Integrating Stock-Flow Modeling and Energy System Optimization to Explore Decarbonization Pathways for China's Cement Industry.

In the global effort to mitigate climate change, the cement sector remains highly emission-intensive and hard-to-decarbonize. Previous research has highlighted material efficiency strategies─including more intensive use, lifetime extension, material-efficient design, and end-of-life processes, as demand-side options for reducing emissions. However, unintended effects and supply side responses, such as shifts in technological portfolios and investment trends, remain underexplored. This study develops a framework that couples detailed stock-flow modeling and a bottom-up energy system optimization model, a subcategory of integrated assessment models. Taking China's cement sector as a pilot case, our framework projects comprehensive decarbonization pathways for cement-based materials. The results show that material efficiency strategies could reduce cement demand by 57%, significantly decreasing reliance on supply side technologies required for net-zero emissions, with these strategies contributing nearly 50% of the cumulative decarbonization effort. The material efficiency strategies also reduce the incremental total production costs associated with low-carbon technologies in upstream sectors. When combined with CO2 uptake from cement-based materials, this study offers a cost-effective pathway for achieving net-zero emissions in the cement sector, lowering both costs and CO2 emissions without heavy dependence on carbon capture and storage.