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Expert shares insights on ammonia’s toxicity as a bunker fuel

Muammer Akturk, a Senior Marine Surveyor, provides insights into the intricacies of ammonia’s toxicity, the safety measures needed, and the evolving regulations shaping its adoption.




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Muammer Akturk, a Senior Marine Surveyor specialising in alternative bunker fuels, recently published an article on ammonia as a marine fuel in his Alternative Marine Fuels Newsletter.

He provides insights into the intricacies of ammonia’s toxicity, the safety measures needed, and the evolving regulations shaping its adoption with the recent discussions at IMO:


The maritime sector confronts several significant challenges, primarily due to increasingly stringent regulations concerning emissions and climate change. Factors such as globalization, geopolitical shifts, digitalization, and cybersecurity concerns are further complicating an already intricate operational environment as the shipping industry seeks efficient propulsion and fuel strategies for its global fleet.

The recent alterations to the IMO’s Initial GHG-Reduction Strategy is an international pivot in the maritime industry towards adopting zero-carbon and low-carbon fuels by 2050.

Amidst the diverse array of technological and fuel options currently under consideration by ship designers, builders, owners, and operators, anhydrous ammonia (NH3) is emerging as a potential marine fuel that could be introduced relatively swiftly. It presents a zero-carbon solution (measured from tank to wake) and when considering the entire lifecycle from production to usage (well-to-wake), green ammonia holds the promise of being the ultimate solution. However, it is important to recognize that while ammonia hold great potential, addressing its inherent toxicity remains as a pivotal challenge in harnessing its full benefits.

Properties of Ammonia

Ammonia, under standard atmospheric conditions, exists as a colorless gas and is known for its distinctive strong odor. When subjected to higher pressures, it transitions into a liquid state, simplifying its transportation and storage.

Ammonia exhibits a relatively limited flammability range when compared to some alternative fuels being explored within the shipping industry. However, it is vital to acknowledge its toxicity and high reactivity.

At lower concentrations, ammonia can cause irritation to the eyes, lungs, and skin, while at higher concentrations or upon direct contact, it poses an immediate life-threatening risk. Symptoms encompass breathing difficulties, chest pain, bronchospasms, and, in severe cases, pulmonary edema, characterized by lung fluid accumulation leading to respiratory failure.

Skin exposure to concentrated ammonia can result in severe chemical burns, while contact with the eyes can induce pain, excessive tearing, conjunctival swelling, iris and corneal damage, as well as conditions such as glaucoma and cataracts. Acute exposure to liquid ammonia can manifest as skin redness, swelling, skin ulcers, and frostbite.

Health Risks Associated with Ammonia Fuel Usage

Owing to its harmful properties, ammonia is categorized as a hazardous substance. National standards 

regulate exposure levels and duration, often establishing Permissible Exposure Limits around 50 ppm (parts per million), Recommended Exposure Limits at 25 ppm, and recognizing the Immediate Danger to Life or Health threshold at 300 ppm. Refer to Table 1 for details on exposure duration and associated health effects measured in ppm.

Table 1: Ammonia concentration and Hazard to Human Health

Table 1: Ammonia concentration and Hazard to Human Health

Acute Exposure Guideline Level (AEGL): Ammonia

AEGL 1: Causes irritation but is recoverable immediately when the exposure is stopped

AEGL 2: Cause irreversible or long-lasting health hazards

AEGL 3: Fatal

Potential Source of Ammonia Leakages Onboard

Presently, there are ongoing industry efforts to design and build both an ammonia-powered engine and a corresponding ammonia fuel supply system. These developments facilitate the identification of potential ammonia leaks within a ship’s system. Figure 1 illustrates various sources of ammonia leakage in the ship’s open areas, with the key sources being:

4.1 Sources of Ammonia Leakage in Open Areas

  • Ammonia fuel tank PRV open.
  • Fuel supply system purge/vent/bleed outlet.
  • Ventilation outlets in fuel prep room, TCS, double wall spaces.
  • Bunkering manifold in open zones.

4.2 Sources of Ammonia Release in Enclosed Spaces

  • Fuel preparation room (FPR).
  • TCS (Tank Connection Space).
  • Double wall spaces, including GVU room (Gas Valve Unit).
  • Enclosed bunkering station (if present).

4.3 Release Sources Under Normal Operating Conditions

  • Controlled releases from fuel prep ventilation outlets.
  • Purging and venting outlets with safety measures.
  • Safety measures include gas detection, alarms, shutdown, and ammonia treatment.

4.4 Release Sources in Emergency Situations

  • Uncontrolled release during emergencies, like fires near fuel tanks.
  • Large release potentially covering entire ship with harmful ammonia concentration.
  • Operation of ammonia treatment facility might not feasibly reduce vast gas release.
Figure 1: Potential Source of Ammonia leakages onboard (Source CCC 9/3/1)

Figure 1: Potential Source of Ammonia leakages onboard (Source CCC 9/3/1)

Development of IMO Draft Interim Guidelines for the Safety of Ships Using Ammonia as Fuel

The 9th session of CCC is scheduled to take place from September 20 to 29. Much attention is currently focused on drafting guidelines related to alternative fuels, crucial for the industry's decarbonization goals. One notable effort is the formulation of interim guidelines ensuring the safety of ships utilizing ammonia as fuel.

These interim guidelines are intended for ships subject to SOLAS Chapter II-1 Part G compliance and should be used alongside the IGF Code, incorporating specific considerations for hazards and fuel properties. Completion of this work is anticipated by the end of 2024.

The safety framework employed in the IGF Code for LNG systems encompasses five core principles:

  1. Segregation: Ensuring protection of the fuel tank and installation against mechanical harm and fires.
  2. Integrity: Designing the fuel system to minimize fuel leakage.
  3. Implementing double barriers in all fuel system components to prevent leaks.
  4. Detecting and warning of system leakages, enabling automatic safety responses.
  5. Automatically shutting down the fuel supply system upon leakage detection to mitigate potential consequences.

Additional critical safety measures are required to address fuel's toxicity properties too. A thorough understanding of these unique properties and their impact on risk assessment is vital for implementing effective safety measures to mitigate the risks associated with ammonia as a fuel. This serves as a critical foundation for the development of robust safety regulations.

As depicted in Figure 2, the safety principles outlined in the IGF Code for natural gas can be adapted for ammonia, albeit with substantial modifications to address the heightened toxicity risk in case of containment breach. The existing IGF Code requirements for natural gas do not encompass fuel toxicity, necessitating more stringent safety measures to safeguard against ammonia exposure during normal operation and emergencies.

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Figure 2: Ammonia toxicity risk table on IGF Code concept (Source CCC 9.INF7)

Final Thoughts

The utilization of ammonia as a fuel in the maritime industry holds promise for decarbonization efforts. However, it comes with inherent toxicity issues that necessitate careful consideration. Safety guidelines and principles established for LNG systems, while adaptable to ammonia, require substantial modifications to address the elevated toxicity risk. Understanding the unique properties of ammonia, its potential health impacts, and implementing effective safety barriers are fundamental steps in mitigating the associated risks. As the industry progresses towards ammonia as a viable alternative fuel, robust safety regulations and comprehensive safety measures must evolve in parallel to ensure a safe and sustainable transition.

Photo credit: Chris Pagan on Unsplash
Source: Alternative Marine Fuels Newsletter 
Published: 12 September, 2023

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Alternative Fuels

Singapore to develop alternative bunker fuels standards by 2025

Among local standards and accreditation programmes in the pipeline include a methanol and ammonia bunkering standard that will cover refuelling as well as a hydrogen refuelling standard.





Singapore to develop alternative bunker fuels standards by 2025

Enterprise Singapore (EnterpriseSG) on Friday (29 September) said businesses can look forward to a slew of new international and Singapore standards and accreditation programmes in areas such as greenhouse gas reporting, decarbonisation and renewable energy in the next two to three years. 

These efforts will be spearheaded by EnterpriseSG, together with the Singapore Standards Council (SSC) and Singapore Accreditation Council (SAC).

Among local standards and accreditation programmes that being developed in the pipeline are:

  • A methanol and ammonia bunkering standard that will cover refuelling, operational and safety requirements for the delivery of methanol and ammonia, guiding the local maritime industry in their transition to sustainable alternative fuels. The standard is planned for 2025.
  • Standard on hydrogen refuelling to guide the transportation of hydrogen and operational and safety requirements of refuelling stations. This standard will support companies in their trial of hydrogen fuel cell vehicles and the associated refuelling operations and infrastructure development. The standard is planned for 2025.
  • New standards that will assist the decarbonisation and net zero emission targets of harbourcrafts operating in Singapore. Expected to be developed by 2025, these standards aim to standardise the deployment of charging stations in Singapore to ensure compatibility and interoperability. This will ensure that the charging infrastructure in Singapore can support different types of electric harbourcrafts.

These efforts will be spearheaded by EnterpriseSG, together with the Singapore Standards Council (SSC) and Singapore Accreditation Council (SAC).

EnterpriseSG will work with SSC and SAC to introduce and revise more than 25 sustainability-related national standards and accreditation programmes over the next two years. 

These programmes cover a wide range of sustainability capabilities – from standards targeted to accelerate decarbonisation efforts in the energy and maritime sectors, to sector-agnostic standards to help enterprises improve their environmental performance in carbon emissions, energy, water efficiency and material management.


Ms Choy Sauw Kook, Director-General (Quality & Excellence), Enterprise Singapore, said: “Given the global emphasis on sustainability, it is essential for companies to adopt standards and use accredited testing, inspection, and certification services to strengthen sustainability practices, which builds trust and confidence in Singapore’s products and services.”

“EnterpriseSG, together with our national Standards and Accreditation Councils, will continue to elevate Singapore’s participation in sustainability standards and accreditation programme development and adoption at the international level. Locally, we will also roll out standards and accreditation programmes in key emerging areas including renewable energy and decarbonisation over the next few years. These efforts are expected to benefit more than 1,000 companies.”

Mr Tay Jih-Hsin, Chairman of the Singapore Standards Council, said: “Standards continue to play an integral role in enabling enterprises to build new sustainability capabilities. The SSC will continue to work in developing standards that support enterprises on their sustainability journey. We will also expand our active participation in international standards committees such as the ISO and IEC to raise the profile of Singapore’s sustainability push and connect local companies to more overseas stakeholders.”

Photo credit: Enterprise Singapore
Published: 2 October, 2023

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WinGD receives first ever AiP for ammonia two-stroke engine

Lloyd’s Register awarded the AiP to WinGD’s X-DF-A dual-fuel range, giving shipowners the assurances they need to realise vessel designs using ammonia-fuelled main engines for the first time.





WinGD receives first ever AiP for ammonia two-stroke engine

Swiss marine power company WinGD has secured the first ever approval in principle (AiP) for two-stroke engines fuelled with ammonia, according to Lloyd’s Register on Thursday (28 September). 

Lloyd’s Register awarded the AiP to WinGD’s X-DF-A dual-fuel range, giving shipowners the assurances they need to realise vessel designs using ammonia-fuelled main engines for the first time.

Development of WinGD’s ammonia-fuelled engine series has been advanced with strong support from shipowners, shipyards and engine builders. 

The first engine to be developed, the 52-bore X52DF-A, will be available for delivery from Q4 2024 and is applicable to a range of vessels including gas and bulk carriers.

WinGD CEO Dominik Schneiter, said: “Time is of the essence as shipping looks to clean power solutions. This approval shows the industry that WinGD is leading the way in bringing carbon-free ammonia power to the deep-sea fleet. With the support of expert partners including Lloyd’s Register, these technologies will be available long before emission targets require them, giving operators vital space to plan and gain experience.” 

Lloyd’s Register CEO Nick Brown, said: “The maritime industry needs to trust that new technologies can be deployed safely as it continues to evaluate multiple transition pathways. This AiP will give first movers confidence that, subject to subsequent care in design, build, integration and operation, this ammonia two-stroke engine can help meet that demand. LR is delighted to have worked with WinGD on this groundbreaking development.” 

WinGD was able to validate to Lloyd’s Register experts that the X52DF‑A concept is technically ready to satisfy future regulatory requirements with no major obstacles. As part of the AiP process, Lloyd’s Register considered the engine safety concept, risk assessments and preliminary engine and fuel supply system design, as well as confirming the compatibility of materials with ammonia fuel.

WinGD will extend the X‑DF‑A platform to a 72-bore variant in 2025 followed by other engine sizes in 2026 according to market needs, accommodating a wide range of vessel types from small tankers and car carriers to very large tankers. The engines operate according to the Diesel principle in both diesel and ammonia modes, have the same rating field as WinGD’s existing Diesel engines and will be available with the same cylinder configurations.

Photo credit: Lloyd’s Register
Published: 2 October, 2023

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Alternative Fuels

GCMD, BCG survey highlights three maritime decarbonisation archetypes

Survey identified three decarbonisation archetypes within the shipping industry, differentiated in their outlook, investment appetite and the challenges faced.





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The Global Centre for Maritime Decarbonisation (GCMD) and Boston Consulting Group (BCG) conducted an industry survey to take stock of shipowners and operators’ progress in establishing six elements needed for the shipping industry to reach net zero, according to BCG on Wednesday (27 September). 

The survey saw strong participation from 128 shipowners and operators across vessel types, fleet sizes and geographies, which collectively own or operate 14,000 merchant vessels, and account for USD500 billion in revenue.

The duo found high decarbonisation ambitions: Most respondents viewed net zero as a strategic priority, and 77% had already set concrete decarbonisation targets. The industry has also mobilised resources to decarbonise: respondents are investing 2% of their revenues into green initiatives, and 87% have personnel working toward green objectives.

The path to net zero for shipowners and operators requires six elements:

  • A robust strategy and roadmap
  • Four specific decarbonisation levers to reduce emissions: operational efficiency, technological efficiency, fuel transition, and shipboard carbon capture
  • Enablers such as dedicated sustainability teams, strategic investments in green initiatives, internal carbon prices, and digitalization

While the industry has made some progress in adopting mature and cost-effective efficiency levers, adoption of complex or nascent levers remains low. Drop-in green fuels are constrained by costs and supply-side gaps, and optimism for future cleaner fuels is yet to translate into firm commitment.

The industry is now at a pivotal point, with many shipowners and operators ramping up their decarbonisation efforts. Three-quarters of respondents plan to increase investments in green initiatives. Stakeholders can build on this momentum with a variety of supportive actions. But to be effective, they need to tailor their interventions to address the specific challenges that shipowners and operators face at each stage of decarbonisation.

Three Decarbonisation Archetypes

GCMD and BCG saw three archetypes, differentiated in their outlook, investment appetite, and the challenges faced.

Frontrunners have the greatest ambitions and are willing to invest heavily. They are pushing boundaries, adopting even nascent decarbonisation levers, such as wind propulsion and air lubrication. A majority plan to pilot shipboard carbon capture solutions by 2025. Frontrunners are also planning to adopt methanol and ammonia as early as 2026 and 2029 respectively, and the availability of fuels and bunkering infrastructure will be critical to enabling adoption.

Followers believe in decarbonising their fleets, but have tighter investment thresholds and a near-term outlook. They have kept pace with Frontrunners in adopting mature and cost-effective efficiency levers, such as main engine improvements and slow steaming, but are behind in the adoption of nascent levers, such as wind propulsion and air lubrication.

Conservatives are still early in their decarbonisation journey, likely due to a lack of awareness and familiarity with the various decarbonisation levers, and the capabilities to assess and deploy them. They are best supported by measures that increase their familiarity with the levers and help contextualise them to their specific fleets and operational requirements.

The research highlights five key actions for stakeholders:

Conduct technical pilots and facilitate data sharing, especially for nascent levers

  • Create innovative financing mechanisms to de-risk adoption of less mature levers
  • Raise awareness, contextualize levers, and build capabilities, especially among Conservatives
  • Start to build out future fuels infrastructure at ports
  • Develop mechanisms to equalize and share the costs of levers across the ecosystem
  • Maritime decarbonization is a complex, critical endeavor. The successful implementation of these five key actions demands a whole-of-value-chain approach. By working together, stakeholders can transform the maritime sector into a beacon of environmental stewardship, and set a course for a greener future where decarbonization and commercial success go hand in hand.

Note: The GCMD-BCG Global Maritime Decarbonisation Survey report can be downloaded here.

Photo credit: Venti Views on Unsplash
Published: 28 September, 2023

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