JP5190716B2 - Wave power generation method - Google Patents

Description

The present invention relates to a wave power generation method using ocean wave energy.

Power generation using natural energy is a power generation method that does not rely on fossil fuels, and it has great expectations such as prevention of global warming, measures against uneven distribution of resources, and effects of economic levitation.
However, wind power generation and solar power generation, which are the mainstream, are not always blessed with an installation environment in the region. For example, in Japan, wind power generation is too strong due to the influence of typhoons, and the wind direction at the peak is not constant.
Regarding solar power generation, geographical conditions such as Japan do not have a vast desert, etc., the amount of sunlight is small, and it is difficult to realize a large-scale solar power generation system.

On the other hand, regions such as Japan are surrounded by the ocean and are blessed with an installation environment for using ocean energy. Ocean energy has a large amount of energy and has great utility value.
As for power generation using ocean energy, there are ocean current power generation, tidal current power generation, temperature difference power generation, etc., but wave energy has a large amount of energy and exists in a wide range of sea areas, and this commercialization is highly desired.
However, the conventional wave power generation method has not been sufficient for practical use on a large-scale commercial level comparable to wind power generation and solar power generation.

In order to promote practical application, it is essential to increase the size and increase the efficiency from the technical aspect and to reduce the construction cost and power generation cost from the cost aspect.

There are the following examples of wave power generation methods to date including experiments and proposals.

One is classified as an oscillating water column type, which transmits the vertical motion of waves to the pressure in the air chamber and drives the turbine by this air pressure. The problem with this method is that it is difficult to increase the size and the equipment cost is high.

The other is classified as a movable object type, in which an object is moved by the motion of a wave, a high-pressure pump is driven by this motion, and a turbine is driven by the high-pressure fluid obtained thereby. The problems with this method are that it is difficult to increase the size and the equipment cost is high.

The other is classified as an overtopping type, in which seawater is guided to a reservoir located higher than the surface of the water by wave motion, and a turbine is turned to generate electricity using the difference in elevation from the sea level. The problems with this method are that it is difficult to increase the size and the equipment cost is high.

Other methods include wave power generation using artificial muscles, direct drive wave power generation using linear generators, gyro wave power generation, wave power generation using floating kites, and tsube type wave power generation. The problem with this method is that the practical application technology is still immature.

None of the above methods is sufficient to achieve large-scale large output, high efficiency, construction cost reduction, and power generation cost reduction on a commercial level.

Shuichi Nagata “Trends in Wave Power Generation” Lecture on the International Forum on Ocean Energy Resources (June 25, 2009)

Ocean Engineering Technical Committee, “21st Century Ocean Energy Development Technology”, Sankaido 2006

NEDO Overseas Report No.1044, “Latest Trends in Tidal and Wave Power Projects in Europe and America” May 2009

Port Technology Research Material No. 654, 1989, Shigeo Takahashi “Characteristics of Wave Power and Wave Power Generation Around Japan”

The problem to be solved by the invention is to provide an efficient wave power generation system with large capacity and high efficiency.

Specifically, it is possible to increase the receiving cross-sectional area or receiving line length for waves, to realize a method that can cope with wave flows that constantly change in the direction of movement, wavelength, and shape, and to improve the efficiency of energy absorption. Is to realize.

Also, it is to provide a system with low construction costs including equipment itself, maintenance costs, and power generation costs. For this purpose, it is necessary to realize a method that is simple in structure, easy to manufacture, transport, and install. The aim is to simplify the installation offshore where the installation area is large.

In the present invention, a rotating disk equipped with a large number of passively variable pitch receiving vanes is installed in the horizontal direction near the water surface, and it is rotated by obtaining a propulsive force from wave motion as an energy source, and absorbing energy from this rotation. Doing is the main feature.

The following effects are produced by the present invention.

Equipped with multiple passive variable pitch receiving vanes in segmented positions, for each wave segment that constantly changes due to wave motion direction, wavelength, period, shape and other vane effects It is possible to cope with an independent and optimum form, and the entire apparatus can finely and optimally cope with a complicated movement of a wide range of waves.

In addition, by adopting a passive variable pitch type for each receiving vane, even if the direction of the waves changes with time and position, the rotation propulsion direction of the disk by the waves is the same, and the rotational movement in the same direction is performed. Stable operation can be realized.

In addition, since the wave energy absorption mode of the passive variable pitch blade is not a resistance type that disturbs the wave flow, the energy of the wave is not wasted and the energy absorption efficiency is high.

In addition, since the structure of the part that receives waves of the entire system is horizontal and thin, the vertical area is small, and it is affected by typhoons and storms that blow the sea surface horizontally, tides that flow horizontally, and ocean currents. There are few things.

In addition, a wide rotating disk has a simple structure, can give an appropriate buoyancy, and does not need to be a strong structure to resist gravity, and can be easily increased in size.

In addition, since the entire apparatus can be a floating type rather than a bottomed type, the degree of freedom in selecting the installation location is great, and transportation and installation work are easy. In particular, it can be installed offshore where the wave power is large and a large installation area can be taken. Therefore, the system can be scaled up, the cost of obtaining the installation location can be reduced, the problem of inhabitants can be avoided, and the problem of fishing can be avoided.

Moreover, since the rotating disk is almost under water, it does not cause noise problems such as wind power generation, bird collision death problems, and landscape problems. Since the rotating speed of the rotating disk is not as high as that of wind power wings, it is unlikely to cause a collision death problem for marine animals.

FIG. 1 is an overall view showing a first embodiment. FIG. 2 is a side view showing the first embodiment. FIG. 3 is a top view showing the first embodiment. FIG. 4 is an enlarged view of a part of the rotating disk of the first embodiment. FIG. 5 is an external view of a receiving blade of the first embodiment. FIG. 6 is an explanatory view showing the pitch change of the receiving blade. FIG. 7 is an explanatory view showing a force vector applied to the receiving blade. FIG. 8 is an explanatory diagram for showing numerical examination. FIG. 9 is an external view of a receiving blade of the second embodiment. FIG. 10 is an external view of a turntable of the third embodiment. FIG. 11 is an overall view showing a fourth embodiment. FIG. 12 is a side view showing the fourth embodiment. FIG. 13 is an enlarged view of a part of the rotating disk of the fourth embodiment. FIG. 14 is an overall view showing a fifth embodiment. FIG. 15 is an overall view showing a sixth embodiment. FIG. 16 is an explanatory view showing the operation of the sixth embodiment. FIG. 17 is an explanatory view showing the operation of the sixth embodiment. FIG. 18 is an explanatory view showing the operation of the sixth embodiment.

A rotating disk equipped with a large number of passively variable pitch receiving vanes described in the means for solving the above problems is installed in the horizontal direction near the water surface, and it is rotated by obtaining propulsive force from wave motion as an energy source. Examples of a method for absorbing energy from this rotation are as follows.

FIG. 1 is an overall view showing an embodiment of the first embodiment. In FIG. 1, the entire structure has two rotating disks 11 and 12 that rotate in opposite directions by the movement of waves, and each rotating disk is divided into an angular direction and a radial direction, and a number of receiving currents arranged concentrically. The blades 3 are attached, and each blade 3 obtains a propulsive force by the water current of the waves and rotates the rotating disk. The shaft structure 5 of the rotating disk is supported by the support structure 2. The shaft structure 5 has a rotating part or rotor 51 and a fixed part or stator 52, and the rotor is driven by a rotating disk to rotate. The stator is fixed by the support structure 2, does not rotate, and supports a stable power generation operation. The support structure 2 is anchored to the sea floor by an anchor 1.

The shaft structure 5 includes a speed increaser and a generator, and is driven by the rotation of the rotating disk to generate power.

The support structure has buoyancy, and this buoyancy can be adjusted to an appropriate amount by taking in and out air inside the support structure. As a result, the turntable is adjusted to the optimum vertical position for absorbing wave energy.

Also, when there is an excessively large wave during a storm, it can be lowered to a depth that is less affected by the wave.
Furthermore, it can be raised to a height that is easy to work during construction and maintenance.

Further, when the vehicle is towed from another place at the time of construction or the like, the height is adjusted to be easily pulled.
As an energy collecting method, it is possible to drive a high-pressure fluid generating pump instead of the generator and use the high-pressure fluid generated here as an energy source.

FIG. 2 is a side view showing the embodiment. As shown in the figure, the turntables 11 and 12 and each receiving blade are located directly below the water surface 6 and receive wave motion. The whole structure is a floating body and is anchored to the seabed 7 by the anchor 1.

In addition, when it is difficult to extend the anchor to the land when the installation site is deep offshore, there is a method of keeping the system in a fixed position by the fixed position control method described later.

FIG. 3 is a top view of the entire structure. When each rotating disk receives wave force and rotates in the opposite direction, a moment of force in the opposite direction, which is a reaction of each, is generated. The moment of each force is transmitted to the support structure 2 through the shaft structure 5, and each rotating disk is The rotational moment received by the motor is offset, and the support structure itself does not rotate and supports a stable power generation operation.

The anchor 1 also has a function of suppressing unnecessary rotational movement of the support structure.

Also, with this structure, the support structure does not need to be fixed to the seabed 7 and may be a floating body, which simplifies the structure and enables installation offshore.

When the water depth is shallow and the construction is simple and a simple structure with a single rotating disk is desirable, a method of fixing the fixed axis of the rotating disk to the seabed (bottomed) may be used. In this case, since the moment of force as a reaction when the rotating disk rotates is supported by a fixed shaft fixed to the seabed, the support structure 2 shown in FIG. 1 is unnecessary. Moreover, the rotating disk may be independent and the whole structure becomes simple.

The generated power or high-pressure fluid is sent to land for use by transmission lines or pipes installed along the seabed or in the sea. A method of keeping the strength by bundling the power transmission line or pipe with the anchor is also possible. If the depth of water is deep and it is difficult to install the anchor, it will be fixed with the transmission line or pipe to the land or to a shallow depth.

Furthermore, when the installation site is offshore and it is difficult to extend the transmission line or pipe to the land, there is also a method of charging a large-sized battery with the generated power and transporting it to a use site by a ship or the like. Alternatively, there is a method in which a substance that can store energy such as hydrogen is generated by the generated electric power and transported to a place of use by a ship or the like.

  FIG. 4 is an enlarged view of a part of the rotating disk. The frame 8 constituting the rotating disk is equipped with the receiving vanes 3.

FIG. 5 shows the appearance of one receiving blade 3. The receiving vane is composed of a fixed portion 31 and an elastic portion 32, and the fixed portion 31 is fixed to the frame 8 in FIG. The elastic portion 32 is integrated with the fixed portion 31, but the elastic portion 32 is deformed by receiving wave motion. That is, the pitch of the receiving vanes changes passively.

FIG. 6 is an explanatory diagram showing the deformation of the receiving blade due to the wave motion. When the water current of the wave goes from the bottom to the top in the figure, the receiving blade receives a force in the upward direction, the elastic part is deformed in the upward direction, and receives a force in the left direction of the figure by the water flow. When the water current direction of the wave is from the top to the bottom, the elastic portion is deformed downward and receives a force in the left direction of the figure by the water flow. That is, regardless of the direction of wave water flow, each receiving blade receives a driving force in the left direction of the figure and travels in the left direction. Since the actual receiving vanes are arranged concentrically on the rotating disk, the propulsive force received by the receiving vanes acts in the direction of rotating the rotating disk in the same direction.

FIG. 7 shows, as a vector, the force applied to the receiving blade by the wave water flow. The receiving wing receives a force Fo in a direction perpendicular to the wing surface due to water flow. Fo is decomposed into a direction Fb perpendicular to the rotating disk and a direction Fa horizontal. Fa is directed to the left in the figure regardless of the direction of water flow, and is the force that propels the rotating disk in the same direction.

The numerical examination is shown below.

  FIG. 8 is a vector diagram for a rough quantitative explanation. In the figure, the horizontal line represents the rotating disk, and the diagonal line represents the receiving blade.

In the figure, each parameter and variable are defined as follows.
Fo: Force applied to the receiving wing by waves
Fa: Horizontal force on the receiving wing (traveling propulsion force)
Fb: Normal force applied to the receiving blade (non-running force)
Vc: Vertical component velocity of wave motion
Va: Receiving blade travel speed
Vd: Wave speed equivalent deceleration by receiving blade travel
So: receiving blade area θ: pitch angle of receiving blade ρ: weight density of water
P: Energy available per hour (power generation)

First, the force Fo applied to the receiving wing by waves is
Fo = ρSo (Vc − Vd) ^{2 =} ρSo (Vc − Va sinθ) ² ---------- (1)
It becomes.
Here, the wave velocity equivalent deceleration Vd due to running of the receiving blade is
Vd = Va sinθ
--------- (2)
It is represented by

The driving force Fa received by the receiving blade is
Fa = Fo sinθ = ρSo (Vc − Va sinθ) ² sinθ ----------- (3)
The available energy per hour P generated in the receiving blade is
P = Va Fa = ρSo Va (Vc −Va sinθ) ² sinθ
----------- (Four)
It becomes.

Where k is the wave velocity equivalent deceleration coefficient
k = Vd
/ Vc = Va sinθ / Vc -------------------------- (5)
Then,
P = ρSo Vc ³ (1− k) ² k ---------- (6)
It becomes.

Differentiating P by k to find the maximum value of P, P is maximum when k = 1/3.
P, that is, the maximum value of power generation is Pmax, and the value of (1−k) ² k is μa = 0.148
-------------- (7)
Next
Pmax = ρSo Vc ³ (1−k) ² k = ρμa So Vc ³ = 0.148ρSo Vc ³ ------------------ (
8)
It becomes.

Specific numerical examples are as follows.
If the wave height is H and the wave period is T, the wave vertical velocity Vc is
Vc = = 2πH cos (2πt / T + C) / T ------------- (9)
It is. As a specific value,
If the wave height H is 2.5 m and the wave period T is 10 sec, the maximum value of Vc Vc max is
Vc max = 2πH / T = 1.57 m / s
--------- (Ten)
It becomes.

If the outer diameter Ra of the rotating disk is 100 m and the inner diameter Rb is 60 m, the total receiving blade area Sa is
Sa = π (Ra / 2) ² −π (Rb / 2) ² = 5,024 m ² ---------
(11)
Assuming that the wave comes from one direction, the effective area So of the receiving wing that the wave receives is half of Sa,
So = Sa / 2 = 2,512 m ² --------- (12)
It becomes.

As shown in Equation (7), the maximum efficiency μa for absorbing wave energy by the receiving blade is 0.148.
Power generation efficiency μg considering other losses
μg =
0.3
----------(13)
Then, the maximum power generation Pmax is
Pmax = μg μa ρSo (Vc max) ³ = 4,573 KW ---------
(14)
It becomes.

Vc is a sine wave that can be expressed by equation (9). The average root Vav of the absolute value of the cube is V
Vav = 0.424 Vc max
--------- (15)
Therefore, the average power generation Pav obtained from one rotating disk is
Pav = 1,842KW --------- (16)
It becomes.

When there are two rotor blades, the amount of power generation is twice that, and when there are N rotor blades, it is N times.

  Actual power generation has many complicated factors such as wing shape, complex wave shape and period, seasonal changes, overlapping of different waves, and specific power generation efficiency, and it is not easy to estimate accurately. However, the above value is a rough estimation example.

As another power generation amount estimation method, there is a method of using actually measured statistical data of wave energy.
According to the material of Non-Patent Document 1, the wave power in the appropriate land for offshore wave power generation around Japan is 20 to 70 KW / m 2.

  If the receiving blade has a diameter of 100m and is long enough to receive waves, and the power generation efficiency is 0.3 and this energy is absorbed, the power generation is 600 KW to 2,100 KW, which is not much different from the estimated power generation above.

FIG. 9 shows another embodiment of the receiving blade shape. In the figure, the receiving wing is formed of a canvas or an elastic membrane, the leading edge 91 is fixed to the frame 8 shown in FIG. 4 with a solid material, and the trailing edge 92 is deformed by wave motion, as shown in FIG. The same rotating force in the same direction is received and the turntable is rotated. The features of the receiving vane of this embodiment are that the material cost is low and the resistance when traveling underwater is small because the thickness is thin.

The shape of the receiving blade and the material selection are determined in consideration of the environmental condition of the sea surface, the scale of the system, the budget, and the like.

If this receiving wing is made of a transparent material, sunlight will reach the bottom of the rotating disk, and it is possible to suppress the effects on the marine animals and plants, the environment, and the ecosystem by blocking the light.

  In addition, the variable pitch structure of the receiving blade is deformed via a shaft or hinge located at the leading edge by receiving wave motion without using an elastic material, and the deformation angle is elasticized by a spring built into the shaft when deforming. There is also a way to change it.

  There is also a method of determining the pitch angle at the time of receiving without giving an upper limit to the deformation range without using an elastic material.

In addition, there are a method using a fixed pitch type receiving blade that generates lift when traveling, and a method using a combination of a variable pitch receiving blade and a fixed pitch receiving blade, such as a vertical axis wind power generation method. . Since the fixed-pitch receiving blade has a weak propulsive force at the time of starting rotation, it can be smoothly started by combining it with the variable-pitch receiving blade.

FIG. 10 shows another embodiment. In the embodiment shown in FIG. 1, the receiving blades are arranged in concentric rows, but in the embodiment of FIG. 10, the receiving blades are arranged in a radial row. The feature of this embodiment is that each receiving blade is easy to remove for each row, and easy to carry, construct and maintain.

FIG. 11 shows the external appearance of another embodiment, and each receiving blade is arranged as two receiving blade groups 33 and 34 that are not horizontal but rather vertical. FIG. 12 shows a side cross-sectional view of the system, showing that the two receiving blade groups 33, 34 are perpendicular to each other.

FIG. 13 shows an enlarged view of the rotating disk portion of this embodiment.
This combination of receiving vanes can capture both the vertical and horizontal directions of wave motion, increasing energy absorption efficiency. However, since it is easy to receive horizontal movement of waves and tidal currents, the strength to fix the whole position must be large.

In order to efficiently absorb the wave energy, it is desirable that the receiving blade is not swept away in the direction of wave motion. In the embodiment of FIG. 1, it is desirable that the turntable does not move up and down. When the rotating disk moves up and down with the wave, the relative speed between the wave and the rotating disk decreases, and the power generation efficiency decreases.

FIG. 14 shows an embodiment for suppressing the vertical movement of the rotating disk. The wave motion is elliptical, but the wave motion is less at some depth below the surface of the water. The resistance plate 21 is installed in parallel to the water surface at a depth where the wave motion is reduced, and resists the vertical motion. The resistance plate 21 is fixed to the stator 52 of the shaft structure 5 of the rotating disk. Therefore, the turntables 11 and 12 exhibit resistance to up and down movement caused by waves, and the up and down movement is suppressed. This suppresses a decrease in rotational efficiency, that is, power generation efficiency.

The system of the embodiment of FIG. 1 is a floating type, and the system is fixed to the seabed by an anchor. If the system is installed on the deep sea where the anchor cannot reach, it may be swept away by wind, tidal current, etc.

FIG. 15 shows the appearance of a structure that is controlled so that the system is in place. In the figure, the linear propulsion boards 13 and 14 have the same receiving blade as in FIG. 1 and receive propulsive force by waves. However, the receiving vanes are arranged in the same direction, and the linear propulsion board receives the propulsive force in the linear direction, not the rotational force.

The directions of the linear propulsion boards 13 and 14 can be rotated in an arbitrary direction by an appropriate control system. FIGS. 16, 17 and 18 show how the entire system is propelled by the direction of the propulsion panel.

In FIG. 16, the propulsion vectors of the two linear propulsion boards 13 and 14 are in the same direction, and the entire system receives the propulsive force and moves in the linear direction.

In FIG. 17, the composition of the propulsion vectors of the two linear propulsion boards is the rotational direction, and the system rotates in response to the rotational moment.

In FIG. 18, the propulsion vectors of the two linear propulsion boards are erased from each other and there is no propulsive force.
The direction of the linear propulsion board is controlled by detecting system position information by GPS or the like, and the system position is moved to a desired position and angle. As a result, it is fixed in place without using an anchor.

In addition, the system can be moved from the place where the system is manufactured, repaired and inspected at the time of system installation, maintenance or repair to the system installation location, thereby reducing the cost of installation and maintenance.
If the wave is weak and sufficient position control is not possible, a method of performing position control by moving a screw or the like by external electric power or an internal battery is also possible. A propulsion mechanism using a linear propulsion board or a screw for the purpose of position control and movement is generally referred to as a propulsion module.

The wave power generation method of the present invention can realize a large-scale, efficient and low-cost wave power generation, and has a great effect on the future use of natural energy, the accompanying reduction of CO2, correction of uneven distribution of energy resources, creation of new economic activities, etc. Can be demonstrated.

DESCRIPTION OF SYMBOLS 1 Anchor 2 Support structure 3 Receiving blade 5 Shaft structure 6 Water surface 7 Seabed 8 Frame 11 Rotating disk 12 Rotating disk 13 Linear propulsion board 14 Linear propulsion board 21 Resistance plate 31 Fixed part 32 Elastic part 33 Receiving blade group 34 Receiving blade Group 51 Rotor 52 Stator 91 Front edge 92 Rear edge

Claims (6)

Equipped with a plurality of receiving blades arranged concentrically in a radial direction and a circumferential direction, which are propelled by the movement of waves, the receiving blades having opposing connecting parts and non-connecting parts, The connecting part and the non-connecting part of the receiving blade are fixed to a rotating disk so that they are aligned in the circumferential direction, and receive the driving force of the receiving blade and rotate on a horizontal plane along the sea surface. A wave power generation system characterized in that the generator or pump is driven by the movement of the rotating disk to generate power.
The wave power generation method according to claim 1, wherein the rotating shafts of a plurality of rotating disks rotating in opposite directions are combined by a support structure to cancel the moment of force that each rotating disk receives as a reaction. The wave power generation method according to claim 1, further comprising a plurality of receiving vanes arranged vertically to each other. The receiving vane is composed of a fixed part and an elastic part. The fixed part is fixed to the frame, and the elastic part is integrated with the fixed part. The wave power generation method according to claim 1, wherein the wave power generation method is changed. 2. The wave power generation system according to claim 1, wherein a rotating disk equipped with a receiving blade whose pitch is changed by wave motion, a receiving blade with a fixed pitch, or a combination of both is used. Having a propulsion module with propulsive force in the linear direction or rotational direction, and controlling the linear propulsive force and rotational propulsive force to perform position control and angle control to keep the system position at a fixed position, or system The wave power generation method according to claim 1, wherein the apparatus is moved from a manufacturing site or a maintenance / repair base to an installation location.