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Cross-industry risk assessments highlight the dangers and solutions of ammonia as a future fuel

Ammonia might be a frontrunner in the fuel of the future stakes, but it still has plenty of safety hurdles to overcome to gain widespread acceptance, something class experts are looking into a great deal of late.

Because it burns without emitting CO2 and is zero-carbon well-to-wake when produced from renewable energy, ammonia is a top contender among potential alternative fuels. However, ammonia presents several safety challenges, which must be addressed before it can be used onboard ships. Ammonia is toxic to humans, and exposure beyond certain levels and durations can have serious health consequences for crewmembers and other people onboard.

One small leak on a ship equals 20 funerals


One regular Splash reader warned of the perils of pursuing ammonia as a fuel for vessels, tweeting a while ago: “One small leak on a ship equals 20 funerals and don’t even get me started on what it would do if it leaked into the water.”

Together in Safety, a non-regulatory shipping industry safety consortium which features Lloyd’s Register, Shell, Chevron MSC and Carnival among others, has been carrying out a cross-industry risk assessment study with nine partners to evaluate potential operational risks of LNG, methanol, hydrogen and ammonia.

The collaborative study, which involved a series of hazard identification (HAZID) workshops across a set of operational scenarios based on a standard tanker design, found that of the four fuels reviewed, methanol poses the least overall risk, followed by LNG, hydrogen and ammonia.

Ammonia scored “broadly acceptable” risk as a potential source of ignition in the scenario of tug support or third-party vessel attendance at sea. However, some risks for ammonia as a fuel are classified as high – or intolerable- in navigation scenarios like grounding or collision leading to a hull breach, cargo operations in case of damage to equipment or vent mast, and leaks or loss of containment during bunkering. To bring these hazards down to medium or a low-risk ratings, the study offers recommendations for ammonia usage. These include safety equipment for seafarers if there is a risk of gas pocket formation; dedicated emergency training for crew on fuel system safety devices and mitigating damage to fuel system scenarios; and guidelines on fuel system designs that mitigate risks from grounding or collisions.

Meanwhile, French class society Bureau Veritas (BV) has carried out its own study in collaboration with energy major TotalEnergies aiming at de-risking the use of ammonia as a marine fuel, with a specific focus on leak mitigation and treatment. The study has found there’s much to be learned from shipping’s earlier adoption of LNG as a fuel.

The joint preliminary study has evaluated the health and safety risks from ammonia leaks for crew and passengers and pinpointed key safety criteria, broadening the shipping industry’s understanding of ammonia as a marine fuel. So far, the study has examined different leak scenarios for single-wall and double-wall containment, as well as during bunkering operations – also providing key insights on the efficiency of ventilation and vapor processing systems, the size of safety zones needed, and the health risks to people exposed to leaks.

Marine stakeholders can begin the journey to de-risking ammonia as fuel, as they did for LNG


BV is building on a tried-and-tested approach that was used in the last decade to propel the development of LNG as fuel. BV’s Rule Note NR 671 was also used as a guideline, given its focus on preventing ammonia leaks and requirements for onboard vapor processing systems.

BV and TotalEnergies began by assessing what concentrations of ammonia in the air would be problematic, and compared those levels to LNG. An LNG-fuelled tanker served as the model for the comparison, showing a stark contrast between the two fuels. LNG becomes dangerous at around 50,000 parts per million (ppm), while ammonia starts to have health effects above 30 ppm when permanently exposed, or around 300 ppm when exposed for one hour.

Based on this, BV noted that unless modifications are made to design, safety distances should be much greater for ammonia than LNG. This confirmed the approach outlined in BV’s NR 671, which includes more stringent leak management onboard and vapor gas processing to avoid even small leaks reaching manned areas.

Laurent Leblanc, senior vice president at BV, commented: “Until technology developments can eliminate ammonia leaks completely, leak mitigation and treatment remain the best course of action for shipowners and designers. Our preliminary study with TotalEnergies forms a strong basis for future industry collaboration. By pairing the right questions with the right tests, marine stakeholders can begin the journey to de-risking ammonia as fuel, as they did for LNG.”

Sam Chambers

Starting out with the Informa Group in 2000 in Hong Kong, Sam Chambers became editor of Maritime Asia magazine as well as East Asia Editor for the world’s oldest newspaper, Lloyd’s List. In 2005 he pursued a freelance career and wrote for a variety of titles including taking on the role of Asia Editor at Seatrade magazine and China correspondent for Supply Chain Asia. His work has also appeared in The Economist, The New York Times, The Sunday Times and The International Herald Tribune.
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