Energy from down under

A few miles below the Earth’s surface, there is a huge, untapped power source which could provide a virtually limitless source of energy – geothermal energy.

Scientists from MIT are investigating the use of geothermal energy as a method of generating electricity with no greenhouse gas emissions that could meet the world’s energy needs, in theory, for many centuries.

Herbert Einstein, professor of civil and environmental engineering, has received a grant from the US Department of Energy to continue studying fracturing in rocks. He is developing computer programs that can help evaluate geothermal sites, accessing both the potential power output and risks.

“What these decision tools do is allow you to consider the uncertainties, of which there are a lot,” said Einstein. His work is crucial in creating new Engineered Geothermal Systems (EGS) sites.

Water heated by hot bedrock just beneath the surface of the Earth naturally rises and it can be tapped to drive a turbine and generate electricity. Where naturally heated water is unavailable, EGS can be used recreate this process. Water at high pressure is injected into a deep well and creates a network of fractures in the deep rock. The water is heated as it passes through the cracks. It reaches the surface again at a second well, where it can be tapped.

Einstein’s program will assess proposed tunnel sites and landslide risks, taking into account of the rock encountered and how it will fracture under pressure.

 “Engineered Geothermal Systems can be an enormous contributor to the world’s renewable energy portfolio,” said Curt Robinson, executive director of the Geothermal Resources Centre in California. He says EGS could play a significant role in meeting energy needs if there are better ways of finding potential sites.

 “You could replace everything that’s around,” Einstein says, “That’s certainly very promising.”