Why not, when the mine is done, install a bunch of turbines in the shaft and pour a bunch of water down to 4km, send the steam back up to the top and voila! Endless power.
The fun part is remembering most of geothermal power is derived from nuclear decay. So really, it's nuclear power!
Of course, really, in the end everything is nuclear power. Sunlight (solar panels) is a byproduct of nuclear activity. Fossil fuels are plants that grew by the light of the sun; wind is a result of heating of the atmosphere by the sun, and hydroelectric is a result of heating of the ocean by the sun.
(stretching, I know)... yet the power systems use something more than hydrogen and helium so are made of fusion byproducts from stars. ("We are all starstuff.")
