Scientists have known for nearly two centuries how to transmit electricity without wires, and the phenomenon has been demonstrated several times before. But it wasn't until the rise of personal electronic devices that the demand for wireless power materialized. In the past few years, at least three companies have debuted prototypes of wireless power devices, though their distance range is relatively limited [see "Power Brokers," next page]. Then last year, a team at the Massachusetts Institute of Technology set the stage for wireless power that works from across a room.

The world´s first commercial wave farm, located off the coast of Portugal, will use machines called Pelamis Wave Energy Converters to turn the motion of the ocean into electricity. Click here to see how one of these machines works.