Way back in 1904 Nikola Tesla, the inventor of alternating current, had proposed an elaborate system for electricity transmission without wires. More than a century down the lane we are now hopeful of finally realizing that dream with energy transmission wirelessly becoming a possibility. Wireless power had always been present but never feasible enough to be implemented.

Since the last couple of decades the number of household devices has been growing steadily from mobile phones to digital cameras to vacuum cleaners. Each one the appliances came with its own bundle of wires. This has led to a tangled mess of wires and the fact that each of the devices had separate connectors didn’t help. This year’s CES has thrown up new technologies which promise on transmitting wireless power over short distances.

Small range wireless power is based on the principle of induction. Demonstrated originally by Faraday, induction is the creation of an electric current due to changes in the magnetic field and vice versa. Induction is already very widely used in retail outlets where it is employed in the form of tags that detect theft. The same technology has now been harnessed to power digital devices such as mobile phones. The form of electromagnetic induction used is called resonant coupling. The power source has a coil which induces an electromagnetic current in the coil of the coupled device. Tight coupling of the device and source also factors the orientation, shape and distance of the device. Devices can also be loosely coupled to increase the number of devices for a single source but this figures a drop in the efficiency. Loosely coupled induction chargers are already available in the market in the form of mats on which the device can be placed for it to be charged.

Another form of wireless power for long range transmission has been proposed by Powercast. Powercast has come up with a new concept of trickle charge. Power is transmitted over a very wide area by devices called powercaster transmitters in the form of radio waves. A module called the powerharvester receiver harvests the electrical power from the radio waves. This system of wireless power can only give small amounts of current and hence the name trickle charge. The low capacity of the system renders it useless for use in devices which need fast recharging like mobile phones. The idea though can be put to a different use. Trickle charge can be used to power up small scale devices over a large area. For example a zoo could have all its animals tracked by GPS locaters which are powered centrally.

Wireless power has many benefits apart from the obvious comfort. The lack of need for wires and batteries is a boon for the environment. RFID tags can be powered over a wide area which decreases maintenance. Widespread power transmission though is sure a long time away.