Can Cruising Really Be Net Zero by 2050?

As the cruise industry pursues its industry-wide goal of achieving net zero carbon emissions by 2050, a lot of options for new energy sources are on the table. These include biofuels and synthetic fuels, batteries and hydrogen fuel cells, as well as photovoltaic (solar) power. Wind, too, the most classic and natural form of ship “fuel” could also be increasingly used to at least partially power cruise ships big and small.

“I am hopeful for wind in the future,” says Bill Burke, chief maritime officer for Carnival Corporation, the world’s largest cruise company with nine cruise brands that include Carnival, Holland America Line, Princess Cruises, Cunard, and Seabourn. “I would hope it’s in the next decade,” Burke tells AFAR as he discusses wind power as a way for cruise ships to reduce—and ultimately eliminate—greenhouse gas emissions.

But if the cruise industry is going to meet its short- and long-term climate goals, ships themselves will likely end up using multiple emissions-reducing fuels and technologies. Cruise lines are investing billions of dollars in future ways to power ships, even trying to predict green energy sources and stumbling blocks that are not even on the map yet. There’s a reason: Cruise ships are built to last 25 to 30 years; those debuting now need to be able to run on sustainable engine technologies and greener fuels that may not have even been created or fine-tuned yet, to meet future goals.

Future fuel sources for cruise ships

Currently, the focus in the cruise industry is on Liquified Natural Gas (LNG), the cleanest burning fossil fuel available at scale, which is being used on more than a dozen cruise ships as a “transitional fuel,” meaning that it can easily be replaced by green bio or synthetic LNG using the same engines and fuel supply systems currently in place once those more sustainable fuels are more widely available. There are 25 LNG-powered cruise ships scheduled to debut in the next five years, according to the Cruise Line Industry Association (CLIA).

LNG reduces virtually all sulfur emissions, all or most particulate emissions, and most nitrous oxides. The fuel has been criticized for emitting methane, but that may be an outdated argument. Critics often don’t consider new technology addressing methane slip, says Burke.

Carnival Corp. has 11 LNG-powered ships that are expected to join its fleet through 2025, including eight ships that are already in operation. Royal Caribbean Group (which consists of the cruise lines Royal Caribbean, Celebrity Cruises, and Silversea) is introducing LNG ships also set up to test fuel cell technology—the 728-passenger Silver Nova for ultra-luxury line Silversea, which launched last month, and the 7,600-passenger Icon of the Seas from Royal Caribbean, which will debut as the largest ship in the world in January 2024.

Also arriving in short order are seven ships that will be either methanol ready or methanol capable, coming from brands such as Norwegian Cruise Line, Celebrity Cruises, and Disney Cruise Line. These ships will be able to switch to green methanol, which will make operation almost climate neutral when it becomes more readily available. Carnival Corp. is looking to hedge its bets and retrofit some existing ships for methanol in the near term and may also order some methanol-ready newbuilds in the future, according to Burke.

When it comes to LNG versus methanol, “We don’t necessarily want to pick a winner, so we’ll have ships with both,” Burke says.

New fuels are a key to decarbonizing, but their availability is also the biggest challenge facing the cruise industry in terms of arriving at net zero by 2050. Among other issues, cruise ships will be competing with the rest of the maritime sector, aviation, and several other industries for the green fuels.

Looking towards 2050, “The long pole in the tent is green power,” says Burke.

Courtesy of AIDA

In addition to using LNG and methanol as fuel sources, cruise lines are running an increasing number of pilot programs to test other sustainable fuels on ships currently operating. Molecularly identical to traditional marine gas oil, these greener fuels can also be dropped in to existing engines—which means that older vessels would be able to use them as well.

Carnival began using a biofuel blend of marine gas oil mixed with raw natural materials on German line AIDA’s 3,300 passenger AIDAprima in July 2022. Royal Caribbean’s Navigator of the Seas became the first ship in the U.S. to run on renewable diesel in October 2022.

Cruise lines are working with companies making biofuels from manure, vegetables, used vegetable oil, tallow, and wood.

CLIA reports that there are 32 pilot projects and collaboration initiatives underway between cruise lines and sustainable fuel producers and engine companies. Also, seven newbuild cruise ships that are currently in the works are anticipated to run on zero-carbon fuels—including five hoping to run on green methanol and two on green hydrogen (from MSC Groups’ new luxury line Explora Journeys).

But lack of supply is an issue. “We’ve tested a bunch of different feedstocks and we’re pleased with the results, and we’ll try some more over the next couple of years, but they are generally not available in large volumes today and remain much more expensive than their fossil fuel counterparts,” says Burke.

During a 4-day sailing in June, the 6,300-passenger MSC Euribia sailed from Sant Nazaire, France, to Copenhagen to prove that net-zero cruising is possible today. The LNG-powered ship used bio-LNG from Nordic energy company Gasum, a leading producer of biogas, and technology to optimize energy efficiency.

Wind and solar fit into the testing scenario as well. Think of it as an open call for sustainable options. There’s even been mention of ammonia, hydrogen, and nuclear—though Burke, for one, doubts that these will take hold in cruise.

Batteries, fuel cells, and wind power

Courtesy of Orient Express

Batteries and fuel cells will also be a piece of the 2050 net-zero goals pie. Some cruise lines, such as the Norwegian company Hurtigruten and French line Ponant, already have ships that can operate for at least a few hours using battery power and/or hydrogen-fuel cells, mimicking some of the developments we see in the auto industry, where a big push for more electric vehicles (EVs) is currently underway, and to a lesser extent in the airline sector.

Larger cruise lines such as Royal Caribbean, Viking, and MSC Cruises are newly equipping ships with hydrogen fuel cells that can provide power for short periods of time or serve as auxiliary power systems, reducing fuel consumption. And Carnival Corp. is testing a 10-megawatt battery on AIDAprima. “There is potential for peak shaving, allowing you to operate at a more efficient speed or reduce your engine run hours,” says Burke.

According to CLIA, 15 percent of newbuilds entering service in the next five years will be equipped with battery storage and/or fuel cell technology.

“We anticipate that fuel cell systems and battery technology can help supplement some of the main energy supply needed to run our ships,” Jason Liberty, chairman of Royal Caribbean Group, said in the company’s annual sustainability report, released in April (and based on 2022 research and insights). “This complex and cutting-edge undertaking changes how energy traditionally has been generated and distributed onboard cruise ships.”

Wind is coming soon, too. The first passenger cruise ships using a SolidSail technology, developed by French shipyard Chantiers de l’Atlantique, will debut in 2026 and 2027. The 100-passenger vessels, ordered up by Orient Express, will mark the luxury hotel company’s first move into the cruise market and will be powered by a foldable, large, rigid sail made of composite materials.

For its potential wind scenario, Carnival Corporation is looking at “a vertical rotor-type piece,” Burke says. It would be up on top of the ship near the exhaust stacks and will likely be introduced on a newbuild (versus an existing vessel).

Courtesy of Hurtigruten

The cruise ships of the future

Some cruise companies are further pushing the envelope with ship design, hoping to introduce net-zero ships as early as seven years from now.

Ponant is aiming for a zero-greenhouse gas emissions ship in 2030. The prototype 200-passenger vessel runs on wind, solar, low-temperature hydrogen fuel cells, plus a high-temperature fuel cell carbon-capture technology.

Hurtigruten, too, is looking for a 2030 launch of a ship that runs on wind from retractable sails, solar power, and batteries, with some of the planned technology still in early development while other developments have “reached a relatively advanced stage,” according to the cruise line. The prototype ship would carry 500 passengers.

Royal Caribbean Group plans to build a ship by 2035 that can achieve net zero for all ship operations “without emitting air pollutants such as sulfur dioxides and nitrogen oxides.” The company has looked at LNG, methanol, and ammonia, among other green concepts.

Reducing fuel consumption

Even as new, more sustainable fuels and energy sources enter the mix, cruise lines will need to continue to reduce fuel consumption to help keep costs down—sustainable fuels cost more than traditional marine fuels.

Many ships have updated their HVAC (heating, ventilation, and air-conditioning) systems to be more efficient and have switched to LED lighting to minimize the amount of energy they need.

Among the other cruise industry innovations for reducing fuel use are hull coatings to reduce drag. Some ships float on a bed of millions of microscopic bubbles created by air-lubrication systems in order to reduce drag and conserve fuel. Another way to cut fuel use is better route planning and slowing down, says Burke.

Plugging in at port

Cruise lines have also increasingly invested in shoreside electricity, which allows ships to switch off engines for significant emissions reductions in port—something that of course makes the most sense and has the greatest positive impact when the local power grid itself is green.

Depending on the mix of energy sources, plugging in—which literally means using giant plugs—can reduce emissions up to 98 percent, according to studies, including by the U.S. Environmental Protection Agency. According to CLIA’s latest environmental data report, 120 out of 292 member ships are now equipped for shoreside electricity—a 48 percent increase since 2022, and 86 percent of CLIA member ships coming online between now and 2028 will be able to plug in at port.

There is a pretty major hurdle here, however. While an increasing number of cruise ships have plug-in capability—CLIA puts the number at 210 ships by 2028—only 32 ports, or less than 2 percent of the world’s cruise ports, have at least one cruise berth with plug-in capability. The European Union’s Fit for 55 green program calls for all major ports in Europe to be required to have shoreside power by 2030. But obviously there is a need for more plug-in capabilities at ports globally.

The 2050 outlook

CLIA and its member cruise companies are calling for support of research efforts in order to meet the 2050 sustainability goals.

“With the right level of support from governments and international institutions in incentivizing acceleration of technological advancements and renewable fuels availability, the industry can achieve net-zero emissions cruising by 2050,” says Michele Francioni, senior vice president of optimization for the cruise division of MSC Group.

Is the industry ready to meet its 2050 goals? “I think we’re in a pretty good position,” says Burke. But he admits there is a long road ahead.

“I think the train has left the station and we’re trying to do it,” he says. “We certainly hope to achieve net zero, but there is a lot that has to go right to enable this.”