Hydrogen Ships: How Maritime is Going Green with Fuel Cells

Maritime's Decarbonization Challenge

Ocean-going ships burn the dirtiest petroleum fraction — heavy fuel oil (bunker fuel) containing up to 3.5% sulfur. A single large container ship can consume 300+ tonnes of fuel per day. The scale of maritime energy demand requires energy carriers with very high density — making hydrogen and ammonia (a hydrogen carrier) particularly attractive.

Hydrogen Ferries in Operation

Several hydrogen ferries are operating commercially:

• MF Hydra (Norway): World's first liquid hydrogen ferry, launched 2021, serving the Hjelmeland-Skipavik-Nesvik route with zero emissions
• Golden Gate Zero Emission Marine: Fuel cell-powered ferry serving San Francisco Bay

Ammonia as a Hydrogen Carrier

Pure hydrogen is difficult to ship at ocean scale. Ammonia (NH₃) can be produced from green hydrogen and nitrogen, stored at −33°C (much easier than −253°C for liquid H₂), and shipped in existing tankers. At the destination, ammonia can be cracked back to hydrogen or burned directly in modified diesel engines. MAN and Wärtsilä have developed ammonia-compatible marine engines.

Large Container Ship Programs

Maersk, the world's largest shipping company, has ordered methanol-powered vessels as an intermediate step, with hydrogen and ammonia in the next generation. The IMO has mandated 50% reduction in shipping emissions by 2050 relative to 2008 — driving this massive investment in alternative marine fuels.