Energy supply system for a consumer unit with one or more safety-relevant electronic consumers (14a..x), having: an energy supply network to which at least one safety-relevant electronic consumer (14a..x) can be connected or is connected; a main energy supply source for feeding electrical energy into the energy supply network in the normal operating mode of the energy supply system; a first energy detection device for detecting the electrical energy which is fed into the energy supply network by the main energy supply source; at least one thermal battery (26a..n) for feeding electrical energy into the energy supply network in the emergency operating mode of the energy supply system if the electrical energy which can be fed into the energy supply network by the main energy supply source is insufficient, wherein at least one capacitor is connected in parallel with the at least one thermal battery (26a..n); a controller for switching the energy supply system into the emergency operating mode and activating the at least one thermal battery (26a..n) if the energy which is detected by the first energy detection device undershoots a predetermined limiting value; and a switch (15a..x) in series with the at least one safety-relevant electronic consumer (14a..x), characterized in that also a second energy detection device is provided for detecting the electrical energy which is fed into the energy supply network by the at least one thermal battery (26a..n); and the controller is also configured to open the switch (15a..x) of the safety-relevant electronic consumer (14a..x) in the emergency operating mode of the energy supply system in order to charge the at least one capacitor if the energy which is detected by the second energy detection device undershoots a predetermined limiting value. an energy supply network to which at least one safety-relevant electronic consumer (14a..x) can be connected or is connected; a main energy supply source for feeding electrical energy into the energy supply network in the normal operating mode of the energy supply system; a first energy detection device for detecting the electrical energy which is fed into the energy supply network by the main energy supply source; at least one thermal battery (26a..n) for feeding electrical energy into the energy supply network in the emergency operating mode of the energy supply system if the electrical energy which can be fed into the energy supply network by the main energy supply source is insufficient, wherein at least one capacitor is connected in parallel with the at least one thermal battery (26a..n); a controller for switching the energy supply system into the emergency operating mode and activating the at least one thermal battery (26a..n) if the energy which is detected by the first energy detection device undershoots a predetermined limiting value; and a switch (15a..x) in series with the at least one safety-relevant electronic consumer (14a..x), characterized in that also a second energy detection device is provided for detecting the electrical energy which is fed into the energy supply network by the at least one thermal battery (26a..n); and the controller is also configured to open the switch (15a..x) of the safety-relevant electronic consumer (14a..x) in the emergency operating mode of the energy supply system in order to charge the at least one capacitor if the energy which is detected by the second energy detection device undershoots a predetermined limiting value.