The power station uses the
hydraulic head of about between the
Walchensee (acting as the upper reservoir, at above sea level) and the
Kochelsee ( a.s.l.) to generate electricity. Through six, ducts connecting the two natural lakes, the water flows to the hydro-electric plant's four
Pelton water turbines with
single-phase generators, which power
the German railroad network. Then it flows through four
Francis water turbines with three-phase generators, linked to the European grid, and exits into the Kochelsee. Because the water level constantly changes, neither lake fully freezes in the winter; what does freeze on the lakes is potentially hazardous thin ice. The natural outflow of the Walchensee at Niedernach — over the Jachen to the River
Isar — is blocked by a
weir, but the natural inflow to the lake is still insufficient to provide enough water to the reservoir for the operation of the power station, so the waters of the
Rißbach river are also used.
Isar transfer The Isar, which flows as a whitewater river from the Austrian part of the
Karwendel mountains, is dammed between
Mittenwald and
Krün by a weir to form the Krüner Isar reservoir () and is then diverted to the Walchensee. This water flows past the Krün hydroelectric plant in an open channel, through a culvert, under the B 11 road at
Wallgau and then via a tunnel to the Sachensee lake (). Here a 3.9 kilometer long
penstock begins. At the end the water enters the hydro-electric power plant at (), propels the turbines, and finally flows into the lake.
Rißbach transfer The Rißbach comes from the northern part of the Karwendel mountains, where it gathers the water of smaller streams in the Ahornboden area. After crossing the border between Tirol and Bavaria, and immediately after the inlet of the Fermersbach, a 6960 m
adit carries water to the hydro-electric power plant at Niedernach at the southeast end of the Walchensee. The power station has been in operation since 1951. ==History==