Development of a Versatile and Reversible Multi-Stack Solid Oxide Cell System Towards Operation Strategies Optimization

Solid oxide cell technology is currently rapidly industrializing. To investigate operational strategies, CEA-Liten has designed and assembled a four-stack reversible solid oxide cell (rSOC) toolbox system. Each stack comprised 25 cathode-supported cells with a 100 cm 2 active area, amounting to a nominal electrolysis module power of approximately 13 kW DC at −1 A cm −2 . Most of the present work reports on preliminary functional validation carried out in a two-stack configuration. Thermal losses have been quantified and their sources identified. While the hotbox is showing high intrinsic performances, the overall losses increased twofold when pass-through piping and current connections are taken into account. Module fluid distribution was verified to be homogeneous, and did not affect nominal stack operation. A test sequence of 3.5 kh is presented. Over the first 1.1 kh, the stacks behavior was similar to that of stack tested on a bench, indicating adequate control of the system. However, continued testing highlighted that stack degradation was significantly increased. A detailed analysis of efficiency was then conducted after thermal stabilization and in the nominal four-stack configuration. A maximum efficiency of 79% LHV was recorded when steam generation was excluded.