Watch: French electric bus bursts into flames—the model is now taken out of service

This is a Bluebus 5SE electric bus from the supplier Bollore that caught fire in Paris. Illustration: Screenshot/youtube

An odour of molten plastic spreads as sparks, flames, and thick black smoke erupt from the burning bus across the street. This is how France 21 describes the fire that broke out in one of the electric buses in Paris on a Friday morning this spring.

“The bus driver immediately evacuated all the passengers, and no one was injured,” said RATP, Paris bus operator.

The electric bus in question was a Bluebus 5SE model from the supplier Bollore. Earlier this month, a fire had broken out in another bus of the same model, so RATP decided to take all of the city’s 149 Bluebus 5SE buses out of service.

At present, it is unclear why the French buses have caught fire, but it is technically possible for a battery cell to burst into flames if there is a random hidden material defect. However, this happens very rarely.

“The chemical process in the battery can short circuit due to too high a temperature. It provides a lot of heat that might spread to neighbouring cells. If the battery pack is properly built, there is no problem, but if the structure allows the warmth to spread to other cells, then there could be a chain reaction that leads to the battery burning out,” explains Kjeld Nørregaard, senior project manager at the Danish Technological Institute.

No greater risk with electric buses

Kjeld Nørregaard emphasizes that there is no reason to believe that electric buses should generally pose a greater risk than diesel buses. He has no concrete figures for fires in electric buses, but a recent Norwegian study concluded that the probability of fire in electric cars is lower than in conventional cars.

The battery technology in electric cars and electric buses is comparable, but battery packs in electric buses are significantly larger and more complex. A more robust and safer battery type is often used in electric buses. Bus manufacturing typically takes place in smaller series with a little more custom work than mass manufacturing of passenger cars.

“We can therefore not apply electric car statistics directly on electric buses, but that does not mean that the risk is greater with electric buses. Diesel buses can also burn, as we have seen in Copenhagen, among other places,” Kjeld Nørregaard says and refers to the incident in which a diesel bus caught fire in the middle of Frederiksberg earlier this year.