Types of Energy
Types of Dams
Table Camparison of dams
The Power Stations
Types of Turbines
The Transport of Electricity
The Future of Hydroelectricity

Through the visits of the various dams and the related infrastructures, La Torpille found that the adventure of hydro-electricity is exciting. This page tries to give a summary of it. Since La Torpille does not have infused science, the information presented here is based on the Internet and whose sources are indicated at the bottom of page but also information gleaned during the visits. If you have any comments or concerns about this article, please do not hesitate to contact us.


Electricity, an energy vector, has revolutionized the way machines have been operating since the early 1900s, and it is now completely part of our daily lives and it is no longer possible to do without them. Electricity can be produced by many sources of energy such as solar, wind, hydro or nuclear. At present, the vast majority of electricity in Switzerland is produced by nuclear power (38%) and hydroelectric power (57%), while at the global level it is clearly fossil fuels (oil, gas, coal). Solar power (1.2% in Switzerland) and wind power (0.1% in Switzerland) are promising but remain far behind in terms of electricity production.

The world’s largest wind farm in Gansu, China. Its total power should reach 20GW in 2020 (Great Dixence 2GW). Photo Flickr Tim Zachernuk.

A solar farm in Ukraine. Photo Flickr “Activ Solar”.


In the case of dams, of course, we are dealing with hydroelectricity, where electricity is generated by the force of water that drives a turbine (see below). This is one of the oldest techniques for generating electricity on a large scale. The higher the flow and the water velocity, the greater the force or quantity of water on the turbine will be and therefore the better the electricity production. In order to increase the speed, the greatest difference in height between a reservoir and the turbine is required, and this is where the dam, which holds the maximum of water as high as possible at high altitude, intervenes. The maximum flow is obtained by slogging the water of a river (in the course of the water), in this case the speed will be low but one will benefit from the broadband. In Switzerland, hydraulic power stations are either run-of-the-river, accumulating (dams), or pumping-turbines. Running and storage plants produce the same amount of electricity annually in Switzerland (17,000 GWh), but the accumulation plants have much more power than the run-of-river power stations, 8,000 MW compared to 3,500 MW. Indeed, the accumulation plants operate less consistently. The pumped-turbine power stations (see below) produce 1300 GWh / year for a power of 1500 MW are to develop. These figures are provided by the Swiss Federal Office of Energy (SFOE) and relate to power stations over 0.3 MW. It should be noted that the smaller installations can have their utility such as by turbines “free” the excess pressure of a drinking water supply installation.

Which are the advantages of hydroelectricity?

Hydro-electricity is often considered “green” energy, meaning its energy source, water, is recyclable and does not emit harmful emissions such as CO2 (coal ) Or radioactive waste (nuclear). Solar and wind are also considered “green” but have the disadvantage of being related to weather conditions. However, it would be wrong to say that hydroelectricity does not emit greenhouse gases because dam reservoirs contain microorganisms that decompose organic substances and produce CO2 and methane. A paragraph is dedicated to this aspect below.

Another little known advantage of the electricity produced with the water of a dam is the possibility of strongly modulating its injection in the network as a function of needs and in particular at the time of high consumption, which is particularly useful because electricity cannot be stock in large quantities. The famous Bieudron power station, near Sion in Valais, allows to mobilize its 1200 MW power from the stop to full power in less than 3 minutes to produce the peak energy. A nuclear power station or a run-of-river power station will have to produce electricity in a constant manner ensuring the “background noise” of consumption or energy in ribbon.

→ Which are the disadvantages of hydroelectricity?

The disadvantages of hydroelectricity are its environmental impacts. A dam, especially at a river or river level, will deplete biodiversity, for example by cutting water circulation for fish. Dams in high mountains dry up streams that disrupt the ecosystem. The construction of a dam can affect the population by forcing it to move and cause landslides on newly flooded areas. Fortunately, in Switzerland, dams are mostly built outside the residential areas and affect the environment reasonably, although dams such as Schieffenen and Rossens on the Sarine cause significant disturbance to the ecosystem. Schieffenen and Rossens, in addition to having swallowed agricultural land and forced people to leave their village, cut off the circulation of fish, which is not the case with Mauvoisin and Grande Dixence. In other countries, ecological considerations are still hardly taken into account, as for the dam of all the superlatives, the Three Gorges Dam in China, which forced 1.5 million people to travel and Amount of arable land. Species have even disappeared as a species of river dolphin. A significant increase in the number of small earthquakes has been observed since the impoundment of the dam and worse still some believe that the earthquake of May 12, 2008 causing 87’000 victims was caused by the mass of the dam pressing on a dam seismic fault. Moreover, this mass is about 50 billion tons that it has modified the distribution of the mass of the Earth with respect to its axis of rotation and has lengthened the rotation time of 0.06 microseconds.

Dams on rivers also have the disadvantage of hindering the movement of boats. To solve the problem, locks are set up to allow the obstacle to be crossed. At the level of the Trois Gorges Dam (still it!), the difference in height is so great (over 100m) that “monstrous” boat lifts are in use rather than locks. They lift boats as well as water that allow them to float.

The dams of Schieffenen, Rossens, Mauvoisin and Grande Dixence.

As for the Itaipu dam on the border between Brazil and Paraguay, where the hydroelectric infrastructure is the second most powerful in the world, the impoundment of the dam disrupted a natural wonder, the Cascade Of the Seven Falls which is until 1982 the date of its disappearance the most important waterfall of the world in term of water flow. The electrical infrastructure linked to this dam is the second most powerful behind that of the Trois-Gorges but the annual current produced is equivalent between the two infrastructures at about 100 TWh.

The Itaipu dam. Photo Flickr Myben.be

The case of the monstrous Aswan dam on the Nile is interesting. This huge gravity type dam is built to produce energy, but also to prevent flooding and to alleviate droughts. Its dimensions are impressive, with a volume of 42 million cubic meters of earth and rockfill, a capping length of 3800 m, a dam width of nearly one kilometer and a reservoir of 169 billion cubic meters. All these figures are considerably higher than those of the Three-Gorges dam, but at the same time the Aswan dam produces much less electricity, its power (2 Gw) and its annual electricity production (8 TWh) are 10x less than Those of the Three Gorges.

Unfortunately, the negative consequences on the environment of this dam, built during the Cold War are numerous. In addition to the swallowing of historical monuments or the more significant reflux of salt water on the Nile, the most interesting case is the retention by the dam of fertilizer silt, which has been used to grow crops on the Nile plain for millennia. This results in the use of fertilizers by farmers. Another phenomenon caused by the dam, the alteration of the currents at the level of the Suez Canal, increasing the intrusion of the Red Sea fauna, often intrusive, into that of the Mediterranean. Some experts question the usefulness of this dam (and even that of the large dam in general) considering that the disadvantages are superior to the advantages that it brings.

The downstream side of the Aswan Dam in the middle of the desert. Photo Flickr J. Griffin Stewart.

Finally, a last known disadvantage is the release of methane gas, a greenhouse gas much more powerful than CO2, by the retaining lakes. The organic material in water is decomposed in layers low in oxygen by bacteria which transforms it into methane and CO2. The release of methane depends on several factors such as the amount of organic matter, water temperature or depth of the reservoir. The figures of actual methane emissions from dams are still unclear, but they would appear as the Alpine dams are only slightly affected by these emissions, which are not dams in the tropics or the equator at low altitude where the studies provide figures still very different. Some figures indicate that dams in these latter areas would emit up to 20% of human-induced methane, which would mean that dams are not as “clean” as often described, while other studies tend to Opposite values ​​with more symbolic figures compared to the release of methane.

Types of Energy:

Energy in the dam is stored as potential energy. When it flows from the barrier in the form of water into the forced pipe, it gains momentum and transforms into kinetic energy. A turbine converts the kinetic energy into mechanical energy and then the latter is in turn transformed into electrical energy by an alternator that operates in the opposite direction to the turbine. Electricity goes into high-voltage lines using a transformer.

The problem with electricity is that it cannot be stored directly in large quantities despite decades of research. This is where the advantage of the dam that stores this electricity indirectly increases the accumulation of water in the form of potential energy. A pumping station-turbine, like that of the Nant de Drance at the dam of Emosson, makes it possible to slog the water during periods of high consumption and thus to produce electricity and, on the contrary, during periods of low consumption to store it in the Pumping between two reservoirs of water of different altitude. In the case of Nant de Drance, the water rose from the Emosson dam to the Vieux-Emosson dam 300 meters higher. Pumping-turbine thus transforms electricity into potential energy, yield is about 80%, which means that for 100 units of energy used to go up the water, 80 will be produced. It should be noted that the price of the energy used to raise the water is often much less than that which can be sold with the turbine because it will be ensured to produce electricity when the demand is high.

→ In summary:

Dam = Potential Energy → Forced Driving = Kinetic Energy → Turbine = Mechanical Energy → Alternator = Electricity


Switzerland has a large number of dams mainly located in the Alps and especially the canton of Valais. The king of the dams is that of Grande-Dixence because of its height (285m) and the phenomenal amount of concrete that composes it. It remained for a long time the highest in the world before being surpassed by 3 other dams. Currently, a Chinese dam, the Jinping I dam with its 305m is the highest in the world. The dam generating the most electricity is that of the Three Gorges as indicated above.

The use of concrete allows the dams to rise from the end of the 19th century with in 1872 the first concrete dam in Europe in Pérolles in the canton of Fribourg. The Hover Dam (Hover Dam), along the Colorado River in the United States, was built in the 1930s during the Great Depression and is the first large dam ever erected with 220m height. It is remarkably constructed in only 4 years in technological and human conditions much more difficult than those which one could have of these days. It is currently still functioning and at the same time a tourist attraction with 1 million visitors per year.

The Hover dam. Flickr Photo Graham McLellan

Are we sure of the strength of a dam?

Nowadays, breaking a dam is a virtual possibility due to the monitoring and verification technologies in force, it would even be possible to empty the dam as soon as disturbing signals appear as was the case for the Tseuzier dam in 1978 which was damaged by underground soundings. In the past in the early 1960s, there were two catastrophes. The first (1959 – 423 dead) is the rupture of the Malpasset dam in France releasing 50 million m3 of water due to high flooding and multiple design failure as an anchor defect in the rock. The second (1963 – 1900) dead at the Vajont dam in Italy near Venice was not due to the breaking of the dam but to an enormous landslide in the dam reservoir which caused the overflow of 25 million m3 of water. The dam remains intact after the disaster but is subsequently decommissioned. Another threat could come from an earthquake that would cause a dam to break. Estimates have indicated that breaking the Great Dixence would cause a 37-meter-high wave in Sion, 2.5 meters in Martigny and another 2m in Villeneuve 6 hours later.

The remains of the dam of Malpasset and the dam of Vajont high of 261m, the highest of Italy. Photos Flickr Philpp Clifford (Malpasset) and BestKevin (Vajont).

When to visit a dam?

Valais dams must be visited in summer or early autumn as they are mostly inaccessible in winter due to the lack of snow clearing on the access road or avalanche risk. This is particularly the case for the three highest Valais dams, the Grande Dixence, Mauvoisin and Tseuzier dams. The month of September is on average the month when the deductions are filled to the maximum, whereas the opposite is the case in April where the deduction can only be filled to 10% of its capacity. Dams in the plain like those of Rossens or Schieffenen have a volume of filling which varies much less and are of course accessible all the year. Dams mainly produce electricity in the winter and early spring while they fill up with water the rest of the year.

Access to the dam of Mauvoisin closed at Fionnay level again in May due to the risk of avalanche

The dam of Tseuzier almost empty in early April and the dam of Mauvoisin filled in mid-September.

And here is a little exercise, what is the pressure exerted at the bottom of the Lake of the Ten, the dam of Grande-Dixence?

The simplified formula is the following: p = rho gh which is the pressure exerted on a point of the dam. Rho (pronounced rho) is the density, 1000 kg / m3 for water. G is gravity, 9.81 m / s2 and h is the height of the water above the chosen pressure point. Let us take a water height of 227m if the dam is completely filled and we therefore have a pressure of 1000 x 9.81 x 227 = 2’268’700 kg / s2 * m. This unit is equal to Pascal or N / m2. In summary, the force exerted on the dam increases with the height of water, this explains why the thickness of a dam is greater at its base than at its coronation. This is particularly striking on a weight barrier like that of the Grande Dixence where the thickness varies from 200m (!) Down to about fifteen meters at the top. It should be noted that the force exerted on the dam does not depend on the quantity of water in the reservoir.

Is a concrete dam Eternal?

No structure is eternal. In this case, there is not enough recoil to give a lifetime since the first concrete dams of importance were built since the late 1950s. Even if they resist remarkably well, a problem of swelling Concrete known as the “alkali-aggregate reaction” unknown at the time affected dams to varying degrees. To explain this reaction simply, it can be said that the concrete consists of a mixture of sand, pebbles, cement and water in precise proportions which hardens for a certain time after this mixing. In the agglomerate thus formed small spaces are constituted by water and air at high pH which will interact with the silica constituting the sand and the small pebbles of the concrete by increasing the pressure causing a swelling and then a cracking of the structure. This causes an alteration in the mechanical properties of the concrete.

The Salanfe dam in the Valais region was particularly affected by this problem, so that work had to be carried out in 2013. These works serve only to delay the propagation of the irreversible swellings of the concrete which has been vertically incised for 1 centimeter by the saw. The incisions close gradually.

Work on the Salanfe dam to fight against the swelling of the concrete. Image Flickr Alpiq

The Sixth Avenue Viaduct in Los Angeles, built in 1932, was demolished in 2016 due to particularly large alkali-granulate reactions, which weakened its structure in a sensitive seismic region.

A structure of the 6th Avenue viaduct degraded by the phenomenon of the alkali-aggregate reaction. Image Flikr

Some peculiarities of other dam in Switzerland and in the world.

The Valjont dam (261m) is the highest in Italy, Tigne (160m), the highest in France and Lake Oroville (231m) is the highest in the United States. The latter is experiencing a serious problem in February 2017. Following heavy rainfall, the weirs are used, causing erosion damage, the dam is not threatened, but water may cause the rupture of one of the damaged weirs causing a wave of nearly 10m. The situation returned to normal a few days later.

The last dam built in Switzerland is the Linthal dam. It is built in 2014 in the canton of Glarus and is the longest in Switzerland with a coronation of one kilometer long and the highest in altitude in Switzerland but also in Europe at 2500m. It is part of the Linthal Pumping-Turbine Plant which goes up the water of Lake Limmern 630m below.

The Three Gorges Dam has the most powerful hydroelectric infrastructure in the world but it is not the largest dam in the world, in this case the Tarbella dam in Pakistan. The latter consists mainly of earth and riprap in contrast to the concrete of Trois-Gorges. The Kariba Dam on the Zambesi in Africa, has the largest volume of water with 180 billion m3 or 4x more than the Three Gorges

Types of Dams:

→ Arch

Example: Dam of Mauvoisin, Emosson, Tseuzier, Rossens and Schiffenen

This type of elegant dam allows to rest part of the pressure of the water on the rock walls. It is less concrete consumer and requires a relatively small distance between the walls.

Some dams such as the Hongrin have a double vault, the two vaults are separated by a rock anchor. This dam is visible from Rochers de Naye at the Alpine Garden La Rambertia.

→ Gravity

Example: Grande-Dixence or Trois-Gorges Dam

The dam supports only the weight of the dam, of triangular shape in cross section perpendicular to the crown of the dam. It requires a large amount of concrete

→ Arch-gravity

Little used in Switzerland, dam allowing large widths saving concrete because the buttresses of the dam are in arch type

→ Dam or Embankment

Example: Mattmark

Dam consisting of rock or earth with a waterproof concrete or clay core. Much wider and limited in height than concrete dams.

Comparative Table of Dams

Seven dams were visited by La Torpille. In the table, the Three Gorges dam in China is added for comparison, it is the installation that produces the most energy in the world all energies combined.

See the geographical positioning of the dams visited.

BarragesGrande-Dixence petit drapeau du canton du valaisMauvoisin petit drapeau du canton du valaisEmosson petit drapeau du canton du valaisTseuzier petit drapeau du canton du valaisMoiry petit drapeau du canton du valaisHongrin petit drapeau du canton de vaudCleuson petit drapeau du canton du valais
Toules petit drapeau du canton du valaisRossens petit drapeau du canton de fribourgMontsalvens petit drapeau du canton de fribourgSalanfe petit drapeau du canton du valaisSchiffenen petit drapeau du canton de fribourgAubonne petit drapeau du canton de vaudTrois-Gorges (Chine)
Lien vers activitésLienLienLienLienLienLienLienLienLienLienLienLienLien
Photos des barragesbarrage de la grande dixence - hydroélectricité en suisse romandebarrage de mauvoisin - hydroélectricité en suisse romandebarrage d'emosson - hydroélectricité en suisse romandebarrage de Tseuzier - hydroélectricité en suisse romandebarrage de Moiry - hydroélectricité en suisse romandebarrage de l'Hongrin - hydroélectricité en suisse romandebarrage de Cleuson - hydroélectricité en suisse romandebarrage des Toules - hydroélectricité en suisse romandebarrage de Rossens - hydroélectricité en suisse romandebarrage de Montsalvens - hydroélectricité en suisse romandebarrage de Salanfe - hydroélectricité en suisse romandebarrage de Schiffenen - hydroélectricité en suisse romandebarrage d'aubonne - hydroélectricité en suisse romandebarrage des trois gorges - hydroélectricité en suisse romande
Construction [année]1953-19611951-19581967-19731953-19571954-19581966-19711947-19501955-19641944-19481919-19201947-19531961-19641954-19561994-2012
PoidsVouteVouteVouteVouteDouble VouteContrefortsVouteVouteVoutePoidsVoutePoidsPoids
Date mise en service [année]19611958197519571958197119511964194819201950196419562006-2009
Rang suisse
Rang mondial
123 (Nord) 95 (Sud)

Longueur [m]748520555256610325 (Nord)
272 (Sud)
Epaisseur base [m]19553.245263422?8020.528224014?115
Epaisseur couronne [m]15128773?3.5 à 54.553?57?40
Altitude Couronne [m]236419711931177722501255218718116708021925534561229
Courronnement ouvert aux voituresNonNonNonNonNonNonnonNonOuiOuiNonOuiNonNon
Evacuateur de crue [m3/s]Aucun10760366210014535543012.21000180
Volume réservoir [Mm3]400211227507752202022012.64058.60.063545'300
Superficie réservoir [km2]
Longueur réservoir [km]5551.
Volume Béton [1000*m3]6'0002'0001'100300814228 (Nord)
116 (Sud)
Déformation max [cm]1179762.47.53.2?
Galeries dans barrage [km]32
Bassin versant total [km2]420 (46 bassin versant direct)167 (198 avec bassin après barrage)175 (34 bassin versant direct)18.7MOTTEC
29 barrage moiry
36 barrage Tourtemagne
87: Navisence à Mottec
19: Torrent du Moulin
66: Navisence à Vissoie
TOTAL: 244
45 Adductions Est et Ouest
45 Hongrin et Petit-Hongrin
23 (16 bassin versant direct et 7 collecteur eaux du Tortin)78 (110 usine Orsière)95417331
(Salanfe 18, Saufla: 13)
Collecteurs [km]100env 13 (7.5 + 5.5)4720.825?00400
Nom du LacLac des DixLac de MauvoisinLac d'EmossonLac de TseuzierLac de MoiryLac du HongrinLac de CleusonLac des ToulesLac de la GruyèreLac de MontsalvensLac de SalanfeLac de Schiffenen?Lac des Trois-Gorges
Distance/Temps Tour du LacPas possible côté est
12km / 7h?
4.7km / 1h10m7.5km / 2h2022.5km / 5h304km / 1h1512.5km / 4h3050km/14h3510km / 2h45m7km / 1h45m?
RivièreDixenceDranse de BagnesBarberineLienneGougraHongrinPrintseDranse d'EntremontSarineJogneSalanfeSarineAubonneYangtze
Rivière résiduel en avalNonNonNonNonNonOuiNonNonOuiOuiNonOuiOuiOui
Nom SociétéGrande Dixence SA ou
Cleuson Dixence
Forces Motrices
de Mauvoisin SA
Electricité Emosson SA / CFFElectricité de la Lienne SAForces Motrices de la Gougra SAForces Motrices Hongrin-Léman SAEnergie de l'Ouest Suisse (EOS)Forces Motrices du Grand-St-BernardGroupe EGroupe ESalanfe SAGroupe ESEFAChina Yangtze Power
VisitableOui 15 francsSur rendez-vous GratuitSur Rendez-Vous 300 FrancsSur réservation
9 francs
NonSur Rendez-VousSur demande, Gratuit?Sur rendez-vous GratuitSur rendez-Vous GratuitSur rendez-vous GratuitN/A
Centrale 1 [MW]CHANDOLINE - 150
Extérieur - 160
MIEVILLE - 70 ExtérieurPIED DE BARRAGE 1 - 70
Photousine de chandoline - hydroélectricité en suisse romandeUsine de hydroélectrique de FionnayUsine de hydroélectrique de La BatiazUsine de hydroélectrique de MottecUsine de hydroélectrique de Veytaux IUsine de hydroélectrique de PallazuitUsine de hydroélectrique de Miéville
Turbinex? Pelton3 Francis2 Pelton verticales à 5 injecteurs de 80MW1 Pelton6 Pelton ( 3 alternateurs)4 Pelton (2 alternateurs)1 Pelton ?1 Francis 1.7 MW5x Francis2 Pelton verticales 35MW2x Kaplan14x Francis 700MW
Débit [m3/s]Arrêtée en 20133x 11.529m3/s0.453x 44x 8102267.21350.3
Longueur conduite [km]Galerie d'amenée: 4.7
Puit blindé: 0.6 ?
Galerie d'amenée: 9.8 + 0.27
Puit blindé: 0.92
environ 3.5Galerie d'amenée: 3.4
Puit Blindé: 1
Galerie d'amenée: 7.98
Puit Blindé: 1.22
Galerie d'amenée: 5.5
Puit blindé: 0.6
Hauteur de chute [m]180040062638868588348067100 variable1472 variable4590
Prise d'eauBarrageBarrageBassin de compensation de ChâtelardBarrageBarrage de Moiry et TourtemagneBarrageBarrageBarrageBarrageBarrageBarrageBarragebarrage
EcoulementRhôneBassin compensation Fionnay IRhôneBisse d'AyentBassin d'accumulation de MottecLac LémanBassin d'accumulationSarineSarineRhôneSarineAubonneYangtze
Année de mise en service1934 (Dixence)
1958 (Grande Dixence)
Centrale 2 [MW]FIONNAY - 290
CROIX - 66
PIED DE BARRAGE 2 - 2.5 ExtérieurPLAN-DESSOUS - 12 ExtérieurRIVE DROITE - 8400
PhotosUsine de hydroélectrique de FionnayUsine de hydroélectrique de Riddes/EconeUsine de hydroélectrique de VallorcineUsine de hydroélectrique de VissoieUsine de hydroélectrique de Veytaux IIUsine de hydroélectrique d'orsière
Longueur conduite [km]9Galerie d'amenée: 15
Puit blindé: 2.45
Galerie d'amenée: 1 + 0.5
Puit blindé: 1.1
[Puit blindé: 0.5/1.89]
Galerie d'amenée: 3.2
Puit blindé: 1.4
Galerie d'amenée: 6.9
Puit blindé: 0.9
Galerie d'amenée: 7.98
Puit Blindé: 1.22
Galerie d'amenée: 5.6
Puit blindé: 0.7
Turbine12 Pelton type horizontal (6 alternateurs)10 Pelton (5 alternateurs) ?3 Pelton vertical à 5 injecteurs de 64MW
[1 Francis 50MW]
2 Pelton type horizontal de 33MW6 Pelton (3 alternateurs)2 Pelton4 Pelton type verticale à 2 injecteurs ?4x Francis1x Diagonale1x Francis3x Francis12x Francis 700MW
Débit [m3/s]4510x 2.829
93x 42x 168750.5510
Hauteur de chute [m]8001000750
85534288338775 à 11045489790
Prise d'eauBarrageFionnayBarrage
[Les Esserts/Belle-Place]
BarrageBassin d'accumulation de Mottec et rivière navisenceBarrageBassin d'accumulation de PalauitBarrageBarrageBarrageBarragebarrage
EcoulementBassin compensation Fionnay II (166'000 m3)RhôneBassin de compensation de Châtelard-Frontière
Bassin de compensation de CroixBassin d'accumulation de VissoieLac LémanDranse d'EntremontSarineJogneSarineBassin centrale Plan-DessousYangtze
Année de mise en service1958197319582017?1948 (1902)201319642000 (1895)
Centrale 3 [MW]NENDAZ - 430
SEMBRANCHERPIED DE BARRAGE 1 - 0.6 ExtérieurLA VAUX - 3.5 ExtérieurCENTRALE 3 - 4300
Prise d'eauBassin compensation Fionnay IIChambre de compensation de Breney (En amont barrage)BarrageBassin de compensation de CroixBassin d'accumulation de Vissoie et rivière navisenceBarrageBassin centrale Plan-DessousBarrage
PhotoUsine de hydroélectrique de NendazUsine de hydroélectrique CFF du châtelardUsine de hydroélectrique de Navizence
Turbine12 Pelton type horizontal (6 alternateurs)1 pelton à 2 injecteur?3 Pelton horizontal à 1 injecteurs 11MW (I)
2 Pelton horizontal à 2 injecteurs 40MW (II)
2 Francis 17 MW6 Pelton (3 alternateurs)1 Francis1 Kaplan6x Francis 700W
2x Francis 50W
Débit [m3/s]452x 51610.53x 4110
Longueur conduite [km]16Galerie d'amenée: 4.1
Puit blindé: 0.9
Galerie d'amenée: 8.5
Puit blindé: 1.1
Hauteur de chute [m]1000350804420695674390
EcoulementRhôneBarrage MauvoisinBassin de compensation ChâtelardRhôneRhôneSarineAubonneYangtze
Année de mise en service19581925 (I) /1972 (II)1908 (2014)19762008
Centrale 4 [MW]BIEUDRON/RIDDES - 1200
PhotoUsine de hydroélectrique du BieudronUsine de hydroélectrique de ChampsecUsine de hydroélectrique CFF de Vernayaz
Turbine3x Turbine Pelton type vertical à 5 injecteurs2 Turbines Pelton3 Pelton à 2 injecteurs
27/40/40 MW
Débit [m3/s]751.217
Longueur conduite [m]Galerie d'amenée: 15.8
Puit blindé: 4.3
Hauteur de chute [m]1900550645
Prise d'eauBarrageChambre de compensation Les CreuxBassin de compensation de Châtelard
EcoulementRhôneDranse de BagnesRhône
Année de mise en service19981928
Station de pompageZmutt - 470m-86MW-17m3/sUsine Vallorcine
2x 9m3/s, 800m, 120 GWh/an
vers barrage Emosson
Mottec: pompe d'accumlation: 23MWVeytaux I
4 pompes, 32 m3/s
4 pompes de 1MW et 0.5 m3/sClusanfe
2m3/s, 0.88MW
Stafel - 212m-26MW-9m3/sUsine Châtelard II
31 MW, 4 m3/s, 800m
vers barrage Emosson
Veytaux II
32 m3/s
Gietroz du Fond
0.6m3/s, 1MW
Ferpecle - 212m (via Arolla) -21MW-8m3/s
Arolla - 312m-48MW-12m3/s
Barrage de Cleuson - 165m
Pompage turbinage [MW]En construction 2018
Nant de Drance 900
6 Francis 150 MW
2500Gwh ?
Production Total [GWh/an]2800 (2015)7001100
(800 ESA + 300 CFF)
240650Environ 1000230
(Palazuit 100 + 130 Orsière)
Puissance Total [MW]2700 (2015)400637
(410 ESA + 217 CFF)
(dont 60 de réserve)
(36 + 24)
Energie accumulée [GWh]660100
Drames/problème [année]19991818 (avant barrage)1978
DétailRupture CanalisationGlacier du GietrozGrâves fissures dans le barrage"Cancer" du béton
RecordsPlus haut barrage poids du monde
Plus puissante turbine pelton du monde
Plus haute chute d'eau
Plus haut barrage voute d'EuropePlus ancien barrage voute horizontale et verticale d'EuropePlus puissant barrage du monde

The Power Stations:

Surprisingly, the most generating facilities in the world are by far the hydroelectric complexes. The installation of the Three Gorges dam with a power of 22’500 MW and an annual output of 100’000 GWh comes to far ahead. The most powerful nuclear power plant is located in Canada with a capacity of 6300 MW for an annual production of 45’000 GWh. The Kashiwazaki-Kariwa nuclear power plant in Japan has a capacity of 8,300 MW but has been stopped since the 2011 earthquake as a precautionary measure and has not yet restarted in 2017. Many power stations produce electricity with other power plants, Other means but are less powerful than hydro or nuclear.

The Kashiwazaki-Kariwa power station at the seaside of Japan. Flickr photo of “IAEA Imagebank”.

As far as Switzerland is concerned, the Leibstadt power station, built in 1984, is the most powerful of the five nuclear plants built in Switzerland. Its power is 1200MW for a production of 10’000 GWh per year. The Beznau I nuclear power plant is the oldest active power plant in the world. Regarding a vote on energy developments in Switzerland, the people decide on 21 May 2017 the ban on the construction of new nuclear power plants.

The Mühleberg nuclear power plant in the canton of Berne built in 1972. It is the least powerful of the five power stations in Switzerland and one of the oldest in the world.

L’installation hydraulique de la Grande-Dixence, la plus puissante dans son secteur et composée de 3 centrales, est bien plus puissante que Leibstadt avec ses 2000 MW (1200MW pour le Bieudron) mais produit nettement moins d’électricité avec 2’000 GWh (Bieudron 1700 GWh) annuel que la centrale de Leibstadt. En effet la centrale nucléaire fonctionne en permanence et presque à plein régime ce qui n’est pas le cas pour la Grande-Dixence. En Suisse, l’immense majorité de l’électricité est produite par l’hydraulique (58%) et le nucléaire (38%). A noter que juste avant le construction de la première centrale nucléaire Suisse en 1969 , l’hydraulique représentait 90% de la production d’électricité en Suisse. A noter que la centrale électrique turbinant l’eau, non pas par accumulation comme au Bieudron, mais au fil de l’eau la plus puissante est celle de Verbois dans la canton de Genève le long du Rhône avec 98 MW et une production annuelle de 466 GWh. Une superbe carte répertorie les usines hydrauliques en Suisse sur le site de l’Office Fédéral de l’Energie (OFEN). Les centrales à accumulation (barrages) et celles au fil de l’eau représentent chacune 48% de la production hydro-électrique Suisse, le reste provient du pompage-turbinage.


Types of Turbine:

Three types of turbines are mainly used in hydroelectric production. The Kaplan, Francis and Pelton turbines were named after their respective inventors in the late 19th and early 20th centuries. No other efficient hydraulic turbines have been produced since these dates. Each turbine is adapted to different environments mainly depending on the height of the waterfall and the flow of water. The Kaplan and Francis turbines are referred to as “reaction”, that is, the inlet pressure in the impeller is greater than the outlet pressure, while the Pelton turbine is called “action” Ie the pressure at the inlet and at the outlet of the wheel is the same. We add here the turbine Deriaz very minority but observed as part of the visit of the dam Montsalvens.

Video comparing the Pelton, Francis and Kaplan turbines:

→ Pelton Turbin

The Pelton turbine owes its name to its inventor Lester Allan Pelton (1829-1908), an American carpenter by profession. It is the modern version of the paddle wheel used to turn the water of a mill in the Middle Ages until the beginning of the 20th century. At the time the water of a river was channeled and brought on a wheel taking water thanks to wooden shelves called vanes. The Pelton turbine operates on the same principle. It is made of an ultra-resistant metal mixture and receives water at very high pressure from one or more injectors on the central ridge of buckets resembling two shells of nuts or buckets allowing the water to escape The sides. This principle was patented by Pelton in the 19th century. The injection is tangential to the turbine wheel and may be horizontal or vertical using 1 to 6 injectors. Horizontal axis turbines have up to 2 injectors and up to 6 for vertical axis turbines. The kinetic energy of the water is transformed into mechanical energy after turbine and for maximum efficiency, the speed of the water after injection must be as low as possible, ideally zero.

Pelton turbines are less efficient than the Kaplan and Francis turbines due to their low surface area of water contact.

The most powerful Pelton turbine in the world is the Bieudron, near Sion in Switzerland. With a diameter of about 5m, it has a power of 423 MW and a record waterfall of 1883 meters with the Grande-Dixence dam. The Valais in Switzerland is particularly suitable for the use of Pelton turbines, which are particularly efficient at relatively low flows of less than 20m3 / s and waterfalls of over 400 meters. Indeed the bottom of the lateral valleys to the valley of the Rhone is often cashed and at more than 1500 meters of altitude allowing the construction of dams. Moreover, the lateral valleys are close and particularly high compared to the valley of the Rhone itself, less than 500 meters above sea level. The power stations built in the Rhone valley thus benefit from a large waterfall with relatively short forced pipelines.

The water velocity depends only on the height of the fall with the formula v = sqrt {2gh}. G being the earth’s gravity and varies slightly according to the places on earth and to the difference in height. What is the speed of the water coming from the Grande-Dixence dam on the Bieudron turbine? The height is 1883 m, g is equal to 9.81 m / s. Therefore, the square root of 2 x 1883 x 9.81 is equal to 192 m / s, which corresponds to the phenomenal speed of 691 Km / h. The turbine must therefore be very resistant and therefore it is machined by A robot in a single piece of metal. The speed of the turbine is equal to no loss at half the injection speed, that is to say at 345 km / h for the Bieudron. For the record, gravity varies according to where we are on Earth and is the lowest at the equator due to the centrifugal force due to the rotation of the Earth.

What is the rotation frequency of the wheel in turn / minute at Bieudron? The formula is: 60 x speed (m / s) / wheel diameter (m) x Pi, which is therefore 60 x 96 m / s / 4.6 mx 3.14 = 398 rpm.

A remarkable document with photos retraces the history of the Pelton turbine and its operation including a drawing of the forced pipe bringing water on the turbine with the injectors.

Wheel at dawn at the Museum of Iron and Railway in Vallorbe

The old Pelton turbines are often used as decoration objects at the entrance to power stations.

Old Pelton turbine, near the Vevey railway station, opposite the old Vevey engineering workshops where it was machined for the Neubrigg power plant in the Goms valley 


Turbine Pelton exhibited at the Riddes / Ecône plant where the waters of the Mauvoisin dam are turbined.


Turbine Pelton exposed in front of the administrative buildings of the Nendaz / Bieudron factory.

Turbine Pelton at the Miéville plant, next to the PisseVache.

Pelton in Fionnay at the level of the Grande Dixence plant

Pelton at the Champsec factory

Very small Pelton turbine at the Old Mills of la Tine in the Swiss canton of Valais.

Pelton inside the administrative building of the Orsière factory.

YouTube videos of the Pelton turbin:

→ Francis Turbin

It is the most powerful turbine model, it can produce nearly 700 MW, as at the Itaipu dam in Brazil and the Three Gorges dam in China. It is ideal for a large water flow and a waterfall of several hundred meters. For example, the water at the Mauvoisin dam is turbined by the Fionnay plant 400m down with the aid of 3 Francis turbines. The name of this turbine comes from its inventor James Bicheno Francis. It is an improvement of the turbine designed by Benoit Fourneyron, itself derived from the invention of Jean-Victor Poncelet in the early 19th century. The Francis turbine was commissioned for the first time in 1848. It is a submerged “reaction” turbine because the inlet pressure is greater than that at its outlet and its diameter can reach 10 meters for the largest models.

The water enters all around the turbine through a spiral pipe called spiral tarpaulin then guided radially towards the wheel and its dozen pales or blades. The steering vanes modulate the power of the turbine by making it possible to regulate the flow of water towards the moving blades of the wheel and thus to make it rotate more or less rapidly. The kinetic energy of the water and the energy from the pressure difference are transmitted to the alternator for the production of electricity. After passing through the turbine wheel, the water is then evacuated axially by the aspirator. Like the Pelton turbines, the Francis turbines can operate horizontally or vertically.

One of the enormous Francis turbines of 700W for the Three Gorges Dam costing $ 50 million and decorated in honor of China. Photo free of rights present on Wikipedia.

Turbine Francis in an oblique position at the Fionnay plant. It slogs the waters from the Mauvoisin dam for 40 years.


YouTube videos of the Francis turbin:

→ Kaplan Turbin

Invented by Viktor Kaplan and commissioned in 1912, the Kaplan turbine is particularly suited to strong water flow and a very low drop. Like the Francis turbine, it is a so-called “reaction” immersed turbine where the pressure at the inlet of the wheel is higher than at the outlet. This turbine resembles a propeller whose pales are steerable even in motion according to the flow of water which makes it interesting at the level of a river with variable flow. The Kaplan turbine can be 10m in diameter and weigh several dozen tons, it is the turbine that rotates the fastest, up to 1000 revolutions per minute. The waters of Lake Schieffenen are slogged at the foot of the dam by two Kaplan turbines with a cumulative power of 70MW.

Turbine Kaplan. Photo free of rights present on Wikipedia.

→ Deriaz ou Diagonal Turbin:

This turbine is suitable for small hydropower, its operating range includes flow rates from 0.1 to 10m3 / s and a net drop of about 20 to 80 meters. It operates at the foot of the dam of Montsalvens by slogging the residual waters of Jogne. It is a turbine very similar to the Kaplan turbine in its design and its operation is similar to that of the Francis turbine with a diagonal injection of water against the turbine.

→ Summary:

TurbinePeltonFrancisKaplanDiagonale ou Deriaz
TypeTurbine à actionTurbine à réactionTurbine à réactionTurbine à réaction
InventeurLester Allan Pelton (USA)James Bicheno Francis (USA)Viktor Kaplan (AUT)Paul Deriaz (SUI)
Puissance max en service [MW]423
Bieudron (SUI)
Itaipu (BRA)
Diamètre max en service [m]510155
Débit d'eau optimale [m3/s]moins de 25jusqu'à 700jusqu'à 8000.1 à 10 ?
Hauteur d'eau [m]plus de 40030 à 300jusqu'à 3020 à 65
Injection de l'eautangentielleradialeaxialediagonale
Vitesse de la turbine [tour/min]jusqu'à 36jusqu'à 400jusqu'à 1000
PoistionnementVertical ou horizontaleVertical ou horizontale?

The Transport of Electricity

In Switzerland, electricity is transported by SwissGrid, a 450-person company that manages the network and maintains it. Interesting statistics are available on the Swissgrid website. The company manages the electricity transmission network, which includes the 380kv high-voltage lines with a length of 1780Km and those of 220kv with a length of 4920km. The total of the very high voltage lines is 6700 km for more than 10’000 pylons.

The distribution network includes high (9000km), medium (45000km) and low (85000km) lines. Transformers provide conversion between different intensities. The high and very high voltage lines are very predominantly aerial whereas it is the opposite for the lines with medium and low voltages which are for the vast majority underground. The cost of burying a very high voltage line is close to 10x more expensive than that of an overhead line, but it improves the landscape and fauna as well as less vulnerability to the weather.

It is interesting to note that the loss of electricity during its routing is of the order of 6%. We learn that Switzerland with SwissGrid imports electricity mainly from France but also from Germany and Austria and exports to Italy.

Pylone and very high voltage lines between the substations of La Bâtiaz in Martigny and that of Châtelard to bring the electricity produced in the infrastructure of the dam Emosson.

What is the future of hydropower in Switzerland?

→ The cost of electricity

The cost of energy has fallen particularly in recent years for several reasons:

    • Liberalization of the energy market in Europe.
    • Arrival on the market of electricity produced by coal plants which benefit from the low cost of coal and that of CO2 emission.
    • Solar and wind generation in neighboring countries, especially Germany.

The price of the KWh on the European market is of the order of 3-4 cents to the purchase whereas that produced by the hydraulic double, that is to say 6-8 cents the KWh. It is sold between 10 cents and 40 cents per KWh to the final customer. The profitability of hydroelectric power in Switzerland is thus called into question. The closure of coal-fired power plants at European level and a strong economic recovery could change the situation and cause the price to rise on the European market but the price seems to remain very low for a while.

→ Global warming

Currently, global warming causes an increase in the amount of water available in dams by accelerating the melting of glaciers. It is estimated that around 2050, the situation will reverse with a significant decline in the water supply of glaciers due to their gradual disappearance. Some studies claim that glaciers in Switzerland will have almost completely disappeared around 2100, so the supply of water will only be provided by snowfall and rainfall, which is insufficient for dams. A solution could come from pumping-turbine where water is pumped into the dam during periods of low consumption. For example, one could imagine the pumping of water from the Rhone to fill the dam of Grande-Dixence.

Hydroelectricity in the world

Not surprisingly, China is the country that produces the most hydro-electricity in the world with more than a quarter of total production, in 2015 1126 TeraWatt / h. Brazil and Canada each produce around 10% of the world’s total with about 350-400 TeraWatt / h in 2015. The total power of China’s hydroelectric facilities is more than 300 GW, more than 22 for the Three -Gorges. By way of comparison, the facilities of the Grande Dixence have a power of about 2.5 GW. In Switzerland, the total hydroelectric production is 40 TeraWatt / h in 2015 for a 14 GW power generated by more than 600 power stations.

The share of hydropower in the world in relation to the total electricity produced is 16% in 2010. The total of 24’097 TW / a for 2’999 TW / a for hydropower. The countries that use hydroelectricity most are Norway almost totally (96%) as well as Brazil, Venezuela and Canada in a percentage between 60% and 70%. Switzerland arrives afterwards with 58%.

Pays producteurs mondiaux d'électricité en 2015

  • Total
  • Hydro

Consommation Hydro-électrique par rapport au total

  • % du Total

Energies produisant de l'électricité dans le monde

  • Type d'énergie
The most beautiful castles
→ Dams

Grande Dixence Dam

  • → Hérémence
  • Torpille
  • → Dams
Emosson Dam
→ Dams

Emosson Dam

  • → Finhaut
  • Torpille
  • → Dams
Moiry Dam
→ Dams