Degradation-aware supervisory control of PEM water electrolysers under renewable operation: Joint current–temperature optimisation for lifetime-LCOH trade-offs

PEM water electrolysers (PEMWEs) are key in Power-to-X, but dynamic renewable operation accelerates degradation, reducing lifetime and increasing the levelised cost of hydrogen (LCOH). This paper presents a control-oriented, simulation-based single-stack PEMWE model integrating electrochemical, thermal, degradation, and auxiliary dynamics within a hierarchical supervisory control framework. Using hourly Danish wind-power and spot-price data, load-following, price-aware, degradation-aware, and lifetime-aware strategies are compared under joint current-density and temperature optimisation. The degradation-aware strategy achieves the lowest LCOH, 10%–22% below strategies without degradation awareness, with the second-longest lifetime; maximising lifetime alone yields no systematic cost advantage. The comparatively lower hydrogen production is recoverable: a 25% higher hydrogen selling price yields 37% more lifetime production at 1.3% higher LCOH. Under wide Monte Carlo parameter uncertainty, the degradation-aware strategy remains cheapest in 60% of realisations. Restricting the degradation-aware strategy to current-density optimisation requires ∼ 14% higher LCOH at comparable lifetime, thereby demonstrating temperature optimisation’s value.