Earthquakes: The Other Side of Drilling for Geothermal Power

Geothermal technology surely is one of the cleanest technologies available to us, extracting clean heat from the hot underground. This energy source is often seen as inexhaustible, and its benefits seem to outweigh its weak points. For decades, geothermal companies have been drilling into Earth’s crust at depths of over 4-5km.

You can’t just dig anywhere to find real, efficient, abundant geothermal energy – it has to be an area where the crust is thinner, so to reach the outer core. If you want to heat up your home, for example, you don’t need to dig that low; a few tens of meters are enough. Still, if you’d like more, you have to go deep.

Going that deep implies nothing bad at a first glance, but taking a second look above everything, you can cause an earthquake. That’s what happened in Basel, Switzerland just a few years ago, and that’s what’s beginning to happen 90 miles from San Francisco, in Anderson Springs. The drilling in Basel caused a magnitude 3.4 geothermal earthquake.

Scientific American digs into this matter in an interview with U.S. Geological Survey Earthquake Hazards Team seismologist David Oppenheimer, who is based in Menlo Park, Calif., just a couple hours south of Anderson Springs area. Mr. Oppenheimer explains how geothermal drilling can be made safe and how measures are being taken to prevent geothermal earthquakes from happening. Still, if they happen, he says, they’re guaranteed not to exceed 2 Richter-scale degrees.

The project in Anderson Springs has big stakes: the U.S. Department of Energy has already chipped in $36 million for AltaRock’s project. In an effort to drive down the price of renewable energy, Google has financed it with up $6.25 million, the Times reported.

The phenomena is the following, as explained by David Oppenheimer: “Here’s what we know: You can think about The Geysers-the upper three miles (4.8 kilometers) of crust-as a sponge, and the sponge is wet. Now we’re taking fluid out of the sponge, and we’re taking heat out of the sponge. When you dry out a sponge, it contracts. The Geysers is contracting. From the data, we can see it pulling in, which means that it’s changing the stress field around it. Surrounding the field are some active faults, which have the capacity for some larger earthquakes. So one day one of the tectonic faults is going to move.”

Every source of energy seems to have its drawbacks: we know them for oil, wind mills can disturb the birds and the wind activity, biofuels cause starvation in the long run, and here’s the geothermal drilling kicking in. These facts are known for decades, but the winning technology is the one who will manage to naturally minimize all the side effects. In my opinion, solar is the most promising. All we have is to capture what we are “given”, and do what we want with it.

With all the technological advancements going on, and despite all the efficiency increasing from year to year, we still consume more and more, because the efficiency can make us afford this consumption. There is a critical point, though, where nature will say “Stop!”, and then we’ll stop. Will it be geothermal earthquakes, or floods, or global warming, I don’t know. All I know is that, from time to time, we have to keep our money into our pockets and stop spending so much energy. I must say that the Earth seems to be alive, with the risk of being non-scientific. Alive in a different way, at least.