(www.MaritimeCyprus.com) Among the alternative fuel options, anhydrous ammonia has drawn a lot of interest from the marine industry for its potential to become a long-term solution for decarbonisation. As a carbon-free substance, ammonia is being investigated as a promising future marine fuel that could contribute meeting the objectives of 2023 IMO GHG Reduction Strategy by offering a zero, or a near-zero, carbon solution on a tank-to-wake basis and for green ammonia near-zero can be met on a well-to-wake basis. Notwithstanding the many benefits, there are also significant risks associated with using ammonia that need to be properly considered to support legislation and safeguards for both the ship and health of persons onboard. The introduction of ammonia in fuel systems, the engine room and the engine itself creates potential risks that need to be properly addressed.
There is extensive land-based experience with the production and use of ammonia as a fertiliser, refrigerant and chemical. With a production of about 200 Mt in 2022, it is the second-largest chemical product manufactured globally.
On the other hand, there is no practical experience in using ammonia as a fuel in shipping and ammonia-based concepts for propulsion, such as ammonia internal combustion engines, are still at development stages. Despite that, a relatively large number of ammonia fuelled ships have been ordered already. Because of its use in other industries, neither handling nor transportation of ammonia as cargo in shipping is a novel concept and there is solid experience with its carriage in liquefied gas carriers that can provide guidance to the development of statutory requirements for its application as marine fuel.
Feedback and lessons learned from land-based industry can be useful. The comprehensive review of accidents, as outlined in section 2.4, underscored critical causes of these incidents that allow identifying recurring patterns and highlighting critical areas for preventive or corrective measures for application in the maritime sector. Valve failures are the most common, leading to ammonia dispersion, severe injuries, and environmental damage. Other root causes are electrical problems and power failures triggering critical events like explosions or safety system failures. Corrosion in pipes and equipment due to chemical exposure and lack of maintenance is also identified. Additionally, design errors, technical specification mistakes, and human errors such as misuse of alarms, incorrect operating procedures, and training deficiencies contribute to incidents, sometimes by delayed or inefficient emergency response exacerbating consequences. These assessments help pinpointing vulnerable equipment and systems prone to failure, enabling the implementation of robust mitigation measures to avert ammonia-related accidents and their adverse impacts on human safety and the ship.
Task 1 of this study presents an extensive analysis of ammonia properties and characteristics and how these are applicable as marine fuel. The main hazard of ammonia in comparison to other conventional and alternatives fuels is toxicity, which can start being dangerous to health from low concentrations (25-50 ppm) and can be fatal when in
higher concentrations (300 ppm), and corrosivity. This study provides an analysis of the toxicity and exposure limits of ammonia comparing several regulatory frameworks. Aside from toxicity, the general behaviour of ammonia was investigated, how this reacts with air and water and how that affects other materials with its corrosive nature and through the stress corrosion cracking.
This report includes a review of the current onshore and offshore regulatory framework related to the use and transport of ammonia and acknowledges that there is still work to do to address properly the safety hazards of ammonia as fuel. Nevertheless, the IMO has significantly progressed in the development of interim guidelines for ships using ammonia as fuel to supplement IGF Code and has included in the work plan the approval of those guidelines for December 2024. This timeframe would match the delivery plan of the first ammonia engines announced for the end of 2024 or beginning 2025. Design work on the first ammonia internal combustion engine is already under advanced development from major engine manufacturers such as MAN ES, Wartsila, HHI-EMD, Japan Engine Corporation and WinGD.
While ammonia carriers would be suitable candidates to be the first movers to adopt ammonia as fuel, the use of toxic cargo as fuel is not yet allowed under the provisions of the IGC Code. Subject matter is highlighted at IMO and proposal to exempt anhydrous ammonia from the list of toxic products that can be used as fuels is to be taken into further consideration.
Toxicity of ammonia adds complexity to ship designs. Toxic areas prescriptive requirements are introduced into the interim guidelines and classification rules as outlined in section 2.3. However, actual toxic areas should be a result of ship specific gas dispersion analysis supported by relevant risk assessment covering several scenarios (e.g. loss of containment from storage tank or piping, during bunkering etc.). With the exact toxic areas’ determination, the below could be verified:
- Ammonia gas does not reach air intakes, outlets and other openings into the accommodation, service and machinery spaces, control stations, the navigation bridge and other non-toxic areas in the ship.
- Lifesaving appliances (LSA), muster stations and escape routes are not located in toxic areas.
- Decontamination showers and eyewash stations.
- Gas detection requirements and sensors’ locations.
- Bunkering safety zones.
- PPE selection according to working area and exposure to ammonia.
An analysis for PPE requirements and standards was conducted. It should be ensured that suitable protective equipment is provided for persons on board, for both routine operations and emergency conditions. Experience from land-based industry shows that the choice of PPE in different areas is subject to the expected concentration and exposure time to ammonia therefore different chemical suits and accessories may be required. Toxic areas determination as described above is a critical step to decide what PPE will be used for each space onboard. This approach with PPE layers is introduced in various publications (SGMF, NTU) and the recent YCA workshop that investigate the safety of ammonia use as fuel.
Classification societies have worked to support the ammonia fuel concept by updating their rules and, through IACS, to feed IMO with useful information. There are still areas where classification rules present minor deviations such as with regards to ammonia detection levels, the lifespan of storage tanks, the ventilation and others indicated in Section 3.3.2. In addition, classification societies have engaged with shipowners, designers, shipyards, engine manufacturers and other stakeholders to conduct feasibility studies for ammonia fuelled vessels including risk assessment workshops and grant approvals in principle for concept designs.
This study is part of a broader planned work that will delve into reliability analysis and risk assessments of ammonia fuelled vessels designs. This first part is relevant for understanding the specific hazards inherent to the nature of ammonia, how such hazards affect the ship and persons onboard, where the regulatory framework development stands and what gaps should be covered to contribute to the adoption of ammonia as a marine fuel.
Building on existing or under development rules and regulations (such as the Guidelines for the use of ammonia as fuels of the IMO) the final objective is the development of Guidance for ships using ammonia as fuel. The preliminary structure for development of such a goal-based Guidance is included in this report.
For more details, download below the report “Safety of Ammonia for Use in Ships” published by the European Maritime Safety Agency (EMSA):
Source: EMSA
For more Guidance papers and research on Ammonia as a Maritime Fuel, click HERE
