| 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 about 2,002 MWe with 1,885 MWe net delivering power to the grid producing approximately 16,000 GWh per year for a 97% capacity factor. Geothermal electric power plants are located in California, Nevada, Utah and Hawaii. The two largest concentrations of plants are at The Geysers in northern California and the Imperial Valley in southern California. The latest development at The Geysers, due to recent declines in steam output, is injecting recycled wastewater from two communities into the reservoir, which presently has recovered 69 MWe of power generation. 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 about 4,350 MWt and the annual energy use is 22,250 TJ or 6,181 GWh. The largest applications is ground-source (geothermal) heat pumps (60% of the energy use), and the largest direct-use is in aquaculture pond and raceway water heating. Direct utilization is increasing at about six percent per year; whereas, electric power plant development is almost static. The energy savings from electric power generation, direct-uses and ground-source heat pumps amounts to 6.6 million tonnes of equivalent fuel oil per years and reduces air pollution by 5.8 million tonnes of carbon annually (compared to fuel oil). |