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Energy from sea

The seas and oceans and other water bodies are a source of kinetic and potential
energy due to the immense volume of water and the motion of waves.

Tidal energy

 Tides are variations in the level of water due to the gravitational pull of the moon.
 The phenomenon of rise and fall of water level or high and low tide gives tidal
energy.
 Tidal energy is obtained by constructing dams near the narrow openings of the
sea. When the tide sets in, it moves the turbine which directly produces
electricity.
 It is limited to places near the sea.

Wave energy

 Waves possess a lot of kinetic energy that can be harnessed to produce
electricity.
 Waves are produced by strong winds blowing over the sea.
 Limited to places with strong winds. Devices have been designed to capture this
energy.

Ocean thermal energy

 The difference in surface temperatures of water and water at a certain depth in
oceans is exploited to harness this form of energy.
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 Temperature difference must be 20 c between the surface and water up to
depths of 2 km.
 Warm water is used to boil volatile ammonia to form vapours that move the
turbine. Cold water is used to condense the vapour back to liquid.