Ethanol Glossary

The following excerpt is from a book entitled Sustainable Ethanol: Biofuels, Biorefineries, Cellulosic Biomass, Flex-Fuel Vehicles, and Sustainable Farming for Energy Independence


alcohol—An organic compound with a carbon bound to a hydroxyl group. Examples are methanol, CH3OH, and ethanol, CH3CH2OH.

anhydrous ethanol—Ethanol with almost all water removed.

ARS—USDA, Agricultural Research Service

bagasse—The solid material left after processing sugar cane to produce sugar or ethanol. Often burned for power production, but could be made into more ethanol with cellulosic processing techniques.

biodiesel—A renewable, biodegradable transportation fuel for use in diesel engines. It is produced from organically derived oils or fats. Biodiesel can be used as a component of or replacement for diesel fuel.

bioenergy—Renewable energy derived from organic matter.

biofuel—Liquid, solid, or gaseous fuel produced by conversion of biomass. Examples include woodchips, biodiesel, ethanol from biomass, bio-oil, and biogas.

biogas—A renewable gas derived from decomposing organic material under anaerobic conditions. Normally consists of 50–60% methane. Can be upgraded to replace fossil-based natural gas for automobiles, heating, cooking, generation of electricity, and other uses.

biomass—Organic matter available on a renewable basis. Includes agricultural crops, residues, wood and wood waste, animal wastes, fast-growing trees, municipal waste, and food processing waste.

bio-oil—A liquid fuel produced by the pyrolysis of biomass. Bio-oil can be upgraded to ethanol or other biofuels and materials. As an energy-dense intermediate, it is easier to transport than raw biomass.

biorefineriy—A facility for the production of biofuels.

BTU—British Thermal Unit. A standard unit of measure representing the heat energy required to raise the temperature of 1 pound of water by 1 degree Fahrenheit at sea level.

butanol—(C4H10O) An alcohol. Sometimes referred to as “biobutanol” when made from biomass such as grains or cellulosic material. It has a higher volumetric energy content than ethanol and shows promise as an automotive fuel if production costs can be brought down.

cellulose—A long chain of glucose (sugar) molecules. Strengthens the cell walls of most plants.

cellulosic ethanol—Ethanol made from cellulose or hemicellulose after breaking them down into constituent sugars.

CHP—Combined Heat and Power. Also known as cogeneration. The production of electricity and useful thermal energy from a common fuel source, increasing energy efficiency.

coproduct—A product of biomass processing when multiple products are produced from the same feedstock.

crop residue—Organic residue remaining after harvesting a crop.

crop rotation—Alternating the crops grown on a given plot of land. Can improve soil fertility and help reduce pests and diseases.

DDGS—Dried Distillers Grain with Solubles. Nutrient-rich coproduct of
ethanol production from grains. Can be a high quality livestock feed.

denatured ethanol—Ethanol made unfit for beverage use.

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distillation—Extraction of a volatile component (such as alcohol) by condensation and collection of vapors produced as a mixture is heated.

DOE—United States Department of Energy

E10—A mixture of 10% ethanol and 90% gasoline based on volume.

E85—A mixture of 85% ethanol and 15% gasoline based on volume.

ERS—USDA, Economic Research Service

EIA—DOE, Energy Information Administration

EPA—United States Environmental Protection Agency

ensilage—The process of partially fermenting and storing fresh plant material in an oxygen-poor environment.

enzyme—A protein or protein-based molecule that can speed up chemical reactions in biomass.

ethanol—(CH3CH2OH) A colorless, flammable liquid usually produced by fermentation of sugars. Used as a fuel oxygenate and replacement for gasoline. Ethanol is the alcohol found in alcoholic beverages.

ethanol optimization—Designing an engine for better efficiency, performance, or fuel economy when powered by ethanol.

ethanol-livestock integration—Combining livestock and ethanol production in a synergystic fashion, resulting in greater energy efficiency and other benefits. Livestock waste can serve as the process fuel for a biorefinery, for instance, while DDGS is fed to the livestock.

feedstock—Any material converted to another useful form or product. For example, cornstarch can be a feedstock for ethanol production.

FER—Fossil Energy Replacement Ratio. Energy delivered to the final customer divided by the fossil energy inputs into the production system for a given energy carrier such as ethanol. FER is a measure of reliance on fossil energy. Higher FER means less fossil energy went into producing that energy carrier.

fermentation—A biochemical reaction that breaks down complex organic molecules into simpler materials. Bacteria or yeasts can ferment sugars to ethanol, for instance.

flex-fuel vehicle—A vehicle that can operate on alternative fuels (usually E85 in North America) or on traditional fuels such as ethanol-free gasoline or a mixture of alternative and traditional fuels.

fossil fuels—Solid, liquid, or gaseous fuels formed in the ground after millions of years by chemical and physical changes in plant and animal residues under high temperature and pressure.

gasification—A chemical or heat process to convert coal, biomass, wastes, or other carbon-containing materials into a gaseous form that can be burned to generate power or processed into chemicals and fuels, including ethanol.

glucose—A simple six-carbon sugar, C6H12O6. A sweet, colorless sugar that is the most common sugar in nature and the sugar most commonly fermented to ethanol.

greenhouse gases—Those gases, such as water vapor, carbon dioxide, nitrous oxide, and methane, that are transparent to solar radiation but opaque to long wave radiation.

hemicellulose—Short, highly branched chains of sugars. In contrast to cellulose, which is a polymer of only glucose, a hemicellulose is a polymer of five different sugars. Compared to cellulose, the branched nature of hemicellulose renders it relatively easy to hydrolyze.

hydrated ethanol—Ethanol containing a significant amount of water. Can be used as a fuel in engines designed or modified for the purpose.

hydrolysis—The conversion of a complex substance into two or more smaller units, such as the conversion of cellulose into glucose sugar units for cellulosic ethanol production.

landfill gas—A bio-gas produced as a byproduct of decomposition in landfills. Can be a process fuel or feedstock for biofuel production.

legumes—Plants in the pea family, characterized by their ability to host nitrogen-fixing bacteria, lessening or eliminating the need for nitrogen fertilization. Includes beans, alfalfa, and many native prairie plants.

lignin—The major structural constituent of wood and other plant materials. It cements cells together. A co-product of some cellulosic ethanol production systems, it can be burned as a process fuel.

MIT—Massachusetts Institute of Technology

MTBE—Methyl Tertiary Butyl Ether. A colorless, flammable liquid. Used as an oxygenate additive to gasoline to increase octane and reduce engine knock.

ORNL—Oak Ridge National Laboratory

octane rating—A number indicating a fuel's resistance to self-ignition, hence also a measure of the antiknock performance of the fuel.

oxygenates—Substances which, when added to gasoline, increase the amount of oxygen in that gasoline blend. Ethanol, Methyl Tertiary Butyl Ether (MTBE), Ethyl Tertiary Butyl Ether (ETBE), and Methanol are some examples.

particulate matter—A small, discrete mass of solid or liquid matter that remains individually dispersed in gas or liquid emissions.

perennial crops—Crops that live multiple years without replanting.

petroleum—A generic term applied to fossil-derived oil and oil products in all forms. Includes crude oil, unfinished oil, refined petroleum products, and natural gas plant liquids.

proof—A measure of the volume of ethanol in a liquid. Proof is twice the percentage number, so 100% ethanol would be 200 proof.

PRR—Petroleum Replacement Ratio. Energy delivered to the final customer divided by the petroleum inputs into the production system for a given energy carrier such as ethanol. PRR is a measure of reliance on petroleum, a fossil energy source more likely to be imported into the U.S. as compared to other fossil fuels. Higher FER means less petroleum went into producing that energy carrier.

starch—A molecule composed of long chains of linked glucose molecules.
Because of the way the glucose molecules are linked, starch can be readily broken down into glucose by enzymes. Glucose, a type of sugar, can then be fermented for ethanol production.

sustainable farming—Using farming methods that maintain productivity, soil fertility, and a healthy ecosystem over the long term.

USDA—United States Department of Agriculture

from the book entitled Sustainable Ethanol

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