Pushing 800W of Wireless Power at 5 Meters

Joe Decker writes "The Nevada Lightning Laboratory has experimented with Nicola Tesla's methods of wireless power transmission to push 800 Watts over 5 meters, besting MITs mark of 60W over 2 meters last year. (May I dream of wireless laptop power? I hate power cords.)"

more interesting: Self-Powered 'Automatons.'

[prgrmr]

This unit collects energy from the ambient electric fields using an on-board 'reverse Tesla Coil,' which in turn charges a large, on-board capacitor bank. The capacitors then drive a DC motor connected to one of the wheels, providing motive effort for the machine.

I wonder how much ambient electricity can be captured in a large city as an alternate means of powering an electric car?

Re:hmmmm

[gnick]

Yes. Yes we do - Or at least we could with some sensible investments. Our (the US) power transmission infrastructure needs an overhaul - I'd rather spend tax $$ on that than several of the things they're going toward now. But, if we adopted sensible energy policies, there's no good reason that we can't have electricity to just throw away.

I'll agree that throwing $$ away in one place is no justification for throwing it away in another, but a better power (and data?) transmission system nationwide with upgraded power production (nuclear, wind, cleaner coal, etc) IMO is not remotely a waste.

Re:hmmmm

[Moryath]

If you want to conserve power, wireless is not the way to go - it is always going to be inherently lossy, because (a) air will never be an ideal medium (not that current wiring is, but we're getting better and better with low-resistance conductor material) and (b) if you have to distribute it from an antenna, you necessarily waste a vast amount of your energy that will not be picked up by the receiving antenna.

The only way to get around (b) is to have a perfectly tuned, ideal directional antenna and a perfectly tuned, ideal receiving antenna pointed exactly at each other for the entire time you are functioning. Any deviation from these will result in power loss.

You have your choice: energy efficiency OR omnidirectional transmission. The two are mutually exclusive. Plus, I along with many, many others would not like to have my reproductive organs anywhere near such a device.

Re:Lets think about this for a while

[jonnythan]

Hate to break it to you, but you're bathed in much more than a few millitwatts of EM every second of every day.

Think about the 50,000 watt AM antenna you drive by on the way to work. The hundreds of multiple-watt in-use cell phones you walk by every day. The Wi-Fi in your office and your local Starbucks.

You're bathed in all sorts of EM radiation all the time. You can't get away from it.

Wireless power + laptop == bad

[Taxilian]

Another problem that any physics professor will tell you (after pointing out that "the boys" are not going to be in any more danger from that than they are from your cell phone, since neither would be likely to operate at a frequency at which the human body is resonant) is that any bit of metal can act as an antenna. All it takes is to have one piece of wire inside your laptop that happens to be the right resonant frequency for the power that is being transmitted and ZAP! I for one would not want my sensitive electronics that can be fried by static electricity in the wrong place to be anywhere near something like that.

Re:more interesting: Self-Powered 'Automatons.'

[smellsofbikes]

People who live near (under) high-voltage cross-country power lines can tell you about harvesting electric fields. People have been known to run wires through their attics, parallel to adjacent high-voltage lines, and run lights off them. It's considered power theft, which I think is a shame, because it helps make the rest of the house a little more liveable, with fewer shocks from touching light switches or heating vents.
In Moab, Utah, there's a popular bike trail with the parking area right under a major power line. There are audible snapping and popping sounds coming from bikes on car-top racks. I keep meaning to wire up a capacitor bank and see how far it charges up while I'm out on a ride, but I haven't had time yet to build that.

Re:Used for good?

[Anonymous Coward]

You can use two laser beams to ionize the air and conduct electricity to some given target. In short, wireless Tasers. They're called electrolasers [wikipedia.org].

Tesla was way ahead of his time...

[Anonymous Coward]

Tesla's original idea was to use the Earth's resonant frequencies to wirelessly transmit power from space based transmitters (e.g. PV cells) to terrestrial electrical devices.

  Inexpensive wireless power would be available for everyone -- with the initial development, implementation, and maintenance costs possibly covered by some form of world tax.

Re:hmmmm

[khallow]

Wireless power transmission is wasteful.

I disagree. We have found ways to transmit power efficiently, for example, parabolic antennas and phase arrays. We could even design the systems (assuming they have enough antenna placed in the space and the wavelength is small enough) so that the transmissions mostly avoid certain places (eg, you, the interior of your TV set, etc). Having said that, I don't see a compelling reason to have substantial power provided via wireless in a personal space. If the system is hacked, it can cause considerable property damage and bodily harm.

Re:more interesting: Self-Powered 'Automatons.'

[KnightElite]

Apparently a farmer near the town of Estevan, Saskatchewan, got in trouble with the law for doing something like this. He was only a few miles from the powerplant and built a shed with a large transformer in it underneath the high voltage lines and pulled power from it to run parts of his farm. From what I heard, he did this for several years before being caught.

Re:Lets think about this for a while

[Anonymous Coward]

The sun has the ability to cause DNA mutation... Remember that thing called Skin cancer?

The sun's power is also spread over a larger surface and a very large quantity is simple reflected (remember that thing called light?) or dissipated through heat.

UV however can go through the skin... causing cancer. Guess what portion of the sun's power reaching the surface of earth is UV, then put it on the surface required for them to transfer 800W wirelessly. I'm sure you wouldnt step into that beam afterward...

Re:Not great for everyone

[Hafnia]

When you bring ferromagnetic metal into an MRI the really important issue is mass. Even a 1.5T won't pull very hard on a small mass object. But it will throw a pallet lifter around and hold so strongly that it's almost impossible to get loose. You will have to ramp down the magnet which will weaken the strength of the magnet(Bad , but not fatal).If there is a person in the scanner they will push the quench button - this is much worse for the magnet and very expensive since all the helium boils off and has to be replaced. And helium is very expensive ! But anyway .... i've been near 1.5T with an ordinary screwdriver and it's very strong - but not impossible to hold - i was not in the isocenter though, and i'm not certain i would be able to keep holding it there. But small grains of magnetic material , like in a tattoo is generally not an issue.

Re:more interesting: Self-Powered 'Automatons.'

[schweini]

The Mythbusters busted that one [howstuffworks.com]

Re:it would help if you understood the physics her

[srmalloy]

Of course, this being Slashdot, it's not surprising that most posters never RTFAed and post nonsense "it's just like an inductive transformer" (nope, those don't use resonance) or "it's just like an antenna" (nope, that is radiative transfer) or "Tesla looked at this a century ago" (nope, people like Tesla were concerned with power transfer over long distances, which necessitates radiative mechanisms and hence low efficiency).

It's a pity that your handwave of the "Tesla looked at this a century ago" opinion falls so flat by proving that you, yourself, did not RTFA, or you would have seen the third paragraph of the article, which states "Intriguing as this might be, we have no plans to pursue intellectual property for this discovery. The concept of using resonant coils to wirelessly couple power was patented by Nikola Tesla over 100 years ago." Shooting your argument in the foot by demonstrating that you are a member of the population you rail against does little for your credibility.