Steam rising from a geothermal power plant in Iceland.PThe heat in the upper six miles of the Earth’s crust contains 50,000 times as much energy as found in all the world’s oil and gas reserves combined. Despite this abundance, only 10,700 megawatts of geothermal electricity generating capacity have been harnessed worldwide.
Partly because of the dominance of the oil, gas, and coal industries, which have been providing cheap fuel by omitting the costs of climate change and air pollution from fuel prices, relatively little has been invested in developing the Earth’s geothermal heat resources. Over the last decade, geothermal energy has been growing at scarcely 3 percent a year.
Roughly half the world’s existing generating capacity is in the United States and the Philippines. Indonesia, Mexico, Italy, and Japan account for most of the remainder. Altogether some 24 countries now convert geothermal energy into electricity. El Salvador, Iceland, and the Philippines respectively get 26, 25, and 18 percent of their electricity from geothermal power plants.
The potential of geothermal energy to provide electricity, to heat homes, and to supply process heat for industry is vast. Among the countries rich in geothermal energy are those bordering the Pacific in the so-called “Ring of Fire,” including Chile, Peru, Colombia, Mexico, the United States, Canada, Russia, China, Japan, the Philippines, Indonesia, and Australia. Other geothermally rich countries include those along the Great Rift Valley of Africa, such as Kenya and Ethiopia, and those around the Eastern Mediterranean.