Duke, NETL study CO2 storage impact: Leakage must be reckoned with

Duke University, in collaboration with the DOE, just completed a study on carbon storage and the impacts of CO₂ injection into different geologic formations. The findings were published in the Oct. 26, 2010 edition of Environmental Science & Technology.

The report, “Potential Impacts of Leakage from Deep CO₂ Geosequestration on Overlying Freshwater Aquifers,” also presented information that can be used for advanced detection of CO₂ in the case of a leak.

According to a National Energy Technology Lab press release:

The researchers incubated core samples from a variety of freshwater aquifers with CO₂ for more than 300 days, and found increased acidity and metals concentrations in water surrounding the samples. They concluded that “the relative severity of the impact of leaks on overlying drinking water aquifers should be considered in the selection of CO₂ sequestration sites.” This confirms earlier research conducted by NETL, several other DOE national laboratories, the U.S. Geological Survey, and others indicating that CCS sites must be carefully selected and monitored.

The Duke researchers also identified three elements-manganese, iron, and calcium-which they suggest should be monitored, along with pH, as geochemical markers of CO₂ leaks.

Carbon capture and storage uses several technologies to separate, compress, transport and store CO₂. The biggest obstacle that must be overcome is storage of CO₂ without contaminating ground water supplies.

According to a Duke press release, “The fear of drinking water contamination from CO₂ leaks is one of several sticking points about CCS and has contributed to local opposition to it,” says Robert Jackson, professor of biology at Duke and director of its Center on Global Change. “We examined the idea that if CO₂ leaked out slowly from deep formations, where might it negatively impact freshwater aquifers near the surface, and why.”

Researchers also conclude that contamination to drinking water supplies can be avoided by finding ideal sites with impervious caprock, using proper construction materials and maintaining proper operating conditions.

“Based on incubations of core samples from four drinking water aquifers, we found the potential for contamination is real, but there are ways to avoid or reduce the risk,” says Jackson.