Global decarbonization potential of CO mineralization in concrete materials.

CO mineralization products are often heralded as having outstanding potentials to reduce CO-eq. emissions. However, these claims are generally undermined by incomplete consideration of the life cycle climate change impacts, material properties, supply and demand constraints, and economic viability of CO mineralization products. We investigate these factors in detail for ten concrete-related CO mineralization products to quantify their individual and global CO-eq. emissions reduction potentials. Our results show that in 2020, 3.9 Gt of carbonatable solid materials were generated globally, with the dominant material being end-of-life cement paste in concrete and mortar (1.4 Gt y). All ten of the CO mineralization technologies investigated here reduce life cycle CO-eq. emissions when used to substitute comparable conventional products. In 2020, the global CO-eq. emissions reduction potential of economically competitive CO mineralization technologies was 0.39 Gt CO-eq., i.e., 15% of that from cement production. This level of CO-eq. emissions reduction is limited by the supply of end-of-life cement paste. The results also show that it is 2 to 5 times cheaper to reduce CO-eq. emissions by producing cement from carbonated end-of-life cement paste than carbon capture and storage (CCS), demonstrating its superior decarbonization potential. On the other hand, it is currently much more expensive to reduce CO-eq. emissions using some CO mineralization technologies, like carbonated normal weight aggregate production, than CCS. Technologies and policies that increase recovery of end-of-life cement paste from aged infrastructure are key to unlocking the potential of CO mineralization in reducing the CO-eq. footprint of concrete materials.