Modeling High-Power Density Ceria-Based Direct Ammonia Fueled SOFC Stacks for Mobile Applications

SOFCs can be directly run with ammonia (NH3), which is anticipated to play a major role in future renewable energy systems due to its superior conditioning and storage characteristics. Here, we numerically investigate the performance of NH3-fueled SOFC stacks based on a high-power density ceria-based cell design by means of detailed multi-scale simulations on 1D-button cell and 3D-stack level. The model is validated based on electrochemical performance data collected on a Ni-GDC/GDC/SSC-GDC button cell at 500-650 °C. While the decomposition of NH3 at the surface of the Ni-particles is modeled by employing an elementary kinetic framework, a physically-based distributed charge-transfer model is consulted to account for the leakage current across the GDC electrolyte as a function of operation conditions. In this way, the intricate coupling between the mass, heat and charge transport phenomena, as well as the electrochemistry and thermo-catalytic chemistry can be studied on the industrially relevant scale to assist integration into a hybridized power generation system. Model predictions indicate the 120-cell stack running on NH3 to reach a very promising performance in the intermediate-temperature range.