Sept. 25, 2008 - Volvo is marketing what it calls the "first commercially viable hybrid bus," promising bus operators a five- to seven-year payback in reduced fuel costs.

The company claims that its new Volvo 7700, which consumes 30% less fuel than its diesel counterpart, is more affordable than traditional hybrid diesel vehicles because all hybrid components are developed in-house.

"A common approach earlier was that bus manufacturers purchased hybrid components externally and attempted to adapt them to their own bus, but this is difficult," says Håkan Karlsson. "Since we developed the components internally, we have been able to optimize the bus’s fuel consumption fully. At the same time we could ensure very high reliability."

Volvo’s hybrid technology, known as I-SAM, has a lithium-ion battery which is charged during braking, and then provides energy to the electric motor for drive power. As a parallel hybrid, the bus can be powered by the electric motor or the diesel engine independently and by both engines simultaneously. As a result, the bus could be equipped with a smaller, 5-liter diesel engine compared with the 9-liter engine in the diesel version of the Volvo 7700.

And because parts do not need to be retrofitted on to a traditional bus, additional passenger space is gained. According to the company, the Volvo 7700 Hybrid weighs only 100 kilograms more than a diesel version. As a result of better weight distribution, it can carry up to seven more passengers than its diesel counterpart.

Companies are recognizing the benefits of investing in hybrid vehicles as fuel prices rise. Cable operator Cox Communications, for exaple, recently announced the expansion of its hybrid service truck fleet.

Volvo says it will deliver its first hybrid buses to customers during 2009, with mass production beginning in early 2010.