The Geysers, a geothermal power field located 72 miles (116 km) north of San Francisco, California, is the largest geothermal development in the world. It was here that Pacific Gas and Electric began operation of the first successful geothermal electric power plant in the United States in 1960.[1] The original turbine lasted for more than 30 years and produced 11 MW net power.[2] The Geysers has 1517 megawatt (MW)[3] of active installed capacity with an average capacity factor of 63%.[4] Calpine Corporation owns 15 of the 18 active plants in the Geysers and is currently the United States' largest producer of geothermal energy.[5] Two other plants are owned jointly by the Northern California Power Agency and the City of Santa Clara's municipal Electric Utility (now called Silicon Valley Power). The remaining Bottle Rock Power plant owned by the US Renewables Group has only recently been reopened.[6] A nineteenth plant is now under development by Ram Power, formerly Western Geopower. Since the activities of one geothermal plant affects those nearby, the consolidation plant ownership at The Geysers has been beneficial because the plants operate cooperatively instead of in their own short-term interest. The Geysers is now recharged by injecting treated sewage effluent from the City of Santa Rosa and the Lake County sewage treatment plant. This sewage effluent used to be dumped into rivers and streams and is now piped to the geothermal field where it replenishes the steam produced for power generation.
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Description
The Geysers geothermal development spans an area of around 30 square miles (78 km²) in Sonoma and Lake counties in California, located in the Mayacamas Mountains. Power from The Geysers provides electricity to Sonoma, Lake, Mendocino, Marin, and Napa counties. It is estimated that the development meets 60 percent of the power demand for the coastal region between the Golden Gate Bridge and the Oregon state line.[7]
Steam used at The Geysers is produced from a greywacke sandstone reservoir, that is capped by a heterogeneous mix of low permeability rocks and underlaid by a Felsite intrusion.[8] Gravity and seismic studies suggest that the source of heat for the steam reservoir is a large magma chamber over 4 miles (7 km) beneath the ground, and greater than 8 miles (14 km) in diameter. [9]
Unlike most geothermal resources, the Geysers is a dry steam field, which means it mainly produces superheated steam. Because the power plant turbines require a vapor phase input, dry steam resources are generally preferable. Otherwise, a two-phase separator is required between the turbine and the geothermal wells to remove condensation that is produced with the steam.
History
The first recorded discovery of The Geysers was in 1847 during John Fremont's survey of the Sierra Mountains and the Great Basin by William Bell Elliot. Elliot called the area "The Geysers," although the geothermal features he discovered were not technically geysers, but fumaroles. Soon after, in 1852, The Geysers was developed into a spa for The Geysers Resort Hotel, which attracted the likes of Ulysses S. Grant, Theodore Roosevelt, and Mark Twain.[10]
Future
The Geysers electrical plant reached peak production in 1987, at that time serving 1.8 million people. Since then, the steam field has been in gradual decline as its underground water source decreases. Currently, the Geysers produce enough electricity for 1.1 million people.
Techniques developed from Enhanced Geothermal Systems research will increase the production of the region in the future. By reinjecting greywater from the nearby city of Santa Rosa, existing wells will be recharged. This water will be naturally heated in the geothermal reservoir, and be captured by the existing power plants as steam. The project should increase electrical output by 85 MW, enough for about 85,000 homes.[11]
See also
References
- ^ Lund, J. (September 2004), "100 Years of Geothermal Power Production", Geo-Heat Centre Quarterly Bulletin (Klamath Falls, Oregon: Oregon Institute of Technology) 25 (3): 11-19, ISSN 0276-1084, http://geoheat.oit.edu/bulletin/bull25-3/art2.pdf, retrieved 2009-04-13
- ^ McLarty, Lynn; Reed, Marshall J. (October 1992). "The U.S. Geothermal Industry: Three Decades of Growth". Energy Sources, Part A: Recovery, Utilization, and Environmental Effects (London: Taylor & Francis) 14 (4): pp. 443 - 455. doi:. ISSN 1556-7230. http://geotherm.inel.gov/publications/articles/mclarty/mclarty-reed.pdf.
- ^ DiPippo, Ronald. Geothermal Power Plants, Second Edition: Principles, Applications, Case Studies and Environmental Impact. Butterworth-Heinemann. ISBN 978-0-7506-8620-4.
- ^ Lund, John W.; Bloomquist, R. Gordon; Boyd, Tonya L.; Renner, Joel (24-29 April 2005), "The United States of America Country Update", Proceedings World Geothermal Congress, Antalya, Turkey
- ^ All figures adjusted to include recently reopened Bottle Rock Power plant.
- ^ Baker, David R. (Sunday, January 14, 2007). "Steamy industry may clear the air". San Francisco Chronicle (Lake County): p. page F-1. http://www.sfgate.com/cgi-bin/article.cgi?file=/c/a/2007/01/14/BUGV2NHQP61.DTL. Retrieved 2009-11-09.
- ^ "Calpine Corporation - The Geysers" (http). http://www.geysers.com. Retrieved 2008-06-11.
- ^ RESERVOIR RESPONSE TO INJECTION IN THE SOUTHEAST GEYSERS, 1991 (pdf) Steve Enedy, Kathy Enedy, John Maney, Sixteenth Workshop on Geothermal Reservoir Engineering 1991. (accessed 2007-05-16)
- ^ "Cascades Volcanic Observatory (USGS) - Clear Lake Volcanic Field, California" (http). http://vulcan.wr.usgs.gov/Volcanoes/California/ClearLake/description_clear_lake.html. Retrieved 2007-05-16.
- ^ "A History of Geothermal Energy in the United States" (http). http://www1.eere.energy.gov/geothermal/history.html. Retrieved 2007-05-17.
- ^ "[[1] National Renewable Energy Laboratory - Enhanced Geothermal Sources]" (pdf). [2]. Retrieved 2007-06-01.
External links
- Calpine to Increase Renewable Energy Production at The Geysers; Calpine and Santa Rosa to Expand Geysers Recharge Project
- USGS map of frequent earthquakes in the Geyser area
Coordinates: 38°47′26″N 122°45′21″W / 38.79056°N 122.75583°W
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