A significant reason for the fuel savings being so large as up to 30% in Volvo’s hybrid bus is that all hybrid components are developed by Volvo.

“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,” relates Maurice Brown. “Since we developed the components internally, we have been able to integrate the new technology with both the engine’s and the bus’s other energy usage and thereby optimize the bus’s fuel consumption fully. At the same time we could ensure very high reliability.”

Electric-powered doors

The electrification of many of the support systems also contributes to the substantial fuel savings. Instead of loading the diesel engine, the system is powered by recovered braking energy. The door-opening function is powered electrically as well as the air compressor, the air-conditioning and power steering.

Volvo Bus calculates that the new hybrid bus has the same lifetime as the comparable diesel bus. Maintenance of the bus is carried out in the same manner as with the diesel buses and in certain cases the maintenance requirement is even less.“The electric motor/generator is so powerful that that it will often stop the bus itself. Wear on the wheel brakes will decline, resulting, for example, in longer intervals between replacement of the brake linings,” says Maurice Brown.

Carry more passengers

With many of today’s hybrid solutions, the bus becomes substantially heavier and, consequently, can carry fewer passengers. It is the opposite with the Volvo 7700 Hybrid. The bus weights only 100 kilograms more than a diesel version. As a result of the batteries being placed on the roof forward of the front axle, the bus gains a weight distribution whereby it can carry up to seven more passengers than its diesel counterpart.

Volvo 7700 Hybrid - Inside View