Kinetic Energy Recovery Systems (KERS)

What is KERS?
The acronym KERS stands for Kinetic Energy Recovery System. The device recovers the kinetic energy that is present in the waste heat created by the car’s braking process. It stores that energy and converts it into power that can be called upon to boost acceleration.

How does it work?
There are principally two types of system - battery (electrical) and flywheel (mechanical). The electrical system looks like being the most popular. It uses 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.

The mechanical system captures braking energy and uses 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 the electrical KERS, the mechanical energy doesn’t change state and is therefore more efficient.

There is one other option available, though it looks unlikely to be adopted - hydraulic KERS, where braking energy is used to accumulate hydraulic pressure which is then sent to the wheels when required.

Do the regulations place limitations on the use of KERS?
Currently the regulations permit the systems to convey a maximum of 60kw (approximately 80bhp), while the storage capacity is limited to 400 kilojoules. This means that the 80bhp is available for anything up to 6.67s per laps, which could be released either all in one go, or at different points around the circuit. The predicted lap time benefit is expected to be around 0.1s and 0.3s.

How will the stored energy be released by the driver?
The regulations stipulate that the release must be completely under the driver’s control. There will be a boost button on the steering wheel which can be pressed by the driver.

Why has KERS been introduced?
The aims are twofold. Firstly to promote the development of environmentally friendly and road car-relevant technologies in Formula One racing; and secondly to aid overtaking. A chasing driver can use his boost button to help him pass the car in front, while the leading driver can use his boost button to escape. In line with the regulations, there are limits on the device’s use and therefore tactics - when and where to use the KERS energy - will come into play.

Do teams have to use it?
The use of KERS is not compulsory for 2009. Given that the ultimate costs and benefits of the system remain somewhat unclear, do not be surprised if some team’s 2009 machine’s do not initially feature KERS.

Will a car running KERS be heavier than one which is not running the system?
No. The KERS systems are expected to weigh around 35 kilograms. Formula One cars must weigh at least 605kg (including the driver), but traditionally teams build the car to be considerably lighter and then use up 70 kg of ballast to bring it up to weight. This means that teams with KERS will have less ballast to move around the car and hence have less freedom to vary their car’s weight distribution. Any teams using KERS and a relatively heavy driver will have even less freedom, so lighter drivers could be at an advantage in 2009.