Enhancing Efficiency and Storage Capacity

2006 - 2016

Wayside Energy Storage System Pilot

SEPTA officially unveiled a "wayside energy storage system" (WESS) at the Letterly Substation in Kensington and Griscom Substation in the Frankford neighborhood of Philadelphia in 2012. The system allows SEPTA to capture, store, and reuse the regenerative braking energy from railcars on the Market-Frankford Line. In a similar way that batteries on hybrid-electric buses reduce fuel consumption, the WESS reduces electricity required to power the Market-Frankford Line.

As part of the WESS pilot, the regenerative braking capacity for railcars along the Market-Frankford line was optimized. As railcars along the Market-Frankford Line brake, the motor of the train acts as a generator, turning the kinetic energy of the train back into electrical energy. That electrical energy can be reused to power the train, sent along the rail to help power an accelerating train nearby or the electrical energy can be captured by WESS battery. Optimizing regenerative breaking capabilities in combination with the WESS simultaneously minimized electricity requirements and maximized GHG emission reductions of this project.

Project Highlights:
  • SEPTA was one of the first in public transportation to install this battery
  • Optimized regenerative braking capabilities
  • Reduced energy consumption by 27,016,998 kWh
  • Reduced GHG emissions by 59,375,279 lbs CO2-equivalent

Silverliner V-Fleet
The Silverliner V fleet regenerative braking system improvements allowed SEPTA to increase the efficiency of the rail fleet. Between 2011 and 2015, the rail fleet improved by 19 kWh per car mile, which reduced GHG emissions by 4,996,332 lbs CO2-E. All future commuter railcar procurements will feature regenerative braking capabilities.

2016 - 2021

Wayside Energy Storage Build-Out

Success from the WESS pilot prompted SEPTA to install seven new WESS batteries along the Market-Frankford and Broad Street Lines. Energy and GHG emissions reductions from this build-out will be incrementally less because the regenerative braking capabilities have already been optimized. The additional seven batteries will both increase the efficiency of the Market-Frankford and Broad Street Lines and provide resiliency in the event of an grid power outage by offering 8.75 MW worth of storage capacity. Once installed, SEPTA's GHG emissions will be reduced by 5,672,026 lbs CO2-E.

The image below showcases how the WESS works to capture and store energy from regenerative braking:

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