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Energy timelines


  • The first dry steam geothermal power plant was built in Laderello in Tuscany, Italy. The Larderello plant today provides power to about 1 million households.
  • The first commercial-scale development tools were placed in California at The Geysers, a 10-megawatt unit owned by Pacific Gas & Electric.
  • Re-injection of spent geothermal water back into the production reservoir was introduced as a way to dispose of waste water and to extend reservoir life.
  • Deep well drilling technology improvements led to deeper reservoir drilling and to access to more resources.
  • Scientists began to develop the first hot dry rock (HDR) reservoir at Fenton Hill, New Mexico. An HDR power facility was tested at the site in 1978 and started to generate electricity two years later.

  • U.S. Department of Energy (DOE) funding for geothermal research and development was increased substantially.
  • The Public Utility Regulatory Policies Act (PURPA) of 1978 was enacted to promote greater use of renewable energy, cogeneration and small power projects.
  • The first commercial-scale binary plant in the United States began operation in Southern California’s Imperial Valley.
  • California’s Standard Offer Contract system for PURPA-qualifying facilities provided renewable electric energy systems a relatively firm, stable market for output, allowing the financing of capital-intensive technologies like geothermal energy facilities.

  • Geothermal (hydrothermal) electric generating capacity, reached a new high of 1,000 megawatts.
  • Utah’s first commercial geothermal power plant began operating  at Roosevelt Hot Springs with a 20 megawatt capacity.
  • Nevada’s first geothermal binary power production plant began operating at Wabuska Hot Springs.
  • DOE and the Electric Power Research Institute operated a 1-megawatt, geopressured power demonstration plant in Texas, extracting methane and heat from brine liquids.
  • DOE funding for geothermal energy research and development declined throughout the 1980s and reached a low of $15 million.
  • The world’s first magma exploratory well was drilled in the Sierra Nevada Mountains to a depth of 7,588 feet.
  • The Puna field of Hawaii began electrical generation at a 25 megawatt geothermal plant.
  • California Energy became the world’s largest geothermal company through its acquisition of Magma Power.
  • Worldwide geothermal capacity reached 6,000 megawatts.
  • At Empire Nevada, a food-dehydration facility processed 15 million pounds of dried onions and garlic a year, using geothermal resources. 
  • A DOE low-temperature resource assessment of 10 Western States identified nearly 9,000 thermal wells and springs and 271 communities with a geothermal resource greater than 50ºC.
  • California's geothermal power plants provided 54.9% of the State’s electricity.
  • The DOE and industry worked together on the Geothermal Resource Exploration and Definition Program.  It was a cooperative effort to find, evaluate, and define additional geothermal resources throughout the western United States. 
  • Geothermal energy costs dropped from $.10 - .16 per kilowatt hour to $.5 - .8 per kilowatt hour.
  • The U.S. geothermal industry became a $1.5 billion a year business that involved electricity generation and thermal energy in direct use such as indoor heating, greenhouses, food drying, aquaculture.
  • Alaska installed a 200 kilowatt power plant that used low-temperature (74ºC) geothermal water along with cooling water (4ºC).
  • Idaho’s first commercial geothermal power plant began operating.

Last Revised: July 2008
Sources: U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, A History of Geothermal in the United States, January 2008

California Energy Commission, Overview of Geothermal Energy in California, January 2008
California Energy Commission, California Geothermal Resources, January 2008
California Energy Commission, Geothermal Technologies Program, January 2008
U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Geothermal Research, January 2008
Oregon Institute of Technology, JHC Bulletin, Development and Utilization of Geothermal Resources, June 2007