Energy recovery method

Abstract

Provided is an energy recovery method that suppresses the influence on the course of a ship that generates power. The energy recovery method includes: a step in which a floating body constituting a power generation system generates power while automatically navigating, thereby accumulating energy in the floating body; and a step in which the energy transport ship recovers energy from the floating body in the vicinity of the end of the sea area in which the floating body is automatically navigated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of an energy recovery method for recovering energy generated at sea. BACKGROUND

[0002] As an energy generation method using such a method, a wind power generation using a kite tethered to a ship is proposed (see Patent Literature 1).

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: International Publication No. 2021 / 094987 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] For example, the wind power generation using a kite tethered to a ship is performed in a sea area far from land. Therefore, it is difficult to use a power cable to transport electric power from the ship. In addition, from the viewpoint of the operation rate, it is desirable that the ship tethering the kite be exclusively used for power generation. In light of the above, it can be said that it is desirable to transport electric power (i.e., energy) generated by the wind power generation to land by a different ship from the ship tethering the kite. In this case, there is a technical problem point that, if another ship approaches the ship tethering the kite, it is likely to affect the course of the ship tethering the kite.

[0008] The present application is an application accomplished in view of the above problem point, and a problem thereof is to provide an energy recovery method capable of suppressing an influence on a course of a ship performing power generation.

[0009] METHOD FOR SOLVING THE PROBLEM

[0010] An energy recovery method according to one embodiment of the present application is a method including: a step of accumulating energy in a floating body constituting a power generation system by performing power generation while the floating body automatically travels; and a step of recovering the energy from the floating body by an energy transport ship at a position near an end of a sea area in which the floating body automatically travels. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 A conceptual diagram for illustrating a concept of a power generation system according to an embodiment.

[0012] Figure 2 A diagram for illustrating one example of a floating body according to an embodiment.

[0013] Figure 3 A diagram for illustrating one example of a travel path of a floating body according to an embodiment.

[0014] Figure 4 A flowchart illustrating the movement of the transport ship and the floating body involved in the implementation method.

[0015] Figure 5 This diagram illustrates an example of a change in the movement path of the floating body according to the embodiment. Detailed Implementation

[0016] Reference Figures 1 to 5 The implementation methods involved in the energy recovery method will be described.

[0017] (Structure of a power generation system)

[0018] Reference Figures 1 to 3 The structure of the power generation system will now be described. In the power generation system of this embodiment, multiple floats 20 that do not require mooring are used to generate electricity in a sea area SA that is relatively far from land. The multiple floats 20 navigate automatically within the sea area SA. That is, the multiple floats 20 generate electricity while navigating automatically within the sea area SA. For example, the sea area SA can also be a sea area 50 kilometers from land.

[0019] Reference Figure 2 Let's now explain the float 20. Figure 2 In (a), the float 20a, serving as the float 20, includes a sail 21 and a kite 22. The float 20a can utilize the wind energy carried by the sail 21 as propulsion. In the float 20a, as the kite 22 rises, the tethering line for the kite 22 is unwound from a winch (not shown). The unwinding action of the tether causes the winch drum to rotate. A generator (not shown) rotates along with this drum, generating electricity. After the tether has been unwound to a predetermined length, or after a predetermined time, the winch drum rotates in the direction of winding up the tether via a motor. As a result, the kite 22 descends due to the winding up of the tether. Electricity is generated in the float 20a by repeatedly performing the unwinding and winding actions of the tether. In other words, tethered wind power generation is performed in the float 20a. In addition, the float 20a can also utilize the wind energy carried by the kite 22 as a propulsion force.

[0020] exist Figure 2 In (b), the float 20b, which serves as the float 20, includes a sail 21 and an underwater turbine generator 23. The float 20b can utilize the wind energy collected by the sail 21 as propulsion. As the float 20b moves, seawater flows into the underwater turbine generator 23. As a result, electricity is generated through the underwater turbine generator 23.

[0021] In addition, the float 20a can also be equipped with an underwater turbine generator 23. That is to say, in addition to tethered wind power generation, the float 20a can also generate electricity using the underwater turbine generator 23. Similarly, the float 20b can also be equipped with a kite 22. That is to say, in addition to generating electricity using the underwater turbine generator 23, the float 20b can also generate electricity using the tethered wind power.

[0022] The float 20 can store electricity generated through power generation in a battery (e.g., a lithium-ion battery). In other words, the float 20 can store electrical energy as electrical energy. The float 20 can also electrolyze water using the electricity generated to produce hydrogen. The float 20 can then store this produced hydrogen. That is, the float 20 can also store electrical energy as hydrogen energy. Furthermore, hydrogen can be stored either through compression or by being adsorbed by a hydrogen-absorbing alloy.

[0023] In the following text, it is assumed that the float 20 generates hydrogen by electricity obtained from power generation and compresses and stores the generated hydrogen.

[0024] Return to Figure 1 The transport ship 10 navigates between a land-based port P and a sea area SA. For example, near the end of the sea area SA (e.g., area CA), the transport ship 10 retrieves compressed hydrogen tanks containing hydrogen from the float 20. At this point, the transport ship 10 delivers the empty hydrogen tanks to the float 20. The transport ship 10 then transports the hydrogen tanks retrieved from the float 20 to the port P. In the port P, the transport ship 10 unloads the hydrogen tanks retrieved from the float 20 and loads them with empty hydrogen tanks. The transport ship 10 then proceeds to the sea area SA. Here, "near the end of the sea area SA" means an area where the transport ship 10 and the float 20 can rendezvous and where the course of the float 20 is not affected by the transport ship 10.

[0025] Thus, in this power generation system, offshore power generation is achieved by multiple floating bodies 20, and energy transportation is achieved by transport ships 10.

[0026] Next, an example of the number of floats 20 will be given. For example, if the power generation capacity of the power generation system is 5 GW (gigawatts) and the rated output of one float 20 is 1 MW (megawatts), the power generation system has 5,000 floats 20.

[0027] like Figure 1As shown, multiple floats 20 form a queue. Furthermore, the multiple floats 20 automatically navigate along a route set within the sea area SA. Here, by forming a queue, interference between the floats 20 can be suppressed. As a result, the reduction in the power generation efficiency of one float 20 due to other floats 20 can be prevented. Additionally, the "route" can also be referred to as a "movement path" or "track." For example, the transport ship 10 recovers hydrogen tanks from the floats 20 in area CA. From an energy efficiency point of view, it is desirable that the hydrogen tanks be full when the floats 20 arrive at area CA.

[0028] For example, in Figure 1 In this process, the float 20 can travel from the left side of sea area SA along edge S1 (i.e., the top) to near edge S2 (i.e., the right side) of sea area SA, and then turn back near edge S2, traveling along edge S1 to the left side. In this case, the length L1 of edge S1 such that the hydrogen tank is full when the float 20 reaches the left side of sea area SA (in other words, region CA) can be determined in the following manner.

[0029] As a premise, a buoy 20 with a rated output of 1MW is required to navigate with a quadrilateral occupied area of ​​700 meters, provided it does not interfere with other adjacent buoys 20. Furthermore, the speed of the buoy 20 is set to 5 m / s, the time from an empty hydrogen tank to a full tank is set to 24 hours, and the buoy 20 is set to navigate four laps within a designated sea area SA in 24 hours. The length of the straight section along edge S1 of the buoy 20's route is defined as L_Line, and the length of the circling section of the route is defined as L_terminal. In this case, the length of one lap of the buoy 20's route is "2 × L_Line + 2 × L_terminal". Here, if the length of one side of the occupied area is defined as L_float, then L_terminal is expressed as "L_terminal = L_float × 2 × pi / 2". That is, "L_terminal = L_float × pi".

[0030] As mentioned above, the float 20, traveling at a speed of 5 m / s, completes four laps on the course in 24 hours. If we define the speed of the float 20 as V_fleet, the travel time as T, and the number of laps as N, then the mathematical formula "V_fleet × T = N × (2 × L_Line + 2 × L_terminal)" holds true. According to this formula, L_Line becomes 51802 meters. The length of the side S1 extending from the circling portion of the float 20 is 1400 meters. In this case, the length L1 of the side S1 of the sea area SA becomes approximately 53 kilometers.

[0031] When multiple floats 20 form a queue and navigate along the aforementioned route, the number of floats 20 capable of navigating along a single route, N_float_inLine, is expressed as "N_float_inLine ≤ 2 × L_Line / L_float". Here, N_float_inLine = 148. Assume that multiple floats 20 capable of navigating along a single route form a queue. In this case, to accommodate 5000 floats 20 within the sea area SA, 34 queues are required. If the number of queues (34 here) is set to N_fleet, then the length L2 of the edge S2 of the sea area SA is expressed as "L2 = 2 × N_fleet × L_float". Here, the length L2 of the edge S2 becomes approximately 48 kilometers.

[0032] Furthermore, the power generation capacity, the rated output of a single float 20, the speed of the float 20, the time it takes for the hydrogen tank to become full, the number of times the float 20 circles the route, and the length of one side of the quadrilateral area required for the float 20 to navigate without interfering with other adjacent floats 20, described above, are examples and are not limited to these. Therefore, the size of the sea area SA is not limited to the dimensions described above. Additionally, although in Figure 1 The diagram shows a quadrilateral sea area SA, but the shape of sea area SA may not be quadrilateral. Furthermore, the position of sea area SA may not be fixed. For example, the position of sea area SA may be changed according to the course of buoy 20.

[0033] Next, refer to Figure 3 Let's illustrate the course of float 20 with an example. When utilizing wind energy caught by the sail as propulsion, the speed of float 20 is maximized when it receives wind from the side relative to its direction of travel. Therefore, as... Figure 3 As shown in (a) and (b), the course of the float 20 can be set such that the float 20 travels for a relatively long period in a direction almost perpendicular to the wind direction. In addition, the course of the float 20 can be set by taking into account factors other than wind direction, such as wind speed, ocean current direction and ocean current speed.

[0034] According to the inventors' research, when the float 20 is used for tethered wind power generation, if the float 20 moves upwind when unwinding the tether (i.e., during power generation) and downwind when rewinding the tether, the net power generation will increase. Therefore, when the float 20 is used for tethered wind power generation, it is desirable for the float 20 to move along... Figure 3 It navigates automatically along the route shown in (a).

[0035] In the case where the float 20 is used to generate electricity for the underwater turbine generator, it is expected that the float 20 will move along...Figure 3 The float 20 will automatically navigate along the route shown in (b). This is because it is expected that the speed of the float 20 will be at its maximum. Additionally, the float 20 can also navigate along... Figure 3 It navigates automatically along the route shown in (c).

[0036] (The movement of transport ship 10 and buoy 20)

[0037] Next, refer to Figure 4 The flowchart illustrates the operation of the transport vessel 10 and the floating body 20 in the power generation system. Figure 4 In this process, the transport ship 10 travels from port P to an energy recovery location (e.g., area CA) (step S111). The energy recovery location is approximately near the end of sea area SA. At this time, the float 20 generates electricity and stores energy while automatically navigating within sea area SA (step S121). Furthermore, the float 20 can store both electrical and hydrogen energy as energy obtained from power generation.

[0038] When the transport vessel 10 arrives at the energy recovery point and the transport vessel 10 and the float 20 rendezvous, the float 20 transfers energy to the transport vessel 10 (step S122), and the transport vessel 10 recovers energy from the float 20 (step S112). For example, the transport vessel 10 can recover a compressed hydrogen tank from the float 20 and hand over the empty hydrogen tank to the float 20. For example, the transport vessel 10 can recover a charged battery that has stored electrical energy from the float 20 and hand over an uncharged battery to the float 20.

[0039] After the process in step S122, the float 20 performs the process in step S121. That is, the float 20 generates electricity while automatically navigating within the sea area SA. After the process in step S112, the transport ship 10 proceeds from the energy recovery location to port P (step S113). After the transport ship 10 arrives at port P, it replaces the energy storage tank (step S114). For example, if the transport ship 10 recovers a compressed hydrogen tank containing hydrogen from the float 20, it can unload the hydrogen tank and load an empty hydrogen tank. For example, if the transport ship 10 recovers a charged battery from the float 20, it can unload the charged battery and load an uncharged battery. Then, the transport ship 10 performs the process in step S111. That is, the transport ship 10 proceeds from port P to the energy recovery location.

[0040] In addition, regarding the route of buoy 20 within sea area SA, such as Figure 1 As shown, the course of one group of floats 20 may be the same as that of another group of floats 20. For example, all the floats 20 may travel along the same route.Figure 5 They sail along the routes indicated by (a) and (b), respectively. Furthermore, it can be said that... Figure 5 The routes shown in (a) and (b) are routes with the same starting point and ending point, and are routes that can be drawn without passing through a portion of the route that is part of the route more than twice (so-called routes drawn in one stroke). In this case, the location where the transport ship 10 recovers energy from the float 20 can be any location near the edge of the quadrilateral representing the sea area SA. However, considering the fuel cost of the transport ship 10, it is desirable for the transport ship 10 to recover energy from the float 20 at the location closest to the land in the sea area SA.

[0041] (Technical effect)

[0042] From the viewpoint of power generation efficiency, it is desirable for the multiple floats 20 forming a convoy to continuously navigate automatically without chaos. If we assume that the transport ship 10 enters the sea area SA to recover energy from the floats 20, the floats 20 may slow down as they try to avoid the transport ship 10. This could potentially reduce the power generation efficiency of the floats 20. In contrast, in this embodiment, the transport ship 10 recovers energy from the floats 20 near the end of the sea area SA (e.g., area CA). In this way, the transport ship 10 does not need to enter the sea area SA. In other words, the course of the floats 20 can be prevented from being affected by the transport ship 10. Therefore, the situation where the speed of the floats 20 is reduced due to the transport ship 10 can be suppressed. That is, the situation where the power generation efficiency of the floats 20 is reduced due to the transport ship 10 can be suppressed.

[0043] The inventive methods derived from the embodiments described above will be described below.

[0044] One aspect of the invention relates to an energy recovery method comprising the following steps: generating electricity by a float constituting a power generation system while it is automatically navigating, thereby accumulating energy in the float; and recovering energy from the float by an energy transport vessel near the end of the sea area where the float is automatically navigating.

[0045] Alternatively, the buoy may automatically navigate within the sea area along a track whose starting and ending points coincide, and which can be drawn without passing through a portion of the track that is part of the track more than twice.

[0046] Alternatively, in the process of the floating bodies accumulating energy, the multiple floating bodies forming the queue generate electricity while automatically navigating.

[0047] Alternatively, the floating body can be used for tethered wind power generation.

[0048] Alternatively, the floating body can be equipped with an underwater turbine generator.

[0049] This invention is not limited to the embodiments described above. Appropriate modifications can be made without departing from the spirit or idea of ​​the invention as read in whole from the claims and the specification, and the energy recovery method with such modifications is also included within the technical scope of this invention.

[0050] Symbol Explanation

[0051] 10… Transport ship; 20… Floating body.

Claims

1. An energy recovery method, comprising: The process of generating electricity by a floating body that constitutes a power generation system while automatically navigating, thereby accumulating energy in the floating body; Near the end of the sea area where the floating body navigates automatically, an energy transport vessel recovers energy from the floating body.

2. The energy recovery method as described in claim 1, wherein, The buoy automatically navigates within the sea area along a track whose starting and ending points coincide, and which can be drawn without passing through a portion of the track that is part of the track more than twice.

3. The energy recovery method as described in claim 1, wherein, In the process of storing energy on the floating bodies, the multiple floating bodies forming a queue generate electricity while automatically navigating.

4. The energy recovery method as described in claim 1, wherein, The floating body is used for tethered wind power generation.

5. The energy recovery method as described in claim 1, wherein, The floating body has an underwater turbine generator.

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