[trencedamp]

I take your point that they rely on local conditions, but those conditions are certainly not as restrictive as for hydro.

[leonidasrup]

In most places, thermal conductivity of rock is very low.

"The conductive heat flux averages 0.1 MW/km2. These values are much higher near tectonic plate boundaries where the crust is thinner. They may be further augmented by combinations of fluid circulation, either through magma conduits, hot springs, hydrothermal circulation."

https://en.wikipedia.org/wiki/Geothermal_energy