EAST HAMPTON, Conn.—Swinging a small sledgehammer, state geologist Teresa Gagnon pounds at a boulder, trying to break off just the right stone to prove geothermal heat can be generated from deep below Connecticut.
Shards of rock fly in all directions as Gagnon seeks a stone that's not too small and not too weathered. She hones in on boulders jutting from the ground, ignoring loose boulders that could have come from anywhere.
Gagnon was combing a Connecticut state park on a recent morning as part of an effort to map rock formations with geothermal potential here and in Massachusetts. As geothermal energy receives more attention as an alternative to oil and coal, researchers say knowing the location of rocks with natural radioactivity will help the two states to capitalize on lower exploration costs.
Gagnon said many of the rock formations are left over from eroded mountains, some of them potentially 400 million to 500 million years old.
"I need a good-sized chunk if I can find one," she said.
After bagging the rocks, Gagnon brings them to the University of Massachusetts at Amherst, where researchers crush them into powder that can reveal a presence of uranium, thorium and other radioactive elements.
Margaret Thomas, Connecticut's state geologist, said researchers can then determine which rocks have the potential to generate heat deep in the earth and would be considered targets for geothermal drilling. Geothermal heat is generated by the natural radioactive decay in certain rocks and combines with the natural heat from the earth's interior.
The three-year Massachusetts-Connecticut project, currently in its first year, is funded by a $441,062 grant from the U.S. Energy Department through the American Association of State Geologists.
Geothermal energy is often harnessed in the western United States by tapping hot springs, but researchers in New England are focusing on heat-producing rocks. With current technology, a rock must contain enough radioactive thorium, uranium and potassium to heat water to higher than 300 degrees to have potential geothermal applications. One technology would pump cold water into fractured rocks and recover the hot water and steam.
As oil prices and environmental concerns continue to climb, universities, government and industry are looking aggressively into alternative sources of energy.
Investment in geothermal energy has lagged behind solar and wind power, but researchers say there are potential commercial applications.
Don O'Shei, chief executive officer at AltaRock Energy Inc., a Sausalito, Calif., company that develops projects to exploit underground reservoirs for geothermal energy, said tapping rocks for energy will become more common. Drilling costs are bound to fall as efficiency improves, he said.
"We're in effect creating a new industry. It is going to happen," he said.
Mike Rhodes, professor of volcanology at UMass, said many companies are exploiting geothermal energy in volcanic regions such as Iceland, Indonesia and the United States, but none yet are producing commercial electricity by using fractured rock and its radioactivity.
It is uncertain how much energy potential might lie in New England's rockbeds.
Preliminary work by the researchers so far has not turned up rocks with enough radioactive elements to generate heat, according to Massachusetts state geologist Steve Mabee. But regardless of the result, he said the work will put the states in a strong position as new technologies are expected to bring down exploration and other costs.
"When the economics improve, when companies come to us and ask where should we drill, we'll have the answers," Mabee said.
