Assessment of transient and steady-state behavioral dynamics in polymer electrolyte membrane and alkaline electrolysis for hydrogen generation

This study systematically evaluates alkaline electrolysis (AE) and polymer electrolyte membrane (PEM) systems under steady-state and dynamic conditions, including cold starts, ramp-up/down, and high-frequency transient monitoring. PEM electrolysis demonstrated faster initiation (40 s vs. 175.4 s) and cold start times (<10 min vs. 210 min) compared to AE. While both systems showed 15–16 % higher thermoneutral voltage efficiency than reversible voltage efficiency, AE consumed less energy (4.2 vs. 5 kWh/Nm³). AE also maintained more stable hydrogen purity (>99.9 %) than PEM. The novelty lies in high-resolution dynamic analysis, employing normalized change rate thresholding and filtering to evaluate electrical, thermal, and mass transfer responses. Findings highlight trade-offs between efficiency, flexibility, and gas purity, suggesting hybrid AE-PEM systems could optimize performance. This work provides critical insights for design, optimization, and policy, advancing the integration of electrolysis with renewable energy systems. The detailed comparison of dynamic parameters fills a key gap in understanding electrolyzer behaviour under real-world operational conditions.