Thesis work for Master
Polymer electrolyte membrane water electrolyzers (PEMEL) have been identified as a key component in a decarbonized large-scale energy system, as they can produce high-purity hydrogen from renewable electricity sources for the chemical industry or energy storage. However, the long-term durability and performance of PEM electrolyzers remain a major challenge, with degradation being a critical factor that limits their lifespan and efficiency. Recent studies have focused on developing accelerated stress test (AST) protocols for PEM electrolyzers to better understand the conditions and mechanisms that lead to degradation. Especially the reversible rise in cell potential, which in the literature is often regarded as apparent or reversible degradation, must be further investigated to find mitigation strategies for operation.
This work aims to develop an initial model for the reversible degradation effects of PEM water electrolyzers. To validate the model, measurements will be taken on a commercialized test bench equipped with a 7 kW 8-cell stack at the Fraunhofer ICT in Pfinztal. The measurements are part of a larger research project named “hyBit” (hydrogen for Bremens industrial transformation) aiming to find operation strategies for large PEMEL plants. The tests will provide a better understanding of the various degradation phenomena and the recovery of reversible effects across PEMEL stacks. Among other things, the experimental methods will include high-frequency measurement and electrochemical impedance spectroscopy of the stack. The stack must operate continuously during these long-term test protocols. Two test protocols will be used to simulate both static and dynamic operation modes for PEMEL stacks. A model approach must be developed and implemented in Python based on the measurements and scientific literature. Finally, the model will be validated against the measured data.
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