No sooner have you moved off than you’re on the brakes again. That’s city traffic for you. Public buses brake even more often – at every bus stop. But this suits the MAN Lion’s City Hybrid just fine; it simply converts the braking energy into electricity. Through an intelligent interplay between diesel engine and electric motor, it saves up to 30% in fuel. As an added plus, the bus leaves the stop almost silently and with no exhaust fumes.
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Munich and Vienna are the first cities to put MAN’s hybrid buses into service. In the coming months, more will join them: Paris, Barcelona, Milan, several cities in the Netherlands and Hagen have all opted for the MAN Lion’s City Hybrid.
In the hybrid buses, an electric motor works in conjunction with a diesel engine. The electric motor is supplied with energy recovered from braking, which is then stored and used for acceleration. That’s why hybrid systems are of the greatest value in cities, where constantly alternating between braking and acceleration is typical.
In city traffic, hybrid buses can achieve multiple goals simultaneously: reducing energy consumption and noise levels along with lowering operating costs and decreasing exhaust emissions. As a result, not only is diesel consumption drastically reduced but the climate-damaging carbon dioxide emissions decrease to the same degree. That, in the age of the greenhouse effect, makes hybrid buses particularly environmentally-friendly.
MAN has been researching hybrid drive for almost 40 years, giving it a head start that has clearly paid off in the latest MAN Lion’s City Hybrid generation. With hybrid drive, MAN is taking an innovative route, using so-called ultracaps – highly efficient capacitors that can efficiently store braking energy for short periods and stand out from the crowd due to their particularly long life.
Energy storage isn’t the only feature that the MAN buses enjoy, however. They use an economic common rail diesel engine that meets the EEV (enhanced environmentally-friendly Vehicle) exhaust emission standard, which is currently the best one available. The diesel engine doesn’t drive the axle via the gearbox directly. Instead, a high-power generator feeds its output in turn into two electric motors. Both of these power packs are connected to the electrical storage system mounted on the roof – the ultracaps. The diesel engine only starts when the driver presses harder on the accelerator. Test trials have shown that the diesel engine remains switched off between 25% and 40% of the time during which the buses are in operation, depending on the route. This saves up to 30% fuel when compared with conventional engine systems – and with it up to 26 tons of greenhouse gas emissions (based on 60,000 km on the road).
All this makes the MAN Lion’s City Hybrid a particularly environmentally-friendly example of the use of groundbreaking technology – one of many from MAN.
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