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), although F1 teams have so far all opted for the battery system. Electrical 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 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.
There is one other option available – hydraulic KERS, where braking energy is used to accumulate hydraulic pressure which is then sent to the wheels when required.
Table 1 Energy storage capacities depending on materials[/one_half]
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 can be released either all in one go or at different points around the circuit. Lap time benefits range from approximately 0.1 to 0.4s.
How is the stored energy released by the driver?
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.
Why was KERS 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 – come into play.
Is a car running KERS heavier than one which is not running the system?
No. A typical KERS system weighs around 35 kilograms. Formula One cars must weigh at least 640kg (including the driver), but traditionally teams build the car to be considerably lighter and then use up 70kg of ballast to bring it up to weight. This means that teams with KERS have less ballast to move around the car and hence have less freedom to vary their car’s weight distribution. Heavier drivers are at a particular disadvantage, an issue addressed by the raising of the minimum car weight for the 2011 season.
Do teams have to use it?
The use of KERS is not compulsory. Several teams used it during its introductory 2009 season. A gentlemen’s agreement between constructors then precluded its use in 2010, before its return in 2011.