... Variations in water level along coastlines can be used to drive turbines technology is the same as low-head hydro power . ... Intermittent tidal flow is major problem. Tidal facility produces about 1/3 the electrical energy of a hydro facility of the same peak capacity . Two tidal plants in the world: . ... Bottom Line: There aren't many favorable sites in the world for tidal power and the estimated capacity is 50 times smaller than the world's hydroelectric power capacity. ...