Thermodynamic and Degradation Models of a PEM Electrolyzer, Supported by EIS Analysis

Abstract

The increasing of usage of renewables creates the need of new technologies which can operate intermittently and storage systems which let use the energy not locally. Moreover the EU is going toward a �green� energy system which not allows the usage of fossil-fuel based technologies. In this context electrolyzers are a good choice due to their zero GHG emissions and the possibility to storage energy in hydrogen form, which has a very high energy density. The main problems of this technology are the high costs of initial investments and the degradation of the cells. Due to these latter it is important to have instruments to simulate the degradation mechanisms without wasting real cells. In this work has been developed a system model of a PEM electrolyzer which include electrochemical and thermodynamic behavior of the stack. The System is composed mainly of a stack, an oxygen separator tank and a heat exchanger. Results obtained are studied through sensitivity analysis and validated thanks to experimental results and Electrochemical Impedance Spectroscopy (EIS) analysis. The system model is then integrated with semi-empirical equations used to simulate di�erent degradation phenomena. To validate the degradation model are used graphs of polarization curve and of the overvoltage contributions and thus compared to experimental results.