Geothermal energy: too dangerous?

Earlier this month, a $60 million project to extract renewable energy from the hot bedrock deep beneath Basel, Switzerland, was shut down after a government study determined that earthquakes generated by the project were likely to do millions of dollars in damage each year, the New York Times reported. The project was first suspended in 2006 after it generated earthquakes that caused about $9 million in damage to other structures.

The day after this report, the Times covered the abandonment of a similar project by AltaRock Energy, outside San Francisco, which was attempting to extract vast amounts of renewable energy from deep, hot bedrock. AltaRock had a $6 million grant from the Department of Energy, part of the $440 million the department has put into its geothermal program this year alone, according to the article.

These are devastating turns for those who believe the use of geothermal energy could cut the world's use of emissions-causing fossil fuels. And there is no question that the risks deserve a second look. But when it comes to humans causing earthquakes, geothermal drilling--which involves drilling into hot rock at depths of several kilometers and pumping water into the depths--is just one culprit. (Wired has a good breakdown of all the ways we can cause earthquakes, from coal mining to oil drilling.)

I recently talked to Dr. Christian Klose, who just became a senior research scientist at Think GeoHazards in New York, about human-triggered earthquakes. Previously, Klose worked at Columbia University’s School of Engineering and Applied Science and the Lamont-Doherty Earth Observatory.

What do you do at Think GeoHazards?

My research focuses on understanding natural hazards and their impacts on human security. We do research proposals and studies on the climate and help our clients manage their risks.

You study earthquakes caused by human actions. So are these still considered “natural” disasters?

It’s an event caused by the natural system, but triggered by human activities. I describe it as geohazards—hazards that can come from the earth. They can be triggered or induced by humans or by nature. Ninety-five percent of all earthquakes are of natural origin and occur in active regions, such as California, Japan, Turkey or the Pacific. Five percent occur in stable regions, and of that percent, you have a fraction that are human-triggered.

How should humans change our behavior to prevent these earthquakes?

I’m not going to come out and say you need to stop that [activity]. I’m saying you need to make an appropriate risk assessment. The goal is for people to understand the geology and understand the coupling of interactions between the human system and natural system. If we assume we can trigger an earthquake, there will be a risk. So to reduce the risk, you reduce the hazards. You decide not to build a dam, or you build a smaller dam, or we can decrease vulnerabilities. Don’t build close to where we can expect earthquakes.

Most of the time we have ignored those issues. When you look at the areas exposed to mining earthquakes—there’s an earthquake, and then afterward we will put some money into getting rid of the damages, but there’s no preemptive measure to make sure it doesn’t happen. Ignoring a problem until it happens is not the best way. I’ve shown this in the Newcastle, Australia earthquake [1989, Richter 5.6, 13 people killed, 160 injured]. This has been a coal-mining region for 200 years. If you do a cost-benefit analysis and look at the money you really make and compare this with the monetary amount of the damages, you end up at $3 billion in damages. These aren’t just little earthquakes and some damages. It can be detrimental.

What’s the difference between an induced earthquake and a triggered earthquake?

Induced earthquakes happen only when humans do engineering, such as when we excavate a mine. They would never happen under natural conditions. If you inject fluid into the rock for hydrocarbon production, you induce tiny earthquakes, and this is expected, for instance, when reservoirs are built. The only question is how big the earthquakes will be. But 40 years ago no one excepted the idea of this.

Triggered earthquakes are natural earthquakes that would have happened under natural conditions, but the question is, when do these natural conditions trigger earthquakes, and how much stress does it take to trigger them? You have to understand the geology to understand where the fault zones are and when was the last earthquake. Then you can come up with physical models that can tell you, for example, if you remove a huge amount of mass from mining, how it affects the earth’s crust. You will never be able to predict an earthquake—the uncertainties are too huge. But you can have a forecast.

This post was originally published on Smartplanet.com