How carbon stored underground could find its way back into the atmosphere

Generous federal tax credits are driving the surge of carbon capture and storage projects being proposed in the U.S. But there’s a chance that carbon emissions could seep back up into the atmosphere after they are injected underground, reports Louisiana Illuminator.

How? Through any of the thousands of abandoned oil and gas wells nationwide. Louisiana alone has 4,500 abandoned wells and more than 21,000 inactive wells, though there are ongoing efforts to close them up. Nationwide, there could be as many as 3 million such wells.

Companies—including Occidental Petroleum, Denbury and Blue Sky—are rushing to purchase the underground spaces, generally deep underground and sometimes in the spaces that once held oil and gas. So far, more than two dozen storage sites in Louisiana are publicly known, including the most controversial under Lake Maurepas.

“Those wells are like straws in the marsh,” says Alex Kolker, Louisiana coastal geologist at the Louisiana Universities Marine Consortium. “It’s a conduit for carbon dioxide to reach the surface.”

Capturing climate-warming carbon dioxide from energy production, industrial processes or directly from the air is considered an important part of plans to keep global warming in check. But critics worry about the implications of pumping millions of tons of the captured carbon underground. Worries include the potential for earthquakes from forcing the carbon underground, contamination of groundwater and the eventual leakage of that carbon back into the atmosphere.

The leakage problem has been studied extensively, including by the industry itself. Sue Hovorka, a research scientist at the University of Texas in Austin and who is considered a pioneer of the geologic sequestration of carbon dioxide, says the risk is manageable with proper oversight and regulation.

Government regulations for geologic sequestration of carbon, called Class VI permits, require careful analysis of all potential pathways for the carbon to escape, as well as regular monitoring and testing. Those regulations require identifying and mitigating all abandoned or inactive wells on that property. So far, however, only two such wells have been constructed in the U.S.

Louisiana has applied for permission to regulate such wells within the state, and the Environmental Protection Agency indicated earlier this year that it would hand over that authority. A comment period on that decision ended Sept. 15.

The handoff to states adds another layer of concern for some critics of carbon capture. Read the full story from Louisiana Illuminator.