Plant Description

The small hydropower plant is located on the Feistritz River and is of the diversion type. A reservoir being created by a gravity concrete dam is located approx. 1.5 km upstream of the discharge point into the Feldaist.

The intake building is situated on the orographic right hand side and accommodates the trash rack. A dip board is placed at its entrance to prevent floating material from entering the building. The trash rack located in the building is equipped with a mechanical cleaner. The headrace tunnel starts right behind the trash rack.

The 194 m long headrace tunnel has the shape of an inverted U-profile with a height of 140 cm high and a bottom width of 90 cm. Most of it is plastered, some is concrete lined. It passes below a forest, then the Lasberger Provincial road and ends at the surge tank. Hydraulically, the tunnel is a free surface flow system with a minimum gradient, but fully filled towards its end.

The surge tank is of the vertical cylinder type with a square floor area. Its appearance is rather characteristic due to its cubicle proportions and the doomed roof. Consequently it has been declared to a protect worthy “technical monument”.

The 181 meter long penstock leads from the surge tank to the power house. It is a steel pipe of 740 mm diameter. A bifurcation pipe right in front of the power house separates the flow into two pipes of 530 mm diameter, feeding the two generation sets. Both feeder pipes are equipped with flap valves.

Two power generation sets are installed in the power house with capacities of 100 kW and 200 kW. The turbines are of Francies type. The different sizes permit to run the plant at optimum efficiency at varying water flows. In parallel operation, the plant reaches an output capacity of 300 kW.

Water leaves the turbines through the suction pipes which permit the exploitation of the suction head for energy generation. The tailwater runs through the 300 meter long tailwater channel and discharges into the Feldaist at its orographic left hand side.

The electric energy produced is supplied into the public power grid of the Linz AG. The average annual energy production is 1,200,000 kWh but logically varies according to the hydrological conditions in every year.

The power plant is able to cover the electricity demand of 400 households with clean and renewable energy. This is equivalent to 40% of the households of the Municipality of Lasberg.