Volume 6 hydro power 6 12 – hydropower in switzerland

Volume 6 hydro power 6 12 – hydropower in switzerland Volume 6 hydro power 6 12 – hydropower in switzerland Volume 6 hydro power 6 12 – hydropower in switzerland Volume 6 hydro power 6 12 – hydropower in switzerland Volume 6 hydro power 6 12 – hydropower in switzerland

B Hagin, Ingénieur-Conseil, Lutry, Switzerland

© 2012 Elsevier Ltd All rights reserved

6.12.6 Dixence, Grande-Dixence, and Cleuson-Dixence Schemes as an Example of Capacity Increase 350

6.12.1 Short Recall of Switzerland ’s Characteristics

Switzerland is a landlocked alpine country in Central Europe The country borders Germany to the north, France to the west, Italy to the south, and Austria and Liechtenstein to the east The area of Switzerland is 41 285 km2 with a population of 7 783 000 inhabitants in 2010 (Figure 1)

The Alps cover 65% of Switzerland’s surface area, making it one of the most alpine countries Among this, 9788 km2

or 24% of the territory is above 2000 m elevation and 936 km2 or 2.3% are above 3000 m elevation The highest summit is ‘La Pointe Dufour’, with an altitude reaching 4634 m

The glaciers of the Swiss Alps cover an area of 1230 km² (3% of the Swiss territory), representing 44% of the total glaciated area in the Alps (2800 km²)

The average annual rainfall is 1456 mm (European annual average is around 790 mm) The area around Sion in Valais, in the Rhône Valley in the south, being the driest zone with an average value of 600 mm yr−1 and the wettest part with 2900 mm yr−1, is around the Säntis mountain in Appenzell, north-east of the country (Figure 2)

6.12.2 The Drainage Basins of Switzerland

The south-west side of the Swiss Alps is drained by the Rhône River, flowing to France and then to the Mediterranean Sea The north

is drained by the Aar and the Rhine River, flowing to Germany and then to the North Sea The south-east is drained by the Ticino River, flowing to the Pô, through Italy, and then to the Adriatic Sea The extreme east is drained by the Inn River, flowing to the Danube River and then to the Black Sea (Figure 3)

Switzerland possesses 6% of Europe’s freshwater and is sometimes referred to as the ‘water tower of Europe’

6.12.3 Electricity Production in Switzerland

6.12.3.1 In General

Thanks to its topography and high levels of annual rainfall, Switzerland has ideal conditions for the utilization of hydropower Toward the end of the nineteenth century, hydropower underwent an initial period of expansion, and between 1945 and 1970, it experienced a genuine boom during which numerous new power plants were opened in the lowlands, together with large-scale storage plants in the Alps

Figure 1 Map of Switzerland with the main cities and the 26 cantons

Figure 2 Topographical map of Switzerland

Based on the estimated mean production level, hydropower still accounted for almost 90% of domestic electricity production at the beginning of the 1970s, but this figure fell to around 60% by 1985 following the commissioning of Switzerland’s nuclear power plants, and is now around 56% Hydropower, therefore, remains Switzerland’s most important domestic source of renewable energy

In a European comparison, Switzerland ranks fourth in terms of contribution of hydropower toward electricity production, behind Norway, Austria, and Iceland

The total number of power plants of a capacity higher than 300 kW is presently equal to 543, representing an installed capacity of

13 480 MW and an annual production of 35 601 GWh

The statistics of the hydropower plants are placing them in four categories:

The combined power turbine

The pure turbine

Conventional thermal power plants and

miscellaneous

plants 24.2 %

39.3 %

31.6 %

Storage power plants

Rhône basin Aar and Rhine basin Ticino and Pô basin Inn and Danube basin

Figure 3 The drainage basins of Switzerland

Figure 4 The electricity production in Switzerland

The big hydraulic plants with an installed capacity over 10 MW, produce about 90% of the hydroelectricity of Switzerland (Figure 4) Hydropower plays a major role in Switzerland’s energy production, with a share of around 56% In addition, storage plants are

an important factor for power production at short notice and for the changeover of production from summer to winter Thanks to its storage capabilities, Switzerland plays a central role as an electricity supplier in the European networks Hydropower is the most important, CO2-free energy source

6.12.3.2 Large-Scale Hydropower Plants

Today, there are 543 hydropower plants in Switzerland, each having a capacity of at least 300 kW, and these produce an average of around 35 600 GWh per annum, 47% of which is produced in run-of-river power plants, 49% in storage power plants, and approximately 4% in pumped-storage power plants The main water sources (feeding 476 power plants) are the Rhine (into which the Aar, Reuss, and Limmat flow) and the Rhône

Two-thirds of hydroelectricity are generated in the mountain cantons of Uri, Grisons, Ticino, and Valais, while Aargau and Bern also generate significant quantities Roughly 10% of Switzerland’s hydropower generation comes from facilities situated on bodies

of water along the country’s borders

In Switzerland’s hydropower plant statistics, a distinction is made between four types of plants: run-of-river plants (3707 MW,

16 611 GWh), storage plants (8073 MW, 17 397 GWh), pumped-storage plants (1383 MW, 1594 GWh), and basic water flow plants (316 MW)

Large-scale hydropower plants (capacity >10 MW) account for around 90% of Switzerland’s total hydropower production

Legende/Legende/Leggenda

10 - < 50 MW (103 Zentralen)

50 - < 200 MW (62 Zentralen)

≥ 200 MW (16 Zentralen)

Zentrale elner Internationalen Wasserkraftanlage

Centrale o”un Implanto Idroelettrico Internationale

6.12.3.3 Small-Scale Hydropower Plants

In Switzerland, the term small-scale hydropower plant refers to facilities that produce a mean mechanical gross capacity of up to

10 MW

Small-scale hydropower plants have been around for a long time in Switzerland At the beginning of the twentieth century, there were already around 7000 in operation But with the advent of low-cost electricity from large-scale power plants, many of these ceased production

Today, there are more than 1000 small-scale hydropower plants in operation, with an installed capacity of approximately

760 MW and an output of 3400 GWh per annum

Electricity production in small-scale hydropower plants is attractive from both an economical and an ecological point of view, and an expansion of output is perfectly feasible, as long as ecological aspects are duly taken into account The potential is estimated

at around 2200 GWh per annum Technological innovations and measures to lessen environmental impacts make small-scale hydropower plants inexpensive energy sources that provide renewable energy on an independent basis and help protect the environment

In addition to small-scale hydropower plants in rivers and streams, it is now possible to utilize other sources, for example, excess pressure in drinking water systems

6.12.3.4 Dams

The Swiss Federal Office of Energy (SFOE) is the highest supervisory authority for all dams in Switzerland In practice, however, the SFOE delegates responsibility for the supervision of several hundred small dams to the relevant cantonal authorities, so that it can focus on the country’s larger facilities (195 reservoirs with 217 dams) Eighty-four percent of these are for the production of hydropower One hundred and thirty-four dams take the form of concrete walls (78 gravity dams, 52 curved dams, 2 multiple-curve dams, and 2 pierhead dams), 78 are soil and stonefill constructions, and five are in the form of river weirs Twenty-five are higher than 100 m and four are over 200 m high, namely the Grande-Dixence gravity dam (285 m) and the Mauvoisin (250 m), Luzzone (225 m), and Contra (220 m) curved dams Most of the large-scale dams are located in the Alps

The oldest dams date from the nineteenth century, though most of the biggest dams in Switzerland were constructed in the period between 1950 and 1970 (Figure 5)

Figure 5 Location of the main dams and power plants in Switzerland

Reservoir volume

(Continued)

6.12.4 List of the Dams in Switzerland

The list of the main Swiss dams is given hereunder in alphabetic order

(Continued )

Reservoir volume

(Continued)

(Continued )

Reservoir volume

PG/TE, Concrete gravity and fill dam; PG, concrete gravity dam; TE, earth dam; ER, rockfill dam; VA, arch dam; CB, butress dam; MV, multiple arch dam

Source: For more details on each dam, see http://www.swissdams.ch/Dams/damList/

6.12.5 New Developments

The federal government wants to promote the use of hydropower to a greater extent through a variety of measures In order

to exploit the realizable potential, existing power plants are to be renovated and expanded while taking the related ecological requirements into account The instruments to be used here include cost-covering remuneration for feed-in to the electricity grid for hydropower plants with a capacity up to 10 MW and the measures aimed at promoting hydropower included in the ‘Renewable energy’ action plan In terms of quantity, the goal is to increase the mean estimated production level by at least 2000 GWh versus the level recorded in the year 2000 by renovating existing hydropower plants and constructing new ones

2496

Q max 80 m3/sec 2364

2240

2180

STAFEL

1883 m

2009 2186

FIONNAY

1486

AROLLA

1835

Galeries d’amenee a 2400 m

Galeries d’amenee a 2000 m

Galeries et conduites sous pression

Usines de pompage

Cleuson-Dixence

6.12.6 Dixence, Grande-Dixence, and Cleuson-Dixence Schemes as an Example of Capacity Increase

6.12.6.1 In General

Situated in the Canton of Valais in the Val des Dix, a contributory of the Rhône River, the Grande-Dixence scheme is well known for its concrete gravity dam, the highest concrete dam in the world, at 285 m high It is an example of several extensions to improve its capacity and especially the production of peak energy

This scheme was developed in three stages

6.12.6.2 First Stage: The Dixence Scheme

The first stage is the Dixence scheme with the Dixence dam, a 80 m high vault-gravity concrete dam with a storage capacity of

50 000 000 m3 built in the period from 1930 to 1935 It collects the water of the Val des Dix and later on receives the water pumped from the Cleuson buttress dam, which has a storage capacity of 20 000 000 m3 built in the period from 1948 to 1950 in a lateral valley The water head was 1747 m (a world record at that time) with a discharge of 10 m3 s−1 to the 120 MW Chandoline Power House located in Sion, in the Rhône Valley (Figure 6)

6.12.6.3 Second Stage: The Grande-Dixence Scheme

The second stage is the construction of the Grande-Dixence gravity concrete dam, 285 m high, downstream of the Dixence dam It has a storage capacity of 400 000 000 m3 and it is filled by collecting the water on a drainage basin of 350 km2, located above

2000 m in altitude and extending to the East, up to Zermatt and the Matterhorn

The drainage basin contains 35 glaciers, and the water is collected through 75 water intakes and 100 km of galleries, four pumping stations, with altogether 18 pumps There are four compensating reservoirs, made by the Z’Mutt arch dam, the Stafel Basin, both above Zermatt, and the reservoir of the Ferpècle arch dam and the underground storage basin of the Arolla pumping station in the Val d’Hérens (Figures 7–9)

Figure 6 The Dixence dam, now inside the Grande-Dixence lake

Figure 7 Schematic view of the Grande-Dixence scheme

Figure 8 Panoramic view of the Grand-Dixence scheme with the collecting galleries

Figure 9 The Dixence dam and the Grande-Dixence dam in April at low reservoir

The total water head of the Grande-Dixence scheme is 1886 m, with water discharge of 45 m3 s−1 The water is turbined in two steps: at first in the intermediate power house of Fionnay, with a water head of 878 m, and then in the lower step in the Nendaz power house, in the Rhône valley, with a water head of 1008 m The total capacity of the two power houses is 680 MW (Figure 10) The total installed capacity of the Grande-Dixence scheme together with Chandoline is therefore 800 MW, with a total water discharge of 55 m3 s−1

With a storage capacity of 400 000 000 m3 and an annual inflow of about 520 000 000 m3, the whole Grande-Dixence scheme produces energy for about 2000–2200 h a year, mainly in the winter time and during the strong demand periods

6.12.6.4 Third Stage: The Cleuson-Dixence Scheme

The Cleuson-Dixence scheme was built during the period from 1993 to 1998, with the view to increase the installed capacity from

800 to 2000 MW in order to produce super peak energy on the base of 1000 h a year, to be injected on demand on the Swiss and the European electrical network

Figure 10 The Grande-Dixence dam, 285 m high

It consists of a new water intake in the Grande-Dixence dam, a new pressure gallery, a new penstock, and a new power house in the Rhône Valley, the Bieudron power house

The water head is 1883 m (a world record) with 75 m3 s−1, and the Bieudron power house is equipped with three Pelton turbines

of 400 MW each (also a world record) (Figures 11 and 12)

6.12.7 New Hydroelectric Schemes Presently under Construction in Switzerland

Several projects to increase the installed capacity, and especially for producing peak energy, are presently under construction in Switzerland Among them, the three main ones are the following

6.12.7.1 The Nant de Dranse Scheme

The Nant de Dranse scheme is a development of the Emosson high head storage scheme

Figure 11 The general layout of the Dixence, the Grande-Dixence, and the Cleuson-Dixence schemes, high head galleries, and penstocks

Figure 12 Longitudinal section of the Cleuson-Dixence high head gallery and penstock

Emosson arch dam is located on the Swiss-French border in the Canton du Valais, between Martigny and Chamonix Its extension is called the ‘Nant de Dranse 600 MW Project’

It connects the reservoir of the ‘Vieil Emosson’, a concrete gravity dam which has a reservoir capacity of 11 400 000 m3

situated at elevation 2205 m, with the reservoir of the Emosson arch dam, having a reservoir capacity of 210 000 000 m3 at elevation 1930 and with adding an underground power house equipped with four Francis pump–turbine of 150 MW each, to produce peak energy by pumping during the low-demand energy and then to turbine during the peak hours (Figure 13)

6.12.7.2 The Linthal 2015 Project

The Linthal 2015 project is a development of the Linth-Limmern high head storage scheme by extending with a pump–turbine power house with a capacity of 1000 MW

The storage capacity of the natural lake of Mutt will be increased from 12 000 000 to 25 000 000 m3, from elevation 2446 to

2474 m, by building a gravity dam which is 35 m high

Figure 13 Schematic view of the Nant de Dranse project

Niveau min

2180.00 NM

Puits vertical

1695 NM*

Cavernes

Niveau min

-ΔH=180 m

ΔH=250 m

ΔH=375 m

1830.00 NM Galerie d’acces principate

Galerie d’amenee Galerie d’acces et de la ventilation

Reservoir de

Vieux Emosson

Niveau max 1930.00 NM