Scientists Say A Rock Can Soak Up Carbon Dioxide
US: November 10, 2008
NEW YORK - A rock found mostly in Oman can be harnessed to soak up the main
greenhouse gas carbon dioxide at a rate that could help slow global warming,
scientists say.
When carbon dioxide comes in contact with the rock, peridotite, the gas is
converted into solid minerals such as calcite.
Geologist Peter Kelemen and geochemist Juerg Matter said the naturally
occurring process can be supercharged 1 million times to grow underground
minerals that can permanently store 2 billion or more of the 30 billion tons
of carbon dioxide emitted by human activity every year.
Their study will appear in the Nov. 11 edition of the Proceedings of the
Natural Academy of Sciences.
Peridotite is the most common rock found in the Earth's mantle, or the layer
directly below the crust. It also appears on the surface, particularly in
Oman, which is conveniently close to a region that produces substantial
amounts of carbon dioxide in the production of fossil fuels.
"To be near all that oil and gas infrastructure is not a bad thing," Matter
said in an interview.
They also calculated the costs of mining the rock and bringing it directly
to greenhouse gas emitting power plants, but determined it was too
expensive.
The scientists, who are both at Columbia University's Lamont-Doherty Earth
Observatory in New York, say they could kick-start peridotite's carbon
storage process by boring down and injecting it with heated water containing
pressurized carbon dioxide. They have a preliminary patent filing for the
technique.
They say 4 billion to 5 billion tons a year of the gas could be stored near
Oman by using peridotite in parallel with another emerging technique
developed by Columbia's Klaus Lackner that uses synthetic "trees" which suck
carbon dioxide out of the air.
More research needs to be done before either technology could be used on a
commercial scale.
Peridotite also occurs in the Pacific islands of Papua New Guinea and
Caledonia, and along the coast of the Adriatic Sea and in smaller amounts in
California.
Big greenhouse gas emitters like the United States, China and India, where
abundant surface supplies of the rock are not found, would have to come up
with other ways of storing or cutting emissions.
Rock storage would be safer and cheaper than other schemes, Matter said.
Many companies are hoping to cut their greenhouse gas emissions by siphoning
off large amounts of carbon dioxide from coal-fired power plants and storing
it underground.
That method could require thousands of miles of pipelines and nobody is sure
whether the potentially dangerous gas would leak back out into the
atmosphere in the future.
(Reporting by Timothy Gardner, editing by Eric Beech)
Story by Timothy Gardner
REUTERS NEWS SERVICE
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