Shipping electricity
© PowerX
December 2021

Shipping electricity

By Volker Paulun
Does shipping offshore wind power to onshore grids make sense? A Japanese start-up says yes it does.

Coal, oil, gas: Tons and tons of fossil fuels are being shipped across the oceans, but what about electric current? PowerX intends to do exactly that and has commissioned the first power transfer vessel to be built. It’s scheduled to start its service in 2025. Imabari Shipbuilding, the company contracted to build the vessel, is obviously convinced of the concept as well – the shipyard has acquired a stake worth 7.75 million euros in the PowerX start-up.

The idea of maritime power transfer, says PowerX, is particularly attractive for the Japanese market because of the island state’s mostly deep coastal waters that aren’t suitable for conventional offshore wind farms with turbine foundations set in the seafloor. Like in other parts of the world with similar coastal conditions (such as Norway), the deployment of floating wind turbines suggests itself there. But laying subsea cables to the wind farms located far away from the coast to transfer electric power from there to onshore substations is more expensive and has a greater environmental impact than transferring it on board of battery ships, according to PowerX.

Electricity for 22,000 households

The Power ARK 100 model targeted for 2025 is a trimaran with a length of 100 meters (328 feet) that, logically, will be propelled by electric power and have a range of 300 kilometers (186 miles). For longer distances, a hybrid version with an additional biodiesel propulsion unit is planned as well. The electricity will be stored in 100 grid-scale batteries with a capacity of 220 MWh, which, according to PowerX, is sufficient to supply some 22,000 Japanese households with electric power for one day.

Plans exist for larger versions (150 meters and 220 meters / 492 and 722 feet) and even for a battery factory dedicated to equipping the vessels with the required storage cells.