Environmental tradeoff on integrated carbon capture and in-situ methanation technology

Compared to conventional CO₂ removal methods, carbon capture and in-situ conversion using dual function materials avoid compression and transportation of CO₂, which is regarded as a promising technology. Although it brings additional economic benefits, the environmental impacts of CO₂ capture and conversion remain unclear. A life cycle assessment of an integrated CO₂ capture and methanation system using dual function materials is conducted to investigate its feasibility to reduce global warming. Life cycle inventory is obtained through construction, operation, and disposal process of the integrated system. A dynamic model of CO₂ capture and methanation is developed to obtain the operating parameters. Results show that the optimal global warming potential is 0.706 kg CO_2,eq per kilogram captured CO₂, which indicates the advantages of using dual function materials for carbon mitigation. Global warming potential is a minor factor among the overall normalized environmental impacts, only accounting for 0.5 % of the total normalized impact, while the main factor marine aquatic ecotoxicity accounts for around 73 %, and fresh water aquatic ecotoxicity accounts for around 23 %. Global warming potential is the most affected by green hydrogen input, followed by dual function material input. Results reveal that the integrated CO₂ capture and conversion using dual function materials is conducive to carbon mitigation but has significant other environmental impacts, such as marine aquatic ecotoxicity, and the main contributors to the environmental impacts are wind electricity, green hydrogen, refrigerator, and dual function material.