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Solid Oxide Cell (SOC) technology is considered as an efficient electrolysis technology to produce hydrogen at large scale. It can also operate in fuel cell mode using different fuels (carbon-based or non-carbon based like ammonia), and in reversible mode. Though proofs-of concept have been achieved at different relevant scales for those operating modes, some R&D works still need to be performed to improve performance, durability and cost. Improved and upscaled cells and stacks need to be developed, with a methodology combining multiscale and multiphysics modelling, electrochemical characterization in relevant conditions and advanced post-test analysis. Their integration into modules made of several stacks is also a stepping stone in order to reach multi-MW electrolysers. CEA is working on the whole value chain of SOC technology, from cell development and optimisation to module design and operation through stack upscaling. Recent achievements on those aspects will be presented.

Solid oxide cell technology is currently experiencing a rapid industrialization phase. To investigate operational strategy, CEA/LITEN has designed and constructed its first multi-stack reversible solid oxide cell (rSOC) module. While it is able to host four of CEA’s standard 25-cell stacks, the present work reports on preliminary validation results obtained in a 2-stack configuration. Thermal losses have been quantified and identified. While the hotbox is showing high performances, the overall losses increased twofold when taking into account pass-through piping and current connections. Module fluid distribution was verified to be homogeneous, and does not affect nominal stack operation. A durability test of more than 2 kh is presented. Over the first 1.1 kh, the stacks behavior was compared to that of a stack previously operated on a test bench. The remarkable similarities indicate adequate control of the module. Finally, a detailed analysis of the recorded efficiency was conducted.