Monday’s Friday Reads – 15 July 2019

1. Electric cars (or other electric vehicles) have no exhaust fumes, and minimal brake wear due to regenerative breaking. That eliminates two of the three urban pollution sources, leaving only tyres.

2. Eric:
   The so called “Oslo” problem ( because, IIRC, said city is where this slight difficulty was first noted ) is one that the more voluble of the supposed “pure air” campaigners don’t want to acknowledge, of course.

   LOVE the drought-resistant stonecrops planted on the Utrecht bus-stops – a really good idea.
   Lots more information here.. – they are easy to grow, ifyou can get hold of them.

3. Eric, you forgot the road surface debris mentioned in the article.

   Although these particulates are only a problem in dry conditions.

4. Greg:

   To clarify, is the problem that there’ll still be air pollution even if a city has 100% electric cars?

5. David
   YES – very much so, because of the surface dirt strirred up by the rubber-tyre/road-surface interactions & “fluid” flow sucking up particulates from the surfaces & dispersing them into the air.
   The tiny rubber particles from the tyres are one of the worst offenders – they contain all sorts of ‘orrible crosslinking compounds put into the rubber during the tyres’ manufacturing processes, which will ( & do ) really unpleasant things to the insides of your lungs & for that matter your bloodstream.
   Definitely carcinogenic, too.

6. 92% of brake dust is iron, apparently. The claim for the underground is that this is not a (particularly) dangerous particulate. Presumably the worst case for dust formation is heavy braking, which wont be regenerative. Though heavy braking will be less on urban roads.

   The issue with tyres has been they cause runoff to be polluted with plastic. Most plastic /deep/ at sea is from this source.

   Electric cars being heavier will, other things being equal, cause both sources to increase.

7. Re Tom Hawtin & Eric,

   Regenerative braking is used at low speeds hence much of city driving braking activity may not change being stop start low speed traffic.

   LU also identified a lot of unknown origin dust assumed to be organic filler material assumed to be from brake pads but they weren’t certain hence the brake dust will be a lot less than 92% iron based origin once unknown is accounted for.

   The helpful thing about the iron based dust is that it is fairly large which a good thing as that tends to reduce chemical activity (small particles are the once you need to worry about) and large iron based particles aren’t that problematic.

8. Of course, even if we had 100% EVs and could solve the brake/tyre dust problem, they still wouldn’t solve the congestion problem, which is a function of space taken up. Private cars are inherently inefficient in this respect with no rectification possible.

9. @ NGH 15 July at 18:08
   ‘Regenerative braking is used at low speeds hence much of city driving braking activity may not change being stop start low speed traffic.’

   Was that what you meant to say or did you miss out a ‘not’? The impression that I have is that regenerative breaking is more effective at higher speeds and thus largely irrelevant around town.

10. Re RayJayK,

    Yes well spotted the “not ” is missing

11. Regenerative braking. Technology is moving fast. Some newer electric models can bring the vehicle to a virtual stop using regen alone, needing friction brakes for only the very last few mph. (If at all). The jaguar i-pace is one example.
    Doesn’t solve the tyre particles pollution though.

12. ‘Autonomous’ operation holds the promise of gentler control with less strain on the tyre and brake wear particles.

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