Siemens will install the first Sitras SES Energy Storage Unit with supercapacitor technology on the new TriMet Portland-Milwaukie Light Rail Transit Line in Oregon, US, to tap braking energy to be reused on the network.
The Sitras SES will store energy created during the braking of trains so it can be reused for voltage stabilisation during periods of peak demand, helping to save energy.
Siemens will install the first energy storage unit in the southeast Portland Tacoma substation, which will be used by Trimet for voltage stabilisation during peak demand.
In voltage stabilisation mode, the Sitras SES enables the rail system to ensure that the system voltage always remains within the required range, preventing voltage-related disruptions.
The system voltage can drop below a critical level if a number of vehicles accelerate simultaneously, and could result in under-voltage tripping in vehicles in some instances, leading to passenger service disruptions.
TriMet executive director of capital projects Dan Blocher said: "The regenerative energy storage unit is an important piece of the many sustainable elements being incorporated in this light rail project."
The energy generated by braking rail vehicles will be absorbed by the energy storage unit in energy savings mode and will be stored until the system can safely feed it back to the power supply during vehicle acceleration.
With the installation of the Sitras SES substations starting in October 2013, TriMet will be able to avoid placing a utility-connected substation in the same location.
Apart from cost saving, the Sitras Energy Storage Unit is also capable of reducing CO2 emissions by 300 tons per annum, according to Siemens.
Siemens is also manufacturing 18 S70 light rail vehicles (LRVs) under a $73m contract secured from TriMet in May 2012 as a part of the Portland-Milwaukie Light Rail project.
The new LRVs are expected to be delivered in August 2014, bringing the total number of light rail cars built by Siemens for TriMet to 119.
The Portland-Milwaukie Light Rail Transit Project is scheduled to be commissioned in 2015 and expand the MAX system by 60 miles.
Image: Siemens is delivering 18 S70 light rail vehicles for TriMet’s Portland-Milwaukie Light Rail project. Photo: courtesy of Steve Morgan.