Just how much of an impact could a hybrid drive system make to the fuel consumption of a bus? Well it appears the Siemens series hybrid drive Elfa is making a big impact.
According to the company, it consumes one third less fuel than conventional buses because rather than powering an automatic transmission it drives a generator that uses power electronics to supply electricity to one or more drive motors.
As part of the Elfa system, the electric motors actually act as generators during braking and feed electricity back to the batteries. This power can be used to drive the vehicle meaning the bus can run on electricity only without producing emissions. The range meanwhile, is dependent on battery capacity and can vary from a few hundred metres to several kilometres.
Furthermore, Elfa also helps to reduce noise as the diesel engine doesn’t provide any acceleration and only operates at quiet and economical speeds. This means that fuel consumption falls by about one third.
A test fleet of the buses using the Elfa hybrid drive system are already being used in several cities worldwide including London. The technology is also being targeted at other commercial vehicles that make frequent stops such as garbage trucks and light delivery trucks.
