Regenerative braking
Videos
Regenerative braking is an energy recovery mechanism that slows down a moving vehicle or object by converting its kinetic energy or potential energy into a form that can be either used immediately or stored until needed.
The S7/8 Stock on the London Underground can return around 20% of its energy usage to the power supply.
A Tesla Model S P85+ using regenerative braking power in excess of 60 kW. During regenerative braking the power indicator is green.
The box extending sideways from the roof directly over the word "operation" allows air to freely flow through the resistors of the dynamic brakes on this diesel-electric locomotive.
Flywheel energy storage
Videos
Flywheel energy storage (FES) works by accelerating a rotor (flywheel) to a very high speed and maintaining the energy in the system as rotational energy. When energy is extracted from the system, the flywheel's rotational speed is reduced as a consequence of the principle of conservation of energy; adding energy to the system correspondingly results in an increase in the speed of the flywheel.
One of the older gyrobuses parked in a museum in Antwerp.
A Flybrid Systems Kinetic Energy Recovery System built for use in Formula One