Because areas in the U.S. with the hottest rocks tend to be more seismically active, the success of the American ventures -- based primarily in the West -- will require careful site selection. At the time, Häring's rudimentary seismic analysis seemed sufficient to most experts, says Domenico Giardini, the director of the Swiss Seismological Service. The mess actually inspired more-rigorous testing, and so he and Williams think other facilities can be successful, provided that the quake risk is small. "As long as you do this far away from inhabited areas, there shouldn't be a problem," Giardini says. "But for cities with a history of earthquakes, it's probably best not to install enhanced geothermal." To wit, the DOE directed the bulk of its $100 million to projects in rural areas of California, Idaho, Nevada and Oregon.