Critical iridium demands arising from global expansion of proton exchange membrane electrolysis

Abstract Proton exchange membrane electrolysis (PEMEL) is a key technology for producing green hydrogen, but its scalability is limited by the use of scarce materials, particularly iridium. Iridium oxide, the preferred anode catalyst in PEMEL, offers exceptional stability but is produced only as a by-product of platinum mining, with annual output around 7.5 tons. This study estimates future iridium demand for PEMEL under various global deployment scenarios and technological advances. Results show that meeting net zero targets will require both significant improvements in catalyst efficiency and access to roughly 30% of global iridium production annually. Supply shortages could arise as early as 2030, earlier than previously anticipated. The analysis also reveals that long-term iridium needs beyond 2040 are significantly underestimated. These findings underscore the urgent need for innovation in material efficiency and recycling, and the importance of integrating resource constraints into energy policy and technology planning to ensure a sustainable hydrogen transition.