Maybe a few tens of watts across a distance of several meters, tops. This sort of technology just doesn’t scale up well without serious safety or efficiency issues coming into play. In theory, we can beam megawatts of power across miles using microwaves, as the SD article indicates–and with pretty decent efficiency–but this presents a seriously large safety problem; all it takes is a strong storm or an earthquake or something to knock the beam off axis and you’re potentially putting thousands of people in a giant microwave oven. No thanks.
GUYS. Did YOU read the article in full? I was asking questions about this powercast business a few months ago, and I’m glad to finally find an article that says more than bullshit.
Apparently, these people’s innovation is to make an antenna that can autotune and pick up multiple frequencies. This lets them recover “70%” of the energy that’s recoverable (I wonder how much previous receiver designs recovered). It also lets them, apparently, absorb waves that have bounced off walls. It may be possible to wallpaper rooms with radio mirrors, and actually achieve reasonable efficiency. If that’s not possible, though, then this tech is just an incremental improvement on the induction-based recharge matts that are also trying to reach the market.
Anyway, all you guys keep shouting your point that powering cities wirelessly impossible, which it is. Only a few have pointed out that two sides are arguing about two different things. So shut up. And One Hit Wonder, READ WHAT OTHER PEOPLE ARE SAYING.
BTW, demo videos that I watched the last time I looked into this barely worked at 3 inches, not 3 feet. 3 feet might power a wristwatch.
Perfectly stated. To which One Hit Wonder replies:
The reply is a non-sequitor, but OHW does have a point about the sculptor… Cecil also never even mentions ordinary induction or explains how power can be transmitted over short distances. He just makes the reader think someone pulled this idea out of their ass based on the theory of Ether.
Frankly, I think this was just a bad, overly-opinionated, under-insightful article on Cecil’s part. But Cecil wasn’t really wrong…
BTW, wireless electricity transmission doesn’t necessarily involve waste proportional to geometry. In induction, the two coils sit merely side-by-side but are coupled to eachother and let very little energy radiate out. It’s not out of the realm of the imaginable for someone to invent a way to couple receiver and transmitter in a way that works over a longer distance. In fact, I think that this is one of Powercast’s claims, although I very much doubt the effect is large.
what makes you think I’m not? sorry that I don’t have much to say about the long division of polygonal breadstick theorem…I’m just talking about the idea as a whole.
interesting that videos of the device (I didn’t look at any) show it only working reasonably from a few inches away…I have no doubt they’re hyping their shtick…personally, I bet in ten years this company diverts their attention to wireless tv’s or something, using the guts of this idea in related applications within. But I would never put it past tech nerds to surprise us all within our lifetime…Uncle Cheech seems certain they won’t in his article.
STATUE of limitations!!! I know what i’m talking about!!! 
http://www.mortalwombat.com/Special/Statue_of_Limitations.jpg
Only if they’re magnetically coupled by a ferromagnetic core, as in a transformer. Otherwise, it’s 1/r^2 as usual.
'zactly what I’m saying. I don’t know anything about this stuff…but in two seconds on the internet, his article is worthless vs. what it could be…hence, pwned. And I stand by his final sentences being wrong, in the same light.
Well, yeah, inasmuch as anyone can really be “pwned” by a self-admitted scientific illiterate who spent about 2 seconds researching the issue. Sort of the same way a bug “pwns” the windshield by making a spot upon it.
wow, you actually went back and edited that? for what, clarity?
In as much as any self-admitted scientific illiterate who types “broadcast power” into a google search and gets the two articles in my original post as first hits would quickly decide The Straight Dope ain’t the place to go for answers on the matter, hell yeah. Cecil got pwned mighty quick. Did I say I pwned him?
Here’s a thought, instead of insisting lack of pwnership, why not spend some more time elsewhere on the net and educate yourself to the extent that you’re able to comprehend even the most fundamental definition of the term?
…hey, that sounds familiar…scrolls up…
you’re all as pleasantly educational as a preschool teacher with a hangover.
“dammit kids! it’s called fingerpainting…not smear crap around with your hands and make a mess!”
I’m afraid you’re all gonna get the last word on the matter…adios!
I’ll agree you’re an expert on limitations. 
Pleasant is exactly what the Straight Dope Message Boards aren’t, and I don’t think anyone pretends otherwise. In terms of education, though, I can’t think of a finer place on the web.
Cautious indeed, I would be, before calling The Master wrong.
Yet, this whole idea is intriguing. How much broadcast power is floating around my household, and could I manage to run some small appliance on it? Hmm
Well, I dunno. It wasn’t exactly a great article, to be sure, and some discussion of the scale effects of broadcast power in general would have made the article a lot more insightful. However, the little thing that One Hit Wonder likes to ignore is that the original question was, “could broadcast power be used for non-polluting electric vehicles?” Whether broadcast power can recharge the cell phone in your pocket is interesting an all, but it’s more of a contrast to opering an electric vehicle than a comparison with same.
Statements like this make it pretty clear that you aren’t reading what other people are saying, and prefer to argue from a position of ignorance.
Measured against all the wonderful, marvelous things brought to us by today’s Internet, the phenomenon of the Instant Expert must weigh heavily as an extreme irritation.
Appears to have been appropriately chosen, too.
It gets me every time - the sheer delight people like** OHW** take in their own ignorance. As though a lack of knowledge is a positive qualification.
Here’s an ad for a christmas tree with these lights–I definitely saw them advertised in mainstream media within the past year: http://www.frontgate.com/jump.jsp?itemID=12210&itemType=PRODUCT&path=1,2,556,2922,&iProductID=12210&k=XX23159
Note that the tree still has a cord (because the transmitter is in the base of the tree)–it is just the lights on the tree that are “uncorded.”
You say “overly-opinionated” as if it were a bad thing.
From the link:
HAHA. Powercast is so full of themselves. They even thought people would buy their dumb tree for $400.
OWH I hope I can clear this up for you. I can list a device that was powered solely by radio waves back in the 1920’s: it’s called a crystal radio. You could conceivably use it to charge an AAA battery, but my guess is you’d be long dead before it fully charged.
This technology which you stated has “pwned” Cecil is simply a more refined version of the crystal radio. This type of ancient radio captures a small amount of electromagnetic energy in the RF spectrum within a narrow set of frequencies (think of flashlight that has a cover of red cellophane and only emits a pure red light like a Helium-Neon laser). The crystal radio’s captured power is going to range in the microwatts to nanowatt range, and additional losses within the radio will result in another 100 fold loss of amplitude before it hits the ear drum—fortunately, for you, your ears are exquisitely designed to capture low power audio (down to the trillionths of a Watt).
What the article stated was the transmitter-receiver system is more efficient in capturing a lot more power at a short-range distance. In other words, remove the red cellophane from the flashlight, and brighter white light will now show. That’s all the Powercast® receiver really is, it can see many more colors in the RF spectrum then a crystal radio would see and by extension gathers a lot more energy which is significant enough to be useful.
There’s nothing new here, theoretically, other than someone figured it could be made practical and cost effective. Cecil pointed out that the broadcasting power to free space (i. e., the great outdoors) isn’t practical. And that’s still the case. You didn’t read the article closely enough—it directly states that energy is being captured is “bouncing off the walls.” What does that mean? Think of blowing a fire cracker off in the men’s room, rather than outside in an open area. Which one is going to leave your ears ringing more? Again, think of reading inside of a white room with a single light bulb as opposed to reading out at night with a single light bulb. You’re going to need a brighter light bulb, or hold your book closer to the light to get the same brightness on the page outside in that mean, dark, cruel world.
In other words, the walls are serving as reflectors of the Powercast® transmitter, and helping reflect the energy from transmitter around the room to the receiver. Not unlike a microwave oven, but without the splatter. OWH, that’s what you’re calling “broadcasting power.” That’s not what Cecil intended, nor was that what Tesla wanted to do. Cecil and Tesla spoke of sending it out to free space, not keeping it some confined area (which is what Powercast® takes advantage of), and that the economics of using the technology of broadcasting power to free space back then, as now, are as impractical as launching the Saturn V to the moon on charcoal briquettes and lighter fluid.
Let me expand this with that earlier analogy: if you place a light bulb out in field at night in an open field, the amount of light reaching your eyes is going to be less then inside of a white room. That’s where your understanding breaks down OWH, you keep thinking that that the right kind of light bulb is going to fix the problem. It isn’t the light bulb–doesn’t matter if it’s a compact fluorescent bulb, an LED bulb, Castle-Bravo, or a hyper-nova. It’s the path the energy takes and the losses it incurred that determine whether the received energy is useful or not. In the big outdoors, that means most of it speeds off to sky never to be see again. And who wants to invest in a power source that even my home generator can beat literally a million times over for cost even with record gas prices?
It seems to me, OWH, IMHO your knowledge and understanding of electromagnetic fields seems to be comparable to Ben Stein’s understanding on evolution. You seem to think that because you’ve read something and presume to be smart enough to understand it, you’ve discovered some obvious holes. Good luck, cause I’m sure your still young and very smart. Probably a lot smarter then me. I have no problem admitting that right now, but I did about thirty years ago.
In thirty years, you’ll understand why.
Well, in fairness, Frontgate is one of those over-priced catalogers, kind of like the Sharper Image of home decor, and any holiday tsatske will be seriously discounted if it doesn’t sell out by the 25th of December. But, yeah, expensive light sticks and tinsel.