Method of shoreline wave energy capture

Abstract

Abstract The wave energy along any length of shoreline is captured by accessing the interior of a cliff from its face, tunneling along the edge of the cliff, and excising oscillating water column clambers from the tunnel. Energy capture means such as turbines can be positioned in the airflow from these chambers and removed when threatened by storm waves. Abstract 2021202211 13 Apr 2021

Description

Spanish patent No. 434915 discloses capture of the energy of ocean waves at the shoreline from natural blowholes, and US patent No. 6968683 discloses the use of man-made ones for it. The present invention is a practical method of achieving their objectives. It is illustrated in the accompanying drawings, which are section views of a shoreline cliff. Fig 1 of these shows the operation of the invention where the cliffs are not so high as to make it uneconomic to drill from the top to the water level. Fig. 2 shows it in a situation where the cliffs are higher than this, and Fig. 3 shows how the energy could be extracted from a significant length of wave front. In Fig. I, Tis the cliff, and 2, 2, are the exits in its face of a pair of holes drilled from its top. These exit holes are at least an average wave height below low water spring tide level, so that they are always covered by water. 3, 3 indicate the exits of another pair of holes also drilled from the cliff top, to emerge from the cliff face below holes 2, 2. Each hole in a pair diverges laterally from the other, and the planes of each pair of holes are designed to intersect. 4 is diamond wire cutting equipment on the top of the cliff. In operation, traces are threaded from the cliff top through the pair of holes 2, 2. When these emerge into the water, their ends can be retrieved by having attached to them either an inflatable float which can be picked up from a boat, or a balloon which can lift the end of the trace into the air for retrieval by a drone. Both traces can then be connected to enable a continuous loop of diamond wire to pass down through one hole of a pair, and then across on the cliff face to the second hole, so that mechanism 4 can cut a slot upwards into the rock of the cliff for a prescribed distance from its face. The same procedure is followed with holes 3, 3, until cutting upwards enables their slot to meet the slot already cut by using holes 2, 2. When both slots have met, a volume of rock has been excised remotely from the cliff face and will fall out into the water. This is facilitated by the divergence of the slots which define its shape. The space left in the cliff by the removed rock then forms chamber 5 within which an oscillating water column (OWC) moves air through a means which can capture its energy such as a turbine. Any such means must be capable of being moved to safety from damage from exceptional waves. For the lowest cliffs, it may be possible to use holes 2, 2 and 3, 3, possibly with one or more of their diameters enlarged, as exhaust shafts for the air moved by the waves in chamber 5. When the height of the cliff makes this approach uneconomic, the energy capture means needs to be positioned as close as possible to the top of OWC chamber 5, as shown in Fig. 2. This can be done with lift car 6, under the control of crane or gantry 7, on the top of cliff 1. Wheels 8, 8 on car 6 enable it to move vertically over the face of cliff 1 while in contact with it. 9 indicates an air exhaust shaft at a point on the cliff face that corresponds to the upper part of OWC chamber 5. Workers and their drilling gear can be moved to an appropriate access point on the cliff face by car 6, to enable them to bore exhaust shaft 9 to the top of chamber S. A turbine or other energy device can then be lowered in car 6 and inserted into shaft 9 to capture the energy from air movement through it. When exceptional force from storm waves threatens to damage the energy capture equipment, it can be removed to safety in car 6. The height of cliffs may also make it more economic not to operate from the cliff top to make each individual OWC chamber, but instead to make a tunnel 12 inside the cliff face at the waterline for whatever length of wave front it is proposed to exploit, as shown in Fig. 3. This tunnel need only be of sufficient diameter to enable means for making OWC chambers to be operated inside it. An access point 13 for this tunnel on the cliff face can be reached by lift car 6, and is fitted with sealable door 14 to protect gear in the tunnel from damage by water from exceptional waves during the period of tunnel construction. OWC chambers 15, 15 can then be excised from the cliff face from tunnel 12. This can be done by diamond wire excising as already explained, or by other means such as drilling and blasting or water jet cutting. Bulkhead 16 divides tunnel 12 into two or more discrete sections. If only two sections are needed, it is movable and sealable, in order to protect workers and gear in tunnel 12 from exceptional waves which could reach them once they had excised the first OWC chamber. Also, a multiplicity of bulkheads 16 may be permanent constructions in tunnel 12 to increase the aerodynamic efficiency of a multiplicity of OWC chambers by tuning them better to wave direction and periodicity. Air exhaust shafts 17, 17 can be excavated from the tunnel to the cliff face, or inwards from the face by workers and gear transported by lift car 6. Energy capture means 18, 18 can then be installed in tunnel 12 or in shafts 17.

Claims

EDITORIAL NOT 2021202211 "here are 2 pages of claims only. Claims: I. The method of making a water wave energy capture means comprising, in combination — drilling at least two pairs of holes in a cliff which emerge from its face in a pattern which enables an oscillating water column (OWC) chamber to be excised from the cliff face by cutting with diamond wire; passing traces through these holes which have means attached to them for retrieving their lower ends for attachment to a loop of cutting wire; excising an OWC chamber from the face of the cliff with this wire; and attaching means for extracting the energy of the waves in the OWC chamber.

2. The method as in Claim 1, in which the planes of pairs of holes intersect.

3. The method as in Claim 1, additionally provided with means for accessing the interior of a cliff from its face for construction, including an exhaust shaft from the OWC chamber through the cliff face.

4. The method as in Claim 3, wherein the accessing means comprises a lift car under the control of a gantry on the cliff top.

5. The method as in Claim 4, wherein the lift car is equipped with wheels for movement over the cliff face.

6. The method of making a water wave energy capture means comprising, in combination: Excavating a tunnel along the line of the cliff above the waterline; drilling multiple holes at intervals from the tunnel to the cliff face in a pattern which enables an oscillating water column (OWC) chamber to be excised from the cliff face by cutting with diamond wire; passing traces through these holes which have means attached to them for retrieving their lower ends for attachment to a cutting wire loop excising the OWC chamber from the face of the cliff with this wire; excavating air exhaust shafts from the tunnel to the cliff face; constructing one or more bulkheads in the tunnel; and installing means for capturing the energy from wave movements in the chamber. 7 The method as in claim 6, to which is added means for accessing the interior of a cliff from its face for construction purposes.

8. The method as in Claim 7, wherein the accessing means comprises a lift car under the control of a gantry on the cliff top.

9. The method as in Claim 8, wherein the lift car is equipped with wheels for movement over the cliff face.

10. The method as in Claim 6, wherein the bulkhead is movable and sealable.

11. The method of making a water wave energy capture means as in any previous claim, in which the excavation means is drilling and blasting.

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