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Why AZ fire department plans to bury burning electric vehicles

Posted at 10:36 PM, May 22, 2023
and last updated 2023-06-12 13:03:57-04

As electric vehicle sales have surged, so have concerns about the dangers of EV battery fires, which are more difficult to extinguish than traditional car fires.

After a Tesla crashed into a North Valley building in late February, witness Alexandra Toepel told ABC15 "It went up in flames in like 30 seconds."

The young Tesla driver and her mom escaped unharmed, but Toepel remembers it as "a really scary moment."

Firefighters say it can take longer to put out EV fires than traditional car fires.

"It's all about chemistry and fire science," said Assistant Phoenix Fire Chief Tim Kreis.

The encased lithium-ion battery packs can go into what's known as a thermal runaway.

"The batteries generate their own heat and their own oxygen," said Andrew Klock, senior manager of education and development for the National Fire Protection Association.

Experts say EV fires aren't necessarily more dangerous, but they do have to be treated differently. Firefighters must take precautions to avoid electrocution and toxic smoke. They must also be cognizant of the lengthy time it takes to sufficiently water cool the battery packs.

Some companies are developing new EV firefighting tools to improve safety and efficiency.

Rosenbauer's battery extinguishing system technology [BEST] includes a tool to puncture the bottom of the battery housing so water can be applied directly from underneath the vehicle.

Bridgehill, a Norwegian company, says its reusable, car-size fire blankets can isolate and extinguish EV fires in minutes.

Even after the fire seems to be out, battery-powered cars have the potential to reignite hours or days later.  

At the Lucid electric car manufacturing facilities in Casa Grande, employees have dealt with a couple of thermal runaway battery fires, according to city fire department records.

"There are fire blankets that are on site, and they take that fire blanket and smother it," said Casa Grande Fire Chief Dave Kean. "After they smother the fire, the next thing that happens is [the battery] goes into a tank - a water tank." 

The Phoenix Fire Department is putting a twist on the water tank concept.

When a Waymo car caught fire this month, firefighters doused it with water. Then they brought in a dumpster, placed the Waymo car inside, and covered it with sand.

"If it was to go into a process with thermal runaway a day later, a week later, it's contained in a safe sort of way," said Kreis.

Burying a car to prevent a fire from reigniting may seem extreme, but Phoenix fire officials say it's the safest option.

While EV fires are rare, a 2021 Highway Loss Data Institute study looked at insurance claims and found EVs don't catch fire any more often than traditional cars.

"It is absolutely safe to park your EV in your garage," added Kreis.

Kreis says numerous items in most homes like e-bikes, power tools, and computers already have similar, but smaller, lithium-ion batteries.

While electric vehicle fires are unusual now, the number is expected to grow as more people buy EVs, and the fleet on the roads today age. Older vehicles are more prone to fires. 

Auto industry experts estimate 7% of new vehicles sold in early 2023 were all-electric.