Biomass is organic material that comes from plants or animals, and it represents a source of renewable energy.
Biomass sources include:
- Wood and wood processing wastes
- Agriculture crops and waste materials
- Biogenic materials in municipal solid waste
- Animal manure and human sewage
Biomass is then converted to energy through processes such as direct combustion to produce heat, thermochemical conversion to produce solid, gaseous, and liquid fuels, chemical conversion to produce liquid fuels, biological conversion to produce liquid and gaseous fuels. All biomass can be burned directly for heating buildings and water, for industrial process heat, and for generating electricity for steam turbines. 
Thermochemical conversion of biomass includes the following:
- Pyrolysis which involves heating organic materials to 800-900°F in the absence of free oxygen. This produces fuels such as charcoal, bio-oil, renewable diesel, methane, and hydrogen.
- Hydrotreating is used to process bio-oil with hydrogen under elevated temperatures and pressures in the presence of a catalyst to produce renewable diesel, gasoline, and jet fuel.
- Gasification involves heating organic materials to 1,400-1,700°F with controlled amounts of free oxygen to produce syngas. Syngas can be used for diesel engines, heating, and generating electricity for gas turbines. Syngas can also be treated to separate the hydrogen and then burned or used in fuel cells or further processed to produce liquid fuels.
Another chemical process known as transesterification is used to convert vegetable oils, animal fats, and greases into fatty acid methyl esters (FAME), which are used for biodiesel. Fermentation is used to convert biomass into ethanol and anaerobic digestion to produce renewable natural gas and ethanol is used as vehicle fuel.
In 2020, biomass provided 4,532 trillion (Btu) equal to about 4.9% of total U.S. primary energy consumption. About 2,101 TBtu were from wood and wood-derived biomass, 2,000 TBtu were from biofuels (ethanol), and 430 TBtu were from municipal wastes. Below are the amounts of and percentages of total U.S. biomass energy use by consuming sector in 2020.
- Industrial – 2,246 TBtu (50%)
- Transportation – 1,263 TBtu (28%)
- Residential – 458 TBtu (10%)
- Electric Power – 424 TBtu (9%)
- Commercial – 141 TBtu (3%)
According to the Energy Information Administration (EIA), in 2021, approximately 20% of electricity in the US was produced using a renewable energy source. Biomass is one form of renewable energy, accounting for about 1.3% of total US electricity generation in 2021 and about 6.7% of electricity generation from renewable energy. Biomass can be “burned directly in steam-electric power plants, or it can be converted to a gas that can be burned in steam generators, gas turbines, or internal combustion engine generators.”
Updated by Erin Bennett, June 2022