[MrBuddyCasino]

Thats not the theoretical limit though. This is a physical device with moving parts. What if the bearing fails? What if the weight disintegrates due to a manufacturing fault?

Suddenly all that stored energy wants to go somewhere.

[opwieurposiu]

The flywheel will have breakers to prevent excessive inflow or outflow of power.

In a conventional plant, the spinning machinery is monitored by vibration sensors. If the vibration exceeds some threshold, a "Turbine Trip" occurs and the offending generator is disconnected from the grid. It then slowly spins down, dissipating energy via it's own friction.

https://en.wikipedia.org/wiki/Turbine_trip