6 ms·

> There's also this ridiculously persistent anti electric vehicle I'm all for working toward better air quality, and electric vehicles definitely reduce greenh

by apta 7y ago

> There's also this ridiculously persistent anti electric vehicle I'm all for working toward better air quality, and electric vehicles definitely reduce greenhouse (and other) gas emissions. At the same time, pollution from cars is not just from exhaust emissions due to combustion. I recall reading somewhere that 80% or more of particulate matter pollution from cars comes from tires and brakes. So the notion of replacing all combustion engine cars with electric cars will somehow solve the pollution issue is not realistic. The Tesla Cybertruck might be a great vehicle, but it's heavy (large tires and lots of break wear). We need better solutions.

fignews 7y ago
EVs have regenerative braking. Brake pads last the life of the vehicle.
- thisisnico 7y ago
  EV's are harder on tires though because of the weight, does it balance out?
  - ricw 7y ago
    Minutely so. Tesla’s model 3 is 200kg (~400 pounds) heavier than BMWs equivalent 3 series. Don’t think the tire wear due to that difference will make much of a difference...
    - OnlineGladiator 7y ago
      400 pounds is a lot, that's more than 10%. The degradation is almost certainly not linear. There is an old study, which admittedly has its flaws, showing road damage was proportional to the fourth (!!!) power of the weight. I don't believe it's that bad (there are very specific conditions for that study and also it does not directly translate to tire wear), but I'd imagine it's at least to the second power, making a roughly 25% difference using your example vehicles. If someone knows more precise math, please share.
      - polyomino 7y ago
        https://sci-hub.tw/https://www.researchgate.net/publication/297889793_Non-exhaust_PM_emissions_from_electric_vehicles https://sci-hub.tw/https://www.researchgate.net/publication/... If you’re this study posted here before, it was just extrapolating based on weight of ice vehicles and is therefore largely useless in estimating the air quality impact of regenerative braking vehicles.
        OnlineGladiator 7y ago
        I have no idea about ice, but road degradation is fairly well studied (admittedly I'm learning about it as I find these): https://higherlogicdownload.s3.amazonaws.com/IPWEA/c7e19de0-08d5-47b7-ac3f-c198b11cd969/UploadedImages/pdfs/Info%20sheets/IS-06_4th_Power_Law.pdf https://higherlogicdownload.s3.amazonaws.com/IPWEA/c7e19de0-... > For example, a vehicle with an axle weight of 1000 kg is considered to cause 16 times the damage compared with a vehicle with an axle weight of 500 kg. It seems the 4th power law might actually be more accurate than I thought. If the vehicles can damage the road proportional the fourth power of their weight, surely there is significantly more wear on the wheels (the only part touching the road) than just a linear increase in weight? My hunch, and again I want someone to provide a more accurate model, is the wear would be proportional the third power of weight. EDIT: I found something, and it is complicated. https://journals.sagepub.com/doi/full/10.1177/1687814017700063 https://journals.sagepub.com/doi/full/10.1177/16878140177000... Figure 6 is what we're interested in, although you won't understand it without reading everything before it. It's definitely not linear, but it seems to roughly come out to something like the 3rd power, but it really depends (honestly you should click that link, there are so many variables). EDIT EDIT: Here we go! https://www.academia.edu/24153619/Tyre_Wear_Model_Validation_and_Sensitivity_Analysis https://www.academia.edu/24153619/Tyre_Wear_Model_Validation... So it seems to be somewhere between the second and third power of weight. Assuming tire wear is directly proportional to particle emissions (I have no idea if this is true), that would mean (using the 80% of emissions coming from tires number cited in an earlier comment, and EVs being roughly 10% heavier on average) that EVs are actually worse for air quality! This is lumping together brakes and tires though, which could be wrong. Although I am certain there is at least a second power effect from braking from vehicle weight. But as another commenter mentioned, regenerative braking (while not unique to electric vehicles, I think this is a fair contrast) will benefit the EV greatly here. Also it's worth mentioning that while EVs lose, it's not by a huge amount (but it seems to be enough to be measurable). So like most things, "it's complicated."
MertsA 7y ago
Electric vehicles can use regenerative braking for the majority of the time in normal driving. Brake pads can last substantially longer on hybrids and electric cars because of this.
- wasdfff 7y ago
  With stick shift cars you can use the engine to brake and get the same brake pad savings
  - thfuran 7y ago
    You can but very few people drive stick in the US and, of those, I suspect very few use engine breaking for a significant fraction of their braking. For getting off a highway maybe, but probably not for stop and go in a city.
    - paulie_a 7y ago
      In fact engine breaking is illegal in most populated areas
      - jandrese 7y ago
        This is not true. There are specific areas that ban it and have signage alerting drivers to that fact, but it is not common. Plus, it typically only applies to Semis as their engine braking is especially noisy. On a typical gas powered sedan you would be hard pressed to identify that someone is engine braking unless you were right next to it. Being prosecuted for it would be even more exceptional.
      - organsnyder 7y ago
        That kind of engine braking (the kind trucks do that's extremely loud) is completely different from "engine braking" with the transmission
      - macintux 7y ago
        This is the braking that communities post signage about: https://en.wikipedia.org/wiki/Compression_release_engine_brake https://en.wikipedia.org/wiki/Compression_release_engine_bra...
MayeulC 7y ago
As a cyclist, I still find it very hard to breathe when a truck passes me (worst are motor scooters going uphill), and would welcome such a reduction in particulate emissions. I guess that the size of those particulates is not the same either (tires and ICE). Last article or paper I read on the topic counted particulates drafted from the ground as emissions, which of course EVs do not reduce much. But there's still much less nocive emissions, and doesn't smell as bad...
davidw 7y ago
> We need better solutions. A good start is fixing our land-use regulation in the US to: * Allow apartments https://www.sightline.org/2019/11/27/end-apartment-bans-to-save-the-planet-un-climate-report-says/ https://www.sightline.org/2019/11/27/end-apartment-bans-to-s... * Allow things people need day to day near where they live: https://www.strongtowns.org/journal/2018/2/6/complete-neighborhoods https://www.strongtowns.org/journal/2018/2/6/complete-neighb... - if they still have to drive, it won't be as far, and more people will be able to walk and bike.

by apta 7y ago

fignews 7y ago

EVs have regenerative braking. Brake pads last the life of the vehicle.

thisisnico 7y ago
EV's are harder on tires though because of the weight, does it balance out?
- ricw 7y ago
  Minutely so. Tesla’s model 3 is 200kg (~400 pounds) heavier than BMWs equivalent 3 series. Don’t think the tire wear due to that difference will make much of a difference...
  - OnlineGladiator 7y ago
    400 pounds is a lot, that's more than 10%. The degradation is almost certainly not linear. There is an old study, which admittedly has its flaws, showing road damage was proportional to the fourth (!!!) power of the weight. I don't believe it's that bad (there are very specific conditions for that study and also it does not directly translate to tire wear), but I'd imagine it's at least to the second power, making a roughly 25% difference using your example vehicles. If someone knows more precise math, please share.
    - polyomino 7y ago
      https://sci-hub.tw/https://www.researchgate.net/publication/297889793_Non-exhaust_PM_emissions_from_electric_vehicles https://sci-hub.tw/https://www.researchgate.net/publication/... If you’re this study posted here before, it was just extrapolating based on weight of ice vehicles and is therefore largely useless in estimating the air quality impact of regenerative braking vehicles.
      - OnlineGladiator 7y ago
        I have no idea about ice, but road degradation is fairly well studied (admittedly I'm learning about it as I find these): https://higherlogicdownload.s3.amazonaws.com/IPWEA/c7e19de0-08d5-47b7-ac3f-c198b11cd969/UploadedImages/pdfs/Info%20sheets/IS-06_4th_Power_Law.pdf https://higherlogicdownload.s3.amazonaws.com/IPWEA/c7e19de0-... > For example, a vehicle with an axle weight of 1000 kg is considered to cause 16 times the damage compared with a vehicle with an axle weight of 500 kg. It seems the 4th power law might actually be more accurate than I thought. If the vehicles can damage the road proportional the fourth power of their weight, surely there is significantly more wear on the wheels (the only part touching the road) than just a linear increase in weight? My hunch, and again I want someone to provide a more accurate model, is the wear would be proportional the third power of weight. EDIT: I found something, and it is complicated. https://journals.sagepub.com/doi/full/10.1177/1687814017700063 https://journals.sagepub.com/doi/full/10.1177/16878140177000... Figure 6 is what we're interested in, although you won't understand it without reading everything before it. It's definitely not linear, but it seems to roughly come out to something like the 3rd power, but it really depends (honestly you should click that link, there are so many variables). EDIT EDIT: Here we go! https://www.academia.edu/24153619/Tyre_Wear_Model_Validation_and_Sensitivity_Analysis https://www.academia.edu/24153619/Tyre_Wear_Model_Validation... So it seems to be somewhere between the second and third power of weight. Assuming tire wear is directly proportional to particle emissions (I have no idea if this is true), that would mean (using the 80% of emissions coming from tires number cited in an earlier comment, and EVs being roughly 10% heavier on average) that EVs are actually worse for air quality! This is lumping together brakes and tires though, which could be wrong. Although I am certain there is at least a second power effect from braking from vehicle weight. But as another commenter mentioned, regenerative braking (while not unique to electric vehicles, I think this is a fair contrast) will benefit the EV greatly here. Also it's worth mentioning that while EVs lose, it's not by a huge amount (but it seems to be enough to be measurable). So like most things, "it's complicated."

MertsA 7y ago

Electric vehicles can use regenerative braking for the majority of the time in normal driving. Brake pads can last substantially longer on hybrids and electric cars because of this.

wasdfff 7y ago
With stick shift cars you can use the engine to brake and get the same brake pad savings
- thfuran 7y ago
  You can but very few people drive stick in the US and, of those, I suspect very few use engine breaking for a significant fraction of their braking. For getting off a highway maybe, but probably not for stop and go in a city.
  - paulie_a 7y ago
    In fact engine breaking is illegal in most populated areas
    - jandrese 7y ago
      This is not true. There are specific areas that ban it and have signage alerting drivers to that fact, but it is not common. Plus, it typically only applies to Semis as their engine braking is especially noisy. On a typical gas powered sedan you would be hard pressed to identify that someone is engine braking unless you were right next to it. Being prosecuted for it would be even more exceptional.
    - organsnyder 7y ago
      That kind of engine braking (the kind trucks do that's extremely loud) is completely different from "engine braking" with the transmission
    - macintux 7y ago
      This is the braking that communities post signage about: https://en.wikipedia.org/wiki/Compression_release_engine_brake https://en.wikipedia.org/wiki/Compression_release_engine_bra...

MayeulC 7y ago

As a cyclist, I still find it very hard to breathe when a truck passes me (worst are motor scooters going uphill), and would welcome such a reduction in particulate emissions. I guess that the size of those particulates is not the same either (tires and ICE). Last article or paper I read on the topic counted particulates drafted from the ground as emissions, which of course EVs do not reduce much. But there's still much less nocive emissions, and doesn't smell as bad...

davidw 7y ago

> We need better solutions. A good start is fixing our land-use regulation in the US to: * Allow apartments https://www.sightline.org/2019/11/27/end-apartment-bans-to-save-the-planet-un-climate-report-says/ https://www.sightline.org/2019/11/27/end-apartment-bans-to-s... * Allow things people need day to day near where they live: https://www.strongtowns.org/journal/2018/2/6/complete-neighborhoods https://www.strongtowns.org/journal/2018/2/6/complete-neighb... - if they still have to drive, it won't be as far, and more people will be able to walk and bike.