Austrian inventor Franz Tsotleterer (Franz Zotlöterer) from the town Obergrafendorf  devised an unusual scheme for mini-HPS. His project is called “Maelstrom Technique” (Wasserwirbeltechnik), and mini-hydro -Gravitational- station.

In order to avoid adverse environmental impacts during construction of the dam mini-hydro inventor suggested that part of the flow near the bank set aside in a special channel that directs water to the dam.

 The dam consists of a concrete cylinder, to which water is suitable for the tangent, crashing into the center of the bottom. Thus, in the center of the cylinder is formed a whirlpool, which spins a turbine. This type of mini-hydro optimal for power plants of up to 150 kW. Good efficiency appears from the drop height 0,7 m.

Conversion efficiency of energy of falling water in such a mini-hydropower plant in the current reaches 73%. A prototype installed on the creek, has developed more than 50 MW Wh of electricity at an operating elevation of water 1.3 m and a flow rate of 1 cubic meter / sec. Maximum electric power of such a mini-station reaches 9.5 kW.

The action of such mini-hydro turbine speed is low and the fish caught in a whirlpool, blade wheels do not represent danger. In addition, the blade does not cut through the water, and rotate synchronously with whirlpool.

Another environmental advantage of this project is the mixing of pollutants in the whirlpool and good aeration of the water, which contributes to heavy use of microorganisms, cleaning it naturally.

Whirlpool, which is formed into a mini-hydro, contributes to thermoregulation in the water – increased contact area of water with air leads to its cooling in summer and in winter hydropower continues to operate under the ice, the most dense water gravitates to the center of swirl at the edges of the cylinder is formed ice crust, which serves the role of insulation, not giving too much to cool the center.