Safety
Grid-scale battery standards and fire containment practices are at an early stage of development.[46]
Fire risks are one factor that has delayed the deployment of some utility energy storage systems. Most battery fires cannot be extinguished with water, which is the primary firefighting technique in most communities. A fire in a single cell can cascade to others via thermal runaway, possibly in milliseconds, potentially creating a major hazard.[46]
Preventing fires involves multiple layers of protection. First, is to prevent fire in a single cell, by eliminating sparks and short circuits. However, grid-scale systems face potential problems such as coolant leaks and faulty installation. Venting flammable gases and improved insulation reduce cascade risks. Placing controls outside of the container gives more management options. Instead of suppressants, monitoring the situation while watering surrounding areas can help contain the fire. Sensors that track local weather conditions can help avoid overheating. Lithium-free designs with lower fire risks are possible.[46]
"Plume modeling" attempts to predict how gases from burning battery chemicals might travel. The gases produced vary across battery types, hydrogen fluoride (HF) is of particular concern even at low concentrations. A later plume analysis by Vistra reported that concentrations of HF above California exposure limits could spread across an area 1300 feet in diameter under wind conditions that occur 7 percent of the year.[46]
In Raquette Lake, New York, the town passed a one-year moratorium preventing battery installation in response to protests citing fires at three New York battery installations. Protestors cited a fire in Lyme, New York that burned for four days.[46]
A Megapack ignited at Pacific Gas and Electric's (PG&E's) Moss Landing, California facility in September 2022. The fire led to a day-long shelter-in-place advisory. PG&E stated that safety measures included thermal alarms that can shut down the system, an incident command center, an audible evacuation alarm, pre-fire planning with local fire crews and emergency shut down protocols. Heat-suppression systems, intended to curb thermal runaway, were accidentally triggered, dousing batteries in water that caused arcing and short circuiting. The plant was shut down for months.[47] Vistra's third installation in Moss Landing adopted the outdoor container model instead of putting the racks under a single roof. (Vistra stated that the outdoor design was chosen to expedite construction.)[46][48]
In July 2021, one of the 212 Megapack modules at the Victorian Big Battery project caught fire[49] due to a coolant leak while the battery was unmonitored. That ignited the adjacent Megapack.[37] Three days later, the fire had burnt itself out as preferred by the fire department.[50][51][46]
A 50 MW / 100 MWh battery project using Tesla Megapack 2 was under construction in Bouldercombe near Rockhampton, Queensland.[52] The alternating current section caught fire in September 2023 and spread to the cells of one Megapack module, also damaging the adjacent module. Both modules are being replaced by Tesla. Other 36 modules were operational a couple of days later.[53]
