MIT researchers have successfully tested an experimental system to deliver power to all manner of electronic devices wirelessly.

Following through on a paper presented last fall, MIT researchers have successfully sent a beam of electricity, like a radio wave, between two points, using the broadcast to power a 60-watt light bulb.

The team lit up the bulb from a power source seven feet away, with no physical connection between the two points. The project has been dubbed WiTricity, for wireless electricity.

The experiment demonstrates the concepts the research team outlined in a paper last autumn. The power transfer has a limited range.

"Still, for laptop-sized coils, power levels more than sufficient to run a laptop can be transferred over room-sized distances nearly omni-directionally and efficiently - even when objects completely obstruct the line-of-sight between the two coils," the researchers said in a statement.

A WiTricity laptop in a room with a transmitter unit would charge automatically, without having to be plugged in, and would run without having a battery.

The technique is somewhat similar to magnetic induction, used in power transformers that have coils very close to each other to transmit power between them. But as the distance increases, these nonresonant coils become vastly less efficient, according to the researchers.

More details of the experiment are in the June 7 online edition (access to full paper requires paid subscription or per-article fee) of ScienceExpress, the pre-publication venue for Science Magazine.
The project team includes MIT professors and graduate students: Professor Peter Fisher, John Joannopoulos, Aristeidis Karalis, Andre Kurs, Robert Moffatt, and Professor Marin Soljacic. The research has been funded by the Army Research Office (via MIT's Institute for Soldier Nanotechnology), the National Science Foundation and the Department of Energy.

Reports of the experiment have triggered a storm of contemptuous blogosphere comments from those who argue that electrical genius Nikolai Tesla created a much more powerful power transmitter over a 100 years ago, in his famous and famously dramatic experiments in May 1899 in Colorado Springs, Colo.

Among other things, Tesla, who worked for Thomas Edison at one point, was the inventor of the Tesla coil, a transformer that uses a technique called the spark gap to transform a low-voltage, low-frequency current into a high-voltage, high-frequency current. Large Tesla coils in action often can be seen in museum displays, such as the Theater of Electricity.

In the Colorado experiments, Tesla seems to have tried to generate and transmit over distances. The 2006 movie, "The Prestige," used Tesla (played by David Bowie) and the Colorado laboratory, as a key element in its plot.

But a 2000 PBS documentary, "Tesla: Master of Lightning," directed and co-written by Robert Uth, concluded it was unclear what Tesla had actually achieved in Colorado Springs.

"A great deal of mystery still surrounds Tesla's work at Colorado Springs," states an account on the website. "It is not clear from his notes or his comments exactly how he intended to transmit wireless power. But it is clear that he returned back to New York City fully convinced that he could accomplish it."

Over 100 years later, Tesla's scientific descendents have done so.