How Hybrids Work: KERS Explained

November 24, 2011 / No Comments

Modern hybrid electric vehicles are about 20-35 percent more efficient than their gas-powered counterparts. But where does that efficiency come from? KERS, or kinetic energy recovery systems, play an important role in hybrid electric vehicles and how they reduce fuel consumption.

KERS in Formula 1 Ferrari How Hybrids Work: KERS ExplainedWhat are KERS? Kinetic energy recovery systems are based on the law of physics that states that energy can be neither created nor destroyed.

Energy can be transferred (e.g., from a wall outlet to a lamp), and it can change states (e.g., electrical energy can transform into the light and heat energy of a light bulb); however, the amount of energy that goes into an action and the amount of energy that comes out the other side is always equal.

With that in mind, imagine how car brakes work. When you press the brake pedal, brake pads are pressed against the wheel drum, causing friction and slowing the vehicle. In terms of energy transfer, the braking system is transferring kinetic energy, or the car’s forward momentum, into heat energy via the friction between the wheel and the brake pad. KERS aim to recapture that wasted energy, store it and then put it back to work when needed.

How do KERS work? A kinetic energy recovery system is a broad term that can refer to any number of energy capturing systems. The type of KERS that hybrid electric vehicles use is powered by a concept called regenerative braking.” Using the car’s electric motor as a generator when the brakes are engaged, regenerative braking captures the car’s kinetic energy and then stores it one of two ways:

  • Battery storage: A battery, typically lithium ion, holds the charge generated by the electric motor and then uses that charge to accelerate the vehicle.
  • Flywheel storage: A heavy cylinder mounted on ball bearings uses the captured energy to spin at high speeds. This captured kinetic energy can then be used to power the electric motor at low speeds.

Where are KERS used? Most modern consumer class hybrid electric vehicles use regenerative braking to assist in acceleration. Formula One race cars have also begun experimenting with kinetic energy recovery systems, and they are used by a few teams today. Many hybrid electric buses also use a KERS system powered by regenerative braking, as do some freight trains.

The increased efficiency of hybrids can help reduce your monthly gasoline bill, which means more money in your wallet. But don’t forget to explore other car related savings. Find out which affordable auto insurance companies offer discounts for safe driving, customer loyalty and other factors that can lower your premium.