JP7548460B2 - Water storage device - Google Patents

Description

The present invention relates to a water storage device installed underwater.

Pumped-storage hydroelectric power generation, an electricity storage system that utilizes the potential energy of water, has been widely known for some time. In pumped-storage hydroelectric power generation, a power station equipped with a water turbine is constructed between an upper dam and a lower dam, and electricity is generated by a generator that drops water from the upper dam through the water turbine toward the lower dam. The water stored in the lower dam is then pumped up to the upper dam, and electricity is stored in the form of the potential energy of the water.

In recent years, marine inverse dams have been developed as a seawater potential energy storage system that uses the potential energy of seawater to repeatedly generate and store electricity, based on the same principle as the pumped storage hydroelectric power generation described above. Patent Document 1 discloses the details of this system as an electricity storage system, but an outline is shown in Figures 9(a) and (b). The marine inverse dam 200 is constructed near the seabed offshore, with a box-shaped water tank 201 that serves as the dam space, and a power generation facility 202.

At the marine inverse dam 200, electricity is generated by dropping seawater W into the water tank 201 via the power generation equipment 202, as shown in FIG. 9(a). On the other hand, when the water tank 201 is filled with the seawater W used for power generation, the seawater W is discharged using the lift pump 203, as shown in FIG. 9(b), to make the water tank 201 hollow. This makes it possible to resume power generation by the power generation equipment 202, which uses the potential energy of the seawater described above, and electrical energy is now stored.

Patent No. 5787943

As described above, the marine inverse dam 200 that uses seawater W can generate electricity steadily throughout the year because it is constructed offshore where the seawater level is stable. Also, by increasing the number and capacity of the box-shaped water tanks 201, it is possible to secure a large amount of electricity. Furthermore, by constructing a roof on the top of the water tank 201, it is expected that the roof area can be used to install large-scale solar panels or a power transmission/reception antenna can be installed to realize long-distance energy transmission using a microwave mirror satellite.

However, constructing a box-shaped water tank 201 underwater poses various challenges. For example, during construction, it is necessary to adjust the seabed to ensure stable installation of the water tank 201. Also, considering that the weight of the water tank 201 increases when seawater W flows into the water tank 201 to generate electricity, it becomes necessary to carry out ground improvement and ground reinforcement on the entire seabed surface on which the water tank 201 is to be installed so that the weight can be supported. Furthermore, considering that buoyancy acts on the water tank 201 when electricity is stored by pumping up the seawater W in the water tank 201, it becomes necessary to take measures such as constructing the water tank 201 to be heavy and anchoring ground anchors 204 into the seabed to resist this.

Furthermore, if the box-shaped water tank 201 is constructed at a height that reaches from the seabed to the sea surface, it may not be able to maintain its structural function in the event of a natural external force such as a tsunami, and so a high bending rigidity is required even under normal circumstances. In addition, the water tank 201 is expected to be a reinforced concrete structure, but in a marine environment not only is the reinforcing steel prone to early deterioration, but maintenance measures to prevent deterioration can also be difficult.

Furthermore, by installing the box-shaped water tank 201 offshore, it is possible to ensure a large installation area and depth to the seabed, which allows for a high level of power generation. However, this increases the distance to land where the electricity is used, which requires large-scale power transmission equipment and increases power loss during transportation.

The present invention has been made in consideration of these problems, and its main objective is to provide a water storage device that can be constructed efficiently underwater and has a structure suitable for use in a seawater potential energy utilization electricity storage system.

In order to achieve this object, the water storage device of the present invention is a water storage device comprising a pipe member having a seawater inlet and a seawater outlet communicating with the internal space, in which a storage space is formed, and a plurality of pipe member support members that support the longitudinal direction of the pipe member along the seabed surface, and is characterized in that an air injection pipe that supplies outside air to the storage space is provided on the seawater inlet side formed at one end of the pipe member, and a drainage mechanism that discharges seawater from the storage space and an exhaust mechanism that discharges air are provided on the seawater outlet side formed at the other end of the pipe member. The air injection pipe is also characterized in that it is provided with a check valve that supplies outside air to the storage space when open.

According to the water storage device of the present invention, the pipe material laid along the seabed surface is supported by multiple pipe material support members, so that if seawater flows into the storage space of the pipe material and the total weight of the pipe material increases, the load can be shared and supported by the multiple pipe material support members. Similarly, if buoyancy acts on the pipe material after seawater is discharged from the storage space, this buoyancy can be resisted by each of the multiple pipe material support members.

This eliminates the need for large-scale underwater work such as leveling the seabed and improving the seabed foundation, allowing the water storage device to be constructed efficiently underwater. Furthermore, even if seawater repeatedly flows in and out of the storage space, the pipe support members allow the pipes to be stably installed on the seabed. This makes it possible to use the water storage device as a suitable structure for a seawater potential energy storage system, such as an ocean inverse dam, where seawater flows in and out every time electricity is generated and stored.

In addition, by appropriately changing the extension shape of the pipe material to a straight line, curved line, cross-shaped line in plan view, etc., it is possible to freely adjust the volume of the storage space. Furthermore, as long as the pipe material has a rigidity sufficient to withstand water pressure when installed on the seabed, there is no need to ensure high rigidity to withstand natural forces such as tsunamis, as is the case when using a box-shaped structure, and the water storage device can be made into a structure with high resistance to natural forces.

According to the water storage device of the present invention, suction anchors are used as pipe support members, which simplifies the installation of pipes on the seabed and improves workability. In this case, if standardized products such as precast members that are traded on the market as pipes are used, the work to be performed underwater can be significantly reduced, making it possible to further improve workability. In addition, since the pipes can be easily removed, maintenance work such as replacing or relocating the pipes that may be performed after the system is put into service can be easily performed.

According to the water storage device of the present invention, since the pipe material is composed of multiple pipe material bodies, it is possible to easily increase or decrease the capacity of the storage space provided in the internal space by appropriately changing the number of pipe material bodies that are connected. Furthermore, if a defect such as damage occurs in a part of the pipe material, the damaged pipe material body can be removed and replaced, and maintenance work on the pipe material can be easily performed.

If the water storage device of the present invention is used in an electricity storage system that converts electrical energy into potential energy of seawater and stores it, the capacity of the storage space can be freely adjusted by appropriately changing the extension shape of the pipe material installed along the seabed, with the seawater inlet of the pipe material located near the shore. This not only makes it possible to secure the desired amount of stored electricity while locating the power generation equipment connected to the seawater inlet of the pipe material near the shore, but also makes it possible to reduce the labor required for the power transmission equipment required to transmit the generated electricity to land and significantly reduce power losses associated with power transmission.

According to the present invention, the water storage device has a simple structure in which a pipe with a storage space in its internal cavity is supported by a plurality of pipe support members while aligned with the seabed surface, so that it can be constructed efficiently underwater, and even if seawater repeatedly flows in and out of the storage space, the pipe support members allow the pipe to be stably installed on the seabed surface, making it possible to use it as a suitable structure for a seawater potential energy utilization electricity storage system.

1 is a diagram showing an outline of a power storage system according to an embodiment of the present invention; 5A to 5C are diagrams showing details of a pipe material support member in an embodiment of the present invention. 1 is a diagram showing an example of a water storage device according to an embodiment of the present invention (part 1). FIG. FIG. 2 is a diagram showing an example of a water storage device according to an embodiment of the present invention (part 2). FIG. 3 is a diagram showing an example of a water storage device according to an embodiment of the present invention (part 3). FIG. 4 is a diagram showing an example of a water storage device according to an embodiment of the present invention; 1A to 1C are diagrams showing a method for constructing a water storage device according to an embodiment of the present invention (part 13A to 13C are diagrams showing a method for constructing a water storage device in accordance with an embodiment of the present invention (part 2). FIG. 1 is a diagram showing an example of a marine inverse dam according to the prior art.

The water storage device of the present invention is suitable for use in an electricity storage system that converts electrical energy into potential energy of seawater and stores it. The details of the electricity storage system using the water storage device will be described below with reference to Figures 1 to 8.

<<Energy Storage System>>
As shown in Figures 1(a) and (b), the energy storage system 100 includes a power generation equipment 10 that generates power using seawater W, a water storage device 20 through which the seawater W used in the power generation equipment 10 flows, a drainage device 30 that discharges the seawater W stored in the water storage device 20, and an air injection pipe 40 that supplies outside air to the water storage device 20.

The power generation facility 10 includes an inflow pipeline 11 through which seawater W flows, a power generation device 12 to which the seawater W that has flowed down the inflow pipeline 11 is supplied, and an outflow pipeline 13 that supplies the seawater W that has flowed out from the power generation device 12 to the water storage device 20. The power generation device 12 is the same as the power generation facility provided in a pumped-storage hydroelectric power generation system, and includes a water turbine that uses the seawater W to rotate, and a generator that uses the rotation of the water turbine to generate electricity. If necessary, a water flow facility may be provided to adjust the flow rate of the seawater W that flows down from the inflow pipeline 11 toward the outflow pipeline 13.

The water storage device 20 is installed along the seabed surface sf so as to connect the power generation equipment 10 arranged on the shore side of the seabed with the drainage equipment 30 arranged on the offshore side, and has a storage space S1 capable of storing seawater W flowing down from the power generation equipment 10. Details of the water storage device 20 will be described later.

The drainage facility 30 includes a drainage pump 31 that discharges seawater W stored in the water storage device 20, and a power generation system 32 that generates power for the drainage pump 31. In this embodiment, offshore wind power generation is used as an example of the power generation system 32, but this is not limited to this, and solar power generation or the like may also be used. In addition, as long as equipment capable of supplying power to the drainage pump 31 is provided, the power generation system 32 does not necessarily have to be installed.

As shown in FIG. 1(a), the storage system 100 having the above-described configuration starts supplying seawater W to the power generation device 12 through the inlet pipe 11 when the storage space S1 of the water storage device 20 is hollow or has a gap that can store water. At this time, the air injection pipe 40 has a solenoid valve such as a check valve (not shown) in a closed state. In addition, an exhaust mechanism (not shown) for exhausting air from the storage space S1 is provided, for example, in the drainage equipment 30 and is operated. As a result, when seawater W is supplied, the power generation device 12 generates electricity, and the electricity obtained by the generation is transmitted to the substation facility 15 provided on the land side through the power transmission equipment 14.

Meanwhile, the seawater W that has passed through the power generation device 12 flows down through the outflow pipe 13 into the water storage device 20 and is stored in the storage space S1. Then, as shown in FIG. 1(b), when the storage space S1 of the water storage device 20 is filled or when the desired amount of power generation is reached, power generation is temporarily stopped and the drainage equipment 30 is operated. At this time, the air injection pipe 40 opens an electromagnetic valve such as a check valve (not shown) so that outside air can be supplied to the storage space S1.

Then, the seawater W is discharged from the storage space S1, making it hollow, and the power generation facility 10 is again able to generate electricity using the potential energy of the seawater W, which means that electrical energy has been stored. This causes the energy storage system 100 to function as a seawater potential energy storage system that repeatedly generates and stores electricity using the potential energy of the seawater W.

<<Water Storage Device>>
The water storage device 20 used as described above comprises a pipe material 21 whose inner space forms a storage space S1, and a plurality of pipe material support members 22 that support the pipe material 21 on the seabed surface sf, as shown in Figure 1(b).

The pipe material 21 is installed along the seabed surface sf so as to extend from the shore side toward the offshore side, and a seawater inlet section 21a is formed at one end located on the shore side, to which the outlet pipeline 13 of the power generation equipment 10 is connected. A seawater outlet section 21b is formed at the other end located on the offshore side of the pipe material 21, to which the drainage pump 31 of the drainage equipment 30 is connected. In this way, the pipe material 21 connecting the power generation equipment 10 and the drainage equipment 30 is installed on the seabed surface sf via the pipe material support member 22.

As shown in FIG. 2(a), the pipe material support member 22 is equipped with a gripping member 23 that grips the pipe material 21, and a suction anchor 24 to which the gripping member 23 is attached. The suction anchor 24 is composed of a top plate 241 and a skirt member 242 having a cylindrical shape that hangs down from the underside of the top plate 241, and the gripping member 23 is attached to the upper surface of the top plate 241.

As shown in Figures 2(a) and 2(b), the top plate 241 is further provided with drainage holes 2411 for draining seawater W that is retained in the space enclosed by the enclosed space S2 of the top plate 241 and the skirt member 242. As a result, as shown in Figure 2(b), when the skirt member 242 is in contact with the seabed surface sf and the seawater W in the enclosed space S2 is drained using the drainage holes 2411, the skirt member 242 penetrates into the seabed and maintains this state, functioning as an anchor member that is fixed to the seabed.

By providing multiple such pipe material support members 22 in the longitudinal direction of the pipe material 21 grasped by the grasping member 23, as shown in FIG. 1(b), when seawater W is stored in the storage space S1 of the pipe material 21, the load can be shared and supported by the multiple pipe material support members 22. Therefore, there is no need to carry out extensive ground improvement work on the seabed ground on which the water storage device 20 is located.

On the other hand, as shown in FIG. 2(c), when seawater W is discharged from the storage space S1 of the pipe material 21, buoyancy occurs in the pipe material 21, and a pull-out load acts on each of the multiple pipe material support members 22. However, the pipe material 21 can resist this by the suction anchors 24 that constitute the pipe material support members 22 fixed to the seabed. Therefore, there is no need to take measures such as increasing the weight of the pipe material 21 or providing ballast to take buoyancy into account.

In this way, the water storage device 20 can stably install and support the pipe material 21 on the seabed surface sf by the pipe material support member 22, even when seawater W repeatedly flows in and out of the storage space S1 of the pipe material 21. Therefore, the water storage device 20 can be used as a suitable structure for a seawater potential energy utilization electricity storage system in which seawater W flows in and out every time electricity generation and storage are repeated.

<<Extension shape of pipe material>>
In the water storage device 20 having the above-described configuration, the pipe material 21 is composed of a plurality of pipe material bodies 211. As illustrated in Fig. 1 and Fig. 3 to Fig. 6, by combining a plurality of pipe material bodies 211 and appropriately changing the extension shape of the pipe material 21, it is possible to freely adjust the capacity of the storage space S1 provided in the inner hollow portion.

As shown in FIG. 1(b), the pipe body 211 is a long tubular member with an internal hollow portion, and may be made of any material that has sufficient rigidity to not deform significantly even when subjected to water pressure when positioned on the seabed surface sf. For example, it is possible to use standard products that are widely traded on the market, such as precast concrete Hume pipes and box culverts, and the cross-sectional shape may be either cylindrical or square.

The pipe material 21 is formed by connecting adjacent ends of such pipe material bodies 211 so that the internal space that constitutes the storage space S1 is in communication. As a result, if a defect such as damage occurs in a part of the pipe material 21, the pipe material body 211 located in the defective part can be removed and replaced, making it possible to easily carry out maintenance work on the pipe material 21. The pipe material bodies 211 may be connected to each other by any means, but for example, it is recommended to use an intermediate body 25 as shown in Figure 2 (a).

The intermediate body 25 is a joint member that connects adjacent pipe bodies 211 in a communicating state, and any structure such as a sleeve joint or a flexible joint can be used as long as it can be connected watertight and is detachable. The intermediate body 25 having such a configuration may be installed together with the gripping member 23 on the upper surface of the top plate 241 that constitutes the suction anchor 24 of the pipe support member 22, or it may be used alone without being installed on the pipe support member 22.

In addition, if the pipe body 211 has male or female joints at both ends, for example, and a watertight joint can be formed between adjacent pipe bodies 211, the intermediate body 25 does not necessarily have to be used.

As shown in Figures 1(a) and 1(b), for example, multiple pipe bodies 211 having such a configuration are sequentially connected in a straight or curved manner in the longitudinal direction to form the pipe 21, which connects the power generation equipment 10 and the drainage equipment 30. This makes it possible to easily increase or decrease the capacity of the storage space S1 of the pipe 21 and the extension length of the pipe 21.

Here, the number of pipes 21 connecting the power generation equipment 10 and the drainage equipment 30 is not limited to one, and multiple pipes may be arranged in parallel. For example, in Fig. 3(a) and (b), two pipes 21 are arranged in parallel, and the seawater inlet 21a and the seawater outlet 21b are connected to the power generation equipment 10 and the drainage equipment 30, respectively. In this way, even if maintenance becomes necessary due to damage to one of the equipment, it is possible to continue operating the power generation equipment 10. In this case, the two parallel pipes 21 may be structured to communicate with each other using a relay body 25 as shown in Fig. 3(a), or may be structured to be independent of each other as shown in Fig. 3(b).

The pipe material 21 is not necessarily limited to a linear shape such as a straight line or a curved line. For example, as shown in FIG. 4(a), a single main line 21A made of pipe material 21 connects the power generation equipment 10 and the drainage equipment 30. Two branch lines 21B also made of pipe material 21 may be separately connected to this main line 21A to form a cross shape in a plan view. In this case, the above-mentioned relay body 25 is interposed between the connection between the main line 21A and the branch line 21B to connect the storage spaces S1 of the main line 21A and the branch line 21B.

Also, as shown in FIG. 4(b), multiple branch lines 1B may be connected to the main line 21A. In this way, by appropriately changing the number and length of the branch lines 21B connected to the main line 21A, it is possible to adjust the capacity of the storage space S1 while maintaining a constant distance between the power generation equipment 10 and the drainage equipment 30. This makes it possible to ensure a large-capacity storage space S1 while keeping the main line 21A connecting the power generation equipment 10 and the drainage equipment 30 short and small, that is, while moving the entire energy storage system 100 closer to the shore of the sea area.

Furthermore, the seawater inlet 21a and the seawater outlet 21b of the pipe 21 do not necessarily need to be provided in different positions, and both may be used in the same place. Specifically, as shown in FIG. 5, a seawater inlet 21c is provided in the main line 21A made of the pipe 21, and two branch lines 21B made of the pipe 21 are prepared. The other ends of these two branch lines 21B are then each connected to the seawater inlet 21c, and one end of one branch line 21B is connected to the power generation equipment 10, and one end of the other branch line 21B is connected to the drainage equipment 30.

Then, the above-mentioned relay structure 25 is installed at the connection between the main line 21A and the two branch lines 21B to connect the three lines. In this case, if the seawater inlet/outlet 21c is provided on the shore side in the longitudinal direction of the main line 21A, both the power generation equipment 10 and the drainage equipment 30 can be located on the shore side. This makes it possible to significantly improve workability during construction compared to when the drainage equipment 30 is located on the offshore side, and also improves the workability of maintenance work during operation.

The seawater inlet 21a and seawater outlet 21b on the pipe 21 are not limited to one each, and may be provided in multiple locations. For example, in FIG. 6, the pipe 21 is constructed in a U-shape in a plan view, and is installed on the seabed surface sf with the opening of the U-shape facing the shore. Seawater inlet 21a is then provided at each of the two ends of the pipe 21 located on the shore side, and a power generation facility 10 is connected to each. In addition, three seawater outlets 21b are provided on the offshore portion of the pipe 21, and drainage facilities 30 are connected to each.

In this way, it is possible to increase the amount of power generated by operating the two power generation facilities 10 simultaneously or alternately. Also, if one of the power generation facilities 10 needs maintenance due to a malfunction, the other power generation facility 10 can be operated, making it possible to continue power generation work when a power supply is required.

<<<How to construct a water storage device>>
An example of a method for constructing the water storage device 20 will be described below. First, as shown in Fig. 7(a), pipe support members 22 are placed at predetermined intervals at the planned installation positions of pipe members 21 on the seabed surface sf. At this time, it is preferable to abut a part of the suction anchors 24 of the pipe support members 22 against the seabed ground.

Next, as shown in FIG. 7(b), the seawater W remaining in the enclosed space S2 surrounded by the top plate 241 and the skirt member 242 is drained using the drainage holes 2411, causing the skirt member 242 to penetrate into the seabed and anchoring the pipe support member 22 to the seabed. In this embodiment, the pipe support members 22 are installed at intervals roughly equivalent to the length of the pipe main body 211, and the ends of adjacent pipe main bodies 211 are arranged to face each other above the pipe support member 22.

Next, as shown in FIG. 7(c), the vicinity of the end of the pipe body 211 is placed on the top plate 241 of the suction anchor 24, and then the pipe body 211 is gripped on the top plate 241 via the gripping member 23. This operation is carried out continuously, and as shown in FIG. 8(a), multiple pipe bodies 211 are sequentially placed on the pipe support member 22 via the gripping member 23.

In parallel with the work of installing the pipe material main body 211 on the pipe material support member 22, or after completing these works, as shown in Figure 8 (b), the ends of adjacent pipe material main bodies 211 are connected in a communicating state using the relay body 25 to construct a pipe material 21 formed in a desired extension shape or having a desired capacity in the storage space S1. In this embodiment, the ends of adjacent pipe material main bodies 211 are opposed to each other on the top plate 241, so the relay body 25 is placed on the pipe material support member 22.

In this way, even if seawater W repeatedly flows in and out of the storage space S1, the pipe material 21 can be stably installed and supported on the seabed surface sf by the pipe material support member 22, without the need for large-scale work such as leveling the seabed surface sf or improving the seabed ground. Therefore, the underwater work required to construct the water storage device 20 can be significantly reduced, and the water storage device 20 can be constructed efficiently underwater.

After constructing the water storage device 20 consisting of the pipe material 21 and the pipe material support member 22 according to the procedure described above, the power generation equipment 10 and the drainage equipment 30 are connected to the water storage device 20, and the storage system 100 as shown in FIG. 1 is constructed on the seabed surface sf.

The above-mentioned power storage system 100 employs a water storage device 20, and while the seawater inlet 21a of the pipe material 21 installed along the seabed surface sf is located near the shore side, the capacity of the storage space S1 can be freely adjusted by appropriately changing the extension shape of the pipe material 21. This not only ensures the desired amount of stored power while locating the power generation equipment 10 connected to the seawater inlet 21a of the pipe material 21 on the shore side, but also reduces the power required for the power transmission equipment 14 required to transmit the generated power to land and significantly reduces power loss associated with power transmission.

The water storage device 20 and the power storage system 100 using the water storage device 20 of the present invention are not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention.

For example, in this embodiment, the pipe material support member 22 that supports the pipe material 21 on the seabed surface sf is configured with a gripping member 23 that grips the pipe material 21 and a suction anchor 24 to which the gripping member 23 is attached, but this is not necessarily limited to this. As long as the pipe material 21 can be stably fixed and supported on the seabed surface sf, the pipe material support member 22 may adopt any support structure.

In addition, in this embodiment, the power storage system 100 is constructed using only the water storage device 20 equipped with the pipe material 21, but this is not limited to this, and the power storage system may be constructed by combining an ocean inverse dam 200 equipped with a box-shaped water storage tank 201, as shown in Figures 8(a) and (b) in the prior art.

100 Energy storage system 10 Power generation equipment 11 Inflow pipeline 12 Power generation device 13 Outflow pipeline 14 Power transmission equipment 15 Substation equipment 20 Water storage device 21 Pipe material 21a Seawater inlet section 21b Seawater discharge section 211 Pipe material main body 21A Main line 21B Branch line 22 Pipe material support member 23 Grip member (mounting tool)
24 Suction anchor 241 Top plate 2411 Drain hole 242 Skirt member 25 Intermediate structure 30 Drainage equipment 31 Drainage pump 32 Power generation system 40 Air injection pipe 200 Marine inverse dam 201 Water tank 202 Power generation equipment 203 Water lifting pump 204 Ground anchor sf Seabed surface W Seawater S1 Storage space S2 Enclosed space

Claims (2)

A pipe member having an internal space in which a storage space is formed and having a seawater inlet and a seawater outlet communicating with the internal space;
A water storage device comprising: a plurality of pipe material support members that support the pipe material in a longitudinal direction along the seabed surface,
An air injection pipe for supplying outside air to the storage space is provided on the seawater inlet side formed at one end of the pipe material,
A water storage device characterized in that a drainage mechanism for discharging seawater from the storage space and an exhaust mechanism for discharging air are provided on the seawater discharge section formed at the other end of the pipe material. The water storage device according to claim 1,
A water storage device characterized in that the air injection pipe is provided with a check valve that supplies outside air to the storage space when open.

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