⚡ Hydroelectricity in Western Switzerland in 2020
⚡ Hydro-electricity in French-Speaking Switzerland in 2020
- 1 Foreword
- 2 Types of energy
- 3 Dams
- 4 Power plants
- 5 Types of turbines
- 6 Transport of electricity
- 7 Future of electricity in Western Switzerland
- 8 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 or Western 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 salmons 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.
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
Discover all the details about the dams in Western Switzerland in the very complete article of la Torpille.
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 was the least powerful of the five Swiss power stations. It is finally shut down on 20 December 2019. It will take more than 15 years to dismantle it.
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.
Dawn wheels at the Iron and Railway Museum in Vallorbe.
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.
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 aim is to bring the water against the turbine with the highest possible speed. 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.
YouTube videos on the Pelton turbine
Vidéo sur l’ensemble d’un système hydraulique utilisant une roue Pelton.
Reconstitution d’un petit modèle Pelton.
Fabrication par un robot à partir d’un seul pièce de métal d’une roue Pelton.
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||?|
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.
Future of electricity in Western Switzerland
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
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
Video on dams.
A video on the Itaipu dam.