STEVE INSKEEP, host:
The BP spill reminded us of some of the environmental costs of the energy on which we all depend. Turns out the Federal Department of Energy calculates there is enough clean energy below our feet to keep the whole country humming with electricity for thousands of years.
The question is how to get to that energy. And we'll talk about it this morning as we continue our reports with member station KQED on California's clean energy goals. Craig Miller reports on a hot prospect of a hidden energy source.
CRAIG MILLER: Stop most Californians on the street and ask them where the state gets most of its renewable energy and they'll say...
Unidentified Man #1: I guess the sun.
Unidentified Woman #1: I would guess wind.
Unidentified Man #2: Not really, I would say, like solar power.
Unidentified Woman #2: Let me guess. Ill go dams. How about that?
(Soundbite of laughter)
MILLER: Good guess. Hydro-power is still out front. But theres another big one that almost nobody guesses. And its up here, on a ridge-top crisscrossed with pipes, about two hours north of San Francisco. This is the Geysers, the worlds biggest field for producing geothermal energy. Wandering around up here is sort of like hiking across the top of a tea kettle - pipelines hiss with steam pressure tapped from far below the surface. The steam drives turbines to generate electricity.
Plants like this one provide twice as much renewable energy in California as wind and solar combined.
Mr. JIM TURNER (Chief Operations Officer, AltaRock Energy): The pot of gold, if you will, is that we have a huge renewable energy resource that produces base-load electrical power, which is what geothermal does.
MILLER: When I visited here last year, Jim Turner was running the field operations for AltaRock Energy.
Mr. TURNER: Unlike solar, which you have to have the sun shining, or wind, you have to have the wind blowing, geothermal is basically running all the time.
MILLER: The trouble is that after several decades, some conventional geothermal sites are literally running out of steam. So AltaRock was trying out a new technology to boost the output...
(Soundbite of machinery)
MILLER: ...drilling a hole 10,000 feet down, to where the Earth's natural radiation heats the rock to about 500 degrees. This enhanced geothermal process forces water from the surface into those spaces, releasing more steam than would naturally work its way up.
Mr. JOHN GEESMAN (American Council on Renewable Energy): At its root, it's hot rocks.
MILLER: John Geesman co-chairs the American Council on Renewable Energy and is a big fan of geothermal.
Mr. GEESMAN: The challenge is a technological one, and that is harvesting that resource in an economic and environmentally acceptable fashion.
MILLER: And there is a minor public relations issue. It's been know to cause, well, earthquakes - small ones at least. A series of them shook downtown Basel when a similar kind of work was tried in Switzerland.
David Oppenheimer is a geologist with the U.S. Geological Survey and was part of a federal review of the seismic risk.
Mr. DAVID OPPENHEIMER (U.S. Geological Survey): Think of it as a sponge, a big wet sponge. That's the Earth's crust.
MILLER: And, as anyone knows, when you wring out a wet sponge and let it dry, it shrinks.
Mr. OPPENHEIMER: It's got all these little tiny fractures, and then they come in with their wells, their steam wells or their injection wells, and they start taking out heat and they start taking out water. The area is contracting and these fractures are moving. So you have the conditions for small earthquakes, but big earthquakes are rather unlikely.
MILLER: The Department of Energy agreed with Oppenheimer that AltaRocks plans did not pose a significant earthquake risk.
Mr. OPPENHEIMER: You know, there is no source of energy that I'm aware of that is completely benign. And in this case, this is actually a pretty attractive renewable energy resource.
MILLER: But you still have to get at it. AltaRock eventually gave up on its well in California when the bore hole kept collapsing, and moved on to a new site in Oregon.
Still, geothermal technology is attracting money from top venture capital firms, and even Google, which has money in AltaRock.
Bill Weihl is Googles green energy czar, and thats actually his title.
Mr. BILL WEIHL (Green Energy Czar, Google): Enhanced geothermal in particular, where you can access heat virtually anywhere on the planet, by drilling deeply, is scalable. So it could satisfy a very large - potentially very large fraction of our energy needs.
(Soundbite of geysers)
MILLER: No, not right away. Eighty percent of the nations geothermal energy is still produced in California. But federal stimulus money is driving more than a hundred projects across the U.S.
For NPR News, Im Craig Miller in San Francisco.
INSKEEP: We dont know if California really will lead the way in renewable energy. But we're certainly learning a lot from what they're trying. And we continue tomorrow by looking at a new frontier for renewable energy: tribal lands. Windmills and solar panels could replace casinos as a source of revenue on the Rez.
It's NPR News.