Using CO2 to Make Geothermal Energy More Practical

via Ritholtz, Fast Company has the story:

The way geothermal energy is usually tapped for power generation is by drilling a couple of shafts deep into the earth, and pumping high-pressure water down one shaft. This makes its way through a hot rock layer (which gets its heat from the essentially inexhaustible energy of nearby plumes of hot lava) to the second shaft, picking up heat en route. The resulting steam is used to push a turbine, and generate power.
Except that two scientists pondered: What if the water in this equation was replaced with high-pressure carbon dioxide? Because it's a gas rather than a liquid, CO2 can ferret its way into more and tinier cracks in the sub-surface hot rocks than water--making the new system more feasible in areas water-based geothermal sources aren't deemed practical.

I wouldn't vouch for the practicality of this scheme.  It approaches the too-good-to-be-true criteria in my opinion, but it is something to think about.