The world's largest cruise ship is set to make its maiden voyage on Saturday, but environmental groups are concerned that the liquefied natural gas-powered ship – and other giant cruise ships – could leak harmful methane into the atmosphere.
Royal Caribbean International Capitalizes on the growing popularity of Icon of the Seas cruises from Miami with a capacity of 8,000 passengers on 20 platforms.
The ship is built to run on liquefied natural gas (LNG), which burns more cleanly than traditional marine fuels but poses greater risks for methane emissions. Environmental groups say methane leaking from ship engines poses an unacceptable risk to the climate because of its short-term harmful effects.
“This is a step in the wrong direction,” said Brian Comer, director of the marine program at the International Council for Clean Transportation (ICCT), an environmental policy think tank.
“We estimate that using LNG as marine fuel releases 120% more life-cycle greenhouse gas emissions than marine gas oil,” he said.
In terms of warming effects, methane is about 80 times worse than carbon dioxide over 20 years, which means reducing those emissions to limit global warming.
Cruise ships like the Icon of the Seas use low-pressure, dual-fuel engines that leak methane into the atmosphere during the combustion process, known as “methane slip,” industry experts claim. Two other engines are used on bulk carriers or container ships that emit less methane, but are too tall to fit on a cruise ship.
Royal Caribbean says its new ship is 24% more efficient when it comes to carbon emissions than the International Maritime Organization (IMO) global shipping regulator requires.
LNG emits fewer greenhouse gases than very low sulfur fuel oil (VLSFO), which powers the bulk of the global shipping fleet, said Steve Esau, chief operating officer of Sea-LNG, an industry advocacy group.
Cruise engines convert natural gas into power in the cylinder, where “it's important to make sure all the natural gas is converted to energy,” said Juha Kaitola, director of R&D and engineering at Wartzila, the maker of the cruise ship's engines.
Unconverted can escape into the atmosphere during the combustion process, he said, adding that Warsaw's natural gas engine technology emits 90% less methane than it did 20 to 30 years ago.
According to 2024 research funded by ICCD and other partners, cruise ship engines have an average methane slip of 6.4%. IMO considers methane slip to be 3.5%.
“Methane is still under scrutiny,” Canadian shipping campaigner Anna Barford told the non-profit organization Stand Earth, noting last summer that the IMO included addressing methane emissions in its efforts to reduce greenhouse gases.
According to the Cruise Line International Association, of the 54 ships ordered between January 2024 and December 2028, 63% are expected to be powered by LNG. Currently, about 6% of the 300 cruise ships sailing are fueled by LNG.
Newer cruise ships are designed to run on alternatives like traditional marine gas oil, LNG or bio-LNG, which account for only a fraction of US fuel consumption.
Royal Caribbean will use different fuels as the market evolves, said Nick Rose, the company's vice president of environment, society and governance.
“LNG is part of our real strategy,” he said.
(Other than the headline, this story was not edited by NDTV staff and was published from a syndicated feed.)