Ocean Energy



One of the most abundant sources of renewable energy on Earth is ocean energy. That is because around 70% of the Earth’s surface is covered by water. Not only is ocean energy abundant, it is also one of the most powerful forces on our planet. Few people realize that ocean tides are caused by the gravitation pull of the sun and moon upon the Earth. As the Earth rotates, the relative positions of the sun and moon changes, causing ocean water to rise and follow the gravitation wake.

The sun affects the ocean in another way as well. As light from the sun strikes the Earth’s oceans, it is converted into thermal energy. This thermal energy creates differences in ocean temperature, causing the water to circulate. Both the thermal and mechanical energy of the Earth’s oceans can be used to produce renewable energy.

The process of turning thermal ocean energy into electricity is called Ocean Thermal Energy Conversion (OTEC). OTEC makes use of the temperature difference between the warm top layers of ocean water, and the cold lower layers. The process begins by pumping warm ocean water through a heat exchanger. This heat is then used to evaporate a liquid with a low-boiling point, such as ammonia. As the ammonia boils, it generates steam pressure, which is used to generate electricity. The cold ocean water is then used to condense the gaseous ammonia back into its liquid state, and the process begins again.

Another way of harnessing ocean energy is through the use of submerged turbines, which work on the same principle as wind turbines. As water moves over the water turbine, it causes the propeller blades to spin. This spinning motion then turns a generator, which produces electricity. These tidal turbines are actually more efficient then wind turbines: a tidal turbine with a fifteen-meter diameter can produce the same amount of electricity as a wind turbine with a 60-meter diameter. Another method of converting ocean energy into electricity is by utilizing wave energy. This method makes use of floating buoys that convert the bobbing motion of ocean waves into electricity. The electricity is then sent to shore through underwater cable.

If developed to its full potential, ocean energy could provide a substantial amount of our electricity. Renewable energy experts believe that ocean energy could generate 2 terawatts of electricity, which is equal to 2 trillion watts of electricity. 

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