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I've read numerous analyses arguing that a small to mid size EV releases less CO2 and other pollution than a similarly sized typical gas car (or even a hybrid)

by api 5y ago

I've read numerous analyses arguing that a small to mid size EV releases less CO2 and other pollution than a similarly sized typical gas car (or even a hybrid) even if the electricity comes from 100% coal. Coal releases the most CO2 per unit energy. It's almost pure carbon after all. But to compare with a gasoline car you have to consider: (1) Large power plants are anywhere from 1.5X to 3X more thermally efficient than a small piston engine. How much better depends on whether the power plant is an old school boiler and turbine or a newer supercritical steam or combined cycle plant. (2) Gasoline is the highly refined and quality controlled end product of a long supply chain. Oil must be drilled, sometimes cracked (for heavy oil), shipped (often more than once), refined (this uses a lot of power), doped with small amounts of manufactured additives, then shipped at least one and sometimes two or three more times to a gas station. Every step of that supply chain uses even more energy, and this must be subtracted to get the overall end-to-end efficiency of a car engine. This makes car engine efficiency from oil well to tailpipe really suck. Coal meanwhile is often shipped only once or twice and requires minimal processing, usually just pulverization and then flue gas scrubbers at the exhaust end. (3) ICE cars require a lot more maintenance and fluids that have to be changed, etc., and all that has to also be considered in their energy footprint. EVs are superior in every single way except range and recharge time: complexity of the vehicle, reliability, acceleration and driving experience, urban pollution, overall emissions, and end to end efficiency. They remain superior even in the worst case of a 100% coal fired power grid, and very few regions get their power from only coal. The range and recharge time gap is already small enough to make EVs practical for 90%+ of driving scenarios and the gap is closing. The oil age is over.

AdrianB1 5y ago
I would like to see a source for the first claim. If I recall correctly from my parent's expertise (energy domain) an efficient large power plant (~60-65%) can be ~ 1.5 times more efficient than a modern ICE engine (averaged, Diesel being better than gasoline, around 40%). 3x would push the efficiency over 100%.
- api 5y ago
  Can't find it now, but you are probably right for newer and well maintained ICE engines. I'm guessing that the 1.5X-3X range I saw includes old and badly maintained engines. They could also have been measuring overall fuel to wheel efficiency and including a ~15% loss in the transmission and drive train and maybe also including average time spent idling (which doesn't apply to EVs). Keep in mind that there are a lot of shitty cars on the road. A power plant's engine is going to usually be well tuned and maintained because small increases in efficiency can be worth a ton of money when you are generating tens of gigawatt hours per day of power. How often does a typical driver of a middle-aged car take it in to be tuned with the objective of maximizing energy efficiency? I bet the average gap across all cars on the road and including transmission loss is at least 2X. Also it's tough to argue against the second point. Look into how much power is used in the oil to gasoline supply chain, especially if the oil is coming from heavy oil that requires an additional cracking ("upgrading") step or fracked wells that require a lot of energy to drill and hydraulically fracture. I recall reading an analysis years ago arguing that the Canadian tar sands are almost an indirect natural gas to oil conversion operation rather than a net producer of energy. A huge amount of gas is burned to get that stuff out of the ground and into a form that refineries can handle. You could instead just burn that gas in a combined cycle power plant and run EVs with it and emit a lot less carbon. Thing is when you are buying any oil product you are really not buying energy. It's ridiculously expensive compared to energy from any other source. You are buying conveniently stored energy and paying a huge markup for it.
- mikeyouse 5y ago
  Not OP but he’s correct if talking about how much energy actually moves the car —- IC engines are indeed ~40% efficient but if you’re measuring the energy that actually moves the car it’s more like 23%-25% due to all the parasitic and drivetrain losses. So it’s completely plausible for a power plant to be 3x that. Of course some of those losses would also apply to EVs but still, “wasting” 3/4 the energy of a highly refined, carbon intensive product is a pretty low bar. Page 53 onward: https://deepblue.lib.umich.edu/bitstream/handle/2027.42/57640/mpapke_1.pdf?sequence=2&isAllowed=y https://deepblue.lib.umich.edu/bitstream/handle/2027.42/5764...
cesarb 5y ago
> EVs are superior in every single way except range and recharge time While I'm also in favor of EVs, I can see two other ways in which EVs are not superior: weight (every article about EVs I read seems to mention that they're heavier than the corresponding ICE vehicles; on the other hand, the weight distribution seems to be yet another way in which most EVs are superior, with their low center of gravity), and price. The price seems to be the main barrier to EV adoption IMO, and is probably the reason they are so rare where I live (it's a major metropolitan area, and yet so far I have seen a non-rail EV only once).
- api 5y ago
  The weight issue is a mixed bag. It can improve handling in some conditions such as bad weather. Regenerative braking makes up for the energy cost fairly well. The cost is higher up front but lower overall. The comparison is also only fair if you compare similar cost/luxury classes of car. It's not fair to compare a Tesla Model S to a Honda Civic. Instead you'd compare a Model S cost to a mid-high end BMW, Mercedes, Audi, etc. You'd compare a Honda Civic to a Nissan Leaf or a Chevy Bolt.
  - giantg2 5y ago
    I'm still waiting for ones not based on "loaded" trims. Appearently the margins are too low to support budget vehicles. Look at trucks. I just want/need a basic work truck. They're about $25k. The lowest cost I've seen for an electric one is about double the cost. So I agree that you have to compare similar levels/trims, but many times the lower trims don't exist in the EV market.
- mrtranscendence 5y ago
  > The price seems to be the main barrier to EV adoption IMO, and is probably the reason they are so rare where I live (it's a major metropolitan area, and yet so far I have seen a non-rail EV only once). Interesting. I live near a (relatively!) affluent suburb of Cincinnati and I see at least one or two Teslas a week, depending on how much I'm driving. Our next door neighbors have an electric BMW (i3). And I'm not a car guy, so there could be a lot more than that I'm missing. Next car I buy will probably be a Tesla? Though it might be a few years. Of course, this doesn't disprove your point that price is an issue in adoption.
giantg2 5y ago
The big question in my mind, is what are we going to build roads out of? Most of them are still using petroleum products. Concrete is a CO2 emitter too. What's left? Is there a point to creating electric cars if we find out that we need to do away with the infrastructure they require, or did we not think that far ahead yet? I'm genuinely curious what options exist to deal with this.
- Ottolay 5y ago
  The problem is not petroleum products themself, the problem is burning the petroleum products. Even if we move the whole energy economy away from fossil fuels we'll still be using oil for lubrication, plastics, asphalt, and a bunch of other things. That is fine.
  - giantg2 5y ago
    Eventually it is a problem - they are not renewable. Are all the components usable for these other uses? I thought some distillates only worked for some uses (can the gas portion be used for asphalt?). I would also imagine there is immense heating from the road surfaces. Not to mention the fumes, chemicals used in the processing, and all the transportation.
    - richiebful1 5y ago
      If we're not burning petroleum for heating/electricity anymore I imagine our reserves will be enough for thousands of years of roads, chemicals, synthetic materials, etc. By then we'll have developed alternatives, if not sooner
      - giantg2 5y ago
        I think that's wishful thinking on the timeline and a very hopeful outlook for technology to save us. It also doesnt answer the question of if some of the byproducts are only useful for burning. If I remember right, gasoline was originally considered a byproduct.

by api 5y ago

AdrianB1 5y ago

I would like to see a source for the first claim. If I recall correctly from my parent's expertise (energy domain) an efficient large power plant (~60-65%) can be ~ 1.5 times more efficient than a modern ICE engine (averaged, Diesel being better than gasoline, around 40%). 3x would push the efficiency over 100%.

api 5y ago
Can't find it now, but you are probably right for newer and well maintained ICE engines. I'm guessing that the 1.5X-3X range I saw includes old and badly maintained engines. They could also have been measuring overall fuel to wheel efficiency and including a ~15% loss in the transmission and drive train and maybe also including average time spent idling (which doesn't apply to EVs). Keep in mind that there are a lot of shitty cars on the road. A power plant's engine is going to usually be well tuned and maintained because small increases in efficiency can be worth a ton of money when you are generating tens of gigawatt hours per day of power. How often does a typical driver of a middle-aged car take it in to be tuned with the objective of maximizing energy efficiency? I bet the average gap across all cars on the road and including transmission loss is at least 2X. Also it's tough to argue against the second point. Look into how much power is used in the oil to gasoline supply chain, especially if the oil is coming from heavy oil that requires an additional cracking ("upgrading") step or fracked wells that require a lot of energy to drill and hydraulically fracture. I recall reading an analysis years ago arguing that the Canadian tar sands are almost an indirect natural gas to oil conversion operation rather than a net producer of energy. A huge amount of gas is burned to get that stuff out of the ground and into a form that refineries can handle. You could instead just burn that gas in a combined cycle power plant and run EVs with it and emit a lot less carbon. Thing is when you are buying any oil product you are really not buying energy. It's ridiculously expensive compared to energy from any other source. You are buying conveniently stored energy and paying a huge markup for it.
mikeyouse 5y ago
Not OP but he’s correct if talking about how much energy actually moves the car —- IC engines are indeed ~40% efficient but if you’re measuring the energy that actually moves the car it’s more like 23%-25% due to all the parasitic and drivetrain losses. So it’s completely plausible for a power plant to be 3x that. Of course some of those losses would also apply to EVs but still, “wasting” 3/4 the energy of a highly refined, carbon intensive product is a pretty low bar. Page 53 onward: https://deepblue.lib.umich.edu/bitstream/handle/2027.42/57640/mpapke_1.pdf?sequence=2&isAllowed=y https://deepblue.lib.umich.edu/bitstream/handle/2027.42/5764...

cesarb 5y ago

> EVs are superior in every single way except range and recharge time While I'm also in favor of EVs, I can see two other ways in which EVs are not superior: weight (every article about EVs I read seems to mention that they're heavier than the corresponding ICE vehicles; on the other hand, the weight distribution seems to be yet another way in which most EVs are superior, with their low center of gravity), and price. The price seems to be the main barrier to EV adoption IMO, and is probably the reason they are so rare where I live (it's a major metropolitan area, and yet so far I have seen a non-rail EV only once).

api 5y ago
The weight issue is a mixed bag. It can improve handling in some conditions such as bad weather. Regenerative braking makes up for the energy cost fairly well. The cost is higher up front but lower overall. The comparison is also only fair if you compare similar cost/luxury classes of car. It's not fair to compare a Tesla Model S to a Honda Civic. Instead you'd compare a Model S cost to a mid-high end BMW, Mercedes, Audi, etc. You'd compare a Honda Civic to a Nissan Leaf or a Chevy Bolt.
- giantg2 5y ago
  I'm still waiting for ones not based on "loaded" trims. Appearently the margins are too low to support budget vehicles. Look at trucks. I just want/need a basic work truck. They're about $25k. The lowest cost I've seen for an electric one is about double the cost. So I agree that you have to compare similar levels/trims, but many times the lower trims don't exist in the EV market.
mrtranscendence 5y ago
> The price seems to be the main barrier to EV adoption IMO, and is probably the reason they are so rare where I live (it's a major metropolitan area, and yet so far I have seen a non-rail EV only once). Interesting. I live near a (relatively!) affluent suburb of Cincinnati and I see at least one or two Teslas a week, depending on how much I'm driving. Our next door neighbors have an electric BMW (i3). And I'm not a car guy, so there could be a lot more than that I'm missing. Next car I buy will probably be a Tesla? Though it might be a few years. Of course, this doesn't disprove your point that price is an issue in adoption.

giantg2 5y ago

The big question in my mind, is what are we going to build roads out of? Most of them are still using petroleum products. Concrete is a CO2 emitter too. What's left? Is there a point to creating electric cars if we find out that we need to do away with the infrastructure they require, or did we not think that far ahead yet? I'm genuinely curious what options exist to deal with this.

Ottolay 5y ago
The problem is not petroleum products themself, the problem is burning the petroleum products. Even if we move the whole energy economy away from fossil fuels we'll still be using oil for lubrication, plastics, asphalt, and a bunch of other things. That is fine.
- giantg2 5y ago
  Eventually it is a problem - they are not renewable. Are all the components usable for these other uses? I thought some distillates only worked for some uses (can the gas portion be used for asphalt?). I would also imagine there is immense heating from the road surfaces. Not to mention the fumes, chemicals used in the processing, and all the transportation.
  - richiebful1 5y ago
    If we're not burning petroleum for heating/electricity anymore I imagine our reserves will be enough for thousands of years of roads, chemicals, synthetic materials, etc. By then we'll have developed alternatives, if not sooner
    - giantg2 5y ago
      I think that's wishful thinking on the timeline and a very hopeful outlook for technology to save us. It also doesnt answer the question of if some of the byproducts are only useful for burning. If I remember right, gasoline was originally considered a byproduct.