Biomass is renewable organic material that comes from plants and animals and was the largest source of total annual U.S. energy consumption until the mid-1800s. Biomass contains stored chemical energy from the sun with plants producing biomass through photosynthesis. Biomass can be burned directly for heat or converted to renewable liquid and gaseous fuels through various processes. The use of biomass fuels for transportation and for electricity generation is increasing in many parts of the world as a means of avoiding carbon dioxide emissions from fossil fuel use. In 2020, biomass provided about 5% of total primary energy use in the United States.