It's here:
Global Warming Emissions and Fuel-Cost Savings of Electric Cars (2012) | Union of Concerned Scientists
Full report at the bottom of the page.
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UoCS Study: How Green are Electric Cars?
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Global Warming Emissions and Fuel-Cost Savings of Electric Cars (2012) | Union of Concerned Scientists
Full report at the bottom of the page.
There was no attempt whatsoever that I can see, with a quick perusal, to address well-to-wheels for ICE cars.
Haven't found the calculation, yet, but see page 8 of the full report where they say that they do. The Technical Appendix goes into great detail on how they calculated it for electric vehicles.
Edit: They use 11,200 grams CO2 / gallon of gasoline which they took from GREET. The actual burning of a gallon of gas will result in 8,170 grams CO2.
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hjr
#1291
Why do the critics always use the Leaf or Volt as examples. The Leaf they say takes 0.34 kwh/mile. Today onthe highway in my Roadster 2.5 Sport I used 0.24 kwh/mile. In Connecticut they said the Leaf gets equivalent of 67 mpg, but if you use the actual numbers i get on my roadster it is more like the equivalent of a 95 mpg car.
It's pretty easy to do a thought-experiment comparison of electric to ICE. Make the assumption that coal, the dirtiest source of energy for electricity, causes as much CO2 creation in the mining and shipping process to get it to the power plant as oil causes from the drilling and pumping at the well to shipping/pumping it to the refinery. Then, take the energy alone used to refine it into gasoline at 5-7kWH and stick that energy directly into my Roadster. I've just saved 19 lbs of CO2 from being created by not burning that gasoline, and I can now drive 20 miles using the 5kWH, the same distance a performance-comparable Porsche 911 Turbo could have driven on that gallon of gas (on average... they're 16 city, 24 highway). If they argue that the transmission line losses make up the difference, remind them that we didn't have to truck that gasoline from the refinery to the gas station, and it didn't have to evaporate as it was being pumped into the ICE car.
It's a simple explanation, and it proves our point definitively.
It's a simple explanation, and it proves our point definitively.
DuncanWatson
Member
I went through the Prepublication paper as well and though found references to well to wheel, I couldn't see anywhere were the cost was calculated for an ICE vehicle. It calculated the cost of EV to a miles per gallon of green house gas equivelant. No reference to what one gallon of ghg is equal to or what assumptions upstream it makes on the production of a gallon of gasoline.
This means that the work is unverifiable.
JRP3
Hyperactive Member
According to Drees they used the GREET model, which includes upstream emissions for gasoline.
Not without mentioning the capabilities of the Roadster and how that it is entirely reasonable to assume that all EVs will get better with each year and the Roadster is proof.
This kind of report if widely accepted will stop time.
Just like people are stuck on old info and data like "you have to drain the battery" and " the heater and headlight kill range" and memes from the 90's.
At least it kills the "electric cars are dirtier because they run on coal" line that was probably more true 20 years ago.
JRP3
Hyperactive Member
Unless most EV's are going to be small sports cars their efficiency is probably not going to be similar to the Roadster. There is also the issue of charging efficiency, the Roadster seems to use a lot more energy managing the pack than other EV's, which lowers it's actual wall to wheels efficiency.
Does anyone have any actual wall-to-wheels efficiency for their Roadster?
The numbers I see posted on MyNissanLEAF.com seem to vary between the EPA number at the low end, (2.9 mi/kWh) to well over 4.5 mi/kWh. Without thermal management and no significant vampire draws, the LEAF seems to track at 85% of the dash mi/kWh gauge when charging on L2.
Personally, I get anywhere from 3.2 mi/kWh (freeway driving at 70 mph) to 4.0 mi/kWh (city driving) from the wall in my LEAF. My average is around 3.7 mi/kWh or 270 Wh/mi, significantly better than EPA. Which is interesting because in my last car and other car, fuel economy tracked EPA estimates very closely with similar driving habits.
Here's what the technical appendix says:
Perhaps the more knowledgeable forum members can explain a point to me. My understanding is that the efficiency of an EV, as measured in kWh/mile, varies with speed. The appendix doesn't seem to account for this. If we consult Tesla's published values for the Roadster at 55 mph its efficiency is 0.23 kWh/mile or 32% more efficient than the number used for the LEAF. I wouldn't say that a 32% increase in efficiency is "similar". :wink:
Larry
The EPA's published testing procedure for EVs it's nothing like driving at a steady 55 mph and further more, the actual test results are reduce by a somewhat arbitrary 30% to make it more like "real world". Never mind that Tesla's published values for 55 mph driving don't include charging losses which are at least 10-15%.
My real world tests of the LEAF show it around 250 Wh/mi (from the wall) at a constant 55 mph on level ground. Or basically the same as the Roadster once you take into account charging losses.
Tomsax has access to both a LEAF and a Roadster and I believe has performed tests of similar nature?
(runs off to google)
Oh yes, he has: EV Efficiency: Tesla Roadster and Nissan LEAF Compared - Tom Saxton's Blog
His numbers show the Roadster about 5% more efficient at 70 mph. Not unexpected, The Roadster probably has a smaller CdA than the LEAF given it's about half as tall. Results would probably be similar at 55 mph where aero drag is a lower proportion of total drag.
Tom's test does appear to relying on on-board instrumentation from both cars which is also a source of error and makes the assumption that charging losses are similar - ideally one would charge both cars to "full", perform the exact same drive, then measure how much energy it takes to re-charge each car back to full.
Final Edit: Forgot one important thing.
I presume that the EPA tests already do all this measurement and is repeatable. On the highway test, the EPA puts the Roadster at 112 MPGe and the LEAF at 92 MPGe. 20% better - very good!
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Thanks very much for the clarification.
In your opinion does this "somewhat arbitrary 30%" reduction in EV test results actually produce more accurate results, or does it render comparisons with ICE vehicles less fair?
Larry
Norbert
TSLA will win
For me personally? It seems to penalize EV range too much. But for the average person? Hard to say. (BTW - the 30% adjustment factor is also applied to gas cars).
In this post:
Saving money with the Roadster
I noted that I averaged 415 Wh/mi, so 2.41 mi/kWh, in the first 26,000 miles with my Roadster. I do pretty much never try to drive it efficiently and nearly always try to enjoy the acceleration.
Neither it's there because the public doesn't know how to use the EPA ratings. And they made the mistake of using MPG rather than an index number (the way the UTQG for tires does).
The way you are supposed to use the EPA ratings is:
1. Get your average MPG from the logbook that you keep.
2. Get the EPA number for your current car.
3. Divide 1 by 2 to get the ratio. (e.g. 1=30 2=35) so you get 86% of the EPA rating.
4. Get the EPA number for the car you are considering.
5. Multiply 4 by 3 to get the expected MPG that you will get. (e.g. 4=60 3 = 0.86) so you should get about 52 mpg on your new car.
When used the correct way it doesn't really matter what the number is as long as the test is consistently run.
dhrivnak
Active Member
Also remember they are measuring from the plug not the wheels. There is about a
15% loss in charging.
15% loss in charging.
smorgasbord
Active Member
Union of Concerned Scientists EV Study
The Union of Concerned Scientists just released a study saying:
1) Electric Cars Cost $1,200 a Year Less to Run.
2) Electric vehicles also are responsible for fewer emissions than gasoline models even when taking into consideration the output from coal-fired power plants and other generating sources. The environmental advantage varies by part of the country.
I think this is the link to actual study: Global Warming Emissions and Fuel-Cost Savings of Electric Cars (2012) | Union of Concerned Scientists
The Union of Concerned Scientists just released a study saying:
1) Electric Cars Cost $1,200 a Year Less to Run.
2) Electric vehicles also are responsible for fewer emissions than gasoline models even when taking into consideration the output from coal-fired power plants and other generating sources. The environmental advantage varies by part of the country.
I think this is the link to actual study: Global Warming Emissions and Fuel-Cost Savings of Electric Cars (2012) | Union of Concerned Scientists
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