Following an explosion caused by a fire in the battery room aboard the ferry Ytterøyningen in Norway, the Norwegian Maritime Authority (NMA) has issued a recommendation that all operators with batteries review their risk assessments and possible accumulation of gases.

The battery supplier, Corvus Energy, also issued a recommendation that operators should not sail without communication between the energy management system and the battery management system. And that battery packs should not be powered down, if a thermal runaway situation or fire is suspected, as an unpowered pack cannot communicate system data including faults, warnings, etc.

The investigation into the incident is ongoing and it is not known whether the battery system was connected to the ferry’s energy management system, according to the NMA.

The fire started in the battery room in the evening on Oct. 10. The ferry reached port under its own power, while firefighting was underway, and crew and passengers were safely evacuated. The explosion happened Friday morning under deck and/or in the battery room.

The explosion made the deck bulge out and there is assumed to be considerable internal damage, but toxic and explosive gas accumulation has hampered the investigation so far.

Built in 2006, Ytterøyningen has sailed for the Norwegian ferry company Norled since 2006 and was rebuilt as a hybrid vessel in 2018 with batteries combined with diesel power. She has capacity for 38 cars and 160 passengers.

Norled has 80 vessels and operates ferries and fast vessel services from the Oslofjord to the Troms county in Northern Norway. Headquartered in Stavanger, the company has invested in new vessels and environmentally-friendly technologies. It is owned by the Nordic infrastructure fund Cap Man Infra and the Canadian private equity firm CBRE Caledonian Capital Management.