Wireless Electricity


Overview

Wireless electricity, also called "wireless power," is the transmission of electrical current through atmospheric channels rather than over physical wires, from an originator of said current to a receiver of this current. The receiver must be capable of receiving a signal from the originator, and then converting it into electricity. Wireless electricity is quite similar to wireless Internet access, in which a beacon (or access point, in wireless Internet parlance) sends out "invitations" (called frames) via the atmosphere to any wireless receivers that are within the beacon's proximity. And, like its "atmospheric Internet" cousin, wireless electricity is vulnerable to physical atmospheric phenomena that may serve as signal blockages.

The idea of wireless communication between devices originates with Serbian-turned-American citizen Nicola Tesla (considered to have been one of the greatest electrical engineers ever to have worked in the United States) in the latter part of the 19th century. This idea was further developed by later researchers. However, it was not until 2007 that scientists at MIT converted wireless electricity from a dream to a reality. They dubbed their creation "WiTricity," and debuted it to the world in a demonstration that powered a television and two cellular phones (one of which was manufactured by Apple, in order to prove that the scientists' creation was compatible with virtually any brand of device) via wireless power.

History of Tesla and Wireless Electricity

Nikola Tesla (10 July 1856 – 7 January 1943) was born in what is now known as Croatia, to an ethnically Serbian family. As a young man Tesla attended several universities, but withdrew from classes before completing a degree. Tesla was a brilliant young man, with a unique mental make up, which was both the basis of his genius and a great hindrance to his ability. Tesla suffered from spells of blinding white flashes, hallucinations and had several nervous breakdowns during his lifetime. However, his mind also produced vivid images of his ideas (possibly Synesthesia), detailed to the point that drafting or writing them down was unnecessary. After moving about Europe and collaborating on several early projects, Tesla came to New York City, the technological hub of the modern world. Once there, he would attempt to work with Thomas Edison, but the men’s ideas about electricity were divergent and a lifetime of competition began. The main point of contention was over alternating current vs. direct current. Tesla was focused on ac, while Edison spent a great deal of time trying to convince the public that the system was highly dangerous. Tesla’s ac system now dominates the electrical transmission market. In the field of wireless electrical transfer, Tesla again made great contributions. As part of a system for broadcasting radio over long distances, Tesla built the wardenclyffe tower. The tower did not succeed in its bid to transfer a radio signal across the Atlantic, but Tesla believed that his design could one day provide limitless wireless power to the whole of the world. The illustrations of his tower portray waves of lightning like energy radiating from the tower, which is a classic image of Tesla’s work. Today, many people are familiar with the concept of a tesla coil, and the imagery of that coil. It is the science fiction mainstay of Dr. Frankenstein’s laboratory and of the mad scientist generally. Tesla himself posed for dramatic photographs of himself with his coils blasting arcs of electricity around him, and it is these coils which became the backbone of modern systems of wireless electrical transfer. The coils react to and create resonant magnetic fields which, when near a coil which resonates at the same frequency, can facilitate the transfer of electrical current. Tesla experimented with this extensively, even demonstrating the illumination of an un wired light bulb. Today, Tesla’s name has been applied to many of the core principles which underpin the science of wireless electrical transfer.

MIT Developments

A few years ago, Marin Soljacic, an assistant professor of physics at MIT, was dragged out of bed by the insistent beeping of a cell phone. "This one didn't want to stop until you plugged it in for charging," says Soljacic. In his exhausted state, he wished the phone would just begin charging itself as soon as it was brought into the house.

So Soljacic started searching for ways to transmit power wirelessly. Instead of pursuing a long-distance scheme like Tesla's, he decided to look for midrange power transmission methods that could charge--or even power--portable devices such as cell phones, PDAs, and laptops. He considered using radio waves, which effectively send information through the air, but found that most of their energy would be lost in space. More-targeted methods like lasers require a clear line of sight-and could have harmful effects on anything in their way. So Soljacic sought a method that was both efficient--able to directly power receivers without dissipating energy to the surroundings--and safe.

He eventually landed on the phenomenon of resonant coupling, in which two objects tuned to the same frequency exchange energy strongly but interact only weakly with other objects. A classic example is a set of wine glasses, each filled to a different level so that it vibrates at a different sound frequency. If a singer hits a pitch that matches the frequency of one glass, the glass might absorb so much acoustic energy that it will shatter; the other glasses remain unaffected. Soljacic found magnetic resonance a promising means of electricity transfer because magnetic fields travel freely through air, yet have little effect on the environment or, at the appropriate frequencies, on living beings. Working with
MIT physics professors John Joannopoulos and Peter Fisher and three students, he devised a simple setup that wirelessly powered a 60-watt light bulb.

The researchers built two resonant copper coils and hung them from the ceiling, about two meters apart. When they plugged one coil into the wall, alternating current flowed through it, creating a magnetic field. The second coil, tuned to the same frequency and hooked to a light bulb, resonated with the magnetic field, generating an electric current that lit up the bulb-even with a thin wall between the coils.




How Wireless Electricity Works

To date, the most effective means of generating wireless electricity, as carried out by MIT, consists of 60-centimeter copper coils and a 10-megahertz magnetic field. This transfers power over a distance of two meters with about 50 percent efficiency. The team is looking at silver and other materials to decrease coil size and boost efficiency. "While ideally it would be nice to have efficiencies at 100 percent, realistically, 70 to 80 percent could be possible for a typical application," says Soljacic. Other means of recharging batteries without cords are emerging. Startups such as Powercast, Fulton Innovation, and WildCharge have begun marketing adapters and pads that allow consumers to wirelessly recharge cell phones, MP3 players, and other devices at home or, in some cases, in the car. Nevertheless, Soljacic's technique differs from these approaches in that it might one day enable devices to recharge automatically, without the use of pads, whenever they come within range of a wireless transmitter.

Applications

Wireless electricity, though still in its infancy, could potentially expand to the point of rendering traditional wirebound electricity virtually obsolete. If it were to expand to this degree, silver would likely be used in the coils that comprise the devices which power wireless electricity, thereby driving up the spot price for silver.

Wireless electricity will be available sooner than most people think. Hope are this new technology will be accessible to people like us for charging our cell phones within a year to year and a half. A wireless power mat, which is customizable for the various electric cars, has been created for the consumer to charge their electric car just by driving into their own garage. This application could also create a boos in the consumer purchase of electric cars, which could in turn generate additional revenue for the car industry with the ease of recharging an electric car.

The intention is to no longer rely on the use of power cords for electricity and eliminate the use of batteries all together. It is estimated that within five years this new technology will become the norm. The concept of allowing one power pad to send wireless electricity to multiple units is currently being developed. Image being able to eliminate the power cords in the bathroom as you get ready each day. One power pad would have the ability to be used to power your electric toothbrush, your blow-dryer while listening to your MP3 player that is docked into speakers.

Here are a couple of videos that show just how wireless electricity can be used.
http://www.ted.com/talks/eric_giler_demos_wireless_electricity.html
http://news.bbc.co.uk/2/hi/technology/8165928.stm


External Links


http://hackaday.com/2009/08/28/wireless-electricity/
http://web.mit.edu/newsoffice/2007/wireless-0607.html
http://www.fastcompany.com/magazine/132/brilliant.html
http://www.fastcompany.com/magazine/132/brilliant.html
http://www.cnn.com/2009/TECH/09/02/wireless.electricity/index.html
http://www.kitco.com/market/
http://blog.mapawatt.com/2009/09/02/wireless-electricity/

References

"MIT researchers demonstrate WiTricity.(Massachusetts Institute of Technology, wireless electricity)(Brief article)." Electronic Engineering Times 1479 (June 11, 2007): 66. General OneFile . Gale. Brevard County School Dist (not FEL). 17 Sept. 2009
< http://find.galegroup.com/gps/start.do?prodId=IPS >.

"MIT Scientists Demonstrate Advance in Wireless Electricity." GearLog (June 8, 2007): NA. General OneFile . Gale. Brevard County School Dist (not FEL). 17 Sept. 2009
< http://find.galegroup.com/gps/start.do?prodId=IPS >.

"MIT Researchers Transmit Wireless Electricity.(11:00-12:00 PM)(Massachusetts Institute of Technology)(Broadcast transcript)(Audio file)." Morning Edition (June 8, 2007): NA. General OneFile . Gale. Brevard County School Dist (not FEL). 17 Sept. 2009
<http://find.galegroup.com/gps/start.do?prodId=IPS >.

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