Electric bus

An electric bus is a bus that is powered by electricity.

There are two main electric bus categories: autonomous and non-autonomous. Autonomous buses keep the energy stored within the vehicle, while non-autonomous buses maintain a continuous supply of electric energy from outside of the vehicle. Autonomous electric buses are majorly battery electric buses, in which the electric motor obtains energy from an on-board battery, although examples of other storage modes do exist, such as the gyrobus which uses flywheel energy storage. In non-autonomous buses electricity is supplied by contact with outside power sources. For example, overhead wires, as in the trolleybus, or with non-contact conductors on the ground, as seen in the Online Electric Vehicle.

 

Buses using a combination of internal combustion engines and electric propulsion are defined as hybrid electric buses or dual-mode buses, and are not covered in this article.

 

Future developments

Sinautec is in discussions with MIT's Schindall about developing ultracapacitors of higher energy density using vertically aligned carbon nanotube structures that give the devices more surface area for holding a charge. So far, they are able to get twice the energy density of an existing ultracapacitor, but they are trying to get about five times. This would create an ultracapacitor with one-quarter of the energy density of a lithium-ion battery.[13]

Future developments includes the use of inductive charging under the street, to avoid overhead wiring. A pad under each bus stop and at each stop light along the way would be used.