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. Biomass contains stored energy from the sun. Plants absorb the sun's energy in a process called photosynthesis. The chemical energy in plants is passed to animals and people after the plants are consumed.

Biomass is a renewable energy source. Some examples of biomass fuels are wood, crops, animal manure, and human sewage.

The chemical energy in biomass is released as heat when it is burned. The wood burned in a fireplace is a biomass fuel. Wood and waste materials made from wood and garbage are burned to produce steam for making electricity or heat for industries.

Converting biomass to other forms of energy

Burning biomass is not the only 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 the main component of natural gas. Garbage, agricultural waste, and human waste release methane gas—also called landfill gas or biogas.

Crops like corn and sugar cane can be fermented to produce ethanol. Biodiesel, another transportation fuel, can be 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 2014. Of that 5%, about 46% was from wood and wood-derived biomass, 44% was from biofuels (mainly ethanol), and about 10% was from municipal waste. Researchers are trying to develop ways to use more biomass for fuel.