Performance, CO2 emissions and more broadly, pollution levels … Electric cars and thermal cars are constantly compared. This time, researchers wondered what would happen if an electric car caught fire. Would it be more dangerous than in the case of a thermal car? The answer in video.
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They are more and more numerous on the roads of France and the world. With the diversification of the offer and the fall in prices, electric cars are gradually gaining a place on the market. This raises more and more questions about their performance or the pollution they generate. But also with regard to the risks they could represent in the event of a fire, for example. And in particular in a closed place, a road tunnel or an underground car park.
To find out more clearly, researchers from the Federal Laboratory for Materials Testing and Research (Empa – Switzerland) have deliberately set battery modules for electric cars on fire in a test gallery. More precisely, they simulated – at 1 / 8th scale – fires on a small electric car with a fully charged 32 kWh battery.
Tests in different conditions
First in conditions reminiscent of those of a closed car park, without mechanical ventilation. Then in those that may exist when the car park is equipped with a sprinkler system. Finally, under conditions similar to those of a fire occurring in a ventilated tunnel.
Empa researchers set out to analyze the distribution of soot on surfaces and on the protective suits worn by firefighters. They also studied the toxicity of residues on surfaces and in the water and possible corrosion-related damage, several months later.
This video shows the tests carried out on burning electric car batteries by researchers at the Federal Laboratory for Materials Testing and Research (Empa – Switzerland) in the test gallery in Hagerbach (Switzerland): flames of a meter long and huge amounts of thick black soot. © Empa
No more danger than with a thermal car
Differences were observed according to the scenarios. In the presence of a sprinkler system, for example, walls and ceilings were less affected by soot and smoke which concentrated on the floors. But more generally, from a thermal point of view, an electric car on fire does not represent more danger than a classic car also on fire. Even hydrofluoric acid – a particularly corrosive and toxic acid -, often considered a particular danger of burning batteries, remained in concentrations below the established critical values. And current ventilation systems have proven to be quite suitable for evacuating the fumes generated by an electric battery fire.
A sensitive point is however underlined by the researchers. The extinguishing and cooling water – which is used during firefighting, but also for storing the burnt battery – emerges highly contaminated. The chemical load of the extinguishing water even exceeds the Swiss limit values for industrial wastewater by a factor of 70. And the researchers even recorded a factor of 100 for the cooling water. It is therefore important that this water undergoes treatment before flowing into the network.
As for the restoration of the premises after the fire – we should even speak of decontamination – this should be carried out by fire cleaning professionals, equipped with suitable coveralls. “The soot emitted during such an accident contains large amounts of cobalt oxide, nickel oxide and manganese oxide. These heavy metals cause serious allergic reactions on unprotected skin, “said Lars Derek Mellert, a tunnel safety expert, in a press release from Empa.
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