Give me a lever long enough, and a fulcrum strong enough, and single-handed, I can move the world.


  • Low-maintenance technology
  • Also suitable for low heads
  • Favourable acquisition costs
  • Long service life, then 100% recyclable
  • Versatile
  • The ecological value of existing weirs improves if they are converted to incorporate a hydropower screw
  • Can be used as a water lifting screw for drainage and flood protection 
Design principle of the Rehart hydropower screw

Robust powerhouse. Tested by Archimedes!

Even well into the 19th Century, water was the only reliable means of generating energy. There were 80,000 such sites located along German rivers and streams.

As far back as 250 B.C., Archimedes discovered the principle of the screw named after him. It enabled water to be brought up to a higher level. At that time, it was a revolutionary invention for the irrigation and drainage of large fields. The transfer of energy used in Archimedes' screw-trough pump was later reversed to create a system for generating electrical energy. Now it's not the screw that moves the water, but the water that moves the screw.

The principle is simple
A hydropower screw is installed in a trough or tube set at an angle of 20 to 30 degrees. The water flows in from the top and the weight of the falling water acts on the helix of the screw, setting it in motion. The resulting screw rotation of 20 to 40 rpm is transformed by the gearbox to the generator speed. This is an easy and yet very effective way of generating environmentally friendly energy.

Without the water having been changed in any way, it flows out of the bottom of the trough and continues on its way.

The principle is robust
These low-speed generators are characterized by their robustness and ease of maintenance. They are adaptable and cope well with varying amounts of water. In contrast to conventional turbines, their efficiency remains an almost constant 90%. Not only that, water even continues to flow at night and on windless days. This technology also does away with the need for a complex screen cleaning procedure. Normal debris also flows through the coarse screen and the screw. The coarse screen is cleaned by occasional back-flushing. For this we install our screen back-flushing system which is protected as a utility model.

The principle is good for fish
These systems are not just successful in terms of energy efficiency. Fishery biological studies attest to the particularly high fish friendliness of the systems ,which meets high standards. Fish up to 60 cm in length are able to move downstream through the slowly rotating hydropower screw unharmed. Unlike in fast rotating turbines, they simply swim between the screw volutions.

Case studies

  • Hydropower screw SH, Untermünkheim - Germany
  • Hydropower screw CR, Haddo - Ireland
  • Hydropower screw CR, Bischofsmais - Germany