Integration of underground coal gasification with a solid oxide fuel cell system for clean coal utilization

Underground coal gasification (UCG) is a promising clean coal technology. Typically, the syngas obtained from UCG is used for power generation via the steam turbine route. In the present paper, we consider UCG as a hydrogen generator and investigate the possibility of coupling it with a solid oxide fuel cell (SOFC) to generate electrical power directly. We show, through analysis, that integration with SOFC gives two specific advantages. Firstly, because of the high operating temperature of the SOFC, its anode exhaust can be used to produce steam required for the operation of UCG as well as for the reforming of the syngas for the SOFC. Secondly, the SOFC serves as a selective absorber of oxygen from air which paves the way for an efficient system of a carbon-neutral electrical power generation from underground coal. Thermodynamic analysis of the integrated system shows considerable improvement in the net thermal efficiency over that of a conventional combined cycle plant.