A PEM electrolyzer system for hydrogen production is established and the corresponding efficiency is derived. Based on semi-empirical equations, thermodynamic-electrochemical modeling of water splitting reaction is systematically carried out. It is confirmed that the Joule heat resulting from the irreversibilities inside the PEM electrolyzer is larger than that needed in the water splitting process in the whole region of the electric current density. Some alternative configurations are designed to improve the overall performance of the system and the corresponding expressions of the efficiency are also derived. The curves of the efficiency varying with the electric current density are presented and the efficiencies of the different configurations are compared. The optimally operating region of the electric current density is determined. The effects of some of the important parameters on the performance of the PEM electrolyzer system are analyzed in detail. Some significant results for the optimum design strategies of a practical PEM electrolyzer system for hydrogen production are obtained.Fujian Natural Science Foundation; Fundamental Research Fund for the Central Universities, People's Republic of China [201112G006
