The Charge of the Ultracapacitors

Nanotechnology takes energy storage beyond batteries. A bank of ultracapacitors releases a burst of energy to help a crane heave its load aloft; they then capture energy released during the descent to recharge. Buses, trams, and garbage trucks powered by the devices all run for short stretches before stopping, and it´s during braking that the ultracapacitors can partially recharge themselves from the energy that´s normally wasted, giving the vehicles much of the juice they need to get to their next destinations.