Environmental impacts of carbon capture and utilization by mineral carbonation

Mineral carbonation technologies are associated with the concept of Carbon (dioxide) capture, utilization, and storage and rely on the mineralization reaction, which can be observed in nature. In order to overcome the slow natural reaction rates, diverse pathways are studied to sequester carbon dioxide into mineral products. However, studies that perform a life cycle assessment (LCA) on mineral carbonation are poorly comparable due to differences in the assessment methodology. A two-step approach is applied to report on and overcome this issue. First, a qualitative analysis based on a systematic literature review of 29 relevant articles was conducted. Second, a meta analysis with harmonized methodological assumptions was applied to assess which of the proposed ex-situ carbonation routes in literature has the lowest environmental impacts (16 different impact categories assessed). The qualitative literature review demonstrates that the most critical difference of the published LCAs on mineral carbonation technologies is handling multifunctional processes, as this parameter influences the result of an LCA. Since none of the assessed studies evaluated the technology readiness level (TRL) of the investigated technology, a TRL estimation based on the studies' descriptive information, ranging from 2 to 6, was provided. This is reflected in the predominant usage of laboratory or simulated data as the primary data source. The main finding of the meta analysis in terms of global warming and the impact category minerals and metals is that direct aqueous carbonation, carbonation mixing, and carbonation curing show negative values in those impact categories despite the deployed scenario. Hence, these three mineral carbonation technologies seem to be most promising. However, it could be demonstrated that other impact categories show positive results. In the case of indirect aqueous carbonation, it depends on the substitution credit assumed whether this pathway acts as a climate mitigation pathway.