Hydrogen is the future of energy – everyone says so. Billions of pounds of funding have been unveiled as part of the Government’s UK Hydrogen Strategy, which includes marine sector targets
Hydrogen is the future of energy – everyone says so. But what options are there for hydrogen powered boats?
In fact it may be here already, according to Tom Sperrey of Fuel Cell Systems in Berkshire.
‘We could do it today,’ he tells me. ‘I could have your boat in the water with a fuel cell by the spring for £100k plus the cost of the boat!’
Hydrogen fuel has the potential to be entirely carbon-free, producing just water as a by-product of its use.
A decade or more ago, it was assumed that hydrogen combustion would provide a useful stepping-stone to the use of hydrogen fuel cells, because it allowed manufacturers to use existing engine blocks and design.
But burning hydrogen in a thermal engine is up to 50% less efficient than reacting it with air in a fuel cell, and pretty noisy to boot, so this approach has been sidelined in favour of adopting more innovative solutions.
In cars or boats, where every mile of extra range is critical, a key challenge with fuel cells is how to store the hydrogen.
It is a gas at normal pressure and temperature, which means that it has to be heavily compressed to get enough of it into a tank.
At sea, the current limit is 350bar, although the automotive industry has approval for 700-bar storage, which gives an extra 25% capacity.
But, to maintain such pressure, you need specialist carbon cylinders lined with impervious plastic, as well as a system of robust pumps and piping.
And that adds both cost and weight.
Using a 350-bar system, the weight of the fuel cell and the hydrogen storage system still comes in below that of a traditional diesel set-up, but it requires more volume and it costs more.
Using gaseous hydrogen as a fuel leads French marine fuel cell developer EODev to be cautious about marine applications.
‘We’re not looking at replacing the diesel engine – although that is the ultimate goal. [Our target] is limited cruising in inshore areas. It makes perfect sense from an environmental perspective.’
Hydrogen powered boats: Liquid fuel
Another approach is to use a liquid fuel that is rich in hydrogen – like methanol or ammonia.
They naturally contain less usable energy than pure hydrogen, so are less efficient, but being stored in standard fuel tanks makes them easier to integrate with current designs of boat.
The drawback here is that methanol reactions generate CO2 and ammonia produces polluting nitrous oxides.
All these fuels can be produced industrially from fossil fuels, with the associated emissions, or from water and air using renewable energy.
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This gives rise to different ‘colours’ of fuel, ranging from green to grey, brown and black – a loose measure of how environmentally friendly they are.
The other challenge is a relative lack of infrastructure for distributing pure hydrogen (of any colour), which makes it rather difficult to fill up during a cruise.
‘Right now, the thing that’s stopping us is the availability of hydrogen,’ agrees Sperrey.
His company has developed a stand-alone refueller called the HyQube as well as refuelling stations on wheels.
Growing momentum for hydrogen powered boats
Across Europe, many pilot schemes are being rolled out via mobile or small-scale distributors and there are already 11 UK filling stations – concentrated in the south-east of England.
It would not take a big leap to start developing a distribution network around petrol station forecourts and extending to key harbours.
More excitingly, the French company EODev is building a floating hydrogen refuelling station which actually makes its own hydrogen by desalinating and electrolysing seawater in the harbour.
With all these ifs and buts, you might think that the technology would not be ready yet for actual boaters.
But there are already several marine-specific power modules on the market, ranging from 40W to 200kW.
Naturally enough, big engineering firms like ABB and CMB are also building much larger fuel cell systems for commercial vessels, and this will have a trickle down effect in time.
If you want to go emissions-free now, it’ll cost €100k upwards, so it’s an expensive project.
That would make much more sense as part of a luxurious new build project, like the D88 catamaran from Daedalus, which will make its own hydrogen as it goes.
But Daedalus founder Michael Reardon is convinced the technology will trickle down quickly.
‘In the very near future, there’ll be hundreds of hydrogen 32-footers,’ he promises.
In the meantime, you can always use an Efoy methanol cell so you don’t have to fire up the engine for battery charging.
Efoy fuel cells have long been a staple of boat show stands and are now on their fifth generation, leading the market for small-scale methanol units.
The marinised models are the Efoy 80 and Efoy 150 – slightly confusingly generating 40W and 75W of power respectively, at 12V or 24V.
You can simply connect them up to standard, gel, AGM or lithium batteries, although they are at their most efficient paired with an Efoy lithium cell.
‘I have an Efoy on my boat which is 12 years old,’ says Sperrey. ‘It’s been very reliable. As with all fuel cells its performance declines over time.’
Both units are fairly compact (448 x 198 x 275mm) and weigh less than 7kg, making them easy to site.
No need to worry about exhaust gases – just a small quantity of waste water, which should be drained or collected.
You can install an optional control panel in the system to see what’s going on, or add an Efoy Bluetooth adapter – sometimes bundled – and consult the Efoy app via smartphone or tablet.
Liquid methanol fuel comes in 5L or 10L canisters costing £75.60 or £106.80 respectively.
You can also order a 28L canister. At 12V, expect to get 460Ah (5.5kWh) out of the small 5L cartridge or 925Ah (11.1kWh) from the big 10L one.
Efoy 80 BT: £2,670 Efoy 150 BT: £4,230, www.fuelcellsystems.co.uk
Spun out of the sailing campaign of Phil Sharp and his IMOCA 60 OceansLab, this is a hydrogen-based power module that you can order now, although manufacturing is still at a low level, so you won’t receive your fuel cell module until 2022.
It is in a different league to the Efoy, capable of generating up to 15kW of continuous power.
This makes it suitable for propulsion in smaller or easily driven boats, and should easily cover hotel loads on a larger boat with lots of gadgets.
One of the benefits of proton membrane exchange technology like this is that it can supply even very low currents efficiently and step up in the blink of an eye.
The extra power comes with extra dimensions, though.
The unit is over a metre long (110cm), 65cm wide and 35cm high, although it weighs in at just 90kg.
Genevos is also developing larger units with outputs of 30kW and 45kW.
The cost of buying and installing a full system starts at around €100,000, according to Sharp.
‘The price of fuel cells and green hydrogen is really going to drop, especially when large scale electrolysis gets online,’ he says.
‘We’re expecting a 70% reduction in costs. By 2025, there’ll be production boats with hydrogen energy systems.’
HPM-15: c£42,750 (€50,000) www.genevos.com
As the name here implies, this unit is considered as a range extender to an electric boat, but it is also an effective generator.
It has been developed by the commercial spin-off of the Energy Observer project, which is in the process of sending a specially designed hydrogen-electric craft around the globe without a drop of fossil fuel.
The other partner was car-maker Toyota, which provided the fuel cell technology – identical to that in its new Mirai car.
The headline power rating is 70kW – roughly equivalent to 94hp, and the unit is ‘stackable’ so you can install several in series for more power.
Like all hydrogen fuel cells, it is silent, can instantly generate power across its full range of outputs and produces only water as a waste product.
Although it is a recent product, the first commercial demonstration is already afloat; the new Hynova 40 motorboat – currently on a publicity tour in the south of France.
Its top speed is 22 knots and, at 6 knots, it has a range of 69 miles courtesy of 22.5kg of hydrogen stored in three cylinders.
EODev is looking at smaller units too, and admits that the current cost of the REXH2 makes it unlikely to appeal to smaller boats.
‘Our objective is to bring [the price] down significantly within the next couple of years once full industrialisation is underway,’ says Tallieu.
Source: Yachting Monthly