2023-11-10 16:27:03
Electric car fires often make headlines, but they are not common.
According to Honeywell Safety and Productivity Solutions, 239 fires recorded in the UK between July 2022 and June 2023 were related to electric vehicles.
While this is an 83% increase year on year, it is important to note that the number has increased alongside the growing presence of electric vehicles on British roads.
A study by the Swedish Civil Contingencies Agency also revealed that gasoline and diesel cars caught fire 19 times more often than electric vehicles.
Why do electric car fires attract so much attention?
Electric car fires are attracting increasing attention for many reasons. The technology is new and newsworthy; and are complex and often heralded by a highly toxic vapor cloud accompanied by hissing and highly directional jets, possibly followed by an explosion.
Electric car fires are also incredibly difficult to put out. You think it’s gone and then it flares up again hours, days, or even weeks later.
Considering all this, it’s no wonder people are worried about electric car fires, especially those who have to put them out.
How do firefighters deal with electric vehicle fires?
Fire services are developing new strategies to deal with electric car fires.
For example, one Fire and Rescue Service has announced that, following any incident, traffic collision or fire involving an electric vehicle, “one of our fire trucks will follow the recovery vehicle to the unloading point in your yard to help with any fire.”
It also said it has developed a system that allows fire crews to identify which model of electric vehicle is involved in an incident and where its battery and isolation switches are.
Experts are divided on the best way to deal with an electric vehicle fire, but in general, immense amounts of water are needed to cool the battery pack (although this will not prevent the fire from breaking out again), a fire blanket to put out the flames and breathing equipment for firefighters. protecting them from the toxic vapor cloud is the standard approach.
Either that or just let the fire go out on its own.
Trying to put out the fire with inert gases is ineffective because, being a chemical fire, it does not require oxygen.
In the meantime, the surroundings should be checked for discarded battery cells that could have been ejected from the battery pack by an explosion and could ignite spontaneously later.
After containment, the burned electric vehicle must be removed and deposited in an area away from buildings and other vehicles. (About 25% of junkyard fires are caused by spent lithium-ion batteries.)
More radical measures include submerging the car in water, although not in seawater, because chlorine gas could be released.
Does fire risk mean electric cars are unsafe?
It all sounds pretty alarming and a good reason not to buy an electric car, but Paul Christensen, professor of pure and applied electrochemistry at Newcastle University and senior adviser to the National Fire Chiefs Council, is keen to calm fears about safety. fire prevention of electric vehicles, especially given the benefits that the technology offers.
“As someone who helped Nissan during the creation of its battery plant, if I could afford it, I would have a Nissan Leaf tomorrow,” he says. “We should not worry about the small incidence of fires involving electric vehicles, but we should be aware.
«A lithium-ion battery stores a huge amount of energy in a very small space. Since 2008, the adoption of these types of batteries has surpassed our appreciation of their risks. “We are racing to catch up, but we will get there.”
As part of his campaign to improve awareness of the fire risk of electric vehicles among first responders, Christensen has so far made presentations to 30 of the UK’s 50 fire services, as well as fire services in Europe, Australia and New Zealand.
He begins each talk by describing the structure of a lithium-ion battery cell. A sliver of aluminum, called a cathode, is coated with a mixed metal oxide ink.
It is accompanied by a graphite-coated copper slice called the anode. Among them is a fragile, perforated plastic separator soaked in an organic solvent containing a small amount of additives whose identity, worryingly, is known only to the cell manufacturer.
Depending on whether the battery is charging or discharging, lithium ions move to or from the cathode and anode.
Then the professor gives the first surprise to his audience of firefighters. Full, a cell contains 4.2 V of charge, but even when empty, it still has 2.5 V. A Nissan Leaf has about 192 cells in 24 modules and a Tesla Model S more than 7,000 in 16 modules.
That’s a lot of power when the car’s power gauge says it has none.
Full or “empty,” the risk of this energy escaping uncontrolled is what some scientists believe leads to “thermal runaway,” when heat and gases fuel even higher temperatures and even more gases, including hydrogen. and oxygen, in a process of self-control. performing the cycle until the cells begin to burn and burst.
A cloud of toxic vapor is formed that carries the risk of deflagration. Once thermal runaway has started, no battery management system or circuit breaker can stop it. “A battery fire can be controlled, but it cannot be extinguished,” says Christensen.
It has shown in tests how puncturing or otherwise damaging a battery pack, such as in an accident, can cause it to catch fire. “If the battery case of an electric vehicle is dented, you have to assume that it is dangerous,” he says.
Battery packs have been known to catch fire from overheating and while charging. What is more worrying is that a fire in a battery can spontaneously erupt, with one possible explanation being contamination of even a single cell during its manufacturing.
“Even the most experienced and careful manufacturers have defective electric cells that pass through their careful quality control systems,” says Christensen.
A battery flame is like a blowtorch that quickly ignites anything in its path, so Christensen wants city councils and other organizations to consider the safety risks of electric vehicles in underground car parks as well as bus stations. where vehicles are parked side by side.
“Three bus stations have burned down in Germany in the last six months,” he says. “Tunnels, ferries, car parks, cargo ships carrying electric vehicles – all places where electric vehicles are located should be considered a safety risk and appropriate measures should be taken.”
He’s also concerned about classic cars being converted to run on used lithium-ion batteries. “No one really knows how safe used lithium-ion batteries are, and no standard test has yet been devised to indicate this,” he says.
“Some batteries re-enter the market after being removed from illegal workshops. How safe are they?
“There is a lot of research into the safety of lithium-ion batteries, but everyone needs to come together, because right now we are at the end of a very steep learning curve.”
When all else fails…
For electric cars that are on fire or at risk of being on fire, the fire service in Copenhagen, Denmark, has developed a truck-mounted vehicle containment solution.
The smoking electric vehicle is lowered into the container, which, like a shipping container, is then loaded onto a flatbed truck. Nozzles on the floor and sides of the container allow water to be pumped into it.
Once full, the container and car are taken to a secure storage area and left, possibly for weeks, until the vehicle is no longer a hazard. If all goes well, the water is filtered and treated for safe disposal.
In Europe there is a proliferation of Chinese EVs, many of them at affordable prices, which are slowly flooding the market, with models that are not as safe as those manufactured in Europe. Some Chinese cars come disguised under well-known models, such as Polestar or Volvos, which are manufactured in China under the tutelage of the parent automaker, Geely.
Europeans, for now, trust Tesla or Volkswagen, which are the manufacturers that sell the most electric cars.
European countries and the use of electric cars by country compared to the US.
The highest percentages were found in Norway (89%), Sweden (58%) and Iceland (56%). Germany, France and Norway together accounted for around 64% of all new BEV registrations between EU-27 countries and non-EU EEA countries.
Norway had the highest number of new BEVs registered in 2022, accounting for 79% of new car sales.
Source: Coach- Wikipedia
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