necessary to promote optimal gas production on digestion of spent grain for at least 10 times the retention time. Much of the current research on digester design is aimed at improved performance over high-rate digestion through increased solids retention times (SRT) and shorter hydraulic retention times (HRT), thereby reducing reactor size and cost, and greater retention of the microbial population to maximize substrate conversion. The various reactor configurations achieve these objectives through recycling of digested solids (anaerobic contact process); binding of the anaerobes within the digester to solid supports (anaerobic filters, fluidized or expanded beds, downflow fixed film or packed bed units, upflow fixed film or packed bed units); or flocculation and/or separation of biomass from the liquid phase within the digester (upflow sludge blanket units, baffle digesters). Most of these designs have been in commercial use for several years with wastes (see Sec. 4) ; they are now being evaluated in the laboratory and pilot plants with various biomass substrates. One of the advanced digester configurations employs an ultrafiltration polyether sulfone membrane to separate biomass and particulate organics for recycling to the digester. With simulated, high-strength whey feed, >95% BOD removal was achieved at loadings up to 1.0 lb/ft3 day, and methane production was 4.85 ft3 (STP)/lb COD removed at HRT’s of 2 to 7.4 days. The effect of longer SRTs on digester performance is clear for mesophilic digestion of giant brown kelp. In this case, an upflow-solids reactor that passively retained solids longer than the liquid portion of the feed demonstrated better overall performance than high-rate (stirred-tank) reactors operated at similar loading rates. Two-phase digestion in which the acid and methane phases are physically separated is a configuration that shows great promise for a variety of biomass and waste feeds (IGT). It can also be used with many of the advanced designs to permit longer SRTs than HRTs. A novel approach to two-phase digestion combines a lower, fully mixed acid phase for liquefaction and acid formation, and an upper, fixed-film methane phase with preimmobil-ized bacteria for

178 ENERGY APPLICATIONS OF BIOMASS

converting fatty acids to methane into one digester. The combined two-phase system outperforms the other processes to a considerable degree. Several research projects are in progress to evaluate various biomass species as sources of methane. Application of a long-term, batch anaerobic biogasification potential assay to several herbaceous species afforded methane yields in the range 4 to 6 ft3/lb VS added. Sorghum exhibited a methane yield up to 6.4 ft3/1b VS added, corresponding to a reduction in organic matter of 92%. Methane yields as high as 3.5 to 5.1 ft3/lb VS added were observed for several hardwood species without pretreatment, while sodium hydroxide pretreatment resulted in improved methane yields or production rates with several species. Based on this work and many other studies of the digestability of biomass, there is no shortage of degradable feedstocks. Almost all land-based, aquatic, and marine species examined to date either have good digestion characteristics or can be pretreated to promote digestion. The cost, of course, is reduced if pretreatment is not necessary. One of the biomass species that does not require pretreatment for conversion to methane by anaerobic digestion is giant brown kelp. A recent detailed economic analysis was made of the growth, harvesting, and biological conversion of kelp to methane for an integrated near-shore kelp farm and a shoreline digestion plant. Depending on the assumptions made in the analysis, baseline methane costs were $13.47/106 Btu. Kelp and gas yield increases, which are believed to be achievable, reduced the methane price to $6.14 to $8.66/106 Btu. Thus, the economic feasibility of kelp as a feedstock for methane production appears to be within reach. Additional research on kelp growth and conversion will help determine whether kelp-to-methane systems are competitive. Although the economic feasibility of simultaneous waste disposal-methane production by anaerobic digestion has been established in many cases, the economic feasibility of producing methane from urban wastes is yet to be demonstrated, according to some analysts. The 100-ton/day (design) RefCom plant in Pompano Beach, Fla., which produces methane from MSW by anaerobic digestion is the largest research project in the world that has the goal of determining this feasibility. The RDF-preparation section of this plant was recently modified to overcome operating problems. The entire system will now be operated to evaluate the performance of newly installed disc screens in the RDF section; dewatering of the digested solids by belt press, cone press, and vacuum filter; the effects of digestion temperatures less than 60°C; and the effects of various municipal sludge: RDF ratios. 3 LIQUEFACTION * Liquefaction of biomass and wastes is accomplished by natural, direct and indirect thermal, and fermentation methods. Natural liquefaction systems were referred to in Sec. 2.2 of this paper in connection with certain arid-land plants

CONVERSION OF LIGNOCELLULOSIC BIOMASS TO ETHANOL 179

and microalgae growth and the resultant formation of lipids and hydrocarbons. Other natural processes that produce liquids suitable as fuels are performed by certain tree species (e.g., the Brazilian Copaifera langsdorfii tree that yields sesquiterpenes that can be used as diesel fuels without modification, and plants that bear oil seeds; e.g., sunflowers). Research is continuing in all of these areas. One of the most interesting approaches to the natural production of liquid fuels by biomass is under investigation by Nobel prize winner Melvin Calvin using a combination of natural photosynthesis and genetic manipulation. The overall process consists of three steps: hybridization of Euphorbia lathyris with E. esula, which produces fewer hydrocarbons than E. lathyris but grows as a perennial rather than an annual; modification of the photosynthetic pathway of the hybrid to cyclize C15 intermediates so that sesquiterpenes are formed; and transfer of the gene that codes for sesquiterpene production from C. langsdorfii to the plant. Conceptually, this sequence would optimize for sesquiterpene production by a herbaceous plant that can be grown in the United States at high annual yields without replanting each year. This process would provide a significant advance over present techniques of liquid hydrocarbon production from biomass. Currently, more research is being done on direct and indirect thermal liquefaction methods for biomass and wastes than on the other methods. Direct liquefaction is either reaction of biomass components with smaller molecules such as H2 and CO (e.g., PERC and LBL processes) or short-term pyrolytic treatment, sometimes in the presence of gases such as H2. Indirect liquefaction involves successive production of an intermediate, such as synthesis gas or ethylene, and its chemical conversion to liquid fuels. In 1983, after several years of laboratory and pilot-plant work on the PERC and LBL processes, which involve reaction of product oil or water slurries of wood particles with H2 and CO at temperatures up to about 370°C and pressures up to 4000 psig in the presence of sodium carbonate catalyst, researchers concluded that neither process can be commercialized for liquid fuel production without substantial improvement. The most attractive approach to such improvement is believed to be a combination of solvolysis with a pyrolysis or reduction step. However, the oxygen content of the resulting complex liquid mixture is still high (~6 to 10 wt %), and considerable processing would appear to be necessary to upgrade this material. A convenient classification of biomass pyrolytic processes is shown in Table 4. Maximum liquids yields are usually obtained in the intermediate temperature range if the residence time is short. Among the short residence-time processes (0.5 to 5 s) under development are vacuum pyrolysis at about 300° to 400°C and 0.3 atm (U. of Sherbrooke, Canada), flash pyrolysis at about 500° to 650°C and 1 atm (U. of Waterloo, Canada), hydropyrolysis in an atmosphere of

*Note: Ethanol and methanol fuels are discussed in the next two sections.

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hydrogen at about 500° to 600°C andS to 6atm (HYFLEX™ , IGT), and flash pyrolysis in atmospheres of hydrogen or methane at 600°-1000°C and 1 to 70 atm (Brookhaven National Laboratory). An interesting report of a relatively long residence time (10 to 15 min heat-up, several hours at temperature) pyrolysis study at reduced pressures of 0.0004 to 0.004 atm and temperatures of 250° to 320°C of wild cherry wood seems to contrast with the results of several reports on flash pyrolysis. In this study, about 70 wt % of the sample was volatilized at 290° to 315°C over the pressure range studied; the major products were methanol, acetone, acetic acid, cresols, and substituted phenols. These results suggest that the combination of lower temperature, reduced pressure, and long residence time may provide a technique for minimizing char and heavy tar formation. In any case, the liquid products from all direct pyrolysis processes are highly oxygenated and acidic. Chemical rather than fuel applications would appear to be more feasible with these wood oils at this time. Fundamental studies of the mechanisms of biomass pyrolysis continue to shed more light on the complex chemistry of direct thermal conversion. One of the most interesting techniques developed by the Solar Energy Research Institute (SERI) for this work uses direct mass spectrometrio sampling of pyrolysis products from wood. The goal of these studies is to determine, in molecular detail, the chemistry and kinetics of the primary and secondary pyrolysis processes for biomass and its constituents. “Fingerprints” characteristic of the particular biomass used and identification of the broad range of compounds formed including specific polynuclear aromatics will undoubtedly make this technique very useful. Table 4: Biomass pyrolysis classifications* pyrolysis type heating rate (°C/ temperature (°C) residence time s) Conventional

<2

primary products

<500

>5 s for gas, Tar, char long for solids Flash >2 400–600 <2 s Tar, liquid Ultra** 200–100,000 >600 <0.5 s Gas *Adapted from reports of the National Research Council of Canada. **Original draft defined ultrapyrolysis as fast pyrolysis; revised to ultrapyrolysis in subsequent articles.

Research on indirect liquefaction processes has continued on the production of diesel fuels via synthesis gas by Fischer-Tropsch chemistry (U. of Arizona) and on polymer gasoline formation from ethylene (SERI). The latter process uses an entrained flow cyclonic reactor with external resistance heaters to obtain very high heating rates and little or no char. About 93% of pine wood flour was gasified at 718°C, 0.76-s residence times, 11 kPa, and a steam-wood weight ratio of 5.0; the product contained 15 wt % C2+ components. Current results indicate

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that 15 wt % conversions of softwoods, or about 35% to 10% of the contained energy, to C2+ hydrocarbons including aromatics are feasible. The products contain about 7 to 7.5 wt % of the feed as ethylene. Whether this yield level is sufficient to make polymer gasoline manufacture economically feasible has not been established. Commercialization of biomass liquefaction processes using short-term pyrolysis techniques has not occurred in the United States in modern times; an unsuccessful attempt was made a few years ago in California with RDF. Other prospects do not appear favorable either. For example, a recent assessment of hydropyrolysis concluded that HYFLEX is not commercially feasible with feedstocks from a tree farm in Hawaii because the estimated price of $55/BOE for the product is too high relative to current crude oil prices. Because of the cost of harvesting, which was estimated to be $22.40/dry ton, it was also concluded that its highly improbable product cost can be reduced to competitive levels. The most likely candidates for commercialization of biomass-derived liquid fuels, excluding alcohol fuels, in the next several years are the natural oils such as the triglycerides. These products are under extensive tests in various forms as diesel fuels or diesel fuel components. Although prospects appear to be poor for commercialization of biomass liquefaction processes for fuels at the present time, it should not be forgotten that sales of biomass-derived chemicals, many of which are liquids, are extensive. Sales of wood-based chemicals, for example, were over $0.5 billion in the United States in 1977. Many of the products are specialty chemicals whose molecular structures have not been drastically modified by severe thermal treatment. Perhaps the lesson to be learned from this is that processes for biomass-derived liquids should be designed to capitalize on the structures of their precursors. 3.1 Ethanol Fuel Motor fuel usage of ethanol in the United States almost tripled from 1981 to 1982, and projections indicate that sales will increase about 178% over that in 1982 to a level of 375 million gal (1.419×109 L) in 1983. Production of ethanol fuel by fermentation surpassed synthetic ethanol for the first time in 1982. The federal and state tax exemptions for ethanol fuel are substantial, and effectively subsidize a booming industry that would not survive without tax forgiveness. Interestingly, although the price of corn, from which most ethanol fuel is made in the United States, increased from $2.54/bu (12–28–82) to $3.44/bu (12–21–83), the F.0.B. price charged by the largest producers of fuel ethanol—Archer Daniels Midland (39% of total U.S. capacity) and Pekin Energy Co. (~11% of total U.S. capacity)—decreased from $1.68/gal to $1.54–1.57/gal over the same time period. Since the embedded feedstock cost at these corn prices corresponds to about $0.98/gal (12–28–82) and $1.32/gal (12–21–83) without by-product credits, the apparent reason for this unexpected trend in fuel ethanol pricing in

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1983 is the competition caused by the reduction in gasoline prices. Obviously the profit margins of the ethanol fuel producers who use corn feedstocks have significantly diminished. The largest ethanol fuel effort in the world, Brazil’s Proalcool program, is making excellent progress and should achieve its production goal of 2.83×109 gal/yr (10.7×109 L/yr) by 1985, or the equivalent of 101,000 BOE/day. Production in 1982 and 1983 was estimated at 1.1×109 gal and 1.4×109 gal; 1984 production is projected to be 2.3×109 gal. Although discrepancies among the various market figures are reported, about 136 ,000 neat-ethanol-fueled cars were sold in the first quarter of 1983, and about 500,000 to 600,000 all-alcohol vehicle sales were projected for 1983. Alcohol shortages are expected, so the Brazilian government has stated that it will allow the production of neat-ethanol cars only as long as fuel supplies are guaranteed. In accordance with the requirements of the U.S. Energy Emergency Preparedness Act of 1982, the USDA and DOE published a study in 1983 on the potential of a Strategic Alcohol Fuel Reserve (SAFURE) similar to the existing Strategic Petroleum Reserve (SPR). In the event of a petroleum disruption, ethanol (methanol was considered also) would be withdrawn from the SAFURE and used as a gasoline extender. Two of the major conclusions from this study were: the highest value use for ethanol during a disruption is as an octaneenhancing blending component for unleaded gasoline, and none of the SAFURE alternatives compared favorably with equivalent crude oil storage in the SPR for the base case set of assumptions. The overall, conclusions of the study were that the costs of acquiring, storing, and managing an alcohol fuel reserve are substantially higher than the costs of the current SPR program, and that the value of a barrel of SPR crude oil stored in the Gulf Coast salt domes is substantially greater than a barrel of ethanol stored under any of the SAFURE options considered. The apparent built-in difficulty with this study is that it focused on the use of alcohol as a high-octane gasoline additive; few alternatives were evaluated. Consequently, this defined limitation became part of the conclusions, and the intrinsic value of using ethanol (or methanol) for neat-alcohol fueled vehicles, for example, to permit complete independence from petroleum disruptions was not considered. There is much current research on new ethanol fermentation methods and improvements to increase productivities, permit the use of low-grade biomass or biomass not readily converted, and conserve energy through more efficient separation processes, thereby increasing net energy production. Many of these projects should make important contributions to the development of superior fermentation technology. Some are expected to include improved alcohol fermentation processes for complete use of both the hexoses and pentoses; simultaneous hydrolysis and fermentation of cellulosics; low-cost, multistage acid hydrolysis processes for cellulosics; nondistillation separation of ethanolwater mixtures via extraction, adsorption-desorption on solids, and selective

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membrane permeation; and bioreactors in which residence times are reduced from days to minutes. Research reports in 1983 on the thermal production of ethanol from biomass concerned using catalysts for conversion of synthesis gas, and an interesting process concept that uses intermediate lactic acid salts. Modifying the Cu/ZnO methanol synthesis catalyst by incorporating Mn, Fe, Co, Rh, and Pd by aqueous copreoipitation from nitrate solutions or by impregnation of the binary catalyst with metal carbonyls from organic media resulted in decreased catalytic activity. The best catalyst of those tested for C2+ alcohol formation was the Fe/Cu/ZnO system, but the selectivities for higher alcohol production were poor compared to the 72% selectivities reported by the Institute Francais du Petrole for C2+ alcohols in a similar process. In the lactic acid salt process, biomass-derived sugars are converted to lactic acid salts such as calcium salts, which are decarboxylated to yield ethanol. In experimental work, lactic acid metal salts formed in high yields from hexoses and pentoses, but low yields of ethanol were obtained on thermal treatment of these salts in water. Additional research is necessary to perfect the decarboxylation step. 3.2 Methanol Fuel Without cosolvent, methanol is legally limited to 0.3 vol % concentrations in unleaded gasoline. Methanol is also excluded from federal and most state tax exemptions because essentially all of it is presently made from natural gas. A few projects have been announced in which biomass will be used as feedstock, but none has yet reached the commercial stage. The latest request to use up to 3 vol % neat methanol in unleaded gasoline by DuPont in 1982 was denied by the USEPA in February 1983. There are several technical reasons for limiting neatmethanol usage in blends with unleaded gasoline to 0.3 vol %, but it is still used in relatively large quantities in the approved formulations, and as the additive MTBE (methyl-t-butyl ether). Sales of Oxinol, a 50:50 mixture of methanol and t-butyl alcohol cosolvent, are reported to be equivalent to nearly 50×10 gal of methanol (and 50×106 gal of t-butyl alcohol) in 1983. This does not include the potentially large volumes of neat methanol used illegally in gasoline blends. Production of methanol increased about 40% from 1975 to 1983. However, statistics indicate the fuel applications will grow rapidly to about 20% to 27% of total usage in 1985 and to about 32% in 1990. By 1985, net imports are projected to cover the short-fall. Long-term growth of methanol fuel usage appears to be gathering momentum despite the present limitation on use of neat methanol. The Ford Motor Company still maintains the position that for the United States, methanol is the chosen alcohol fuel because of for economic reasons. Near-neat methanol (methanol containing about 10 vol % gasoline) or neat methanol is preferred over methanol blended into gasoline. To develop this technology in the United States, Ford

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Motor Company has supplied California with 506 methanol-fueled Escorts for use in fleet tests, and the California Energy Commission has sponsored the construction of 33 methanol fueling stations. The role that biomass will have as a feedstock for methanol production is not clear at this point. Numerous studies have been carried out to develop economic estimates, and a few projects have been announced; but to date none of these activities has resulted in an operating biomass-fueled plant in North America. The most recent project, now in the detailed engineering phase, will process 300 ton/day of sawmill residues using the Omnifuel pressurized, fluid-bed gasifier and a methanol train to yield 165 ton/day of methanol. But this scale of operation is far removed from the projected demands for methanol fuel, since about 14 or 15 50,000-bbl/day methanol plants based on coal would be able to supply enough methanol to displace about 10% of the country’s daily gasoline consumption. The amount of dry biomass equivalent needed as feed for such plants would be about 16,000 ton/day. This is about 25 times the feed rate of the largest woodfueled power plant believed to be feasible at this time because of the limitations on fuel transport distance. Thus, present technology will limit methanol-frombiomass facilities to smaller dispersed plants, with maximum methanol capacities of 2000 to 3000 bbl/day (~50% thermal efficiencies to methanol, ~1.5 bbl methanol/green ton feed). The total production cost of methanol including capital charges for a 1070-bbl/ day plant supplied with green wood feedstock (wood chips at $15.50/ton, 50 wt % moisture) ranges from $0.88 to $1.16/gal (1983 dollars) for a broad range of gasification processes. As of December 21, 1983, methanol was selling for $0.43 to $0.45/gal, so clearly methanol produced by conventional wood gasificationsynthesis gas reduction technology could not compete in the open market. Sensitivity analyses for the Omnifuel process showed that increases in plant sizes to 500 and 1000 ton/day of methanol reduced the methanol price to $0.67 and $0. 63/gal, which is still not competitive. A similar analysis conducted with landfill gas at $1.50/10° Btu for a 568-bb1/day plant afforded methanol at $0.77/gal.

CONVERSION OF LIGNOCELLULOSIC BIOMASS TO ETHANOL L.J.DOUGLAS* *Solar Energy Research Institute, Golden, Colorado

1 INTRODUCTION The Solar Energy Research Institute (SERI) has been assigned field responsibility by the Department of Energy, Biomass Energy Technology Division, for the direction of the National Alcohol Fuels Program. The principal objectives of the program are to develop the conversion technology for transforming lignocellulosic biomass into fuels alcohols, and to provide a mechanism for the early transfer of mature processes to the private sector. Premium liquid fuels, particularly in the transportation sector, represent an area of potential shortfall in the event of another disruption in imported oil, and in the long term liquid fuels are expected to be in short supply. This paper discusses why ethanol is a useful fuel, and why lignocellulose is a suitable feedstock for ethanol. 2 ETHANOL AS A FUEL Ethanol is a high-value liquid fuel that has excellent octane-enhancing properties and readily blends with the existing hydrocarbon-based fuel supplies and distribution system. Ethanol has very clean combustion properties and offers an environmentally safe material for octane replacement for tetraethyllead, which is being phased out of gasoline. 3 LIGNOCELLULOSIC BIOMASS AS A FEEDSTOCK FOR ETHANOL Ethanol is principally made from grain and ethylene. Ethylene-based ethanol plants are being closed down as the price of petroleum increases because ethylene-based ethanol cannot compete with grain-based ethanol in the marketplace. However, substantial increases in the amount of grain based

186 ENERGY APPLICATIONS OF BIOMASS

ethanol would cause disruptions in the food chain and raise the often heard “food versus fuel” arguments. Lignocellulosic feedstocks provide an inexpensive, renewable resource for the production of ethanol. Use of these feedstocks would minimize competition with the food chain, since dedicated wood crops could be grown on marginal, nonagricultural lands. The conversion processes are environmentally benign and can be adapted to such lignocellulosic materials as crop and forest residues, hard- and softwoods, and MSW. 4 FEEDSTOCK CHARACTERISTICS Lignocellulosic materials are in the form of a matrix that consists of three polymeric components: cellulose, hemicellulose, and lignin. These three components are situated in the material in a manner that provides mechanical strength and forms a barrier to chemical and biological attack. Cellulose is the principal component of the complex and is a linear polymer of hydroglucose units. Cellulose is always found in nature in microfibrils, which are 40 cellulose chains or 35 angstroms in cross-section. These very rigid structures are embedded in a matrix of amorphous hemicellulose and lignin, which forms the resistant cell walls. The feedstocks chosen for this program are hardwoods and crop residues. Figure 1 shows the relative composition of a hardwood, in which the cellulose fraction constitutes about 50% of the material, hemicellulose about 25%, and the lignin about 25%. 5 RESEARCH OBJECTIVES The objectives of the program are to • Develop the technology base for the economic conversion of lignocellulosic biomass to ethanol and other liquid fuels • Improve the overall utilization of lignocellulosics through research on – Acid hydrolysis processes – Enzymatic hydrolysis processes – Supporting research activities. Figure 2 shows the current conversion efficiency of developed processes and indicates that only cellulose is used to produce fermentation sugars. Thus only about 30% of the feedstock is used to produce an end-product fuel. Figure 3 shows ethanol yield goal of the program in which about 70% of the feedstock is used to produce sugars for fermentation to ethanol and other liquid fuels. In

COMPARISON OF ALTERNATIVES FOR THE FERMENTATION OF PENTOSES 187

addition, the lignin fraction can be converted to liquid fuels via thermal processes that will boost the total yield to about 90% of the feedstock. Clearly, the research objectives are to produce the maximum amount of liquid fuels from the feedstock; however, relating the changes in conversion yield to specific improvements in the cost of production of the ethanol is not an easy process. Figure 4 shows the year 2000 cost goals for renewable ethanol technology, which is to produce ethanol for $1.21/gal without any federal subsidy. This goal will be accomplished by meeting several research objectives that include reduction in the feedstock cost via the short rotation woody crops program and utilization of higher percentages of the native feedstock through higher conversion yields. Note that the feedstock contribution to the selling price of ethanol becomes less significant as the conversion yields increase. If the process efficiency can also be improved, then the cost of the feedstock will no longer dominate the process economics. 6 ROUTES TO ETHANOL The several approaches to production of ethanol are shown in Fig. 5. The fermentation of sugars, conversion of starch to sugars, and fermentation of sugars to ethanol are mature technologies and will not be described in this paper. The conversion of lignocellulosic biomass to ethanol via hydrolysis of cellulose and hemicellulose followed by fermentation is a more difficult approach because of the highly resistant properties of this material. The two basic types of hydrolysis of cellulose are acid and enzymatic hydrolysis. The various system configurations for each of these processes can accommodate variations in several process parameters, including type and concentration of acid, operating temperature, reactor configuration, microbial system, and pretreatment. Acid hydrolysis approaches included for study in the program are dilute sulfuric acid and concentrated sulfuric acid processes. Two dilute acid processes are being investigated. One uses Dartmouth’s plug-flow reactor design, which features a high-temperature, short residence time system and will be discussed in more detail later. The other is a moderate-temperature (180°C) system that is a variation of the Madison percolation system developed during the 1940s. Three enzymatic hydrolysis systems are being developed under the program: separate hydrolysis and fermentation (SHF), simultaneous saccharifi cation and fermentation (SSF), and direct microbial conversion (DMC) processes. The SHF system uses separate hydrolysis and fermentation reactors for processing the feedstock and is the standard (base case) approach for microbial conversion, conceptually the most simple. This system will also be discussed in more detail later. The SSF system combines the hydrolysis and fermentation steps in one reactor. While this variation provides several technical improvements, it also requires additional process control. The SSF process appears at present to be the most feasible system in the mid-term. The DMC approach uses thermophilic

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bacteria that feed directly on the cellulose and hemicellulose portions of the feedstock to produce sugars and use the sugar to produce ethanol directly, in one step. Conceptually, this should be the preferred system in the long-term; however, this approach has the highest risk and the most technical barriers to success. 7 BASE CASE STUDIES In this paper only one variation for each of the general process types will be discussed: (1) a high-temperature, dilute-acid hydrolysis process, and (2) a basecase enzymatic hydrolysis process (SHF) that uses steam explosion as the pretreatment. 7.1 Acid Hydrolysis Process The base-case acid hydrolysis process employs a plug-flow reactor in the hydrolysis unit that operates at 240°C, 1% acid, and a 7-s residence time. The substrate is ground aspen wood, which is loaded into the reactor as a 15% solids slurry with water. The unreacted solids are pressed and burned to provide heat for the process. The liquid stream containing the soluble sugars is neutralized using calcium hydroxide and treated to remove any materials that would be toxic to the fermentation organisms. Standard fermentation and distillation convert the glucose sugars to ethanol and purify the ethanol to fuel quality. The base-case design was sized to produce 50 million gal/yr of anhydrous ethanol from aspen wood; the cost estimates were based on a Gulf Coast location and constant 1983 dollars. The 50 million gal/yr size reflects the dispersed nature of biomass and assumes a maximum collection radius of 25 miles. The estimate for the selling price of ethanol from the base-case system as configured was $2/gal. Parametric analyses were performed for several operating conditions and system configurations. The items determined to be the dominant cost-controlling factors are feedstock cost, solids loading in the reactor, and xylose sugar utilization. The cost of the feedstock is the dominant factor in determining the costeffectiveness of production of ethanol in the acid hydrolysis process. Figure 6 shows the relationship of the selling price of ethanol in $/gal versus the cost of the aspen wood. This relationship dictates the necessity of reducing the cost of the feedstock or increasing the yield for the process to reduce the production cost per unit of ethanol. The amount of water in the process streams has a large effect on the process economics. The presence of large amounts of water increases the steam requirements as well as the equipment size and capital cost of the plant. In addition, low solids loading yields a dilute sugar stream to the fermentation

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section, resulting in a low ethanol concentration in the beer and increased energy requirements for the distillation section. Figure 7 shows the effect of solids loading on the selling price of ethanol. The optimum solids loading appears to be about 30%. This is the target value in our current process design; however, reliable equipment for handling solids at this level may be difficult to obtain. Process changes that favor the use of the xylose sugars in the feedstock can greatly reduce the selling price of ethanol. One approach being studied is to develop, through genetic engineering techniques, a yeast that can ferment both xylose and glucose in the same fermentation vessel. This research issue is being pursued with vigor because meeting this goal has the potential to reduce the selling price of ethanol to about $1.10/gal. A more imminent alternative is to convert the xylose to furfural and use the by-product credit to subsidize the selling price of ethanol. Figure 8 shows the effect of credit for furfural on the selling price of ethanol. The current market price for furfural is about $0.60/lb, and a net selling price for furfural of $0.10/lb could reduce the selling price of ethanol to less than $1/gal. With the current demand for furfural, one or two 50million-gal/yr plants would saturate that market. However, there is a large potential market for derivatives of furfural that are based on well-known chemical processes if the price of furfural were low enough to encourage the chemical industry to change feedstocks. 7.2 Enzymatic Hydrolysis Process The base-case enzymatic hydrolysis process was a separate hydrolysis and fermentation (SHF) system that was studied at SERI using the Chem Systems model, which was developed under a SERI subcontract. The data include recent research results from Lawrence Berkeley Laboratories. The base case consisted of steam-explosion pretreatment, enzyme production by a fed-batch fermentation of the RUT-C30 strain of the fungus Triehoderma reesei, hydrolysis of the cellulose to glucose by enzymes followed by fermentation of the glucose in a separate process step, and vapor reuse distillation. The operating conditions for the base case were: • Pretreatment for 5 seconds with 400 Ib of steam per ton of wood at 560 psig and 247 °C • Substrate loading of 20 wt % • Enzyme loading of 25 FPU per gram of substrate (to yield 80% conversion of cellulose to glucose). The base case for the enzymatic process was also sized to produce 50 million gal/ yr and was subjected to the same constraints as the acid hydrolysis case. The estimated selling price of fuel-grade ethanol from the process as configured was $2.30/gal.

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Parametric analyses completed on the base-case enzymatic hydrolysis process identified the most cost-sensitive factors as feedstock cost, enzyme recycle, and xylose utilization. The feedstock cost had approximately the same effect on the selling price of ethanol as in the acid hydrolysis case. However, the conversion yield in the enzymatic processes is anticipated to be higher than in the acid hydrolysis case, and the effect of feedstock cost will not dominate the total cost. For example, the feedstock cost in acid hydrolysis base case was approximately $0.75/gal, while for the enzymatic hydrolysis case it was about $0.50/gal (based on cellulose conversion only). The process variable with the most effect on the selling price of ethanol was enzyme recycle. Figure 9 shows the relationship between enzyme recycle and the selling price of ethanol. Clearly enzyme recycle has a dramatic effect on the process economics; however, Fig. 10 shows the effect of several other process options, and again the recycle option is clearly dominant. Conversion of xylose to ethanol also provides a substantial reduction in the price of ethanol, while the remaining changes in operating conditions produce only a small reduction in selling price. Figure 11 shows the impact of improvements to the microbial organism for enzyme production. This research activity also has a major role in reducing the selling price of ethanol. 8 CONCLUSIONS The technology for the conversion of biomass to alcohols has developed rapidly in the last few years, and several systems will probably be ready for scale-up experiments in the next three or four years. To assess the readiness of these technologies, two approaches have been used: evaluation by commercial engineering companies, and modeling studies to identify the cost-sensitive parameters in the candidate processes. SERI has enlisted the assistance of several consulting firms to review the current state of the art of cellulose conversion technology by completing feasibility studies for each process that has commercial potential. The firms selected were Stone and Webster, A.D. Little, Chem Systems, and Badger Engineering. Each of these companies will develop a flow sheet using the best available data for the process being evaluated. Then capital costs will be estimated, heat and material balances will be calculated, and a production cost determined. Each engineering firm will also suggest areas for further research to reduce the cost of production based on their evaluation and feasibility study results. The use of parametric analysis as a tool to evaluate process options in biomass conversion technology has been a valuable asset to development of research strategy for the Alcohol Fuels Program. These results must be kept in perspective because the estimated costs for the production of ethanol shown in this

COMPARISON OF ALTERNATIVES FOR THE FERMENTATION OF PENTOSES 191

Fig. 1. Relative composition of lignocellulosics

Fig. 2. Current conversion of fractions to ethanol

presentation are accurate to only ±35% at best. The real value in this exercise comes from comparing various process options and plant configurations, and using the results of these studies to identify the research and process activities that have the greatest potential for cost reduction.

192 ENERGY APPLICATIONS OF BIOMASS

Fig. 3. Ethanol yield goals to improve productivity

Fig. 4. Cost goals for renewable ethanol technology (based on feedstock cost of $40/dry ton)

COMPARISON OF ALTERNATIVES FOR THE FERMENTATION OF PENTOSES 193

Fig. 5. Ethanol process options

194 ENERGY APPLICATIONS OF BIOMASS

Fig. 6. Selling price of ethanol vs. cost of aspen wood

Fig. 7. Cost of ethanol vs. percentage of solids in the reactor feed

COMPARISON OF ALTERNATIVES FOR THE FERMENTATION OF PENTOSES 195

Fig. 8. Selling price of ethanol as a function of the net furfural by-product credit

Fig. 9. Selling price of ethanol vs. percentage of enzyme recycle

196 ENERGY APPLICATIONS OF BIOMASS

Fig. 10. Ethanol selling price vs. process improvements

Enzyme Productivity (IU/liter/hr) Enzyme Costs ($/gal of ethanol) Fig. 11. Research improvement

1980

1985

1990

2000

50 IU

100 IU

200 IU

400 IU

1.20

.60

.30

.15

COMPARISON OF ALTERNATIVES FOR THE FERMENTATION OF PENTOSES TO ETHANOL BY YEASTS T.W.JEFFRIES* *U.S.D.A., Forest Service, Forest Products Laboratory, Madison, Wisconsin

SYNPOSIS Hemicelluloses are major components of plant biomass. In hardwoods and agricultural residues, xylose is the principal hemicellulosic sugar. Xylose and other hemicellulosic sugars are recovered from lignocellulose more readily but are fermented with greater difficulty than is glucose. Xylose metabolism employs pathways distinctly different from those involved in the utilization of glucose. With most yeasts, xylose metabolism requires air. Aeration results in cellular respiration (as opposed to fermentation) and low ethanol yields. It is possible, however, to suppress respiration by feeding small amounts of glucose during the xylose fermentation. Some yeasts, such as Pachysolen tannophilus, will metabolize xylose anaerobically. Alternately, other yeasts will anaerobically ferment the keto isomer of xylose, xylulose, after it is formed from xylose by the action of xylose isomerase. In both instances, the fermentation rates are low. Improved strains of P. tannophilus have been obtained by UV mutagenesis followed by enrichment for faster growth in nitrate-xylitol broth or by selecting for yeast strains incapable of using ethanol as a carbon source. Several yeasts have been described as superior xylose fermenters, including (in approximate ascending order) : Candida troplcalis. Kluyveromyces marxianus. P. tannophilus, the mutant Candida sp. XF 217, and Candida shehatae (and its sexually perfect form, Pichia stipitis) . The xylose fermentation rate of C. shehatae is 3 to 5 times higher than that obtained with P. tannophilus, but the yields of ethanol from xylose are similar with the two organisms. The glucose fermentation rate and ethanol yield are lower with C. shehatae) than with P. tannophilus. Unstable petite and grande strains of C. shehatae have been obtained on urea+xylitol agar, and some show markedly different fermentation rates and products. Further strain improvement and process development should soon provide commercially practicable technology for the fermentation of xylose.

198 ENERGY APPLICATIONS OF BIOMASS

1 INTRODUCTION Within the realm of liquid fuel production from biomass, utilization of lignocellulose has focused largely on the problem of cellulose saccharification. Various approaches have been tried including hydrolysis by extra-cellular streptomycete and fungal cellulases, simultaneous saccharification and fermentation by cellulolytic bacteria, and acid hydrolysis followed by fermentation. To a certain extent, the attention given to cellulose is justifiable. Cellulose comprises about half of the total weight of lignocellulose, and its fundamental constituent, glucose, is an excellent fermentation substrate. In a larger context, however, consideration of cellulose to the exclusion of the two other major constituents, hemicellulose and lignin, is futile. One reason is that it is uneconomical to throw away almost half of the feedstock. Another is that cellulose has appreciable commercial value as fiber. Converted to pulp, a ton of cellulose is worth $400 to $700; converted to ethanol, it is worth less than $300. In the kraft pulping process, lignin and hemicellulose are extracted under alkaline conditions and then burned to recover chemicals and energy. In some instances, the lignin is recovered for other applications. The hemicellulose is largely degraded to organic acids prior to combustion and has no current commercial value. Other technologies are being developed that will enable the efficient fractionation of lignocellulose into pulp-grade cellulose, useful lignin derivatives, and useful hemicellulosic sugars including xylose. The objective of the research described in this paper is to improve our knowledge of pentose metabolism in yeasts and to thereby provide the means for more efficient utilization of xylose. 1.1 Sources and Recovery Hemicellulosic sugars are major constituents of wood and agricultural residues. Table 1 shows the average proximate composition of seven commonly occurring hardwood (angiosperm) and softwood (gymnosperm) species (Ref. 1–3) along with a few major U.S. agricultural residues (Refs. 4–6). Table 1: Proximate composition of some major lignocellulosic materials* lignooellulose

hemicellulosic sugars

cellulose

lignin

Hardwoods** Softwoods′ Wheat straw Corn stalks

24 19 29 28

45 43 31 30

21 29 14 —

NOVEL DEVELOPMENTS IN BIOREACTOR DESIGN AND SEPARATIONS TECHNOLOGY 199

lignooellulose

hemicellulosic sugars

cellulose

lignin

Soybean residue 19 37 — *(% of total dry weight) . **Average of Populus tremuloidies, Fagus grandifolia, Betula Papyrifera, Acer saccharum, and Quercus faloata. ′ Average of Thuja occidentalis, Pinus taeda, Pseudosuga taxifolia, and Picea glauca.

Generally, hardwoods have slightly more neutral hemicellulosic sugars and cellulose but less lignin than softwoods. The composition of the hemicellulose differs in hardwoods and softwoods. In hardwoods, the predominant hemicellulosic sugar is the pentose xylose; in softwoods, the predominant hemicellulosic sugar is the hexose mannose. The xylose content of hardwoods is greater than softwoods. Most agricultural crops are angiosperms and, like hardwoods, have xylose as the predominant hemicellulosic sugar. As described elsewhere in this symposium, low-grade hardwoods are available in relative abundance in the United States, but low-grade softwoods are in relatively short supply. The combination of a greater angiosperm resource and a higher proportion of xylose in that resource make xylose utilization a major concern in production of fuel from biomass. In addition to being relatively abundant, xylose is more readily recovered from hemicellulose than glucose is from cellulose. Dilute acid hydrolysis of hemicellulose yields about 85% to 90% of the xylose present in red oak; dilute acid hydrolysis of cellulose yields only about 50% to 60% of the glucose present. The difference between the xylose and glucose yields can be attributed directly to physical and chemical properties of the two polymers and hence is not readily amenable to process changes. The situation is similar with regard to enzymatic hydrolysis. Although up to 90% of the glucose can be recovered from steam-exploded wood if sufficient cellu lase is added, at economical enzyme loadings glucose yields are substantially lower. Taking the differences in yields of xylose and glucose into account, roughly equivalent amounts of sugar can be recovered from the hemicellulosic and cellulosic fractions. 1.2 Biochemical Pathways and Fermentative Capacities Xylose can be assimilated by many bacteria, yeasts, and filamentous fungi, but initial steps of assimilation in yeasts and fungi are significantly different from those in bacteria. In yeasts and fungi, xylose is first reduced to xylitol and then oxidized to xylulose. In bacteria, the conversion from xylose to xylulose is catalyzed by xylulose isomerase in a single step (Ref. 7). This paper considers only the activities of naturally occurring yeasts.

200 ENERGY APPLICATIONS OF BIOMASS

Most yeasts use a xylose reductase with a specific requirement for NADPH as a cofactor to reduce xylose to xylitol. Next, xylitol dehydrogenase specific for NAD oxidizes xylitol to xylulose. Consequently, assimilation of xylose converts NADPH into NADH. In Candida utilis, the organism best studied in this regard (Ref. 8), NADPH is supplied by the oxidative phase of the pentose phosphate pathway (PPP) in a closed cycle (Fig. 1). Under oxidative conditions, the only mode of fungal xylose assimilation known until 1981, NADH is recycled to NAD by respiration. Under anoxic conditions, NAD cannot be regenerated, and xylose assimilation ceases (Ref. 9). NADPH is used primarily in metabolic syntheses, and is generated mainly by the oxidative PPP (Ref. 10). Thus, production of NADPH by the oxidative PPP is thought to provide the means to assimilate xylose for aerobic production of ethanol by Candida tropicalis and other yeasts (Ref. 12). More recently, certain yeasts capable of fermenting xylose to ethanol in the absence of oxygen (anoxically) (Ref. 13) have been shown to possess xylose reductase(s) capable of using either NADH or NADPH as a cofactor (Ref. 14). If NAD(H) can be used for both the reductive and oxidative steps of xylose metabolism, the balance between NAD and NADH can be maintained under anoxic conditions (Fig. 2) and xylose utilization is not dependent on aeration. The observation that P. tannophilus will ferment but not grow anaerobically on D-xylose could be attributed to the insufficient production of metabolic reductant or energy for growth. 2 PROCESS ALTERNATIVES 2.1 Coupled Isomerization and Fermentation In 1980, Wang, Shopsis, and Sohneider (Ref. 15) showed that yeasts are able to ferment xylulose to ethanol under anoxio conditions. This finding had immediate implications because the conversion could be carried out readily by using commercial xylose (glucose) isomerase. The discovery was immediately seized upon and became the basis for considerable research and development in this field. As proposed for commercial practice, the technology would employ exogenous, immobilized xylose isomerase (already commercially derived from bacteria) to convert xylose to an equilibrium mixture of xylose and xylulose. The xylulose would then be fermented to ethanol and the residual xylose recycled over the xylose isomerase. The process would be continued until all xylose was consumed. Several variations on the basic process are possible and most have been attempted, but the principal remains the same. Xylose isomerase could be incorporated directly into the fermentation vessel or the xylulose could be produced exogenously and separated from the xylose prior to fermentation.

NOVEL DEVELOPMENTS IN BIOREACTOR DESIGN AND SEPARATIONS TECHNOLOGY 201

The process of sequential isomerization and fermentation is affected by several factors. At equilibrium in aqueous solution, xylose isomerase catalyzes the formation of about 17% xylulose from xylose. In comparison 47% fructose is formed from glucose. The lower equilibrium obtained with xylose is offset somewhat by the higher turnover rate of xylose isomerase acting on its native substrate. Other reaction conditions, such as temperature or the inclusion of borate to chelate the xylulose as it is formed, can affect the equilibrium. The literature on xylose isomerase and the xylulose fermentation has been covered in earlier reviews (Refs. 16–19). Cost estimates for the isomerization of xylose have been based on information from the isomerization of glucose to high fructose corn syrup (HFCS). Xylose isomerase is used in both instances. But whereas HFCS production employs high sugar concentrations and optimal conditions for isomerizing glucose, these factors must be compromised with those optimal for fermentation. Reliable values for the cost of HFCS production are difficult to obtain outside the industry; however, one figure published in 1978 placed the cost of isomerization at 2.3 to 3.7¢/kg of fructose produced (Ref. 20). Given that roughly 5.9 kg of sugar are required to produce 1 gal of ethanol, the isomerization reaction would add about 15¢ to 25¢/gal to the cost of ethanol production as compared to an equivalent fermentation using glucose as the feedstock. Although sequential xylose isomerization and fermentation is technically feasible, it is hampered by several factors: the cost of the enzymatic isomerization, the formation of xylitol as a by-product, inhibition of xylose isomerase by xylitol, the use of separate optimal pHs and temperatures for isomerization and fermentation, and the low rate of the xylulose fermentation. Alternatively, new yeasts might be constructed by recombinant DNA techniques to possess xylose isomerase. The approach of employing reeombined yeasts suffers from many of the difficulties listed above plus the basic problem of obtaining adequate expression of enzymatic activity. Moreover, there are few inherent advantages in carrying out a multistep process in a single reactor (or with a single organism) if the process steps have different optimal conditions or if separate organisms are capable of carrying out each of the steps more efficiently. 2.2 Fermentation Rates with Different Sugars The specific xylulose fermentation rate, even with the best strains of yeasts, is appreciably lower than the rate attained with glucose, and in some instances, it is lower than the rate attained with the direct fermentation of xylose. About 60 yeast strains have been screened for their abilities to ferment either xylulose or a mixture of xylose and xylulose under equilibrium conditions (Refs. 21–23). Results with some of the best strains are summarized in Table 2. In general, C.

202 ENERGY APPLICATIONS OF BIOMASS

tropicalis and Schizosaccharomyces pombe ferment xylulose most rapidly, but strains of Saccharomyces cerevlsiae also give better-than-average rates. Volumetric fermentation rates (g ethanol/L•h) are subject to a great deal of variation because cell growth varies under the conditions employed. Indeed, immobilization of cells can lead to very high volumetric rates because of high cell densities. Note, however, that specific fermentation rates (g ethanol/g dry wt of cells•h) generally decrease after cells are immobilized. Although immobilization has been attempted with both the xylulose and xylose fermentations, the volumetric fermentation rates obtained do not approach those commonly observed in the fermentation of glucose by free cells of S. cerevisiae or Zymomonas mobilis. It is better to use specific rates when comparing fermentations of different sugars. The highest reported specific xylulose fermentation rate is about 1/18 of the specific glucose fermentation rate obtained with S. cerevisiae. On the other hand, the highest reported xylose fermentation rate is about 1/6 the specific glucose fermentation rate. For both of these pentoses, little is known about the regulatory biochemical steps or the conditions optimal for fermentation. Table 2: Comparison of xylulose, xylose, and glucose fermentation rates fermentation rate cells

g/L·ha

g/g·hb

Xylulose S. cerevisiae — 0.058 c S. cerevisiae 0.25 0.025 C. tropicalis 0.7 — C. tropicalisc 1.2 — S. pombe — 0.086 S. pombe — 0.10 Xylose K. marxianus 0.04–0.1 — P. tannophilus 0.12 0.05 c P. tannophilus 0.023 2.0 P. tannophilus — 0.12 C. shehatae — 0.28 Glucose P. tannophilus 1.0 0.22 C. shehatae 0.5 — S. cerevisiae 11.8 1.78 Z. mobilis 8.0 2.5 aGrams ethanol/liter of reactor per hour.

reference Chiang et al. (24) Suikho and Poutanen (25) Jeffries (21) Jeffries (21) Roman et al. (26) Chiang et al. (21) Margaritis and Bajpai (27) Jeffries et al. (28) Slininger et al. (29) Slininger et al. (30) du Preez and van der Walt (31) Jeffries et al. (28) this report Maiorella et al. (32) Rogers et al. (33)

NOVEL DEVELOPMENTS IN BIOREACTOR DESIGN AND SEPARATIONS TECHNOLOGY 203

fermentation rate cells g/L·ha g/g·hb bGrams ethanol/gram dry wt cells per hour. clmmobilized cells.

reference

Yeasts ferment glucose, xylose, and xylulose at characteristic rates. In a survey of several different xylose- and xylulose-fermenting yeasts, Maleszka and Schneider (Ref. 22) showed that yeasts capable of fermenting xylose were typically poor xylulose fermenters, and vice versa. Two primary examples are S. pombe and P. tannophilus. S. pombe is a very good fermenter of glucose, but it does not metabolize xylose at all; on the other hand, it is a good fermenter of xylulose. Pachysolen tannophilus ferments glucose more readily than it does xylose, but it ferments xylulose poorly. The fermentation rate obtained on glucose is still much lower than that attained with S. cerevisiae, S. pombe. and other yeasts used for commercial alcoholic fermentations. In this work from our laboratory, C. shehatae has been shown to ferment glucose at a lower specific rate than P. tannophilus, even though it ferments xylose much more rapidly (Table 2 and Figs. 3, 4, and 5). 2.3 Incidence of Xylose-Fermenting Yeasts Sixty-four percent of the species listed in Ref. 32 are cited as capable of assimilating xylose and 7% are cited as variable, but none is listed as capable of fermenting this sugar. A separate taxonomic treatment by Barnette, Payne, and Yarrow lists P. tannophilus and P. stipitis as capable of fermenting xylose (Ref. 35). This discrepancy stems in part from the inability of these yeasts to grow under anaerobic conditions. Even though P. tannophilus will ferment xylose, no cell growth occurs anaerobically, and because the specific fermentation rate is very low, negative results appear unless high cell densities are employed as the inoculum. In a study specifically designed to identify xylose-ferment ing yeasts (Ref. 36), 200 species able to ferment glucose anaerobically and to grow on xylose aerobically were tested for their abilities to ferment D-xylose. In most of these species, ethanol production on xylose was negligible. Only 19 species produced between 0.1 and 0.1 g/L of ethanol. Strains of Brettanomyces naardenensis, Candida shehatae, Candida tenuis, Pachysolen tannophilus, Pichia segobien-sis, and Pichia stipitis produced more than 1 g/L ethanol from 2% xylose.

204 ENERGY APPLICATIONS OF BIOMASS

3 PROCESS VARIABLES 3.1 Effects of Aeration Aeration stimulates cell growth and occasionally stimulates fermentation as well. Only a few yeasts are capable of (limited) anaerobic growth. This inability stems in part from a biochemical requirement for molecular oxygen in the synthesis of membrane steroids. However, Schneider and co-workers (Refs. 7, 8) have shown that the inability of P. tannophilus to grow anaerobically cannot be overcome by the addition of ergosterol or unsaturated fatty acids. Maleszka and Schneider have also shown that oxygen and mitochondrial function are also required for S. cerevisiae to grow on xylulose (Ref. 39). These observations suggest that the anaerobic metabolism of pentoses supplies metabolic energy (ATP) fast enough to satisfy only the basal metabolic demand but does not provide enough ATP to allow cell growth. Aside from affecting growth, aeration strongly affects the specific fermentation of glucose by P. tannophilus. This was first shown by Scheffers and Wiken (Ref. 40). Unexpectedly, the stimulation does not extend to xylose (Table 3). Aeration does increase the volumetric fermentation rate, but this stimulation can be attributed to increase in cell mass. Table 3: Effect of aeration on the specific and volumetric rates of glucose and xylose fermentations by P. tannophilus (Ref. 25) aerobic g/L·h*

anaerobic g/g·h**

Glucose 0.98 0.22 Xylose 0.12 0.05 *Volumetric rate=gethanol/(liter-h) **Specific rate=g ethanol/(g dry wt cells·h)

g/L·h*

g/g·h**

0.11 0.06

0.10 0.05

Pachysolen tannophilus is not alone in showing a stimulation of the glucose fermentation by aeration. The genus Brettanomyoes shows this trait among most of its species (Ref. 40). Aeration is also known to play a role in the fermentation of glucose by Saccharomyces (Ref. 41), but in this instance, it is primarily important in maintaining cell viability and ethanol tolerance (Ref. 42). Aeration decreases the yield of ethanol from xylose by P. tannophilus. It is hypothesized that the reduction occurs by virtue of increased ethanol respiration (Ref. 41). Under strictly anaerobic conditions, P. tannophilus produces essentially the same net yield of ethanol from xylose— after correcting for the amount of xylose going into xylitol—as it does from glucose (Table 4). The

NOVEL DEVELOPMENTS IN BIOREACTOR DESIGN AND SEPARATIONS TECHNOLOGY 205

amount of carbon going into xylitol is deducted from the calculation, because it accumulates early in the fermentation pathway and essentially represents sugar that is not metabolized. The yield of xylitol decreases under aerobic conditions and increases under anaerobic conditions (Ref. 28). 3.2 Effect of Glucose on Ethanol Yields from Xylose The aerobic ethanol yield from xylose can be improved by adding small amounts of glucose during the fermentation (Table 5). By using this approach, a high rate of ethanol production can be achieved with relatively little ethanol loss. The improvement in yield is not observed under anaerobic conditions, and control experiments show that adding glucose at the low concentrations employed does not affect the rate of xylose assimilation. So the observed improvement in yield is attributed to a decrease in the rate of ethanol respiration (Ref. 28). Table 4: Product yields of P. tannophilus from glucose and xylose under anaerobic conditions (Ref. 28) ethanol*

co2*

xylitol*

acetic*

Ethanol (xo-xi)**

Xylose 0.33 0.32 0.30 0.03 0.47 Glucose 0.48 0.44 0 0.02 0.48 *Yield expressed as g product ÷ g sugar consumed. **Yield expressed as g ethanol ÷ (g xylose consumed—g xylitol produced). Table 5: Effect of glucose additions on the yield of ethanol from xylose under aerobic conditions (Ref. 28) ethanol yield g/g* 4.5% xylose alone 0.28 4.5% glucose alone 0.43 3% xylose+0.5% glucose 0.41 at T0, 24 and 48 h 0.43 *g ethanol/g sugar consumed **actual yield divided by theoretical (0.51 g/g)×100

% of theoretical** 55 84 81 (xylose) 84 (glucose)

3.3 Effects of Nitrate on Ethanol Production Nitrate increases the levels of PPP enzymes in yeasts, fungi, and plant cells (Refs. 10, 45–57). The enhancement occurs because the PPP is the primary

206 ENERGY APPLICATIONS OF BIOMASS

source of NADPH and because nitrate reductase requires large amounts of NADPH for nitrogen assimilation. It was for this reason that we examined the ability of nitrate to stimulate the rate of xylose fermentation in P. tannophilus (Ref. 48). Although nitrate stimulated the specific aerobic xylose fermentation rate, cells grew slower on nitrate, and under anaerobic conditions, the specific rate of ethanol production of nitrate-grown cells was appreciably lower. The anaerobic effect was dependent on both pregrowth on nitrate and the presence of nitrate in the medium. 3.4 Effects of Nitrate and Xylitol on Strain Selection in P. tannophilus Xylitol and nitrate were used in an indirect enrichment and selection method to obtain improved xylose fermenters. These restrictive carbon and nitrogen sources were used to help select vigorous rather than crippled mutants. P. tannophilus tends to accumulate xylitol during growth on xylose, so it was used as a sole carbon source on the assumption that xylitol utilization is a rate-limiting step. P. tannophilus grows slower on nitrate than on other more readily assimilated nitrogen sources, and nitrate-grown cells exhibit higher specific aerobic fermentation rates than ammonia-grown cells. Moreover, nitrate is known to induce higher levels of PPP enzymes; therefore, by using it as a nitrogen source, the cells are fully induced for PPP enzymes. Any faster-growing mutant would have metabolic capacities beyond the normal adaptative range of the parent. For these reasons, cells able to grow well on nitrate should be capable of generating NADPH at an elevated rate. Hence, nitrate was chosen as the sole nitrogen source. Taken together, these restrictive conditions slowed growth so that a minimum of 7 to 10 days was required for significant growth to occur in liquid or on solid media (Ref. 49). Strains capable of relatively rapid growth on nitrate+xylitol media were generally much better xylose fermenters than the parent strain or mutants obtained under less restrictive conditions (Fig. 6). The strains derived from nitrate +xylitol enrichment produce ethanol twice as fast and in 30% better yield than the parent strain under aerobic conditions. Moreover, they have a specific fermentation rate 50% greater under anaerobic conditions (Fig. 7). These strains are stable under repeated subculture, and the enrichment and selection method has been successfully employed several times with P. tannophilus. Other approaches to obtaining improved mutants of xylose-fermenting yeasts have been attempted, including selecting strains of Candida sp. for relative growth rates on xylose and xylitol media (Ref. 50) and selecting strains of P. tannophilus for low rates of ethanol assimilation (Ref. 51). Both of these methods have led to improved xylose-fermenting strains.

NOVEL DEVELOPMENTS IN BIOREACTOR DESIGN AND SEPARATIONS TECHNOLOGY 207

3.5 Candida shehatae as a Rapid Xylose Fermenter Although mutation and selection methods have been successful in obtaining incremental improvements in the xylose fermentation rates of laboratory strains, enrichment and screening of yeast strains from natural sources has led to the identification of C. shehatae as a species capable of fermenting xylose at four to five times the specific rate of P. tannophilus (Ref. 31). Candida shehatae produces up to 3.8% (w/w) ethanol from 16% D-xylose (Fig. 8) and about 5% ethanol from 16% D-glucose (Fig. 9). In comparison to P. tannophilus, which forms much more ethanol on D-glucose than on D-xylose, with C. shehatae the final ethanol concentrations on these two sugars and the ethanol yields (after deducting xylitol production) are about the same (Table 6). Table 6: Product yields from xylose and glucose (g/g) (Ref. 25) sugar conc. (%)

xylose

ethanol

xylitol

glucose EtOH/(Xo-Xi)*

4 0.307 0.052 8 0.267 0.151 12 0.264 0.236 16 0.242 0.274 20 0.255 0.230 *ethanol/(xylose consumed—xylitol formed) .

cells

ethanol

cells

0.322 0.313 0.343 0.334 0.328

0.096 0.069 0.047 0.040 0.039

0.322 0.345 0.350 0.312 0.253

0.100 0.072 0.044 0.035 0.026

Pichia stipitis is the sexually perfect stage of C. shehatae. Although no published study has yet made a detailed comparison of the fer-mentative capacities of various strains of these two forms, work in this laboratory has shown that for the most part, they are very similar. As much variation exists among strains of each form as between the anomorph and the teleomorph. In other research, separate studies have compared fermentation characteristics of P. tannophilus with either C. shehatae (Ref. 50) or P. stipitis (Ref. 53) and found C. shehatae or P. stipitis to be the better fermenter in each case. Strain improvement is proceeding with C. shehatae. One of the first approaches tried was to apply the same enrichment and selection method used successfully with P. tannophilus. According to conventional taxonomic tests, C. shehatae is unable to use nitrate as a nitrogen source (nitrate negative). We have found that some strains will grow to a limited extent in nitrate+xylitol medium, but this approach has not been successful with this organism. The fastest xylosefermenting strain we have obtained to date is an unstable petite-like variant derived from C. shehatae ATCC 22984 by selection on urea+xylitol medium (Ref. 54).

208 ENERGY APPLICATIONS OF BIOMASS

Certain strains of C. shehatae exhibit marked small colonies remin-iscent of the petite mutation in Saceharomyces when they are grown on urea+ xylitol agar. Conventionally, the petite designation refers to strains showing small colonies on glucose and deficiencies in respiratory metabolism. Many of the petite-like colonies of C. shehatae ATCC 22984 on xylitol agar show diminished respiratory capacity as judged by the tetrazolium overlay method (Ref. 55). The petite-like colonial morphology of C. shehatae is expressed on both xylose and glucose. However, strains designated grande on xylitol exhibit slightly smaller colonial diameters when growing on glucose. Conversely, strains designated petite on xylitol show larger colonial diameters when growing on glucose. The transitions between small and large colonial sizes occur in both directions (Table 7). Table 7: Frequencies of petite and grande colonies derived from single isolated grande or petite colonies of Candida shehatae ATCC 22984 when grown on three different carbon sources (Ref. 54) source of cells

urea +xylitol agar freq. dia. (mm)

urea+xylose agar freq. dia. (mm)

urea+glucose agar freq. dia. (mm)

Grande

0.86 0.14 0.92 0.03 0.05

0.84 0.16 0.94 0.06

0.92 0.08 0.93 0.07

Petite

1.44±0.20 1.12±0.22 0.97±0.11 0.41±0.12 1.44±0.10

1.23±0.16 0.71±0.13 1.46±0.26 0.67±0.28

1.38±0.20 0.64±0.23 1.76±0.41 0.44±0.31

The xylose fermentation characteristics of petite and grande strains are related to respiratory activities. When a tetrazolium agar overlay is applied to colonies growing on urea+xylitol agar, five different colony types can be distinguished (Table 8). Some of these strains, occurring in low frequency, exhibit a small colony diameter and a strong tetrazolium reaction on xylitol. These strains are poor ethanol producers, but they form other products. The petite colonies showing a weak tetrazolium reaction on xylitol tend to produce less xylitol and glycerol, but the higher overall yield of all products formed by grande tetrazolium-positive strains tends to suggest that these strains have lower endogenous respiratory activity when growing fermentatively. Neither grande nor petite strains show significant tetrazolium reactions on xylose. Preliminary studies in my laboratory have shown that a similar petite-like variation occurs in strains of P. stipitls. An improved understanding of this petite-like variation should eventually contribute to the isolation of yeast strains capable of fermenting xylose economically under practical conditions.

NOVEL DEVELOPMENTS IN BIOREACTOR DESIGN AND SEPARATIONS TECHNOLOGY 209

Table 8: Average colony diameters, tetrazolium reactions, and fermentation patterns of C. shehatae ATCC 22984 strains exhibiting different characteristics on xylitol agar (Ref. 54) freq.

dia. (mm)

tetrazolium reaction

ethanol

g/g*

g/g h**

g/g/*

g/g/*

0.08 2.44±0.30 3+ 0.03 1.61±0.14 4+ 0.84 1.15±0.01 1+ 0.01 0.92± 0.05 4+ 0.04 0.65±0.19 1+ *g product/g xylose consumed. **g product/g dry wt cells • h. ′ other products formed.

0.23 0.20 0.18 0.11 0.17

0.09 0.05 0.07 0.02 0.08

xylitol

glycerol

0.26 0.40 0.14 0′ 0.10

0.11 0.16 0.04 0′ 0.04

3.6 Comparison of Various Xylose-Fermenting Yeast Strains Various researchers have used many different media and cultural conditions in studying different yeast strains for their abilities to ferment xylose. While these strains doubtless possess different optima for ethanol production, it is useful to compare them under a single set of fermentation conditions. My lab has recently done such a comparison. Results show that although the mutant strains of P. tanophilus and Canida sp. performed better than their parent strains, all strains of C. shehatae were better than any other strain tested. These results show that further strain development with C. shehatae as well as enrichment and selection of new isolates should continue. 4 CONCLUSIONS 1. Xylose is widely available in angiosperm residues and more readily recoverable than glucose from lignocellulosic materials. 2. Although a two-stage isomerization and fermentation of xylose is feasible, direct fermentation of xylose to ethanol can proceed at a higher specific rate and is more likely to have a lower overall cost. 3. Xylose fermentation rates and ethanol yields are still much lower than commercial glucose fermentations, but they are improving. For specialized situations where waste xylose streams constitute a disposal problem, fermentation to ethanol may be economical. 4. Biochemical, genetic, and strain selection studies have only recently been undertaken, and it is expected that they should result in better strains and fermentation conditions.

210 ENERGY APPLICATIONS OF BIOMASS

5 ACKNOWLEDGEMENT The author wishes to thank Henry Schneider and his coworkers at the National Research Council, Ottawa, Ontario for useful discussions and for sharing references and preprints of unpublished data. 6 REFERENCES 1. 2. 3. 4. 5.

6. 7. 8.

9.

10.

11. 12.

13.

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Rydholm, S.A. ‘Pulping processes’, John Wiley and Sons, 1965. Browning, B.L. ‘Composition and chemical reactions of wood’, The Chemistry of Wood, B.L.Browning, ed., John Wiley and Sons, 1963. Sjöström, E. ‘Wood chemistry, fundamentals and applications’, Academic Press, 1981. Sloneker, J.H. ‘Agricultural residues, including feedstock wastes’, Biotechnol. Bioeng. Symp., vol. 6, 235–250, 1976. Krull, L.H. and Inglett, G.E. ‘Analysis of neutral carbohydrates in agricultural residues by gas-liquid chromatography’, J.Agric. Food Chem., vol. 28, 917–919, 1980. Wilkie, K.C.B. ‘The hemicelluloses of grasses and cereals’, Adv. Carbohyd. Chem. Biochem., vol. 36, 215–264, 1979. Chiang, C. and Knight, S.G. ‘Metabolism of D-xylose by molds’, Nature, vol. 188, 79–80, 1960. Horecker, B.L., Rosen, O.M., Kowal, J., Rosen, S., Scher, B., Lai, C.Y., Hoffee, P. and Cremona, T., ‘Aspects of yeast metabolism,’ A.K. Mills, ed., F.A. Davis Co., 1968. Jeffries, T.W., ‘A comparison of Candida tropicalis and Pachysolen tannophilus for conversion of xylose to ethanol’, Biotechnol. Bioeng. Symp., vol. 12, 103–112, 1982. Bruinenberg, P.M., van Dijken, J.P. and Scheffers, W.A. ‘A theoretical analysis of NADPH production and consumption in yeasts’, J.Gen. Microbiol, vol. 129, 953–964, 1983. Jeffries, T.W. ‘Conversion of xylose to ethanol under aerobic conditions by Candida tropicalis’, Biotechnol. Lett., vol. 3, 213–218, 1981. Bruinenberg, P.M., de Bot, P.H.M., van Dijken, J.P. and Scheffers, W.A. ‘The role of redox balances in the anaerobic fermentation of xylose by yeasts’, Eur J.Appl. Microbiol. Biotechnol., vol. 18, 287–292, 1983. Sehneider, H., Wang, P.Y., Chan, Y.K. and Maleszka, R. ‘Conversion of D-xylose into ethanol by the yeast Pachysolen tannophilus’, Biotechnol. Lett., vol. 3, 89–92, 1981. Bruinenberg, P.M., de Bot, P.H.M., van Dijken, J.P. and Scheffers, W.A. ‘NADHlinked aldose reductase: the key to anaerobic alcoholic fermentation of xylose by yeasts’, Appl. Microbiol. Biotechnol., vol. 19, 256–260, 1984. Wang, P.Y., Shopsis, C. and Schneider, H. ‘Fermentation of a pentose by yeasts’, Biochem. Biophys. Res. Comm., vol. 94, 248–254, 1980.

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Jeffries, T.W. ‘Utilization of xylose by bacteria, yeasts and fungi,’ Adv. Biochem. Eng./Biotechnol., vol. 27, 1–32, 1983. Chen, W.-P. ‘Glucose isomerase (a review), part 1’, Proc. Biochem., vol. 15, 30–35, 1980. Chen, W.-P. ‘Glucose isomerase (a review), part 2’, Proc. Biochem., vol. 15, 36–41 1980. Hsiao, H.-Y., Chiang, L.-C., Chen, L.-F. and Tsao, G.-T. ‘Effects of borate on isomerization and yeast fermentation of high xylulose solution and acid hydrolysate of hemicellulose’, Enzyme Microb. Technol., vol. 4, 25–31, 1982. Venkatasubramanian, K. ‘High fructose corn syrup: plant design and process economies’, in Enzymes, The Interface Between Technology and Economics, J.P.Danehy and B.Wolnak, eds., Marcel Dekker, 1978. Jeffries, T.W. ‘Fermentation of xylulose to ethanol using xylose isomerase and yeasts’, Biotechnol. Bioeng. Symp., vol. 11, 315–324, 1981. Maleszka, R., and Schneider, H. ‘Fermentation of D-xylose, xylitol and D-xylulose by yeasts’, Can. J.Microbiol., vol. 28, 360–363, 1982. Suihko, M.-L. and Dravic. ‘Pentose fermentation by yeasts,’ Biotechnol. Lett., vol. 5, 107–112, 1983. Chiang, L.-C, Gong, C.-S., Chen, L.-F. and Tsao, G.T. ‘D-xylulose fermentation to ethanol by Saccharomyces cerevisiae’, Appl. Environ. Microbiol., vol. 42, 284–289, 1981. Suihko, M.-L. and Poutanen, K. ‘D-xylulose fermentation by free and immobilized Saccharomyces cerevisiae cells’, Biotechnol. Lett., vol. 6, 189–194, 1984. Roman, G.N., Jansen, N.B. and Tsao, G.T. ‘Ethanol inhibition of Dxylulose fermentation by Schizosaccharomyces pombe’, Biotechnol. Lett., vol. 6, 7–12, 1984. Margaritis, A. and Bajpai, P. ‘Direct fermentation of D-xylose to ethanol by Kluyveromyces marxianus strains’, Appl. Environ. Microbiol., vol. 44, 1039–1041, 1982. Jeffries, T.W., Fady, J.H. and Lightfoot, E.N. ‘Effect of glucose supplements on the fermentation of xylose by Pachysolen tannophilus’, Biotechnol. Bioeng., 1984. Slininger, P.J., Bothast, R.J., Black, L.T. and McGhee, J.E. ‘Continuous conversion of D-xylose to ethanol by immobilized Pachysolen tannophilus’. Biotechnol. Bioeng., vol. 24, 2241–2251, 1982. Slininger, P.J., Bothast, R.J., Van Cawenberge, J.E. and Kurtzman, C.P. ‘Conversion of D-xylose to ethanol by the yeast Pachysolen tannophilus’, Biotechnol. Bioeng., vol. 24, 371–384, 1982. du Preez, J.C. and van der Walt, J.P. ‘Fermentation of D-xylose to ethanol by a strain of Candida shehatae’, Biotechnol. Lett., vol. 5, 357–362, 1983.’ Maiorella, B.L., Blanch, H.W. and Wilke, C.R. ‘Economic evaluation of alternative ethanol fermentation processes’, Biotechnol. Bioeng., vol. 26, 1003–1025, 1984. Rogers, P.L., Phil, D., Lee, K.J. and Tribe, D.E. ‘High productivity ethanol fermentations with Zymomonas mobilis’. Proc. Biochem., vol. 15, 7–11, 1980. Kreger-van Rij, N.J. W., ed. ‘The yeasts, a taxonomic study (3rd edition)’, Elsevier Science Publishers, 1984. Barnette, J.A., Payne and Yarrow, D. ‘The yeasts’, Cambridge University Press, 1983.

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Toivola, A., Yarrow, D., van den Bosch, E., van Dijken, J.P. and Scheffers, W.A. ‘Alcoholic fermentation of D-xylose by yeasts’, Appl. Environ. Microbiol., vol. 47, 1221–1223, 1984. Maleszka, R., Wang, P.Y. and Schneider, H. ‘Ethanol production from Dgalactose and glycerol by Pachysolen tannophilus’. Enzyme Microb. Technol., vol. 4, 349–352, 1982. Neirinck, L.G., Maleszka, R. and Schneider, H. ‘The requirement of oxygen for incorporation of carbon from D-xylose and D-glucose by Pachysolen tannophilus’, Arch. Biochem. Biophys., vol. 228, 13–21, 1984. Maleszka, R. and Schneider, H. ‘Involvement of oxygen and mitochondrial function in the metabolism of D-xylulose by Saccharomyces cerevisiae’, Arch. Biochem. Biophys., vol. 228, 22–30, 1984. Scheffers, W.A. and Wiken, T.O. ‘The Custers effect (negative Pasteur effect) as a diagnostic criterion for the genus Brettanomyces’, Antonie van Leeuwenhoek, vol. 35, A31-A32, 1969. Tyagi, R.D. ‘Participation of oxygen in ethanol fermentation’, Proc. Biochem., vol. 19, 136–141, 1981. Hoppe, G.K. and Hansford, G.S. ‘The effect of microaerobic conditions on continuous ethanol production by Saccharomyees cerevisiae’ , Biotechnol. Lett., vol. 6, 681–686, 1984. Maleszka, R. and Schneider, H. ‘Concurrent production and consumption of ethanol by cultures of Pachysolen tannophilus growing on D-xylose’, Appl. Environ. Microbiol., vol. 44, 909–912, 1982. Bruinenberg, P.M., de Bot, P.H. M., van Dijken, J.P. and Scheffers, W.A. ‘The role of redox balances in the anaerobic fermentation of xylose by yeasts’, Eur. J.Biotechnol., vol. 18, 287–292, 1983. Hankinson, O. and Cove, D.J. ‘Regulation of the pentose phosphate pathway in the fungus Aspergillus nidulans’, J. Biol Chem., vol. 249, 2344–2353, 1974. Jessup, W. and Fowler, M.W. ‘Interrelationships between carbohydrate and nitrogen metabolism in cultured plant cells, Part 3’, Effect of the nitrogen source on the pattern of carbohydrate oxidation in cells of Acer pseudoplatanus grown in culture’, Planta, vol. 137, 71–76, 1977. Osmond, C.B. and Rees, T.A. ‘Control of the pentose phosphate pathway in yeast’, Biochim. Biophys. Acta., vol. 184, 35–12, 1969. Jeffries, T.W. ‘Effect of nitrate on the fermentation of xylose and glucose by Pachysolen tannophilus’, 1983 Biotechnology, vol. 1, 503– 506, 1983. Jeffries, T.W. ‘Mutants of Pachysolen tannophilua showing enhanced rates of growth and ethanol formation from D-xylose’, Enzyme Microb. Technol., vol. 6, 254–258, 1984. McCracken, L.D. and Gong, C.-S. ‘D-xylose metabolism by mutant strains of Candida sp.’, Adv. Biochem. Eng./Bioteohnol., vol. 27, 34–55, 1983. Schneider, H. Personal communication, 1984. du Preez, J.C., Prior, B.A. and Monteiro, A.M.T., ‘The effect of aeration on xylose fermentation by Candida shehatae and Pachysolen tannophilus’, Appl. Microbiol. Technol., vol. 19, 261–266. Dellweg, H., Rizzi, M., Methner, H. and Debus, D. ‘Xylose fermentation by yeasts. 3. Comparison of Pachysolen tannophilus and Pichia stiptis’, Biotechnol. Lett., vol. 6, 395–400, 1984.

NOVEL DEVELOPMENTS IN BIOREACTOR DESIGN AND SEPARATIONS TECHNOLOGY 213

Fig. 1. Metabolism of xylose by Candida utilis in a closed oxidative pentose phosphate pathway

Fig. 2. Metabolism of xylose by Pachysolen tannophilus in a balanced anaerobic pentose phosphate pathway 54. Jeffries, T.W. ‘Unstable petite and grande variants of Candida shehatae’, Biotechnol. Lett., in press, 1984. 55. Ogur, M., St. John, R. and Nagai, S. ‘Tetrazolium overlay technique for population studies of respiration deficiency in yeast’, Science, vol. 125, 928–929, 1957.

214 ENERGY APPLICATIONS OF BIOMASS

Fig. 3. Comparison of glucose and xylose fermentations by Pachysolen tannophilua under low aeration Xylose fermentations are shown with closed symbols, glucose with open. Culture conditions employed 50 ml of 0.17% yeast nitrogen base without ammonium sulfate or amino acids (YB, Difco) plus 0.27% urea as a nitrogen source shaken in 125 ml Erlenmeyer flasks at 100 rpm. The incubation temperature was 30°C. Sugar concentrations: 4.5% (, ); 6% (, ); 9% (, ); 12% (, ).

Fig. 5. Fermentation of D-glucose by Candida shehatae ATCC 22984 Culture conditions were the same as Fig. 4. Solid lines= ethanol concentrations; broken lines= sugar concentrations.

NOVEL DEVELOPMENTS IN BIOREACTOR DESIGN AND SEPARATIONS TECHNOLOGY 215

Fig. 4. Fermentation of D-xylose by Candida shehatae ATCC 22984 Culture conditions employed YB plus 0.65% Bacto Peptone and 4%, 8%, 12%, 16%, or 20% (w/vol) of Dcylose (Sigma). Solid lines= ethanol concentrations; broken lines= sugar concentrations; other conditions same as Fig. 3.

Fig. 7. Ethanol production from 4.5% D-xylose by mutants of P. tannophilus. Symbols are the same as in Fig. 6.

216 ENERGY APPLICATIONS OF BIOMASS

Fig. 6. Correlation of colony diameters on YB urea+xylitol (2%) agar with specific anaerobic fermentation rates Data points are averages of triplicate cultures for individual strains, (), P. tannophilus NRRL Y-2460; (), nitrate-enriched, nitrate plated strains; (), nitrate-enriched, urea plated strains; (), urea-enriched, nitrate plated strains; () ureaenriched, urea plated strains; (), fastest growing strain obtained from nitrate enrichment and nitrate plating.

NOVEL DEVELOPMENTS IN BIOREACTOR DESIGN AND SEPARATIONS TECHNOLOGY 217

Fig. 8. Comparison of D-xylose fermentations by P. tannophilus and Candida sp. strains Cultures contained 6% D-xylose inYB+ urea medium. Other conditions given in Fig. 3.

218 ENERGY APPLICATIONS OF BIOMASS

Fig. 9. Comparison of D-xylose fermentations by several strains of Candida shehatea Cultures contained 6% D-xylose in YB+urea medium. Other conditions given in Fig. 3.

NOVEL DEVELOPMENTS IN BIOREACTOR DESIGN AND SEPARATIONS TECHNOLOGY C.D.SCOTT* *Chemical Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee

1 INTRODUCTION Much of the recent activity in the new biotechnology is associated with the production of high-value products at a relatively small scale. However, the more conventional fermentation industry has a long history of large-scale production of commodity-type products. This type of technology will gain increasing importance as the production of fuels and chemicals from renewable resources again becomes economically viable. Although many advanced research and development concepts will have applications in either type of biotechnology, the primary interest here will be to consider the large-scale systems, with particular emphasis on bioconversion systems. In general, an integrated bioconversion system using advanced concepts may have several processing steps, including preparation of the feed material, production of the biocatalyst, the bioconversion step, and product concentration and purification (Fig. 1). The heart of the system is the bioreactor; however, separation processes also play important roles in several of the possible processing steps. Recent advances in more efficient separation processes and advanced bioreactor concepts will be discussed in greater detail. 2 SEPARATIONS Separation processes are important components in many of the possible processing steps in advanced biotechnology (Fig. 1). They may include: • Fractionating biomass feed materials to supply necessary process substrates • Removing or recovering particulates in suspension such as microorganisms, microbial fragments, raw material fractions, or nonbiological solids • Recovering and concentrating macromolecules such as proteins and enzymes that will either be the end product or be used as biocatalysts

220 ENERGY APPLICATIONS OF BIOMASS

• Recovering and purifying soluble, low-molecular-weight substances such as alcohols, organic acids, and other oxychemicals that may be the desired products. Using current technology, separation costs may constitute 25% to 40% of the overall manufacturing cost of fermentation products, particularly if distillation is used (Ref. 1). In such cases, the necessary process separations are also the dominant energy users. Advances are being made in all of the areas mentioned above; however, recovery of the fermentation product will be the focal point of this paper. The major goal is either to remove large quantities of water from the dilute fermentation product or to extract the small concentration of product from gross quantities of water. The use of solvent extraction systems and solid sorbents will probably have the most important future impact on the concentration and purification of lowmolecular-weight fermentation products. Such approaches may be considered as replacements of distillation or an important adjunct to distillation. 2.1 Solvent Extraction In solvent extraction, the fermentation broth is contacted with an appropriate immiscible organic extractant in a countercurrent contactor in which one of the phases is dispersed in the other (Fig. 2). The depleted broth exits from one end of the contactor, while the solvent containing the product leaves the other end of the contactor. Product is recovered from the solvent by a thermal process, evaporation or distillation, and the solvent can then be recycled back to the system. In this case the thermal process is less energy-intensive than the usual distillation process, since a solvent of low volatility can be used and, of course, huge quantities of water do not have to be removed. For solvent extraction to be successful, the solvent of choice must not only be relatively immiscible in water (this prevents solvent loss) and inexpensive, but it should also have high capacity and specificity for the organic product. Research in this area is primarily focused on determining the most effective extractants for specific applications, with particular emphasis on the recovery of ethanol. To date, higher-molecular-weight alcohols and organic acids, especially with branched chains, seem to be the best candidates (Fig. 3) (Refs. 2, 3). 2.2 Solid Sorbents The use of a solid sorbent for removing fermentation products from a dilute broth is somewhat similar in concept to the use of solvent extraction. However, the unit operation is somewhat different. In this case, the fermentation broth would percolate through a stationary packed bed of the sorbent, leaving the product

DIESEL FUEL VIA INDIRECT LIQUEFACTION 221

behind on the packing (Fig. 4). After the sorbent bed had been loaded with product, it would be taken off line (at least two packed beds would be required for continuous operation) and regenerated. Again, a thermal process would probably be used; in this case, however, the solid sorbent would be extremely nonvolatile and, in turn, thermal efficiencies should be quite high. Current research is oriented toward developing a sorbent material that has high capacity and high specificity. Both synthetic molecular sieves and neutral resins show promise for this application (Fig. 5) (Refs. 4, 5), and there will undoubtedly be other candidates in the future. 2.3 Integrated Processes The most optimum separation systems may include a combination of two or more concepts into a single processing step. For example, sorption or solvent extraction in conjunction with distillation may have an advantage over either single process. It is also beneficial to combine the primary separation step with the fermentation step in a single processing vessel. This would result in a decrease in the total number of processing steps, but it also might enhance the fermentation step since product inhibition could be decreased. 3 ADVANCED BIOREACTOR SYSTEMS Most conventional, large-scale bioreactor systems are batch-fed stirred tanks; however, important research advances are being made on innovative, new concepts that would be more efficient, controllable, and productive. It would be desirable to have continuous bioreactors with high concentrations of the biocatalyst (e.g., microorganisms) that also operate in a multistage mode. The latter point is important in instances where product or substrate inhibition affects the microbial kinetics. 3.1 Continuous Columnar Bioreactors Columnar systems operating continuously with high concentrations of immobilized biocatalysts appear to be very attractive as high-productivity bioreactors. Such systems with large biocatalyst particles and low product flow rates will operate as fixed-bed bioreactors, while systems with small biocatalyst particles and higher flow rates will be operated as fluidlzedbed bioreactors in which the particles are suspended by the upflow of the feed stream (Fig. 6). Continuous columnar systems have been shown in the laboratory to be many times more productive than batch-stirred tanks, (Refs. 6, 7, 8) and they can apparently be scaled up in a straightforward manner (Fig. 7).

222 ENERGY APPLICATIONS OF BIOMASS

3.2 Immobilization of Biocatalyst Advanced columnar bioreactor systems require that the biocatalyst be immobilized onto or into a particulate that remains in the reactor, even at high flow rates. In some fixed-bed systems, especially for wastewater treatment, a biological film is formed on the external surface of the packing material (Ref. 9). However, systems for producing commodity-type chemicals will require a much better controlled immobilization technique. Of particular interest is the incorporation of the biocatalyst into a solid support matrix. For example, natural gels, such as carrageenan, can be used to entrap microorganisms into biocatalyst beads (Fig. 8) (Refs. 7, 10). Such materials, when used in a fluidized-bed bioreactor for producing ethanol from glucose, have been shown to increase productivity by over an order of magnitude when compared with conventional technology (Ref. 8). 4 CONCLUSIONS Advanced technological approaches promise to significantly increase the productivity and to decrease the cost and energy requirements of biological processing systems. This seems to be especially true for largescale fermentation for commodity-type chemicals. As feed materials for bioprocess become competitive with fossil-based processes, a resurgence in the bioconversion industry will undoubtedly follow. REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

Emyanitoff, R. and Weinert, H.M. ‘Genetic Eng. News’, vol. 8, 9, 1984. King, C.J. personal communication, 1984. Roddy, J.W. and Coleman, C.F. ‘Ind. Eng. Chem. Fundam’, vol. 22, 51, 1983. Pitt, W.H., Haag, G.L. and Lee, D.D. ‘Biotech. Bioeng.’, vol. 25, 123, 1983. Lencki, R.W., Robinson, C.W. and Moo-Young, M. ‘Biotechnol. Bioeng. Synp. No. 13’, 617, 1983. Margaritis, A. and Wallacea, J.B. ‘Biotechnol. Bioeng. Symp. No. 12’, 147, 1982. Scott, C.D. ‘Ann. N.Y. Acad. Sci.’ vol. 413, 448, 1983. Scott, C.D. ‘Biotechnol. Bioeng. Symp. No. 13’, 287, 1983. Genung, R.K. et al. ‘Biotechnol. Bioeng. Symp. No. 8’, 329, 1979. Venkatsubramanian, K. (ed.) ‘Immobilized microbial cells’, ACS Symp. Series No. 106, American Chemical Society, Washington, D.C., 1979.

DIESEL FUEL VIA INDIRECT LIQUEFACTION 223

Fig. 1. Typical processing steps in an advanced bioconversion system

224 ENERGY APPLICATIONS OF BIOMASS

Fig. 2. Simplified solvent extraction system for product recovery and concentration

Fig. 4. Simplified solid sorbent separation system for product recovery and concentration Fig. 3. Potential ex tractants for ethanol from dilute aqueous solutions KD=(concentration in organic phase/ concentration in aqueous phase), a=(concentration of ethanol/ concentration of water) in extradant

DIESEL FUEL VIA INDIRECT LIQUEFACTION 225

Fig. 5. Ethanol breakthrough curve for a 72.5-mL packed bed of molecular sieves operating at 21°C and 185 mL/h

226 ENERGY APPLICATIONS OF BIOMASS

Fig. 6. Two types of columnar bioreactor systems

DIESEL FUEL VIA INDIRECT LIQUEFACTION 227

Fig. 7. Large-scale 16-in.-diameter fluidized-bed bioreactor that was scaled up from laboratory data for a 1-in.-diameter system

228 ENERGY APPLICATIONS OF BIOMASS

Fig. 8. Carrageenan gel beads containing Z. mobllis cells at approximately the theoretical concentration

DIESEL FUEL VIA INDIRECT LIQUEFACTION J.L.KUESTER* *Arizona State University, Tempe, Arizona

1 INTRODUCTION A thermochemical conversion process to convert various biomass materials to diesel type fuels has been under development at Arizona State University (ASU) since 1975. An indirect liquefaction approach is used, i.e., gasification to synthesis gas followed by liquefaction of the synthesis gas. The primary virtue of an indirect liquefaction approach for cellulosic feedstocks is that oxygen contained in the materials is easily separated. Thus the hydrocarbon liquid product is free of oxygenated compounds and can therefore be tailored to match transportation fuel products currently derived from petroleum. Approximately 100 biomass materials are being studied as received from private industry, government laboratories, and other university laboratories. The feedstock candidates include industrial wastes, agricultural and forest residues, and crops that could be deliberately grown for energy conversion purposes. The product of the process is a liquid hydrocarbon transportation grade fuel similar to diesel. This can be upgraded to high-octane gasoline via catalytic reforming if desired. The products should be compatible with existing engine designs and fuel distribution and marketing systems. The major virtue of the process is that a renewable, often lowvalued material is used as the feedstock to produce a quality product. Current efforts on the project are designed to maximize diesel fuel yields for a variety of feedstocks of commercial interest and to establish corresponding reliable, reproducible mass and energy balances. Auxiliary tasks include alternative feedstock assessment, alternative product development, system simplification and automation, gasification and liquefaction catalyst development, environmental assessment, and scale-up to a 10 ton/day facility. The primary purpose of the larger scale facility is to produce a sufficient amount of product for applications testing and to minimize the risk to a commercial scale. With the present status of the process, a profitable scale would require about 300 ton/day of feedstock. This number is expected to decrease with further improvements in the process that are currently in progress in the research

230 ENERGY APPLICATIONS OF BIOMASS

laboratories. The ultimate goal is a portable unit that could be moved to appropriate biomass sites. 2 CONVERSION SYSTEM DESCRIPTION A schematic of the ASU indirect liquefaction system is shown in Fig. 1. Photographs of the conversion system and control room are shown in Figs. 2 and 3. The existing laboratory-scale system has a capacity of approximately 25 lb/h (11 kg/h) of feedstock. Target product yields are 50 to 100 gal of diesel type fuel per ton of dry, ash-free feedstock. Continuous processing is employed. While the unit is small, the processing steps and procedures are commercially realistic. The gasification system is composed of two fluidized beds with connecting, circulating, solid-transfer loops. One fluidized bed is used as a feedstock pyrolyzer while the other bed (regenerator) operates in a combustion mode to heat the circulating solids media. Both inert solids (sand) and catalytic materials are under investigation. The fluidized bed approach allows for efficient heat transfer, continuous solids recirculation, and elimination of a combustion zone in the pyrolyzer and thus avoids gas cleanup steps. Cellulosic (biomass) feedstocks are continuously fed to the pyrolyzer and flashed to a synthesis gas consisting of paraffins, olefins, carbon monoxide, hydrogen, and carbon dioxide. The gas passes through a cyclone-scrubber system to a compressor. From the compressor, the gas can be distributed to the pyrolyzer and/or liquefaction reactor. Additional gas candidates for fluidizing the pyrolyzer are steam and off gas from the downstream reactors. Studies to date indicate that the use of recycled pyrolyzer gas is not desirable for fluidizing the pyrolyzer due to the increased effective residence time with respect to the reactive gas components. The regenerator is fluidized by air and recycled gas from the pyrolyzer and/or downstream reactors. The off gas from the regenerator is passed through a cyclone-scrubber system before being vented. The liquefaction system contains a catalytic reactor to produce paraffinic liquid fuel. Both fluidized bed and slurry phase systems are being studied. These reactor types allow for effective temperature control in the presence of the significant exothermic heat of reaction and also offer the possibility of continuous regeneration via external circulation if necessary. The fluidized bed is a simpler system than the slurry phase system type. The slurry phase system, however, offers the potential advantages of better temperature control, longer catalyst life, residence time flexibility, and improved gas-solid contacting. In both reactor types, the reactive components in the synthesis gas (olefins, carbon monoxide, hydrogen) are converted to a primary paraffinic hydrocarbon phase and a secondary alcohol-water phase. The off gas from this reactor accumulates an appreciable amount of normal paraffins plus carbon dioxide and exhibits an enhanced heating value as compared to the synthesis gas (due to hydrogen and carbon monoxide depletion).

THERMAL CONVERSION OF BIOMASS: PROGRAESS AND PROSPECTS 231

Work also has been performed on the system to produce a high-octane gasoline via catalytic reforming of the paraffinic liquid phase in a conventional, fixed-bed system using commercial catalysts. To achieve a commercial octane range, a liquid yield loss of about 20% occurs in the reforming step. The off gas is of high heating value (~2300 Btu/ft3) due to the presence of C1–C4 normal paraffins, and thus some of the yield loss could be recovered via recycling of this gas in the overall process. Typical operating conditions for the process steps are as follows: pyrolyzer fluid bed/slurry phase liquefaction reactor Temperature (°C) 600–800 250–300 Pressure (psig) 0–1 140 Residence time (s) 2 18

reformer 490 400 11

3 PROCESS STUDIES The basic objective of the project is to maximize yields of high-quality, oxygenfree liquid hydrocarbon fuel suitable for transportation use in existing engines. The oxygen in the biomass is converted to carbon monoxide, carbon dioxide, and water in the gasification step. In the liquefaction step, the carbon monoxide is converted to paraffinic hydrocarbons, water, and normal propanol via the following reactions:

With proper manipulation of the reactions, the oxygen in the biomass will end up in water, carbon dioxide, and normal propanol. Carbon dioxide and water will be vented from the gasification system regenerator, and an immiscible alcoholwater phase will be separated from an oxygen-free paraffinic hydrocarbon phase. Past and present efforts on the project have been aimed at optimizing the implementation of this scheme via process variable studies involving the assessment of various feedstocks and factor studies on the conversion system. The feedstock materials studied in our laboratory are received from private industry, municipalities, government laboratories (from various nations), and other university laboratories. A photograph of the feedstock storage area (milled materials) is shown in Fig. 4. A range of characterization data for the various

232 ENERGY APPLICATIONS OF BIOMASS

biomass feedstocks is given in Table 1. In general, all the feedstocks will produce a quality product. Yields will depend on the synthesis gas composition potential of the feedstocks. Some variations have been observed; for example, cork materials produce a high olefin content, while Euphorbia lathyris gives a high H2/ CO ratio. A fairly wide variation in ash content and composition has also been observed, which affects ash handling facilities, possible catalytic effects, and disposal options. Table 2 lists various conversion factors being studied. Many of these studies are performed in separate, stand-alone experimental systems. Liquefaction catalyst development work, for example, is performed in six parallel, small-scale reactors (Figure 5). Synthesis gas compositions experienced in the laboratory for a wide range of feedstocks and operating conditions are listed in Table 3 ; typical product characteristics are compared with commercial fuel oil and shown in Table 4. Table 1: Feedstock characteristics (dry basis) characteristic

ranges

Heating value, Btu/lb Ash, wt % Protein, wt % Polyphenol, wt % Oil, wt % Hydrocarbons, wt % Suberin, wt % Lignin, wt % Cellulose, wt % Lipids, wt % Elemental analysis, wt % C H 0 N S

7,400–12,700 0.1–35.9 0.1–25.3 0.1–20.2 0.03–9.20 0–10.4 0.5–26.6 7.8–28.8 17.7–46.7 5.1–14.9

Table 2: Factor studies Gasification: 1. Reactor system configuration 2. Feedstock characterization 3. Heat transfer media/catalyst 4. Fluidization gas composition

37.7–60.9 4.7–8.8 28.9–54.4 0.3–1.7 < 0.01

THERMAL CONVERSION OF BIOMASS: PROGRAESS AND PROSPECTS 233

5. Residence time 6. Temperature 7. Pressure 8. Recycle effects Liquefaction: 1. Catalyst composition 2. Catalyst preparation method 3. Catalyst calcination, reduction, pretreatment 1. Reactor system configuration 5. Conversion temperature 6. Conversion pressure 7. Conversion residence time 8. Feedgas composition 9. Recycle effects Table 3: Synthesis gas composition (mol %)

Hydrogen Carbon monoxide Olefins Paraffins Carbon dioxide

range

typical

10–53 6–60 5–39 6–33 4–26

32 32 10 15 11

Table 4: Properties of Fischer-Tropsoh product and commercial fuel oils

Specific gravity Gravity, API° Boiling point range,

commercial fuel oils

Fischer-Tropsch product

no. 2 diesel kerosene JP–4

almond prunings feedstock

guayule bagasse

0.8360

0.8108

0.7586

0.7902

0.7950

37.8

43

55

47.6

46.5

336 410 479 47.8

147 302 438 48.3

235 352 471 45.3

238 414 535 55.7

21676

22440

19354

21043

0F

10% 369 evaporated at 50% 458 90% 563 Calculated cetane 45.9 index Heating value, Btu/lb 19383

234 ENERGY APPLICATIONS OF BIOMASS

Factor studies in the gasification system indicate that low pressure and residence time, ~1500°F, and a combination of steam (hydrogen source) and liquefaction reactor off gas (paraffin source for cracking to olefins and hydrogen) for fluidization are favorable. The fluldized solid candidates are still under investigation to satisfy the criteria of operational reliability and selectivity (catalysts). For the liquefaction system, the best catalyst is an impregnated cobalt catalyst with conversion conditions of 500°F, 140 psig, 15– to 3–s single-pass residence time, and 3/1 recycle (weight basis) . The H2/CO mole ratio in the synthesis gas can be manipulated over a broad range for a given feedstock (say 0. 5 to 8.0), but the olefin composition is heavily feedstock dependent. Typical synthesis gas compositions considered achievable for virtually any biomass feedstock are indicated in Table 3. Without any post reactor refining, the product quality is most similar to JP-4 jet fuel due to the presence of materials in the C7–C10 range. A simple distillation will produce a product in the No. 2 diesel fuel range. Further “tuning” of process conditions is expected to establish the flexibility to manipulate the product quality without the necessity of a separation step. Details of the various feedstock and factor studies performed in the laboratory are presented elsewhere (Refs. 1–5). 4 CONTINUING WORK Tasks in progress in the laboratory include product yield improvement, throughput optimization, alternative feedstocks and products assessment, environmental compatibility, process simplicity, and automation. A contract has been let to Ultrasystems, Inc. to design a larger scale version (10 ton/day of feedstock) of the process with the primary purpose of minimizing the risk at a commercial scale. The continuing objective is to minimize the break-even commercial scale and thus increase the number of applications for the process technology. 5 ACKNOWLEDGEMENTS The research project described in this paper is currently sponsored by the U.S. Department of Energy, Office of Industrial Programs and the U.S. Department of Agriculture. International Business Machines Corporation (IBM) has provided computational equipment via a joint study program with Arizona State University.

THERMAL CONVERSION OF BIOMASS: PROGRAESS AND PROSPECTS 235

Fig. 1. Indirect liquefaction system schematic (RC=recycle)

REFERENCES 1. 2. 3.

4.

5.

Kuester, J.L. ‘Conversion of cellulosic wastes to liquid fuels, DOE interim report’, COO-2982–108, Contract No. DE-AC02–76CS40202, May 1984. Kuester, J.L. ‘Diesel fuel from biomass’, in Proceedings of the Energy from Biomass and Wastes VIII Symposium, Institute of Gas Technology, 1984. Kuester, J.L. ‘Liquid hydrocarbon fuels from biomass’, Chapter 8 in Biomass as a Non Fossil Fuel Source, D.L. Klass, ed., ACS Symposium Series 144, American Chemical Society, 1980. Kuester, J.L. ‘Conversion of cellulosic wastes to liquid fuels’, Chapter 15 in Energy from Waste—Vol. I, T.C. Franiewicz, ed., Ann Arbor Science Publishers, 1980. Kuester, J.L. ‘Diesel fuel from biomass via indirect liquefaction’, presentation at BioEnergy 84, Gotenborg, Sweden, June 1981.

236 ENERGY APPLICATIONS OF BIOMASS

Fig. 2. Integrated laboratory scale indirect liquefaction system

THERMAL CONVERSION OF BIOMASS: PROGRAESS AND PROSPECTS 237

Fig. 3. Control room

238 ENERGY APPLICATIONS OF BIOMASS

Fig. 4. Feedstock storage area

THERMAL CONVERSION OF BIOMASS: PROGRAESS AND PROSPECTS 239

Fig. 5. Liquefaction catalyst test reactors

THERMAL CONVERSION OF BIOMASS: PROGRESS AND PROSPECTS G.F.SCHIEFELBEIN* *Biomass Program Office, Pacific Northwest Laboratory, Richland, Washington

1 INTRODUCTION The Energy Research Advisory Board (ERAB) has estimated that biomass could potentially supply the nation with about 10.5×1015 kJ (10×1015 Btu) by the year 2000 (Ref. 1). Similarily, the Office of Technology Assessment (OTA) has estimated that, with proper resource management and the development of efficient conversion processes, the potential contribution of biomass to U.S. energy demand could range as high as 18×1015 kJ (17×1015 Btu) per year (Ref. 2). To place these estimates in some perspective, they represent, respectively, 14% and 23% of the nation’s total estimated energy consumption in 1982 (Ref. 3). This potential contribution is greater than that of any other renewable energy technology. In addition, biomass is the only renewable technology that can contribute to the need for transportation fuels. Thermochemical conversion processes are expected to contribute a majority of the total. In thermochemical conversion elevated temperatures convert biomass materials to more useful energy forms. Wood and crop residues are 96% of the biomass feedstocks available for conversion to liquid and gaseous fuels. Thermochemical processes are capable of converting 85% to 95% of the organic material in these feedstocks with high efficiency and relatively little sensitivity to variations in the feed material. In addition to utilizing diverse biomass resources efficiently, thermal conversion processes can produce a broad spectrum (Fig. 1) of energy products that fit existing U.S. energy use patterns. Biomass feedstocks have unique properties that offer great potential advantages for thermochemical conversion processes. These advantages include: • High Volatility—Biomass feedstocks contain 70% to 90% volatile material for wood versus 30% to 45% for typical coals. Thus a large fraction of most biomass feedstocks can be pyrolyzed (devolatilized) rapidly at relatively low temperatures. Figure 2 compares weight loss due to devolatilization versus temperature for wood and a typical coal.

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• High Char Reactivity—Biomass chars gasify rapidly in the presence of steam at relatively low temperatures. Figure 3 compares the char reactivity of some biomass feedstocks with peat and coal at 800°C and 2.1 MPa (300 psi) in the presence of steam. • Low Sulfur Content—Typical wood feedstocks contain less than 0.2% sulfur, which greatly reduces gas clean-up costs and allows biomass to be reacted in the presence of catalysts without sulfur poisoning problems. • Low Ash Content—Wood and most other biomass feedstocks contain less than 3.0% ash. Ash removal systems are simplified, and ash disposal costs are reduced. These key characteristics of biomass have important implications for the design of thermal conversion processes. Since biomass reacts rapidly at relatively low temperatures, smaller reactor systems are required for a given throughput. This factor, coupled with the lack of requirement for extensive sulfur and ash removal systems, means relatively low capital investment requirements. Small biomass thermal conversion facilities can be built that are economically competitive with other energy resources. More important, these facilities do not have prohibitively large financing requirements. The last point is important since it reduces the amount of capital placed at risk to finance a single project. The Biomass Thermochemical Conversion Program is sponsoring research and development projects on innovative concepts for converting biomass into a spectrum of versatile energy products. Innovative process concepts are being tested and developed in both bench-scale and process research unit (PRU) facilities. As illustrated in Fig. 4, critical process steps are first defined and evaluated in small, bench-scale facilities. If the process innovation continues to show technical and economic merit at the end of this stage, further testing and development are usually conducted in a PRU. Typical PRUs are capable of processing between 900 and 9000 kg (1–10 tons) of biomass per day. The PRU stage allows key process features to be tested and evaluated in a continuous operating mode while optimizing process parameters and obtaining material and energy balances. Scale-up of a process beyond the PRU stage depends on private sector commitment to cost sharing further development such as pilot plants. Currently, several of the projects sponsored by the program are attracting significant interest from the private sector. 2 CURRENT RESEARCH ACTIVITIES The research activities sponsored by the Biomass Thermochemical Conversion Program are directed toward exploiting the unique natural properties of biomass. Currently, this research can be divided into three areas: • Innovative direct combustion technology

242 ENERGY APPLICATIONS OF BIOMASS

• Gasification technology • Liquid fuels technology. A discussion of the complete program can be obtained elsewhere (Refs. 4, 5). Selected projects with nearer term potential for technology commercialization by the private sector are discussed. 2.1 Direct Combustion Technology The Biomass Thermochemical Conversion Program is sponsoring innovative direct-combustion research projects focused on converting the heat released from direct combustion directly into mechanical power. By directly producing mechanical power without the use of an intermediate working fluid, such as steam in a boiler-steam turbine system, operating economies can be realized in industrial-scale applications. Aerospace Research Corporation, Roanoke, Va., is conducting research to determine whether combustion gases from wood can be used to directly power gas turbines. Hot combustion gases from a pressurized, wood-fired suspension burner are passed through a series of cyclones to remove particulate matter and are injected directly into a gas turbine. A general flowsheet for the process is shown in Fig. 5. Trials using a 375-kW combustor/ turbine system indicated no significant signs of erosion or corrosion following 500 hours of operation. Tests showed that 80% to 90% of the particulates entering the gas turbine were less than 0.5µm in diameter. Total particulate loading entering the turbine ranged from 9 to 13 mg per dry normal cubic meter of combustion gas. These results strongly suggest that turbine erosion will not be a problem. A 3000-kW combustor/gas turbine electrical generating system was constructed at Roanoke. Particulate sampling tests conducted during shakedown tests indicated that the particulate loadings entering the turbine are similar to those observed with the smaller system. The 3000-kW system has been moved to Red Boiling Springs, Term., where it will undergo long-term testing while generating electrical power, which will be sold to the Tennessee Valley Authority. Over 80% of the funds for the 3000-kW unit are being provided by the private sector. The Allison Division of General Motors is donating the gas turbine for the project. Figures 6 and 7 show the combustor/cyclone systems and the turbine/generator for the 3000-kW unit. 2.2 Gasification Technology Biomass gasification technology can be divided into processes that produce a low-energy gas with an energy content of 3.5 to 7.0 MJ/m3 (90 to 180 Btu/ft3) and those that produce a medium-energy gas containing 12 to 21.5 MJ/m3 (300

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to 550 Btu/ft3). Several systems for producing low-energy fuel gas are commercially available. The versatility of the fuel gas produced by these lowenergy systems is restricted and subject to the following limitations: • The low heating value of the gas requires that it be consumed at or near the site of production in a close coupled process • Retrofitting oil or natural gas-fired boilers to use low-energy fuel gas usually requires boiler derating or extensive retrofit modifications • The high nitrogen content of low-energy gas precludes its use as a synthesis gas for the production of liquid fuels. The Biomass Thermochemical Conversion Program has recently initiated a small research effort aimed at resolving problems associated with using low-energy gas to fuel internal combustion engines. However, the main thrust of the gasification research and development efforts sponsored by the program is directed toward technology for the production of medium-energy gases. Medium-energy gas is a versatile fuel with the following advantages: • A higher heating value, which allows it to be used in nearly all retrofit applications on a particular industrial site without major modifications or derating problems • Higher flame temperatures, making it suitable for retrofitting processes, where higher flame temperatures are critical • Two to five times the energy density of low-energy gas, allowing it to be transported moderate distances by pipeline at a reasonable cost • Required for the synthesis of derived liquid fuels such as methanol and Fischer-Tropsch liquids, and for the production of pure methane (SNG). Gasification research sponsored by the Biomass Thermochemical Conversion Program is directed toward optimizing medium-energy gasifiers to produce fuel gas or synthesis gas for subsequent conversion to liquid fuels, and developing innovative reactor designs that reduce or eliminate the requirement for oxygen by exploiting the high reactivity of biomass. Battelle-Columbus Laboratories (BCL) is conducting research on a process to produce a medium-energy fuel gas without requiring pure oxygen. This process involves indirectly heating an entrained bed gasifier by circulating low-density, hot, incandescent sand to the gasifier. The entrained sand and any unreacted char leaving the gasifier are separated from the product gas in a cyclone. The char is burned in a fluidized-bed, air-fired combustor, and the hot sand is recirculated back to the gasifier. A schematic flowsheet for the process is shown in Fig. 8. In previous research using a 15.2-cm (6-in.) diameter gasifier, BCL successfully produced a medium-Btu fuel gas with a heating value of about 18.6 MJ/m3 (475 Btu/ft3) using both wood chips and coarsely shredded bark. This

244 ENERGY APPLICATIONS OF BIOMASS

heating value did not vary significantly for feedstocks containing from 8% to 40/ 6 moisture. Gasifier throughputs of up to 8660 kg/h m2 (1800 lb/h ft2) were achieved. The gasifier was subsequently modified to a 25-cm (10-in.) diameter to more fully examine critical operating parameters. It has operated successfully, obtaining even higher carbon conversions under similar operating conditions than were obtained in the smaller unit. Preliminary estimates indicate that a 17.4 to 21.6 MJ/m3 fuel gas can be produced by this process for less than $4.27/103 MJ ($4.50/106 Btu). The University of Missouri-Rolla is conducting a research program to investigate the technical feasibility of using a metal, fire-tube heat exchanger to provide heat to a fluidized bed gasifier. This concept, suggested by Davy McKee, would allow the production of medium-energy gas or synthesis gases without using expensive oxygen. The university uses a 0.5-m (20-in.) diameter gasifier fitted with an internal heat exchanger consisting of thirty 2.5-cm (1-in.) diameter U-tubes spaced on a 5-cm (2-in.) pitch. Hot combustion gases, produced by burning a portion of the product gas or other fuels such as char, are passed through the heat exchanger. The system has been operated at feed rates up to 205 kg/h (450 lb/h) using 10% moisture wood and temperatures up to 740°C (1365°F). Current research efforts are aimed at determining the optimal process conditions for producing medium-Btu gas and critical design parameters for the heat exchanger. A view of the reactor, with the top removed exposing the heat exchanger, is shown in Fig. 9. The Solar Energy Research Institute (SERI) is developing a pressurized, oxygen-blown, fixed-bed, down-draft gasifier (Fig. 10) for the production of methanol synthesis gas or medium-energy fuel gas. The 0.15-m I.D. gasifier has a nominal capacity of 900 kg of wood per day and a design operating pressure of 1.03 MPa (150 psig). In down-draft operation, pyrolysis tars and oils produced in the upper zone of the bed are forced through the hotter zone at the bottom of the bed where they are cracked. Typical hydrogen to carbon monoxide ratios ranged from 0.5 to 0.8 in the synthesis gas produced. Oxygen consumption averaged 0. 43 kg/kg of wood gasified. The Institute of Gas Technology (IGT) is conducting research on an oxygenblown pressurized, fluidized-bed research gasifier (Fig. 11) designed to produce either a synthesis or fuel gas. The 0.30-m (12-in.) diameter research gasifier has a design capacity of 410 dry kg (900 lb) of wood per hour. The effects of pressure up to 3.5 MPa (500 psia) oxygen consumption are being explored. Data obtained to date indicate that oxygen consumption has ranged from about 0.20 to 0.35 kg/kg of wood (~10% moisture) gasified. Gas heating values have ranged from 11.5 to 14.7 MJ/m3 (292 to 372 Btu/ft3). Hydrogen to carbon monoxide ratios of the gas produced have ranged from 1.8 to 2.2. An important activity associated with this project has been the design and construction of a reliable pressurized wood lock-hopper feeding system.

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2.3 Liquid Fuels Technology The ability to convert biomass to liquid fuels has several advantages over the biomass resource itself. Liquid fuels have a higher energy density and can be transported and stored more economically. Liquid fuels also match existing energy end-use patterns better, particularly in the transportation sector. As noted previously, biomass is the only renewable energy technology that can contribute to the supply of transportation fuels. It must be noted, however, that the molecular composition of biomass can lead to biomass-derived liquid fuels that are different chemically from petroleum fuels. The challenge, then, is to generate high-value liquid fuels from biomass that can both supplement existing liquid fuels and be economically competitive. The liquid fuel research sponsored by the DOE Biomass Thermochemical Conversion Program is directed at: • Identifying reaction pathways and methods to produce high-value intermediates for liquid fuels • Improving yields and quality of liquid fuels • Producing economically competitive fuels in the post-2000 time frame. The liquid fuels research is divided into two primary areas: pyrolysis and direct liquefaction. The differences in these approaches make it possible to generate a variety of fuels ranging from fuel oil substitutes to olefinic/aromatlc hydrocarbons, helping to meet the wide range of demands from the liquid fuel market. Pyrolysis refers to the heating of biomass in the absence of air. Traditionally, it has been used to produce charcoal. Conventional pyrolysis typically produces products consisting of about one third each gases, pyrolysis oil, and solid char. In recent years, the concept of rapid pyrolysis has emerged as a promising alternative. Using rapid heating rates, yields of gases and liquids as high as 95% can be produced. Georgia Tech University, Atlanta, Ga., is conducting research with an entrained flow pyrolysis unit with the goal of generating high yields of liquids at low cost. During 1983, Georgia Tech finished construction of an entrained flow pyrolysis reactor, shown schematically in Fig. 12. The system consists of an upflow, entrained pyrolysis reactor and an oil recovery system that allows partial on-stream fractionation of the product. Experimental operation of the unit is currently under way. Reaction temperatures of 400° to 550°C have been examined and wood feed rates up to 10 kg/h (90 Ib/h) have been obtained. Preliminary results indicate that greater than 50% oils by weight (moisture-free basis) can be obtained, well over double the yields from conventional pyrolysis systems. Results from related research indicate that yields as high as 60% by weight may be obtained as operating parameters are optimized. While the

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pyrolysis oils are quite different chemically than petroleum liquids, the low projected costs of the biomass oils indicate that upgrading may be economically feasible. SERI is investigating the use of an ablative reactor for fast pyrolysis to determine how to obtain the high heat fluxes needed for rapid pyrolysis and to investigate fundamental reaction behavior. The unique reactor -supplies heat for reaction by the ablation of biomass particles forced against a hot reactor wall. Heat-up rates of up to 500,000°C/sec can be obtained at the sample surface. Contact of the biomass with the reactor surface converts the biomass into a liquid layer, which subsequently is vaporized. A schematic of the reactor system is shown in Fig. 13. The initial products formed in the reactor section are primary pyrolysis vapors that can be condensed as pyrolysis oils at yields of about 60%. The primary tars can also undergo secondary cracking in a vapor cracker to form highvalue products such as benzene, toluene, xylene, and ethylene, plus carbon monoxide and hydrogen. Biomass can also be converted to liquid fuels via direct liquefaction technology. Direct liquefaction research at this time is based primarily on a concept proposed by the Pittsburgh Energy Technology Center (PETC). In this concept, biomass is mixed with recycle wood oil and sodium carbonate catalyst along with a mixed H2/CO reducing gas of mixture. The mixture is injected into a high-pressure vessel at 21 MPa (3000 psi) and heated to about 350°C. During 1981, tests of the PETC process in a DOE research facility located at Albany, Ore., confirmed the technical feasibility of this approach. Over 5000 kg (11,000 Ib) of oil resembling No. 6 fuel oil were produced in one run alone. However, the results indicated that the process is not now economically competitive, partly because of the large recycle oil requirement. The Biomass Thermochemical Conversion Program is attempting to improve the competitiveness of direct liquefaction by: • Improving the economics of direct liquefaction through the use of increased feedstock slurry concentrations • Improving product quality by reducing oxygen content and molecular weight. The University of Arizona, Tucson, is conducting research on an advanced concept for direct liquefaction that would use very concentrated biomass slurries. The goal of this work has been to use a polmer extruder as a slurry feeding/pumping device. The modified extruder/feeder system is capable of handling slurries as concentrated as 60% wood solids in biomass oil. Conventional systems, by comparison, typically cannot handle slurries containing over about 25% wood. During 1984, the university designed and began constructing an integrated extruder/static mixer liquefaction system. The static mixer is expected to allow adequate mixing and agitation of the viscous slurries. Construction of the unit is nearing completion, and shakedown operation is expected in early 1985. A schematic flowsheet of the Arizona reactor system is shown in Fig. 14.

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Fig. 1. Thermochemical conversion can provide a broad spectrum of products

3 ADDITIONAL INFORMATION Detailed descriptions of all the research and development projects funded by the Biomass Thermochemical Conversion Program are given in Ref. 5. REFERENCES 1. 2. 3. 4.

5.

‘Solar energy research and development: federal and private sector roles, draft report of the solar R&D panel of the energy research advisory board’, Sept. 2, 1982. ‘Energy from biological processes, volume I—biomass resource base’, Office of Technology Assessment, Congress of The United States, Washington, D.C. ‘Energy projections to the year 2010’, Office of Policy, Planning and Analysis, U.S. Department of Energy, DOE/PE-0029/2, Oct. 1983. Schiefelbein, G.F., Stevens, D.J. and Gerber, M.A. ‘1983 annual report: biomass thermochemical conversion program,’ PNL-5096, Aug. 1984. National Technical Information Service, U.S. Department of Commerce, Springfield, VA. ‘Proceedings of the 16th biomass thermochemical conversion contractors’ meeting’, May 8–9, 1984, Portland, OR. CONF-8405157. National Technical Information Service, U.S. Department of Commerce, Springfield, VA.

248 ENERGY APPLICATIONS OF BIOMASS

Fig. 2. Biomass is far more volatile than coal

Fig. 3. Biomass chars gasify very rapidly compared to peat and coal chars

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Fig. 4. Biomass thermochemical conversion program appproach

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250 ENERGY APPLICATIONS OF BIOMASS

Fig. 5. Flowsheet for combustor/gas turbine/generator system at Aerospace Research Corp.

Fig. 6. Aerospace combustor/cyclone system

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Fig. 7. Layout of Aerospace turbine/generator unit

Fig. 8. Schematic flowsheet of Battelle-Columbus gasifier

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252 ENERGY APPLICATIONS OF BIOMASS

Fig. 9. University of Missouri-Rolla gasification reactor

Fig. 10. SERI downdraft gasification unit

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Fig. 11. Schematic flowsheet of IGT gasifler

Fig. 12. Flowsheet for entrained flow pyrolysls system at Georgia Tech

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254 ENERGY APPLICATIONS OF BIOMASS

Fig. 13. Schematic view of SERI ablative pyrolysis reactor

Fig. 14. Schematic of direct liquefaction unit at the University of Arizona

INSTALLATION OF A 3-MW WOODBURNING GAS TURBINE SYSTEM AT RED BOILING SPRINGS, TENNESSEE J.T.HAMRICK* *Aerospace Research Corporation, Roanoke, Virginia

1 INTRODUCTION Wood-burning research begun in 1976 led to the building and testing of a 375kW wood-burning gas turbine system (Ref. 1). Experience with that system resulted in the building and testing of a 3000-kW system. The gas turbine had long been used with liquid and gaseous fuels and operability with wood had been demonstrated more recently. The main question to be answered, that of turbine life, could have been answered to some extent by long-term testing of the 375kW system. However, gas turbines differ in their designs. Those differences may not greatly affect the life of turbines powered by liquid or gaseous fuels, but with wood there is the possibility of erosion by solid particles, and the number of turbine stages, gas velocities through the turbine passages, and turbine inlet gas temperature may make a significant difference in turbine life. Therefore, it was decided to build a system and test it in a location where power could be generated and sold during life testing of the turbine. The selection of a gas turbine, location of the operating site, construction of the system, and preliminary operating results are discussed in this report. 2 GAS TURBINE SELECTION Factors that were considered in gas turbine selection were size, adaptability to an external burner and wood fuel, availability, efficiency, and maintainability. Both foreign and domestic gas turbines were evaluated. 2.1 Gas Turbine Size An economic study of the 375 to 500-kW gas turbine quickly eliminated it as a candidate. The next size turbine—one that produces 3,000 to 5,000 kW—is popular for offshore oil drilling rigs, gas pipeline compressors, and emergency

256 ENERGY APPLICATIONS OF BIOMASS

power in the United States and abroad. Its major components can be fabricated at the factory and moved to the operating site by common carrier. The wood requirement is only 100 to 150 tons/day, which matches the local wood supply in many areas. The capital outlay is under $2 million. Use of two, three, or four of the 3,000 to 5,000-kW systems at a given location provides for continued operation when one system is shut down for maintenance. The time required for site preparation and installation is about one year, but movement to a new site can be accomplished in two months if the new site is prepared before the move. 2.2 Adaptability to External Burner and Wood Fuel Some gas turbines, especially those of foreign design, employ external burners for liquid and gaseous fuels. Most U.S. designs are of the through flow type used on airplane engines. In those designs, a major factor is the ability to modify the burner section so that air can be ducted away from the compressor to an external burner, and hot gases can be ducted back to the turbine. The only 3000-kW engine manufactured in the United States that is readily adaptable to an external burner is the Allison model 501 K. The introduction of a higher pressure drop between the compressor and turbine can adversely affect the matching of these two components. In a gas turbine engine, the compressor and turbine are sized so that at the operating speed and pressure of the compressor, the angle of air flow into the compressor blades matches that of the blade angle within 6 to 8 degrees. If the air flow rate drops off, the angle of flow into the blades may become large enough to stall the blades. Continuous operation of a stalled compressor can result in structural failure of the blades. Thus, detailed performance curves for the compressor and turbine are needed to determine if changes in the compressor operating point due to ducting, combustor, and filter losses will result in compressor stall. With the use of wood there is an additional shift in the operating point. A greater mass of wood than oil or gas is required for a given gas turbine output because of the lower heating value of the wood. In addition, the moisture in the wood results in an increase in the mass flow. Both increase the flow through the turbine, and consequently there is a higher pressure demand from the compressor (Ref. 2). The data required to make an evaluation of engine performance with external combustion system pressure drop and wood fuel are not easily obtainable from the gas turbine manufacturers, especially foreign suppliers. Allison supplied complete data on the 501 K engine. A computer program was written to monitor the 501 K engine performance, and the results showed that stable operation of the engine could be expected at design speed.

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2.3 Gas Turbine Efficiency Three foreign gas turbines with external combustors were evaluated as candidates for the 3000-kW system. All had published efficiencies of 24% or less, compared to 28.3% for the model 501 K engine. With the increased pressure loss through the combustor, the computed efficiency for bone-dry wood is 27.3%. With 35% moisture wood, the efficiency drops to 26.4%. In Australian experiments (Ref. 3) it was shown that injection of steam into the hot gas stream ahead of the turbine could significantly increase the power output and overall efficiency of the gas turbine. GM-Allison’s tests on the 501 K engine showed similar results. Calculations were made for the system performance on wood with the injection of 4 Ib steam/s at 405°F generated by turbine exhaust gases. By maintaining a turbine inlet temperature of 1700°F, an overall efficiency of 31% can be achieved with a power output of 5000 kW. 2.4 Maintainability Availability of replacement parts and the speed with which they can be replaced favors aircraft derivative engines as they are designed for ease of maintenance. The foreign engines that were evaluated could not be easily replaced and repairing of the turbine in the field would be lengthy. The turbine section of the 501 K, which includes the rotating and stationary blades, can be removed and replaced in an eight-hour shift. With a solids burning system in which there is a chance of turbine blade erosion, that feature is very attractive and may prove essential to commercial success. 2.5 Gas Turbine Selection The results of the evaluation were that none of the foreign built engines could compare with the Allison model 501 K for this application. GM-Allison provided a new engine on loan for the application, and the U.S. Air Force provided a T-56 engine on loan as a backup. The Air Force is interested in this test because at least six Air Force bases have enough wood to provide all of their power needs on a continuing basis. 3 SITE SELECTION Two sites were considered for location of the first system. They were Bedford County, Va., and Macon County, Tenn. The objective in considering the two sites was to acquire property along high voltage transmission lines where there was

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easy access to wood waste. Property was acquired in both places. However, after purchase of the property in Bedford County, Va., the avoided cost of electricity paid by the Virginia Electric and Power Company was reduced, making it less economical to install the system there than in Macon County. The Tennessee Valley Authority recommended Macon County because it has a large excess of waste wood, primarily sawdust. Sawmillers in the area have difficulty in disposing of sawdust because the nearest market of any size is 120 miles away. The selected site, which lies along a 69,000-V transmission line, is within the city limits of Red Boiling Springs, Tenn. Contracts have been negotiated with sawmillers in the area for delivery of sawdust for $5 per green ton. A ten-year contract has been signed with the TVA for generation of up to 14, 000 kW of power to be sold at a rate of 4.645¢/kWh peak and 2.925¢/kWh off peak. 4 SYSTEM CONSTRUCTION The realistic testing of a gas turbine with wood as the fuel can most economically be accomplished in a system that converts the fuel to salable electric power. A system with 3000-kW output requires approximately 100 tons of green wood per day (50% moisture). The weighing and processing of that amount of wood requires a sizable outlay of funds for land and equipment. The combustor and filter are comparable in size to the complete gas turbine generator set. To deliver the generated power to the TVA requires an electrical substation complete with switch gear, transformers, oil circuit breakers, metering equipment, and high voltage line switch. To design, build, and assemble all of the required equipment requires a total outlay of approximately $1.8 million. About 22% of the financing of this beneficial project has been contributed by the Department of Energy. Upon completion of the research, the system, with some modification, will be useful as a commercial system. Thus the remaining 78% of the funding has come from private sources. A brief description of the Red Boiling Springs facility follows. Scales that have a 50-ton capacity were installed to accommodate tractortrailer loads of sawdust. The fuel is bark-free hardwood sawdust. Moisture content of random samples is determined for each load as delivered. Some deliveries will be made in self-dumping trucks and some in trailers, which will be unloaded with a front-end-loading tractor at an unloading dock. Approximately one hour is required to unload 25 tons of sawdust. Experience in the research program has shown that outdoor storage of sawdust is satisfactory except under the most inclement conditions of snow and ice. Green sawdust as delivered is fed by a self-unloading enclosed bin to a fluldized bed dryer that uses exhaust gases from the gas turbine as the drying agent. A dryer was built and tested for this research. The information derived from that dryer was furnished to a dryer manufacturer, who designed and

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constructed a dryer for the Red Boiling Springs operation. Sawdust with not more than 30% to 35% moisture leaves the dryer and is fed into a hammermill with a 7/32-in. screen to produce a uniform particle size. The dried and pulverized sawdust is fed to a self-unloading van and then to a live bottom metering bin by means of two elevating augers. Wood is metered from the live bottom bin into the rotary valve above the combustor (see Fig. 1). 5 PRELIMINARY OPERATING RESULTS After operation of the system at low speed, three factors emerged: the height of the firebrick in the secondary combustor, the horsepower requirement during starting, and a decision on the elimination of the second cyclone. After adequate operation had been conducted to take action on the first two problems, preliminary sampling of—the exhaust gases for particle content was conducted by Battelle-Columbus Laboratories. As there was no means of dissipating any significant amount of power generated by the system at Roanoke, it was necessary to forego testing at rated conditions before moving the system to Red Boiling Springs. However, the system was operated at approximately 20% wood feed, maximum operating turbine inlet temperature, and 65% of rated speed, as discussed later. 5.1 Combustor Performance Based on the results obtained with the 375-kW system, the burner for the 3000kW system was designed as shown in Fig. 2. In the initial design the primary combustion chamber was lined from top to bottom with high-density firebrick. The combustor was designed so that products from the primary chamber swirled into the secondary chamber and exited at the top. It was estimated that the burning of any char would be completed within approximately 5 ft of the bottom of the secondary chamber. That portion was lined with firebrick, and the remainder of the chamber was lined with RA253MA alloy. During operation it was determined that some burning at the walls occurred above the 5-ft level, making it necessary to raise the height of the firebrick. Because of uncertainty as to the height at which burning ceased, the full height of the chamber was lined with firebrick. The main side effect of increasing the brick height was a reduction in heat transfer to the combustion air. As can be seen in Fig. 2, air from the compressor enters the top of the secondary chamber and moves through an annular passage down, then across and up to the primary combustion zone. As the air moves, it cools the firebrick while increasing the air temperature. With the stainless steel liner above the firebrick, the inlet temperature of the air at the combustion zone would have been approximately 1000°F at operating conditions. Experimental results to date indicate that with full firebrick lining, the temperature will be 900°

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F. The air temperature at the primary combustion zone and the condition of the wood feed determine the completeness of burning in the primary chamber, which determines the amount of char entering the secondary chamber and the maximum temperature reached on the walls. That temperature must be kept below approximately 2300°F to prevent slagging of the wood ash, which would require slag removal at the bottom of the secondary chamber. With 900°F air, hardwood sawdust may have to be dried to below 25% moisture to avoid slagging. 5.2 Starting Requirements Power from the Oldsmobile starting engine is delivered through the 3000-kW generator shaft and gear box to the gas turbine. Additional power to the gear box is provided by driving the generator as a motor. Below approximately 12,000 rpm in the conventional engine configuration it is necessary to bleed air at the fifth and tenth stages of the compressor to avoid compressor stall. With the long ducting, large combustor, and cyclone filter on the wood burning system, the amount of compressor-generated pressure lost is 8%, compared to 4% for the conventional engine. As a result, it is necessary to bleed additional air from the compressor outlet duct to avoid stall. Without the additional bleed, stalling occurred at 5000 rpm with an engine inlet temperature of 1800°F. The additional bleed together with the greater loss through the external combustor imposes a required starting horsepower for the engine that is much greater than is required for conventional starting. Under standard conditions with JP-4 fuel the conventional 501 KB engine reaches operating speed in under 40 s. The starter contributes no power after the engine reaches 8022 rpm. Above that speed the engine is self-sustaining at a turbine inlet temperature of 1450°F and accelerates to 13,146 rpm; all bleed valves then snap shut from compressor pressure. The fuel is decreased rapidly at that point, dropping the turbine inlet temperature to 999°F. The engine then accelerates to a no-load operating speed of 13,820 rpm. With the wood-fueled system the engine is not self-sustaining at 9300 rpm. It might be possible to partially close the 2-in. bleed valve at the compressor outlet and achieve sustained speed, but the risk of stalling the compressor and damaging the blades is too great to allow experimentation. There was not adequate electrical power at the Roanoke facility to accelerate the engine to a higher rpm without closing the valve. The Oldsmobile engine is estimated to be supplying 160 hp; and the 3000-kW generator, running as a motor on 240 V, is estimated to be supplying 180 hp. At 9300 rpm it is estimated that 340 hp is wasted by dumping through the 2-in. valve. Therefore, it was decided to sample the combustion gases for particulate loading at 8000 to 9000 rpm and postpone complete sampling until after installing the system at Red Boiling Springs, where adequate power is available. An advantage to starting with the 3000-kW generator is the degree of control available. With the unavoidably large volume of hot gases stored in the ducting,

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combustor, and cyclone of the wood-fueled system, there is a great risk that the engine will overspeed if the temperature of the gases exceeds 1000°F when the bleed valves snap shut and the 2-in. valve is closed, even if the wood feed is shut off. The gas generator model 501 KC engine has a bleed manifold with a controllable valve that can be fitted to the model 501 KB engine. However, with the horsepower available with 4160 V, the engine can be accelerated from the 5000 rpm produced by the Oldsmobile engine to 12,000 rpm, where the valves can all be closed with safety. Therefore, the controllable valve system will be needed only for starting where distribution grid power is not available, and a high-horsepower starting engine is used. 5.3 Cyclone Performance The system was designed and built with two cyclones in series. In early experiments a negligible amount of ash was collected in the second cyclone. That led to the consideration of removing it from the system, which also involved the pressure drop through the system and starting requirements. Each cyclone in the system imposes a loss equal to approximately 4% of the pressure generated by the compressor. Eliminating the second cyclone and reducing the pressure drop would not only increase efficiency but would also improve matching of the compressor and turbine during start-up, thus reducing the amount of air to be dumped and the horsepower required for starting. The potential gains in performance from eliminating the second cyclone were judged to outweigh any gains from the collection of particulates by that cyclone. The density and sizes of particles in the hot gas stream entering the turbine were determined by Battelle-Columbus personnel. The gas turbine speed during the sampling period varied from 7100 to 8600 rpm, and the wood feed varied from 800 to 1080 Ib/h with a moisture content of 25%. This is approximately half the amount needed for idling at the design speed of 14,200 rpm. The air flow through the combustor at 8600 rpm with all bleed valves open is 25% of that for design speed. With that air flow rate the wood-feed-to-air ratio approaches that which will exist at the rated speed of 14,200 rpm and load of 3000 kW. The sample results showed the total loading to be 60 ppm with no particle larger than 2.6 µm. Eighty-six percent of the particles are 0.55 µm or less. Allison-GM engineering sets 5 µm as the maximum particle size that can be tolerated by the turbine. The 60 ppm loading includes particles of potassium chromate. The potassium in the wood ash reacts with the chromium in the RA253MA alloy ducting and cyclones to produce greenish yellow potassium chromate dust particles in the hot gas stream. In the 385-kW system, the surfaces of the 310 stainless steel reacted the same way, but formation of the potassium chromate had essentially ceased in the more than 200 h of operation before the hot gas sampling was performed. The 3000-kW system had been operated only 48 h before the sampling occurred.

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However, in the duct leading from the combustor into the cyclone a piece of eleven gauge stainless steel, 11 in. x 22 in., believed to be type 304, was mistakenly used in the fabrication of the ducting and could have contributed heavily to the production of potassium chromate after the remainder of the surfaces had become passified. The piece has now been replaced by RA253MA alloy. Potassium chromate melts at 1775°F. At the point in the ducting at which the sampling took place, the average temperature was 1849°F during the sampling period. During the sampling period, the temperature dropped as low as 1751°F for short periods; at all other times it was above 1830°F. The potassium chromate may have reached that point in the form of an aerosol and condensed in the sampling stream. The average exhaust gas temperature at the turbine outlet during the period was 1174°F, which is slightly higher than the maximum for a 130°F day and 12,400 rpm for the conventional configuration. There were no provisions for accurately measuring the turbine inlet temperature. The ambient air temperature varied from 62°F at the start to 78°F at the finish, and the ambient pressure was 14.3 psia. After 50 hours of operation there was a small amount of slag in the bottom of the secondary chamber, which indicated that the wall temperature had exceeded 2300°F. Three major factors determine the temperature on the walls of the secondary chamber: wood particle size, moisture content of the particles, and combustor outlet temperature. The more rapid combustion with smaller particles reduces the amount of char entering the secondary chamber and, therefore, the wall temperature. Drier particles produce the same result. With higher combustor outlet temperature there is a correspondingly higher temperature on the chamber walls. In the effort to maintain the engine speed of 8000 to 9000 rpm for the sampling run, it was necessary to maintain the average engine inlet temperature at 1849°F. To produce 3000 kw, the anticipated engine inlet temperature is 1750°F. That lower temperature should drop the wall temperature below the slagging point. The ash lock hoppers at the bottom of the cyclone showed some caking of fine particles on the walls. In the work at the Coal Utilization Research Laboratory (Ref. 4), caking of coal ash occurred on the cyclone walls, an occurrence that has not been detected with wood. The caking occurs when water condenses on the walls at start-up. The cyclone is insulated and heats up with the starting gas. The ash lock hoppers were not insulated and depend on conduction from the bottom flange of the cyclone tank to heat them during warm-up. While the caked material flakes off easily upon cooling of the hopper walls, it may prove necessary to insulate them lightly. The ash particles vary from dust size to approximately 0.045 in. in average diameter. The ash density is approximately 80 lb/ft3 . Ash is slightly magnetic, indicating the presence of iron oxide Fe3O4. Wood ash generally contains about 3% iron oxide. There is a tendency for the particles leaving the cyclone to agglomerate at stagnation points in the ducting and turbine. The accumulation is soft, and yields to cleaning with milled walnut hulls. With the wood burning gas turbine, the walnut hulls that go through the compressor do not reach the turbine. As a result, the compressor and turbine must

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be cleaned separately. The frequency of clean-ing the compressor should be the same as for the conventional engine, but the frequency of turbine cleaning is yet to be determined. Cleaning can be performed while the engine is running under full load. Cleaning experiments at 3500 rpm have shown the walnut hulls to be effective in cleaning the turbine blades. In all operations, the turbine exhaust gases were perfectly clear. The 0.031 grains per dry standard cubic foot is less than 10% of the 0.315 grains allowed by the Tennessee Air Pollution Control Board. NOX is the only possible emission that has not been quantified. Should it exceed the 13.4 lb/h allowed by the EPA, water would have to be injected downstream of the combustor, a measure that would not significantly affect performance. 6 SUMMARY OF RESULTS A 3000-kW wood burning gas turbine system has undergone preliminary operation at the Roanoke facility of Aerospace Research Corporation with the following results: 1. It was found necessary to fully line both primary and secondary chambers of the combustor with firebrick. 2. Because the pressure losses in the combustor, cyclone, and ducting were twice those for the conventional combustor, bleeding of air at the compressor outlet was necessary to prevent stalling of the compressor during start-up. 3. Because of the power lost by bleeding air, the required start-up power exceeded the 340 hp available at the Roanoke site. It was decided to sample the gases entering the turbine at 50% to 60% of design speed. Bleeding air from the compressor resulted in a wood-to-air ratio approaching that expected at design speed and load. 4 . To operate at 50% to 60% of design speed with the power available, it was necessary to maintain an average combustor outlet temperature of 1849°F. As a result, the temperature on the walls of the secondary chamber of the combustor exceeded 2300°F, and some slagging occurred. The projected combustor outlet temperature at full load operation is 1750°F. No slagging at that temperature is anticipated. 5. The results of the sampling by Battelle showed a maximum particle population density of 60 ppm in air by weight with no particles larger than 2. 6 m. Eighty-six percent of the particles were 0.55 m or less in size. GMAllison sets 5 m as the maximum particle size that can be tolerated by the turbine. The particle population is less than 10% of the maximum allowed by the Tennessee Air Pollution Control Board. 6. The system is being moved to Red Boiling Springs for full load operation.

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Fig. 1. 3000-kW system being installed at Red Boiling Springs, Tennessee

7 ACKNOWLEDGEMENT This work was performed with support from the U.S. Department of Energy primarily under Contract No. DE-AC05–78-ET20058. The DOE contract managers were Gary F.Schiefelbein and Simon Friedrich. REFERENCES 1.

2.

3. 4.

Hamrick, J.T. and Hamrick, T.M. ‘Development of wood as an alternative fuel for large power generating systems part 1: Research on wood burning gas turbines’, Aerospace Research Corporation Final Report DOE/ET/20058–72, Sept. 1981. Hamrick, J.T. and Owen, Nancy H. ‘Gas turbine performance with high moisture content biomass’ , Presented at Sixth Symposium on Biotechnology for Fuels and Chemicals, Gatlinburg, Tenn., May 1984. Wisdom, J.C. ‘A preliminary examination of a gas turbine cycle with steam dilution’, A.R.L./M.E. Tech. Memo. 188, Nov. 1958. Roberts, A.G., Barker, S.N., Phillips, R.N., et al. ‘Fluidized bed combustion’, NCB Coal Utilization Research Laboratory Final Report, Department of Energy Report FE-3121–15 (a), 1980.

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Fig. 2. Schematic of a 3000-kW combustor

SCALE-UP OF A HIGH-THROUGHPUT GASIFIER TO PRODUCE MEDIUM-BTU GAS FROM WOOD H.F.FELDMANN, M.A.PAISLEY, And H.R.APPELBAUM* *Battelle Columbus Laboratories

1 THE BATTELLE PROCESS A schematic flowsheet of the gasification process under development under U.S. DOE’s sponsorship at Battelle’s Columbus Laboratories is shown in Fig. 1. The process employs a hot-sand phase as a conveying and heat transfer medium. By use of such heat transfer methods, it is possible to produce a 500 Btu/SCF fuel gas from biomass without using oxygen. Wood is fed into the gasifier with no pretreatment except partial drying to utilize sensible heat present in the flue gas from the combustor. The wood (or other biomass) is gasified at throughputs up to 2000 lb/h ft of reactor area to produce the fuel gas and a small quantity of char (typically 20% of the dry wood fed). The char and sand then are removed from the gas phase and transferred to the combustor, where the char is burned. The combustion reactions reheat the sand, which returns to the gasifier to provide the heat for gasification . Heat recovery from product and flue gases provides both process and export steam (or other heat sources as might be needed) in addition to drying incoming wood. Separation of the gasification and combustion zones allows the following two major advantages: • Medium-Btu gas can be produced without requiring an oxygen plant, which is expensive at the scale of most biomass gasification plants. • The heating value of the cooled, cleaned product gas remains constant, independent of the moisture level of the feed. 2 CURRENT TECHNICAL STATUS Early testing of the process was conducted in a 250 lb/h process research unit (PRU) at Battelle’s Columbus Laboratories (Ref. 1). These tests demonstrated that the major virtues of this process approach were:

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• A medium Btu (400 to 500 Btu/ft3) product gas could be produced from wood without requiring an oxygen plant. • A wide range of feedstocks would be handled without pretreatment. • Constant-heating-value gas can be produced regardless of feed moisture level. • Extremely high throughputs can be achieved, resulting in compact, economical reactors. • Heat necessary for gasification can be supplied totally from an entrained, recirculating sand phase. • No by-product char remains after combustion. • Tar production is very low with all feedstocks tested, and since tar is burned in the combustor no net tar production results. The success of these initial studies along with favorable economic projections led to the modification of the PRU to increase the throughput to 12 ton/day by automating the wood feed system and increasing the gasifier diameter to a 10-in. internal diameter. Operation with the larger diameter gasifier in the PRU has been smooth and trouble-free. R-sults are in agreement with those generated in the smaller gasifier except that carbon conversion has somewhat increased over that measured in the smaller gasifier unit. Total operating time in the PRU has been in excess of 7000 h. Since the program is funded for single-shift operation and the unit, once heated up, reaches steady-state conditions in minutes, data gathering runs have ordinarily been limited to single-shift operating periods. However, one extended around the clock operation for a period of 4 days was recently completed with a planned shutdown. This operation demonstrated smooth, stable operation and indicated that a commercial system should be very suitable for automated control. 3 INDUSTRIAL APPEAL AND APPLICATIONS The Battelle process is being developed specificall to exploit the special properties of biomass, namely, its high reactivity and favorable gaseous product spectrum, to produce a high energy density gas in relatively compact conversion equipment. In this way it differs from many other biomass conversion processes that either require oxygen to produce a medium-Btu gas or that produce a lowBtu gas. In addition, unlike single-vessel gasification systems, the heating value of the gas produced is independent of the moisture level of the feed. This is illustrated in Fig. 2, where the heating value of the dry product gas at standard conditions from the Battelle process is compared with that from an air-blown fluid-bed at varying feed moisture levels. The high energy density of the product gas allows it to be utilized in place of natural gas or oil without derating or expensive retrofitting of existing combustion equipment. Therefore the industrial or utility user of this gas can

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maintain natural gas or oil as a backup fuel and use combustion equipment including gas turbines designed for natural gas. On the other hand, utilization of low-Btu gas would require extensive derating, retrofitting, and the utilization of specially designed equipment. The economics of the process have been discussed in previous publications (Ref. 1). Briefly, these evaluations indicate that the process can produce mediumBtu gas at a cost competitive with natural gas or oil even in plants as small as 200 ton/day. More important, these economic evaluations indicate that conversion of biomass to a medium-Btu gas will be cheaper than direct combustion. A comparison of cost and performance projections with various direct combustion-based cogeneration projects indicates a significant advantage for the Battelle-Columbus gasification process in both investment costs per kilowatt of capacity and in kilowatts generated per unit of biomass consumed . 4 IDENTIFICATION OF TECHNICAL RISKS A technical risk is considered to be an unknown that either cannot be determined from operation of the smaller facility or that is calculated based upon extrapolation (as opposed to interpolation) of data from the smaller facility. Technical risks considered important are those that could either affect ultimate operability of the system or significantly affect the economics of operation. Obviously, there are risks other than purely technical risks such as estimated capital costs, interest rates, cost/ availability of raw materials, and many other issues that can affect the overall economics of a new technology. These nontechnical risks, though critical, are project specific and will therefore not be discussed further in this report. Thermal Performance is defined as the ability of the gasification system to produce a given yield of product gas of a given composition per unit of dry wood fed. Thermal performance is, therefore, the single most important factor in determining the economics of the gasification system. The thermal performance, upon which existing cost feasibility evaluations were based, was calculated based on normalizing experimental material balances, published and estimated thermochemical data, and assumed heat losses. Heat losses in the PRU are unavoidably high and are compensated for by burning a supplementary fuel (natural gas) in the fluid-bed combustor. Therefore the thermal performance of larger, commercial-scale process systems must be based on calculations. Since the parameters used in the calculations are all subject to error and/or uncertainty, the thermal performance of a commercial system could deviate from that predicted by calculations based on PRU data. System Availability and Reliability are two parameters that are critical in determining the system’s economics. System availability is defined as simply the time that the system can operate between planned maintenance. Thus, system

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availability influences the economics because it determines the total energy production per unit of capital investment, influences maintenance costs, and requires the user to purchase supplemental energy during downtimes. System reliability is a measure of the entire system, from wood feed to final end use of the cooled, cleaned product gas, to function in an integrated manner. Thus, it is anticipated that reliability will be improved by operation of a fully integrated facility. Obviously, to maximize reliability and determine the system’s potential availability it will be necessary to operate an integrated system that has incorporated into it commercial design philosophy. In addition, the system must operate round-the-clock, day after day in an integrated mode from wood feeding to ultimate use of the cleaned gas. Thus, the scaled-up facility must have the following characteristics: • Employee commercial design philosophy and use components including monitoring and control systems that will be commercially employed • Operate in an integrated mode from wood drying and feeding to final gas utilization • Operate for extended periods of time and be subjected to detailed inspection to determine potential failure due to material selection, design philosophy, operating parameter selection, or other controllable design and operating factors. Biomass Throughput is also extremely important in determining system economics. It determines not only the capital investment required for a particular energy output but also the maximum capacity for a shop-fabricated gasification system. In the PRU facility, heat losses and combustor capacity limit throughput. Therefore it is important that the proposed scaled-up facility proposed be of sufficient size to allow the factors affecting maximum throughput to be determined. The above factors are probably the most important issues that must be resolved by the operation of a scaled-up facility to provide the data needed for the design of a commercial plant. 5 SENSITIVITY OF PROCESS ECONOMICS TO UNKNOWN TECHNICAL FACTORS The actual economics of producing fuel gas will depend on several technical factors that cannot be determined in Battelle’s existing PRU. These factors are summarized below: 1. System Availability. The assumption is that the system will be available 90% of the time or 330 days/yr.

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2. Thermal Performance. Process heat and material balances extrapolate to a cold gas efficiency of up to 72% when the hot combustor flue gas is used to preheat air. 3. System Throughput. Maximum throughput achieved thus far in Battelle’s PRU is about 2000 lb/ft2 h. 4. Capital Costs. The capital cost estimates are based on preliminary designs and the assumptions on system performance outlined above. Development of a firm figure will require a detailed design and determination of actual system performance parameters. In addition, the adequacy of supporting unit operations, such as water treatment and gas clean-up, must be established. It is very possible that actual operating experience will result in the achievement of reduced capital costs. The sensitivity of the above parameters on gas is illustrated in Figs. 3 and 4. These calculations, which should be regarded as generic in that they are not sitespecifie, are intended only to illustrate the influence of changes in the above system parameters on gas price. The following assumptions were used to calculate the gas prices illustrated: • Annual capital related charges= 0.4 × total project capital requirements • Annual operating charges (excluding wood)= $240,000 • Wood cost= $20/ton (as received). Figure 3 shows the combinations of plant availability and thermal performance required to produce a cooled cleaned 450 Btu/ft gas competitive with natural gas. For this illustration, the price of natural gas to an industrial user is assumed to be $4.50/1012 Btu. Figure 4 illustrates the influence of gasifier throughput on gas price. Again, the competing price of natural gas is assumed to be $4.50/1012 Btu. Calculations of this type thus define the performance criteria that must be satisfied in order to economically utilize biomass as a replacement for natural gas or fuel oil. 6 TECHNOLOGY TRANSFER Through presentations, publications, and discussions with visitors to Battelle’s facilities, an interchange of information on industrial needs and how this technology can fulfill these needs is constantly occurring. By far the most important part of this dialogue is the information received regarding the needs of potential industrial users of this technology. These discussions indicate a common pattern of energy needs regardless of the type of industry. These needs can be summarized as follows:

LIST OF ATTENDEES 271

1. Fuel utilization is generally distributed throughout the plant, making a higher energy density gas important in allowing existing distribution systems to be used. 2. A clean fuel is required for direct process heating applications such as kilns and spray dryers. 3. Cogeneration of electricity and steam or hot combustion gases for direct heating applications has a very high priority. Chances for commercialization of Battelle gasification technology now appear excellent because a group of organizations has teamed together to consider scaleup of the technology at the site of an industrial user in the chemical business. This development team includes the following kinds of organizations: • An industrial user • An organization that will arrange financing for, own, and operate plants based on Battelle technology • An A&E firm to do detailed design and plant construction • A firm to fabricate gaslfier and combustion vessels. In addition, a group of companies is considering participation as part of a technical advisory group that will participate in the scale-up project. Battelle will provide the technical support required to make this transfer of DDE-supported technology to the private sector as efficient and risk-free as possible. 7 ACKNOWLEDGEMENTS This work is supported by the Biomass Energy Technology Division of the Department of Energy. Program direction and management is provided by Gary Schiefelbein and Mark Gerber of PNL and Simon Friedrich of DOE in Washington, D.C. REFERENCE 1.

Feldmann, H.F., Paisley, M.A. and Appelbaum, H.R. ‘Conversion of forest residues to a methane-rich gas in a high-throughput gasifier’, 16th Biomass Thermochemical Contractor’s Meeting, Portland, Ore., May 8–9, 1984.

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Fig. 1. Battelle’s biomass gasification system

LIST OF ATTENDEES 273

Fig. 2. Product gas heating value varies significantly with feed moisture in an air blown system

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Fig. 3. Effect of plant availability and thermal performance on gas price

Fig. 4. Effect of reactor throughput on gas price

LIST OF ATTENDEES Richard Abbott DAVEY ENVIRONMENTAL SERVICES 1000 Connecticut Ave., N.W. Washington, D.C. 20036 Betsy Amin-Arsala AGENCY FOR INTERNATIONAL DEVELOPMENT 508 SA-18 Washington, D.C. 20523 David Archer WESTINGHOUSE ELECTRIC CORPORATION 1310 Beulah Road Pittsburgh, PA 15235 Joseph Asbury ARGONNE NATIONAL LABORATORY 9700 South Cass Ave. Argonne, IL 60439 Rajai Atalla INSTITUTE OF PAPER CHEMISTRY P.O. Box 1039 Appleton, WI 54912 Allan N.Auclair CANADA FOREST SERVICE OTTAWA-ENVIRONMENTPLACE VINCENT MASSEY Ottawa, Ontario, CANADA K1A 1G5 Don C.Augenstein ELECTRIC POWER RESEARCH INSTITUTE 3412 Hillview Avenue Palo Alto, CA 94303 Suresh P.Babu INSTITUTE OF GAS TECHNOLOGY 3424 South State Street Chicago, IL 60616 Phillip C.Badger TENNESSEE VALLEY AUTHORITY F4 NFDC Muscle Shoals, AL 35660 David B.Bancroft COUNCIL OF GREAT LAKES GOVERNORS 122 W. Washington Ave. Suite 801A Madison, WI 53703 William R.Barclay SERI 1617 Cole Blvd. Golden, CO 80401 John W.Barrier TENNESSEE VALLEY AUTHORITY F4 NFDC Muscle Shoals, AL 35630 Thomas D.Bath SERI 1617 Cole Boulevard Golden, CO 80401 Don R.Beasley A. T. Kearney Incorporated 699 Prince Street Alexandria, VA 22313 John C.Becker FLOW INDUSTRIES 21414 68th Ave. So. Kent, WA 98032 Steven Beggs ARGONNE NATIONAL LABORATORY 9700 South Cass Ave. Argonne, IL 60439 John R.Benemann GEORGIA INSTITUTE OF TECHNOLOGY School of Applied Biology Atlanta, GA 30332 Peter Benson GAS RESEARCH INSTITUTE 8600 W.Bryn Mawr Ave. Chicago, IL 60631

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Paul F.Bente, Jr. THE BIO-ENERGY COUNCIL 1815 No. Lynn St., Suite 200 P.O. Box 12807 Arlington, VA 22209–8807 Beverly Berger DEPARTMENT OF ENERGY Forrestal Bldg. Rm. 5F–059 Washington, D.C. 20585 Michael K.Bergman APPA Staff Scientist 2301 M. Street, N.W. Washington, D.C. 20037 UNIVERSITY/BIOLOGY Martha D.Berliner VIRGINIA COMMONWEALTH 816 Park Avenue Richmond, VA 23284) Kimon Bird GAS RESEARCH INSTITUTE 8600 W. Bryn Mawr Chicago, IL 60631 Paul R.Blankenhorn PENNSYLVANIA STATE UNIVERSITY 310 Forest Resources Laboratory University Park, PA 16802 Diane Brown GENEX 16020 Industrial Dr. Gaithersburg, MD 20877 Michael D.Brown PACIFIC NORTHWEST LABORATORY P.O. Box 999 Richland, WA 99352 Robert Brown UNIVERSITY OF GEORGIA Chairman: Division of Agricultural Engineering Athens, GA 30602 Stan Bull SERI 1617 Cole Blvd. Golden, CO 80401 William S.Bulpitt GEORGIA INSTITUTE OF TECHNOLOGY O’Keefe Bldg. Rm. 223 Atlanta, GA 30332 Maria K.Burka National Science Foundation 1800 G. Street, N.W. Washington, D.C. 20550 Christopher D.Burnett ILLINOIS NATURAL HISTORY SURVEY 607 E. Peabody Dr. Champaign, IL 61820 James L.Butler USDA SOUTHERN AGRICULTURAL ENERGY CENTER Coastal Plain Experiment Station Tifton, GA 31793 Robert S.Butner PACIFIC NORTHWEST LABORATORY BATTELLE-N.W. P.O. Box 999 Richland, WA 99352 Gustavo Calderon INTER-AMERICAN DEVELOPMENT BANK 801 17th St. N.W. Washington, D.C. 20577 Melvin Calvin UNIVERSITY OF CALIFORNIA Dept. of Chemistry Berkeley, CA 94708 Susan E.Campbell USAID Washington, D.C. 20523 Craig L.Chase BIOMASS ENERGY SYSTEMS CONSULTANT 12840 S.E. 10th Ct., Suite A–4 Bellevue, WA 98006

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Compton Chase-Lansdale AGENCY FOR INTERNATIONAL DEVELOPME Bureau for Private Enterprise PRE/I Room 671/SA14 Washington D.C. 20523 Helena L.Chum SERI 1617 Cole Blvd. Golden, CO 80401 David P.Chynoweth INSTITUTE OF GAS TECHNOLOGY 3424 South State Street Chicago, IL 60616 F.Bryan Clark USDA FOREST SERVICE P.O. Box 2417 Washington, D.C. 20013 L. “Davis” Clements Department of Chem. Engineering University of Nebraska Avery Hall 236 Lincoln, NE 65888–0126 Robert A.Clyde CLYDE ENGINEERING P.O. Box 983 Asheville, NC 28802 William P.Collins UNDER SECRETARY OF ENERGY U.S. DEPARTMENT OF ENERGY CE-1 Forrestal Bldg. Rm. 7B-260 Washington, D.C. 20585 Janet H.Cushman OAK RIDGE NATIONAL LABORATORY P.O. Box X Bldg. 1503 Oak Ridge, TN 37831 Bruce E.Dale COLORADO STATE UNIVERSITY Ag. & Chemical Eng. Ft. Collins, CO 80523 Ford A.Daley DYNATECH R&D COMPANY 99 Erie Street Cambridge, MA 02161 Ed Davis ARKANSAS ENERGY OFFICE One State Capitol Mall Little Rock, AR 72201 Robert S.Davis POWER RECOVERY SYSTEMS INC. 181 Rindge Avenue Extension Cambridge, MA 02140 Raymond Desrosiers TEXAS TECH. UNIVERSITY CHEM. ENGR. DEPT. Lubbook, TX 79404 James P.Diebold SERI 1617 Cole Blvd. Golden, CO 80401 Philip D.Dixon POWER GENERATING INCORPORATED 1407 Texas Street Fort Worth, TX 76102 Dan A.Dolenc RESEARCH INSTITUTE 8600 West Bryn Mawr Avenue Chicago, IL 60631 Roger L.Dougette DAVEY ENVIRONMENTAL SERVICES BIOMASS ENERGY RESEARCH ASSOCIATION (BERA) 1825 K.Street N.W. Washington, D.C. 200006 Larry J.Douglas SERI 1617 Cole Blvd. Golden, CO 80401 Harold M.Draper FLORIDA GOVERNOR’S ENERGY OFFICE 301 Bryant Building Tallahassee, FL 32301–8047

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Victoria L.Duffy POWER ALCOHOL INC. 206 Claremont Avenue Montclair, NJ 07042 James Easterling PACIFIC NORTHWEST LABORATORY Battelle Blvd. Richland, WA 99352 James L.Easterly MERIDIAN CORPORATION 5113 Leesburg Pike, Suite 700 Falls Church, VA 22041 Glenn R.Ekers Dept. of Energy & Economic Development State of Minnesota 150 E. Kellogg, St. Paul, MN 55101 Douglas C.Elliott BATTELLE PACIFIC NORTHWEST LABS P.O. Box 999 Richland, WA 99352 John E.Fisher FIBER FUELS INSTITUTE 310 Cedar Street ST. Paul, MN 55101 Herman Feldmann BATTELLE COLUMBUS LABS 505 King St. Columbus, OH 43201 Sidney I.Firstman GEORGIA TECH 4 BERA Atlanta, GA 30332 James A.Fisher FIBER FUELS INSTITUTE 310 Cedar Street St. Paul, MN 55101 Virgil J.Flanigan UNIVERSITY OF MISSOURI-ROLLA 223 Erl Rolla, MO 65401 Ab Flowers Gas Research Institute 8600 West Bryn Mawr Avenue Chicago, IL 60631 Jo Ellen Force DEPT. OF FOREST RESOURCES UNIVERSITY OF IDAHO Moscow, ID 83843 Patrick J.Fox DOE BONNEVILLE POWER ADM. GENERAL ENGINEER P.O. Box 3621 Portland, OR 97208 James Frank GAS RESEARCH INSTITUTE 8600 W. Bryn Mawr Ave. Chicago, IL 60631 Eugene Frankel House Committee on Science 4 Technology B 374 Rayburn Building Washington, D.C. 20515 Simon Friedrich DOE Forrestal Bldg. Rm. 5F-064 Washington, D.C. 20585 Don Fuqua HOUSE OF REPRESENTATIVES 2269 Rayburn House Office Bldg. Washington, D.C. 20515 Linda Gaines ARGONNE NATIONAL LABORATORY 9700 South Cass Ave. Argonne, IL 60439 Patricia G.Garfinkel House Committee on Science 4 Technology 2321 Rayburn House Office Building Washington, D.C. 20515

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Ellen G.Carver Univ. of Minnesota Bio-Energy Office 1445 Gortner Avenue St. Paul, MN 55108 Earle E.Gavett DIRECTOR OFFICE OF ENERGY U.S. DEPARTMENT OF AGRICULTURE Washington, D.C. 20250 Mark A.Gerber PACIFIC NORTHWEST LABORATORY P.O. Box 999 Richland, WA 99352 Wayne A.Geyer KANSAS STATE UNIVERSITY Forestry Department Call Hall Manhattan, KS 66506 Mohinder Gill USDA ERS NRED 500 12th Street S.W. Washington, D.C. 20250 Paul Gilman Senate Energy Committee U.S. Senate Washington, D.C. 20510 Barbara H.Glenn SERI 1617 Cole Blvd. Golden, CO 80401 Alberto Goetzl NATIONAL FOREST PRODUCTS ASSOCIATION 1619 Massachusetts Ave. N.W. Washington, D.C. 20036 Barry Goldstein NEW MEXICO SOLAR ENERGY INSTITUTE P.O. Box 3 SOL Las Cruces, NM 88003 Stephen C.Grado PENNSYLVANIA STATE UNIVERSITY 206 Ferguson Building University Park, PA 16802 Karel Grohmann SERI 1617 Cole Boulevard Golden, CO 80401 Sigmund Gronich DOE Office of Alcohol Fuels Forrestal Bldg. Washington, D.C. 20585 Suzanne Grundstrom SERI 1617 Cole Blvd. Golden, CO 80401 Marty Gutstein BIOMASS ENERGY TECHNOLOGY DIV. DOE Forrestal Bldg. 1000 Independence Ave. S.W. Washington, D.C. 20585 David O.Hall KING’S COLLEGE 68 Half Moon Lane London, ENGLAND Joseph T.Hamrich AEROSPACE RESEARCH CORP. 5454 Jae Valley Rd. Roanoke, VA 24014 Robert E.Hansen LEGISLATIVE COMMISSION ON MN RESOURCES Room B46 State Capitol Bldg. St. Paul, MN 55155 Dr. Harold Hanson House Committee on Science 4 Technology 2321 Rayburn House Office Building Washington, D.C. 20515 Reid Hartsell DOE Forrestal Bldg. Rm. 5-F-044 1000 Independence Ave. S.W. Washington, D.C. 20585 Sadiq Hasnain NATIONAL RESEARCH COUNCIL DIVISION OF ENERGY Ottawa, CANADA K1A OR6

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Martin C.Hawley Michigan State University Department of Chemical Engineering East Lansing, MI 48824 Robert Hayden 1516 King Street Alexandria, VA 22314 Thomas D.Hayes GAS RESEARCH INSTITUTE 8600 W. Bryn Mawr Ave. Chicago, IL 60631 Roger R.Heyrman New York Power Authority 10 Columbus Circle New York, NY 10038 Alden D.Hinckley OFFICE OF SOLID WASTE, EPA 2908 Mayer Place Alexandria, VA 22302 William Hoagland SERI 1617 Cole Blvd. Golden, CO 80401 Joseph J.Hoffmann BIORESOURCES RESEARCH FACILITY UNIVERSITY OF ARIZONA 250 E. Valencia Rd. Tucson, AZ 85706 Peter Hofmann STONE & WEBSTER ENGINEERING CORP. P.O. Box 2325 Boston, MA 02107 Peter Holihan DOE Forrestal Bldg. Rm. 5-F-064 1000 Independence Ave. S.W. Washington, D.C. 20585 J.Bradford Hollomon NY STATE ENERGY R&D AUTHORITY 2 Empire State Plaza Albany, NY 12223 Randal D.Holtzclaw TENNESSEE VALLEY AUTHORITY Natural Resource Building Norris, TN 37828 John Hornick Rt. 7, Box 198 Stafford, VA 22554 Gary Howland CLONAL PRODUCTS INC. 1056 Captiva Lakeland, FL 33801 Dr. H.M.Hubbard SERI 1617 Cole Blvd. Golden, CO 80401 William F.Hubka SCIENCE APPLICATIONS INC. 1626 Cole Blvd. Suite 270 Golden, CO 80401 Mario Ibacache INTER-AMERICAN DEVELOPMENT BANK 801 17th St. N.W. Washington, D.C. 20577 Larry Icerman New Mexico Research & Development Institute 1220 S. St. Francis Drive Pinion Boulevard, Rm 358 Santa Fe. NM 87501 Steven H.Isaacs Glunderstr 8 D-3000 Hannover 1 WEST GERMANY Thomas W.Jeffries USDA FOREST PRODUCTS LABORATORY P.O. Box 5130 Madison, WI 53705 David B.Johnson U.S. Department of Agriculture Forest Service P.O. Box 2417 Washington, D.C. 20013

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Donald L.Johnson A. E. STALEY MFG. COMPANY 2200 East Eldorado Street Decatur, IL 62525 Janice M.Johnson Trends Publishing National Press Building Washington, D.C. Ted Johnson ENERGY STREAMS INC. RT.1 Box 104 Toivola, MI 49965 Howard Kator Virginia Institute of Marine Science Gloucester Point, VA 23062 David J.Keenan NATIONAL WOOD ENERGY ASSOCIATION P.O. Box 4548 Portsmith, NH 03801 Cater Keithley Wood Heating Alliance 1101 Connecticut Avenue, N.W. Washington, D.C. 20036 Robert P.Kennel ULTRASYSTEMS INCORPORATED 10340 Democracy Lane Fairfax, VA 22030 Richard J.King Science Applications International Inc. 1710 Goodridge Drive McLean, VA 22102 Donald Klass INSTITUTE OF GAS TECHNOLOGY 3424 S. State St. Chicago, IL 60616 Will Klausmeier Biomass Energy Research Association (BERA) 1825 K. Street, N.W. Suite 218 Washington, D.C. 20006 James A.Knight GEORGIA TECH RESEARCH INSTITUTE Georgia Institute of Technology Atlanta, GA 30332 Andrew W.Kramer PROCTER & GAMBLE 6105 Center Hill Rd. Cincinnati, OH 45224 Ulrich Kraus TECHN. UNIVERSITAT MUNCHEN Bayer. Landesanstalt fur Landtechnik Weihenstephan Vottingerstrabe 36 D 8050 Freising, WEST GERMANY James L.Kuester ARIZONA STATE UNIVERSITY ECG-233, Chemical & Bio. Dept. Tempe, AZ 85287 Reiner W.Kuhr STONE & WEBSTER ENGINEERING CORP. 245 Summer St. Boston, MA 02107 Larry J.Kulp WEYERHAEUSER COMPANY WTC1K42 Tacoma, WA 98477 Eric D.Larson CENTER FOR ENERGY AND ENVIRONMENTAL STUDIES Princeton University Princeton, NJ 08544 Mildred R.Lemmons SERI 1617 Cole Blvd. Golden, CO 80401 Robert Lightner YORK-SHIPLEY, INC. 693 North Hills Rd. York, PA 17402

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Edward Lipinsky BATTELLE COLUMBUS LABORATORIES 505 King Avenue Columbus, OH 43201 Kathleen S.Locke GAS RESEARCH INSTITUTE 8600 West Bryn Mawr Avenue Chicago, IL 60631 Michael Z.Lowenstein SERI 1617 Cole Blvd. Golden, CO 80401 Charles MoAuliffe UNIVERSITY OF MANCHESTER Inst. of Science & Technology Manchester, ENGLAND M60 1QD Michael J.McClelland MICHIGAN ENERGY ADMINISTRATION P.O. Box 30228 Lansing, MI 48909 Thomas F.McGowan Georgia Tech. Research Institute Rm. 215 O’Keefe Atlanta, GA 30332 Robins P.Mclntosh SERI 1670 Cole Blvd. Golden, CO 80401 Richard McKenna MERIDIAN CORPORATION 5113 Leesburg Pike, Suite 700 Falls Church, VA 22041 Joe M.McKinney McKINNEY LUMBER INC. P.O. Box C Muscle Shoals, AL 35662 Katherine McKusick NORTH CAROLINA ALTERNATIVE ENERGY CORPORATION P.O. Box 12699 Durham, NC 27709 Dean B.Mahin EDITOR, BIOENERGY SYSTEMS REPORTS POB 591 Front Royal, VA 22630 Neil Malarkey ELTEN ENGINEERING 2128 Wallace St. Philadelphia, PA 19130 Uzi Mann Texas Tech. University Chemical Engineering Department Lubbock, TX 79409 Momtaz N.Mansour MANAGEMENT & TECHNICAL CONSULTANTS INC. 5570–310 Sterrett Place Columbia, MD 21044 Eliseo O.Mariani MARELCO, INC. P.O. Box 5084 Alexandria, VA 22305 Mark Mason ENERGY CONSULT CORP. 310 Cedar St. Paul, MN 55101 Parker D.Mathusa NEW YORK ENERGY RESEARCH & DEVELOPMENT 2 Rockefeller Plaza Albany, NY 12144 Richard P.Mattocks VITA P.O. Box 89 Princeton, WV 24740 Daniel M.Maxfield U.S. Department of Energy CE 131 Washington, D.C. 20585 Marshall R.Mazer BETHLEHEM STEEL CORP. Room 1423 Martin Tower Bethlehem, PA 18016

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Mark A.Megalos North Carolina State University 2004 Biltmore Hall-Western Boulevard Raleigh, NC 27695–8002 Tom G.Melton BUCK RODERS COMPANY INC. 150 Industrial Parkway Industairport, KS 66031 Mark Meo WOODS HOLE OCEANOGRAPHIC INSTITUTION Water Street Woods Hole, MA 02543 Ann Marie Merrall Biomass Energy Research Assoc. 1825 K Street, N.W. Washington, D.C. 20006 Bennett Miller FRED C. HART ASSOCIATES INC. 1110 Vermont Ave. N.W., Suite 410 Washington, D.C. 20005 Charles A.Miller AEROSPACE AND MECHANICAL ENGINEERING DEPT. UNIVERSITY OF ARIZONA Tuscon, AZ 85721 Thomas A.Milne SERI 1617 Cole Blvd. Golden, CO 80401 Narciso M.Mindajao Minnesota Dept. of Energy & Economic Development 980 American Center Building 150 E. Kellogg St. Paul, MN 55101 Allan G.Moon MD FOREST SERVICE 580 Taylor Avenue Annapolis, MD 21401 Joseph R.Moore ENERGY DIVISION ADECA P.O. Box 2939 Montgomery, AL 36105–0939 Richard Moorer DOE OFFICE OF ALCOHOL FUELS Forrestal Building Washington, D.C. 20585 Kieron M.Morkin TENNESSEE VALLEY AUTHORITY TVA Reservation Muscle Shoals, AL 35660 Gregory P.Morris Polydyne, Incorporated Menlopark, CA 94025 James A.Morrison POWER GENERATING INCORPORATED 20 Metekunk Drive Trenton, NJ 08638 Alfred L.Mowery U.S. DEPARTMENT OF ENERGY Mail Stop G-226 Germantown Washington, D.C. 20545 Lyle K.Mudge BATTELLE-NORTHWEST P.O. Box 999 Richland, WA 99352 Joseph A.Mulloney Mueller Associates Inc. 1401 S. Edgewood Street Baltimore, MD 21030 William A.Murphy SAI Suite 1000 800 Oak Ridge Tpke. Oak Ridge, TN 37830 George R.Newkome EXECUTIVE DIRECTOR CENTER FOR ENERGY STUDIES Louisiana State University East Fraternity Circle Baton Rouge, LA 70803–0301

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Russell O’Connell DOE Forrestal Bldg. Rm.5F-064 1000 Independence Ave., S.W. Washington, D.C. 20585 Michael R.Olvey POWER GENERATING INC. 1407 Texas Street Fort Worth, TX 76102 Michael Onischak Institute of Gas Technology 3424 S. State Chicato, IL 60616 Forrest Orr PYROS INCORPORATED 656 Quince Orchard Rd. Suite 304 Gaithersburg, MD 20878 Richard Orrison DOE Forrestal Bldg. Rm. 5F-059 1000 Independence Ave. S.W. Washington, D.C. 20585 Robert J.Parra AGENCY FOR INTERNATIONAL DEVELOPMENT Bureau for Private Enterprise c/o State Department Washington, D.C. 20034 Fred A.Payne CLEMSON UNIVERSITY Agricultural Engr. Dept. Clemson, SC 29631 Robert Perlack OAK RIDGE NATIONAL LABORATORY 4500 N., G-20, P.O. Box X Oak Ridge, TN 37831 Auton L.Perpich State of Minnesota St. Paul, MN 55101 Christine Peterson SRI INTERNATIONAL 1611 N. Kent Street Arlington, VA 22209 Robert S.Pile Tennessee Valley Authority F114 NFDC Muscle Shoals, AL 35660 Delores Pollard DOE Forrestal Bldg. Rm.5F-059 1000 Independence Ave. S.W. Washington, D.C. 20585 Wilson Prichett NRECA 1800 Massachusetts Ave. N.W. Washington, D.C. 20036 Kendall Pye BIOLOGICAL ENERGY CORP. P.O. Box 766 2650 Elsenhower Ave. Valley Forge, PA 19482 Richard Y.Richards SAIC 5113 Leesburg Pike, Suite 710 Falls Church, VA 22041 Marilyn J.Ripin JAYCOR 205 S. Whiting Street Alexandria, VA 22304 Joseph C.Roetheli TENNESSEE VALLEY AUTHORITY F114 NFDC Muscle Shoals, AL 35630 Barry H.Rosen VIRGINIA COMMONWEALTH UNIVERSITY Biology Department 816 Park Ave. Richmond, VA 23284 Seppo K.Ruottu Assistant Professor Ukonuellonkatu 23 Kotka, FINLAND

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John Ryther HARBOR BRANCH INSTITUTE RR 1, Box 196 Ft. Pierce, FL 33450 Pertti J.Sarkomaa Professor Kuusitie 27 Lappeenranta, SF 53810 FINLAND Sue Ellyn Scaletta PASHA PUBLICATIONS INCORPORATED 1401 Wilson Boulevard, Suite 910 Arlington, VA 22209 Robert Scheid BIOMASS ENERGY RESEARCH ASSOC. 1632 30th Street, N.W. Washington, D.C. 20007 Gary Schiefelbein PACIFIC NORTHWEST LABORATORY Box 999 Richland, WA 99352 Charles D.Scott OAK RIDGE NATIONAL LABORATORY P.O. Box X Oak Ridge, TN 37830 John Sealock PACIFIC NORTHWEST LABORATORY P.O. Box 999 Richland, WA 99352 James G.Seay ARGONNE NATIONAL LABORATORY 25W425 Flint Creek Rd. Wheaton, IL 60187 Jan-Olof Sehlin SUNDS DEFIBRATOR AB S-851 94 Sundsvall SWEDEN Eugene Shull NATURAL RESOURCE RESEARCH INSTITUTE University of Minnesota-Duluth Duluth, MN 55812 Oliver C.Sitton UNIVERSITY OF MISSOURI-ROLLA 223 Erl Rolla, MO 65401 Wayne H.Smith DIRECTOR, CENTER FOR BIOMASS ENERGY SYSTEMS University of Florida G040 McCarty, FL 32611 Diane Spindler SERI 1617 Cole Blvd. Golden, CO 80401 Sarah Sprague DOE Forrestal Bldg. Rm. 5F-059 1000 Independence Ave., S.W. Washington, D.C. 20585 George Spring Consultant Box 5 Clarksburg, MD 20871 Ralph M.Stanford ENERGY DIVISION OF ADECA 3465 Norman Bridge Road Montgomery, AL 36105–0939 Meyer Steinberg BROOKHAVEN NATIONAL LABORATORY Upton, NY 11973 Henry D.Steingass AGENCY FOR INTERNATIONAL DEVELOPMENT 508 SA-18 Washington, D.C. 20523 Dan M.Steinway HOUSE COMMITTEE ON SCIENCE & TECHNOLOGY B374 Rayburn House Office Bldg. Washington, D.C. 20515

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John M.Veigel AEC Pamlico Bldg., Suite 212 P.O. Box 12699 Research Triangle Park, NC 27709 Robert Vining NEW ENGLAND CONGRESSIONAL CAUCUS 53 D Street, S.E. Washington, D.C. 20003 George Voss SOLID FUELS, INCORPORATED 4365 Lawn Avenue Western Springs, IL 60558 Carl J.Wallace ARGONNE NATIONAL LABORATORY 1331 H. St. N.W. Washington, D.C. Edward I Wan SCIENCE APPLICATIONS INC. 1710 Goodridge Dr. McLean, VA 22101 Morris Wayman UNIVERSITY OF TORONTO Toronto, CANADA M5S 1A4 Lloyd Weaver ACCUBURN Box 151A River Road Topsham, ME 04086 Rhonda H.Weaver ACCUBURN Box 151A River Road Topsham, ME 04086 Barry E.Welch TIME ENERGY SYSTEMS INC. 12944 Traviah Rd. Patomic, MD 20854 Donald H.White UNIVERSITY OF ARIZONA Dept. of Chemical Engr. Tucson, AZ 85721 Irvin L.White NYSERDA Two Rockefeller Plaza Albany, NY 12223 David Wilson COALITION OF NORTHEASTERN GOVERNORS Washington, D.C. 20003 Walter H.Winnard BATTELLE MEMORIAL INSTITUTE 2030 M Street N.W. Washington, D.C. 20036 Frederick E.Wood MERIDIAN CORPORATION 5113 Leesburg Pike, Suite 700 Falls Church, VA 22041 Richard C.Wright ENERGY SYSTEMS DIV. AQUA-CHEM P.0. Box 421 Milwaukee, WI 53201 Charles Wyman 1617 Cole Blvd. Golden, CO 80401 Beverly Yocum DOE Forrestal Bldg. Rm. 5F-059 1000 Independence Ave., S.W. Washington, D.C. 20585 Jackson Yu ULTRASYSTEMS INCORPORATED 22 Second Street, Third Floor San Francisco, CA 94105 John I.Zerbe FOREST PRODUCTS LABORATORY P.0. Box 5130 Madison, WI 53705

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Fred H.Zerkel INSTITUTE OF GAS TECHNOLOGY 1825 K.Street, N.W., Suite 218 Washington, D.C. 20006 Tim Zorach MAINE OFFICE OF ENERGY RESOURCES Statehouse Station #53 Augusta, ME 04333