Chiltern Railways, which operates services out of Marylebone station, has started testing a train fitted with a special sort of Rolls Royce engine.

The Chiltern train has been fitted with a Rolls Royce MTU hybrid drive which can run on normal diesel power at speed, but switches automatically to battery storage when travelling slowly, such as when at a railway station.

Senior managers from Porterbrook and Chiltern Railways

The hybrid engine is being supplied by Rolls Royce combines an MTU diesel engine, built to EU Stage V requirements, with an electric unit that can function both as a motor and as a generator, and with the MTU EnergyPack battery system that stores energy recovered during braking.

The hybrid engine is said to reduce power consumption by 20 per cent, which is good for the railway, but from a passenger perspective, switching to batteries when close to railway stations improves air quality for passengers waiting at stations.

Data suggests potential reductions of 20% in fuel consumption and circa 70% in NOx emissions on Chiltern services between London and Birmingham. In addition to improved air quality and reduced noise, HybridFLEX units also expected to deliver journey time and route capacity improvements, as the combination of diesel and electric power will offer enhanced acceleration capabilities.

The Rolls Royce MTU hybrid drives are also expected to produce maintenance savings through reduced ‘wear and tear’ on consumables, such as brake pads and discs.

Rolls Royce MTU hybrid drive

The test train is owned by the rolling stock leasing firm, Porterbrook.

The HybridFLEX battery-diesel train is currently undertaking a programme of tests prior to being returned to Chiltern in the summer.