There are many types of biomass—organic matter such as plants, residue from agriculture and forestry, and the organic component of municipal and industrial wastes—that can now be used to produce fuels, chemicals, and power. Wood has been used to provide heat for thousands of years. This flexibility has resulted in increased use of biomass technologies. According to the Energy Information Administration, 53% of all renewable energy consumed in the United States was biomass-based in 2007.
Biomass technologies break down organic matter to release stored energy from the sun. The process used depends on the type of biomass and its intended end-use.
Biopower is the production of electricity or heat from biomass resources. With 10 gigawatts of installed capacity, biopower technologies are proven options in the United States today.
Biopower technologies include direct combustion, co-firing, and anaerobic digestion.
Most electricity generated from biomass is produced by direct combustion using conventional boilers. These boilers primarily burn waste wood products from the agriculture and wood-processing industries. When burned, the wood produces steam, which spins a turbine. The spinning turbine then activates a generator that produces electricity.
Co-firing involves replacing a portion of the petroleum-based fuel in high-efficiency coal-fired boilers with biomass. Co-firing has been successfully demonstrated in most boiler technologies, including pulverized coal, cyclone, fluidized bed, and spreader stoker units. Co-firing biomass can significantly reduce the sulfur dioxide emissions of coal-fired power plants and is a least-cost renewable energy option for many power producers.
Anaerobic digestion, or methane recovery, is a common technology used to convert organic waste to electricity or heat. In anaerobic digestion, organic matter is decomposed by bacteria in the absence of oxygen to produce methane and other byproducts that form a renewable natural gas.