A tidal barrage is designed to extract energy from the rise and fall of the tides and is relatively simple in concept. Thus a tidal barrage has only four main components: turbines, located in water passages which are designed to convert the potential energy of the difference in water levels across the barrage into kinetic energy in the form of fast-moving water. This kinetic energy is then converted into rotational energy by the blades of the turbines and then into electricity by generators driven by the turbines. Openings fitted with control gates, called sluices, which are designed to pass large flows under modest differential heads. These have a dual role. During construction, they allow the tides to continue to flow into and out of the basin behind the barrage with relatively little obstruction and thus enable the last parts of the barrage to be built without undue difficulty. Once the barrage is in operation, they refill the basin (or empty it) ready for the next power generation period. Locks or similar apparatus, to enable ships or boats to pass safely across the barrage after it is complete, and to pass safely through a part complete barrage where the remaining openings would have relatively fast-flowing water and/or construction activities in progress. Embankments, or else simple concrete caissons, which fill the remaining gaps across the estuary. These have to be reasonably 'opaque' to water flow so that water and energy are not wasted. They also provide a route to the working parts of the barrage for operation and maintenance staff and equipment, and a safe route for power cables from the barrage to the shore.

Inspec keywords: hydraulic turbines; tidal power stations; dams; blades

Other keywords: turbine blades; maintenance equipment; power generation; kinetic energy; energy extraction; hydroelectric turbines; control gates; concrete caissons; tidal power barrage

Subjects: Tidal power stations and plants