Sultartangi Power Station

Sultartangi Power Station utilises water from both the Þjórsá and Tungnaá rivers, which meet in Sultartangalón reservoir above the station. Water from the Tungnaá has already passed through Sigalda and Hrauneyjafoss Power Stations before reaching Sultartangi, making the station an important link in the interconnected hydropower system of the Þjórsá and Tungnaá area.

Sultartangi Dam is the longest dam in Iceland, stretching 6.1 km. The reservoir covers approximately 20 km² and supplies water to the station through a 3.4 km headrace tunnel running beneath Sandafell. Two penstocks carry the water to the turbines before it is discharged through a tailrace canal and returned to the Þjórsá riverbed downstream.

The Þjórsá and Tungnaá area is home to seven of Landsvirkjun’s hydropower stations: Búðarháls, Búrfell, Búrfell II, Hrauneyjafoss, Sigalda, Sultartangi and Vatnsfell. The area also includes Vaðalda Wind Farm, Iceland’s first wind power plant, as well as Hafið, a wind energy test site with two experimental turbines.

At the heart of the system is Þórisvatn, Iceland’s largest natural lake and the region’s main reservoir. Water collected in the Kvíslaveita diversion system and Hágöngulón flows through Þórisvatn before being used by power stations farther downstream.

The Þórisvatn reservoir system was developed between 1970 and 1972 as part of the expansion of hydropower generation in the area. Its reservoirs, dams, canals and control structures make it possible to store water, regulate flows and optimise energy production throughout the year.

Construction of the Kvíslaveita diversion system began in 1980 and was completed in 1997. The system collects water from tributaries and the upper reaches of the Þjórsá River and diverts it to Þórisvatn.

Hágöngulón was developed between 1997 and 1999 and covers an area of 37 km². It increases the utilisation of water resources in the Kaldakvísl catchment by storing water during the summer months.

Together, Þórisvatn, Kvíslaveita, Hágöngulón and a number of smaller reservoirs form the backbone of the hydropower system in the Þjórsá and Tungnaá area.