Generation game

A new generator system for hybrid electric buses could improve city centre air quality while helping the government to meet its targets for reducing carbon emissions. The challenge has been accepted by a team at Newcastle University, with electric-vehicle systems specialist Hil Technologies.

They aim to boost the efficiency of series hybrids, in which an engine and a generator unit is used to produce electricity and an electric traction motor alone powers the wheels. The drawback is there are several power conversions: combusting the fuel in the engine to drive the generator, which produces electricity to be stored in batteries before powering the motors to mechanically turn the wheels.

This has too many losses for series hybrid systems in cars, which is why the Toyota Prius and others are parallel hybrids in which both the engine and motor can turn the wheels. 'The wheel-to-wheel analysis of series hybrids shows they can be good for vehicles where you know the driving cycle,' said Dr Volker Pickert at