Engineered geothermal is still experimental worldwide, but a few small commercial power plants do exist.
Japan burst onto the engineered geothermal scene early by demonstrating it on the side of a volcano, at a site called Hijiori. Its longest test ran for a year and harvested enough heat to run a small, 130-kilowatt power plant. The test stopped because one well cooled a dramatic 63 degrees F (17 degrees C) in one year [source: Tester].
The prospects look good in Australia because throughout the continent, radioactive sources heat basement rock that's shallow, cracked and now under the right kind of stress. In the Cooper Basin, currently used for oil and gas, surveyors found a 386-square-mile (1,000-square-kilometer) slab of granite sizzling at 482 degrees F (250 degrees C). Geodynamics Ltd. scooped up the site, sunk in a pair of wells, aptly called "Habanero-1" and "Habanero-2," cracked the rock and started circulating water. A power station is being built, which could generate hundreds to thousands of megawatts of electricity, the latter making it competitive with a coal plant, if many wells go into the big field [source: Tester].
France and Germany are now producing electricity by engineered geothermal. One plant, in Soultz-sous-Forêts, France, produces about 1 megawatt of electricity. The other, in Landau, Germany, produces 2 to 3 megawatts, says Rose. These small outputs could grow if the projects raise money to drill more wells.
In the United States, engineered geothermal is now starting. The first demonstrations will be at natural geothermal power plants at the Geysers in California and at Desert Peak and Brady in Nevada. In the demonstrations, engineered geothermal techniques will rescue some dry wells and boost power production at the sites.
The U.S. Geological Survey plans to demonstrate more engineered geothermal in the Midwest and in hot rock basins east of the Mississippi. "That would capture the imagination of a lot more states and congressmen and would help tremendously if it convinced them this wasn't only a Western resource," says Rose. If all goes well, stand-alone power plants might appear in the United States in five years, says Rose.
Read on to learn what else experts predict about the future of EGS.