Electrolyzer System Modeling - Experimental Testing of PEM Electrolyzer Degradation

Bermudez Blanco, Javier

4. term

Energy Engineering, Master

2026

Green hydrogen can help make energy systems more sustainable. Proton exchange membrane (PEM) electrolyzers - devices that split water into hydrogen and oxygen - are among the most promising ways to produce it. Yet we still know too little about how these systems age and lose performance over time. In this project, I built a Python simulation that links how gases and liquids move through the cell (mass transport) with its thermodynamic and electrochemical behavior. The model includes known degradation mechanisms so it can estimate both day-to-day operation and long-term lifetime. To ground the model in reality, an experimental cell was assembled and operated for 500 hours in a Greenlight test station. Additional measurements came from electrochemical impedance spectroscopy (EIS), which probes resistances and reaction rates, and X-ray diffraction (XRD), which examines material structure. These data were used to build a one-dimensional semi-empirical model. The model's flexibility and robustness were tested by simulating a wide range of operating conditions, including different temperatures, pressures, current densities, and symmetric/asymmetric configurations. A key, counterintuitive result at high temperatures is that membrane thinning can be reduced at low overall pressure, or when the cathode pressure is elevated, by managing oxygen crossover (oxygen passing through the membrane) and oxygen solubility in water. Overall, the model is a practical tool for optimizing operation, predicting lifetime, and studying the underlying phenomena in PEM electrolyzers.

Grøn brint kan gøre energisystemer mere bæredygtige. Proton exchange membrane (PEM)-elektrolysatorer - anlæg der spalter vand til brint og ilt - er blandt de mest lovende teknologier til at fremstille den. Men vi ved stadig for lidt om, hvordan disse systemer nedbrydes og mister ydelse over tid. I dette projekt er der udviklet en Python-baseret simulering, som kobler massetransport i cellen med dens termodynamiske og elektrokemiske opførsel. Modellen indeholder kendte nedbrydningsmekanismer, så den kan estimere både drift fra dag til dag og den langsigtede levetid. For at forankre modellen i virkeligheden blev en forsøgscelle samlet og kørt i 500 timer på en Greenlight teststation. Yderligere målinger kom fra elektrokemisk impedansspektroskopi (EIS), som undersøger modstande og reaktionshastigheder, og røntgendiffraktion (XRD), som ser på materialestruktur. Disse data blev brugt til at opbygge en endimensionel, semi-empirisk model. Modellens fleksibilitet og robusthed blev afprøvet ved at simulere mange driftsbetingelser, herunder forskellige temperaturer, tryk, strømtætheder og symmetrisk/asymmetrisk konfiguration. Et centralt, kontraintuitivt fund ved høje temperaturer er, at membrantynding kan reduceres ved lavt overordnet tryk, eller når katodetrykket er forhøjet, ved at styre ilt-gennemtrængning (oxygen crossover) og iltopløselighed i vand. Samlet set er modellen et praktisk værktøj til optimering, levetidsforudsigelse og forståelse af de underliggende fænomener i PEM-elektrolysatorer.

[This abstract has been rewritten with the help of AI based on the project's original abstract]

Hydrogen ; PEM electrolyzer ; Degradation ; Simulation Model ; Electrolysis

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Bermudez Blanco, Javier:

• Experimental Testing of PEM Electrolyzer Degradation (2025)