REPURPOSING redundant North Sea oil and gas rigs could enable them to be used to pump huge quantities of carbon dioxide (CO2) emissions into rocks below the seabed, according to Scottish researchers.

They said refitting the old platforms to act as pumping stations for self-contained CO2 storage sites would also be 10 times cheaper than decommissioning them.

Such a move would see the sites store emissions generated by natural gas production, as well as being used to lock away CO2 produced by other sources – such as power stations – which would help to combat climate change.

The University of Edinburgh scientists analysed data from the Beatrice oilfield – 15 miles off the north-east coast of Scotland – and found that making minor modifications could enable existing platforms to be re-used as storage sites.

Using a computer model, the team calculated that over a 30-year period, the scheme would be around 10 times cheaper than decommissioning the Beatrice oil field, which is likely to cost more than £260 million.

The team also found that large amounts of natural gas and heat energy can still be extracted from saltwater in exhausted oil and gas fields.

Such gas can be used as a fuel or burnt on platforms to generate electricity.

Researchers said mixing the saltwater from the oil field with CO2 produced by burning the gas enables it to be injected deep underground for permanent safe storage.

The scheme would also bring down the costs of storing carbon emissions and postpone expensive decommissioning of North Sea oil and gas infrastructure.

The study, published in the International Journal of Greenhouse Gas Control, was completed as part of the University of Edinburgh’s GeoEnergy MSc programme.

Jonathan Scafidi, of the university’s School of GeoSciences, the report’s lead author, said: “Removing platforms at large expense is short-sighted.

“Re-using them to dispose of CO2 in rocks several kilometres beneath the seabed will not only be cheaper, but provides a cost-effective means of cutting the UK’s CO2 emissions to meet the 2050 net-zero target.”

Dr Stuart Gilfillan, also of the School of GeoSciences, who co-ordinated the study, added: “Our study shows, for the first time, that natural gas production from saltwater can be combined with CO2 storage in the North Sea.

“The potential revenue provided by extending natural gas production in the North Sea could help kick-start a world-leading carbon capture and storage industry in the UK.”

A contract for the development of Scotland’s first carbon capture and storage (CCS) project using oil and gas sector infrastructure was last December awarded to an Aberdeenshire company by oil industry watchdog the Oil and Gas Authority.

Pale Blue Dot Energy, based in Banchory, won the initial four-year licence for its Acorn CCS project.