The decarbonization of fossil fuel is crucial for balancing energy security and carbon management. Underground coal gasification (UCG) is a promising process because of its potential for mitigating ecological impacts, but its conventional autothermal approach with oxygen injection still generates substantial CO 2 . By utilizing thermal plasma to simultaneously provide heat and highly reactive species, can enable rapid coal seam heating and drive directed carbon-reduction pathways without carbon combustion, thereby effectively mitigating CO 2 generation. Experimental results demonstrate that, plasma-driven underground coal gasification (PUCG) initiates within 1 min, producing >94% effective gas and reducing CO 2 concentration by over 86%. Under plasma treatment, aromatic clusters in coal undergo cleavage and recombination into longer, more planar polycyclic assemblies, then carbon defect sites develop on these aromatic clusters, driving the carbon structure toward a more reactive state. The carbon defects serve as attack sites for reactive species, promoting the formation of oxygen-containing functional group (C O ). The activation energy for the reaction between a coal model compound and OH· species to form syngas is only 27.65 kJ·mol −1 . Compared with coal gasification by ground-state water, the activation energy is reduced by more than 80%. Therefore, PUCG offers a promising novel pathway for low-carbon transition of coal-based energy. • A novel in-situ enhanced coal seam gasification system via plasma for H 2 production • Plasma-driven gasification achieves >94% effective gas with >86% CO 2 reduction • Active carbon sites are continuously generated under conversion • Reactive oxygen-containing functional group (C O ) formed under plasma conditions • Activation energy for gasification is reduced by over 80%
Qi et al. (Mon,) studied this question.