ELECTRIC POWER WITH NO WIRES IS IN THE FORESEEABLE FUTURE

Bill Brown who was technical director of a JPL Raytheon program between 1969 and 1975, beamed 30 kW over a distance of 1 mile at 84% efficiency. Hardly anyone paid attention to it as there was no interest. But in 2007 a  team from Massachusetts Institute of Technology demonstrated its feasibility. They called their invention "WiTricity". The MIT inventors believe it could change the way we use electricity and do away with the tangle of cables, plugs and chargers that clutter modern homes. It could also allow the use of laptops and mobile phones without batteries.

Scientists have known since the time of Nicola Tesla that it is possible to transfer an electrical current from one coil of wire to another without them touching. The phenomenon, called electromagnetic induction, is used in power transformers and electric motors around the world. However, the coils in motors and transformers have to be close for power to pass from one to another.

Attempting to transfer power over distances is possible. Using two coils of copper, the team transmitted power 7ft through the air to a light bulb, which lit up instantly. The scientists say the technique works only over distances of up to 9ft. However, they believe it could be used to charge up a battery within a few yards of the power source connected to a receiving coil. Placing one source in each room could provide enough power for an entire house. The receiver and transmitter would not have to be in view of each other. Professor Peter Fisher, another of the researchers, said: "As long as the laptop is in a room equipped with a source of wireless power, it would charge automatically without having to be plugged in. In fact, it would not even need a battery to operate inside such a room."

The researchers think there is little to worry about on safety grounds, saying that magnetic fields interact weakly with living organisms and are unlikely to have any serious side effects.