Reducing Emissions in the Cement Industry
The cement industry is a large emitter of carbon dioxide, accounting for nearly eight per cent of global emissions, and this research, funded through ERA’s Biological and Adaptation Program in 2017, provided a framework for replacing high-carbon intensity fuels with alternative low-carbon fuels (ALCFs), such as waste streams, in cement production. In addition, by using ALCFs in combination with carbon capture, cogeneration and other technologies, the cement manufacturing industry can move towards sustainability and eventually net zero.
Emissions in the cement industry arise from the carbon emitted during the conversion of limestone and other minerals to clinker – the backbone of cement production – and from the use of fossil fuels in those thermal processes. In the Canadian cement industry, currently, over 90 per cent of fuels used are coal, petcoke, natural gas and other high fossil content fuels. To lower their carbon footprint, Lafarge Holcim Canada worked with the University of Calgary to explore replacing fossil fuels with waste-based ALCFs, which has the added benefit of providing a disposal pathway for this waste. The study also investigated the impact of an integrated low emission cement and power reduction system (LECAPP) on GHG emissions. This system incorporates external reforming molten carbonate fuel cells to capture the CO2 emissions from a natural gas-fired cement plant. The results of the study, which was completed in 2022, can assist the cement manufacturing industry in choosing the optimal ALCF content for their plant.
Ensuring the Safe Transition to Alternative Fuels
The results of this study show that replacing 50 per cent of the energy content of natural gas with an alternative fuel mixture containing construction and demolition waste, railway ties, asphalt shingles and other such materials can result in up to 3.9 per cent reduction in the greenhouse gas (GHG) emissions and NOx emissions could reduce by 6.6 per cent. However, before transitioning to ALCFs at cement kilns, there are several safety issues that must be considered. The explosibility of dusts from ALCFs may pose new risks, and dust hazard analysis should be conducted at all cement facilities implementing ALCF. The researchers also found that using integrated low-emission cement and power production technologies to produce both a CO2 stream for sequestration and a by-product of low carbon electricity reduced GHG emissions from clinker production by 92 per cent compared to a plant without carbon management.
What’s next?
A successor project has been funded under ERA#3 E0160289 “Low Carbon Fuels Project” by Lafarge (Website link: Lower Carbon Fuels Project – Emissions Reduction Alberta (eralberta.ca)). University of Calgary researchers continue to advise on the project and the knowledge of ALCF characterization, dust management, and modelling tools has been incorporated into the project implementation. With ongoing collaboration to develop and demonstrate the use of low-carbon fuels, Lafarge’s project is estimated to have an annual emission reduction of 265,000 tonnes of CO2 when the facility is fully ramped up in 2030.