A - E N - Z
feedstock: Any material used as a fuel directly or converted to another form of fuel or energy product.
fermentation: Biochemical reaction that breaks down complex organic molecules (such as carbohydrates) into simpler materials (such as ethanol, CO2 and water). Bacteria or yeasts can ferment sugars to ethanol.
fluidized bed: Gasifier or combustor design in which feedstock particles are kept in suspension by a bed of solids kept in motion by a rising column of gas. The fluidized bed produces approximately isothermal conditions with high heat transfer between the particles and gases.
forestry residues: Includes tops, limbs, and other woody material not removed in forest harvesting operations in commercial hardwood and softwood stands, as well as woody material resulting from forest management such as precommercial thinnings and removal of dead and dying trees.
fossil fuel: Carbon or hydrocarbon fuel formed in the ground over millions of years from the remains of dead plants and animals. Oil, natural gas and coal are fossil fuels.
gasification: Any chemical or heat process used to convert a feedstock to a gaseous fuel.
greenhouse gas: Gas—such as water vapor, CO2, tropospheric ozone, methane and low-level ozone—that contributes to the greenhouse effect.
hemicellulose: Hemicellulose consists of 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.
herbaceous plants: Non-woody species of vegetation, usually of low lignin content, such as grasses.
herbaceous energy crops: Perennial non-woody crops that are harvested annually, though they may take two to three years to reach full productivity. Examples include switchgrass (Panicum virgatum), reed canary grass (Phalaris arundinacea), miscanthus (Miscanthus x giganteus), and giant reed (Arundo donax).
hydrolysis: Conversion, by reaction with water, of a complex substance into two or more smaller units, such as conversion of cellulose into glucose sugar units.
landfill gas: Biogas produced from natural degradation of organic material in landfills. By volume, landfill gas is about 50 percent methane and 50 percent CO2 and water vapor.
life-cycle analysis: Assessment of the impacts from all stages of a product’s development, from extraction of fuel for power to production, marketing, use and disposal.
lignin: Structural constituent of wood and other native plant material that encrusts the cell walls and cements the cells together.
lignocellulose: Plant materials made up primarily of lignin, cellulose and hemicellulose.
methane: (CH4) The major component of natural gas. It can be formed by anaerobic digestion of biomass or gasification of coal or biomass.
methanol (wood alcohol): (CH3OH) Alcohol formed by catalytically combining carbon monoxide with hydrogen in a 1:2 ratio under high temperature and pressure.
microorganism: Any microscopic organism such as yeast, bacteria, fungi, etc.
municipal solid waste: Any organic matter, including sewage, industrial and commercial wastes, from municipal waste collection systems. Municipal waste does not include agricultural and wood wastes or residues.
Source: Adapted from National Renewable Energy Laboratory (NREL) Glossary of Biomass Terms, www.nrel.gov/biomass/glossary.