Wireless Electricity

Electricity is central to our entire way of life; virtually everything we use in the 21st century relies on it, from flicking the light switch in the morning to using the latest tablet computer. Yet the way it has been delivered has hardly changed in the past hundred years. We still face the sometimes arduous task of looking for the right lead or cable to plug into the last available socket, which just so happens to be in the most inconvenient place in the room. However the socket in the wall that we are so reliant on, may soon become a thing of the past, as our plugged in world is set to be transformed by the arrival of wireless electricity.

The idea of transmitting electricity without power cables is as old as the idea of electricity itself. Indeed, one of the founding fathers of electricity generation, Nikola Tesla, proposed the idea in the late 1800’s as a way of spreading electricity around the world. He even successfully demonstrated this by running lamps up to 25 miles from his power source. Sadly, the idea never took off commercially, as for one, it was actually cheaper at the time to build miles and miles of copper cables, rather than the aerials needed for Tesla’s idea!


Whilst long range wireless transmission has remained a long term aim, recent developments have meant that short range delivery systems, ideal for use in the home or workplace, have become efficient, as well as affordable. The basic physics behind wireless electricity only involves two coils of wire, and is as follows. The first coil has electric current passed through it, which causes a magnetic field to be generated. This magnetic field then generates an electric current in the second coil, which is a short distance away from the first, which can be used to charge your device. The main problem with this though, was that it was originally a very inefficient process when compared to wired transmission.


A recent breakthrough was made however, by MIT researchers in 2005. They demonstrated that by having the coils vibrate at the same resonant frequency, they could increase the efficiency to around 70%, even when the coils were separated by a few metres and no direct line of sight between them. In contrast, a PC cord has about 75% efficiency.


One reason in wireless electricity’s favour, is that it is an inherently much safer system, when compared to our current model. Due to the fact that all the coils would be covered and hidden away, the components can be much better protected. Containers could be made watertight, protected against explosion and corrosion would be less of a problem. There would also be no chance of an accidental electric shock from touching a live wire.


The uses for this technology are set to be widespread. Already mobiles phones from the likes of Samsung and HTC can be charged wirelessly, but imagine placing transmitter coils in people’s desks to recharge devices while they work. Or as a replacement for the millions of batteries we use and have to dispose of every year. Medical implants could be safely recharged through the skin, eliminating the chance for infection. Bigger projects need not be exempt either, for example South Korea is attempting to develop a way of wirelessly recharging electric buses and there are plans to embed the technology in the car parks of the future.


So as wireless electricity becomes part of our everyday life, it appears that the days of the dreaded red battery level could soon be at an end.


Toby Kingsman


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