From Unavoidable CO Source to CO Sink? A Cement Industry Based on CO Mineralization.

The cement industry emits 7% of the global anthropogenic greenhouse gas (GHG) emissions. Reducing the GHG emissions of the cement industry is challenging since cement production stoichiometrically generates CO during calcination of limestone. In this work, we propose a pathway towards a carbon-neutral cement industry using CO mineralization. CO mineralization converts CO into a thermodynamically stable solid and byproducts that can potentially substitute cement. Hence, CO mineralization could reduce the carbon footprint of the cement industry via two mechanisms: (1) capturing and storing CO from the flue gas of the cement plant, and (2) reducing clinker usage by substituting cement. However, CO mineralization also generates GHG emissions due to the energy required for overcoming the slow reaction kinetics. We, therefore, analyze the carbon footprint of the combined CO mineralization and cement production based on life cycle assessment. Our results show that combined CO mineralization and cement production using today's energy mix could reduce the carbon footprint of the cement industry by 44% or even up to 85% considering the theoretical potential. Low-carbon energy or higher blending of mineralization products in cement could enable production of carbon-neutral blended cement. With direct air capture, the blended cement could even become carbon-negative. Thus, our results suggest that developing processes and products for combined CO mineralization and cement production could transform the cement industry from an unavoidable CO source to a CO sink.