Biomass is organic material that comes from plants and animals, and it is a renewable source of energy.
Biomass contains stored energy from the sun. Plants absorb the sun's energy in a process called photosynthesis. When biomass is burned, the chemical energy in biomass is released as heat. Biomass can be burned directly or converted to liquid biofuels and biogas that are burned as fuels. Examples of biomass and their uses for energy:
- wood and wood processing wastes—burned to heat buildings, to produce process heat in industry, and to generate electricity
- agricultural crops and waste materials—burned as a fuel or converted to liquid biofuels
- food, yard, and wood waste in garbage—burned to generate electricity in power plants or converted to biogas in landfills
- animal manure and human sewage—converted to biogas, which can be burned as a fuel
Converting biomass to other forms of energy
Burning biomass is only one way to release its energy. Biomass can be converted to other useable forms of energy like methane gas or transportation fuels like ethanol and biodiesel.
Methane gas is a component of landfill gas or biogas that forms when garbage, agricultural waste, and human waste decompose in landfills or in special containers called digesters.
Crops such as corn and sugar cane are fermented to produce fuel ethanol for use in vehicles. Biodiesel, another transportation fuel, is produced from vegetable oils and animal fats.
How much biomass is used for fuel?
Biomass fuels provided about 5% of the energy used in the United States in 2015. Of that 5%, about 43% was from wood and wood-derived biomass, 46% was from biofuels (mainly ethanol), and about 11% was from municipal waste. Researchers are trying to develop ways to use more biomass for fuel.