What real world factors keep the world or at least countries like the U.S. from having a massive system of wireless power distribution that would in effect replace the current system of overhead and underground distribution? I know distance could be a factor and probably cost and we already have a system that works. Is the technology not advanced enough at this time? Would such a system ever be feasible in the real world?
Wouldn’t massive power loss through inefficient transmission pretty much doom this? Besides, you can’t get people to build houses close to existing transmission lines, you think they’d want power flowing through the air?
There just isn’t any way to broadcast appreciable amounts of energy wirelessly in close proximity to humans, without putting them at serious risk of injury.
Not only is it inefficient, but it would cause all kinds of havoc with existing systems that would act like their own antennae and start picking up current, probably to their detriment. Not to mention royally screwing up radio wave reception in all sorts of bands.
Isn’t the inverse square law the fly in the ointment?
Of course there is. You just keep your power density low. The problem with that is that you’d also need to have very large antennas. If you shoot for, say, 10 watts per square meter, and you want to transmit one megawatt from your power plant to a substation, you’ll need an antenna which covers an area of at least 100,000 square meters and probably more, since no antenna system is perfectly efficient.
Not if you use scalar power…
[related topic] What is the latest deal in those solar power satellites which would beam their
energy down to earth in the form of microwaves? I heard a lot about those 20-25 years ago,
but I guess it all came to naught.
Well, you need an antenna with a large capture area. Depending upon the frequency of the transitted wave, the physical size of the antenna can be smaller than the capture area. Further than that, the 10 W/m[sup]2[/sup] is the power density at the receiving end. What with the divergence of the wave, the power density at the transmitter needs to be many times that.
Considerable power can be sent optically by lasers. However, as has been pointed out, this would be exceedingly hazardous for anyone who wanters into the beam if it were used for the wholesale distribution of power…
Would that be a 1920’s style wireless power distribution system?
Yes, & the difference between that & a Death Ray would be the color of 3 of the knobs.
pool, the broadcast would Shake & Bake™–the Preschoolers!
Give this plan a pass.
OK, you got me. For “there isn’t any way…”, read “there isn’t any sane/practical/cost-effective way…”
How about “scavenging” free or low cost power from already existing radio stations? Say there is a 50,000 watt radio station nearby (the current maximum for the US); is it possible?
Déjà vu - I was reading this only a week ago 
I suppose it’s possible, but you’d want to set up a massive antenna as close to the broadcast antenna as possible, and I think they’d notice and complain - any power you’re sucking out of the airwaves is diminishing their signal strength for their listeners.
There have been cases of people setting up pickup coils in barns underneath overhead power cables, but the power companies notice the drain, investigate and prosecute.
I’ve read the anecdotes too. However, once the power leaves their antenna, it’s “free” to all comers, no?
I don’t have any illusions about “free” power, but I did have the thought that as an interesting hobbyist sort of thing, a “nightlight” or LED might be doable? Say a large antenna, robust ground plane, step-up transformer, diode bridge, rechargeable Ni-cads, etc.
Maybe, maybe not - I expect it depends on the rights granted by any relevant authorities in the broadcasting licence. I feel sure nobody would get away with doing this to the BBC here in the UK (actually, they’d most likely find themselves nobbled by the planning department as soon as they erected their massive antenna)
Interestingly, I asked almost exactly this question in GQ some time ago - because I remembered reading instructions on building such a device; the thread is probably gone by now, but the consensus was that unless it was right next to a powerful broadcast antenna, it would be very difficult to make a device efficient enough that would accumulate power at a faster rate than it leaked away through imperfections in the components, etc.
Do any of our lawyers know of case law on the subject? It seems to me that the intended use of the broadcast signal is for entertainment, information and the like. Can the broadcaster restrict any other use, such as a power source to charge batteries?