Highly efficient operation of an innovative SOFC powered all-electric ship system using quick approach for ammonia to hydrogen

Abstract

The solid oxide fuel cell (SOFC) power system fueled by NH₃ is considered one of the most promising solutions for achieving ship decarbonization and carbon neutrality. This paper addresses the technical challenges faced by NH₃ fuel SOFC ship power system, including slow hydrogen (H₂) production, low efficiency, and limited space. It introduces an innovative a NH₃-integrated reactor for rapid H₂ production, establishes a safe and efficient all-electric SOFC all-electric propulsion system adaptable to various sailing conditions. The system is validated using a 2 kW prototype experimental rig. Results show that the SOFC system, designed for a target ship, has a rated power of 96 kW and an electrical efficiency of 60.13%, meeting the requirements for rated cruising conditions. Under identical catalytic scenarios, the designed reactor, with highly efficient heat transfer, measuring 1.1 m in length, can achieve complete NH₃ decomposition within 2.94 s, representing a 35% reduction in cracking time and a 42% decrease in required cabin space. During high-load voyage conditions, adjusting the circulation ratio (CR) and ammonia-oxygen ratio (A/O) improves system efficiency across a wide operational range. Among these adjustments, altering the A/O ratio proves to be the most efficient strategy. Under this configuration, the system achieves an efficiency of 55.02% at low load and 61.73% at high load, allowing operation across a power range of 20% to 110%. Experimental results indicate that the error for NH₃ cracking H₂ is less than 3% within the range of 570–700 °C, which is relevant to typical ship operation scenarios. At 656 °C, the NH₃ cracking H₂ rate reaches 100%. Under these conditions, the SOFC produces 2.045 kW of power with an efficiency of approximately 58.66%. The noise level detected is 58.6 dB, while the concentrations of CO₂, NO, and SO₂ in the flue gas approach zero. These findings support the transition of the shipping industry to green, clean systems, contributing significantly to future reductions in ocean carbon emissions.