Ancient rock formations could store millions of tonnes of CO2, research says

Ancient rocks formed by volcanoes could safely store millions of tonnes of carbon dioxide by turning it to stone, researchers have said.

Scientists at the University of Edinburgh have identified several underground volcanic formations around the UK that they say could store more than 3,000 million tonnes of industrial CO2 waste, which they say is approximately equivalent to 45 years worth of UK industrial emissions.

Some areas deemed fit by researchers include places in Co Antrim in Northern Ireland, the Isle of Skye in Scotland, and in the Lake District, England.

The teams say the areas are rich in calcium and magnesium, which binds with CO2 to form a solid mineral in a process known as carbon mineralisation.

The process works by dissolving captured CO2 in water, which is then injected into volcanic rocks deep underground.

Mineralisation occurs in the cracks and spaces between the rocks, turning the carbonated water into stone.

The team then calculated how much CO2 each rock group can hold after combining the surface area and thickness of the rocks with details of their chemistry.

Mid-range estimates said the Antrim Lava Group in Northern Ireland could hold about 1,400 million tonnes of CO2.

The Borrowdale Volcanic Group in England was estimated to offer 700 million tonnes of storage, and the Skye Lava Group could store about 600 million tonnes.

According to the research team, similar pilot projects in Iceland and in the US have already found positive results, with larger scale projects ongoing to measure how much CO2 can be stored via the method.

Safe, permanent storage of CO2 will be required to limit g­lobal warming to between 1.5C and 2C above pre-industrial levels, with mineralisation providing a storage solution for the UK, researchers say.

The study was published in Earth Science, Systems and Society, issued by the Geological Society of London, and was funded by the National Environment Research Council (NERC).

Angus Montgomery, who started the study while studying geology and physical geography at the University of Edinburgh, said: “By showing where the UK’s most reactive volcanic rocks are and how much CO2 they could lock away, we highlight a practical and permanent way to mitigate unavoidable industrial emissions, adding to the UK’s arsenal of decarbonisation options.”

Professor Stuart Gilfillan, personal chairman of geochemistry from the University of Edinburgh, who led the study, said: “To cut CO2 emissions at scale, we urgently need carbon storage.

“CO2 mineralisation offers the UK more room to store CO2, adding to the huge resource offered by the rocks beneath the North Sea.

“Our next steps are to assess effective porosity and rock reactivity in detail. This will tell us how efficiently each formation can mineralise CO2 in practice.”