Efficient solid oxide fuel cell system could power ships with ammonia-derived hydrogen

In the global quest for sustainable maritime solutions, a study led by researchers from the China–UK Low Carbon College at Shanghai Jiao Tong University, in collaboration with the Energy Institute at University College London and the School of Mechanical Engineering at Shanghai Jiao Tong University, has unveiled an innovative solid oxide fuel cell (SOFC) system powered by ammonia (NH₃) for all-electric ships.

This research, published in Frontiers in Energy, offers a highly efficient and environmentally friendly approach to ship propulsion, addressing the urgent need for decarbonization in the shipping industry.

As the world’s leading maritime nations strive to develop advanced green marine power systems, SOFCs have emerged as a promising technology due to their high efficiency and fuel adaptability. The International Maritime Organization has set ambitious targets, aiming for more than 60% of newly constructed ships to utilize NH₃ or hydrogen (H₂) by 2060.

NH₃, being inexpensive, nonflammable, and easily storable and transportable, presents a compelling alternative to traditional fuels. Its use in SOFCs eliminates the issues associated with carbon deposition and fuel reforming, making it a key player in the transition to green and low-carbon shipping.

The study tackles the technical challenges of NH₃ fuel SOFC ship power systems, including slow hydrogen production, low efficiency, and limited space. The researchers introduce an innovative ribbed catalytic-combustion integrated ammonia cracker (IAC) for rapid hydrogen production, which is crucial for efficient NH₃ decomposition into high-concentration H₂. The system is designed to be adaptable to various sailing conditions and is validated using a 2 kW prototype experimental rig.

The NH₃-fueled SOFC system is designed for a target ship, with a rated power of 96 kW and an electrical efficiency of 60.13%, meeting the requirements for rated cruising conditions. The IAC, measuring 1.1 meters in length, achieves complete NH₃ decomposition within 2.94 seconds, representing a 35% reduction in cracking time and a 42% decrease in required cabin space. The system’s efficiency can be further optimized by adjusting the circulation ratio (CR) and ammonia-oxygen ratio (A/O) under high-load voyage conditions.

The experimental results are striking. 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, demonstrating the system’s minimal environmental impact.

This research not only provides a technical breakthrough in the development of NH₃-fueled SOFC power systems for ships but also supports the shipping industry’s transition to green, clean systems. The findings contribute significantly to future reductions in ocean carbon emissions, aligning with global efforts to combat climate change. The innovative IAC and the efficient SOFC system offer a practical and efficient solution for the decarbonization of the maritime sector, paving the way for a sustainable future in shipping.

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