GeoThermal circulation to run a generator?

[AC_Hacker]

I think that an interesting way to look at this proposal might be to consider 'Heat Pipes'.

This principle is used in many evacuated tube solar collectors. The idea is to find an appropriate working fluid that would vaporize at a temp found at the bottom of the heat pipe, and change state into a liquid (condense) at the temperature found near the top of the heat pipe. The vaporization/ condensation point can be adjusted by changing the pressure of the working fluid.

The heat absorbed by vaporization and then released by condensation is considerably larger than the delta-T would suggest.

This would not supply enough heat to run an engine, but it could provide a way to bring low level heat energy to the surface, with no moving parts.

if the below ground temp is always ~55*

...the average temp depends on the latitude. It's around 55 degrees near the around here in Oregon, for instance, much warmer in the southern states, colder in the northern regions.

-AC_Hacker