New technology for harnessing hydropower

The StECon (Stiller Energy Converter) is an innovative, flexible water wheel that can generate electricity in areas where it had previously been impossible due to technical constraints: in watercourses with low fall heights of up to one metre. It thus increases the exploitable hydropower potential and drives the expansion of renewable energies forward. Within the framework of a research project, the Department of Hydraulic and Coastal Engineering at the University of Siegen is currently working on bringing the water wheel to market maturity.

StECon water wheel: New potential in hydropower

The StECon is significantly more compact than conventional water wheels and can be installed at sites which do not have sufficient space for larger water wheels – for example on boat docks or in the outflows of waste water treatment plants. The latter in particular provide a good test for the research project’s practicality: In North Rhine-Westphalia, over 630 public waste water treatment plants purify 2.4 billion cubic metres of water per day on average, consuming a lot of energy in the process. If the StECon is installed at the outflows of these waste water treatment plants, these will be able to directly generate electricity for their own requirements.

Engine for progress:

  • New technology for harnessing hydropower
  • Exploitation of new hydropower potential
  • Invention and development from and in North Rhine-Westphalia
  • Ecosystem preservation

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Photo: Universität Siegen

The first model of the innovative water wheel was built by Hans-Ludwig Stiller, before the cooperation with the University of Siegen began. The photo shows the prototype which was built during the first research project.

Thanks to the energy converter STECon, the interference with nature is kept to a minimum: There is no need for damming of water bodies, construction of large hydropower plants or laying of power lines – which in turn protects the environment and the climate. This makes the StECon a real alternative to the new construction of run-of-river power plants, whose construction is usually associated with a considerable intrusion into the ecosystem. In addition, the wheel works in any watercourse with sufficient stream flow: examples in North Rhine-Westphalia include large rivers such as the Rhine, the Meuse, the Weser or the Ems. With the StECon, researchers have found a new solution for unleashing new hydropower potential, driving the energy transition further ahead and contributing to energy supply security.

From patent over research to the finished product

The water wheel was developed by the mathematician Hans-Ludwig Stiller from Bonn. He constructed a water wheel with moving blades and an axis of rotation which sits vertically when submerged. The StECon follows the working principle of a rudder: above water, the rudder is rotated parallel to the water surface so that it can be led back in as flat a position as possible and no braking effect is generated upon re-entering the water. During submersion, the rudder is rotated again to achieve the largest possible surface area for generating a forward propulsion movement. In the case of the StECon wheel, this complete movement sequence takes place underwater. It is also conceivable to power the Rhine river ferries in this way.

The Siegen-based researchers have already demonstrated the effectiveness of the StECon in their first research project (under the name StEwaKorad). In a second project, long-term tests as well as optimisations of the wheel’s design are being carried out. To this end, one prototype of the water wheel is installed in a waste water treatment plant and another onto a ship dock in the Rhine river.

Photo: Universität Siegen

"Thanks to the new energy converter STECon, the natural flow velocities of watercourses from small streams up to large rivers can be harnessed without traverse structures or weirs. This contributes to the energy transition without burdening the ecology and landscape aesthetics. "University Professor Dr.-Ing. Jürgen Jensen, Director of the Research Institute for Water and Environment at the University of Siegen

Partners and sponsors

  • Universität Siegen
  • Herr Hans-Ludwig Stiller
  • Weber Mechanische Bearbeitung

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