Comparative analysis of the thermodynamic performances of solid oxide fuel cell–gas turbine integrated systems for marine vessels using ammonia and hydrogen as fuels

Abstract

To mitigate environmental issues and implement energy management strategies, hydrogen is emerging as the most promising and sustainable energy source to help achieve decarbonization targets and meet world energy demands. However, hydrogen poses significant storage and transportation challenges due to its low volumetric and gravimetric density. Hence, ammonia is a potential candidate for a hydrogen storage medium because it contains 17.65% hydrogen by weight, and its volumetric hydrogen density is 45% higher than that of liquid hydrogen. In the maritime sector, these available fuels of ammonia and hydrogen are utilized via internal combustion engines, fuel cells, and gas turbines, which are employed on board ships. This study investigates the possibility of using ammonia and hydrogen as fuels for Solid Oxide Fuel Cells (SOFCs). A combined SOFC-Gas Turbine (GT) system was proposed to generate power for marine propulsion plants. This system was designed and modeled with support from Aspen HYSYS V.12.1. Thermodynamics performances of the proposed system were analyzed using the first and second laws of thermodynamics. The energy efficiencies of direct ammonia and hydrogen SOFCs were 60.96 and 64.46%, respectively. The energy efficiencies of the combined systems increased by 12.37 and 13.97% when using ammonia and hydrogen as fuels, respectively, compared with that of single SOFC systems. The exergy destruction of the primary components with each fuel was examined. Furthermore, a parametric study was performed to select the most suitable fuel utilization factor for the system. This analysis proved that ammonia has the potential as a hydrogen carrier and that waste heat recovery is an effective method to improve the thermodynamic performance of an SOFC system.