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The team consists of (top to bottom, left to right) Andre Kurs, Prof. John Joannopoulos, Aristeidis Karalis, Prof. Marin Soljacic, Prof. Peter Fisher, and Robert Moffatt. (Source: MIT, Aristeidis Karalis)
A 60-watt bulb illuminates for the future of wireless power

"Wireless" isn't exactly a new concept to computing. Network connectivity, USB devices and even displays had their cords cut in recent years.  Researchers from the Massachusetts Institute of Technology took the final steps towards cutting the last tether of the laptop user: the power cord.

Transmitting power wirelessly is traditionally limited to line-of-sight methods such as microwave or laser, which have a "significant negative effect" on anyone or anything unfortunate enough to be caught in the middle.

Playfully dubbed "WiTricity" by the team, the researchers were able to power a sixty-watt lightbulb from seven feet away using the principle of magnetically coupled resonance. The basic concept is similar to existing electromagnetic inductive chargers, but does not suffer the massive drop in efficiency when distance is increased.

The experiment works as follows. Two magnetic coils resonate at the same frequency.  When one of these coils is attached to a power source, the resonant magnetic field produced by the coil increases dramatically.  The second, unpowered coil "couples" with the resonating magnetic field.  The resonance from the second coil is then converted back to electricity for the device.

The MIT researches are quick to tout magnetically coupled resonance over electromagnetic induction.  Aristeidis Karalis, an MIT graduate student that worked on the project, states, "Here is where the magic of the resonant coupling comes about. The usual non-resonant magnetic induction would be almost 1 million times less efficient in this particular system."

In addition to increased efficiency, the WiTricity project does not transmit biologically harmful electromagnetic radiation during operation.  Additionally, line-of-sight issues present in microwave technology disappear with WiTricity; magnetic fields are more-or-less unaffected by non-metallic materials in most environments. 

The most current WiTricity experiments use coils approximately 20" in diameter and operate at distances of approximately two meters.  The team hopes to eventually power a notebook from a several meters away.

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RE: questions...
By Amiga500 on 6/11/2007 12:50:28 PM , Rating: 2
This is probably a proof-of-concept as much as anything.

I guess there will be a few papers published on this somewhere... maybe have a look for IEEE (Institute of Electrical & Electronics Engineers) conferences - I'd guess they'd be presenting some stuff there.

It'll be refined in time of course :-)

RE: questions...
By Oregonian2 on 6/11/2007 1:58:02 PM , Rating: 2
It strangely resembles the concept of the spark transmitter first demonstrated, what, over a century ago? Except back then they keyed it on and off and used the receiving coil for data transmission rather than power. The transmitting coil was resonate, that picked it's operating frequency. I think the receiving coil "antenna" was tuned as well, but I don't recall (I wasn't there). The receiving coil just had an airgap to spark as the "signal" rather than having a light bulb load (but the sparks made certainly indicated power being transferred). They were use for quite a distance as I recall as well (although they got really BIG to gain the distance).

There have been tuned transformers nearly forever as well, although those used an iron core rather than air (and were a LOT more efficient than 40%).

Having two tuned circuits couple power from one to other is about as old as using iron for knives, so I'm not quite sure what's new here other than perhaps the demonstration application, the PR, and the implementation details.

RE: questions...
By Amiga500 on 6/11/2007 2:05:45 PM , Rating: 2
Yeah, it could be based on it all right (as a principal at the very least).

But, from what I understand, the spark transmitter was more of a signal generator (akin to radio) rather than a means of transmitting significant amounts of power.

RE: questions...
By Spivonious on 6/11/2007 2:43:27 PM , Rating: 2
I just thought of this. Big powerplant has a giant transmitter magnet thingy which beams power to the town. Every house and car in the town has a receiver magnet thingy and thus are powered everywhere. The need for batteries disappears. The power companies control the world.

RE: questions...
By FITCamaro on 6/11/2007 3:44:07 PM , Rating: 1
The only way we'd ever make that much power reliably though would be to use nuclear power. And at least the US has made its view abundantly clear with nuclear power in that its satan. I personally hate this fact since I live in the US and want cheap electric power thats not tied to the price of oil.

But thanks to environmental groups we don't get it.

RE: questions...
By agentcooper on 6/11/2007 6:56:22 PM , Rating: 1
sure, blame the environmentalists. Sheesh, what an ignorant statement. I'm an environmentalist and I support more nuclear power.

Don't you think big oil and the coal industry would make a big stink about nuclear taking a huge share of energy production?

And then there's the NIMBY attitude which would be adopted by everyone, everywhere.

RE: questions...
By Ringold on 6/12/2007 12:26:20 AM , Rating: 2
Not to start a flame war, but you're a minority amongst your own people. I watch Bill Maher's show (entertainment) and virtually without fail every liberal/environmentalist he has on his show is against nuclear power, and he doesn't understand it because he, like you, supports it in recognition of its great track record. It's sad..

RE: questions...
By Dactyl on 6/12/2007 2:47:15 AM , Rating: 2
The only reason for NIMBY attitudes towards nuclear power is enviro scare tactics.

It's true there are legitimate reasons to oppose nuclear power (for instance, the waste it creates). But those aren't NIMBY issues, because the waste gets dumped in Nevada or some other desolate place, not near the power plant.

No, the only reason people oppose nuke plants near them is that they're afraid some horrible thing will happen (mutations, cancer, radioactive gas leak, going critical, etc.)

RE: questions...
By Chernobyl68 on 6/12/2007 11:55:44 AM , Rating: 2
actually for quite a while waste is stored on site. Until Yucca mountain is open and legal for permanent waste storage...

RE: questions...
By theapparition on 6/12/2007 6:58:17 AM , Rating: 2
Kudo's to you, but you are a signifigant minority in the enviromenalist group.

However, we see the power (or lack thereof) of enviromentalists lobbying the government. They are not organized, don't have an effective platform, not to mention policies that are ludacris at best. So to blame enviromentalists for lack of nuclear power is wrong.

My own opinion is that the biggest issue is political. How can you stand before the world and say you need to make more nuclear power plants, it's the future of energy. Then tell other countries (cough, Iran, cough) they shouldn't have it?

RE: questions...
By vortmax on 6/12/2007 3:05:31 PM , Rating: 2
Because (cough, Iran, cough) is really creating nuclear weapons to kill people with. Why else would a nation with enough oil within their borders to last many centuries push so hard to create nuclear plants for power? I'm sure they aren't just being proactive....

RE: questions...
By theapparition on 6/13/2007 6:55:17 AM , Rating: 2
And just how many power plants do you know that burn crude oil?

I don't disagree that the thought of an unstable country like Iran posessing nulear fuel is quite unsettling. There is no doubt that their ultimate goal is to enrich uranium enough for weapons grade material. However, that doesn't change my original post, which states that (IMO) the US isn't pushing nuclear energy at home, because it wants to prevent other countries from thinking nuclear is the way to go. And that is directly related to the potential proliferation of nuclear weapons.

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