Used city bus batteries get second life in Hanover

Battery systems from Mercedes-Benz eCitaro city buses are being given a second life as stationary energy storage units. (Photo: Daimler Buses)

Daimler Buses is a partner in the GUW+ pilot project at Üstra Hannoversche Verkehrsbetriebe AG, in which battery systems from Mercedes-Benz eCitaro city buses are being given a second life as stationary energy storage units. Announced in 2021, the project involving an energy storage solution developed and implemented by Mercedes-Benz Energy GmbH has now been put into operation at Üstra’s rectifier substation in Hanover, Germany.

The rectifier substation powers Üstra’s light rail and electric buses and is connected to the public power grid. The energy storage unit is being used to serve as a buffer, allowing recuperated energy to be used efficiently for light rail. By storing energy in this way, it is possible to balance load peaks and ensure smooth, continued operation in the event of a grid failure, the announcement noted. Üstra has also set up a specially designed charging station on its premises to charge its electric buses using the rectifier substation’s storage system.

The stationary storage solution consists of 28 second-life NMC battery systems with a total capacity of more than 500 kWh. (Photo: Daimler Buses)

The stationary storage solution consists of 28 second-life NMC battery systems from eCitaro buses, with a total capacity of more than 500 kWh. The solution is regenerative and configurable, and can be adapted as necessary for other applications and scaled accordingly.

The batteries used in the GUW+ pilot project currently still come from buses used by Daimler Buses to conduct test drives. Daimler Buses also assisted in the development of the software and control components. Mercedes-Benz Energy GmbH, a subsidiary of Mercedes-Benz AG specializing in second life and “spare storage units” applications, is responsible for the development and implementation of the energy storage unit for the project on behalf of Fraunhofer IVI.

Starting in 2026, the stationary energy storage unit is expected to be expanded with batteries swapped out from 49 all-electric eCitaro rigid and articulated buses currently run by Üstra, enabling Üstra to completely cover its energy needs with its own batteries.