Control of tethered airfoils for sustainable marine transportation

The application to marine transportation of an innovative technology for high-altitude wind power generation is presented in this paper. The key idea is to pull a boat and to generate electricity onboard by exploiting the traction forces generated by automatically controlled tethered power kites. The kites are able to fly fast in crosswind conditions, between 200 m and 600 m above the sea, thus exploiting the stronger and less variable high-altitude winds. Numerical analyses are carried out, using a mathematical model of the system and an efficient Nonlinear Model Predictive Control (NMPC) law. The control law aims to maximize a cost function that takes into account both the traction forces exerted on the boat and the generated electricity, while satisfying the kite operational constraints.