The Rance Tidal Power Station is the world's first tidal power station and also the world's second biggest tidal power station. The facility is located on the estuary of the Rance River, in Brittany, France. Opened on the 26th November 1966, it is currently operated by EDF, and is the second largest tidal power station in the world, in terms of installed capacity. With a peak rating of 240 MW, generated by its 24 turbines, it supplies 0.012% of the power demand of France. With a capacity factor of approximately 40%, it supplies an average 96 MW, giving an annual output of approximately 600 GWh. The barrage is 750m (2,461ft) long, from Brebis point in the west to Briantais point in the east. The power plant portion of the dam is 332.5m (1,091ft) long. Power is generated from 24 bulb turbines with a 5.35m (17.55ft) diameter that rotates at 93.75rpm and is rated at 10MW at a head of 5.65m (18.54ft).
The facility is located on the estuary of the Rance River near Saint Malo, Britany, France. This estuary has an average tidal range of 8.2m (13.5m maximum) with a reservoir of 184,000,000m3 over a 22km2 basin area that creates a maximum flow of 9,600m3/s.
It took six years to complete, and was commissioned at various stages between August 1966 and December 1967. The following were the most important stages of its construction: January, 1961: commencement of work. 19th November, 1962: commissioning of the lock. 24th March, 1963: commissioning of the sluice-way section of the dam. 20th July, 1963: final closure of the dam across the estuary. 19th August, 1966: on-line connection of the first power set. 26th November, 1966: inauguration by the President of France. 1st July, 1967: inauguration of the road across the dam. 4th September, 1967: commissioning of the twenty-fourth power set. The plant is currently operating.
The barrage has caused progressive silting of the Rance ecosystem. Sand-eels and plaice have disappeared, though sea bass and cuttlefish have returned to the river. By definition, tides still flow in the estuary and the operators, EDF endeavors to adjust their level to minimize the biological impact.