IV. COMPARING THE ALTERNATIVES[edit | edit source]
FUELS COMPETING WITH ETHANOL[edit | edit source]
Methanol, butanol, and some types of vegetable oil are three alternatives to ethanol. Both methanol and butanol can be used to replace or extend gasoline or diesel fuel. Vegetable oils, however, are limited to replacing only diesel fuel until further research proves otherwise.
Methanol is the most important alternative. It is a liquid alcohol containing one carbon atom ([CH3]OH). Like ethanol, it is used to replace or be blended with gasoline. Methanol is produced by a chemical process that uses methane as the primary feedstock. Methanol can also be produced from coal or biomass. On a worldwide scale, the methanol production industry is relatively large, and it uses natural gas for feedstock. Methanol production requires high temperature, high pressure, and special catalysts.
This process is much more complex than ethanol production and is generally economical in only very large industrial plants.
Butanol is a four-carbon alcohol. It has two possible chemical structures, depending on the position of the hydroxyl: N butanol ([CH3] [CH2] [CH2][CH2]OH) and 2 butanol ([CH3] [OH1] [CH2] [CH3]). Fermentation produces N butanol. Unlike ethanol or methanol, butanol can substitute for or be blended with diesel fuel in compression ignition engines. It is produced by bacterial fermentation of starch- or sugar-containing feedstocks and purified by distillation. The bacteria produce ethanol and acetone in addition to the principal product, butanol.
The production of butanol has two disadvantages: (1) the fermentation of butanol is difficult compared with that of ethanol; and (2) butanol fermentation produces less-useful fuel per unit of feedstock than ethanol fermentation with yeast. Butanol has been produced commercially under wartime conditions. Today, however, butanol is no longer produced commercially for use as fuel.
CURRENT RESEARCH AND DEVELOPMENT[edit | edit source]
Ethanol fuel production is a well-established commercial technology. But it is also a technology that has room to improve. That is why research and development efforts in ethanol fuel production are ongoing. The research areas relating to this technology that continue to be addressed include (1) feedstock; (2) starch hydrolysis and fermentation process design; (3) ethanol and by-product end uses; and (4) site-specific integration of ethanol production with local agricultural economics.
Feedstock is the most significant cost element in ethanol production. Questions of possible competition for prime agricultural land, and impacts of ethanol production on food supply and distribution are crucial to the social and economic success of this technology. One important area of research is the identification of starch- and/or sugar-containing crops that can be grown on poor land and that require a minimum amount of cultivation and chemical inputs (e.g., fertilizers). Such feedstocks must be compatible with the local climatic conditions, the water resources, and the soil type. They should not disrupt the local agricultural economy. Alternative feedstocks under evaluation in various parts of the world include sago palm, bamboo, sweet potatoes, and honey locust trees. Once potential crops are identified, research will be directed toward increasing yields, adapting crops to specific situations, and developing cultivation, harvest, and storage techniques.
Alternative feedstocks will require research to adapt starch hydrolysis and fermentation equipment and procedures to the particular feedstock characteristics and concentration of fermentable sugars. Fermentation research might also include the selection of yeast strains for improved fermentation efficiency. Improvements could include increased tolerance to high sugar and ethanol concentrations, tolerance to high fermentation temperature, or adaptation to particular feedstock characteristics.
Research needs in ethanol and by-product end uses could include evaluation of technology and economics for uses of ethanol other than as a motor fuel; evaluation of conversion techniques for specific types of engines; and evaluation of specific feedstocks for recovery and use of by-products.
Research on integration of ethanol fuel production with agricultural economies could cover a broad range of topics, including feedstock economics and cultivation, plant and equipment design to fit specific local constraints, process fuel sources, impacts on employment and income distribution, and effects on national balance of payments.
V. INTEGRATION[edit | edit source]
The successful introduction of ethanol fuel production and use in developing countries requires careful planning. The technology must be integrated with local economic conditions, available resources, and potential end use of both the ethanol and its by-products. The operating efficiency of large-scale ethanol plants may be greater than that of small-scale plants. However, this efficiency may be of little value if the plant is too large for the available feedstock and support utilities or if the local economics of food production and distribution are disrupted.
Ethanol plants should be scaled so that demand for feedstock does not disrupt distribution systems and markets for agricultural commodities. Support utilities and transportation should be able to support the scale of ethanol production. One important, hidden cost of large-scale ethanol plants is the cost of building or upgrading roads, water supply systems, pollution control systems, and electricity generating capacity. The method used to finance these support systems is an important economic question.
Distillers dried grains (DDG) are the major by-product commodity resulting from ethanol production. This high protein product is an excellent livestock feed, and feed lots could be located near the ethanol plant. Another extremely important potential use of this protein-rich material could be as a human food supplement.
End use of the ethanol and by-products must be on a scale that matches production. Technical resources need to be available for engine conversions if necessary. If ethanol is to be blended with gasoline, marketing and distribution systems for ethanol and for ethanol/gasoline blends must be developed in parallel with the construction and operation of ethanol fuel plants.
Proper integration can enhance ethanol production economics and can be achieved with well-designed small- and medium-scale plants. Small-scale plants can often take advantage of low value or waste feedstocks such as food processing waste or damaged or spoiled crops. A variety of low-cost boiler fuels such as biogas, waste heat from other industry or power plants, or biomass can be used if the plants are scaled to match the resources available within economical transport distances. Dehydration can be eliminated if ethanol is used in converted engines. Alternatively, a number of small ethanol plants can supply 80 to 95 percent ethanol to a centralized plant for dehydration and distribution. By-product processing can be reduced if the plant is scaled to supply livestock feed demand in the immediate area of the plant.
Small-scale plants are much simpler to build and operate than large plants. With technical support, small-scale ethanol plants can be built and operated using locally available skills and resources. With the exception of such equipment as motors, boilers, and controls, small-scale plants can be built in any reasonably well-equipped machine shop, provided that technically sound plans are available. Small-scale plants can also be mounted on flat-bed trailers so they can be moved from site to site.
Starch hydrolysis and ethanol dehydration are the two steps requiring long-term purchase of materials outside the local or even national level. The production of starch hydrolysis enzymes and molecular sieves requires relatively sophisticated technology. Enzymes and molecular sieves are supplied by a number of companies. As an alternative to purchasing these materials, they can be manufactured in centralized plants for distribution to small-scale ethanol plants.
VI. CHOOSING THE APPROPRIATE TECHNOLOGY[edit | edit source]
The decision to produce and use ethanol fuel requires addressing both direct and indirect technical and economic questions. These questions are important on any scale of development ranging from an individual local decision to produce on a small scale to national-level programs.
Direct technical and economic questions in the decision to produce and use ethanol fuel include the cost and the availability of feedstock; ethanol and by-product end uses and marketing; laws and regulations; production scale; and selection of plant design and equipment options.
Factors affecting feedstock availability and cost include transportation, storage, potential spoilage, and seasonal variations in supply and price.
Ethanol and by-product uses are affected by product transportation and distribution, storage, possible spoilage of by-products, seasonal variations in market demand or on-site use, and whether the ethanol is to replace or be blended with gasoline. If ethanol is to be blended with gasoline, the costs and the systems for distribution, blending, and marketing need to be taken into account. If ethanol is to replace gasoline, the costs of engine conversion and limitations to vehicle use are two important factors.
Laws and regulations affecting ethanol fuel production will vary from country to country. Variations may also occur between legal and political jurisdictions within countries. Regulations must be checked for each individual case. The principal regulations are those that prevent the use of fuel ethanol for human consumption. Generally, these regulations require that ethanol be denatured by adding chemical agents to the ethanol to make it unfit for human consumption. The most readily available denaturant for ethanol is gasoline mixed at one percent per volume. Other regulations may govern discharges of liquid and gaseous effluents and occupational safety and health. Laws dictating conformance to building codes (e.g., electric, plumbing, and fire safety codes) may also apply.
Decisions regarding plant scale, equipment, and process design depend primarily on feedstock, the availability of markets for both ethanol and its by-products, and the availability of plant financing. Economies of scale in ethanol fuel production are much less important than well-planned integration of ethanol fuel production with agricultural economics, local transportation, local utilities, and end uses.
Indirect social and economic questions are also very important in the decision to produce and use ethanol fuel. Economic decisions regarding ethanol production may rely more on the ability to meet such objectives as increasing rural employment, achieving energy independence, and providing alternative markets for crops than on direct evaluation of production costs and market values. Technical decisions regarding plant scale, process design, and equipment may be influenced by the ability to meet such objectives as the use of local labor and locally manufactured equipment, the creation of alternative markets for agricultural crops as feedstocks, and the local use of process energy.
The emergence of ethanol as a viable alternative to gasoline has led to two major controversies that can affect decisions regarding ethanol fuel production.
The first controversy concerns the question of net energy yield; that is, whether the energy content of the ethanol is greater than the energy consumed in production. With efficient technology, the energy content of ethanol exceeds the direct in-plant process energy inputs by about 2 to 1. However, one recent analysis, which took into account the energy used to cultivate feedstocks and to transport feedstock and products, calculated that ethanol production consumes more energy than is produced. The technical response to this analysis is that ethanol is not a primary energy source; rather, it is an energy conversion and storage system. In ethanol production, low-quality, diffuse primary energy sources are upgraded to a high-quality, liquid fuel. Solar energy in the form of plant carbohydrate and low-quality boiler fuels is converted to a fuel suitable for use in transportation. In simple terms, the response is that automobiles cannot run on cassava. When ethanol is viewed as an energy conversion system, the net energy question is largely irrelevant. Nevertheless, the question is useful because it points out the need to select those feedstocks requiring relatively little cultivation and low inputs of fertilizer and chemicals, and the need to use low-quality boiler fuels.
The second controversy surrounds the issue of food versus fuel; that is, whether the use of agricultural crops for ethanol fuel production will adversely affect the amount of land available for food production and food supply, as well as affecting food prices. This is a complex question to which there are no absolute answers. On the one hand, a large-scale diversion of food crops to ethanol production could reduce food supplies and increase food prices. On the other hand, a carefully planned and well-integrated ethanol fuel industry does not necessarily result in direct competition for agricultural land and food supplies. Low-value crops grown on marginal land are often good alcohol feedstocks with poor food value. Cultivation of low-value crops may contribute to the economy through conversion to a high-value product. Increased rural employment may increase people's economic access to high-quality food. Ethanol might also be produced from agricultural commodities that would otherwise be exported. Sugar cane, for example, may be worth more as a feedstock for domestic fuel production to displace imported petroleum than as an export crop. The issue of food versus fuel emphasizes the need for careful planning but does not mean that ethanol fuel production is an inappropriate technology.
BIBLIOGRAPHY[edit | edit source]
The Bioenergy Council. The Bioenergy Directory. Washington, D.C.: The Bioenergy Council.
Bernton, Hal; Kovarik, William, and Sklar, Scott. The Forbidden Fuel: Power Alcohol in the Twentieth Century. New York: Boyd Griffin, Inc., 1982.
Brown, Michael H. Brown's Alcohol Motor Fuel Cookbook. Cornville, Arizona: Desert Publications, 1979.
Carley, Larry W. How To Make Your Own Alcohol Fuels. Blue Ridge Summit, Pennsylvania: Tab Books, Inc., 1980.
Cheremisinoff, Nicholas P. Gasohol For Energy Production. Ann Arbor, Michigan: Ann Arbor Science Publishers, 1979.
De Rasor, Roberto. Alcohol Distiller's Manual for Gasohol and Spirits. San Antonio, Texas: Dona Carolina Distillers, 1980.
Development Planning and Research Associates, Inc. Gasohol: Economic Feasibility Study 1978. Available from the National Technical Information Service, U.S. Department of Commerce, 5285 Port Royal Road, Springfield, VA 22161.
First InterAmerican Conference on Renewable Sources of Energy. Proceedings of the First InterAmerican Conference on Renewable Sources of Energy, 25-29 November 1979. New Orleans, Louisiana: First InterAmerican Conference on Renewable Sources of Energy, 1980.
Hale, William J. Prosperity Beckons: Dawn of the Alcohol Era. Minneapolis, Minnesota: Rutan Publishing, 1979.
The Mother Earth News. Making Alcohol Fuel. Hendersonville, North Carolina: The Mother Earth News, 1979.
Solar Energy Information Data Bank, Solar Energy Research Institute, U.S. Department of Energy, Alcohol Fuels Bibliography (1901 - March 1980). April 1981, SERI/SP-751-902. This document is available in print from the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402, or in microfiche from the National Technical Information Service, U.S. Department of Commerce, 5285 Port Royal Road, Springfield, VA 22161.
Solar Energy Information Data Bank, Solar Energy Research Institute, U.S. Department of Energy, Fuel From Farms. A Guide to Small-Scale Ethanol Production. 1980. Also available from the above sources.
U.S. Industrial Chemicals Co. Division of National Distillers and Chemical Corporation. Ethyl Alcohol Handbook. New York, New York: U.S. Industrial Chemicals Co., 1969.
Willkie, Herman F., and Kolachov, Paul J. Food For Thought. Indianapolis, Indiana: Indiana Farm Bureau, Inc., 1942.
Winston, Paul R. Make Alcohol: The New Way To Go. McHenry, Illinois: For-Wins Inc.
The World Bank. Emerging Energy and Chemical Applications of Methanol: Opportunities For Developing Countries. Washington, D. C.: The World Bank. 1982.
Reference inquiries on specific topics relating to ethanol fuel production can be referred through VITA to the staff of Renewable Technologies, Inc., who prepared this report, or to other VITA volunteers with expertise in ethanol fuel.