Old oil rigs could become CO2 storage sites
North Sea oil and gas rigs could be modified to pump carbon dioxide emissions into rocks below the seabed, Edinburgh scientists have found.
Refitting old platforms to act as pumping stations for self-contained CO2 storage sites would be 10 times cheaper than decommissioning the structures.
The sites would store emissions generated by natural gas production.
They could also be used to lock away CO2 produced by power stations, helping to combat climate change.
Edinburgh University scientists analysed data from the Beatrice oilfield - 15 miles off the north east coast of Scotland.
They found existing platforms could be re-used as storage sites by making minor modifications.
Using a computer model, they worked out that over a 30-year period, the scheme would be about 10 times cheaper than decommissioning the Beatrice oilfield, which is likely to cost more than £260m.
Large amounts of natural gas and heat energy can still be extracted from saltwater in exhausted oil and gas fields, the team found.
The researchers have found 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 team said the scheme would bring down the costs of storing carbon emissions and postpone expensive decommissioning of North Sea oil and gas infrastructure.
The study, published in International Journal of Greenhouse Gas Control, was completed as part of Edinburgh University's GeoEnergy MSc programme.
Jonathan Scafidi, of the University of Edinburgh's School of GeoSciences, 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, said: "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."