While geothermal power has always been a very small part of the renewable energy mix in the U.S., there have been signs that it could be picking up a bit, and even gaining consideration in places like Japan, which are actively pursuing alternative forms of energy.
A new study out this week in the prestigious journal Science suggests that along with wastewater treatment plants that pump water underground, geothermal plants increase the frequency of earthquakes in the surrounding area. One of the studied power plants was in Southern California, near the Salton Sea. The plant extracts hot water from underground and converts it into steam and thus electricity. The paper shows that water extraction from the ground correlates with earthquake activity, giving a precise frequency rate of half a billion gallons of extracted water per month leading to an earthquake every 11 days.
Now to be fair these are very small earthquakes, but given the location of the studied geothermal plant near the San Andreas Fault, further geothermal plant construction will undoubtedly get another layer of scrutiny, particularly in earthquake prone locations like Japan.