Ocean current power generation system

Abstract

To provide an ocean current power generation system capable of performing stable ocean current power generation even in deep-sea areas.SOLUTION: The ocean current power generation system includes: a floating body that floats on the sea surface; an anchor fixed to a quay wall or the seabed; a mooring line connected to the anchor; an ocean current power generator connected to the mooring line; and a tether having one end fixed to the floating body and the other end fixed to the ocean current power generator. This configuration enables the deployment of the ocean current power generator even in deep-sea areas where operation of installing the anchor is difficult.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an ocean current power generation system.

Background Art

[0002] It is said that there is energy of several hundred TWh per year in ocean currents around the world. Since ocean currents are more stable than fluctuations in sunlight and wind power, power generation using ocean currents has attracted attention as a stable power generation method. Furthermore, since ocean current power generation does not emit carbon dioxide CO2, it has also attracted attention as power generation using natural energy with an extremely small environmental load. Conventionally, there has been a technology for converting the kinetic energy of water flow into electrical energy by rotating a rotating body such as a propeller using the water flow in the sea or a river.

[0003] Patent Document 1 describes a technology in which a water rotor is rotatably installed on a vertical member or a frame fixed to the seabed, and the rotational energy obtained by the ocean current rotating the water rotor is transmitted to an offshore generator via a power transmission mechanism vertically arranged inside the vertical member.

[0004] Also, conventionally, as shown in FIG. 1, there has been an ocean current power generation system of a type in which an anchor installed on the seabed and a power generation unit floating in the sea are fastened with a mooring cable. Patent Document 2 describes a submersible floating ocean current power generation device including a turbine rotated by the flow of seawater and a pod housing a power generation unit that supports the turbine and generates power by the rotation of the turbine, the submersible floating ocean current power generation device including fixing means fixed to the seabed such as a sinker, a mooring cable having one end connected to the fixing means and the other end connected to the pod, and mooring angle detection means for detecting a mooring angle which is an inclination of the mooring cable with respect to the fixing means.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] In the invention of Patent Document 1, it is necessary to fix vertical members and frameworks to the seabed, and in the invention of Patent Document 2, it is necessary to fix sinkers, etc. to the seabed. To fix a structure to the seabed, the water depth is at most about several hundred meters, and it is difficult to fix a structure to the seabed in deeper waters.

[0007] In the waters off the coast of Japan, the ocean current called the Kuroshio does not always flow in the same position, but usually flows at a location more than several tens of kilometers away from the land. The location more than several tens of kilometers away from the land is a deep sea area with a water depth of 1000 m or more, and it is not an area where an anchor can be installed on the seabed. If a power generation device is floated without an anchor, the power generation device may drift, so there is a risk that stable power generation cannot be performed. An object of the present invention is to provide an ocean current power generation system capable of stably performing ocean current power generation even in deep sea areas. [Means for Solving the Problems]

[0008] The invention according to claim 1 is an ocean current power generation system including a floating body floating on the sea surface, an anchor fixed to a quay wall or the seabed, a mooring cable connected to the anchor, an ocean current power generation device connected to the mooring cable, and a first cable body having one end fixed to the floating body and the other end fixed to the ocean current power generation device. The invention according to claim 2 is the ocean current power generation system according to claim 1, wherein the anchor is fixed at a position higher than the ocean current power generation device. The invention described in claim 3 is the ocean current power generation system according to claim 1 or claim 2, comprising a propulsion device and a positioning information receiver attached to the floating body, and a control device that drives the propulsion device based on the positioning information received by the positioning information receiver. The invention described in claim 4 is the ocean current power generation system according to claim 3, comprising a second cable body with one end fixed to the floating body and the other end fixed to the mooring cable.

Advantages of the Invention

[0009] According to the present invention, it is possible to provide an ocean current power generation system that can stably perform ocean current power generation even in deep sea areas.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 2 is a diagram showing an ocean current power generation system 1 to which the present embodiment is applied. The ocean current power generation system 1 is composed of a power generation device 20, a floating body 30, a propulsion device 40, a positioning information receiver 50, a cable body 60, a control device 70, a mooring cable 80, a power transmission cable 90, a weight 100, an anchor 200, etc.

[0012] The power generation device 20 is composed of a rotating body 21, a rotating body support structure 22, etc. Inside the rotating body 21, a generator (not shown) is built in. The rotating body 21 converts the energy of the ocean current into rotational energy, and the generator further converts the rotational energy into electrical energy. The electricity generated by the generator is sent to the land through the power transmission cable 90 and supplied to the power grid system, etc. The power generation device 20 does not have to be one unit, and may be composed of a plurality of power generation devices as shown in FIG. 2. It is desirable that the water depth at which the power generation device 20 floats is a water depth where the ocean current flows fast. For example, the power generation device 20 is installed so as to float at a water depth of several tens of meters to several hundreds of meters.

[0013] The floating body 30 is a structure having buoyancy and is connected to the power generation device 20 via a cable 60. Since the floating body 30 must always float on the sea surface, it has a buoyancy that balances the force with which the power generation device 20 tends to sink toward the seabed due to its weight. In the embodiment shown in FIG. 2, the floating bodies 30 are arranged corresponding to the power generation devices 20 respectively, but it may also be in a form in which each of the plurality of power generation devices 20 is connected by a cable 60 from one large floating body 30.

[0014] The propulsion device 40 is fixed to the floating body 30. For example, by rotating the propeller, the floating body 30 on the sea surface can be moved in an arbitrary direction. The positioning information receiver 50 can receive positioning information from positioning satellites such as GPS by radio waves and measure the position. One end of the cable 60 is fixed to the floating body 30, and the other end is fixed to the rotating body support structure 22 of the power generation device 20. The control device 70 determines whether the floating body 30 is in an appropriate position based on the position information of the positioning information receiver 50. When it is determined that there is a deviation from the proper point, the propulsion device 40 is driven to move the floating body 30 to the proper point. Since the floating body 30 always pulls the power generation device 20 with the cable 60, the power generation device 20 can continue to exist in the proper place. An information receiver (not shown) is installed on the floating body 30, and by receiving information on weather and sea conditions, it constantly monitors the central position of the Kuroshio current.

[0015] The mooring cable 80 is composed of a high-strength wire connecting the power generation device 20 and the anchor 200. The mooring cable 80 may be a high-strength metal wire with rust prevention technology applied. The power transmission cable 90 is a cable for transmitting the electricity generated by the generator of the power generation device 20. Since the power transmission cable 90 is inferior in strength compared to the mooring cable 80, it is wound around the mooring cable 80 and installed so that there is no mechanical burden such as tension on the power transmission cable 90. The mooring cable 80 is fixed to the anchor 200 fixed to the seabed. The power transmission cable 90 extends from the anchor 200 point along the seabed and reaches the land.

[0016] The weight 100 is connected to the lower end of the rotating body support structure 22 that constitutes the power generation device 20. The weight 100 has the effect of stabilizing the posture and position of the power generation device 20. If there is weight at the lower end rather than the upper end of the rotating body support structure 22, the stability for keeping the rotating body support structure vertical increases. Furthermore, the increased mass due to the presence of the weight 100 acts to suppress the action of the power generation device 20 being washed away by the ocean current, so that the position of the power generation device 20 can be stabilized. When the seabed S1 is shallow, the weight 100 can be fixed to the seabed S1, but in a deep sea area where the seabed S1 is deep, the weight 100 will float in the sea S2.

[0017] The anchor 200 is installed on the seabed S1 ranging from several tens of meters to several hundreds of meters. The anchor 200 is fixed by embedding it in the sediment in the case of the seabed S1 with sediment. In the case of bedrock with little sediment, the anchor 200 is fixed by driving piles, bolts, etc. into the seabed S1. Such work for fixing the anchor 200 is difficult in deep sea areas. Since there are many areas with a water depth of more than 1000 m in the area where the Kuroshio current flows fast, it is difficult to fix the anchor 200 to the seabed. For the above reasons, the anchor 200 is installed on the seabed S1 up to about several hundreds of meters, which is the installable water depth.

[0018] By adopting the above configuration, the ocean current power generation system 1 can extend the mooring cable 80 and the power transmission cable 90 to a deeper sea area than the laying point of the anchor 200. Therefore, the power generation device 20 can be positioned in the deep sea area S2 where the Kuroshio current flows. Since the distance between the anchor 200 and the power generation device 20 may range from several kilometers to several tens of kilometers, the power transmission cable 90 may break due to its own weight. For this reason, it is desirable to wind the power transmission cable 90 around the mooring cable 80 made of a wire with higher strength than the power transmission cable 90. Also, the power generation device 20 tends to sink in the deep sea area S2 due to gravity. Against this, the cable body 60 connected to the floating body 30 acts to pull the power generation device 20 upward by the buoyancy of the floating body 30 on the sea surface S3. Therefore, the floating body 30 needs to be a mechanism with sufficient buoyancy so that it can be maintained on the sea surface S3. In the embodiment shown in FIG. 2, the power generation device 20 is arranged at a deeper position than the anchor 200. For example, the anchor 200 is installed at a water depth of about 30 m, and the power generation device 20 can be arranged in the deep sea area S2 with a water depth of several hundred meters in the offing at a horizontal distance of about 10 km from the point where the anchor 200 is fixed. As described above, since the power generation device 20 is supported by the buoyancy of the floating body 30 and the mooring cable 80, it can stably maintain a floating state in the deep sea area S2.

[0019] In the normal operating state, the power generation device 20 connected to the mooring cable 80 stably exists at a substantially fixed position. That is, the tension from the mooring cable 80, the self-weight, the buoyancy from the floating body 30, and the force received by the power generation device 20 from the ocean current are balanced. Due to changes in the speed of the ocean current or the like, the position of the power generation device 20 may shift. In this case, the control device 70 detects the deviation from the center of the Kuroshio current flow from the position information of the positioning information receiver 50 and drives the propulsion device 40 to move to an appropriate point. As described above, according to the ocean current power generation system 1, stable ocean current power generation can be performed even in a deep sea area.

[0020] Note that a flow rectifying device such as fins (not shown) is installed in the rotating body support structure 22, and the power generation device 20 may be controlled to face the optimal direction with respect to the flow of the ocean current. This direction control may be in the form that the control device controls the angle of the fins based on information from a known ocean current direction and velocity sensor or the like.

[0021] FIG. 3 is a diagram showing an ocean current power generation system 2 to which the present embodiment is applied. In the ocean current power generation system 2 shown in FIG. 3, the vertical relationship between the positions of the anchor 200 and the power generation device 20 is different from that of the ocean current power generation system 1 shown in FIG. 2. In the ocean current power generation system 1 of FIG. 2, the power generation device 20 was at a position lower than the anchor 200, but in the ocean current power generation system 2 of FIG. 3, the power generation device 20 is at a position higher than the anchor 200. When the anchor 200 can be installed on the seabed deeper than the power generation device 20, power generation is performed in the embodiment of the ocean current power generation system 2 of FIG. 3. For example, the anchor 200 is installed at a water depth of about 200 m, and the power generation device 20 can be arranged in the sea S2 at a water depth of 50 to 100 m in the offing at a horizontal distance of about 10 km from the point where the anchor 200 is fixed.

[0022] When comparing the vertical positions of the anchor 200 and the power generation device 20, when the power generation device 20 is long in the vertical direction, the upper part of the power generation device 20 may be at a position higher than the anchor 200, and the lower part of the power generation device 20 may be at a position lower than the anchor 200. In such cases, in this specification, the vertical relationship is determined by comparing the positional relationship between the center of gravity point of the power generation device 20 and the center of gravity point of the anchor 200.

[0023] FIG. 4 is a diagram showing an ocean current power generation system 3 to which the present embodiment is applied. It is different from the embodiment of FIG. 2 in that there is a cable body 61 connecting the floating body 30 and the mooring cable 80. Regarding the same configuration as in FIG. 2, the description will be omitted. As the Kuroshio current flows farther from the land, the mooring cable 80 extending from the anchor 200 needs to be longer. Then, since the dead weight of the mooring cable 80 becomes very large, it leads to lack of stability and breakage of the mooring cable 80. Therefore, as described above, by connecting the cable body 61 between the floating body 30 and the mooring cable 80, the burden of the dead weight of the mooring cable 80 can be dispersed and it can be stably arranged. One end of the cable body 61 is fixed to the floating body 30 and the other end is fixed to the mooring cable 80. For example, by arranging the cable body 61 every 500 m, the burden on the mooring cable 80 itself due to its own dead weight can be reduced. The length of the cable body 61 can be adjusted as appropriate. For example, in an area where the mooring cable 80 crosses the route, since it is necessary to install the mooring cable 80 at a location deeper than the diving depth of the hull, the cable body 61 needs to extend deeper than the diving depth so that the mooring cable 80 does not affect the ship. In addition, in the embodiment of FIG. 4, the anchor 200 is located at a position lower than the power generation device 20, but the anchor 200 may be installed at a position higher than the power generation device 20.

[0024] Even when the area directly below the power generation device 20 is a deep sea area where the anchor 200 cannot be fixed to the seabed, an ocean current power generation system capable of stably performing ocean current power generation can be provided according to the embodiments of FIGS. 2 to 4 described above. That is, since the floating body 30 near directly above the power generation device 20, the anchor 200 fixed to the seabed, and the power generation device 20 are connected by the cable body 60, the mooring cable 80, etc., the power generation device 20 can be stably operated even in a deep sea area. By having the above configuration, the present invention enables the installation and operation of the power generation device in a deeper sea area farther from the land than the location where the anchor 200 can be installed.

Explanation of reference numerals

[0025] 1, 2, 3... Ocean current power generation system, 20... Power generation device, 21... Rotating body, 22... Rotating body support structure, 23... Generator, 30... Floating body, 40... Propulsion device, 50... Positioning information receiver, 60... Cable body, 70... Control device, 80... Mooring cable, 90... Power transmission cable, 100... Weight, 200... Anchor, S1... Seabed, S2... Sea area, S3... Sea surface

Claims

1. A floating body floating on the sea surface, An anchor fixed to a quay wall or the seabed, A mooring cable connected to the anchor, An ocean current power generation device connected to the mooring cable, A first cable body having one end fixed to the floating body and the other end fixed to the ocean current power generation device, An ocean current power generation system comprising:

2. The ocean current power generation system according to claim 1, wherein the anchor is fixed at a position higher than the ocean current power generation device.

3. A propulsion device and a positioning information receiver attached to the floating body, A control device that drives the propulsion device based on the positioning information received by the positioning information receiver, The ocean current power generation system according to claim 1 or claim 2, comprising:

4. A second cable body having one end fixed to the floating body and the other end fixed to the mooring cable, The ocean current power generation system according to claim 3, comprising:

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