Energy resources: tidal energy

The rise and fall of ocean tides result from the combined gravitational pull on water by the Moon and, to a lesser extent, bu the Sun, which exerts a force on water directed towards the two astronomical bodies. These gravitational effects combine with centrifugalo forces that result from the Earth and the Moon orbiting each other to make the details of tidal changes complex. This unit considers the power of the ocean tides as a potential source of useable energy and whether or not they can ever make any significant contribution to global energy suppllies.