Earth's heat
Heat from the Earth's interior, kept up by radioactive decay deep underground.
Natural sources · Earth, gravity and atoms · No. 17
- Natural sources
- Origin: Geothermal
- Renewable: Yes, if managed well
The Earth leaks about 47 TW of heat, around 2.5 times world energy use, but only hot spots are easy to tap.
Chart: Illustration: Earth's heat
Where it comes from
Chart: Map of where it comes from
Heat left over from the planet's formation, topped up by decaying uranium, thorium and potassium, seeps out slowly and is tapped where hot water sits near the surface.
Three things to know
- China leads direct use of geothermal heat by far, with an estimated 603 PJ in 2024, mostly for heating and bathing.
- At Wairakei in New Zealand, the ground sank 15 m after 50 years of fluid extraction.
- The US lists 4.0 GW of geothermal nameplate capacity but had only 2.7 GW actually operable at the end of 2024.
The journey
- 1 Deep EarthFormation heat plus radioactive decay
- 2 Hot rockHeat stored in rock and fluids
- 3 Hot spotsPlate boundaries and volcanic zones
- 4 WellsBring hot water or steam up
- 5 Power and heat99 TWh electricity, 245 TWh heat, 2024