[yabones]

There's also a huge amount of internal friction created by the moon stretching and squeezing the earth, I believe that accounts for more heat than nuclear decay. Regardless, there's no way we can realistically impact planetary dynamics by blowing some cold water down tubes to the mantle, there's simply too much thermal mass - so yeah geothermal is a fantastic and reliable energy source.

[voldacar]

>There's also a huge amount of internal friction created by the moon stretching and squeezing the earth

Wow, I hadn't even thought of that. How much heat does this produce, roughly? For context, the total heat lost from the earth's interior is about 47 TW according to another comment, so in order for the earth to not heat up I assume that moon friction heat + nuclear decay heat < 47 TW?