Researchers at Massachusetts Institute of Technology (MIT) have outlined a system to transmit power wirelessly to electronic devices in the home. The project is being developed by Assistant Professor Marin Soljacic from the Department of Physics and Research Laboratory of Electronics, who is collaborating with graduate student Aristeidis Karalis and Professor John Joannopoulos. The team has not yet built a test system, but their plan is based around physics that have been around since the 19th century, and computer simulations of the system indicate that it would work.

Other wireless power systems include Nikola Tesla's long-range wireless energy experiment, the Wardenclyffe Tower (which ended when he ran out of funding); directional energy transfer such as lasers; and induction-based energy transfer systems such as the charger for electric toothbrushes. MIT's team hopes to improve upon these existing systems with their own solution, a type of longer-range induction, based on the resonance of an electromagnetic field. Outside of smaller applications, such as charging your toothbrush, this is something typically used in radio antennas. However, a radio antenna is inefficient for transferring energy because it broadcasts radio waves in all directions regardless of other devices—a waste of energy if used for powering devices wirelessly.

To remedy this, the researchers designed an emitter to make use of long-lived resonances with "non-radiative" objects. This keeps the energy close to the antenna until another object with a similar resonance comes within range—no broadcasting into space is necessary. The two resonating objects can sync their frequencies easily, which would then cause energy to "tunnel from one object to another," Professor Soljacic told the BBC. When not transferring energy to another device, "most" unused energy simply gets reabsorbed into the emitter.

The MIT team's system is designed for use in a home or office, as it can transfer energy to other devices within 3 to 5 meters of the emitter. However, the antenna's range doesn't have to be limited to just that, says Professor Soljacic. "This would work in a room let's say but you could adapt it to work in a factory," he said, adding that it could also be scaled down to be used on a microscopic level as well because the range would be determined by the size of the emitter.

The applications for such a system are obvious: laptops, cell phones, and other battery-powered devices that need constant recharging would be able to recharge themselves. Soljacic theorizes that one emitter in every room of the house would be enough to power most household devices in your home. There are other, perhaps less obvious uses for the emitter though. Soljacic is also apparently the proud owner of a Roomba (the vacuuming robot), which he feels would be able to make good use of such a powering mechanism. "It does a fantastic job but, after it cleans one or two rooms, the battery dies," he said, adding that more sophisticated, freely-roaming robots in, say, a factory pavilion could also recharge themselves wirelessly while within range of an emitter. And we thought that we'd be able to stop the robots when they ran out of power...