.
"Waves are caused by wind and their enormous potential energy can be tapped using hydraulic or mechanical means to translate the up-and-down motion to rotate a generator" (blah 338). Energy from the tides can be harnessed in two ways: By using the change in height of the tides (potential) or by using the flow of the water (kinetic). In order to harness power from the movement of the ocean and tides, several devices have been designed to do this. Three most common technologies evolved are In-stream devices, barrages, and tidal lagoons. .
In-stream devices make use of the kinetic energy harnessed in water in order to power turbines. This method is popular because it can be scaled up from device to a larger one. Also, it costs less than other technologies. Barrages make use of the potential energy harnessed in water through the difference of height in high and low tides. Typically, they are dams across the mouth of a river that connects into the ocean. Tidal barrages first allow water to flow into the bay or river during high tide, and release it back during low tide. They are extremely expensive and are associated with many environmental concerns. Tidal lagoons are most similar to barrages that trap high water and release it to generate power. .
One of the in-stream devices includes the "Salter Duck". Placed inside the ocean, the duck "bobs" up and down along side the waves. On the inside, a special "turbine" converts this movement into energy. In order to take advantage of wave formations, these ducks are arranged in set patterns along the sea. Each salter duck is as large as a Double Decker bus. Each device operates on an electricity system based on a pendulum attached to a generator. As the duck "bobs" the pendulum swings back and forth forming electricity. Because of its complicated design, it still hasn't been perfected just yet.
