Remedy for global warming
2008-11-07 18:04
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 one 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 November 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 four billion to five 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.