The oceans cover a little more than 70 percent of the Earth's surface. General speaking, ocean energy refers to the natural and renewable energy hold in store in the ocean, mainly including the tidal energy, wave energy, current energy, temperature differential energy and the salt differential energy as well. More broad sense of ocean energy should include the wind energy above the ocean, solar energy on the surface of ocean and the marine biomass energy. Tracing to the source, the tidal energy and current energy are originated from the gravitational force difference of the sun and the moon upon the earth, while others from the solar radiation. 

According to storage forms of ocean energy, it can be also divided into mechanical energy, thermal energy and chemical energy, among which tidal energy, current energy and wave energy belong to mechanical energy, and temperature differential energy belong to thermal energy, and salt differential energy belong to chemical energy.

Related Topics and Papers:

The Present Status of Ocean Energy Exploration in China

Ocean Energy Prospects in China

Prospects of Ocean Energy Utilization and Proposals for the Development Strategy in China