Decarbonizing Cement and Concrete: A Curable Problem

Cement manufacturing is responsible for over 7% of global CO2 emissions and represents a major part of recalcitrant emissions by midcentury in most global models of decarbonization pathways as global demand is expected to increase considerably over the coming decades. Cement production is challenging to decarbonize because of the high temperatures required and the direct emissions from the calcination of limestone. This work uses a meta-analysis of life cycle assessment (LCA) paired with a techno economic assessment (TEA) to evaluate five different decarbonization pathways, with a focus on understanding the role that CO2 curable pre-cast concrete will play in the decarbonization of the production of cement and concrete. We modeled (1) the adoption of a high efficiency kiln system, (2) the use of alternative fuels, (3) the use of supplemental cementitious materials (SCMs), (4) the use of alternative cements, and (5) the installment of carbon capture and storage (CCS) at cement plants. The results suggest that pre-cast curable elements have significant potential to reduce the life cycle CO2 emissions of concrete. Adding CCS to a cement production facility produces the deepest cuts in emissions but at the greatest expense. Other options, such as high efficiency kilns and use of SCMs cut emissions modestly whereas the use of alternative cements could produce the kinds of appreciable emissions cuts over the life cycle, without dramatically increasing the price of concrete. The outputs from the LCA-TEA are then used to inform the integrated assessment model (IAM), Global Change Analysis Model (GCAM). This represents the first in-depth look at decarbonization pathways in an integrated modeling context. The results point to interesting connections related to interactions between various sectors (for example, important changes in SCM availability over the coming decades as coal-fired power plants are retired at the global scale) in order to evaluate the role CO2 curable pre-cast concrete plays in global decarbonization.