Green energy generating a more sustainable world: Discover how Johnson-Fluiten Rotary improved Kaplan Turbines’ efficiency, productivity and energy saving. Kaplan hydroelectric turbines have been using Johnson-Fluiten rotary unions for years. The precision manufacturing continuous improvement and service have made Johnson-Fluiten an appreciated partner. The Kaplan turbine, invented 1912, has been a long, proven solution for generating green energy. Kaplan turbines have an efficiency of more than 90%. Controlling the rpm, which is typically between 50-500 rpm, is important to optimize the efficiency.