Life-Cycle Exergy Evaluation of Power Generation from Underground Coal Gasification with CCS

Under the carbon neutrality context, underground coal gasification combined cycle (UGCC) power generation with carbon capture and storage (CCS) technology can effectively mitigate climate change and reduce pollutant emissions. However, due to the complexity of the UCG process and significant fluctuations in syngas composition, the overall power generation efficiency of the plant may be affected to some extent. Existing studies have predominantly focused on single-link energy efficiency analysis, with a lack of full life-cycle resource–environment synergistic evaluation based on the extended exergy analysis framework, and comparative sustainability research between UGCC and integrated gasification combined cycle (IGCC) systems remains inadequate. Accordingly, this study establishes an exergy Life-Cycle Assessment model for UGCC power plants based on Aspen Plus, systematically evaluates the resource utilization rate and environmental sustainability index, identifies key influencing factors, and conducts a comparative analysis with IGCC power plants. The results indicate that the comprehensive sustainability performance of UGCC power plants is significantly enhanced after CCS retrofitting, with exergy efficiency reaching 37.56% at an oxygen-to-coal ratio of 0.6 and a water-to-coal ratio of 0.1; compared with IGCC, UGCC demonstrates a superior resource utilization rate but relatively weaker environmental sustainability; and the underground gasification unit is the critical link affecting exergy efficiency. This study offers a new perspective for sustainability assessment of energy systems and provides theoretical support and technical reference for the construction of a low-carbon reliable supply system in the power industry, thereby facilitating the implementation and refinement of a novel sustainable energy system.