Overcoming technological barriers to realize all-electric SOVs

Vard Electro is driving progress towards realization of fully electric service operation vessels (SOVs) by putting in place offshore charging stations alongside existing onboard technologies to facilitate zero-emission maintenance operations at offshore wind farms.

Battery-driven power and propulsion systems are seen as the optimal solution to minimize the environmental footprint of SOVs, which are used for crew transfers and logistics in relation to turbine maintenance and account for a high proportion of emissions in wind farm operations.

There are now strong regulatory and commercial drivers for construction of battery-powered ships, given the increased cost of using pollutive fossil fuels as a result of implementation from 2024 of the EU Emissions Trading System (EU ETS) for shipping that ultimately could include offshore vessels, as well as more stringent global emissions regulations such as CII.

Commercial gains from battery power

Emissions performance is seen by wind farm operators as a key technical and commercial competitive parameter in tender rounds for SOV charters. There is also growing pressure from banks and investors for green vessel capacity to cut emissions across the value chain as a condition of wind project financing, as well as from other stakeholders such as NGOs.

While the initial capex for a battery-powered SOV is relatively high, this will deliver commercial benefits in the longer term due to higher costs for emissions and improved energy efficiency that cuts operational expenses", says Øystein Longva, Chief Technology Officer in Vard Electro

All-electric ships with energy storage in large batteries with optimized power control can significantly reduce fuel costs, maintenance and emissions. This also results in increased vessel responsiveness with improved safety and regularity in critical situations.

Vessels running on battery power have improved seakeeping and manoeuvring performance due to a more dynamic response capability from instant current, compared with a diesel generator that needs to ramp up. They also require less maintenance as there are no moving engine parts, which reduces noise and vibration, according to Vard Electro’s Product Manager Power & Propulsion, Jogeir Skinnes.

Along with smart dynamic positioning with more efficient use of thrusters to enhance station-keeping, these factors can enhance overall efficiency as well as widen the operational window for a battery-driven SOV, he says.

Offshore charging in the wind

There have been major advances in battery technology in recent years, with lithium-ion batteries optimized for energy density, lifecycle, cold weather performance, robustness and safety, while costs have been reduced significantly.

Increased battery capacity has resulted in wider application in the maritime industry, with the first all-electric battery-powered car ferry, Norled’s Ampere, brought into operation in 2015 and battery energy storage systems installed on a number of offshore supply vessels.

Longva points out that all the onboard technologies are now in place for fully electric SOVs, with Vard Electro delivering energy storage as well as power management and automation systems as part of its SeaQ product range.

The marine electrical systems supplier is now addressing the final technical obstacle - offshore charging - through its joint leadership of the industry research project Ocean Charger launched earlier this year to test, validate and commercialize new technological solutions for energy transfer to battery-powered vessels offshore.

The project aims to lay the groundwork for green maritime infrastructure as part of future wind development by facilitating charging points at offshore substations connected to wind farm power grids that would enable SOVs to charge batteries with minimum additional energy sources.

Longva points out that such a solution would fit well with the operational profile of SOVs due to proximity to a renewable power source for recharging while working at wind farms. This would also overcome the barrier of limited operational range for fully electric vessels working at long distances from shore-based power supplies.