Flywheels have very different properties from battery storage. Most notably flywheels loose a lot of power over time and are mostly good for short term storage.

Flywheels have very different properties from battery storage. Most notably flywheels loose a lot of power over time and are mostly good for short term storage. So it depends a lot on the situation which technology makes more sense. In the case of that Island I assume what they need is that over longer timeframes they have enough sun and can store the oversupply of electricity for a relatively long time, because the occassions when there isn't enough sun are rare.