> flywheels have a pretty destructive worst-case failure mode... Do they? If their casing is solid enough, the worst that they can do is damage themselves inte

> flywheels have a pretty destructive worst-case failure mode... Do they? If their casing is solid enough, the worst that they can do is damage themselves internally and heat up a bit. There is no buildup of pressure, leakage of chemicals or risk of a chemical fire.