Biodiesel: A diesel fuel made from plant or other biological material, often from soy beans. Diesel fuel contains more carbon in longer atomic chains than does gasoline. Often used in trucks, diesel fuel tends to get greater mileage per gallon than does gasoline.

Biorefinery: A facility that converts biomass, such as corn, into fuel and other products, such as animal feed and chemicals.

Cellulose: The major part of plant cell walls that makes them thick and tough. Cellulose has the formula (C6H10O5)n

Enzyme-enhanced fermentation: A process by which cellulosic plants are converted to a biofuel, with fermentation enhanced by protein from living cells. In fermentation, sugar is converted to carbon dioxide and alcohol.

Fischer-Tropsch synthesis: A process that converts coal to fuel and can also be used to convert cellulose plants into biofuel. Fischer-Tropsch works through gasification and synthesis into liquid fuel.

Greenhouse Gas (GHG) balance: The ration of greenhouse gasses used by a fuel or industrial product relative to another fuel or project. GHG balance should be calculated using a life cycle analysis; whether to include indirect land use is controversial.

Indirect Land Use: The amount of land displaced for one use by another, often referring to food uses displaced by biodiesel production. It also refers to forest or other natural land displaced, altering the GHG balance and contributing to climate change.

Life cycle analysis (LCA): A complete analysis encompassing every cost of the use of a fuel or product, including raw materials, transportation, production, and final use. An LCA assesses energy use in conjunction with environmental impact at every stage. It should also account for associated products and possible recycling.

Lignose: A strong, glue-like substance in the stalks and other parts of plants designed to protect them.

Peak Oil: The point at which half of global oil reserves have been used, at which point scarcity will gradually increase and prices rise. When this will happen is not known. In 1956 geologist M. King Hubbert came up with the principle of peak oil, and predicted, accurately, that the United States would hit peak oil in the 1970s.

Photobioreactor: A closed system used to grow algae, carefully controlling light, nutrients, temperature and other variables.