Comparison of multi-criteria decision-analysis methods for selecting carbon dioxide utilization products

The paper presents several multi-criteria decision-analysis methods for the purpose of assessing carbon dioxide utilization pathways, to identify and select the most relevant processes to convert captured CO₂ from industrial gas streams into compounds of interest. This paper explores and illustrates the application of decision-analysis approaches, their associated outcomes and how these both differ and complement each other. It includes non-compensatory methods (LexiMin and LexiMax), aggregation-based methods (Weighted Sum Model and Analytic Hierarchy Process), and the elimination and choice expressing the reality approach. Nine indicators grouped into three performance criteria, involving engineering, economic, and environmental aspects, are considered to assess ten alternatives and help to identify the preference relation among them. The rankings and their tolerance to change in criterion and indicator weights are compared amongst the selected methods, highlighting the fact that some indicators are more sensitive than the others. Even though the results obtained by the aggregation methods are more decisive, the outranking method proposes more qualified conclusions, where the techno-economic and environmental aspects are complementary but not interchangeable. Low degree compensatory methods might be advised in the specific field of CO₂ utilization, as well as in the wider issue of environmental decision-making. Also, this paper discusses the limitations of the proposed methods, while providing insights and some recommendations for applications of these approaches in similar contexts. Overall, the results show that methanol, methane, and dimethyl carbonate are CO₂-based products that are the most promising to be implemented in very near future with respect to engineering, economic, and environmental performances.