By Andrew Nusca
Posting in Energy
Two major geothermal projects in the U.S. and Europe were both permanently abandoned last week after officials said they could cause earthquakes.
A form of "clean energy," geothermal energy projects deliberately drill into the Earth to harness its inherent energy in the form of heat. But the projects, located in northern Carlifornia and Basel, Switzerland, were deemed too dangerous and capable of triggering earthquakes.
The California project, located 100 miles north of San Francisco and operated by AltaRock Energy, was put on hold in September after the company's drilling efforts met "physical difficulties" in the form of snapping drill bits. The project is located in The Geysers, the world's largest dry-steam geothermal steam field.
The Swiss project has been on hold since 2006, when it caused a 3.4 magnitude earthquake thousands of aftershocks and millions worth of damage in Basel, a town of about 167,000 people.
Both projects were based on an "enhanced geothermal" system, which fractures bedrock and circulates water through the cracks to heat it and produce steam that powered the turbines of a power plant. Naturally, both projects were also based in areas with a history of seismic activity.
The projects were originally supposed to force water underground to open new cracks, into which workers could then pump additional water, to be heated and turned into steam.
Geothermal energy is currently used to heat and cool homes by circulating fluids at shallower depths to be passively warmed by the Earth's heat. But scaling that technology requires companies to tap into heat at much deeper levels.
By name alone, it's no surprise that the "fracturing" process can cause earthquakes. Most are small enough to go unnoticed.
But a Swiss government study released last week showed that the $60 million geothermal project was likely to cause earthquakes that would do several millions of dollars in damage each year. Residents could expect anywhere from 14 to 170 more earthquakes, most minor, over the 30 years the project would be in service.
U.S. officials have not yet completed a study on the California project, but the company said it is now removing its drill rig due to its difficulties drilling into resident caprock. The project had won a $6 million grant from the Energy Department and $30 million in private investment.
The U.S. Department of Energy remains optimistic on geothermal power as a clean energy source. The department is working on drafting its National Geothermal Action Plan and has invested more than $400 million in geothermal projects in 2009 alone, including enhanced geothermal projects in Idaho, Nevada and California.
Dec 15, 2009
Any facility has a measure of risk. Many passive systems don't have to be in fault zones but some active systems are located among those zones. Local conditions have to be regarded for energy provision as well as distribution. Subsurface geology is both a blessing and safety concern. Yet, these two particular facilities seem to have encountered different issues within a very broad time frame. It is plausible these injection-type facilities could create more risk though. Also, it appeared that the Swiss sight was the only one actually halted due to the allegedly induced quake while the California sight encountered technical difficulties. Maybe due to fault slippage during drilling. However, the Swiss sight has been static since 2006 so why dig it up? Was the Swiss sight actually blamed for the tremor or is it still under investigation? I'm sure there are other facilities operating but recognize their limitations to manage their risk.
My reaction was the same as yours. The authors need to create their title more accurately. Such sloppiness creates a lot of confusion among people who are unfamiliar with the subject. We have a closed loop geothermal system to heat our house and we are very pleased with it, but then no bedrock was disturbed during installation either.
Geothermal energy is a very broad term so perhaps you should ask if 'Enhanced Geothermal Systems' are too risky, because the answer is obviously 'it depends.' No two locations are going to be identical. Geothermal is a lot more than just power and heat pumps, which by the way are two entirely different technologies. One generates electricity and the other uses electricity for heating/cooling buildings. Geothermal also includes direct uses like district heating, agra/aquaculture uses, de-icing, dehydration, Next time try using a ball-peen hammer rather than a sledgehammer.
It is definitely too risky for CA. They are bankrupt and trying to build a new stadium for another NFL team. On second thought, maybe they should go with it.