Institute of Technical Thermodynamics, RWTH Aachen University, 52062 Aachen, Germany.
Global R&D, HeidelbergCement AG, Oberklamweg 2-4, 69181 Leimen, Germany.
Environ Sci Technol. 2021 Apr 20;55(8):5212-5223. doi: 10.1021/acs.est.0c07599. Epub 2021 Mar 18.
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.
水泥工业排放了全球人为温室气体（GHG）排放的 7%。减少水泥工业的温室气体排放具有挑战性，因为水泥生产在煅烧石灰石时会产生化学计量的 CO。在这项工作中，我们提出了一条使用 CO 矿化实现碳中和水泥工业的途径。CO 矿化将 CO 转化为热力学稳定的固体和副产物，这些副产物有可能替代水泥。因此，CO 矿化可以通过两种机制来减少水泥工业的碳足迹：（1）从水泥厂的烟道气中捕获和储存 CO，（2）通过替代水泥来减少熟料的使用。然而，由于克服缓慢反应动力学所需的能量，CO 矿化也会产生温室气体排放。因此，我们根据生命周期评估分析了结合 CO 矿化和水泥生产的碳足迹。我们的结果表明，在考虑到理论潜力的情况下，使用当今能源组合的 CO 矿化和水泥生产相结合，可将水泥工业的碳足迹减少 44%，甚至高达 85%。低碳能源或在水泥中更高比例地混合矿化产品可以实现碳中和的混合水泥生产。通过直接空气捕获，混合水泥甚至可以实现碳负排放。因此，我们的结果表明，开发 CO 矿化和水泥生产相结合的工艺和产品，可以将水泥工业从不可避免的 CO 源转变为 CO 汇。
