Motorsport: Energy recovery cleans up F1

Last year the Federation Internationale de l'Automobile (FIA), decided it would get involved in some hybrid technology and introduced the Kinetic Energy Recovery System (KERS). It was up to teams to decide if they wanted to use it or not. The new rules allowed cars to collect, retain and reuse kinetic energy that would otherwise have been dissipated as heat under braking.

With a KERS system fitted, a Formula One car can now store energy during braking at a rate of up 60kW. This stored energy is then re-introduced as part of the drivetrain each lap and boosts the car's overall power by up to 10 per cent.

Drivers have access to a "boost" button that releases the stored energy.

An F1 car's efficiency is improved and some would say the racing has become more exciting. However, most agree the racing is better because of the aero changes introduced, which has reduced the amount of dirty air behind the cars. This allows following cars to get closer to car in front. President of the FIA, Max Mosley, decided a KERS system would go part way towards making Formula 1 more environmentally clean and relevant. He also envisaged more racing technology cross-platforming over to normal road cars. He wanted to see F1 as a manufacturers' research and development arm of their business rather than a place to build big fast things with no general relevance. At the first few races of the 2009 season the teams who had spent more time developing KERS were behind the teams who had decided not to develop KERS but concentrate on improved aerodynamics.

KERS cars were slower than the so-called double diffuser cars that had a special rear airflow design. So in the first races, no KERS cars won.

The rules stipulate that cars may have a maximum of 80 extra horsepower - about 10 per cent more than that produced by the engine - for 6.5 seconds per lap. Drivers may use a single power burst, or multiple short bursts. The batteries where the extra energy is stored are lithium ion; with the Williams team the only one using a flywheel system.

Teams that chose to use KERS have slower cars because of the extra weight the system carries, 20 to 27kg and a car must be a minimum 605kg, including driver. Because use of ballast helps in the car's racing set-up, lighter drivers have an advantage. Although BMW has both abandoned KERS and F1, an example of how important weight is was evident when Robert Kubica was unable to use ballast while the lighter Nick Heidfeld could place ballast in strategic parts of the car and make it easier to drive. But the extra weight meant the KERS cars were slower compared to their non-KERS equipped opponents.

But KERS did help some drivers overtake. It also helped give some drivers an advantage when the lights changed getting a bit of a jump on the rest by the first corner.

Set out below is how the KERS system works on the Renault R29 courtesy of Renault and FormulaOne.com.

When the 2009 KERS system was being conceived, the engineers had a choice between two different approaches. The first consisted of using a carbon flywheel in a vacuum linked via a CVT transmission to the differential. This system stores the mechanical energy, offers a big storage capacity and has the advantage of being independent from the gearbox.

However, to be driven precisely, it requires some powerful and bulky actuators, and lots of space. The second option was to rely on an electrical motor, which works by charging the batteries under braking and releasing the power on acceleration.

Renault chose to go with the electrical solution, as did most other teams. The system consists of three important parts:

- An electric motor (MGU: Motor Generator Unit) situated between the fuel tank and the engine, linked directly to the crankshaft of the V8 to deliver additional power.

- Some latest generation ion-lithium batteries (HVB: High Voltage Battery Pack) capable of storing and delivering energy rapidly.

- A control box (KCU: KERS Control Unit), which manages the behaviour of the MGU when charging and releasing energy. It is linked to the car's standard electronic control unit.

Firstly, it was necessary to deal with the weight and volume of the system, which adds considerable weight in comparison with the 2008 car. Also, the cooling of the batteries is of great importance and it was necessary to develop a specific system.

The batteries are positioned under the fuel tank. Some teams have chosen to place them under the driver's legs or in the sidepods, but Renault opted against this as it felt these solutions presented more problems.

The MGU is connected straight to the rear wheels and releases its power through the differential. Some teams ran out of time to get a system up and running at the start of the season due to the development timescale being tight: just 18 months.

There has also been the safety of the drivers and mechanics to consider which has required extensive safety training. Finally, the factories have had to install special testing rigs and implement further personnel training

If all the teams use KERS, they will use it in the same way, in the same places, at the same times, and so there will be no advantage. On the other hand, not having the system will be an enormous handicap.

The development of electrical motors capable of delivering 80 horsepower for minimum space and weight while operating in a harsh environment represents a significant step forward in the world of energy recovery.

* Additional information from BMW.