BiomassBiomass is the organic non-fossil material of biological origin, collectively. For example, plants (including trees) and animals are biomass, as are the materials they produce, such as animal droppings and wood. Biomass is sometimes burned as fuel for cooking and to produce electricity and heat. Biomass used as fuel often consists of underutilized types, like chaff and animal waste. This is often considered a type of alternative energy although it is not a non-polluting one.