The International Bunker Industry Association (IBIA) has released a publication with frequently asked questions surrounding ammonia as a marine fuel, developed by the IBIA Future Fuels Working Group.
As explained, the document forms part of a series of practical resources designed to assist industry stakeholders in navigating the complexities of alternative marine fuels. The questions answered include -but are not limited to- the following:
How is ammonia produced and distributed for bunkering purposes?
The Haber-Bosch process is the most utilised production method for ammonia. It is an energy-intensive process, which combines nitrogen from the air with hydrogen under high pressure (150 to 250 bar) and moderately high temperatures (400 to 650°C). An iron-based catalyst is used. Around 90% of the energy requirements and GHG emissions from the Haber-Bosch process are from the production of hydrogen from gas feedstock.
New pathways to lower-emission ammonia include the use of electrolysis to produce hydrogen (water and electricity feedstocks), but these are not currently deployed at industrial scale. Most of the ammonia produced worldwide is immediately consumed to manufacture fertilizers. In the cases where ammonia is transported offsite, production plants are usually adjacent to the coast and terminal facilities, allowing for straightforward loading onto a ship.
Pipeline, truck, and rail transport are all alternative options for transporting ammonia and are all well-established practices. ammonia can be stored in large tanks (typically 40,000 m³; world’s largest operational tank is 60,000 m³). Most existing large-scale ammonia tanks are also port-adjacent and involved in ammonia imports/exports, so a significant amount of global storage infrastructure already exists that can be leveraged for future bunkering.
What is the bunkering process for ammonia in the shipping sector?
Currently, a variety of bunker options are being explored. These include:
- Ship-to-ship (STS) breakbulk at an anchorage or a jetty-based location
- Shore-to-ship (SHTS) breakbulk at a jetty-based location
- STS bunkering at an anchorage or a jetty-based location
- SHTS bunkering at a jetty-based location
- Truck-to-ship bunkering at a jetty-based location
What are the key considerations for establishing ammonia bunkering infrastructure?
The establishment of ammonia bunkering infrastructure for the maritime industry is subject to several key considerations:
Safety (human and environmental), Due to the toxic and corrosive nature of ammonia, specific equipment and protocols will be required to ensure safe design and enable safe handling, especially at large volumes. There is a range of existing safety systems & technologies that can be deployed.
Handling, Ammonia in its liquid form should be stored at low temperatures (-33°C) and atmospheric pressure. Storage tanks and handling systems must be designed according to specific requirements to prevent leakages and prevent the risk of serious injuries.
Stakeholder engagement, Specialised training on safe handling and the operational aspects is needed for all frontline workers to minimise risks. Transparent, well-communicated, and globally recognised safety protocols are required to gain the trust and acceptance of nearby communities.
Risk management , Strict risk management strategies that include emergency response protocols, coordination with local emergency responders, and adequate training for managing ammonia-related incidents, including spills and leaks.
Insurance – Due to the risks associated with ammonia, port storage, bunkering facilities, and shipping companies will need to collaborate with insurers to share the safeguards and risk assessment put into place.
Are there any challenges or limitations in the supply chain logistics of ammonia for shipping?
Competition for decarbonised ammonia from other industries, including fertilizers and power generation, will be a significant future challenge. Current ammonia transport infrastructure is focused on very specific supply chains, including fertilizers and chemicals manufacturing.
There is no large-scale ammonia bunkering infrastructure currently deployed anywhere in the world, and there is limited juxtaposition between key ammonia production locations and key global bunker hubs. There have been several projects announced to retrofit & expand existing ammonia storage facilities in key locations. As for fuel costs and market development, the current cost of lower-emission ammonia is much higher than conventional ammonia.
As more low-emission production projects reach FID and production scales up, these costs will come down, but the inherent uncertainty in the developing market is a challenge to building the first supply chains. Similar challenges were present during the development of LNG fuel, which began about four decades ago. LNG fuel is now considered a mature, fluid market.
What regulations govern the use of ammonia as a marine fuel? What is the status of regulatory development at the IMO, and what are future timelines?
The “International Code of Safety for Ships Using Gases or Other Low-flashpoint Fuels” (IGF Code) provides an international standard for ships operating with gas and other low flashpoint fuels. But the IGF Code does not presently have prescriptive requirements for a range of alternative fuels, including ammonia. In December 2024, the IMO’s Maritime Safety Committee approved interim guidelines for the safe use of ammonia as a marine fuel. The guidelines are part of an ongoing process to address this regulatory gap and to make amendments to the IGF Code where necessary. Revisions and additions are already anticipated as the first vessels gain sailing experience, and a formal revisit of the guidelines is scheduled for 2027 (possibly late 2026).
Under the International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk (IGC Code), the use of toxic gas cargo for fuel (such as ammonia) is prohibited. Draft interim guidelines for using ammonia cargo as a fuel under the IGC Code are expected to be finalised at the IMO in September 2025, removing this prohibition. These changes are expected to enter into force in July 2026, but IMO member states have proposed that shipowners should be able to voluntarily adopt the anticipated changes, allowing ammonia-fuelled, ammonia-carrying vessels to hit the water before then.
What are the potential economic benefits of transitioning to ammonia in the shipping sector?
Compared to synthetic hydrocarbon fuels, including methane (e-methane, bio-methane) and methanol (e-methanol, bio-methanol), ammonia can be produced at large-scale at a much lower cost. The reason for this is that atmospheric nitrogen (N₂) is abundantly available in the air and available at a significantly lower cost compared to carbon sources such as biomass and carbon dioxide (CO₂). Competition for synthetic hydrocarbon fuels is also a challenge: for example, biofuel adoption in aviation is already affecting its availability for shipping.
What are the costs of adoption of ammonia in the first five years expected to be for shipping operators and owners?
There are several ammonia adoption costs for shipping operators and owners, including: CAPEX requirements, increased fuel costs, crew training, and increased ship management costs.
What are the switching costs of ammonia and how does it affect the future fleets of maritime shipping?
As ammonia-fuelled vessels are in the early stages of adoption, newbuild and retrofit costs are yet to be established. Estimates for ammonia-fuelled vessels range from 16% above the cost of conventional newbuilds to 19–40% for retrofits.
How does the adoption of ammonia affect vessel performance and operations compared to traditional fuels?
Emissions and performance – Engines fed with ammonia as a fuel have an energy efficiency similar to traditional fuels. As ammonia does not contain sulphur, emissions of sulphur oxides are eliminated. Ammonia slip, N₂O, and NOₓ emissions are an environmental and GHG risk and must be fully mitigated.
Bunkering frequency . A switch to ammonia will require more frequent vessel refuelling due to its lower energy content than traditional fuels.
Pilot fuel – The combustion reaction of ammonia can require pilot fuel for ignition. Currently, the most widely used pilot fuel is a small percentage of diesel (5–10%). This can be replaced by alternatives such as biofuel, or even hydrogen-ammonia fuel blends produced by onboard ammonia cracking. Engine manufacturers should be consulted about the latest developments in this space.
Vessel design and impact – Similar to methanol, ammonia has an energy density by volume (and mass) of roughly half that of heavy fuel oil, meaning more fuel storage is required, as are more frequent bunker stops. Ammonia fuel requires a tank-in-tank containment design, so there is also a reduced volumetric energy density in addition to the calorific factor. Other considerations include the need for more complex safety systems, location of crew quarters and mess areas, and containment of all fuel lines from storage tanks to the engine room.
What are the environmental benefits of using ammonia in maritime transportation?
Ammonia does not contain carbon, so there are no carbon dioxide (CO₂) emissions tank-to-wake. Ammonia also does not result in methane slip (CH₄). Ammonia combustion can result in ammonia slip, N₂O, and NOₓ emissions, which are all potential GHG pollutants. NOₓ emissions are mitigated via a Selective Catalytic Reduction (SCR) system. Similarly, N₂O and ammonia slip can be removed by catalytic treatment. Engine makers report excellent emissions results during testing: in some cases, emissions of some species are lower than conventionally fuelled engines (and within regulatory limits) before any exhaust after-treatment is applied.
From a lifecycle perspective, there is a GHG footprint for ammonia fuel. Current ammonia production pathways mean that gas-based ammonia would likely have a similar GHG footprint to conventional maritime fuels. But as lower-emission production pathways scale and the GHG footprint of ammonia fuel reduces, the benefits of using it as a maritime fuel will increase.
In nearly all forecast scenarios for the uptake of ammonia maritime fuel, it is e-ammonia (or ammonia produced from electrolytic hydrogen) that dominates, and this product can be produced with low to near-zero GHG emissions.
