Harnessing hybrid energy storage

The contract, worth more than 100 million euros, will see Siemen’s supply 19 Avenio trams that are equipped with the company’s Sitras Hybrid Energy Storage (HES) system, which will run on 11.5km of track wihout any overhead contact lines, with energy being supplied at the tram stops.

A spokesperson for Siemens Australia told Rail Express that the contract marks the first time that a tram network will be designed to take advantage of the benefits of energy storage.

“Hybrid energy storage offers energy savings up to 30% which equates to 80 tonnes less CO2 emissions per tram per year,” the spokesperson said.

Siemen’s system will be installed at Doha’s Qatar Foundation – a centre of excellence housing a cluster of top universities and world-class research and technology centres, designed to tranform Qatar into a knowledge-based society – serving the university campus and 25 stations.

Siemens Rail Systems chief exectuive Hans-Joerg Grundmann said the trams' energy storage system for optimising the energy balance and its operation without overhead contact lines “go toward making the Avenio a model system for sustainable, rail-based mass transit.”

According to Saad Al Muhannadi, Qatar Foundation vice president of Capital Projects and Facilities Management, the contract demonstrates the Qatar Foundation’s commitment to help spearhead the nation’s drive towards environmental sustainability.

“All of our new constructions are designed with the environment in mind, and this innovative transport scheme further demonstrates this commitment. Ultimately, our aim is to make the Qatar Foundation site a car-free zone and, with the introduction of the new tram system, we are well on our way to achieving this goal," Al Muhannadi said.

According to Siemens, running without overhead contact lines has a positive effect on the urban landscape. The Sitras HES system can be charged at each of the 25 stops even during the shortest of halts by means of centralised rectifier substations and distributed charging stations. Power converters transform the three-phase current with a rated voltage of 11 kV into the 750 V direct current required for charging the energy storage unit.

The Sitras HES system consists of double-layer capacitors and a traction battery. No pantograph needs to be raised thanks to the special design of the overhead conductor rails at the tram stops.

The spokesperson said the company’s hyrbid energy storage system has potenital application for Australia.

"Light rail in Australia is again becoming first choice for new or expanding public transprot systems," the spokesperson said.

"This technology, with its many beenfits, is ideal for large metropolitan networks like Sydney or Melbourne and for smaller conurbations like Canberra."

Siemen’s contract with the Qatar Foundation also includes signalling and communication systems, electrification and depot equipment. The tram system will enter service in 2015.