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SEPTA / Viridity Energy S EPTA's Market Frankford line, the busiest transit line in Philadelphia and referred to locally as the “El,” has moved commuters, shoppers and visitors for more than 100 years. Moving these trains requires a large amount of electricity. In 2010, SEPTA partnered with Viridity Energy to implement a new strategy to cost-effectively reduce SEPTA's energy consumption. The El's electrically powered trains also have regenerative braking capabilities. When trains brake, their electric motors produce energy—a six-car train on the Market-Frankford Line can produce up to three megawatts in 15 seconds of braking. The problem is, unlike hybrid vehicles, 20th century trains were not designed with an energy storage capacity. Regenerated energy from a braking train can only be used if there is another train accelerating in the immediate area. Otherwise, the regenerated energy is wasted—dissipating as heat through resistor banks on the top of the train. Viridity applied for and was awarded a $900,000 Pennsylvania Energy Development Authority (PEDA) grant to enable SEPTA to install an energy storage device at the Letterly Substation in the Kensington section of Philadelphia, thereby effectively "hybridizing" a key portion of the MarketFrankford Line. The device captures much of the regenerated energy, stores it, and pumps it back into the system as needed. The project team selected Saft Batteries to manufacture the storage device and Envitech to supply the electronic controls for system integration. SEPTA anticipated that the device would supply approximately 10 percent of the power demand at Letterly, reducing electricity bills by more than $100,000. Actual results have been close to estimates since commissioning in June 2012. In addition to energy savings, the storage device has served as a distributed energy resource for the regional grid operator, PJM. During extreme weather (very hot or very cold) events, the grid can become destabilized by large fluctuations in demand. SEPTA's energy storage device has helped PJM regulate grid frequency, which in turn has generated additional revenue from the project. During the unusually cold month of January 2014, for example, the storage device generated more than $55,000 in revenue from frequency regulation services—more than one-fifth of the total annual estimate of revenue potential. Photo courtesy: SEPTA Photo courtesy: Viridity The capture, storage, and reuse of electricity generated from braking trains improves energy efficiency and reduces demand for SEPTA and the entire PJM grid. The success of this project has led to SEPTA scoping work for another energy storage system along their Market Frankford line—and ultimately to many other substations across the system —resulting in continued savings for SEPTA commuters. Pennsylvania Energy Development Authority 0120-FS-DEP4515 2/2016 G1595