Ocean Power Technologies, Inc.

United States of America As Represented by the Secretary of the Air Force

Charles B Carroll

Meredith Bell

Ching-Yue Lai

George W Taylor

Joseph R Burns

Paul J Smalser

Michael Y Epstein

Eric Cross

An elongated cylinder is fully submerged, in vertical orientation, just below the mean water level of, e.g., and ocean, and of a length, dependent upon surface waves of preselected wavelength, such that the top of the cylinder experiences relatively large pressure variations in response to over passing waves while the bottom of the cylinder experiences an almost steady pressure substantially independent of the over passing waves. The pressure differential over the length of the cylinder is used for causing relative movements between the cylinder and adjoining water, and such relative movements are used for driving a piston of an energy converter. The cylinder can be hollow and in fixed location for causing water movements through the cylinder, or the cylinder can move through the water relative to a fixed transducer. In one version of the movable cylinder, the transducer is fixedly mounted on a fixed in place float disposed within the movable cylinder. In a second version, the transducer is fixedly mounted beneath the movable cylinder on the ocean floor, and the cylinder is coupled to the transducer.

Wave energy converters utilizing pressure differences

Protection against damage caused by excessively high input energies, e.g., from ocean storms, is provided in energy converting systems by, in response to the detection of excessively high input energies, changing the electrical impedance of the electrical load to which power from an electrical generator is being delivered for increasing the generator output current for reducing the power converting efficiency of the generator. This increases the mechanical impedance presented by the generator to the source of input energy for reducing the motion producing effect of the input energy.

Protection arrangement for natural energy power generation systems

A piezoelectric power generator, particularly for use in a flowing fluid stream, comprises an elongated, flexible central layer of a dielectric material having, spaced axially along opposite sides thereof, a plurality of separate piezoelectric elements each formed from a portion of a continuous layer of a piezoelectric layer extending along each opposite side of the central layer sandwiched between a pair of electrodes unique to each piezoelectric element.

Energy harvesting eel

An electrical energy generator relying upon piezoelectricity includes electrical generating elements comprising electroded bodies of an electrostrictive material, e.g., polyurethane, having inherent but weak piezoelectric characteristics. A d.c. bias is applied between the electrodes for field-inducing a larger piezoelectric characteristic whereby, upon applying mechanical energy to the element, in known manner, for alternately straining and destraining the body, electrical charge is generated on the electrodes with a high mechanical energy to electrical energy conversion efficiency.

Field-induced piezoelectricity for electrical power generation

An open ended tube is mounted in fixed, vertical orientation within a body of water with the top and bottom ends of the tube at preselected depths relative to a mean water level when preselected waves with which the invention is designed for use are present. The tube top open end is disposed at a first depth approximately equal to but not less than the maximum preselected wave amplituded so that the top end is always submerged. The tube bottom open end is disposed at a depth where the energy level associated with preselected waves of maximum wavelength is small. In response to pressure variations caused by passing waves, water flows into and out of the tube, and energy capturing means, e.g., a piston or turbine, is disposed within the tube for converting the water flow to useful energy.

Wave energy converter utilizing pressure differences

For capturing energy contained in surface waves on a body of water while protecting the system from damage against conditions on the water surface, a transducer for converting wave energy to useful, e.g., electrical, energy is anchored to the water bed. A float is connected to the transducer by a rigid connector for transmitting variable forces against the float caused by wave induced circulatory water movements against the float. The connector is of such length that the float is always fully submerged (but within the energy zone of the waves) thus displacing a fixed volume of water and providing an essentially constant upward force on the transducer. The constant upward force is modified by the moving water induced variable forces against the float. The float can be a sphere, but the float is preferably of a shape including laterally extending panels providing a ratio of area to volume larger than that provided by a sphere. The transducer can be suspended from the float either closely adjacent to or well above the floor of the water body.

Surface wave energy capture system

A piezoelectric generator comprises one or more inner hubs, an outer, stationary support, and a plurality of strap-like piezoelectric power generating elements mounted between the hubs and the outer support. The hubs are mounted for relative rotation on a first shaft mounted eccentrically on a second shaft having an axis of rotation coincident with central axis of the outer support. Rotation of the eccentric first shaft causes the hubs to follow a circular path around the outer support axis but without rotation of the hub around its own axis. The movements of the hubs cause alternate straining and destraining of the piezoelectric elements for generating electrical energy. For obtaining high energy conversion efficiency, the elements are arranged in groups of three or more substantially identical elements which are identically strained but symmetrically out-of-phase with one another.

Piezoelectric rotary electrical energy generator

Piezoelectric electrical generators comprise cantilevered beams of piezoelectric material, cross sections of the beams preferably being triangular and of increasing area from free end to fixed end. Arrays of spaced apart beams are disposed in overlapping, interdigitated relationships with arrays of cams, and the cam arrays are moved relative to the beam arrays for causing engagement and deflection of the beams by the cams for the generation of electrical energy. One system comprises a raft floating on the surface of an ocean. Cam arrays are suspended from the raft for interaction with vertically extending beam arrays mounted on the ocean floor beneath the raft. Relative vertical movements are caused by passing surface waves. In another system, beam arrays are suspended from an above surface structure, e.g., an oil drilling ocean platform, and the beam arrays extend towards and interact with cam arrays mounted on the upper surface of a floating raft.

Frequency multiplying piezoelectric generators

A known type of piezoelectric power generating system for converting the mechanical energy of waves on a body of water comprises a float and a piezoelectric power generating element suspended, under tension, between the float and a bottom anchor. For preventing excessive vertical stretching of the piezoelectric element in response to the presence of excessively high waves, a protective element is coupled between the float and the bottom anchor for effectively limiting the rise of the float above a preselected height corresponding to the maximum straining desired for the piezoelectric element. The coupling is automatic and occurs only at those instances when the piezoelectric element elongation is approaching its maximum amount, and automatic decoupling occurs immediately upon the float falling to a height where non-excessive straining occurs.

Piezoelectric generator protection

An electrical energy generator comprises a cylindrical stator, a cylindrical liner of a piezoelectric material in concentric contact with the stator, and an armature rotatable about the liner. In one embodiment, as the armature rotates, the armature squeezes successive portions of the liner against the stator for alternately compressing and decompressing the liner portions for causing them to generate electrical energy. In another embodiment, the armature causes alternating stretching and destretching of successive portions of the liner between spaced apart portions of the stator for causing the liner portions to generate electricity.

Piezoelectric electric energy generator

A high intensity heat exchanger that uses a solid copper heat sink having a lurality of integral pins formed on one side thereof, and an electrical insulator comprised of thin film of aluminum nitride (AlN) or diamond-like carbon (C) deposited on the other side. A device to be cooled, such as a computer chip, or an infrared detector cell is secured to the insulating layer by means of a very thin film of solder. A cooling liquid is circulated to the pins through conduits which also support the heat sink. The pins have a rectangular cross section and the spacing of the pins, and the fluid velocity are optimized to provide turbulent flow around the pins. The apparatus is provided with a space under the pins for a removable orifice plate, thereby enabling the optimization of the size, shape and number of orifices for a particular application.

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Mercer County, NJ, United States of America

Charles B Carroll