ENERGY
Marine Current Energy
Energy exists in the oceans in several different forms, one of which is marine current energy. Marine current is caused by tidal effects and thermal and salinity differences of sea water.
Under the most likely commercial development scenario, energy would be extracted from ocean currents by using submerged water turbines similar to wind turbines. These turbines would have rotor blades, a generator for converting the rotational energy into electricity, and a means of transporting the electrical current to shore for incorporation into the electrical grid. Also, there would need to be a way to keep the turbines stationary, such as posts or cables anchored to the sea floor. Additional components might include concentrators (or shrouds) around the blades to increase the flow and power output from the turbine.
Unlike wind, because water is much denser than air, the size of turbine needed to extract energy underwater can be much smaller than a wind turbine. The velocities of the currents are lower than those of the wind. However, owing to ocean water is some 840 times denser than air, so speeds of about one-tenth of that of the wind speed can generate the same power.
