ENERGY COLLECTING METHOD

Abstract

An energy collecting method includes: a step in which a floating body, which constitutes a power generation system, stores energy by the floating body generating power while automatically sailing; and a step in which an energy transport ship collects energy from the floating body near an edge of a sea area in which the floating body automatically sails.

Claims

1. An energy collecting method including: a step in which a floating body, which constitutes a power generation system, stores energy by the floating body generating power while automatically sailing; and a step in which an energy transport ship collects energy from the floating body near an edge of a sea area in which the floating body automatically sails.

2. The energy collecting method according to claim 1, wherein the floating body automatically sails in the sea area along a trajectory that has a starting point and an end point that coincide, and that can be drawn without passing through a partial trajectory that is a part of the trajectory more than once.

3. The energy collecting method according to claim 1, wherein in the step in which the floating body stores energy, a plurality of floating bodies, that constitute a formation, generate power while automatically sailing.

4. The energy collecting method according to claim 1, wherein the floating body performs tether-type wind power generation.

5. The energy collecting method according to claim 1, wherein the floating body has an underwater turbine generator.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 is a conceptual diagram showing concept of a power generation system of an embodiment.

[0008] FIGS. 2A and 2B are diagrams showing an example of a floating body of the embodiment.

[0009] FIGS. 3A-3C are examples of a movement path of the floating body of the embodiment.

[0010] FIG. 4 is a flowchart showing operation of a transport ship and the floating body of the embodiment.

[0011] FIGS. 5A and 5B are examples of a modified example of the movement path of the floating body of the embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0012] An embodiment of an energy collecting method is explained with reference to FIGS. 1 to 5B.

(Configuration of the Power Generation System)

[0013] Configuration of a power generation system is explained with reference to FIGS. 1 to 3C. In the power generation system of this embodiment, power generation is carried out using a plurality of floating bodies 20 that do not require mooring in a sea area SA, which is relatively far from land. The plurality of floating bodies 20 automatically sail within the sea area SA. In other words, each of the plurality of floating bodies 20 generates power while automatically sailing within the sea area SA. For example, the sea area SA may be a sea area 50 kilometers away from land.

[0014] The floating body 20 is explained with reference to FIGS. 2A and 2 B. In FIG. 2A, the floating body 20a as a floating body 20 is provided with a sail 21 and a kite 22. The floating body 20a may use the wind energy received by the sail 21 as propulsion. In the floating body 20a, the tether that moors the kite 22 is unrolled from a winch (not shown) as the kite 22 rises. The drum of the winch rotates due to the operation of the tether being reeled out. Power generation is carried out by the generator (not shown in the figure) rotating in conjunction with the rotation of the drum. After the tether has been reeled out to a predetermined length or a predetermined amount of time has elapsed, the drum of the winch is rotated in the direction of winding up the tether by the motor of the winch. As a result, the kite 22 descends due to the operation of the tether being reeled in. On the floating body 20a, power generation is carried out by repeating the process of extending and retracting the tether. In other words, tether-type wind power generation is carried out on the floating body 20a. In addition, the floating body 20a may also use the wind energy received by the kite 22 as propulsion.

[0015] In FIG. 2B, a floating body 20b has a sail 21 and an underwater turbine generator 23. The floating body 20b may use the wind energy received by the sail 21 as propulsion. As the floating body 20b moves, seawater flows into the underwater turbine generator 23. As a result, power generation is carried out by the underwater turbine generator 23.

[0016] In addition, the floating body 20a may be equipped with an underwater turbine generator 23. In other words, the floating body 20a may generate power using the underwater turbine generator 23 in addition to tether-type wind power generation. Similarly, the floating body 20b may be equipped with a kite 22. In other words, the floating body 20b may generate power using the underwater turbine generator 23 in addition to tether-type wind power generation.

[0017] The floating body 20 may store the power generated in a storage battery (e.g., a lithium-ion battery). In other words, the floating body 20 may store electrical energy as electrical energy. The floating body 20 may generate hydrogen by electrolyzing water using the power generated. The floating body 20 may store the generated hydrogen. In other words, the floating body 20 may store electrical energy as hydrogen energy. In addition, hydrogen may be stored by compression or by absorption into a hydrogen storage alloy.

[0018] In the following, the floating body 20 is assumed to generate hydrogen using the power obtained from power generation and to store the generated hydrogen by compression.

[0019] Returning to FIG. 1, a transport ship 10 sails between the port P on land and the sea area SA. For example, the transport ship 10 retrieves a hydrogen tank that has compressed hydrogen stored in it from the floating body 20 near the edge of the sea area SA (e.g., in the area CA). At this time, the transport ship 10 hands over an empty hydrogen tank to the floating body 20. After that, the transport ship 10 transports the hydrogen tank retrieved from the floating body 20 to the port P. At Port P, the transport ship 10 unloads the hydrogen tanks recovered from the floating body 20 and loads empty hydrogen tanks. The transport ship 10 then heads for the sea area SA. Here, the area near the edge of the sea area SA may mean an area where the transport ship 10 and the floating body 20 can meet and an area where the route of the floating body 20 is not affected due to the transport ship 10.

[0020] In this way, in the power generation system, offshore power generation is carried out using plurality of floating bodies 20, and energy transport is carried out using transport ships 10.

[0021] Next, we will explain an example of the number of floating bodies 20. 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 have 5000 floating bodies 20.

[0022] As shown in FIG. 1, the plurality of floating bodies 20 form a convoy. The plurality of floating bodies 20 automatically sail along a route set in the sea area SA. By having the plurality of floating bodies 20 form a convoy, interference between the floating body 20 can be suppressed. As a result, the power generation efficiency of one floating body 20 can be suppressed due to other floating body 20. In addition, the route may be referred to as a movement path or orbit, for example. For example, the transport ship 10 recovers the hydrogen tank from the floating body 20 in area CA. From the perspective of energy efficiency, it is desirable for the hydrogen tank to be full when the floating body 20 reaches area CA.

[0023] For example, in FIG. 1, the floating body 20 may sail from the left side of the sea area SA along the side S1 (i.e., the top side) of the sea area SA to the vicinity of the side S2 (i.e., the right side) of the sea area SA, and then turn around in the vicinity of the side S2 and sail along the 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 (in other words, the area CA) of the sea area SA may be determined as follows.

[0024] As a premise, the length of one side of the rectangular area of occupation required for a floating body 20 with a rated output of 1 MW to sail without interfering with other adjacent floating bodies 20 shall be 700 meters. In addition, the speed of the floating body 20 shall be 5 m/s, the time required for an empty hydrogen tank to be filled to capacity shall be 24 hours, and the floating body 20 shall make four laps of the route set in the sea area SA in 24 hours. The length of the straight section of the route of the floating body 20 along side S1 is L_line, and the length of the section of the route where the floating body 20 turns is L_terminal. In this case, the length of one round of the route of the floating body 20 is 2L_line+2L_terminal. Here, L_terminal is assumed to be expressed as L_terminal=L_float2/2 when L_float is the length of one side of the above-mentioned occupied area. In other words, L_terminal=L_float.

[0025] As mentioned above, the floating body 20, which has a speed of 5 m/s, completes four laps of the route in 24 hours. If we define the speed of the floating body 20 as V_fleet, the navigation time as T, and the number of laps of the route as N, then the following formula holds: V_fleetT=N(2L_line+2L_terminal). From this formula, L_line is 51802 meters. The length of the direction in which the side S1 of the area where the floating body 20 turns is extended is 1400 meters. In this case, the length L1 of the side S1 of the sea area SA is about 53 kilometers.

[0026] When plurality of floating bodies 20 are navigating in a line along the above-mentioned route, the number of floating bodies 20 that can sail along a single route, N_float_in_line, is expressed as N_float_in_line2L_line/L_float. In this case, N_float_in_line=148. It is assumed that plurality of floating bodys 20 that can sail along a single route form a single formation. In this case, 34 formations are required to accommodate 5000 floating bodies 20 within the sea area SA. If the number of formations (in this case, 34) is represented by N_fleet, the length L2 of the side S2 of the sea area SA can be expressed as L2=2N_fleetL_float. In this case, the length of side S2, L2, is approximately 48 kilometers.

[0027] The above-mentioned power generation scale, rated output of one floating body 20, speed of floating body 20, time until hydrogen tank is full, number of times floating body 20 circles the route, and length of one side of the occupied area of the rectangle required for floating body 20 to sail without interfering with other adjacent floating body 20 are examples, and are not limited to these values. For this reason, the size of the sea area SA is not limited to the size described above. In addition, although the sea area SA is shown as a square in FIG. 1, the shape of the sea area SA does not have to be a square. In addition, 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 in accordance with the route of the floating body 20.

[0028] Next, we will explain an example of the route of the floating body 20, referring to FIGS. 3A-3C. When using the wind energy received by the sail as propulsion, the speed of the floating body 20 is greatest when the wind is received directly from the side in the direction of travel of the floating body 20. For this reason, as shown in FIGS. 3A and 3B, the route of the floating body 20 may be set so that the period during which the floating body 20 travels in a direction almost perpendicular to the wind direction is long. In addition to the wind direction, the route of the floating body 20 may be set by taking into account, for example, the wind speed, the direction of the ocean current, and the ocean current speed.

[0029] In the case of tether-type wind power generation, the inventor's research has shown that the net amount of power generated can be increased if the floating body 20 moves upwind when the tether is deployed (i.e. when power is being generated) and moves downwind when the tether is reeled in. Therefore, when the floating body 20 is performing tether-type wind power generation, it is desirable for the floating body 20 to automatically sail along the route shown in FIG. 3A.

[0030] When the floating body 20 is generating power using an underwater turbine generator, it is desirable for the floating body 20 to automatically sail along the route shown in FIG. 3B. This is because the floating body 20's speed is expected to be the greatest. The floating body 20 may also automatically sail along the route shown in FIG. 3C.

(Operation of the Transport Ship 10 and the Floating Body 20)

[0031] Next, we will explain the operation of the transport ship 10 and the floating body 20 in the power generation system in question, referring to the flowchart in FIG. 4. In FIG. 4, the transport ship 10 heads from port P to the energy collect point (e.g., area CA) (step S111). The energy collect point can be said to be near the edge of area SA. At this time, the floating body 20 generates power and stores energy while automatically navigating within area SA (step S121). In addition, the floating body 20 may store electrical energy or hydrogen energy as the energy obtained from power generation.

[0032] When the transport ship 10 arrives at the energy collect point and the transport ship 10 and the floating body 20 merge, 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 from the floating body 20 in which hydrogen is compressed and stored, and deliver an empty hydrogen tank to the floating body 20. For example, the transport ship 10 may recover a rechargeable battery in which electrical energy is stored from the floating body 20, and deliver an uncharged battery to the floating body 20.

[0033] After processing in Step S122, the floating body 20 performs the processing in Step S121. In other words, the floating body 20 generates electricity while automatically navigating within the sea area SA. After processing in Step S112, the transport ship 10 heads for the port P from the energy collect point (Step S113). After the transport ship 10 arrives at the port P, the transport ship 10 exchanges the energy storage (Step S114). For example, if the transport ship 10 retrieves a hydrogen tank from the floating body 20 that has compressed hydrogen stored in it, the transport ship 10 may unload the hydrogen tank and load an empty hydrogen tank. For example, if the transport ship 10 retrieves a rechargeable battery from the floating body 20, the transport ship may unload the rechargeable battery and load a non-rechargeable battery. After that, the transport ship 10 performs the processing of step S111. In other words, the transport ship 10 heads from port P to the energy collect point.

[0034] Furthermore, the route of the floating bodies 20 in the sea area SA does not have to be different from the route where a group of floating bodies 20 sails and the route where another group of floating bodies 20 sails, as shown in FIG. 1. For example, all of the plurality of floating bodies 20 may sail along the single route shown in each of FIGS. 5A and 5B. The routes shown in FIGS. 5A and 5B are routes where the starting point and ending point coincide, and can be said to be routes that can be drawn without passing through the partial routes that are part of the route (so-called one-stroke routes) more than once. In this case, the point where the transport ship 10 recovers energy from the floating body 20 can be any point near the edge of the rectangle indicating the sea area SA. However, in view of the fuel costs of the transport ship 10, it is desirable for the transport ship 10 to recover energy from the floating body 20 at the point closest to the land in the sea area SA.

Technical Effect

[0035] From the perspective of power generation efficiency, it is desirable for plurality of floating bodies 20 in a convoy to continue to sail automatically without becoming disrupted. If a transport ship 10 enters the sea area SA in order to recover energy from floating bodies 20, the speed of the floating bodies 20 may decrease due to the floating bodies 20 avoiding 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 body 20 in the vicinity of the edge of the sea area SA (e.g., in the area CA). In this way, there is no need for the transport ship 10 to enter the sea area SA. In other words, it is possible to avoid the transport ship 10 affecting the route of the floating body 20. As a result, it is possible to suppress the reduction in the speed of the floating body 20 caused by the transport ship 10. In other words, it is possible to prevent the power generation efficiency of the floating body 20 from decreasing due to the transport ship 10.

[0036] Aspects of the invention derived from the above-described embodiment are explained below.

[0037] One aspect of an energy collecting method of the invention is an energy collecting method including: a step in which a floating body, which constitutes a power generation system, stores energy by the floating body generating power while automatically sailing; and a step in which an energy transport ship collects energy from the floating body near an edge of a sea area in which the floating body automatically sails.

[0038] The floating body may automatically sail in the sea area along a trajectory that has a starting point and an end point that coincide, and that can be drawn without passing through a partial trajectory that is a part of the trajectory more than once.

[0039] In the step in which the floating body may store energy, a plurality of floating bodies, that constitute a formation, generate power while automatically sailing.

[0040] The floating body may perform tether-type wind power generation. The floating body may have an underwater turbine generator.

[0041] This invention is not limited to the above-mentioned embodiment, but can be changed as appropriate within the scope that does not contradict the gist or idea of the invention that can be read from the claims and the entire specification, and energy collect methods that involve such changes are also included in the technical scope of this invention.