Cruise ships: greenwashing or real green?

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Exclusive: Cruises ‘pour poison into the air’ by failing to plug into low-carbon electricity while in UK ports

Ben Webster Lucas Amin

The cruise industry has been accused of misleading tourists with false claims that ships use green energy with “zero emissions” while in port in the UK.

Cruise companies claim the giant vessels – which some experts believe are worse for the climate than flying – are reducing emissions by switching off their engines and plugging into low-carbon electricity while moored.

But an investigation by openDemocracy has found that cruise ships regularly fail to use the ‘shore power’ available in port, and instead burn diesel, which is cheaper but has a huge carbon footprint.

Data from the UK’s biggest cruise port in Southampton shows that only around one in ten cruise ships has plugged into shore power since it became available at the port in 2022.

The data also suggests that the few ships that did use the energy plugged in for only about five hours per visit on average, despite typically spending 12 hours in port.

Cruise ships’ failure to use the shore power appears to be worsening air pollution in Southampton. Just 45 ships visiting the port produced almost ten times more harmful pollutants than the city’s 93,000 cars combined, according to a study published by the Transport & Environment (T&E) think tank in June.

T&E also found that cruise ships emit two to five times more CO2 per passenger kilometre than the average commercial aeroplane in Europe.

Shore power, which is available at 32 cruise ports across the world, can “reduce emissions by up to 98%, depending on the mix of energy sources, while a ship is in port”, according to Cruise Lines International Association

But companies are choosing not to use it, in part because it costs more than tax-free marine diesel, according to the UK Chamber of Shipping, the industry trade association.

Jon Hood, sustainable shipping manager at T&E, said: “It’s hard to believe in 2023 that cruise ships are still allowed to sit in our busy port towns pouring poison into the air that people breathe.

He continued: “[It’s] harder still to believe they’re allowed to do this even when there’s clean power available right there, but the cruise companies don’t want to pay for it for the sake of their profits.”

‘Plume of smoke’

openDemocracy’s investigation comes as the cruise industry is expanding, with more than 70 new ships – many of which can accommodate up to 7,000 passengers and staff – on order globally. Some 1.7 million people in the UK and Ireland holidayed on a cruise ship last year.

In 2021, the chief executives of six of the world’s biggest cruise lines signed a letter committing to support the development of shore power, which they said was needed “to combat climate change”.

Carnival, the world’s largest cruise company, lists “shore power connection” as a key “environmental feature” of its vessels in its 2022 sustainability report.

But the industry is frequently failing to use shore power when it is available. Southampton port’s owner, Associated British Ports (ABP) announced that shore power was ready for use at two its five terminals where cruise ships can dock in April 2022, saying ships could plug in to achieve “zero emissions at berth”.

Between then and the end of July 2023, there were more than 300 days when at least one cruise ship was berthed at Southampton, according to openDemocracy’s analysis of ABP’s schedule.

This suggests shore power could have been used 300 times over that period – even with local grid constraints that mean only one ship can use shore power at any one time.

But in August, ABP told openDemocracy that shore power had been used on just 71 “occasions” since April 2022, though it refused to say exactly when these occasions were.

One only has to look at the plume of smoke from the cruise liners to see the pollution being discharged over our cityKatherine Barbour, Southampton councillor

The failure to use shore power can partly be explained by cruise lines delaying the necessary investment to upgrade their ships to be compatible with the energy source.

Only 46% of cruise ships globally can connect to shore power, according to CLIA – despite the first shore power port connection for cruise ships being installed more than 20 years ago. CLIA says 72% of ships will be able to do so by 2028.

Carnival admitted that the Iona, Ventura and Queen Victoria, which visited Southampton 80 times between May 2022 and February 2023, were not capable of taking shore power in that period.

Yet even cruise ships that can use the electricity regularly fail to do so in Southampton.

The cruise company AIDA, which is owned by Carnival, said in 2021 that the use of shore power “is a decisive step for AIDA cruises to reduce local emissions to zero during berthing over time, as a cruise ship typically stays in port around 40% of its operating time”.

AIDA has also claimed to be “campaigning for the development” of shore power infrastructure at other ports.

But the company’s flagship vessel, the AIDAprima, did not connect to shore power in Southampton on 80% of its visits, despite being able to do so, according to ABP data from May 2022 to February 2023 obtained by openDemocracy.

Katherine Barbour, who became Southampton’s first Green councillor in May, said: “One only has to look at the plume of smoke coming up from the cruise liners to see the pollution that is being discharged over our city.”

A spokesperson for Carnival said: “Our ships leverage shore power whenever possible where available at our destinations.”


Southampton port owner ABP successfully applied in 2020 for a £4.4m public subsidy to install shore power.

In its business case for the grant – which was awarded via the Solent Local Enterprise Partnership (LEP), a voluntary partnership between the local authority and businesses to encourage economic growth in the area – ABP stated that cruise ships were at berth for an average of 12 hours and could plug in for “96% of time in port”.

But figures published in Solent LEP’s annual report suggest that the 55 ships that used shore power in Southampton in the 12 months to the end of March 2023 did so for an average of only five and a half hours, spending the remaining six hours in port burning fossil fuel to generate power. A cruise ship consumes an average of 2,700 litres of diesel an hour in port.

The report stated that the 55 ships used shore power to draw a total of 1.5 million kilowatt hours of electricity. One large cruise ship is likely to use at least this amount of energy in less than two weeks.

It’s hard to believe cruise ships are allowed to pour poison into the air even when there’s clean power available right there

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Peter Aylott, the director of policy at the UK Chamber of Shipping, told openDemocracy: “The current price of electricity is so high that no cruise company is going to use it unless they had to by a mandatory requirement.”

A spokesman for the chamber later clarified Aylott’s comment, saying that the high price of electricity was one reason why cruise ships do not always plug in at Southampton when shore power is available.

The UK is lagging behind the EU in forcing the cruise industry to reduce its emissions via shore power. Cruise ships visiting EU ports will be required to connect to shore power from 2030 under the FuelEU Maritime Regulation. By contrast, the UK government is still considering “options” for expanding shore power use, including “exploring the potential” of requiring vessels to use it when in port.

Jon Hood of T&E said cruise companies that “trumpet their use of shore power in an effort to seem green” but fail to actually use it are guilty of greenwashing.

“The government must require cruise ships to plug into shore power when it’s available,” Hood added. “As a first step, cruise companies should have to publish when their vessels take shore power, and for how long.”

Southampton councillor Katherine Barbour said: “If cruise liners are not mandated to change this will continue and our residents will suffer. We need all berths to be able to provide shore power and ships need to be adapted to use it.

“At the moment every ship is like a small town, spewing out pollution when they are not using electricity.”

Cruise companies have separately been accused of misleading the public with their claims that ships are becoming more environmentally friendly because they can burn liquified natural gas (LNG) instead of diesel.

Environmental group Opportunity Green said research showed that leaks of unburned methane could cancel out the claimed climate benefits of LNG.

A spokesperson for MSC Cruises, whose ships regularly visit Southampton, said it “intends for all ships belonging to MSC Cruises to fully utilise shore power facilities at all other ports they visit once available”. They added that “there exists a variety of reasons for not utilising shore power” but said cost was not one of those reasons.

A spokesperson for ABP said: “ABP Southampton always seeks to maximise the use of its shore power facility subject to asset availability constraints, including grid capacity outside the port, and in response to customer demand.

“The numbers presented to us by [openDemocracy] seem to be taken out of context and to contain important flaws.”

The numbers were either supplied directly by ABP or based on analysis of ABP data.

Asked how many times a cruise ship had failed to plug in at Southampton when shore power was available, the spokesperson said: “We don’t collect the data.”

The Solent LEP report said shore power had saved 1.7 million kilograms of CO2 in a year. That is only a fifth of the annual savings predicted by ABP in its business case submitted to the LEP to obtain the £4.4m grant. ABP said: “Implementation always takes a while to work up as both users and providers become familiar with use in practice.”

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