Energy Storage System, which usually uses capacitors to capture energy and release it again shortly afterwards to
boost train acceleration.
But in SEPTA’s case, the capacitors have been replaced with high performance lithium-ion batteries supplied by Saft,
a world leader in the design and manufacture of advanced technology batteries for industry.
The energy recovery and storage system is complemented with software that enables SEPTA to monitor energy prices and sell the stored energy back to the grid when energy prices are high, usually during peak hours and in hot weather, so helping reduce operational costs and creating a new revenue stream.
Braking energy is captured from 400 stopping trains per day at the five stations and has enabled SEPTA to drop its energy consumption by 10 per cent, equivalent to $190,000 per year and bring in a revenue of between $75,000 and $250,000
It is the ability to sell energy back to the grid at peak times that has made wayside energy storage for mass transit systems commercially viable and it also brings the additional benefit of back-up power in the event of an emergency outage.