With the power of tide

This digest paper summarizes 30 years of operation of the Rance tidal power plant near Saint-Malo (France), before its renovation which stated in 1995. After 30 years of functioning, this plant appears as a technical and economical success for power production. The basic functioning principles of tidal plants is recalled and the Rance plant characteristics are compared to similar plants and future projects abroad. The building of the Rance plant has had several environmental consequences on the Rance estuary ecosystems and a different ecological equilibrium has been recovered progressively. The main environmental problem remains the sediment accumulation and the water quality in the estuary. (J.S.)