Hydrogen production by steam electrolysis at intermediate temperature:merits and challenges of PCCEL and SOEL with emphasis on materials aspects

Kurzfassung

The global hydrogen market is expanding rapidly, with demand projected to reach 175 million tons by 2030. In Europe alone, clean hydrogen supply is expected to hit 170 GW and 20 Mt H2 per year, still short of the estimated 30 Mt H2 needed—highlighting a 10 Mt H2 supply gap. This is primarily due to the low-capacity factor of renewables and the high energy demand of current electrolysis technologies. At a given hydrogen production rate, the use of renewable heat or industrial waste heat in the electrolysis process all allows for higher efficiency and reduced specific electricity demand. This makes the high temperature electrolysis technologies especially attractive compared to liquid water electrolysis. Nowadays, if SOEL (Solid Oxide electrolyzer) technologies is the most advanced high temperature technology, PCCEL (Protonic ceramic cell electrolysis) is emerging especially for applications in the temperature range 400 – 600°C. In this contribution, on the basis of the experimental and degradation features of Solid Oxide Cells (SOCs) and Protonic Ceramic Cells (PCCs) we will present some of the key merits and enduring challenges for the two technologies in the perspective of operation at a temperature below 600°C. On the basis of some identified physical limiting processes, we will discuss major directions for future developments to enable scale-up of the technologies.