Design for Remanufacturing and Resource Circulation in Proton Exchange Membrane Water Electrolysis Systems Using Sustainability Benefit Ratio.

Proton exchange membrane water electrolysis (PEMWE) is a promising route to low-carbon hydrogen production, but its sustainability remains incomplete unless the electrolyzer itself is designed for circularity. Repeated stack replacement can impose substantial lifecycle burdens because PEMWE relies on resource-intensive components such as iridium-based anodes, fluorinated polymer membranes, and titanium-based stack materials. Here, we investigate the significance of introducing remanufacturing into PEMWE systems from the perspective of design for remanufacturing and resource circulation. Repeated new-manufacturing and repeated remanufacturing scenarios are compared using the Sustainability Benefit Ratio (SBR), a lifecycle-oriented indicator that integrates greenhouse-gas burdens, avoided burdens, and valuation-weighted lifecycle factors into a unified circular-economy metric. The results show that remanufacturing consistently improves the cumulative environmental-economic balance relative to repeated new manufacturing, reduces carbon-footprint-based burdens, and enables repeated circulation of valuable stack-related resources while maintaining comparable hydrogen output. Cost decomposition and sensitivity analysis further reveal that the OER electrode governs the circular value of PEMWE remanufacturing and that its contribution can be translated into practical design targets in terms of catalyst cost, remanufacturing cost, recovery ratio, and electrochemical performance. These findings demonstrate that SBR can serve as a practical design-support tool for quantifying circular-economy value and guiding remanufacturing-oriented PEMWE development.