Evaluating the efficiency of a proton exchange membrane green hydrogen generation system using balance of plant modeling

Abstract

A system model of a proton exchange membrane green hydrogen generation system is developed with the intent of demonstrating the dynamic interactions of the system with varying inputs such as electrolyzer current density and hydrogen pressure. The model includes physics-based modules that are validated with available experimental data for the power electronics, electrolyzer stack, pressure swing adsorption dryer, hydrogen compressor, and cooling circuit components of the system. A single electrolyzer system and multi-electrolyzer system are evaluated with varying operating conditions and multi-stack system operating strategies. Increasing electrolyzer cathode pressure results in an overall increase in specific energy consumption but may allow the use of low-pressure storage without the need for a hydrogen compressor. For a theoretical case study of excess renewable energy generation in Texas, the system achieves an overall efficiency of 46.5 % defined as the efficiency of converting electricity into an equivalent energy content of the produced hydrogen.