Johannes Juul (1887-1969), Dutch wind energy pioneer who built an innovative 200 kW wind turbine in Gedser, Denmark, on the southern coast (1956-57). This is thought to be the first wind turbine connected with an asynchronous AC generator to an electrical grid. The turbine was equiped with aerodynamic tip brakes on the rotor blades that released automatically in dangerously high winds. For many years, the Gedser wind turbine remained the largest in the world, and it ran without any major maintenance for 11 years. It was refurbished in 1975 at the request of the National Aeronautics and Space Administration (NASA), who sought measurement results from the turbine for the new U.S. wind energy program. Juul was one of the first students of wind energy pioneer Poul La Cour.
The Wind Energy Pioneers: The Gedser Wind Turbine (Danish Wind Energy Association)