Method of supplying auxiliary power from an auxiliary power unit and corresponding architecture

The method involves providing non-propelling power to consumers of an aircraft from a storage reservoir (31) of fuel (4) common to an engine of the aircraft and an auxiliary power unit (APU) (2), in a main mode. A basic circulation of the fuel is provided to a combustion chamber (21) of the APU. The APU is used in an emergency mode to provide backup power to vital systems of the aircraft. The chamber is supplied by emergency fuel (6) from an emergency tank (51) according to independent and separated circulation in a part in connection with a primary pipe (52). The fuel is kerosene, and the emergence fuel (6) is hydrogen directly stored in a solid, liquid or gas state in the specific source. An independent claim is also included for power supply architecture.