No More Power Cords: Wireless Energy is Here
The tinfoil hat brigade has something new to worry about: WiTricity, or wireless transfer of electricity from source to device without a cord. The dust bunnies will have nowhere to hide when the mess of wires under the desk is banished, replaced by a resonating receiver. Scientists have been playing with this for a while; 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. Now researchers have lit a 60W lightbulb from a distance of seven feet.
According to the BBC, The new system The system exploits "resonance", a phenomenon that causes an object to vibrate when energy of a certain frequency is applied. When two objects have the same resonance they exchange energy strongly without having an effect on other surrounding objects. Here they use extremely low frequency , thirty meter long electromagnetic waves, which are said to be harmless to humans. "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."
Because of the length of the wave the antennas are really big, and so far the efficiency is only about 40% so a lot of energy is being wasted. But oh, I look forward to losing those power bars and wires...::BBC
Update: Linton at Hugg points us to this great video on Tesla
and to Engadget