Naturally occurring steam field reservoirs below the earth's surface are found in the Mayacamas Mountains, located north of San Francisco The Geysers, as it is known as the largest producer of geothermal electricity in the world drawing steam from than 350 wells. The Geysers border between Lake, Mendocino, and, Sonoma counties; and provide power to Sonoma, Mendocino, Lake, Marin, and Napa counties. Covering more than 45 square miles, commercial geothermal power has been continuously generated at The Geysers since 1960. There are 18 geothermal plants which use heat from the earth's interior to produce electricity around the clock.
The Geysers is one of only two locations in the world where a high-temperature, dry steam resource is found that can be directly used to move turbines and generate electricity. Since the late 1970's, the California Energy Commission licensed 11 geothermal projects at The Geysers. There are currently 18 geothermal plants in operation at The Geysers producing about 835 megawatts of electricity.
Today, The Geysers' reservoir continues to be recharged by injection of treated waste water, producing additional electricity. The waste water is piped up to 50 miles from its source at the Lake County Sanitation waste water treatment plants and added to the Geysers steam field. Injecting treated water into The Geysers protects local waterways and has produced electricity without releasing greenhouse gases emissions.
Photo of McCabe Unit 5 and 6 courtesy of Calpine Corporation. Photos of NCPA Plant #2 courtesy of the California Energy Commission
- The geothermal plants use heat from the earth's interior to produce electricity around the clock.
- The geothermal plants have the capacity to generate 725 megawatts, enough green energy to power San Francisco.
- An estimated 300 full-time operational jobs were created to operate Calpine's geothermal plants.
Key Developers and Partners
- Pacific Gas and Electric Company (PG&E), the California Department of Water Resources, the Northern California Power Agency (NCPA), the Sacramento Municipal Utility District, and Occidental Geothermal were the initial developers of geothermal power plants at The Geysers.
- As part of electricity deregulation, in 1999, PG&E sold all of its geothermal power plants to Calpine Corporation.
- Calpine owns and operates 15 plants. NCPA operates two plants and Bottle Rock Power, LLC, operates one power plant.
Type of Project
Calpine proposed two new geothermal power plants, each capable of producing up to 49 megawatts. The North Geysers project would be the first new plants constructed at The Geysers since 1989.
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