Toxicity and system-level impact make it more demanding than other ready concepts.
Tank space reserves, safety distances, ventilation, material selection and class assumptions.
Additional costs, later conversion effort and residual value.
Technical, economic and infrastructure questions assessed together.
Ammonia (NH₃) is technically more demanding as a marine fuel than methanol or LNG because it affects multiple system areas simultaneously. A genuine ammonia-ready preparation must therefore go significantly deeper than for other alternative fuels.
Toxicity and safety zones: Ammonia is potentially lethal at concentrations above 300 ppm. This requires safety zones that exceed standard IGF Code requirements. Independent ventilation systems with sufficient capacity must be installed in the engine room to rapidly reduce concentration below the danger threshold in the event of a leak. Gas detection systems must be designed redundantly – at least two independent sensors per monitored area – and the alarm chain must automatically trigger emergency shutdowns.
Material compatibility: Ammonia is corrosive to copper, copper alloys and certain zinc coatings. This potentially affects heat exchangers, cooling water systems, electrical connections and instrumentation. In a ready preparation, the entire material selection in the area of the future fuel system must be reviewed and, where necessary, switched to ammonia-resistant alternatives (typically stainless steel or special nickel alloys).
Tank concept: Ammonia can be stored at ambient temperature under pressure (approximately 10 bar) or cooled to -33°C at atmospheric pressure. Each variant places different demands on tank design, insulation and safety valves. A ready preparation must commit to one of the two variants, as the structural requirements are fundamentally different.
Engine integration: As of 2026, no ammonia marine engine is in series production. MAN Energy Solutions and WinGD are developing ammonia-capable two-stroke engines, but class type approval is still pending for most series. A ready preparation must therefore work with engine specifications that may still change – which complicates the planning of foundations, exhaust lines and control technology.
Exhaust aftertreatment: Ammonia combustion can lead to elevated NOx emissions and so-called ammonia slip (unburnt NH₃ in the exhaust). Both problems require specific exhaust aftertreatment systems – SCR catalysts for NOx, ammonia absorbers or scrubbers for slip. These systems need their own space, which must be provided for in a ready preparation.
Crew protective equipment: Unlike methanol or LNG, ammonia requires special personal protective equipment (PPE) for crew: self-contained breathing apparatus (SCBA), chemical-resistant protective suits and emergency showers near all areas where ammonia exposure is possible. The storage and training requirements for this equipment must already be considered in a ready preparation.
A due diligence review of an ammonia-ready designation should systematically cover five levels:
1. Structural level: Are tank spaces prepared in the correct size and position? Are bulkhead penetrations for ammonia lines provided? Are structural reinforcements dimensioned for the higher weight of pressure tanks (for Type C tanks) or the thermal load of cooled tanks?
2. Safety level: Are safety zones defined in accordance with current (and foreseeably forthcoming) ammonia regulations? Are ventilation, detection and emergency shutdown systems at least conceptually integrated?
3. Material level: Is a material certificate available confirming the ammonia compatibility of all materials used in the fuel area?
4. Classification level: Has the responsible classification society documented the ready preparation in a formal notation? Which conditions have been defined that must be fulfilled before an actual conversion?
5. Economic level: What are the estimated costs of the remaining conversion? What timeframe is realistic? How does the ready preparation affect the vessel’s current operations (loss of cargo capacity, additional weight)?
In the global orderbook, several dozen newbuilds carry an ammonia-ready designation – predominantly in the bulk carrier and tanker segments. However, the depth of preparation varies considerably. Some projects have merely provided space reservations in the general plan without specific material specifications or safety concepts. Others have undertaken comprehensive preparations including structure, ventilation and class notation.
Notably, most ammonia-ready orders originate from larger shipping companies pursuing a long-term fleet strategy. For these operators, ammonia-ready is a hedge against regulatory tightening – particularly in view of possible IMO measures that could favour ammonia as a zero-emission fuel.
The fact that no ammonia engine is available in series production makes every ammonia-ready preparation a bet on technological development. Unlike methanol-ready, where dual-fuel engines are already in operation, ammonia still lacks the critical building block of the engine. The ready preparation prepares the vessel – but the engine intended to use the fuel does not yet exist in series-ready form.
Operators and owners should ask at least these questions in every ammonia-ready assessment:
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