The energy source for ocean temperature difference is solar energy. Since it appears as thermal energy, it is also called ocean thermal energy.
The ocean is illuminated by the sun and converts energy from solar radiation into ocean thermal energy. In tropical and subtropical areas, surface sea water is maintained between 25 and 28 degrees Celsius and the temperature of deep sea water a few hundred meters away is stabilized between 4 and 7 degrees Celsius through the conversion of the thermal energy of the oceans. and the lower layers of seawater with different temperatures as sources of heat and cold, they can use their temperature differences to produce electricity.
With the exception of a small part of the solar energy received by the ocean which is directly reflected into the air, most of it will be absorbed by seawater. Water ofsea absorbs solar energy, water molecules move faster and water temperature increases.
In this way, the radiant energy of sunlight is converted into the kinetic energy of the thermal movement of seawater molecules and stored. Solar energy stored in seawater is what is often called ocean thermal energy.
When it comes to ocean depth, although it is “measurable” in terms of data, the mysteries contained in seawater thousands of meters or even tens of thousands of meters deep, can still be described as "non-measurable" describe.
Sunlight can only shine on the surface of seawater. As the depth of seawater increases, the amount of sunlight passing through it decreases. The deep sea area where sunlight cannot reach is a dark ocean world. This creates a big difference betweene surface seawater temperature and deep seawater temperature.
For example, the surface water temperature of the Persian Gulf and the Red Sea can reach 35°C, but at a depth of 500 to 1,000 meters underwater, the temperature of sea water is only 3 to 6°C. This vertical temperature difference causes the "uneven hot and cold" of sea water. It is this temperature difference that contains huge energy, which is the energy of the ocean temperature difference.