Abstract:As the sector with the largest greenhouse gas emissions both in China and globally, thermal power generation urgently needs to transition toward "low-carbon utilization of high-carbon resources" under the "dual carbon" goals. This study explores the carbon reduction potential of the emerging industry of underground coal gasification (UCG) for power generation. Based on the context of distributed power generation using UCG coupled with carbon capture, utilization, and storage (CCUS) technology, and considering the geological setting and coal seam conditions of a site in Guizhou Province, a distributed power generation route based on shaftless UCG was developed. This route integrates CO2 capture, compression, reinjection, and reduction reactions. Theoretical calculations and sensitivity analyses were conducted to evaluate the full-lifecycle carbon emission intensities of various resource extraction and power generation models, including: (1) shaftless UCG-gas turbine power generation, (2) shaftless UCG-solid oxide fuel cell (SOFC) power generation, (3) underground coal mining-road/rail transport-coal-fired power generation, (4) natural gas extraction-pipeline transport-gas power generation, and (5) shale gas extraction-pipeline/LNG ship transport-gas power generation. The impact of syngas composition ratios on the carbon emission intensity of UCG-based power generation was also analyzed. The results indicate that natural gas and shale gas power generation models had the lowest carbon emission intensities, followed by the UCG-SOFC model. In contrast, the UCG-gas turbine and coal-fired power generation models exhibited similar and higher carbon emission intensities. For both the shaftless UCG-gas turbine and shaftless UCG-SOFC models, syngas was converted into electricity on-site, thereby eliminating transport carbon emissions. Consequently, these models showed lower pre-power-generation carbon intensities. When CO2 in the syngas was emitted directly without reinjection or utilization, the carbon emission intensities were 1.058 t CO2/(MW·h) and 0.705 t CO2/(MW·h), respectively. Under CO2 reinjection and utilization scenarios, the full lifecycle carbon emission intensities were 0.87 t CO2/(MW·h) and 0.58 t CO2/(MW·h), respectively. By adopting CO2 reinjection and increasing the proportion of effective components in the syngas to over 85%, with H2 accounting for more than 44%, the carbon emission intensity of UCG-based power generation could be significantly reduced, achieving up to a 35.27% reduction. This study highlights the significant potential for further reducing the carbon emission intensity of UCG power generation by analyzing changes in the key factor of syngas composition. These findings provide a more comprehensive demonstration of the competitiveness of the UCG-CCUS integrated power generation model. Given China's current energy endowment and the fact that coal and thermal power are regional pillar industries, this research offers valuable references for energy sector transformation in high-carbon-resource regions. Close-