A method for operating a fuel cell system includes electrically coupling a fuel cell stack to an energy storage device and an electrical demand by a load device. The deposited precursor is cured by electron-beam, infrared-light, visible-light, or ultraviolet-light radiation, as most appropriate for the particular material being deposited. The fan ring includes a suction-side rounded part which reduces a flow channel on a suction side and a discharge-side rounded part which expands the flow channel on a discharge side, and each of the blade pieces is inclined at a sweep forward angle from an axial center toward a rotation direction. These chambers communicate with a main chamber via conduits.