The Status and Future of Geothermal Electric Power by Charles F. Kutscher, NREL from the Proceedings of the American Solar Energy Society Annual Conference proceedings, June, 2000.
http://www.ecotopia.com/apollo2/geothermalstatus.pdf
This is quite an interesting report for USA viewers. It shows the areas (Fig 1) in the western US where geothermal energy can be used to generate electricity. He also says that currently (in 2000) identified resources could provide 20,000 MW of power and undiscovered resources might provide 5 times that amount.


