Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!


Forgot your password?
Power Science Technology

Pushing 800W of Wireless Power at 5 Meters 397

Joe Decker writes "The Nevada Lightning Laboratory has experimented with Nicola Tesla's methods of wireless power transmission to push 800 Watts over 5 meters, besting MITs mark of 60W over 2 meters last year. (May I dream of wireless laptop power? I hate power cords.)"
This discussion has been archived. No new comments can be posted.

Pushing 800W of Wireless Power at 5 Meters

Comments Filter:
  • by YrWrstNtmr ( 564987 ) on Wednesday December 10, 2008 @02:09PM (#26063159)
    800 Watts over 5 meters, ...
    (May I dream of wireless laptop power? I hate power cords.)

    I think I'll pass on that. Don't really want that sort of power aimed directly at the boys.
  • That's nothing (Score:5, Insightful)

    by internerdj ( 1319281 ) on Wednesday December 10, 2008 @02:09PM (#26063161)
    I've seen more watts over more distance all my life.
    http://www.nssl.noaa.gov/primer/lightning/ltg_damage.html [noaa.gov]
    You just don't want to stand between the source and the destination...
  • by VeNoM0619 ( 1058216 ) on Wednesday December 10, 2008 @02:10PM (#26063177)
    The link: "http://en.wikipedia.org/wiki/Nikola_Tesla"
    The summary Nicola Tesla's

    Who is right? The world may never know...
  • Maybe... (Score:5, Funny)

    by dmp123 ( 547038 ) on Wednesday December 10, 2008 @02:11PM (#26063183)

    May I dream of wireless laptop power? I hate power cords

    Depends - do you want kids in future?

    • Re:Maybe... (Score:5, Funny)

      by UnknowingFool ( 672806 ) on Wednesday December 10, 2008 @02:24PM (#26063391)
      This is /. The chances of him having kids would greatly increase if he did the following things in order:
      1. Get out of parent's basement once in a while.
      2. Talk to a girl.
      3. Get girl to go out on a date.
      4. ????
      5. Girl gives birth.
      6. Profit!!

      For those of you who are wondering about step 4, let the rest of us know when you figure it out cause I need to get out of this basement first before I figure it out.

  • Wow! (Score:4, Funny)

    by Anonymous Coward on Wednesday December 10, 2008 @02:11PM (#26063197)

    This is making my hair stand on end just thinking about this achievement.

    Or I am a little too close.

  • by elashish14 ( 1302231 ) <.profcalc4. .at. .gmail.com.> on Wednesday December 10, 2008 @02:12PM (#26063207)
    So what happens if you have cavity fillings or a metal plate in your body?
    • Cavity fillings might not matter, since they don't respond to magnetism hence you can get an MRI with them. Metal plates might be a bad thing though... and tattoos with a metal component to the ink might also have a bad effect.
      • Re: (Score:3, Informative)

        by mog007 ( 677810 )

        The Mythbusters tried the metallic ink in an MRI myth. There isn't enough metal in the ink to have any sort of effect at all. The person with the tattoo who had the MRI said that there was no pain or heat or anything.

        A metal plate might do something, though.

        • Oh man, I apparently missed an episode!

          I was going by this site [radiologyinfo.org], which said "Dyes used in tattoos may contain iron and could heat up during MRI, but this is rarely a problem." So maybe it depends on the dye, but either way I wouldn't imagine it would be a big problem, probably a little discomfort if anything.
        • by ceoyoyo ( 59147 )

          It depends on the dye (as the other replier mentioned), the location, the sequence that's run and the coil that's used.

          The red dyes are of more concern because they sometimes contain iron. If you combined that with a high field magnet, imaging near the tattoo and a sequence with lots of RF you might get some heating.

          Naturally the Mythbusters didn't test all the combinations.

      • Metal plates might be a bad thing though.

        Newer ones are not a problem. I have one in my leg from when I took a nasty fall down a flight of stairs a few years back, and I have no idea what it's made of, but it doesn't set off metal detectors. I have spoken to people with older plates though that do.

  • by Drakin020 ( 980931 ) on Wednesday December 10, 2008 @02:12PM (#26063209)
    What about wireless Tasers?
  • by prgrmr ( 568806 ) on Wednesday December 10, 2008 @02:12PM (#26063213) Journal
    This unit collects energy from the ambient electric fields using an on-board 'reverse Tesla Coil,' which in turn charges a large, on-board capacitor bank. The capacitors then drive a DC motor connected to one of the wheels, providing motive effort for the machine.

    I wonder how much ambient electricity can be captured in a large city as an alternate means of powering an electric car?
    • by lxs ( 131946 ) on Wednesday December 10, 2008 @02:18PM (#26063299)
      You could probably run a car on the stray emissions of a city. But running one car per city is mostly useless. There would be fights over who'd get to sit up front.
    • by smellsofbikes ( 890263 ) on Wednesday December 10, 2008 @02:52PM (#26063859) Journal

      People who live near (under) high-voltage cross-country power lines can tell you about harvesting electric fields. People have been known to run wires through their attics, parallel to adjacent high-voltage lines, and run lights off them. It's considered power theft, which I think is a shame, because it helps make the rest of the house a little more liveable, with fewer shocks from touching light switches or heating vents.
      In Moab, Utah, there's a popular bike trail with the parking area right under a major power line. There are audible snapping and popping sounds coming from bikes on car-top racks. I keep meaning to wire up a capacitor bank and see how far it charges up while I'm out on a ride, but I haven't had time yet to build that.

  • The words "Lightning" and "laptop" in the same article... I think I will pass. Who cares if it's high voltage, high frequency. ITS LIGHTNING! Plus 800W is a bit overkill for a laptop eh?
  • How long does it take to heat up a burritto?

    Isn't this the basic idea behind a microwave oven?

    • Re: (Score:2, Informative)

      by X0563511 ( 793323 )

      Nope. Standing-wave microwaves are absorbed by water molecules, and re-radiated as heat.

      • So - if I understand this properly, that means that anything that was completely dry could sit in a microwave indefinitely without heating up (assuming the air in the unit had all moisture removed too)?

  • Aren't there many stories of farmers who would set up antennas to steal power by induction from high voltage lines that run across their fields?

    • and they weren't able to get enough power to make it really worthwhile. They concluded that it was possible but that you'd need a really large rig to get worthwhile amounts of power and that such a rig would be easily detectable.

      • They concluded that it was possible but that you'd need a really large rig to get worthwhile amounts of power and that such a rig would be easily detectable.

        If it was . . . what could they do? It seems like if he's not touching of modifying their equipment, that there's not a lot that they could do if he's on his own property. It's not even a case of "intellectual property" or anything like DirecTV can claim against satellite "theives".

    • Myth-busters did this as well. For the cost of materials it isn't worth it. Hundreds of dollars of material to get barley enough electricity to run a watch. You are better off using a battery and replacing it when you die. Say $5.00 for a watch battery, that lasts 5 years. So if you spent $100 to get the stray power from the grid it will take 100 years to get a return on your investment. More likely they illegally tapped into the power lines without killing themeless.

    • by mcgrew ( 92797 ) *

      My dad was an electrical lineman, and did a lot of construction, including building the high tension lines on the big metal towers. He said even before there was any power plant-generated electricity flowing through the lines, you could coil a wire around one and arc-weld your initials onto the tower.

      He could never figure out how it worked, but it was obvious to me - the electricity was being generated by the Earth's magnetic field and the motion of the transmission lines swaying back and forth in the wind.

    • How about this guy. It looks like a little more power than it takes to run a watch.

      http://cellar.org/showthread.php?t=14259 [cellar.org]

      Also my dad was telling me about how when he worked in a radar stating in the airforce. If you pointed the range finder antenna downtown you could light up the arc sodium lamps.

  • Even a 100 years or so later, the man's idea are still way ahead of the curve! Nonwithstanding of the whole "cracking the earth in half with a bomb" and "portable earthquake machine" claims, of course. Then again, maybe in another 100...
    • by Anpheus ( 908711 )

      The mythbusters tested the portable earthquake machine on an unused bridge and got the whole thing to start vibrating using only a small linear motor.

      Given that more powerful mechanical forces introduced by wind can cause much more damage, I would like to see a repeat experiment with a more powerful linear motor and a more accurate measurement of the resonant frequency.

      As far as causing an earthquake goes, I think you'd need to connect it to bedrock or something.

  • The Tesla is a unit of magnetic flux already, 1 Tesla (T) is equivalent to 10,000 Gauss (G)
  • It matters not one whit whether they can push X watts Y meters. What matters is the the efficiency plug to socket. Anything over 25% is unlikely. Anything under 80% is wasteful.

    And it's important to not cook anybody's eyeballs into 3-minute hard-boiled eggs in the process.

    Experience with radar waves shows that any flux over 5 milliwatts per square centimeter is going to cause cataracts. Not good.

  • by Taxilian ( 516595 ) on Wednesday December 10, 2008 @02:51PM (#26063845) Homepage
    Another problem that any physics professor will tell you (after pointing out that "the boys" are not going to be in any more danger from that than they are from your cell phone, since neither would be likely to operate at a frequency at which the human body is resonant) is that any bit of metal can act as an antenna. All it takes is to have one piece of wire inside your laptop that happens to be the right resonant frequency for the power that is being transmitted and ZAP! I for one would not want my sensitive electronics that can be fried by static electricity in the wrong place to be anywhere near something like that.
  • by Muad'Dave ( 255648 ) on Wednesday December 10, 2008 @03:18PM (#26064237) Homepage
    What's the frequency, Kenneth?
  • by gillbates ( 106458 ) on Wednesday December 10, 2008 @03:19PM (#26064249) Homepage Journal

    Look at the transfer efficiency: they're using a 3.6 kW transmitter to power a mere 775 watt load.

    At distances beyond ten meters, even steam engines have better efficiency. When you consider the best efficiency they had was 38%, and most power plants are about 33% efficient, they need a considerable improvement for this to be practical. By way of comparison, the typical cable delivery system is about 90% efficient and doesn't have the somewhat undesirable property of setting nearby electronics on fire.

  • by TheNarrator ( 200498 ) on Wednesday December 10, 2008 @03:24PM (#26064319)

    I have been following "new" energy for years. Every "new" energy story is a mystery novel with the last half removed.

    1. Big announcement.
    2. Impressive Demo.
    4. Denunciation by "mainstream science" (Second Law of Thermodynamics, etc explained again)
    5. ????
    6. Never hear anything else about it ever again good or bad.

  • by cryfreedomlove ( 929828 ) on Wednesday December 10, 2008 @04:21PM (#26065189)
    Imagine the applications of this if we had a sizable fleet of electric cars in use.

    Place chargers near congested intersections in big cities. Cars would be getting charged while waiting at red lights.

    Parking garages for large office buildings would charge all of the cars parked in them for the day.


Feel disillusioned? I've got some great new illusions, right here!