Monday, January 25th, 2010
While the question the title of this article poses might seem like something from out of a Bruce Willis sci-fi action movie, geothermal drilling triggering seismic activity is very much the stuff of reality.
At least according to engineers from around the world, who recently studied a seismic event which occurred in Landau in der Pfalz, Germany. Some experts attributed the minor, 2.7-magnitude earthquake to the “enhanced engineered geothermal system (EGS)” that is providing heat and energy to the city. But engineers working inside the facility claim that the accusations are false. In their humble opinion, the shaking of the ground beneath their boots was nothing more than the routine geological activity according to the rules of Mother Nature.
Geothermal technology is derived by tunneling deep into the Earth’s underground in order to tap into water that is naturally warmed by the earth’s own heat. The water is then pumped up to the surface where it is used as energy to drive turbines that then generate electricity. EGS drilling tech however, goes much deeper into Earth. The massive drills bore through the bedrock and soil to depths of up to 10 kilometers. The enhanced drilling technology seeks to fracture the deep embedded rock and then pull out the heated water, bringing it up to the surface.
The major benefit of the geothermal energy is that, unlike oil or natural gas, it runs clean and is a sustainable green energy source. But does drilling for the energy cause earthquakes?
According to the earthquake experts at the US Geological Survey, seismic events occur when the stress that builds up from underground fault lines is suddenly released. The resulting “shaking of the ground caused by an abrupt shift of rock along a fracture in the Earth,” is what is known as a fault. While deep geothermal drilling is intended to unlock the potentially limitless reserves of heat and heated water from the Earth’s depths, it is the fracturing of the rock that has some engineers concerned about upsetting the Earth’s seismic inclinations, especially if the drilling is occurring too close to a seismic zone.
In a recent article drafted for ENR.COM, a popular trade magazine for engineering professionals, engineers opposed to the proliferation of EGS drilling are claiming that “fracturing the deep rock can cause earthquakes if the fracturing is too close to an active seismic fault zone.”
But Jefferson Tester, an MIT chemical engineering professor, believes that concern over serious earthquakes due to engineered geothermal drilling are unfounded. He backs up his beliefs by pointing out that the oil and natural gas industries have been drilling and fracturing the deep rock for decades without yet triggering a serious seismic event. “Yet” being the key word here.
However, according to Renewable Energy World.Com, it’s these very same engineering professors and experts who have no choice but to admit that “small seismic events known as microearthquakes have been recorded and monitored in the immediate vicinity of some injection sites. These usually have Richter magnitudes of 2 or 3 and are ordinarily imperceptible to people unless they are quite close to the epicenter.” What’s more, it is said that these microearthquakes, although triggered by geothermal drilling, pose no real “significant hazard” to surrounding buildings and infrastructure, be they homes, roads, bridges, commercial high-rises or, as in the case of Landau in der Pfalz, Germany, power plants.
Optimistic professors like Tester who defend geothermal drilling in order to tap into the Earth’s radiant core, are combating the naysayers by publicly cautioning the world against “unbalanced reports”. It is his professional opinion that, despite the microearthquake that occurred in Germany and another in nearby Switzerland, the intensity of the tremors caused by drilling is not “alarming” enough to be considered a damage-causing earthquake.
But one overriding question looms large: how inevitable is it that a so-called microearthquake might one day chain-react into a major earthquake of devastating proportions? With EGS tech becoming more popular and more deep holes being drilled down into the subterranean depths and more bedrock fractured unnaturally, only time and Mother Earth know the answer.