Burying Greenhouse Gas a Viable Idea, Study Finds

(CN) — Storing massive amounts of carbon dioxide underground may be a more effective tool for limiting global climate change than previously thought, a study released Thursday says.

The study, published in the journal Nature Communications, shows the viability of plans to capture and store carbon in order to curb greenhouse gas emissions.

Researchers studied carbon dioxide trapped naturally underground for about 100,000 years and found it has not corroded the cap rocks — a layer of hard rock overlying and often covering a deposit of gas, oil or coal — which suggests that storing greenhouse gases underground could be a viable option for stemming climate change.

The carbon dioxide would have to remain buried for at least 10,000 years to avoid contributing to climate change.

Carbon capture and storage is a potential solution for reducing carbon emissions from gas-fired power stations and coal, though the strategy also poses potential danger to the planet and creates regulatory and financial challenges.

"A major obstacle to the implementation of carbon capture and storage is the uncertainty over the long-term fate of the carbon dioxide, which impacts regulation, insurance, and who assumes the responsibility for maintaining carbon dioxide storage sites," study co-author Mike Bickle said. "Our study demonstrates that geological carbon storage can be safe and predictable over many hundreds of thousands of years."

Led by researchers from the University of Cambridge, the team reviewed a natural reservoir in Utah where carbon dioxide released from deeper formations has been trapped for around 100,000 years. The researchers drilled into the footwall — the block of rock on the underside of an inclined fault — that cut across multiple reservoirs of carbon dioxide-charged brine and analyzed the corrosion of the cap rock.

While carbon dioxide is injected as a dense fluid, it is still less dense than the brines filling the pores in the reservoir sandstones, and will rise until trapped by the seemingly leak-proof cap rocks.

"Although natural carbon dioxide reservoirs demonstrate that carbon dioxide may be stored safely for millions of years, uncertainty remains in predicting how cap rocks will react with carbon dioxide-bearing brines (a solution of salt in water)," the study says.

The findings are good news for academics and politicians who have championed carbon capture and storage, despite ongoing hurdles that have forced several pilot programs to be reduced, delayed or terminated.

In May, Republicans in Congress criticized the Department of Energy and Environmental Protection Agency over their perceived bias against fossil fuels.

"Through the national labs, the department should take the lead on fossil energy technology innovation, conducting the foundational research that allows the private sector to commercialize groundbreaking technology," Rep. Randy Weber, a Republican from Texas, said.

Several economists and think tanks have pointed out the financial challenges associated with carbon capture and storage, noting that many facilities have to be built up to 25 percent larger to accommodate the process.

David Bailey and David Bookbinder published an article Thursday for the Niskanen Center — a blog dedicated to exploring the politics and policy of climate change from a libertarian perspective — which highlighted the various problems that must be resolved before significant progress is made with carbon capture and storage.

"The first barrier is simple: it costs a bundle (about 50 percent more) to build and to operate a fossil-fuel plant with carbon capture and storage compared to a plant without the process," the article states. "As things stand now, the only incentive to build a plant with carbon capture and storage is the hope that there will be a market in the United States (or elsewhere) for this technology in the future."

The threat of the stored carbon dioxide eventually being released into the atmosphere is another significant concern.

Bickle explained that some issues observed in previous studies of carbon capture and storage — including how carbon dioxide-charged brines, which form as carbon dioxide dissolves, might progressively corrode cap rocks and weaken them enough to release the trapped carbon dioxide — were not witnessed in the team's research.

"These studies were either carried out in the laboratory over short timescales or based on theoretical models. Predicting the behavior of carbon dioxide stored underground is best achieved by studying natural carbon dioxide accumulations that have been retained for periods comparable to those needed for effective storage," Bickle said.

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