WIRELESS ENERGY?

Now they’ve got to start working on a wireless nationwide grid.

Wireless energy promise powers up; A clean-cut vision of a future freed from the rat's nest of cables needed to power today's electronic gadgets has come one step closer to reality
Jonathan Fildes, June 7, 2007 (BBC News)
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WHO
Massachusetts Institute of Technology (MIT) research team (Assistant Professor Marin Soljacic, Andre Kurs, Aristeidis Karalis, Robert Moffatt, John Joannopoulos and Peter Fisher); Professor Sir John Pendry, Imperial College London

WHAT
Researchers have successfully transmitted electricity wirelessly from a power supply to a 60 watt bulb 2 meters (7 feet) away. They call this WiTricity.

WHEN
Outlined 2006, proven 2007.

WHERE
Research published in the journal Science.

WHY
- The experiment: a transmitter w/60 cm (2 ft) diameter copper coils sent power 2 meters (7 feet) to an unconnected receiver which lit a 60 watt bulb attached to it with 40% efficiency. Wood, metal and electronic obstructions did not stop the bulb’s glow.

- The key to WiTricity is very low frequency electromagnetic wave “resonance” between the transmitter and receiver, which allows energy transfer via harmonious vibrations. The copper coils resonate at 10Mhz and "tails" of energy to flow between them. Low frequency electromagnetic waves 30m (100ft) long keep the field magnetic rather than electric and thereby prevents harm to humans crossing it. A “far field” (of 2 GHz such as a mobile phone) produce an electric field which is what powers a microwave.
- Physicist/engineer Nikola Tesla attempted a 29m wireless transfer at Wardenclyffe Tower in New York but failed. Others have worked with lasers, which require an uninterrupted interval.
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QUOTES
- Pendry: "There is nothing in this that would have prevented them inventing this 10 or even 20 years ago…But…In the last few years we have seen an exponential growth of mobile devices that need power. The power cable is the last wire to be cut in a wireless connection."
- Soljacic: "We had a strong faith in our theory but experiments are the ultimate test… These results are encouraging. The numbers are not far from where you would want for this to be useful…"
- Pendry: "The body really responds strongly to electric fields, which is why you can cook a chicken in a microwave…But it doesn't respond to magnetic fields. As far as we know the body has almost zero response to magnetic fields in terms of the amount of power it absorbs."
- Soljacic: "This was a rudimentary system that proves energy transfer is possible. You wouldn't use it to power your laptop. The goal now is to shrink the size…go over larger distances and improve the efficiencies…"