The Alette Maersk was the first container vessel powered by low-carbon methanol fuel to cross the Pacific Ocean - a milestone in the shipping industry's effort to reduce its climate impact.

But when the 1,148-foot (350-meter) vessel arrived at the Port of Los Angeles from China last week, there was nowhere in the U.S. to buy more of the green fuel, forcing it to rely heavily on petroleum-based maritime fuel for the return trip.

The Alette Maersk, a green methanol-powered ship, is seen docket at the Port of Los Angeles, in Los Angeles, California, U.S., August 27, 2024. REUTERS/Lisa Baertlein

At a day-long ship naming event on Tuesday, A.P. Moller-Maersk representatives said the industry that accounts for close to 3% of global greenhouse gases needs more and cheaper green fuel if it is to decarbonize at the pace scientists and world governments say is necessary to fight climate change.

"We're on a clock," said Maersk CEO Vincent Clerc.