5 ms·

I've seen compelling arguments that driving a Model 3 actually even has lower average CO2 emissions per mile than riding a bike, since riding a bike requires ea

by NickM 7y ago

I've seen compelling arguments that driving a Model 3 actually even has lower average CO2 emissions per mile than riding a bike, since riding a bike requires eating extra calories to power it, and food has a substantial carbon footprint. Depends on the type of food you're eating, your local electricity grid, and many other factors of course. And obviously this ignores both manufacturing costs and the physical and psychological benefits to biking, so I'm not saying everyone should ditch biking, but it's an interesting comparison. https://twitter.com/Robotbeat/status/1102249291568029696 https://twitter.com/Robotbeat/status/1102249291568029696

Robotbeat 7y ago
That was me. :) The assumption was that if you have a particularly high emissions source of most of your calories (like virtually all meat especially ruminants or, interestingly, fresh fruit and not much grains, sugars, or oils), then biking could be worse. But it's just to point out how efficient electric cars can be and how diet can start to play a bigger role. I wasn't super serious about the comparison. :) (And e-bikes are much, much more efficient than an electric car... if they last long enough).
- gpm 7y ago
  > (And e-bikes are much, much more efficient than an electric car... if they last long enough). Would this hold true for e-motorcycles as well, or are we really saying "slow moving vehicles are much more efficient than fast moving vehicles"?
  - Robotbeat 7y ago
    I think in this case it's small vehicles (low mass, low aerodynamic cross section) that are more efficient. Electric cars would only be marginally more efficient (~50% better) at low speeds due to rolling resistance (whose coefficient is basically constant with respect to speed) and parasitic loss from the computer, infotainment, climate control, etc. Per seat, electric cars are generally much better than electric motorcycles and about half as good as much slower e-bikes (although if ridden at the same speed, almost as good).
  - Balero 7y ago
    It takes less energy to accelerate less mass. So the lighter your vehicle the more fuel efficient it is for the same speed/acceleration. Going a lower speed is also more fuel efficient (depending on the engine, but it takes less energy) as you have a lower air/road resistance.
  - Obi_Juan_Kenobi 7y ago
    In practical terms, while ebikes may have a slow top speed, they move through congested areas much more quickly, so for trip-substitution purposes, the efficiency is apples-to-apples. More direct routes at steady speeds is a real benefit to ebikes. Much of the efficiency benefit is from the lower drag due to lower speeds, but if the purposed served is comparable, then it's valid. Just depends on what you're looking at. FWIW, even at 30mph, ebikes are over an order of magnitude more efficient than a Model 3 at 70mph (<28 vs. 280 WH/mile). Zero (electric motorcycle) states 180 WH/mile at 70mph.
    - Robotbeat 7y ago
      Agreed. That fits with my info. Pack a Model 3 with 5 people and go 30mph, and the efficiency per person is about the same as an ebike.
      - consp 7y ago
        If you go steady speed the lower Cd and higher efficiency of the drivetrain might actually make it more efficient than the bike.
  - Gibbon1 7y ago
    Two things I can think of is gasoline powered motorcycles aren't that much more efficient than a Prius. And a Prius seats four. I suspect the same applies when you switch to electric[1]. The other one is the injuries per mile are much higher for motorcycles. One aught to account for that as well. Side issue: Motorcycles are terrible from an emissions standpoint. Though of course an e-motorcycle would be better. [1] Scaling factor vs size is highly positive.
- NickM 7y ago
  Oh my gosh, wow, what a strange coincidence! I totally did not notice that I was replying to the same person who wrote that post. Small world :) And yeah, I wasn't necessarily reading too much into the comparison since of course there are so many different factors that can tilt the numbers different ways, but I found it very thought-provoking regardless. Great point about e-bikes too.
megaremote 7y ago
This is just stupid. Does this ignore the calories the driver uses up as well?
- Robotbeat 7y ago
  It's only counting additional calories burned on top of basal metabolic rate. Of course, the car will get you there faster (less time in transit), so basal metabolic calories will ALSO be lower in the car...
  - ido 7y ago
    Speed greatly depends on your location, I highly doubt the majority of commutes in Berlin (where I'm at) will be significantly (if at all) faster by car than by e-bike - seeing as the ubahn tops at 45 mph & is quite often quicker to get around town than driving. I suspect the same is similar to any major (and therefor congested) urban area. The real killer is the American-style sparse suburban living that requires long commutes on highways...
    - kaybe 7y ago
      I'd say depending on where you park the bike can be substantially faster (it's actually door-to-door, a car is very rarely).
      - ido 7y ago
        I think so too, i was trying to be careful and make the less drastic bet that it's at the very least not slower :)
dahart 7y ago
> I've seen compelling arguments that driving a Model 3 actually even has lower average CO2 emissions per mile than riding a bike, since riding a bike requires eating extra calories to power it, and food has a substantial carbon footprint. Color me skeptical. A Model 3 has ~20x the mass of a rider & bike, give or take. Producing it, delivering it, and moving it around thus takes ~20x the energy in the best case, energy that has to come from a CO2 emitting source in both cases. As bad as meat & dairy might be, being 20x worse than automobile and electricity production combined is a really high and unlikely bar.
- justinator 7y ago
  This is where I'm tripping up on this idea, too. The 20x difference in mass of a Tesla - but still more efficient than a human pedaling a bike may in fact violate the Laws of Thermodynamics. Also, I'm not sure if this is truly taking into consideration of the resources needed to make a Tesla vs. a bicycle. Or I guess the big one: the # miles/year driven by a usual car owner vs. # miles/year cycled by someone using purely human power to move oneself.
  - Dylan16807 7y ago
    The car can absorb energy when braking, so the minimum expenditure based on the laws of thermodynamics is minuscule and irrelevant.
    - dahart 7y ago
      That’s an extremely tall claim, that minimum expenditure is minuscule and irrelevant, maybe taller than the original unlikely claim that a car might be more efficient than a bike rider. Regenerative braking does not invalidate the laws of thermodynamics, we just have to identify the regeneration efficiency. So how much of the energy expenditure does regenerative braking in a Model 3 recover? From what I’m reading, it may be in the single digit percentages for highway driving. Tesla’s own web page says the theoretical max is 64% [1], and that’s only in a perfect situation (accelerate & immediately stop), it’s not accounting for driving for a long time without braking or using the electric features inside the car, e.g. aerodynamic loss, rolling loss, & heating & a/c. Wikipedia says including the accessories, typical best-case efficiency is around 50% [2]. But if you accelerate and drive for a mile without braking, you’ve already lost most of your initial energy to air & tires & battery conversion loss, the brakes can only capture energy from what’s left. [1] https://www.tesla.com/blog/magic-tesla-roadster-regenerative-braking https://www.tesla.com/blog/magic-tesla-roadster-regenerative... [2] https://en.m.wikipedia.org/wiki/Regenerative_brake https://en.m.wikipedia.org/wiki/Regenerative_brake
scarejunba 7y ago
You know what's even better? Me. I drive an SUV in San Francisco and I offset all my carbon usage every year. I also eat meat. I also fly. I'm also better than nearly every electric car driver.
- tunesmith 7y ago
  I know you're being tongue-in-cheek, but it's worth making the point. Carbon offset prices are determined by current carbon offset capacity. Like, number of acres where trees can be planted, number of carbon-scrubbing machines that can be installed at a certain location, etc. Carbon offset supply is limited. Meaning, it cannot scale to the level the planet needs, at current prices. If we gave these carbon-offset companies X billion dollars tomorrow at current prices, it's not like our problems would be solved. Therefore, carbon offset prices will go up as demand (read: more people seeking to offset carbon) goes up. One way to battle that is to reduce carbon emissions while buying offsets. That will reduce the required "supply". People who buy offsets without reducing their emissions, on the other hand, are effectively stealing resources from future people, by buying low and making it more expensive for the people buying later. (If you really want to be a jerk about it, you can calculate your lifetime carbon expenditures and just offset all of it now while prices are cheap.)
  - scarejunba 7y ago
    Haha, you’re right, of course. My real goal is to popularize the notion of paying for your carbon debt so that one day when we know we only have a certain carbon budget we’re acclimated to the idea of paying to pollute a little more by buying some of someone else’s budget. Also, I’d rather bootstrap them now rather than later. I have to buy the offsets now though or no one will listen. Cool idea to buy the entire lifetime’s offsets.
jdnenej 7y ago
The average American probably already eats enough calories to ride a bike to and from work multiple times a day.

by NickM 7y ago

Robotbeat 7y ago

That was me. :) The assumption was that if you have a particularly high emissions source of most of your calories (like virtually all meat especially ruminants or, interestingly, fresh fruit and not much grains, sugars, or oils), then biking could be worse. But it's just to point out how efficient electric cars can be and how diet can start to play a bigger role. I wasn't super serious about the comparison. :) (And e-bikes are much, much more efficient than an electric car... if they last long enough).

gpm 7y ago
> (And e-bikes are much, much more efficient than an electric car... if they last long enough). Would this hold true for e-motorcycles as well, or are we really saying "slow moving vehicles are much more efficient than fast moving vehicles"?
- Robotbeat 7y ago
  I think in this case it's small vehicles (low mass, low aerodynamic cross section) that are more efficient. Electric cars would only be marginally more efficient (~50% better) at low speeds due to rolling resistance (whose coefficient is basically constant with respect to speed) and parasitic loss from the computer, infotainment, climate control, etc. Per seat, electric cars are generally much better than electric motorcycles and about half as good as much slower e-bikes (although if ridden at the same speed, almost as good).
- Balero 7y ago
  It takes less energy to accelerate less mass. So the lighter your vehicle the more fuel efficient it is for the same speed/acceleration. Going a lower speed is also more fuel efficient (depending on the engine, but it takes less energy) as you have a lower air/road resistance.
- Obi_Juan_Kenobi 7y ago
  In practical terms, while ebikes may have a slow top speed, they move through congested areas much more quickly, so for trip-substitution purposes, the efficiency is apples-to-apples. More direct routes at steady speeds is a real benefit to ebikes. Much of the efficiency benefit is from the lower drag due to lower speeds, but if the purposed served is comparable, then it's valid. Just depends on what you're looking at. FWIW, even at 30mph, ebikes are over an order of magnitude more efficient than a Model 3 at 70mph (<28 vs. 280 WH/mile). Zero (electric motorcycle) states 180 WH/mile at 70mph.
  - Robotbeat 7y ago
    Agreed. That fits with my info. Pack a Model 3 with 5 people and go 30mph, and the efficiency per person is about the same as an ebike.
    - consp 7y ago
      If you go steady speed the lower Cd and higher efficiency of the drivetrain might actually make it more efficient than the bike.
- Gibbon1 7y ago
  Two things I can think of is gasoline powered motorcycles aren't that much more efficient than a Prius. And a Prius seats four. I suspect the same applies when you switch to electric[1]. The other one is the injuries per mile are much higher for motorcycles. One aught to account for that as well. Side issue: Motorcycles are terrible from an emissions standpoint. Though of course an e-motorcycle would be better. [1] Scaling factor vs size is highly positive.
NickM 7y ago
Oh my gosh, wow, what a strange coincidence! I totally did not notice that I was replying to the same person who wrote that post. Small world :) And yeah, I wasn't necessarily reading too much into the comparison since of course there are so many different factors that can tilt the numbers different ways, but I found it very thought-provoking regardless. Great point about e-bikes too.

megaremote 7y ago

This is just stupid. Does this ignore the calories the driver uses up as well?

Robotbeat 7y ago
It's only counting additional calories burned on top of basal metabolic rate. Of course, the car will get you there faster (less time in transit), so basal metabolic calories will ALSO be lower in the car...
- ido 7y ago
  Speed greatly depends on your location, I highly doubt the majority of commutes in Berlin (where I'm at) will be significantly (if at all) faster by car than by e-bike - seeing as the ubahn tops at 45 mph & is quite often quicker to get around town than driving. I suspect the same is similar to any major (and therefor congested) urban area. The real killer is the American-style sparse suburban living that requires long commutes on highways...
  - kaybe 7y ago
    I'd say depending on where you park the bike can be substantially faster (it's actually door-to-door, a car is very rarely).
    - ido 7y ago
      I think so too, i was trying to be careful and make the less drastic bet that it's at the very least not slower :)

dahart 7y ago

> I've seen compelling arguments that driving a Model 3 actually even has lower average CO2 emissions per mile than riding a bike, since riding a bike requires eating extra calories to power it, and food has a substantial carbon footprint. Color me skeptical. A Model 3 has ~20x the mass of a rider & bike, give or take. Producing it, delivering it, and moving it around thus takes ~20x the energy in the best case, energy that has to come from a CO2 emitting source in both cases. As bad as meat & dairy might be, being 20x worse than automobile and electricity production combined is a really high and unlikely bar.

justinator 7y ago
This is where I'm tripping up on this idea, too. The 20x difference in mass of a Tesla - but still more efficient than a human pedaling a bike may in fact violate the Laws of Thermodynamics. Also, I'm not sure if this is truly taking into consideration of the resources needed to make a Tesla vs. a bicycle. Or I guess the big one: the # miles/year driven by a usual car owner vs. # miles/year cycled by someone using purely human power to move oneself.
- Dylan16807 7y ago
  The car can absorb energy when braking, so the minimum expenditure based on the laws of thermodynamics is minuscule and irrelevant.
  - dahart 7y ago
    That’s an extremely tall claim, that minimum expenditure is minuscule and irrelevant, maybe taller than the original unlikely claim that a car might be more efficient than a bike rider. Regenerative braking does not invalidate the laws of thermodynamics, we just have to identify the regeneration efficiency. So how much of the energy expenditure does regenerative braking in a Model 3 recover? From what I’m reading, it may be in the single digit percentages for highway driving. Tesla’s own web page says the theoretical max is 64% [1], and that’s only in a perfect situation (accelerate & immediately stop), it’s not accounting for driving for a long time without braking or using the electric features inside the car, e.g. aerodynamic loss, rolling loss, & heating & a/c. Wikipedia says including the accessories, typical best-case efficiency is around 50% [2]. But if you accelerate and drive for a mile without braking, you’ve already lost most of your initial energy to air & tires & battery conversion loss, the brakes can only capture energy from what’s left. [1] https://www.tesla.com/blog/magic-tesla-roadster-regenerative-braking https://www.tesla.com/blog/magic-tesla-roadster-regenerative... [2] https://en.m.wikipedia.org/wiki/Regenerative_brake https://en.m.wikipedia.org/wiki/Regenerative_brake

scarejunba 7y ago

You know what's even better? Me. I drive an SUV in San Francisco and I offset all my carbon usage every year. I also eat meat. I also fly. I'm also better than nearly every electric car driver.

tunesmith 7y ago
I know you're being tongue-in-cheek, but it's worth making the point. Carbon offset prices are determined by current carbon offset capacity. Like, number of acres where trees can be planted, number of carbon-scrubbing machines that can be installed at a certain location, etc. Carbon offset supply is limited. Meaning, it cannot scale to the level the planet needs, at current prices. If we gave these carbon-offset companies X billion dollars tomorrow at current prices, it's not like our problems would be solved. Therefore, carbon offset prices will go up as demand (read: more people seeking to offset carbon) goes up. One way to battle that is to reduce carbon emissions while buying offsets. That will reduce the required "supply". People who buy offsets without reducing their emissions, on the other hand, are effectively stealing resources from future people, by buying low and making it more expensive for the people buying later. (If you really want to be a jerk about it, you can calculate your lifetime carbon expenditures and just offset all of it now while prices are cheap.)
- scarejunba 7y ago
  Haha, you’re right, of course. My real goal is to popularize the notion of paying for your carbon debt so that one day when we know we only have a certain carbon budget we’re acclimated to the idea of paying to pollute a little more by buying some of someone else’s budget. Also, I’d rather bootstrap them now rather than later. I have to buy the offsets now though or no one will listen. Cool idea to buy the entire lifetime’s offsets.

jdnenej 7y ago

The average American probably already eats enough calories to ride a bike to and from work multiple times a day.