BURYING carbon dioxide deep underground is an attractive solution to climate change, but keeping the gas from bubbling to the surface may prove difficult. Injecting nanoparticles into underground reservoirs before they are filled with CO2 could make any leaks self-sealing.
When CO2 rises quickly through cracks in the bedrock, the highly pressurised gas behaves like a liquid and shears into droplets. Steven Bryant, an engineer at the University of Texas at Austin, says silica nanoparticles coated with polyethylene glycol would bind to the droplets, creating a viscous foam. This would plug leaks much like the inner coating on a self-sealing tyre does, he says.
In lab tests, he used n-octane, a liquid that behaves like supercritical CO2, to show that the foam forms and clogs cracks in rock. He presented the results at the US Department of Energy’s Energy Frontier Research Centers Forum in Washington DC on 26 May. His team now plan to conduct tests using supercritical CO2.
Donald DePaolo of the Lawrence Berkeley National Laboratory in California says the idea has promise but may be prohibitively expensive. “Having an option like this to seal leaks once they form may be very attractive,” he adds.
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