Integrated reliability and thermodynamic assessment of high-temperature hybrid fuel cell–electrolysis systems

• Integrated FMEA–thermodynamic framework for hybrid SOFC–electrolysis systems. • Air supply module identified as highest-risk component (RPN = 270) • Air-flow increase raises total efficiency to 85.28% but lowers electrical efficiency. • SOEC shows higher water-flow sensitivity than PEMEC in energy performance. High power-generation efficiency and low pollutant emissions demonstrate the potential of fuel cell systems for distributed renewable applications, yet long-term reliability remains a critical concern. A reliability–thermodynamic assessment framework is established by integrating Failure Mode and Effects Analysis (FMEA) with system-level thermodynamic modeling to evaluate operational performance of a hybrid fuel cell–electrolysis system. FMEA identifies the air supply module as the dominant risk source, with the highest risk priority number (RPN) of 270 and additional influence on the thermal box module (RPN = 210), indicating the critical role of air-flow regulation in high-temperature operation. Parametric analysis reveals that increasing SOFC air-flow rate enhances thermal recovery but reduces electrical efficiency, with a maximum electrical efficiency of 60.72% and total energy efficiency of 85.28%, reflecting a trade-off between power generation and heat utilization. For electrolysis operation, increasing inlet water flow significantly reduces hydrogen production efficiency in the SOEC system, with a maximum value of 71.44%, while the PEMEC system exhibits comparatively moderate efficiency variation. Incorporation of subsystem heat losses highlights the importance of evaluating thermal interaction in hybrid configurations. The proposed framework provides guidance for long-term monitoring, operational optimization, and industrial design of renewable-coupled fuel cell systems.