Curing time: a temporally explicit life cycle CO2 accounting of mineralization, bioenergy, and CCS in the concrete sector

Abstract

The decarbonization of concrete production requires a multi-pronged approach including the abatement of CO₂ emissions from cement production as well as storage of CO₂ within concrete itself. This study explores the decarbonization potential of combining bioenergy and carbon capture and storage (CCS) during cement production with the accelerated carbonation of fresh concrete and the natural carbonation of demolished concrete for the life cycle net CO₂ of 30 MPa ordinary Portland concrete. As both biomass and concrete reuptake CO₂ over time, the timing of CO₂ emissions and removals is explicitly accounted for. At current technology levels, the combination of bioenergy and CCS in cement production combined with the carbonation of demolished concrete was seen in our model to allow for net CO₂-negative concrete. However, the concrete is CO₂-positive until the CO₂ of production is reabsorbed by biomass regrowth and the carbonation of demolished concrete at end-of-life. In our model, accelerated carbonation was, by itself, an inefficient CO₂ storage mechanism, due to the penalty of energy use and injection losses. However, if it led to a gain in concrete strength, accelerated carbonation could result in lower CO₂via reduced resource demand and cement production.