A review on PEM Electrolyzer Modelling: guidelines for beginners

Abstract From a sustainability perspective, a synergy between hydrogen, electricity and Renewable Energy Sources (RES) is particularly attractive. A combination of Proton Exchange Membrane (PEM) fuel cells and PEM electrolyzers provides a back-up system for RES avoiding the intermittency: electrolyzers convert the excess of energy from RES into hydrogen and PEM fuel cells use this hydrogen to convert it back into electricity when it is needed. Models are an essential tool in electrolyzer development because it allows to understand the influence of different parameters on the electrolyzer performance enabling an efficient simulation, design and optimization of electrolyzer systems. Modelling studies have been developed with different degrees of complexity. This review presents a compilation of published models focusing on the main equations used to predict cell voltage, including reversible voltage, activation losses, ohmic losses and mass transport losses. Special sections are devoted to dynamic behaviour, two-phase flow effects and inclusion of thermal effects in model development. Also, a brief description of empirical/semi-empirical models is provided. This review aims to provide the main guidelines for the beginners on PEM electrolyzer modelling and, for this purpose, includes a section with the technology basic principles.