Ula Ship Management: The Expert for Ammonia-powered Ships

99% of the world's merchant fleet burns conventional fuels. Since the beginning of 2020, the focus of the new MARPOL regulations has been on reducing SOx and NOx emissions through low-sulphur marine fuels and diesel. But more and more ships with “green” propulsion systems are coming onto the market, as the order books show. One in nine newbuildings is powered by alternative fuels – mainly large ships. LNG as a fuel minimises SOx and NOx emissions, but fuels like ammonia, hydrogen and biomethanol are alternatives for the next step in emissions reduction: reducing CO2 emissions, the predominant greenhouse gas.

In this context, ammonia has undeniable advantages that could contribute to the creation of a sustainable maritime industry. The chemical compound consists of one nitrogen atom and three hydrogen atoms. It can be produced ”green“ from renewable sources such as wind, sun or water. Since it is not a carbon compound, it burns carbon-free.

Moreover, unlike LNG, ammonia solutions build on established technologies and infrastructure. Ammonia is produced and handled on a large scale as fertiliser. Therefore, it can be easily handled in port terminals, which helps to significantly shorten the path to sustainability.

Compared to hydrogen, the storage of ammonia is relatively simple as ammonia only needs to be cooled to minus 33 degrees Celsius to become liquid, not minus 253 degrees. Alternatively, it can also be compressed. At a temperature of 20 degrees Celsius, 9 bar is enough for ammonia to become liquid. This makes the transport and storage easier and more cost-efficient. It also has a higher energy density and is safer in terms of explosiveness at the same time.

The big advantage of ammonia compared to biomethanol is that ammonia is carbon-free, whereas biomethanol can never be better than “carbon neutral”. And again, biomethanol does not yet have as mature a well-established, large-scale production and port infrastructure as ammonia

Ammonia can not only be burned in engines but can also be used as a hydrogen carrier to power a fuel cell. For this purpose, the hydrogen is largely separated from the ammonia. Pure nitrogen escapes into the air or is fed into the fuel cell together with the hydrogen.

Wärtsilä and MAN, the largest engine manufacturers in the industry, are working on providing ammonia-powered engines for the maritime industry. MAN plans to deliver the first CO2 emissions-free two-stroke engine powered by ammonia in 2024. All in all, there is no doubt that ammonia will become an important carbon-free energy source and make an important contribution to the decarbonisation of the maritime sector.