Physics promises wireless power

The tangle of cables and plugs needed to recharge today's electronic gadgets could soon be a thing of the past. US researchers have outlined a relatively simple system that could deliver power to devices such as laptop computers or MP3 players without wires.

The concept exploits century-old physics and could work over distances of many metres, the researchers said.

Although the team has not built and tested a system, computer models and mathematics suggest it will work. ... The answer the team came up with was "resonance", a phenomenon that causes an object to vibrate when energy of a certain frequency is applied. ... The team from MIT is not the first group to suggest wireless energy transfer.

Nineteenth-century physicist and engineer Nikola Tesla experimented with long-range wireless energy transfer, but his most ambitious attempt - the 29m high aerial known as Wardenclyffe Tower, in New York - failed when he ran out of money.

HOW WIRELESS POWER COULD WORK?

1) Power from mains to antenna, which is made of copper

2) Antenna resonates at a frequency of 6.4MHz, emitting electromagnetic waves

3) 'Tails' of energy from antenna 'tunnel' up to 5m (16.4ft)

4) Electricity picked up by laptop's antenna, which must also be resonating at 6.4MHz. Energy used to re-charge device

5) Energy not transferred to laptop re-absorbed by source antenna. People/other objects not affected as not resonating at 6.4MHz

- bbc

I've heard that the reason Tesla's wireless power idea was suppressed is that power companies could not figure out a way to get paid using that model.