NYK Line, Japan Engine Corporation, IHI Power Systems Co., Ltd., and Nihon Shipyard Co., Ltd. received approval in principle from ClassNK for an ammonia-fueled ammonia gas carrier.
At present, there are no international regulations for the use of ammonia as marine fuel. Therefore, the Consortium have been conducting research and development to ensure that the AFAGC has the same safety features as vessels using existing fuel oil or LNG fuel.
The Consortium conducted a HAZID risk assessment of the safety of using ammonia as marine fuel in anticipation of obtaining approval of an alternative design, which is indispensable for realizing a demonstration operation in fiscal 2026. The Consortium then received an AiP from Japanese class society ClassNK after concluding that safety can be ensured. This is the first time that a risk assessment has been conducted and an AiP obtained not only for a concept but also an alternative design.
Background of AFAGC development
Since ammonia does not emit carbon dioxide (CO2) when combusted, it is expected to be a next-generation fuel that contributes to the global warming measures and is expected to be in demand for mass transportation in the future. In addition, by transporting ammonia as cargo and using it as fuel during voyages, it will be possible to significantly reduce greenhouse gas emissions during voyages.
This initiative is the development of vessels equipped with a domestically produced ammonia-fueled engine, which was initiated in October 2021 by NYK, Japan Engine Corporation, IHI Power Systems Co., Ltd., and Nihon Shipyard Co., Ltd. as part of the Green Innovation Fund Project of the New Energy and Industrial Technology Development Organization (NEDO).
With the goal of early social implementation of next-generation fuel vessels, the Consortium are developing (a) a two-stroke ammonia-fueled engine for vessel propulsion, (b) a four-stroke ammonia-fueled engine for onboard power supply, and (c) a safe and environmentally friendly hull. The Consortium is working together to study the feasibility of construction and commercial operation of the prototype vessel in an integrated manner.
Basic design of prototype vessel completed and AiP obtained
The main design issues when using ammonia as a fuel during development are as follows.
1. It is necessary to combust ammonia stably and operate the engine while increasing mixed combustion rate of ammonia, which is hardly-flammable and has low energy density.
2. Since the combustion of ammonia generates nitrous oxide (N2O: about 300 times the warming potential of CO2) instead of CO2, it is necessary to control the combustion to suppress the generation of nitrous oxide.
3. A design to prevent leakage of toxic ammonia and adequate safety measures in the event of leakage are needed. Safety measures based on risk assessments are necessary to ensure the same level of safety as conventional vessels.
The Consortium have established the development hull design for this project to be an MGC, which is currently common size for marine transportation of ammonia, and have developed and selected main and auxiliary engines and onboard equipment while securing an ammonia-loading capacity equivalent or more than that of conventional vessels. The Consortium have completed the concept design of a prototype vessel that can cope with the above issues through the safe and practical installation of ammonia-fuel-related equipment in the limited space available in the vessel. The equipment layout has been devised, and the Consortium will work on further design optimization.