Carbon capture and storage

Researchers Evaluate Using Extremophiles To Help Trap Carbon Dioxide Deep Underground

Researchers form South Dakota Mines are studying microbial acceleration of carbon mineralization with extremophiles found at the Sanford Underground Research Facility.

Core samples, drilled from the drifts of the Sanford Underground Research Facility, contain colonies of microscopic life.
Credit: Adam Gomez.

When first learning about the Sanford Underground Research Facility (SURF), it can help to imagine it as a vast, inverted apartment complex. Experiments move into the large, underground caverns. And SURF provides the usual amenities: electricity, running water, elevator maintenance, radon mitigation, liquid nitrogen deliveries, and, of course, shielding from cosmic rays.

But, amidst the facility’s 370 miles of tunnels, shafts, and drifts, there is one group of tenants who pay no rent at all. At SURF, billions of microorganisms—known to biologists as “extremophiles” for their ability to carve out a living far from sunlight and with limited oxygen—live deep underground.

This summer, a research group from South Dakota Mines (Mines) retrieved a core sample—a smooth cylinder of gray rock—from 4,100 ft. below of the surface of SURF. Under a microscope, it wriggled with SURF’s hardiest inhabitants.

From this sample, the research group hopes to find a microbe with a distinct set of characteristics that could help store excess greenhouse gases deep underground.

Locking Away Carbon Dioxide
While extremophiles have slowly evolved to withstand their adverse habitat, scientists are on a mission to keep the Earth’s atmosphere as hospitable as possible. And so a global effort is underway to store carbon dioxide (CO2) emissions in deep underground reservoirs. One promising method to keep it locked in place is called “carbon mineralization.”

“Carbon dioxide gas is captured from the atmosphere, then pumped in liquid form deep into underground rock formations,” said Bret Lingwall, a geotechnical, biogeotechnical and earthquake engineering researcher, who leads the Mines research group. Deep underground, a chemical reaction transforms the COinto a stable, solid carbonate mineral—effectively trapping it for millennia.

But this process has a severe limitation: speed.

The crippling pace of the method’s chemical reaction is measured not in weeks or months but in years. Currently, the largest carbon mineralization project on Earth can sequester 10,000 tons of CO2 each year—barely a drop in the bucket when climatologists measure carbon emissions by the gigaton (one billion tons).

Meanwhile, Earth is in a bit of a rush.

For carbon mineralization to have an effect, the process desperately needs some added speed.

“What we are trying to do is to accelerate that timescale from a couple of years to a couple of weeks,” Lingwall said. “How we propose to do that is through microbial acceleration.”

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