March 23, a 38-year-old man driving a Tesla Model X rammed headfirst
into an unshielded highway median while traveling south on U.S.
Highway 101 near Mountain View, California. Two other vehicles
subsequently rear-ended the SUV, which caught fire after the driver,
who later died from his injuries, was pulled from the wreckage.
to news reports, the car blaze shut the highway for 5 hours,
firefighters required special suits for cleanup, and at one point
had to call Tesla for help in containing the blaze. On Tuesday
(March 27), the U.S. National Transportation Safety Board (NTSB)
announced a field investigation into the incident.
we have an electric vehicle involved in a postcrash fire. … Did the
batteries play a role in that? Did the batteries make it harder for
the fire to be put out?" NTSB spokesman Chris O'Neil told The
are all excellent questions that Tesla drivers might be itching to
are Teslas more
likely to catch fire than other cars? And when they do catch fire,
why are they such a nightmare to put out?
limited available data suggest that electric vehicles are not more
prone to battery fires — but their lithium-ion batteries can fuel
hotter fires that release toxic fumes and are harder to extinguish,
Surprising Physics of 7 Everyday Things]
batteries that fuel a typical gasoline-powered car differ from those
in an electric vehicle. The former are lead-acid-based, with lower
energy densities — meaning they carry less energy in the same amount
of space — than the compact,rechargeable lithium-ion, or Li-ion,
batteries that power
electric vehicles, including the Tesla Model X.
normal 12-volt "small" gasoline-powered car battery provides roughly
0.5 kilowatt-hours (kWh) of energy. Since the fully electric battery
in the Model X comes with 75- to 100-kWh batteries, this means
roughly 150 to 200 normal car batteries would be needed to power the
difference between the battery you might jump in a gas-powered car
and the one you'd find under a Model X hood is that, while lead-acid
batteries can self-ignite with small fires, those can't leap into
other parts of the battery to ignite them and cause a chain
reaction. This can happen in lithium-ion batteries, however, said
Peter Sunderland, a professor of fire protection engineering at the
University of Maryland. Sometimes, when a Li-ion battery gets
damaged, it shorts. The resulting spark might ignite the nearby
lithium, and the lithium next to that, until the whole battery is
trick with designing an EV battery, in particular, is balancing the
benefits of higher
energy density — which enables the EVs to go
farther on each charge — with the associated risks of battery
sparking. "Higher energy density means a higher risk of external
sparking,"Arunachalanadar Mada Kannan, a professor of engineering at
Arizona State University, told Live Science.
often in EVs, however, lithium-ion
battery fires happen due to thermal runaway,
or the spontaneous explosion of the battery thanks to a buildup of
heat in the cells inside. In its recent blog post, Tesla noted that
the battery packs in the company's electrical vehicles were designed
with firewalls, so that a fire would spread slowly enough to give
the driver time to exit the car.
battery fires can be very intense, emitting large amounts of heat
and smoke or gas, Bengt-Erik Mellander, a professor of subatomic and
plasma physics at Chalmers University of Technology in Gothenburg,
Sweden, told Live Science in an email.
recent high-profile Tesla fires have started after the battery was
damagedin some way.
crash in Mountain View was very violent, chopping off the front end
of the car and severely damaging the front end of the battery
storage under the car (as far as I can see)," Mellander wrote. In
the 2013 fire, the Model S's battery compartment was also damaged
prior to the fire, when an errant metal object hit the
return of an old debate
recent Model X crash has brought back the debate on whether electric
vehicles (EVs) are saferthan gasoline- and diesel-powered
vehicles when it comes to car fires. (Separately, investigators are
asking whether the Tesla's
semi-autonomous Autopilot mode contributed to the crash.)
isn't the first time a Tesla has caught fire. In 2013, a Tesla Model
S driving near Seattle experienced an unexpected fire in its car
battery. Videos and images of the fiery inferno splashed across
media outlets, and Tesla's stock took a tumble before company CEO
Elon Musk swooped in to assuage consumer concerns. In
his blog, Musk did some quick calculations to determine that
"You are 5 times more likely to experience a fire in a conventional
gasoline car than a Tesla!"
fact, the limited statistics available suggest electric vehicles are
not more prone to fires, Mellander noted.
order to further minimize risks, however, "something needs to be
done at the level of the manufacturing plant, where these batteries
are being made," Sunderland said. "Better quality control, better
research and development to make sure the battery materials are up
electric cars may not be more fire-prone, "the risks and the
strategies to use in case of an accident and a subsequent fire are
different to that of fires in conventional cars," Mellander said.
agreed. While firefighters know how to handle gasoline fires, these
personnel are not as well-trained in dealing with electrical
emission hazards. "With a gasoline fire, they know if they get
enough water on it, it'll go out," he said. "But with a deep-seated
fire, it's hard to spray the water deep enough into the battery to
stop the fire."
reported that the firefighters who attempted to put out
the 2013 Model S car fire in Seattle had trouble and "ended up using
a circular saw to cut a hole that would allow them to pour water
directly on the battery."
a fiery Tesla crash into a barrier in Austria, the car kept
reigniting, forcing firefighters to battle the flames for hours. The
car had to be put into quarantine for 48 hours to remove the chances
of reignition, Jalopnik
more, lithium-ion fires can release high levels of "toxic gases"
such as carbon monoxide, soot, hydrogen fluoride, and particulates
of oxides of nickel; aluminum; lithium; copper; and cobalt, according
to a Tesla Model X emergency response guide. As a result,
firefighters need to wear a self-contained breathing apparatus and
should use hoses that spray fog and special ventilation fans that
push air out at a high velocity to protect bystanders downwind of
the fire, according to the guide.
need more training, but the reality is that fires in electric
vehicles don't happen that often, Sunderland said.
if many more electric vehicles take to the roads in the future,
these fires could become more common, and firefighters will need to
know how to safely extinguish them.