Ocean Power Technologies, Inc.

Olean Power Technologies, Inc.

James S Gerber

David B Stewart

George W Taylor

William Blaine Powers

Diana Bull

Thomas R Welsh

Wei Qiu

Donald Smith Spencer

Christopher Thomas Phelan

Thomas J Meaney

Christopher T Phelan

A wave energy converter (WEC) having an asymmetrically shaped float and a spar which move relative to each other in response to the waves. The asymmetrical float has one side longer than the other. A power take off device (PTO) is coupled between the asymmetric float and the spar for converting their relative motion into useful power. Apparatus is coupled to the WEC for: (a) orienting and rotating the longer side of the float to face and receive oncoming waves to increase energy capture when the waves have an amplitude below a predetermined value for improving the power generation of the WEC; and (b) rotating the float to orient the narrower side of the float to face and receive the incoming waves when the waves have an amplitude above a predetermined value, so as to reduce the forces to which the WEC is subjected. There is no known WEC system with an asymmetrical float which is raised and lowered by the waves.

Wave energy converter with asymmetrical float

A wave energy converter (WEC) system includes first and second bodies which can move relative to each other in response to waves and a power-take-off (PTO) device coupled between the two bodies to convert their relative motion into energy. A sensor is used to sense selected characteristics of an incoming wave and produce signals which are applied to a control computer for predicting the impact of the incoming waves on the WEC. Simultaneously, signals indicative of the actual conditions (e.g. the velocity) of the WEC are also supplied to the control computer which is programmed to process the predicted and actual information in order to generate appropriate signals (forces) to the components of the WEC such that the average wave power captured by the PTO is maximized.

Advanced wave energy converter control

A float structure for a WEC is designed to have a tapered underside to reduce the impact due to wave slam and bending moments while providing little reduction in the surface area responding to the wave surface in order to maintain the beneficial power generating capability of a 'flat' float. The underside of the float presents an inverted wedge section to decrease loads associated with wave slamming. The float may have a generally toroidal or elliptical configuration at and about the 'still' water line with the generally submerged underside of the float having a cross section shaped to have one or more inverted triangular sections extending between the outer perimeter of the float and its center to reduce impact loading due to wave slamming while maintaining power producing capability.

Float for wave energy converter (WEC)

For protecting surface floating wave energy converters (WEC's) against surface turbulence, the WEC's are removed from the water surface. For reducing the force required, the WEC's include a hollow member having an apertured outer wall. In the case where the WEC is to be lifted out of the water, the hollow member is normally submerged and full of water, and, during its lifting, water drains through the wall apertures thereby reducing the weight of the member and reducing the force required to lift it. In the case where the WEC is to be submerged, the hollow member is normally empty of water but fills with water through the wall apertures as the member is pulled beneath the surface. The weight of the water reduces the force required to submerge the member.

Protection of apparatus for capturing wave energy

Apparatus embodying the invention include a damping plate attached to the submerged end of a spar-like element floating in a body of water. The spar like element tends to move up and down in a vertical direction in response to passing waves. The damping plate has a pair of oppositely facing surfaces extending transversely to the vertical direction of the movement of the spar-like element and vertical structures ('lips') mounted on the oppositely facing surfaces for increasing the effective mass of water pushed during movement of the damping plate through the water. Damping plates with lips, as per the invention, may be used in wave energy converters to control the relative motion between the spar-like element and a float to increase the energy produced.

Heave plate with improved characteristics

The stability and power conversion efficiency of a wave energy converter (WEC) which includes a float, a spar and a power taken device (PTO) connected between the spar and the float is increased by connecting a heave plate to the spar in a very secure manner and by carefully limiting the movement between the float and spar to one direction (i.e., up-down motion). Buoyancy chambers may be attached to the WEC to facilitate its transportation and deployment. The WEC may be formed in sections and assembled at, or close to, the point of deployment.

Wave energy converter (WEC) with heave plates

In a wave energy converter (WEC) for capturing energy contained in surface waves on large bodies of water, one or both of the floats used in the WEC has an internal spring system including a weight suspended from a spring mechanism having a selectively variable spring constant for allowing vertical oscillations of the weight in response to bobbing motions of the float The mechanical impedance of the system is a function of the oscillations of the weight, hence the system is tunable to selected values of mechanical impedance for optimal coupling with the prevailing waves.

Tunable wave energy converter

A wave energy converter (WEC) for converting energy contained in surface waves on a body of water to useful energy comprises two floats movable relative to one another in response to passing surface waves. Both floats comprise expandable outer envelopes which have been expanded into full and firm shape. In one process, expansion is obtained by filling the floats with fluids, for example, air and water. The fluids can be pumped into the floats, or the floats can be mechanically expanded in the presence of the fluids for self filling owing to pressure differentials. In one embodiment, a float envelope can comprise of plurality of end to end connected length sections in nested or telescoped relationship. Expansion is obtained by pulling the telescoped sections out from one and other, for example, by pumping fluids into the telescoped sections.

Expandable wave energy conversion system

A wave energy converter (WEC) includes a shell suitable for being placed within a body of water. The shell contains an internal oscillator comprising a 'reaction mass' and a spring mechanism coupled between the reaction mass and the shell. The shell and internal oscillator are constructed such that, when placed in a body of water and in response to waves in the body of water, there is relative motion between the shell and the internal oscillator's mass. A power take-off (PTO) device is coupled between the internal oscillator and the shell to convert their relative motion into electric energy. In systems embodying the invention, the spring mechanism is designed such that its displacement or movement is less than the displacement or movement of the reaction mass. The spring mechanism may be any device which enables the reaction mass to undergo a given replacement while its displacement or movement is less than that of the reaction mass. This property enables the size of the WEC to be more readily controlled (e.g., made smaller).

Wave energy converter utilizing internal reaction mass and spring

The invention relates to active impedance matching systems (AIMS) and methods for increasing the efficiency of a wave energy converter (WEC) having a shaft and a shell intended to be placed in a body of water and to move relative to each other in response to forces applied to the WEC by the body of water. The system includes apparatus for: (a) extracting energy from the WEC and producing output electric energy as a function of the movement of the shell (shaft) relative to the shaft (shell): and (b) for selectively imparting energy to one of the shell and shaft for causing an increase in the displacement and velocity (or acceleration) of one of the shell and shaft relative to the other, whereby the net amount of output electrical energy produced is increased. The apparatus for extracting energy and for selectively supplying energy may be implemented using a single device capable of being operated bi-directionally, in terms of both direction and force, or may be implemented by different devices.

Active impedance matching systems and methods for wave energy converter

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.

Wave energy converter (WEC) device and system

Apparatus for converting energy contained in surface waves on a body of water to useful energy comprises a float from which is suspended a fully or effectively fully submerged inverted cup-shaped member having a closed top end and an open bottom end. Disposed within the top space is a compressible fluid separated by a flexible membrane from a column of water filling the bottom open end of the submerged member. Passing surface waves cause pressure variations at the bottom end of the member causing changes in the water column height and corresponding changes in the buoyancy of the member. The buoyancy changes induce vertical oscillations of the member relative to the float and known means are used for converting the relative movements of the float and submerged member to useful energy. Preferably, the float vertically oscillates in synchronization with the passing waves, and the vertical movements of the float increase the relative movements between the float and the submerged member.

Float dependent wave energy device

A wave energy converter (WEC), for use in a body of water of depth Dw, includes a tubular structure and a piston within the tubular structure where the relative motion between the piston and the tubular structure is used to generate electric power. The length (L) of the tubular structure may be selected to have a predetermined value based on the fact that: (a) the efficiency of the power generated by WEC increases as the length &ldquo;L&rdquo; of the tubular structure increases from a minimal value until L reaches an optimal value; and (b) the efficiency decreases as L is increased beyond the optimal value due to the increased mass of the water that the tubular structure and the piston have to move.

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Saint Paul, MN, United States of America

James S Gerber