Deep decarbonization of the cement sector: a prospective environmental assessment of CO2 recycling to methanol

Abstract

Current decarbonization pressures are prompting efforts to reimagine the future of the hard-to-abate cement sector. To date, fuel switching has arisen as the most readily operational strategy, and its application in the cement sector is expected in the short to midterm. However, around two-thirds of the cement CO2 emissions come from the calcination of limestone. The implementation of CO2 capture utilization and/or storage will be crucial to support a reliable net-zero carbon future by 2050–2070. CCS is considered as the most carbon-neutral technology in the cement decarbonization roadmap, while CO2 recycling (CCU) has arisen as a suitable strategy for those locations where there is an industrial symbiosis between the cement market and CO2-based chemical markets (e.g., methanol, formic acid, etc.). Despite that the CCU strategy cannot be carbon-neutral by itself, it could be a powerful option in combination with CCS. To date, most CO2 recycling technologies are still emerging, and their development has to be boosted in the next decades. In this study, a prospective environmental analysis has been conducted through life cycle thinking to explore the benefits of cement long-term decarbonization by implementing a carbon recycling plant (CRP) based on the emerging electrochemical reduction (ER) of CO2 to produce methanol (MeOH). The study aims to demonstrate the synergic decarbonization and defossilization for both cement and MeOH markets, respectively. Cell energy efficiency and MeOH concentration have been identified as the key performance parameters that should be around 60% and 40% wt, respectively, to ensure a future sustainable implementation of ER to the MeOH technology. A CRP powered by low-carbon renewable electricity (<0.02 kg CO2eq/kW h) and with a low-fossil depletion (FD) impact (<0.01 kg oileq/kW h) could lead to an integrated cement and MeOH production with sharp reductions in the carbon footprint (∼75%) and FD (∼66%) of the integrated cement and MeOH production compared to the conventional fossil-based productions. The proposed CO2 recycling scheme can contribute to accelerating the innovation of carbon capture and recycling technologies and their deployment in these hard-to-abate sectors.