Faster trains use less energy
Modern trains are 40 to 50 percent faster than older ones, yet they use up almost 30 percent less energy than older, loco-hauled trains – this is the essence of a recent KTH report. There are several reasons for this: lower train weights, better aerodynamical design of new trainsets and also more advanced electric control systems, enabling the traction motors to act as generators during braking, thereby regenerating electric current to the catenary (contact wire).
This is not just a matter of small savings. For instance, if there were modern trainsets available for every train now running in the Lake Mälaren region, i e westward from Stockholm, thereby replacing older locomotive-hauled trains, an energy saving equal to the heating of 1,300 medium-size private houses would occur.
If we recalculate this to national Swedish level, the saving would become twelve to fifteen times larger. Conversely, it would be possible to increase the train traffic volume by some 35 to 40 percent without any increase in the national energy consumption.
If train speeds with locomotive-hauled trains had been raised from 130 to 200 km/h – without any other modifications – the energy consumption would instead have increased by some 60 percent.
KTH actually contributed to this favourable trend by designing the extra-wide coaches now used on the Regina type trainsets. Also, current research at KTH addressing electric propulsion systems is constantly improving electric motor performance and control.
This study was presented jointly with trainset builder Bombardier on 14 December. Five different examples of modern trainsets now operating in the Nordic countries have been studied, among them the Swedish X2000 and Regina trainsets now running around Lake Mälaren.