A study of zero-carbon fuels on a fleet of more than 200 container ships points to a potential $25bn gap between three alternatives.

Total fleet costs up to 2050 would be highest using hydrogen but much lower using methanol and ammonia, according to a report led by classification society Lloyd's Register.

Its Maritime Decarbonisation Hub analysed transition pathways on 222 feeder container ships.

Fleet costs would be $69.4bn for hydrogen, followed by methanol ($51.5bn) and ammonia ($44.5bn).

This compares with a fossil fuel baseline of $42.3bn.

Newbuildings and retrofitting will be required to meet net zero by 2050, the study said.

But whichever fuel is used, 26% of the transition would be achieved through retrofitting.

That means that replacing vessels with newbuildings is not sufficient to meet a net-zero 2050 target.

Younger vessels in operation today need to be retrofitted to accelerate the uptake of zero-carbon fuels, the study added.

Voyage costs dominate the fleet's overall expense, representing 71% to 82% of the cumulative fleet's total costs, depending on the transition.

So improving vessel efficiency and voyage optimisation will be increasingly important to reduce the cost of decarbonisation.

'Words are not enough'

The study evaluated a fleet of feeder container ships operating between Singapore, Hong Kong and other Asian countries.

The methodology evaluated the entire supply chain, from fuel production to usage on board vessels.

"It is now clear that words are not enough, action must be taken to meet our 2030 and 2050 goals," said Shmulick Yoskovitz, chief executive of Singapore's X-Press Feeders.

"As shown in this report, there will probably be more than one 'green' fuel during this transition.

"If partnerships are not formed now to take risks, build vessels and experiment, we will still be debating these issues in five years without being any closer to a solution."

The analysis shows a trade off between early efforts to decarbonise the fleet and the long-term planning approach, which attempts to find the solution with the lowest overall cost.

It suggests a balance must be found that provides a growing supply of fuel without major price fluctuations.

Charles Haskell, programme manager of the Lloyd's Register decarbonisation hub, said the study "can support the container fleet in Asia by helping to reduce uncertainty and risk by providing an understanding of the transition pathways open to them.

"This can also inform a strong business case for a potential coalition that will support their route ahead."