A power plant that uses more power than it generates

  1. There were no pictures available , i wonder why..??
    try googleing Yards Creek Power Plant
    what a waste of power..!!!
     
  2. jcsd
  3. Hurkyl

    Hurkyl 16,089
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    Well, the alternatives are:

    (1) Have brownouts during the day, because power plants aren't producing enough power to meet demand.

    (2) Waste gobs of power at night, because power plants are producing far more than is consumed.
     
  4. Niagra falls does the same thing at night time. As it pumps it up hill, it turns the generators in reverse to make power. During the day, it falls back down, and turns the generators once more to meet peak demands. Electric Generators can only produce so much power druing the day, and if the demands are not high, it only makes sense to use this power that would other wise be wasted to give the water a higher potential energy.
     
  5. brewnog

    brewnog 2,791
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    There's a similar system in Llanberis in Wales, - the "Electric Mountain" at Dinorwig. At the time (1985?), it was the largest civil engineering project ever accomplished in the UK, which isn't surprising if you've seen the inside of the generator hall; it's massive, and is actually inside a mountain. You can go on a tour of the facility, it's fantastic.
     
  6. Clausius2

    Clausius2 1,479
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    Well, I am not an expert in this stuff, but I am going to give my opinion. Here there are such power plants also. I think I was taught those power plants have two missions:

    i) meeting peak demands.

    ii) Pumping Reactive Energy into the electrical system. Usually such turbines are coupled to a synchronous (did I write it right??) motor-generator. These motors are capable of generating Reactive Energy when they works with an appropriate intensity in the rotor. Electrical companies must balance the consumption of Reactive Energy, because this energy is employed by motor consumers to magnetize the machines during the day. Also, insuflating Reactive Energy will stabilize and increase the voltage in some disfavoured electrical node. You know also that an excessive consumption of Reactive Energy is penalized by electrical companies, because it is a more expensive type of energy. So it seems these power plants give more profits to electrical companies than we might think, by the way they wouldn't exist if this last statement is not completely true.

    Have I translated rightly the term "Reactive Energy"? I am not sure I did it. I don't know if this power is called so in english.

    Anyway, if some electrical engineer is not agree with me, feel free to criticise me (but not too hardly! :smile: )
     
  7. Ivan Seeking

    Ivan Seeking 12,535
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    Clausius2, are you talking about a sliding scale for power rates based on the power factor for each customer?

    As for the original post, does anyone know approx. how efficient these systems may be? By a seat of the pants calculation, I land around the 5% range [.9 x .2 x .3 x .9] as a best case, which is about the same efficiency as converting the excess energy into hydrogen, and offsetting peak demands by using the H2 fuel. This has a been one focus for the H2 folks and it looks like they could already be competitive.
     
  8. We call our electrical supply base load, load following, and peak load. Reactive energy sounds to me like load following.
     
  9. H2 vs pumped storage

    Where did you get those figures? Willi wrote it takes 3 kilowatts-hours of pumping uphill to generate 2 kilowatt-hours of electricity when generating. That would be a storage efficiency of 67%.



    It is not likely H2 will ever be as efficient as pumped storage. The problem with pumped storage is that there are limitation on places to pump to. We could do like the Soviets did and blast out reservoirs with hydrogen bombs, or we can settle for less-efficient storage technologies such as H2.
     
  10. Danger

    Danger 9,878
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    I'm going to pretty much ignore all of the posts and comment only upon the title of the thread. All electrical generation facilities consume more power than they produce. Even a fusion plant, should an operable one be developed, would be in that category. It's only a partial conversion of one state of energy to another, with attendant losses. When you consider how much energy went into creating deuterium and tritium in the first place, it's obvious that there is really no 'break even' point. It's almost like petrochemicals, where one thinks that oil is a free resource once you get it out of the ground. That doesn't factor in the amount of solar energy and planetary gravity/heat that went into sustaining the lives of the dinosaurs and plants and then squishing them into oil.
     
  11. Ivan Seeking

    Ivan Seeking 12,535
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    Sorry, I was on Tsu's computer and the screen resolution threw me. I never saw that...but that seems impossibly high as a final number. I was assuming a 90% motor/generator efficiency, two ways, and then 20% for pumping, and 30% for turbine efficiency. Of course it depends on the turbines, but I think the best run around 66%, and this only accounts for one of four stages of the process.

    I don't follow. I cited the current, known, 5% well to wheels efficiency for H2 internal combustion. Its already being done.
     
    Last edited: Jul 18, 2005
  12. China's pumped-storage efficiency claims

    China is claiming the same thing.
    power-technology.com/projects/tianhuangping

    --
    East China Electric Power's Tianhuangping pumped storage hydroelectric project is the biggest of its type in Asia. It [...] has a total installed capacity of 1,800MW.

    [...]

    The plant design achieved an overall cycle efficiency of 70%.
    --


    If we assume a 91.5% efficiency for the pump motor, a 91.5% efficiency for the pump, a 91.5% efficiency for the turbine, and a 91.5% efficiency for the generator, that would be an overall efficiency of 70.0945700625%.

    Wikipedia's pumped-storage efficiency claims are even bolder than China's.
    en.wikipedia.org/wiki/Pumped-storage_hydroelectricity

    --
    Between 70% and 85% of the electrical energy used to pump the water into the elevated reservoir can be regained in this process.
    --
     
    Last edited: Jul 18, 2005
  13. the point of my post was to illuminate you to the fact that we are wasting huge amounts of power , by pumping it up hill , just to let it flow back down , when demand is higher..
    the only reason this is feasable is because power is cheaper at night ( for large users) ...
    So they buy cheap power at night , and sell it back , at a hgher rate..
    you would think that this would put a higher load on the overall system..
     
  14. The time value of energy in human enterprise

    In human enterprise, energy has time value. If you can parlay time-energy of a given value into time-energy of a greater value, your time-energy investment is not wasted.
     
  15. If someone was to build a huge capacitor network to store the power at night..
    and put it back during peak demand..
    that would have much more efficiency , and make more sence than all the losses associated with pumping water up hill...
     
  16. You mean it would be cheaper?
     
  17. It would be like charging a battery, as opposed to
    charging a battery while it is pumping water up hill ..
    there is allways losses , even when charging a battery..
    but not as much , as the topic of this discussion..
     
  18. If the topic of this discussion is the saving of power no matter the price, wouldn't it be topical to mention that even more power could be saved by reducing base-load power production at night?
     
  19. russ_watters

    Staff: Mentor

    It is not a waste in most cases. It is recovering energy that would normally be wasted if it weren't done. Someone else already explained this to you: you cannot just shut off a nuclear power plant at night so if you don't do something with that power, then it is wasted.
    Or you could use actual batteries. That's what regenerative breaking in hybrid cars does. The problem is that batteries and capacitors, in the size necessary for storage of grid power, would be extremely expensive.
     
  20. Russ , you wouldnt use batteries for regenerative braking..
    you would use something that is able to store power quicker than a battery..
     
  21. Willi, the Prius, the Insight, the Civic Hybrid, the Accord Hybrid, and the Lexus RX400h, among other vehicle models, all use lead-acid batteries in their regenerative braking systems. Eventually they might switch to ultracapacitors, though ultracapacitors have the problem of extremely low energy density relative to that of lead-acid batteries.
     
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