Ad Hoc Marine Designs Ltd (AHMD) has unveiled a new class of crew transfer vessel (CTV) that is 100% battery-powered, that is designed to be recharged offshore using power from a mothership, or have its ‘drop-in’ batteries replaced when required
The 15-m Faraday-class ‘electric personnel transfer vessel (ePTV)’ is an all-electric vessel designed to align with the offshore wind industry’s need to decarbonise operations and maintenance (O&M) operations and align with the UK Government’s vision for a future in which internal combustion engine is phased out of the maritime sector.
Faraday-class ePTVs will be available exclusively from shipbuilder AMC on the Isle of Wight on the south coast of the UK, AHMD/AMC being part of a consortium that won the clean marine Department of Transport Grant. The other members of the consortium are MJR Power, Turbulent Marine Simulations, Stirling Batteries and the ORE Catapult. The Clean Maritime Demonstration Competition is funded by the Department of Transport and delivered in partnership with Innovate UK. Announced in March 2020, and part of the Prime Minister’s Ten Point Plan to position the UK at the forefront of green shipbuilding and maritime technology, the Clean Maritime Demonstration Competition is a £20M (US$28M) investment from government alongside a further £10M from industry to reduce emissions from the maritime sector.
AHMD believes existing concepts for fast CTVs transporting wind turbine technicians from port to a windfarm are “being stretched to the limit” by far-from-shore windfarms. Existing designs are not sustainable when using diesel engines, it said, and it believes the whole ‘model’ for design and operation of CTVs “must change.”
“What energy company would continue to offer contracts to a company using diesel engines when its own modus operandi is to be 100% renewal and green?” the company said. “The whole model needs a tectonic shift, changing the way a vessel is designed and operated – and this can only be achieved by looking to the future, which is 100% electric.”
AHMD believes the Faraday class fulfils this role by using Sterling Plan B batteries. “The power density of batteries is known to be around 50 to 1 when compared with an internal combustion engine, but this should not be seen as a barrier, rather as an opportunity,” said the company. “The opportunity is there to change the narrative from diesel engines to all-electric.”
“Our objective, using energy storage systems/batteries that can be quickly replaced by a simple lift in and out, has been satisfied. The objective of having a personnel transfers vessel that can be 100% electric, using batteries, by careful selection of the right type and size that makes the ePTV cost-effective, has been satisfied. The Faraday-class ePTV is essentially an electric taxi,” said the company.
The Faraday-class ePTV is one of four daughter vessels that would be stowed on the deck of a mothership in an offshore windfarm. Overnight the batteries are charged and/or replaced. “When duty calls, the ePTV is lifted off the mothership and launched into the field. The ePTV then has around four to five hours of usable power, depending upon its duties. When the charge is low it can be recharged directly from a wind turbine or return to the mothership where it docks at the stern, allowing for the spent batteries to be lifted and replaced with fully charged batteries within minutes,” AHMD explained.
“The mothership is capable of ‘creating’ its own electricity from its own wind generators where it is not possible to connect with the windfarm cables. It also carries diesel/alternative fuel generators when the wind doesn’t blow and for redundancy/emergency back-up.”
The mothership acts as a hotel and an offshore charging station and does not transfer technicians to the tower. Rather, it loiters in the area of operation for the day. This increases the level of safety for windfarm technicians when compared with existing SOV operations. “In an emergency situation, such as a lightning storm, a maximum of 12 technicians on a tower can quickly disembark back to the ePTV – attempting this using a service operation vessel with up to 60 technicians is not so straightforward.”
Although the battery-powered concept of operations is being promoted for newbuilds, AHMD says it is also suitable for retrofit and could be used to repower existing CTVs. “Once the Faraday-class is up and running and vessels are in service, it provides a benchmark of how best to re-engineer and repower old designs, using this modular energy storge system power source,” the company told OWJ. “This would make it possible to ‘green’ the existing fleet and upgrade older vessels to a 100% green and renewable power source. Doing so would make the long-term objective of the UK Government possible.”
What is more, said the company, with a fully-electric battery-powered solution available, there is no need for new windfarms around the world to use polluting, diesel-powered vessels. “There is no need to adopt old designs and technology,” said AHMD. “Sidestep the learning curve and go directly electric.
“New windfarms in Japan, for example, are located around 10 km offshore. This short distance is ideal for the use of battery-powered ePTVs. There is little point in using an old design with a diesel engine for O&M operations. Looking at sites off the eastern seaboard of the US, the Faraday-class operational model of mother and daughter vessel makes perfect sense too.”
In addition to innovative propulsion, AHMD said part of its vision with the ePTV was the creation of a new style and livery to match this ambition. The styling and livery of the ePTV was developed by DESIGNOVA to distinguish itself from other CTVs. AHMD previously collaborated with DESIGNOVA when designing the 100-m stabilised monohull ‘Power Ark’ for PowerX, a vessel transporting energy via batteries to and from a windfarm.
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