The Flywheel KERS is fitted to the rear axle and stores energy generated from braking by spinning a carbon fiber flywheel to a speedy 60,000 rpm. And when the vehicle needs to get on the go, the flywheel releases all that energy back onto the rear wheels through a sophisticated Continuously Variable Transmission (CVT). While the front wheels are still powered by a conventional combustion engine, the Flywheel KERS will give an extra 80 horsepower boost, which can be used either to aid fuel consumption or improve acceleration. But since the flywheel only recovers a limited amount of energy from braking, the system's benefits will be most effective during repeated starts and stops in busy urban traffic, saving as much as 20% in fuel according to Volvo.
"If the tests and technical development go as planned, we expect cars with flywheel technology to reach the showrooms within a few years," says Derek Crabb, Vice President of Powertrain Engineering for Volvo. "The flywheel technology is relatively cheap. It can be used in a much larger volume of our cars than top-of-the-line technology such as the plug-in hybrid. This means that it has potential to play a major role in our CO2-cutting DRIVe Towards Zero strategy."
This technology has already been explored 30 years ago, but its development back then was hampered by the limited material options of the time. It is only now can they exploit the true potential of the system by using a lightweight carbon fiber flywheel. Volvo's Flywheel KERS technology might not be as versatile as a hybrid system as it can only store small amounts of energy compared to a battery, but considering its simplicity, it might just be the most cost-effective fuel-saving solution today. As testing begins this 2011, Volvo will be one of the world's first car manufacturers to utilize the potential of flywheel technology.