Page last updated at 08:45 GMT, Wednesday, 14 April 2010 09:45 UK

Wireless electricity could be just months away

By Maryam Maruf
Digital Planet

Nikola Tesla
Nikola Tesla envisaged wireless electricity over 100 years ago

In 1905 the Serbian inventor Nikola Tesla built a huge 18-storey tower in Long Island.

His aim was to create the world's first power station that would transmit wireless electricity around the globe.

Unfortunately the dream was short-lived. His financiers, including JP Morgan, grew cautious and withdrew funding. The project was considered too audacious and ill-thought out, and was eventually abandoned.

The tower, torn down to pay Tesla's mounting debts, became his bold failure. But now, 100 years on, can his ambition be realised?

WiTricity, a US-based firm set up by physicists from the Massachusetts Institute of Technology (MIT), is one of a number of companies around the globe developing different models of powering up gadgets without using cables.

Inspired by Tesla's vision, WiTricity believes it can launch wirelessly-powered products within the year.

A wireless world

Wireless electricity is transmitted between a device and its power source via fitted metal coils, explained researcher Aristeidis Karalis.

Wardenclyffe tower, consructed by Nikola Tesla
Tesla's tower was built to transfer electricity without wires

"One coil is the source, the other is the device. The source generates a magnetic field which induces a current in the device. This is converted into the power the device wants to use."

The goal is to transmit electricity over mid-range distances - so electricity from a wall to the middle of a room.

The firm's president Eric Giler says its research is developing rapidly.

"Imagine your house. Look under the table and there's a coil. You see multiple devices working from a distance away. So you come home and your phone is in your purse - you don't have to think about where to put it."

However some say the technology is still far from perfect.

According to Menno Treffers from the Wireless Power Consortium, energy transfer becomes rapidly inefficient the further a device is moved from the source.

"You can make it work over a coil diameter, but what's the point in transmitting power from the wall to the TV - 20 to 30cm away - if you can't take it outside?"

Climate challenge

Eric Giler agrees that wireless power is not as efficient as using a cable, but the environmental difference it makes is considerable.

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"A wireless keyboard uses four batteries. We made about 40 billion of these in the world this year. Building one of those batteries is the same as driving three miles in your car.

"The greenhouse gas emissions are huge. But if you put a coil in the table and put the keyboard on the table - on it comes - without a battery."

The WiTricity physicists did look at Tesla's patents for their research, but for now their plans do not include global power transmission. Still, Eric Giler shares Tesla's expectations about the idea's potential.

"Imagine a pacemaker that never needs to be replaced or a car that starts charging as soon as it's parked. Five years from now it will seem obvious - it's only today it sounds futuristic."

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