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Grande Dixence Dam

Grande Dixence Dam
File:GrandeDixence.jpg
Location of Grande Dixence Dam
Location Hérémence, Switzerland
Coordinates

46°04′50″N 07°24′14″E / 46.08056°N 7.40389°E / 46.08056; 7.40389Coordinates: 46°04′50″N 07°24′14″E / 46.08056°N 7.40389°E / 46.08056; 7.40389{{#coordinates:46|04|50|N|07|24|14|E|type:landmark |primary |name=

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Status In use
Construction began 1953
Opening date 1964
Operator(s) Grande Dixence SA
Energie Ouest Suisse
Dam and spillways
Type of dam Gravity dam
Impounds Dixence River
Height Script error: No such module "convert".
Length Script error: No such module "convert".
Width (base) Script error: No such module "convert".
Dam volume Script error: No such module "convert".
Reservoir
Creates Lac des Dix
Total capacity Script error: No such module "convert".
Catchment area Script error: No such module "convert".
Surface area Script error: No such module "convert".
Max. water depth Script error: No such module "convert".
Power station
Commission date 1965, 1998
Installed capacity 2,069 MW
Annual generation 2,000 GWh

The Grande Dixence Dam is a concrete gravity dam on the Dixence River at the head of the Val d'Hérens in the canton of Valais in Switzerland. At Script error: No such module "convert". high, it is the tallest gravity dam in the world and is part of the Cleuson-Dixence Complex. With the primary purpose of hydroelectric power generation, the dam fuels four power stations, totaling the installed capacity to 2,069 MW, generating approximately 2,000 GWh annually, enough to power 400,000 Swiss households.

The dam withholds Lac des Dix (Lake Dix), its reservoir. With a surface area of 4 km², it is the second largest lake in Valais and the largest lake above 2,000 m in the Alps. The reservoir receives its water from four different pumping stations; the Z’Mutt, Stafel, Ferpècle and Arolla. At peak capacity, it contains approximately Script error: No such module "convert". of water, with depths reaching up to Script error: No such module "convert"..[1] Construction on the dam began in 1950 and was completed in 1964, before officially commissioning in 1965.

History

File:Dixence-Staumauer.jpg
The Grande Dixence Dam in 2004, facing west and Mont Blava

In 1922, Energie Ouest Suisse (EOS) became established with a few small power stations. To generate substantial amount of electricity, EOS looked to the Valais canton which contains 56% of Switzerland's glaciers and stores the largest amount of water in Europe. In 1927, EOS acquired the license for the upper Dixence basin. In 1929, 1,200 workers constructed the first Dixence dam which would be complete in 1935. The first dam would supply water to the Chandoline Power Station which has a capacity of 120 MW.[2]

After the Second World War, growing industries needed electricity and construction on the Cleuson Dam began in 1947 and was completed in 1951. Plans for the Super Dixence Dam were now being finalized by the recently founded company, Grande Dixence SA. Construction on the Super Dixence Dam soon began later in 1950. By 1964, 3,000 workers had finished pouring Script error: No such module "convert". of concrete, completing the dam. The original Dixence dam was submerged by the filling of Lac des Dix beginning in 1957, it can still be seen when the reservoir level is low.[2]

In the 1980s, Grande Dixence SA and EOS began the Cleuson-Dixence project which improved the quality of electricity produced by building new tunnels along with the Bieudron Power Station. By the time the Cleuson-Dixence Complex was complete, the power generated had more than doubled.[2]

The construction of the dam was documented in the short film Opération béton, the first film directed by Jean-Luc Godard.

Characteristics

File:BarrageDeLaGrandeDixenceFaceValee.JPG
The dam as seen from downriver

The Grande Dixence Dam is a Script error: No such module "convert". high, Script error: No such module "convert". long concrete gravity dam. The dam is Script error: No such module "convert". wide at its base and Script error: No such module "convert". wide at its crest. The dam's crest reaches an altitude of Script error: No such module "convert".. The dam structure contains approximately Script error: No such module "convert". of concrete.[1] To secure the dam to the surrounding foundation, a grout curtain surrounds the dam, reaching a depth of Script error: No such module "convert". and extending Script error: No such module "convert". on each side of the valley.[3]

Although the dam is situated on the relatively small Dixence River, water supplied from other rivers and streams is pumped by the Z’Mutt, Stafel, Ferpècle and Arolla pumping stations. The pumping stations transport the water through Script error: No such module "convert". of tunnels into its reservoir, Lac des Dix. Water from the Script error: No such module "convert". high Cleuson Dam, located Script error: No such module "convert". to the northwest, is also transported from its reservoir, the Lac de Cleuson. Three penstocks transport water from Lac des Dix to the Chandoline, Fionnay, Nendaz and Bieudron power stations, before being discharged into the Rhône River below.[4] All the pumping stations, power stations and dams form the Cleuson-Dixence Complex. Although the complex operates with water being pumped from one reservoir to another, it does not technically qualify as a pumped-storage scheme.[5]

Most of the water comes from glaciers when they melt during the summer. The lake is usually at full capacity by late September, and empties during the winter, eventually reaching its lowest point around April.

Power stations

Chandoline Power Station

The Chandoline Power Station was the power station for the original Dixence Dam. The Grande Dixence Dam submerged the original dam but the power station still operates with water received from the reservoir of the Grande Dixence Dam, Lac des Dix. The power station is the smallest of the four, producing 120 MW from five pelton turbines with a gross head of Script error: No such module "convert"..[6]

Fionnay Power Station

The Fionnay Power Station receives water from the Grande Dixence Dam by a Script error: No such module "convert". long tunnel with an average gradient of 10%. Once the tunnel reaches a surge chamber at Louvie in Bagnes, it turns into a penstock which descends at a gradient of 73% for Script error: No such module "convert". until it reaches the power station. The water, now flowing at a maximum rate of Script error: No such module "convert". spins six pelton turbines, generating a combined maximum capacity of 290 MW.[7]

Nendaz Power Station

After arriving at the Fionnay Power Station from the Grande Dixence Dam, water then travels through a Script error: No such module "convert". pressure tunnel which eventually leads into the Péroua surge chamber, Script error: No such module "convert". above the Nendaz Power Station. The water, which remains at a maximum rate of Script error: No such module "convert". spins six pelton turbines, generating a combined maximum capacity of 390 MW.

The Nendaz power station is located within mountains between Aproz and Riddes and is the second-largest hydroelectric power station in Switzerland after the Bieudron Power Station.[8]

Bieudron Power Station

The water travels down a long penstock from the Grande Dixence Dam before reaching the Bieudron Power Station Script error: No such module "convert". down. The water spins three pelton turbines, generating a combined capacity of 1,269 MW.[9] The power station was constructed after the Nendaz and Fionnay power stations. The power station was built by both Grande Dixence SA and Energie Ouest Suisse between 1993 and 1998 at a cost of US$1.2 billion.[9]

The Bieudron Power Station alone holds three world records, for the height of its head (Script error: No such module "convert".), the output of each Pelton turbine (3 × 423 MW) and the output per pole of the generators (35.7 MVA). It was taken out of service in December 2000 after the rupture of a penstock. The power station became partially operational in December 2009 and fully operational in 2010.[2][9][10]

Notes and references

External links