There is a great deal of energy in tides. To use it, we can build a large dam, called a tidal [?], across an [?] where the tides are strong. There are proposals to build one across the river [?] in the UK.

Tidal energy is [?], needs no [?] and produces no [?]. However, such a huge dam is very [?] to build and will affect the environment over a [?] area. The largest one in the world so far is in the Rance estuary, in [?].

An alterntive is 'offshore [?]', like an underwater wind farm. This will not have such a dramatic effect on the surrounding area.

It will only generate power when the tide is going [?] or [?], but we know when this will be so we can easily plan for it.