Kinetic Energy Recovery System (KERS) is an energy saving device fitted to the engines to convert some of the waste energy produced during braking into more useful form of energy. The system stores the energy produced under braking in a reservoir (for example a flywheel or a battery) for later use under acceleration. Kinetic Energy Recovery System is a type of Regenerative Braking system.

Regenerative braking should not be confused with dynamic braking, which dissipates the electrical energy as heat and thus is less energy efficient. Regenerative Braking is an energy recovery mechanism which slows a vehicle by converting its kinetic energy into another form, which can be either used immediately or stored until needed. The braking energy is converted into electric power, which is used to charge the vehicle battery. Regenerative braking utilizes the fact that an electric motor can also act as a generator.

Types and Operation of Kinetic Energy Recovery System (KERS)

There are principally two types of Kinetic Energy Recovery System – battery (electrical) and flywheel (Electro-Mechanical KERS). Electrical KERS systems use a motor-generator incorporated in the car’s transmission which converts mechanical energy into electrical energy and vice versa. Once the energy has been harnessed, it is stored in a battery and released when required.

Mechanical KERS systems capture braking energy and use it to turn a small flywheel which can spin at up to 80,000 rpm. When extra power is required, the flywheel is connected to the car’s rear wheels. In contrast to an electrical KERS, the mechanical energy doesn’t change state and is therefore more efficient.

Kinetic Energy Recovery Systems (KERS) by means of Flywheel Energy Storages (FES). KERS by means of FES are currently under development both for motor sport and road hybrid vehicles. Kinetic storages, also known as Flywheel Energy Storages (FES), are used in many technical fields. Flywheel mass is either mechanically driven by CVT (Continuously Variable Transmission) gear unit or electrically driven via electric motor / generator unit. Devices that directly use mechanical energy are being developed, but most FES systems use electricity to accelerate and decelerate the flywheel.

There is one other option available – Hydraulic KERS System, where braking energy is used to accumulate hydraulic pressure which is then sent to the wheels when required.

The regulations stipulate that the release must be completely under the driver’s control. There is a boost button on the steering wheel which can be pressed by the driver. The key purpose of the introduction was to significantly improve lap time and help overtaking. KERS is not introduced to improve fuel efficiency or reduce weight of the engine. It is mainly introduced to improve racing performance. One of the main reasons that not all cars use KERS is because it adds an extra 25 kilograms of weight.