Earlier this year at the Detroit Auto Show, we heard about Porsche’s hybrid race car that garners energy from a flywheel, and now a consortium called Flybus has put that energy reusing technology into a regular bus. This simple technology takes kinetic energy generated as the vehicle is breaking and winds up a flywheel that feeds energy back into the wheels when acceleration begins again. The flywheel can be wound up to a maximum of 60,000 rounds per minute and can pack some serious emissions-free energy, making both gas powered and electric vehicles more efficient. Another perk? Hybrid-electric buses can be really expensive, but engineers believe this hybrid flywheel system could sell for a fraction of the cost.
The engineers involved in the Flybus consortium come from many different companies and call their invention the Optare Solo Midibus. The companies have banded together to use their expertise to execute a single vision in making buses more efficient — Torotrak has provided the transmission, Ricardo provided the flywheel, Allison provides transmission expertise and Optare is a major UK bus and coach company. The project has been partially funded by the UK’s Technology Strategy Board and will be presented at the Low Carbon Vehicle Event which takes place this week in the UK. Though the idea has been proven feasible the group hasn’t tested the actual fuel savings of their design — that’s the next step in the process.
“The recovery and reuse of kinetic energy during stop-start drive cycles is a priority for bus operators, not just because of the positive impact on emissions but also because it reduces fuel costs and brake wear,” says John Fuller, Product Leader for Kinetic Energy Recovery Systems (KERS) at Torotrak. “Electric hybrid systems are expensive, often doubling the transaction cost of a bus. Initial cost estimates suggest that the Flybus system could be available at a fraction of the cost of an electric hybrid, whilst simulation results indicate fuel savings comfortably in excess of 10%.”