The International Maritime Organization’s (IMO’s) strengthened GHG strategy has set the decarbonization pathway for shipping, with the ultimate goal of achieving net-zero emissions by 2050. Together with new EU regulations, these will be important drivers for decarbonizing international shipping. Expectations from cargo owners and financial institutions also continue to drive ship decarbonization with increased requirements on transparency and reporting of emissions throughout the supply chain.
Given their long lifespan, ships should be prepared for the introduction of future regulations putting a cost on emissions and limitations on the GHG intensity of fuels.
Hydrogen and ammonia, used in internal combustion engines or fuel cells, are expected to be important in the necessary fuel transition towards 2050, even though there are challenges related to technology readiness, fuel availability, and cost. We have recently seen the deliveries of the first hydrogen-fuelled newbuilds and the orders for the first ammonia-fuelled ships, marking their introduction as marine fuels. DNV is the first classification society to have classed a ship fuelled by liquefied hydrogen and to have certified an oceangoing vessel fuelled by ammonia.
This paper outlines how DNV can assist shipowners in obtaining approval for ammonia- and hydrogen-fuelled ships in today’s immature regulatory landscape. Further, it describes the efforts required by maritime stakeholders to safely introduce ammonia and hydrogen as marine fuels and to progress towards their widespread use. We also consider what it takes to enable seafarers to operate ammonia- and hydrogen-fuelled ships safely.
Safety and approval
Both hydrogen and ammonia have properties that introduce new safety challenges, triggering the need for increased focus on safety in ship design, construction, and operation.
Ammonia has been transported and used as a refrigerant at sea. However, introducing ammonia as marine fuel creates toxicity challenges related to bun- kering, onboard storage, supply and consumption. These challenges may vary depending on ship type and bunkering location.
Hydrogen has a long history of use in a wide variety of industries other than maritime, and the majority of hydrogen today is used in fields like oil refining, ammonia production, and methanol production. Understanding hydrogen and its safety-related properties in a maritime context will be key for its safe and efficient introduction as a ship fuel. A key challenge is to avoid the chain of events that can lead to an explosion, from which the potential consequences can be severe.
Obtaining approval for ammonia- and hydrogen-fuelled ships
There are currently no detailed and prescriptive IMO regulations to support Flag State approval for vessels using hydrogen or ammonia as fuel. The IMO approved the first version of non-mandatory interim guidelines for ammonia in late 2024 and will continue developing similar hydrogen guidelines in 2025. The additional efforts to arrive at mandatory regulations are expected to take years. Given an accelerated development process, the earliest opportunity for new mandatory regulations in the IGF Code is 2028.
Meanwhile, the IMO provides a risk-based approval methodology for new fuels and technologies where the safety level must be demonstrated to be equiv- alent to that of a conventional oil-fuelled ship. The approach is commonly referred to as the alternative design approval process (ADA). The shipowner will typically have a more prominent role in the ADA compared to a conventional newbuild project, and close interaction between the owner, designer, shipyard, Flag Administration and Class is required.
DNV has the expertise and class rules for ammonia- and hydrogen-fuelled ships
DNV has aimed to develop ammonia and hydrogen classification rules with prescriptive requirements as far as possible, acknowledging that this will ensure increased predictability for owners, designers, and shipyards. Compliance with these rules will suffice to issue the classification certificate for the ship.
Subject to Flag Administration acceptance, the DNV rules can be applied as the Flag Administration’s approval basis or to significantly reduce the complexity of the ADA. DNV can help owners and shipyards in the initial contact with the Flag Administration to obtain necessary clarification regarding the approval scope and process.
Based on our experience from first-mover projects and knowledge gained through numerous risk stud- ies related to concept developments, joint industry projects, and rule development, DNV has gained superior insight into the types of studies that a Flag Administration may require for the approval of ammonia- and hydrogen-fuelled ships. This experience will ease the approval process, reduce uncertainties, and help focus expensive and resource-demanding analyses on the required risk areas.
Streamlining the approval process
Shipping as a global industry depends on regulations and standards that are agreed upon, adopted, and implement- ed internationally. The widespread adoption of ammonia and hydrogen as fuels requires that the IMO provides the maritime industry with a predictable mandatory regula- tory framework. DNV is leading several initiatives aimed at accelerating the regulatory development process for the safety of ammonia- and hydrogen-fuelled ships: the Nordic Roadmap for Future Fuels project ; the European Maritime Safety Agency (EMSA) study investigating the safety of hydrogen as fuel on ships ; the Green Shipping Programme ; the EMSA study on the identification of
specific competencies for seafarers on ships using alter- native fuels and energy systems; and the MarHySafe joint industry project .
Safety is more than rules
– Maturing fuel technologies and ship designs
When new technologies are introduced in shipping, the industry-standard safety level will be established by the approval process between regulators, designers, shipyards and equipment suppliers translating new requirements into workable designs. Developing cost-efficient ship designs without compromising safety is challenging and requires close interaction between all stakeholders.
– Enabling seafarers to operate safely
Operating ships safely using ammonia or hydrogen as fuel will require changes to the safety management system, generate the need for new competencies on board and ashore, and may also affect the organizational set-up.
The International Safety Management (ISM) Code sets clear objectives and requirements for shipboard operations. The entire ship’s Safety Management System (SMS) will be affected by using hydrogen or ammonia as fuel, including normal operation, maintenance, and emergency prepared- ness. Until International Convention on Standards of Training, Certification and Watchkeeping for Seafarers (STCW) courses for seafarers on ships utilizing ammonia or hydrogen as fuels are in place, training on such ships should be developed based on existing resources in consultation with the Flag Administration.
Analysing accidents in other industries helps devise strate- gies to prevent accidents related to hydrogen and ammo- nia systems on ships. One such example is a recent EMSA study that reviewed accident databases for hydrogen-re- lated accidents (EMSA, 2024). Nearly half the incidents analysed were related to human and organizational factors. This emphasizes that training the operating personnel and including fuel-related hazards in the safety management systems will be crucial to preventing future incidents.
Recommendations
DNV has extensive experience in supporting the adoption of alternative fuels and is actively researching safety solutions and developing regulations. In today’s immature regulatory landscape, where the IMO’s risk-based approval methodology applies until new mandatory regulations are included in the IGF Code (in 2028 at the earliest), the following should be taken into consideration:
• Compliance with DNV’s classification rules for ammonia and hydrogen as fuel will suffice to issue the classification certificate for the ship. Subject to Flag Administration acceptance, the DNV rules can be applied as the Flag Administration’s approval basis or to significantly reduce the complexity of the ADA. Early dialogue with the Flag Administration is important to clarify their approval scope and process, identifying any possible additional analysis they may require in their approval.
• Establishing comprehensive training, operating procedures, and a robust safety culture is vital to ensure the ship’s safe operation. DNV has developed a recommended practice on competence related to the use of ammonia as fuel. Further, the guidelines developed by the Maritime Technologies Forum (MTF) on alternative fuel safety management systems can guide the Safety Management System’s updating.
The safe introduction and progress towards widespread adoption of ammonia and hydrogen as fuels require a collaborative and open-minded approach among maritime stakeholders, integrating specific fuel regulations into the IGF Code, maturing fuel technologies and ship designs, and enabling seafarers to operate safely. Although there are obstacles, they are not insurmountable.
