Flywheels got touted several years ago as a great way to store energy, which is needed if renewable energy use continues to increase, and is used. But they had problems. A new flywheel design claims to have solved some of those problems. We shall see. But it if works, it's better news for those renewables like solar and wind that are intermittent.
Storing electricity in spinning wheels isn't new, but a new design may make it cheap enough to compete with other technologies