How the WESS was done Wayside energy storage systems (WESS) capture energy from braking trains, but instead of releas- ing it as heat they store it for later use. In SEPTA’s case, this was accomplished using a lithium-ion battery combined with ABB converters. How much energy the system can capture from any one train depends on a variety of factors (see boxed text). However, SEPTA’s project was capa- ble not only of re-using energy within the transit system but also of providing support services back to the grid—for a price. PECO, the local electric utility company serving the Philadelphia area, is a member of PJM Inter- connection, the overarching grid operator re- sponsible for maintaining the balance between supply and demand on the 13-state power sys- tem. Part of that respons

Join for free to read