If we need power why not try using the Yellowstone super volcano as a source. It can and most likely will have many ups and downs to it but what doesn't. Many people will not get it at first but in time i hope people will be able to get it and in the end I hope the Yellowstone super volcano will help us all with power and many more things in the near future.
Yellow stone reserve stands atop a massive puddle of molten rock, Not to mention it's active state. If we extract the heat from the top layer of the molten rocks, They will begin to solidify which would in turn increase the pressure underneath. It would be like putting an airtight lid over a boiling water pot.