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

Abstract

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.