ABS three factors of ammonia’s use as a marine fuel:
- Ammonia offers ship owners and operators a zero-carbon tank-to-wake emissions profile, regardless of fuel source.
- Ammonia’s toxicity requires stringent handling measures and permissible exposure limits to be followed.
- Although there are currently no prescriptive requirements surrounding ammonia as a marine fuel, demonstrating a vessel’s capability to operate on ammonia is advantageous.
According to the guide, ammonia is a compound of nitrogen and hydrogen and at atmospheric pressure and normal temperatures is a colorless gas with a characteristic pungent smell. At higher pressures ammonia becomes a liquid, making it easier to transport and store. The typical heating value for ammonia is similar to methanol. As with most alternative fuels, it has a lower energy density than fuel oils, so producing the same energy content would require about 2.4 times more volume as compared to petroleum-based fuels.
The fuel must be placed in specific storages and specific refrigerated conditions. Thus, the requirements of ammonia gas includ low-temperature service, pressurized storage tanks, flammable gases, and working with corrosive and toxic materials is key to addressing the safety hazards of using ammonia as a marine fuel. Some of the considerations when using ammonia as fuel on a vessel are listed below:
- Equipment failure
- Cascading failures
- Safety management plan
- Personnel training to reduce human error.
In addition, ABS presents the pros and cons of using ammonia. Accordingly:
|Carbon free – no CO2 or soot
|Low flammability risk – 15.15% to 27.35% in air
|Can be produced from electrical energy – renewable
||Lack of regulations
|Easily reformed to hydrogen and nitrogen
||Engine development at design stage
|Can be stored and transported as a liquid at a practical pressure and temperature
|Established commercial product
||Corrosiveness to certain materials
||Poor combustion characteristics for IC engine
||Possible need for high percentage of pilot fuel
||Possible increased NOx emission
||Possible ammonia slip
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