Exploring avoidable carbon emissions by reducing exergy destruction based on advanced exergy analysis: A case study

The energy efficiency improvement and practicable carbon emission reduction of coal chemical industry as well as other industrial systems are major concerns associated with designing feasible carbon emission reduction scheme. Based on advanced exergy analysis, this study establishes quantitative analysis between exergy destruction and direct carbon emission by three different methods to explore avoidable exergy destruction and subsequent avoidable carbon emissions in coal to synthetic natural gas (coal-toSNG) industry. The research shows avoidable exergy destruction accounts for 57.99% of total exergy destruction and 86.07% of total exergy destruction is endogenous, so the main causes of irreversibility of units come from units' internal operations and this coal-to-SNG system has considerable improvement potential. The avoidable carbon emissions range from 52.50 t/h (0.16kgC/Nm(3)SNG) to 165.32 t/h (0.52kgC/Nm(3)SNG) according to different assumptions. In light of the scenarios of exergy destruction reduction and available research results, the real avoidable carbon emissions may be closer to 115.95 t/h, correspondingly the carbon emission reduction potential may be 44.06%. Therefore, reducing exergy destruction by one percentage point may bring about 0.76% carbon emission reduction. This idea identifying avoidable carbon emission by avoidable exergy destruction reduction may be spread to coal chemical processes and other industrial systems. (C) 2020 Elsevier Ltd. All rights reserved.