A Real-Time Method for Estimating Current Efficiency in Alkaline Water Electrolysis Stacks Using Low-Power and Operational Data

Abstract

Real-time current efficiency estimation is critical for accurate hydrogen production in alkaline water electrolysis (AWE) systems, particularly in renewable energy-driven scenarios where current fluctuations are frequent and rapid. Traditional methods, such as hydrogen storage tanks and flow meters, face significant limitations. Hydrogen storage tanks require specialized construction, safety measures, and long stabilization times, while flow meters, despite their fast response, involve high initial investment and maintenance costs. To address these challenges, we propose a novel method based on a simplified equivalent circuit model (ECM) for AWE stacks. The key parameter, manifold shunt resistance, is derived from voltage-current data in the low power range and dynamically adjusted based on real-time operational parameters. This approach enables real-time current efficiency estimation without additional equipment, providing timely and accurate data for gas production calculations and system optimization. Experimental validation on a \SI{1000}{\text{N}\cubic\meter\per\hour} AWE stack demonstrates the method's effectiveness, with an estimated current efficiency of \SI{75.2}{\percent} closely matching the measured value of \SI{72.0}{\percent} at \SI{6000}{\ampere}. Compared to traditional methods, the proposed approach significantly reduces costs, eliminates gas accumulation time, and provides real-time monitoring capabilities, offering a practical solution for large-scale AWE systems, especially in renewable energy applications.

Keywords: alkaline electrolysis, current efficiency, shunt current, equivalent circuit model, realtime monitoring