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A group of companies has come together to develop a better understanding of the practical realities involved in using ammonia (NH3) as a fuel for ships.

One of the key elements in the group's approach is to look at the broader spectrum of implications for many ship types and different operational requirements, including bunkering and port operations.

A first step has been to hold a hazard identification workshop (HAZID) to understand the risks involved with using ammonia as a marine fuel.

Understanding the risks

In comparison with conventional heavy fuel oils, ammonia is less energy dense, can be liquefied at -33 degrees Celsius, and stored at atmospheric pressure for use as a marine fuel.

Additionally, although ammonia is derived mainly from fossil sources today, in the future its greenhouse gas footprint could be nearly eliminated if it is produced using electricity from renewable sources.

However, ammonia also has a number of properties that require further investigation. It ignites and burns poorly compared to other fuels and is toxic and corrosive, making safe handling and storage important.

Burning ammonia could also lead to higher emissions of nitrogen oxides (NOx) unless controlled either by aftertreatment or by optimising the combustion process.

A regulatory framework and class rules would therefore need to be developed for its use as a marine fuel.

Panos Koutsourakis, Global Technology Leader for Sustainable Shipping at Bureau Veritas, remarked: "Ammonia is a carrier for hydrogen which can be generated from renewable energy; and ammonia storage and transportation can, in principle, be managed with established technologies.

"But ammonia is both toxic and corrosive. We need to understand, if and how, the associated risks can be managed to merit further practical and commercial development – especially confirming the potential for stable combustion and NOx emissions. Furthermore, potential availability is not yet assured. Sufficient availability of 'green' ammonia would require the scalable development of 'Power-to-X' technologies to provide the volumes necessary for shipping."

The group of participants is focused on the safety issues that need to be addressed. Currently, aspects of using ammonia are not explicitly covered by the existing regulatory framework – notably IMO's International Code of Safety for Ship Using Gases or Other Low-flashpoint Fuels (the IGF Code) - and require specific attention.

The group is due to perform detailed risk studies to assess the technical feasibility and specific safety risks of ammonia-fuelled ships with a view to considering its potential as a safe fuel for the decarbonization of shipping. Each participating organization is providing its relevant expertise to the project in order to study all potential risks.

The HAZID workshop, held at MAN's offices in Copenhagen, was the first of these studies. The participants are: Alfa Laval; Bureau Veritas Marine & Offshore; C-Job Naval Architects; Capital Ship Management Corp; CMB; DFDS; ENGIE; Exmar; Gaslog LNG Services Ltd; Gaztransport & Technigaz (GTT); MAN Energy Solutions; MOL; NYK; Samsung Heavy Industries; Shell International Trading and Shipping Company; Society for Gas as a Marine Fuel (SGMF); Star Bulk; Stena Teknik; and Stolt Tankers.

Commenting on the event, Diane Ruf, Head of Section, Risk, Reliability & Maintenance, at Bureau Veritas Solutions, Marine & Offshore, said: "The workshop was carried out to identify the safety and operational hazards associated with the use of ammonia as fuel for propulsion engine on board a VLCC. The study led to the identification of practical safeguards and recommendations which should be considered in order to lower the risks to As Low as Reasonably Practicable (ALARP). It covered: NH3 storage space and bunker stations, NH3 Fuel Treatment Room and HP Fuel Pump Room (combined), Engine Room (Gas-safe), Vent/Safety system lines and Vent Mast and ship's operations."

Next steps are being considered, but are set to include addressing operational hazards and looking more deeply at conceptual designs based on different vessel types.

Wärtsilä trials

Elsewhere, technology group Wärtsilä announced last month that it had initiated combustion trials using ammonia. As part of the tests, ammonia was injected into a combustion research unit to better understand its properties.

Based on initial results, the tests are to be continued on both dual-fuel and spark-ignited gas engines. These are to be followed by field tests in collaboration with ship owners from 2022, and potentially also with energy customers in the future.

Wärtsilä is also currently developing ammonia storage and supply systems as part of a project to install ammonia fuel cells on Eidesvik Offshore's supply vessel Viking Energy by 2023.

Additionally, the Finnish firm has gained experience with ammonia from designing cargo handling systems for liquid petroleum gas carriers, many of which are used to transport ammonia.