A new study is out which quantifies just how much EVs help not just in cutting harmful exhaust emissions, but also cutting other types of pollution that come from personal vehicles. But of course, public transport, biking and walking are even better.
We’ve seen plenty of studies showing how the benefits of shifting to EVs translate to the real world, for example in California and London, where higher EV shares and regulations aimed at cutting down the excesses of polluting vehicles have produced significant air quality benefits already.
As it has become more and more untenable for anti-EV propagandists to deny the air quality benefits of EVs, a common refrain from them has become “but tailpipe emissions aren’t everything, what about brakes and tires, huh?!”
Putting aside for the moment the clear concern trolling involved in this response, it’s always been easy enough to point to regenerative braking as a reason that EVs improve that problem too – since they rarely use the brakes, they obviously wouldn’t emit as many brake particles.
But now we have proper quantification of that, and not only is the reduction in brake dust from battery-electric vehicles (BEVs) quite high, its also much higher than the benefit gained from either conventional gas-only hybrids or plug-in hybrids (PHEVs).
The analysis looked at various “non-exhaust emissions” of road transport, recognizing that as car exhaust becomes cleaner due to greater fleet electrification, other forms of emissions will end up taking over as the dominant pollutants from road transport.
It turns out that BEVs reduce the amount of brake dust by 83%, according to a new analysis by EIT Urban Mobility (a body of the European Union) and Transport for London. The study looked primarily at London, Milan and Barcelona.
The primary reason for this is the use of regenerative braking, meaning that electric vehicles can slow down without rubbing friction brakes. Other vehicles that use regenerative braking reduced brake emissions too, with Hybrids reducing them by 10-48%, and PHEVs by 66%.
Other forms of non-exhaust emissions also analyzed
The analysis looked at other forms of pollution as well, from tire and road wear.
On tire wear, the study assumed that BEVs would be responsible for more tire wear due to their greater weight. The study claims that BEVs are about 20% heavier than gas cars – though much of this is attributable to a vehicle mix that is more focused on larger vehicles, as it seems like every EV manufacturer is making huge SUVs and few are making small cars (a trend that can be seen in gas cars as well, which are 21% heavier than they were 20 years ago, and new EVs are more highly represented at the culmination of this trend).
When looking side-by-side at the best purpose-built EVs and their gas-powered counterparts, such as the Tesla Model 3 and the BMW 3 series, there is little difference in weight (the Tesla is only about ~200lbs heavier, across the model line, a difference of about 5%, not 20%).
Despite the slightly higher levels of tire wear from EVs, brake dust was found to be more unhealthy, as brake dust is much more likely to become airborne (>40%) than tire wear is (1-5%). So EVs create a lot less of the worse thing, and a little more of the less-bad thing.
Even using the study’s 20% number for EV. vs. gas car weight, this doesn’t handicap EVs much. BEVs produce 38% less total brake, road and tire wear combined, without even taking into account their exhaust benefits.
The analysis includes an interactive modeling tool where you can examine different types of transport and the amount of emissions they produce, with electric models being the clear winner out of the various analyzed powertrains.
We plugged in a few numbers and taking into account every form of emissions – brakes, tires, road wear and exhaust – electric cars even fared nearly as well as gas-powered motorcycles. While an individual EV does still produce 57% more total emissions than a gas-powered motorcycle per mile, as long as that car has higher occupancy than the motorcycle, that means it could fare better in terms of emissions per person-mile.
Shifting away from private cars is even better
The mention of person-miles brings up another answer for these problems: “mode shifting,” or moving drivers from cars to other methods of transport.
Buses and other heavy vehicles are accounted for in the tool, and they’ve got bigger numbers, but that doesn’t actually mean they’re dirtier.
While buses are obviously responsible for more emissions than cars individually, once you take into account the number of people they carry, that number plummets significantly. Buses may be responsible for ~4-5 times as many non-exhaust emissions as cars per mile, but a bus can hold an order of magnitude more people than a car can, reducing both emissions and traffic congestion.
And, just as was the case with electric cars, electric buses perform significantly better in terms of total emissions than gas buses do.
Beyond that, you get down to the absolute best answers: walking and biking. These two methods produce negligible environmental impact, and the study recommends that cities focus on encouraging these forms of transport wherever possible.
Luckily, we here at Electrek also love to cover electric bikes, which are a great way to get around that still offers the health and environmental benefits of cycling, but reduce the annoyances you might get from hills or windy days.
Study recommendations
Taking all this information together, the study makes some recommendations. It obviously points out that fleet electrification will be beneficial in reducing non-exhaust emissions, and suggests that that should continue rapidly.
However, it also points out that the total reduction in non-exhaust emissions from shifting drivers to public transport, rather than individual vehicles, can be 5x higher than just electrifying the vehicle fleet alone. So shifting drivers to using public transport should be prioritized when possible. Or, getting people to walk or bike instead.
For those vehicles that do remain on the road, lower-wear products can be encouraged, like carbon composite brake discs or those coated with hard metal coatings. Similarly, some tires are more wear-resistant than others, and there is little regulation forcing focus on lower-wear tire technologies.
Governments should also work to reverse ballooning vehicle sizes and higher SUV share for private vehicles (where have we heard that before…).
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