As more electric cars take to UK roads, attention is turning to their safety, in particular fire safety.
No matter that petrol and diesel cars can catch fire and many of them do (remember the spate of Vauxhall Zafira fires not so long ago?), an electric vehicle fire (there were 54 in London in 2019) commands a lot more attention. A few reasons: the technology is new, so newsworthy; EV fires are complex and often heralded by a highly toxic vapour cloud accompanied by a hissing noise and highly directional jets, followed, possibly, by an explosion; they can occur spontaneously; and putting out an EV fire is virtually impossible. You think it’s out and then it erupts again hours, days or even weeks later.
All this considered, it’s no wonder people are becoming concerned about electric car fires, not least those who have to put them out. Thankfully, fire services are developing strategies to deal with them. Bedfordshire Fire and Rescue Service, for example, has announced that in the aftermath of any incident, road traffic collision or fire involving an EV, “one of our attending fire engines will follow the recovery vehicle back to the unloading point at their yard to assist with any fires”. It also said it has developed a system that enables fire crews to identify what model of EV is involved in an incident and where its battery and isolation switches are.
Experts are divided on how best to tackle an EV fire but, generally, immense quantities of water to cool the battery pack (although this won’t prevent fire erupting again), a fire blanket to suppress the flames and breathing equipment for the fire fighters to protect them from the toxic vapour cloud is the standard approach. Either that or simply let the blaze burn itself out. Attempting to suffocate the fire with inert gases is ineffective because, being a chemical blaze, it does not require oxygen. Meanwhile, the surrounding area must be checked for discarded battery cells that could have been propelled from the battery pack by an explosion and might spontaneously ignite later. Following containment, the burnt-out EV must be removed and deposited in a compound away from buildings and other vehicles. (Some 25% of scrapyard fires are caused by spent lithium ion batteries.) More radical steps include immersing the car in water, although not sea water because chlorine gas can be released.
It all sounds quite 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 advisor to the National Fire Chiefs Council, is keen to quell fears about EV fire safety, especially given the benefits the technology offers.