Biomass is the weight or total quantity of one or all species of living and recently living organisms in an area. It is composed of a mixture of organic molecules containing carbon and hydrogen, usually also oxygen, and often nitrogen as well as small quantities of other elements, including traces of heavy metals.
The term biomass can also refer to a fuel that consists of organic matter, including virgin wood, wood processing waste, energy crops, agricultural residues, food waste, and some industrial waste. Such fuel removes carbon from the atmosphere while it is growing, and returns it while it is burning.