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"Your electric car may not be so green"

Discussion in 'Energy, Environment, and Policy' started by voidptr, Dec 16, 2014.

  1. voidptr

    voidptr Member

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  2. Merrill

    Merrill Active Member

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    All the more reason to dump coal!
     
  3. toto_48313

    toto_48313 CAN P #5

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    Another article which is part of the Gas industry game... learn more by reading this, and you will not beleive those articles any more : Merchants of Doubt - Home
     
  4. Firewired

    Firewired Member

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    What a misleading hype by the media. It's not the EVs it's the coal. Bottom line: Coal is bad, and anything that make more use of coal is a worse thing.
     
  5. scaesare

    scaesare Active Member

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    The AP article covering the actual article indeed doesn't say much.

    You can read the actual article HERE

    I'm still trying to digest it...
     
  6. Robert.Boston

    Robert.Boston Model S VIN P01536

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    The full article is available without charge.

    The article concludes that running EVs on electricity from natural gas, nuclear, wind, water, or solar is cleaner than running gasoline cars, an important finding given the fact that most of the sales of EVs has been along the west coast, the northeast, and Florida -- all places where these low- or no-carbon energy sources are on the margin almost all the time.

    Which brings me to my major complaint with this research article: the impact of EVs on the power system should be examined at the margin, i.e. what is the change in pollution? There will be no new coal plants built in the U.S. under current policies, and the older, less efficient coal plants will be shut down by 2020; the remaining, high-efficiency plants will be operating close to capacity. So where will incremental power come from to fuel an increase in EVs? Not coal, but natural gas, solar, wind, and water (and some nuclear, in some areas).
     
  7. scaesare

    scaesare Active Member

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    I’m looking at the actual article referred to by that AP storyand noticed that they opted to ignore that EV’s powered by Natural Gas or WWS (wind/water/solar) are FAR lower than gas, diesel, direct ethanol, or CNG emissions, and that corn ethanol electricity production is on par with them.

    As was mentioned above, coal’s the problem here… for any electricity usage.

    (EDIT: I see Robert.Boston posted similar while I was reading and composing... agreed)
     
  8. AndreN

    AndreN Member

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    #8 AndreN, Dec 16, 2014
    Last edited: Dec 16, 2014
    I ran into this article and of course was pretty ticked off about it, pointing out as others have that the right headline should be "Coal plants are poisoning us and should be shut down". My next thought was: what percent of the electricity from coal-fired plants is consumed by electric cars? I figured it was probably 0.1%. I did some math and came up with a rough answer: 0.03%. So yeah. The solution for coal plants being dirty is not to stop making electric cars because it wouldn't make much difference (yet).

    Assumptions:
    People who own electric cars drive the same average number of miles/year as gas car owners. It may be lower due to lower range of some electric cars?
    I got the average electric car efficiency by just summing Leaf + Volt + Model S 85 and dividing by 3. Probably within 10% of the real number.
    I ignored the real possibility that electric cars are more prevalent in states that have less coal-fired power plants.

    Now the math:
    # of electric cars in US:
    260,000 (source)

    Average miles a car travels in a year:
    13,476 (source)

    Electric miles driven (multiply above two numbers together):
    3,503,760,000

    Average electric car efficiency (wh/mi):
    335 (source)
    or, 0.335 kwh/mi

    kwh used by all electric cars (miles driven * kwh/mi):
    1,173,759,600

    or, 1,173,759.6 mwh

    dividing by 8766 hours per year (365.25*24),

    133.8991 mw of generation capacity needed

    Energy in US coming from coal plants (in 2012):
    1,514,043 gwh (source)

    divided by hours/year,
    172.717 gw
    or,
    172,717 mw of generation capacity in coal plants

    So finally, percent of coal plant electricity used by electric cars:
    133.8991 / 172717 = 0.0775%

    Update: Saghost pointed out this number would be true if somehow all electricity for electric cars came from coal. But currently only 39% (source) of US electricity comes from coal. So the real answer is 0.0775 * .39 = about 0.03%
     
  9. Saghost

    Saghost Active Member

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    If I'm reading this right, you're actually very pessimistic here - your analysis appears to assume that all power for all those electric cars comes from coal - which is less than 40% of the grid overall I believe?
    Walter
     
  10. AndreN

    AndreN Member

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    #10 AndreN, Dec 16, 2014
    Last edited: Dec 16, 2014
    Good point, and you're right. Basically the question I wanted to answer was: you have a coal plant, it produces a bunch of electricity. How much of that is likely going into electric cars? Since only 39% of US electricity is from coal, you'd need to multiply 0.0775 by 39% (percent of US electricity from coal). So it's more like 0.030%. Thanks for catching that!
     
  11. RiverBrick

    RiverBrick Active Member

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    I read the document and they state that for the purposes of their study, all oil is obtained by conventional means. They flat out state that extraction from oil sands is not considered. As for fracking, I'm not sure if they consider it "conventional" or not.

    As for the electricity consumed by EVs, they calculate it as coming from coal according to some 2007 grid average. They absolutely do not consider that much of EV charging is at night, where surpluses often mean that NO extra coal is being burned to fuel EVs.
     
  12. Dutchie

    Dutchie Member

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    EXACTLY, Electric cars are als green as it can be. How power is generated is a totally different discussion which has nothing to do with EV's
     
  13. mknox

    mknox Well-Known Member

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    At one point, there was a blog post by Elon stating that even if the electricity was produced 100% from coal, EVs would be cleaner than gasoline because of the higher efficiencies of the electric motors.

    There is also a fair amount of electricity used in the production of gasoline and let's not forget transportation costs. (Sorry, haven't read the article yet if that is covered).
     
  14. techmaven

    techmaven Active Member

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    Studies like this have many inherent limitations and the assumptions and modeling issues can often obscure the findings. It is good that this study uses the GREET model, so they aren't winging it when it comes to well to wheels calculations.

    Our meaning of "clean" and "green" are also a bit confused here. The number one item this study looks at is fine particulate matter, which is important, but different than greenhouse gases. For fine particulate matter pollution, coal for electricity production is very, very bad and this study bears that out. Compared to gasoline, according to this study, the fine particulate matter pollution is worse with coal and corn grain ethanol. For greenhouse gases, however, even in West Virginia with 96% coal, a Model S has lower GHG output than an equivalent BMW or Jaguar gasoline powered car. You can see this on fueleconomy.gov which has a handy comparison feature with GHG and uses the Argonne National Lab's GREET model data to provide the results.

    It is unclear in my reading of the study so far on the effect of different coal scrubbing and cleaning technologies - not all coal plants are the same.

    The EV grid average is also pretty bad. However, what this study doesn't address is the fact that EV charging usually happens at a specific time of day and EV grid average is an annual average across all the times, 24/7. The largest use of fossil fuels for electricity production is during the peak day in the summer, when every last bit of production is turned on. That's the most coal usage, the most natural gas usage, the most biomass usage, and so forth. Typically, that's not when EVs charge. Instead, we typically charge at night. At night, we use baseload power - that's nuclear, wind, hydro, and the lowest output level of coal and natural gas. The production mix at 1am to 4am is very different from the production mix on average and the production mix during the hottest part of the day. The most pollution actually goes towards your air conditioning as a result, followed by your increased electricity usage for cooking and activities in the evening.

    For me, my Tesla charges off the North Anna nuclear power station at super off peak rates and many of us in the Mid Atlantic and northeast are on primarily nuclear late at night. Many Teslas are sold into areas where hydro, wind, and nuclear dominate late night baseload power. In some cases, the coal plant is running at the rate it would be running whether we charge off of it or not. We are not adding additional pollution, at least not until there are substantially many more EVs in the overall fleet. We should definitely push for time of use rates for EV charging to continue and expand to try to get EVs to mostly charge either at super off peak or during the day off local solar.

    Also, as EVs gain in popularity, then it makes sense for utilities to build more baseload power rather than more inefficient peaker plants. We should also push towards solar charging at work. There are also potentially many possibilities with smart charging, vehicle to grid, and other cooperative strategies that become possible with many battery packs distributed and hooked up to the grid.
     
  15. David99

    David99 Active Member

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    #15 David99, Dec 16, 2014
    Last edited: Dec 16, 2014
    I remember a post by Tesla Motors (not sure where, probably Facebook) when they say that the electricity to transport and refine one gallon of oil to produce gasoline is as much or even more than the Model S needs to drive the same miles as you could with that gallon of gasoline. It's really important to factor in all the pollution and cost and side effects of gasoline when comparing it to electricity.

    Edit: found some good info on how much energy is used to refine oil here

    There is a lot of factors and a lot of numbers and you can pick specific ones to make your case against EVs but it's not the full story.

    In the end, it is always better to use electricity over gasoline cars. You can produce electricity from many different sources in different ways, and most importantly, you can produce it locally. Even if the electric power production right now isn't perfectly clean, it can be changed to become clean. Oil never can. Oil has cause terrible problems around the world, both on the environment and politically (wars).
     
  16. stopcrazypp

    stopcrazypp Well-Known Member

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    I looked briefly at the study. It seems they are assuming EV batteries are produced using coal powered electricity. They also didn't account for the additional pollution of making hybrid batteries (they said other studies show the difference is small, so they didn't do so).

    Basically the main reason why they find such bad results for air quality for the coal and grid average EVs is because coal mining is done in this country and in close enough proximity to the general population. And in general, coal is many times worse for a lot of air quality metrics.

    However, the rest is nothing new in terms of GHG. If everything was 100% coal, an EV is slightly worse considering the full life-cycle.
     
  17. dhrivnak

    dhrivnak Active Member

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    The study conveniently excludes any gasoline refining which we all know is significant. So by focusing only on particulate pollution they are attempting to slant the study.
     
  18. William13

    William13 Member

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    #18 William13, Dec 16, 2014
    Last edited: Dec 16, 2014
    - - - Updated - - -

    Ok, I don't have a clue about the authors' motivation. I have many issues with their methodology. A quick reading of their paper with help from some other forum members' comments. These are a few faults.

    1 They ass/u/me a 2007 US grid. This over emphasizes coal overall use and pollution markedly. Shame on them. Their study is brand new and new numbers are easily available. NG and pollution control concerns have shuttered many old coal plants since 2007.

    2 They assume 100% conventional gasoline. The US uses mostly 90/10 mix with grain alcohol to boost octane ratings and lower cost. This increases "gasoline" particulates. I understand making the 100% assumption but you should not mix apples and oranges. Straight gasoline versus straight coal is Ok but where is typical gasoline versus typical EV?

    3 They used 2020 passenger cars as standard. This only helps improve gasoline fuel efficiency beyond current 2014 cars. EVs get no boost with 2007 grid coal particulates. There are new EPA rules that will shutter many coal plants or improve their emissions by 2020. Where is the parity here?

    4 They include EV battery production as 100% 2007 coal for Tesla Roadster era batteries. No adjustment for improved battery capacity. They obfuscate this whole issue which is huge when doing lifecycle analysis. Battery tech is improving at 7% yearly. They could do all calculations on 2007 and acknowledge their biases rather than hiding them...

    5 Their study should have been better peer reviewed. This study will allow Fox etc to report more FUD about EVs. It has already started as the OP pointed out.

    I am sad. This study could have been so much better.

    Bill
     
  19. techmaven

    techmaven Active Member

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    Actually, I believe they do capture refining emissions since they use the GREET model as a starting point. But as William13 points out, there are many particulars that can throw off the results.
     
  20. basvk

    basvk Active Member

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    Even if it is not greener (which we all know it is), an EV is so much more pleasant to drive.

    And I'll invite the writer of the article to come sit in my garage with my old 1977 Citroen CX running idle with the garage door rolled shut for an hour, and do the same with my Tesla 'idling'. He can then choose again which car is healthier (if he survives).
     

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