UK Environment Secretary Proven Wrong On EV Tires & Brake Pollution
UK Environment Secretary George Eustice made some notable comments recently that got picked up by The Daily Mail. These comments were about EVs, that they produce more fine particulate matter through brake and tire pollution than traditional ICE vehicles. Speaking to MPs on the Commons’ environment, food, and rural affairs committee last month, UK Environment Secretary George Eustice claimed that fine particulate matter might be worse with EVs due to their weight, The Daily Mail reported.
The RAC, which was initially founded as the Automobile Club of Great Britain and is currently working to speed up the adoption of electric vehicles, commissioned Dr. Euan McTurk, a leading battery electrochemist, to address Eustice’s remarks.
Eustice said to the committee:
“The unknown thing at the moment is how far switching from diesel and petrol to electric vehicles will get us. There is skepticism. Some say that just wear and tear on the roads and the fact that these vehicles are heavier means that the gains may be less than some people hope, but it is slightly unknown at the moment.”
According to The Daily Mail:
“This means the gains from switching to electric cars from petrol and diesel ones ‘may be less than some people hope’ because of particles they create which do not come out of the exhaust.”
Debunking the “EV Brakes Cause More Pollution Than ICE Vehicle Brakes” FUD
Eustice noted that wear and tear from brake linings and tires on the road might be more with EVs than ICE vehicles due to how much the batteries in EVs weigh. This, he said, generates more polluting fine particles.
Dr. McTurk not only addressed the claims made by the UK Environment Secretary but debunked them in his report. The report discussed brake particulate matter, noting that although all vehicles produce particulate matter dust in the process of slowing cars down, while the overwhelming majority of EVs use regenerative braking which reduces the use of the mechanical brake discs and pads while adding more range to the vehicle. He said:
“In EVs, the overwhelming majority of braking can be done via regenerative braking. This is where the electric motor works in reverse, converting kinetic energy from the moving vehicle into electricity, which is used to charge the battery when slowing down. This not only reduces the use of the mechanical brake discs and pads, but adds more range to the vehicle, too.
“Such is the strength of regenerative braking that Volkswagen has switched from brake discs and pads, to brake drums, on the rear of its ID series of EVs, and on other EVs using its modular electric drive matrix (MEB) platform like the Skoda Enyaq. Most car manufacturers prefer brake pads and discs for their petrol and diesel cars because the latter is exposed to the elements and therefore dissipates heat better during repeated braking.”
Dr. McTurk also noted that EV brake pad lifespans can last up to 100,000 miles. As an example, he pointed to Dundee Taxi Rentals.
“High mileage electric vehicle fleets across the country will testify to the reduced wear and increased lifespan of brakes on EVs compared to those on petrol or diesel vehicles. A perfect place to start is in Dundee, a city that has thoroughly embraced EVs. Ryan Todd, director of Dundee Taxi Rentals — one of several electric taxi fleet operators in the city — notes that his 11 electric Nissan Leaf taxis typically have a brake pad lifespan of 80,000 to 100,000 miles, with discs typically being changed because of warping rather than wear.
Zwith little thought given to brake wear or efficiency. Such is the reduction in particulate matter from EVs versus diesel cars – not just from brakes, but from exhaust emissions too – and such is the extent that Dundee has embraced electric taxis, cars, buses and vans, that in 2018, Dundee city centre met key air quality targets for the first time, as a direct result of the city’s switchä to EVs.”
Cleevely EVs, he pointed out, is a well-known EV mechanic in the UK and often sees EVs with brakes that have lasted over 100,000 miles. Cleevely EVs noted that they usually have to replace brakes on EVs because they seize up due to lack of use — not because of wear and tear.
Debunking the “EV Tires Cause More Pollution Than ICE Vehicle Tires” FUD
Dr. McTurk noted that a source of particulate matter pollution from EVs is the tires, but that the idea that EV tires cause more pollution than typical ICE vehicle tires just doesn’t make sense. He cited a report by Emissions Analytics that suggested particulate matter pollution from the wear and tear of tires is 1,000 times higher than car exhaust emissions. The report also said that tires may produce up to 9.28 grams of particulate matter per mile. However, Dr. McTurk shared calculations that disproved this.
“A typical 16” family car tyre weighs around 9 kg, so four of them on a vehicle gives a total weight of 36 kg. That’s not just the tread, but the full tyres. If the car really did shed 9.28 grams of particulate matter per mile from the tyres, then the car tyres would physically have disappeared — and the car would be running on its alloys — in less than 4,000 miles.
“In reality, the tread of a tyre is about 35% of the tyre’s total weight, so the tyres would be bald in less than 1,358 miles, or two months’ worth of driving for the average UK driver. Chances are that the Emissions Analytics study was accidentally measuring particulate matter emitted by other cars, that had settled on the road and then been kicked up by the tyres of the test car, rather than what was being shed from the tyres of the car undergoing the test.
“So, we now know that tyre wear is nowhere near as big a contributor to particulate matter emissions as the Emissions Analytics’ report claimed. However, if electric vehicles are heavier than petrol or diesel cars, do they wear out their tyres faster? Firstly, modern electric vehicles aren’t actually that much heavier than many modern petrol or diesel cars, especially with the recent trend towards bigger and heavier SUVs.”
For more, you can read the full report here.
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