Attentive passengers get a pleasant surprise as the train pulls away – it’s all so quiet! The line is usually served by a multiple-unit train with a heavy diesel unit above the bogies. There’s no way around it, since there’s no overhead line. In technical terms, the line is not electrified. So diesel propulsion is the only way. Until now.
The vehicle accelerating out of the station in this scenario has neither a diesel drive nor an overhead line. Engineers at the Knorr-Bremse subsidiary Kiepe Electric have converted it to run largely on electricity. One of the two diesel units has made way for a large, high-performance battery unit. The control system switches to battery power on non-electrified sections of the route. These account for 40 percent of Germany’s entire rail network. If there is an overhead line, the control system draws power from it – and charges the batteries at the same time. This concept could soon be widely used on passenger trains.
This approach represents a genuine bridging technology to climate-neutral trains. On routes that used to be served exclusively by diesel power, operators are now running all-electric or using a maximum of 20 percent diesel power. In combination, the three energy sources of overhead line, traction battery and diesel generator bring huge savings in energy and CO2 emissions. This also stems from the varying degrees of efficiency. With electric traction under overhead lines, efficiency is as high as 80 percent. The battery-powered train is only slightly lower, at around 73 percent. The conventional diesel multiple unit, on the other hand, only achieves around 35 percent efficiency.