DE3812828A1 - Apparatus for utilising the kinetic energy of sea waves - Google Patents

Abstract

The invention relates to an apparatus for utilising sea waves with the aid of a floating body, a connection element to the sea bed and an energy converter. Apparatuses which exploit in particular the up-and-down motion of the waves are known. Both the high building costs for inert base systems and the poor efficiency are disadvantageous. The object of the invention is to find a simple construction having a high efficiency, which can adapt itself reliably to changing sea conditions. This object is achieved in that the floating body is constructed as a converting element which preferably converts the horizontal components of the wave forces into horizontal movements which are transmitted to a hydraulic pump which is inserted in the connection element and is connected on the high-pressure side, via an outlet valve, to a reservoir. <IMAGE>

Description

The invention relates to a device according to the preamble of claim 1.

Sea waves arise under the influence of the wind, which is a part transfers its energy to the water. Save the waves a significant dynamic and potential energy. Something is missing therefore not trying to harness the energy of the waves in usable To convert forms of energy.

DE 29 34 004 is a sea wave power generation plant become known, the large, acting as an inert mass has floating wall. In front of this wall are vibrating elements arranged, which move back and forth in the waves. The Swinging elements are adjustable via rigid and hydraulically Links arranged in front of the wall that their Movements are transferred to double-acting hydraulic pumps can.

This system requires a very high level of design effort, because very large masses must be installed in order to work with a ver equally small vibrating element to gain energy. Night egg Lig is also that only a part of the deep water fen reaching waves is detected. The overall efficiency is bad because the damper wall gives way and vibrates. In addition ground anchors and traction ropes must be so strong that they withstand the forces exerted on the supporting structure.

DE 28 37 869 describes a device for energy withdrawal from ocean waves, which also requires a great deal of effort different. The basis is a large raft, which acts as a "resting pole" is anchored near the coast and in which different energy extraction systems can be integrated.

In one embodiment, chambers are formed in which by the incoming waves of air is compressed with the air turbine to be operated. The efficiency is very bad because by far the largest part of the wave energy in frictional heat is converted.

In another embodiment, the up and down movement delivery of articulated floating bodies by means of piston pumps  Hydraulic energy implemented. Here too, the efficiency is despite of the large construction costs relatively low because of the device is not stationary and only captures part of the wave energy.

DE 27 40 722 discloses a device that has a has floats below the waterline. He is Movable horizontally on the sea floor using large leaf springs anchored. The vibrations of the body act on a built-in one Generator so that the relative movement to generate electricity can serve. However, the efficiency is extremely high bad because the generator has limited inertia sen and the relative speed changes constantly.

The patent DE 30 39 030 shows a device for using a Part of the energy of surf waves. The main ingredient is a Fixed wave catch, in which the waves hit so that in a pressure potential can be built up inside. Furthermore can be applied to a movable wing that a Hydrau lik pump operated. The high technical level is also disadvantageous here Effort due to the fixed installation in the coastline and the resulting difficulty of a repair. Very un the impossibility of adapting to the tide is also favorable Since only water with low pressure is stored here the efficiency is bad.

DE 30 44 198 proposes a large area on the water floating membrane facing a second membrane moved in the calmer deep water. Through the relative movements an energy conversion device is actuated, which consists of piston Cylinder units can exist.

However, this device is unable to control the tides and to consider very high waves. In addition, we are Degree of inconvenience because an elastic yielding membrane only very limited traction can be transmitted from the vertical Wave components are triggered.

All in all, no device has been proposed so far been to a significant use of wave energy would have led.

The invention is therefore based on the object of a device to create energy that is as simple as possible construction, high efficiency and large loading drive safety even in very changing sea conditions having.

This object is achieved with the in the characterizing part of patent claim 1 specified means solved.

Embodiments of the invention are explained with reference to FIGS. 1-10 of the drawing.

Fig. 1 shows a device according to the invention from the side,

Fig. 2 shows this apparatus from above,

FIGS. 3 and 4, other cross-sectional shapes of the wall element,

Fig. 5, a flexible wall member with attached buoyancy body,

Fig. 6, 7, 8 and 9 different wall shapes with direct Ver anchoring on the seabed,

Fig. 10 shows an example of a hydraulic train only stressed likrau pump.

In Fig. 1, 1 denotes a wall element which has so much buoyancy in itself that it just just protrudes above the water line 2 . The wall element 1 is held by connecting members 3 of the same length, which lead via a node 4 to a main connecting member 5 . At its left end, the main link 5 is connected to a pile anchor 6 , which is rammed obliquely into the sea floor 7 . In the main link 5 , a hydraulic pump 8 is inserted, the pressure chamber of which is on the piston rod side. In the vicinity of the piston rod passage, at least one outlet valve 9 is provided, via which the pressure medium is fed to a high-pressure line 10 . If hydraulic oil is used as the pressure medium, an inlet valve 11 is to be provided in addition to the outlet valve, which leads via a low pressure line 12 to a low pressure accumulator, not shown.

The entire device is anchored in the shallow water area off the coastline. The direction of the wave is indicated by the arrow 13 . The main link 5 is held so long that its angle to the horizontal is relatively small, that is, for example, at 15 °. The length must be sufficient to take account of the different tides from place to place. At low tide, the wall element 1 should remain well buoyant, at high tide its distance from the sea floor 7 is correspondingly larger, the direction of pull steeper. In the low water position shown, the wall element 1 is inclined approximately 15 ° with respect to the vertical. It can be assumed that a slight swell, which is always present, keeps the connecting element taut, so that the hydraulic pump 8 does not sink to the sea floor 7 . If necessary, it could be provided with additional buoyancy elements, just like the connecting elements.

The device described so far works as follows: Each wave running towards the coast causes the water masses it moves to strike the wall element 1 , thus giving it impulses in the direction of the wave. The rolling shaft tries to take the wall element with it, with a greater or lesser tensile force being transmitted via the connecting members 3 , 5 to the hydraulic pump 8 : the pump piston conveys the pressure medium via the outlet valve 9 into the high-pressure line 10 as soon as the pump pressure is greater than that in the high pressure line 10 pending storage pressure.

The outlet valve closes when the tensile force decreases or when the pump piston reaches the upper end position. If the pump pressure now drops below the pressure in line 12 , the low-pressure medium flows into the cylinder in order to bring the piston back into the lower end position. Depending on the wave phase, the wall element 1 sets the return process against a more or less small resistance. At the end of the return process, the pump is again filled with the pressure medium and thus prepared for the next working stroke.

The gross energy gain per stroke corresponds to the product the delivery volume and the pressure difference between high and never  derdruckleitung. In order to keep the friction losses low, you should the valves can be integrated directly into the pump and the lines to keep the memories as short as possible.

The energy potential of the printing medium can be exhausted known rules. It is preferable to become a hydraulic motor and operate electric generator, the size of the Hydro memory depends on whether the generator works in island operation or feeds into the existing network.

FIG. 2 shows a partial view of the device according to FIG. 1 from above. The optimal length L of the wall element 1 and its depth T result from several influencing factors, in particular the construction material used and its bending stiffness. The length L should preferably be 2 to 3 times the depth T be.

Fig. 3 shows a wall element 14 which is curved in its surface around the longitudinal axis, wherein the shape can resemble a circular section, a parabola or a hyperbola. To achieve greater stability and to better utilize the water forces, the element can also be curved around two axes.

In Fig. 4 two wall sections 15 a , 15 b form a right to obtuse angle with each other.

Both wall shapes according to Fig. 3 and 4 may for example consist of a stratified material whose average specific gravity is smaller than 1, so that they have sufficient buoyancy. Walls that are concave when viewed in the direction of the waves, that is to say their curvature faces the coast, behave in a particularly stable position with at least 4 connecting links at the end points in the sea. Their efficiency is also higher than with a straight wall. In particular, curved wall elements in the room are cheaper to manufacture than flat panels with the same stability.

In Fig. 5 a device is shown in which the wall element 16 is bent into a U-shape and consists of resilient material. An additional buoyancy body 17 is provided at the upper edge. This device can automatically adapt to changing water levels. The solid line applies when the tide is low, and the broken line when the tide is high. This wall shape is particularly useful when the tidal range is not too great. The wall can consist of an elastic curved plate or of plate parts with joints. The bulge is strongest when the water level is low, and approaches a semicircle when the water is high.

In all embodiments according to FIGS. 1-5, the entire apparatus is suspended from a pile anchor, so that it can follow a slight change in the shaft direction. In general, however, all wave fronts with ground contact align so that they run perpendicular to the coastline.

The connecting links 3 , 5 , which are only subjected to tension, can consist of rods, pipes, ropes or chains. Tubes made of light metal alloys are very useful, which are watertight at the nodes and thus generate sufficient buoyancy.

In Fig. 6 is a construction is shown in which the wall element 18 reaches down to the bottom 7 and is held there with pile anchors 19th A projecting beyond the water line 2 wall section 18 a helps to stabilize the wall in the water and at the same time to increase the efficiency.

When the wave hits, a water build-up occurs. The different water levels 2 and 2 'on both sides of the wall are an image of the pressure difference that can be used for the working stroke. With this design, however, different water levels are used as disruptive factors.

Instead of a flat wall element according to FIG. 6, a curved wall element 20 can be selected according to FIG. 7, the overlying wall section 20 a of which forms an additional wave obstacle.

In Fig. 8 a U-shaped wall member 21 is shown, which is supported by a pile anchor 19 downward and having a top to sätzlichen buoyancy body 22. This buoyant body causes the upper vertical wall section 21 a to rise and fall with the water level.

The required height for this wall section is determined according to the maximum wave heights to be expected and the desired Pressure difference.

Fig. 9 shows a wall element 23 , which consists of two curved surfaces. The element is in turn anchored at the bottom on the sea floor, while connecting members 3 attach in the middle and above, which lead via the node 4 and the main connecting member 5 to the hydraulic pump (not shown). This design is particularly suitable for high water levels and waves. The extension of the system upwards can be mechanically limited by further tension members so that the arcs are not flatter than half circles. In the event of unusual flooding, the float 22 and the wall part 23 a are then flooded.

The embodiments according to FIGS. 6 to 9 stood at high water and stormy seas advantageous because the hardest waves hit the submerged and directly anchored to the ground sighting. Nevertheless, there is a strong horizontal water movement in the area to the sea floor, which can be used very well by the curved wall elements for energy generation.

In order to increase the resistance of the system to storm damage, one can provide further connecting members between the anchors 19 for the lower wall edge and the pile anchor 6 for the main connecting member.

5, 7, 8 and 9 proved to be surprisingly well suited as material for the shape-changing wall elements according to FIGS. 5, 7, 8 and 9. Sheets made of polyethylene, polyvinyl chloride and polypropylene with a thickness of 2-5 mm are resistant to sea water and very resistant to shock loads. These plastics are also particularly inexpensive as semi-finished products.

In order to create an economically working wave power plant, you can add as many of the devices described next to arrange each other. The devices interfere with each other not and can generate energy independently. To an arrangement in a row would also be in order  several rows, conceivable. As a result, the total costs are low kept that the individual supply and discharge lines for pressure oil in Storage containers are detected, from which a high and Low pressure line leads to the mainland. These lines can because of the constancy of the volume flows a relatively small cross have cut. There are more highs in the headquarters pressure accumulator, low pressure accumulator, hydraulic motors and generators, whose electrical energy can be fed into a network. The high pressure and low pressure lines deliver almost without rule even volume flow because the pressure and Compensate volume peaks of the individual devices largely.

The systems are particularly insensitive to interference because all electrical parts of the system are protected on land can be brought.

In Fig. 10, a hydraulic pump is shown, which works with sea water as a pressure medium and, as a result, does not require a return line. A strong coil spring, which is housed in the pressure cylinder, is used to retrieve the wall element.

The cylinder jacket of the hydraulic pump is labeled 24 , the piston 25 , the piston rod 26 . At the upper end of the cylinder an outlet valve 28 is provided which opens into the high pressure line 29 . Via the inlet valve 30 , the lake water is sucked directly. A sand filter can be installed upstream of this valve. Between the piston and the bushing flange, a strong coil spring 31 is mounted, which is pressed together during the working stroke and then returns the piston and thus the wall element to the starting position.

The use of water as a pressure medium has the great advantage environmental sustainability. Pollution of coastal waters through leakage or line break is excluded, which causes the Such an installation should be accepted.

The invention makes use of the knowledge that in Close to the coast, i.e. in shallow water, the circular orbital dome movements of the water wave to flat ellipses to horizontal Vibrations on the seabed are deformed. For the most part capturing the wave energy, it is sufficient, as described  to use horizontal force components.

In contrast to proposed facilities, here are the Her cost of ownership is particularly low because of the pump and the power transmitting links can only be subjected to tension. In the Dimensioning the hydraulic pumps plays the kink resistance not matter. Also the corrosion of pumps that is constantly from Sea water are covered, less than would be expected.

It is particularly easy to anchor the anchor piles in a relatively flat area Ramming water into the coastal floor. All plant parts are because their buoyancy was easy to assemble and was largely maintenance-free.

The wall elements are set up parallel to the coast and ver stay in this position too.

To achieve high efficiency, the pumps and Wall elements are designed so that they optimally on the front prevailing wave spectrum are set. To take care of each Working can adapt to the prevailing swell pressure can be adjusted. This means that when you are small Waves with the hydraulic motor (with reduced power) operates at a much lower pressure than very strong ones Waves.

With an average wave height of 1.5 m with a Power of 4-7 kW per meter wall width to be expected, which one Efficiency equivalent to 30-50%.

A power generation device in the technically interesting Scale could, for example, consist of 10 wall elements 4 m long and 3 m high. With an average wave height of 1.5 m and 40% efficiency, the power could be 220 kW wear.

If you look at the downstream hydraulic circuit of 68% efficiency and the generator with 95% useful energy the electrical power output is to be expected 142 kW.

Under these conditions you get 70% annual utilization 870,000 kWh per year at a very competitive price.  

The generation of electrical energy may be in the foreground, but other forms of energy conversion are also interesting. The system described could, for example, supply 1500 m ^{3 of} pressurized water of 75 bar per day to a seawater desalination plant.

Wave power plants of the type described are renewable Energy source that not only does not pollute the environment, but because of the damping of the waves on the coast fortifications can be particularly useful.

Claims (9)

1. Apparatus for harnessing the kinetic energy of ocean waves with the aid of a floating body, a connecting element to the solid surface and a transducer detecting the movement of the floating body, characterized in that the floating body is designed as a wall element ( 1 ), which preferably the horizontal components of the wave forces in horizontal movements implements, which are transmitted to a hydraulic pump ( 8 ) which is inserted into the connecting member ( 3 , 4 , 5 ) and which is connected on the high-pressure side to an accumulator via an outlet valve ( 9 ). 2. Device according to claim 1, characterized in that the wall element ( 14 ) in the shaft running direction ( 13 ) is concave. 3. Apparatus according to claim 1, characterized in that the wall element ( 16 ) curved about a horizontal axis carries on its upper edge buoyant body ( 17 ) and consists of a resilient material so that it changes its radius of curvature in accordance with the wave movement. 4. The device according to claim 3, characterized in that a wall part ( 21 a ) on the buoyancy body ( 22 ) and thus protrudes beyond the water line ( 2 ) and acts as a baffle when the shaft hits. 5. Apparatus according to claims 1-3, characterized in that the wall element ( 16 ) is held at its upper and lower edge with connecting members ( 3 ) which converge at a node ( 4 ), and that the hydraulic pump ( 8 ) in arranged between the node ( 4 ) and pile anchor ( 6 ) main connector ( 5 ). 6. The device according to claims 1-3, characterized in that the lower edge of the wall element ( 18 , 20 , 21 ) is fastened several times with the help of pile anchors ( 19 ) on the sea floor, while the upper edge is held by connecting links ( 3 , 5 ) which transmit tensile forces to a pile anchor ( 6 ) via a node ( 4 ) and the hydraulic pump ( 8 ). 7. The device according to claim 5, characterized in that the inclination of the main link ( 5 ) is less than 15 °. 8. The device according to claim 3, characterized in that the wall elements consist of plastic plates. 9. The device according to claim 1, characterized in that several wall elements and hydraulic pumps alongside and / or are anchored in series and that the hydraulic pumps via high pressure and low pressure manifolds with Stores connected to the mainland.