This is interesting. Someone has come up with a proposal to use underground C02 storage sites for geothermal power. Here's the writeup at If We Can Bury Carbon Dioxide, Why Not Use It to Make Electricity? Excerpt:
In conventional geothermal plants, water and steam heated by hot rocks deep underground drive turbines in a power plant. The water is then pumped back underground to be heated up again.
The new technology would use carbon dioxide instead of water. This approach has several potential advantages. By eliminating the need for water, it increases the prospects for geothermal projects in dry areas. And computer simulations show that CO2 could produce twice the electricity from a given area that water produces, says Martin Saar, a professor of geology and geophysics at the University of Minnesota. Saar is cofounder of Heat Mining, a company that plans to test this technology in a small power plant that it will build next year.
It's all based on computer simulations so far, and we saw how far astray those things led some people about global warming. But it just might work. Read the whole thing to see the pluses and minuses of the project.
Meanwhile, speaking of global warming, this is interesting, too: Study: El Nino caused half the global warming since 1970s.