Analysis of Unbalanced Pressure PEM Electrolyzer for High Pressure Hydrogen Production

Abstract

Proton exchange membrane (PEM) electrolyzer is a promising technology and likely to be an important hydrogen generator. The ability to produce high purity hydrogen and deliver it at relatively high pressure is an important advantage of the PEM electrolyzer technology. In this work, the high pressure PEM electrolyzer without the need for external compression is studied. The simulation of the electrolyzer is performed based on an electrochemical model with consideration of hydrogen permeation. The effect of cathode pressure and membrane thickness on electrolyzer performance is studied. The explosion limit of a hydrogen-oxygen mixture in the anode is also taken into consideration. The electrochemical compression shows advantage in term of delivering hydrogen at high pressure with having less effect on performance and low power requirement. The increase of cathode pressure slightly affects the electrolyzer performance. The high pressure operation at the cathode and the use of thin membranes cause hydrogen crossover from the cathode to anode, especially at high current density operation.