11 Nov 2008 05:11:30
Rock turns CO2 to stone
A rock which reacts quickly to carbon dioxide to form a solid carbonate such as limestone or marble, could be used to trap up to four billion tonnes of CO2 emissions, according to scientists.
In a report in the Proceedings of the Natural Academy of Sciences, the researchers claim that peridotite, which comprises most of the rock in the earth's mantle, has a previously undiscovered high rate of reaction underground.
Earlier attempts to use the stone to reduce emissions, such as by grinding it up and combining it with smokestack gasses, have been considered too expensive.
However, by studying exposed and underground peridotite in Oman, Peter Kelemen and Juerg Matter of Columbia University's Lamont-Doherty Earth Observatory have revealed that the rock still reacts to CO2 underground, opening the possibility for safe CO2 sequestration.
Emissions could be pumped underground into areas where peridotite is in abundance and the rock would then turn the CO2 into solids.
"This method would afford a low-cost, safe and permanent method to capture and store atmospheric CO2," said Mr Kelemen.
Previous suggestions for sequestering CO2 involved liquefying it and pumping it into massive underground caves a prospect which worried campaigners because it could leak out, polluting water and marine ecosystems in the process.
Meanwhile, BP has withdrawn from the government's carbon capture and storage competition to build a demonstration plant in the UK to test the technology.
It leaves E.On, Peel Power and Scottish Power as the remaining three bidders.http://www.physorg.com/news145126515.html