14 DAY TRIAL // Injecting carbon dioxide deep underground as a way of fighting global warming, could blow up in our faces, as it could leak into drinking water aquifers near the surface, and rise the contaminants levels by ten or more in some areas, found a new study carried out by Duke University scientists.
They actually carried out a year-long analysis of core samples taken from four drinking water aquifers, and concluded that “the potential for contamination is real, but there are ways to avoid or reduce the risk,” said Robert B. Jackson, Nicholas Professor of Global Environmental Change and professor of biology at Duke.
He added that “geologic criteria that we identified in the study can help identify locations around the country that should be monitored or avoided.
“By no means would all sites be susceptible to problems of water quality.”
Jackson along with his postdoctoral fellow Mark G. Little gathered core samples from four freshwater aquifers around the United States, and incubated them for a year, in their lab at Duke's, with carbon dioxide bubbling through them.
When the year ended, the samples were analyzed and the researchers concluded that “there are a number of potential sites where CO2 leaks drive contaminants up tenfold or more, in some cases to levels above the maximum contaminant loads set by the EPA for potable water.”
However there are three factors that could influence the risk of drinking water contamination from underground carbon leaks: solid-phase metal mobility, carbonate buffering capacity and electron exchanges in the overlying freshwater aquifer.
The team also found four markets that can be used to test for potential CO2 leaks; Jackson explains that “along with changes in carbonate concentration and acidity of the water, concentrations of manganese, iron and calcium could all be used as geochemical markers of a leak, as their concentration increase within two weeks of exposure to CO2.”
The CO2 storage process, deep below the surface of the Earth, is called geosequestration, and it's part of the new carbon capture and storage (CCS) technologies, on which governments all around the world are working, to reduce global warming caused by greenhouse gas emissions.
These technologies are still evolving but their goal is to capture and compress CO2 emissions at their source, and carry the carbon dioxide to locations where it can be buried for long-term storage.
In the US, there are at least seven regional CCS projects that the Department of Energy started planning.
Jackson, who directs Duke's Center on Global Change, said that “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.
“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.”
This study appears in the online edition of the journal Environmental Science & Technology.