Thermodynamic and parameter analysis of a zero-carbon emission PEMFC system for coalbed methane reforming

In this study, a novel zero-carbon emission proton exchange membrane fuel cell system is developed for coalbed methane recovery. Coalbed methane reforming produces hydrogen, which is supplied to the proton exchange membrane fuel cell subsystem. The carbon dioxide produced in the process is used to produce urea, thus realizing carbon capture and utilization. The system can effectively control carbon dioxide emissions while realizing efficient and clean utilization of coalbed methane. A thermodynamic model for the proposed system is presented. The effects of five key operating parameters, namely steam methane reforming operating temperature, steam to carbon ratio, current density synthesis tower operating temperature and pressure, on the coupled system are analyzed. The results indicate that the total energy efficiency of the proposed system is 41.17 %. The subsystem with the highest energy destruction is coalbed methane recovery with 189.22 kW. The exergy destruction is concentrated in three components, Cathode, Urea synthesis tower, and Ammonia synthesis tower, which accounted for 20.71 %, 17.13 %, and 13.36 %, respectively. Through parameter analysis, the coupled system is currently recommended for steam methane reforming temperature, steam carbon ratio, current density, operating temperature, and operating pressure of 800 degrees C, 3.5, 0.8 A/cm2, 200 degrees C, and 225 bar, respectively. The main results of this study can provide a guiding direction for the development of a sustainable integrated system for hydrogen production from coalbed methane reforming.