The energy from oceans is available in many forms. The main forms in which energy is available iron the oceans are : Ocean thermal energy; Energy of sea-waves; Tidal energy; Energy from limit gradient in the sea; Energy from sea-vegetation or biomass and energy from the nuclear fusion of deuterium (heavy hydrogen) present in sea-water. Let us discuss all this in detail.
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(i) Ocean Thermal Energy (OTE). There is always a temperature difference between the water :it the surface of ocean” and “at deeper levels.” At many places in the ocean, this difference in temperature of water is upto 20°C. The energy available due to the difference in the temperature of water at the surface of the ocean and at deeper levels is called ocean thermal energy (OTE). The ocean thermal energy can be converted into “usable form” of energy like electricity.
(ii) Sea-Waves Energy. Energy from the oceans is also available in the form of oceanic waves or sea-waves. Due to the blowing of wind on the surface of ocean, very fast sea-waves (or water waves) move on its surface. Due to their high speed, sea-waves have a lot of kinetic energy in them. The energy of moving sea-waves can be used to generate electricity. This can be done as follows : Some specially designed devices are set-up in the sea which move as the sea-waves pass them. Their movement can be used to drive dynamos which generate electricity.
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(iii) Tidal Energy. The rise of ocean water due to the attraction of moon is called “high tide” whereas the fall of ocean water is called “low tide.” The tidal waves in the oceans build up and recede (rise and fall) twice a day. The enormous movement of water between the high tides and low tides provides a very large source of energy in the coastal areas of the world. The tidal energy can be harnessed by constructing a tidal barrage (or tidal dam). The sea-water risen during the high title is trapped by the barrage. This water is then allowed to fall down slowly on water turbines due to which the water-turbines start rotating. The rotating water-turbines drive generators which produce electricity.
(iv) Energy from Salinity Gradient in Seas. The concentration of salts in the waters of different seas is different. The difference in the concentration of salts in the waters of two different seas is called “salinity gradient.” The difference in the concentration of salts where water from two different seas meets can be used to obtain energy in usable form.
(v) Energy from Sea-Vegetation or Biomass. Sea-vegetation or biomass is another indirect source of obtaining energy from the oceans. For example, the vast amount of sea-weeds present in oceans may provide an endless supply of methane fuel in future.
vi) Energy from the Nuclear Fusion of Deuterium present in Oceans. The ocean water is an I unlimited source of the heavy hydrogen atom called deuterium which is present in oceans in the form | of heavy water. Deuterium is that isotope of hydrogen which has one proton and one neutron in its nucleus. Efforts are being made to produce energy by carrying out the controlled nuclear fusion of deuterium isotope. When success is achieved in these efforts, then oceans will become such enormous source of energy which can supply us energy for billions of years.