U.S. patent number RE31,111 [Application Number 06/032,162] was granted by the patent office on 1982-12-28 for wave driven generator.
This patent grant is currently assigned to Williams, Inc.. Invention is credited to Glenn E. Hagen.
United States Patent |
RE31,111 |
Hagen |
December 28, 1982 |
Wave driven generator
Abstract
A plurality of different sized floats are connected into an
array through nonlinear interfaces so their relative motions drive
hydraulic pumping means. Floats in the array are sized to present a
"black body" to the ocean waves incident upon the array. Fluid
moved by the pumping means is used to drive an electric
turbogenerator.
Inventors: |
Hagen; Glenn E. (New Orleans,
LA) |
Assignee: |
Williams, Inc. (New Orleans,
LA)
|
Family
ID: |
26708060 |
Appl.
No.: |
06/032,162 |
Filed: |
April 23, 1979 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
657892 |
Feb 13, 1976 |
04077213 |
Mar 7, 1978 |
|
|
Current U.S.
Class: |
60/500; 60/501;
417/331 |
Current CPC
Class: |
F03B
13/20 (20130101); F05B 2240/311 (20130101); F05B
2200/21 (20130101); Y02E 10/30 (20130101); Y02E
10/38 (20130101) |
Current International
Class: |
F03B
13/20 (20060101); F03B 13/00 (20060101); F03B
013/12 () |
Field of
Search: |
;60/497,500,501,505,506
;417/331,332,333,337 ;290/53 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Ostrager; Allen M.
Attorney, Agent or Firm: Dula; Arthur M.
Claims
I claim:
1. A power gathering array for extracting energy from wave motion
of a fluid, said wave motion having both an amplitude spectrum and
wavelength spectrum, comprising:
a plurality of differing sized floats, each said float having a
density such that it floats on the surface of said fluid and moves
in response to said wave motion;
a connecting means for connecting the rear of at least one first
smaller float of said plurality to the front of at least one second
larger float of said plurality, said connecting means being adapted
to allow relative motion to occur between said first and second
floats responsive to said wave motion when the two floats are
oriented so the smallest float points into the direction of wave
motion;
second connecting means for connecting the rear of the largest
float of said array to a fixed object; and
work extracting means responsive to said relative motion for
extracting a unit amount of work from a unit amount of said
relative motion and a non-linearly greater number of units of work
from each additional unit of relative motion.
2. A power gathering array according to claim 1 wherein the sizes
of said plurality of floats are chosen to allow said floats to
dynamically couple into a plurality of wavelengths of said wave
motion.
3. A power gathering array according to claim 1 wherein the
nonlinear response of said nonlinear work extraction means to said
relative motion is adapted to match the amplitude spectrum of said
wave motion.
4. A power gathering array according to claim 3 wherein:
each said rear float has a front solid prismatic surface, having an
upper and lower fact, whose apex is parallel to the surface of said
fluid and proximate the middle of the rear surface of its
associated said front float;
said nonlinear work extraction means comprises:
a hollow tubular member proximate at least one face of said
prismatic surface and adapted so relative motion of said floats
causes a change in the cross section of said tubular member;
and
said hollow tubular member is filled with fluid and equipped with
at least one check value to cause it to function as a pump.
5. A power gathering array according to claim 3 wherein at least
two of the plurality of said floats are connected by means of at
least one hydraulic cylinder adapted to pump a fluid in response to
the relative motion of said floats.
6. A power gathering array according to claim 5 wherein said
hydraulic cylinder is a single action hydraulic cylinder mounted on
one of said floats, the piston shaft of said hydraulic cylinder
being responsive to and operatively connected to said other float
via a mechanical linkage adapted to nonlinearly convert the
relative motion of said floats to linear motion of said piston
shaft.
7. A power gathering array according to claim 1 wherein said
plurality of floats increase regularly in length by a scaling
factor equal to the nth root of an integer greater than one times
the length of the smallest float in the array, n being greater than
one.
8. A power gathering array according to claim 7 wherein the
smallest float of the array is square and said scaling factor is
the cube root of two.
9. A power gathering array according to claim 7 wherein the
smallest float in the array is approximately one-half the length of
the shortest wavelength wave from which power is to be obtained and
the largest float in the array is approximately one-half the length
of the longest wavelength wave from which power is to be
obtained.
10. A power gathering array according to claim 9 wherein said
plurality of floats includes enough floats to trap the wave motion
of said fluid as a black body absorber, whereby both the reflected
and transmitted energy from any one float of the array would be at
least in part absorbed by other floats in the array.
11. A power gathering array as in claim 5 wherein the fluid pumped
by said hydraulic cylinder is raised to a higher potential energy
level and stored for later use.
12. A power gathering array according to claim 9 wherein said
smallest float is approximately from 50 feet to 100 feet long and
said largest float is approximately from 200 feet to 400 feet
long.
13. A wave generating unit for converting the power of the wave
motion of a fluid, said wave motion having an amplitude spectrum
and a wavelength spectrum, to mechanical and electrical power
comprising:
a plurality of differing sized floats, each said float having a
density such that it floats on the surface of said fluid and moves
in response to said wave motion;
a connecting means for connecting the rear of at least one first
smaller float of said plurality to the front of at least one second
larger float of said plurality, said connecting means being adapted
to allow relative motion to occur between said first and second
floats responsive to said wave motion when the two floats are
oriented so the smallest float points into the direction of wave
motion;
second connecting means for connecting the rear of the largest
float of said array to a fixed object;
work extracting means responsive to said relative motion for
extracting a small amount of work from a slight amount of said
relative motion and a nonlinearly larger amount of work from each
proportionately larger amount of said relative motion; and
power conversion means responsive to said nonlinear work extraction
means for converting power collected by the extraction means to
mechanical and electrical power.
14. A wave powered generating unit as in claim 13 including a
plurality of wave generating units, each said unit connecting
physically in parallel to prevent any individual unit from becoming
disoriented with respect to the direction of wave motion.
15. A wave generating unit according to claim 13 wherein the sizes
of each plurality of floats are chosen to allow said floats to
dynamically couple into a plurality of wavelengths of said wave
motion.
16. A wave generating unit according to claim 13 wherein the
nonlinear response of said nonlinear work extraction means to said
relative motion is adapted to match the amplitude spectrum of said
wave motion.
17. A wave generating unit according to claim 16 wherein:
each said rear float has a front solid prismatic surface, having an
upper and lower fact, whose apex is parallel to the surface of said
fluid and proximate the middle of the rear surface of its
associated said front float;
said nonlinear work extraction means comprises:
a hollow tubular member proximate at least one face of said
prismatic surface and adapted so relative motion of said floats
causes a change in the cross section of said tubular member;
and
said hollow tubular member is filled with fluid and equipped with
at least one check valve to cause it to function as a pump.
18. A wave generating unit according to claim 16 wherein at least
two of the plurality of said floats are connected by means of at
least one hydraulic cylinder adapted to pump a fluid in response to
the relative motion of said floats.
19. A wave generating unit according to claim 18 wherein said
hydraulic cylinder is a single action hydraulic cylinder mounted on
one of said floats, the piston shaft of said hydraulic cylinder
being responsive to and operatively connected to said other float
via a mechanical linkage adapted to nonlinearly conver the relative
motion of said floats to linear motion of said piston shaft.
20. A wave generating unit according to 13 wherein said plurality
of floats increase regularly in length by a scaling factor equal to
the nth root of an integer greater than one time the length of the
smallest float in the array, n being greater than one.
21. A wave generating unit according to claim 20 wherein the
smallest float of the array is square and said scaling factor is
the cube root of two.
22. A wave generating unit according to claim 20 wherein the
smallest float in the array is approximately one-half the length of
the shortest wavelength wave from which power is to be obtained and
the largest float in the array is approximately one-half the length
of the longest wavelength wave from which power is to be
obtained.
23. A wave generating unit according to claim 22 wherein said
plurality of floats includes enough floats to trap the wave motion
of said fluid as a black body absorber, whereby both the reflected
and transmitted energy from any one float of the array would be at
least in part absorbed by other floats in the array.
24. A wave generating unit as in claim 18 wherein the fluid pumped
by said hydraulic cylinder is raised to a higher potential energy
level and stored for later use.
25. A wave generating unit according to claim 22 wherein said
smallest float is approximately from 50 feet to 100 feet long and
said largest float is approximately from 200 feet to 400 feet
long.
26. A wave generating unit as in claim 16 wherein said power
conversion means is a water driven turbine driving an electric
generator.
27. A wave generating unit as in claim 26 wherein at least a
portion of said power conversion means is mounted on at least one
of the floats of said array.
28. A wave generating unit as in claim 27 wherein:
said turbine and generator are housed on the largest float of said
array; and
electric power from said generator is fed to shore through a
subsurface power transmission cable.
29. A wave generating unit as in claim 26 wherein said turbine is a
pelton wheel.
30. A wave generating unit as in claim 29 including feedback
control means for controlling the flow of water to the pelton wheel
adapted to maintain constant water pressure. .Iadd.31. A power
generating array for extracting energy from wave motion of a fluid,
said wave motion having both an amplitude spectrum and a wavelength
spectrum comprising:
a plurality of differing sized floats, said float sizes chosen to
allow said floats to dynamically couple into a plurality of
wavelengths of said wave motion, each said float having a density
such that it floats in said fluid and moves in response to said
wave motion;
connecting means for holding said plurality of floats in position
relative to one another while allowing said plurality of floats to
move in response to said wave motion; and
work extracting means responsive to said motion of said floats for
extracting a unit amount of work from a unit amount of said motion
and a nonlinearly greater number of units of work from each
additional unit of
motion. .Iaddend. .Iadd.32. A power gathering array according to
claim 31 wherein the nonlinear response of said work extraction
means to said relative motion is adapted to match the amplitude
spectrum of said wave motion. .Iaddend. .Iadd.33. A power gathering
array according to claim 32 wherein said plurality of floats differ
in length by a scaling factor equal to the nth root of an integer
greater than one times the length of the smallest float in the
array, n being greater than one. .Iaddend. .Iadd.34. A power
gathering array according to claim 33 wherein the smallest float of
the array is square and said scaling factor is the cube
root of two. .Iaddend. .Iadd.35. A power gathering array according
to claims 31, 32, 33 or 34 wherein the smallest float in the array
is approximately one-half the length of the shortest wavelength
wave from which power is to be obtained and the largest float in
the array is approximately one-half the length of the longest
wavelength wave from which power is to be obtained. .Iaddend.
.Iadd.36. A power gathering array according to claims 31, 32, 33 or
34 wherein said plurality of floats includes enough floats to trap
the wave motion of said fluid as a black body absorber, whereby
both the reflected and transmitted energy from any one float of the
array would be at least in part absorbed by other floats in the
array. .Iaddend. .Iadd.37. A power gathering array as in claim 36
wherein the fluid pumped by said hydraulic cyliner is raised to a
higher potential energy level and stored for later use. .Iaddend.
.Iadd.38. A power gathering array according to claim 35 wherein
said smallest float is approximately from 50 feet to 100 feet long
and said largest float is approximately from 200 feet to 400 feet
long. .Iaddend. .Iadd.39. A power gathering array according to
claim 38 wherein said work extracting means is a plurality of
hydraulic cylinders, said cylinders being responsive to and
operatively connected to between said floats and a fixed object via
a mechanical linkage adapted to nonlinearly convert the relative
motion of said floats to linear motion of said piston. .Iaddend.
.Iadd.40. A power gathering array for extracting energy from wave
motion of a fluid, said wave motion having both an amplitude
spectrum and a wavelength spectrum comprising:
a plurality of differing sized floats, said float sizes chosen to
allow said floats to dynamically couple into a plurality of
wavelengths of said wave motion, each said float having a density
such that it floats in said fluid and moves in response to said
wave motion;
connecting means for holding said plurality of floats in position
relative to one another while allowing said plurality of floats to
move in response to said wave motion;
work extracting means responsive to said motion of said floats for
extracting a unit amount of work from a unit amount of said motion
and a nonlinearly greater number of units of work from each
additional unit of motion; and
power conversion means responsive to said nonlinear work extraction
means for converting power collected by the extraction means to
mechanical and electrical power. .Iaddend. .Iadd.41. A wave powered
generating unit as in claim 40 including a plurality of wave
generating units, each said unit connecting physically in parallel
to prevent any individual unit from becoming disoriented with
respect to the direction of wave motion.
.Iaddend. .Iadd.42. A wave generating unit according to claim 40
wherein the sizes of each plurality of floats are chosen to allow
said floats to dynamically couple into a plurality of wavelengths
of said wave motion. .Iaddend. .Iadd.43. A wave generating unit
according to claim 40 wherein the nonlinear response of said
nonlinear work extraction means to said relative motion is adapted
to match the amplitude spectrum of said wave motion. .Iaddend.
.Iadd.44. A wave generating unit according to claim 43 wherein the
smallest float of the array is square and said scaling factor is
the cube root of two. .Iaddend. .Iadd.45. A wave generating unit
according to claim 44 wherein the smallest float in the array is
approximately one-half the length of the shortest wavelength wave
from which power is to be obtained and the largest float in the
array is approximately one-half the length of the longest
wavelength wave from which power is to be obtained. .Iaddend.
.Iadd.46. A wave generating unit according to claim 45 wherein said
plurality of floats includes enough floats to trap the wave motion
of said fluid as a black body absorber, whereby both the reflected
and transmitted energy from any one float of the array would be at
least in part absorbed by other floats in the array.
.Iaddend. .Iadd.47. A wave generating unit according to claim 45
wherein said smallest float is approximately from 50 feet to 100
feet long and said largest float is approximately from 200 feet to
400 feet long. .Iaddend. .Iadd.48. A wave generating unit as in
claim 40 wherein said power conversion means is a water driven
turbine driving an electric generator. .Iaddend. .Iadd.49. A wave
generating unit as in claim 48 wherein at least a portion of said
power conversion means is mounted on at least one of the floats of
said array. .Iaddend. .Iadd.50. A wave generating unit as in claim
49 wherein:
said turbine and generator are housed on the largest float of said
array; and
electric power from said generator is fed to shore through a
subsurface power transmission cable. .Iaddend. .Iadd.51. A wave
generating unit as in claim 48 wherein said turbine is a pelton
wheel. .Iaddend. .Iadd.52. A wave generating unit as in claim 51
including feedback control means for controlling the flow of water
to the pelton wheel adapted to maintain constant water pressure.
.Iaddend.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to wave engines and more
particularly relates to wave engines used to drive electric
generators. Specifically, the present invention relates to wave
driven generators using a plurality of different sized floats to
present a black body to the incoming wave energy whereby wave
energy is nonlinearly coupled into hydraulic pumping means.
2. Background of the Prior Art
It has long been known in the art of power generation to use the
potential energy available in ocean waves to lift a float. A
.[.truely.]. .Iadd.truly .Iaddend.amazing variety of ingenious
mechanical linkages have been developed in an attempt to
efficiently capture the energy of ocean waves. See, for example,
U.S. Pat. Nos. 562,317, 632,139, 694,242, 738,996, 886,883, 917,411
and 986,629. All of these early patents rely upon mechanical
linkages between fixed floats to trap the rocking, lifting, falling
or longitudinal motions of waves. All of the engines disclosed in
these patents are mechanically complex and highly inefficient.
While all the above cited references depend on the potential energy
of waves to develop motive power, some wave motors in the past
taught the use of the wave's kinetic energy. See, for example, U.S.
Pat. No. 1,072,272.
A careful study of the prior art shows that most historical wave
motors utilize either (1) the kinetic energy of waves by devices
such as paddle wheels, or (2) the wave's potential energy by a
float or a series of floats. Few devices utilize both forms of
energy.
The prior art, insofar as it relates to wave engines that rely upon
the lifting power of waves, i.e., its potential energy, rely either
on a single float, for example U.S. Pat. Nos. 1,202,742, 1,471,222,
1,647,025, 1,746,613, 1,953,285 and 1,962,047, or utilize a series
of floats of the same size, for example U.S. Pat. Nos. 1,925,742,
1,867,780, 1,688,032, 1,567,470, and 1,408,094. Additionally, many
early wave motors are extremely complex mechanically. For example,
see U.S. Pat. Nos. 1,528,165, 1,169,356, and 1,818,066.
All prior art wave motors teach the direct linear coupling of the
float's motion through either mechanical or hydraulic means to the
motion of a shaft or piston. As a result, all such wave motors had
to be very rugged and heavy to withstand the wide spectrum of wave
energy incident upon them. For example, one wave motor installed in
Atlantic City, N.J. consisted of six foot cylinder floats 4 feet
high. Each float weighed about 3,100 pounds and was lifted two feet
by waves 11 times per minute. They drove a horizontal shaft by
means of chains and rachets, developing about 11 horsepower,
steadiness being obtained by the use of heavy flywheels. The
inefficiency, capital cost and complexity of this and all prior art
wave motors caused them to be unsuccessful. (Power, Jan. 17, 1911).
(A similar wave motor was proposed by Smith in Mechanical
Engineering, September, 1927 at page 995.)
The most modern wave motors taught by the prior art does not differ
significantly in its manner of operation from wave engines taught
at the beginning of this century. See, for example, U.S. Pat. No.
3,879,950, issued Apr. 29, 1975 to Kiichi Yamada for a wave
generator to be used in conjunction with an offshore nuclear power
plant. This modern wave motor uses a plurality of identical floats
whose motion is coupled linearly to a series of pneumatic pistons.
Unfortunately, such a linearly coupled collector cannot efficiently
trap wave energy.
Waves in the ocean vary in amplitude, or wave height, from a
fraction of a foot to over 50 feet and in frequency from a wave
length of less than 5 feet to over 1,000 feet. To extract the
maximum potential energy from any given wave, a float must be
capable of dynamically coupling to the wave's movement. A given
size float will respond most efficiently to only one wave length.
To be efficient, a wave motor must provide a plurality of different
size floats capable of coupling efficiently into a broad spectrum
of differing wavelengths, i.e., to all the waves from which power
must be efficiently extracted. Broadly, this concept is called
"resonance".
In addition to resonance with a broad spectrum of wavelengths, the
floats of an efficient wave motor must be capable of extracting
power from both low and high amplitude waves. Because waves differ
in amplitude by as much as two orders of magnitude, any device that
extracts power by linearly coupling wave movement to gears or
pistons will have to be inefficient in extracting power from either
the high or low amplitude end of the wave power spectrum.
Theoretically, .[.an.]. .Iadd.a .Iaddend.single float acting alone,
even if it is the proper size, can only absorb about one third of
the available power from a wave incident upon it. This is caused by
the fact that a third of the wave's energy is absorbed by the
float, a third is reflected back from the float and the final third
is transmitted through the float to its attached structures. This
fact, as well as the fact that wave motors taught by the prior art
do not couple efficiently into either the frequency or amplitude
spectrum of ocean waves, have caused all prior art wave motors to
be very inefficient.
It is an object of the present invention to teach a wave engine
that is capable of extracting hydraulic power efficiently from a
wide variety of wavelengths of ocean waves.
It is a further object of the present invention to provide a wave
engine that couples into the amplitude spectrum of ocean waves in a
nonlinear manner so as to efficiently extract power from both high
amplitude and low amplitude waves.
It is yet a further purpose of the present invention to provide a
wave generator whose multiple floats act together to form a black
body trapping all incident wave energy.
It is yet another purpose of the present invention to provide a
wave engine having an assemblage of different size floats that
function together as a wave trap to convert approximately 80% of
the wave energy incident upon it to hydraulic power.
Yet a final purpose of the present invention is to provide a wave
motor that can easily be scaled up to provide a large amount of
power cheaply and that is simple enough to require a low level of
maintenance.
After an extended search at the Patent Office, the closest art
found to the present invention is U.S. Pat. No. 1,757,166 covering
an apparatus and method of obtaining power from ocean waves.
However, even this prior art teaches the use of a plurality of
single unconnected floats of the same size. No prior art found by
the inventor teaches the advantages of tying together a group of
floats in an array to form a wave trap to capture reflected and
transmitted wave energy. Also, no prior art found by the inventor
teaches the nonlinear coupling of the floats to their associated
power extraction devices.
SUMMARY OF THE INVENTION
The present invention is an array of floats that would be anchored
to the ocean floor some distance off shore. The optimum distance
offshore will generally be beyond the point where the ocean grows
so shallow that a significant portion of wave energy is dissipated
in turbulence. These floats are arranged so waves impinge first
upon the smallest floats of the array. These smallest floats are
pivotally connected to progressively larger floats. The floats are
also connected by hydraulic pumping means, such as hydraulic
cylinders or tubes and pressure plates. These hydraulic pumping
means are nonlinearly responsive to any relative motion between the
floats. As larger amplitude waves strike the floats each additional
increment of relative motion between the floats does
proportionately more work and moves an incrementally greater amount
of hydraulic fluid. The undulating action of the array of floats is
thus converted to moderate pressure hydraulic energy which can then
be used to operate a turbogenerator.
The smallest float in the array must be approximately half the size
of the smallest wave from which energy is to be efficiently
extracted. The largest float should be approximately one-half the
wave length of the largest wave the system will significantly
attenuate.
The most significant differences between the present invention and
those wave engines taught by the prior art is as follows:
1. The present invention employs an array of floats of different
sizes. This array extracts energy from a wider frequency spectrum
of waves than was taught by the prior art.
2. The relative motion of floats in the present invention is
converted to hydraulic energy nonlinearly. This allows the array of
floats to respond efficiently to very low amplitude waves by
presenting very little resistence to them while still responding
very efficiently to high amplitude waves by presenting a great deal
more resistance to incremental .[.amount.]. .Iadd.amounts
.Iaddend.of relative motion caused by them.
3. Finally, the use of a plurality of floats coupled together in an
array allows the present invention to trap the wave energy that
would otherwise be lost by reflection or transmission from the
individual floats. In the present invention, the portion of wave
energy transmitted by the float forms a portion of the total energy
incident upon other floats in the array. The energy reflected from
a float also, except at the perimeter of the array, forms a portion
of the energy incident upon the other floats. Thus a wave incident
upon the array is trapped in it and the array functions as a black
body to efficiently absorb all incident wave energy.
As a result of this efficient absorption of wave energy the area
directly behind the array is relatively calm. The floating array of
wave engines taught by the present invention will thus function as
a floating breakwater, although this is not a primary purpose of
the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic cross sectional view of an idealized
wave;
FIG. 2 is a graph showing the total energy contained in ocean waves
for given wave amplitudes and wave lengths;
FIG. 3 is a cross sectional schematic view of a portion of a float
array as taught by the present invention together with a schematic
illustration of its associated hydraulic accumulators and
generators;
FIG. 4 is a vertical schematic view of the same section of the wave
motor array as was illustrated by FIG. 3;
FIG. 5 is a view taken along section line 5--5 of FIG. 4 and
illustrates one of the hydraulic pumping means taught by the
preferred embodiment of the present invention;
FIG. 6 shows schematically the inner action between a wave and a
portion of a float array taught by the preferred embodiment of the
present invention;
FIG. 7 shows an alternative hydraulic pumping means connecting two
floats in an array as taught by the present invention; and
FIG. 8 is another view of the embodiment of the present invention
shown in FIG. 7.
FIG. 9 is an isometric view of a typical power generating array,
one module of a power generating system, constructed according to
the preferred embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 shows an idealized ocean wave seen in cross section. Wave 10
has crest 12 and trough 14. The distance between two crests or two
troughs is known as the "wavelength" of the wave and is a function
of the wave's total energy. The height or amplitude of the wave is
defined as the difference between the crest and trough of the wave.
Total wave energy is also a function of wave height.
The total energy of a wave, expressed in horsepower per foot of
wave breadth, i.e. per foot of wave front incident upon an array of
floats, is found by the equation:
where H is the height of the wave in feet and L is the wave length,
also in feet. Albert W. Stahl, U.S.N., Transactions, American
Society of Mechanical Engineering, Volume 13, page 438.
The British Admiralty Weather Manual classifies wave height as
follows:
TABLE A ______________________________________ Description of Mean
Height of Waves Sea Disturbance m ft
______________________________________ calm; glassy 0 0 calm;
rippled 0.2 0.5 smooth; wavelets 0.3-0.8 1-2.5 slight 1.5 5
moderate 3 9 rough 4 14 very rough 6 19 high 8 15 very high 9-11
31-37 exceptionally high 14 45 or over
______________________________________
The usual type of North Atlantic wave has a wave length from 160 to
320 feet, occasionally attaining 500 to 600 feet, and a speed that
ranges from 25 to 35 knots. In the South Pacific waves with
wavelengths up to 1,000 feet and speeds up to 50 knots are to be
found. Illustrations in the remainder of the discussion of the
present invention will be confined to moderate waves having heights
between 5 and 15 feet and wavelengths between 100 and 300 feet. The
reason for this limitation is not due to any limitation on the
present invention, but is a convenience because such waves are the
average waves found off the North Atlantic coast of the United
States.
FIG. 2 is a graph showing the energy contained in ocean waves
having wave .[.height.]. .Iadd.heights .Iaddend.between 5 and 15
feet and wavelengths between 100 and 300 feet. This representation
was obtained by using the value for the total energy of the wave,
determined by the equation shown above, to yield the horsepower per
foot of wave breadth and then converting from horsepower per foot
to megawatts per mile. (There are 3.94 megawatts per mile in a wave
that has a total energy of one horsepower per foot.) To gain
perspective, the largest nuclear power generating facility in the
United States is capable of generating approximately a thousand
megawatts.
The values of total energy given in megawatts per mile in FIG. 2
will be used throughout the rest of this specification. It should
be understood that these figures are chosen only for convenience
because they represent typical wave heights and wavelengths for
average size waves in the Atlantic. "Modern Studies of Wind
Generated Waves", Volume 8, Contemporary Physics, pages 171-183,
March 1967. Also see, R. A. R. Tricker, Boars, Breakers, Waves and
Wakes: An Introduction to the Study of Waves On Water (1965).
FIG. 3 shows array 30 comprising first float 32, second float 34,
third float 36 and a portion of fourth float 38. Array section 30
is connected by means of hydraulic line 40 to accumulator generator
section 42. Float 32 is a hollow water tight member containing a
.[.bouyant.]. .Iadd.buoyant .Iaddend.cavity 44. The displacement of
the float on water level 46 is determined by the size of
.[.bouyant.]. .Iadd.buoyant .Iaddend.cavity 44 according to well
known hydrostatic laws. See generally Hydraulics, R. L. Daugherty,
McGraw Hill 1937. Float 32 may be of any desired shape, but in the
preferred embodiment a flat back plate 48 at its side proximate
front 50 of float 34. The rear edges of float 32 are attached by a
hinge, which will be described in connection with FIG. 4, to the
front of float 34. The front of float 34 is provided with a pair of
prismatic surfaces 52 and 54 on its lower and upper side,
respectively.
Hydraulic fluid input line 56 is connected through one-way valve 58
to lower pump tube 60. Lower pump tube 60 lies between prismatic
face 52 of the front of float 32 and the rear flat portion 48 of
float 2. Likewise, upper pump tube 62 is located between upper
prismatic face 54 of float 34 and the rear flat face 48 of float
32. Upper pump tube 62 is connected through one-way valve 64 to
accumulator hydraulic feed line 66. Float 34 is approximately 26%
longer than float 32. Likewise float 36 is approximately 26% longer
than float 34. Similarly float 38 is approximately 26% longer than
float 36. Except for the smallest front float, each succeeding
float in this embodiment has an upper and lower prismatic front
face and a vertical rear face that act together with pump tubes to
pump hydraulic fluid. All the floats are connected together by
simple hinges, which will be described in greater detail below.
Float 34 has .[.bouyant.]. .Iadd.buoyant .Iaddend.space 68 and back
flat face 70. Upper and lower pump tubes 72 and 74, respectively,
lie between the upper prismatic face of float 36 and rear face 70
and the lower prismatic face of float 36 and rear face 70
respectively. As was described in connection with the upper and
lower pump tubes between float 32 and 34, lower pump tube 74 is
connected in fluid communication through one-way valve 76 with
hydraulic supply line 56 and upper pump tube 72 is connected
through one-way valve 78 in fluid communication with hydraulic
accumulator line 66.
The hydraulic pump tubes between each pair of floats in the array
are similarly connected to the hydraulic supply and accumulator
hydraulic power line through one-way valves.
First hydraulic accumulator 82 is connected to three-way valve 80
by line 84. Second hydraulic accumulator 86 is connected to valve
80 by line 88. The first hydraulic accumulator is connected to
turbine input 90 by line 92. First hydraulic accumulator 82 is also
equipped with a dump valve 94. Second hydraulic accumulator 86 is
also connected to turbine input 90, but by line 96. Second
hydraulic accumulator is also equipped with a dump valve 98.
Turbine input 90 is located at the high pressure input end of
turbogenerator 100. Hydraulic fluid outlet 102 is on the low
pressure side of turbogenerator 100.
Structurally, the floats shown in FIG. 3 may be made of any
material that is watertight and .[.bouyant.].
.Iadd.buoyant.Iaddend.. It is expected that the first test models
of the wave motor will be made of wood while larger models will
have floats made of concrete. The upper and lower pump tubes and
all the hydraulic connecting tubing may be any type of hydraulic
tubing capable of withstanding the 100 to 200 pounds of pressure
per square inch generated by the hydraulic power collecting array
of the present invention.
The floats and all hardware used to connect them together should be
made of corrosion resistant material.
Functionally, working fluid, which may be water or any other
convenient hydraulic fluid is drawn in through input line 56
through one-way valves 58 and 76 and into their respective lower
pump tubes. As will be explained in greater detail in connection
with the discussion of FIG. 6 below. Any relative movement of the
floats places compressive force on these pump tubes and causes them
to act as hydraulic pumps. The arrangement of one-way valves is
very straightforward and is designed to prevent the fluid from
flowing backwards when the relative motion of the floats reverses.
As the amount of relative motion between the floats increases, each
additional degree of rotation of a float about its pivotal
connection with another float causes the flat back of the forward
float to become more nearly parallel with the upper or lower
prismatic face of its following float. The two surfaces also move
together as the angle increases. A small amount of relative motion
causes the pump tubes to pump a small amount of hydraulic fluid.
Once this small amount of hydraulic fluid has been pumped, a
further increase in relative motion of any two floats will pump an
incrementally greater amount of hydraulic fluid. If a wave has
sufficient amplitude to cause a yet further relative motion to
occur between two floats, then the front surface of one float and
back surface of the other will become more nearly parallel and will
pump a still greater incremental volume of hydraulic fluid.
In very calm weather a small ripple of water will meet little
resistance in absorber array 30 and will efficiently cause relative
motion to occur between its floats. This relative motion will pump
hydraulic fluid and thus energy will be effectively absorbed from
low amplitude waves. During a storm, whenever high amplitude waves
are available, very large amounts of relative motion will occur
between float pairs in the array. This large amount of relative
motion will be much harder to achieve and the array will thus
effectively absorb .Iadd.a .Iaddend.greater amount of energy
available from higher amplitude waves.
Hydraulic fluid entering valve 80 may be selectively directed to
either the first or second accumulator. It is the function of these
hydraulic accumulators to even out surges of power coming from the
array and to provide a steady hydraulic pressure to turbogenerator
100. The hydraulic accumulators are duplicated and placed in
parallel so maintenance may be performed upon one without
interrupting the supply of hydraulic power to turbogenerator
100.
Each float is 1.26 times (or 26%) longer than the preceding float
because 1.26 is approximately the cube root of 2. Thus float length
doubles every third float, and, by doubling the width of this third
float, the array may be scaled up to any desired size without
difficulty.
After hydraulic fluid has flowed through the turbogenerator and
generated electricity, it may be returned to input line 56. The
system may thus be closed. Alternatively, the present invention
could be used to pump water from a body of water to an elevated
reservoir. Water in the reservoir could then be run through an
existing turbogenerator to generate power.
FIG. 5 is similar to the structure shown in FIG. 4, as seen from
above. Float 32 is connected by means of hinge 200, which may be
any conveniently designed hinge, to float 34. Float 34 is connected
by hinge 202 to float 36 and float 36 is connected by hinge 204 to
float 38.
FIG. 4 shows how an array of floats is assembled. Floats 32, 108,
110 and 112 form the first rank of floats. They are connected by
hinges (like hinge 200) at their edges to the edges and center of
the next level of floats, in this instance floats 34 and 114. Upper
pump tubes 62 and 72 are clearly shown between their respective
pairs of floats.
When a wave strikes the first group of floats, some wave energy is
absorbed when it causes relative movement of the floats and pumps
hydraulic fluid. The incident wave's remaining energy is
transmitted to larger floats. Some of this transmitted energy is
relected and again perturbs smaller floats causing additional
hydraulic pumping. Some of the transmitted energy is absorbed by
causing relative motion in the next group of floats 34 and 114.
This pumps additional hydraulic fluid. The remaining energy,
however, is transmitted further to interact with float 36 and pump
additional hydraulic fluid. Again, some of the transmitted energy
is reflected back to floats 34 and 114 and to the smallest group of
floats where it interacts to pump additional hydraulic fluid. The
array functions as a wave trap and is significantly more efficient
than any means taught by the prior art extracting hydraulic energy
from movement of ocean waves. The preferred embodiment of the
present invention can convert approximately 80% of the ocean wave
energy incident upon its wave motor float array to hydraulic
energy.
FIG. 5 shows a view along line 5--5 of FIG. 4. Hinge pivot 206 and
207 are provided to attach the front of float 38 to back hinge 204
of float 36. Lower prismatic face 208 and upper prismatic face 210
of the front of float 38 are obscured by upper pump tube 212 and
lower pump tube 214 as shown. The upper and lower pump tubes are
connected at end 216 and are attached at end 218 to their
respective one-way valves, as described above.
FIG. 6 shows the operation of the upper and lower pump tubes. As
array 30 responds to wave 602, floats of array 30 are set into
motion relative to one another. Float 32 has risen and float 34
fallen as they encounter a crest and trough of a wave,
respectively. This causes back surface 48 to assume a position
nearly parallel to front prismatic surface 54 of float 34. The pump
tube being therebetween has been squeezed and its hydraulic fluid
forced to move into hydraulic feed line 66 through valve 64 as
described in the discussion of FIG. 3 above. As float 34 dropped,
float 36 rose, to a lesser extent because of its larger size. Wave
602 is approximately the right size to couple efficiently into
floats 34 and 36. Again, as the floats are set in relative motion,
back surface 70 of float 34 squeezes lower pump tube 74 against the
lower prismatic surface at the front of float 36.
By the time the wave reaches float 38 most of its energy has been
consumed by the absorber array. However, it has raised float 36
slightly and thus set float 36 into relative motion with float 38.
As the back surface of float 36 moves slighty toward upper
prismatic surface 210 of float 38, upper hydraulic pump tube 212 is
slightly deformed and pumps a small amount of hydraulic fluid
through its associated check valve. The low amplitude wave is thus
efficiently converted into hydraulic power.
FIG. 7 shows an alternative means of nonlinearly coupling pairs of
floats making up a power absorbing array taught by the preferred
embodiment of the present invention. In FIG. 7, float 701 has an
upper pin 703 and a lower pin 705 located on the side of the float
near its back plate. Float 707 has mounted on its side a single
action hydraulic cylinder 709, which is associated with an input
check valve 711 and output check valve 713. Valve 711 is connected
at its input end to a source of hydraulic working fluid and valve
713 is connected at its output end to a hydraulic accumulator as
taught in FIG. 3. Single action hydraulic cylinder 709 has a piston
rod 715 which is connected and rigidly affixed to a triangular
plate 717. As float 701 moves relative to float 707, as is shown in
FIG. 7, either upper pin 703 or lower pin 705 will engage
triangular plate 707 and thus depress piston rod 715. This will
cause hydraulic cylinder 709 to pump hydraulic fluid.
The advantage in using a single acting cylinder rather than a
double acting type is that the latter must have a shaft seal so it
can compress on both ends. This makes it much more expensive.
Double acting pistons are also more maintenance prone because the
shaft is exposed to corrosive salt spray.
Functionally, a very slight movement of float 701 will cause only a
very slight travel of piston rod 715. The amount of travel of the
piston rod accomplished per unit of relative motion of the floats
is a direct function of the cosine of the angle generated between
two floats. Thus, as floats enter into greater relative motion,
each additional increment of relative motion produces an
incrementally greater travel of the piston rod. The hydraulic
piston is nonlinearly responsive to relative motion of the two
floats. Because the piston rod will be traveling a greater distance
when the angle between the two floats is greater, a wave of high
amplitude will have to expend more energy to cause greater relative
motion.
This arrangement is described as an alternative to the pump tube
arrangement described above because it may be more suitable for
certain applications of the present invention. Any nonlinear
coupling means, however, will practice the present invention. A
good engineer could certainly produce many alternate drives and
linkages without departing from the scope of the present
invention.
FIG. 8 shows the embodiment of the present invention as illustrated
in FIG. 7 sitting in calm water. Like numbers denote like parts in
both drawings.
Functionally, this alternative means of nonlinearly extracting
power from floats in an array allows a single action hydraulic
cylinder to pump hydraulic fluid regardless of the direction of
relative motion between the two floats. This is much less expensive
than, for example, using two hydraulic cylinders and depending on
each one to pump when relative motion between the two floats is in
a given direction.
Turbine 100 shown in FIG. 3 would preferably be a "Pelton wheel".
This type of turbine is characterized by its ability to maintain
synchronous rpm so long as pressure is constant, but it can
accommodate a widely varying flow rate of water by simply varying
the orifice size of its nozzle. Size of this orifice would
preferably be controlled by pressure in the accumulator. A
servoloop is established to hold exactly a given pressure, such as
100 psi., in the system. This has the advantage of keeping the
hydraulic system independent of the electrical system and prevents
a failure of hydraulic power if electric power is lost.
The generator would preferably be a converter type with a DC
commutator on one end and AC slip rings on the other. This type of
generator is old in the art of electrical power engineering and is
being described in schematic form merely to show its use in
conjunction with the present invention. The DC portion of the
generator feeds a bank of batteries that act as a stabilizer. The
rpm of the generator may be controlled by varying the amount of
mechanical load it places on the turbine. This may be done by
allowing a tachometer measuring turbogenerator rpm to control
generator field current. If the turbine begins to speed up, the
tachometer increases generator field strength. This increases DC
output voltage, increases load on the turbine and brings it back
down in speed to a proper rpm to generate synchronous AC current.
This servo control loop is entirely independent of the rate of
arrival of hydraulic energy.
Finally, the AC portion of the generator is fed to a shore power
grid by means of a variable transformer. This yields a final servo
control loop. The variable transformer can vary the rate at which
power is sent into the power grid. This rate is controlled by the
condition of the battery bank. If the batteries are full and
charging, then AC output to shore is maximized. Thus whatever power
is available in the power station can be transmitted to shore to
the land power grid.
The principle objection to the commercial use of wave generators is
twofold. First, such generators are expensive to build. Secondly,
they are highly inefficient and can not be scaled up efficiently to
generate large amounts of power.
The present invention avoids these difficulties by providing a wave
motor that is designed to be scaled up to any size by building a
plurality of modular units that will interact as a wave trap to
increase the efficiency of the entire collector array. Secondly, by
acting as a wave trap and thus converting approximately 80% of
incident wave energy to useful hydraulic power, rather than the 30%
maximum taught by prior art, the present invention is
efficient.
FIG. 9 shows an isometric view of a typical power generating array
constructed according to the preferred embodiment of the present
invention. This array would be one module of a power generating
system.
Array 903 comprises a plurality of floats. The first rank of floats
913 comprise four floats, each 100 feet.times.100 feet.times.20
feet. Unless otherwise described, all floats in this example are 20
feet thick. The four floats in rank 913 are pivotally connected at
their rear end to the front end of float rank 915. Float rank 915
is also made up of four floats, each of which is 126 feet.times.100
feet. The four floats in float ran 915 are pivotally connected, as
was described in connection with FIG. 4 above to float rank 917.
Float rank 917 comprises two floats, each of which is 156 feet long
by 200 feet in width. Each of the floats in float rank 917 is
connected to two of the floats in float rank 915. Each of the
floats in float rank 917 is also pivotally connected at its rear to
the front of float rank 919, which also comprises two floats. Each
of the floats in float rank 919 is 200 feet.times.200 feet.
It should be noted that this array is a good example of how the
preferred embodiment of the present invention can be scaled up to
simply make a large wave generator.
The floats in rank 913, 915, 917 and 919 form an array exactly like
the array discussed in connection with FIG. 4 above. Each of the
two floats in float array 919 can then be considered as the first
floats on the larger array comprising ranks 919, 921, 923, and 925.
If larger floats were required, the float in rank 925 could be
attached to even larger .Iadd.floats .Iaddend.and the scaling up
could increase to any desired degree. Conversely, if it was desired
to gather power from even smaller waves, then front rank 913 could
be attached at its front end to smaller floats.
Float rank 919 comrises two floats that are 200 feet long by 200
feet wide. Each of these is pivotally connected at its rear to
float rank 921 which comprises two floats each of which is 252 feet
long by 200 feet wide. The two floats in float rank 921 are
pivotally connected at their rear to the single float in float rank
923 which is 400 feet wide and 312 feet long. This float is
connected at its rear pivotally to the float in float rank 925,
which is the terminal float in this array and is 400 feet long by
400 feet wide.
Turbogenerator housing 930 is attached to the upper surface of
float 925 and delivers power to shore through power line 933. The
rear of float 925 is anchored at its rear edges by lines 907 and
909 to two remotely operated winches which are firmly attached to
the sea floor beneath the collector array.
Sea level in this illustration is indicated by dotted line 901.
This collector array is shown individually and, as such, is far
longer than it is wide. In actual operation, a number of these
arrays would be hooked together side by side and their floats would
be pivotally attached to one another. This plurality of float
arrays, all anchored at their rear extremity by winches, would be
very stable and would stay pointed into the direction of wave
motion. For the purpose of this illustration only, a sea anchor 929
is shown attached by line 927 to the front of the collector array.
The purpose of this sea anchor is to hold the front of the array
into the wind.
Functionally, all of the floats in this example are connected by
nonlinear hydraulic pumping means, as were described in connection
with FIGS. 5, 6, 7 and 8 above. These are not shown in FIG. 9 for
the purpose of clarity. It should be understood that any nonlinear
coupling means may be used to operationally connect the floats in
this array to their respective hydraulic pumping means.
The array shown in FIG. 9 would be most efficient in collecting
power from waves having wave lengths of between 100 and 400 feet. A
turbogenerator is placed within a housing 931 on the rear most
float of collector array 925 to minimize power loss due to
hydraulic friction in the hydraulic lines. Float 925 is
considerably larger than a football field and should carry a
turbogenerator on its surface with no difficulty. The purpose of
winches 912 and 911 is to compensate for tidal activity and to
allow the array to ride out a large storm.
The entire array 903 is approximately 400 feet wide by 1500 feet
long. As was mentioned before, all of the floats in this example
are 20 feet thick. A power generating array that would intercept 10
miles of waves would require 132 of these array modules. More
specifically, such an array would require 528 floats that are 100
feet.times.100 feet; 528 floats that were 128 feet.times.100 feet;
264 floats that were 200 feet.times.156 feet; 264 floats that were
200 feet.times.200 feet; 264 floats that were 200 feet.times.252
feet; 132 floats that are 400 feet.times.316 feet and 132 floats
that are 400 feet.times.400 feet. The use of a large number of
identical floats is advantageous because it greatly reduces the
construction cost of each float. Such a collector array, if it used
standard array modules as illustrated by FIG. 9, would also require
264 subsea winches and 132 turbogenerators.
Given typical conditions in the North Atlantic, i.e., wave heights
of from 5 to 15 .Iadd.feet .Iaddend.and wave lengths from 100 to
300 feet, 23.86 megawatts of power would be instant upon the array
module shown in FIG. 9. Of this, 19 megawatts would be converted by
the collector array to usable hydraulic power. If we assume 50%
losses in the hydraulic collecting array and in the turbogenerator
931, then, on the average, the array turbogenerator would put out
91/2 megawatts through power line 933 to the shore power grid.
To give a commercial example, if a generating unit built according
to the preferred embodiment of the present invention intercepts ten
miles of wave front and these waves are of average size for the
North Atlantic (wave height of 12 feet, wave length of 200 feet),
then the total wave power falling on the collector array will be
315 megawatts per mile. This is 3,150 megawatts incident upon the
entire array. The array will capture 80% of this power, or 2,520
megawatts, as hydraulic energy. If the generating facility
associated with the hydraulic power collecting array is only 50%
efficient, and this is a very low efficiency figure, then the
station will generate 1,260 megawatts. This is more than the total
amount of power generated by the largest nuclear power reactor
presently existing in the United States.
In economic terms, large electric utilities charge on the order of
1.85.cent. per kilowatt hour to heavy industrial users. (Houston
Lighting and Power Company, December, 1975). This figure will be
rising over the next few years as power companies are forced to
turn from cheap sources of fuel such as natural gas, to coal and
uranium. At this rate, 1,200 megawatts is worth $22,200.00 an hour.
Admittedly, the power level generated by the station will vary, but
1,260 megawatts is an average figure and, over a year, should
represent the average output of such a generating station.
If such a power station ran 23 hours a day, 360 days of the year,
it would yield 183.8 million dollars worth of power per year. Such
an installation would require 52,800 linear feet of collector
array. Such a collector could certainly be constructed for $10,000
a linear foot. At $10,000 a linear foot, the collector array would
cost approximately $500,000,000. This is less than the cost of a
nuclear power plant of similar capacity. Even if the associated
hydraulic accumulators and generators cost on the order of
$50,000,000 to $70,000,000, such a power generating facility should
be highly cost efficient. The capital cost per kilowatt of the
present invention would be approximately $450. (The current cost
for nuclear plants is approximately $900 per kilowatt). Over a 40
year life with no fuel cost, it is clear that the present invention
would make a considerable profit. Further, its environmental impact
would be far less serious than a conventional or nuclear plant.
The use of such a hydraulic generating array would also yield a ten
mile long strip of calm water. It would function as a floating
breakwater.
It should be understood that the preferred embodiment described
above and the examples given in connection therewith merely
illustrate one way the concept of the present invention may be
reduced to practical form. Many other embodiments will quickly be
recognized by those skilled in the art. For example, a small island
could be completely surrounded with a collector array or a
collector array in the form of a circle could be anchored in
reasonably deep water to produce a calm lagoon. The above
specification and preferred embodiment, therefor, should not be
considered as limiting the invention. The present invention is
limited only to scope of the appended claims and their
equivalents.
* * * * *