Ammonia as a Shipping Fuel

The BHP Group says that it aims to receive its first ammonia-fueled bulk carrier just two years from now. The justification is that ammonia does not emit CO2 during combustion. However,

• Ammonia is not a direct source of energy ― it is an energy carrier. The manufacture of ammonia emits considerable amounts of CO2.

• The combustion of ammonia produces the powerful greenhouse gas, nitrous oxide, N2O.

• The energy density of ammonia is 18.6 MJ/kg, as compared to 55.7 and 44.4 MJ/kg for methane and gasoline/petrol respectively. This means that considerable cargo space will have to be converted to fuel storage.