I would say a conventional power system, single or twin or some other configuration for takeoff and climb to speed. Somewhat minimal battery storage (for weight consideration) and two power recovery tubes that have counter-rotation airflow for torque equalization. Conditioning the velocity of airflow inside the tube will move the vast majority of mass and temperature into a high friction driving flow that is moving at an accelerated spin speed, far above the speed of entrance air. (vortex tubes have air spin at over 1,000,000 rpm in a 1" pipe, from a 1/4" tube @ 100 psi) of course, a much larger design would reduce spin speed by many times. My older refrigeration manual described the power of friction inside the tiny 3/4" tube, to be equal to 1/2 horsepower (this resulted in heat transferred to the tube shell) I believe an image of basic structure and operation in one's mind, must precede any evaluation and analysis of numbers and size. Edit to add content (always forget to say the important things) That friction driving flow will power a generating stator and possibly assist in a mechanical form of drive assist to the electric discharge fan, which should be producing a slight positive thrust. The power to the rear fan will determine if this is just an energy recovery system or a possible additional power source to aid in flight.