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I Name the forces involved?

  1. Jan 11, 2018 at 10:38 AM #1
    Hi all, this is my first post. It seems around eight years ago I was on a similar brain-wave-length as Laurence Kemball-Cook, with his idea to create a power generating flooring surface... only he had the know-how to bring the idea to market, so credit where credit is due. (though now I wonder couldn't the insides of shoes simply have this and save on the manufacture of area that may never get stepped on? Or maybe that's been done already too)

    Anyway, on to the next idea I don't have the know how to bring to market, but I'm curious to learn about the feasibility of the idea in terms of forces involved... it's based on an idea I had watching the footage of ice going down in low-tide and being lifted in high-tide in this clip from BBC Human Planet: (around the 1:10 minute mark is where the ice goes down). What immense power is demonstrated there, in lifting such heavy ice!

    I can't help but wonder if the two ideas for energy conversion were to be married:
    That of buoyancy and that of weight pressing down.... could the up-down motion, buoyancy and weight of an object lifted and let down by tides, be part of an equation that allows us to convert that energy into something we can use? I'm NOT talking about a PMM or Free Energy because nothing is free and nothing is perpetual I understand very well.

    I've seen tidal power plant concepts but nothing that utilizes an up-down motion, with a buoyant but heavy object when it's being pulled up, or the weight of the same object when it's released down, to generate electricity. Am I way out there with such a marrying of ideas?

    What forces are involved (that aren't immediately apparent i.e. Gravity & buoyancy... or I haven't already mentioned) and what mechanisms/engineering principles would I need to get schooled in, in order to learn more about the principles involved?

    And it also makes me think of the up down motions of elevators... I wonder if there are any elevators that are geared towards self-charging when it's the case that the elevator is going down? Like a hybrid car that is half electric and half self-charging?

    Thanks in advance for any kind and patient input you could give or directions you could point me in.
     
    Last edited: Jan 11, 2018 at 11:04 AM
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  3. Jan 11, 2018 at 10:48 AM #2

    BvU

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    Hello Beth, :welcome:
    Seems to me you've seen them but not understood them ? If something works on a back and forth motion it just might be that such motion is in fact caused by an up/down force...
     
  4. Jan 11, 2018 at 10:49 AM #3

    BvU

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    Ever seen counterweights at the side of elevator shafts ?
     
  5. Jan 11, 2018 at 11:19 AM #4

    Lord Jestocost

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    Your idea reminds me, for example, of the "NEMOS Wave Energy Converter" (https://www.nemos.org/waveenergy/).
     
  6. Jan 11, 2018 at 11:31 AM #5
    I'm aware of the role the counterweight plays, to some degree, but would the up and down motion being carried out through everyone's daily comings and goings not be something that an ulterior tailor made energy conversion/power generating system could "plug" into?
     
  7. Jan 11, 2018 at 11:46 AM #6
    Thanks for mentioning that.... im looking into it
     
  8. Jan 11, 2018 at 12:12 PM #7

    jbriggs444

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    Suppose that a person comes into the building on the ground floor in the morning, rides the elevators for most of the day and exits from the ground floor in the evening. How much energy can be harvested from the difference between that person's potential energy upon arrival and upon exit?
     
  9. Jan 11, 2018 at 12:44 PM #8

    sophiecentaur

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    I am amazed that the message "you don't get anything for nothing" is not instilled into kids of all ages at school and at home. It works in all of life and not just Engineering.
    If people all climbed the stairs and then rode down in the elevator there could be some mileage in the idea. (Tongue in cheek)
     
  10. Jan 11, 2018 at 1:00 PM #9
    Yet elevators ride empty all the time. I'm talking about viewing an up and down motion, that's happening anyway for other reasons, as a sort of engine that we can plug into. Same as the tide and anything that the water happens to hold up or let down, as an engine to plug a power generator into.
     
  11. Jan 11, 2018 at 1:01 PM #10
    How do we factor in the empty elevator that travels to pick people up when they call for it? It's moving up and down through the day and it's the motion of it moving up and down I'm interested in figuring out how to "plug" into.
     
  12. Jan 11, 2018 at 1:03 PM #11

    jbriggs444

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    What is the difference in potential energy between an empty elevator on the ground floor first thing in the morning and an empty elevator on the ground floor at evenings end?

    You can't pull energy out of the elevator that the elevator's motors did not put in to start with. It's a losing game.
     
  13. Jan 11, 2018 at 1:08 PM #12
    Elevators are run on electricity and counterweights so yeah it would only be getting out a portion of what was put it. But the concept of how to do that with an elevator, would be the concept or principle that I would want to apply to an object being lifted and let down by rising and lowering tide waters.
     
  14. Jan 11, 2018 at 1:28 PM #13
    We've all also seen boats left sitting on a dry coastal sea floor, when the tide is out. So what is the potential energy of such a large item when it has been lifted up to 15 meters?
     
  15. Jan 11, 2018 at 1:30 PM #14

    jbriggs444

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    http://lmgtfy.com/?q=potential+energy+formula
     
  16. Jan 11, 2018 at 1:32 PM #15
    Thank you for pointing me to that. Let's suppose the floating object is usually 200 kg. And let's say the height at high tide is 15 meters... but now I'm having a hard time figuring it's SI, or acceleration due to gravity, because it's not free falling... not like in the illustration that shows up in the following search: acceleration due to gravity
     
    Last edited: Jan 11, 2018 at 1:49 PM
  17. Jan 11, 2018 at 1:53 PM #16
    It's buoyant weight is different I'm sure but as it's let down imagine if there were mechanisms offering resistance, designed to generate electricity as its lowered? Like the electricity generating flooring surface that Lawrence Kemball Cook came up with?
    Or if the object's height could be maintained til the tide has gone out, and then let the object free fall? Would that work better?
     
    Last edited: Jan 11, 2018 at 2:02 PM
  18. Jan 11, 2018 at 2:10 PM #17
    I did acknowledge nothing is free. I think what I'm trying to say is that tide waters lifting heavy things up for us for 'free', is the same idea as people climbing the stairs but taking a power-generating-elevator down, if only we could plug into the potential energy of those raised heavy objects, and then maybe even also plug into their natural desire to stay buoyant, as the waters raise it again....
     
  19. Jan 11, 2018 at 2:11 PM #18

    jbriggs444

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    If you offer resistance as the object is lowered, you can harvest energy. How much energy you can harvest depends on how much resistance you can offer and how far the boat will move against that resistance.

    What is the maximum resistance you can offer?
    If you offer this much resistance, what effect does it have on the distance the boat can be allowed to fall?
     
  20. Jan 11, 2018 at 2:19 PM #19
    Those are good questions. I don't know anything about offering resistance but what if the whole thing was designed abit like an elevator with a counterweight on a pulley? (The counterweight would need a water-free shaft maybe so that the water doesn't influence the freedom of its up and down movement?)
     
  21. Jan 11, 2018 at 2:27 PM #20

    jbriggs444

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    A counterweight is going to do no good at all. The point of a counterweight is to allow a mechanism to operate with minimum external force applied. For instance, in a properly balanced elevator, a two ton carriage balanced by a two ton counterweight can be moved up and down with (ideally) no effort at all.

    If you are attempting to generate power, you want to maximize the external force. You want to harvest energy on the upstroke (if freeboard permits). You want to harvest energy on the downstroke. A counterweight that reduces the force presented to the generator is counter-productive. A counterweight that makes the force higher in one direction than in the other would mean that you have to over-engineer your generator to deal with the increased maximum force.

    One simple-minded approach would be to hook the boat up to some chains or cables on a winch and let the winch run a generator as the cable plays out. Not very efficient though. It would make far more sense to use turbines and a huge reservoir instead of cables and a small boat.
     
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