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Mauvoisin Dam in Switzerland gives power to 300,000 houses | See how it's done

Updated: Aug 10, 2020

General Info 📚

  • Construction Dates: 1951 - 1957

  • Type of dam: Concrete variable radius arch dam

  • Height: 250 m (820 ft)

  • Length: 520 m (1,710 ft)

  • Total capacity: 211,500,000 m3(171,500 acre⋅ft)

  • Catchment area: 167 km2 (64 sq mi)

  • Surface area: 208 ha (510 acres)

  • The power produced: 363 MW which can power approximately 300,000 homes 💡

  • The dam is the 11th highest in the world and the 6th highest arch dam

About the Reservoir - Lac de Mauvoisin

The reservoir is formed by the Mauvoisin Dam, which is 250 m high.

  • Max. length : 4.9 km (3.0 mi)

  • Surface area : 2.08 km2 (0.80 sq mi)

  • Maximum depth: 180 m (590 ft)

  • Surface elevation: 1,961 m (6,434 ft)

Lac de Mauvoisin in the canton of Valais, Switzerland. The reservoir lies in the upper Val de Bagnes, between the massif of the Grand Combin, one of the highest mountains of the Alps, and La Ruinette. The highest peak visible from the lake is the Combin de la Tsessette (4,135 m).


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About the Mauvoisin Dam - Arch Dam

The arch dam is designed so that the force of the water hydrostatic pressure that is pressed against the arch from the water mass stored in the reservoir behind it.

An arch dam is most suitable for narrow canyons with steep walls of stable rock to support the structure and stresses. Since they are thinner than any other dam type, they require much less construction material, making them economical and practical in remote areas.

Arch Dam

A Rule of Thumb when designing is:

The ratio of base thickness to the structural height (b/h):

  • Thin: (b/h) less than 0.2

  • Medium: (b/h) between 0.2 and 0.3

  • Thick, for (b/h) over 0.3

Arch dams classified with respect to their structural height are:

  • Low dams: 100 feet (30 m)

  • Medium dams: 100–300 ft (30–91 m)

  • High dams: 300 ft (91 m)

Mauvoisin Dam
Mauvoisin Dam

Water Turbine Engineering ⛲️

Mauvoisin Dam provides a hydraulic head of 482 m (1,581 ft) to the Fionnay generating station, which can produce 138 MW from three Francis turbines.

The water then drops another 1,014 m (3,327 ft) to the Riddes generating station, where it drives five Pelton turbines with a combined capacity of 225 MW.

The two plants produce about 943 million kilowatt-hours (KWh) each year, with Fionnay generating 278 million kWh (29.5%) and Riddes generating 665 million kWh (70.5%).

Francis turbine🎡🏗

The Francis turbine is a type of water turbine that was developed by James B. Francis in Lowell, Massachusetts. It is an inward-flow reaction turbine that combines radial and axial flow concepts.

Francis turbine
Francis turbine

Francis turbines are the most common water turbine in use today. They operate in a water head from 40 to 600 m (130 to 2,000 ft) and are used primarily for electrical power production.

The electric generators that most often use this type of turbine have a power output that generally ranges from just a few kilowatts up to 800 MW, though mini-hydro installations may be lower.

Francis turbines Elevation
Francis turbines Elevation

Penstock (input pipes) diameters are between 3 and 33 ft (0.91 and 10 m). The speed range of the turbine is from 75 to 1000 rpm. A wicket gate around the outside of the turbine's rotating runner controls the rate of water flow through the turbine for different power production rates.

Francis turbines are almost always mounted with the shaft vertical so as to isolate water from the generator. This also facilitates installation and maintenance.

Pelton wheel🎡🏗

Old Pelton wheel from Walchensee Hydroelectric Power Station, Germany.
Old Pelton wheel from Walchensee Hydroelectric Power Station, Germany.

The Pelton wheel is an impulse type water turbine invented by Lester Allan Pelton in the 1870s. The Pelton wheel extracts energy from the impulse of moving water, as opposed to water's dead weight like the traditional overshot water wheel.

Many earlier variations of impulse turbines existed, but they were less efficient than Pelton's design. Water leaving those wheels typically still had high speed, carrying away much of the dynamic energy brought to the wheels.

Pelton's paddle geometry was designed so that when the rim ran at half the speed of the water jet, the water left the wheel with very little speed; thus his design extracted almost all of the water's impulse energy—which allowed for a very efficient turbine.

Pelton Wheel Diagram
Pelton Wheel Diagram


Source: Wikipedia


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