Unwired Energy

Recharging your laptop computer or your cell phone might one day be done the same convenient way many people now surf the Web---wirelessly. At this week's AIP Industrial Physics Forum, in San Francisco, Marin Soljacic (MIT) spoke about how energy could be transferred wirelessly by the phenomenon of induction, just as coils inside power transformers transmit electric currents to each other without touching. The idea of wireless energy transfer is not new. Nikola Tesla was working on the idea more than a century ago but failed to develop a practical method.

In the new MIT scheme, a power transmitter would fill the space around itself with a non-radiative electromagnetic field -- meaning that its energy would not ripple away as electromagnetic waves. Energy would only be picked up by appliances specially designed to resonate with the field; most of the energy not picked up by a receiver would be reabsorbed by the emitter.

Contrary to more traditional, radiative means of energy transmission such as microwaves, it would not require a direct line of sight. It would be innocuous to people exposed to it. With designs proposed by Soljacic in a paper with Aristeidis Karalis and John Joannopoulos, an object the size of a laptop could be recharged within a few meters of the power source. Soljacic (soljacic@mit.edu) and his MIT colleagues are now working on demonstrating the technology in practice.

Contact Marin Soljačić
soljacic@mit.edu
Tel: 617-253-2467