Geothermal energy, the sexy kind, involves drilling in volcanic areas and running natural superheated steam through a power plant. But a lot of potential lies in low-temperature situations in unexpected places. Ordinary seasonal climatewarm summers and cold winterscreates temperature differences between the surface and underground that can be exploited for heating and cooling. Individual houses can use heat pumps, for instance, to play the constant underground temperatures against the fluctuating surface conditions. But the real payoff is in large, municipal scale systems. In upstate New York, Cornell University uses the cold bottom water of Cayuga Lake this way.
What if your city has no large lake nearby? The British Geological Survey is looking at old flooded mines, something never treated as a resource before. BGS announced last week that Glasgow, Scotland could satisfy 40 percent of the city's heating by extracting energy from the cold watery labyrinth beneath it. See more about it on the BGS blog.