Wireless power transfer offers lots of conveniences to mobile device users. When your device is running out of battery, you can simply hook up to a remote power station wirelessly, which allows you not to be bound by tangling power cable.
Sony is currently working on wireless power transfer technology, which has achieved pretty promising result that can transfer up to 60 watt of electrical energy over half a meter distance. The efficiency falls around 80%, 60% with rectifier. Besides portable gadgets, home entertainment system such totally wireless HDTV is possible in the near future.
Wireless transmission of audio and video signals is currently available from your set-top-box or AV unit to the TV. Plus the wireless power transmission, the TV will become a fully wireless TV.
The wireless power transfer makes use of the concept of magnetic resonance, which electromagnetic energy is only transferred to the recipient devices that are in the identifal resonance frequencies as the energy source.
Currently the wireless power distance is only 50 cm, but Sony has also developed a passive extender that allows the transfer distance to be extended from 50cm to 80cm with no degradation in efficiency.