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U.S. has large geothermal resources, but recent growth is slower than wind or solar

November 18,2011 EIA-Geothermal is one of the main renewable energy sources used to generate U.S. electricity, even though its growth has not been as strong as wind and solar over the last three years during a big push to increase generation from renewables. Geothermal energy's greatest growth potential is in the western states (see map above).

U.S. geothermal net electricity generation totaled 10,898 million kilowatthours (kWh) during the first eight months of 2011, up 10% from the same period in 2008, according to the latest data from EIA's Electric Power Monthly report. The data in the report reflects power generation facilities of 1 megawatt or larger. Geothermal energy also provides heating and cooling for three million Americans.

Compared to all generating sources, geothermal produced just 0.4% of electricity from all sectors nationally during the first eight months of this year. However, most geothermal power plants are located in the western states (see map below) with California producing the most electricity from geothermal, about 5% of the state's total power generation.

Several factors have influenced the growth of geothermal generating capacity:

  • Technology costs. New technology, referred to as enhanced geothermal systems (EGS), which may allow greater use of geothermal resources in other areas, is now in early-development. Current cost estimates for EGS are generally higher than those for conventional geothermal plants and other more mature renewable technologies like wind power.
  • Location. Geothermal plants can be very site-specific, and have generally been limited to areas with accessible deposits of high temperature ground water.
  • Transmission access. Lack of access to transmission lines, especially in western states where the geothermal resources are highest, limits growth.
  • Completion lead times. Completing a geothermal power generating project takes four to eight years, longer than completion timelines for solar or wind.
  • Risk. Even in well-characterized resource areas, there is significant exploration and production risk, which can result in high development costs. Development is often undertaken incrementally at a site to mitigate this risk and control costs

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Credit:The U.S. Energy Information Administration (EIA)