Analysis of theoretical carbon dioxide emissions from cement production: Methodology and application

Alternative low-carbon cements could contribute significantly to CO2 reduction in the cement industry. However, the existing methods require the input of the actual production data, and thus cannot be used to calculate CO2 emissions of alternative low-carbon cements that are not yet produced in cement plants. This study aims to develop a model to analyze the theoretical CO2 emissions of alternative low-carbon cements. The novelty of this model is that it can be used to calculate the fuel consumed in the production of new low-carbon cements based on the theory of heat balance, and then predict their CO2 emissions. The model is used to calculate CO2 emissions of several low-carbon binders and ordinary Portland cement (OPC). The results show that the direct CO2 emissions of OPC clinker calculated by this model approach the value derived from the cement plants and the Cement Sustainability and Initiative (CSI). Calcium sulfoaluminate (CSA) clinker has the direct CO2 emissions of 0.540 kg/kg, 34% lower than OPC clinker, while its cost of raw materials is over four times that of OPC clinker. High-belite calcium sulfoaluminate (HB-CSA) clinker, with the direct CO2 emissions comparable to CSA clinker, lowers its cost of raw materials by half as it requires less expensive bauxite. Moreover, CO2 emissions from HB-CSA cement production can be further reduced by the use of high volume of supplementary cementitious materials (SCMs). The knowledge gained provides a valuable reference for the design of new low-carbon binders.