NO344108B1 - Device and method for recovering energy in water streams - Google Patents

Description

Field of the invention

The present invention relates to a device and method for converting kinetic energy in water flows. The device and method will utilize natural resources by transferring the energy contained in streams of water to other energy. The device is preferably used for extracting energy in horizontal water flows.

The background of the invention.

In ocean currents there is a stable source of energy in the form of kinetic energy from the moving mass. For example, the Gulf Stream has a speed of as much as 2.5 m/s in some places, and there are very large masses of water in motion. Furthermore, the flow rate of water currents will increase when large masses of water (for example from seas or rivers) are pushed through straits or constrictions. The device can also use the flow movement in tidal currents, i.e. the water currents caused by the tide, to convert energy.

The device and method according to the invention are thus based on converting the kinetic energy in flowing water into electrical energy, or another form of energy. The density of water is almost 1000 times higher than air, and this makes it possible to efficiently convert energy even at low flow rates. It is expected that even flow speeds of, for example, 0.1 m/s will be sufficient to be able to convert the movement energy into other forms of energy.

There are currently several known solutions for converting energy from flow in bodies of water. Most solutions are based on the tide flowing from a basin to a lower basin via a turbine. Furthermore, tidal mills are known, but this requires large water flows. Tidal turbines can be compared to underwater windmills. However, they have a relatively low degree of recovery.

Norwegian patent NO321762 describes a solution where submerged sails are moved with the tide between two magazines. The tide pushes the sails in one direction from one magazine to the other, reaching the opposite way when the tide flows in the opposite direction.

Norwegian patent NO326942 describes a solution where a wing or hydrofoil is movably stored in a supporting structure. The hydrofoil is equipped with a turning device which turns the hydrofoil when it has reached a turning point, and this changes the angle of attack of the hydrofoil in relation to the direction of flow of the water current so that the direction of movement of the hydrofoil reverses.

US4539484 describes a device which includes a frame which is fixed in relation to varying levels of water, and includes a float which moves in relation to water level.

FR3003608 describes a horizontally arranged tidal turbine comprising a blade and a supporting structure. The blade has a design that causes the tidal currents to push it in one direction.

It is an aim of the present invention to provide a device and method for efficient and effective utilization of the energy that flows in water in the form of kinetic energy in water currents. The aim is to achieve a better and more environmentally friendly extraction of energy than current solutions. It is also an object of the invention that the plant should have a simple and robust structure.

The solution that the present invention produces has fundamental similarities with oscillating hydrofoils (for example as described in NO326942) and tidal kites. With the present invention, a cloth or plate is arranged in water so that the water flow comes towards the cloth/plate. For example, the plate is arranged horizontally in the water, parallel to the water surface. The water flow will then go under and over the plate. The plate is equipped with some elements that either protrude from the plate. These can be changed so that they either project upwards from the plate, or project downwards from the plate. The plate thus becomes asymmetrical so that the water flow will press differently on the upper and lower sides of the plate, and this will cause a movement of the plate either downwards in the water or upwards in the water. Furthermore, the elements will generate turbulence which also contributes to movement of the plate. The movement energy of the plate, as it is caused by the water currents to move either up or down in the water, is preferably converted into electrical energy.

Summary of the invention

The present invention thus relates in a first aspect to a device for converting the kinetic energy in a water flow, characterized in that the device comprises a movable stored sheet-like structure for reciprocating movement between a first and a second turning point, where said sheet-like structure is in connection with an energy-generating device for converting the structure's reciprocating movement into another form of energy, where one or more resistance elements are movably stored to the sheet-like structure that form an angle of attack against the direction of the water flow, where the resistance elements can be changed to be protruding on one or the other side of the structure.

In one embodiment, one or more sheet-like structures are movably stored in a framework.

In one embodiment, each sheet-like structure comprises one or more resistance elements.

In one embodiment, the framework is positioned in a laminar water flow, preferably by means of attachment to buoyancy aids (buoys) on the water surface.

In one embodiment, the sheet-like structure is a plate, canvas or tarpaulin.

In one embodiment, said resistance element is a cylinder which is movably arranged in an opening in the structure arranged so that the position of the cylinder in relation to the structure can be moved from a position on the underside of the structure to a position on the top of the structure.

In one embodiment, the cylinder comprises barbs in the upper and lower part arranged so that the cylinder will stop when the barbs form an engagement with the structure.

In one embodiment, the cylinder includes means for moving the cylinder up and down in the water column.

In one embodiment, said means are established to move the cylinder downwards in the water column, as the cylinder has a density that is greater than the surrounding water.

In one embodiment, said means for moving the cylinder upwards in the water column are buoyancy means which are arranged adjacent to the cylinder, preferably on the inside of the cylinder, where movement of the cylinder upwards is established by supplying the buoyancy means with gas or air sufficient for the buoyancy to exceed the cylinder's gravity.

In one embodiment, said sheet-like structure comprises a number of openings/perforations.

In another aspect, the present concerns a method for converting kinetic energy in a water flow into another form of energy, characterized in that a device as stated above is arranged in a water flow, preferably a laminar water flow, where the device in a first state is arranged with the resistance elements projecting upwards and where the water flow will thus impose via the resistance elements a downward movement of the sheet-like structure, and as the structure has moved to a turning point, the resistance elements are forced to change position to a second state where the resistance elements project downwards from the structure so that the sheet-like structure will move upwards in the water column, and where the kinetic energy from the reciprocating movement of the structure is converted into another form of energy via energy conversion agents.

In one embodiment, a change of position of the resistance elements in relation to the structure is carried out as the structure approaches a predetermined turning point.

In one embodiment, changing the position of the resistance elements in relation to the structure is performed automatically.

In one embodiment, the device comprises one or more sheet-like structures, and that each of the sheet-like structures comprises one or more resistance elements.

In one embodiment, the sheet-like structure is a plate, canvas or tarpaulin.

In one embodiment, said resistance element is in the form of a cylinder (14).

Preferred embodiments of the invention will be described in more detail below with reference to the accompanying figures, where:

Figure 1 schematically shows the principle of the present invention where movement energy from a water flow meets resistance elements on the upper side of the plate and drives the plate downwards into the water.

Figure 2 schematically shows a resistance element in the form of a cylinder and how this can be moved to be arranged above (fig.2a) or below (2b) the structure.

Description of preferred embodiments of the invention.

Figure 1 schematically illustrates the principle underlying the invention. A device 10 is positioned in a water reservoir where water is in flowing motion. The water flow is indicated by arrows A in the figure. In this case, the direction of the water flow is parallel to the water table (50).

A sheet-like structure (12) is positioned in the water in the same plane, and parallel below the water surface. This structure (12) has a plate-like design, i.e. it is relatively thin in one dimension, and relatively large (elongated) in the other two dimensions. The structure (12) can be, for example, a plate, cloth or tarpaulin.

The support for the sheet-like structure (12) is one or more resistance elements (14). In the figure, two such resistance elements (14) are shown and they extend upwards from the structure (12). In the situational picture shown in figure 1, all the resistance elements (14) are thus on the upper side of the structure (12), i.e. the structure (12) has an asymmetrical design which means that as the water currents flow above and below the structure (12) the currents will meet greater resistance on the upper side of the structure (12) than under the structure (12), and the structure (12) will thus be forced to migrate downwards in the water mass, as indicated by arrow B in the figure.

The resistance elements (14) can in principle have any design, the essential thing being that they protrude above the plane of the structure (12), i.e. either upwards (as in Figure 1) or downwards. In Figure 1, the resistance elements (14) are open cylinders, which can travel vertically (when the structure (12) is positioned horizontally) between openings in the structure to a position respectively so that they project upwards from the structure (12) and to a position where they project downwards from the structure (12). This design of resistance elements is shown in more detail in figure 2. An alternative solution is that the resistance elements (14) are in the form of flaps which are hinged in the structure (10) so that they can be changed so that the flap either projects upwards from the structure, or projects downwards from the structure (12).

The resistance elements (14) are equipped with a device that actively controls a movement of the element (14) in relation to the plane of the structure (12). For example, the resistance elements can be driven up and down using hydraulics or electricity. A currently preferred solution is to use open cylinders as resistance elements (14) and use the gravity of the resistance elements (14) to drive the resistance elements (14) downwards, and to use buoyancy to drive the resistance elements (14) upwards. This solution is explained in more detail below.

The sheet-like structure (12) is movably stored in a truss or framework (40). For example, this can be in the form of vertical bars in each of the structure's (12) corner sections. The framework is positioned in the water, for example by the framework in bottom parts being attached to the bottom formation, and the upper part of the framework being attached to buoyancy elements such as buoys, so that the position of the device (10) in the water can be adjusted. The structures (12) can thus move vertically downwards and upwards in the water column, and this movement is transferred to an energy conversion unit (60).

One or more such plates or structures (12) may be arranged in a framework (40). Preferably, the position of the device (10) and the vertical extent of the framework (40) is adapted to the water flow at the location in question. If several structures are used in the same framework (40), these can be mutually connected to each other so that they move up and down with the same mutual distance.

In some embodiments, it has proven appropriate to perforate the plate (12). How many and how big openings there should be in each plate (12) will be determined by testing. The openings can have a function in equalizing the pressure when the plate (12) moves up or down in the water.

Furthermore, one or more resistance elements (14) can be arranged for each structure (12). In Figure 1, 2 resistance elements are shown, but often the structures (12) will be quite large, and it is then appropriate to have many resistance elements.

Positioning of the various resistance elements (14) on the structure (12), and what shape and dimension these should have can be optimized and adapted to the conditions in which the device (10) is to be installed.

Figure 2 schematically shows an embodiment of a resistance element (12) and how this can be moved from a position above the structure (12), as shown in Figure 2a, to a position below the structure (12) as shown in Figure 2b.

The resistance element (14) is here in the form of open cylinders (14). The cylinders (14) are positioned in openings in the structure (10), and the cylinders are equipped with a number of barbs (14a) in the bottom part and top part so that the movement of the cylinders (14) in relation to the structure (12) will stop when they are in engagement with the structure (12).

For example, three such barbs in the bottom or top section will ensure correct stopping and positioning of the cylinders.

Figure 2 also shows an embodiment where gravity and buoyancy are used to change the position of the cylinders (14) in relation to the structure (12). The cylinders have a greater density than the water they are positioned in, and the weight will therefore cause them to naturally sink in the water column. This will cause the cylinders to move from a position above the structure (12) to a position below the structure (12). In order to move the cylinders upwards, they are equipped with a buoyancy element (20) which is connected to means for supplying or draining a buoyancy agent such as gas or air. The buoyancy means (20) can be attached to the inside of the cylinder (14), but the buoyancy means can also be freely movable in the cylinder, and in such a case the cylinder (14) is equipped with grates (14b) in the top and bottom parts which prevent the buoyancy element from can move out of the cylinder (14).

In one embodiment, it is possible to add or remove gas or air to or from the buoyancy means (20). This will change the buoyancy. When the buoyancy is greater than gravity, the cylinders (14) will move from a lower position as shown in figure 2b to an upper position as shown in figure 2a.

If the buoyancy element contains a given amount of gas or air, the buoyancy effect will change based on the ambient pressure applied at different water depths. This means that the buoyancy increases as the plate moves upwards in the water, and at a given depth the buoyancy will be greater than gravity and the resistance elements will move to a position above the plate, which will cause the direction of movement of the plate to reverse and face downwards . Different buoyancy is schematically shown as the size of the buoyancy elements (20), and Figure 2a with large buoyancy then shows the buoyancy means as it has moved from a lower position to the upper position. Figure 2b schematically shows the buoyancy element (20) as the gravity of the buoyancy element is greater than the buoyancy, i.e. as the cylinder moves downwards in relation to the structure (12).

In a preferred embodiment, there will be a locking mechanism (for example magnetic lock) between the resistance elements and the plate so that the resistance elements can be locked in a given position. The lock is deactivated when the resistance elements are to move to the other side of the plate.

The cylinders (14) are not attached to the structure (12) and can move freely up and down in relation to the structure (12) until they are stopped by the barbs (14). The number of barbs can be from three barbs to a large number, and they can also be replaced by a collar around the cylinder at its bottom and top.

The cylinders (14) can be equipped with means (not shown in detail in the figure) to lock the cylinder (14) in a given position in relation to the structure (12). Such locking means can, for example, be in the form of a magnetic lock, and that the magnetic lock is activated to lock the cylinder in a given position, for example in a position close to the turning point. When the structures (12) have moved to the desired position, the magnetic lock is deactivated and the structures will, depending on gravity and buoyancy, move to a new position.

As stated above, the resistance elements (14) can be of any shape as long as they extend respectively above and below the plate (12) during movement. It is preferred that they have a cylindrical shape, and then the circumference of the cylinder can vary, and also the height of the cylinder can vary. Also the number and density of such cylinders on a plate can vary, and this can be optimized by the person skilled in the art with testing. The flow towards the resistance elements 14 will establish different pressures on the two sides of the plate, and turbulence will also occur. The turbulence that is established will also establish a pressure against the plate in the desired direction. The number of openings and the size of the openings in the plate (12) are also optimized based on the positioning, shape and size of the resistance elements and the flow conditions at the location.

We have developed models of the device (10) and tested these by applying water flow. It has been tested with different pipe diameters on the resistance elements, different heights, different degrees of perforation of the plate, and also the distance and position of the cylinders have been tested. The tests have clearly confirmed that a water flow applied horizontally to horizontally positioned plates, where the plates have vertically protruding resistance elements, will move the plates vertically upwards or downwards in the water column.

For example, we have tested small-scale models with plates of 75x75 cm, and where the pipe diameter has been 8.5 cm. The height of the cylinders has been 0.5 to 2 pipe diameters. It has been tested with different numbers of cylinders and with different locations.

During the tests, a flow of approx. 0.4 cm/sec has typically been applied. The movement energy has been measured indirectly by measuring how heavy a load the plates can move upwards, or by measuring how much buoyancy can be overcome by moving the plates downwards. In this model, we measured that the plate pulls down with an effect of 5-6 kg in addition to counteracting a buoyancy of 2 kg. If you attach a plumb bob to the plate (e.g. lead), the same forces are measured upwards.

One aspect of the invention relates to a method for converting kinetic energy in a water flow into another form of energy, preferably electrical energy.

One identifies a location with water currents. Preferably, the water currents should be stable and persist over time, but you can also use tidal currents that typically change direction when the tide turns.

A device (10) is positioned underwater, vertically in the water column so that the laminar water currents act on the device (10). This can, for example, be at depths from 30 meters deep, or even deeper. As the laminar flows press against the resistance elements (14) and the sheet-like structure (12), a greater pressure will be established on the side of the structure (12) where the resistance elements are protruding. The laminar flow (arrow A in Figure 1) is transformed into turbulence, which presses on the plate and ensures that it moves in the direction with the least pressure. That is that the plate will move upwards when the resistance elements are on the underside of the plate, and the plate will move downwards (arrow B in figure 1) when the resistance elements (14) are on the upper side of the plate (12).

When the plate (12) has moved sufficiently, the position of the resistance elements is changed so that the plate moves in the opposite direction. The plate will thus move reciprocatingly, respectively upwards and downwards in the water column. The movement of the plate (12) will be independent of which side the laminar water flow comes from, or whether the direction of the water flow changes (as with tidal currents).

Activation of cylinder movement can be controlled automatically, i.e. when the structure (12) approaches a given position, the magnetic lock is deactivated, and air/gas is supplied or released by the buoyancy means so that the relationship between gravity and buoyancy controls movement of the cylinders (14). The position of the cylinders (14) in relation to the structure (12) will determine the direction of movement of the structures (12).

The structures (12) will thus continuously move upwards or downwards, and the movement energy of this mass is converted in an energy conversion unit (60) into another form of energy, preferably electrical energy.

Claims (17)

Patent claims 1. Device (10) for converting the movement energy in a water flow, characterized in that the device (10) comprises a movable stored sheet-like structure (12) for reciprocating movement between a first and a second turning point, where said sheet-like structure (12) is in connection with an energy-generating device (20) for converting the reciprocating movement of the structure (12) into another form of energy, where one or more resistance elements (14) are movably stored on the structure (12) which form an angle of attack against the direction of the water flow, where the resistance elements (14 ) can be changed to be protruding on one or the other side of the structure (12). 2. Device (10) in accordance with claim 1, characterized in that one or more sheet-like structures (12) are movably stored in a framework (40). 3. Device (10) in accordance with claim 1, characterized in that each sheet-like structure (12) comprises one or more resistance elements (14). 4. Device in accordance with any of claims 1-3, characterized in that the framework (40) is positioned in a laminar water flow, preferably by means of attachment to buoyancy aids (buoys) on the water surface. 5. Device in accordance with any of claims 1-4, characterized in that the sheet-like structure is a plate, canvas or tarpaulin. 6. Device in accordance with any of claims 1-5, characterized in that said resistance element (14) is a cylinder (14) which is movably arranged in an opening in the structure (12) arranged so that the position of the cylinder (14) in relation to the structure (12) can be moved from a position on the underside of the structure (12) to a position on the upper side of the structure (12), and vice versa. 7. Device in accordance with claim 6, characterized in that the cylinder (14) comprises barbs (14a) in the upper and lower part arranged so that the cylinder will stop when the barbs (14a) form an engagement with the structure (12). 8. Device in accordance with claim 6, characterized in that the cylinder (14) comprises means for moving the cylinder up and down in the water column. 9. Device in accordance with claim 8, characterized in that said means for moving the cylinder downwards in the water column are established as the cylinder has a density that is greater than the surrounding water. 10. Device in accordance with claim 8, characterized in that said means for moving the cylinder upwards in the water column are buoyancy means (20) arranged adjacent to the cylinder (14), preferably on the inside of the cylinder (14), where movement of the cylinder (14) ) upwards is established by supplying the buoyancy means (20) with gas or air sufficient for the buoyancy to exceed the cylinder's (14) gravity. 11. Device according to any one of claims 1-10, characterized in that said sheet-like structure (12) comprises a number of openings/perforations. 12. Method for converting kinetic energy in a water flow into another form of energy, characterized in that a device according to any of claims 1-11 is arranged in a water flow, preferably a laminar water flow, where the device (10) in a first state is arranged with the resistance elements (14) projecting upwards and where the water flow will thus force, via the resistance elements, a downward movement of the sheet-like structure (12), and as the structure (12) has moved to a turning point, the resistance elements (14) are forced to change position to a second state where the resistance elements (14) project downwards from the structure (12) so that the sheet-like structure will move upwards in the water column, and where the movement energy from the reciprocating movement of the structure (12) is converted by the energy conversion means (60) into another form of energy. 13. Method in accordance with claim 12, characterized in that changing the position of the resistance elements (14) in relation to the structure (12) is carried out as the structure approaches a predetermined turning point. 14. Method in accordance with claim 13, characterized in that changing the position of the resistance elements (14) in relation to the structure (12) is performed automatically. 15. Method in accordance with claim 12, characterized in that the device (10) comprises one or more sheet-like structures (12), and that each of the sheet-like structures (12) comprises one or more resistance elements (14). 16. Method in accordance with claim 12, characterized in that the sheet-like structure is a plate, canvas or tarpaulin. 17. Method in accordance with claim 12, characterized in that said resistance element (14) is in the form of a cylinder (14).