Does a corn-ethanol vehicle beat the Tesla Roadster in lifetime CO2 emissions?
by Sebastian Blanco on Oct 16th 2009 at 2:59PM 
2010 Tesla Roadster Sport – Click above for high-res image gallery
What does it take for a car to "beat" the Tesla Roadster? With a 0-60 time that blows away almost anything else on four wheels, there aren't many vehicles that are faster. With an all-electric drivetrain, the car sits at the absolute pinnacle (along with every other EV) for lowest tailpipe emissions. But is it possible that a vehicle that burns corn-based ethanol (or gasoline!) can beat the Roadster on overall CO2 emissions?
This is the claim from the unbiased folks at Biofuels Digest, who crunched theoretical numbers like this:
- The Tesla gets its juice from a power plant that is burning coal, which means it has 2.095 pounds of CO2 per kWh and can go 3.12 miles per kWh.
- The theoretical corn-ethanol E85-burning vehicle puts out CO2 according to the GREET model (Greenhouse gases, Regulated Emissions, and Energy use in Transportation) for lifecycle emissions and is operating at the proposed new CAFE standards.
Over the vehicles' lifetimes (of 145,000 miles), Biofuels Digest says, the E85 vehicle creates 30 percent fewer CO2 emissions, and the Roadster will even put out 21 percent more CO2 than a car that uses straight gasoline (we tried to dig into the GREET model to see how deep the well-to-wheels model tracks CO2 generation, but didn't see how crop and oil production is specifically handled here. Since GREET has been in development since 1999, we're going to assume the system takes these factors into account). Biofuels Digest uses government data – from the EIA, DOT, Argonne National Lab, etc. – and Tesla's numbers to come to their conclusion. You can find a chart produced by Biofuels Digest after the jump.
At first glance, this reminds us of the Prius vs. Hummer debacle, but we're open to further investigation. Got an opinion?
Gallery: First Drive: Tesla Roadster Sport
[Source: Biofuels Digest via Domestic Fuel]
Reader Comments (Page 1 of 3)
Bob from the ALAMN 10:26AM (10/19/2009)
Well, I can't afford a Tesla Roadster anyhow. It will be interesting when the EV World and the FFV World collide in the form of the Chevy Volt, which reportedly will be produced as a flex fuel vehicles.
PS: Both the Tesla and any FFY can get a reserved parking space at our HQ in Saint Paul, MN. Any alt. fueled vehicle qualifies.
PPS: The first 25 FFVs in at the Minnesota Vikings Gold Lot in downtown Minneapolis on Sunday park for free. Everyone else has to pony up $40 for the parking.
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Jeremy 3:30PM (10/16/2009)
"3.12 miles per kWh"
Simple math here: the car goes 244 miles on a charge. The battery holds 53 kwh of electricity. 244/53 = 4.604 miles per kWh.
I don't know where the 3.12 estimate comes from but, on the face of it, it doesn't seem right to me. We know a Tesla will legitimately do that 244 miles on a full battery and we know the size of the battery.
Although you are trading emissions from the tailpipe for emissions from a power plant, the electric drivetrain is upwards of 90% energy efficienct whereas a gas engine car is about 20-27% efficient. The energy use per mile should be less. I would be shocked if the theory in this article proved to be true, unless coal powerplants are just HORRIBLY inefficient.
Hopefully though, this country will move away from coal as its primary source of electric power generation and into something 'greener.' Not that I think CO2 emissions really matter. It's a VERY weak greenhouse gas, and current human-activity-caused CO2 outputs are such a teeny, tiny fraction of what the earth itself puts out. High atmospheric CO2 relates to times in history of massive plant and life populations. I don't really see the hubbub over CO2. Methane is a much, much stronger greenhouse gas. Water vapor is the #1 most prevalent and one of the strongest greenhouse gasses. I understand emissions regulations for particulates, chemicals, and compounds that turn into things like acid rain, etc. But CO2 provides life to plants and isn't even much of a greenhouse gas... I really don't understand the fixation on it specifically.
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paulwesterberg 3:41PM (10/16/2009)
Coal power plants are only a small part of the energy mix in California. Even here in Wisconsin coal only makes up 50% of the energy mix. I pay an extra $5 per month for wind power for my home.
meme 4:03PM (10/16/2009)
Yeah, that's the most ridiculous part about the "study". Only half our grid power is coal. The next biggest sources, which make up almost all of our remaining generation, are nuclear (near-zero carbon), natural gas (low carbon), hydro (near-zero carbon), and wind (near-zero carbon). And the grid is getting cleaner every year.
Also, last I heard, the GREET model said that EVs were 40% more energy efficient than gasoline cars. So how they're getting worse is beyond me...
paulwesterberg 4:29PM (10/16/2009)
Tesla reports the battery-to-wheel efficiency as 110 Wh/km (5.65 mi/kWh) on an unspecified driving cycle (either a constant 60 mph (96 km/h) or SAE J1634 test[19]) and states a charging efficiency of 86%. This results in an overall station-to-wheel efficiency of 128 Wh/km (4.85 mi/kWh).
paulwesterberg 5:50PM (10/16/2009)
Ok, you can download their crappy spreadsheet here:
http://www.ascension-publishing.com/BIZ/CO2.xls
Check out how they calculate the C02 lifetime E85 Corn(FAIL), it is directly based on the C02 per lifetime gasoline and does not take into consideration the horrible mileage you get on e85.
If your theoretical car got a generous 24.5mpg on e85 you would pay $1,267 yearly for fuel, $230 extra out of your pocket and $312 extra from the federal government so that you could use ethanol instead of gas. Your C02 lifetime ends up being closer to 114816lbs and CO2 savings E85 v electric becomes negative at: -73.9%.
The only way they can claim lifetime cost savings for e85 is by saying that the electric car requires an extra $12k for battery replacement. They also state that the lifespan of the car is 145,000 which means that they expect you to junk your car even though at 145,000 miles it would have lightly used replacement battery ignoring that even dead batteries will have some residual value.
dwarg 3:36PM (10/16/2009)
Here's an interesting study. The Institute for for Hydrogen Bullshit claims that hydrogen powered vehicles will save more lives than ethanol vehicles.
Assuming the ethanol comes from murdered children and the hydrogen comes from magic you can see hydrogen will save 132% more lives than ethanol.
It's simple math really.
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Serge 3:44PM (10/16/2009)
Excellent point, dwarg.
wincros 11:44AM (10/17/2009)
C'mon. Have a heart. Those failed "scientists" from the oil funded anti-global warming reports have to find work somewhere and it is hard when do not have the qualifications or the interest to do real science. Fortunately for them big agriculture's money has found a use for their "sciencey" talents. Wonder whether these are the same "scientists" who created the facts for the clean coal campaign.
occ 3:50PM (10/16/2009)
1. Show me a comprable E85 vehicle that gets 35mpg using purely E85.
2. Show me where you can get 100% coal electricity vs
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Thunderbuck 3:57PM (10/16/2009)
If you look carefully, you'll see it assumes 29.4 MPG for the E85 vehicle.
paulwesterberg 4:55PM (10/16/2009)
which is still too high considering the highest mileage e85 vehicle gets 18mpg.
http://www.fueleconomy.gov/feg/compx2008f.jsp
paulwesterberg 5:15PM (10/16/2009)
btw if you look the difference between gas and e85 on fueleconomy.gov you see that mileage falls by about 30%. They say a 35mpg gas vehicle can get 29.4mpg on e85, but I bet that such a theoretical vehicle would only get 24.5mpg on e85.
Bill 3:48PM (10/16/2009)
I think a volt like car that had an ICE that could use bio-diesel or ethanol would give you the best bang for the buck- I agree with Jeremy's opinion on CO2 probably not being the main culprit in global warming.
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Jeremy 3:50PM (10/16/2009)
Spent a minute on the Tesla site:
***Don't electric vehicles actually just move pollution to another location? And therefore don't EVs still use oil? ***
No. Most electric power generation in the United States does not use oil. Coal, hydro, nuclear, solar, and natural gas are typical sources for generating electricity. Power generation plants, even coal burning ones, are inherently more efficient and less polluting than vehicles due to economies of scale and the ability to more efficiently remove pollutants from a smaller number of much larger fixed locations.
Also, an electric car is far more efficient than a gasoline car, so the amount of pollution generated by producing the electricity to drive an EV a given distance is much less than the pollution from the gasoline to drive an internal combustion car the same distance. Whereas a combustion engine car – even those powered by hydrogen, ethanol, and biodiesel – can make use of around 20 percent of the energy that it consumes, a battery electric car like the Tesla Roadster is able to put more than 80 percent of the energy it consumes to use in moving the car down the road.
You can read more in our Energy Efficiency section. http://www.teslamotors.com/performance/well_to_wheel.php
http://www.teslamotors.com/images/content/well_to_wheel_energy.gif
http://www.teslamotors.com/images/content/ca_electric.gif
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occ 3:52PM (10/16/2009)
1. Show me a comprable E85 vehicle that gets 35mpg using purely E85.
2. Show me where you can get 100% coal electricity vs less than 100% coal electricity in the US.
3. Show me where you can get E85 vs where you can't.
4. Show me where you can get 0% carbon E85 [impossible by definition] (I can show you where I *currently* get my 0% carbon electricity). Show me that you don't use the same 100% coal electricity to refine/produce/ship E85.
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BOB_E 5:41AM (10/22/2009)
I don't believe it. This just does not sound right to me. I would guess, that the ethanol powered car would have to be running at peak efficiency to even get close to the Tesla (electric motors are somewhere near 90% efficient). And lets face it, who keeps their car tuned up ALL THE TIME? Not many, I would think. And even if someone did, I still don't think an internal combustion engine fueled by ethanol can compete with a car fueled by electricity from a coal powered energy plant. Why do I have the sneaky suspicion that this so-called study was funded by the corn producers of America? People will say anything, if you pay them enough money.
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Brammofan 4:00PM (10/16/2009)
I think the GREET model needs to be recalculated based on some changes in the biofuel industry since the original calculations and bases were made. At least, that's what I get from this letter by Michael Wang of Argonne Labs:
http://awakeatthewheel.net/2008/02/20/greet-model-used-wrong-michael-wang-of-argonne-lab-responds-to-science-magazine-study/
BTW, dwarg, I thought hydrogen came from unicorn nipples.
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Thunderbuck 4:01PM (10/16/2009)
This is really the kind of study that Mark Twain had in mind when he wrote about "Lies, damned lies, and statistics."
It assumes 100% coal-fired generation, and we can't be totally sure that the corn lifecycle CO2 is being accounted for. Both of those make this a bit suspect.
I'm not against ethanol (though I'd much prefer cane to corn), but lying doesn't help their cause at all.
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jake 4:02PM (10/16/2009)
Rebuttal by gas 2.0.
He did all the mathematics so I don't have to.
http://gas2.org/2009/10/14/study-electric-cars-produce-30-more-emissions-than-ethanol-cars/
Basically the argument is on the current US electric grid (which is slightly less than 50% coal) EVs are cleaner than both conventional and ethanol vehicles.
Also the average car MPG isn't 35mpg, esp combined mileage: that is the proposed CAFE rule. For ethanol, I don't think you can find a 35mpg vehicle anywhere, even if it is just highway, much less combined.
http://autos.yahoo.com/green_center-fuel_ethanol-cars/
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