How to travel more sustainably
Travel more sustainability with these eco-friendly tips.
ProblemSolved, USA TODAY
- The cruise industry is exploring alternative fuels to achieve net-zero emissions by 2050.
- Liquefied natural gas (LNG) offers some emissions benefits over diesel but may not be a long-term solution.
- Green methanol and hydrogen fuel cells offer greater potential but face storage and safety challenges.
- Batteries are viable for short-term, localized emission reduction but lack the capacity for entire voyages.
Cruise ships can often be seen as symbols of excess and environmental waste, but behind the scenes, the industry is working to create a cleaner course for the future.
While sustainable fuels for cruise ships are still not widely available, preparation for that day is well underway.
The industry aims to reach net-zero emissions by 2050, and is investing heavily in adaptable propulsion systems and a range of potential power sources.
“We’re still, I think, in the … position where every fuel has its benefits and its drawbacks, and not one of them with a clear winner,” said Matthew Collette, a professor of naval architecture and marine engineering at the University of Michigan. Most recently, Viking said it will take delivery of its first hydrogen-powered ship in 2026.
Collette walked USA TODAY through the pros and cons of some of the current leading alternative fuel candidates for cruises. Here’s what to know.
Can cruise ships run on liquefied gas?
▶ What it is: LNG, which stands for liquefied natural gas, is “a liquefied version of the natural gas that comes to your house,” according to Collette. As of August 2024, 19 cruise ships operated by Cruise Lines International Association’s oceangoing member lines were capable of using LNG as their main propulsion fuel.
▶ Pros: When burned cleanly, combusting all of the methane, LNG can reduce global warming impacts by around 10% compared with the diesel fuel many modern cruise ships use, Collette said. LNG also contributes less to air pollution in ports.
“It’s much cleaner than diesel fuel in terms of soot, sulfur (and) other things that can affect the local region around the cruise ship,” said Collette.
▶ Cons: Methane is a potent greenhouse gas, and if any escapes unburned through the atmosphere, it has a high global warming potential. “And it probably isn’t going to get us anywhere close to net-zero for CO2 production, because it’s only about 10% better than diesel fuel,” he added.
Other potential options include bio-LNG, which could get closer to net-zero by pulling carbon out of the air during the production process, though Collette said that has not yet been seen “at any large scale.”
Can cruise ships run on green methanol?
▶ What it is: “Green” denotes methanol that is produced without using fossil fuels. “So, you’re getting it from a biological source, or you’re synthesizing it from renewable energy to make hydrogen, and then you capture some carbon, and you can make methanol,” Collette said.
▶ Pros: The fuel could also get the industry close to net-zero by removing carbon from the atmosphere to make the fuel. “So, it has a nice circular property,” Collette said. Unlike LNG, it also doesn’t need to be cooled to -162 degrees Celsius (about -260 degrees Fahrenheit).
▶ Cons: Green methanol has a lower flash point than diesel fuel, and the vapors are noxious. “There’s a lot of concern around explosion, leaks, because it’s a little bit more dangerous than diesel fuel for those things,” he said.
The fuel is also bulkier, taking up roughly twice as much volume.
Can cruise ships run on hydrogen fuel cell?
▶ What it is: Cruise ship operators can run hydrogen through a fuel cell “and you basically get clean power,” according to Collette.
“It’s not being combusted,” he said. “It’s being chemically reacted in a fuel cell, and the properties of that process are very low impact in terms of the environment.”
▶ Pros: Hydrogen can be made by electrolyzing water, resulting in a zero-carbon fuel. “It’s just H2, so that’s really nice,” Collette said. “Virtually everything else about hydrogen is not nice.”
▶ Cons: The fuel is very difficult to transport and store and is explosive. “It’s incredibly bulky,” he added. “The energy density is worse than methanol, and it has to be stored under either pressure, which is probably unrealistic for a cruise ship, or liquefied.” In the latter case, it requires cooling to below -253 degrees Celsius (-423 degrees Fahrenheit).
Can cruise ships run on batteries?
▶ What it is: Batteries allow cruise ships to operate emissions-free during voyages. Over 15% of cruise ships launching within the next five years will have battery storage, according to CLIA.
▶ Pros: Cruise operators could use battery power in sensitive regions, such as Antarctica or parts of Norway. “You could certainly think about switching over to battery power for, you know, six to 12 hours at low speed and then have zero emissions locally while you’re doing that,” said Collette. In ports without shore power infrastructure, ships could also shut down their diesel engines and run on battery power for several hours.
Batteries can also be used for hybrid propulsion, using batteries to help shoulder some of the load.
▶ Cons: Batteries don’t currently have the energy density to power large cruise ships on a standard seven-day itinerary. “I think we’re a way away from that type of energy density, even with lithium-ion batteries,” Collette said.
Nathan Diller is a consumer travel reporter for USA TODAY based in Nashville. You can reach him at ndiller@usatoday.com.
