ABSTRACT
Biomass is a scientific term for living matter, but the word biomass is also used to denote products derived from living organisms-wood from trees, harvested grasses, plant parts, and residues such as twigs, stems, and leaves, as well as aquatic plants and animal wastes. Stated differently, biomass consists of plant and plant-derived materials, including animal manure, starch, sugar, and oil crops that are already used for food and energy. All of the Earth’s biomass exists in the thin layer we call the biosphere. This represents only a tiny fraction of the total mass of the Earth, but in human terms it is an enormous store of energy-as fuel and as food. More importantly, it is a store that is being replenished continually. The source that supplies the energy is, of course, the sun, and although only a tiny fraction of the solar energy reaching the Earth each year is converted into biomass it is nevertheless equivalent to over five times the total world energy consumption. Bioenergy (stored energy from the sun) has been used since early times when people began burning wood to cook food and to keep warm.
