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Thread: EV calculator

  1. #11
    Senior Member dhrivnak's Avatar
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    Thank you Michael

    Thank you for putting this together. The only question/issue I have with it is I certainly have not averaged 206 watts/mile in my Roadster. I think I am much closer to an average of 250. I wonder if I drive it much harder than most but I would not think so.
    Last edited by dhrivnak; 2012-03-29 at 05:41 PM.

  2. #12
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    I was curious about the long term savings on EV costs, which might be a nice thing to add to your calculator. Using my local off-peak charging costs at .04422 (yes, Oregon has great off-peak rates), 25 mpg average for gas, and 283 wH/mile (Model S 85kWH / 300 miles), then figuring vs. gas costs at various prices, I get something like the following. Of course, it's not fair to consider increases in gas without increases in electricity, but I, uh, got lazy.

    For long term ownership, I'm thinking it's well beyond a no-brainer.

    Code:
    kWh	$0.0442					
    miles    EV Cost     Gas Cost @4  Gas Cost @5  Gas Cost @6   Gas Cost @7  Gas Cost @8
    0        $0.00       $0.00        $0.00         $0.00        $0.00        $0.00
    10000    $125.27     $1,600.00    $2,000.00     $2,400.00    $2,800.00    $3,200.00
    20000    $250.54     $3,200.00    $4,000.00     $4,800.00    $5,600.00    $6,400.00
    30000    $375.81     $4,800.00    $6,000.00     $7,200.00    $8,400.00    $9,600.00
    40000    $501.08     $6,400.00    $8,000.00     $9,600.00    $11,200.00   $12,800.00
    50000    $626.35     $8,000.00    $10,000.00    $12,000.00   $14,000.00   $16,000.00
    60000    $751.61     $9,600.00    $12,000.00    $14,400.00   $16,800.00   $19,200.00
    70000    $876.88     $11,200.00   $14,000.00    $16,800.00   $19,600.00   $22,400.00
    80000    $1,002.15   $12,800.00   $16,000.00    $19,200.00   $22,400.00   $25,600.00
    90000    $1,127.42   $14,400.00   $18,000.00    $21,600.00   $25,200.00   $28,800.00
    100000   $1,252.69   $16,000.00   $20,000.00    $24,000.00   $28,000.00   $32,000.00
    110000   $1,377.96   $17,600.00   $22,000.00    $26,400.00   $30,800.00   $35,200.00
    120000   $1,503.23   $19,200.00   $24,000.00    $28,800.00   $33,600.00   $38,400.00
    130000   $1,628.50   $20,800.00   $26,000.00    $31,200.00   $36,400.00   $41,600.00
    140000   $1,753.77   $22,400.00   $28,000.00    $33,600.00   $39,200.00   $44,800.00
    150000   $1,879.04   $24,000.00   $30,000.00    $36,000.00   $42,000.00   $48,000.00
    Last edited by ckessel; 2011-10-27 at 10:09 AM.

  3. #13
    Happy Model S Owner
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    Quote Originally Posted by ckessel View Post
    I was curious about the long term savings on EV costs, which might be a nice thing to add to your calculator. Using my local off-peak charging costs at .04422 (yes, Oregon has great off-peak rates),
    Our electricity is now about .08/kWh. Which is extraordinary, since it was .11/kWh a year ago, and I'm paying for "all-renewable". It actually went *down*, and significantly, too. I should probably make a topic about electric price trends... but anyway, imagine that the electricity is free, since it's close enough to free, and I'll assume that for the rest of this post. Widespread solar panel adoption, together with continually improving solar panels, as well as major efficiency programs by big users, the great lightbulb change, improved heating efficiency, and so on, should keep driving prices down for a while.

    25 mpg average for gas, and 283 wH/mile (Model S 85kWH / 300 miles), then figuring vs. gas costs at various prices, I get something like the following. Of course, it's not fair to consider increases in gas without increases in electricity, but I, uh, got lazy.

    For long term ownership, I'm thinking it's well beyond a no-brainer.
    *Sigh*. For you. I just don't drive enough.

    I'm probably doing around 5000 miles a year. Assuming that I'm comparing the Model S Signature to a $69,900 fully loaded luxury car, assuming I get the $7500 tax credit, and assuming that I consider $5500 to be the Signature premium (the difference between my "fully loaded" Standard specs and the Signature price), and assuming no extra delivery charges, then at current prices, I have to keep the car for 16 years to break even. (This doesn't account for cheaper maintenance.)

    If gas averaged $8/gallon over the next 8 years (it won't, as it would have to hit $12 by 2020) I would still take 8 years to break even.

    Of course, I expect the car to still be in good shape in 16 years, which should still give me a better TCO than a gas car. But for me, it's close, and it depends on the car's durability, maintenance costs/difficulty (which I expect to be lower),

    For people who drive more, electric really *is* a no-brainer. If you drive at least 10,000 miles per year, you can halve all those years-to-break-even numbers.
    Of course, electric cars aren't going to be competing against pure gas cars for long, not with those numbers!

    They'll be competing against plug-in hybrids with relatively efficient onboard generators. Hybrids are already starting to dominate the market, and there's really no reason why they aren't plug-in, so eventually they will all be plug-in. Comparing a BEV to a PHEV requires a rather different TCO spreadsheet, as it requires one to consider "percentage of time gas-free"; maintenance costs will start to loom very large as a difference between the BEV and the PHEV; while the weight of the generator and gas tank in the PHEV will be balanced against that of the battery in the BEV when computing wH/mile numbers.

  4. #14
    Model S VIN P01536 Robert.Boston's Avatar
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    FYI, wholesale electricity prices have been falling like a rock, too. In October, the benchmark east-coast price (confusingly called PJM Western Hub) closed at over $55/MWh (5.5cents/kWh) for February delivery; today it's at $38.55/MWh. And these are the peak hour strip prices! Even summer strips are trading for only $46/MWh currently; last summer, PJM peak summer prices averaged about $65/MWh. It's natural gas prices.

  5. #15
    Senior Member Lloyd's Avatar
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    Hmmm...... And Locally next to Diablo Canyon PG&E released several weeks ago that consumer rates will be going up 4 to 8% across the board for all users.
    SP-2823(sold), Tesla/Rav4EV, P+17252, XP-12

  6. #16
    Model S VIN P01536 Robert.Boston's Avatar
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    Welcome to the world of buying over-priced renewable power and associated long-haul transmission lines, Lloyd.

  7. #17
    Senior Member Lloyd's Avatar
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    Yes, as I am sure you are aware, the renewables are required by state mandate, and now the cost of that is being passed on to the consumers. We agree on this one!!
    SP-2823(sold), Tesla/Rav4EV, P+17252, XP-12

  8. #18
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    Quote Originally Posted by Robert.Boston View Post
    FYI, wholesale electricity prices have been falling like a rock, too. In October, the benchmark east-coast price (confusingly called PJM Western Hub) closed at over $55/MWh (5.5cents/kWh) for February delivery; today it's at $38.55/MWh. And these are the peak hour strip prices! Even summer strips are trading for only $46/MWh currently; last summer, PJM peak summer prices averaged about $65/MWh. It's natural gas prices.
    Interesting. So you think the electric price drop is due *entirely* to a natural gas price drop?

    The next question is, why does the downward electric price movement seem to *exceed* the downward gas price movement? I'd expect something related to the elasticity of demand, availability of substitutes, marginal consumer phenomenon, etc., but I haven't thought it through.

    I could take a stab at this. Natural gas provides peaking demand for electricity and quoted electricity prices are for peaking demand. There are alternatives for peak power, and if natural gas prices get too high, utilities will switch to them, so the upside price effect is capped. However, demand shifts slowly, so any demand reduction due to previous high prices sticks. And the reduction in peaking demand will cause the overall costs to be affected more by the lower baseload prices. However, the rest of the natural gas market has fairly inelastic demand, and the price will only be affected directly/linearly by demand reductions; there will be no second-order effect. Where electricity can have a strong response to demand changes due to a reduced percentage of electricity usage being from peaking plants, gas can have no similar effect, as it doesn't currently have a significant number of wildly differently priced sources which can be taken on and off line easily. (Though it should, shouldn't it?)

    It's just a guess.

  9. #19
    Model S VIN P01536 Robert.Boston's Avatar
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    On the supply side, the bid stack of units runs like this: renewables, nuclear, coal, gas, peaking oil.* Given the huge gap between oil and (natural) gas prices, there's a huge jump in electricity prices in hours when you have to use the few remaining oil-burners. Otherwise, in the northeast, the price is set by some gas unit. However, all gas units are not created equal: the most efficient ones are used first, with less efficient, more costly ones layered in above that.** So, electricity prices are actually more volatile than gas prices, and shifting demand by a good bit has a very strong effect on prices. So, while I'm sure that electricity prices and natural gas prices are tightly linked, the relationship isn't always one-to-one.

    * Gas is now cheap enough that high-efficiency gas units are often cheaper than some, or many, coal plants.
    ** Sometimes expensive units in load pockets, like New York City, need to be on even if cheaper units upstate have spare generation capacity.

  10. #20
    Roadster NA #1026
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    The WSJ had an article a day or so again regarding Exxon continuing to produce natural gas while other produces are cutting back due to low prices. Makes me wonder if they see that high natural gas prices would accelerate/justify development of other/renewable electrical generation.

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