⚡ Hydroelectricity in French-Speaking Switzerland
- 1 HYDROELECTRICITY IN FRENCH-SPEAKING SWITZERLAND
- 1.1 FOREWORD
- 1.2 THE TYPES OF ENERGY
- 1.3 DAMS
- 1.3.1 Switzerland, the queen of dams
- 1.3.2 The use of concrete
- 1.3.3 How to be sure of the solidity of a dam?
- 1.3.4 When should you visit a swiss dam?
- 1.3.5 Pressure applied by water
- 1.3.6 Is a concrete dam eternal?
- 1.3.7 Some particularities of other dams in Switzerland and around the world In Europe
- 1.3.8 The Atlantropa project
- 1.4 THE TYPES OF DAMS
- 1.5 COMPARATIVE TABLE OF DAMS
- 1.6 POWER PLANTS
- 1.7 TYPES OF TURBINES
- 1.8 THE TRANSPORT OF ELECTRICITY
- 1.9 THE FUTURE OF HYDROPOWER IN FRENCH-SPEAKING SWITZERLAND
- 1.10 HYDROPOWER IN THE WORLD
The purpose of this article is to present the different aspects of hydropower, i. e. electricity production with the power of water, within the regional framework of French-speaking Switzerland without forgetting international focuses.
Electricity, an energy carrier, has revolutionized the way machines operate since the early 1900s, it is now an integral part of our daily lives and it is no longer conceivable to do without it. Electricity can be produced by many energy sources such as solar, wind, water or nuclear. Currently, the vast majority of electricity in Switzerland is generated by nuclear (38%) and hydropower (57%), while worldwide, it is clearly fossil fuels (oil, gas, coal). Solar (1.2% in Switzerland) and wind (0.1% in Switzerland) are encouraging but remain far behind for the moment in terms of electricity production.
In the case of dams, we are of course dealing with hydropower where electricity is produced by the force of water that drives a turbine (see below for types of turbines). It is one of the oldest techniques for producing electricity on a large scale. The higher the flow rate and speed of the water, the greater the force or quantity of water on the turbine and therefore the better the electricity production. To increase the speed, the greatest difference in height between a reservoir and the turbine is needed, this is where the dam that retains the highest possible amount of water at altitude comes in. The maximum flow rate is obtained by turbining the water of a river, in this case the speed will be low but we will benefit from the high flow rate.
In Switzerland, hydroelectric power plants are either run-of-river, storage (dams) or pumped storage power plants. Run-of-river and storage power plants produce the same amount of electricity annually in Switzerland (each 17,000 GWh) but storage power plants have a much higher capacity than run-of-river plants, 8,000 MW compared to 3500 MW. Indeed, storage power plants operate less constantly and more at the time of peak consumption. Pumped storage power plants (see below) produce 1300 GWh/year for a capacity of 1500 MW are expected to expand. The above figures are provided by the Swiss Federal Office of Energy (SFOE), which is in charge of monitoring dams in Switzerland and concerns power plants of more than 0.3 MW. It should be noted that smaller installations can be useful as if they turbined “free of charge” the excess pressure of a drinking water supply installation.
Les sites suivants sont intéressants pour obtenir plus d’informations:
- News on dams in Switzerland on the aqueduc.info website.
- A civil engineering treaty on dams by EPFL in the form of an ebook.
What are the benefits of hydropower?
Hydroelectricity is often considered as “green” energy, i.e. its energy source, water, is recyclable and does not emit harmful emissions such as CO2 (coal) or radioactive waste (nuclear). Solar and wind energy are also considered “green” but have the disadvantage of being linked to weather conditions. However, it would be wrong to say that hydropower does not emit greenhouse gases because dam reservoirs contain microorganisms that break down organic substances and produce CO2 and methane. A paragraph discusses this aspect below.
Another little-known advantage of electricity produced with the water from a dam is the possibility of strongly modulating its injection into the grid according to needs and in particular at times of peak consumption, which is particularly useful because electricity is still not storable in large quantities nowadays. The famous Bieudron power station near Sion in Valais allows to mobilize its 1200 MW power from stop to full power in less than 3 minutes to produce peak energy. A nuclear or run-of-river power plant will be designed to produce electricity in a constant way, ensuring the “background noise” of the consumption or ribbon energy.
What are the disadvantages of hydropower?
The main disadvantages of hydropower are its impact on the environment. A dam, particularly at the level of a river, will impoverish biodiversity by, for example, cutting off water circulation for fish. High mountain dams dry up streams that disturb the ecosystem. The construction of a dam can affect the population by forcing them to move and cause landslides in newly flooded areas.
Fortunately, in Switzerland, dams are mainly built outside residential areas and reasonably affect the environment, although dams on the Saane River in Schieffenen and Rossens significantly disturb the ecosystem. Indeed, Schieffenen and Rossens, in addition to having swallowed up agricultural land and forced people to leave their village, cut off the circulation of fish, which is not the case in Mauvoisin and Grande Dixence.
For the anecdote, Atlantic salmon went up the Rhine, the Aare and then the Saane to breed in Gruyère until the end of the 19th century. This is no longer the case for several reasons:
- The dams and obstacles along the river block traffic.
- The artificial lakes preventing fish orientation because there is no longer a current of water.
- The housing destruction and the degradation of water quality.
However, in 2013, thanks to efforts in Germany, salmon were spotted in Rheinfelden on the Rhine near Basel showing their reappearance in Switzerland since 1950 as an indicator of the good health of a river. Nevertheless, the return of salmon to Gruyère is problematic and because it involves crossing two dams (Schieffenen and Rossens) nearly 80 metres high.
In other countries, ecological considerations are still not taken into account as little as for the dam of all the superlatives, the Three Gorges Dam in China, which has forced one and a half million people to move and swallowed up a considerable amount of arable land. Some species have even disappeared like a river dolphin specimen. A significant increase in the number of small earthquakes has been observed since the dam was impounded and even worse, some believe that the earthquake of 12 May 2008, causing 87,000 victims, was caused by the mass of the dam supporting a seismic fault. Moreover, this mass is such, about 50 billion tons, that it has modified the distribution of the Earth’s mass in relation to its axis of rotation and has lengthened the rotation time by 0.06 microseconds.
Dams on rivers also have the disadvantage of hindering boat traffic. To overcome the problem, locks are being installed to overcome the obstacle. At the Trois-Gorges dam (again him!), the difference in height is so great (more than 100 m) that “monstrous” boat lifts are in service rather than locks. They lift the boats and the water that allow them to float.
The Itaipu Dam
Concerning the Itaipu dam on the border between Brazil and Paraguay, its impoundment has caused the disappearance of a natural wonder, the Seven Falls Waterfall. Until 1982, when it disappeared, it was the largest waterfall in the world in terms of water flow at more than 10,000 m³/s. By way of comparison, the Rhine Falls in Switzerland have an average start of about 350 m³/s. The Seven Falls Waterfall is even irremediably destroyed by the former Brazilian military regime in power by blasting its parts that remained above the water to facilitate navigation on the reservoir created by the dam. The electrical infrastructure linked to this dam is the second most powerful in the world clearly behind that of the Trois-Gorges, but the annual electricity produced is equivalent between the two infrastructures to around 100 TWh.
The Aswan Dam
The case of the monstrous Aswan dam on the Nile is interesting. This huge weight dam is built to produce energy but also to prevent floods and mitigate droughts. Its dimensions are impressive with a volume of 42 million m³ of soil and rockfill, a crown length of 3800 m, a width at the base of the dam of nearly one kilometre and a water retention of 169 billion m³. All these figures are much 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 lower than those of the Three Gorges.
Unfortunately, the negative consequences on the environment of this dam built in the middle of the Cold War with the help of the Soviet Union are many. In addition to the engulfment of historic monuments or the greater reflux of salt water onto the Nile, the most interesting case is the retention by the dam of the fertilizing silt that has allowed the growth of crops on the Nile plain for millennia. This results in the use of fertilizers by farmers. Another phenomenon caused by the dam is the modification of streams at the Suez Canal, which increases the intrusion of the Red Sea fauna, often intrusive, into the Mediterranean fauna. Some experts question the usefulness of this dam (and even large dams in general), considering that the disadvantages outweigh the advantages it brings.
Le dégagement de méthane
Finally, a last and little-known disadvantage is the release of methane gas, a greenhouse gas much more powerful than CO2, through the reservoirs. The organic material in the water is broken down in the oxygen-poor layers by bacteria that convert it into methane and CO2. The release of methane depends on several factors such as the amount of organic matter, the water temperature or the depth of the reservoir. The actual methane emissions figures from dams are still unclear and subject to discussion, but it would appear that Alpine dams are not very affected by these emissions, unlike those located in the tropics or on the equator at low altitude. Some figures indicate that dams in these latter regions would emit up to nearly 20% of the methane associated with human activities, which would mean that dams are not as “clean” as often described while other studies tend towards opposite values with more symbolic figures in relation to methane release.
THE TYPES OF ENERGY
The energy in the dam is stored as potential energy. When it flows from the dam as water in the penstock, it gains speed and is transformed into kinetic energy. A turbine converts kinetic energy into mechanical energy and then the latter is in turn converted into electrical energy by an alternator that operates in the opposite direction to the turbine. Electricity flows into high-voltage lines using a transformer.
The problem with electricity is that it cannot be directly stored in large quantities despite decades of research. This is where the advantage of the dam that stores this electricity indirectly comes in with the accumulation of water as potential energy. A pumped storage station, such as the one at the Emosson dam in Nant de Drance, allows water to be turbined during periods of high consumption and therefore produce electricity and, on the contrary, during periods of low consumption, to be stored by pumping it between two water reservoirs at different altitudes. In the case of the Nant de Drance, the water is pumped up from the Emosson dam to the Vieux-Emosson dam 300 metres higher. Pumped storage makes it possible to “transform” electricity into potential energy, the efficiency is around 80%, which means that for every 100 units of energy used to pump up water, 80 will be produced. It should be noted that the price of the energy used to raise water is often much lower than the price that can be sold with the turbine because we will ensure that electricity is produced when demand is high.
Nikola Tesla (1856-1943). Born in Croatia during the time of the Austrian Empire, he emigrated to the United States and developed the first alternators for alternating current electricity production. Today, Tesla’s name is known as an electric car manufacturer.
Dam = Potential Energy → Penstock = Kinetic Energy → Turbine = Mechanical Energy → Alternator = Electricity
Switzerland, the queen of dams
Switzerland has a large number of dams mainly located in the Alps and especially in the canton of Valais. The king of dams is the one of Grande-Dixence because of its height (285 m) and the phenomenal quantity of concrete it contains. It remained for a long time the highest in the world before being surpassed by 3 other dams. In 2018, a Chinese dam, the Jinping I dam with its 305 m is the highest in the world. The dam producing the most electricity is the Trois-Gorges dam, as indicated above.
The use of concrete
The use of concrete allowed dams to rise at the end of the 19th century with, in 1872, the first concrete dam in Europe at Pérolles in the canton of Fribourg. The Hover Dam, along the Colorado River in the United States, was built in the 1930s during the Great Depression and is the first major dam ever built with a height of 220 m. It is remarkably built in only 4 years under much more difficult technological and human conditions than those we could have today. It is currently still in operation and at the same time a tourist attraction with 1 million visitors per year.
How to be sure of the solidity of a dam?
Nowadays, the failure of a dam in Switzerland is a near-zero possibility due to the monitoring and verification technologies in place, and the dam could even be emptied as soon as worrying signals appear, as was the case for the Tseuzier dam in 1978, which was damaged by underground drilling.
In the past, a few disasters have left their mark on people’s minds. A disaster in the United States at the end of the 19th century. Two in Western Europe in the early 1960s and one in China in 1975.
- Johnston USA 1889
- Malpasset France 1959
- Vajont Italy 1963
- Banqiao China 1975
In the United States in 1889, very heavy rains caused the South Fork Dam in Transylvanie on the east coast to overflow and then completely destroy it. This earth and rockfill dam was 22 metres high and had a volume of 18 millions m³. This disaster, known as the “Johnstown Flood”, took the lives of 2200 people.
In Europe, the first disaster (1959 – 423 deaths) was the rupture of the Malpasset dam in France, releasing 50 million m³ of water due to high floods and multiple design failures such as a lack of anchoring in the rock. The second (1963 – 1900 deaths), at the Vajont dam in Italy near Venice, is not due to the failure of the dam but to a huge landslide in the dam’s reservoir that caused 25 million m³ of water to overflow. Fortunately, the dam remains intact after the disaster but is later disused. The danger in the event of an overflow of a reservoir is the erosion of the dam’s foundations by the force of the water, which can quickly cause the dam to rupture.
The rupture of a dam that cost the most lives occurred in 1975 in China with the bursting of the Banqiao dam causing the death of about 25’000 people directly and certainly more than 100’000 as a result of the epidemics and famines that followed and affected more than 10 million people. This disaster was long hidden by the Chinese government.
In the Valais, the threat could come from an earthquake that would cause a dam to break. Estimates have shown that the total rupture of the Grande Dixence would cause a wave 37 metres high in Sion, 2.5 metres in Martigny and another 2 metres in Villeneuve 6 hours later.
When should you visit a swiss dam?
Valais dams should be visited in summer or early autumn as most of them are inaccessible in winter due to the absence of snow removal from the access road or the risk of avalanches. This is particularly the case for the three highest dams in the Valais, the Grande-Dixence, Mauvoisin and Tseuzier dams. The month of September is on average the month in which the reservoirs are filled to the maximum while the opposite is the month of April in which the reservoir can be filled to only 10% of its capacity. Still in spring, access is not necessarily ideal because of the ever-present snow and the almost empty water reservoir. Plains dams such as Rossens or Schieffenen have a much less variable filling volume and are of course accessible all year round. Dams mainly produce electricity in winter and early spring while they fill up with water the rest of the year.
Pressure applied by water
In a hydroelectric complex, the pressure generated by the water must be accurately assessed. Here we will calculate the pressure at the bottom of a dam and explain how operates the water hammer.
What is the pressure at the bottom of Lac des Dix, the Grande-Dixence dam?
The simplified formula is as follows: which is the pressure applied to a point on the dam. (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 selected pressure point. Let us take a water height of 227 m 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 the Pascal or N/m². In summary, the force acting on the dam increases with the water level, which explains why the thickness of a dam is greater at its base than at its top. This is particularly striking on a gravity dam such as the Grande Dixence dam, where the thickness varies from 200 m (!) at the base to about 15 metres at the top. It should be noted that the force applied to the dam does not depend on the quantity of water in the reservoir.
The water hammer
Water hammer is a phenomenon of pressure build-up that occurs as a result of a sudden stop in the speed of a liquid when a valve is suddenly closed. In the case of a dam, this phenomenon can cause the failure of the penstock or infrastructure of the downstream power plant. To overcome this problem, an surge chamber is created, which is a vertical well connected to the pipe and which aims to absorb the excess pressure generated by the water hammer. The surge chamber is generally positioned between the inlet gallery that starts from the dam on a gentle slope and the penstock that goes to the power plant on a steep slope.
Is a concrete dam eternal?
No structure is eternal. In this case, there is not enough distance to give a life time since the first major concrete dams were built in the late 1950s. Although they are remarkably resistant, a concrete swelling problem called the “alkali-aggregate reaction” unknown at the construction time affects dams to varying degrees. To simply explain this reaction, we can say that concrete is a mixture of sand, small stones, cement and water in very precise proportions that hardens some time after this mixture. In the agglomerate thus formed, small spaces are made up of water and air with a high pH which will interact with the silica constituting the sand and the small stones of the concrete by increasing the pressure causing a swelling and then a crack in the structure. This causes an alteration of the mechanical properties of the concrete.
The Salanfe dam in the Valais was particularly affected by this problem, so that work had to be carried out in 2013. These are only used to delay the spread of irreversible swelling in concrete that has been cut vertically over 1 cm wide with a saw. The incisions are gradually closing.
The Sixth Street Viaduct in Los Angeles, built in 1932, was demolished in 2016 due to particularly severe alkali-aggregate reactions that weakened its structure in a sensitive seismic region.
Some particularities of other dams in Switzerland and around the world
In Europe and the US
The Vajont dam (261 m) is the highest in Italy, the Tigne dam (160 m), the highest in France and the Lac Oroville dam (231 m) is the highest in the United States. The latter is facing a serious problem in February 2017. Following heavy rains, weirs are used to avoid overflowing, causing erosion damage. The dam is not threatened, but the water may cause one of the damaged weirs to rupture, causing a wave of nearly 10 m. The situation returned to normal a few days later.
The last dam built in Switzerland is the Linthal dam. It was built in 2014 in the canton of Glarus and is the longest in Switzerland with a crown of one kilometre long and the highest in altitude in Switzerland but also in Europe at 2500 m. It is part of the Linthal pumped storage power station, which raises the water from Lake Limmern 630 m below.
In the world
The Three Gorges Dam has the most powerful hydroelectric infrastructure in the world but is not the largest dam in the world, in this case the Tarbella Dam in Pakistan. The latter is mainly composed of earth and rockfill, unlike Trois-Gorges concrete. The Kariba dam on the Zambezi River in Africa has the largest volume of water with 180 billion m³, 4x more than the Three Gorges.
The Atlantropa project
The Atlantropa project is one of the most colossal construction projects ever imagined. It is a gigantic dam 35 kilometres long designed by the German engineer Herman Sörgel in 1928 at the level of the Strait of Gibraltar separating the Atlantic Ocean and the Mediterranean Sea. The dam would have reduced water supply in the Mediterranean and thus created a difference in level allowing underground plants to produce huge amounts of electricity. The water level was expected to decrease by almost one metre per year to 100 metres for the sea part between Sicily and Gibraltar and 200 metres between Sicily and the eastern part. The 2 parts of the sea being separated by a dam between Sicily and Africa. Another dam was to be built at the Dardanelles to separate the Black Sea from the Mediterranean Sea. According to Sörgel, new land has emerged from the water, making it possible to have additional cultivable and habitable areas. For example, the Adriatic Sea would have almost disappeared.
Unfortunately, the project is not ecologically acceptable, which was not part of the considerations at the beginning of the 20th century. For example, the drop in the level of the Mediterranean Sea would have discovered new lands but they would have been difficult to cultivate because of the salinity of the soil. The salt concentration of the water is reported to have increased, causing disturbances to aquatic fauna and flora. Other problems would have arisen, such as access to coastal cities that would no longer have a port. More generally, the drop in water level would have had repercussions on the climate around the Mediterranean.
A travelling exhibition presented the Atlantropa project to the population in the 1930s, mainly in Germany. Sörgel was invited to the universal exhibitions in Barcelona in 1929 and New York in 1939. He even continued to promote it after the Second World War and died hit by a car on his way to one of his own meetings.
THE TYPES OF DAMS
The types of dams in Switzerland are as follows:
- Arch Dams
- Gravity Dams
- Buttress Dams
- Embankment Dams
Examples: Mauvoisin, Emosson, Tseuzier, Hongrin, Moiry, Toules, Rossens, Schiffenen and Montsalvens dams. Highest in Switzerland: Mauvoisin, 250 m.
This type of elegant dam allows part of the water pressure to rest on the rock faces. It is less concrete consuming and requires a relatively small distance between the walls.
Some dams such as the Hongrin dam have a double vault, the 2 vaults are separated by a rocky anchor. This dam is visible from the Rochers de Naye at the level of the Jardin Alpin La Rambertia.
Example: Grande-Dixence and Salanfe dams. Highest in Switzerland, Grande-Dixence, 285 m.
The dam alone supports the weight of the dam, which is triangular in shape in cross-section perpendicular to the crown of the dam. It requires a large quantity of concrete.
Little used in Switzerland, dam allowing large widths while saving concrete because the buttresses of the dam are arch-shaped. The only buttress dam in Switzerland is the Lucendro dam in the Canton of Ticino, 73 m high. The Cleuson dam has the particularity of being of the buttress type despite its appearance which reminds us of the gravity type. This is because the spaces between the buttresses are filled with concrete to increase its strength in 1950, not to fight against water pressure, but to improve its resistance in the event of bombardment. The end of construction took place a few years after the end of the Second World War and images of the destruction of some dams during the war, particularly in Germany, are still very much in evidence at that time.
The Cruachan dam in Scotland with the arches on the downstream side. Photo Flickr “Tom Parnell”. The Lucendro dam with the arches on the upstream side. Photo Wikimedia.org.
The Möhne dam near Dortmund was bombed by the Royal Air Force in 1943 during Operation Chastise. The picture was taken from an English plane. New bombs called “bouncing bombs” must be invented to destroy the dams and pass over the anti-torpedo protection nets. Source Wikimedia Commons.
Example: Mattmark. Highest in Switzerland, Göscheneralp, 155 m.
Barrage constitué d’enrochement ou de terre avec un noyau étanche en béton ou argile. Beaucoup plus large et limité en hauteur que les barrages en béton.
COMPARATIVE TABLE OF DAMS
COMPARATIVE TABLE OF DAMS
Among all the dams in French-speaking Switzerland, the 12 highest were visited by La Torpille. In the table, the Three Gorges Dam in China is added for comparison purposes, it is the facility that produces the most energy in the world, all energies combined.
|Barrages||Grande-Dixence||Mauvoisin||Emosson||Tseuzier||Moiry||Hongrin||Cleuson ||Toules||Rossens||Montsalvens||Salanfe||Schiffenen||Aubonne||Trois-Gorges (Chine)|
|Link to activity||Link||Link||Link||Link||Link||Link||Link||Link||Link||Link||Link||Link||Link|
|Commissioning date [year]||1961||1958||1975||1957||1958||1971||1951||1964||1948||1920||1950||1964||1956||2006-2009|
|123 (Nord) 95 (Sud)|
|Length [m]||748||520||555||256||610||325 (Nord)|
|Base thickness [m]||195||53.2||45||26||34||22?||80||20.5||28||22||40||14||?||115|
|Crown thickness [m]||15||12||8||7||7||3?||3.5 à 5||4.5||5||3?||5||7||?||40|
|Crown altitude [m]||2364||1971||1931||1777||2250||1255||2187||1811||670||802||1925||534||561||229|
|Crowning open to cars||No||No||No||No||No||No||No||No||Yes||Yes||No||Yes||No||No|
|Flood evacuator [m3/s]||?||107||60||36||62||100||145||355||430||12.2||1000||180|
|Reservoir volume [Mm3]||400||211||227||50||77||52||20||20||220||12.6||40||58.6||0.0635||45'300|
|Reservoir area [km2]||4.04||2.08||3.27||0.85||1.3||1.6||0.5||0.60||9.6||0.74||1.85||4.25||?||1544|
|Reservoir length [km]||5||5||5||1.3||2.4||2.7||1.4||1.5||13.5||1.7||1.8||12.5||?||600|
|Concrete volume [1000*m3]||6'000||2'000||1'100||300||814||228 (North)|
|Max distortion [cm]||11||7||9||7||6||2.4||7.5||3.2||?|
|Galleries in dam [km]||32|
|Total water catchment area [km2]||420 (46 direct whatershed)||167 (198 with watershed after dam)||175 (34 direct whatershed)||18.7||MOTTEC|
29 Moiry dam
36 Tourtemagne dam
87: Navisence in Mottec
19: Torrent du Moulin
66: Navisence à Vissoie
45 East and West adductions
45 Hongrin et Petit-Hongrin
|23 (16 direct whatershed and 7 Tortin water collector)||78 (110 Orsière central)||954||173||31|
(Salanfe 18, Saufla: 13)
|Collectors [km]||100||About 13 (7.5 + 5.5)||47||20.8||2||5?||0||0||4||0||0|
|Lake name||Lac des Dix||Mauvoisin lake||Emosson lake||Tseuzier lake||Moiry lake||Hongrin lake||Cleuson lake||Toules lake||Gruyère lake||Montsalvens lake||Salanfe lake||Schiffenen lake||?||Trois-Gorges lake|
|Distance/Time around the Lake||Not possible because of east side||12km / 7h||?||4.7km / 1h10m||7.5km / 2h20||22.5km / 5h30||4km / 1h15||12.5km / 4h30||50km/14h35||10km / 2h45m||7km / 1h45m||?|
|River||Dixence||Dranse de Bagnes||Barberine||Lienne||Gougra||Hongrin||Printse||Dranse d'Entremont||Sarine||Jogne||Salanfe||Sarine||Aubonne||Yangtze|
|Remaining river downstream||No||No||No||No||No||Yes||No||No||Yes||Yes||No||Yes||Yes||Yes|
|Company name||Grande Dixence SA ou|
de Mauvoisin SA
|Electricité Emosson SA / CFF||Electricité de la Lienne SA||Forces Motrices de la Gougra SA||Forces Motrices Hongrin-Léman SA||Energie de l'Ouest Suisse (EOS)||Forces Motrices du Grand-St-Bernard||Groupe E||Groupe E||Salanfe SA||Groupe E||SEFA||China Yangtze Power|
|Can be visited||Yes 15 francs||On reservation|
Free of charge
|No||On reservation||On reservation|
Free of charge?
Free of charge
Free of charge
Free of charge
|Central 1 [MW]||CHANDOLINE - 150|
|FIONNAY - 138|
Outdoor - 160
|CHAMARIN - 0.9|
|MOTTEC - 69|
|VEYTAUX I - 240|
|PALLAZUIT - 36|
|PIED DE BARRAGE 2 - 1.7|
|ELECTROBROC - 25|
|MIEVILLE - 70 Outdoor||PIED DE BARRAGE 1 - 70|
|PIED DE BARRAGE - Outdoor||RIVE GAUCHE - 9800|
|Turbine||x? Pelton||3 Francis||2 vertical Pelton with 5 injectors of 80MW||1 Pelton||6 Pelton ( 3 alternators)||4 Pelton (2 alternators)||1 Pelton ?||1 Francis 1.7 MW||5x Francis||2 vertical Pelton 35MW||2x Kaplan||14x Francis 700MW|
|Flow rate [m3/s]||Stopped in 2013||3x 11.5||29m3/s||0.45||3x 4||4x 8||10||2||26||7.2||135||0.3|
|Pipe length [km]||Supply tunnel: 4.7|
Shielded penstock: 0.6 ?
|Supply tunnel: 9.8 + 0.27|
Shielded penstock: 0.92
|environ 3.5||Supply tunnel: 3.4|
Shielded penstock: 1
|Supply tunnel: 7.98|
Shielded penstock: 1.22
|Supply tunnel: 5.5|
Shielded penstock: 0.6
|Drop height [m]||1800||400||626||388||685||883||480||67||100 variable||1472 variable||45||90|
|Water intake||Dam||Dam||Bassin de compensation de Châtelard||Dam||Moiry and Tourtemagne dams||Dam||Dam||Dam||Dam||Dam||Dam||Dam||Dam|
|Flow||Rhône||Fionnay I tailpond||Rhône||Bisse d'Ayent||Mottec tailpond||Lake of Geneva||Tailpond||Sarine||Sarine||Rhône||Sarine||Aubonne||Yangtze|
|Year of commissioning||1934 (Dixence)|
1958 (Grande Dixence)
|Central 2 [MW]||FIONNAY - 290|
|RIDDES/ECONE - 225|
|VALLORCINE - 242|
|CROIX - 66|
|VISSOIE - 45|
|VEYTAUX II - 240|
|ORSIERE- 24||HAUTERIVE - 70|
|PIED DE BARRAGE - 0.18|
|PIED DE BARRAGE 2 - 2.5 Outdoor||PLAN-DESSOUS - 12 Outdoor||RIVE DROITE - 8400|
|Pipe length [km]||9||Supply tunnel: 15|
Shielded penstock: 2.45
|Supply tunnel: 1 + 0.5|
Shielded penstock: 1.1
[Shielded penstock: 0.5/1.89]
|Supply tunnel: 3.2|
Shielded penstock: 1.4
|Supply tunnel: 6.9|
Shielded penstock: 0.9
|Supply tunnel: 7.98|
Shielded penstock: 1.22
|Supply tunnel: 5.6|
Shielded penstock: 0.7
|Turbine||12 horizontal Pelton (6 alternators)||10 Pelton (5 alternators) ?||3 vertical Pelton with 5 injectors de 64MW|
[1 Francis 50MW]
|2 horizontal Pelton of 33MW||6 Pelton (3 alternators)||2 Pelton||4 vertical Pelton with 2 injectors ?||4x Francis||1x Diagonal||1x Francis||3x Francis||12x Francis 700MW|
|Flow rate [m3/s]||45||10x 2.8||29|
|9||3x 4||2x 16||8||75||0.5||5||10|
|Drop height [m]||800||1000||750|
|855||342||883||387||75 à 110||45||48||97||90|
|Dam||Mottec tailpond and Navisence river||Barrage||Palazuit tailpond||Dam||Dam||Dam||Dam||Dam|
|Flow||Fionnay II (166'000 m3) tailpond||Rhône||Châtelard-Frontière|
|Croix tailpond||Vissoie tailpond||Lac Léman||Dranse d'Entremont||Sarine||Jogne||Sarine||Plan-Dessous cenatral tailpond||Yangtze|
|Year of commissioning||1958||1973||1958||2017||?||1948 (1902)||2013||1964||2000 (1895)|
|Central 3 [MW]||NENDAZ - 430|
|CHANRION - 28|
|CFF CHATELARD I et II - 110MW - Underground||SAINT-LEONARD - 34|
|NAVIZENCE - 70|
|SEMBRANCHER||PIED DE BARRAGE 1 - 0.6 Outdoor||LA VAUX - 3.5 Outdoor||CENTRALE 3 - 4300|
|Prise d'eau||Fionnay II tailpond||Breney (before dam) tailpond||Dam||Croix tailpond||Vissoie tailpond and Navisence river||Dam||Plan-Dessous tailpond||Dam|
|Turbine||12 horizontal Pelton (6 alternators)||1 pelton with 2 injectors?||3 horizontal Pelton with 1 injector 11MW (I)|
2 horizontal Pelton with 2 injecteurs 40MW (II)
|2 Francis 17 MW||6 Pelton (3 alternators)||1 Francis||1 Kaplan||6x Francis 700W|
2x Francis 50W
|Flow rate [m3/s]||45||2x 5||16||10.5||3x 4||1||10|
|Pipe length [km]||16||Supply tunnel: 4.1|
Shielded penstock: 0.9
|Supply tunnel: 8.5|
Shielded penstock: 1.1
|Drop height [m]||1000||350||804||420||695||67||43||90|
|Flow||Rhône||Mauvoisin dam||Châtelard tailpond||Rhône||Rhône||Sarine||Aubonne||Yangtze|
|Year of commissioning||1958||1925 (I) /1972 (II)||1908 (2014)||1976||2008|
|Central 4 [MW]||BIEUDRON/RIDDES - 1200|
|CHAMPSEC - 5|
|CFF VERNAYAZ - 107 Outdoor||MARTIGNY-BOURG|
|Turbine||3x vertical Pelton turbine with 5 injecteurs||2 Pelton turbines||3 Pelton with 2 injectors |
|Flow rate [m3/s]||75||1.2||17|
|Pipe length [m]||Supply tunnel: 15.8|
Shielded penstock: 4.3
|Drop height [m]||1900||550||645|
|Water intake||Dam||Les Creux tailpond||Châtelard tailpond|
|Flow||Rhône||Dranse de Bagnes||Rhône|
|Year of commissioning||1998||1928|
|Pumping station||Zmutt - 470m-86MW-17m3/s||Vallorcine power plant|
2x 9m3/s, 800m, 120 GWh/an
vers barrage Emosson
|Mottec: pump: 23MW||Veytaux I|
4 pumps, 32 m3/s
|4 pumps of 1MW and 0.5 m3/s||Clusanfe|
|Stafel - 212m-26MW-9m3/s||Châtelard II power plant|
31 MW, 4 m3/s, 800m
to Emosson dam
|Gietroz du Fond|
|Ferpecle - 212m (via Arolla) -21MW-8m3/s|
|Arolla - 312m-48MW-12m3/s|
|Cleuson dam - 165m|
|Pumped storage [MW]||In construction 2018|
Nant de Drance 900
6 Francis 150 MW
|Total Production [GWh/year]||2800 (2015)||700||1100|
(800 ESA + 300 CFF)
(Palazuit 100 + 130 Orsière)
|Total power [MW]||2700 (2015)||400||637|
(410 ESA + 217 CFF)
(36 + 24)
|Accumulated energy [GWh]||660||100|
|Drama/problem [year]||1999||1818 (before dam construction)||1978|
|Details||Pipe Break||Gietroz galcier||Major cracks in the dam||"Cancer" du béton|
|Records||Highest weight dam in the world|
World's most powerful pelton turbine
|Highest arch dam in Europe||Oldest horizontal and vertical arch dam in Europe||Most powerful dam in the world|
The power of hydroelectricity
Surprisingly, by far the most electricity-producing installations in the world are hydroelectric complexes. The installation of the Trois-Gorges dam with a capacity of 22,500 MW and an annual production of 100,000 GWh is by far the most important. The most powerful nuclear power plant is located in Canada with a capacity of 6300 MW and 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 shut down since the 2011 earthquake as a precautionary measure and has still not restarted. Many power plants produce electricity with other means but are less powerful than hydropower or nuclear power.
Nuclear power plants in Switzerland
Concerning Switzerland, the Leibstadt power plant built in 1984 is the most powerful of the 5 nuclear power plants built in Switzerland. Its capacity is 1200 MW for a production of 10,000 GWh per year. The Beznau I nuclear power plant is the oldest operating power plant in the world. On 21 May 2017, the Swiss people decided to ban the construction of new nuclear power plants on a vote on energy developments.
The Mühleberg nuclear power plant in the canton of Berne built in 1972. It is the least powerful of the 5 Swiss power plants and one of the oldest in the world in operation.
The distribution of electricity production
The Grande-Dixence hydraulic installation, the most powerful in its sector and composed of 3 power plants, is much more powerful than Leibstadt with its 2000 MW (1200 MW for the Bieudron) but produces much less electricity with 2,000 GWh (Bieudron 1700 GWh) annually than the Leibstadt plant. Indeed, the nuclear power plant operates continuously and almost at full capacity, which is not the case for Grande-Dixence. In Switzerland, the huge majority of electricity is generated by hydropower (58%) and nuclear power (38%). It should be noted that just before the construction of the first Swiss nuclear power plant in 1969, hydropower accounted for 90% of Switzerland’s electricity production. The most powerful run-of-river power plant turbining water, not by accumulation as in the Bieudron, is the Verbois power plant in the canton of Geneva along the Rhône with 98 MW and an annual production of 466 GWh. A superb map lists the hydropower plants in Switzerland on the website of the Swiss Federal Office of Energy (SFOE). Storage power plants (dams) and run-of-river power plants each account for 48% of Swiss hydroelectric production, the rest comes from pumped storage.
TYPES OF TURBINES
Three types of turbines are mainly used in hydroelectric production. The Kaplan, Francis and Pelton turbines named after their respective inventors at the end of the 19th century and the beginning of the 20th century. No other efficient water turbines have been produced since these dates. Each turbine is adapted to different environments mainly according to the height of the waterfall and the water flow. The Kaplan and Francis turbines are called “reaction” turbines, i.e. the inlet pressure in the wheel is higher than the outlet pressure, while the Pelton turbine is called “action” turbines, i.e. the inlet and outlet pressure in the wheel is the same. We add here the Deriaz turbine, a very small minority but observed during the visit of the Montsalvens dam.
Comparative video of the main turbines
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 and until the beginning of the 20th century. At that time, the water of a river was channeled and brought on a water-taking wheel 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 edge of buckets resembling two nut shells or buckets allowing water to escape from the sides. This principle was patented by Pelton in the 19th century. The injection is tangential to the turbine wheel and can 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 turbining and for maximum efficiency, the velocity of the water after injection must be as low as possible, ideally zero.
Allan Pelton in 1880 inventor of the turbine that bears his name.
Large Pelton turbines operate in the vast majority of cases in connection with a dam and a high waterfall to generate power during peak consumption periods. The Bramois power station at the bottom of the Borgne Gorge is an exception since its large Pelton turbines produce electricity “run-of-river” depending on the water flow available. There is no water accumulation before the power station.
It should be noted that Pelton turbines have a slightly lower efficiency than Kaplan and Francis turbines due to their small surface area in contact with water.
The most powerful Pelton turbine in the world is the Bieudron turbine, near Sion in Switzerland. With a diameter of about 5m, it has a capacity of 423 MW and a record waterfall of 1883 metres with the Grande-Dixence dam. The Valais in Switzerland is particularly suitable for the use of Pelton turbines, which are efficient at relatively low flows of less than 20 m3/s and waterfalls of more than 400 metres. Indeed, the bottom of the valleys lateral to the Rhone Valley is often steeped and at an altitude of more than 1500 metres, allowing the construction of dams. In addition, the lateral valleys are close and particularly high compared to the Rhone Valley itself, at an altitude of less than 500 metres. The power plants built in the Rhône Valley therefore benefit from a significant waterfall with relatively short penstocks.
The speed of the water depends only on the height of fall with the formula is the Earth’s gravity and varies slightly according to the places on earth and h the height difference. What is the speed of the water arriving from the Grande-Dixence dam on the Bieudron turbine? The height is 1883 m, g is equal to 9.81 m/s. So 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 that is why it is manufactured by a robot in a single piece of metal. The turbine speed is equal without loss to half the injection speed, i.e. 345 km/h for the Bieudron. For the brief history, gravity varies according to where you are on Earth and is lowest at the equator due to the opposite centrifugal force due to the rotation of the Earth.
What is the rotation frequency of the wheel in rpm at Bieudron? The formula is: 60 x speed (m/s) / wheel diameter (m) x Pi, so 60 x 96 m/s / 4.6m x 3.14 = 398 rpm.
A remarkable document with photos traces the history of the Pelton turbine and its operation, including a drawing of the penstock that brings water to the turbine with the injectors.
Old Pelton turbines are often used as decorative objects near power plants or elsewhere. Below is an overview of different turbines observed by La Torpille.
YouTube videos on the Pelton turbine
This is the most powerful turbine model. This turbine can produce 700 MW of power, as at the Itaipu dam in Brazil and the Trois-Gorges dam in China, which has a capacity of more than 10 to 50 million dollars each. It is perfectly suited for a large water flow and a waterfall of several hundred meters. For example, the water from the Mauvoisin dam is turbined by the Fionnay plant 400m lower using 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 Jean-Victor Poncelet’s invention at the beginning of the 19th century. The Francis turbine was first commissioned in 1848. It is a submerged “reaction” turbine because the pressure at the inlet is greater than that at the outlet and its diameter can reach 10 meters for the largest models.
The operating principle is as follows: the water enters all around the turbine thanks to a spiral pipe called a spiral tarpaulin then guided radially towards the wheel and its ten blades or vanes. The guide vanes modulate the power of the turbine by regulating the flow of water to the moving vanes of the wheel and thus making it rotate more or less quickly. The kinetic energy of the water and the energy from the pressure difference are transmitted to the alternator for electricity production. After passing through the turbine wheel, the water is then evacuated axially by the vacuum cleaner. Like Pelton turbines, Francis turbines can operate horizontally or vertically.
YouTube videos of a Francis turbine
Invented by Viktor Kaplan and first commissioned in 1912, the Kaplan turbine is particularly suitable for high water flow rates and very low waterfall. Like the Francis turbine, it is a submerged turbine called a “reaction” turbine where the pressure at the inlet of the wheel is higher than at its outlet. This turbine looks like a propeller whose blades can be rotated even when running according to the water flow, which makes it interesting for a river with a variable flow rate. The Kaplan turbine can have a diameter of 10 m and weigh several tens of tons, it is the fastest rotating turbine, up to 1000 rpm. The waters of Lake Schieffenen are the only major dams in French-speaking Switzerland to be turbined at the foot of the dam by two Kaplan turbines with a combined capacity of 70 MW.
Small Kaplan demonstration turbine exposed at Electrobroc.
Deriaz or Diagonal turbine
This turbine is suitable for small hydropower, its operating range includes flows from 0.1 to 10m3/s and a net drop of about 20 to 80 meters. It operates at the foot of the Montsalvens dam by turbining the waste water from the Jogne river. It is a turbine very similar to the Kaplan turbine in its design and operation is similar to the Francis turbine with diagonal injection of water against the turbine.
|Turbine||Pelton||Francis||Kaplan||Diagonale or Deriaz|
|Type||Action turbine||Reaction turbine||Reaction turbine||Reaction turbine|
|Inventor||Lester Allan Pelton (USA)||James Bicheno Francis (USA)||Viktor Kaplan (AUT)||Paul Deriaz (SUI)|
|Max. power in service [MW]||423 |
|Max. operating diameter [m]||5||10||15||5|
|Optimal water flow rate [m3/s]||less than 25||until 700||until 800||0.1 à 10 ?|
|Water height [m]||more than 400||30 to 300||until 30||20 to 65|
|Turbine speed [tour/min]||until 36||until 400||until 1000|
|Positioning||Vertical or horizontal||Vertical or horizontal||?|
THE TRANSPORT OF ELECTRICITY
In Switzerland, electricity is transmitted by SwissGrid, a 450-person company that manages the grid and its maintenance. Interesting statistics are available on the Swissgrid website. This company manages the electricity transmission network, which includes 380 kv very high voltage lines with a length of 1780 km and 220 kv lines with a length of 4920 km. The total number of very high voltage lines is 6700 km for more than 10’000 pylons.
The distribution network includes high (9000 km), medium (45000 km) and low (85000 km) voltage lines. Transformers ensure the conversion between the different intensities. High and very high voltage lines are overwhelmingly overhead, while the opposite is true for medium and low voltage lines, which are mostly underground. The cost of burying a very high voltage line is close to 10x more expensive than an overhead line but provides an improvement in landscape and wildlife as well as a lower vulnerability to bad weather.
It is interesting to note that the loss of electricity during its transport is about 6%. It is reported that Switzerland with SwissGrid imports electricity mainly from France but also from Germany and Austria and exports electricity to Italy.
THE FUTURE OF HYDROPOWER IN FRENCH-SPEAKING SWITZERLAND
The cost of electricity
Energy costs have fallen particularly in recent years, leading to hydroelectricity in French-speaking Switzerland but also in Switzerland and even in Western Europe in an unprecedented crisis. The reasons are as follows:
- Liberalisation of the energy market in Europe.
- Arrival on the market of electricity produced by coal-fired power plants that benefit from the low cost of coal and that of CO2 emissions.
- Solar and wind power generation in neighbouring countries, particularly Germany.
The price per KWh on the European market is around 3-4 cents at the time of purchase, while that produced by hydraulics doubles it, i.e. 6-8 cents per KWh, while it is sold between 10 cents and 40 cents per KWh to the final customer. It is therefore cheaper to import electricity abroad than to produce it in Switzerland, which seriously threatens the profitability of Switzerland’s hydroelectric infrastructure, primarily dams. The closure of coal-fired power plants at European level and a strong economic recovery could change the situation and cause a price increase on the European market, but the price seems for the moment to remain very low for some time. A large number of new construction projects and especially hydraulic renovations have been cancelled in Switzerland, while recently completed pharaonic projects such as the Veytaux pumped storage plants in Montreux and especially the Nant de Dranse plant next to the Emosson dam risk becoming a financial abyss. At the time of the beginning of the development of these projects, electricity selling prices were much higher than at present and could be expected to generate a real profit.
Currently, global warming is causing an increase in the amount of water available in dams by accelerating the melting of glaciers. It is estimated that by 2050, the situation will be reversed with a significant decrease in the water supply of glaciers due to their gradual disappearance. Some studies claim that glaciers in Switzerland will have almost completely disappeared by 2100, so the water supply will not only be provided by snowfalls and rainfall, which will insufficiently fill the dams. One solution could come from pumped storage where water is pumped into the dam during periods of low consumption. For example, one could imagine pumping water from the Rhône to fill the Grande-Dixence dam.
HYDROPOWER IN THE WORLD
The largest hydroelectric producers
Not surprisingly, China is the world’s largest hydropower producer with more than a quarter of total production in 2015 1126 TeraWatt/h. Brazil and Canada each produce about 10% of the world total with about 350 to 400 TeraWatt/h in 2015. The total capacity of Chinese hydroelectric installations is more than 300 GW, including more than 22 GW for the Trois Gorges dam. By way of comparison, the Grande Dixence installations have a power of approximately 2.5 GW. In Switzerland, total hydroelectric production was 40 TeraWatt/h in 2015 for a capacity of 14 GW generated by more than 600 power plants.
Hydraulics compared to other energy sources
The share of hydropower in the world’s total electricity production is 16% in 2010. The total being 24,097 TW/year for 2,999 TW/year for hydroelectricity. The “large” countries that use hydropower most are Norway almost totally (96%) as well as Brazil, Venezuela and Canada in a percentage between 60% and 70%. Switzerland comes just after with 58%. 5 “small” countries produce 100% of their energy from dams. These are Albania, Bhutan, Lesotho, Nepal and Paraguay.
Statistics and videos on dams and hydropower
World electricity producing countries in 2015
Hydroelectric consumption in relation to total
- % of Total
Electricity generating energies in the world
- Energy Type
Report on the dams
The Itaipu Dam