3.1. Tidal barrage
Tidal barrages consist of a large, dam-like structure built
across the mouth of a bay, or estuary in an area with a large
tidal range as illustrated in Fig. 6. It applies the principles of
hydroelectric generation from the tidal current flows in both
directions using turbines, sluice gates, embankments and ship
locks [37]. As the level of the water changes with the tides, a
difference in height develops across the barrage. Water is allowed
to flow through the barrage via the turbines, which can provide
power during the ebb tide (receding), flood tide (allowing water
to fill the reservoir via sluice gates during flood tide), or during
both tides. This generation cycle means that, depending on the site, power can be delivered twice, or four times per day on a
highly predictable basis. Two examples of famous tidal barrages
include the La Rance barrage in France and Incheon barrage
in Korea.