Slashdot Mirror
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.)"
800 Watts over 5 meters, ...
(May I dream of wireless laptop power? I hate power cords.)
I think I'll pass on that. Don't really want that sort of power aimed directly at the boys.
I've seen more watts over more distance all my life.
http://www.nssl.noaa.gov/primer/lightning/ltg_damage.html
You just don't want to stand between the source and the destination...
May I dream of wireless laptop power? I hate power cords
Depends - do you want kids in future?
This is making my hair stand on end just thinking about this achievement.
Or I am a little too close.
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?
Yes, you can. But I have it already. It's called a battery.
The point wasn't that investment in infrastructure is a waste.
Wireless power transmission is wasteful. Between the inverse square law and eddy currents induced in everything remotely conductive between point A and point B, wireless power would lose a huge percentage of the useful energy generated.
"Prefiero morir de pie que vivir siempre arrodillado!"
You clearly do not know anything about Cyrillic. The 'H' you refer to is actually an 'n' and the backwards 'N' is actually a 'i' type sound. The 'C' is an 's'.
Plus, I along with many, many others would not like to have my reproductive organs anywhere near such a device.
Wait... did you just invoke Rule # 34?
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.
Wireless power is only suitable for everything that is portable. Portable electronics require chargeable batteries. Chargeable batteries are also a wasteful.
Chargeable batteries also generate heat, are harmful to the environment when disposed and can cause fires and serious injury to the point of death when they explode.
There is no point not to use wireless power.
Here be signatures
Look at the transfer efficiency: they're using a 3.6 kW transmitter to power a mere 775 watt load.
At distances beyond ten meters, even steam engines have better efficiency. When you consider the best efficiency they had was 38%, and most power plants are about 33% efficient, they need a considerable improvement for this to be practical. By way of comparison, the typical cable delivery system is about 90% efficient and doesn't have the somewhat undesirable property of setting nearby electronics on fire.
The society for a thought-free internet welcomes you.
Wasteful, but extremely useful for certain purposes. Most electric toothbrushes are a perfect example, if solved slightly differently - you don't want unsealed electrical points on a device that gets wet in normal use. Any other sealed device that needs charging could possibly benefit from this.
So you have a wireless power transmitter in the bathroom integrated in the normal electrical outlet. What powered bathroom devices could we power this way? Tooth brushes, razors, vanity mirrors, shower radios, all sorts of kids toys, and that adult bath toy the battery powered vibrator.
Cell phones, cordless phones, and remotes might also be good to charge via this method as well.
Heck, making AA, AAA, C, and D sized "batteries" that just receives "wireless power" from the "wireless transmitter" would let you power some of those kids toys for as long as you have the wireless transmitter plugged in. That would be much better than running down the batteries really quickly and then either having to recharge or get new ones.
We finally have a method of male contraception that doesn't involve surgery, abstinence, or a woman's permission! I'll take that laptop, son. I'm too old for more kids!
We already had one, it's called slashdot.
The MIT group is not proposing to use omnidirectional (or directional) radiative energy transfer, which indeed would radiate most of the energy into the environment, and only a small fraction into the receiver, and even that could be eliminated if something (e.g. a person) walks between the source and receiver.
They are proposing non-radiative resonant energy transfer, in which both the source and receiver are resonant oscillators at a particular frequency coupled via the near field (non radiatively), and hence preferentially transfer energy compared to anything else that is not resonant (with a long lifetime) at the same frequency. Furthermore, they are using resonators that only couple through their magnetic fields (the electric fields are largely within capacitors inside the device), which further reduces absorption of energy by the environment (because most materials are non-magnetic, energy dissipation is largely via ohmic heating, i.e. by the electric fields). Because of this, almost all of the losses take the form of resistive heating in the devices themselves; only a miniscule fraction is dissipated in the surrounding environment (e.g. a person).
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).
If a thing is not diminished by being shared, it is not rightly owned if it is only owned & not shared. S. Augustine
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.
I was talking about the MIT group (who explicitly discuss the differences between what they are doing and what Tesla considered), not the group in the article here. And you're right that Tesla also looked at non-radiative schemes for very short distances, e.g. Tesla coils, but at the time of Tesla most of the interest was in long-range power delivery (which never worked out because of the problems with radiative transfer, and in any case such schemes were supplanted by the wired electrical grid).
Tesla coils involve large electric fields between the source and receiver device, and so (a) are quite different from the magnetically-coupled resonators the MIT group proposes and (b) are impractical for the short-distance power-delivery applications considered here because they can dissipate too much energy into the environment.
If a thing is not diminished by being shared, it is not rightly owned if it is only owned & not shared. S. Augustine