An energy buffer device supplies energy to a consumer in an aircraft, and an electrical system for an aircraft. In one example, the device includes an energy feed device, an energy storage device and an energy supply device. The energy supply device may have line with a larger cross-sectional area than a corresponding line of the energy feed device. With the use of an energy buffer device, power may be switched on only for a short period of time. In addition, in case of a voltage breakdown in an on-board network, energy may be stored in an energy storage device. Supply of energy may thus occur over a short time at correspondingly high power, without placing a load on an on-board network or a generator.