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EVs now cleaner than a 50mpg car for 60% of the population!

Discussion in 'Prius, Hybrid, EV and Alt-Fuel News' started by Zythryn, Sep 18, 2014.

  1. Zythryn

    Zythryn Senior Member

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    Thanks!
    This was the one I found... http://www.transportation.anl.gov/batteries/us_china_conference/docs/vehicle_demos_day2/WTW_PHEVs_Phase_2.pdf
    Holy cow, the IL regional grid is really messed up!
    Most of the data I saw supported the idea that LESS coal is used under a "smart charging" scenario, while under the "unconstrained" scenario marginal coal use did indeed go up.
    This is outside of the IL grid region. In IL it seemed marginal coal use went up regardless of the scenario;)

    Unfortunately, other than the broad scenarios, they didn't break down the marginal grid affects by time.
    This generality doesn't invalidate the study, it just isn't perfect.
    I would put forth that is the identical reasoning to the UCS study. Just because it isn't perfect doesn't mean nothing can be learned from it.

    What we can take from these studies is that PHEVs and EVs are better than the average car, are getting cleaner automatically as our grid improves,
     
  2. wjtracy

    wjtracy Senior Member

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    ...but one little thing I like about the UCS comparison, at least they are comparing to Prius and the answer is EV similar to Prius.

    The more typical Electrification Coalition claim is EV better than the average (25 MPG) car which people assume means cleaner than all cars, And I am thinking there are some scenarios when EV CO2 is close to the average car. Really they are better off not playing with numbers like this... UCS (and Consumer Reports) should be giving us impartial critical review of EV. God only knows when Prius came out every issue CR said it did not make economic sense, but of course they correctly captured the high 95%+ satisfaction rate of Prius owners.
     
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  3. Zythryn

    Zythryn Senior Member

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    The UCS report is one of the clearest reports I have yet to see on the subject.
    You can't fault the report writers for unsupported and incorrect assumptions readers make, such as the average car being equivalent to all cars.
    The UCS reports also shows the equivalent GHG mpg equivalent under the worst circumstances (electricity sourced from 100% coal).
    Even in that scenario, with 2009 data, EVs were better than the average car, although not as good as a high efficiency car such as the Prius.
     
  4. SageBrush

    SageBrush Senior Member

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    There is actually another study I was thinking of -- I'll track it down later today. However, this Elgowainy study did take into account time of day, but I think they homogenized the results based on assumptions of when the cars charge. I'll have to read it again to be sure. My recollection about the granularity was wrong -- they looked at regional marginal emissions. However, since the grids are actually regional grids -- maybe that is granular enough ?

    Now, to the point: A cleaner average grid does not automatically a cleaner EV imply, specifically because of the choices in marginal emissions. Imagine this scenario:
    A) It is 2 am and the grid is suppling energy that is 80% coal and 20% nuclear. EVs come online, and the coal plant increases production to supply the load. In this case the EV carbon intensity is derived from 100% coal

    B)It is 2 am, 10 years later, and the grid is supplying energy that is 60% coal, 20% nuclear, and 20% clean. EVs come online, and the coal plant increases production to supply the load. In this case, again, the carbon intensity to supply the EVs is derived from 100% coal.

    ----
    So far as I know, the grid outside of CA is considerably cleaner during the day than at night. An unpleasant scenario (which I suspect is pretty common) for a Greenie PV tied to the grid with an EV charging at night is that the PV displaces NG during the day, and charges up with coal at night. Overall the carbon intensity is higher for this person's EV than a Prius owner, even in the specific case that PV was bought FOR the EV. Sobering thought, isn't it ?
     
    #24 SageBrush, Sep 19, 2014
    Last edited: Sep 19, 2014
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  5. Jeff N

    Jeff N The answer is 0042

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    Doubling the fuel economy would have reduced emissions by 50% per mile. A 1970 car emitting 20g per mile of unburned hydrocarbons would be reduced to 10. But doubling fuel efficiency is a hard challenge even today with hybrid powertrains.

    By contrast, the EPA mandated emission controls reduced unburned hydrocarbons by at least 10-20x under real-world conditions. The auto industry lobby was claiming an overall 96% reduction in regulated emissions between 1965 and 1995 based on EPA emission standards and those standards have been tightened significant since then.

    Carbon monoxide and nitrous oxides have been reduced by at least 4x. I remember what pre-control tailpipe emissions smelled like -- reducing that by 25-50% would have still smelled pretty bad. By contrast, tailpipe emissions from a modern car are barely perceptible.

    This handy table is from a report published in 1995.

    http://www.ucsusa.org/assets/documents/clean_vehicles/acfem4qn0.pdf

    image.jpg
     
    #25 Jeff N, Sep 19, 2014
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  6. SageBrush

    SageBrush Senior Member

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    AHA
    http://www.transportation.anl.gov/pdfs/TA/629.PDF
    Also by Elgowainy

    And my fav graphic from that article:

    Elgowainy.png
    -------
    As you can see, so called 'smart charging' INCREASES carbon intensity because it pushes consumers towards charging from coal, where it is more profitable for the utilities.
     
  7. SageBrush

    SageBrush Senior Member

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    Zythryn, the table below is also from Elgowainy, part of a SAE conference presentation in 2011. It summarizes findings from his published articles noted above but is easy to follow. This is 'smart' charging. It shows marginal emissions in action.

    Elgo - table.png

    It should be clear to the open-minded by now that grid charging of an EV has a carbon intensity in the range of NG to Coal, and that use of 'average grid carbon intensity' is simply wishful/poor thinking. And excuse me saying so, but I have been pointing this out for 5 years. I sure wish at least my Green friends at PriusChat would accept the obvious by now.
     
  8. Zythryn

    Zythryn Senior Member

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    You are picking and choosing.
    Look at the detailed graphs showing regional marginalized GHG emmissions. Most have lower emissions. The IL regional grid is such a large exception it takes the average in the other direction.

    Update---
    Your hypothesis seems to be that the marginal use will not improve as the grid as a whole does?
    As your table shows (also shown in my link), some grids actually cut coal use for increased power use. Yes, NG use increased, but the far more intense coal actually decreased in the CA grid.
    This is a good example of improvement being available in both the average grid composition as well as marginal requirements.

    Of course, all of this is based on the general grid and not calculating additional renewables and conservation that is a direct result of plugin ownership.
     
    #28 Zythryn, Sep 19, 2014
    Last edited: Sep 19, 2014
  9. SageBrush

    SageBrush Senior Member

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    Grab a specific graph please. I think what you are pointing out is that it is common for a non "IL" type grid to supply EVs by NG. That will typically be less carbon intensive than the regional grid average. This is why I say that carbon intensity related to EV charging is as low as NGcc and as high as coal in an old crap plant.

    Colorado could be a place where wind comes on line for night time EVs but power politics and old coal plants are currently winning here, too.
     
    #29 SageBrush, Sep 19, 2014
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  10. SageBrush

    SageBrush Senior Member

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  11. Zythryn

    Zythryn Senior Member

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    The graph you picked out is good, look at the details.
    CA had a negative coal use and additional NG use, overall minimal. And again, they are calculating based on kWh, not efficiency.
    My understanding is that a coal plant running at low temps, as the demand for electricity is low, is less efficient, leading to higher carbon intensity.
    Creating more demand allows the utility to run at a higher efficiency, thus lowering the carbon intensity of the entire grid.
     
  12. SageBrush

    SageBrush Senior Member

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    Zythryn,
    I promise -- last barrage.
    This author is a Prof at UC berkeley
    Source: Marginal vs. Average Generation: The Case of the Electric Car |
     
  13. Zythryn

    Zythryn Senior Member

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    Yes, I came across that in my Google search.
    It reads as an opinion piece, certainly not objective.

    Comparing a Honda Fit to a Leaf? That is no better than the comparisons of the Fit to the Prius.

    The point of marginal grid use is a very valid one and should be considered.
    The added illogical comparisons simply weaken the valid points.
     
  14. SageBrush

    SageBrush Senior Member

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    Post #27: The table shows that of the grids analyzed, only 'CA+imports' has a reduction in coal use as EVs come online. Thank Enron ;)

    My point -- I doubt it qualifies as a hypothesis -- is two-fold:
    1. Overwhelmingly today, fossil fuels cover the margin.
    2. The oft declared rally that 'EVs get cleaner as the grid gets cleaner' is a canard.
     
  15. SageBrush

    SageBrush Senior Member

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    Written for laypeople and informally to be sure, but the man is speaking in an area of his very substantial expertise. Give him a break ;)
     
  16. Zythryn

    Zythryn Senior Member

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    No argument with the first part.

    As I have already shown from the table you provided, there is a wide variety of grids, and improvement is possible.
    The huge step forward will be when grid level storage is solved economically.
     
  17. -Rozi-

    -Rozi- Member

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    I bought a PiP because I did my calculations and estimated it will cost me less than a regular gasoline powered car of approximately equal size and trim level over a life span of a car. So being economical was my primary motivation to convert to PHEV. Although ecology is very important, it was not my primary motivation when choosing the car. To me it's just a welcome side effect of using less resources in my daily life.

    The PV grid powering our house and my PiP was also purchased based on economic motivation. It'll pay out itself in like 10 years due to government subsidies. Again beeing green is a welcomed side effect, but no more than a side effect.

    That's what I was trying to say.
     
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  18. SageBrush

    SageBrush Senior Member

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    I'm not sure what this means, other than the obvious: if cleans energy was cheaper for the utility than dirty energy, clean energy would be used.

    The only other routes are political will to give priority to clean energy when available; or my choice: the clean energy provider to the grid gets paid regardless of whether the energy is used. I'm pretty sure that the latter suggestion will magically result in the grid operators finding that they can in fact incorporate the clean energy into the grid.

    Addendum: Oh, now I think I understand your point. That time shifting is required to utilize clean energy that is produced in excess in real time. It is only 'excess' in the sense that the utilities prefer to use put their filthy coal plants online first at full capacity.
     
    #38 SageBrush, Sep 19, 2014
    Last edited: Sep 19, 2014
  19. austingreen

    austingreen Senior Member

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    Hi Zythryn,

    I have the priuschat member you are responding to on ignore, so I don't know the whole conversation, but agree that if we can get at the data margin electricity makes more sense than average electricity, as phevs and bevs are marginal loads. Here we really need to drill down into figures to see how the cars are charged, where and when. Austin Energy, along with some other groips are studying this, but final reports is not ready.

    In most cases the marginal electricity used by plug-ins is generated by natural gas. In a state like California, which is studies center around, marginal electricity produces more ghg than base electricity because the nuclear and hydro electricity would be generated with or without the plug-ins. In places like texas, the marginial load is cleaner than the base load, with texas marginal load getting close to california's, but the base load generates much more. In other places like Illinois the marginal load consumes a great deal of coal, and remains high in ghg.

    Surveys of plug-in drivers in california and texas show that they often vote for renewables with their pocket book. California buyers often also buy solar (39%) texas buyers often buy wind. The net effect is that these new renewables partially offset the ghg load of plug-ins on the grid.

    OK so lets look at a source saying marginal load makes plug-ins more dirty than hybrids.
    http://www.cleancaroptions.com/html/Marginal_Grid_Mix_final_paper_copy.pdf
    Lots of data, and lots of analysis, what is wrong. The paper accurately says some states are cleaner for plug-ins on the marginal grid

    Texas, California, New York, New England, etc. Unfortunately it ranks states by percentage of ldv(light duty vehicles( bought. This gives california 13% weight, when it actually has bought 42%. Put lots of weight in the dirty states, because they buy cars not plug-ins, and you get a dirty average. Ok why did the author make such a obvious mistake? We could be generous and say maybe it simply was ignorance, but they are advocating for fuel cells, and its likely they want to pretend fuel cells will make the world cleaner, because they will go where the grid is dirty, that they won't be concentrated in california where the grid is relatively clean. Georgia may have moved up to number 2 in terms of plug-ins, or it may be washington state. Georgia marginal electricity running a leaf produces more ghg than a prius, washington less. Sounds like if all you care about is ghg you would be against atlanta striving to push plug-ins, but.... in 2017 georgia may retire enough coal to make that leaf cleaner. We need to check again in a few years, but on balance these cars reduce oil imports and pollution.

    A few more things to add -this doesn't account for plug-in buyers being a force for change of the grid. They appear to be in california. Except for Alaska and Hawaii the data is relying on 2020 projections from the eia from 2007. EIA assumed more coal and less wind in those projections, and if we revise with current projections the marginal emissions should be much lower. Finally eia from 2007 does not fully account for methane leackage from well to grid, so ccgt and ocgt likely produce more emissions than stated.
     
    #39 austingreen, Sep 19, 2014
    Last edited: Sep 19, 2014
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