co2 rocks

CO2 stored in underground rocks could be safe from geological faults

Image credit: Johannes Miocic

Storing carbon dioxide (CO2) emissions in underground rocks would be feasible even if geological faults are present according to a new study.

University of Edinburgh researchers said that the possibility of the gas escaping from fault lines back into the atmosphere is minimal, which is promising for the future of carbon capture and storage (CCS).

CCS has been cited as a stopgap measure to limit the impact of climate change until renewables become the primary form of energy generation.

If widely adopted it could help meet targets set by the 2015 UN Paris Agreement, which seeks to limit climate warming to below 2°C compared with pre-industrial levels.

The researchers conducted tests on a naturally occurring CO2 reservoir and hope that the findings will address public concerns over the proposed long-term storage of carbon dioxide in depleted gas and oil fields.

The natural CO2 repository is located in Arizona, US, where 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.

They found that a very small amount of carbon dioxide escaped the site each year, well within the safe levels needed for effective storage.

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

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

Another study recently found that renewable energy could be stored in the form of compressed air trapped inside porous rocks off the coast of the UK in the North Sea. 

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