Johannes Juul
Johannes Juul was a Danish engineer who is remembered for the important part he played in the development of wind turbines. His achievements are included in the Danish Culture Canon.
Early life
Born in Ormslev near Aarhus, Juul was brought up in a Grundtvigian home. He attended a free school, where physics was his favorite subject. His uncle bought him equipment for experiments. When he was 17, he became a student at Askov Højskole, a folk high school, where he was one of the first to study wind electricity applications under the pioneer Poul la Cour. The school was the first in Denmark to have a turbine producing electric power. He went on to qualify as an electrician at Copenhagen's Machinist School in 1914, taking a power electronics diploma the following year at Helsingør Technical School.Career
On the basis of a bank loan, Juul set up his own workshop in Køge working as an electrical installer and power electronics expert. One of his customers was the electricity company SEAS who gave him responsibility for their grid.After carefully studying the needs of Danish housewives, he worked on the design of an electric oven. In order to save power and reduce risk, he created a model with hotplates operating at 6, 11 and 14 volts, depending on the amount of heat required. The hotplates heated up much more quickly than on earlier models. His patented design was put into production in 1934 by the firm Lauritz Knudsen, remaining popular until the late 1950s.
Denmark had suffered from fuel shortages during the Second World War. In 1947, Juul therefore embarked on the wind turbine project that was to bring him worldwide fame. After much experimentation with wind tunnels, the first turbine with two blades and producing 10 kW, was developed in 1950 and installed at Vester Egesborg in the south of Zealand. The turbine turned out to be generally self-regulating as the rotor was automatically slowed down by the generator's braking action, even in heavy winds. For additional protection, he invented a system consisting of aerodynamic brakes on the blade tips. Two years later he produced a turbine for Bogø with an output of 45 kW.
Installed at the top of a tower in 1957, the 200 kW Gedser wind turbine was designed by Johannes Juul on the basis of the Bogø turbine. The Gedser facility ran maintenance free for over 10 years. Now dismantled, its essentials can be seen at the Energy Museum near Bjerringbro in central Jutland, while the tower still stands near the east coast, 2 km North of Gedser.