In theory the transition to hybrid power for trains should be easy, since many already have drives for both diesel and electric motors -- which are used alternatively, depending upon whether the tracks have electric power supplied (in Europe, just over half of the train tracks are electrified, on average).
First Converted Hybrid Train Starts Carrying Passengers
But due to factors like the longer capital investment planning cycles, the sensitivity to reliability, and the more extreme conditions faced by trains, hybrid technology has been slow to leap onto the tracks, where it has been limited mostly to shunting locomotives which have particularly high energy losses. That is about to change, with the first converted hybrid train taking passengers in Germany, part of a hybrid train pilot project.
The first hybrid train project will carry passengers between Aschaffenburg und Miltenberg, southeast of Frankfurt on the Main. The route has 14 stops in just 37 km (22 miles), therefore many opportunities to recharge batteries with regenerated braking power.
Hybrid Power Pack Replaces Diesel Engines
A Siemens Desiro Classic VT 642 locomotive was refitted with batteries and regenerative braking capacity for the project. Where two 275 Kilowatt diesel engines once reigned, two 315 Kilowatt-rated hybrid power packs now drive the train. Tognum daughter MTU provided the new drive system -- intended to reduce fuel consumption and greenhouse gas emissions by 25% by diverting energy captured during braking to batteries for later use.
In addition to reducing fuel consumption, the MTU hybrid power pack supports emissions-free movement in sensitive or populated areas such as in the station area. Braking energy can be stored in a lithium-ion battery and used for starting, accelerating, or for supplying electrical loads on the train. Battery packs sit on the roof, where they are cooled by the air streaming across the top of the train while it is in motion.