Defunct oil and gas platforms could pump CO2 far beneath the seabed

All across the globe, thousands of defunct oil and gas platforms remain standing in the ocean. With the cost of dismantling them astronomical, it may seem tempting to put the process off. One group of scientists from the University of Edinburgh has now come up with a compelling reason to do just that.

The proposal claims that oil and gas platforms could be modified to pump carbon dioxide several kilometres beneath the sea bed, trapping it there forever and offering redemption for these old carbon emitters. Using the Beatrice oilfield off the northeast coast of Scotland as a case study, the researchers claim that over a 30-year period, the scheme would be ten times cheaper than the cost of decommissioning the platform, which could reach more than £260million.

To bury carbon dioxide, the first stage of the process would actually create it. Rather than extracting oil from the ground far below, the platform would be modified to extract brine held within the rocks. This brine contains natural gas which would then be burned to generate electricity – an added bonus. By mixing the resulting brine with the CO2 produced by burning the natural gas, the researchers claim it could then be injected back underground, permanently storing the carbon. They add that this is a secure method that results in no leaking.

Lead author of the paper, Jonathan Scafidi explains that this process in itself wouldn’t reduce CO2 in the atmosphere, because it would only trap that which has just been created. But he says that there is potential to add large amounts of additional CO2 to the brine that is injected underground. ‘We found that by taking out the gas from the brine, burning it and putting the carbon dioxide back in, you've only used about ten per cent of the space available for carbon dioxide within the brine. So that leaves another 90 per cent available. If there’s another entity that wants to ship or pipe CO2 out there to bury, you've got the space to do it.’

The authors are keen to point out that this carbon capture and storage scheme (also known as CCS) could help the UK in its goal to reach carbon neutrality by 2050. Achieving the target will first and foremost involve drastically reducing the amount of carbon the country produces, but as some industries will undoubtedly remain carbon intensive, the government will also need to embrace CCS.

The main barrier to this type of technology is currently the cost of development. But by utilising existing oil platforms, Scafadi says the economics of this scheme make sense. ‘The cost of decommissioning is going to happen anyway, regardless of what you do,’ he says, ‘But we also have a commitment to become net zero in carbon emissions by 2050 in the UK. The only way to do that is by carbon capture and storage – that has to be part of the plan to become net zero.’

Source: geographical.co.uk