Atmosphere Air, or the gases that compose the air, including oxygen, nitrogen, carbon dioxide and trace amounts of gases such as argon, methane, and others.
Barrel A barrel refers to 42 U.S. gallons of oil.
Biofuel A fuel that is derived from a biological process. Examples include ethanol from fermentation, methane gas from the decomposition of organic material, and firewood.
Biomass Any material produced by living things. In this lesson, biomass generally means material left over from forestry or farming activities.
Carbon neutral Does not increase the concentration of carbon dioxide in the atmosphere.
Cellulose One of the three major components of lignocellulosic biomass. Cellulose is composed of glucose molecules linked together. The other two components of lignocellulosic biomass are hemicellulose and lignin.
Conventional ethanol Ethanol produced from the fermentation of traditional sources of sugar or starch, such as sugarcane, sugarbeets, corn, wheat, and barley.
Distillation The process of separating two materials based on their different boiling points. In the case of ethanol and water, ethanol boils at a lower temperature than water, and so ethanol can be separated from water and purified by boiling the mixture and collecting the vapors. The vapors will contain a higher percentage of ethanol than the original liquid mixture.
E10 E10 is a gasoline blend containing 10% ethanol and 90% gasoline. E10 is available at many gas stations and can be used by most cars built after 1986.
E85 E85 is a gasoline blend containing 85% ethanol and 15% gasoline. E85 can be used by flexible fuel vehicles.
Enzymatic hydrolysis Hydrolysis is the breaking apart of large molecules into smaller molecules with the addition of water. Enzymatic hydrolysis uses enzymes to catalyze or speed up the reaction.
Enzyme One of a number of different types of molecules produced by living things which catalyze specific chemical reactions. Cellulase enzymes speed up the rate at which cellulose breaks apart into glucose molecules.
Ethanol Also called ethyl alcohol. Ethanol is a volatile, flammable, colorless liquid at room temperature. It has a high energy value and can be used as a liquid fuel. It is also the primary intoxicating ingredient in alcoholic beverages.
Fermentation A process to obtain energy for living in the absence of oxygen. In the absence of oxygen, yeast can ferment sugars to alcohols.
Flexible Fuel Vehicle A car or truck which can run on alcohol, gasoline, or any blend of alcohol and gasoline. A computer chip and sensors determine the specific blend in the fuel tank and tunes the engine to run best for that blend.
Fossil fuel Coal, oil, and natural gas. Fossil fuels are the result of the slow decomposition of plants and animals which lived approximately 300 million years ago.
Gas mileage The number of miles which can be driven in an automobile on one gallon of gas.
Greenhouse gas (GHG) Any gas in the atmosphere which absorbs and emits radiation in the infrared range. Examples are water vapor, methane, and carbon dioxide. Because greenhouse gases absorb infrared radiation, they have the effect of retaining some of the heat that would otherwise be re-emitted into space from the surface of the planet.
Hemicellulose One of the three major components of lignocellulosic biomass. Hemicellulose is composed of many different kinds of sugars, including xylose, arabinose, mannose, glucose, and galactose. The other two major components of lignocellulosic biomass are cellulose and lignin.
Hydrolyzate The liquid left over from a hydrolysis process. In hydrolysis of lignocellulosic biomass, the hydrolyzate contains the sugars from the cellulose and hemicellulose.
Lignin One of the three major components of lignocellulosic biomass. Lignin is a highly disordered, tarry material with a high energy value. In lignocellulosic ethanol production, lignin, which contains no sugars, is separated from the cellulose and hemicellulose, which do contain sugars. Lignin, which is still in its solid form after lignocellulosic ethanol production, can be burned to provide heat and electricity for the process.
Lignocellulosic biomass Biomass composed of three main components; lignin, cellulose, and hemicellulose.
Microorganism A single-cell living thing which can only be seen with the aid of a microscope. Many microorganisms produce useful things as a byproduct of living. An example of a useful byproduct produced by microorganisms is ethanol.
Petroleum Crude oil, natural gas and their products, such as gasoline, kerosene, wax, asphalt and many other derivatives.
Photosynthesis The way that green plants make food by capturing sunlight, carbon dioxide, and water to form sugars.
Pilot Scale A small study for designing or checking methods before investing in a large scale operation.
Pretreatment The first step in converting lignocellulosic biomass into ethanol. Pretreatment involves treating the woody biomass with a chemical (like dilute acid) to disrupt the complex structure of the biomass. Many types of pretreatment involve breaking down the material into sugars for fermentation.
Renewable Resources which are continually replaced, such as trees, water, and wind.
Simple sugar A sugar which is in its most fundamental form. It cannot be hydrolyzed any further while still remaining a sugar. Simple sugars are the easiest to ferment to ethanol.
Starch A complex sugar composed of glucose molecules.
Unconventional ethanol Ethanol produced from any source other than fermentation of traditional sources of starch or sugar. See conventional ethanol.