Siemens Develops New Energy Storage System for Trams

Siemens has launched a new energy storage system, which reduces emissions by up to 80 metric tons of CO2 per year and enables trams to operate without an overhead contact line.

The new Sitras HES hybrid energy storage system consists of two energy-storing components: the Sitras MES mobile energy storage unit (double-layer capacitor, DLC) and a nickel-metal hydride battery.

Vehicles equipped with energy storage systems consume up to 30% less energy per year and produce up to 80 metric tons less CO2 emission than vehicles without energy storage systems.

Thanks to a new connection concept, Sitras HES and Sitras MES can be retrofitted in existing vehicles without any difficulty leaving the tramway infrastructure completely unaffected.

When the vehicle is in operation, the energy storage units are charged during braking. A tram can use this stored energy to travel relatively long distances without having to be supplied with power from the contact line. The energy storage units can also be recharged en route.

Siemens Mobility installed a Sitras HES in a tram belonging to the Portuguese company Metro Transportes do Sul SA (MTS) in November 2008. The system has since been used in passenger service and has proved to be highly successful.