Ammonia: The Fuel of the Future

Last edited: 19/11/2022

The need for alternative fuels:

Overall control and reduction of global greenhouse gas emissions of the maritime industry, regulated by the IMO (International Maritime Organization), encourage the development of low-carbon or carbon-neutral fuels. During the past years, such efforts have resulted in the increasing adaptability of a number of green fuel solutions that aim for better sustainability, and efficiency and encourage innovation. The most commonly used alternative fuels are Liquified Natural Gas (LNG), Liquefied Petroleum Gas (LPG), hydrogen (H2), ammonia (NH3), methanol (CH3OH), and biofuels.

What is NH3?

Ammonia is an inorganic compound of nitrogen and hydrogen, a colorless gas with a pungent odor that contributes significantly to the nutritional needs of terrestrial organisms.  This property is the reason why ammonia saved the world a century ago when a looming food crisis caused a shortage of fertilizers. Now NH3 is expected to do the same and become the hero of climate change with the focus now on the maritime industry.

Carbon-Free Background:

Production methods of Ammonia can be classified into four categories [1]according to the carbon intensity. Grey/Brown Ammonia makes up nearly all of the annual global production of 180 million metric tons and is a compound of atmospheric nitrogen and hydrogen as a byproduct of a CO2 emitting process which is the steam reformation of methane. Blue Ammonia is a type of Grey whose CO2 byproduct is captured and stored in order to reduce emissions. Turquoise Ammoniauses pyrolysis to convert methane into carbon and hydrogen which are in turn reacted with nitrogen and is considered to be in between Green and Blue. Green Ammonia is made from hydrogen produced by water electrolysis powered by renewable energy and nitrogen obtained from the air. In short, Green Ammonia is quite literally made of air, water and sunlight.

An investment opportunity:

The global production of Ammonia was approximately 150 million metric tons in 2021 and is expected to increase with a compound annual growth rate of 6.47% in 2022. [2]Since the market for marine fuels is also expected to increase over the course of the next years, and more specifically by 2030[3], there is a great opportunity for ammonia to take a more important role in the market for zero-carbon marine fuels. However, ammonia contributes significantly to the nutritional needs of terrestrial organisms and serves as a precursor to 45%[4] of the world’s food and fertilizer. Current ammonia production is destinated, mostly, for the agriculture sector, as a fertilizer and not as a fuel, while 70%[5] of current ammonia is used for fertilizer production. In order for the market of Green Ammonia to grow and match the expectations of the growing demand, expansion of production capacity is required, with a focus on the electrolysis function producing hydrogen. This would require great investment as currently only about 1% of Hydrogen is produced using electrolysis. [6]

Transportation and handling Ammonia as a cargo:

An extensive network of liquid Ammonia pipelines and anhydrous Ammonia-specific gas carriers make up a widespread trade network of NH3 for agricultural purposes. However, regarding the shipping industry, the fuel (in liquid form) can be transported by three different vessel types depending on how cargo is stored. Refrigerated cargo, typically at -50ºC at close to ambient pressure, semi-refrigerated, typically at -10ºC and 4-8 bar pressure, and under pressure, typically at 17 bar, corresponding to the vapor pressure of Ammonia at about 45ºC.[7] Refrigerated is the only type that can be transported in high amounts and is typically stored in tanks onshore. The other two can only carry smaller amounts of Ammonia, hence could be efficient for shorter routes and smaller vessels.

Advantages in Storage Efficiency:

One major advantage of ammonia is its energy density. Energy density is central for efficiency in transporting ammonia onboard as it determines how much cargo space the fuel takes up. Since ammonia is stored in a liquid form, a suitable comparison could be made with Liquid Hydrogen. Ammonia has a relatively high energy density of 12.7 MJ/L, far more efficient than Hydrogen which has a lower value of 8.5MJ/L. In addition, while Hydrogen requires cryogenic tanks and a temperature of -253°C, Ammonia can be stored at only -33°C, making it far less energy-intensive as well as cheaper and easier to transport.

The cost of Ammonia

Renewable ammonia is highly dependent on electricity for the process of electrolysis. Hence, its cost depends on the cost of electricity but also on the scaling of the equipment related to the electrolyzer stacks. Scaling decreases the price of electrolyzers approximately by 50% and subsequently the capital expenditure related to them. According to market trends, renewable electricity prices and the capital expenditure for electrolysis will decrease substantially over time, making renewable ammonia more and more competitive with respect to its price, especially as carbon taxes and other regulatory drivers increase. Green ammonia will possibly have a lower cost than fossil fuels.

Highlighting ammonia’s cost competitiveness, research on the ‘Techno-economic assessment of zero-carbon fuels’  uses a case study of a typical bulk carrier to compare Ammonia with other alternative fuels such as hydrogen, methanol, biofuels, batteries, and fossil fuels, by examining different scenarios for energy price and total operating cost of the vessel. The case study concluded on Blue Ammonia being the “lowest cost-zero carbon option when considering timeframes to 2050”.

Technological Readiness:

Noting the situation of the ammonia supply chain, several stages of the delivery chain (bunkering equipment, tanks, fuel supply systems) are ready on a theoretical basis, while other stages (quality standards, ancillary equipment onboard, boilers) require more time as they are still simply conceptual.  However, there is significant interest in ammonia, and market specialists[8] are very optimistic regarding the future prospect of this new entrant to the fuel market.

Safety considerations

Ammonia is a non-flammable but toxic substance. Onboard safety and protection of the crew as well as the protection of the maritime environment in the case of accidental discharge, may require redesigns on current vessel layouts. In addition, new legislation and safety procedures need to be introduced in order to reduce the risk involved in carrying and/or combusting such substances especially as the combustion of Ammonia involves a major issue which is the release of nitrous oxide (N2O), a greenhouse gas more harmful than CO2. However, due to ammonia’s low flammability, NOx emissions are low and can be easily managed and limited by developing the appropriate catalysts[9] to remove completely both the NOx and N2O emissions.


Green Ammonia is a carbon-free fuel with great potential to make a major contribution in the decarbonization of the shipping industry. Modified internal combustion engines, low-pressure fuel tanks, and a new set of safety regulations regarding the toxicity of the fuel can lead the way for a powerful new competitor in the renewable fuel market.

Greek shipowner AVIN international already made an impressive step forward by taking delivery of the first ammonia-fuel-ready tanker in the world, leading the way for a number of orders of ammonia-ready vessels from China and Sweden. The market for ammonia fueled vessels looks very promising and introduces a new wave of sustainability to the maritime industry.

[1] Tullo, A.H. (2021) Is ammonia the fuel of the future?, c&en. Available at: (Accessed: October 20, 2022).

[2]  Brinks, H. and Hektor, E.A. (2022) AMMONIA AS A MARINE FUEL. publication. DNV.

[3] Global Marine Fuel Trends 2030. rep. Loyd’s Register Marine.

[4] Ammonia Wikipedia. Wikimedia Foundation. Available at: (Accessed: October 26, 2022).

[5] Ammonia Wikipedia. Wikimedia Foundation. Available at: (Accessed: October 26, 2022).

[6] Sipa Center on global energy policy (2021) Columbia. Available at: (Accessed: October 27, 2022).

[7] Brinks, H. and Hektor, E.A. (2022) AMMONIA AS A MARINE FUEL. publication. DNV.

[8] Brinks, H. and Hektor, E.A. (2022) AMMONIA AS A MARINE FUEL. publication. DNV.

[9] Tsuji*, I. et al. (2022) Exhaust gas treatment catalysts for ammonia-fueled engines, Ammonia Energy Association. Available at: (Accessed: November 16, 2022).

Dimitra Fanouriadi
Author | BIEM 2024

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