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Potential Energy

Discussion in 'Misc Electronics' started by Jasen Betts, Jun 5, 2009.

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  1. Jasen Betts

    Jasen Betts Guest

    an escalator driving a generator ?
    piezo-electric stair treads?
     
  2. karela

    karela Guest

    When we go upstairs we spend a lot of energy that gets stored as potential
    energy. When we go downstairs we waste all the potential energy. Couldn't
    anyone invent a good way of coming down so the potential energy could be
    converted to other forms of energy that could be converted to electricity
    when needed??
     
  3. Doc O'Leary

    Doc O'Leary Guest

    How much are you willing to spend on a contraption to power a 100W light
    bulb for less than 1 minute?

    <http://www23.wolframalpha.com/input/?i=potential+energy+of+100kg+at+5m>
    <http://www23.wolframalpha.com/input/?i=100W+*+1+minute>
     
  4. daestrom

    daestrom Guest

    Well in *theory*, yes you certainly could. Something as simple as a bucket
    and rope tied to a pulley turning a shaft. When you want to go downstairs
    you just climb into the bucket and let it lower you through a hole in the
    floor. Of course there will be *some* losses.

    But lets look at just how much energy we're talking about. Raising a 200
    lbm man up 10 feet in normal gravity would put 2000 ft-lbf of energy into
    the man. If you could recover *all* of that, that is a mere 0.75 watt-hours
    (not kW-hr, just watt-hour). So if he goes up the stairs 20 times a day for
    a year, he'll have used 20*365*.75 / 1000 = 5.5 kW-hr of energy. Recover
    *all* of that perfectly and you have about $1 worth of electricity for the
    year.

    Going up stairs 20 times a day is great exercise, but it won't generate much
    energy for you.

    daestrom
     
  5. Charles

    Charles Guest

    Jump onto a platform with pulleys and counter-weights. The resulting
    rotational energy can be stored in a battery via a rotating generator. The
    overall efficiency will be less than 15%. The time to pay of your
    investment (for all of the pulleys, and gears, and a safe platform, and the
    rotating generator with a storage battery) will be infinity years.
     
  6. Don Stauffer

    Don Stauffer Guest

    I worked on a program for defense dept. The idea was to keep soldier's
    battery packs charged (a modern infantryman carries a lot of battery
    weight). One idea we looked at incorporated piezo-electric strips in
    the sole of shoes. We didn't win the contract.

    Modern magnetic design software is extremely good, and is allowing very
    efficient small generators to be designed these days. Notice the
    profusion of wind-up flashlights. If wearable computers ever make it to
    mass production something like that will likely appear to keep the
    batteries for those computers charged- or at least extend the life.
     
  7. RogerGibb

    RogerGibb Guest

    Be sure to capture the energy from rain falling too. Especially
    when it runs down the spout from your eavestrough.
     
  8. In alt.energy.homepower RogerGibb twisted the electrons to say:
    One of the micro-hydro places near me has it's gutters set to dump the
    water into the mill-race it's on. Okay, I'm never going to claim it (or
    the micro hydro plant further down said mill-race) generates significant
    amounts of power due to this but I do think it's an elegant simple piece
    of design.
     
  9. daestrom

    daestrom Guest

    So let's see, if you have a 45x28 roof, 20 ft up in the air and you get 4
    inches a rain (quite a bit in most areas), and you manage 100% energy
    recovery, that rainstorm would generate about 522480 ft-lbf of energy.

    A whopping 197 watt-hours.

    In my case, I wouldn't bother.

    daestrom
     
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