
Wireless electricity? It's here - uladzislau
http://www.cnn.com/2014/03/14/tech/innovation/wireless-electricity/index.html
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tehwalrus
> _" Don't worry about getting zapped: Hall assures that the magnetic fields
> used to transfer energy are "perfectly safe" \-- in fact, they are the same
> kind of fields used in Wi-Fi routers."_

LOL. power transmitted by a Wifi router ~= mW. Power required for, even a low
energy light bulb ~= 10W. The current draw in modern homes is so big that EM
transmission, especially at sensitive wavelengths like microwaves, is highly
likely to cook things (and people).

They may well have found a real way to make it work. But saying "it's the same
as wifi" shouldn't convince _anyone_.

~~~
squintychino
The common type of bulbs in a few years will be led lights. How much power
does an led light bulb draw? Certainly less than 10W I'm guessing.

~~~
ChuckMcM
True, but its remarkable how constant the amount of electricity the 'typical'
home draws, even as the things in it draw less. Things like the TV went from
several hundred watts to only a couple of hundred, and then we added a home
computer. I agree with the grandparent that you're not going to send a few kW
of power into a house like this.

The other aspect that wireless power folks face is that _any_ conductor now
has a much more serious voltage potential on it. This can cause weird things
to happen when dissimilar metals are suddenly energized. Electro transport can
cause otherwise strong welds/connections to vanish.

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quesera
> Dr. Hall, CTO WiTriCity: > "We just don't think about it anymore: I'm going
> to drive my car home and I'm never going to have to go to the gas station
> and I'm never going to have to plug it in.

Count me as a wireless electricity skeptic, in general. But this claim is
astounding to me.

I believe that if you placed a properly resonant circuit into an MRI device,
for example, you could charge a decent sized battery (but probably not a
vehicle propulsion battery) at a reasonable rate.

But it would be horribly inefficient and your car (and everything else in your
garage) shouldn't be made of ferrous metal.

Cell phone batteries on little charger pads, sure. Maybe even via ambient EM,
though I'm not convinced you could get regulatory approval above a certain
emissions level (which, critically, has an inverse-square relationship to
available current delivery capacity at the device).

But the article also talks about lighting and televisions, and cars. WiTricity
has investors to fluff, clearly, but is this not absolute crazy talk?

~~~
IanCal
The claim on their wiki page was a light bulb at 90% efficiency at 3 feet. If
it's more efficient when closer, you could put one in the bottom of your car
and one just below the surface of your garage, and you'd probably only have a
separation of about 1 foot.

> But the article also talks about lighting and televisions, and cars.
> WiTricity has investors to fluff, clearly, but is this not absolute crazy
> talk?

They've apparently already powered lighting, and the TED talk supposedly had
them powering a TV [0]

[0]
[http://www.ted.com/talks/eric_giler_demos_wireless_electrici...](http://www.ted.com/talks/eric_giler_demos_wireless_electricity)

~~~
quesera
Ok, sure. If you can control the proximity carefully, you can achieve
reasonable efficiency. Transformers work.

But it's still a super high powered magnet. There are more places than not
where that's just a bad idea. Garages are high on that list. Also carports,
kitchens, living spaces in general...offices, sleeping spaces..bathrooms. All
bad.

LED lighting gets you pretty far down the current draw curve, but I don't see
a small, easily moved coil generating enough resonant current to be useful in
many common consumer electronics. That coil has to be plugged in to the mains,
remember -- invalidating the promise of wireless power, even at three feet.

And ambient charging has all of those problems, squared.

~~~
thefreeman
Also, can't magnets interfere with pacemakers? "Oh, you have a pacemaker? Ya,
don't come over or you will die... I don't want to have to plug in my lamps."

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adrusi
This looks interesting, but the conjectures people are making about pcell (the
frontrunner for 5G cellular) being used for wireless power describe a more
attractive solution.

They would provide power only to the area of space where the receiver is which
first and foremost makes it inherently safer than a system which doesn't focus
the power. I'm not going to claim I know much on the topic, but intuitively it
would seem that the ambient power produced by the pcell transmitters would
scale logarithmically with the power being transmitted.

But I trust that Witricity's produce is safe for most people since these
things are highly regulated for safety. Perhaps more important to adoption is
that the nature of Witricity's technology makes it impossible to selectively
transmit power. Therefore, it would be impractical to charge a fee for using a
power source. Pcell __can __do this, because it has to to be useful as a
cellular technology.

I don't see a world where electric cars are charge wirelessly by beacons on
roadsides, not at current electricity prices and the loss that would be
involved, but I can imagine low power devices such phones and laptops becoming
much more elegant through wireless power.

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daimyoyo
It's been here for more than a century.

[http://en.wikipedia.org/wiki/Wireless_power](http://en.wikipedia.org/wiki/Wireless_power)

~~~
mmphosis
[http://en.wikipedia.org/wiki/Wardenclyffe_Tower](http://en.wikipedia.org/wiki/Wardenclyffe_Tower)

[http://theoatmeal.com/comics/tesla](http://theoatmeal.com/comics/tesla)

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finishingmove
No mention of Tesla (Nikola Tesla) in the whole article? ...

~~~
mchouza
He is the first author cited in their paper:

[http://www.witricity.com/pdfs/highly-resonant-power-
transfer...](http://www.witricity.com/pdfs/highly-resonant-power-transfer-
kesler-witricity-2013.pdf)

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drakaal
This isn't new. A "crysal" radio works the same way.

[http://www.instructables.com/id/Build-an-antique-style-
cryst...](http://www.instructables.com/id/Build-an-antique-style-crystal-
radio/)

You can use a Crystal radio to power an LED, or a lot of things, the stronger
the RF source, the more power you can extract. The problem is they aren't
efficient if you are using them as a power source. When you are pulling "free"
energy out of the airwaves they are cool, all that wasted AM band, but if you
are broadcasting just to power your cell phone they are about .1% efficient.
That's not a very eco-friendly.

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clarry
I sure do look forward to getting rid of the mess of power cables on and
behind my desk.

A wireless dog leash would be nice too.

But I'm not holding my breath. I'm also a little worried about efficiency.

~~~
WiseWeasel
A wireless dog leash probably isn't too far off, for those who enjoy the means
to upgrade their furry friend with a remote control brain implant.

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Ygg2
Couldn't the wireless signal used to transmit energy be used to transmit data
as well?

Anyway without a solid power source WiTricity would seem to be kinda non
applicable for larger areas, but it's still good enough for small home
chargers and stuff.

From what I remember about Tesla claiming that he would either use the
ionosphere as a way to either amplify or bounce the signal. It's hard to
separate fact from fiction with that man.

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kirk21
It is just not efficient enough. You lose a lot of energy. JB Straubel
commented that Tesla was looking into smart conductive charging is going to
win out. Read more at [http://evobsession.com/tesla-elon-musk-townhall-
meeting-amst...](http://evobsession.com/tesla-elon-musk-townhall-meeting-
amsterdam-56-minute-video/#EPpeC060WhPrF3tB.99)

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iLoch
Couldn't this affect pacemakers, etc?

~~~
Ygg2
I'd assume so, but it depends on pacemaker model, and the freq. WiTricity
uses.

~~~
lostlogin
This is a very complicated problem. The length and orientation of the leads,
type of pacemaker etc are all factors. And one mistake is one too many. This
applies to a growing list of implants. Spinal cord stimulators, sacral nerve
stimulators, deep brain stimulators, implantable defibs, cochlear implants,
some hearing aids. Its a very long list. The possible complications are not
just possible induced currents, but also heating. Many of the problems are
covered here (although with MRI in mind)
[http://www.mrisafety.com](http://www.mrisafety.com). It's a great resource
but is absolutely terrible to use and everything takes 20x longer than it
should to find.

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shakeel_mohamed
I want this so bad, mainly just for laptops and phones

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chrismcb
Isn't this only about 100 years late?

