One leading solution to the problem to the fossil fuel emissions generated by a coal-fired plant is injecting it into underground storage areas thousands of feet below the surface, a technology known as carbon capture and sequestration. The Energy Department announced this summer that it would finance 15 separate projects to develop iterations of this technology.But the technology may hold some unwelcome surprises if the carbon dioxide finds its way out and up to groundwater aquifers, a new study by Duke University researchers indicates. It could react with minerals there and increase levels of pollutants, perhaps so much that federal regulators would deem the water undrinkable, experiments suggest.
Two researchers took samples of dry sediments from groundwater aquifers that sit above likely sites for carbon storage in eastern Maryland, Virginia, northern Texas and Illinois and exposed them to a steady stream of carbon dioxide.
"The chemical composition of our groundwater experiments was significantly affected by the addition of CO2," wrote the authors, Mark G. Little of Duke's Center on Global Change and Robert B. Jackson, a biologist with the Nicholas School of the Environment. The hypothetical "groundwater" in the experiments became more acidic, which in turn had the effect of dissolving some of the minerals in the sediments.
In particular, the concentrations of iron, cadmium and zinc, among other minerals, increased by more than 1,000 percent after exposure to carbon dioxide.
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