| Abstract |
Geothermal energy is used for electric power generation and direct utilization in the United States. The present installed capacity (gross) for electric power generation is 3,368 MWe (installed) with 1,748 MWe net (running) delivering power to the gird producing approximately 14,974 GWh per year for a 0.54 gross capacity factor and a 0.98 net capacity factor. Geothermal electric power plants are located in California, Nevada, Utah, Hawaii, Alaska, Idaho, Oregon, and Wyoming, with 300 MWe being added the last five years. The two largest concentrations of plants are at The Geysers in northern California and the Imperial Valley in southern California. The Geysers continues to receive waste water from Clear Lake and Santa Rosa, California that is injected into the field and has resulted in the recovery of approximately 200 MWe of power generation. The lowest temperature installed plant is at Chena Hot Springs in Alaska, where binary cycle plants uses 74oC geothermal fluids to run three units for a total of 730 kW (gross). The direct utilization of geothermal energy includes the heating of pools and spas, greenhouses and aquaculture facilities, space heating and district heating, snow melting, agricultural drying, industrial applications and ground-source heat pumps. The installed capacity is 12,611 MWt and the annual energy use is 56,552 TJ or 15,709 GWh. The largest application is ground-source (geothermal) heat pumps (84% of the energy use), and the next largest direct-use is fish farming and swimming pool heating. Direct utilization (without heat pumps) remainded static over the past five years with gains balancing losses; however, ground-source heat pumps are being installed at a 13% annual growth rate with one million units (12 kW size) in operation. The energy saving from all geothermal energy use is about 6.9 million tonnes of equivalent fuel oil per year (45.7 million barrels) and reduces air pollution by almost 6.0 million tonnes of carbon and 17.0 million tonnes of CO2 annually (compared to fuel oil). |