Whaaattt?

I wonder what you plug them into?

 

The Eden Project has been heated by geothermal energy for a few years now. It's quite expensive to install.
Also Earth's heat to produce electricity for homes in UK clean energy first both are in Cornwall.
Iceland has done more with geothermal than we have, but the heat source there is closer to the surface.
In theory it's possible to use heat pumps to extract energy from flooded coal and tin mines, but I'm not aware of any projects to do this.

 

A regular socket, as far as I can tell, though I am the first to admit my understanding of "how to use the sun's rays to boil a kettle" is shaky!