The idea of using kites as an alternative to wind turbines has been gaining ground amidst the scientific community, as winds are much stronger and consistent above a 1,000-meter altitude than on the ground. At the Swiss Federal Institute of Technology in Lausanne, Ph.D. student Sean Costello has developed an autopilot system to control and optimize a kite’s movement so as to obtain the best possible electricity production. The kite’s sail acts as a wind turbine blade. As it offers resistance to the wind, it creates a mechanical tension on the kite’s restraining cable. It is then possible to use the cable's winding and unwinding movements to drive an electric generator that can be placed either onboard or on the ground. “The stronger the cable tension is, the higher the energy production capacity, said the researcher. The autopilot that we have developed is able to find, in any given situation, the most efficient way to control the wing so that it moves as quickly as possible and generates a maximum tension in the cable. In general, the kite’s trajectory will have the shape of an 8. Since some flight paths turn out more successful than others, the autopilot will determine which one is best in each situation,” says Costello.