North Sea oil and gas rigs could be modified to pump vast quantities of carbon dioxide emissions into rocks below the seabed, according to a study by researchers at the University of Edinburgh.

Refitting old platforms to act as pumping stations for self-contained CO₂ storage sites would be 10 times cheaper than decommissioning the structures, researchers say.

The sites would store emissions generated by natural gas production, and could also be used to lock away CO₂ produced by other sources such as power stations.

The Edinburgh researchers analyzed data from the Beatrice oilfield, 15 miles off the north east coast of Scotland. They found that 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 around 10 times cheaper than decommissioning the Beatrice oilfield, which is likely to cost more than £260 million (US$316 million).

Removing platforms at large expense is short-sighted. Re-using them to dispose of CO₂ in rocks several kilometers 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.

—Jonathan Scafidi, School of GeoSciences

Large amounts of natural gas and heat energy can still be extracted from saltwater in exhausted oil and gas fields, the team found. The gas can be used as a fuel or burnt on platforms to generate electricity.

Mixing saltwater from the oil field with CO₂ produced by burning the gas enables it to be injected deep underground for permanent safe storage, researchers say.

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

Resources

• Jonathan Scafidi, Stuart M.V. Gilfillan (2019) “Offsetting Carbon Capture and Storage costs with methane and geothermal energy production through reuse of a depleted hydrocarbon field coupled with a saline aquifer,” International Journal of Greenhouse Gas Control, Volume 90, 102788 doi: 10.1016/j.ijggc.2019.102788