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Capturing lightning

  1. Nov 7, 2006 #1

    taylaron

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    hey all,
    has it ever been possible or even attempted to capture the vast ammount of electricty there is in lightning?:rofl:
    all that ground wire is in almost every non-stationairy device leads into the ground. (kind of waisting electricity in my opinion)
    why cant we use all this energy going into the ground. espcially lightning because it is the process of a massive static discharge.
    i asked around and i got the reply "nothing can hold that ammount of energy for that long of a time. nothing could stand the temperature of lightning."
    and i suppose they're right. lightning is somewhat "hotter" than the sun.
    but why can we use water (a conductor) as the conductor.
    i have no clue what on earth could be charged by a lightning strike in about 1/1000'th of a seccond. charging at that speed i suppose would be very diffucult:grumpy:


    im simply asking why we're not harnessing all of natures energy. or potential energy in some cases. lightning has a lot of electric potential to us i think.:surprised
     
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  3. Nov 7, 2006 #2

    chroot

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    From an electrical engineering perspective, the hardest part about capturing the energy in a lightning strike is indeed its very swiftness. You're probably aware that batteries must be charged very slowly; all batteries have some unavoidable series resistance, and trying to pump tens of thousands of amperes of current through even a tiny resistance will still generate an enormous amount of heat -- enough to essentially fry the battery.

    If you really wanted to capture the energy in lightning, you wouldn't want wait until a bolt occurs -- that's just too much current in too short a period of time. Instead, you could conceivably build a tall vertical structure which is capable of continually neutralizing static charge between cloud and ground. This structure could move the same amount of charge as in a lightning bolt, but spread over a much longer period of time. A current of tens of hundreds of amperes is quite easy to deal with, and could be used to charge ultracapacitors, spin up flywheels, etc.

    Building such a tower would be an engineering feat, however, and it's not clear to me (I'd need to do some calculations) that the economic value of the energy that could reasonably be captured this way would justify the cost of the structures.

    - Warren
     
  4. Nov 7, 2006 #3

    taylaron

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    thats very interesting. i actually thought of that but i failed to mension it in my post. i would greatly appreciate it if you did those calculations to see if it would be "worth it"
    this lightning rod would have to be thousands of feet hight though. facinating idea though.
     
  5. Nov 8, 2006 #4

    chroot

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    Wikipedia says:

    I am no expert on lightning, so I don't know the veracity of this information. If it's correct, it means a single lightning bolt has very little energy indeed; it just looks spectacular because of its nearly instantaneous release.

    - Warren
     
  6. Nov 8, 2006 #5

    es1

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    Hmm...
    i=Dq/Dt -> Dt=Dq/i=5C/30kA=160uS
    Bigger currents just make Dt smaller.
    The best games are ~100fps (right?) so ~10mS is fast for trained human eyes. Back the envelope sure, but ~200uS seems too fast to me.

    Anyway, I agree with the conclusion, not much useful energy in lighting, but something seems weird in those wikipedia numbers.

    University of Florida has it at 5 light blubs for month. They also address the original question in detail.
    http://plaza.ufl.edu/rakov/FAQ.html
     
  7. Nov 8, 2006 #6

    es1

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    Whoa it's surprisingly difficult to determine how long a strike lasts on average through cursory searches. My google searches found answers varying from 1uS to 100mS.

    The guys who operate cameras seem to operate on the order of 10s of mS.

    http://lightningtrigger.com/CameraCompatibility6/CameraCompatibility6.htm

    But this was the most interesting.

    http://www.srh.weather.gov/mlb/ltgcenter/whatis.html

    It seems the forward path of lightning is a series of discrete jumps each lasting about 1uS over ~50m with the time to traverse the total path taking 10s of mS.

    Also, according to the above link, the return does takes less than 100uS and has 5C of charge which does jive with the wikipedia article.

    A stroke is one up down path of charge and a flash can (and often does) contain many strokes.

    Amazing.
     
    Last edited: Nov 8, 2006
  8. Nov 8, 2006 #7

    Danger

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    There's another possible approach that I just thought of. The practicality is pretty 'iffy', and it would entirely depend upon being able to direct where the lightning strikes.
    I'm wondering if, given the intense temperature of a lightning bolt, it could be used to heat a large water reservoir. That could imply flash-boiling in order to run a turbine, although the explosion hazard seems rather high and steam regulation to get a smooth flow could be difficult. The hot water itself, however, could be used for other purposes. This would obviously have to be utilized in an area with a very high incidence of thunderstorms in order to be even marginally practical.
    Any comments from resident experts about this?
     
  9. Nov 8, 2006 #8

    taylaron

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    in my opinion, you would still have to use the long rod sticking up into the atmosphere to "direct" it to the ground where the water is underneith it. but using the static electricty that causes lightning. it would make much more sence to harness electricty for power, to me , would make much more sence. right?

    good idea using water. one downside is that water is a conductor and if the water is in contact with a fraction of any piece of conductive material that leads into the ground. your hosed. in otherwords, it cant be grounded. right?
     
  10. Nov 8, 2006 #9

    taylaron

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    i know lightning bolts; when they strike the sand, it melts the small section of sand into a "ball" or something like that. directing the current to some material in order to melt or use its conductivity in order to change some substance into another form.

    this experiment would have to be taken place in a "bad-weather" location. eg.. a coastline because of all the evaporation by the clouds.
    sigh.....
     
  11. Nov 8, 2006 #10

    taylaron

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    when lightning strikes water does it turn to steam/boil?


    i guess we sould ask ourselves that question first....
     
  12. Nov 9, 2006 #11
    ...

    The only problem is in that energy storage device... I think that the temp. problem could be handled...
    One of the profs. said once that a study proved that a single capture of a lightning could save up energy equal to a big country's 100 year supply of fuel...

    lets try & capture one... anybody interested ??
     
  13. Nov 9, 2006 #12

    Danger

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    We could take over the Empire State Building. Doesn't that thing get hit something like a couple of hundred times a year? :biggrin:
     
  14. Nov 9, 2006 #13
    500 MJ is aproximately the explosive energy of 100 kg of TNT.
    Is that much or very little? I would't know to say.
    EDIT:I heard/read there are more than just one high current discharge in an individual lightning flash.Usually 3-5.Does that mean that total energy is 3-5 x higher than 500 MJ?
     
    Last edited: Nov 9, 2006
  15. Nov 9, 2006 #14
    Just a quick question, why dou you need a building? I would think that it would be way more cost effective to use a weather balloon on the end of a wire running into something like a Li ion bath. It would be like the mother of all batteries.
     
  16. Nov 9, 2006 #15

    taylaron

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    i think it would vaporize the Li ion "bath" because it wouldent be able to abosrb all the energy quick enough. it would overheat quickly and "boom!" just like real battories when you crank alot of voltage and current into them.. hee he..
    good suggestion though.
    i think using a building would be much easier than building just a baloon or building a giant vertical rod to capture this lightning because there would be a significant ammount of structure benith the wire that extends FAR above the sky scraper to support it. this would be benificial to the structure and to the cost. a building is a good support for this wire, but it is still a problem with "stray" strands of lightning going away from the "guide wire" after it gets near the ground in order to be obsorbed in this massive Li ion pool.

    the problem with a baloon ( think.. correct me if im worong) is it would mealt the canavs that envelops the hydrogen. plus this thing would have to be HUGE!!! to carry a significant gague of wire from the earth to our atmosphere. if it was a really small gague, than i think it would "guide" the lightning but all that electricity is being forced into that little space and would "fry" it almost instentaniously.
    all that crap about ben frankeln catching a lightning bolt with a key on a string is crap if you had that on your mind.
    i think temperature is our problem for baloons. for this reason, baloons would be (if not at all) 1 time use. because they would fall back to the earth (if not vaporized first)
    but you always hear about planes being struck by lightning and nothing damaged (but the electronics) because the lightning was simply "passing through" the plane. the plane wasent grounded to the ground. the same principle might work here. im not sure.
    good idea though. keep up the thinking.

    correct me if im wrong, but there would have to be some sort of "battorie" part to this Li ion "bath" the rods used for the + and - would have to be HUGE if not impossible to make/use. the lightning would also fry these on its way.
    please feel free to correct me on anything i say. im just basing this off my current knowledge

    forgive my spelling as well..........ugh....
     
    Last edited: Nov 9, 2006
  17. Nov 9, 2006 #16

    Danger

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    I can forgive your spelling, but not that pun. :yuck:
     
  18. Nov 9, 2006 #17
    Capturing lightning is easy...


    [​IMG]
     
    Last edited: Nov 9, 2006
  19. Nov 10, 2006 #18
    I had not intended for the balloon to actually be struck by the lightning, the balloon would be above the weather. There are balloons that have been used to get into the jet-stream at 35,000 ft. and circumnavigate the globe, I'm sure that would work to keep the balloon above the lightning clouds. Also I was not intending for lightning to strike the wire at all, but going with chroot's suggestion of collecting energy all the time. The only real problem is the weight of conductor.
     
  20. Nov 19, 2006 #19
    has anyone seen those researchers who fire model rockets up into storm clouds, trailing a fine wire, they measure the electrostatic field levels, and when the get high enough, they fire the model rocket, ALOT of the time, very soon after they get a stike on the launch platform, where the wire is connect to ground, they use this rig to measure the lightnings parameters.

    i remeber years ago, when i was working in radio comms, working at a transmitter station with 3 600 foot towers, when a electrical storm was approaching, we would drive out to the base of the towers, and with any lighting close by, the lightning arresters "spark gaps" would have a continuous arc across it, we'll before the storm was overhead and before the towers had receive any direct hits.

    (we were out of there by them, its a scary sight very loud and violent).

    i dont know how much power is in lightning, but i once saw a strike, when i was driving in a very bad storm, i heard the explosion and the light at the same instant (it was really close).
    this lightniting strike, actually ignited the tree, and split in or snaped off a branch. the tree burst into flames in the poring rail. quite a sight to see, but scary :)
     
  21. Nov 19, 2006 #20
    http://www.lightning.ece.ufl.edu/
     
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