The movement of sea water in and out drives turbines.
A tidal barrage is built across estuaries, forcing water
through gaps.
In future underwater turbines may be possible out at sea
and without dam.
Should be ideal for an island country such as
the UK. Potential to generate a lot of energy
this way.
Tidal barrage can double as bridge, and help
prevent flooding
Construction of barrage is very costly.
Only a few estuaries are suitable.
Opposed by some environmental groups as
having a negative impact on wildlife. May
reduce tidal flow and impede flow of sewage
out to sea