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Power Technology

Focused Microwaves Could Enable Wireless Power Transfer 180

esocid alerts us to news out of the University of Michigan, where physics researchers have found a way to focus microwaves to a point 20 times smaller than their wavelength using a new 'superlens'. Such resolution was thought to be impossible until recent years, and it could bring about the capability to transfer power wirelessly. "No matter how powerful a conventional lens, it cannot focus light down to more than about half its wavelength, the 'diffraction limit'. This limits the amount of data that can be stored on a CD, and the size of features on computer chips. The new lens is a 127-micrometer-thick plate of teflon and ceramic with a copper topping. 'The beauty of these is that they're planar,' Grbic says, 'they're easy to fabricate.' The lenses can be made through a single step of photolithography, the process used to etch computer chips."
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Focused Microwaves Could Enable Wireless Power Transfer

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  • by MichaelSmith ( 789609 ) on Friday April 25, 2008 @08:06PM (#23204236) Homepage Journal

    a superlens-based CD, DVD or Blu-Ray system could get 10 times the capacity per track
    Maybe it could it improve resolution in integrated circuit manufacture as well.
  • Re:We tried that (Score:4, Interesting)

    by CRCulver ( 715279 ) <> on Friday April 25, 2008 @08:08PM (#23204248) Homepage
    It's interesting to consider whether power beamed down from orbit even has much of a future. If space elevators ever become a reality, it seems much safer just to have power from orbital solar arrays wired back down the elevator than beam it, where anything passing through could be fried.
  • by Ungrounded Lightning ( 62228 ) on Friday April 25, 2008 @08:25PM (#23204364) Journal
    Back in the 1960's. Diode grid to rectify the beamed power. Bad idea.

    Actually it was a very GOOD idea. But NASA blew it.

    The plan was to site solar power satellites in geosync orbit and bring the power back via microwaves.

    Unlike microwave ovens (which are tuned to a frequency that is strongly absorbed by water), these would be tuned to a frequency where water - clouds, rain, birds, cows, people - is essentially transparent. This is good both for getting the power through the atmosphere and avoiding rains of roast duck.

    I could go into detail on why there's no problem from the millimeter waves, but that would take time. Short form: System failures defocus the beam so much it becomes just radio interference in directional antennas pointed at the satellites. Even when fully focussed it's not an issue for tissue: You can grow crops and graze cattle under the (rather spindly) rectennas, so they don't even use up the chunk of land they're on.

      - Enough power to completely replace fossil fuel AND nuclear plants and absorb forseeable energy use expansion for decades.
      - 'Way cheaper, too. (Even at '60s fuel prices.)
      - Essentially no pollution at ground level.
      - Bootstraps a space program that can then move other manufacturing processes, and THEIR pollution, off the planet as well.

    NASA blew it by doing a study that purported to show it would be too expensive. But they did that by splitting the design teams for the rockets and the power plant. The power plant designers made a turbine very large to get a couple extra percent of efficiency. Then the rocket designers came up with a heavy lifter sized to take the biggest piece. Result: Enormous rockets with few trips to ammortize the design/construction costs, rather than moderate sized ones with many trips. Cost skyrockets versus a properly integrated design with a small turbine and a fleet of smaller lifters.
  • Re:We tried that (Score:5, Interesting)

    by NeverVotedBush ( 1041088 ) on Friday April 25, 2008 @08:57PM (#23204534)
    The issue with wires is that you will have IR drop and I^2R power losses. If you make the wires thicker to cut the resistance and losses, you have now made the wires heavier. Plus, you have to somehow support the weight of all that wire which means the tensile strength must be huge.

    On the other hand, if you beam the energy down, you will have much lower losses provided the atmosphere is transparent at the wavelength you use to send the energy. All you will get from beam spread will be a lower energy density but the same total amount of energy (aside from absorption and scatter losses) will be available.

    Beaming power down is probably a much more efficient way to go depending on conversion losses at the source, the scatter and absorption losses, and the conversion losses again at the receiver.

    I don't know about the efficiencies and losses of beaming but would guess they would be much less than however many miles of cable would be required and would bet the cost would be lower as well.

    You would just need to make damn sure you switch the beam off if it quits tracking the target receiver. Bu as the other person commented, I think this isn't intended to beam power from space.
  • Re:We tried that (Score:4, Interesting)

    by node 3 ( 115640 ) on Friday April 25, 2008 @09:24PM (#23204684)
    The energy in question is coming from the sun, and was going to enter the biosphere anyway.

    To a certain extent, the effect will be the exact opposite of what you are thinking, as the sunlight would have most assuredly heated the land, sea and air, but beamed down to the electrical grid, it will be stored in other forms, such as the potential energy of a high-rise building, or in places where the increased warming isn't terribly important, like the area immediately around a ski lift.
  • Re:We tried that (Score:2, Interesting)

    by Anonymous Coward on Friday April 25, 2008 @10:52PM (#23205092)
    Actually, wire losses fall off as 1/e^(decay*r); it's free space where losses go as 1/r^2 when you get to the antennas' far field, but your overall point is still valid.

    For *any* wire, even if it was made out of a really good conductor like gold, there is always some distance where the losses become greater than that of wireless transmission at the same distance.
  • by Anonymous Coward on Friday April 25, 2008 @11:10PM (#23205162)

    I'd prefer to not have any randomly scattered ionizing radiation impinging on my home, thanks.
    Well it's a good thing microwave radiation isn't ionizing, then. This obvious mistake makes me less likely to believe every other part of your post. Do you have any actual data about the efficiency of beaming power through the atmosphere and whether it is so bad that it outweighs the advantages of 24/7 sun with no atmospheric attenuation in space, or are you just shooting your mouth off about your completely unfounded opinions?
  • Re:We tried that (Score:3, Interesting)

    by beav007 ( 746004 ) on Saturday April 26, 2008 @12:28AM (#23205470) Journal
    So. What about beaming it down the elevator umbilical cord, using optic fibre?
  • by tcgroat ( 666085 ) on Saturday April 26, 2008 @08:59AM (#23206750)
    The deal-killer for space-based power generation via Hertzian cables is the difficulty of putting it in geosynchronous orbit. Consider how long and how many flights it's taken to assemble the ISS. That's for low earth orbit, where the space shuttle and Souyuz can reach it. Getting a series of power generation satellites to the Clarke belt would make that task look simple.
  • by Bruce Perens ( 3872 ) * <> on Saturday April 26, 2008 @04:51PM (#23208880) Homepage Journal
    It's a gun. Phaser, here we come.

"How many teamsters does it take to screw in a light bulb?" "FIFTEEN!! YOU GOT A PROBLEM WITH THAT?"