PROMETEO aims at producing green hydrogen from renewable heat & power sources by high temperature electrolysis in areas of low electricity prices associated to photovoltaic or wind. Solid Oxide Electrolysis (SOE) is a highly efficient technology to convert heat & power into hydrogen from water usually validated in steady-state operation. However, the heat for the steam generation may not be available for the operation of the SOE when inexpensive power is offered (e.g. off-grid peak, photovoltaics or wind). Thus, the challenge is to optimize the coupling of the SOE with two intermittent sources: non-programmable renewable electricity and high-temperature solar heat from Concentrating Solar (CS) systems with Thermal Energy Storage (TES) to supply solar heat when power is made available.

In PROMETEO a fully integrated optimized system will be developed, where the SOE combined with the TES and ancillary components will efficiently convert intermittent heat & power sources to hydrogen. The design will satisfy different criteria: end-users’ needs, sustainability aspects, regulatory & safety concerns, scale-up and engineering issues.

The players of the value-chain will play key roles in the partnership created around the project: from developers and research organizations, to the electrolyzer supplier, system integrator/engineering and end-users. A fully-equipped modular prototype with at least 25 kWe SOE (about 15 kg/day hydrogen production) and TES (for 24 hours operation) will be designed, built, connected to representative external power/heat sources and validated in real context (TRL 5). Particular attention will be given to partial load operation, transients and hot stand-by periods.

Industrial end-users will lead to techno-economic & sustainability studies to apply the technology upscaled (up to 100 MW) in on-grid & off-grid scenarios for different end-uses: utility for grid balancing, power-to-gas, and hydrogen as feedstock for the fertilizer & chemical industry.