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If liquefied natural gas, or LNG, had to be described in just two words, “clean” and “cold” work just fine.
The former is the reason Royal Caribbean chose LNG to power the two ships in its newest class, Icon, now on order subject to terms and set for delivery in 2022 and 2024. The latter is one of the design challenges in adopting LNG as a fuel.
Besides the fact that today no cruise ship uses LNG as its power source, RCL’s environmentally driven choice will be bolstered by the use of non-polluting fuel cells, possibly to provide electricity for the ships’ hotel functions.
RCL Chairman and CEO Richard Fain describes the Icon class as the start of a “journey to take the smoke out of our smokestacks.”
Regulatory concerns have driven merchant ship investments in LNG in recent years to comply with or prepare for environmental rules from the International Maritime Organization and the MARPOL – International Convention for the Prevention of Pollution from Ships.
“LNG technology is one of the options that can meet existing and upcoming requirements for the main types of emissions” including sulfur oxides, nitrogen oxides and carbon dioxide, according to Norway-based energy consultant DN GVL.
To date, DN GVL says, most maritime uses of LNG have been on smaller craft, including passenger ferries, service boats, even a high-speed catamaran with an LNG-powered gas turbine, but it has also been used on tankers, and orders have been placed for container ships and tugs.
The clear, non-toxic fuel they use is natural gas – methane and a bit of ethane – that has had impurities removed and then liquefied by cooling it to a temperature of about minus 260 degrees F. Specially designed, heavily insulated tanks are used to hold the enormously condensed liquid, which is about 1/600th of natural gas’s volume in home use.
The U.S. Department of Energy says the most common use of LNG is for transporting natural gas to markets around the world, where it is transformed back into its gaseous state and distributed by pipeline.
Several configurations and processes exist for using LNG as maritime fuel, and Royal Caribbean has not released any details of its choices for the new Icon class ships.
However, Fain said Royal Caribbean’s plans to use LNG provide more momentum for an industry already making significant inroads in maritime uses.
“Increasing the commitment to LNG makes it easier for suppliers to make their own infrastructure commitments,” Fain said. “As more ships are built for LNG, the number of ports that support it will grow.”
The Icon ships are expected to run primarily on LNG but will also be able to run on distillate fuel, to accommodate occasional itineraries that call on ports without LNG infrastructure.