Posted on 11/27/2006 6:03:25 AM PST by FLOutdoorsman
You may one day be able to recharge your laptop or mobile phone without having to plug it into the wall, says a US physicist.
But others say there are many hurdles before such transfer of energy means we can say goodbye to wires.
Assistant Professor Marin Soljacic, of Massachusetts Institute of Technology, will present his team's work at the American Institute of Physics forum in San Francisco this week.
Today's wireless transfer of energy, such as the transfer of light energy from the Sun for solar power or the transfer of microwaves from transmitters for communication, involve relatively low levels of energy.
But recharging devices like laptops requires a much higher level of energy. And if this was routinely zapped through the air it could 'fry' any living organisms that get in the way.
But Prof Soljacic says he has found a way of transmitting energy so that only the devices that it is recharging will pick it up, so it will not affect humans.
Instead of using traditional radiation, he wants to use the part of the electromagnetic field that is 'non-radiative'.
He says devices can be tuned to the frequency of this field and thus act as a sink for all the energy the transmitter gives out.
Prof Soljacic says this would prevent energy radiating out to areas it does not need to go to, providing an efficient and safe method of wireless energy transfer.
"The team calculates that an object the size of a laptop could be recharged within a few metres of the power source," he says. "Placing one source in each room could provide coverage throughout your home."
Prof Soljacic also thinks the technology could be used to power freely roaming robots in a factory. Finding a 'magic' frequency
But Australian physicists, yet to see the full details of Prof Soljacic's work, are sceptical of his claims.
They say the challenge is finding a 'magic' frequency that does not also affect living organisms and thus pose possible health risks.
"You would be reintroducing all the problems that we went through with mobile phones," says Dr Geoff Anstis of the University of Technology, Sydney, referring to the uncertainty surrounding any long-term health effects of using mobiles.
"And it wouldn't be until a couple of decades that you may be happy that there isn't a significant problem."
His colleague Professor Geoff Smith agrees and says there are also technical challenges to keeping the devices tuned with the transmitters, thus preventing the general release of stray energy.
"I think this is nice physics but there's a way to go before it would be possible," says Prof Smith.
He says any changes in the surrounding environment could "de-tune" the system and stop the safe and efficient transfer of power.
Electrical engineer Dr Trevor Bird of CSIRO's ICT Centre says attempts so far to develop wireless power transfer have not been very successful.
He agrees that safety and technical barriers to wireless power systems are huge and would like further details on Prof Soljacic's proposal.
Dr Bird also says that, depending on the frequency of the field, the antenna on the device being recharged may have to be very large.
Now thats funny. But, I still don't know about being anywhere near these puppies. They sound like lawsuit magnets.
All hell breaks loose when such electric fields start ruining sensitive equipment like HDD actuators and digital cameras, and any circuit with a wayward coil of wire to get energised ruinously by induced currents!
Warning: Even though these microwaves are about as harmful as the leakage from an ordinary microwave oven (not much), do not put computers, televisions, other sensitive electrical equipment, food, liquids, paper, glass, flammable substances, magnets, or living things in between the base and satellite units. Just in case.
Your comment reminds me of "Waldo" from the Robert A. Heinlein book "Waldo and Magic, Inc". It's one of Heinlein's novellas. Part of the story has to do with the problems from all the "stuff" being shot through people and what it does to them. It also has something called "deKalbs" (if I recall correctly) which are wireless energy devices.
I think Heinlein wrote "Waldo" in the 1940's.
Heinlien was, IMHO, one of the best science fiction writers ever. He's my personal favorite.
"He's using the non-electromagnetic part of the electromagnetic spectrum. :)"
Is that like using a football bat?
Will some physist out there explain untraditional, non-radiative radiation to me? Also how energy can be transmitted without being "radiated"?
Wow! Does that mean that they won't kill me by stopping or damaging my pacemaker.
bump from your alma mater:)
"Also how energy can be transmitted without being "radiated"?"
Carrier wave.
In other news; Tumors of the brain have shown a sharp increase in recent years. Medical experts have no explanation.
Broadcast power seems inherently terribly inefficient. Only a tiny portion of the power broadcast could be used. Most would radiate into space that contains no receiver.
Zot powered!
UNPLUGGED. Alternating current fed into a wire loop (blue) generates a field that induces currents in the coil (red, at left), creating a magnetic field that reaches a second coil (red) several meters away (at right), creating a local field that induces a current in the second loop (blue), lighting a bulb. -- Science
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