Cheap electricity from French tides: The sea has demonstrated both friendly and adverse effects during the 14-year history of the Saint Malo plant

The unrelenting power of sea tides is driving turbogenerators in Northwest France and helping to produce enough electricity to supply an average French town with a population of 120 000. Nearly 500 million kilowatthours are being produced annually at a plant in the Rance estuary near Saint-Malo (Fig. 1).