Omani rock could absorb vast amounts of carbon dioxide

November 6th, 2008 - 12:22 pm ICT by IANS  

Washington, Nov 6 (IANS) A rock found in Oman could soak up huge quantities of globe-warming carbon dioxide, cheaply.The studies show that the rock, known as peridotite, reacts naturally at high rates with carbon dioxide (CO2) to form solid minerals - and that the process could be speeded with simple drilling and injection methods.

Scientists said that the process could be speeded 100,000 times or more simply by boring down and injecting heated water containing pressurised CO2.

“This method would afford a low-cost, safe and permanent method to capture and store atmospheric CO2,” said co-author Peter Kelemen, a Columbia University geologist. Kelemen and geochemist Juerg Matter, also of Columbia, made the discovery during field work in the Omani desert.

Once jump-started in this way, the reaction would naturally generate heat - and that heat would in turn hasten the reaction, fracturing large volumes of rock, exposing it to reaction with still more CO2-rich solution, said a Columbia University release.

Scientists asserted that Oman alone could probably absorb some four billion tonnes of atmospheric carbon a year - a substantial part of the 30 billion sent into the atmosphere by humans, mainly through burning of fuels.

Peridotite comprises most or all of the rock in the mantle, which undergirds earth’s crust. It starts some 20 km or more down, but occasionally pieces are exhumed when tectonic plates collide and push the mantle rock to the surface, as in Oman.

Researchers said that the discovery of previously unknown high rates of reaction underground means CO2 could be sent there artificially, at far less cost.

“It’s fortunate that we have these kinds of rocks in the Gulf region,” said Matter. Much of the world’s oil and gas is produced there, and Oman is constructing new gas-fired electric plants that could become large sources of CO2 which could be pumped down.

The study will appear in this week’s edition of the Proceedings of the National Academy of Sciences.

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