Name the three forms in which energy from oceans is made available for use. What are $OTEC$ power plants? How do they operate?

(N/A) The three forms of energy from the oceans are:
$(i)$ Tidal energy
$(ii)$ Ocean wave energy
$(iii)$ Ocean thermal energy
Ocean Thermal Energy Conversion $(OTEC)$ power plants are facilities designed to harness the temperature difference between the warm surface water of the ocean and the cold water at deeper levels to generate electricity.
Operation:
$1$. In an $OTEC$ power plant,the warm surface water of the ocean is used to boil a volatile liquid like ammonia.
$2$. The high-pressure vapours of this liquid are then used to drive turbines,which in turn rotate generators to produce electricity.
$3$. The cold sea water from deeper levels is pumped up to condense the vapours back into a liquid,which is then recycled.
$4$. This system can operate continuously for $24$ hours a day.