Background:

As fossil fuels deplete day-by-day, need for alternate energy sources has been increased. Hydrokinetic energy is one such renewable source and over the years, numerous hydrokinetic devices have been proposed for extracting energy from waves (e.g., sea or lake surface waves) to produce electrical energy. The use of sea walls, track and rail systems, pump systems, capture basins, piston driven systems, oscillating water columns, flapper systems, linear magnet systems, wave swings, or floatation elements have been proposed, in combination with other elements, to facilitate the extraction of energy from waves. Though tidal energy is seen as a promising energy source of future, till now, none of these devices incorporate real time adjustments to the device depth and response frequency in response to real time changes in wave characteristics to optimize the energy extracted from the waves. Therefore, such devices fail to convert the full energy provided by the waves into electricity.

Summary:

The present invention applies real time adjustments in response to real time changes in wave characteristics, so as to optimize the energy extracted from the waves. The wave energy harnessing device has a surface flotation device with a line attached to a reel positioned on a submerged `-platform, which itself is anchored to the sea floor. The flotation device line is wrapped around the reel. Lift from the floatation device and load from a power take-off system induce reciprocating rotary motion on the reel as waves pass by the flotation device. The lift from the floatation device inputs energy to the power take-off system, causing the reel to rotate in one direction, and the power take-off system acts as a spring to rewind the reel after the wave passes under the floatation device, causing the reel to rotate in the opposite direction. Since more energy is required to lift the floatation device than to rewind the reel, there is a net gain in energy stored in the power take-off system from each wave cycle. The submerged buoyant platform is maintained in a submerged position by anchors in the sea floor that are attached to winches on the platform who control the depth of the platform below the surface. This variable depth capability of the platform enables a wave shoaling feature and an active storm avoidance feature. In calm and moderate seas, the platforms may be raised near the surface to use the buoyant platform to shoal incident waves, to increase the combined wave energy extraction efficiency of the coordinated grouping of hydrokinetic devices. In storms or periods of extremely large waves, the platforms may be lowered near the sea floor where water particle motion is reduced, to reduce the kinematic and dynamic loads on the platforms and anchor lines. The variable depth feature is controlled by winches with continuous response to changing anchor line and/or flotation device line tension. The wave energy harnessing device converts the energy that fluxes through very large volumes of water such as, but not limited to, oceans, lakes, and rivers into electricity or stored energy. The energy flux may come in the form of swells, wind waves, or currents. The wave energy harnessing device uses the torque applied to the reel by the line under tension as the mechanical energy source. The mechanical energy source is the lift force applied by the floatation device. The reel rotates a pump-motor to force hydraulic fluid through a hydraulic line into an accumulator housing. A fraction of the energy stored in the accumulator will be used to rewind the reel after a wave crest has passed under the floatation device, while the remainder is used to drive a generator to produce electrical energy.

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Link to Full Patent:

Wave Energy Harnessing Device