We all know that hydrogen is the power of the future. After all, scientists have been discussing it for decades. Between zero emissions, zero noise and no vibration, it is surely the fuel that yacht owners have been waiting for. Why, then, is it taking so long to arrive, and when will we see hydrogen-powered boats?

The answer to the last question is simple: they already exist. There is a commercial barge plying the River Seine through Paris running solely on hydrogen, for instance.

At rush hour you can cross the harbour from Antwerp to Kruibeke in Belgium on Hydroville, the world’s first H2-powered passenger shuttle. And the well-publicised Energy Observer project successfully sent a solar-powered hydrogen yacht around the planet without using a drop of fossil fuel.

Hydrogen power is stimulating the feverish imaginations of yacht designers searching for the next step forward in futuristic luxury.

In 2019 there was the lavish 112m motor yacht Aqua drawn by Dutch design powerhouse Sinot. It had features galore, including a swimming pool that gushed in steps down the long teak transom of the boat, a glass bow observation lounge and shell-like helical staircase running from the top to the lower deck. And at its core were two 28-tonne hydrogen vacuum tanks capable of storing the gas in liquid form at -253°C.

With 4.4MW hydrogen fuel cells on board, this was enough to power the yacht to 17 knots and give her a 3,750-mile range.

Then last year, news of the Nemesis One was released, a jet-black ‘stealth fighter’ of a catamaran engineered by multihull experts VPLP in pure carbon to foil at over 50 knots.

The boat employs America’s Cup technology on a scale never seen before. Its towering 80m-plus soft autonomous AYRO Oceanwings wingsail is capable of generating huge power and twin L-shaped foils are controlled by an automatic flight system.

The 750m2 of solar panels and the hydrogen-electric powertrain appear almost as a footnote to a project that focuses more on the technology of speed and on luxury.

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Both of these remain no more than concepts, though, if spectacular ones. Sinot says that potential clients are still showing interest in Aqua, and that hydrogen power continues to be a priority for them.

Feadship reports that its clients are increasingly asking after alternative fuels and OceanCo is already working on yachts which operate in a ‘leave no trace’ manner. But across the yachting sector as a whole, the undoubted interest in hydrogen has yet to translate into any meaty projects.

Hydrogen power – no technical leaps needed

“The technology is there, and environmentally speaking it’s the best option we can think of,” says Thibault Tallieu of French hydrogen pioneer EO Dev, which spun out of the Energy Observer project.

“The challenges aren’t technical, not even so much the cost,” but, says Tallieu, it’s the combination of those factors combined with the lack of refuelling solutions. “To have that infrastructure in place so owners know they can go from Monaco to St Tropez; Capri to the Balearics.”

The UK’s Fuel Cell Systems is working on a French project for a mobile refuelling station capable of supplying up to 40kg of pure hydrogen – equivalent to about 250 litres of diesel.

At first it will be in place in Marseille, supporting the launch of an innovative 40ft hydrogen tender from Hynova this June. Then it will follow the boat up the coast in hops to include Toulon, La Ciotat, St Tropez, Cannes, Nice and Monaco as part of Hynova’s Sea Show.

“We aim to move the boundaries,” says Hynova’s Laetitia Vichy. “Without hydrogen in the ports, we can’t grow the number of boats.” She hopes that the mobile stations will stimulate demand and give way to fixed hydrogen fuel pumps with a capacity of 100-200kg.

The transformation can happen very quickly – a matter of months. “It’s a question of investment,” says Cyril Dufau-Sansot of Hy2gen. “Two to three million Euros is the cost of a fixed station, whereas the mobile solution is around €100,000. The cost will drop with scale and manufacturing of mobile modules – within the next 3-4 years, you can halve the price.”

In this model, hydrogen is produced at a large-scale central electrolysis plant capable of turning out 12 tonnes of gas a day, and requiring an eye-watering 30MW of green power. Special trucks carrying a stack of long cylinders then deliver the gas to stations under huge pressure. Other developers want to build small filling stations that make their own hydrogen from mains power and water.

But there is another way of doing it, according to EO Dev. The company is testing a futuristic-looking design for a floating hydrogen fuel station. It would be tethered in ports and harbours and connected to shore power to produce hydrogen from seawater 24 hours a day. Using first desalination then electrolysis, up to 250kg of pure hydrogen could be produced and dispensed every day. “We’ll have a technically functional prototype by the end of 2021, but regulations will take at least another year,” says Tallieu.

A question of space

Getting the hydrogen to the boat is one part of the conundrum, but storing it on board is just as tricky.

As a diffuse gas, Hydrogen must be compressed to 350 bar or even super-chilled to a liquid in heavy tanks aboard. Between the cylinders, pumps and handling systems, hydrogen propulsion requires more space than diesel, even though the fuel cell itself is smaller than the engine.

I asked superyacht builder Royal Huisman, no stranger to ground-breaking technology, what that meant in design terms. “We took an existing yacht and used a 3D model of the vessel, energy use of that vessel, and also the installed power, and replaced everything that was needed to run the vessel on hydrogen – just as an experiment,” says proposals manager Henriko Kalter.

“At that moment your technical volume doubles. There you have to make a choice. If you want to build the same vessel with the same range, you will lose a lot of space on board,” he concedes.

“But that’s part of our smart energy approach, where you also have to lower your energy consumption.” It is an approach the builder adopted successfully with Ethereal and in the refit of Juliet as diesel-electric hybrids, with a large battery bank and smart peak-shaving power management.

But hydrogen presents another challenge. Being one of the smallest molecules found in nature and highly flammable to boot, H2 gas needs very careful treatment. This is one reason that hydrogen tanks can’t simply be built into the bilges, like diesel tanks. They must be ‘outside the hull’ where they can vent safely, according to classification societies such as Lloyds.

“In our research, we made the hull look as if it was continuous from the outside (comparable to a hull door), but the actual vessel stops 4m before the aft end. The last bit is just a rack of big 700-bar hydrogen cylinders,” says Royal Huisman’s Kalter.

Some designers see an opportunity here, because it is much more flexible than the current diesel drivetrains. “The modular nature of an all-electric yacht could also allow unusual layouts which could open exciting design and lifestyle opportunities,” says Lateral’s Simon Brealey, whose team designed the engineering for Aqua. “We can totally re-imagine where the technical spaces on a yacht should go and what they look like.”

A self-refuelling yacht?

The dream is to design a boat capable of making its own hydrogen as it goes, so that it never needs refuelling. The principle was proven by Energy Observer, and Swiss company Aquon has just launched a similar concept for a very swish 64ft power catamaran.

Aquon One can generate up to 13kW of electricity using 70m2 of solar panels. “Many times, the solar panels produce more energy than needed at that specific moment – for instance when Aquon One is at anchor,” explains CEO Christine Funck. “This excess energy is transformed and stored in the form of green hydrogen.”

In optimum conditions, the yacht is capable of operating indefinitely at 3-6 knots, Funck says. And she sees no reason why it shouldn’t work for a sailing version, although shading from sails, rigging and spars naturally reduce the output of the solar panels.

“It would work well on a sailing-catamaran of a certain size, and we have had discussions with clients regarding this topic.”

Daedalus Yachts has got furthest with a design for an 88ft catamaran that makes its own hydrogen using a 10kW solar array, wind turbines and hydrogeneration. The D88 will store the gas in custom-made carbon tanks, which founder Michael Reardon claims to be the only ones certified by DNV. This allows the yacht to fit its tanks in special containment boxes in the bilge of each hull.

This, despite the fact predicted sailing speeds are an eye-watering 36 knots in 24 knots of wind.

Lamination has commenced for a predicted launch next year. “Everybody else is just talking about hydrogen – we’ve actually done the engineering,” says Reardon. “It can work on a monohull too, but the optimum size is 120ft plus.” A simpler system which takes on hydrogen from a shorebased pump rather than making it from seawater will bring hydrogen propulsion to boats as little as 32ft, Reardon thinks. “In the very near future, there’ll be hundreds of hydrogen 32-footers.”

Other types of hydrogen power

Another approach making way in the commercial sector is the use of alternative fuels such as ammonia and methanol. Both are hydrogen-rich, and easier to store than pure hydrogen. Alex Corrigan of ship builder CMB says: “Given a year or two, I think all that press you see now for hydrogen will be moving to ammonia.”

It is not without problems, though, because burning ammonia produces toxic nitrous oxide which has to be removed by exhaust treatment. Methanol is not much better, as it generates CO2 when it reacts in a fuel cell.

Nevertheless, Mathias May of Alva Yachts sees some potential up to about 15kW in his 25m monohull. “We have developed a fuel cell solution using either hydrogen or methanol for our Ocean Sail 72 and Ocean Sail 82,” he says. “In this case we substitute the diesel genset for a fuel cell, but the whole boat is still a serial hybrid.”

“Over a long distance, you can’t store all the power you need even with a diesel motor,” he points out. However, he admits it is a tough sell to customers, and still recommends a ‘get you home’ diesel generator too.

Lürssen recently announced the sale of its first hydrogen-powered superyacht, due for delivery in 2025, which will use fuel cell technology that converts methanol into hydrogen. The German shipyard says this will allow it to travel 1,000 miles emission-free.
Fellow superyacht builder OceanCo meanwhile wants to focus on what it does know. “We can say for certain that future-proofing requires electrification,” says group marketing director Paris Baloumis.

“Also, more intelligent use of technical space is going to be needed, because all alternative fuels are less energy dense than current fossil fuels. The main way to reduce its volume will be to reduce how much of it is needed. Which means we need to keep pushing forward with energy reduction.”

But with so much effort being poured into R&D, it is a question of ‘when’ and not ‘if’ a major hydrogen yacht project gets off the drawing board. “I would hope to see a hydrogen yacht being built at Royal Huisman in the next five to 10 years,” says Henriko Kalter.

“We need some brave owners who are willing to make that step. But as soon as momentum picks up, sailing yachts should be among the first to happen.”

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