Flywheels are kinetic energy storage systems: a flat cylinder is rotated around a pivot, and this inertia is then reused as is (e.g. in Formula 1 racing) or in the form of electricity. These are very short-term, highly reactive storage systems.
Flywheels are currently widely used. In particular, they are found in Formula 1’s Kinetic Energy Recovery Systems (KERS ): when braking, kinetic energy is absorbed by the flywheel and then released. Generally speaking, they can be found in machinery. We’re going to look at flywheels designed to store electricity.
The principle of flywheels for storing electricity
The energy we want to store will rotate a flat cylinder, then, when we want to recover it, we activate a system that generates electricity with this rotation, slowing it down.
Flywheels are extremely reactive, whether charged or discharged. This is their main advantage, which is why they are already widely used in many machines. They are also likely to be developed to improve load management on smart grids.
The flywheel must have two crucial characteristics: it must have a high density (be heavy and not take up too much space) and it must be strong. Indeed, its storage capacity depends on its mass. However, the heavier it is, the greater the stress it will be exposed to. It must therefore be resistant to shattering.
Innovations in flywheels
Flywheels can be improved in a number of ways:
- Reducing friction.
- Developing heavier, more resistant materials.