Experimental study on the influence of a PEM water electrolyzer cell's impedance on its power consumption under impaired power quality

Abstract

Impaired power quality is known to increase the power consumption of water electrolysis cells without affecting the hydrogen production rate. Owing to a lack of large-signal dynamic water electrolyzer models, simulations on the topic often consider only the static polarization curve omitting actual cell dynamics. This article aims to bridge the gap by experimentally studying the dynamic phenomena leading to additional power consumption of a polymer electrolyte membrane water electrolyzer cell using sinusoidal current ripple. The effect of ripple amplitude is analyzed with high-speed current and voltage waveform measurements, and the frequency dependence is determined using electrochemical impedance spectroscopy. The complex cell impedance is found to be the only parameter needed for determining the additional power consumption at frequencies above $30\mathrm{Hz}$. This finding enables a simple prediction of additional power consumption for arbitrary current waveforms at frequencies relevant for water electrolyzer rectifiers. At frequencies below $30\mathrm{Hz}$, the static polarization curve begins to influence the voltage waveform of the specific cell, thereby reducing the predictive power of the impedance model. The results prove the use of the static polarization curve is generally inaccurate for modeling water electrolysis power consumption with ripple current.