The diagrams below show a structure that is used to generate electricity from wave power. Summarise the information by selecting and reporting the main features, and make comparisons where relevant.

The two diagrams illustrate a method of creating electricity from the force of waves using a specifically designed man-made construction. The structure, consisting of a wave chamber and a tall column containing a

turbine

, is erected on a steeply sloping coastal cliff or sea wall where it is subject to the movement of the ocean waves. The first diagram shows how the incoming wave fills a large chamber and forces the

air

inside

this

space up the column and through the

turbine

. The pressure of the

air

rotates the

turbine

which generates a current of electricity. The process does not end there for the structure is able to continue producing power as the sea recedes as can be seen in the second diagram. As the water now flows away from the structure, it draws

air

back down the column and downwards through the

turbine

in the same direction as the previous upward flow of

air

. The

turbine

continues to turn

thus

generating even more electricity.