The Largest Lithium-Ion Battery in the World Keeps Melting

Ten battery packs melted in an energy storage facility in California, the second meltdown in five months.
Tesla Megapack batteries at the Elkhorn Battery Energy Storage System next to the Vistra Moss Landing natural gas fired power plant in Moss Landing, California, U.S. Getty Images ​
Tesla Megapack batteries at the Elkhorn Battery Energy Storage System next to the Vistra Moss Landing natural gas fired power plant in Moss Landing, California, U.S. Getty Images

The largest lithium-ion battery in the world experienced a meltdown over the weekend, its second in five months. 

An energy storage facility owned by Vistra Energy in Moss Landing, California, triggered fire alarms on the evening of Feb. 13. Four fire trucks responded to the event and found around ten battery packs in the facility melted entirely, according to local broadcaster KSBW. 

“The building’s systems contained the event without the need for outside assistance,” the company said in a Feb. 15 statement on the outage. “There are no injuries to personnel. An investigation is underway to determine what caused the safety system to activate. While this is in its very early stages, what we know is the water-based suppression system released water that contacted some batteries.” 

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Though it’s too early to know how the meltdown started, North Monterey County fire district chief Joel Mendoza told KSBW that the facility’s fire suppression system was activated and had successfully cooled the batteries when his team arrived on the scene "to the point that there wasn't any flame or fire.

This is the second time in five months that the 300-megawatt facility has gone offline due to battery issues. The plant was less than a year old when the first incident took place in September, setting off sprinklers that damaged around 7,000 batteries, or 7 percent of the facility’s nearly 100,000 battery modules. 

The energy generation company said in a release issued months after the September meltdown  that the facility’s fire management software detected low levels of smoke in one area of the facility due to a "failed bearing in an air handling unit," the company wrote, which armed the heat suppression system that, due to "failures of a small number of couplings on flexible hoses and pipes, sprayed water directly on a number of battery racks, causing some to overheat. This created more smoke, which generated more water, and so on. 

In its statement regarding the latest meltdown, Vistra Energy said there are early indications that the September incident repeated itself. "There is early evidence that water hoses leaked and that some batteries shorted, creating smoke in the building, similar to what we observed with the September incident at our 300-MW Phase I facility next door," the release states.

The most recent incident highlights how fragile battery storage systems are: Lithium-ion batteries ignite easily and the fires they generate are difficult to contain. Water only reacts with lithium—it doesn’t put lithium fires out. This poses problems for energy storage companies like Vistra, which are crucial to the renewable energy transition. 

“The Moss Landing Energy Storage Facility is playing a key role in helping California achieve lower emissions and improve grid reliability, and systems like these will become more necessary as additional renewable power is integrated into electric grids across the US,” Vistra chief executive Curt Morgan said in a January release on the facility’s last meltdown. 

In large facilities, any number of factors can create a cascading incident like Sunday’s meltdown. Vistra has embarked on an investigation into the source of this one, the company said in a statement. The facility remains offline in the meantime.