I. Introduction
Reduction of greenhouse gas emissions is more mandatory now than before. The aviation sector contributes significantly to these emissions, where the sector CO2 emissions resembled 2.2% of the global CO2 emissions in 2017 [1]; 97% of the aviation CO2 emissions are generated by the aircraft jet fuel [1], whose consumption reached 7% of world oil products in 2015 [2]. Jet fuel powers conventional aircraft via aeroengines. This power mainly produces the propulsive thrust, but a nonnegligible fraction is converted to four other forms [3], [4].
Pneumatic power provides energy to the environmental control system (ECS) compressor. Besides, it supplies hot air to the wing anti-icing (WAI) systems, which prevents the atmospheric ice from building up on the wings.
Mechanical power runs the main electrical generator and the central hydraulic pumps. It is also converted to the following forms.
Hydraulic power powers the actuation systems of most of the aircraft’s primary/secondary control surfaces in addition to the landing gears [3], [4].
Electric power runs the avionics, fuel pumps, lighting, communications, passenger comfort systems, cargo heaters, galley ovens, and other loads.