The Southeastern Pennsylvania Transportation Authority (SEPTA) has started a project to capture breaking energy from subway cars and trains on the Market-Frankford Line and supply it back to the regional electric grid.
SEPTA's new smart grid solution will capture the regenerative braking energy of trains via a large-scale battery storage system and deploy that energy as virtual power into PJM's wholesale power frequency regulation and energy markets.
When trains carrying thousands of passengers brake at each station, kinetic energy is converted into electricity and later saved at an old brick substation with a vaulted ceiling.
SEPTA general manager Joe Casey said that through the pilot project, the metropolitan transportation authority will become even more energy efficient, which will help control operating costs, benefiting both customers and taxpayers.
"We've made our system cleaner, greener and more efficient in recent years; things like replacing traditional diesel buses with diesel-electric hybrids and installing energy-efficient lighting at stations, facilities and offices," Casey said.
The pilot project was launched by SEPTA in partnership with Viridity Energy, a smart grid technology firm that specialises in electric market integration.
Battery provider Saft will provide its first dual-purpose trackside energy storage systems (ESS) that offer megawatt-level electricity storage.
Saft will design, manufacture and commission its Intensium Max20 P System, a battery ESS, while power controls, power conversion and system integration will be offered by Envitech Energy using its Envistore system.
SEPTA said that with all the technologies from its partners, the train's regenerative braking energy is being transformed into virtual power that will provide energy savings.
Viridity Energy president and CEO Audrey Zibelman said: "By harnessing the regenerative braking power of the trains and empowering SEPTA to become a virtual power generator that can provide valuable and environmentally responsible service to the electric grid, we can fulfil the promise of interconnected systems on the grid and behind the meter, responding dynamically to reliability and economic signals to strengthen the grid."
In 2010, SEPTA received a $900,000 grant from the Pennsylvania Energy Development Authority for the project.
Image: SEPTA will capture the regenerative braking energy of trains on the Market-Frankford Line through a large scale battery storage system. Photo: courtesy of AEMoreira042281.