What is geothermal energy?

Geothermal energy is thermal energy extracted from the Earth's crust, originating from planetary formation and radioactive decay. It has been used for millennia for heating and, since the 20th century, for generating electricity at a constant rate regardless of weather. Most extraction occurs near tectonic plate boundaries, and the resource is considered a sustainable, renewable form of energy.

What we know

• Geothermal energy combines thermal heat from the planet's formation and from radioactive decay within the Earth's crust. [2]
• Geothermal power plants produce electricity at a constant rate regardless of weather conditions. [2]
• Most geothermal extraction occurs in areas near tectonic plate boundaries where volcanic activity rises close to the surface. [2, 4]
• Greenhouse gas emissions from geothermal electric stations average about 45 grams of carbon dioxide per kilowatt-hour, representing less than 5% of conventional coal-fired plants. [3]

Still open

• Estimates of total global geothermal potential vary significantly, with the Geothermal Energy Association estimating only 6.9% tapped while the IPCC reports potential to be between 35 GW and 2 TW.

Where to go next

• how it workedHow is electricity generated from geothermal sources?
• a case in pointHow does geothermal heating work?
• the bigger pictureWhat are renewable energy forms?
• whenHow did geothermal energy use evolve over time?
• whereHow is geothermal energy developed in Ukraine?
• an unexpected connectionHow does radioactive decay heat the Earth from within?Geothermal energy relies not only on leftover heat from the planet's formation, but also substantially on ongoing radioactive decay of minerals deep underground.

Sources

• [1]geothermal energy (Wikidata Q127993) · CC0 1.0
• [2]Geothermal energy · CC BY-SA 4.0
• [3]Geothermal power · CC BY-SA 4.0
• [4]Geothermal heating · CC BY-SA 4.0
• [5]Geothermal energy in Ukraine · CC BY-SA 4.0