I would have guessed Iceland, but it’s actually the U.S.:
As policymakers promote alternative energy sources to reduce the United States’ emissions of greenhouse gases and its dependence on foreign oil, entrepreneurs are becoming increasingly inventive about finding novel ways to power the economy.
Beyond solar power and wind, which is America’s most developed renewable-energy sector, a host of companies are exploring a variety of more obscure technologies. Researchers are trying to come up with ways to turn algae into diesel fuel. In landfills, startups are attempting to wring energy out of waste such as leaves, tires and “car fluff” from junked automobiles.
It is hard to predict what portion of the country’s needs could be met by these emerging technologies. The United States is already the world’s largest producer of geothermal electricity, with 212 plants generating 3,119 megawatts. A panel convened by the Massachusetts Institute of Technology concluded in a recent report that by 2050, geothermal plants could produce 100 gigawatts, which would be equivalent to 10 percent of current U.S. electricity capacity.
To be honest, I never think too much about geothermal, because I always thought of it as a niche application. I had no idea the U.S. produced that much geothermal energy. To put the 3,119 geothermal megawatts in perspective, installed wind capacity is about 12,000 megawatts in the U.S., and installed solar PV is about 6,000 megawatts. And to put those numbers in perspective, installed nuclear capacity is 100,000 megawatts, and installed coal capacity is 335,000 megawatts.