Despite perceptions that travel by sea is more climate-friendly than flying, massive cruise ships contribute significant greenhouse gas emissions. Recently, climate observers have expressed concerns about the proliferation of massive ‘cruisezillas’, and their insufficient commitment to reducing emissions.
A recent report by Transport & Environment (T&E) concluded that the world’s biggest ocean liners have doubled in size since 2000. If the industry’s growth isn’t curbed, the report projects, these ‘cruisezillas’ will be eight times the size of the Titanic by 2050.
Cruise liners have few engineering limits beyond the size of the ports they dock at. Royal Caribbean’s Icon of the Seas, launched in January this year, is the world’s biggest cruise ship at 365 metres long. It carries just under 10,000 people, split over 20 decks, with 40 restaurants, 7 pools, a theatre and a park. All these amenities require massive amounts of energy to run.
And yet just a few short years ago, many were speculating that COVID would leave the cruise industry dead in the water, unable to attract enough customers back to make up for pandemic losses and scandals. The reality completely defied such expectations: T&E projects 35 million passengers will take cruises this year, constituting a 6% increase from pre-COVID levels.
Unfortunately, this industry growth constitutes a major risk to the environment. As Professor Stefan Gössling of Linnaeus University summed up, “hardly any form of tourism is more energy-intensive than cruises”.
In 2022, carbon dioxide emissions from cruise ships were up 17% from 2019 levels. Methane emissions rose 500% over the same period.
Cruise Industry’s Fuel Dilemma
Many of today’s cruise ships, including the Icon, forego the older ‘dirty’ marine fuels to run instead on liquefied natural gas (LNG). While LNG does emit less CO2 than regular marine fuel, burning it releases methane – a greenhouse gas that is 80 times more potent than CO2.
Experts like T&E sustainable shipping analyst Inesa Ulichina agree that “The only green and scalable solution for decarbonising maritime activities is e-fuels. Cruising is a luxury business and operators must take responsibility for their climate impact.” T&E estimates e-fuels could power close to 4% of Europe’s shipping by 2030.
E-fuel options currently seen as the future of sustainable cruising include hydrogen, methanol and ammonia. But they come with their own problems.
While methanol can cut carbon emissions by 95%, and nitrogen oxide emissions by up to 80%, the process of producing green methanol is complicated, and requires as-yet emerging technologies. Still, the container giant Maersk has invested into methanol as its solution of choice.
As for ammonia, Oxford’s Environmental Change Institute projects it could decarbonise 60% of global shipping if it were provided at just a handful of regional fuel ports. It emits no CO2 at all when burned. But many cruise companies say it’s unsafe to use on passenger ships given its highly flammable and toxic nature.
Ultimately, the cruise industry maintains that LNG remains the best option at the moment, with e-fuels largely still under development, and not yet scalable. CLIA, the world’s largest cruise ship trade body, says the industry is “more energy efficient than ever”, and has called on “governments to help accelerate the [fuel] transition by setting more ambitious production targets, particularly for synthetic and biofuels.”
While measures like the EU’s carbon price on ships will force cruise companies to make some eco-friendly switches, sufficient and efficient reforms will require cooperation between governments and cruise companies.
Cover photo by Peter Hansen on Unsplash.
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