Wireless Electricity: Finally A Reality?

Fri, Jul 24, 2009

Applications, Technology

Wireless Electricity: Finally A Reality?

The BBC reported today on a system that can deliver power to electrical and electronic devices at significant distances away from the source, without the need for wires or cables.  Eric Giler from Witricity demonstrated the use of the system to charge cell phones and other devices during the TED Global event in Oxford, UK.  Mr. Giler said that “[t]here is something like 40 billion disposable batteries built every year for power that, generally speaking, is used within a few inches or feet of where there is very inexpensive power”.

The system consists of two coils, and uses a form of magnetic induction, but the key to the energy transfer is “resonance”, where the efficiency of the transfer of energy is much greater.  One coil is plugged into the mains and the other is connected or even embedded into the item to be charged. When the first coil is switched on, a magnetic field is produced which causes a resonant field  in the second coil.  This in turn causes a voltage to build up and this can then be used to charge the gadget.

According to the Witricity Web site, “these proprietary source and device designs and the electronic systems that control them support efficient energy transfer over distances that are many times the size of the sources/devices themselves”.  Furthermore, the technology exploits the “near field” during transmission.  At distances of less than one wavelength of the electromagnetic wave being transmitted, away from the transmitter, the near field is almost entirely magnetic, much safer than the potentially dangerous mix of electrical and magnetic field that manifests in the “far field” – more than one wavelength from the transmitter.  The frequencies used in the Witricity device produce wavelengths of approximately 30 m (100 feet), which gives us an idea of the effective range in which the device might operate.

Of course, as the article points out, this isn’t the first time that scientists and engineers have tried to transmit energy in this manner.  The famous Nikola Tesla is well known for his experiments in the transmission of electrical power, wirelessly.  More recently companies such as Intel have also been experimenting with this type of technology.

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- who has written 67 posts on Terra Magnetica.

Gareth is a Founding Principal at Technology Metals Research, LLC. He has expertise in a variety of magnetic materials, devices and applications, and their associated trends and challenges, particularly for renewable energy production. For more information check out his biography page. Don't forget to check out Terra Magnetica at Twitter too.

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