Carbon capture study 'significantly increases number of suitable storage sites'

The slow leak of gas from an underground reservoir in Arizona adds further evidence that a potentially vital technology to combat climate change is reliable, researchers have said.

A team from the universities of Edinburgh, Glasgow, Freiburg and Heidelberg studied the naturally occurring carbon dioxide repository to investigate the potential of carbon capture and storage (CCS), a technology using various methods to collect manmade carbon dioxide emissions and prevent it from dispersing into the atmosphere.

Many believe that CCS – similar to CCUS, in which the captured gas is used for purposes such as concrete production or directed back into blast furnaces – will be a vital element of international efforts to reduce carbon emissions. The vast majority of countries are committed to limiting average global temperature rises to 2ºC over pre-industrial levels, under the 2015 UN Paris Agreement.

Despite backing from many, including IMechE head of engineering Dr Jen Baxter, development of the technology has been hobbled by inconsistent investment. Researchers behind the new study said there are also public concerns over proposed long-term storage of CO₂  in depleted gas and oil fields.

The researchers studied the repository in Arizona, where some gas migrates through geological faults to the surface. Researchers used chemical analysis to calculate the amount of gas that had escaped the underground store over almost half a million years, and found that “a very small amount of carbon dioxide escaped the site each year, well within the safe levels needed for effective storage”.

The work, which was supported by the European Union and Natural Environment Research Council, could lead to an increase in the number of sites deemed suitable for gas storage.

“This shows that even sites with geological faults are robust, effective stores for CO₂,” said joint study leader Dr Stuart Gilfillan, from the University of Edinburgh’s school of geosciences. “This find significantly increases the number of sites around the world that may be suited to storage of this harmful greenhouse gas.”

“The safety of carbon dioxide storage is crucial for successful widespread implementation of much-needed carbon capture and storage technology,” said Dr Johannes Miocic from the University of Freiburg, who also jointly led the study. “Our research shows that even imperfect sites can be secure stores for hundreds of thousands of years.”

The study was published in Scientific Reports.