You don't have to go out of your way to find doomsayers when it comes to methods of supplying the world's electrical power. Carbon emissions might melt the icecaps and drown whole cities. Nuclear power might turn the surrounding area into a radiated no-man's land. Biofuels could starve developing countries and further ravage the rainforests.
The severity of these threats really depends on whom you ask, but that's where the risks of artificial geothermal energy differ from everything else. Enhanced geothermal systems (EGSs) actually have produced earthquakes. On Dec. 8, 2006, Geothermal Explorers International managed to set off an earthquake in Basel, Switzerland, damaging buildings and terrifying the population. And while it only measured a 3.4 on the Richter scale, the quake was followed by 60 aftershocks in the weeks to follow.
Earthquakes typically occur around unstable areas such as volcanoes, fault lines and geothermal regions. So, any area ripe for enhanced geothermal tinkering is already prone to get the shakes. On top of that, pumping water down to subteranian regions of heated bedrock causes the rock to expand and contract, fracturing the rock. As such, seismic activity isn't just a side effect of the process, it's a part of the process. The deeper the shaft, the greater the chance that increased levels of seismic activity could reach nearby fault lines, generating an even more powerful earthquake.
Geothermal Explorers International and the Swiss government both attributed the earthquake in Basel to artificial geothermal energy, so operations there ceased. Still, that's not stopping the U.S.-based AltaRock Energy from trying the same thing in California. After all, there's a great deal of money to be made in alternative energy -- that is if you can avoid crippling litigation and seismic catastrophe.
Explore the links on the next page to learn even more about geothermal energy and the inner workings of the planet.