They said something similar about oil.
(
Mu Dinofiddler,
Thu 17 Jun 2010, 15:26,
archived)
We could certainly do some awesome stuff if we used all the earth's geothermal energy.
It mostly comes from decaying radioactive elements. I don't think the Earth is doing anything useful with it.
(
_Felix 's school of dance and occult sciences,
Thu 17 Jun 2010, 16:05,
archived)