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PHEV Emission Comparison

Discussion in 'News' started by doug, Apr 23, 2008.

  1. doug

    doug Administrator / Head Moderator

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  2. WarpedOne

    WarpedOne Supreme Premier

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    Our CO2 emissions are important for what exactly?
     
  3. Tesla2Go

    Tesla2Go Member

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    Solar has almost as much CO2 emissions as gasification with CO2 storage? Seems strange....
     
  4. Cobos

    Cobos S60 owner since 2013

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    That seems pretty normal as solar in those data has 0 CO2 emissions and coal with CO2 storing has a little bit, as in 16. The big yellow part of the graph is the gasoline part of the hybrid drive.

    Cobos
     
  5. BBHighway

    BBHighway Member

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    I always wonder about these things - are they really counting just the end product of gasoline, or including the entire oil production chain, drilling, pumping, shipping, refining, etc. Those steps can be quite energy intensive.

    The figure I've seen before was that gasoline production is 85% efficient. That comes from the oil&gas industry, and so far as I can tell, they don't supply any details that one could use to verify that. I think that is likely a best case number, and typical is probably much worse, but there is no way to prove it.

    If you've ever read about everything that is needed for modern oil production, it is hard to believe they achieve anything like that sort of efficiency.

    Then there is flaring of natural gas. I'm almost positive they don't count that, since it doesn't go into making gasoline; it's a by-product. Still, if you're counting CO2 emissions, that really needs to be included whenever gasoline is burned. Again, actual figures from the oil industry are hard to find.

    Then if you really want to get into it, a rising percentage of oil production is from the oil sands/oil shale/tar sands. Producing oil and ultimately gasoline from that stuff winds up producing two to three times as much CO2 as regular oil and gas production.
     
  6. Hunter

    Hunter Member

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    Well, they claim to be considering the whole production chain's emissions. The part I don't like is that they aren't specifying the driving conditions or the specs of the plugin hybrid. How many miles are being driven? What's the electric range? If they used the Volt's range and an average daily drive for the miles driven, I would think there would be no gas-based emissions in the chart for plugins at all. Changing either of those numbers can push the chart around in any direction you like, so the table is really just about arbitrary.
     
  7. graham

    graham Active Member

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    IBT comparison of of hybrids vs Roadster and Mini-E and claim the hybrids have lower emissions compared to the energy production used to create the electricity.

    http://www.ibtimes.com/articles/20090220/electric-cars-emissions-problem-times-more-than-hybrids.htm

    [​IMG]

    Of course their chart assumes that you are producing electricity using 100% coal. They mention in the text of the article that coal is less than half of what is produced in the US today, but didn't let that stop them from making their claims.
     
  8. stopcrazypp

    stopcrazypp Well-Known Member

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    #8 stopcrazypp, Feb 20, 2009
    Last edited: Feb 20, 2009
    Funny how I just commented on autobloggreen this article http://www.autobloggreen.com/2009/02/20/automobilwoche-editor-widespread-electric-cars-will-take-15-mor/ that they tend to almost always assume 100% coal, even though it is very rare this will be the case.

    I'll just redo a calculation I did but for lbs/100mi rather than grams/km:
    35kWh and 104 mile combined range from the Mini-E spec sheet to get 33.7kWh/100 mile (this is to be fair since the brochure gives a 0.14kWh/km number for city driving only, rather than combined)
    http://www.miniusa.com/pv_obj_cache/pv_obj_id_13382CB3DE5965A128742ED5AF950647FC510200/filename/Mini-E-spec-sheet.pdf

    Times 724lbs/MWh from my local power company (California PG&E) and I get CO2 Emissions of 24.4 lbs/100miles.


    Using the US national average grid CO2 emissions of 1329lbs/MWh, I get 44.8 lbs/100 miles.

    And keep in mind I am using the more "real world" combined driving number of 104 miles rather than 150 miles that they used in their calculations; if I used the 150 number the difference would be even more dramatic.

    Obviously the results change drastically depending you using 100% coal, the national average, or sources cleaner than even the national average (like my power company does).

    It's very easy to get CO2 numbers for your power company using the below link and compare it to the national average.

    How clean is the electricity I use? - Power Profiler | Clean Energy | US EPA

    Edit: Anyone a member at IBtimes? If there is, feel free to post the numbers I calculated there just to show the errors in their analysis.
     
  9. Joseph

    Joseph Member

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    #9 Joseph, Feb 20, 2009
    Last edited: Feb 20, 2009
    Also, of course, they didn't include the energy it takes to produce the gasoline.

    The only thing the article claims is that EVs - powered by coal - are roughly just as good as hybrids. I've read that elsewhere. It sounds like it's true. But we don't need to worry because only half our energy comes from coal.

    In addition, most of the places where EVs would be most popular (California and major cities) are the places where energy production is cleanest.
     
  10. mt2

    mt2 Member

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    Interesting.

    I looked up my electric source mix and found that we're using 72.8% coal compared to the national average of 49.6%. There's also 2.7% natural gas in there, but the bulk of the remainder is nuclear.

    So I did some simple back of the napkin math and just multiplied the CO2 emissions of the Roadster and Mini E by 75%. The Roadster showed 35.6 lbs/100 miles and the Mini E showed 39 lbs.

    Hence, both beat out the the best hybrid, the Prius, even with our neighborhood grid being nearly 50% dirtier than the national average.
     
  11. stopcrazypp

    stopcrazypp Well-Known Member

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    Yeah, that's because they used the most ideal numbers for both the Roadster and the Mini.

    The way I did it was using combined city/high range numbers which is how CO2 emissions numbers are supposed to be calculated.

    I used 104 miles of combined range instead of 150 ideal max, so if I adjust your result for the 104 miles, I get 39lbs/100miles*150/104 = 56.25lbs/100miles

    Which kind of makes more sense since you wouldn't expect to get lower numbers than the average when your area is clearly dirtier.
     
  12. vfx

    vfx Well-Known Member

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    This is what I got -except the word "good" get's replaced with "bad".
     
  13. Joseph

    Joseph Member

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    "This is what I got -except the word "good" get's replaced with "bad"."

    Yes, but it is a good thing! Imagine a coal car as clean as a hybrid? Only an EV could do that.

    Well, actually, there's an exception. Coal powered EVs are just as clean, and are cleaner in terms of most pollutants, but are dramatically higher in SO2. I think it's SO2, or some other nasty something. Then again, at least it's not being released directly in our cities.
     

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