Hydroelectric power is an important renewable energy resource but it is not without an environmental cost. Water diversions engineered for conventional run-of-river power plants disrupt aquatic ecosystems and can damage riverbanks. A more ecologically benign approach to hydropower system design developed by Technical University of Munich engineers is now being demonstrated in Germany.

The facility constructed on the River Loisach in Bavaria is the world’s first shaft hydropower plant, featuring a turbine concealed in a shaft in the riverbed upstream of a weir. After entering the shaft and driving the turbine, the water returns to the river beneath the weir, eliminating the need to divert the river’s course. The design Fish can migrate downstream through openings in the weir. Source: Frank Becht/Technical University of Munich provides for safe fish passage over the shaft while weir openings facilitate downstream migration and a conventional fish pass affords upstream migration.

Two shafts were excavated at the site, which has a fall height of 2.5 m, in an arrangement which allows debris and driftwood to pass more freely downstream. A rack on the shaft keeps this material away from the turbine and the bedload is regularly pushed downstream through a gate opened in the weir, which allows water to be released when the river floods.

The grid-connected system currently produces enough electricity for approximately 800 households and the technology can be implemented for different sizes of river and different fall heights. Twelve such plants are being planned in Germany by Hydroshaft GmbH, a spin-off from the university.