Innovative Solid Oxide Electrolyser Stacks for Efficient and Reliable Hydrogen Production

Relhy is an interdisciplinary project funded by the European Commission within FP7 work programme with clear focus on developpement of novel or improved, low cost materials (and the associated manufacturing process) for their integration in efficient and durable components for the next generation of electrolysers based on Solid Oxide Electrolysis Cells (SOEC). It is specially tailored for

1. Optimisation of novel or improved cell, interconnect and sealing materials
2. Achievement of innovative designs for SOE stacks to improve durability.

As such, it is positionned as a bridge between currently good performing electrolysis cells and their efficient and relialable integration into advanced stacks to pave the way for the production of a new electrolysers generation.

To achieve these goals, the Relhy project is based on the coupled development of instrumented single repeat unitsand stacks and of associated simulation tools (from cell to stack scale). The mixed experimental and simulation approach will be used on several batches of materials :

• To give specifications for novel improved materials and evaluate them, where special attention is paid to material compatibility (between electrodes, electrolyte, coating, interconnects and sealing).
• To propose innovative designs able to overcome the present limiting parameters and to increase stack reliability, durability and performance.

These material and design innovations will be validated at laboratory scale on a 25-cell stack prototype and its competitiveness will be assessed.

Concept

Built on the Hi²H² project results and taking advantage of material research under progress in the on going SOFC projects REAL-SOFC and SOFC600, the Relhy project is positionned as a bridge between between current good performing electrolysis cells and their efficient and reliable integration into advanced stacks to pave the way for the production of a new generation of electrolysers (figure1). It is based on the coupled development of instrumented 1-cell stack also called single repeat units (SRUs) and 5-cell stacks and of associated modelling tools (from cell to stack scale) to be implemented iteratively on promising materials currently under optimisation.

The final target is to increase the reliability and lifetime of SOEC electrolysers by reducing the operating temperature, and because to be used will be cheaper at lower temperature. This technical target should be achievable within the project due to the coupled approach of material development and/or improvement and stack design. Indeed, two main S&T objectives will be addressed simultaneously :

• the achievement of innovative designs for SOEC stacks
• the optimisation of cell, interconnect, coating and sealing materials,

The selected most promising materials and design innovations will be validated by integration at laboratory scale in a 25-cell electrolyser stack prototype that will be operated until the end of the project.

Te competitiveness of this innovative laboratory electrolyser and it's potential integration into a large scale system will be evaluated. The choice of cost effective materials and processes will help decrease the investment and thereby hydrogen production costs.

Since the project is centered on R&D activities, the Relhy multidisciplinary European consortium is merging expertise from two university laboratories and three research centres already recognised for material development and cell production, instrumentation and testing, and modelling (DTU-Risoe, Imperial College, ECN, EIFER and CEA) and also from a fuel cell stack manufacturer that can produce electrolyser stacks (TOFC) and from an energy company (HELION) that can specify the operation conditions and assess the competitiveness of the innovative electrolyser prototype and it's potential integration.