Do electric vehicles catch fire when submerged in salty sea water? We look at the facts

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Do electric vehicles catch fire when submerged in salty sea water? We look at the facts

时间：2024-10-11 11:04 来源：未知作者：admin 阅读：次

Florida is no stranger to storm surges, which can inundate the land — and cars on it — with sea water.

As Hurricane Milton approached landfall in Florida earlier this week, electric vehicles (EVs) found themselves on trial.

Fears of EVs exploding when submerged in salt water raced ahead of the natural disaster, with town mayors and county sheriffs calling the cars "ticking time bombs" and urging owners to park them out of danger on elevated ground.

Social media, meanwhile, was awash with snarky memes mocking EV owners who'd have to evacuate areas without electricity.

Florida highway signage announces the impending arrival of Hurricane Milton.

Yet in Facebook groups such as the Florida Rivian Club, the story was very different. Owners of the Rivian large EV utes proudly posted photos of them skipping long queues for petrol or powering their homes with the cars' chunky batteries.

"I did feel like I was cheating when I drove past all of the people waiting in line to get gas and just pulled into a supercharger spot," Rob, an anaesthetist in Saint Petersburg, Florida, told the ABC.

"Most EV owners charge at home, so there's no scrambling to find gas when everybody starts evacuating."

These wildly diverging narratives are examples of the way "green" technologies intended to address the climate crisis, from EVs to wind turbines and solar panels, come under intense scrutiny during climate-charged disasters.

Do EVs explode when submerged in salt water?

They can catch fire, but not often.

Emma Sutcliffe is an EV battery fires specialist and the project director for EV FireSafe, a private company funded by the Department of Defence to research EV battery fires and advise emergency responders.

Lithium-ion batteries that power EVs can catch fire when submerged in salt water, Ms Sutcliffe said.

But this happens relatively rarely, and typically only when the battery has been submerged over days or weeks.

When hurricanes make landfall, their strong winds push water inland, causing an abnormal rise in sea level and extensive coastal flooding.

Prior to Hurricane Milton, there had been a total of 34 reports worldwide of EV battery fires following salt-water submersion — and of those, four were unverified, Ms Sutcliffe said.

Twenty-eight occurred due to hurricanes, one during a very violent storm, and five when EVs were accidentally submerged at boat ramps.

Whether a submerged EV catches fire depends on its battery chemistry, battery size, how much charge it held at the time, and whether the car was damaged.

EV batteries comprise thousands of interconnected cells filled with an electrolyte solution. Salt water can corrode the walls of these cells and the electronics between them, and when it drains away, leaves a path of salt crystals.

These crystals conduct electricity, which can cause the battery to short circuit and heat up.

This triggers a chemical reaction within the battery, further pushing temperatures higher in a process called "thermal runaway".

The result can be a melted wreck.

Whether an EV catches fire can also depend on how responders remove the car. If they tow it with its wheels turning, this can generate power and recharge the battery. If the battery cells are damaged, this kick of electricity may be enough to start a fire.

Ms Sutcliffe said EVs were not necessarily more dangerous than internal combustion engine vehicles during natural disasters such as hurricanes.

"All vehicles have their own challenges, but we're more used to internal combustion. This is a new thing we're learning with EVs."

Is the risk of exploding EVs exaggerated?

This is a trickier question to answer.

The risk of submerged EVs catching fire is fairly low.

When Hurricane Ian hit Florida in 2022, about 1 per cent of submerged EVs caught on fire, according to a recent report by the Idaho National Laboratory.

But there's still a risk it will happen. Ms Sutcliffe said US authorities were right to warn the public.

"The information coming from authorities in the US is valid but it's just an 'alert, but not alarmed' issue."

Sandbags were distributed by residents of Miami in anticipation of a storm surge caused by Hurricane Milton.

Others say EV fires are getting more attention than they deserve.

Footage of a Tesla bursting into flames during flooding brought on by Hurricane Helene last month has been shared thousands of times on Facebook.

Right-wing news sites such as Breitbart and the Epoch Times claimed hurricanes Helene and Milton are exposing the shortcomings of EVs, and highlighting the risks of the broader clean energy transition.

John Higham, chair of the US EV Association, said "clickbait" stories about isolated reports of fires are fanning the flames of anti-EV sentiment.

"Mostly it's due to the ignorance of people who are generating these stories," he said.

Can EV owners evacuate?

What about when the power goes out? Are EV owners simply stuck?

The satellite image below shows Hurricane Helene's path of destruction, knocking out power as it made landfall in Florida's Gulf Coast and tracked north.

Before: The view of the US southeast region at night before Hurricane Helene.. . After: And immediately after Hurricane Helene.. .

Instructions: Use left and right arrow keys to control image transition

Before and after images

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The view of the US southeast region at night before Hurricane Helene. / And immediately after Hurricane Helene.

But the US EV Association is currently polling members and so far has heard no reports of EV owners stuck on the roadside with an empty battery.

"If they know the hurricane's coming, they charge the EV up," Mr Higham said.

"And modern EVs have 200 to 300 miles (320 to 480 kilometres) of range."

Florida deployed pop-up diesel-powered EV fast chargers along Hurricane Milton evacuation routes.

Still, EV owners who do not evacuate could potentially face trouble charging their vehicles once the power grid inevitably fails after the worst of the hurricane has passed.

Rob, the anaesthetist in Florida, planned to work rather than evacuate.

"What does worry me is the ability to charge the car after the storm," he said on Wednesday night (Australian time), hours before Hurricane Milton hit the coast.

"If there are widespread power outages hopefully I have enough charge to get me home."

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Do electric vehicles catch fire when submerged in salty sea water? We look at the facts

Do EVs explode when submerged in salt water?

Is the risk of exploding EVs exaggerated?

Can EV owners evacuate?

Before: The view of the US southeast region at night before Hurricane Helene.. . After: And immediately after Hurricane Helene.. .

Science in your inbox

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