1 July 2007

Tesla’s wireless electricity concept rises again

In the early 20th century, the electricity pioneer Nicola Tesla discarded the idea of wireless electricity transmission because it did not work over long distances. 

Automation engineers working with wireless robots without batteries do not care. There are plenty of other applications for such a concept too.

The Wall Street Journal reported a team of researchers at Massachusetts Institute of Technology has demonstrated wireless transmission of electric power by magnetically coupled resonators. 

They dubbed their technology “WiTricity” for wireless electricity.

Marin Soljacic, the physics professor who led the team, said the technology is ready and “now is a good time to start thinking about commercializing it.” He said while further development is necessary to improve efficiency, he thinks commercial products could be on sale in a few years. 

MIT will handle licensing of the technology.

Soljacic said over short distances, wireless transmission appears to be about 80% as efficient as wired transmission. The resonant devices interact with each other without interfering with either biological processes or other electrical devices. 

While wireless transmission of electricity over radio waves is well known, it is very inefficient because most of the power scatters in directions other than the device that needs the power. 

Soljacic’s team theorized that two copper coils tuned to resonate in identical mag-netic fields would assure the power would go to the desired destination.  

Resonant objects interact only with objects of the same resonance. For example, if an opera singer holds a high note in a room of wine glasses filled to different levels, only one glass, which resonates with that note, is likely to  shatter.

The researchers’ technology uses a copper coil attached to a power outlet to transmit electromagnetic waves at set frequencies. A receiving coil attached to the base of the light bulb, can receive the power for a distance up to seven feet, making it appropriate for rooms.

One application would be to include such coils in battery-powered devices such as laptop computers to make automated, wireless recharging possible.

The technology does not work over long distances, but it functions well within average sized rooms in homes. That might make it possible to build wireless devices that do not require batteries. Many devices such as robot vacuum cleaners and laptop computers run on less energy than a light bulb.