AltaRock Energy Site in California
After hitting a fault in Basel, Switerland and triggering a 3.4 earthquake that shook the city, Markus Haring shut down his project. In August German geothermal company Geox caused a few quakes and is investigating. And, in California, AltaRock Energy just suspended it’s exploration of an area north of San Francisco.
Is Geothermal energy too dangerous? Or do the small micro-seismic events resulting from drilling deep and fracturing hard rock relieve built-up pressure and prevent bigger quakes?
Science is still trying to decide. But the search for renewable power sources has led many to the core of the planet, where a seemingly unending source of heat can be found and captured.
This is a very poorly written article. It is small wonder that confidence in the press is at an all time low, given the rampant shoddy fact checking out there of the sort rife in this piece.
The first major problem is that the headline attributes problems to “drilling.” No, no, no, no. The concern is about what happens **after** the drilling is complete. The act of drilling is not the issue, it is what happens after the drilling is done, when water is pumped under pressure down the well.
Further down the article, where mention is made of “fracturing rock,” the author again implies (erroneously) that the drilling is fracturing rock.
And no responsible seismologist believes that smaller quakes “relieve built-up pressure and prevent bigger quakes.”
Another gaffe by the author of this article is that he lumps all the types of geothermal into a single bucket. There are two basic kinds of geothermal-based electricity generation. The familiar kind, in operation for more than 40 years, uses near-surface hot water resources (sometime, but rarely, it is steam) that flow with enough volume to allow the economic generation of electricity. These are called hydrothermal resources.
The geothermal technology at issue in this careless article is called Enhanced (sometimes Engineered) Geothermal Systems (EGS). It involves enhancing, and perhaps creating, water-flow paths in hot rock. The heat is NOT created, as this article says — it is already there. The aim of EGS is to access that heat and “mine” it by flowing water through the paths and bringing it up to the surface when hot enough to the run electricity-generating turbines.
All EGS projects are **expected** to generate some level of earthquakes. It is intrinsic to the process of prying open the water pathways. Some of this is also desired, because it allows remote monitoring the extent of the fracture enhancment by mapping quake locations. The trick is to keep the quake sizes small, and figuring out how to do this is part of the R&D of ongoing EGS efforts.
Quakes of various sizes also accompany hydrothermal operations from “re-injection” of the geothermal water back into the ground once most of the heat is “mined”, which is done to keep the geothermal reservoir healthy. Quakes also accompany some kinds of widespread oil and gas recovery.
The AltaRock project was suspended because of near-surface drilling problems that have nothing to do with EGS technology. It is dishonest of the author to not mention this.
The German EGS project is still generating electricity while the government investigates the earthquakes. It is dishonest of the author to also not mention this.
The Swiss government has paused the Basel EGS project while it considers if it can go forward safely. Nobody was hurt by the quakes that occured there. The city of Basel and its surroundings includes more than 600,000 people. The quake that scared everyone resulted in only about 2,700 claims that paid out an average of almost $3,100 each, about the amount spent when a tree falls on a roof to fix the roof and remove the tree (see the Wikipedia article on EGS for these details).. The damage was regrettable, but hardly epic or tragic.
Please don’t ever write on this topic again without letting someone knowledgable review it.