Modelling and Study of Shunt Currents in an Industrial Alkaline Water Electrolyser With Various Number of Cells in Series

Abstract

Interest in green hydrogen production using electrolysers powered by renewable energy has grown in recent years, driven by applications in energy storage and various industrial sectors. Scaling-up alkaline water electrolyser (AWE) stacks by increasing the number of series-connected cells, and elevating the operating voltage (1000–1500 V) can reduce overall capital cost and improve the efficiency of power converters. However, shunt currents remain a key challenge, preventing scaling-up of AWE, while reducing the energy efficiency, especially under partial load conditions. This study developed an equivalent circuit model of the stack to investigate the impact of shunt currents on a large-scale AWE. The model was verified with measurement data of an industrial AWE system, and the simulations were carried out in the MATLAB/Simulink environment. The main goal of this work was the shunt currents modelling, based on a resistance components network of each cell, considering the geometric design of fluid ports and manifolds, and the presence of gas bubbles in outlet channels at the anode and cathode. Impact of increasing the equivalent resistance of fluid ports was studied across stacks of various lengths, containing a larger number of series-connected cells. The reduction of shunt currents can significantly improve the energy efficiency of AWE systems.