Techno-thermodynamic investigation of pressurized ammonia-fueled SOFC systems for co-production of electricity and hydrogen

This study presents the techno-thermodynamic optimization of pressurized ammonia-fueled solid oxide fuel cell (SOFC) systems for the co-production of electricity and hydrogen and establishes an efficiency–hydrogen trade-off within realistic balance-of-plant (BoP) configurations. A rigorously calibrated SOFC stack model, validated against literature data and in-house experiments, was integrated into a pressurized system layout comprising staged air compression, a recuperative heat exchanger, a combustor, and a hydrogen separation unit. A parametric study covering pressures from 2 to 10 bar, operating temperatures between 700 and 800 °C, fuel utilization factors from 0.4 to 0.8, and current densities from 1000 to 5000 A/m² was conducted to quantify the efficiency–hydrogen trade-off under BoP conditions. The results demonstrate that increased pressurization benefits hydrogen recovery but reduces net electrical efficiency owing to heightened air-compression work; however, the combined electricity–hydrogen efficiency peaks at approximately 69% at 6 bar. Furthermore, larger stack temperature differentials (80–100 °C) reduce cathode airflow, thus improving both hydrogen yield and electrical efficiency, whereas higher stack temperatures (750–800 °C) primarily improve electrical performance; moderate current density, in turn, ensures balanced coproduction. By contrast, low fuel utilization optimizes hydrogen production. Consequently, a balanced coproduction regime emerges near 5 bar with moderate fuel utilization and current density, yielding electricity and hydrogen at practical efficiency levels. These findings delineate realistic operating windows and offer clear guidance for dispatchable ammonia-SOFC systems for flexible, carbon-free energy supply.