Skip Ribbon Commands
Skip to main content An Official Website of the Commonwealth of Kentucky
FCCTC students perform tests while producing biodiesel.  Photo by Mary Jo Harrod

Division of Biofuels
Glossary N-Z

 A - E       F - M



net energy balance: Total amount of energy used over the full life cycle of a fuel, from feedstock production to end use.

nitrogen oxides (NOX): Product of photochemical reactions of nitric oxide in ambient air and the major component of photochemical smog.

nonrenewable resource: One that cannot be replaced as it is used. Although fossil fuels, such as coal and oil, are in fact fossilized biomass resources, they form at such a slow rate that, in practice, they are nonrenewable.




opportunity fuels: Biomass feedstocks derived from waste materials that would otherwise go unused or would be disposed of. Bioenergy production provides an opportunity to productively use these materials.

oxygenate: Compound that contains oxygen in its molecular structure. Ethanol and biodiesel act as oxygenates when they are blended with conventional fuels. Oxygenated fuel improves combustion efficiency and reduces tailpipe emissions of CO.




particulates: Fine liquid or solid particle, such as dust, smoke, mist, fumes or smog, found in air or emissions. 

petroleum: Any substance composed of a complex blend of hydrocarbons derived from crude oil, including motor fuel, jet oil, lubricants, petroleum solvents and used oil.

pyrolysis: Breaking apart of complex molecules by heating in the absence of oxygen, producing solid, liquid and gaseous fuels.




renewable energy resource: Energy resources that can be replaced as they are used, including solar, wind, geothermal, hydro and biomass.

residues, biomass: Byproducts from processing all forms of biomass that have significant energy potential. For example, making solid wood products and pulp from logs produces bark, shavings, sawdust and spent pulping liquors. Because these residues are already collected at the point of processing, they can be convenient and relatively inexpensive sources of biomass for energy.




silviculture: Science and practice of growing trees for human use.

stover: Dried stalks and leaves of a crop remaining after the grain has been harvested.

syngas: Synthesis gas produced by the gasification process using biomass feedstock. Syngas can be burned in a boiler or engine to produce electricity or heat, and can be used to produce a liquid for biofuels production.




tar: Liquid product of thermal processing of carbonaceous materials.

thermochemical conversion: Use of heat to change substances chemically to produce energy products.

transesterification: Chemical process that reacts an alcohol with triglycerides contained in vegetable oils and animal fats to produce biodiesel and glycerin.




volatile: Solid or liquid material that easily vaporizes.




xylose: (C5H10O5) Five-carbon sugar that is a product of hydrolysis of xylan found in the hemicellulose fraction of biomass.




zero net contribution: Refers to a process that results in contribution of no additional carbon emissions to the atmosphere. For example, combustion of biomass feedstocks returns the same amount of CO2 to the atmosphere that was absorbed during growth of the biomass.

Source: Adapted from National Renewable Energy Laboratory (NREL) Glossary of Biomass Terms,