[telchar]

Most geothermal heat is produced by nuclear decay in subsurface radioisotopes vs gravitational/frictional source or residual heat of planetary formation, so it's effectively renewable at any kind of level of extraction that we might feasibly be able to make use of.

"About 2,900 kilometers (1,800 miles) below the Earth’s crust, or surface, is the hottest part of our planet: the core. A small portion of the core’s heat comes from the friction and gravitational pull formed when Earth was created more than 4 billion years ago. However, the vast majority of Earth’s heat is constantly generated by the decay of radioactive isotopes, such as potassium-40 and thorium-232."[0]

[0] https://education.nationalgeographic.org/resource/geothermal...

[jacobsimon]

Interesting! This might be my favorite type of energy now :D