The Rance site lent itself well to such a project. First, because the amplitude between low and high tides is one of the highest in the world (it reaches up to 13.5 metres during equinoctial tides); second, because the estuary offers a reservoir of 22 km2 capable of impounding 180 million m3. At peak periods, 18,000 m3 of water per second go through the estuary, or a flow that is ten times greater than that of the Rhone River.
To harness such power, the estuary had to be blocked by a structure 750 metres long and 13 metres high. Twenty-five years of studies and six years of construction works were needed to erect the Rance tidal power plant. Since 1967, this facility, the only full-scale power station of this type in the world, generates 600 million kWh every year, enough to provide energy to 250,000 households.