Carbon dioxide utilization in concrete curing or mixing might not produce a net climate benefit

Carbon capture and utilization for concrete production (CCU concrete) is estimated to sequester 0.1 to 1.4 gigatons of carbon dioxide (CO2) by 2050. However, existing estimates do not account for the CO2 impact from the capture, transport and utilization of CO2, change in compressive strength in CCU concrete and uncertainty and variability in CCU concrete production processes. By accounting for these factors, we determine the net CO2 benefit when CCU concrete produced from CO2 curing and mixing substitutes for conventional concrete. The results demonstrate a higher likelihood of the net CO2 benefit of CCU concrete being negative i.e. there is a net increase in CO2 in 56 to 68 of 99 published experimental datasets depending on the CO2 source. Ensuring an increase in compressive strength from CO2 curing and mixing and decreasing the electricity used in CO2 curing are promising strategies to increase the net CO2 benefit from CCU concrete. Carbon curing or mixing in concrete is promising for carbon dioxide sequestration. Here, the authors show that the increased use of binder material to compensate the loss in compressive strength and electricity for carbon dioxide curing is more likely to increase carbon dioxide emissions on a life cycle basis for carbon cured or mixed concrete.