Energy recovery method

Abstract

To suppress influence on a sea route of a ship generating power.SOLUTION: An energy recovery method includes a step in which a floating body constituting a power generation system stores energy by performing power generation while automatically navigating, and a step in which an energy transport ship recovers energy from the floating body in the vicinity of an end of a sea area where the floating body automatically navigates.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to the technical field of energy recovery methods for recovering energy generated offshore. [Background technology]

[0002] As an energy generation method using this type of method, wind power generation using kites moored to a ship has been proposed (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 094987 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, wind power generation using kites moored to a ship is often carried out in ocean areas relatively far from land. This makes it difficult to transmit power from the ship using a power cable. Furthermore, from the standpoint of availability, it is desirable for the ship mooring the kites to be used exclusively for power generation. For these reasons, it is desirable for the electricity (i.e., energy) generated by wind power generation to be transported to land by a ship other than the ship mooring the kites. In this case, there is a technical problem in that if other ships approach the ship mooring the kites, it may affect the route of the ship mooring the kites.

[0005] The present invention has been made in consideration of the above problems, and an object of the present invention is to provide an energy recovery method that can reduce the impact on the route of a ship generating electricity. [Means for solving the problem]

[0006] An energy recovery method according to one aspect of the present invention includes a step of storing energy in a float constituting a power generation system by generating electricity while the float navigates automatically, and a step of an energy transport ship recovering energy from the float near the edge of the sea area in which the float navigates automatically. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a conceptual diagram illustrating a concept of a power generation system according to an embodiment. [Figure 2] FIG. 1 is a diagram illustrating an example of a floating body according to an embodiment. [Figure 3] FIG. 2 is a diagram showing an example of a movement path of a floating body according to an embodiment. [Figure 4] 4 is a flowchart showing the operation of a transport ship and a floating body according to an embodiment. [Figure 5] FIG. 10 is a diagram showing a modified example of the movement path of the floating body according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of the energy recovery method will be described with reference to FIGS.

[0009] (Power generation system configuration) The configuration of the power generation system will be described with reference to Figures 1 to 3. In the power generation system according to this embodiment, power is generated using multiple floating bodies 20 that do not require mooring in an ocean area SA that is relatively far from land. The multiple floating bodies 20 navigate automatically within the ocean area SA. That is, each of the multiple floating bodies 20 generates power while automatically navigating within the ocean area SA. For example, the ocean area SA may be an ocean area 50 kilometers away from land.

[0010] The floating body 20 will be described with reference to FIG. 2. In FIG. 2(a), a floating body 20a as the floating body 20 includes a sail 21 and kites 22. The floating body 20a may use wind energy received by the sail 21 as propulsion. In the floating body 20a, as the kites 22 rise, a tether mooring the kites 22 is let out from a winch (not shown). The tether let-out operation rotates the winch drum. The rotation of the drum rotates a generator (not shown), generating electricity. When the tether is let out to a predetermined length or after a predetermined time has elapsed, the motor of the winch rotates the winch drum in a direction to reel in the tether. As a result, the kites 22 descend due to the reeling of the tether. In the floating body 20a, power is generated by repeatedly letting out and reeling in the tether. In other words, the floating body 20a performs tether-type wind power generation. The floating body 20a may also use wind energy received by the kites 22 as a propulsive force.

[0011] 2(b), a floating body 20b as the floating body 20 includes a sail 21 and an underwater turbine generator 23. The floating body 20b may use wind energy received by the sail 21 as propulsion force. As the floating body 20b moves, seawater flows into the underwater turbine generator 23. As a result, electricity is generated by the underwater turbine generator 23.

[0012] The floating body 20a may be equipped with an underwater turbine generator 23. That is, the floating body 20a may perform power generation using the underwater turbine generator 23 in addition to tethered wind power generation. Similarly, the floating body 20b may be equipped with kites 22. That is, the floating body 20b may perform power generation using the underwater turbine generator 23 in addition to tethered wind power generation.

[0013] The float 20 may store the electricity obtained by power generation in a storage battery (e.g., a lithium-ion battery). That is, the float 20 may store electrical energy as electrical energy. The float 20 may generate hydrogen by electrolyzing water using the electricity obtained by power generation. The float 20 may store the generated hydrogen. That is, the float 20 may store electrical energy as hydrogen energy. Note that hydrogen may be stored in a compressed state, or may be stored by being absorbed in a hydrogen storage alloy.

[0014] In the following description, it is assumed that the floating body 20 generates hydrogen using the electricity obtained by power generation and compresses and stores the generated hydrogen.

[0015] Returning to FIG. 1 , the transport ship 10 sails between a port P located on land and a sea area SA. For example, the transport ship 10 retrieves a hydrogen tank in which hydrogen is compressed and stored from a floating body 20 near the edge of the sea area SA (e.g., area CA). At this time, the transport ship 10 hands over an empty hydrogen tank to the floating body 20. The transport ship 10 then transports the hydrogen tank retrieved from the floating body 20 to port P. At port P, the transport ship 10 unloads the hydrogen tank retrieved from the floating body 20 and loads an empty hydrogen tank. The transport ship 10 then heads for the sea area SA. Here, "near the edge of the sea area SA" may mean an area where the transport ship 10 and the floating body 20 can meet up, and where the route of the floating body 20 is not affected by the transport ship 10.

[0016] In this way, in this power generation system, offshore power generation is performed by the plurality of floating bodies 20, and energy transportation is performed by the transport ship 10.

[0017] Next, an example of the number of floating bodies 20 will be described. For example, if the power generation scale of the power generation system is 5 GW (gigawatts) and the rated output of one floating body 20 is 1 MW (megawatts), the power generation system will include 5,000 floating bodies 20.

[0018] As shown in FIG. 1, multiple floating bodies 20 form a formation. The multiple floating bodies 20 then automatically navigate a route set within the sea area SA. Here, by forming a formation of multiple floating bodies 20, interference between the floating bodies 20 can be suppressed. As a result, it is possible to suppress a decrease in the power generation efficiency of one floating body 20 due to the other floating bodies 20. Note that the "route" may also be referred to as a "travel path" or "trajectory," for example. For example, the transport ship 10 retrieves a hydrogen tank from a floating body 20 in the area CA. From the viewpoint of energy efficiency, it is desirable that the hydrogen tank be full when the floating body 20 arrives in the area CA.

[0019] 1, the floating body 20 may travel from the left side of the sea area SA along side S1 (i.e., the top side) of the sea area SA to the vicinity of side S2 (i.e., the right side) of the sea area SA, turn around near side S2, and travel back along side S1 to the left side. In this case, the length L1 of side S1 such that the hydrogen tank is full when the floating body 20 reaches the left side of the sea area SA (in other words, area CA) may be determined as follows.

[0020] As a premise, the length of one side of the rectangular occupied area required for a float 20 with a rated output of 1 MW to navigate without interfering with other adjacent floats 20 is assumed to be 700 meters. Furthermore, the speed of the float 20 is assumed to be 5 m / s, the time it takes for an empty hydrogen tank to become full is assumed to be 24 hours, and the float 20 will make four laps around the route set within the sea area SA in 24 hours. The length of the straight portion of the route of the float 20 along side S1 is assumed to be L_line, and the length of the portion of the route along which the float 20 turns is assumed to be L_terminal. In this case, the length of one lap of the route of the float 20 is "2 × L_line + 2 × L_terminal." Here, where the length of one side of the occupied area is assumed to be L_float, L_terminal is expressed as "L_terminal = L_float × 2 × Pi / 2." In other words, "L_terminal = L_float × Pi."

[0021] As described above, the floating body 20, with a speed of 5 m / s, makes four laps around the route in 24 hours. If the speed of the floating body 20 is V_fleet, the sailing time is T, and the number of laps around the route is N, then the following formula is established: "V_fleet × T = N × (2 × L_line + 2 × L_terminal)". From this formula, L_line is calculated as 51,802 meters. The length in the direction in which side S1 of the part of the floating body 20 that rotates is extended is 1,400 meters. In this case, the length L1 of side S1 of the sea area SA is approximately 53 kilometers.

[0022] When multiple floating bodies 20 navigate the above-mentioned route in a formation, the number of floating bodies 20 that can navigate along one route, N_float_inline, is expressed as "N_float_inline≦2×L_line / L_float". Here, N_float_inline = 148. Assume that multiple floating bodies 20 that can navigate along one route form one formation. In this case, 34 formations are required to accommodate 5,000 floating bodies 20 within the sea area SA. If the number of formations (here, 34) is N_fleet, the length L2 of side S2 of sea area SA can be expressed as "L2 = 2×N_fleet×L_float". Here, the length L2 of side S2 is approximately 48 kilometers.

[0023] Note that the above-mentioned power generation scale, rated output of one floating body 20, speed of the floating body 20, time until the hydrogen tank is filled up, number of times the floating body 20 circles the route, and length of one side of the rectangular occupied area required for the floating body 20 to navigate without interfering with other adjacent floating bodies 20 are merely examples and are not limited to these. Therefore, the size of the sea area SA is also not limited to the above-mentioned sizes. Note that while FIG. 1 shows a rectangular sea area SA, the shape of the sea area SA does not have to be rectangular. Note that the position of the sea area SA does not have to be fixed. For example, the position of the sea area SA may be changed depending on the route of the floating body 20.

[0024] Next, an example of the route of the floating body 20 will be described with reference to Figure 3. When wind energy received by the sail is used as propulsion force, the speed of the floating body 20 is greatest when the wind hits the floating body 20 directly beside the traveling direction of the floating body 20. For this reason, as shown in Figures 3(a) and 3(b), the route of the floating body 20 may be set so that the period during which the floating body 20 moves in a direction approximately perpendicular to the wind direction is long. Note that the route of the floating body 20 may be set taking into consideration, for example, wind speed, ocean current direction and ocean current speed in addition to wind direction.

[0025] Research by the present inventors has revealed that when the floating body 20 performs tether-type wind power generation, the net amount of power generation improves if the floating body 20 moves upwind when letting out the tether (i.e., during power generation) and moves downwind when reeling in the tether. For this reason, when the floating body 20 performs tether-type wind power generation, it is desirable for the floating body 20 to automatically navigate along the route shown in Figure 3(a).

[0026] When the floating body 20 generates power using an underwater turbine generator, it is desirable for the floating body 20 to automatically navigate along the route shown in Figure 3(b), because this is expected to maximize the speed of the floating body 20. Note that the floating body 20 may also automatically navigate along the route shown in Figure 3(c).

[0027] (Operation of the transport ship 10 and the floating body 20) Next, the operation of the transport ship 10 and the floating body 20 in the power generation system will be explained with reference to the flowchart in Figure 4. In Figure 4, the transport ship 10 heads from port P to an energy recovery point (e.g., area CA) (step S111). The energy recovery point can be said to be near the edge of sea area SA. At this time, the floating body 20 generates power while automatically navigating within sea area SA and stores the energy (step S121). Note that the floating body 20 may store electrical energy or hydrogen energy as the energy obtained by power generation.

[0028] When the transport ship 10 reaches the energy recovery point and the transport ship 10 and the floating body 20 join, the floating body 20 transfers energy to the transport ship 10 (step S122), and the transport ship 10 recovers energy from the floating body 20 (step S112). For example, the transport ship 10 may recover a hydrogen tank in which hydrogen is compressed and stored from the floating body 20, and deliver an empty hydrogen tank to the floating body 20. For example, the transport ship 10 may recover a charged storage battery in which electrical energy is stored from the floating body 20, and deliver an uncharged storage battery to the floating body 20.

[0029] After the processing of step S122, the floating body 20 performs the processing of step S121. That is, the floating body 20 generates power while automatically navigating within the sea area SA. After the processing of step S112, the transport ship 10 heads from the energy recovery point to port P (step S113). After the transport ship 10 arrives at port P, the transport ship 10 exchanges energy storage (step S114). For example, if the transport ship 10 recovers a hydrogen tank in which hydrogen is compressed and stored from the floating body 20, the transport ship 10 may unload the hydrogen tank and load an empty hydrogen tank. For example, if the transport ship 10 recovers a charged storage battery from the floating body 20, the transport ship may unload the charged storage battery and load an uncharged storage battery. Thereafter, the transport ship 10 performs the processing of step S111. That is, the transport ship 10 heads from port P to the energy recovery point.

[0030] The routes of the floating bodies 20 within the sea area SA may not be different between the route traveled by one group of floating bodies 20 and the route traveled by another group of floating bodies 20, as shown in FIG. 1 . For example, all of the floating bodies 20 may travel along a single route shown in each of FIGS. 5(a) and 5(b). The routes shown in FIGS. 5(a) and 5(b) are routes whose starting and ending points coincide, and can be described as routes that can be drawn without passing through a partial route that is a part of the route more than once (so-called unicursal routes). In this case, the point at which the transport ship 10 recovers energy from the floating bodies 20 may be any point near the sides of the rectangle representing the sea area SA. However, in consideration of the fuel costs of the transport ship 10, it is desirable for the transport ship 10 to recover energy from the floating bodies 20 at a point in the sea area SA that is closest to land.

[0031] (Technical Effects) From the viewpoint of power generation efficiency, it is desirable that the multiple floating bodies 20 in formation continue to navigate automatically without disruption. If the transport ship 10 enters the sea area SA to recover energy from the floating bodies 20, the speed of the floating bodies 20 may decrease as the floating bodies 20 avoid the transport ship 10. This may result in a decrease in the power generation efficiency of the floating bodies 20. In contrast, in this embodiment, the transport ship 10 recovers energy from the floating bodies 20 near the edge of the sea area SA (for example, area CA). In this way, it is not necessary for the transport ship 10 to enter the sea area SA. In other words, it is possible to avoid the route of the floating bodies 20 being affected by the transport ship 10. Therefore, it is possible to prevent a decrease in the speed of the floating bodies 20 due to the transport ship 10. In other words, it is possible to prevent a decrease in the power generation efficiency of the floating bodies 20 due to the transport ship 10.

[0032] Aspects of the invention derived from the above-described embodiments will be described below.

[0033] An energy recovery method according to one aspect of the invention includes the steps of: storing energy in a float constituting a power generation system by generating electricity while the float navigates automatically; and recovering energy from the float by an energy transport vessel near the edge of the sea area in which the float navigates automatically.

[0034] The floating body may automatically navigate within the sea area along a trajectory whose starting point and ending point coincide and which can be traced without passing through a partial trajectory that is a part of the trajectory more than once.

[0035] In the step of storing energy, the floating bodies forming the formation may generate power while automatically sailing.

[0036] The floating body may perform tethered wind power generation. The floating body may include an underwater turbine generator.

[0037] The present invention is not limited to the above-described embodiments, but can be modified as appropriate within the scope of the claims and the gist or idea of ​​the invention as can be read from the entire specification, and energy recovery methods involving such modifications are also included in the technical scope of the present invention. [Explanation of symbols]

[0038] 10...Transport ship, 20...Floating body

Claims

1. a step of storing energy in a float constituting the power generation system by generating power while automatically sailing; a step of recovering energy from the floating body by an energy transport ship near an edge of the sea area in which the floating body automatically navigates; An energy recovery method comprising:

2. The floating body automatically navigates within the sea area along a trajectory in which the starting point and the end point coincide with each other and which can be traced without passing through a partial trajectory that is a part of the trajectory more than twice. The energy recovery method according to claim 1 .

3. In the step of storing energy in the floats, the plurality of floats forming the formation generate power while automatically sailing. The energy recovery method according to claim 1 .

4. The floating body performs tethered wind power generation. The energy recovery method according to claim 1 .

5. The floating body has an underwater turbine generator. The energy recovery method according to claim 1 .

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