The Norwegian Maritime Authority (NMA) has issued two safety recommendations regarding the use of lithium-ion battery systems in the aftermath of a small fire and a subsequent explosion on a local passenger vessel on Thursday, October 10.
The incident occurred in the battery room of the Norled-operated Ro-Pax ferry Ytterøyningen while it was in transit in Sunnhordland on the evening (local time) of October 10.
The vessel then immediately diverted to port in Halsnøy to allow the evacuation of all on board.
No injuries were reported among the passengers and crew. However, local media reports 12 firefighters who had boarded the vessel following the evacuation were later brought to hospital to be treated for exposure to hazardous gases in the battery room.
An explosion then occurred in the battery room within hours of Ytterøyningen's arrival in port.
Investigators believe the blast was the result of thermal runaway, a phenomenon wherein lithium-ion cell temperatures exceed a certain thermal threshold. The activity then causes the release of excessive heat and flammable gases, which could combine and cause an explosion.
Following consultation with Corvus Energy, which supplied Ytterøyningen's battery system, the NMA recommended that battery installations on diesel-electric vessels should be connected at all times to ensure access to alarm systems and safety notifications.
The recommendation comes after the NMA discovered that Ytterøyningen's crew had disconnected the battery system and the ferry had been sailing on diesel fuel when the incident occurred. Since the battery system was disconnected, there was no communication between the vessel's energy management system and the battery packs and thus the bridge crew was unable to receive any error messages about the fire.
Further, the NMA stated that operators of vessels with battery installations need to perform regular risk assessments related to the dangers of accumulation of explosive gases during unwanted incidents in the battery systems.
