Geological CO2 storage safer than previously thought

The research, published in Nature Communications, looked at a natural reservoir in Utah where CO2 released from deeper formations has been trapped for around 100,000 years. It examined how acidic carbonated water affected the ability of the cap rock to act as an effective trap over that extended time.

The team found that CO2 had very little corrosive impact on the minerals, limited to just a 7cm layer over the period. This is substantially less than the amount predicted in some previous studies, which suggested that corrosion could be many metres thick, compromising the integrity of the cap rock to contain the CO2.

“Earlier studies, using computer simulations and laboratory experiments, have suggested that these cap rocks might be progressively corroded by the CO2-charged brines, formed as CO2 dissolves, creating weaker and more permeable layers of rock several metres thick and jeopardising the secure retention of the CO2,” said Prof Mike Bickle, director of the Cambridge Centre for Carbon Capture and Storage at Cambridge University.