Broadcast power

About this column…

I do realise this column was written almost 20 years ago, but still, i want to reflect on this - for wireless electricity is now a reality. I’ll provide a link:

And they directly admit they developed it following Tesla’s notes, Sony even built a TV based on this technology. Obviously, this is not a 26 mile run, but maybe thats also plausible. So dear Cecil, maybe its time to review this, and admit that even if Tesla was a nut, you cannot prove that based on the idea of wireless electricity.

Sonko

Sorry, but this has been done many times before, with your very own link included in them. The correct answer is that everybody, including even Cecil amazingly, understands that broadcast power is of course possible at small distances and in small amounts. Tesla’s insane notions remain impossible, though.

Earlier threads.

What’s with all you guys who think that Tesla was so far advanced from his time that he could invent marvels that nobody in a century since can reproduce? That doesn’t happen. We know a jillion times more about every aspect of science, technology, engineering, and materials than he did. How could he have accomplished any of this stuff using his era’s equipment?

The sad truth is that Tesla had mental illnesses that affected his work. Virtually nothing he did after about 1900 ever came to fruition, although his earlier successes kept getting him backers. Screaming that he was an unsung genius doesn’t get you anywhere if none of his work is replicable.

Hmm, sorry for not looking through, should have found the topics you mentioned.

Slow down please! I’ve never said any of that, the maximum you can make out of my comment is “Tesla wasn’t crazy”, which is frankly, maybe a wild theory, but nowhere around this.

Now that came up, i think Tesla was a very special man, and he did invent a lot of significant stuff, and maybe he didn’t got the credit for all his work, and again maybe, he had other, “forgotten” ideas, which may inspire new technology nowadays.

Wireless electricity may advance in the next few years, or may not - almost any technology is constantly evolving (think of mobile phone, or computer industry), why this isn’t plausible, too?

(Or i could assume that was a rhetorical question?)

Because you’re confusing “I want to run a marathon faster than anyone ever has before” and “I want to be able to fly by flapping my arms”.

[LIST=A]
[li]Tesla’s basic theory with regard to broadcast power was based on plain old magick. The way he wanted to do it just can’t work. Ever. It’s grounded in a falsehood.[/li][li]The short-range wireless power technology that does exist (it’s not even all that new – my electric toothbrush, several years old now, charges its battery wirelessly) could, in theory, work – at the price of frying everything for miles around. It’s roughly the equivalent of trying to solve the fresh-water problem by having everyone live under an artificial lake. It worked for Sir Lancelot’s stepmother, but – there you are, magick again![/li][/LIST]

I didn’t check through all of the other links so there’s a good chance that this was already mentioned, but the main thing that makes it implausible is the fact that it is horribly inefficient. It’s not too bad if you are doing something over a very short range like the toothbrush charger that John mentioned, but if you try to blanket a large area with radiated power most of the power ends up wasted.

As energy resources get more and more scarce, the idea of setting up an energy delivery system that wastes most of the energy that goes through it starts to sound a little silly.

It’s the same reason you’ll never see a flying car any time soon. We can make flying cars with existing technology, but who would want to spend $1000 a week on fuel to go to work and back when their existing car can do it for $30?

Wireless electricity doesn’t work through radiation. Instead, it works by coupling to the near magnetic field. The near field falls off like 1/r^3, so the distance must be small, but the near field component doesn’t radiate.

I heard about a system that used microwaves to beam energy a few years back. Different than what you describe, still isn’t radiating energy…

…still inefficient and a waste of time. Oh well. Wireless power is still a fun fantasy, like teleporters.

But if you crank up those small amounts? (figuring on my TI-59 calculator) Tesla’s insane notions are still screwed.

Tesla worked at the very beginning of electrical mathematics.

So did Edison, but he didn’t care. DC carried an even shorter distance before being pissed away in the wires.

In the greater scheme of things, they knew EVEN LESS about the subject than I do, and I know next to nothing. I mean, even a mathematical moron like me sees how the Inverse Square Law becomes more and more irrelevant the further one reaches from the antenna, and that is measured in inches and feet. Real power over miles? Not unless you plug a SHITLOAD (it’s an engineering term and you can look it up) of power beyond what you want to transmit AND don’t care how few centimeters the bulk of it is transferred.

Earlier threads.

What’s with all you guys who think that Tesla was so far advanced from his time that he could invent marvels that nobody in a century since can reproduce? That doesn’t happen. We know a jillion times more about every aspect of science, technology, engineering, and materials than he did. How could he have accomplished any of this stuff using his era’s equipment?

The sad truth is that Tesla had mental illnesses that affected his work. Virtually nothing he did after about 1900 ever came to fruition, although his earlier successes kept getting him backers. Screaming that he was an unsung genius doesn’t get you anywhere if none of his work is replicable.

However, one of my twins almost got named Nicola, because his successes beat the shit out of his failures. She ended up being named after the female component of the squirrels who kept begging at our kitchen door. Or Santa Claus. OR, indirectly, after one of her aunts, but that would not mean her twin was named, “Tickle.” Which she wasn’t (she’s my junior, thankyewverymuch).

Wooo, look at everyone foam at the mouth.

To be fair, there seems to have been a recent advance over the plain “toothbrush” induction coupling. Somehow the two inducting loops are constructed to be “in resonance,” boosting the efficiency a fair bit. (Enough to propel it into more consumer uses.) I wanted someone on the boards who is more knowledgeable to explain it, but they’re just too busy foaming…

I didn’t know the Straight Dope Science Advisory Board was so famed for its modesty.

It’s not a question of “immodesty”. Anyone who’s passed Physics 101 knows more about the subject than Edison did, and anyone who’s done the whole four years knows more than Tesla did.

As to “how resonance works”, I rather fancy the math is too nasty to typeset here, but there’s a brief discussion on Wikipedia s.v. “WiTricity”. But you should know that the essence of it all is that it’s short range and (for safety) low power, not just because it’s experimental, but because it’s a fundamental limit of the process. Charging batteries for modern portable electronics, yes; powering electric cars, no; and “More power!” won’t make it work any better.

T

Sure, it fries everything, really, as you can see the craters and ashes everywhere. Again, i didnt mentioned “zomg wireless electricity we can power remotely everything”. I just said the technology exists, and on a somewhat advenced level than in Tesla’s time.

On the other hand, for the question why it isnt commercially, wide avalible, it’s perfectly reasonable that because its inneficient.

From your link:

Which, for metric challenged Americans, is less than 20 inches.

To hell with this Tesla stuff… you have a TI-59 that still works?!?

I had a TI-58 way back when, but I upgraded to an HP-41C in 1981. My 41C still works and I use it regularly. But I’m shocked that the TI-59 would still be functional.

We’re still stuck at the immense chasm between point-to-point at six feet and broadcast at miles.

You didn’t have to; it’s the subject under discussion in this thread.

Read the resonant energy transfer article. It’s pretty cool. Here’s how it works.

[ul]
[li] Instead of an inductor, you have an inductor and a capacitor[/li][li] The LC circuit resonates as normal, storing energy yet making it available for on-demand consumption[/li][li] Consumption happens when another nearby coil leeches power via magnetism *[/li][li] Nearby coils that are also LC circuits of the same resonant frequency, leech many more watts through the magnetism *[/li][/ul]

  • By “leeching” I mean the process by which induction creates a current in the receiving coil (raising the energy of the receiving coil), and thereby creating an opposing magnetic field, which counter-induces the current in the transmitting coil (creating a ‘back-EMF’, ie a reduction in voltage). Any coil or other parasitic inductor will do this. Yet when the receiver is also a resonant circuit of the same frequency (and the received energy is not used or taken) the current builds up higher and higher, creating a stronger opposing field and increasing the rate of energy transfer between the transmitter and receiver.

Ideally, the device can aspire for very good efficiency. That is, energy is not fundamentally wasted by an R^2 law or any such thing. The main challenge is creating coils with very low resistance and very high inductance. This is to reduce the resistive losses, increase the transmission rate, minimize the size of the transmitters/receivers, and affect the relative impact of parasitic losses in the environment.

As electric cars await supercapacitors, so perhaps broadcast power awaits superinductors.

Sonko said:

The issue is not about applying a limited amount of energy to a direct transfer over short distances to power 1 specific device (or perhaps a handful of similar devices), but dumping large scale power transfer to everything at any distance. It’s like the difference between trying to water your lawn from a garden hose vs. using that same hose to water the neighborhood, the city, the country.

That’s what the topic of discussion is - large scale remote power for everything over vast distances, not localized, specific item transfer of power over a few feet.

No, that’s what you want the definition of “broadcast power” to be, so that you could be unequivocally right.

It’s the topic of the original 1990 question, it’s the topic of Cecil’s original 1990 answer, it’s the topic of the follow-up question, and it’s the topic of Cecil’s follow-up answer. And it’s implicit in the very word “broadcast”.

The word “broadcast” implies neither kilowatts or miles. Granted, it implies something more than a TV that’s hanging a foot from its power source, but it could mean broadcasting across a room or a building, or broadcasting a small amount of power for cellphones. All exciting scenarios. Clearly, you want to maximize the claim as much as possible (and refute any possibility of the claim being more modest), so you could feel more certain in pouring shit on it.

But the original question to Cecil most certainly did imply both kilowatts and miles. Original question:

The followup comment from another reader, discussing Tesla, said in part:

I think it’s not a bad thing to discuss short-range broadcast power for things like cell phones, even within the context of a high-power, long-range bradcast power discussion, specifically because it highlights why one can work and the other can’t. However, this is the “Comments on Cecil’s Columns” forum, and the original column was indisputably about whether high-power, long-range broadcast power was feasible. The answer to that is “no,” regardless of the feasibility of low-power systems.