Ammonia offers two primary pathways for energy utilization: it can be directly used in fuel cells (FC) for electricity generation or decomposed into hydrogen to power hydrogen fuel cells. However, both approaches present significant technical challenges. Direct ammonia fuel cells face obstacles such as catalyst inefficiencies, ammonia crossover issues, NO emissions during oxidation, long-term operational stability concerns, and prolonged start-up times, particularly in solid oxide fuel cells (SOFCs). On the other hand, ammonia decomposition is an endothermic reaction requiring high temperatures, typically in the range of 850–950°C, achieved using nickel-based catalysts on aluminum oxide. The hydrogen obtained through this process must then be separated before use in fuel cells.
Integrating fuel cells with ammonia-cracking systems can enhance efficiency by utilizing waste heat and a portion of the generated electricity to sustain the cracking process, potentially enabling self-sufficient, auto-thermal operation. This integration can significantly reduce energy costs, minimize material consumption, and lower emissions. However, identifying the optimal process configuration for such systems remains complex and depends on factors such as the fuel cell type, system architecture, and the technology employed for ammonia decomposition and hydrogen separation.
This study focuses expands a previous comparative energy analysis of various technological solutions for integrated ammonia-fueled systems. Using process simulations by Aspen Plus and Aspen adsorption, we evaluate state-of-the-art components to determine the most energy-efficient configurations. Different system designs incorporating low- and high-temperature proton exchange membrane (PEM) fuel cells, along with SOFCs, are assessed based on heat recovery potential and overall energy performance. A sensitivity analysis further examines key parameters, including fuel cell efficiency, heat recovery effectiveness, and hydrogen/nitrogen separation efficiency.