Energy Storage That May Be Too Good to Be True: Comparison Between Wayside Storage and Reversible Thyristor Controlled Rectifiers for Heavy Rail

There has been substantial interest in the traction community for using wayside energy storage systems (ESSs) to better use train braking energy, thus reducing energy costs and peak power as well as voltage stabilization. An alternative solution to reach the same goals is using recuperating (also called reversible) traction power substations such as reversible thyristor controlled rectifiers (RTCRs). This article compares advantages and disadvantages of ESSs of three most common types-flywheels, batteries, and supercapacitors-and recuperating substations. The analysis takes into account size, capital cost, the "round trip" energy losses, and energy savings for heavy rail applications.