The various forms in which energy is available from the sea are:

(a) Tidal Energy: The enormous movement of water between the high tides and low tides provides a very large source of energy in coastal areas of the world. The tidal energy can be harnessed by constructing a tidal barrage or tidal dam or tidal dam across the narrow opening to the sea.

(b) Wave Energy: Due to the high speed, sea waves have a lot of kinetic energy in them. The energy of moving sea waves can be used to generate electricity.

(c) Ocean Thermal Energy: The energy availability due to the difference in temperature of water at the surface of the ocean and at deeper levels is called ocean thermal energy. The device used to harness ocean thermal energy is called Ocean Thermal Energy Conversion Power Plant (OTEC power plant).

Limitations of Harnessing:

Tidal Energy:

There are very few sites around the world which are suitable for building tidal barrages or tidal dams.

Rise and fall of sea water during high and low tides is not enough to generate electricity on high scale.

Wave Energy:

The harnessing of sea wave energy would be a viable proposition only in those places where sea waves are very strong.