Driving change
The move to net zero requires a rethink for the way marine vessels are powered but, as Sandy Neil reports, there are a number of alternatives to consider.
On 14 August, 18-year-old Harry Besley became the first, fastest, and the youngest person to circumnavigate the UK in an electric boat.
After a month on the water – 31 days, 20 hours and 46 minutes to be exact – the Taunton teenager returned to his starting point at Lyme Regis in Dorset, 1,600 nautical miles later. The point of this Round Britain eRIB Challenge? Proving what is possible.
“This is really to raise awareness of the possibility of electric boats,” said Harry. “The electric boat, because it’s silent, doesn’t cause noise, air or water pollution, so there’s many benefits. I just wanted to do something to make people aware of the alternatives.”
Harry Besley aboard Electra
Before the start, the leader of Harry’s support crew – his mum Jaqui – said: “We cannot underestimate the scale of this challenge. EBoat technology is only just developing and EV battery management systems are not designed for continual impact. We have massive range constraints and virtually no shore-side charging infrastructure.”
The rigid inflatable boat (RIB), named Electra, has a Ukrainian-built aluminium hull and Norwegian propulsion system from EVOY. Put together in the Netherlands, Electra carries 126kWh batteries and a 150 peak horsepower equivalent motor.
The secret to covering longer distances in electric boats is a slower speed. At a very slow five knots, the battery will last for 55 miles. At 20 knots, that drops to just 25 miles. They stopped at over 40 points along the way to charge the boat’s engine, and promote the new technology.
Evoy electric aquaculture workboat
Standard marina facilities provide an AC supply but, as with electric cars, a faster charge can be delivered from a DC fast charger.
“At some stops, we’ve been pulling the boat out of the water to put it on a trailer and take it to a car charger,” Jaqui said. “In supermarket car parks, a fast charger is ideal. We’ve been doing that in the middle of the night to meet the next tide.”
Crossing the Irish Sea and navigating the Scottish islands was challenging. The team had to miss the whole north-west coast of Scotland, from Fort William to Inverness, passing through the Caledonian Canal and Loch Ness.
“We aren’t able to go right round the top of Scotland sadly as there isn’t anywhere to come in and the sea state is always rough!” the team’s website explained. “There are also stretches of the coast on the North Sea where there just isn’t any three-phase power available at all.” But despite all these challenges, Harry showed it can be done: he became the youngest person to circumnavigate the UK in a powerboat, and the first person to achieve it in an electric vessel.
Damen SOV e-charging
The fuel alternatives
Traditionally, workboats have relied heavily on diesel engines for propulsion. The aquaculture sector is seeing an increasing trend to hybrid diesel-electric options, and even all-electric boats. Could these become the norm? What are the advantages of switching from diesel – and what are the most common challenges? Is it feasible to retrofit existing vessels for hybrid operation? Are other alternative fuels, such as hydrogen, biofuel or ammonia, feasible?
“All around the world, new regulations are coming into force that will require maritime operators to report – and reduce – the carbon impact of their fleets,” writes Joost Mathôt, a director in the workboats division at Damen shipyard. “To say this presents a challenge to the industry is to understate the situation.
Damen Multi Cat
“For one thing, carbon reduction technology requires an increase in CAPEX (capital expenditure), and frequently OPEX (operational expenditure) too, at a time when it offers no increase in earning potential. A further challenge exists; in most cases, the technology has not yet reached a state of maturity.
“We’ve been spoiled by diesel. It has a high energy density and can be used for all operations, anywhere in the world. The fuels of the future will not have those characteristics. There will be no ‘one-size-fits-all’ solution. None of the currently available alternative fuel types provides a definitive solution. Plus, the origins of the fuels raise further questions.
“On the surface of it, methanol, for example, can offer significant reductions in emissions. But are we talking about grey methanol, blue methanol, or green methanol? All of them have different emissions implications from well-to-wake. It’s the same with electrification. An electric operation is often referred to synonymously as zero emissions. If that operation is drawing energy from a coal power station, though, then emissions reduction is only taking place locally – from tank-to-wake. You’ve just moved the problem ashore.”
Damen has unveiled a “groundbreaking” fully electric Service Operations Vessel (SOV), called the SOV E, that is able to charge from a turbine or substation at an offshore wind farm. The emissions-free vessel will be able to recharge its batteries once a day, thanks to its operational profile, where it deploys technicians to the wind turbines and then loiters nearby until it is time to retrieve them. It will therefore generally have idling time in each 24-hour period, which can be used for recharging the vessel, using just a small part of the energy generated by the wind farm.
At the Seawork exhibition in Southampton on 13 June, Damen also unveiled the Multi Cat 1908 Electric: a multi-purpose workboat designed for operations up to 20 nautical miles from shore. The MuC 1908 E is able to operate for up to 12 hours on a single charge, bringing a full day’s work comfortably into range. The batteries are, additionally, able to power the vessel for up to a decade following delivery.
Flugga electric workboat
Workboats go electric
Back in September, Unst Inshore Services Ltd built the UK’s first 100% electric workboat. The 7.5m Fluggaboat uses an Evoy 120hp continuous rated, electric outboard powered by a 63kWh lithium-ion battery housed in the console. Charging uses an onboard charger, so the vessel can be fully charged overnight or topped up during the day, depending on the rate of use.
The top speed is 30 knots but the most economical speed is 24 knots. The touch screen dash panel gives a good indication of battery state of charge, and use, speed and available range are constantly updated, while motor RPM and kw are also displayed. Below 20%, the battery management system will go into a “get home” reduced power mode to enhance the range for the return trip to a charge point.
Meanwhile Coastal Workboats, a shipbuilder based in Lewis and Devon, is delivering the E-LUV (Electric-Landing Utility Vessel). “The E-LUV will be the first all-electric workboat built and operating in the UK,” it said. “The E-LUV is a highly capable vessel, built to withstand the toughest marine environments found in our harsh waters.
Electric Goldfish X9, powered by Evoy
“Most workboats are deployed in areas with low or no grid power to support recharging of e-vessels. The new E-LUV addresses this via its accompanying shore power storage system (SPSS) which can be used to recharge the vessel, power other applications and, with its innovative rapid-charging capability, significantly reduce vessel turnaround. The power unit can also be carried on the E-LUV’s deck, significantly extending the vessel’s working range and enabling underway charging.
“The SPSS has 1200kWh capacity and can act as a range extender to increase the range of the E-LUV by 50%. Predicted range is 100 miles in good conditions, allowing for three round trips to Papa Stour if an emergency required this. This is increased to 150 miles if relocating the vessel by placing the SPSS on the vessel.”
In spring 2025, the E-LUV is scheduled to enter a four-week trial in the Shetland Isles, serving the West Burrafirth to Papa Stour ferry route.
Hybrid power
Hybrid engines represent another alternative. Hybrid propulsion systems combine conventional combustion engines with electric motors and rechargeable batteries, offering lower fuel consumption and reduced maintenance costs. The battery on a hybrid ship can smooth out the peaks and troughs in power demand, allowing the engine to run at optimal load, known as “peak shaving”. Marine technology innovator Wärtsilä says a hybrid ship can provide fuel savings of 15–25% compared to an equivalent diesel-powered vessel.
With the price of batteries steadily coming down while their performance continues to go up, hybrids are becoming an ever-more attractive option.
Whilst initial investment may be higher than traditional engines, the long-term savings in fuel and maintenance can make them a cost-effective choice.
Mull-based Inverlussa Marine Services, which provides services to Scotland’s aquaculture sector, has commissioned a new hybrid diesel-electric workboat from Macduff Shipyards in Aberdeenshire. It will be equipped with upgraded crane and deck equipment, including larger towing and heavy-duty winches designed to lift and tow heavy objects such as feed barges.
Intended to service larger sites operating in deeper, more exposed, and remote offshore locations, the vessel’s design emphasises advanced seakeeping capabilities to provide a stable platform in rough seas. It will be 25-metres long, operate with a crew of six, and feature five ensuite cabins with a significant focus on noise reduction especially when conducting 24-hour operations to enhance living conditions aboard. It should be operational by the third quarter of 2025, supporting salmon farms off the west coast, as well as in Shetland and Orkney.
Witnessing the contract signing at Macduff Harbour, Scotland’s Deputy First Minister Kate Forbes said: “It is crucial that we continue to embrace innovation in aquaculture practices so that the sector can become resilient to the pressing challenges posed by climate change.”
Copister hybrid feed barge, Cooke Scotland
Following the installation of its first hybrid barge system at Mill Bay on Orkney in 2022, salmon producer Cooke Scotland added two additional hybrid systems at Vestness, Orkney, and Copister in Yell, Shetland, in 2023.
“Energy savings have been immediate,” a spokesperson told us, “with the barges being able to operate for up to 20 hours each day from the batteries alone, and only relying on four to six hours of power from the generator at optimum load. Cooke Scotland also has a workboat which is powered by the latest battery hybrid technology to reduce the vessel’s carbon footprint whilst significantly increasing our site service capacity. The hybrid technology has reduced fuel usage and CO2 emissions whilst further resulting in a reduction in noise, vibrations and exhaust gases.”
Meanwhile a brand new semi-hybrid fish farm service vessel is joining the fleet of Scottish salmon producer Organic Sea Harvest in partnership with Inverlussa Marine Services. The 21-metre long Arthur Douglas was built by Nauplius Workboats in the Netherlands and will take up duties at the Organic Sea Harvest sea sites off the coast of the Trotternish peninsula on the Isle of Skye.
The Arthur Douglas has been custom built with aquaculture and mooring operations in mind, with a deck cargo capacity of 90 tonnes and a 15-tonne deck winch. Two deck cranes – one forward and one aft – have lifting capabilities of 72 tonnes/m and 30 tonne/m respectively.
Stewart Rendall, Cooke Scotland’s North Isles Manager, Orkney (L) with site assistant Dean Shearer (R) on Cooke’s Vestness hybrid barge
The semi-hybrid system onboard the Arthur Douglas uses a battery pack to harvest energy during operational hours, which can then be used to power harbour settings, allowing the generators to be shut down. This will also be the first time that Organic Sea Harvest has introduced a semi-hybrid vessel to the fleet, which will reduce noise and fuel consumption during overnights or days when the vessel is stormed off.
Other alternative fuels are also in the pipeline.
“We like to think of ammonia as the next iteration of LNG [liquid natural gas] – a low-emission fuel with safety challenges, but enormous decarbonisation potential,” says Laurent LeBlanc, Senior Vice President of Technical & Operations at Bureau Veritas, a company testing, inspecting and certifying products.
“When produced using renewable energy, ammonia becomes ‘green ammonia’, a zero-carbon fuel from production to use,” its website explains.
“Green ammonia is also known as e-ammonia. It is produced via the Haber-Bosch process, which converts green hydrogen and nitrogen into ammonia. Other methods for producing green ammonia – such as electrochemical nitrogen reduction – are under development, but will take time to mature and become industrialized.
“There are several advantages to using ammonia as a marine fuel. One of the precursors of the molecule, atmospheric nitrogen (N2), is widely and freely available. As a commonly traded commodity, ammonia also benefits from well-developed storage infrastructure and a worldwide terminal network.
Ammonia clean energy graphic
Internal combustion engines which consume ammonia directly are closer to at-scale development than other solutions for alternative fuels.
Bureau Veritas warns, however: “While fossil fuel-based ammonia is cheap and widely traded, green ammonia is expensive and in short supply.
Ammonia is highly toxic to both people and marine life, and its powerful smell can be a physical irritant. It has low energy density – about three times less than conventional fuels – requiring greater amounts to be carried onboard and reducing space for other cargo. In terms of emissions, while ammonia combustion releases no CO2, it may produce nitrous oxide (N2O), a gas 270 times more potent in terms of greenhouse effects than CO2.
“From a well-to-wake perspective, only green ammonia (‘e-ammonia’) can be considered carbon-free. Ammonia produced from fossil fuels (‘brown ammonia’) in fact has a worse well-to-wake emissions footprint than heavy fuel oil.”
Hydrogen presents another alternative. “Hydrogen shows great promise, but technological maturity has to catch up with ambition,” says Julien Boulland, Bureau Veritas’ Global Market Leader for Sustainable Shipping.
“From a well-to-wake perspective, hydrogen is a potentially zero-carbon fuel,” as the Bureau Veritas website explains. “Green hydrogen is sourced from the process of electrolysis which relies on renewable electricity to split water (H2O) into hydrogen (H2) and oxygen (O2).
“On a tank-to-wake basis, hydrogen is considered carbon-free as it cannot generate CO or CO2 as a by-product (however, some NOx by-products can be produced with engines). With that said, not all hydrogen is sustainably produced; most is currently of fossil origin, using coal and oil. The only truly zero-carbon hydrogen fuel – called green hydrogen – is produced by renewably-sourced electricity via electrolysis. Reaching the required levels will entail an enormous scaling-up of renewable energy production to provide a sustainable source of electricity.”
The company argues that hydrogen fuel cells are a mature and available technology and could be a solution for some vessels. Hydrogen is highly flammable and potentially explosive. Both the gas itself and the flames it produces are colourless and odourless, making leaks difficult to identify.Also, hydrogen must either be compressed or stored in liquid form at very low temperatures. This poses storage design challenges for ships.
Harbour charging point for electric boats
“Production and supply are not yet available at the necessary scale, but the groundwork is being laid around the world,”Bureau Veritas concludes.
To sum up, we turn to the Workboat Association’s Chief Executive Officer Kerrie Forster. “Although the quest for ‘the future fuel’ of the maritime sector appears to have come to a halt with a long list of variable options,” she said, “we do know that within aquaculture, due to the often short-distance between pen and shore, the requirement for large capacity energy types is typically not necessary. Thus, electrifying the common aquaculture fleet is a realistic and achievable objective.
“But this won’t work for all vessel types, for example those vessels often moving between different farm locations, or those of larger design or more intensive operations. Also, the infrastructure requirements need to be taken into consideration. Electricity cannot be transported by road, and if we take the Scottish Highlands and Islands as a case study, generally speaking, the ground is often extremely hard for digging and laying miles of high-capacity electrical cabling and its associated technical apparatus.
“There is no silver bullet, but with the size requirements on board taken into consideration, the high cost of manufacturing and transporting and storing fuels such as hydrogen, methanol and ammonia, electrification does stand out as a strong alternative to current forecourt fuels in a number of cases within the aquaculture industry.”
Harry Besley, and many e-boat builders, are showing us it can be done.
