Biomass, or biofuel, is converted to electricity through a variety of means, including direct combustion, gasification, anaerobic digestion and pyrolysis, which is a form of thermochemical decomposition. The most common method is direct combustion, such as when woody materials are burned.
According to the Whole Building Design Guide, the term "biomass" encompasses a wide range of materials, including human and animal waste, agricultural byproducts, plants and wood. Generally speaking, woody biomass is gasified or combusted to generate electricity, while wet biomass, such as human and animal waste, is converted into gaseous form in an anaerobic digester.
The American Biogas Council explains that anaerobic digestion is a process in which microorganisms break down biomass in an environment devoid of oxygen. The result is usually biogas, which generates electricity when combusted. Biogas may also be converted into transportation fuel and renewable natural gas.
Plant matter and wood byproducts contain stored energy from the Sun, according to the Natural Resources Defense Council. For this reason, researchers are attempting to develop efficient means of generating energy from fast-growing, high-yielding potential energy crops, such as switchgrass and willow.
The Natural Resources Defense Council reports that most biomass materials produce electricity or heat with fewer harmful emissions than coal and are renewable, unlike fossil fuels.