The Issue with going all Electric

Discussion in 'Electric Propulsion' started by jehardiman, Sep 5, 2022.

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  1. Scuff
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    Scuff Senior Member

  2. gonzo
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    gonzo Senior Member

    Tesla proved over a century ago that AC is the most efficient way of transmitting electricity by wire over long distances. Can you show any technology that is more efficient?
     
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  3. gonzo
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    gonzo Senior Member

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  4. DogCavalry
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    DogCavalry Senior Member

    The company I work for did a study for the city of Vancouver, Canada's third largest city, to determine how many more electric cars could be added to the grid. The answer was, not many more. BC produces a tremendous amount of hydroelectric power, and sells the surplus. But the distribution grid doesn't exist to switch to a significant number of electric cars. To build up the grid to that level would require an increase in mining to such a level that it would make electric cars irrelevant. And the horrific human toll in cobalt mines makes for a nightmare scenario.
     
  5. fallguy
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    fallguy Senior Member

    I am gonna have to disagree. Here in the US, we still have no realistic plans for nuke wastes. We keep storing it in places that are extremely unwise. There is really not any wisdom or wise regulation on the waste issue. We play, do what's easiest now.

    Plans for Prairie Island nuclear plant face opposition https://www.mprnews.org/story/2009/05/26/plans-for-prairie-island-nuclear-plant-face-opposition
     
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  6. fallguy
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    fallguy Senior Member

    The thing in California is the massive numbers of cars. 6 lanes, bumper to bumper 30 miles burning gasoline is no panacea. Balanced approaches are best.
     
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  7. DogCavalry
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    DogCavalry Senior Member

    California buys our electricity. They can't make enough of their own. If they went all electric, all of ours wouldn't be enough. And the grid doesn't exist to send it to them. And they don't have the grid to distribute it locally. Strip mine half of earth for the copper. Kill every child in the Congo for the cobalt. All better now.
     
  8. DogCavalry
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    DogCavalry Senior Member

    That's not actually disagreeing with me. You're supporting my point. The problem with nuclear power is regulatory incompetence and corruption, not engineering or physics. And you're also conflating American issues with planet earth.
     
  9. baeckmo
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    baeckmo Hydrodynamics

    This is still valid, the standard long distance transmission in EU is 400 kV AC, but in regions where cables have to be buried (urban regions fe), DC is used, because with AC there will be a rapid phase shift along the line. This requires phase correction stations at about every 15 km. The same goes for long distance underwater transport; here DC is the only way to go. I'm afraid comparisons to your leasure boat, Sean, is not very realistic in the scale we talk about here. In a really robust grid you have to use each technology where it is best suited, all are needed.

    Just as DogCavalry said about the transport from production in Canada (?) to consumers in California, at present it is all about transmission capacity and smoothing out the peaks. And with more renewable (read: not possible to plan and lacking storage) production fed into the grid, the greater the problems of meeting variation in consumption patterns. The only realistic big scale compensatory production types available today are hydro and nuclear, like it or not.
     
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  10. philSweet
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    philSweet Senior Member

    Me three. He was, IIRC, in charge of the British Coal Board at the time he wrote it - an industrialist of the best sort.

    But I'm thinking Cadillac Desert might better foreshadow how this will shake out.

    From the OP's original document -
    This doesn't bode well for EVs since we can reduce the lifetime GHG emissions of a ICE by half overnight if we choose to. It will take about 3 days for individuals to adjust. It will take about three years for industry to pivot on the change. The EV can't do that. If GHG emissions really do matter in the calculations, The EV is in deep doo doo.
     
  11. seandepagnier
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    seandepagnier Senior Member

    He did not prove this, and would disagree with your statement. DC is the most efficient way of transmitting electricity by wire over long distances:

    High-voltage direct current - Wikipedia https://en.wikipedia.org/wiki/High-voltage_direct_current

    AC power is less efficient for transmission since the voltage is actually zero some of the time, so it require 3 wires to transmit the same as 2 wires of DC. Furthermore, the corona losses especially at high voltage are higher for AC than DC. The only reason AC power is used is because back then, there was no technology to efficiently convert DC voltages: it has nothing to do with transmission. as a side note: AC is also better than DC regarding galvanic corrosion.

    I am stating that we are basically at the point where AC power at any level could be considered obsolete and the reason it persists is the cost of replacement. The comparison to my boat is reasonable.. as people in much of the world have similar power requirements, and so they dont need power grid. The scenario with limited power grids for certain industries, and localized energy production elsewhere (eliminating transmission lines for the most part) seems the lowest carbon emission scenario, and essentially eliminates AC power completely.
     
  12. seandepagnier
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    seandepagnier Senior Member

    How do you reduce GHG emissions of ICE by half overnight? Cut speeds in half? EV can do that too.
     
  13. DogCavalry
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    DogCavalry Senior Member

    The EV performs well due to a well known principal in economics called externalization. You don't count a significant part of the cost of something because you can make someone else pay for it. As we've already established, the grid simply precludes any sort of meaningful shift to electric vehicles. Massively upgrade the grid, at enormous environmental cost,and recalculate.

    The most efficient way to move and store energy is in the form of hydrocarbons. If we have the surplus generator capacity, make synthetic fuel, distribute it with yhe existing infrastructure, and use it in the existing vehicles.
     
  14. philSweet
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    philSweet Senior Member

    With EVs , GHG are largely confined to the vehicle's manufacturing. With ICE's the GHG is largely in the operation, which is volitional. We have experienced plenty of fuel supply disruptions that required reducing vehicle consumption by half in order to maintain critical heating oil supplies and farm production. So the vehicle side of things is pretty well understood. Reduced miles, fewer cars on the road, and greater occupancy actually lead to higher speeds in most places. But lower density improved fuel economy overall.
     

  15. seandepagnier
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    seandepagnier Senior Member

    As for moving energy, power lines are more efficient than pipelines/ships/trains etc. As for storing energy.. a rock on top of a hill is more efficient than either since batteries self-discharge, and fuel degrades over time.

    Hydrogen can be produced reasonably efficiently, but it has some specific disadvantages. Denser fuels starting with methane have increasingly lower efficiency to produce from electricity. What you are suggesting is the least efficient way of doing things: the opposite of what you claimed. I dont think you are using the same definition of efficiency which is: "the ratio of the useful work performed by a machine or in a process to the total energy expended or heat taken in."
    So by driving half as much, you reduce energy in half? Not quite because of considerable emissions in producing the vehicles (of any type) and roads. It takes enough energy to maintain all the pavement to ensure CO2 levels will always keep increasing even if we stopped all other emissions. Higher speeds are bad because wind resistance is related to velocity squared. Cars designed with a slower top speed can be significantly lower emissions to produce since they dont need as much power, and the energy to push them is much lower.

    The most efficient car: 27,482 MPGe achieved this by traveling at slower speeds, not faster:
    Duke Student Team Wins Second Guinness World Record for Vehicle Efficiency https://pratt.duke.edu/about/news/duke-student-team-wins-second-guinness-world-record-vehicle-efficiency

    This is roughly 1000 times more efficient than typical cars. Similarly it is quite possible to power a 33ft boat more than 600 nautical miles on the energy equivalent of less than a gallon of diesel fuel, but it is rare to see such systems in place. I have such a motor on my boat, and it is not even optimized. It is theoretically possible to exceed 1000 nautical miles per gallon (zero wind and currents, not favorable or unfavorable) on my 33ft boat, but even if I did, it would not come close to the efficiency of sail power.
     
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