Reports and Documents
- Energy Commission Reports with Keyword "Geothermal"
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- Geothermal: The Energy Under Our Feet, Geothermal Resource Estimates for the United States - National Renewable Energy Laboratory (PDF file)
- The Future of Geothermal Energy - Report by Massachusetts Institute of Technology for Renewable Energy and Power Department Idaho National Laboratory (PDF files)
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California Geothermal Energy Statistics & Data
Because of its location on the Pacific's "ring of fire" and because of tectonic plate conjunctions, California contains the largest amount of geothermal generating capacity in the United States.
In 2007, geothermal energy in our state produced 13,000 gigawatt-hours (GWh) of electricity. Combined with another 440 GWh of imported geothermal electricity, then geothermal energy produced 4.5 percent of the state's total system power. A total of 42 operating geothermal power plants with an installed capacity of 1,727 megawatts are in California, about two-thirds of the total United States' geothermal generation.
The largest concentration of geothermal plants is located north of San Francisco in the Geysers Geothermal Resource Area in Napa and Sonoma Counties (shown in photo on the right). This location has been producing electricity since the 1960s. It uses dry steam; one of only two places in the world for this resource (the other being in Larderello, Italy).
Geothermal Electricity Production
(In Gigawatt-Hours; Includes Imports)