Apparently, artificial ‘enhanced’ geothermal sites may cause earthquakes. The concept (mentioned here before) is to drill shafts down into hot rock formations, pump in cold water, and generate steam to drive turbines. It would considerably increase the number of regions where geothermal power could be used.
According to Swiss government seismologists and officials on the Basel project, an artificial geothermal project caused an earthquake in Basel in 2006 and was subsequently shut down. Even after the shutdown, thousands of smaller earthquakes occurred in the following years. Now, there are concerns about a project that AltaRock Energy wants to undertake in California. Google’s philanthropic arm is investing $6.25 million in the project. The proposed site already experiences as many as a thousand small earthquakes per year. This video has some further details.
Obviously, the earthquake risk needs to be assessed and managed. It may be that not as many sites are suitable for enhanced geothermal as previously assumed. Perhaps such projects will only prove viable in sparsely populated regions. In any case, it is an unfortunate blow to an otherwise promising looking type of renewable generation.
{ 2 comments… read them below or add one }
Big dams also cause earthquakes.
So can extracting oil and mining for coal.
There is a good chance CCS will cause some earthquakes, too.
http://issues.ni4d.us/index.php?title=Geothermal_Power_Responsible_Versus_Irresponsible_Technologies
There are several different ways to go about obtaining geothermal energy or drilling Geothermal wells. The only means which I personally advocate is exclusive to other technologies and is in some senses probably somewhat more expensive over the short term. However, the alternatives will prove to be more expensive over the long term, and to have assorted negative consequences. The only good way to do geothermal power is to drill a conventional well using conventional standard drilling technologies, and then to build closed circuit double loop systems. What this means is that firstly, an actual linear well is drilled straight down into the earth, secondly, that the water which is heated to power the system never leaves the piping which contains it, and thirdly, that water is circulated down on one circuit or loop and rises as steam on a second circuit or loop.
The Alternative being now explored is to use water as an explosive, and to drill non linear wells by pumping water into rock. This creates many small fractures or fissures in the rock, rather than a straight down conventional well. It also can cause earthquakes,is prone to the problem of erosion, and is likely to create a geothermal system which cools very quickly, especially when compared to closed circuit double loop. Claims made about such systems that they are closed systems are obviously false, if the water leaves the tubes then there is obviously potential for that water to leave the geothermal system. Another issue to consider is that a closed circuit double loop system never loses water and never loses pressurization. The systems which they are now creating are highly entropic, and while they may for the time being demonstrate properties of a closed system, they are certainly not truly closed.