Life cycle environmental impact of system irreversibility based on advanced exergy analysis: A case study

Optimizing system irreversibility has been a major concern for the global environmental impacts of production, use, and disposal of goods in international value chains. However, the life cycle environmental impact of system irreversibility based on advanced exergy analysis is still opened problem. Using coal-to-SNG as a case study, this study conducted an integrated assessment of advanced exergy analysis and life cycle environmental impact to provide more insight into system optimization. Based on advanced exergy analysis, SNG production system still has considerable improvement potential because 61.88% of exergy destruction is avoidable. Using life cycle assessment with inventory modified by advanced exergy analysis, the improvement potentials of life cycle environmental impacts can be identified by the near-, mid-, and long-term technological optimization scenarios of SNG production process. The results show that acidification potential, global warming potential, and ozone layer depletion potential throughout the life cycle will continue to decrease, while the optimization potentials of abiotic depletion, eutrophication and human toxicity will gradually become flattened with continuous technology optimization. The potentials for reducing life cycle environmental impacts brought by improving system irreversibility are limited (15%-25%), but they are also indispensable. The results may be helpful to understand the life cycle environmental impact of system irreversibility improvement and optimize environmental performance of industrial systems.