A material-emissions-uptake-nexus driven framework for decarbonizing cement sector in China

Abstract

Over four gigatons of cement are produced annually worldwide, contributing approximately 7.5% of total anthropogenic CO2 emissions. Decarbonizing the cement sector is both arduous and urgent, given the imperative to achieve net-zero CO2 emissions by 2050 to limit global warming to 1.5°C above pre-industrial levels. The process of cement production, particularly clinker production, is one of the most challenging to decarbonize. Approximately two-thirds of the emissions from clinker production stem from limestone decomposition, which cannot be mitigated by decarbonizing energy alone. Alternative cements and clinkers are not yet ready for large-scale deployment. Traditional supply-side strategies, such as energy efficiency improvements and fuel switching, leave limited room for further significant reductions. Consequently, carbon capture and storage (CCS) technologies must play a crucial role on the supply-side decarbonization. Furthermore, previous decarbonization roadmaps often lack spatially explicit guidance for practical implementation, particularly for CCS. On the demand side, future cement consumption is rarely projected systematically, and mitigation potentials from the demand side are seldom investigated. Moreover, the potential role of atmospheric CO2 absorption through carbonation reactions in cement materials, which could serve as a significant carbon sink, has not been fully integrated into existing decarbonization strategies. In response, this research develops a comprehensive framework to decarbonize the cement sector within a material-emissions-uptake (MEU) nexus, effectively integrating both demand- and supply-side dynamics. The world’s largest cement producer, China’s cement sector, is selected as a detailed case study throughout this thesis. Through the MEU framework, historical in-use cement stocks and the associated carbon fluxes (both emissions and uptake), are explicitly analyzed. Then, future in-use cement stock and demand, as well as mitigation potentials, are thoroughly explored and projected through demand-side scenario analysis, with their impacts on emissions and uptake being quantitatively assessed. Following this, the study integrates these demand-side insights with traditional supply-side measures and CCS technologies to develop decarbonization pathways aligned with 1.5°C, 1.7°C, and 2.0°C climate targets. Additionally, a spatial supply-demand and emissions-storage matching analysis is conducted to identify strategic locations for large-scale CCS deployments across China. This comprehensive approach not only provides a robust and feasible pathway for achieving net-zero emissions in the cement industry but also balances supply- and demand-side efforts while leveraging spatial analysis for optimized CCS implementation. The contributions of this thesis are multifaceted. Theoretically, it advances the understanding of the material-emissions-uptake nexus for the cement sector, enabling a more comprehensive analysis by integrating supply- and demand-side dynamics. Methodologically, it introduces a simplified supply-demand matching model that reduces computation time while maintaining empirical accuracy. Practically, it provides valuable spatial-temporal insights for policymakers and industry investors, identifying priority regions for CCS deployment to enhance efficiency and reduce pipeline construction and transportation costs as well failure risks of CCS projects.