World Geothermal Power Generation Nearing Eruption

Geothermal power could be a reliable energy source for reducing oil dependence and greenhouse gas emissions.


| Aug. 19, 2008



geothermal power plant

With a 750-megawatt output from 14 units, The Geysers is the largest producer of geothermal power in the world.


Courtesy NREL/DOE/David Parsons

With fossil fuel prices escalating and countries searching for ways to reduce oil dependence and greenhouse gas emissions, capturing the earth’s heat for power generation is garnering new attention. First begun in Larderello, Italy, in 1904, electricity generation using geothermal energy is now taking place in 24 countries, five of which use it to produce 15 percent or more of their total electricity. In the first half of 2008, total world installed geothermal power capacity passed 10,000 megawatts and now produces enough electricity to meet the needs of 60 million people, roughly the population of the United Kingdom. In 2010, capacity could increase to 13,500 megawatts across 46 countries — equivalent to 27 coal-fired power plants.

Originating from the earth’s core and from the decay of naturally occurring isotopes such as those of uranium, thorium, and potassium, the heat energy in the uppermost six miles of the planet’s crust is vast — 50,000 times greater than the energy content of all oil and natural gas resources. Chile, Peru, Mexico, the United States, Canada, Russia, China, Japan, the Philippines, Indonesia, and other countries along the Ring of Fire (an area of high volcanic activity encircling the basin of the Pacific Ocean) are rich in geothermal energy. Another geothermal hot spot is the Great Rift Valley of Africa, which includes such countries as Kenya and Ethiopia. Worldwide, 39 countries with a cumulative population of over 750 million people have geothermal resources sufficient to meet all their electricity needs. (See data.)

Typically, power generation using the earth’s heat required underground pockets of high-temperature water or steam to drive a steam turbine. Now, new technologies that use liquids with low boiling points in closed-loop heat exchange systems allow electricity to be generated at much lower temperatures. This breakthrough is making geothermal power generation viable in countries such as Germany that are not known for their geothermal resources and is one reason why the number of countries using the earth’s heat to generate electricity could almost double by 2010.

One advantage of geothermal power plants, beyond the benefit of producing electricity from a low-carbon, indigenous energy source with no fuel costs, is that they provide baseload power 24 hours a day. Storage or backup-power is not required.

The United States leads the world in generating electricity from the earth’s heat. As of August 2008, geothermal capacity in the United States totaled nearly 2,960 megawatts across seven states — Alaska, California, Hawaii, Idaho, Nevada, New Mexico, and Utah. California, with 2,555 megawatts of installed capacity — more than any country in the world — produces almost 5 percent of its electricity from geothermal energy. Most of this capacity is installed in an area called the Geysers, a geologically active region north of San Francisco.

Thanks to the Energy Policy Act of 2005, which made geothermal power generation eligible to receive the federal renewable energy production tax credit, electricity generated from geothermal resources now costs the same as fossil-fuel-based electricity in many markets in the western United States. With favorable economics, the geothermal industry is experiencing a surge in activity. As of August 2008, some 97 confirmed new geothermal power projects with up to 4,000 megawatts of capacity were under development in 13 states, with some 550 megawatts of this already in the construction phase. Expected to create 7,000 permanent full-time jobs, the new capacity will include numerous large-scale projects such as the 350-megawatt and 245-megawatt projects by Vulcan Power near Salt Wells and Aurora, Nevada; the 155-megawatt project by CalEnergy near the Salton Sea in southern California; and the 120-megawatt project by Davenport Power near the Newberry Volcano in Oregon.





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