UAlberta mechanical engineering professors Marc Secanell (left) and Pierre Mertiny demonstrated that the use of flywheels on light rail transit can produce big savings in power and cost.

University of Alberta mechanical engineering professors are making an old technology new again by using flywheel technology to assist light rail transit (LRT) in Edmonton. They examined the possibility of using flywheel technology to store energy generated when the city’s LRT trains decelerate and stop. Trains such as the LRT are designed with so-called dynamic braking, using traction motors on the train’s wheels for smooth stops. But the deceleration generates energy, which needs to go somewhere.

Conventional systems simply send the braking electric power to resistors on the train, which convert the electrical energy to heat, which is then released into the air. A flywheel system would take the electrical energy and store it as mechanical energy. This mechanical energy could would then be converted back to electrical energy when the train is ready to leave the station again.