My understanding is that the parts of a typical flywheel energy storage are pretty much the same as the parts of a typical reaction wheel subsystem -- both have a flywheel, electric motor/generator, etc.
Is it possible for a spacecraft to use a flywheel to store and later supply energy, and also (perhaps at an even later time) re-use the same subsystem as a reaction wheel for attitude control?
Is it possible for a spacecraft to use a sufficient(*) number of flywheels to simultaneously control attitude and store energy, and later simultaneously control attitude and supply energy?
(*) 3 flywheels are not sufficient, but my understanding is that many spacecraft already have 4 or more reaction wheels ( Optimal placement of 4 reaction wheels? ).