Low-carbon cement manufacturing enabled by electrified calcium looping and thermal energy storage

Abstract

Decarbonization of the cement industry is an important goal in the carbon neutralization vision. Calcium looping is a promising decarbonization method in the cement industry due to the well-established solid management system and the direct utilization of deactivated sorbent in cement manufacturing. Oxyfuel combustion is often used in the calcium looping to obtain high-purity CO2, yet results in large capital expenditures on the air separation unit and high electricity and fuel consumption. In this work, we propose an electrified calcium looping process which uses electric heating from renewables and thermal energy storage to replace fossil fuels. The CO2 generated in the calciner is directly separated with CO2 as the heat transfer fluid. The proposed process in a cement plant is assessed in the energy, environment, and economic aspects with both tail-end configuration and integrated configuration. Compared to conventional oxyfuel-based calcium looping, electrified calcination can reduce the primary energy consumption in cement manufacturing from 7458.0 MJ/t-clinker to 6484.0 MJ/t-clinker in the tail-end configuration and from 5320.9 MJ/t-clinker to 4996.6 MJ/t-clinker in the integrated configuration, at a CO2 capture efficiency of 90%. The reduced fuel consumption decreases CO2 emissions and capital expenditures for the CO2 capture system. Replacing oxyfuel with electrification and thermal energy storage brings only a limited reduction in the cost of CO2 avoidance in the integrated configuration, and the economic benefits can be significantly improved with lower-priced renewable energy. This work provides insights into the applications of cost-effective renewable energy, electric heating, and thermal energy storage in calcium looping-based industrial decarbonization.