The Rance Tidal Power Station is a

tidal power Tidal power or tidal energy is harnessed by converting energy from tides into useful forms of power, mainly electricity using various methods. Although not yet widely used, tidal energy has the potential for future electricity generation. T ...

station located on the

estuary An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime enviro ...

of the

Rance River The Rance (; , ) is a river of northwestern France. It is long. The semi-tidal river flows into the English Channel between Dinard and Saint-Malo. Before reaching the Channel, its waters are barred by a 750 metre long dam forming the Rance tid ...

Brittany Brittany ( ) is a peninsula, historical country and cultural area in the north-west of modern France, covering the western part of what was known as Armorica in Roman Gaul. It became an Kingdom of Brittany, independent kingdom and then a Duch ...

, France. Opened in 1966 as the world's first tidal power station, the 240-

megawatt The watt (symbol: W) is the unit of Power (physics), power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantification (science), quantify the rate of Work ...

(MW) facility was the largest such power station in the world by installed capacity for 45 years until the 254-MW

South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia. It constitutes the southern half of the Korea, Korean Peninsula and borders North Korea along the Korean Demilitarized Zone, with the Yellow Sea to the west and t ...

n Sihwa Lake Tidal Power Station surpassed it in 2011.

Characteristics

The power station has 24

turbines A turbine ( or ) (from the Greek , ''tyrbē'', or Latin ''turbo'', meaning vortex) is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work. The work produced can be used for generating electrical ...

. These reach total peak output at 240 MW, and produce an annual output of approximately 500 GWh (2023: 506 GWh; 491 GWh in 2009, 523 GWh in 2010); thus the average output is approximately 57 MW, and the

capacity factor The net capacity factor is the unitless ratio of actual electrical energy output over a given period of time to the theoretical maximum electrical energy output over that period. The theoretical maximum energy output of a given installation is def ...

is approximately 24%. The turbines are "bulb"

Kaplan turbine The Kaplan turbine is a propeller-type water turbine which has adjustable blades. It was developed in 1913 by Austrian professor Viktor Kaplan, who combined automatically adjusted propeller blades with automatically adjusted wicket gates to a ...

s, of nominal power 10 MW; their diameter is 5.35 m, each has 4 blades, their nominal rotation speed is 93.75

rpm Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or r⋅min−1) is a unit of rotational speed (or rotational frequency) for rotating machines. One revolution per minute is equivalent to hertz. Standards ISO 80000-3:2019 def ...

and their maximal speed 240 rpm. Half of the turbines were built from

martensitic Martensite is a very hard form of steel crystalline structure. It is named after German metallurgist Adolf Martens. By analogy the term can also refer to any crystal structure that is formed by diffusionless transformation. Properties Mart ...

stainless steel Stainless steel, also known as inox, corrosion-resistant steel (CRES), or rustless steel, is an iron-based alloy that contains chromium, making it resistant to rust and corrosion. Stainless steel's resistance to corrosion comes from its chromi ...

, the other half from

aluminium bronze Aluminium bronze is a type of bronze in which aluminium is the main alloying metal added to copper (for alloys with aluminum as the major component, see aluminum copper alloy), in contrast to standard bronze (copper and tin) or brass (copper an ...

. The plant is equipped with

cathodic protection Cathodic protection (CP; ) is a technique used to control the corrosion of a metal surface by making it the cathode of an electrochemical cell. A simple method of protection connects the metal to be protected to a more easily corroded " sacrifi ...

against

corrosion Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engine ...

. It supplies 0.12% of the power demand of France. The power density is of the order of 2.6 kW/m². The cost of electricity production is estimated at 0.12€/kWh. The barrage is long, from Brebis point in the west to Briantais point in the east. The power plant portion of the dam is long and the tidal basin measures .

History

An early attempt to build a tidal power plant was made at

Aber Wrac'h Aber Wrac'h is a small village and port located on the river which shares its name in the commune in France, commune of Landéda in the department of Finistère in France, located in Brittany. The source of the Wrac'h river is in Trémaouézan. ...

in the

Finistère Finistère (, ; ) is a Departments of France, department of France in the extreme west of Brittany. Its prefecture is Quimper and its largest city is Brest, France, Brest. In 2019, it had a population of 915,090.tidal mills have long existed in areas exposed to

tide Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide tables ...

s, particularly along the Rance. The idea of constructing a tidal power plant on the Rance dates to Gerard Boisnoer in 1921. The site was attractive because of the wide average-range between low and high tide levels, with a maximum

perigean spring tide A perigean spring tide is a tide that occurs three or four times per year when a perigee (the point nearest Earth reached by the Moon during its 27.3-day elliptic orbit) coincides with a spring tide (when the Sun, the Moon, and Earth are nearly ...

range of . The first studies which envisaged a tidal plant on the Rance were done by the

Society for the Study of Utilization of the Tides A society () is a group of individuals involved in persistent social interaction or a large social group sharing the same spatial or social territory, typically subject to the same political authority and dominant cultural expectations. Soc ...

in 1943. Nevertheless, work did not actually commence until 1961.

Albert Caquot Albert Irénée Caquot (; 1 July 1881 – 28 November 1976) was a French engineer. He received the “Croix de Guerre 1914–1918 (France)” (military honor) and was Grand-croix of the Légion d’Honneur (1951). In 1962, he was awarded the Wi ...

, the visionary engineer, was instrumental in the construction of the dam, designing an enclosure in order to protect the construction site from the ocean tides and the strong streams. Construction necessitated draining the area where the plant was to be built, which required construction of two dams which took two years. Construction of the plant commenced on 20 July 1963, while the Rance was entirely blocked by the two dams. Construction took three years and was completed in 1966.

Charles de Gaulle Charles André Joseph Marie de Gaulle (22 November 18909 November 1970) was a French general and statesman who led the Free France, Free French Forces against Nazi Germany in World War II and chaired the Provisional Government of the French Re ...

, then

President of France The president of France, officially the president of the French Republic (), is the executive head of state of France, and the commander-in-chief of the French Armed Forces. As the presidency is the supreme magistracy of the country, the po ...

, inaugurated the plant on 26 November of the same year. Inauguration of the road crossing the plant took place on 1 July 1967, and connection of the plant to the French National Power Grid was carried out on 4 December 1967. In total, the plant cost ₣620 million (approximately

€ The euro sign () is the currency sign used for the euro, the official currency of the eurozone. The design was presented to the public by the European Commission on 12 December 1996. It consists of a stylized letter E (or epsilon), crossed by t ...

94.5 million). It took almost 20 years for the La Rance to pay for itself.

Assessments

In spite of the high development cost of the project, the costs have now been recovered, and electricity production costs are lower than that of

nuclear power Nuclear power is the use of nuclear reactions to produce electricity. Nuclear power can be obtained from nuclear fission, nuclear decay and nuclear fusion reactions. Presently, the vast majority of electricity from nuclear power is produced by ...

generation (1.8 ¢/kWh versus 2.5 ¢/kWh for nuclear). However, the

of the plant is 28%, lower than 85–90% for nuclear power.

Environmental impact

The barrage has caused progressive silting of the Rance ecosystem. Sand-eels and

plaice Plaice is a common name for a group of flatfish that comprises four species: the European, American, Alaskan and scale-eye plaice. Commercially, the most important plaice is the European. The principal commercial flatfish in Europe, it is ...

have disappeared, though

sea bass Sea bass is a common name for a variety of species of marine fish. Many fish species of various families have been called sea bass. In Ireland and the United Kingdom, the fish sold and consumed as sea bass is exclusively the European bass, ''Dic ...

and

cuttlefish Cuttlefish, or cuttles, are Marine (ocean), marine Mollusca, molluscs of the order (biology), suborder Sepiina. They belong to the class (biology), class Cephalopoda which also includes squid, octopuses, and nautiluses. Cuttlefish have a unique ...

have returned to the river. By definition, tides still flow in the estuary and the operator, EDF, endeavours to adjust their level to minimize the biological impact.

Tourist attraction

A tourist facility at the dam is open to visitors. The facility attracted approximately 40,000 visitors in 2011. A lock for navigation at the west end of the dam allows the passage of 1,600-tonne vessels between the

English Channel The English Channel, also known as the Channel, is an arm of the Atlantic Ocean that separates Southern England from northern France. It links to the southern part of the North Sea by the Strait of Dover at its northeastern end. It is the busi ...

and the Rance. Departmental road 168 crosses the dam and allows vehicles to travel between

Dinard Dinard (; , ; Gallo: ''Dinard'') is a commune in the Ille-et-Vilaine department, Brittany, northwestern France. Dinard is on the Côte d'Émeraude of Brittany. Its beaches and mild climate make it a holiday destination, and this has resul ...

and

Saint-Malo Saint-Malo (, , ; Gallo language, Gallo: ; ) is a historic French port in Ille-et-Vilaine, Brittany (administrative region), Brittany. The Fortification, walled city on the English Channel coast had a long history of piracy, earning much wealth ...

. There is a

drawbridge A drawbridge or draw-bridge is a type of moveable bridge typically at the entrance to a castle or tower surrounded by a moat. In some forms of English, including American English, the word ''drawbridge'' commonly refers to all types of moveable b ...

where the road crosses the lock which is raised to allow larger vessels to pass. The Rance estuary is the first part of the inland waterway from the English Channel to the Bay of Biscay via the Canal d'Ille-et-Rance and the river Vilaine.

References

External links

* * * {{cite journal, journal=La Houille Blanche, url=https://www.shf-lhb.org/articles/lhb/pdf/1962/04/lhb1962028.pdf, number=2, year=1962, title=The Rance tidal power plant * ''La Houille Blanche''
n. 2-3, April 1973
* ''La Houille Blanche''

Energy infrastructure completed in 1963 Tidal power stations in France Coastal construction Buildings and structures in Ille-et-Vilaine Saint-Malo Tidal barrages Électricité de France Tourist attractions in Ille-et-Vilaine Articles containing video clips 1963 establishments in France 20th-century architecture in France