Experimental Results of a 10/40 kW-Class Reversible Solid Oxide Cell Demonstration System at Forschungszentrum Julich

In 2018, a 5/15 kW(DC) reversible solid oxide cell system was developed and successfully operated by Forschungszentrum Julich. Based on the knowledge gained with this first system, an optimized system in the power class of 10/40 kW(AC) was developed afterwards in 2019 that uses the well-established Integrated Module. This module consists of four 20-layer sub-stacks, two heat exchangers and five heating plates. It represents the main components of the system. The basic system layout was retained in general from the previous system and adjusted in accordance with the higher power level, as well as the supporting balance of plant components. The layout of the demonstrator system and its results are described. During the experimental evaluation in fuel cell mode, the system could provide an electrical output power from 1.7 to 13 kW(AC). The maximum system efficiency of 63.3% based on the lower heating value (LHV) could be reached at a system power of 10.4 kW(AC). This operating point was also analyzed regarding the temperature distribution in the stack and efficiency losses. In electrolysis mode, a maximum efficiency of 71.1% (LHV) was achieved with an electrical power input of -49.6 kW(AC). At this operating point, about 11.7 Nm(3) h(-1) of hydrogen are generated. The stack temperature distribution and the efficiency losses are also analyzed for the electrolysis mode. Finally, the potential for the efficiency optimization through higher heat integration in this mode is experimentally evaluated and discussed.