Modeling of advanced alkaline electrolyzers: a system simulation approach

A mathematical model for an advanced alkaline electrolyzer has been developed. The model is based on a combination of fundamental thermodynamics, heat transfer theory, and empirical electrochemical relationships. A dynamic thermal model has also been developed. Comparisons between predicted and measured data show that the model can be used to predict the cell voltage, hydrogen production, efficiencies, and operating temperature. The reference system used was the stand-alone photovoltaic-hydrogen energy plant in Jülich. The number of required parameters has been reduced to a minimum to make the model suitable for use in integrated hydrogen energy system simulations. The model has been made compatible to a transient system simulation program, which makes it possible to integrate hydrogen energy component models with a standard library of thermal and electrical renewable energy components. Hence, the model can be particularly useful for (1) system design (or redesign) and (2) optimization of control strategies. To illustrate the applicability of the model, a 1-year simulation of a photovoltaic-hydrogen system was performed. The results show that improved electrolyzer operating strategies can be identified with the developed system simulation model.