October 3, 2008 Public transportation is a good proving ground for hybrid vehicles, with examples like the Orion diesel-electric buses able to demonstrate the long-term advantages of improved fuel economy, and the efficiency of electric motors for stop-and-go driving. In addition to reducing the discharge of particles and nitrous oxides by 40-50% compared with a diesel bus, the Volvo 7700 Hybrid has 30% lower fuel consumption which the company estimates will allow bus operators to recoup the extra cost of the vehicle within seven years.
The Volvo 7700 Hybrid system is named I-SAM, and consists of a combined start motor, electric motor, generator, and an electronic control unit. The bus can be powered by the electric motor and diesel engine individually as well as simultaneously. Like many hybrid buses, the energy from braking is harnessed to charge the battery. While the diesel version of the Volvo 7700 uses a 9-liter engine, the 7700 Hybrid requires only a 5-liter engine.
All the hybrid components in the 7700 are developed by Volvo, allowing the company to build a more streamlined vehicle that weighs just 100 kg more than a its diesel-only counterpart. The hybrid technology will also be incorporated into trucks and construction equipment.
“Another major benefit with Volvo’s hybrid technology is that the diesel engine will be turned off at bus stops and traffic lights,” says Håkan Karlsson, President of Volvo Bus Corporation. “The bus starts moving driven by the electric motor and when the bus reaches 15-20 kph, the diesel engine starts up automatically.”
The first buses will be delivered next year, with mass production scheduled to commence in 2010.