Philadelphia subway brakes for energy savings

SEPTA and Viridity Energy are adding a big battery to Philly's transit system. The plan is to capture energy from braking trains and feed some of it into the city's grid.
Written by Melissa Mahony, Contributor

Electric trolleys still cruise the streets of Philadelphia. Dating to 1892, Philly's transit system is one of the oldest in the U.S. It's also the country's sixth largest.

A section of it is about to get an energy upgrade.

A $900,000 pilot project is on its way to save, and possibly profit from, SEPTA's energy use.Viridity Energyplans to recycle the energy of trains coming into the station for use of the trains when they pull out.

Funded by the State of Pennsylvania, the project entails a huge battery (with 1 to 1.5 megawatt capacity) that will capture energy from the regenerative braking system of the trains, as they screech into some of the substations along the popular Market-Frankford Line.

By lessening SEPTA's dependency on electricity from the grid (remember, Pennsylvania is coal country), the system, according to Viridity, might cut SEPTA's carbon dioxide emissions by 1,258 tons each year.

From our friends at CNET:

The battery will be able to make money, too, by providing services to the grid. Using its stored energy, it can make money from grid operator PJM by supplying quick bursts of energy to maintain a steady frequency. SEPTA can also draw energy from the grid at off-peak times and supply it at peak times when the utility is looking to lower usage because energy prices are high.

If successful, the idea may travel to more of Philly's 38 substations. As is, SEPTA estimates the project will be worth $500,000 to them.

Joseph Casey, SEPTA's general manager, says in a statement:

Upon implementation, the storage system will serve as a foundation for measurable gains in both energy efficiency and voltage stability in this critical corridor, providing a replicable and scalable model for broader system-wide implementation. By moving towards energy storage, SEPTA will be assuming a leadership role among transit agencies.

New York City MTA, are you listening? (Or are you too busy raising my fare and cutting service.)

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