Geothermal energy is heat energy originating from Earth. The word itself was derived from the words geo and thermal meaning Earth and heat respectively. This heat from the earth is used in many ways, including as a source for electricity generation and to heat and cool buildings.
Geothermal energy provides an affordable and sustainable solution to reducing dependence on fossil fuels, and the effects of global warming and public health risks that result from the use of fossil fuel. Currently it accounts for 0.4% of global electricity generating capacity and is widely used in several countries including the US, Philippines, Italy, Mexico, Indonesia, Japan and New Zealand, according to BBC Global Energy Guide.
According to the Union of Concerned Scientist more than 8,900 MW (megawatts) of utility-scale geothermal capacity exist in 24 countries, producing enough electricity to meet the annual needs of approximately 12 million typical U.S. households. Geothermal plants produce approximately 25 percent of electricity in the Philippines, Iceland, and El Salvador. The United States leads the way in terms of installed capacity, with more than 3,000 MW in eight states. In thousands of homes and buildings across the United States, geothermal heat pumps use the steady temperatures just below the ground surface to heat and cool buildings, clean and inexpensively.