Ammonia as fuel
Use of ammonia (NH3), a carbon-free hydrogen carrier, as a fuel for ships, power plants and long-distance hydrogen transport.
Ammonia contains 17.6% hydrogen by mass and no carbon, so combustion produces nitrogen and water. It liquefies at minus 33°C at atmospheric pressure or at about 10 bar at ambient temperature, far easier than hydrogen at minus 253°C, and a global trade and handling infrastructure already exists for about 180–190 Mt of annual production, mainly for fertiliser.
Applications:
- Shipping: two-stroke ammonia engines from MAN and WinGD entered service around 2025–2026; the IMO net-zero framework favours zero-carbon fuels.
- Power: Japan's JERA co-fired 20% ammonia in a 1 GW coal unit at Hekinan in 2024.
- Hydrogen carrier: cracking ammonia back to hydrogen costs 15–25% of its energy.
Challenges: ammonia is toxic and corrosive, burns slowly and can form NOx and nitrous oxide (GWP100 of 273), so slip and N2O must be tightly controlled. Conventional Haber-Bosch ammonia from grey hydrogen emits about 2.0–2.4 t CO2 per tonne NH3; low-carbon routes use blue or green hydrogen. Haber-Bosch synthesis itself requires roughly 28–33 GJ per tonne including hydrogen in best-practice plants.
Related terms
All terms →- Green hydrogen
Hydrogen produced by splitting water in an electrolyser powered by renewable electricity, with near-zero direct CO2 emissions.
- E-fuels (power-to-X)
Synthetic fuels made from electrolytic hydrogen, sometimes combined with captured CO2 or nitrogen, such as e-methane, e-methanol, e-kerosene and e-ammonia.
- Grey hydrogen
Hydrogen made from natural gas by steam methane reforming without carbon capture; the dominant and cheapest production route today.
- Blue hydrogen
Hydrogen produced from natural gas by reforming, with most of the resulting CO2 captured and permanently stored.
- Fuel cell
An electrochemical device that converts the chemical energy of hydrogen or another fuel directly into electricity and heat, without combustion.