U.S. researchers have designed a wireless charging system for electric vehiclesthey say could ultimately lead to all-electric highways capable of charging cars and trucks as they drive down the road. The system, developed by a team at Stanford University, uses magnetic fields to transmit large electric currents between metal coils embedded a few feet apart under the surface of the road. Based on magnetic resonance coupling technology, the process involves one coil that is connected to an electric current, which generates a magnetic field that causes the second coil to resonate, triggering an invisible transfer of electrical energy. The developers say there is a potential to create a wireless network across entire highway systems, a step that would drastically increase the range of electric vehicles since they would theoretically never have to plug into a charging station. “You could actually have more energy stored in your battery at the end of your trip than you started with,” said Richard Sassoon, managing director of the Stanford Global Climate and Energy Project (GCEP) and co-author of the study published in the journal Applied Physics Letters.