In 2006, 7 percent of the energy consumed in the
United States came from renewable resources.
Roughly half of that amount, 3 percent total, was
producing using some form of biomass (U.S. EIA,
2008). Biomass is organic plant or animal material
that is available on a renewable basis (U.S. EIA,
2008). Biomass energy resources include food crops,
grassy and woody plants, agricultural and forestry
residues, municipal and industrial solid wastes, and
landfill gas (NREL, 2008). These resources are renewable
because, although individual trees and plants are
consumed, additional trees and plants can be cultivated
and grown relatively quickly, and municipal and
industrial solid wastes are continually produced.