What is Regenerative Braking? Energy Recovery in Trains

Regenerative Braking is an energy recovery mechanism commonly used in electric trains, metros, and trams. It converts the kinetic energy of the moving train back into electrical energy during braking, instead of wasting it as heat.
In traditional braking systems (friction braking), brake pads press against wheels or discs, creating immense heat that is lost to the atmosphere. Regenerative braking turns the train’s electric motors into generators.

How It Works

Acceleration: The electric motors consume electricity to turn the wheels.
Braking: When the driver brakes, the circuit is reversed. The momentum of the wheels turns the motors.
Generation: The motors now act as generators, creating electricity.
Feedback: This electricity is fed back into the overhead line (catenary) or third rail.

Where Does the Energy Go?

The recovered energy can be used in three ways:
Powering Other Trains: The electricity travels along the wire and powers another train accelerating nearby. This is the most efficient method.
On-board Storage: Stored in supercapacitors or batteries on the train (common in modern light rail).
Grid Feedback: Sent back to the national utility grid if the substation is equipped with reversible inverters.

Regenerative vs. Rheostatic Braking

Not all electric braking is regenerative.

This technology is a cornerstone of sustainable transport, allowing metro systems to reduce their total energy consumption by up to 30%.