Wave energy refers to any process that derives power from the movement of waves on the surface of a body of water. The energy in waves comes from wind, which is driven by unequal heating of the Earth by the sun. Wave energy is a very clean and renewable source of energy. It's not the same as tidal power, which uses the regular ebb and flow of the ocean to generate power. Instead there are several different methods of creating electricity from the movement of waves through water.
Waves and Energy
While water in a wave appears to move is single direction, in fact it is only the wave that propagates in that fashion. Individual molecules of water move in an ellipse and end where they began before the wave. It is this elliptical movement of the water, and anything floating in it, that is harnessed to produce wave energy.
Harnessing Wave Energy
The first method for producing wave energy that has succeeded on a commercial scale is the The Pelamis Wave Energy Converter in Scotland. This simple yet effective device is made of several metal cylinders connected by hinges. As the waves move the different sections in different directions relative to each other, hydraulic rams connected to the hinges pump oil through hydraulic motors, which drive electrical generators to produce electricity. A single cable sends the energy to the shore. The world's first wave energy farm, off the coast of Portugal, consisted of three Pelamis converters. England, Scotland and the United States have expressed interest in similar projects.
Other wave energy generators are buoys that float on the surface of the ocean anywhere from a few hundred feet offshore to several miles. Inside the buoys, the movement of the wave is transformed from mechanical energy to electrical energy, usually by the movement of water through a pump or the relative movement of electromagnetic converters. The wave energy produced is transmitted to shore by a power cable on the ocean floor. Closer to shore, wave power generators tend to be larger, using a series of pontoons rather than the smaller buoys, which are still 12 feet in diameter. This method, however, has not been used to produce significant amounts of energy.
A unique method of using wave energy in use off Fremantle, Western Australia, uses a buoy to drive a pump attached to the ocean floor. The pump is connected to shore via a pipe, which carries pressurized water to onshore hydraulic generators. Moving water collected this way can also power desalinization. Still other techniques for transforming the motion of water into usable energy focus on devices resembling vertically oriented turbines that are rotated directly by wave action.
- Photo Credit OCS/MMS, OCS/MMS, Wikimedia, Wikimedia
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