On paper, at least, "enhanced" geothermal is an incredibly alluring concept. The idea is to bore down, really deep down into the Earth's crust—say, 12,000 feet below the surface—and then pump water through the cracks in the hot bedrock, creating steam to generate electricity. Last year, an MIT report on "The Future of Geothermal Energy" calculated that, if you could make this technology work, the capacity would be staggering: For a mere $1 billion invested over 40 years—the cost of a single large coal-fired plant—we could get 100 gigawatts of carbon-free power, the equivalent of more than 200 coal-fired plants.
So what's the hold-up? Turns out it's not such a snap to grind that deep into bedrock. As James Glanz reports today in The New York Times, one pilot project, financed by the Energy Department and located at the Geysers north of San Francisco, has been bumping up against serious obstacles. Like cap rock. Not only does the drill bit keep fouling up (or even, on occasion, snapping), but there are newfound fears that the drilling could generate earthquakes, which is what happened at a test site in Basel, Switzerland:
The fracturing would be virtually guaranteed to induce earthquakes, which the company has said would be so small as to be nearly imperceptible but which local residents and some scientists fear could be larger. The project is in one of the world’s most seismically active areas.
Although the Basel earthquakes caused only minor structural damage, they frightened many in the city and led to the shutdown of the project there. The Energy Department review, likely to be released in the next few weeks, is expected to compare the Basel and California projects and determine whether AltaRock’s effort is safe.
Much sniping ensues, in which the company doing the drilling, AltaRock, claims that the Swiss were stupidly drilling near a known fault line, and the Swiss accusing the company of lying. If you like earthquake intrigue, read the rest. Though it'd be a real shame if this project had to shut down, seeing as how enhanced geothermal's clean-energy potential is so enormous.
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COMMENTS (1)
Reprinting old comments...
dhauck said:
Turns out it's not such a snap to grind 2.25 miles into bedrock? Huh. Who knew?
But, Brad, why do we have to drill so far down in an area known as "the Geysers"? And aren't there plenty of places like that (just look for geysers, volcanoes, etc.) where we could just scratch the surface to get the heat that we need? To be honest, if we could pull this off, this sounds a lot more like the future of energy production than wind, solar, or even nuclear.
Besides, I've seen "Journey to the Center of the Earth". If you dig too far down, you might let out the dinosaurs that live down there. And man, they are going to be PISSED when they ... view full comment
Reprinting old comments...
dhauck said:
Turns out it's not such a snap to grind 2.25 miles into bedrock? Huh. Who knew?
But, Brad, why do we have to drill so far down in an area known as "the Geysers"? And aren't there plenty of places like that (just look for geysers, volcanoes, etc.) where we could just scratch the surface to get the heat that we need? To be honest, if we could pull this off, this sounds a lot more like the future of energy production than wind, solar, or even nuclear.
Besides, I've seen "Journey to the Center of the Earth". If you dig too far down, you might let out the dinosaurs that live down there. And man, they are going to be PISSED when they see what we've been doing with their ancestors' remains!
August 20, 2009 5:44 PM
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JEFF FREY said:
There is already a fairly large geothermal power plant at the Geysers, and has been for years. They have been tapping the shallow reservoir for years.I don't know the details of the deep drilling project, but I suspect they tried it there because they knew it would be hot enough at depth.
Away from tectonic plate boundaries (which are hotter), the typical geothermal gradient is 25-30C per kilometer of depth. 12,000 feet or 4 km gets you to maybe 100-150C, depending on where you are. Plenty hot enough to boil water, but you have to keep the steam or hot water hot enough on its way back to the surface, so deep geothermal does not seem like a trivial solution to our energy problems. But yes, potentially a huge source of power.
The typical problem with geothermal even at volcanoes is that the heat source is not necessarily shallow (or may be too small), and the cost of building transmission lines to use the power can be excessive. But there are plenty of examples of such plants around the world where the conditions are right, and I know that more are planned.
August 20, 2009 6:10 PM
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Brad Plumer said:
A big reason AltaRock chose the Geysers site, it seems, was that they could start drilling at a hole that was already 3,200 feet below the surface--so they would only have another 8,800 feet to go. And I guess the thing about enhanced geothermal is it has a *lot* more potential than regular old geothermal, so even if you already have an existing geothermal plant, it still might be worth it to dig down even deeper and get at those super-hot rocks. (Assuming this project even works.)
And honestly, I can't imagine dinosaurs would be too pissed off at our museum system, though if it turns out we've made some error and put a human head on a brontosaurus body or some other grievous desecration, all bets are off, really.
August 20, 2009 6:25 PM [Delete]
kerFuFFler said:
This article reminds me of the ignominious conclusion of "project Moho" (aka "project Mohole"). At the same time that NASA was successfully putting a man on the moon in the late '60's, scientists were throwing in the towel over efforts to dig a really deep hole. The goal was to reach down to the "Mohorovicic Discontinuity", the boundary between the earth's crust and the mantle------- about 7 kilometers beneath the ocean floor.
In principle the project seemed simple enough. But think how deep you can dig on the beach before the sides collapse and fill the hole. Cost overruns forced the project to close down.
Now, forty years later, lessons learned from oil drilling have enabled scientists to drill deeper, but it is still very expensive. Geothermal energy has been most effective in places like Iceland where there is a lot of energy near the surface, and where the distances are so small that transmission poses no obstacle. But, boy, when you can get it geothermal energy is GREAT! Iceland heats almost 90% of its buildings------ and hot water too!------ and additionally powers 26% of its electricity with geothermal energy. Must be nice!
Brad, as far as angry dinosaurs go, I'm sure spiritual dinosaurs cannot be happy about the practice of digging up the remains of their relatives for science museums, and even worse are the displays at the Creation Museum which are used to bolster religious views very much at odds with orthodox dinosaur theology.
August 23, 2009 5:58 PM