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Iceland’s Svartsengi (“Black Meadow”) geothermal power plant, located on the Reykjanes Peninsula in Iceland, was the first geothermal plant designed to both create electricity and provide hot water for district heating. With six different plants, it generates 75 megawatts of electricity, enough to supply 25,000 homes. Its “waste” hot water is piped to the Blue Lagoon Geothermal Spa, visited by 400,000 guests annually.

The heat energy contained below the earth’s surface is about 100 billion times more than current world energy consumption. Geothermal power—literally “earth heat”—taps into underground reservoirs of steamy hot water, which can be piped to the surface to drive turbines that produce electricity. That feat was first accomplished in Larderello, Italy, on July 15, 1904.

Prime geothermal conditions are found on less than 10 percent of the planet, but new technologies dramatically expand production potential. One new approach targets deep underground cavities and adds water to create hydrothermal pools where they do not currently exist. Care must be taken, as the means to access these cavities can create micro-earthquakes.

With subterranean resources flowing 24-7, without interlude, geothermal production can take place at all hours and under almost any weather conditions. Geothermal is reliable, abundant, and efficient. While drilling is expensive, the heat source itself is free. According to the Geothermal Energy Association, 39 countries could supply 100 percent of their electricity needs from geothermal energy, yet only 6 to 7 percent of the world’s potential geothermal power has been tapped.


earth’s internal heat…energy generated: Fridleifsson, I.B., R. Bertani, E. Huenges, J. W. Lund, A. Ragnarsson, and L. Rybach. “The Possible Role and Contribution of Geothermal Energy to the Mitigation of Climate Change.” In IPCC Scoping Meeting on Renewable Energy Sources, Proceedings, edited by O. Hohmeyer and T. Trittin, 59-80. Luebeck, Germany, January 20-25, 2008.

Larderello, Italy…Piero Ginori Conti: Dipippo, Ronald. Geothermal Power Plants: Principles, Applications, Case Studies and Environmental Impact. Burlington: Elsevier Science, 2012.

[global] geothermal electricity generation: REN21. Renewables 2016 Global Status Report. Paris: REN21 Secretariat, 2016; Matek, Benjamin. 2016 Annual U.S. & Global Geothermal Power Production Report. Washington, D.C.: Geothermal Energy Association, 2016.

direct geothermal supplies heat: REN21, Renewables 2016; Matek, Geothermal.

prime geothermal conditions: Duffield, Wendell A., and J. H. Sass. Geothermal Energy: Clean Power from the Earth’s Heat. Menlo Park, CA: U.S. Geological Survey, 2003.

Iceland’s Blue Lagoon: Gipe, Paul. “Iceland: High Penetration of Renewables in the Modern Era.” Renewable Energy World. November 7, 2012.

emissions [vs.] a coal plant: Duffield and Sass, Geothermal Energy.

twenty-four countries [with] geothermal power: Matek, Geothermal.

El Salvador and the Philippines: World Bank. “Geothermal Energy: Expansion Well Underway in Developing Countries.” The World Bank. December 3, 2014.

Kenya…Great Rift Valley: World Bank. “Kenya’s Geothermal Investments Contribute to Green Energy Growth, Competitiveness and Shared Prosperity.” The World Bank. February 23, 2015.

U.S. geothermal plants: Matek, Geothermal.

39 countries could supply 100 percent: Gawell, Karl, Marshall Reed, and P. Michael Wright. Preliminary Report: Geothermal Energy, The Potential for Clean Power from the Earth. Washington, D.C.: Geothermal Energy Association, 1999.

6 to 7 percent of the world’s potential…tapped: Matek, Geothermal.

projections [of] undiscovered geothermal resources: Fridleifsson et al, “Possible.”

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