Earthquake concerns shake energy projects

Disappointing, but not surprising.

http://www.msnbc.msn.com/id/34449056/ns/technology_and_science-future_of_energy/

By Charles Q. Choi
updated 1:28 p.m. ET, Wed., Dec . 16, 2009

Hard times are now bedeviling geothermal energy projects that risk triggering earthquakes as they delve miles deep into the Earth to tap clean and virtually limitless energy.

One such enhanced geothermal system, as they are known, caused a magnitude 3.4 quake in Basel, Switzerland, in 2006. A case in court against the head of the firm behind the work, Markus Häring of Geothermal Explorer, started yesterday on charges of property damage.

Meanwhile, a company running a federally funded enhanced geothermal system in California, AltaRock Energy, declared Dec. 11 it was abandoning the project, just one day after Switzerland permanently shut down the Basel system.

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Conventional geothermal energy taps into energy near the surface. Enhanced geothermal systems, on the other hand, drill more than a mile down to access hot dry rock or magma, and pressurized fluid is pumped in to generate steam that can drive turbines. Scientists note the technology remains a promising source of alternative energy, but caution that its risks need more research and open discussion so that people and authorities don't overreact.

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The drawback of enhanced geothermal systems is the fact that they can trigger earthquakes. The pressurized water forced into the rock generates micro-earthquakes. It can also interact with existing deep faults, potentially causing larger temblors.

That is precisely what happened in Basel. The city has a history of earthquakes — in 1356, the city was severely damaged by a magnitude 6.7 quake, the largest ever recorded in central Europe, Giardini noted in a commentary that will be published in the Dec. 17 issue of the journal Nature.

"Basel was probably one of the worst places one could have started from," Giardini said. "Enhanced geothermal systems in the future probably should not focus on cities with a past of devastating earthquakes."

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A number of other enhanced geothermal systems are active in Europe, some of which have been linked with earthquakes.

At two megawatts, the European Hot Dry Rock geothermal energy project in France will be the largest commercial enhanced geothermal system in operation. It was linked with magnitude 2.9 activity, but was adapted to reduce quake risk, and is scheduled to begin generating electricity in January. The work there is carried out in a more rural area without a known history of large earthquakes.

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