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How may EVs does it take before demands become an issue for the Grid?

Discussion in 'Model S: Battery & Charging' started by thegruf, Aug 30, 2015.

  1. thegruf

    thegruf Member

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    Just wondering about this.

    Already there may be local issues at SCs when all bays are occupied whether full charge rates are available for all vehicles.

    But could this actually become an infrastructure issue, where the software maybe in conjunction with the utilities has to start budgetng for some diversity of charge times.
    Overnight is generally good due to lower overall demand, but what about commute times/evenings?
     
  2. JanoSicek

    JanoSicek Member

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    Some back of the envelope calculations:
    Total electricity generated in 2014: 20000 TWh (world), 4400 TWh (USA)
    If you drive a Tesla 10000 miles a year, at 300 Wh/mile that is 3MWh per Tesla car.
    Therefore if all electricity in the world was used for driving Teslas only, the planet would support 6.66 billion cars. USA alone would support 1.5 billion cars.


    Apparently USA has about 250 million cars, so if USA boosts its electricity production by 16%, everyone can drive a TESLA. That would save 130 billion gallons of gasoline per year. And Wolfram Alpha says this about the quantity:

    omparisons as volume:

    [​IMG]



    [​IMG]






     
  3. tessnme

    tessnme Member

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    Since most of us are charging during off peak usage times, I doubt EVs will cause any grid problems at all. What little impact we have on peak usage will be offset by lower electricity usage for refining oil 24/7. BTW, power companies are expecting the increased use of solar to move the peak usage time from 1-7pm to 4-9pm and are changing their rates accordingly.
     
  4. JohnSnowNW

    JohnSnowNW Active Member

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  5. thegruf

    thegruf Member

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    ^ good find - thankyou.

    Interesting that they already are considering utilities "talking" to the cars to increase the diversity of charging times as I speculated.

    And yes, I guess the grid overall could probably cope (there's usually quite a substantial amount of peak reserve power that can be tapped into) but like everything there's always the weakest link, one cable, one transformer etc. so this will more likely initially show itself as individual streets, neighorhoods.
     
  6. MsElectric

    MsElectric Active Member

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    Not as much of an issue as you'd think because due to energy conservation issues electricity use has actually started to go down or plateau in many developed countries.

    With the additional of solar and wind, the grid should be able to handle whatever EVs are bought...
     
  7. David99

    David99 Active Member

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    If my calculation is correct: the USA uses aprox 3600 tWh per year. Night time demand is about 3/5 of daily use. In other words 2/5 would be available during the night without any grid upgrade or additional power plants whatsoever. Assuming an average EV needs to charge about 30 kWh a night the current grid could theoretically handle ~ 130 million EVs. In reality it probably isn't quite as simple without upgrades. But even if we just take half of that. That's still 60 million EV that the grid as it is now can handle. We don't have to worry for a long time.

    My calculation 3600 tW * 2/5 / 365 (days) *1000 *1000 *1000 (from tW to kW) / 30 (what each EV needs) = 131 million.




    Electricity Demand
     
  8. Khatsalano

    Khatsalano Member

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    Also, keep in mind that refining gasoline takes a TON of electricity. It actually takes more electricity to refine gasoline per mile, than actually straight-up using the electricity to direct-drive the car. You will find that the largest commercial utility customers are Chevron/Shell, etc. :) They use more electricity than anybody.

    The grid can handle it. What the grid is not yet able to handle, is bidrection distributed generation with solar ... that is actually much more of an imminent problem to solve than growing EV charging demands.

    - K
     
  9. Saghost

    Saghost Active Member

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    The grid can take it. A while back I attempted to assemble the problem and perspective from the top down on GM-Volt using EIA data and other government sources as best I could:

    What would happen if everyone switched to EV?



     
  10. aesculus

    aesculus Still Trying to Figure this All Out

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    Most Calif utilities have time of use rates for EV's that convince customers to charge off peak, thus avoiding the issues. Simple solution that requires zero or little automation other than what is already built into the cars chargers.
     
  11. tliving

    tliving Member

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    There's a race on between solar and EV and I think Solar is winning. I think 100% will be able to go EV if the solar movement continues. More than just the electricity I need to drive my Model S is generated by SolarCity.
     
  12. TaoJones

    TaoJones Beyond Driven

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    Similar to to what I was going to add. How many EVs will it take before refineries reduce their ginormous power consumption requirements? A 5% reduction, collectively, would power one's choice of small countries.
     
  13. Saghost

    Saghost Active Member

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    Do you have data for the first point? The best studies have read say that it's a misconception, that the 6-8 kWh per gallon to refine that you find in lots of places online is actually total thermal energy input and 90% of it is provided by burning fuels at the refinery.

    I mostly replied because of the second point, though. I'm not seeing how distributed solar generation could possibly be a threat to the grid...

    Adding distributed generation to a distributed load reduces the loading at every transformer and substation, requiring less capacity. Why is this going to lead to an overload?
    Walter
     
  14. nwdiver

    nwdiver Active Member

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    Yup... solar is definitely winning... the US added ~6.2GW last year... that's ~9TWh of additional generation from solar alone or ~27B EV miles.

    You would need ~1.8M cars driving 15k miles each to cover 27B miles.... the US only added 123k to it's EV fleet last year :crying: (yeah... people suck... what're you gonna do?)

    Not even close to being an issue... we're adding >10x as much solar production as EV consumption. Solar is also growing faster than people are choosing responsible transportation so that gap is growing.

    To the refining point... there's another thread that discussed that... the amount of ELECTRICITY is actually small... <400wh/gal. Most of the energy used is not electricity.
     
  15. pkz0125

    pkz0125 Member

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    +1. It would be awesome when the model s is built using solar energy and charged using solar too. I am getting my car in a month and solar panels in 2-3 months. My car won't cause any issue for the grid :).
     
  16. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    There are two threats to the grid from Distributed Solar PV, technical and economic.

    The technical threat has to do with large percentages of "dumb," correlated Solar PV. Adding and removing generating capacity is a big deal for the utilities. Normally, they rely on a "law of large numbers" averaging effect for the total load to change slowly. The problem is that events like clouds going over a neighborhood or city are very correlated events; when the amount of generation from Solar PV is large and comes and goes in unison, managing the generation to match that is a big deal. This is not an issue when solar is a fraction of a percent of total use, but when it becomes 10's of percent, problems occur. I personally believe that the best solution is to add storage that is something like a half hour of maximum production, then use that to make all "ramp up/ramp down" events to happen over 30 minutes or more. This allows the grid to have time to react.

    The second, economic problem is caused by net metering which effectively uses the grid as a big battery that you don't have to pay for. The maintenance of the grid costs money. Right now, the connection fee for most residential customers does not cover those costs. I very much believe in net metering as a way to encourage Solar PV installs, but I also recognize that there are costs to the utility of being the "battery" for solar producers. Perhaps, some sort of additional connection fee for Solar PV, say $1 per kW DC should be added to the base connection fee; that would be an additional $10 per month for a 10 kW; maybe $0.50 per kW for a system with local storage and slow ramp up/ramp down and $2/kW for systems without local storage to encourage customers adding local storage. As more and more Solar PV goes in the fee for non-battery systems probably needs to go up to keep the grid stable.
     
  17. Bangor Bob

    Bangor Bob Member

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    Even at "just" 400wH/gallon, when you consider we demand 19 million barrels a day, the electricity used adds up very quickly. I make that 320GWh/day, 120TWh/year. A continuous demand of slightly more than 13GW (roughly equivalent to ISO New England's minimum nighttime demand), or just about 9 1.5GW nuclear reactors 24/7/365.

    And then we burn it at an average thermal efficiency in the low 20% range, and lose another 10-30% of that by the time it gets to the wheels... Yeeesh.
     
  18. mknox

    mknox Well-Known Member

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    The biggest issue is not energy, but rather demand (specifically, concurrent demand). For most utilities, the choke-point is the local distribution transformer. For the most part, generation, transformer station and feeder capacity is adequate. So too are the service conductors into the home which are sized to the size of electrical service you have. On the other hand, the local transformer (up on the pole near your house, or the green box on the lawn) is sized taking into account the diversity of most electrical loads. Typical loads are not all on at the same time. They cycle on and off. So the 6-10 homes that may be connected to a single transformer won't overload it due to this diversity. These transformers are also designed to have a "cooling period" overnight when loads are typically lower and temperatures are cooler. Now throw in a couple of continuous load EV chargers and you have trouble. Big trouble if everyone starts buying EVs and charging them all at the same time. In some cases, a larger transformer can be substituted and financed through the increased revenues the utility will see, and in other cases, utility demand response technology can communicate with EVSE and "schedule" charging sessions throughout the night so that everyone's car is not charging at the same time.
     
  19. Bangor Bob

    Bangor Bob Member

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    Multiple studies are already finding that utilities are underpaying for solar at net-meter prices, vs. the benefits received by the utility from distributed solar generation. The trick is to count all the benefits the utilities receive, rather than just counting raw kWh in/out. Here's a synopsis of one: Maine PUC’s Solar Power Study Released Today Shows Enormous Benefits
     
  20. MrClown

    MrClown Autosteer Beta Tester

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    Cottonwood's points are exactly right. I'll add that solar doesn't generate at night which is when most EVs will charge. Imagine a world (maybe 50 years from now) where everyone has solar + EVs. We generate a ton of distributed electricity during the day but then use a ton of electricity at night to charge our EVs. Local storage is the only good solution I can see for this whether it's at the customer location or at the neighborhood or substation level. Fortunately, someone is stepping up in a big way to facilitate exactly that solution (thanks Elon!). Battery storage will keep solar's continued growth viable, stabilizing the grid and defending against the naysayers who can't see past the end of their nose into our inevitable renewable energy future.

    - - - Updated - - -

    Energy is energy. That "most" that is not electricity could be used to make electricity instead or do lots of other things, no?
     

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