Biomass is a term for anything organic, dead or alive, as long as it has not been fossilized, such as wood, manure, leaves, and food wastes (see: Other Solid Biofuels). Biomass is also a term for a kind renewable energy source that is made from organic things. Biofuels or biomass fuels are fuels made from organic things, such as ethanol (see: Ethanol and Methanol) or biodiesel. A fuel is any substance that produces energy in any form (thermal, light, electricity, motion, etc.) by a result of chemical change.