Biomass uses the energy in organic matter such as plants. Other sources of biomass energy include agricultural and wood waste, municipal waste, and landfill gas. Geothermal Geothermal energy is used both for power generation and for heating. In 1990, the U.S. had 62 geothermal electric plants generating 2,350 MW of electricity. Geothermal power generation requires high-temperature resources that are found mostly in the western part of the county.
Heat pumps are the fastest growing direct use application of geothermal power.
Hydropower One-half of all the renewable energy used in the United States today comes from hydropower. Hydropower uses the energy of flowing water to turn a turbine which in turn rotates a generator thus producing electricity. Hydropower spurred industrial development in the 19th century. Currently, hydro accounts for 12 percent of the country's generating capacity. However, hydropower development has slowed in recent years due to environmental concerns and more stringent regulatory and operating requirements.