geothermal power stations
A geothermal power plant uses it's geothermal activity to generate power. To harness the energy, deep holes are drilled into the earth (much like when drilling for oil) until a significant geothermal hot spot is found. When the heat source has been discovered, a pipe is attached deep down inside the hole, which allows hot steam from deep within the earths crust to rise up to the surface. The pressurized steam is then channeled into a turbine, which begins to turn under the large force of the steam. This turbine is linked to the generator and so the generator begins to also turn, generating electricity.
Wikipedia definition (similar term):
Geothermal power is power generated by geothermal energy. Technologies in use include dry steam power stations, flash steam power stations and binary cycle power stations. Geothermal electricity generation is currently used in 24 countries, while geothermal heating is in use in 70 countries. As of 2015, worldwide geothermal power capacity amounts to 12.8 gigawatts (GW), of which 28 percent or 3,548 megawatts are installed in the United States. International markets grew at an average annual rate of 5 percent over the last three years and global geothermal power capacity is expected to reach 14.5–17.6 GW by 2020. Based on current geologic knowledge and technology, the Geothermal Energy Association (GEA) estimates that only 6.5 percent of total global potential has been tapped so far, while the IPCC reported geothermal power potential to be in the range of 35 GW to 2 TW. Countries generating more than 15 percent of their electricity from geothermal sources include El Salvador, Kenya, the Philippines, Iceland and Costa Rica. Geothermal power is considered to be a sustainable, renewable source of energy because the heat extraction is small compared with the Earth's heat content. The greenhouse gas emissions of geothermal electric stations are on average 45 grams of carbon dioxide per kilowatt-hour of electricity, or less than 5 percent of that of conventional coal-fired plants.
Source: Wikipedia - Geothermal power