(c) Wiener Linien - Thomas Jantzen

In the course of the project, a pilot system will be used to determine how to use the energy generated from metro brakes more efficiently. The energy will be used in the metro stations for elevators, lighting and escalators and will reduce energy consumption sustainably. The tests were successfully completed in January 2018.

Almost all metros and trams of Wiener Linien already possess the ability to recover the energy of movement (braking energy) as electric energy when braking the train, and to feed it back to the direct current power system. This energy can be used by a train in the nearest environment for acceleration. If there is no vehicle in the vicinity of the regenerative vehicle, the energy is converted into heat in the brake resistors of the train.

The aim of the project is to test in a pilot system how to more efficiently use the accumulated energy from braking a metro train. By feeding the braking energy into the medium voltage grid, energy consumption should be reduced sustainably. The previously unused brake energy is intended to provide support to consumers in the subway stations (e.g., elevators, escalators). The pilot plant was installed on September 19, 2016.


Public transport makes a significant contribution to the quality of life in Vienna. The energy intensity of transport, however, obliges energy efficiency. Right now, the share of the electricity consumption of the metro in the total electricity consumption of Wiener Linien is about 40%. This is about 170 GWh per year, which corresponds to the annual consumption of about 50,000 Viennese households. This project will improve the energy efficiency of metro operation. This results in energy savings and a corresponding reduction in CO2 emissions. The project also has an economic benefit for the Wiener Linien as the energy costs of the metro – a significant cost center of the company’s expenses – can be reduced.

Thanks to the modern vehicle fleet and the energy-optimized driving method by means of train control, Wiener Linien already rank high in an international comparison. In order to increase the energy efficiency in the field of metro operation, however, new approaches had to be taken. Since there are different operational and technical starting points for each transport operator, no standard solution models exist. It is the task of Wiener Linien to find the best solution for the given conditions (operation, vehicles, infrastructure) in order to develop a practical application model for improved energy efficiency in the metro network of Wiener Linien.

As further expansion plans for the Viennese metro network exist, and rising passenger numbers with the growth of the city are to be expected, all gained insights can also be transferred to the further development plans of the metro system, with the aim of increasing energy efficiency with growing supply in the future. Internationally, the topic of feeding back energy is being discussed intensively. The experiences gained from this project can also serve as a model for other transport operators.

Successful test of the plant

At the beginning of 2018, the one-year test phase came to an end. The expectations of the plant, which was tested at the U2 station Hardeggasse, could even be exceeded. During the test phase about 1.6 GWh were produced by the brakes of the trains. This corresponds to the annual consumption of 360 households and energy costs of up to 100,000 euros. Of course, this recycling of energy also results in a reduction of CO2-emissions. In addition to the Hardeggasse location, five more systems throughout the metro network are planned.

The project was funded by means of the FTI Innovation Fund of Wiener Stadtwerke and the project partner Wiener Lokalbahn.


Johanna Griesmayr, BA

Press and Communication

Wiener Linien GmbH und Co KG

E-Mail: johanna.griesmayr@wienerlinien.at

Website: Wiener Linien (in German)

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