Chapter 2: Energy Technology
2.1 Source of Wave Energy
Ocean waves are caused by the wind as it blows across the open expanse of water, the gravitational pull from the sun and moon, and changes in atmospheric pressure, earthquakes etc. Waves created by the wind are the most common waves and the waves relevant for most wave energy technology. Wave energy conversion takes advantage of the ocean waves caused primarily by the interaction of winds with the ocean surface. Wave energy is an irregular oscillating low-frequency energy source. They are a powerful source of energy, but are difficult to harness and convert into electricity in large quantities. The energy needs to be converted to a 60 Hertz frequency before it can be added to the electric utility grid. Wave energy generation is a developing technology. Although many wave energy devices have been invented only a small number have been tested and evaluated and very few of these have been tested in ocean waves – testing is usually undertaken in a wave tank.
2.2 Equipments used
a. Oscillating Water Columns
* The Nearshore OWC rests directly on the seabed and is designed to operate in the near-shore environment in a nominal mean water depth of 15m. * Nearshore OWC units also act like artificial reefs, improving environments for fishing while calming the water for a harbor. * OWC designs typically require high maintenance, costly, taut moorings or foundations for operation while only using the extreme upper strata of an ocean site for energy conversion. While focusing devices are less susceptible to storm damage, massive structuring renders them most costly among wave power plant types. * Since 1965, Japan has installed hundreds of OWC-powered navigational buoys and is currently operating two small demonstration OWC power plants. China constructed a 3 kW OWC and India has a 150 kW OWC caisson breakwater device. * A 75 kW shore-based demonstration plant by Queens University,...
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