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Power storage

Discussion in 'Renewable Energy' started by camerart, Aug 18, 2014.

  1. camerart

    camerart Active Member

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    Hi,

    I was wondering about the problem of power storage. With plenty of power in hot climates and of shore, I was wondering about liquefying or separating air into Oxygen and Hydrogen. This could then be stored and moved in vacuum tankers or containers, to where it is needed.

    Is there any merit in this?

    Camerart.
     
  2. BeerBelly

    BeerBelly Member

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    Separating water, I have seen done before. It was used to operate a modified gas stove and generator.
    The gas is produced and stored in a large tank displacing water. This way power wasn't wasted pressurizing the gas.
     
  3. camerart

    camerart Active Member

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    This low pressure needs a large volume for storage, so not practical for what I mean. You are talking about separating water, as in charging a battery, which also produces Oxygen and Hydrogen this is another possibility. This then needs to be compressed and chilled until it liquefies. With air this is also compressed and chilled until it separates into both gases.

    I'm suggesting using more energy, because there's plenty there, to produce liquids, that take 100s of times less room, and can be transported in vacuum containers, in a similar way to oil.

    I don't know if this is all viable, perhaps someone has the answer.
     
  4. dave

    Dave New Member

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  5. JimB

    JimB Super Moderator Most Helpful Member

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    Actually, a liquefied gas needs to be stored at pressure not in a vacuum.
    Consider a cylinder of Calor Gas, open the valve and gas comes out at several Bar pressure. If it was stored in a vacuum, air would enter the cylinder and gas would not come out.

    Similarly, oil is not transported in a vacuum.
    Unstabilised crude oil gives off gas and will generate quite a pressure in an enclosed vessel.
    Stabilised crude oil, where all the gas has been removed, is transported at atmospheric pressure.

    JimB
     
  6. tcmtech

    tcmtech Well-Known Member Most Helpful Member

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    I think what is meant by Vacuum vessel is the type that use a outer chamber that is held in high vacuum surrounding the inner holding chamber like many liquid oxygen or nitrogen tank systems use.

    Now that said the problem with transporting energy via a liquefied medium Vs direct conversion to electrical power for any reasonably long distance is easy to see where a simple high voltage multi phase power line is magnitudes of order more effective and efficient over the physical conversion transport and re conversion method. Just do the basic math and it pretty easy to see where power lines win.

    On top of that if large quantities of energy need to be stored then used in a efficient and high power level application simple old fashioned pumped water storage is impossible to beat on the scalability cost per unit of energy stored and overall low cost of operations plus its byproducts have multiple positive secondary values as well.

    That;s why you don't see trucks transporting what you are pondering on. A simple power line system and a remotely located pumped water power storage system will beat anything else on the cost, scalability and reliability basis.

    Now for a bit of basic math to compare.

    Her in the us a typical tanker truck is road rated for 80,000 pounds gross weight of which typically that works out in a tanker truck to being around 50,000 pounds of load and 30,000 pounds of truck.

    Given that take a single truck load of hydrogen at an energy density of roughly 51,000 BTU per pound a load of fuel has roughly 2,550,000,000 BTU or about 747 megawatt hours of electrical equivalent assuming a 100% efficient conversion.

    In reality the conversion is likely only going to be at best 20 - 25% efficient including transport costs and losses where as the power line systems will run at 80+ % efficiency even while covering several thousand miles ore more and can run 24 hours a day for decades for a very low cost per unit of energy transported during it's working lifetime all while achieving very high levels of safety connivance and reliability.
     
    Last edited: Aug 19, 2014
  7. JimB

    JimB Super Moderator Most Helpful Member

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    Doh! I never thought of that possibility.

    JimB
     
  8. camerart

    camerart Active Member

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    Hi Tcmtech,

    Correct: High vacuum container.

    Thanks for your calculations.

    Do you think that power lines would win over using the energy to liquefy air, then bring it ashore in vacuum pipelines, before converting it to electricity?

    Camerart.
     
  9. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Yes, it would win massively on ALL grounds - but particularly on safety.

    Essentially you're doing nothing except introducing an expensive, dangerous extra step in the supply chain.

    Where hydrogen 'might' become useful in the future is as a portable fuel, replacing petrol - but it's far more difficult to use than petrol, produces less power, and is MUCH more dangerous.
     
  10. camerart

    camerart Active Member

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    Just found this: http://www.technologyreview.com/new...ower-cars-and-store-energy-from-sun-and-wind/

    EDIT: Regarding the danger issue. I don't know how dangerous liquefying and using Hydrogen would be, but I think most power is dangerous in some way e,g, Diesel and lungs. Assuming that the above link shows some merit, then if what was liquefied was Hydrogen instead of Air, the power could be taken out of the liquid to gas conversion as in the air example, then the gas could be burned as well.

    Camerart.
     
    Last edited: Sep 7, 2014
  11. camerart

    camerart Active Member

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    Hi Karen,

    I have liquefied gas before, but that was Oxygen for pilots to breath, not for energy storage.

    It would be interesting to carry out a proper study, to find out if it is feasible. Especially scaled up.

    Thanks for your interest, C.
     

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