Future fuel: the pros and cons of LNG cruise ships

The cruise industry has seen backlash from the media, environmental activists and government bodies following research demonstrating the damage cruise ships cause to the environment. Concern surrounding the environmental impact of cruise ships has led the industry to take steps towards a greener, more environmentally friendly future. 

Leading independent German pollution analyst company Axel Friedrich stated that a single large cruise ship emits over five tonnes of NO_X emissions per day and emits more sulphur than millions of cars. However, the industry has been pioneering the use of greener fuels such as liquid natural gas. 

LNG is one of the cleanest burning non-electric fuels available for the cruise industry and is being used by many companies worldwide for cleaner cruising, reducing the industry’s carbon footprint.

One of the leading companies in the LNG Cruise ship sector is Carnival Corporation - one of the world’s most widely recognised cruise brands.  In 2015, Carnival Corporation made history by developing the world’s first LNG powered cruise ship. Sphinx-class ship AIDAsol, operated by AIDA Cruises, a subsidiary of Carnival Corporation, was powered by an LNG hybrid barge while in port. 

Since then, the company has made headway with the development of AIDAprima and AIDAperla, two ships supplied directly with LNG thanks to their dual-fuel powered engines. The ships can be powered by LNG while at ports, drawing the green fuel directly from the trucks alongside the ships. 

Three years later in 2018, the company made history yet again with the launch of AIDAnova, the world’s first cruise ship to be powered by LNG both at sea and while at ports. The following year saw the company launch the second LNG powered cruise ship – Costa Smeralda. 

In December 2019, the delivery of Carnival Mardi Gras and P&O Cruises UK’s Iona in late 2020 saw them as the third and fourth LNG powered cruise ships to set sail. 

Carnival is currently working towards the delivery of two additional LNG ships late this year – Costa Toscana and AIDAcosma – along with two more LNG ships to be expected in 2022 – Carnival Celebration and P&O UK’s Arvia. Alongside this, an additional seven LNG cruise ships have been ordered for various Carnival Corporation subsidiaries with delivery slated for between 2021 and 2025, representing half of the corporation’s newbuilds on order.  

Commenting on the company’s decision to switch to LNG, Tom Strang, senior vice president, maritime affairs, Carnival Corporation, says: “LNG is an important short-term and long-term solution and is currently the most future-proof technology available. It exceeds all requirements currently in place regarding air emissions and goes a significant way to reducing our carbon emissions while facilitating the introduction of alternative fuels, as technology developments allow.”

“The introduction of LNG to power cruise ships is a major development that supports our environmental goals and decarbonisation pathway, we are continuing to pioneer the use of LNG and expand on our LNG investment as the marine industry’s most advanced fuel technology to date.”

It’s not only Carnival Corporation cruise ships that are using LNG; MSC Cruises has recently announced the construction of its first LNG powered cruise ship, MSC World Europa.

Scheduled to set sail in 2022, the ship is said to be amongst the most technologically developed cruise ships due to its 50-kilowatt LNG powered solid oxide fuel cell technology which has the potential to reduce greenhouse gas emissions by 25% compared with standard LNG engines. 

In a press release, MSC Cruises executive chairman Pierfrancesco Vago said: “MSC World Europa is further proof of our commitment to environmental stewardship as she is set to reduce carbon emissions even further than many other existing cruise ships powered by LNG, which is currently the most environmentally friendly fuel for commercial maritime operations.

“With this vessel, we also reconfirm our belief in investing in advanced environmental technology to meet our long-term goal of zero emissions from operations.”

It’s not just cruise companies that are developing LNG powered cruise ships; multinational mass media and entertainment conglomerate Disney has also turned to this new green fuel for its ships. 

Named Disney Wish, the latest addition to the Disney cruise ship family will also be its first to be fitted with an LNG powered propulsion system. The ship is currently under construction at the Meyer Werft in Papenburg, Germany and is scheduled to embark on its maiden voyage in June 2022.

LNG is the cleanest fossil fuel currently produced, so it is no surprise that various cruise companies have selected it as the power source for their propulsion. The combustion of the gas releases significantly reduced amounts of CO₂, NO_X and SO₂ emissions into the atmosphere, and produces virtually no particulates or ash. 

The use of LNG for a cruise ship also provides advantages over other fuels on the market in the shape of less wear and tear on the engine, as well as a lower cost. Engines that have been designed specifically for LNG fuel use will not require a scrubber system to be installed or require low sulphur-based fuel.

Discussing the selection of LNG for Carnival Corporation cruise ships compared to other alternative fuels on the market, Strang says: “Many factors influenced our decision to be the world’s first cruise company to use LNG to power our ships, including regulatory, reputation and our sustainability profile, which were the key drivers in our choice.

"Since the design for our series of next-generation LNG ships started almost a decade ago, we made the decision at that time to transition to LNG because it was the best option based on local air quality issues.

“While there are alternative fuels that could provide potential solutions in the future and for the next generation of ships, LNG is currently the most environmentally friendly fuel and the only scalable option available that offers significant emissions reductions today.” 

Although LNG provides many benefits to the cruise industry there are also some setbacks, the most noticeable being the specific engine requirements that are needed. LNG is can't be used in an existing gasoline or diesel engine; a cruise ship needs to be designed with a specific engine that will enable it to hold LNG and burn it correctly. 

As LNG has a lower fuel density compared that its predecessors gas and diesel, cruise ships switching to LNG will need twice as much tank space. Increasing tank space on a cruise ship could result in one or two fewer cabins, reducing the number of paying passengers on each cruise. 

Another setback delaying uptake is the current lack of fuelling depots. There are plans for more LNG fuelling depots to be established for LNG cruise ships, but at present, this has deterred companies from purchasing LNG cruise ships. 

With companies such as Carnival Corporation, MSC, Disney and many more exploring the use of LGN to set course towards a cleaner future for the cruise industry, cruising could become a cleaner holiday choice in the not-too-distant future.