I read an article earlier today that I found very confusing. An article at Green Car Reports said that some European regulators think EVs shouldn’t be exempted from emissions standards, because they might be emitting more brake dust than conventional vehicles. After digging into it more, I’m still skeptical of what Euro regulators are pushing, but I did find that they don’t really think EVs make more brake dust.
Why EVs Making More Brake Dust Makes No Sense
If you know basically anything about EVs, you know that there’s really no way they could make more brake dust than a comparable gas-powered vehicle. There’s one exception, though, and that’s an EV without regenerative braking (no commercially made EVs I know of are like this, but some conversions are).
While regenerative braking doesn’t recapture all of the energy, it does put a good chunk of it back into the battery pack when you stop, while regular friction brakes convert the energy of a moving vehicle into heat to slow it down. But if you’ve washed a gas-powered car before, you know that cleaning the front wheels is harder than the back ones, because brake dust comes off of the brake pads when you stop, making a nasty mess. Sadly, this dust is worse for your health than it is for wheels (PM 2.5), and that’s why European regulators are concerned.
Put more simply, just think about how long the brakes last on an EV compared to most gas-powered cars. If brakes are making brake dust, that dust has to come from somewhere (hint: it’s the brake pads). So, if the brake pads are lasting longer, the vehicle’s brakes must be making less brake dust. It’s really that simple.
So, when I read that some regulator thinks EVs make more brake dust, that set off my bullshit alarm.
What European Regulators Really Think
So, to see what was really going on, I took a deeper look at the Organization for Economic Co-operation and Development (OECD) website. Yes, they are concerned that electric vehicles might make more PM 2.5 pollution (2.5 micrometer particulate matter, aka “dust”), but it isn’t coming from brakes. But, to be totally fair to Green Car Reportsthe regulators didn’t make this very clear and it took a fair amount of digging to figure this out.
To figure out exactly what they’re getting at, I had to look at their study very carefully. It turns out that they do know that EVs make less brake dust. They reduce the estimated brake dust (which can vary depending on the vehicle and its driver) by 75% compared to gas-powered vehicles. This isn’t perfect, but it’s a sensible number to use to get in the ballpark.
They also figure that electric vehicles with shorter ranges (~100 miles) are emitting less overall PM 2.5, while heavier EVs with big battery packs are emitting a little more PM 2.5 than gas-powered cars, but only if you strictly count non-exhaust particulate matter. The exhaust that ICE vehicles (especially diesel) puts out has a lot of PM 2.5.
Even looking at non-exhaust PM 2.5 only, the bigger-battery BEVs only exceed that of the cars because of tires, road wear, and pushing road dust back into the air that sits in the low spots in the pavement. All of these things are caused by extra vehicle weight.
Letting The Perfect Be The Enemy Of The Good
My personal opinion is that they kind of buried where the particulate matter comes from in their paper, and I think it may be because they have an ax to grind against EVs. In the press release, they make it pretty clear that the PM 2.5 recommendations support their assertion that “Policy makers should also favor measures that reduce driving distances, limit urban vehicle access and encourage public transport, walking and cycling.”
Getting people to bike and walk more is good. Getting them to take transit is also good, but only if it’s clean transit and not something burning a bunch of diesel and only carrying a few passengers during off-peak times. But using PM 2.5 pollution figures that they weren’t very clear about in the press release to support limiting urban vehicle access isn’t a very ethical way to get there. Policy makers really should be crystal clear about their justifications for public policy, especially when that policy limits the freedom of the people living under the regulations.
In truth, short-range EVs are shown in the study to have lower PM 2.5 emissions, even when only non-exhaust emissions are considered, so EVs can still be a better choice, even in urban areas. Taking positions against EVs because they aren’t as good as other options risks pushing buyers toward not getting EVs at all, or sowing more distrust in overzealous regulators.
Instead of smearing EVs in total, it would make more sense to encourage the use of smaller-battery EVs in urban areas. Scooters, miniature cars (so people can still keep the elements out), and EVs with shorter range packs are all great options. Modular EVs that can switch to a bigger battery pack for long road trips but run a small pack in the city could also be a good approach. In some cases, a PHEV could even be a good way to have a lighter pack, but only if there’s a good way to make sure the owner doesn’t run the ICE in the city.
It may also be a good idea to leave the methods for reducing PM up to manufacturers instead of mandating specific things at the regulatory level. New technologies, like better tires, could bring PM 2.5 levels down without banning cars, for example. This would probably require more regulatory flexibility than most regulators are comfortable with, but micromanaging technology instead of setting goals runs the risk of stifling superior technologies in the future.
What’s important is achieving the aims of environmental regulations (health and environmental goals), and not exerting control over people or micromanaging them.
Perhaps more importantly, it’s always good to be clear in communications with the public. Putting out press releases that mislead the press isn’t a great move, even when the misunderstanding isn’t intentional.
Featured image by Polestar.
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