GEOTHERMAL POWER HEATING UP WORLDWIDE
By J. Matthew Roney
Earth Policy Release
Plan B Update
June 16, 2011
In 1904, Italy’s Prince Piero Ginori Conti became the first person to use thermal energy from within the earth to turn on the lights—five of them, to be precise. Now, more than a century after his experiment, 24 countries are using geothermal power. The 10,900 megawatts of capacity installed worldwide generate enough renewable electricity to meet the needs of more than 6 million U.S. homes. Geothermal power has grown at just 3 percent annually over the last decade, but the pace is set to pick up substantially, with close to 9,000 megawatts of new capacity projected for 2015. Some 350 projects are under development in dozens of countries.
The energy source for geothermal electricity generation is the tremendous heat flowing from the Earth’s core and mantle and from radioactive isotopes decaying in the Earth’s crust. Developers drill wells to reach porous and permeable rock containing reservoirs of hot water or steam that is then brought to the surface to drive a turbine and generate electricity. Historically, this required a water temperature of 150 degrees Celsius (302 degrees Fahrenheit) or more, which is found in abundance in countries along the Pacific Ring of Fire—including Chile, Indonesia, Japan, and the United States—as well as in Africa’s Great Rift Valley region. Recent technology improvements, however, have made power generation using lower-temperature resources possible, enabling Germany, Hungary, and others to begin harnessing their geothermal power potential.