Alcohols: Organic compounds that are distinguished from hydrocarbons by the inclusion of a hydroxyl group. The two simplest alcohols are methanol and ethanol.

Aldehydes: A class of organic compounds derived by removing the hydrogen atoms from an alcohol. Aldehydes can be produced from the oxidation of an alcohol.

Anhydrous: Describes a compound that does not contain any water. Ethanol produced for fuel use is often referred to as anhydrous ethanol, as it has had almost all water removed.

Aromatics: Hydrocarbons based on the ringed six-carbon benzene series or related organic groups. Benzene, toluene and xylene are the principal aromatics, commonly referred to as the BTX group. They represent one of the heaviest fractions in gasoline.

American Society for Testing and Materials (ASTM): A nonprofit organization that provides a management system to develop published technical information. ASTM standards, test methods, specifications and procedures are recognized as definitive guidelines for motor fuel quality as well as a broad range of other products and procedures.

Benzene: A six-carbon aromatic; common gasoline component identified as being toxic. Benzene is a known carcinogen.

Biochemical Conversion: The use of enzymes and catalysts to change biological substances chemically to produce energy products.

Biodiesel: A biodegradable transportation fuel for use in diesel engines that is produced through trans-esterification of organically derived oils or fats. Biodiesel is used as a component of diesel fuel and can also be used as a replacement for diesel.

Biomass: Renewable organic matter such as agricultural crops, crop-waste residues, wood, animal and municipal wastes used for the production of energy.

Bioenergy: Solar energy that uses organic materials, which ultimately get their energy from the sun. For example, plants use sunlight and carbon dioxide from the atmosphere to make food, in the form of sugars and starches. When plants are harvested and processed, that food becomes energy we can use in car engines or power plants.

Biomass: Any organic material, including plants and animals.

Biofuels: Liquid fuels, such as ethanol or biodiesel, made from biomass.

BTX: Industry term referring to the group of aromatic hydrocarbons benzene, toluene and xylene (see aromatics).

Carbon Dioxide (CO2): A product of combustion that has become an environmental concern in recent years. CO2 does not directly impair human health but is a “greenhouse gas” that traps the earth’s heat and contributes to the potential for global warming.

Carbon Sequestration: The absorption and storage of CO2 from the atmosphere by the roots and leaves of plants; the carbon builds up as organic matter in the soil.

Catalyst: A substance whose presence changes the rate of chemical reaction without itself undergoing permanent change in its composition. Catalysts may be accelerators or retarders. Most inorganic catalysts are powdered metals and metal oxides, chiefly used in the petroleum, vehicle and heavy chemical industries.

Cellulose, Cellulosic: The main substance inside plant cell walls that provides the shape and structure of the plant. Cellulose is actually chains of molecules, including glucose, linked together into a strong matrix. This protects the plant from being torn apart by wind, insects or disease. That’s why it’s so hard to break up cellulose to get to the glucose inside!

Ethanol: An alcohol that can be produced chemically from ethylene or biologically from the fermentation of various sugars from carbohydrates found in agricultural crops and cellulosic residues from crops or wood. Ethanol is used throughout much of the world as an octane enhancer and oxygenate in gasoline (E10 and E15) and can be used in higher concentration in flex-fuel vehicles optimized for its use (E85).

Ester: An organic compound formed by reacting an acid with an alcohol, always resulting in the elimination of water.

Ether: A class of organic compounds containing an oxygen atom linked to two organic groups.

Feedstock: Any material converted to another form of fuel or energy product. For example, corn starch can be used as a feedstock for biofuels production.

Fermentation: The enzymatic transformation by microorganisms of organic compounds such as sugars. It is usually accompanied by the evolution of gas, as in the fermentation of glucose into ethanol and CO2.

Flex-Fuel Vehicles (FFV): Vehicles with a common fuel tank designed to run on varying blends of unleaded gasoline with either ethanol or methanol.

Fungible: A term used within the oil refining industry to denote products that are suitable for transmission by pipeline.

Global Warming: The theoretical escalation of global temperatures caused by the increase of greenhouse gas emissions in the lower atmosphere.

Glucose: The sugar found in plant cells that can be used to make biofuels.

Greenhouse Effect: A warming of the earth and its atmosphere as a result of the thermal trapping of incoming solar radiation by CO2, water vapor, methane, nitrous oxide, chlorofluorocarbons and other gases, both natural and man-made.

Neat Fuel: Fuel that is free from admixture or dilution with other fuels.

Octane Rating: A measure of a fuel’s resistance to self-ignition, and a measure of the antiknock properties of a fuel.

Oxygenate: A term used in the petroleum industry to denote fuel additives containing hydrogen, carbon and oxygen in their molecular structure. Oxygenates include ethers and alcohols such as ethanol and methanol.

Petroleum Fuel: Gasoline and diesel fuel derived from fossil fuels.

Toluene: Basic aromatic compound derived from petroleum and used to increase octane. The most common hydrocarbon purchased for use in increasing octane.

U.S. Department of Energy (DOE): A department of the federal government, established by the Carter Administration in 1977, to consolidate energy-oriented programs and agencies. The DOE mission includes the coordination and management of energy conservation, supply, information dissemination, regulation, research, development and demonstration. The department includes the Office of Transportation Technologies, the umbrella of the Office of Alternative Fuels.

U.S. Environmental Protection Agency (EPA): A government agency, established by the Nixon Administration in 1970, responsible for the protection of the environment and public health. The EPA seeks to reduce air, water and land pollution and pollution from solid waste, radiation, pesticides and toxic substances. The EPA also controls emissions from motor vehicles, fuels and fuel additives.

Xylene: An aromatic hydrocarbon historically derived from petroleum and used to increase octane. Xylenes are highly valued as a petrochemical feedstock. They are highly photo-chemically reactive and, as a constituent of tailpipe emissions, a contributor to smog formation.