Wave energy converter (WEC) device and system
AssigneeOcean Power Technologies, Inc.
InventorsJames Gerber, David B. Stewart
Life of this patent
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Abstract
A wave energy converter system comprises two floats; a first being generally flat and heaving up and down in phase with passing surface waves on a body of water, and the second being elongated and heaving up and down out of phase with the passing waves. Preferably, the first float is annular with a central vertical opening therethrough, and the elongated float, with a weighted bottom end, extends vertically through the central opening of the first float. The two floats thus move out of phase with one another, thus providing a relatively large relative motion between the two floats giving rise to highly efficient energy conversion. Each float serves as a “ground” for the other; thus avoiding the need for anchoring the floats to the floor of the body of water.
Claims7
Apparatus for capturing energy from surface waves on a body of water comprising first and second floats, said first float having a generally flat configuration, and said second float being configured as an elongated spar,
- the draft of said first float being substantially less than the draft of said second float,
- each float having an intercept with the water surface,
- a power take-off element connected between said floats for converting relative movements therebetween into useful energy,
- said floats being configured to rise and fall in response to passing surface waves in out-of-phase relation with one another for causing relative movements between said floats, and
- said first and second floats having configuration values g/Z which are greater and less than ω2, respectively, where:
- g=acceleration due to gravity;
- Z=the effective depths of the floats;
- and
- ω=the angular frequency of the passing waves;
- and where:
- Z(effective depth)=VD/As, where:
- VD is the volume of the water displaced by the float including hydrodynamic added mass;
- and
- As is the waterplane area of the float.
Apparatus for capturing energy from surface waves on a body of water comprising first and second floats of different shapes and different drafts for rising and falling in out-of-phase relationship with one another in response to passing waves for causing relative movements between the floats, said first and second floats have configuration values g/Z which are greater and less than ω2, respectively, where:
- g=acceleration due to gravity;
- Z=the effective depths of the floats;
- and
- ω=the angular frequency of the passing waves;
- and where:
- Z(effective depth)=VD/As, where:
- VD is the volume of the water displaced by the float including hydrodynamic added mass;
- and
- As is the waterplane area of the float,
- and a power take-off element connected between said floats for converting relative movements between the floats into useful energy.
Dependencies are inferred from the claim text.