Electric Vehicle Fires: A cause for concern?

Another car park fire, another day where claims concerning the dangers of electric vehicles (EV) are highlighted by some of the media. But is this concern justified and, do EVs pose a greater risk than internal combustion engine (ICE) driven vehicles?

A large fire occurred in October 2023 in one of the external car parks at Luton airport in England. Immediately after the fire, there were already rumours that the cause was potentially due to an electric vehicle. The fire brigade later confirmed it was caused by a diesel car which is suspected to be the source of the fire.

Despite EVs having been in commercial use for well over a decade, they appear to have recently gained notoriety for bursting into flames and appear to be judged by many as “riskier” than ICE vehicles. But does the data support this?
Firstly, the risk of EVs is different and there are valid concerns in relation to fire risks concerning batteries. To briefly summarise the fire risk, batteries have significant energy stored and under certain conditions can result in thermal runaway (such as when damaged, poorly maintained and/or due to an internal short circuit). Thermal runaway is where a chain reaction within a battery cell produces heat, which drives the temperature higher, causing further chemical reactions that create more heat which can rapidly result in a fire.

So, what does the data concerning EV and ICE vehicle fires indicate?

A report in May 2023 by the Swedish Contingencies Agency, found vehicles powered by ICE were twenty times more likely to catch fire than EVs in Sweden. However, reports such as this are still working with limited data and the sample size could be too small to make any concrete conclusions. Other research from EV fire safe based on a global study on EV battery fires for the period 2010 to 2020 indicates a rate of 0.0012% for passenger vehicle batteries catching fire compared to a rate of 0.1% for ICE passenger vehicles. Researchers from Auto Insurance EZ compiled data from the Bureau of Transportation Statistics and the National Transportation Safety Board which found that hybrid vehicles had the most fires per 100,000 sales at 3474.5, followed by 1529.9 fires per 100k for ICE vehicles and just 25.1 fires per 100k sales for EVs. As before, with any set of statistics a good measure of caution is required not only due to the limited number of data sets but also how these comparisons were conducted. For much of the data the cause of the fire is not commonly specified, maintenance is not consistent across all vehicles, and ICE vehicles are generally older.

Another question we should consider, are EV fires different from ICE vehicles? From two studies (one from Science Direct and the other from Hal Open Science) I was able to find, it appears that the overall heat released is similar and that an EV car fire is comparable to that of a conventional ICE car. This highlighted that combustion characteristics were determined by the typical materials within the car. A concern, however, is that with EVs reignition due to battery thermal runaway is possible and a significant challenge for emergency responders, particularly as large amounts of water are required to extinguish the battery pack once it starts burning (reports have indicated that extinguishment of fires in ICE cars require up to approx. 4,000 litres of water, whereas EV cars can require up to forty times as much).

With further advances in battery technology in the pipeline, including improvements of battery management systems and the potential introduction of solid-state batteries, the frequency of fires is likely to be even further reduced for EVs. However, if a fire does occur there remains a serious challenge in how to effectively extinguish it. This means that although the frequency of a fire occurring is less, the severity of an EV fire may be greater as has less chance of being extinguished.

With the above in mind, what can we cautiously conclude? The fire risk of EVs, based on available data, is far lower than compared with ICE vehicles. So hopefully this helps those who have been swayed by catchy headlines and allows for better debate of the fire risk EVs represent.

Author: Malcolm Chambers, Risk Management Group

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