Assessment of Cement-Decarbonization Pathways in South Africa Using Time-Dependent Scenario Modeling, Production-Stage Carbon Accounting and SBM-DEA

Cement production generates substantial carbon emissions through clinker calcination and fuel combustion. This study applies a sequentially coupled Time-Dependent Scenario–Carbon Accounting–Slacks-Based Measure Data Envelopment Analysis (TDS–CA–SBM-DEA) framework to assess five South African cement-decarbonization pathways from 2023 to 2050: business-as-usual (BAU), energy efficiency and alternative fuels (EFF_FUEL), clinker substitution and material efficiency (CLINKER_MAT), carbon capture and novel binders (CCS_NOVEL), and an integrated net-zero-oriented pathway (NET_ZERO). Production-stage accounting explicitly accounts for amine-based carbon capture, which requires 3.0 GJ of regeneration heat and 100 kWh of auxiliary electricity per tonne of CO2 captured, including emissions from the natural-gas heat supply. Modeled baseline emissions are 8.49 Mt CO2 in 2023. By 2050, BAU reaches 9.50 Mt CO2, while CCS_NOVEL and NET_ZERO decline to 3.54 and 1.53 Mt CO2, respectively. NET_ZERO achieves a carbon intensity of 0.128 t CO2/t cement and cumulative emissions of 140.1 Mt CO2, avoiding 111.6 Mt, relative to BAU. CLINKER_MAT and NET_ZERO remain on the constructed 2050 DEA frontier. Sensitivity analysis identifies clinker factor as the strongest cumulative-emissions driver, while capture deployment and efficiency most influence residual emissions. The framework distinguishes carbon mitigation from scenario-relative resource efficiency, and highlights the additional thermal burden of selected capture technologies. The results are conditional on prescribed sector-level assumptions.