Damen Shipyards Group officially launched its fully electric Service Operations Vessel (SOV) with offshore charging capabilities on 28 November at the Offshore Energy Exhibition & Conference 2023 in Amsterdam. The company says that the new SOV 7017 E, said to be the world’s first vessel with offshore charging capabilities, paves the way for significantly reduced emissions in the maintenance of offshore wind farms.

The vessel, measuring 70 metres in length and 17 metres in width, has 60 cabins that provide accommodation for crew and up to 40 technicians and all the storage space, workshops, and deck space to undertake the broad scope of transportation and work needed.

The new SOV 7017 E features Damen’s DPX-DRIVE layout, with four azimuth thrusters providing propulsion independently in any direction and offering considerably reduced underwater noise levels, according to Damen.

The company said that, when it started looking into the vessel design three years ago, it established that technically it would be possible but it needed to address two main points. The first one was making the SOV able to charge offshore and the second one was establishing there was a healthy business case since this model represents an increase in CAPEX costs.

For the offshore charging capabilities, Damen partnered with UK-based MJR Power & Automation – a company that has previously developed an offshore charging system for a crew transfer vessel – and conducted a business case analysis that showed a healthy return on investment, ranging anywhere between 5 and 15 years, depending on the scenario, according to the company.

“The product launch of the SOV 7017 E demonstrates that the technology is there to make offshore operations fully electric. The reduction in OPEX implied by harvesting energy directly from the offshore wind farm implies a business case for this model,” said Mark Couwenberg, Damen Product Manager Service Operations Vessels.

“We cannot do this alone, however. To make this a reality will require collaboration throughout the chain, with shipbuilder, vessel operator and wind farm developer working together in pursuit of mutual benefit. We’re looking forward to participating in such cooperations as we take this concept forward. Together, we can make our offshore energy production more sustainable.”

The charging system uses the motion-compensated gangway to connect the vessel and a turbine or substation offshore, in much the same way personnel transfer is undertaken.

The gangway is controlled from the wheelhouse, requiring no manual interaction with charging equipment, and the entire system uses pre-existing offshore infrastructure, meaning no redesign or additions to the offshore wind farm components are needed.

Charging is carried out while the vessel is in a low-power, so-called “green DP mode”, requiring less energy than the hotel load. A full charge typically requires energy produced in just a few hours by a single offshore wind turbine.

“We also wanted to be able to plug in on the grid side of the wind farm so even if the wind turbine is out of operation, the vessel could still charge,” Mark Couwenberg said.

The system, which is about to obtain DNV Approval In Principle (AIP), is designed according to internationally recognised safety standards as well as with forthcoming offshore charging standards under collaborative development by DNV UK and Norway.

MJR has developed a 4 MW charger connector, sufficient for a 70-metre vessel. The company is also working on a scaled-up 8 MW, version that will enable charging larger vessels, up to 90 metres.

“The charging system is designed to be safe, convenient and reliable, with rapid connection and disconnection of the charge umbilical. From the outset of this project, the priority has been to ensure the safety of personnel and integrity of the vessel and offshore assets, under all conditions. Charging from an offshore asset represents optimal practicality, providing a means to reduce costs and emissions and optimise efficiency without placing personnel nor infrastructure in a potentially hazardous situation,” said Paul Cairns, Managing Director at MJR.

The SOV 7017 E features a 15 MWhr battery, sufficient to power the vessel during a full day of operations. The battery is lithium iron phosphate (LFP) in place of the more conventional lithium nickel manganese cobalt (NMC) battery type. This is aimed at maximising the vessel’s sustainable credentials, Damen pointed out.

LFP batteries offer the advantage of being less dependent on sensitive raw materials, particularly cobalt, with LFP also offering improved safety performance, being less susceptible to ignition and, in the event of ignition, being easier to contain, the shipbuilder said.

In the event that the vessel cannot access electricity for a short period, the SOV 7017 E features full redundancy and is able to continue operations with conventional diesel propulsion.