Science: Tidal Power

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Ever since electricity came into its own, harnessing the potential of the tides has been one of man's pet schemes.* It remained for the power-short French to translate a major scheme into action. Last week Electricité de France, the nationalized power combine, announced that work would start next spring on a $57 million tidal project near Saint-Malo on the Brittany coast.

Key to the power project will be a concrete dam, 625 ft. long and 154 ft. thick, across the narrow estuary of the River Rance. Twice daily, as the 27-ft. tide rises, the sea will flow through the dam's water gates until slack tide. Then the gates will be shut. Three hours later, as the tide ebbs, the trapped water in the estuary will fight its way through 26 turbines (each 14,000 h.p.) to the sea.

With water pushing through the turbines at the rate of 176,500 cu. ft. per second, the Rance Valley project will produce an annual 550 million kw-h of electricity—enough to supply the needs of a city about the size of Richmond, Va. Estimated completion date: 1960.