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Hot rocks in earth's crust raise hope for clean energy, quake concerns

This energy research project in Basel, Switzerland, was put on hold after temblors generated by drilling shook the region. This energy research project in Basel, Switzerland, was put on hold after temblors generated by drilling shook the region. (Georgios Kefalas/Associated Press/File 2007)

BASEL, Switzerland -- When tremors started cracking walls and bathroom tiles in this Swiss city on the Rhine, engineers knew they had a problem.

"The glass vases on the shelf rattled, and there was a loud bang," Catherine Wueest, a teashop owner, recalled. "I thought a truck had crashed into the building."

But the 3.4 magnitude tremor on the evening of Dec. 8 was no ordinary act of nature: It had been accidentally triggered by engineers drilling deep into the earth's crust to tap its inner heat and thus break new ground -- literally -- in the world's search for new sources of energy.

Basel was devastated by an earthquake in 1365, and no tremor, man-made or other, is taken lightly. After slightly smaller tremors followed the December quake, Basel authorities told Geopower Basel to put its project on hold.

But the power company hasn't given up. It's in a race with a firm in Australia to be the first to generate power commercially by boiling water on rocks 3 miles underground.

On paper, the Basel project looks fairly straightforward: Drill down, shoot cold water into the shaft, and bring it up again superheated and capable of generating enough power through a steam turbine to meet the electricity needs of 10,000 households and heat 2,700 homes.

Scientists say geothermal energy -- clean, quiet, and virtually inexhaustible -- could fill the world's annual needs 250,000 times over with nearly no impact on the climate or the environment.

A study the Massachusetts Institute of Technology released this year said that if 40 percent of the heat under the United States could be tapped, it would meet the demand 56,000 times over. It said an investment of $800 million to $1 billion could produce more than 100 gigawatts of electricity by 2050, equaling the combined output of all 104 nuclear power plants in the United States.

"The resource base for geothermal is enormous," Professor Jefferson Tester, the study's lead author, said in an interview.

But there are other drawbacks besides earthquakes. A hot rock well 3 miles deep in the United States would cost $7 million to $8 million, according to the MIT study. The average cost of drilling an oil well in the United States in 2004 was $1.44 million, according to the US Energy Information Administration.

Also, rocks tapped by drilling lose their heat after a few decades, so new wells would have to be pursued elsewhere.

Bryan Mignone, an energy and climate-change specialist with the Brookings Institution in Washington, D.C., said alternative sources of energy face stiff price competition.

"Currently in the US, new technologies in the power sector are competing against coal, which is very cheap," he said.

Humans have used heat from the earth for thousands of years. The ancient Romans drew on hot springs for bathing and heating their homes. Geothermal energy is in use in 24 countries, including the United States.

But those sources, geysers and hot springs, are close to the surface. Hot dry rock technology, also called enhanced geothermal systems, drills to where the layers of granite are close to 400 degrees Fahrenheit. The equipment is similar to that used for oil, but needs to go much deeper and be wider to accommodate the water cycle.

Hot dry rock technology is meant to stay well away from the 99 percent of the earth's interior that is more than 1,000 degrees Fahrenheit.

Aeneas Wanner, a Swiss specialist, said that if you imagine the earth as an egg, "a bore hole would only scratch the shell of the egg a little bit."

The United States led the way in demonstrating the concept with the Los Alamos geothermal project at Fenton Hill, N.M. The project, begun in the 1970s, demonstrated that drilling 15,000 feet deep was possible and that energy could then be extracted.

But the project came to a halt in 2000 when it ran out of funds. Meanwhile, the MIT report said, problems encountered in testing have been solved or can be managed -- such as controlling how the water flows underground or limiting earthquakes and chemical interactions between water and rock.

Backers in the United States hope government funding will increase as oil and gas prices rise. But Steve Chalk, deputy assistant secretary for renewable energy, said the Department of Energy won't spend more money beyond the $2 million it has already allocated to hot rock technology.

Major energy companies, including Chevron Corp., Exxon Mobil Corp., and American Electric Power, said they are following the research but not investing in it.