The ocean can produce two types of energy: thermal energy from the sun’s heat, and mechanical energy from the tides and waves.
Oceans cover more than 70% of Earth’s surface, making them the world’s largest solar collectors. The sun’s heat warms the surface water a lot more than the deep ocean water.
This temperature difference creates thermal energy. Just a small portion of the heat trapped in the ocean could power the world.
Ocean wave energy is form of the kinetic energy that exists in the moving waves of the ocean.
Only 0.1% of tidal energy can be used to supply power this whole world 5 times more than current global demand.
The World Renewable Energy Report estimates the cost of wave energy at an average of 9 cents/kWh and tidal and current an average of 8 cents/kWh.
Presently, the cost of power from ocean technologies ranges from 7 cents to 16 cents/kw in a low case scenario.
A barrage (dam) is typically used to convert tidal energy into electricity by forcing the water through turbines, activating a generator.
For wave energy conversion, there are three basic systems: channel systems that funnel the waves into reservoirs; float systems that drive hydraulic pumps; and oscillating water column systems that use the waves to compress air within a container.
The mechanical power created from these systems either directly activates a generator or transfers to a working fluid, water, or air, which then drives a turbine / generator.