By Ma Dan CCS Wuhan Rules & Research Institute

With the significant advancement of zero carbon emissions target in the shipping industry, alternative fuels play a crucial role as the main force in reducing emissions, especially zero-carbon fuels. Green ammonia is one of the main zero-carbon fuels, and is considered a strong candidate for alternative fuels in the international shipping industry by virtue of its great potential for application to solve medium and long-term decarbonization targets. The establishment and improvement of the rules and standards for ammonia-fuelled vessels is of great significance for the safe and reliable application of ammonia fuel on ships. This paper mainly sorts out and analyzes the current status of the rules and standards for ships using ammonia fuel, which include the International Maritime Organization (IMO), the International Association of Classification Societies (IACS), the International Organization for Standardization (ISO), major classification societies, and national standards (including established and ongoing codes and standards), and proposes the ideas for future construction, with the aim to provide comprehensive technical support for the safe and sound development of ammonia-fueled vessels.

International Maritime Organization (IMO)

In terms of IGF, its main sections PART A-1, PART B-1, and PART C-1 are currently only applicable to natural gas fuel, while the regulations related to ammonia fuel will be developed within the framework of IGF and initially released in the form of interim guidelines. The interim guidelines are to be finalized at the CCC 10 meeting of the Subcommittee on Containers and Cargoes in 2024 and approved at the Maritime Safety Committee (MSC) meeting in 2025. This interim guideline is expected to provide specific provisions on the objectives and functional requirements, risk assessment, vessel design and arrangement, fuel containment system, material and piping design, fuel bunkering, fuel supply, power generation and propulsion system, fire protection, toxicity protection, ventilation, electrical installations, control, monitoring and safety system, manufacturing, process and testing, drills and emergency drills, operation requirements, training, personal protection, etc. The main difference between this interim guideline and the IGF rules is that the requirements related to ammonia fuel toxicity protection are added, while the requirements for fire and explosion prevention are reduced.

In terms of IGC, the requirement to prohibit the use of toxic cargoes as fuel has now been revised to allow ammonia cargoes used as fuel. However, the existing IGC Chapter 16 "Using Cargo as Fuel" only applies to methane cargo, and the relevant technical requirements for ammonia cargo as fuels are currently being discussed and formulated. The relevant draft has been submitted to the CCC 10 meeting, and the technical requirements mainly include: objectives and functional requirements, supplementary guidance to Chapter 16, additional provisions (risk assessment, arrangement of spaces accommodating gas fuel users, fuel supply, ventilation and liquid/gas detection of fuel spaces, combustion equipment). For liquefied gas carriers using ammonia fuel (non-cargo), relevant technical requirements are also being discussed, mainly focusing on the following aspects: (1) how to distinguish between ammonia fuel tanks and cargo holds; (2) requirements for separation between fuel and cargo pipelines; (3) different requirements for ventilation of cargo holds and fuel tanks; (4) personal protective requirements for goods and fuels; (5) different requirements for the classification of hazardous areas for goods and fuels; (6) the impact of requirements related to toxicity areas of ammonia on cargo operation; (7) the risks and related requirements of simultaneous operation of cargo loading and unloading and fuel bunkering.

International Association of Classification Societies (IACS)

IACS established the "Safety Decarbonization Panel (SDP)" in 2022 to be responsible for making research on the standards related to the application of alternative fuels such as methanol, ammonia, hydrogen, etc. on ships and other decarbonization technologies. On the one hand, IACS actively participated in the discussion and preparation of the IMO "Interim Guidelines for Ammonia Fuels", conducted GAP analysis between ammonia fuel and IGF rules in the early stage, and provided feedback to the IMO Alternative Fuel Communication Group. Subsequently, IACS issued technical opinions and relevant positions on the draft of the "Interim Guidelines for Ammonia Fuels" submitted by the Alternative Fuel Communication Group; on the other hand, IACS SDP actively organized and developed unified requirements/interpretations related to ammonia-fuelled vessels. Currently, the formulation and official release of the unified requirement UR H1-Control of Ammonia releases in Ammonia fuelled vessels have been completed. This UR has defined the hazardous ammonia concentration, normal working conditions, abnormal working conditions, and emergency situations of ammonia-fuelled vessels, and puts forward clear and strict control requirements for ammonia release from ammonia-fuelled vessels on this basis. At the same time, IACS SDP has also continuously conducted research on the UR list related to ammonia fuel. In the next stage, the UR that may be prioritized for development is the Design and testing of ammonia treatment system in ammonia fuelled vessels, which aims at proposing relevant technical requirements for the equipment or systems that control the ammonia release concentration.

International Organization for Standardization (ISO)

ISO is committed to developing and promoting various international standards to facilitate international trade and technological cooperation. ISO has mature experience and important role in the development of standards for the application of anhydrous ammonia in the industrial sector. Ammonia fuel is still at the initial stage of application in the shipbuilding industry, and ISO has relatively little involvement in the development of relevant standards in this field, however, considering the prospect of using ammonia fuel for ship decarbonization, ISO is currently developing relevant standards for marine ammonia fuel. At the same time, the relevant standards for the application of anhydrous ammonia in the industrial sector can also serve as a reference.

ISO/WD 23397: Ships and marine technology---Ammonia fuel systems for ships

Marine ammonia fuel system. During the preparation process, this standard will be based on the "Guidelines for Ships Using Ammonia Fuel" (Interim Guideline) developed by the IMO CCC Subcommittee, which will specify standardized terminology and related requirements for ammonia fuel system for ships. This standard will apply to all types of ships using ammonia fuel, except for ships that transport ammonia as cargo.

ISO/DTS 21343: Fuel ammonia---Requirement and Guideline for boilers for power generation---Environmental performance

This standard is in the approval stage and specifies the guidelines for testing of ammonia combustion boiler manufacturers from design to acceptance to meet the required environmental performance. It specifies the testing method, measurement item, assessment method, and test reports for each test, with NOx, NH3, and N2O measured at the combustion chamber outlet during functional testing and at the boiler outlet during acceptance testing. The scope of application is the equipment that meets the following conditions: 1) onshore boilers used for power generation, with an output power of 100MW or above; 2) using ammonia as fuel; 3) boilers with a burner for burning primary fuels.

The above ISO standards being developed can serve as a guidance and reference for the application of ammonia-fuelled vessels. With the gradual introduction of more relevant standards in the future, it will help further improve the safety, reliability, and environmental friendliness of ammonia-fuelled vessels.

Rules of Classification Society

In addition to international organizations including IMO, IACS, ISO, etc., major classification societies also play an important role in the development of the rules and standards for ammonia-fuelled vessels. The classification societies, based on the laws and regulations, technological level, and market demands of their respective countries, have formulated the rules for classification of ammonia-fuelled vessels based on the physical and chemical characteristics and related risks of ammonia fuel, combined with the actual needs of ship safety and environmental protection, which provides clear technical guidance and requirements for the design and operation of ammonia-fuelled vessels, and promotes the development of application technology for ammonia-fuelled vessels.

China Classification Society (CCS) began the R&D of the codes and standards for ammonia-fuelled vessels in 2020. In 2022, it released the "Guidelines for Ships Using Ammonia Fuel". In response to the main risks of ammonia fuel such as toxicity and explosiveness, this Guideline puts forward the safety technical requirements for ship arrangement, material and pipeline design, fuel enclosure system, fuel bunkering, fuel supply, ammonia engine, ventilation, fire protection, explosion-proof and toxic area division, control, monitoring and safety system, personnel protection, ammonia fuel power system preset, etc. based on the risk assessment concept and the relevant technical requirements of natural gas fueled ships within the framework of IGF.

In terms of bunkering, CCS has launched the scientific research project of the "Research on Technical Standards for Ammonia Fuel Bunkering Ships and Operation" in 2024 to mainly carry out the research in two aspects: one is the research on technical standards for ammonia bunkering ships, and the other is the research on technical standards for ammonia bunkering operation. It has carried out research on the technical standards for the arrangement of bunkering vessels, bunkering system, cargo containment system, related monitoring and safety system, personnel protection, evacuation, fire protection system, etc.; as for bunkering operations, it has carried out research on the technical requirements for bunkering modes, bunkering equipment, safety protection, risk assessment, operating procedures, emergency response, etc. The project results are the "Guidelines for Ships Using Ammonia Fuel" and the "Guidelines for Marine Ammonia Fuel Bunkering Operation", which are expected to be released around the end of 2025.

Other major classification societies around the world, such as American Bureau of Shipping (ABS), Det Norske Veritas (DNV), Lloyd's Register of Shipping (LR), Class NK (NK), Bureau Veritas (BV), Registro Italiano Navale (RINA), Korean Register (KR), etc., have also issued the rules or guidelines for ammonia-fuelled vessels in recent years.

National Standards

In terms of national standards, it, to some extent, serves as a reference for the occupational exposure limits for ammonia and the standards for liquefied anhydrous ammonia, the allowable exposure limits for ammonia-fuelled vessels and the determination of ammonia fuel specifications since there is a lack of relevant standards for the application of ammonia-fuelled vessels. Among them, GBZ 2.1 "Occupational exposure limits for hazardous agents in the workplace" stipulates the hygiene requirements, testing and assessment, and control principles for occupational exposure to ammonia in the workplace; GB/T 536 "Liquefied anhydrous ammonia" specifies the requirements, testing methods, survey rules, packaging, labeling, storage, transportation, and safety requirements for liquefied anhydrous ammonia.

In summary, there is a certain foundation for the development of the regulations, rules, and standards related to ammonia-fuelled vessels worldwide, and the corresponding rules and standards have taken shape. However, there are still deficiencies and improvement. In the future, in-depth research needs to be made in the following five aspects: the standards for specifications of marine ammonia fuel; the standards for ammonia fuel bunkering; the standards for testing ammonia fuel power plants (engines, boilers); the standards for design and testing of ammonia fuel supply system; the standards for design and testing of ammonia emission reduction system.