EXMAR: preparing to sail using ammonia as a marine fuel

In our latest episode of Project Features, we explored EXMAR’s first ammonia carriers with ammonia-capable engines, as well as the risk assessment journey required to enable the use of ammonia cargo as fuel. Kristof Coppé (Director Fleet Operations & Technical Business Development, EXMAR), and Peter Van de Graaf (Strategic Business Partner, Lloyd’s Register) were joined in conversation by AEA Technology Manager Kevin Rouwenhorst. The recording is available on our website, and you can also download the speaker slides here.

As of March 2026, the AEA tracks about 140 ammonia-fueled vessels in various stages of development. Various small vessels with ammonia dual-fuel four-stroke engines, such as tug boats and supply vessels, have hit the waters in 2023, 2024, and 2026. This cohort includes about 50 ammonia-fueled vessels currently on-order around the world, mostly ammonia carriers and bulk carriers with ammonia dual-fuel two-stroke engines. Ammonia carriers will theoretically be able burn their own cargo, but other vessels will need to bunker the fuel and carry it in a separate tank. By using low-emission ammonia (clean ammonia) as fuel, greenhouse gas (GHG) emissions are reduced by around 90%, compared to diesel.

Click to expand. Low-emission ammonia availability for the maritime sector, from Kevin Rouwenhorst, Project Features Introduction April 2026.

Assuming the ordered vessels will use ammonia as the fuel for all voyages, this represents 1.0 million tons of ammonia fuel demand by 2028. The AEA also tracks low-emissions ammonia projects. Based on the low-emissions ammonia projects that are operational and under construction, 3.6 million tons of low-emission ammonia will be available from coastal & export based projects by the end of 2028. Low-emission ammonia fuel availability will not be a bottleneck for initially scaling the maritime sector.

EXMAR: the first ammonia carriers with ammonia-capable engines

EXMAR is the largest independent shipowner in the Midsize Gas Carrier (MGC) segment for LPG and ammonia transport. Since receiving its first ammonia carrier in 1983, EXMAR has transported a cumulative total of over 100 million tons of ammonia as of 2023. In 2021, the world’s first LPG-fueled Very Large Gas Carriers (VLGCs) for LPG transport were delivered to EXMAR.

Click to expand. Specifications of EXMAR’s ammonia dual fuel vessels. From Kristof Coppé, EXMAR’s NH3 fuelled Gas Carriers (Apr 2026).

EXMAR has ordered four 46,000 cbm capacity MGCs with WinGD dual-fuel ammonia engines at HD Hyundai in South Korea. In April 2026, the first two vessels were named ANTWERPEN and ARLON, with the remaining two vessels set for delivery later in 2026. ANTWERPEN will be delivered at the end of May, with sea trials on diesel fuel already completed. Trials using ammonia are scheduled to start in a few weeks, and will be finalized in early May. The vessels can sail for between 10 and 20 days using the fuel in the two deck tanks of 500 cbm ammonia each. Ammonia from the cargo tanks can be transferred to the deck tanks, allowing for “virtually limitless” sailing.

The four vessels have WinGD ammonia dual-fuel engines (X52DF-A-1.0), built by HD Hyundai Heavy Industries in South Korea. The engines completed their Type Acceptance Test (TAT) and Factory Acceptance Test (FAT) earlier in 2026. Although the first two engines aboard the first two vessels were installed without official FAT, results from the third engine have informed retrofits and adjustments to the first two installations.

Ammonia dual-fuel engines have been developed over the past few years, simultaneously with the other ammonia-fueled vessel items, such as the fuel supply system, ammonia release mitigation, and ammonia gas detection systems. This means there were iterations for the engine design, with improvements implemented in the engines, even during the testing period.

Safety guidelines building on operational experience

Ammonia’s toxicity requires rigorous safety measures, including double-walled piping and adequate material selection, gas detection systems, safety studies (HAZID & HAZOP, dispersion analyses), maintenance procedures and operator training. In this context, EXMAR has collaborated with other organizations to develop rules and guidelines, aiming for equivalent safety of ammonia-fueled ammonia carriers like for diesel-fueled ammonia carriers.

Click to expand. EXMAR’s ammonia training & development program. From Kristof Coppé, EXMAR’s NH3 fuelled Gas Carriers (Apr 2026).

EXMAR has developed an ammonia training & development program, which is a two day training. EXMAR also offers this training to third parties, with Woodside Energy recently completing a training course.

In partnership with UK-based classification society and ship design consultancy Lloyd’s Register and the Belgian Federal Public Service for Mobility and Transport, EXMAR helped develop interim guidelines for the safe use of ammonia cargo as fuel on ammonia carriers. Lloyd’s Register also contributed to the recent AEA Whitepaper on Ammonia Gas Detection.

With the first large ammonia-fueled vessels hitting the waters, operational experience allows for identifying the best standard operating procedures in practice. Furthermore, vessel operators can suggest improvements in for example fuel supply systems for next generation ammonia-fueled vessels, allowing ammonia as maritime fuel to get industry-wide consensus on design principles.

Risk Based Certification for novel vessel designs

Risk Based Certification (RBC) is Lloyd’s Register’s process for managing the approval of novel vessel designs. A risk-based approach is used to demonstrate an equivalent level of safety to that achieved with conventional oil-fueled systems. RBC is typically applied where prescriptive requirements for design and construction do not exist (or only partially exist) and/or where risk assessment is required to satisfy Classification Rules and Statutory Instruments. It provides a structured basis for the classification society and the national regulator (the “flag”) to accept the proposed design.

In practice, the RBC process can be described in five key steps (shown in the diagram below):

• RBC-1. The Design & Safety Statement is essentially a project plan that remains live throughout the project and documents the basis for approval.
• RBC-2. The Risk Assessment, typically using hazard identification techniques, is conducted in a workshop format with the team of experts and people involved in the design and development of the project. This can result in an Approval in Principle (AiP) from the class society.
• RBC-3. Supporting Studies as an outcome of the Risk Assessment, or to address relevant prescriptive requirements from class or statutory.
• RBC-4. The Final Design Assessment, typically or Hazard and Operability Study (HAZOP), to check whether changes or new safeguards introduced since the initial design submission are sufficient to safely operate the vessel for its intended role.
• RBC-5. Identifies the requirements for construction, installation and commissioning of the design that has been informed and revised by the previous stages of RBC and develops the related in-service documentation to facilitate the transfer of knowledge from design through to operations.

Click to expand. The Risk Based Certification Process. From Peter Van der Graaf, RBC – Overview (Apr 2026).

RBC is based on IMO guidance and LR’s experience of how a safety justification can inform the normal rigors of ship classification.

The International Maritime Organization (IMO) issued interim guidelines for the use of ammonia as a maritime fuel in September 2024, and further changes to the IGC Code and IGF Code to enable ammonia as a fuel are anticipated. However, as the first ammonia-fueled vessels entering service are first-of-a-kind (FOAK), a risk-based approach is still required to address unknowns and any gaps in existing requirements, as allowed for in the alternative design process.