Temperature assisted water electrolysis.


The TEMPEL project is developing new materials for medium-temperature electrolysis (MTE) for hydrogen production in the range of 150 to 400 °C. This range offers thermodynamic efficiency gains combined with more favorable electrode kinetics compared to conventional water electrolysis. The TEMPEL project aims to understand the fundamentals and capabilities of medium-temperature (100-400 °C) electrolysis by developing thin-film ionic conductors integrated into MEAs and demonstrated at the single cell level.


The future energy system is based on renewable sources for the supply of electricity, heat or fuels and will require an interconnected system of H2-based energy carriers and adequate technologies, capable of converting energy vectors in the most efficient way. Green H2 production is key in transition path 3 of the VLAIO/Deloitte study[1], i.e. its supply needs to triple by 2050, while the Hydrogen Council even estimates a 10-fold increase[2].  TEMPEL aims at producing electrolytic H2 assisted by heat delivered at 150 to 400 °C,  increasing the system’s electrical efficiency. The process temperature affects the electrolysis’ entropy contribution (TΔS) by turning heat almost equivalent to electric energy (fig.1). This is a very attractive value proposition, since such utilization can be more CO2-friendly than converting heat to electricity (e.g. via ORC) or recover residual heat for process heating.

Innovation goals

High-temperature electrolysis (HTE) is setting its first steps into (subsidized) commercialization, operating from 600 to 850°C, but faces serious material and design challenges, causing its lifetime (<10 khrs) to be much lower than of LTE (>40 khrs), inherent to this high-temperature operation.

TEMPEL develops medium-temperature electrolysis (MTE) that already offers thermodynamic efficiency gains, suppressing OPEX significantly,   and bypasses the material degradation intrinsic to HTE.

The major hurdle to tackle is that no electrolyte materials with sufficient conductivity exist in this temperature range. TEMPEL seeks to develop  key enabling material here and answer integration challenges  with advanced synthesis processes. MTE provides opportunities within different sustainability strategies in the process industry, such as residual heat valorization (potential of 180 TWh at 200 – 500 °C in EU), green heat conversion from CST and exothermic heat upgrading from CO2 hydrogenations, in the context of Power-to-X.

[1] Naar een koolstofcirculaire en CO2-arme Vlaamse industrie, Deloitte (2020)

Project details

Project type
ESI Project
Research trajectory
Project status
Approved on
Project date
€2 994 346

Project Partners