(166c) Challenges in PEM Electrolyzer Meas

Proton Exchange Membrane (PEM) water electrolysis stands out as a leading method for green hydrogen production due to its exceptional efficiency and ability to operate under high differential pressures. At the heart of a PEM electrolyzer lies the Membrane Electrode Assembly (MEA), where water molecules undergo decomposition into hydrogen and oxygen. This presentation will delve into the challenges and future pathways concerning MEA materials, operational aspects, diagnostics, maintenance, and ultimate recycling.

An MEA within an electrolyzer comprises platinum group metal (PGM) catalysts, perfluorosulfonic acid (PFSA) membranes, and additional gasketing materials. The catalyst constitutes a significant portion of the PEM electrolyzer stack's cost. Conventionally, Ir oxide-based catalysts have dominated the PEM electrolyzer industry, but due to their high cost, efforts are underway to reduce catalyst loading and develop more active alternatives. Similarly, the membrane plays a crucial role in the MEA, with various thicknesses such as 5mil and 7mil being utilized. However, thicker membranes contribute to higher resistance, leading to efficiency losses. Hence, reducing membrane thickness has become pivotal for improving PEM electrolyzer performance. Yet, thinner membranes bring challenges like increased hydrogen gas crossover, necessitating efficient gas recombination technologies. Additionally, the high differential pressure operation requires reinforcement layers within the membrane, akin to fuel cell technologies.

The unique characteristics of MEA components demand ultra-pure water inputs, although ensuring this purity can be challenging. Contaminants from plumbing systems and incomplete removal by deionization systems can lead to ion leaching, which in turn poisons the catalysts. Establishing a universal method for identifying and rectifying such issues is imperative for maintaining MEA performance.

MEA degradation over time is inevitable, with an expected lifespan of 80,000 to 100,000 hours. While large-scale PEM electrolyzer applications are still in their infancy, MEA recycling is already a consideration. Despite containing valuable materials such as PGM catalysts and PFSA-based membranes, conventional recycling methods like calcination are suboptimal due to the presence of PFSA membranes. Burning MEAs not only wastes expensive membranes but also poses environmental hazards due to carbon and fluoride emissions. Research efforts are thus focused on catalyst recycling and finding alternative uses for PFSA materials, ensuring a sustainable approach to MEA disposal.