Does the Cement Industry Need Carbon Capture and Storage to Decarbonize?

Cement production is responsible for approximately 7–8% of global CO₂ emissions, with a majority arising from limestone decomposition during clinker production. Electrification of high-temperature heat remains highly costly, and the process emissions are unavoidable, which makes deep decarbonization of the cement sector particularly challenging.  

At the same time, the technological landscape for cement production is rapidly evolving. A range of clinker substitutes including ground blast furnace slag (GBFS), fly ash (FA), and uncalcined limestone are already in use and offer low-cost potential to reduce emissions by reducing clinker ratios.  Other emerging technologies such as limestone calcined clay cement (LC3) or electrochemical processes could further reduce or even eliminate the need for conventional clinker. However, these are incompletely represented in most Integrated Assessment Models (IAMs).

To address this gap, we extend the Global Change Analysis Model (GCAM) by explicitly separating cement and clinker production and endogenizing the supply of key clinker substitutes through their linkage to iron and steel production (GBFS) and coal-based electricity generation (FA). We further introduce LC3 and other alternative cement chemistries capable of substantially reducing or eliminating conventional clinker use. These developments are evaluated across a set of no-policy and low emissions scenarios with regionally explicit constraints on CCS deployment.

Results indicate that CCS plays a limited role in cement-sector decarbonization, even when assumed to be the primary mitigation option. In contrast, clinker substitution and alternative cement chemistries emerge as dominant mitigation pathways. Under a RCP2.6 emissions pathway, declining coal use reduces fly ash availability, increasing reliance on LC3 and other emerging technologies.

These findings suggest that no single technology is sufficient for deep decarbonization of cement production. Instead, achieving climate-aligned pathways requires a diversified portfolio of clinker substitution, alternative chemistries, and only limited deployment of CCS, supported by coordinated policy and accelerated technology scale-up.