Volvo is currently testing a British-designed flywheel energy recovery system, which reduces fuel consumption by more than 25 per cent, while costing just a quarter of the factory price of a conventional battery-electric hybrid.
The Flybrid KERS (Kinetic Recovery System) has been fitted to the rear axle of a test S60 saloon and can be used to assist the petrol engine that drives the front wheels. It can be used either to enhance performance, knocking 1.5 seconds off the 0-62mph time of the 254bhp S60 T5, or it can be used in economy mode to reduce Co2 emissions.
The flywheel system is based on a conventional flywheel which runs at a maximum of 60,000rpm and can deliver up to 80bhp. Kinetic energy is stored in the flywheel – which runs in a true vacuum – for 20 minutes before it begins to disperse.
At full deployment, the S60 prototype gets a 10-second power boost. However, Volvo says that conventional brakes develop such a huge amount of energy that even gentle braking for eight seconds will fully recharge the flywheel. A Toyota Prius hybrid would take three times as long to store the same amount of energy, it’s claimed.