The power of the ocean can produce both thermal energy and mechanical energy. The sun’s heat produces thermal energy, while the force of tides and waves creates mechanical energy.
Since oceans cover more than 70% of Earth’s surface, they are considered the world’s largest solar collectors. The ocean absorbs enough heat on a daily basis from the sun to equal the energy from 250 billion barrels of oil. The temperature difference between the heated ocean surface and the deep ocean waters creates thermal energy, of which a small portion could have the potential to power the world with electricity. Ocean thermal energy conversion systems (OTEC) are used to turn thermal energy into electricity.
The mechanical energy created by the force of ocean tides and waves differs greatly from the thermal energy created by the sun. Tidal and wave movements are driven by the pull of the moon and the wind, respectively, which makes their energy much less constant than that of ocean thermal energy. Additionally, mechanical devices are generally used to convert energy from tides and waves. Tidal energy is converted to electricity through the use of a barrage, or dam. Water is forced through turbines, which activates a generator using traditional hydropower technology. Wave energy is extremely powerful, with estimates of total wave power on global coastlines to be between two and three million megawatts.
Sources: National Renewable Energy Laboratory (NREL) and U.S. Department of Energy (Energy Efficiency and Renewable Energy)