Hybrid turbofan and solid oxide fuel cell propulsion system and related methods

A hybrid propulsion system for an aircraft, the hybrid propulsion system comprising:

• a liquid natural gas solid oxide fuel cell;
• a motor driven by electric power from the solid oxide fuel cell;
• a gearbox operatively coupled to the motor;
• a turbofan engine configured to generate thrust for the aircraft, wherein the turbofan engine comprises a duct fan that is operatively coupled to the motor via the gearbox, and wherein the duct fan of the turbofan engine is driven by mechanical power from the gearbox and by the motor;
• and
• a turbo generator operatively coupled to the duct fan and a turbine downstream of the turbofan engine, the turbo generator being parallel with the solid oxide fuel cell.

A method of providing thrust to an aircraft via a hybrid propulsion system, the method comprising:

• generating a first amount of electric power via a liquid natural gas solid oxide fuel cell and driving a motor therewith, wherein the motor is operatively coupled to a duct fan of a turbofan engine of the aircraft via a gearbox;
• driving the motor via a turbo generator simultaneously with driving the motor with the first amount of electric power from the solid oxide fuel cell;
• driving the duct fan of the turbofan engine by mechanical power from the gearbox and the motor, thereby providing the thrust to the aircraft;
• extracting fan bleed air from the duct fan of the turbofan engine;
• and using the fan bleed air as source air for the solid oxide fuel cell.