Roto-Kite: a study for theoretical and experimental validation by Enerkite
The work of Enerkite, with a preliminary study, has allowed to validate the project for the
generation of energy up to the order of MW, obtaining assumptions of weight and cost
of the system and LCOE parameter.
Output power peak 20 kW 1 MW
Nominal wind speed (m/s) 9 9
Kite wing opening (m) 6.5 46.2
Rotor area (m2) 130 6,700
Kite weight (kg) 9 650
Annual production (KWh) 74,885 3,744,292
Total cost generation system(*) (€) 11,320 160,000
Electricity cost (€/KW, less than) 0,025 0,02Authors: Dipl.-Mat. Max Ranneberg; Dr.-Ing. Alexander Bormann; Dr. Bernhard Kämpf; Dipl. Des. Christian Gebhardt Dipl.-Ing. S. Skutnik.
Dok.Nr.: EK_FT_0018 Date: 26.06.2014.
As a preliminary observation It appears that the rotor area is the area swept by the rotor (it is normal) and that the full opening of a wing matches its wingspan. Thus, a wing takes the radius of the swept area. A brief calculation confirms that matches the respective values of the rotor area.
Now the paper on Betz limit indicates:
“AWE drag power systems can harvest up to 16/27 of the power available in the wind.
AWE lift power systems can harvest up to 4/27 of the power available in the wind.”
The “Output power peak” values (20 kW for 130 m², 1 MW for 6,700 m² rotor areas) are far above 4/27…
As a result only one kite (instead of three) could be sufficient as I suggest here.