A method for providing electrical energy to a self-destruct fuze for submunitions in a projectile, the method including: storing mechanical energy in an elastic element attached to a first movable mass at one end of the elastic element upon a firing acceleration of the projectile; engaging a second movable mass with the first movable mass such that movement of the second movable mass upon the acceleration moves the second movable mass which in turn moves the first movable mass; converting the stored mechanical energy to electrical energy upon the acceleration to vibrate the first movable mass and the elastic element to apply a cyclic force to a piezoelectric element attached to another end of the elastic element; and locking the second movable mass in a position where the second movable mass cannot interfere with vibration of the first movable mass upon the second movable mass being subjected to the acceleration.