Sustainability evaluation of a PEMFC system for coalbed methane recovery based on life cycle assessment and emergy analysis

To promote the sustainable development of clean energy, a novel integrated system coupled coalbed methane recovery and proton exchange membrane fuel cell (PEMFC) is developed. Life cycle assessment (LCA) and emergy analysis model are established to analyze sustainability of the proposed system. The parametric analysis is performed to assess the effects of the reforming temperature, steam carbon ratio and current density on the emergy performance. The LCA results indicate that the construction phase has the most significant impact on system sustainability, accounting for 51.65%. Reducing the use of stainless steel and copper in the construction phase and improving the recycling process in the recovery phase can help improve the sustainability performance. The emergy analysis results show that the total emergy consumption of the system is 8.53E+16, the use phase accounted for 55.8%, the construction phase accounted for 43.8%, and the recovery phase only accounted for 0.4%. Parametric analysis shows that the emergy savings ratio increases by 7.11% as the reforming temperature is 800 degrees C. The emergy sustainability index ranges from 3.04 to 4.45 with great sustainability performance, as the increase of steam carbon ratio. The system has low environmental load and high sustainability when the current density is close to 1. This research will help improve the sustainability evaluation system of the energy system and promote the sustainable development of clean energy.