London's Double Deck Buses Go Green

Among other things, London is very well known for its double-decker buses. The have been in operation for many years and thanks to improving technology, it looks like they will be around for many more. This confidence comes as a result of the delivery of the first hybrid version of the iconic bus, with more to follow.

The buses will be equipped with the newest BAE Systems' Diesel Electric drivetrain. This is the same platform that is currently being used in cities such as New York and San Francisco with great success. The system uses a generator that spools from the diesel engine and stores the energy in a pack of Lithium Ion batteries. Extra electricity is also recaptured via the traditional regenerative braking system. From there it goes to a larger electric motor that gets the bus moving.

The diesel motor is roughly half the size of the ones currently being used to power the buses, which is a huge improvement. A computerized system is used to monitor how much power is being pulled from the batteries and can redirect the energy being produced by the generator straight to the electric motor is the need arises. When under heavy acceleration, for example, the computer will recognize the high amount of draw from the batteries and send the power that is being generated straight to the ground, rather than going to the batteries first. Once the need for extra power is gone, the system will return to normal operation.

Another benefit of the system is that the diesel engine will never directly power the bus. The drivetrain has no mechanical transmission and therefore, maintenance will be less expensive and more importantly, less frequent. This first bus should be in use within a day or 2, and 16 more will be on the way as part of an evaluation period.

BAE has already installed the system on more than 1,500 buses across North America and estimates the system has saved an incredible 5 million gallons of diesel fuel since first being introduced.