What is meant by ocean thermal energy? Explain how ocean thermal energy can be used to generate electricity.

The energy that is generated due to the difference between the temperatures of water at the upper surface and the deeper layers of the ocean, is known as ocean thermal energy.

To generate electricity, we use 'Ocean Thermal Energy Conversion' (OTEC) power plants for which a temperature difference of 20℃ or more between the surface water and the water at deeper levels is needed. In this process, the warm surface water of the ocean is used to boil a liquid, like ammonia or chlorofluorocarbons. The high-pressure vapours obtained are used to rotate the turbine of a generator to produce electricity.