Ammonia-fed solid oxide fuel cell-polygen system: Techno-economic analysis and optimization

Ammonia is considered as one of the most promising alternative marine fuels, as high-efficiency energy conversion is crucial in ammonia-to-power pathways. A novel CCHP system is proposed to meet the combined cooling, heat, and power (CCHP) demands of ships. The system integrates solid oxide fuel cells (SOFCs), pumped thermal energy storage, the Kalina cycle, the absorption refrigeration cycle, and batteries. Multi-objective optimizations are performed through parameter and sensitivity analysis employing validated models. The system achieved total electrical efficiency of 69.5 % and net electricity output 97.4 kW, respectively. Additionally, the system provides cooling output of 78.7 kW, and heat output of 11.5 kW. The combined heat and electrical efficiency reaches 77.7 %. Techno-economic analysis uncovered key cost drivers, with the SOFC subsystem, particularly the SOFC stack, as the most expensive. Fuel costs account for the majority of the total expense. Case analysis are performed to compare green and gray ammonia feedstocks showing a higher levelized cost of electricity (LCOE) for the green ammonia-fed system. Furthermore, the imposition of carbon increases the LCOE of gray ammonia-fed systems. Notably, at a carbon tax of $30/ton, the LCOE of the gray ammonia-fed system equals that of the green ammonia-fed system, at $0.176/kWh. This study provides valuable insights into the maritime application of SOFC-based systems and offers comprehensive understanding of their technical and economic feasibility within emerging energy and environmental paradigms.