AMMONIA – NEXT ALTERNATIVE FUEL IN MARINE

Ammonia (NH₃) stands among the world’s four primary industrial chemicals, with current annual production of about 200 million tonnes. It plays a vital role in global agriculture – feeding nearly half of the world’s population through nitrogen-based fertilisers. Although production capacity has increased the global CO₂ emissions deriving from ammonia (less than 2%) have slightly reduced due to improved overall production efficiencies.

Consequently, the decarbonisation of ammonia production and its emerging role as a sustainable maritime fuel are commanding growing attention.

PHYSICAL PROPERTIES, STORAGE AND HANDLING

Ammonia is a colourless, highly toxic gas with pungent smell. Although hazardous at concentrations above detection thresholds (5-50 ppm), ammonia occurs naturally in air and water at levels - far below levels that can be detected by the human senses. It is a common metabolic byproduct in both terrestrial and aquatic environments.

Ammonia is transported and stored in its liquid form, which is achieved by refrigeration (below -33.3 °C), or through pressurization above 8.6 bar at a temperature of 20°C (often to around 20 bar); storage may also be a combination of refrigeration and pressurization. These conditions are less stringent than those for liquefied natural gas or hydrogen, providing logistical advantages. However, owing to its lower energy density per volume unit —only 36% of that of marine gas oil (MGO) — storage tanks must be almost three times larger than for MGO, challenging ship design and operational planning.

Ammonia’s narrow flammability window, high ignition energy, and slow flame speed render it less of a fire risk than what methanol or hydrogen poses, but its toxicity remains the paramount safety concern in marine application.

LOW-CARBON PATHWAYS AND SUSTAINABILITY DRIVERS

Ammonia is synthesised from nitrogen and hydrogen, the latter typically sourced via fossil fuels (mainly natural gas and coal), water electrolysis, or biomass conversion. Based on this, industry tracks production as ‘grey’ (fossil-based, high emissions), ‘blue’ (fossil-based with carbon capture), or ‘green’ (renewables-based, carbon neutral). Although variations exist in resource intensity and emissions, all forms yield chemically identical ammonia.

Ammonia export has contracted 15–20% since 2022 due to global turbulence, yet sufficient production capacity exists for future growth. Currently, less than 3% of ammonia production is blue/green, but significant expansion is anticipated as industries—including shipping—pivot to sustainable supply chains.

AMMONIA'S STRATEGIC MARITIME ROLE

Shipping accounts for roughly 3% of global CO₂ emissions and is under increasing pressure to adopt low- and zero-carbon energy solutions. Market analyses anticipate that ammonia, methanol/ethanol and LNG will become principal marine fuels by 2050.

The earlier established infrastructure supports today large-scale ammonia handling. About 10% of global ammonia is transported via sea, using advanced containment systems. Around 130–195 global ports have ammonia trading capability, equipped with custom berths, refrigerated and pressurised storage, and intermodal loading infrastructure. As maritime demand rises, both port facilities and logistics networks will further adapt.

ENABLING SAFE MARITIME USE: TECHNICAL AND HUMAN FACTORS

The integration of ammonia as a marine fuel depends on stringent safety standards and operational discipline. The maritime regulatory framework—anchored in codes such as IGC and IGF—mandates:

• Segregation of ammonia fuel systems
• Double-barrier pipework
• Automated leak detection and containment
• Dedicated ventilation and gas detection within critical spaces

Operational safety is also based on comprehensive process documentation, regular equipment maintenance, rigorous crew training, and the provision of suitable personal protective equipment (PPE). Risk management approaches, including Quantitative Risk Assessment, guide the continuous improvement of technology, process, and crew training to ensure that handling risks remain low.

CONCLUSION

Ammonia presents a viable pathway for the maritime sector’s energy transition.

While challenges such as toxicity, limited volumetric energy density and questions around supply sustainability demand careful engineering and operational solutions, the existing industrial infrastructure and ongoing regulatory progress provide a solid foundation for adoption.

By combining high-quality systems engineering, best practice operational management, and diligent crew competency development, the shipping industry can unlock ammonia’s potential as a low-carbon marine fuel.

Auramarine stands ready to support the industry in bringing safe, efficient, and sustainable ammonia fuel supply systems, shaping a decarbonised future for global shipping.