NOVELTY - The method involves selectively sourcing power from multiple power sources, where the power sources comprise generators (2-5) driven by an engine, and batteries (23, 26), fuel cells (24, 25), and/or thermo-electric power sources. Power is diverted to essential loads away from non-essential loads under emergency conditions. The power is selectively sourced from each of the power sources to minimize an overall consumption of aviation fuel under non-emergency conditions, where the power is sourced from the power sources simultaneously.    USE - Method for providing electrical power to essential load e.g. avionics system and flight-critical equipment and non-essential electrical load e.g. cabin lighting, food preparation system and entertainment system, of an aircraft.    ADVANTAGE - The method enables selective sourcing or co-ordination of power from appropriate power sources controlled by a controller of a power distribution system. The power is derived from the fuel cells, the batteries and/or the thermo-electric power sources in any desired combination under normal conditions, and the choice of power source can be made so as to maximize the efficiency of the power distribution by minimizing fuel usage. The method allows the fuel cells to produce water in a toilet and hand wash facilities of an aircraft, thus reducing the amount of water to be carried at take-off. The fuel cells and the thermo-electric power source are utilized for deriving power in normal operation, so that water can be generated at the same time improving the efficiency of the thermo-electric power source. The method enables retaining a ram air turbine and an auxiliary power unit, thus providing high level of redundancy and safety.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for an electrical power distribution system.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic block diagram of a power distribution system.'(Drawing includes non-English language text)'    Aircraft power distribution system (1)    Generators (2-5)    Voltage power buses (16-19)    Batteries (23, 26)    Fuel cells (24, 25)