Energy Recovering from Regenerative Braking in DC Railway System

The European community for over a decade is supporting scientific and technological studies in order to reduce the environmental impact of public transport. The modern railway system has recently been rediscovered as key technology to reduce pollution and transport emissions, because it is characterized by a relatively low ratio between energy consumption and transport capacity. However, it results that, in DC Railway system, a significant amount of the energy regenerated with dynamic braking is wasted. The adoption of energy storage system can greatly improve this situation by increasing energy saving. This paper explores this issue starting form experimental data recorded during the monitoring of a railway traction-unit in commercial service on different tracks. The energy flows during braking in real conditions will be analyzed, quantifying the amount of energy that can be recovered by adopting an energy storage system placed onboard train or in railway stations. Different storage technologies will be compared considering the constraints deriving from energy measurements.