US to tighten geothermal drilling rules amidst earthquake fears

2010-01-19 from:BusinessGreen author:Tom Young

Leaked documents suggest geothermal energy developers will be forced to monitor seismic activity more closely

The US Department of Energy (DoE) is to impose new safety regulations on geothermal energy projects designed to address fears that drilling deep holes in order to access energy released by so-called hot rocks could increase local earthquake risks.

According to documents seen by the New York Times, the new safeguards include a requirement for projects to install and monitor ground-motion sensors, and develop a plan to shut down quickly if earthquakes generated by drilling prove larger than expected.

The new rules, which would apply to around 150 US geothermal projects currently in the running for government funding, would also require projects to run plans past seismology experts before they can receive approval for drilling.

Geothermal energy systems typically work by drilling boreholes to access hot bedrocks that are often buried deep underground. Water is then pumped into the boreholes where it creates steam that can be used to drive turbines and produce power.

Advocates of the technology argue that it could provide huge amounts of reliable zero carbon power.

However, there have been concerns that the drilling of deep boreholes can result in an increased risk of small earthquakes which, while unlikely to be large enough to cause serious damage, could affect buildings' foundations.

The new US safeguards look set to be introduced after a project run by Altarock Energy in California was reportedly shut down because of concerns over the impact of drilling.

Altarock has denied allegations from local residents that it underplayed the earthquake risks associated with the project, and refused to comment publicly on whether its drilling operation at the site is still going ahead.

But the New York Times reports that the Department of Energy, which partly funded the project to the tune of $9m (£5.5m) as part of a $338m boost for geothermal included in the US stimulus package, now considers the project to be closed. The paper also reported last month that the company had removed its drill rig from the site.

Last month a $60m geothermal project near Basel, Switzerland, was also shut down after a government study determined that earthquakes generated by the project were likely to result in millions of dollars in damage each year.

The report found that residents of Basel would have felt between 14 and 170 small earthquakes over the 30-year life of the project, though few if any of those earthquakes would be likely to cause bodily harm.