Modeling and multi-objective optimization of an ammonia-fueled protonic ceramic fuel cell/sweeping gas membrane distillation hybrid system for cogeneration of power and freshwater

Abstract This study proposes and investigates a hybrid system that couples an ammonia-fueled protonic ceramic fuel cell (NH 3 -PCFC) with sweeping gas membrane distillation (SGMD) to co-produce electricity and freshwater. A comprehensive steady-state model is developed, incorporating ammonia decomposition kinetics, NH 3 -PCFC electrochemistry, and detailed heat- and mass-transfer within the SGMD module. The NH 3 -PCFC and SGMD submodels are independently validated against published data, providing support for the credibility of the coupled modeling framework. Baseline simulations indicate that the hybrid system achieves a maximum power density of 3,868.26 W m −2 and an overall energy efficiency of 49.2 %, evidencing a clear synergy between electrochemical conversion and waste-heat-driven desalination. Parametric studies indicate that higher operating temperature and thinner electrolyte significantly enhance power output, while hydrogen and air utilization ratios strongly influence system efficiency and exergy destruction. Moreover, increasing SGMD membrane porosity effectively improves freshwater productivity and thermodynamic performance. Resolving the intrinsic trade-off between power density and energy efficiency, a multi-objective NSGA-II optimization delivers a compromise solution with a power density of 6,732.62 W m −2 and an energy efficiency of 51.4 % under balanced operating conditions. The findings indicate the potential feasibility of NH 3 -PCFC/SGMD cogeneration and provide design guidance for applications in remote, maritime, and resource-limited settings.