a class of chemicals (composed of carbon, hydrogen, and oxygen) which can be burned as fuel. Ethanol and methanol are the two main types being considered for fuel use. Compare gasohol.

anhydrous -

containing virtually no water. Anhydrous alcohol (200 proof) can be mixed with gasoline without risk of separation.

biomass -

any plant material that may be used to produce food, feed, fiber, or energy, including grains, cornstalks and other agricultural residues, fruits and vegetables and their processing byproducts, and bagasse (residue from processing sugarcane); wood products and residues from logging and paper manufacturing; and aquatic plants. The term is often used to include animal manure.

Btu -

a unit of measurement that provides a way to compare the energy available in different fuels or other energy sources. One Btu is the amount of heat energy it takes to raise the temperature of one pound of water one degree Fahrenheit.

cellulosic material -

crop stalks, forest residues, and portions of urban waste that can be processed into alcohol fuels once treated with acids or enzymes to break them down into fermentable sugars. Use of these materials to make alcohol fuels on a large scale depends on improving the efficiency (now 20%) of this hydrolysis, or breaking down, step.

conversion ratios (typical) -

1 bushel of corn

= 2.73 gal. of 190 proof ethanol or
= 2.55 gal. of 200 proof ethanol

1 ton of
crop
residue

= 0.8 tons of
fermentable
sugar

= 121.21 gal
of 200 proof
ethanol

1 barrel = 42 gallons

denaturant -

a substance added to ethanol to make it unfit for human consumption so that it is not subject to alcohol beverage taxes.

destructive distillation -

a process to produce fuel from cellulosic materials by heating them in the absence of oxygen, decomposing the material, and then distilling the resulting vapors. Compare hydrolysis.

distillation -

the last stage in making alcohol from fermentable sugars. The "beer" (fermented feedstock containing about 85% water) is heated in a distillation column, or still, to boil off the water and the alcohol, which is condensed and piped off to a storage tank. In "vacuum" distillation, the process takes place at lower pressure, which makes it possible to distill the alcohol using less heat energy.

distillers' mash -

a protein- and mineral-rich byproduct of alcohol production from grain. When water has been removed this byproduct is called distillers' dried grains, or DDG, and can be stored and transported without spoilage. Distillers' mash and DDG are currently used as animal feed supplements (they have higher protein value--22-27%--than the original grain itself), and research is underway on using DDG as a human food supplement.

ethanol (ethyl or "grain" alcohol) -

an alcohol made from grains as well as from starch- and sugar-rich crops by fermentation and distillation); from cellulosic material (which must undergo hydrolysis first); or from petroleum products like ethylene (by reacting them with a catalyst). Ethanol can be blended with gasoline as an extender and octane booster. Ethanol contains 2/3 of the energy in Btus of an equal volume of gasoline but can provide more miles per Btu.

excise tax, gasoline -

a tax collected at the pump to support the construction and maintenance of highways. Gasohol is exempt until 1984 from the $.04 federal excise tax and in some states from the state excise tax.

feedstock -

the raw material from which alcohol can be made, including distressed or substandard grain, grain sorghum, sugar beets, sugarcane, potatoes, fruits, vegetables, cheese whey, food wastes, and potentially, cellulosic materials and municipal solid waste.

fermentation -

a step in the production of ethanol from agricultural products. Bacteria or yeast added to a "mash" of grain, sugar beets, or other agricultural products, break down the sugars into alcohols. The resulting "beer" must then be distilled to produce alcohol of a "proof" suitable for fuel use.

gasohol -

a mixture of 10% 200-proof ethanol and 90% unleaded gasoline.

hydrolysis -

the first step in producing ethanol from cellulosic materials (like wood, urban waste, and vegetable residue). Hydrolysis uses enzymes and/or acid to break down cellulose into sugar before fermentation and distillation can take place. Compare to destructive distillation.

methanol (methyl or "wood" alcohol) -

an alcohol made from wood or carbonaceous urban waste (by destructive distillation), from natural gas (by reacting that gas with a catalyst), or from coal (by liquefaction--a technology that is being advanced for commercial use in this country). Methanol can also be used as a gasoline extender and octane enhancer but, since it tends to corrode certain seals and metals, is likely to come into wider use only if materials and engines are modified to accommodate it.

net energy balance -

the amount of energy available from a fuel when it is burned minus the amount of energy it takes to produce the fuel.

proof -

the volume of ethanol in a liquid. Proof is twice the percentage number, so a liquid that was 100% ethanol would be 200 proof. The higher the proof, the more Btus are available when the liquid is burned.

rack price -

the initial wholesale gasoline price as paid at the refinery delivery rack.

still -

the apparatus used to distill alcohol, that is, to remove water from it in successive stages in order to increase its proof.

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