Damen unveils an electric SOV that can charge offshore

Damen electric SOV uses the vessel's motion compensated gangway to create a connection to the charging point on the offshore structure.[Image: Damen]

Damen Shipyards Group has taken the wraps off its latest vessel offering: a fully electric 70-meter service operations vessel (SOV) with offshore charging capabilities.

Offshore charging of the electric SOV paves the way for significantly reducing emissions during the maintenance of offshore wind farms.

Damen began assessing the feasibility of an electric SOV three years ago and quickly established that technically it would be possible. However, offshore charging capabilities would be required. Additionally, there would be an increase in CAPEX costs, so it had to be established if there was a healthy business case.

To achieve offshore charging, Damen has partnered with U.K. based MJR Power & Automation – a company that (as we reported at the time) has previously developed an offshore charging system for a crew transfer vessel. MJR took up the challenge, developing a system that, says Damen, is fast, efficient and, above all, safe.

The charging system uses the SOV’s motion-compensated gangway to create a connection between the vessel and an offshore turbine or substation in much the same way as when a personnel transfer is undertaken. Damen and MJR selected this charging method in order to maximize safety and efficiency. The gangway is controlled from the wheelhouse, requiring no manual interaction with charging equipment. The approach also has the added benefit of utilizing pre-existing infrastructure — a considerable cost-efficiency.

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

The system is designed according to international recognized safety standards, including IEC/IEEE 80005-1. Additionally, it is set to obtain DNV AIP (Approval In Principle) and is designed in accordance with forthcoming offshore charging standards under collaborative development by DNV U.K. and Norway.

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

“The charging system is designed to be safe, convenient and reliable, with rapid connection and disconnection of the charge umbilical, says MJR’s managing director, Paul Cairns. “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 optimize efficiency without placing personnel or infrastructure in a potentially hazardous situation.”

BUSINESS CASE

To assess the business case for the vessel, Damen carried out an analysi that took into account parameters that included the investment cost for chargers and batteries, the cost of replacement of batteries, energy costs, the price of CO2, large variations of operational profiles, and charge times. The input parameters have been validated in cooperation with wind farm developers and other stakeholders. Many different scenarios have been analyzed, but, says Damen, all had in common a healthy return on investment, ranging anywhere between 5 and 15 years, depending on the scenario.

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) rather than the more conventional lithium nickel manganese cobalt (NMC) battery type. This is aimed at maximizing the vessel’s sustainability credentials. LFP batteries offer the advantage of being less dependent on sensitive raw materials, particularly cobalt. LFP also offers improved safety performance, being less susceptible to ignition and, in the event of ignition, being easier to contain.

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.

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

The vessel has all the storage space, workshops, and deck space to undertake the broad scope of transportation and work expected of it. Its 60 cabins provide comfortable accommodation for crew and up to 40 technicians.

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