The flywheel hybrid system will be based on technology recently developed in accordance with new Formula One regulations. The entirely mechanical system recovers the kinetic energy of a vehicle during braking in a high speed rotating flywheel, rather than using an electric motor to store it in batteries, as in current electric hybrids.
Such kinetic energy hybrid systems have several potential advantages over full electric hybrids, depending on the application. They are more efficient in recovering energy during braking and should be substantially cheaper to produce than electric hybrid systems. The flywheel is also better at 'deep cycle' charge and recharge, whereby all the energy is either released or recovered from the unit, with no loss in performance over the life of the vehicle, as can be the case with electric-based systems where batteries can lose their ability to fully charge and discharge.
The compact layout of the system also makes vehicle packaging and integration simpler. The aim for this flywheel hybrid system is that it will require no change to the base vehicle platform.
The targets for the new system are to have a round trip efficiency of 70%, with a fuel economy improvement over the NEDC (New European Drive Cycle) of 20%. One of the key advantages is that improvements in real world fuel economy are expected to be at least as good as that recorded over the NEDC cycle which is not always the case for conventional electric hybrids.
(Source: Technology Strategy Board, Image: Flybridsystems)