A Rock to Absorb Greenhouse Gases?

What’s the best way to get rid of carbon dioxide in the atmosphere? Two scientists from Columbia University say a rock may be the solution we’re looking for.

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In a paper published this week in the Proceedings of the National Academy of Sciences, geologist Peter Kelemen and geochemist Juerg Matter say that a common type of rock found beneath the earth’s surface can absorb significant amounts of CO₂ by converting it to a harmless mineral.

The rock, peridotite, is rarely seen by human eyes because it exists so far below the Earth’s crust. But in the sultanite of Oman, a particularly large supply of peridotite exists near enough to the surface that Matter and Kelemen say it can be used as a CO2 “sink,” allowing us to get rid of billions of tons of greenhouse gases every year.

The scientists say this location is quite appropriate for studying the efficacy of peridotite, as it is near a large fossil-fuel production area which creates quite a bit of carbon dioxide.

How would they accomplish this? The authors write “Peridotite carbonation can be accelerated via drilling, hydraulic fracture, input of purified CO₂ at elevated pressure, and, in particular, increased temperature at depth. After an initial heating step, CO₂ pumped at 25 or 30 °C can be heated by exothermic carbonation reactions that sustain high temperature and rapid reaction rates at depth with little expenditure of energy. In situ carbonation of peridotite could consume >1 billion tons of CO₂ per year in Oman alone, affording a low-cost, safe, and permanent method to capture and store atmospheric CO₂.”

Would it work? Who knows. But it sounds like a solution worth exploring!