Biomass—renewable energy from plants and animals

Photosynthesis. In the process of photosynthesis, plants convert radiant energy from the sun into chemical energy in the form of glucose or sugar. Water plus carbon dioxide plus sunlight yields glucose plus oxygen. Six water plus six carbon dioxide plus radiant energy yields sugar plus six oxygen.

Source: Adapted from The National Energy Education Project (public domain)

Image with different kinds of biomass types: wood, crops, garbage, landfill gas, and alcohol fuels

Source: Adapted from The National Energy Education Project (public domain)

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 or biogas that can be 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 is only one way to release the energy in biomass. Biomass can be converted to other useable forms of energy such as methane gas or transportation fuels such as 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 primary energy used in the United States in 2016. Of that 5%, about 48% was from biofuels (mainly ethanol), 41% was from wood and wood-derived biomass, and about 11% was from the biomass in municipal waste. Researchers are trying to develop ways to use more biomass for fuel.