Oscillating water column wave energy converter incorporated into caisson breakwater

Abstract

A caisson breakwater provided with vertical duct 2″, room 3″, air-duct 4″, self-rectifying turbine 5″. Under the fluctuations of wave pressure on the outer opening 6, the water, alternately, enters and exits, so that the air in room 3″, alternately, is compressed and expands, and an alternate air flow is produced in the air-duct 4″. The vertical duct 2″ and the room 3′, form a U-conduit, and the air in the room 3″ acts as a spring. The eigenperiod of oscillations in said U-conduit grows as the width of the vertical duct 2″ is reduced and / or the length of said vertical duct is increased, and / or the width and height of the room 3″ is increased. The eigenperiod is fixed close to the wave period of the waves which convey the largest amount of wave energy in a year, so as to absorb a very large quantity of wave energy.

Description

TECHNICAL FIELD [0001] The invention discloses a caisson breakwater which is able to protect a port or a marine sheet of water with a small wave reflection, and is able to convert wave energy into electric power. BACKGROUND ART [0002] Caisson breakwaters (see e.g. Goda Y., Random Seas and Design of Maritime Structures, World Scientific, chap. 4, 2000; or Boccotti P., Wave Mechanics for Ocean Engineering, Elsevier, chap. 13, 2000) consist of caissons in reinforced concrete close to each other or linked together, on a foundation on the seabed. Each caisson is subdivided into a number of cells by vertical walls. Typically the caissons are manufactured in dry docks, towed and sunk. The cells are filled with sand and / or gravel and / or concrete or other kind of ballast. Then a superstructure is cast in concrete. [0003] Caisson breakwaters are excellent for protecting ports, because they can be built easily and are very resistant The only flaw is that they reflect nearly all the incident wa...

AI Technical Summary

Benefits of technology

"The invention is a caisson breakwater that uses a U-shaped duct and a room to absorb wave energy. The breakwater works by allowing waves to enter the U-shaped duct and create pressure fluctuations that cause the air in the room to expand and produce an alternate air flow that drives a turbine. This results in the breakwater absorbing a significant amount of wave energy, reducing the amount of reflected wave energy. The breakwater does not require phase control or compressors and can be easily controlled by adjusting the water level in the room. The compact structure of the breakwater makes it suitable for use in shallow water."

Problems solved by technology

Of course, the wave amplification may be dangerous for boats and ships approaching a port, and the overtopping discharge may be dangerous for persons, facilities, and boats inside a port.

These breakwaters are able to protect beaches from erosion, but they cannot protect a port because a part of the wave energy goes beyond these breakwaters.

As a wave energy converter the caisson of U.S. Pat. No. 6,450,732 B1 has the turbine beneath the sea level, which implies some difficulty of maintenance and the need for a water-tight room for a generator.

Moreover, to improve the efficiency, OWCs need some complex devices for phase control.

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