New Research on Safety of Storing Carbon Underground Is Questioned

For more than a decade, carbon capture and storage technology has been heralded by fossil-fuel industries and many policymakers and scientists as an effective response to the threat of climate change.

But the commercialization of CCS—which captures heat-trapping CO2 from smokestacks and pumps it into reservoirs deep underground—still faces enormous financial, technological, political and environmental hurdles.

One question that critics want answered is what happens if mass quantities of CO2 leak out and collect in communities' air or water.

Conservationists and health organizations warn that a large release of CO2 could contaminate drinking water supplies, cause asphyxiation or alter pH levels in the blood of residents, which can lead to brain malfunction or death. The industry and other supporters say that natural sequestration events and 20 years of carbon injection by oil companies suggest that CO2 can be trapped underground safely and permanently.

A new study from scientists at the University of Edinburgh in Scotland, which was partially funded by industry, claims to clear up at least some of that uncertainty.

The researchers looked at death rates near natural CO2 seeps in Italy over a 50-year period. They found that people living near the storage sites have a one-in-a-32 million annual chance of dying from contamination. The researchers note in the paper that there is a greater chance of winning the lottery than being killed by natural CO2 releases.

"We were really quite surprised to find it had such a low risk," said Jen Roberts, a geologist at the University of Edinburgh and lead author of the study.

The peer-reviewed research, which will be published in this week's Proceedings of the National Academy of Sciences, was funded by the Scottish Carbon Capture & Storage consortium, a collection of researchers and companies that study the technology and implementation of CCS, and the College of Science and Engineering at the University of Edinburgh.

It is one of the first papers to quantify the health risks of CCS and concludes that "the current public concern regarding death by CO2 leakage from storage sites appears overamplified."

Not everyone agrees.

The paper considered death as the only measure of health risk, said Michael McCally, a physician and senior scientist with the nonprofit Physicians for Social Responsibility, who has written about the health risks of CCS. "If the scientists had looked at things like brain damage from non-lethal asphyxiation [caused by overexposure to CO2], I think the risks would have been at least two to three times higher."

Roberts counters that nearly all health issues associated with CO2 poisoning—from the headaches to brain malfunction—are completely reversible once a person starts breathing air with regular, low levels of CO2 again. While the non-lethal records were too incomplete to incorporate, she said she doesn't think it was imperative to include them.

Another unaddressed concern, said McCally, is the potential for CO2 to seep out of the thousands of miles of pipeline that will have to transport the gas to injection sites. "You can't call CCS safe without looking at all the aspects of the technology."

The physician also questions Roberts and her colleagues' potential conflicts of interest.