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 2020
MWe, with 1902 MWe net delivering power to the grid, producing approximately 16,000
GWh per year for a 96% 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 the injection of recycled
wastewater from two communities into the reservoir, which has at present permitted the
recovery of 70 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 4350 MWt and the annual energy use is 22,250
TJ, or 6181 GWh. The largest application is that of ground-source (geothermal) heat pumps
(60% of the energy use), and the largest direct-use is that of aquaculture pond and raceway
water heating. Direct utilization is increasing at about 6% per year, whereas electric power
plant development is almost static. The energy savings from electric power generation, direct
uses and ground-source heat pumps amount to 6.6 million tonnes of equivalent fuel oil per
year and represents a reduction in air pollution of 5.8million tonnes of carbon annually
(compared to fuel oil).
# 2003 CNR. Published by Elsevier Ltd. All rights reserved.
Keywords :
electric power , Imperial Valley , Direct-use , USA , Heat pumps , The Geysers