Geothermal energy is not discussed enough, probably because it is too expensive to install. The government should mandate that there should be a universal price or that a consumer gets a huge tax break to help offset the costs of installation.
I installed a geothermal heating, cooling, and hot water system in my home 6 months ago after doing much research on all types of systems. The cost was $32K, versus a super high-efficiency propane or oil system at $20K. Based on then-current propane and oil costs, I calculated that my break even point was about 30 years--not so good. But of course as fuel costs rise, the break even point gets shorter. Already home heating oil in my area has gone from $2.75/gallon to $4.99/gallon. Break even is now down to about 12 years at that price. BTW, I think I got a tax credit of $300--less than 1%... that's pathetic.
For efficient geothermal operations, you have to drill the wells in areas where geological heat is near the surface. You are in such an area when you see volcanic activity and/or geothermal hot springs. In the U.S., this mainly means Alaska, Hawaii, the entire west coast and the biggest of all: Yellowstone. The Yellowstone area alone has enough potential power to cleanly supply all of our energy needs (at 2007 levels) for 700,000 years!
Unlike solar and wind, which vary depending on season and local weather conditions, geothermal produces clean energy at the lowest cost per KW hour day and night, year in and out. I strongly believe geothermal has to be part of the overall mix of non-fossil fuel alternates.
Please check out the following. This small company had dramatically reduced the cost of Geothermal by using a couple new technologies and modularizing the systems required to put power on the grid. They have dramatically reduced the infrastructure requirements and are able to get power out of much lower temperature sites...