The hunt for big carbon dioxide storage sites offshore Africa must begin quickly to ensure that rising emissions from a fast-growing continent can be captured before they play havoc with the global climate, according to a senior Equinor researcher.
Africa accounts for just 3% of greenhouse gas emissions, said Philip Ringrose, with a per-capita average in 2018 of 0.9 tonnes per annum, far below that of Europe (7 tpa) and the US (16 tpa).
However, a rapid increase in the continent’s population in the coming decades will drive economic growth and increase emissions. So Africa must urgently find locations to store CO2 because, while renewables will probably make a big contribution to future energy supplies, use of natural gas will also accelerate.
Africa will need to deal with these CO2 emissions through deployment of nascent direct air capture technology or by finding suitable geological storage sites into which the waste gas can be injected.
Ringrose, who also works for the Norwegian University of Science & Technology, and Tip Meckel, from the University of Texas in Austin, published a paper in Nature two years ago that assessed global offshore CO2 storage resources.
Their research concluded that to keep global warming to less than 2 degrees Celsius by 2050, about 12,000 CO2 injection wells will need to be drilled globally.
Assuming five continents have one dedicated carbon capture and storage hub each, this figure breaks down into 100 to 200 wells at each hub over the next decade, a number within the capabilities of the upstream drilling sector.
“Our main argument is that this is not a lot; it’s a very achievable objective,” Ringrose told delegates at an Africa E&P event organised by PESGB-HGS.
Due to the sparsity of data elsewhere, the 2019 study focused on the storage potential of two well-understood oil and gas basins: the US Gulf of Mexico and the North Sea.
The North Sea’s mapped CO2 storage resource came out at 160 gigatonnes, while North America’s is at least 2400 Gt.
Only 0.2 Gt of global storage ullage is currently being used, based on about 50 injector wells.
According to the International Energy Agency, Africa’s CO2 emissions in 2018 totalled 1.2 Gt and will hit about 1.8 Gt, possibly more, by 2050, despite what Ringrose called “phenomenal growth” in renewable electricity generation of 8% to 11% per annum.
He said the main sources of CO2 generation in Africa will be gas processing sites and emerging hydrogen infrastructure, industries such as fertiliser and cement, and coal-fired power plants, largely in southern Africa.
To deal with extra CO2 emissions of about 0.6 Gt annually by 2050, Ringrose estimated that Africa will need 110 injection wells in operation by 2030, and 840 wells with total storage capacity of 6.4 Gt by 2050.
Given historic drilling activities in West Africa alone, he said, this well requirement is “small”.