, January 6, 2010 (ENS) - Buried volcanic rocks along the coasts of New York, New Jersey and New England might be ideal reservoirs to store carbon dioxide emitted by coal-fired power plants and factories, according to scientists from Columbia University's Lamont-Doherty Earth Observatory.
Their study this week in the journal "Proceedings of the National Academy of Sciences" outlines formations of basalt rock on land as well as offshore that the scientists have identified as the best potential sites.
Some basalt on land is already well known and highly visible. The vertical cliffs of the New Jersey Palisades, along the west bank of the Hudson River across from Manhattan, are pure basalt.
The New Jersey Palisades, overlooking the Hudson River, are pure basalt. (Photo by Cranky Scorpion)
This formation, created some 200 million years ago, extends into the hills of central New Jersey, and similar basalt masses are found in central Connecticut.
Underground burial, or sequestration, of the greenhouse gas carbon dioxide is being studied across the country. For instance, a proposed coal-fired plant in Linden, New Jersey would pump liquefied carbon dioxide, CO2, offshore into sedimentary sandstone.
The Lamont scientists say this idea is controversial because the CO2 might leak out into the environment. By contrast, their new study focuses on basalt, an igneous rock, which they say offers significant advantages.
Previous research by Lamont scientists and others shows that carbon dioxide injected into basalt undergoes natural chemical reactions that will eventually turn it into a solid mineral resembling limestone. If the process were made to work on a large scale, this would help eliminate the danger of leaks.
"The basalt itself is very reactive, and in the end, you make limestone," said study coauthor Dennis Kent of Rutgers University. "It's the ultimate repository."
Led by geophysicist David Goldberg, the study's authors used existing research to outline more possible basalt underwater, including four areas of more than 1,000 square kilometers each, off northern New Jersey, Long Island and Massachusetts.
A smaller patch appears to lie more or less under the beach of New Jersey's Sandy Hook peninsula, opposite New York City harbor and not far from the proposed plant at Linden.
The undersea formations are inferred from seismic and gravity measurements.
"We would need to drill them to see where we're at," said Goldberg. "But we could potentially do deep burial here. The coast makes sense. That's where people are. That's where power plants are needed. And by going offshore, you can reduce risks."
Goldberg and his colleagues previously identified similar formations off the Pacific Northwest coast.
Goldberg said the undersea formations are potentially most useful, because they are deeper. He says that CO2 pressurized into a liquid would have to be placed at least 2,500 feet below the surface for natural pressure to keep it from reverting to a gas that might make its way back to the surface.
The basalts on land are relatively shallow, but those at sea are covered not only by water, but hundreds or thousands of feet of sediment, and they appear to extend far below the seabed.
In addition to providing pressure, sediments on top would form impermeable caps, said Goldberg who believes the basalts to contain porous, rubbly layers with plenty of spaces where CO2 could fit, simply by displacing seawater.
Theoretically, after morphing into a solid, the CO2 would fill those voids. On land, the same reaction might take place, but it is possible that drilling and injection could disturb aquifers or otherwise disturb neighbors on the heavily populated surface.
The scientists estimate that just the small Sandy Hook basin may contain about seven cubic kilometers of the rock, with enough pore space to hold close to a billion tons of CO2 - the equivalent of the emissions from four billion-watt coal-fired plants over 40 years.
The largest basalt mass appears to extend offshore of Georgia and South Carolina, as well as inland. This coast also is populous, and would make a good target, said Goldberg.
"The next step would be to get some exploratory surveying and drilling going," he said. The paper suggests a half-dozen spots around New York including the Sandy Hook area, and three off South Carolina, to start with.
The study was also coauthored by geologist and paleontologist Paul Olsen, who has been involved in drilling basalt formations in New Jersey. Preliminary drilling also has been done at Lamont-Doherty Earth Observatory itself, which sits atop the basalt cliffs on the Hudson River's west bank.
Copyright Environment News Service (ENS) 2010. All rights reserved.
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