Priorities for supporting emission reduction technologies in the cement sector – A multi-criteria decision analysis of CO₂ mineralisation

As a major contributor to climate change, the cement sector urgently needs to develop and implement greenhouse gas (GHG) mitigation technologies to drastically lower its emissions to reach carbon neutrality by 2050. Among the most promising technologies is CO2 mineralisation in which CO2 is transformed into a thermodynamically stable carbonate. CO2 mineralisation not only offers permanent storage of CO2 but also potentially avoids emissions by partially substituting conventional cement with the obtained carbonation products. Besides overcoming technical barriers, successful development and implementation of CO2 mineralisation require support from key stakeholders. While existing studies already provide technology-related data and assess CO2 mineralisation pathways, knowledge remains scarce about stakeholder priorities and perceptions. Using a multi-stakeholder expert survey, the present study examines: a) the priorities of different stakeholders in supporting CO2 mineralisation, b) their perceptions on the performance of CO2 mineralisation concepts, and c) their priorities if tasked with communicating CO2 mineralisation technologies to other groups. Hereby, we follow a multi-criteria decision analysis approach, based on an analytical hierarchy process, by comparing indicators from the three common sustainability pillars (i.e., environmental, economic, and social impacts). Our results indicate that key stakeholders strongly prioritise the health implications of CO2 mineralisation technologies and generally value social impacts highly. Hence, an in-depth research is needed to provide knowledge-based guidance on health issues and ways to fairly distribute costs and create positive employment outcomes. Additionally, stakeholders of all affiliations give second priority to reducing carbon footprint of cement, showing that they discount potential environmental and economic trade-offs associated with emission reduction goals. The results reveal that these concepts are perceived as compatible with other GHG mitigation approaches, such as carbon capture and storage. Moreover, if tasked with convincing different target groups to support CO2 mineralisation, stakeholders prioritise diverse themes, recognising that communication strategies must address the specific concerns of each group. Overall, the results can help investors, managers, and policymakers to ensure that upcoming decisions in R&D, investments, and the design of support mechanisms align with the priorities of key stakeholders. Our results facilitate communicating technological potentials and risks and can foster successful development and implementation of CO2 mineralisation pathways.