The energy search goes underground — not for oil, but for hot rocks:
Scientists say this geothermal energy, clean, quiet and virtually inexhaustible, could fill the world’s annual needs 250,000 times over with nearly zero impact on the climate or the environment.A study released this year by the Massachusetts Institute of Technology said if 40 percent of the heat under the United States could be tapped, it would meet demand 56,000 times over. It said an investment of $800 million to $1 billion could produce more than 100 gigawatts of electricity by 2050, equaling the combined output of all 104 nuclear power plants in the U.S.
But there are downsides:
A so-called hot rock well three miles deep in the United States would cost $7 million to $8 million, according to the MIT study. The average cost of drilling an oil well in the U.S. in 2004 was $1.44 million, according to the U.S. Energy Information Administration.Also, rocks tapped by drilling would lose their heat after a few decades and new wells would have to be drilled elsewhere.