The introduction of hybrid buses forms a major part of Arriva’s ongoing commitment to green energy. The hybrid vehicle is one that takes its power from more than one source, eg a diesel engine and an electric motor. What makes these buses different is that both units can work independently or together.
When the bus accelerates away from a bus stop, the electric motor works alone and uses the stored energy in the battery to power the bus. During this time, the diesel engine is not utilised – saving fuel, removing emissions and reducing noise pollution.
hybrid02Only when the bus reaches speeds of approximately 10mph will the small diesel engine start, and in that instance, it will work in conjunction with the electric motor to power the vehicle, giving the battery an opportunity to recharge during braking.
– See more at: https://www.arrivabus.co.uk/partners-container-page/partners-home/environment/hybrid-buses/#sthash.w5xG4MqL.dpuf