When Landsvirkjun was established in 1965, it embarked on the construction of the Búrfell Hydropower Station, which came on-line in 1969. It took almost ten years to complete the construction and it was the largest power station in the country until the inauguration of Kárahnjúkar Hydropower Station in 2007.
The River Thjórsá is harnessed at Búrfell with a tailrace tunnel from the Bjarnarlón Reservoir to the powerhouse located in the Thjórsárdalur Valley. The River Thjórsá, which previously flowed south of Mountain Búrfell, is diverted above the mountain into Bjarnarlón Reservoir, and from there through a tunnel passing through the basalt strata of Sámstadamúli into the Thjórsdárdalur valley.
The diversion system in the riverbed of Thjórsá is equipped with a special icebarrier structure. In earlier years, the role of the ice barrier structure was to rinse aside ice and slush to prevent it from reaching the Bjarnarlón Reservoir. Today, the flow rate of the river can be better managed and with the construction of a canal between the Sultartangi and Búrfell stations the amount of ice and slush has been reduced. The need for the structure has therefore been greatly diminished.
From the powerhouse turbines, the water exits via draft tubes into a short canal before entering the River Fossá, which joins the River Thjórsá 2 km downstream. The station’s equipment was partially renewed in 1997-1999. This increased the station’s installed capacity to 270 MW, from 210 MW.
There are six hydropower stations in the catchment area of Rivers Thjórsá and Tungnaá: Búrfell, Sultartangi, Hrauneyjafoss, Vatnsfell, Sigalda and Búdarháls, with combined energy of 935 MW. Water for all the power stations is provided by three main reservoirs, Thórisvatn, Hágöngulón and Kvíslarveita, along with smaller reservoirs connected with each station.
Lake Thórisvatn, Iceland’s largest lake, is the largest reservoir and an important part of Landsvirkjun’s utility system. All water accumulated in Kvíslarveita and Hágöngulón reservoirs runs through Lake Thórisvatn.
Lake Thórisvatn became a reservoir with the harnessing of River Thjórsá at Búrfell Mountain in 1970-1972. River Kaldakvísl was diverted into the lake at the northern edge of the lake and a controlled outflow constructed at the southern edge.
A canal was dug from the lake and a concrete gate structure built in the canal to manage the flow rate. The canal is named the Vatnsfell Canal, and carries water from Lake Thórisvatn through the Vatnsfell Station into the Krókslón Reservoir above the Sigalda Station, and from there to other stations further down in the catchment area.
Work on the Kvíslaveita Reservoir began in 1980 and was completed in 1997. Kvíslaveita is the collective name for the dams, canals, bottom outlets and gate structures that manage the flow rate from the River Thjórsá and its tributaries into Lake Thórisvatn.
The Háganga Reservoir was constructed in 1997–1999 and covers an area of 27 km2. Its purpose is to increase the efficiency of the catchment area of River Kaldakvísl. During the summer months, water accumulates in the Hágöngulón Reservoir, with very little water flowing down the Kaldakvísl riverbed.
|Vatnasvið virkjunar:||6.400 km2|
|Virkjað rennsli:||260 m3/s|
|Afl, 6 Francis hverflar 45 MW hver:||270 MW|
|Orkuvinnsla árið 2000:||2.093,23 GWst|
|Stífla yfir Þjórsá:||370 m löng|
|Hönnun:||Harza Engineering Co Int., Bandaríkjunum|
|Arkitektar stöðvarhúss:||Guðmundur Kr. Kristinsson|
|Framleiðendur háspennulína:||Garczynski & Traploir, Frakklandi|
|Brown Boveri & Cie, Þýskalandi|
|Balfour, Beatty & Co., Bretlandi|
|Framleiðendur hverfla og rafala:||Toshiba, Japan|
|Endurnýjun tengivirkis:||Siemens, Þýskalandi|