THE VINE OCTOBER 31, 2008
Normally, when people prattle on about renewable energy playing a major role in a post-carbon world, they tend to mean mainly solar and wind power—with maybe a passing nod toward biomass and biofuels. But David Biello argues that geothermal may be nothing to sniff at, either. Sure, with current methods, geothermal is expected to satisfy—at most—only about 5 percent of America's electricity needs by 2050 (it doesn't cost that much more than burning coal, and any modest price on carbon would easily close the gap). But now some researchers are looking into "enhanced geothermal systems," which could do much, much more:
Today, The Geysers, the largest geothermal power plant in the world, produces enough electricity for 725,000 homes. The more than 1 gigawatt of geothermal power currently produced globally—from California to Iceland to the Philippines—relies nearly exclusively on such natural outpourings of the earth's heat. Already, there are more than 3,000 megawatts of geothermal capacity in the United States—the bulk of it at the The Geysers—and as many as 100 new geothermal power plants are proposed for promising sites. This week, the U.S. Interior Department announced it would make more than 190 million acres of federal land available to lease for geothermal development.
But mimicking nature—drilling deep beneath the surface, fracturing the rock and pumping water through it to capture heat—could unleash a torrent of geothermal power, according to the recent MIT report, "The Future of Geothermal Energy." Such a manmade geothermal system could harvest as much as 40 percent of the heat in the bedrock and convert 15 percent of it into electricity via simple low-temperature steam turbines at the surface, according to mechanical engineer Ron DiPippo at the University of Massachusetts, Dartmouth, a member of the MIT report team.
The researchers estimate that for just $1 billion invested over 40 years—the cost of one large coal-fired power plant and a fraction of the cost of a nuclear power plant—100 gigawatts of clean, dependable geothermal power could be developed in the United States alone. That’s the energy equivalent of more than 200 coal-fired power plants or 100 new nuclear power plants.
Let's see, add up the billions, carry the one… yeah, getting the clean equivalent of 200 coal plants for the price of just one dirty plant sounds like a great deal, if it were doable. And, on the plus side, geothermal systems aren't intermittent like solar or wind—so there'd be no issues supplying baseload power. It's just that the technology's not yet feasible, drilling that far down into the earth is still costly, it would require pumps that can withstand a terrific amount of heat, earthquakes are a potential issue… Still, it doesn't sound like a total fantasy: Australia's embarked on a crash program, Congress is mulling more money for research, and Google.org's curiosity was sufficiently piqued that it recently gave $11 million to two geothermal start-ups. Here's a video they made on EGS: