NEW YORK – Volvo Bus Corp. launches its 7700 hybrid model that lowers fuel consumption up to 30%.

The 7700 costs more than a conventionally powered bus, but payback to operators in fuel savings is claimed to occur in five to seven years.

VBC uses its I-SAM hybrid technology in the vehicle that has a starter motor, generator and electronic controls in one unit.

VBC says the 7700 reduces carbon dioxide up to 30% and oxides of nitrogen and hydrocarbon emissions up to 40%-50% compared with a conventional diesel-powered bus.

The parallel hybrid system also will be used in trucks and construction equipment manufactured by Volvo Group. As volumes increase, costs will decline, VBC says.

I-SAM works with a diesel engine and an I-shift gearbox. There also is a lithium-ion battery pack that is charged during braking and by an electric motor/generator. The bus can run on either the electric motor or the diesel engine – or both in combination. A choice of a 5.0L and 9.0L engine is available

As with other hybrids, the internal-combustion engine is shut down when the bus is stopped at traffic lights.

“The bus starts moving driven by the electric motor,” says VBC President Hakan Karlsson. “When the bus reaches 15-20 mph (24-32 km/h), the diesel engine starts automatically.” The bus weighs only 220 lbs. (100 kg) more than a diesel model. The hybrid is said to offer better weight distribution and allows operators to carry seven more passengers.

All the hybrid components were developed by Volvo. Previously bus makers purchased hybrid components from suppliers, Karlsson says.

“Since we developed the components internally, we have been able to (fully) optimize the bus’ fuel consumption,” he says.

While limited customer deliveries will commence next year, Volvo promises mass production early in 2010.