With just three hydrogen-fuelled ships on order, it remains far behind methanol (35), LPG (57), battery/hybrid (417) and LNG (534) as a fuel of choice, the report states.

Its appeal is likely to be remain hindered by the lack of regulations for onboard use, which DNV forecasts won’t be implemented until 2032.

While neither 2-stroke nor 4-stroke engines using ammonia as fuel are currently commercially available, DNV forecasts that ammonia and hydrogen onboard technologies will be available within the next three to eight years, and possibly sooner.

The sixth edition report, a year in the making, forecasts 2-stroke and 4-stroke engine technologies on parallel paths for ammonia, enabling uptake in deep sea and regional short sea shipping, with the latter expected to be instrumental for maturing hydrogen technology.

Consequently, the development of fuel cells and 4-stroke engines is ahead of other hydrogen energy converters, the report finds.

Despite the strong interest in ammonia as fuel, it is currently restricted by immature converter technologies.

Nonetheless, the world’s first hydrogen-powered cargo ship (With Orca) and the first hydrogen-powered tug (Hydrotug), using 4-stroke engines, are scheduled to be put into operation within the next couple of years.

Fuel cells with a total capacity of 400kW will power the world’s first liquid hydrogen-powered car ferry, the MF Hydra (pictured).

Key challenges include ammonia’s combustion properties, nitrous oxide (N2O) emissions, and potential ammonia slip.

Shipping faces immense challenges as it strives to decarbonise.

Only around 5.5% of total gross tonnage operating today, and around a third on order, can or will be able to operate on alternative fuels.

If the target of 5% of energy from shipping coming from carbon neutral fuels by 2030 is to be met, huge investments in onboard technologies ($8-28bn) and onshore infrastructure ($30-90bn) are needed, the report states.