This article presents an assessment study of the propulsion system, the fuel distribution system, and the injector/combustor technologies enabling to eliminate CO2 emissions in aviation. In addition, the discussion is on NOx reduction methods and mitigation technologies, and a concept to fully eliminate NOx is proposed. To design and deploy an advanced thermal-powered aircraft based on liquid hydrogen fuel in future, it is important to provide key estimates that support feasibility of the methods and technologies developed and explored in this paper. This is conducted here for a typical narrow-body aircraft that will be retrofitted and considered. Once the design space and performance requirements are introduced, a compact low emission combustor including all components is discussed to operate with hydrogen swirled combustion to equip the turbofan engines of this conceptualized aircraft. The fuel tank is not only discussed with respect to the difference in power per unit volume and per unit mass between Sustainable Aviation Fuel (SAF) and H2 but also taking into account the Breguet range. This demonstrates that the volume of the tanks does not need to be four times more voluminous between H2 and SAF. The paper also presents a thermodynamics performance analysis for SAF fuel that is used to retrofit the engine with hydrogen fuel keeping inlet and outlet combustor stagnation temperatures equivalent. A method to derive the required flow split for future premixed combustor is described and conserve identical thermal power between SAF and H2 fuels. Flame stabilization critical challenges are also introduced.