Dual-fuel trains enter service in India

© NGV GlobalThese are the first two, but reportedly not the last two diesel/CNG-powered trains on India's tracks

Diesel electric trains are hybrids, sort of. They use diesel-powered generators, but only to produce electricity for the motor actually motivating the wheels. Now the generators run on two fuels simultaneously, with CNG being injected into the air intake duct and passes with combustion air through the filter and the turbocharger. The amount of diesel fuel is remarkably reduced (by approx. 20%) and serves to provide ignition rather than engine power. Proportions of all combustion components (air, CNG and diesel) are controlled by an electronic unit.

The advantages are many. Not only is CNG cheaper than diesel fuel so that running costs go down, but also emission levels of carbon monoxide, carbon dioxide, nitrogen oxides and hydrocarbons are significantly reduced. Not to mention particulate matter, which is eradicated almost completely. Last but not least, substitution of diesel with natural gas extends engine life, so maintenance costs drop, too. The conversions have been carried out by the Integral Coach Factory, Chennai, a production unit under the Indian Ministry of Railways. More trains are about to follow.