How Barcelonas Metro trains generate electricity

The Catalan city of Barcelona, home to Sagrada Família, is now partially powered by its own Metro underground trains, thanks to a system called regenerative braking. When an electric vehicle is slowed, the excess kinetic energy released when pressing the brake is harvested, transformed into electricity via a generator, and then stored for future use. Larger vehicles produce more kinetic power, and have the capacity to store more excess energy. The technology is increasingly used in electr