Capturing All The Turbine's Energy

Discussion in 'General Science & Technology' started by jmpet, Apr 24, 2011.

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  1. jmpet Valued Senior Member

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    A wind turbine that lifts things. Energy is obtained by the falling of those things.

    A wind turbine and a 100,000 gallon reservoir in a tank of water 20 feet off the ground.

    As the turbine spins, it carries a gallon of water 20 feet up and drops it into the reservoir.

    As the water flows out of the reservoir, it spins a turbine and creates energy.

    Since the turbine does not always turn, the reservoir is the captured potential energy of the turbine.

    The turbine refills the reservoir and the reservoir consistently produces energy.
     
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  3. fedr808 1100101 Valued Senior Member

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    Other then this being impractical, what's the point

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    I can tell you that if I were to hook a wind turbine to an electric generator it would be a lot more efficient.
     
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  5. Dywyddyr Penguinaciously duckalicious. Valued Senior Member

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    You'd get more energy by doing a direct-to-electricity because of losses in pumping.
     
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  7. Odin'Izm Procrastinator Registered Senior Member

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    So by your approach you are loosing energy in two turbines due to inefficiency? The hydraulic compression generators used now are far more efficient than this, require less maintenance, and can be used offshore where wind energy density is greater.

    Also: wind turbines need to adjust their ratios for changes in wind speed to supplement the grid, if you are using water this becomes very inefficient at low wind speeds.

    And again: Since the turbine is connected to the national grid, its the grid that acts as a reservoir, there is no need to store water.
     
    Last edited: Apr 24, 2011
  8. fedr808 1100101 Valued Senior Member

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    And evaporation. And all the moving parts. And the fact that the generator would probably empty at least 15% of the resovoir before the turbine had the chance to refill 2% of it.
     
  9. jmpet Valued Senior Member

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    I need you guys to think simpler. Turbines generate electricity by spinning the turbine blades. But the wind does not always blow and other times blows too hard, so they can't be reliable as an energy source 24 hours a day.

    But if you could capture all the energy a turbine generates, you could have reliable energy.

    But you can't capture that excess energy because batteries suck. So turbine arrays end up selling surplus energy at a loss... which makes them unprofitable ventures.

    But if all the turbines did was create potential energy instead of electricity, you could harness it all.

    The simplest way to do that is to have the turbine "lift heavy stuff up"- create potential energy. And store it somewhere higher.

    Re: water and evaporation. My original idea was to use ball bearings- that's why I said "lift STUFF up".

    Don't you all see how the simple mechanics of it works?
     
  10. Odin'Izm Procrastinator Registered Senior Member

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    Mate read my post! the grid acts as a reservoir, it supplements the wind turbine when it is spinning too slow, when the wind is too strong they feather the blades.

    The unpredictability of the turbines is why they are investing in super grids where wind in one are supplements a lack of wind in another, there is also something called meso-scale modelling where you can predict the wind yield to match demand...

    You capture all of it's energy already (now, present day) using existing hydraulic generators you don't need to store it in a tank.

    The mechanics of it don't work, because the work doesn't work out...

    BTW Turbine arrays are highly profitable ventures, most of Scotland's economy rests on them, billions are flying around to a point that isn't even funny.
     
    Last edited: Apr 24, 2011
  11. jmpet Valued Senior Member

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    So it is already reality that we can capture all the energy turbines produce?
     
  12. Odin'Izm Procrastinator Registered Senior Member

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    No you still have losses in the generator ranging anywhere from 15-5% depending on conditions, which is slowly being redeveloped. If you look at the website for 'Artemis' http://www.artemisip.com/

    They have some diagrams of their now generator project with motorola, it proposes a similar principle to what you suggest but the fluid is more of a cushion to adjust for minute irregularities in speed.

    More losses are encountered because the blades don't extract all the energy from the wind due to frictional and flow losses (see 'actuator theory')

    Once the energy is harvested it feeds to the grid which acts as a bank, if there is under production it is currently supplemented by using other power sources, but the general idea is to make a large grid connecting all the turbines on continental or national scales, and a lack of wind in one will be offset by another where it is higher (as wind tends to vary in cycles sinusoidally)
     
  13. Odin'Izm Procrastinator Registered Senior Member

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    Jmpet, just found a variation of the idea you proposed but used in tidal/wave energy:http://www.mindfully.org/Energy/2004/Wave-Power-Trinidad4aug04.htm

    Apparently storing water is also done with wind turbines as pumps, much like in holland, but in areas where there is no grid to store energy and availability of a large reserve. It allows the selling of electricity at times when its at it's peak in price. However for traditional use the grid is more reliable.
     
    Last edited: Apr 24, 2011
  14. jmpet Valued Senior Member

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    My goal- and thanks for all the info and I am with you- is to apply it practically. Amazing to think up something that already exists- imagine if it didn't.

    I want turbines to replace oil and coal. And it's possible energy-wise if you can harness all the energy of a mechanism, because then they become units upon which you build a superstructure... it all boils down to putting enough of them up.
     
  15. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    I don't think "flow loses" give the average reader the correct idea, but as you mention actuator theory, you probably know that wind machines can not capture all the energy in the wind for the simple reason that the air must leave the down wind side of the machine with some wind speed (and more than 40% of the upstream energy). I.e. to get all the KE in the wind you would need to bring it to rest and then there would be no air flowing thru the machine and zero efficiency. The theoretical best (59% efficiency) is when the down wind air is moving at 1/3 the up wind air speed:

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    But in practice getting 45% of the kinetic energy from the wind is a very good result.

    Blade friction has been ignored in this analysis, but is not very important, however a one bladed wind machine is the most efficient. They (and even two blades) are are impractical because when blade(s) are vertical there is essentially zero moment of inertia against sideways gust. Thus even though slightly more than three times the blade friction with three blades, (each blade runs in more turbulence from blade 120 degrees leading it) proper design for efficiency almost always has three blades. (The old farm water pump has 20 or so blades for torque in low wind speeds, but terrible efficiency.)

    BTW Brazil has the perfect system for integration of wind energy into the grid because about 80% of Brazil's electric power is hydro-electric. Thus, when wind machines are making a lot of power, you simply release less water from the dams. When they are not, there is more water going thru the dam's turbines.
     
    Last edited by a moderator: Apr 25, 2011
  16. jmpet Valued Senior Member

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    I want a machine that costs X to build and produces Y in profit reliably, 24/7/365.
     
  17. Odin'Izm Procrastinator Registered Senior Member

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    I still think nuclear and hydroelectric energy is the way forward, while wind is a good alternative for now.

    Didn't want to move too far from the abstract... But thank you, its hard to completely drain all the kinetic energy from the flow, and in most cases doing it in stages as it moves through the array is more efficient.
     
    Last edited: Apr 25, 2011
  18. adoucette Caca Occurs Valued Senior Member

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    Somewhat of an exaggeration I'd say:

    http://www.scotland.gov.uk/Topics/Statistics/Browse/Business/SABS/KeyFacts

    Turbines don't even make the list....

    As to energy sources for Electricity, Nuclear is by far Scotland's largest source of Electricity, providing 33% in 2009.
    Coal provided 23%
    Oil and Gas provided 21%
    Hydro provided 12%
    All other (mostly wind) provided 11%.

    Arthur
     
    Last edited: Apr 26, 2011
  19. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    Yes, if second wind machine follows behind the first, one can argue that it collects some more energy, but that would not be economic / efficient us of it compared to putting in the original higher velocity flow.

    Even when the down stream to up stream ratio is the optimum 1/3, part of the cylinder of wind with same diameter as the wind machine's blade sweep area circle, that is far ahead of the wind machine will not pass thru the machine but spill round it. This loss of potential energy is not considered in the analysis for efficiency in the graph I presented. That graph is computing the efficiency of energy capture of the wind that does move thru the machine, not of the energy in the equal diameter cylinder far a head of the machine. The max efficiency in collecting the energy of that cylinder is only about 45%, not the 59% shown in the graph, which ignores the energy that just spills around the machine.

    For example, when the wind is almost stagnated so that only a tiny cylinder, say of radius d = 1% of the far up stream cylinder diameter, D, is the "on axis" air stream, passing thru the machine, it is used with the 50% efficiency shown in the graph for near zero wind exit speed, but as most would define efficiency (capture of the KE in the wind cylinder far head of the wind machine) the efficiency is less than 0.0001 as only that fraction of the far up steam air is even passing thru the machine - most is just spilling around it.

    Which brings me to my point:

    Two rows lines of staggard wind wind machines can produce more energy than all the machines in one row. Symbolically with 19 machines:

    X X X X X X X X X X
    ..X X X X X X X X X Where the wind is coming from the top (side with 10 machines) The two .. are there only because Sciforum's computer will not let me start the second line with a blank.

    Two rows can be slightly better than one: X X X X X X X X X X X X X X X X X X X or all 19 machines in one row as the air spilling around the front row can, if spaced correctly, increase the wind speed incident upon the 2nd row. This only works when the direction of the wind is likely to be transverse to the rows of machines, like "on shore" then "off shore" breezes of a coast line.
     
    Last edited by a moderator: Apr 25, 2011
  20. Odin'Izm Procrastinator Registered Senior Member

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    Can you yourself see a problem in the logic of quoting a 3 year old survey for an industry which is only just becoming mainstream?

    For a start, the UK has a large knowledge based industry, a lot of which are renewable energy and wind consultancies to which I was referring. The size of contracts for new developments is booming, and phase 3 of UK's offshore program is worth billions, as are many private investments made by foreign banks and turbine manufacturers.

    To address your other point

    The Scottish Government has a target of generating 31% of Scotland's electricity from renewable energy by the end of 2011, and reaching 80% by 2020. The amount of investment is huge, and consequently the industry is getting a large influx of both foreign and domestic cash.

    http://www.scotland.gov.uk/News/Releases/2010/09/23134359

    What you also don't understand, is an industry like wind can't just be judged by the energy yield, it also creates jobs and investment in indirect areas, such as the energy grid, offshore technology, new drydocks to handle the new ships...etc. All this brings a huge influx of cash.
     
    Last edited: Apr 25, 2011
  21. fedr808 1100101 Valued Senior Member

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    A much simpler solution is just create a bank of capaciters, allocate say, 25% of the output of the generator to said capaciters, and then release them gradually as the turbine slows down.


    I get your idea, its just that it won't work. The best case scenario is at the end of the day your idea generated just about as much electricity as the traditional generator. The only difference is that your turbine puts out less energy but does it over a potentially greater amount of time.

    What happens if its a very windy day and your tank is overflowing? Your losing a hell of a lot more energy then you think you could save.
     
  22. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    You need to do some economic analysis. I.e. calculate the cost of storing X joules in a capacitor. If you do, you will see this is about the most expensive storage system one can imagine.

    I am just guessing to make a point, but winding up rubber bands to store energy may be more more economical than capacitor storage and that is obviously silly.
     
  23. Odin'Izm Procrastinator Registered Senior Member

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    Hydroelectric is a good plan.
     
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