This hydrogen-powered dreamboat is here to clean up the seven seas

The Europa Seaways will be one of the world’s biggest hydrogen-powered ships. Is it a model for the future of the shipping industry?

Every week, the DFDS ferry shuttles the 480 kilometres between Copenhagen and Oslo, burning 35 tons of oil on its two-day journey, spewing filthy emissions from its smoke stack as it travels. But this is slowly changing. By 2027, the Danish shipping firm hopes a new ship, the Europa Seaways, will run that route powered by compressed hydrogen and emitting only clean water in its wake.

The marine industry is one of the dirty secrets of climate change: we hear about cars, the cloud and even cows contributing to emissions, but marine transport emits 940 million tonnes of CO2 annually and is responsible for 2.5 per cent of global greenhouse gas emissions, thanks to the dirty oil and diesel that's burned for propulsion. "If international shipping was a country, it would be the fifth or sixth highest in the world [for greenhouse gases], between Germany and Japan," says Simon Bullock, a researcher at the University of Manchester's Tyndall Centre for Climate Change Research.

In response, the EU is calling for zero-carbon ships by 2030. Alongside that, the government of Denmark passed a law committing the country to slash carbon emissions by 70 per cent by 2030, requiring different industries to come up with ideas to make that happen. Both decarbonisation efforts give the marine industry a deadline but also make funding available, and that's one reason why DFDS is working on the Europa Seaways project now. A survey by Lloyd's Register suggests that mandatory regulation and financial incentives are the top two reasons why shipping companies accelerate their decarbonisation, with industry body the International Maritime Organization pushing to slash shipping emissions by at least 50 per cent by 2050.

The technology – powering electric propulsion using compressed hydrogen fuel cells produced by local wind farms – already works, though it does need to be scaled for shipping, says Jakob Steffensen, director of innovation at DFDS. But the fuel itself remains expensive, meaning that building a ship that runs on hydrogen makes no financial sense, says Steffensen. "You can't even access the amount of green hydrogen that would be needed and even if we could, the cost is insanely expensive today," he says, adding it would currently cost four times the price of running a ship on diesel.

But that could be set to change. Local power company Ørsted is working with DFDS, shipping giant Maersk, and other industry players to produce green hydrogen using electrolysis, which is splitting water into hydrogen and oxygen, powered by its off-shore wind farms. The source of the power for electrolysis is key to the whole project, as hydrogen is only as sustainable as the energy used to produce it. And, handily, those wind farms are located near the Copenhagen port. "With a bit of luck, we will have a lot of green hydrogen available very near to where our ships go between Copenhagen and Oslo," says Steffensen.

By acting as a bulk purchaser of the fuel, DFDS hopes to help boost demand for hydrogen, kickstarting the market – and eventually reducing prices. "There's a chicken and egg dilemma," Steffensen says, when it comes to supply and demand. "We think projects like this can help… because of the big quantities of fuel that will be needed." The same happened with wind: 20 years ago, it was seen as a joke, a "hippy thing", Steffensen says. "But we broke the curve and now it makes no financial sense to build the old fossil burning plants anymore." If that holds true for hydrogen, it could help the cleaner fuel become financially viable for cars and lorries too, he adds.

In short, the challenges to hydrogen power aren't on ships themselves, but with the market and infrastructure, as production, storage and transport all need to be developed and built. But ships take time to build and stay in use for decades. So even if the fuel itself isn't ready, now is the time to start working on the ships to use it. "Ships live for such a long time – a passenger ship like this can get 30 years," says Steffensen. "If you want to become climate neutral in 2050, this is the time to get started."

And there are technical and design challenges, though Steffensen believes they're solvable. "It's cutting-edge technologies, but it's not like a research project," he says. "We can do these things with the right partners." Those partners include Ballard Power Systems for hydrogen fuel cells, ABB for cell integration as well as electrical propulsion systems, and Lloyd's Register Marine and Shipping for help designing a ship that's safe despite using a highly explosive fuel, as well as Ørsted and others.

The fuel cells will power electric motors, which drive the propellers. So, to start, the Europa Seaways will need electric propulsion, but that's increasingly common on ferries in particular – indeed, there are car ferries navigating Norway's fjords that run entirely on batteries. Jostein Bogen, global product manager at ABB AS Marine & Ports, notes that ten years ago five per cent of ships were built with electric propulsion, and that's now up to 15 per cent. "If you look at what is happening all throughout the transportation segment in terms of electrification, with cars and trucks and trains, this shift is also coming to the marine industry," he says, saying electric propulsion is a future-proofing system that allows an alternative energy source to be swapped out in the future.

Indeed, propulsion is only half the problem. The ferries navigating between Oslo and Copenhagen use ultra low sulphur fuel oil; diesel and liquified natural gas (LNG) are also commonly used in shipping. To switch to hydrogen, the industry will need to scale up fuel cells – though Bogen from ABB doesn't see it as much of a hurdle. "It's a matter of optimising and finding a good way to safely scale it up," he says.

Hydrogen emits only water, but it has downsides – in particular with regards to safety. Not only does it have to be held at extremely low temperatures but at very high pressure, about 250 bar, and it's also extremely explosive, says Charles Haskell, decarbonisation programme manager at Lloyd's Register. "The minimum ignition energy in air for hydrogen is 0.02mJ, in comparison, methane is 0.29mJ," he says. "So in case of a leak, the probability of ignition is very high, thus additional safety measures are required. Added to this the viscosity is low, so the chances of leakage is also increased."

That means ships will need to be designed differently to mitigate the danger. For example, the electronics used in the engine rooms of such ships will have to meet a different criteria, to avoid any hot surfaces igniting hydrogen in case of a leak. Plus, hydrogen is very buoyant, says Haskell, which means if it does leak it can gather and get stuck in high-up corners. "That also provides an opportunity for getting rid of it, if you've got venting built in," adds Haskell. "It's having a consideration of the hazards of the fuel, and designing and engineering around it."

While the Europa Seaways will be massive, carrying 380 cars and 1,800 passengers for multiple days, hydrogen fuel cells won't work for longer-haul trips, such as international container ships, as the energy density isn't high enough, says ABB's Bogen. That means ships travelling long distances wouldn't be able to carry enough fuel for the whole trip, as hydrogen takes up too much space. Haskell says that by volume hydrogen has an energy density one quarter that of petrol, so more space is required for the fuel, a challenge on ships where space is at a premium. The same is true for batteries, with Steffensen saying a ferry running the DFDS route between Sweden and the UK would require a battery weighing 5,000 tonnes using current technology.

One alternative could be hybrid systems, where container ships use diesel when out at sea and switch to battery when closer to shore, helping to reduce local air pollution but not climate change concerns. Another option is ammonia-based fuel, which has a higher energy density than hydrogen, but is also highly toxic. Methanol and biofuels could also be used.

Which will win out? Decades from now, it's likely to be a mix of different fuels, depending on requirements. "In previous transitions in shipping, we've gone from wind to coal and steam and then to oil – every ship was done, they all made the same transition," says Bullock, of the University of Manchester. "Here, we're likely to see combinations: hydrogen, ammonia, methanol, biofuels."

But building ships and replacing existing vessels will take decades. In the meantime, the marine industry can make two changes that will help now: using on-shore power or batteries to limit local pollution, and finding energy efficiencies when sailing.

First, when ships spend time in port, they continue to run their engines – and the fumes they normally spew on the high seas poison the air in highly populated port-side neighbourhoods. Shifting to cleaner energy and electric propulsion is one solution, but until all ships have made the switch, there's also the option to plug in while docked, but only where ports have invested in systems to connect to local electricity grids.

Second, shipping companies can make tweaks to vessels to reduce fuel consumption. "It's hard to retrofit technologies like hydrogen – you need completely different engine types and propulsion systems," says Bullock. Even if alternative fuels are adopted on newly built ships by the end of this decade, he predicts there will still be 80,000 ships running on old fuels for many years to come. To cut emissions now, we can reduce fuel use by simply going more slowly or adding wind-assisted propulsion, more commonly known as "sails". "It's a new twist on an old technology," Bullock says.

If DFDS and its partners can successfully build the hydrogen-powered Europa Seaways, the company says it will cut 64,000 tonnes of carbon emissions annually. But it will also give travellers a quieter ride without a smokestack spewing fumes. DFDS asked customers on its social media channels what should take the place of the iconic smokestack on the new hydrogen ship, and one suggestion was a fountain using the clean water produced by the hydrogen fuel cells. "When you push the throttle down, it'll be a big nice fountain – it would be a good way for us to communicate what this is about: that you can actually propel a 200m ship and the only exhaust is clean water," Steffensen says. "I would love to show my kids that."