The Source of Ocean Thermal Energy is

The correct answer is None of the above.

Key Points

• Ocean Thermal Energy also called Ocean Thermal Energy Conversion (OTEC) refers to a method of using the temperature difference between the deep parts of the sea which are hot and the shallow parts of the sea which are cold to run a heat engine and produce useful work. Basically, Ocean thermal energy conversion is an electricity generation system. 
• Ocean Thermal Energy Conversion uses the ocean thermal gradient between a cooler deep and warmer shallow or surface seawaters to run a heat engine and produce useful work, usually in the form of electricity.

Additional Information 

• The water at the surface of the sea or ocean is heated by the Sun while the water in deeper sections is relatively cold.
• This difference in temperature is exploited to obtain energy in ocean-thermal-energy conversion plants.
• These plants can operate if the temperature difference between the water at the surface and water at depths up to 2 km is 293 K (20C) or more.
• The warm surface- water is used to boil a volatile liquid like ammonia.
• The vapors of the liquid are then used to run the turbine of the generator.
• The cold water from the depth of the ocean is pumped up and condenses vapor again to liquid.
• The energy potential from the sea (tidal energy, wave energy, and ocean thermal energy) is quite large, but efficient commercial exploitation is difficult.