100 Geothermal Energy Facts

    1. The word geothermal is a fusion of “geo”,  a Greek word meaning “Earth,” and “therme” a Greek word meaning “heat.
    2. Geothermal power originates from the Earth’s formation, decay of radioactive isotopes, volcanic activity and solar energy.
    3. The temperature increases around 80 degrees Fahrenheit for each mile of depth below the Earth’s surface.
    4. At the center of Earth is a solid core with an estimated temperature of about 8,000 °F (4426 °C).

          Stromboli is an active volcano, located off the north coast of Sicily, Italy. Its last eruption happened on April 13, 2009

      Stromboli is an active volcano, located off the north coast of Sicily, Italy. Its last eruption happened on April 13, 2009.

    5. The high temperature of the Earth’s core melts the surrounding rock into a hot liquid referred to as magma.
    6. Geothermal energy is being perpetually generated in the Earth as magma travels upward while surface groundwater sinks down to the Earth.
    7. Territories close to the boundaries of Earth’s tectonic plates contain geothermal resources.
    8. The rate of heat energy transfer, known as the conductive heat flux is much higher near tectonic plate boundaries where the Earth’s crust is thinner.
    9. Geothermal energy can be found in the form of volcanoes, hot springs and geysers.
    10. Volcanoes are the most eminent geothermal occurrences.
    11. Sometimes volcanoes are not located at the boundaries of plates. These locations are referred to as hot spots.
    12. The best-known hot spot is located in the Pacific Ocean, forming the series of volcanoes in Hawaii. Mauna Kea, Hawaii is located above the hot spot.
    13. Nevada has hundreds of hot spots.
    14. More than 10,000 years ago, Native Americans directly used geothermal energy for bathing and cooking.
    15. The oldest known use of geothermal energy is a stone pool on Lisan mountain in China, built in the in the 3rd century BC.
    16. Chaudes-Aigues, France, is considered the world’s oldest geothermal district heating system that has been in operation since the 14th century.
    17. In 1832, Hot Springs, Arkansas (a site of 47 hot springs) became the first federally protected area in the US.
    18. The geothermal heat pump was invented in 1852 by Lord Kelvin, a British physicist and mathematician.
    19. Boise, Idaho built the first district geothermal heating system in the US in 1892.
    20. The world’s first commercial geothermal power plant was built in Larderello, Italy in 1911.
    21. Steam and hot water from geysers began heating homes in Iceland starting 1943.
    22. In 1948, a first geothermal heat pump started operating in Ohio.
    23. Italy was the world’s single producer of geothermal electricity until New Zealand built a plant in 1958.
    24. Geothermal energy use in New Zealand started in 1958 when the first geothermal plant was opened in Warakei.

          Boise, Idaho was a location of the first U.S. district geothermal heating system built in 1892.

      Boise, Idaho was a location of the first U.S. district geothermal heating system built in 1892.

25. In 1960, a first-ever commercial geothermal unit started operating at the Geysers, California.

26. The fist binary cycle power plant was erected in 1967 in Kamchatka, Russia.

27. In 2006, a binary cycle plant in Chena Hot Springs, Alaska produced electricity at a record-low temperature of 134.6 degrees F (57°C).

28. Heating is the most common use of geothermal energy.

29. In over 70 countries, geothermal energy is used directly (geothermal energy from the Earth is used for residential heating).

30. The world presently generates 10,000 MW (10 GW) of geothermal energy per year.

31. Geothermal energy constitutes 0.4% of the world’s annual total production of energy.

32. The United States has the largest geothermal energy capacity with installed geothermal capacity of 3 GW.

33. In the US, geothermal electric power plants are located in California, Alaska, Florida, Idaho, Hawaii, Nevada, Oregon, New Mexico, Wyoming and Utah.

    The hot springs at Harkany, Hungary have been utilized as medicinal waters since the 1800s.

The hot springs at Harkany, Hungary have been utilized as medicinal waters since the 1800s.

34. The largest group of geothermal power plants in the world is located at The Geysers, a geothermal field in California.

35. The geothermal power plants in California are located in the Geysers (26 units), Imperial Valley East Mesa (6 units), Imperial Valley Heber (25 units), Imperial Valley Salton Sea (13 units), Coso (9 units), Mammoth (10units) and Honey Lake (3 units).

36. The geothermal capacity of California is 2.5 GW, supplying 4.5% of the state electricity generation.

37. Even though the US is the world’s leader in the development and production of geothermal energy, less than 1 % of its electrical requirements are met with geothermal energy.

38. The Philippines is the world’s second largest producer of geothermal energy for power generation, with an installed capacity of 1.9 GW.

39. Geothermal energy provides 16% of the Philippine’s electricity.

40. The world’s third producer of geothermal energy is Indonesia with capacity of installed geothermal plants of 1.2 GW.

41. The fourth largest producer of geothermal electricity is Mexico with 1 GW installed capacity. 3% of Mexico’s electricity comes from geothermal power sources.

42. he fifth largest producer of geothermal electricity is Italy with 0.8 GW of installed capacity, supplying 2% Italy’s electricity needs.

43. The capacity of installed geothermal plants in New Zealand is 700 MW.

44. Geothermal power in New Zealand provides 10% of the New Zealand’s electricity.

45. The capacity of installed geothermal plants in Iceland is 575 MW.

46. In Reykjavík, Iceland, used geothermal water from the district heating system is channeled below pavements, car parking areas and sidewalks to thaw snow.

47. The Geothermal Energy Association (GEA) says that geothermal power can meet the needs of 60 million people.

48. Geothermal energy delivers 20% of Iceland’s electricity supply. Most electricity in Iceland is produced by hydroelectric plants.

49. The improvements in geothermal energy technology could enable the US to obtain geothermal power for thousands of years.

50. In 50 years the US could use geothermal energy to produce 100,000 MW of electricity annually.

51. The Birdsville geothermal power plant is Australia’s only operating source of geothermal electric power.

52. South Australia has been referred to as “Australia’s hot rock haven”. Geothermal energy could provide 6.8% of its base load power requirements by 2030.

53. According to the Centre for International Economics, Australia has enough geothermal energy to contribute electricity for 450 years.

54. The simplest form of geothermal energy is a vapor-dominated system. Vapor-dominated sites are quite rare, but mechanically simpler and more efficient than any other type of geothermal power plant. In these systems, steam is produced without liquid water.

55. Hydrothermal systems use underground hot water or steam to convert energy from Earth’s heat into electricity.

56. Three kinds of hydrothermal systems exist: flash-steam, dry-steam and binary-cycle.

57. A 3,000-square-foot house in the US can be heated with a geothermal heat pump for $60/month.

    Hot spring in Yellowstone National Park, USA.

Hot spring in Yellowstone National Park, USA.

58. The cost of geothermal heat pump home system is about $7,500.

59. According to the Geothermal Energy Association (GEA), 50,000-60,000 geothermal heat pumps are installed in the US each year.

60. Google invested over $10 million in a geothermal research lab and energy companies in 2008.

61. Unlike weather-dependent wind and solar power, geothermal resources are available 24/7.

62. The emission intensity of geothermal electric plants is 122 kg of CO2 per MWh.

63. The thermal efficiency of geothermal electric plants is low (10-23%). According to the laws of thermodynamics, low temperature constrains the efficiency of heat engines in extracting useful energy during the production of electricity.

64. The capacity factor of geothermal power can be up to 96%. The average capacity is 73%.

65. Geothermal wells are rarely more than 2 miles (3 km) deep.

66. In 2004, 70 countries utilized 270 PJ (petajoules) of geothermal heating through direct use. More than 50% was used for space heating. Another 1/3 was used to heat pools. The rest was used by industry and agriculture.

67. Low-temperature geothermal resources (300 °F) have direct-use applications including district heating, fisheries, greenhouses, industrial process heating and mineral recovery.

68. Where natural hot springs are available, the warm geothermal water can be channeled straight into radiators. Due to its simplicity, this application of geothermal energy is more economic and efficient than geothermal electricity generation.

69. Water from geothermal sources may hold gases and toxic chemicals including antimony, boron, mercury, and arsenic.

70. Geothermal plants that emit harmful chemical compounds are commonly equipped with emission-control systems to reduce pollution.

71. Construction of geothermal plants can adversely affect land stability. Subsidence (land sinking) has occurred in Staufen im Breisgau, Germany and Wairakei, New Zealand.

72. Enhanced geothermal systems (EGS) may trigger earthquakes due to hydraulic fracturing.

73. Geothermal plants have negligible land requirements. Geothermal plants use 1.4 sq mi per GW of electrical production vs. 12 and 4.6 sq mi (32 and 13 km2) for coal and wind farms respectively.

74. Geothermal plants have negligible water requirements. They use 5.3 US galons (20 litres) of freshwater per MWh vs over 260 US galons (1,000 liters) per MWh for coal, oil and nuclear.

75. Geothermal energy requires no fuel except for pumps.

76. The use of geothermal energy is greatly flexible in size – from a small village to an entire city.

77. The world’s largest private geothermal electricity producer is Chevron corporation.

78. The most developed geothermal field in the world is the Geysers, California.

79. The Geysers, California is a vapor-dominated geothermal system.

80. The geothermal heat flows to the surface at a rate of 44.2 TW. The heat is replenished by mineral radioactive decay at a rate of 30 TW. These rates double humanity’s present energy consumption from all primary energy sources. Unfortunately, most of this power is not recoverable.

81. Flowers, fruits and vegetables are effectively grown all year long in geothermally heated greenhouses.

82. Geothermal aquaculture permits breeding in the winter, allowing fish farmers to harvest fish when market prices are high and product availability is low.

83. Geothermal energy works in three main ways: direct geothermal energy, geothermal heat pumps and geothermal power plants.

84. The direct-piped heating is the main application for geothermal energy in Iceland. The direct-piped geothermal water heats all of the buildings in Reykjavík, Iceland.

85. Iceland is located at the boundary of the North American and Eurasian tectonic plates. Owing to its location, Iceland is one of the most tectonically active places on Earth.

86. Iceland has over 600 hot springs.

87. Geothermal hot water heats 90% of buildings and houses in Iceland.

88. Geothermal power plants exist on all continents with the exception of Antarctica.

89. The capital cost of a geothermal power plant is much higher than that of a conventional fuel plant.

90. Geothermal power plants have a very long lifespan. The geothermal plant in Larderello, Italy has been operating for almost 100 years.

91. Geothermal power plants are not very loud and a noise hazard is negligible.

92. Geothermal system can be installed at isolated sites and may not require further infrastructure.

93. Geothermal fluids are transported in pipelines as long as 37.2 miles (60 km).

94. The outdoor pool in the Colorado Rockies, Colorado, is heated with water piped from a geothermal well.

95. Geothermal wells release very low level of greenhouse gases (GHG) per energy unit. Hence, geothermal energy has the capability to alleviate global warming if used instead of fossil fuels.

96. Geothermal energy is a renewable energy resource because the heat from within Earth is in no risk of being depleted. Precipitation constantly supplies water to geothermal reservoirs.

97. Geothermal energy is a sustainable energy resource because of its capability to sustain the Earth’s ecosystems. By using geothermal energy (and other sustainable resources) the present generations will not risk the ability of future generations to use their resources to the same amount that those sources are presently used.

99. As geothermal energy provides stable electricity, it can complement the irregular power derived by wind and solar.

99. Rotorua, New Zealand is well-known for its hot springs, volcanoes, geothermal fields and geysers. Several Rotorua homes use hot wells for heating and, amazingly, steam-barbecuing.

100. The first geothermal power plant in Philippines started operations in 1977.


Dickson, Mary H., and Fanelli, Mario. What Is Geothermal Energy. Publication. Pisa, Italy: Istituto Di Geoscienze E Georisorse, CNR, 2004. US Department of Energy. Available at

Grant, Malcolm A., and Bixley, Paul. Geothermal Reservoir Engineering. Burlington, MA: Academic, 2011.

Geothermal Energy Association. Available at

International Geothermal Association. IGA International Geothermal Association. Available at

Lee, Sunggyu, Speight, James G. and Loyalka, S. K.. Handbook of Alternative Fuel Technologies. Boca Raton: CRC, 2007.

Monroe, James S., Wicander, Reed and Hazlett, Richard. Physical Geology: Exploring the Earth. Belmont, CA: Thomson Brooks/Cole, 2007.

National Energy Authority of Iceland. National Energy Authority of Iceland. Available at

Povarov, Oleg, and Nikolskiy, Alexander. “Experience in Running Geothermal Power Plants in Severe Climate Conditions in Russia.” Workshop Abstracts. Proc. of Electricity Generation from Enhanced Geothermal Systems, Hôtel Régent, 14-16 September 2006, Strasbourg. Sept. 2006.

Science News, Articles and Information | Scientific American. Available at

Union of Concerned Scientists. Available at

Wachtel, Alan, and Voege, Debra. Geothermal Energy. New York, NY: Chelsea Clubhouse, 2010.


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  1. Sapphire Burns says:

    This information was REALLY useful

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