Cost–benefit comparison of steel slag co-utilization and carbon capture, utilization and storage pathways for cement industry decarbonization: Evidence from China

Process emissions from clinker production make the cement industry difficult to decarbonize, highlighting the need for cost-effective mitigation pathways. Steel slag co-utilization and carbon capture, utilization, and storage (CCUS) are promising options, yet their comparative performance under real industrial clustering conditions remains unclear. This study aims to compare these two pathways for cement industry decarbonization in Hebei Province, China. A life-cycle cost comparison framework was developed by integrating a multi-objective mixed-integer linear programming (MILP) model for optimizing steel slag flows between steel mills and cement plants with a CO₂ source-sink matching model for evaluating CCUS deployment over a 30-year horizon. Results show that steel slag co-utilization provides a lower-cost mitigation option for plants located in steel-cement clusters, with abatement costs ranging from 292.75 to 840.60 CNY/tCO₂ and cumulative emission reductions of 102 million tons CO₂. CCUS performance varies substantially by storage type. Oil and gas reservoir storage can achieve negative abatement costs, while saline aquifer storage ranges from 338.65 to 507.94 CNY per ton of CO₂ and yields cumulative reductions of 1266 million tons. Among the 46 cement plants assessed, 32.6% are better suited to steel slag co-utilization, 60.9% should prioritize CCUS deployment, and 6.5% are suitable for a hybrid pathway. The findings reveal the two pathways’ distinct mechanisms and spatial patterns and support more effective decarbonization planning for the cement industry.