Are London’s buses spontaneously combusting due to electric batteries?

We came across the following post on the social communication app Telegram:

The post contains a link to an article from the news site The Expose titled ‘London’s spontaneous bus combustion: How is this being allowed to happen?’. We also found this article published on other sites such as The Liberty Beacon, and USSA News, as well as on the social media platform X (formerly Twitter).

The Expose, The Liberty Beacon and USSA News are all rated by the media credibility resource Media Bias/Fact Check as sources with poor records of factual reporting that regularly promote conspiracy theories. We previously encountered an article from The Expose that was critical of electric vehicles, but also factual.

The Expose’s article about London buses’ ‘spontaneous combustion’, while not immediately evident from the headline, is also critical of electric vehicles (EVs). This becomes clear when reading further into the article.

The Expose claims that ‘in the past couple of years’, there had been a series of fires involving electric vehicles around the world. It said data from the London Fire Brigade for 2019 showed ‘an incident rate of 0.04% for petrol and diesel car fires, while the rate for plug-in vehicles is more than double at 0.1%’.

The article explains that ‘the real danger with electric vehicles is the lithium-ion batteries which are prone to catching fire unexpectedly or exploding and the ensuing inferno is very hard to put out’. It also criticises the ‘insane and economically disastrous net zero target by 2050’ of the UK in giving up fossil fuels, and suggest that these ‘vested interests’ are obscuring the cause of these fires.

The article also pointed out that ‘approximately 56% of London’s bus fleet is “environmentally friendly”’, before listing incidents of buses catching fire spontaneously.

Thermal Runaway

The Expose’s report about the risks of lithium-ion batteries is partly accurate. We could not find information that supported the claim that lithium-ion batteries are ‘prone to catching fire unexpectedly or exploding’.

However, lithium-ion batteries can spontaneously combust in a process called thermal runaway, which can result in high temperatures, violent cell venting (where the contents of the cell are ejected at high speed), smoke and fire.

The risk of this happening is higher in batteries of poor quality, which are more likely to contain defects. External conditions such as age, overcharging, short-circuiting and excessively hot or cold temperatures can also raise the risk of thermal runaway.

Lithium-ion batteries also use materials that are flammable at high temperatures, and these can cause fires in EVs if the battery is damaged during a vehicle accident.

Causes of Fires Undetermined

In the article, The Expose lists several incidents of vehicle fires which it appears to attribute to the lithium-ion batteries. Apart from a report on a spate of e-scooter fires in India, the fire in each case was still under investigation.

While electric or hybrid vehicles with lithium-ion batteries were involved in these incidents, the batteries had not been determined to be the causes of the fires. However, due to damaged lithium-ion batteries igniting vigorously, they were in some cases suspected to have propagated the fire and made it more difficult to extinguish.

When limited for cases of bus fires in London, 6 cases are listed in the article covering a period from 2022 to 2023. These fires transpired in Potters Bar, Brixton, Marylebone, Hackney, Croydon and Bradford.

We investigated the details In each case and found that for all the cases, the cause of fire was not listed, undetermined, or still under investigation. In the case of the Potters Bar fire, which involved 4 diesel-powered buses and two electric hybrid buses at a depot, Transport for London recalled at least 90 electric buses while the cause of fire was being investigated.

No Rise in Fire Frequency

As The cases listed by The Expose were inconclusive in linking electric batteries to a supposed rise in fires on London buses, we investigated data provided by the London Fire Brigade (LFB) to determine if there was any truth in the claims.

A response from the Mayor’s office of London using LFB’s data indicated that bus fires involving hybrid engines or electric batteries had risen from 2021 to 2022. This data was backed up the LFB’s database on Lithium and Electric Vehicle fires, which showed an increasing trend, and the majority of fires occurring in the last 2 calendar years.

However, the data from the Mayor’s office also showed that the number of bus fires, regardless of fuel type, had been fairly consistent in the last five years.

Moreover, data from London’s bus fleet indicates that the fleet has added more hybrid and electric buses in recent years, while no diesel buses have been registered in the last three years and appear to be in the process of being phased out.

With a larger proportion of London’s buses being hybrids and EVs, more of them will be involved in fires involving buses in London. However, there does not appear to be a sudden rise in the rate of bus fires.

Fire Risk in EVs, Hybrids and ICE Vehicles

As the data from London proved inconclusive, we took a broader look at information from around the world to compare the fire risk between vehicle fuel types.

An analysis of data from the US National Transport Safety Board, analysed by the insurer Autoinsurance EZ, found that hybrid cars were more prone to fires than ICE cars, but that electric cars had a lower fire risk.

While the sample size for newer vehicle fuel types is too small to make definitive judgments, the finding that EVs are less prone to fires is backed up by other research findings and expert opinions.

EVs do not have the fire risk that leaking brake fluid poses when contacting with exhaust, which is a major causes of spontaneous fires in ICE vehicles. Moreover, fire risks in EVs are expected to lessen further as battery technology improves.

On the other hand, hybrids may be more prone to fire due to the need to densely package ICE and EV components on one vehicle, leading to poorer thermal management. Batteries in hybrids are also subjected to higher wear than in EVs, leading to faster formation of potential defects.

Data from Norway, Sweden, Australia and the automaker Tesla all support the finding that EVs were less prone to fires. In Norway, which has the world’s highest proportion of electric car sales, there are between four to five times fewer fires in EVs.

The Explosive Caveat

While EVs have lower fire risk than ICE vehicles, they pose more challenges once on fire due to the chemistry of their batteries. Burning lithium-ion batteries can burn three times hotter and are more likely to reignite after being extinguished initially, leading fire services around the world to have to adapt new techniques to fight EV fires.

Gases that emit from damaged battery cells can also be toxic and explosive, causing ‘vapour cloud explosions and rocket flames’.

These explosive events have accelerated dis/misinformation around electric batteries as they become increasingly common in consumer technology products, such as e-bikes and e-scooters that became highly popular during Covid-19 lockdowns.

Lithium-ion batteries in cheap consumer technology products are also often unregulated and of poor quality, resulting in fire incidents. As batteries for these products have different quality standards to EV batteries, comparisons between them may not be accurate.

False Alarm

While researching this story, we found other instances when disinformation about EV fire risks had gone viral recently. Politifact in October 2022 debunked a viral Instagram post that claimed EVs’ batteries made them more likely to catch fire than gasoline-powered cars.

Our past factchecks have revealed that The Expose reported selectively on negative stories about EVs, and we found that it also promoted conspiracy theories.

While The Expose’s headline about London buses spontaneously combusting appears at first glance not to make any contentious claims, the text of the article clearly insinuates that the rising use of electric vehicles has led to a rising trend of London bus fires.

This suggestion is not supported by the data. While hybrid vehicles are more prone to fire than conventional vehicles, and electric batteries burn much more fiercely than fossil fuels, it is false that electric batteries are more prone to fire and responsible for recent trends in bus fires in London. There also do not appear to be any major shifts in fire trends for London buses.

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