(62c) Analysis and Dynamic Modeling of Large-Scale Green Hydrogen Production Via Water Electrolysis

Hydrogen is a vital component of sustainable energy systems and can serve as a renewable resource when produced via water electrolysis powered by renewable electricity. However, electrolyzers face operational challenges under variable power conditions, such as fluctuations from wind, tidal, or solar sources. This study introduces newly developed unit operations models in HYSYS and Aspen Plus for simulating the operation of large-scale electrolyzers, specifically Alkaline (AEC) and Proton Exchange Membrane (PEM) types, under both steady-state and dynamic conditions.

Rigorous models of AEC and PEM electrolyzers have been constructed, grounded in detailed mole and energy balance equations at the anode, cathode, and membrane, and incorporating pressure-flow correlations, water transport across the membrane, and gas crossover phenomena. Cell voltage calculations account for open-circuit voltage and various over-potentials. The model enables an in-depth analysis of electrolyzer stack behavior across a range of conditions (e.g., variable power, duty cycle, feed flow, and pressure), supporting integration with renewable energy systems for the design, analysis, and optimization of sustainable energy solutions. This study highlights the dynamic interactions within an electrolyzer and underscores the necessity of the proposed formulations that separate ancillary functions. Furthermore, the simulator predicts key performance metrics—hydrogen production rate and purity, efficiency, temperature, and more—under practical, large-scale scenarios. This analysis explores the potential benefits of large-scale electrolyzer systems integrated with renewable energy sources in real-world applications.