|Alcohol Fuels: Options for Developing Countries (BOSTID, 1983)|
The potential for alcohol fuels in developing countries must be considered as part of a general biomass-use strategy that is, in turn, subverted by a broader energy supply and demand strategy. When sugarcane is the feedstock, for example, the changing world demand for sweeteners, as well as the possible need for diversification or integrated crop use, should be studied. The final strategies will necessarily reflect the needs, values, and conditions of the individual nations, regions, and societies that develop them.
Technical Aspects of Alcohol Fuel Production and Use
1. The technical capability exists to substitute the lower alcohols, methanol and ethanol, completely or in substantial part for all types of liquid fuels currently derived from petroleum.
2. The potential for substituting alcohol fuels for those based on petroleum is especially significant in transportation. Gasoline engines are currently available in some countries that may be operated efficiently on pure alcohol fuels. Conventional gasoline engines can operate satisfactorily on mixtures of alcohol and gasoline; in most cases, this can be done without any modification of the engine or fuel system. For diesel engines; available technology appears to permit the substitution of part, but not all, of the petroleum-based fuel with alcohol.
3. It is technically feasible to substitute alcohols for petroleum based fuels in all stationary applications such as heating, lighting cooking, and power generation. For these applications, however, some modification of currently available equipment will generally be required.
4. The technical capability exists in almost all countries to
produce ethanol from a broad spectrum of renewable biomass resources, spe
cifically from many varieties of plants and from agricultural, food processing,
and urban wastes. The components in these raw material' from which ethanol may
be produced are sugars, starches, cellulose, and hemicelluloses.
Technology for converting sugars to ethanol is well established and widely available for use on both large and medium scales. Commercial conversion of starches from cereal grains to alcohol is also well established and widely practiced. The starchy raw materials most prevalent in developing countries, such as cassava, taro, sago, yams, and sweet potatoes, differ somewhat from cereal grains, and there is little experience in their conversion on a commercial scale. The technology for converting cellulose to ethanol is either relatively new or limited in scope. Large-scale application is unlikely for 5 to 10 years.
5. The technical capability to produce methanol from biomass, though demonstrated, is not well developed. Current technology for methanol is based on fossil sources such as natural gas, coal, lignite, or peat. Gasification of biomass to produce methanol will require extensive commitments for land and capital.
6. A variety of technology developments now in progress may markedly affect the future viability of schemes for producing alcohol fuels from renewable resources. Significant among these are:
· New techniques for raw material preparation, biological conversion, and product separation
· Development of "appropriate intermediate" technology approaches, permitting the production of alcohol fuels on a modest scale from locally available resources to meet local needs
· Opportunities for the exploitation of integrated systems; for example, coproduction of food or feed and fuels, or the utilization of wastes from one process as the raw material for another (such as the production of biogas from the liquid and solid wastes from ethanol production)
7. Alcohol fuels cannot substitute for the entire range of products from petroleum refining, the diesel fuel fraction is the most difficult to replace. Thus the ability to reduce oil importation may depend in part on the ability to satisfy requirements for diesel fuel through other alternative fuels, such as vegetable oils.
8. In many situations, alcohol fuels may be the most convenient alternative to gasoline, but on a small scale there may be other energy sources that require less capital, organization, and management. These could include low-Btu gas from biomass gasification to fuel internal combustion engines, direct combustion of biomass to power steam engines, or mini-hydro-powered electric motors. These parallel technologies will influence the use of alcohol fuels and should be considered as part of the national and local energy strategies.
The availability of large amounts of biomass in many developing countries or of unused land capable of producing it suggests the possibility of substituting biomass-based alcohols for petroleum fuels in these areas. In evaluating the prospects for such substitutions, it is imperative to assess the quantity of biomass actually available and its seasonally and then to relate this both to the area's overall liquid fuel requirements and to the needs of specific use sectors (public and private transportation, shipping, and industry) and regions (rural and urban areas, for example).
1. The economic consequences that can ensue from adopting biomass-based alcohol fuels must be carefully analyzed; for example, positive indirect-economic factors associated with the replacement of imported petroleum by a home-based fuel industry as opposed to the possible negative effects on food prices and energy costs in different sectors.
2. Economic consequences will also vary, depending on the raw material selected and the utilization strategy employed. For example, the partial use of alcohols as chemical feedstocks or for export will have different local impacts than a pure fuel substitution policy.
1. The environmental implications of a biomass-based alcohol fuel strategy are far-reaching but little understood. They range from the extremely damaging, such as deforestation to produce the wood needed for a cellulose-based alcohol industry, to beneficial, such as improved forest management practices leading to higher productivity with better ecological balance and forest "health." The energy plantation approach to biomass production raises questions about vulnerability to pests, water requirements, and pollution by runoff.
2. Processes for converting biomass to alcohols can generate substantial amounts of liquid and, in some cases, solid wastes. Their utilization or disposal without environmental injury must be accounted for in the overall plan.
3. The substitution of alcohols for petroleum-based vehicle fuels can effect air quality. Although evidence suggests that the overall results may be beneficial, experience with alcohol fuels is too limited to permit unequivocal conclusions. Again, the climatic, industrial, and social conditions in a given area must be considered when evaluating the potential effects of widespread alcohol fuel use.
The most critical social effects are likely to result from the way in which production of alcohol fuels benefits those involved. It is frequently assumed that the urban elite will benefit at the expense of the poor when good land is put into production of grain, sugarcane, or cassava for alcohol. It is, however, also possible that a fuel alcohol program could provide rural jobs and a stimulus for improving agriculture and rural amenities, with farmers' incomes rising and production increased as a result. In this case, social inequity might be reduced through decentralized industrialization of the rural areas as they, rather than urban centers, become the source of development opportunity. The adoption of a biomass-based alcohol fuel policy will have other social impacts, depending on which of these two extremes tends to predominate, and will particularly affect land use and ownership.
Depending to some extent on the feedstock used, a substantial interval will follow any decision to implement a biomass-based alcohol fuel program before results will be observed. Although alcohol from a distillery annexed to an existing sugar mill could be produced fairly quickly, such a program requires the integration of many segments of the economy that are not regularly coordinated: agricultural production, fuel production and marketing, and possibly, chemical manufacture.
To enhance the overall potential for biomass-based alcohol fuels and the prospects for specific projects, the following recommendations are offered:
1. Developing countries must develop or expand their own capabilities to monitor and audit their energy needs, assess their biomass resources, weigh competing requirements, define fuel markets, and evaluate the technologies needed to convert local resources into fuel to meet local needs. These countries should also identify and evaluate, to the extent possible, all potential impacts-economic, environmental, and social-arising from the implementation of a biomass-based alcohol fuel strategy.
2. The development of commercial processes for converting cellulose and hemicelluloses to ethanol should be vigorously pursued. Technology for converting noncereal starches to ethanol should be demonstrated on a scale sufficient to ensure successful commercial application.
3. Research on fuels and chemicals from lignin and other biomass components should be intensified.
4. Existing technology for methanol production from biomass should be reviewed and evaluated in the context of some of the more promising biomass sources in developing countries.
5. Simplified technology and equipment suited to needs of individual developing countries should be designed and tested. Special emphasis should be given to intermediate-scale production units for the conversion of locally available resources to meet local fuel needs.
6. Greater research attention should be given to the prospects for integrated systems approaches to biomass-based fuel production.
7. Research on raising local biomass yields to levels approaching world averages should also be encouraged. Consideration should be given to plant varieties better suited to fuel production. Where monoculture is anticipated, resistance to plant pathogens must be examined. The use of natural fertilizers, including recycling wastes from the conversion step and similar opportunities for reducing energy consumption, must be given research emphasis.
8. Evaluation of vehicle engines specifically designed for alcohol fuels should continue. In this context, the substitution of alcohols for diesel fuels requires much more development than alcohol substitutes for gasoline.