A net climate benefit is defined by the study as the emissions avoided by using CCU technology that outweighs the emissions generated while capturing the gas and making the final product.
The research investigated the uses of captured CO2 in three categories – concrete, chemicals and minerals, ranking them by how much each category benefits the climate.
With estimates showing that captured CO2 could reduce climate-altering emissions by up to 15% by 2030, previous studies discovered that 6.2 gigatonnes of CO2 could be consumed annually by 2050 by using CCU to make products in the above categories.
The study revealed that only four of the 20 “CCU pathways” analysed have a greater than 50% chance of generating a ‘net climate benefit’.
These pathways include two methods that use CO2 to mix concrete, one method to make carbon monoxide from methane, and a method to produce formic acid through the hydrogenation of CO2.
Carbon monoxide is most often used in industrial processes such as synthetic chemical manufacturing and metallurgy, while livestock includes formic acid as a preservative and antibacterial agent, as well as being used to tan leather and as a textile dye.
Commenting on the importance of conducting such research, Dwarak Ravikumar, lead author, formerly of University of Michigan’s Centre of Sustainable Systems, said, “Decisions to globally scale CCU operations will require guidance on identifying products that maximise the climate benefits of using captured CO2.”
He added that their rankings will help prioritise future R&D strategies towards products with the greatest climate benefit.
Considering carbon can be captured via various methods, the study assumed that the CO2 captured would be from a natural gas power plant.
The full study can be accessed here.