Sultartangi Hydropower Station
Sultartangi Station, on the edge of Iceland‘s southern central highlands just inland from Mt. Búrfell, is Landsvirkjun‘s newest power station. It harnesses the same water as the Hrauneyjafoss and Sigalda Stations, as well as the river Thjórsá. Thus it is less dependent than most power stations on hydrological fluctuations - the same, in fact, is true of the Búrfell Station.
Sultartangi Station stands beneath the Sultartangi dam, which was formed at the confluence of the rivers Thjórsá and Tungnaá. Local people call the area around the station Bláskógar (Blue Woods). The origin of this name is uncertain, since the area is bare of trees today, although this could suggest that it was wooded in earlier times.
On the highland route along the road beyond Thjórsárdalur valley, the Sultartangi Station is one of the first buildings that comes into sight. The powerhouse is set into the side of the mountain and is therefore invisible from outside the site, although the switchgear yard and house can be seen from some distance away. Many interesting sightseeing spots are found in the vicinity of the station, such as Háifoss waterfall. Sultartangi is within close reach of the southern lowlands and attractions there such as Galtalækjarskógur, a wooded campsite at the foot of the volcanic Mt. Hekla.
In the other direction, towards the highlands, the road leads to Hrauneyjafoss power station, the Veidivötn lake cluster, the north-south central highlands route across the Sprengisandur desert, and many other interesting places for travellers. The station intake at Sultartangi is decorated with Sigurdur Árni Sigurdsson‘s artwork Sun-Dune, which was chosen from several designs. Based on shadow play, the work casts different images onto the station wall depending on the position of the sun. The most impressive play of shadows is during the summer solstice, when the sun is at its highest point.
Highlights from Sultartangi‘s history
The rivers Thjórsá and Tungnaá were dammed in 1982-1984 at the eastern foot of Mt. Sandfell approximately 1 km upstream from their confluence. From the foot of Sandfell, the dam lies across the course of the Thjórsá, then continues eastwards across Sultartangi and the course of the Tungnaá towards Hald on its south bank. Water which collects behind the dam in the Sultartangi reservoir has been diverted along the course of the Thjórsá to the Búrfell station.
Construction work at Sultartangi Station began in spring 1997 and went into full swing in spring 1998.
Harnessing arrangements
At 6.1 km, the Sultartangi dam is the longest in Iceland. In conjunction with the construction of the power station, the dam crest was raised by 1.0 metre, increasing the reservoir area from 18 km² to 20 km². At the western end of the dam, on the bank of the river Thjórsá, is a bottom outlet with a gate structure. West of the outlet, up from the gate, is a short headrace to the intake at the 3.4 km tunnel leading to the station. The tunnel runs through Mt. Sandfell towards a surge basin on its southwestern side, enclosed by earth dams on three sides.
At the end of the surge basin is the station intake, where penstocks lead down to the powerhouse. Two 60 MW Francis turbines drive the generators. Access is from the Thjórsárdalur road on the eastern side of the tailrace canal.
Transmission lines run from the powerhouse via a 180 m tunnel to the switchgear house on its western side which contains SF6 isolated phase buses. The 220 kV transmission line from Hraunejyarfoss Station to the relay point at Brennimelur is linked up to the switchgear house, and a new 400 kV line was also laid from it to Búrfell Station.
A tailrace canal exits the powerhouse at the foot of Mt. Sandfell and extends via Mt. Álftafell to Haf. Measuring just over 7.2 km in length, the canal curves towards the course of the river Thjórsá, following it to a spot 800 m up from the Búrfell dam on the edge of the river.