IIRC, safety measures for high-energy flywheels end up being pretty expensive. Basically, if the wheel or bearing fails, something is going to get seriously fuc

IIRC, safety measures for high-energy flywheels end up being pretty expensive. Basically, if the wheel or bearing fails, something is going to get seriously fucked up, and an appropriate sacrificial structure is a task in itself. I was once told of a physics lab that, rather than attempting a containment structure, was located next to miles of forest in case its flywheels, er, escaped.