A new report by UL Solutions, a global independent organisation working for safety and security, outlined the hazards of residential battery storage systems along with advice to firefighters on how to respond to incidents.
Lithium-ion battery thermal runaway without active fire may be recognisable by distinct battery gas leaking from the structure and forming low-hanging clouds, it stated. Should thermal runaway occur after firefighters enter, they can spot two-layer accumulation of whitish/grey lighter gases near the ceiling and heavier gases and vapours along the floor. However, there are no reliable visual, thermal imaging, or portable gas meter indicators to confirm lithium-ion battery involvement in a room and contents fire, it said.
The study, prepared for the International Association of Fire Fighters, contains four different fire and explosion tests, which simulate, for example, a garage. The conclusions are that lithium-ion battery fires lead to a rapid growth of the flames and increased explosion hazards, in particular when fire starts in a space with limited ventilation.
The risk of explosion is unpredictable as the batteries undergo thermal runaway and release flammable gas without burning – a spark can cause an explosion. Therefore, firefighters should avoid placing their equipment close to doors or windows of a site containing lithium-ion batteries.
The body forecasts the global market for residential battery storage will grow from $11 billion in 2022 to $30 billion in 2029, at a rate of 16.3% annually. The major markets are North America and Asia Pacific. Lithium-ion batteries have dominated the battery chemistry, but other battery types will take over in the future, it said.
The report is based on more than 8,000 lithium-ion battery failure incidents, including 141 BESS installations. Of these, 60 were residential ESS events worldwide (including 19 in 2022 and 21 in 2023). It said 86% of the incidents were fire-related, while 11% caused an explosion and some 3% were venting events. Most incidents were reported from Europe, many in Germany. This was due to explosions in homes reportedly containing ESS from the German manufacturer Senec.
The International Residential Code, 2021 Edition, includes requirements (Chapter R328) on the installation of BESS in residential applications. That includes the location of the BESS and the highest single unit size, 20kWh, and the aggregate rating, up to 80kWh outdoors.
