Geothermal power—using the enormous heat generated in the Earth's core by the radioactive decay of unstable elements—could prove to be the cleanest, greenest, and most abundant source of energy we have ever used. Literally beneath our feet is a white-hot, seething mass of magma that generates temperatures of up to 9,000 degrees Fahrenheit. The heat is used to generate electricity or heat facilities.
Geothermal energy is so sustainable that the first modern site, established in Lardarello, Italy, in 1904, is still producing power. The existing plant has been in operation since 1913, and was interrupted only once, by a World War II bomb.
Although geothermal energy is experiencing a relatively recent resurgence, it's hardly new. It has been powering the United States since 1922, and currently produces 65 percent more power in the United States than solar and wind combined. Yet despite its commercial success since 1960, geothermal's full potential is just starting to be tapped by a few visionary companies.
The reservoirs of steam and hot water that make large-scale geothermal generation possible are primarily located in the western states, Alaska, Hawaii, and other parts of the Pacific Rim's "RingofFire." However, as we shall see later in this chapter, geothermal heat pumps and direct-use applications can tap the heat energy underground almost anywhere.
In a traditional geothermal plant, steam or superheated ...