OWEC® Research

OWEC® Ocean Wave Energy Converter was invented during architecture school "Ocean Habitat" studio. Designs were developed from ocean research structures along hydroface or in the water column to sea floor. Water-ballasted bodies are variably positioned with electromechanical or chemical assistance. Some have diving and bottom walking ability. Power supply development included ocean wind though abandoned in favor of wave energy. Decision was made, 1978, to forego on or near shore location and primarily utilize offshore and deep ocean wave interaction with floating and neutrally suspended bodies. Other developers and OWECO since participated with FERC Federal Regulatory Energy Commission and MMS Minerals Management Service to help define area jurisdictions and assess environmental impact of "alternative" US activity on outer continental shelves. Recognized, in the winnowing process, is that minimizing or excluding on and near shore technology maintains natural coastal processes, freedom of navigation or other use, and clear visibility. While discrete near shore use will occur, large-scale Ocean Wave Energy Webs may best deploy in exclusive economic zones and  expand to deep-ocean. Ideally, closest edges to land are just slack moored with diminishing investment toward seafloor- where costs are higher.  Inter-array sea lanes permit servicing and module transport. Such remote sites have consistently high energy density and vast areas provide wide planes of hydroface activity. In plan, secondary and tertiary cross-driven undulations approximate curved parallelogram and triangle patterns. Direct conversion of active interference waves is achieved through horizontally melding open structures. Minimum systems of hydroficient units are quick connected to co-form octet octahedron-tetrahedron trusses. Unit neutral buoyancy accommodates module-to-module self-support for quantity distribution. Open web networks of spaced-apart bodies convert multi-directional wave loads where they instantly occur while also enabling wave generation within interior areas. Proximate buoys may absorb reflected or regenerative waves and distribute system stress. The arrangement delimits individual buoy power range for close matching generator properties and permits buoy response to smaller waves. Connector tolerances allow some flexure to help radially diffuse concentrated loads in the octet structural matrix. Scale variation of truss size, module height, and buoy size may correspond to all range of wave conditions.

1980 patent is a tetrahedron module. Independent wave driven buoy shafts move magnets up and down through coils in tubes. Counter-wound coil sets are interspersed between tube bearings. A second coil set is not shown (Development, Slide 2). Tube bearings provide sliding contact with spacers between like pole facing magnets. Lower damper plates provide sea anchor to stabilize buoyancy chamber and coils. Buoy wave reciprocation generates electricity. Output is rectified to direct current and additively combined between module generators and with quick-connect tubes to generators of other modules. Various educational and commercial entities since proposed similar LEG linear electrical generator topologies. But individual rigid moored and seafloor concepts seem impractical. Despite longtime Internet presence and other reference, several parties were apparently unaware of OWECO’s thirty-two year technology precession. While duplication at government-funded university level is educational and confirms OWECO’s path, efforts could be steered toward examining current developments of new work. Though linear generators very directly convert reciprocal motion, each reaches zero stage per half stroke. The design requires excessive magnetic material so that some magnets always correspond to coils during wave passage. An opposite arrangement renders the same result. Another inherent problem is direct support of magnet or coil weight with buoyancy force. Such attributes diminish efficiency. OWECO's four-year experience with linear generators evolved with translation of intermittent reciprocating motion to continuous rotary motion and supporting generators in neutrally buoyant housing.

1987 patent discloses reciprocating rack and counter rotary axle gear within buoyancy chambers.  Clutch converts bi-directional motion to continuous unidirectional motion of flywheel, transmission, and generator. Gear pitch diameter effects rotations per stroke, torque, and flywheel effect. Force bias is toward upstroke buoyancy using relatively large flywheel generators. Separate, smaller flywheel generators operate from downstroke buoy and shaft material weight. While slightly less directly driven, primary advantages are sustained movement, fewer and more commercial parts, and neutrally supported generator weight is independent of buoyancy force. OWECO performed a U.S. Coast Guard contract under the Small Business Innovation Research program. A small full-scale breadboard experiment took input from a variable wave and buoy simulation motor. The power train included linear to rotary converter, adjustable mass flywheel, variable gear ratio transmission, generator configurations, and load. Mechanical simulation of wave properties and electrical output established data power points and scaling factors for descriptive computer models. Drive train resistance confirmed that operational simplicity is essential.

Since 2000, OWECO hosts international engineering interns working on several computational fluid dynamic and structural analyses. Forthcoming engineers will examine electromechanics related to large buoy dynamics. The buoy is first interface between hydroface and OWEC® units. Two general states exist when a wave-following buoy is partially submerged, when it is totally submerged, and whether it is traveling up or down. With respect to electrical generation and other loads, different conditions apply to upward buoyancy and downward gravity forces. An ideal buoy displaces maximum amount of water as quickly as possible while flowing through the water with least resistance. OWECO prior intuitive work with sphere, hemisphere, and modified cylinders confirmed that added mass from turbulence can exert substantial negative pressure. Beyond sphere, two buoys seem promising. Conical, and particularly, bi-conical spheroid shapes show remarkably improved flow efficiency.

The cone shape is adaptable to predominantly long period waves in which most buoy portions extend above hydroface. When near fully submerged, its considerable displacement enhances buoyancy force to compensate slower velocity and drag. Within design parameters, however, an asymmetric relation to reciprocation axis may at times exert large gyration loads on the driveshaft. The fish-like Tetras buoy eliminates twisting stress about the driveshaft due to its axial symmetry. This buoy is most effective near full submergence in active seas. Although buoyancy volume is less than the cone buoy, its reduced weight and efficient form flow enable quick reactions and faster velocity. The net force may be equal or greater than the cone while comprising fewer materials. Buoy strength to weight is further improved using composite thin shell walls reinforced with interior foam lining and balloon framing members.

In addition to hydrodynamics, OWEC® optimization also relates to timely implementation in factory, overland transport, or waterborne vessel to accommodate greater storage quantity per delivery trip. The modular system permits high volume component manufacturing and deployment options. Large buoy and air chamber parts are shaped for close-pack nesting and methodically repetitive quick dis/assembly techniques. Another example is bayonet mount driveshaft racks using slip-fit connections. Module base connectors are made of space-saving nesting tubes that form strong corners when assembled. Lock pins provide two way edge or three way interior connections with other module bases. Mating tolerances allow adjustment of overall truss flexibility and force dispersion. Connectors are supplied with redundant security features and shock absorbers to dampen impact loads from downward shaft and buoy movement. Overtopping waves on buoys induce maximum downward forces but they are relatively low. Though shown as springs, a variety of resilient absorber materials may be implemented including entrapped seawater. 

2008 patent includes above considerations and third direct drive generator design for increasing relative speed and power efficiency with substantially reduced materials. The configuration is symbiosis of our previous designs and improved components that integrate flywheel effect in both reciprocation directions. Heavier components activate from buoyant upstroke, lighter parts counter-rotate from downstroke mass of buoy and driveshaft, and still other parts are stationary. Total energy extraction is optimized by maintaining buoys near full submergence through all stages of passing waves. Also of note, a new gearbox has one protected interior water seal that eliminates prior shaft bellows and associated suction. Located near module apex, buoyancy chamber maintains neutral buoyancy and houses power generation and control equipment. Chamber walls are supported at non-vertical angles for directing some wave laminar flow toward buoys. Upper and lower portions are edge sealed and affixed to a chassis comprising gasketed top and bottom plates. Plates are conjoined by central core and tube elements forming a very strong non-intersecting tetrahedron. Air chamber composite wall strength is augmented with interior partitions separating ballast bladders from electrical generator equipment, buoyancy control pumps, and desiccant. Sensing controls activate pumps to adjust the amount of seawater in bladders thereby maintaining module working depth. Preferably, two-part buoyancy chambers are factory sealed and guaranteed. Current work is improving electrical generator and ballast designs, further integration of commercial components, and manufacture/deployment process.

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