Categories of questions:
Physics of ocean waves
LEG’s and WEG’s
Structure of the Vibristor
Structure and purpose of the PMA and CRMFT
Structure and purpose of the FCA
Operation of the Vibristor
Mechanical simplicity of the Vibristor
Environmental considerations of the Vibristor
Q1: What is a Wave Energy Converter (WEC)?
A device that intersects an incoming
propagating ocean wave that absorbs the wave’s kinetic energy and through some
electromechanical mechanism converts the captured energy into electrical energy
that is then harvested from the device. It may be employed in any body of water
capable of sustaining wind induced water waves of sufficient size so as to
efficiently activate the device.
Q2: What is a vertically oriented Faraday
Linear Electric Generator (LEG)?
A Faraday generator is a device that produces
a movement of a magnetic field relative to coils of conductors. It consists of
a fixed component called the stator which may be either magnets or coils of
wire and a moving component called the rotor which may be either coils or
magnets depending on which component forms the stator. If the movement is a
rotary motion, it is called a rotary generator where the stator windings or
magnets form a fixed cage around a rotating inner rotor consisting of magnets
or windings respectively. If the motion consists of a linear array of magnets
or coil windings (rotor) sliding past a linear array of coil windings or
magnets respectively in a vibrating linear motion, the device is known as a
linear generator. Whether the Faraday Generator is rotary or linear, the
induced electric field and current (power) is always induced in the coils which
are known as the armature. The armature can be fixed comprising a stator or
mobile comprising a rotor that is paired with a corresponding mobile magnet
rotor or fixed magnet stator respectively. If one desires a minimum of moving
parts in a water environment, and given that the wave oscillation is a vertical
semi-sinusoidal one, the optimal generator to use is a linear one oriented in a
vertical direction parallel to the direction of vertical oscillation of the
water wave surface.
Q3: How much energy is available in ocean
A considerable amount of energy is available
and it is expressed as the wave energy flux or wave power available per meter
of oncoming propagating wave. The kinetic power (kinetic energy per second
delivered by the wave per meter of wavefront) is proportional to the product of
the square of the significant wave height and the period of the wave. The
approximate formula is: P = 0.5HteT where P is Kw / meter of
wavefront, Hte is the significant wave height, and T is the period
of the wave.
The significant wave height, Hte,
is defined as the average height of the one third largest waves that are
observed during a defined time period that are crossing a particular point.
The total amount of potentially harvestable
energy that can be converted into electrical power from the world’s oceans has
been estimated by the World Energy Council to be approximately 2 Terawatts.
This represents twice the current world electricity energy production.
Extractable ocean wave energy with its high
power density is thought to be the most concentrated, most consistent, and
potentially cheapest renewable energy source.
Q4: What is an omnidirectional energy point
It is a type of wave energy converter (WEC)
that can absorb wave energy from waves approaching the device from any
direction. It does not need any steering mechanism or permanent orientation
toward the waves, and can absorb energy from multiple simultaneous wave trains
intersecting the device from multiple different directions. The ideal point
absorber will absorb energy equally from all directions (omnidirectional) as
opposed to a unidirectional absorber that absorbs from only one direction, or
absorbs varying amounts from different directions. Examples would be a circular
WEC, a line shaped WEC, and a square shaped WEC respectively.
Q5: What is a surface energy attenuator?
Virtually all the kinetic energy of
propagating water waves is found at the surface and near the surface of the
ocean. As the depth of the water decreases, the water particle velocity and
hence the energy in the moving water particles set into motion by the wave
decreases with the square of the depth. To capture the greatest percentage of
energy lying on and at near the surface, one needs a device that can harvest
the kinetic energy from this surface and sub-surface zone of a region, body, or
area of water of arbitrary shape and size and capable of sustaining propagating
water waves. Do this, a surface energy attenuator is used which generally
consists of a multi-device WEC that is laid out in an array configuration
occupying the targeted area of water so that water wave kinetic energy is
harvested from that entire water area as waves propagate through that bounded
region. The individual devices can either be unidirectional point absorbers
that have to have a steering mechanism or must be permanently moored in such a
fashion that the devices always points at least most of the time in the
direction of propagation toward the oncoming wave fronts or they can be
omnidirectional point absorbers such as the LEG Vibristorthat are
not subject to these restrictions. Furthermore, the devices themselves can be
surface energy attenuators rather than energy point absorbers depending upon
the technology employed. Note that harvesting is maximal when the direction of
propagation of the wave is perpendicular to the surface of the WEC facing the
Q6: What kind of WEC is the Vibristor®
This device is an omnidirectional energy
point absorber capable of harvesting the energy of wave trains approaching and
intersecting the device from any direction or from multiple directions.
It does not need a steering mechanism nor
does it have to be pointed in a fixed direction though if it is moored to a
fixed structure it might be.
When used in large arrays, the collection of
devices becomes an ocean surface energy attenuator.
Thus the Vibristor® has characteristics of
both classifications of wave energy converters.
Why is the Vibristor WEC
(Wave Energy Converter) not run in resonance with the waves?
The rotor of the generator consisting of the
Permanent Magnet Array (PMA) is attached to the buoy floatation collar via a
spring and cable at least the upper end of the buoy and possibly by a spring at
both ends of the PMA.
In small versions of the WEC, the metal
spring is replaced by a magnetic levitation device which serves as a “magnetic”
In any of these configurations, the system
will have its own spring constant (the spring constant of the upper spring
only, or the parallel spring constant if both a perturbing force (upper) and
restoring force (lower) spring are used). Note in the case of the magnetic
repulsive “spring”, the “spring constant” varies with the distance of the end
of the PMA from the end braking magnet and hence, unlike natural elastic
non-deformed springs, the spring expansion and contraction is not linear with
the applied force making for very complicated analysis.
In either of the above cases, the above
system will have its natural resonant oscillation frequency; when the incoming
wave frequency (the driving frequency) matches that of the system’s natural
resonance frequency, the heaving motion of the rotor will be greater than one
(much greater than one if the damping factor of this resonant system is low)
wave amplitude, the velocity of the PMA will be greater at resonant mode, and
thus more power will be generated.
Problem #1: Unless the device is located in
certain ocean areas of the world (i.e. – 15 to + 15 degrees latitude, the
Pacific off the Oregon coast, etc., where the wave motion is uniform in height
and frequency, this won’t work. In most ocean areas of the world, the waves are
far from sinusoidal; consist of multiple frequencies and amplitudes that vary
with a wave and height spectrum that vary with place and time. Furthermore,
multiple wave trains emanating from distant discrete widely separated sources
i.e. weather systems propagate at different velocities from multiple different
directions leading to complex wave form patterns that chaotically vary with
time and place and producing varying areas of constructive and destructive wave
patterns in the wave harvesting area.
Problem #2: Each WEC would have to be built
very specifically for one particular location so that the wave frequency and
the resonant frequency of the WEC match and hence the WEC would not be a
standard mass produced part.
Problem #3: If such a device is operated at
resonance, its sliding tube and vertical height for a given sized maximum
operational wave would have to be much larger to handle the resonant heaving
motion or else the device would destroy itself with repeated severe impacts to
the ends of the stator. The braking magnet system could not handle the impact
unless the device was made much larger (a larger height) to accommodate the
increased stroke distance of the rotor.
Problem #4: If the driving wave frequency
deviated even by a small amount from the natural frequency of the large WEC
needed to accommodate the wave amplitude magnification, the efficiency of the
device in terms of generated watts per cubic unit of device volume would fall
Problem #5: For a small WEC with a small
rotor mass, if the damping factor is purposefully not made high enough, the
buoy floatation collar might try to lift itself completely out of the water
overwhelming the upper end braking unit and slamming hard into the lower
braking unit with significant potential damage to the WEC.
Problem #6: For large amplitude, low frequency
ocean waves, i.e. storm generated swells, in order to bring down the natural
frequency of the WEC to match that of the waves, the rotor would have to be
huge in mass relative to the surface area of the buoy floatation collar to be
operated in resonance mode, and the device would be horribly inefficient by
being both out of resonance and by having most of its potential rotor movement
not occurring whenever these large waves for which it was designed were not
Problem #7: Given the situation created by
problem #7, a very large massive rotor will require a huge and massive WEC as
the stator has to be fixed to a fixed subunit of the WEC that has to be at
least 30 times more massive than the rotor in order for the stator fixed
subunit to be relatively immobile relative to the rotor with the passage of the
wave and generate electrical power at a reasonable efficiency. This is a
problem only for floating tethered WEC devices and not a problem if the stator
fixed subunit of the device is rigidly mounted to either the seabed or a fixed
coastline structure nearby.
Problem #8: While it is possible for single
large WEC to have sophisticated computer controlled outboard sensors which
determines the period of the wave in advance of the arrival of the wave at the
WEC to change the resonant frequency of the WEC in response to the particular
incoming wave period, this greatly adds to expense, complexity, and its
reliability especially since several different waves can impinge on the sensor
at once from different directions. This active adaptive system does not lend
itself to low cost small WEC’s arrayed in a large array consisting of many
loss of efficiency in running a large single WEC at off-resonance frequency
relative to the incoming wave frequency is offset by a multi-layer array of
many small WEC Vibristor® devices. No matter what the frequency (period) of the
incoming wave train is, if it encounters a WEC array of multiple Vibristor®
layers, each layer will harvest a portion of the incoming wave energy, albeit
at less than optimal device vibration frequency relative to the incoming wave
frequency, the incoming wave amplitude and energy will be cumulatively
attenuated by the multiplicity of layers, and by the time the wave train exits
the array, most of its energy will have been harvested with a great degree of
efficiency. Thus while the single WEC, Vibristor® included may be a device whose
efficiency may be greatly dependent upon the matchup between the device’s
internal vibratory frequency and the incoming ocean wave frequency, a
multi-layer array is relatively frequency independent and would exhibit high
energy absorbing efficiencies at all incoming wave frequencies (subject to
certain limitations described at other locations in this document – the wave
period cannot be either too short or too long) independent of the internal
vibration frequency of the individual Vibristor® WEC devices.
Q8: What are the advantages of single or
several large WEC’s versus many small WEC’s used in a densely packed
carpet-like array to harness energy in ocean areas with wide ocean wave
Advantages of large WEC’s include: 1.)
Ability to handle extremely large waves; 2) Ability to produce large amounts of
power from extremely large waves; 3) More likely to be used in possible grid
Disadvantages of large WEC’s include: 1) Huge
initial capital costs; 2) Are difficult to deploy and install; 3) Must be used
either singly or in a “wave farm” group where the units are widely spaced
allowing much of the propagating wave front to go past the devices without any
energy harvesting occurring; 4) Difficult presence on the environment; 5) are
terribly inefficient if the large sized waves for which they were designed are
not present at all times; 6) Are very difficult to replace upon device failure.
7) Not suitable for mass production of standard designs since they are designed
for specific sized waves in specific locations.
Advantages of using many small WEC’s in a
dense carpet-like array include: 1) May be used singly or in closely packed
arrays of many hundreds of units; 2) Devices are small in size; 3) Low initial
cost per WEC and total cost is dependent on the number of WEC’s in the array
that is determined by the size and shape of the array; 4) Shape and size of the
array can be designed to fit the specific size and shape of the body of water;
5) Can be used in any body of water with a minimum size sufficient to support propagating
waves; 6) Can harvest useable electric power from extremely small waves; 7) A
large wave encountering a series of such WEC’s can have its energy extracted
over the series of units allowing for a wide range of wave frequencies,
wavelengths, and amplitudes to be used; 8) Easy to install, transport, service
and replace; 9) Very low environmental presence; 9) Effective energy extraction
even with waves that vary in time with respect to amplitude, wavelength,
height, frequency and direction of propagation; 10) Ability to harvest energy
from multiple simultaneous intersecting wave trains traveling from different
directions; 11) Tethering to the seabed or surrounding structures are easier;
12) Can tolerate adverse weather conditions better as a carpet-like array of
smaller WEC’s can float and ripple with large waves propagating through the
array; 13) The WEC would be a standard component and only the size and shape of
the arrangement of deployed arrays would change; 14) An entire wavefront of a
propagating wave can intersect a large array without any areas of the wavefront
being wasted because of the failure of a portion of the wave to intersect a
WEC; 15) The array can be constructed on site rather than requiring transport
of a large and unwieldy structure to the point of deployment, an expensive
process; 16) The magnet-coil structure of the array can be scaled up in
dimensions so that the power producing capability of each WEC, if the array is
located in an area of sufficiently frequent and powerful waves, so that grid
applications become realistic; 17) Small WEC’s can easily be used in “wave
riding” mode and hence operate with a wide bandwidth of available wave
spectrums; 18) Small WEC’s in arrays can act as a sort of frequency multiplier.
Normally when one wavefront intersects one WEC, only one electrical power pulse
is produced. If the array has 8 rows of WEC’s facing the wavefront, 8
electrical power pulses are produced as the wave propagates through one WEC
after another; 19) Small WEC’s in arrays can act as a bandwidth extender; if
waves of different frequencies and wavelength intersect one WEC, only the wave
with the frequency closest to the natural resonant frequency of the WEC will
respond maximally to the wave; however, a series of WEC’s can efficiently
absorb the energy of waves of a wide spectrum of frequencies and wavelengths as
the individual WEC’s do not have to be operating on waves of their resonant
frequency – even if they are not and individually are less efficient, the
summation of all of the energy absorption of the combined effect of all the
WEC’s will act as if energy was extracted at the same efficiency as if any
incoming wave was at the “resonant frequency” of an individual large WEC. The
Vibristor® array of WEC devices operates at a high level of energy extraction
independent of the frequency of the incoming ocean waves (subject to certain
restrictions described elsewhere in this document).
Disadvantages of using many small WEC’s in an
array: 1) The array would cover a larger area of ocean surface to produce a
greater harvesting of electrical energy; 2) Multiple successive layers of WEC’s
in an array could allow such a high fraction of the available wave kinetic
energy to be harvested that the water behind the array would be so depleted of
kinetic energy that ocean turbulence and mixing of plankton and other small
organisms in the ocean food chain could be impaired (solvable – just don’t use
an excessively large number of WEC’s to do too high an energy extraction
What is wave riding mode?
The WEC, being a spring mass system whose
spring constant depends of the individual spring constants of either the upper
perturbing force spring or the lower restoring force spring, or both (with a
K1*K2 / (K1 + K2 parallel spring constant). This spring constant is further
modified by the braking magnet “magnetic spring constant” and motion dampening
end coils that influences the motion of the rotor only when it is being braked
at the end of the stroke at the wave crest and trough. The “magnetic spring constant”,
a complex non-linear parameter, can be ignored for the sake of simplicity
unless it is the only “spring” component in the absence of conventional
springs. The WEC spring mass system has its own natural frequency Ѡz as
compared to the impinging wave Ѡ. (Ѡz =
(ρgA/m)1/2, p=density of sea water (1030 kg/m3,)
g=gravity constant (9.8 m/s2), A= area of floatation collar, m= mass
of the rotor or mobile subunit of WEC (=
mass of PMA + mass of buoy floatation collar + mass of springs etc.). The mass
of the stator attached to the fixed subunit of the WEC is relatively stationary
and is not part of the mass spring system of the WEC.
When Ѡ / Ѡz = 1, the
system will be at resonance with the oncoming wave and for the wave height
(twice wave amplitude) at that frequency, the heaving motion of the rotor will
be at a maximum and a multiple of that wave height (that multiple, the motion
magnification factor, Q, will vary with the damping factor characteristic of
all resonant electromagnetic and mechanical resonance systems).
Unless the LEG and WEC was built for
precisely that location, that is, unless the mechanical resonant frequency of
the WEC was precisely equal to that of the incoming waves, the heaving motion
of the rotor will drop off considerably and theoretically, therefore, the
amplitude of the rotor’s heaving motion will drop off and its velocity during
all points of the wave cycle (except at the minimum and maximum) will also drop
off, with both factors decreasing power output.
One can graph the heaving motion as a
function of the frequency ratio of the incoming wave relative to the natural
frequency of the WEC (Ѡ/Ѡz) and one
will see a peak at the resonant point where the ratio = 1 and whose height will
depend on the mechanical and electrical damping factors of the system (due to
factors such as kinetic energy conversion to electrical energy, friction, air
damping, elastic losses within the springs etc.)
If one proceeds much to the right of the peak
resonant point (the wave frequency that matches the natural mechanical resonant
frequency of the WEC), where Ѡ/Ѡz
progressively increases, there is a sharp drop in the heaving motion of the
rotor (PMA plus the springs plus the buoy floatation collar) and the electrical
power output drops off to zero. This occurs as a result of the natural
frequency of resonance of the WEC becoming so low relative to the high
frequency of the incoming waves which has three consequences: 1. The higher the frequency of the waves, the
more difficulty the WEC has keeping up with the vertical wave motions impinging
on it (unless A was made much larger and m was made much smaller); 2. The WEC
vibrations will fall behind in phase with the incoming waves; 3. The higher
frequency waves are associated with lower amplitude as they are produced by
less forceful driving forces. For instance, wind capillary waves (capillary
waves – waves that initially propagate because of the friction between the wind
and the water surface associated with its surface tension) are high frequency
low amplitude as compared to storm swells (gravity waves – water waves that
propagate because of the restoring force of gravity) that are high amplitude
but low frequency). All three factors
that operate to the right of the resonance peak cause a much smaller amplitude
of vibration of the rotor and a progressively severe decrease in electrical
power output with the amplitude of the rotor, the velocity of the rotor, and
the power generated by the rotor eventually approaching zero as the Ѡ/Ѡz ratio
becomes quite large.
If one proceeds much to the left of the peak
mechanical resonant point where Ѡ/Ѡz becomes
steadily less than one, there is a gradual decrease of the heaving amplitude of
the rotor (one half of the rotor’s total excursion) and it gradually approaches
and equals the amplitude of the incoming wave for a wide range of frequencies
greater than the resonance frequency. The WEC can follow the wave motion at all
wave frequencies greater than the resonant frequency of the WEC and will thus
produce power over a broad bandwidth of wave frequencies. In this mode, the WEC
appears to float on the wave at all points along the waveform including its
crest and trough in a smooth manner, and hence the device is “wave riding” the
What is the range of frequencies that are optimal for the wave riding
mode of operation for the WEC?
Empirically it is believed that it is optimal
that wave frequencies fall into the range where the Ѡ/Ѡz ratio is
at most 1.2 on the upper end and at least 0.1 on the lower end. At ratios higher
than that, the heaving range of motion of the rotor will be less than the wave
height and thus the WEC efficiency will be unacceptably diminished at higher
Empirically it is also believed that any wave
frequency sufficiently below the point where Ѡ/Ѡz ≤
1.2 will produce acceptable amounts of heaving motion of the rotor as the buoy
floatation collar “rides” the wave and hence significant electrical power will
be produced, subject to one limitation described in the next segment. This
upper limit maybe subject to being raised subject to further quantitative
testing of the WEC.
The wave riding mode however has a low
frequency limitation from another cause. We know that Energy = Force x
Distance, and that the time derivative of Energy, Power = Force x Velocity. The
power produced by the rotor is a function of the rotor’s PMA velocity, and the
time derivative of the PMA’s deviation from the mean rest water level for a
driving wave disturbance with a displacement of Z = Zo cos(Ѡt) (assuming the wave
train is starting from a crest at t=0) is the velocity of the rotor VPMA=-ѠZ osin(Ѡt). Hence, the power
developed in the kinetic energy of the rotor is proportional to the frequency.
As a result the electrical energy developed in the Field Coil Array (FCA) will
also be proportional to the frequency (as is expected from Faraday’s Law which
predicts that the power produced is proportional to the speed of the conductor
through the magnetic field). Thus, if
the waves become too infrequent, even though wave height(and amplitude)
increase as wave frequency decreases making more kinetic energy and power
available per meter of wavefront, the
velocity of the rotor will decrease so much that the net effect is a drop off
in the efficiency of the WEC and in the amount of power converted. The rotor
might move a very large distance but the rate of movement will be so slow that
very little power will be generated. For an extreme example, the frequency of a
tsunami is so low that that it will pass through a wave riding WEC with
scarcely a movement of the rotor producing virtually no electricity.
Empirically, it is believed that this velocity effect requires that the wave
frequencies should be sufficiently high so that Ѡ/Ѡz ≥ 0.1.
This lower limit may be subject to further decrease depending upon results of
further quantitative testing.
We define the wave frequency interval where Ѡ/Ѡz is <
1.2 but > 0.1 to be the operating bandwidth of the Vibristor where the heaving motion amplitude of its
rotor and PMA is at least equal to or greater than the amplitude of the driving
wave. That is the interval on the plot of rotor heaving amplitude versus Ѡ/Ѡz where the
magnification factor, Q, is ≥ 1. Note that if Hz is the
heaving amplitude of the rotor and the PMA, Z=Zocos(Ѡt), and Zo
is the amplitude of the oncoming wave that is a function of the force that
produced the wave, then Hz = QZocos(Ѡt). Q itself is a
function of Ѡ/Ѡz, the
damping factor Δ, and the force of the wave exerted against the underside
of the circular floatation collar Fc . Fc is a function
of Hte and hence, Fc is also a function of the wave
amplitude. Thus, Q = f(Ѡ/Ѡz, Δ,
Why is the WEC run in wave riding mode?
Two or more small low cost standardized WEC’s
intersecting an oncoming wave train in succession can be made to absorb as much
energy as a single large expensive custom made WEC.
A small wave riding WEC can oscillate in sync
with virtually any wave train, even jagged non-sinusoidal wave trains caused by
rough weather or waves coming from multiple directions.
If one defines useable incoming wave
bandwidth as the bandwidth of waves that can be used to harvest useable
electric power by the WEC, an array of WEC’s of just a few rows can harvest the
energy over a huge range of incoming wave frequencies.
One can accommodate oncoming waves of large
amplitude by using rows or arrays of WEC’s sufficient in number to absorb and
harvest efficiently a reasonable percentage of the energy contained within
these waves with the capability of markedly attenuating even large waves
propagating through the array.
The one problem in using multiple WEC arrays
in absorbing the energy of waves of virtually any frequency and amplitude
(other than from severe storms) is that it might absorb too much energy causing
very still water in back of the array which might produce environmental
concerns if too many small WEC’s were used within a given area of the ocean.
These concerns involve lack of sufficient water turbulence created by wave
action caused by overly efficient wave energy attenuation and extraction which
has the consequence of interference in the movement of plankton which could
negatively impact on the ocean food cycle. One avoids this scenario by keeping
the level of energy extraction to below a certain point to insure that some
wave action persists behind the array. This is done by limiting the size and
depth (number of rows) of the array.
In intense storms with extremely large waves,
if a series of waves of very large height happen to come and intersect the
device at the resonance frequency of the device, especially if it is a single
large WEC and not an array, you might get a situation like the Tacoma Narrows
Bridge in the state of Washington which destroyed itself in 1941 when it went
into a resonance vibration mode initiated with wind currents.
Q12: How can too much energy be prevented
from being extracted from propagating wave fronts intersecting the array and
thus prevent too much energy from being removed from the ocean surface and
Making sure the size of the array is small
compared to the body of water in which it is placed.
Making sure the size of the array is small
enough to not be overly efficient extracting energy from the waves of size most
likely to be encountered in that location.
Designing the array so that the maximum
number of rows of small WEC’s that face the propagating wave fronts is such
that the product of the number of rows and the maximum stroke distance of the
rotors of the individual WEC’s is no more than 75% of the significant wave
height of waves most likely to be encountered in that area.
If waves propagate in a given location
predominantly from one direction only, the depth of the array can be made much
deeper than the width of the array so that at the far end of the array, diffraction
of the surrounding wavefront that did not intersect the array will bend around
the rear end of the array preventing calm water behind the array.
If the waves are propagating from one general
direction, a strip shaped array can be used where the long axis of the array is
much greater than the width of the array and it is oriented approximately
perpendicular to the direction of wave propagation. Wave diffraction effects as
described above will prevent the problem of a calm water region from forming.
If the array is attached to a fixed coastline
structure such as a seawall, the calm water turbulence problem will not occur
and in fact will be a significant advantage in protecting the attached coastal
structure against large waves from impacting it.
Q13: How can an array of WEC’s prevent
coastal structures from being damaged?
A strip array can be tethered rigidly or by
flexible means to a sea wall to protect it and increase its life expectancy.
Such an array can also be floated off shore
close to a beach to decrease beach erosion from ocean waves.
A circular ring shaped array surrounding a
central structure like a marine wind generator will protect it.
The mechanism behind all such applications
would be that attenuating the kinetic energy of ocean waves impacting upon
marine exposed structures would lead to lessening the damaging impact of such
waves leading to longer lifetimes and decrease maintenance issues.
The effect would be to have an
“electrokinetic sea wall” (patent issued) that would create electrical power
from the attenuated harvested energy as a useful byproduct.
Q14: In a large array of WEC’s, how can one
prevent some of the WEC’s further into the interior of the array from becoming
progressively inefficient in wave energy extraction the further back into the
array that they are located?
Method 1: employing only a maximum number of
rows of WEC’s in the array so that the attenuation and subsequent harvesting of
wave energy would be significant even for the last row of WEC’s encountering a
wave still having enough energy as it passes through it. As an example, instead
of having a circular array of WEC’s where the WEC’s in the interior of the
delay would see the most attenuation of the wave and therefore would be the
least efficient in energy extraction, one could have a ring array and leave out
the WEC’s in the central area of the array.
Method 2: With each successive row, decrease
the size of the array as each row would encounter a wave of progressively
smaller amplitude and energy flux as the row before it would remove a certain
amount of energy from the wave. Thus efficiency of the device in terms of power
generated per unit volume or weight of WEC would remain fairly constant. The
problem with this approach would be that the WEC would have to be manufactured
in many different sizes and this is less optimal for the mass production of a
low cost standardized device with great flexibility of use as is desired.
Q15: How does an array of Vibristor WEC’s
act like a frequency multiplier?
Small WEC’s in arrays can act as a sort of
frequency multiplier. Normally when one wavefront intersects one WEC, only one
electrical power pulse is produced. If the array has 8 rows of WEC’s facing the
wavefront, 8 electrical power pulses are produced as the wave propagates
through one WEC after another. In fact, if a wavefront intersects n rows of
WEC’s or n WEC’s one behind the other in a strip, n power pulses will be
generated from that single wave front. These multiple power pulses are than
filtered and combined into one master power output source by the Power
Collection Circuitry (PCC) of the array.
If the WEC array is shaped so that it is
omnidirectional, that is like a circle or a ring, then no matter from what direction
the wavefront approaches, the number of WEC’s it intersects will produce the
same number of power pulses per wave front.
If the WEC is shaped so that it is more
efficient in one direction, the number of power pulses produced will depend on
the angle of incidence of the wavefront with the array. For instance, a strip
of WEC’s of depth n of width one WEC will emit n power pulses per waveform if
the waveform is traveling parallel to the long axis of the strip but only one
simultaneous pulse from each of the WEC’s (summed of course into one much
larger pulse) if the wavefront intersects the strip array traveling
perpendicular to its long axis. A square n x n matrix array of WEC’s will
produce n power pulses if any wave comes from one of 4 directions that are each
perpendicular to the intersected face of the array and will produce a varying
number of pulses of different sizes if it comes from any other direction.
Often in oceans, there are usually multiple
simultaneous wavefront propagating in numerous different directions especially
if there are several active intense weather systems active in some part of the
ocean. The energy streams propagating as the group velocity of the various wave
fronts entering the array from different directions set up an interference of
constructive and destructive wave patterns within the array causing electrical
power pulses to be generated in a somewhat chaotic fashion with respect to both
magnitude and frequency which are of course filtered and summated into one
Thus the array of small WEC’s is best suited
to handle the chaotic pseudo-sinusoidal wave patterns that comprise the ocean
surface and sub-surface wave energy layer. These pseudo-sinusoidal and often
completely chaotic wave patterns might be very difficult for a single larger
sized WEC to handle efficiently in a device in the wave riding mode and
virtually impossible for a device trying to operate in the resonance mode.
However, an array of small wave riding WEC’s with its broad response bandwidth
and with each individual WEC producing its own power pulse train output will
convert the majority of water surface fluctuations into useable output power
pulses. The array should accomplish this even if these surface fluctuations are
standing waves with their constructive and destructive interfering waveform
patterns or if the waveforms are totally non-sinusoidal and chaotic. The result
would be a fairly high variable frequency output that can be filtered and
summed together as one power output by the PCC. Useable significant power would
be produced no matter what the surface conditions of the sea were.
Q16: How does an array of VibristorWEC’s act like a bandwidth extender?
Small WEC’s in arrays can act as a bandwidth
extender; if waves of different frequencies and wavelength intersect one WEC,
only the wave with the frequency closest to the natural resonant frequency of
the WEC will respond maximally to the wave; however, a series of WEC’s
operating in the wave riding mode can efficiently absorb the energy of waves of
a wide spectrum of frequencies and wavelengths as the individual WEC’s do not
have to be operating on waves of their resonant frequency. Even if they are not
in the resonant mode and individually are less efficient, the summation of all
of the energy absorption of the combined effect of all the WEC’s will act as if
energy was extracted at the same efficiency as if any incoming wave was at the
“resonant frequency” of the individual WEC’s.
How is the WEC protected against large incoming waves?
At either end of the LEG there is a
mechanical electromagnetic braking system that damps down and extinguishes the
excessive vertical motion of the PMA and prevents it from slamming into the
ends of the LEG as a result of a very large wave intersecting the device.
How is the braking accomplished?
The braking unit consists of three
components, a braking coil, an end-braking magnet, and in large unit LEG’s, a
stiff spring. As a result of an excessively large wave whose amplitude is
higher than for what the unit was designed for, the PMA will have considerable
motion as it approaches either the upper or lower end of the magnet sliding
tube and will slam into the ends of the sliding chamber causing a possibly
violent inelastic collision that can damage the structure, shorten its
lifespan, and in the least, waste kinetic energy turning it into heat rather
As the PMA reaches the end of the sliding
tube, it encounters first, it reaches the large wire gauge end coil which can
be either shorted out or connected to the Power Collection Circuitry (PCC) so
as not to waste this kinetic energy in the moving PMA. If the coil is shorted
out, the braking action is greater but the energy is dissipated as unwanted
heat wasting the energy. The coil can also be replaced by a long ring of
conductor – copper or brass would do. No matter what the arrangement, the large
current flows induced in the braking coil, through Lenz’s Law, induces a back
EMF force that opposes the motion of the PMA and brakes the moving rotor.
If the PMA is not stopped by the end braking
coil, the end-deflecting magnet of the PMA will approach the end-braking magnet
of like magnetic polarity causing a repelling magnetic field to build up as the
field is compressed between the two magnets which will stop the remainder of
the motion of the PMA. A braking spring can be used as a third component to the
Two benefits of the end braking are: First,
the remaining kinetic motion of the PMA ends up being temporarily stored in the
end repulsive magnetic field and then as the PMA slows, stops, and is repelled
in the opposite direction, the stored energy is restored as kinetic energy of
the PMA moving in the opposite direction where it can be converted into
electrical energy by the FCA (Field Coil Array). Second, as the PMA approaches
the end-braking magnet, any magnetic flux lines that have escaped the PMA and
the surrounding FCA from getting past the end deflecting magnets will get
deflected back into the PMA by the repulsive field of the end-braking magnet
instead of being lost into space thereby increasing the efficiency of the
device. Thus as the PMA approaches the end-braking magnet, flux leakage from
the PMA gets reduced considerably.
In large WEC Vibristor units that handle very
large waves, to stop the occasional rogue wave, any PMA kinetic energy that is
left after the first two mechanisms will be stopped by a stiff spring that lies
in front of the end-braking magnet that will finally bring the PMA to a stop
before it crashes into the end-braking magnet. Like the repulsive magnetic
field, the spring also will store kinetic energy of the PMA and restore it
later to the system for energy conversion while helping to keep the encounter
of the PMA with the end-braking magnet a completely elastic collision with all
of the advantages outlined above.
The spring component of the end-braking unit
is not required in small devices with small displacement stroke distances as
the end-braking magnets itself interacting with the approaching end-deflecting
magnet on the PMA acts as a “magnetic spring” that in association with the
damping effect of the end coil windings, all act as a damped mass spring
Are there weather conditions where the array should be shut down?
Extremely intense weather conditions will
call large waves that will surpass the ability of the array to safely generate
electric power. It should be shut down under such weather conditions.
While the WEC’s in the array are small, if
they are tethered together in a flexible array, the array can ripple in shape
as the waves propagate through it providing stability for the array even if
waves larger than what it was designed to operate with intersect the array. In
this respect they would have more tolerance to wave size than a single fixed
array. However, past a certain point, the array should be shut down.
If the WEC’s are rigidly fixed to a coastal
structure such as a linear array fixed to a seawall, in rough weather, the
WEC’s are designed to be water tight and resist submergence by large waves.
Storm surges for fixed rigidly tethered waves
along the coast could be problematical as they might require the WEC’s to be
under water for hours at a time which will require engineering considerations
that will have to be dealt with.
Quite important with regards to device
shutdown is that electrically, the array as a device has to be turned off in
the event of an impending major storm and this is done by using a remote
internet controlled switch from a distance. A single large WEC also would have
to have this same feature.
However, a large WEC has to be mechanically
stabilized against large waves to prevent a large magnet from repeatedly
impacting against the braking unit which in spite of the braking unit, might
lead to damage in a prolonged intense storm. This is especially true if there
was any possibility of the device operating in a severe storm with the chance
that it can encounter a train of very large waves coming in at the resonant
frequency of the device.
A small WEC with a rotor and PMA of small
size, even with extremely large waves, would have a relatively small kinetic
energy because of the rotor’s small mass, and thus would be much less likely to
sustain damage and the PMA’s energy can be damped safely on a repeated basis by
the end braking unit operating on the PMA by the repulsive end braking magnet,
the power absorbing Lenz EMF barking effects of the end braking coils, and a
braking mechanical spring. Hence, it is anticipated that an array of small
WEC’s can ride out an intense storm successfully if the tethering device
connecting the WEC’s have sufficient tensile strength against breaking.
The fact that the individual WEC’s will be in
wave riding mode with the buoy floatation collar floating in synch with the
wave surface rather than in resonance mode will also make the chance of damage
to the individual WEC’s less likely.
Q20: How can a large PMA be stabilized
against excessive and dangerous motion during an intense storm or when the
device is needed to be shut down for maintenance repair work?
The individual coils can each have a control
circuit that can short out the coils by remote control or by direct wire
control so that the PMA will encounter huge back Lenz EMF forces when it moves
against every Field Coil Array (FC A)
In effect, the entire FCA upon command of a
shorting electrical signal, becomes a braking coil to stabilize the PMA against
Q21: How is an array shut off in the event of
impending violent storms?
There would be a remotely controlled switch
that via the internet can be turned on and off to activate the output of the
PCC circuitry output for each WEC in the array.
If the WEC device was large with large
magnets capable of producing large power pulses, a switching circuit could be
used to short out all the coils of the WEC which would stabilize the magnets
from moving significantly during an extreme weather event. It too would be
remote controlled. Haphazard movement of large magnets in the device which in
itself could damage the device would thereby be prevented.
In either case, a switch to shut off the PCC
final output would also be needed to prevent any errant power pulses from being
on the WEC or WEC array power output that would cause safety issues.
Q22: How is an individual WEC replaced in the
event of electrical or mechanical failure?
A large WEC used in a single or few device
wind farm would require an attempt to fix a mechanical or electrical
malfunction while the device is deployed in place as the cost of removing the
device and transporting it to a repair point on shore, or even on a ship, would
be prohibitive. There would also be safety considerations in immobilizing large
magnets in relationship to large coils to prevent unwanted power pulses that
could jeopardize personnel trying to repair such a unit and thus utmost care
would have to be taken to shut off the unit completely and stabilize the
magnets to prevent an errant power pulse.
The preferred option to use a densely packed
array of small WEC’s would allow a WEC to be simply unplugged, removed, and
replace with a new functional device. The malfunctioning device could be
subsequently repaired and returned to service. It would be very easy to switch
off the device either by remote control or manually.
How is the power collected from the numerous WEC’s in an array?
This is done through a hierarchal Power
Collection Circuitry (PCC) that uses modular component circuits of 4 different
varieties that combines multiple AC inputs to form one DC output.
Each of the 4 different circuits can combine
anywhere from 2 two many hundreds of different low level AC inputs (from
sources such as WEC coils) as well as and DC inputs (such as piezoelectric
transducers, solar cells, etc.) and thus a practically unlimited number of
outputs from WEC coils on the same or different devices can be summated into
one output DC current.
All circuits use low powered Schottky diodes
to lessen power loss across multiple levels of diode rectifying junctions.
Circuit #1 is an n phase bridge rectifying
and filtering circuit that produces a monopolar positive output from n number
of low level AC or DC inputs.
Circuit #2 is an n phase bridge rectifying
and filtering circuit that produces a bipolar positive, negative, and ground
outputs from n number of low level AC or DC inputs.
Circuit #3 is a current summation circuit
that sums the current outputs from n number of low level AC or DC low level
sources together to form one summation output current.
Circuit #4 is a voltage summation circuit
that sums the voltage outputs from n number of low level AC or DC low level
sources together to form one summation output voltage.
What is new and unique about these modules
aside from using n number of AC or DC inputs, producing a bipolar voltage
output, and low power Schottky diodes is that each circuit itself can be used
as a component in a hierarchal network of power collection circuits that can
combine an unlimited number of AC or DC inputs into one master power output
making them perfect for collecting the power out of an array of WEC’s each with
a number of coils.
Each circuit can rectify and filter a large
number of input power sources, and its single output can serve as an input to
the next circuit, and thus, many such circuits with all 4 varieties being
present at the same time can have their outputs summed together by any of the 4
circuits to produce one master output and so forth.
example of how this might work is as follows: We have an array of 15 WEC’s that
are in three rows of five each and each WEC has 8 coils servicing a PMA of 4
magnets (2 Structural Magnetic Units, SMU’s). Thus we have a total of 120 coils
producing power that need to be summed up into one master output. We will use a
3 level hierarchal PCC. Each WEC FCA is wired as two groups of four. Each group
of 4 goes through an n = 4 phase rectifier filtering circuit (circuit #1). Each
row of 5 WEC’s has a total of 10 groups of 4 coils producing 10 outputs (first
level of the PCC). These 10 output power sources now have their currents added
together to produce one output current by using an n = 10 source current
summation circuit (circuit #3). This is done for each row (second level of the
PCC). Now we have 3 output sources for the entire array. We can combine these
three inputs in 4 different manners (level 3 of the PCC): a) put these 3 inputs
through circuit #1 (3 phase rectifier
and filter) to produce an output of approximately the same voltage as the
average voltage of the 3 voltage inputs; b) put these 3 inputs into circuit #2
(bipolar n = 3 phase rectifier filter circuit) to produce bipolar positive,
negative, and ground outputs for the entire array; c) sum the currents of these
3 inputs to produce a relatively low voltage high current output for the array
with circuit #3 (n = 3 input current summation circuit) or d) sum the voltages
of these 3 inputs with circuit #4 (n = 3
input voltage summation circuit) to produce a relatively high voltage low
current output for the array. Thus using a 3 tier PCC circuit we were able to
combine a multitude of WEC coil outputs into one master power output from the
array whose characteristics good be changed to suit the application for the
harvested electrical energy.
coils in the WEC’s can be substituted with piezoelectric energy vibrational
energy harvesters producing very low frequency AC or DC power, very low voltage
batteries (DC inputs), atmospheric diode power collectors (so called “free
energy” devices, DC or AC inputs), solar cells (DC inputs), thermoelectric
modules (DC inputs), etc.
How can the impact inelastic collision energy from a large wave be
captured as useful electrical energy?
By three mechanisms: a) storing the kinetic
energy transferred to the rotor and PMA (containing most of the rotor’s mass)
temporarily in the compressed repulsive magnetic field of the end-braking
magnet interacting with the end deflecting magnet magnetic field; b) storing
the kinetic energy temporarily in the spring in front of the end-braking
magnet; c) by braking the magnet through Lenz’s Law with the end-braking coils.
In the case of a) and b), the temporarily
stored energy in the compressed magnetic fields is returned to the PMA as it is
reconverted to kinetic energy which can then be converted to electrical energy
on the next pass of the PMA through the FCA.
In the case of c), the remaining kinetic energy
of the PMA, originally derived from the wave kinetic energy, is converted into
electrical energy by the end-braking coil which can be collected, a process
identical to the conversion of wave kinetic energy into electrical energy as
the PMA interacts with the FCA. However, the amount of energy in the electrical
pulse so collected would be significantly less than the electrical pulses from
the FCA overlying the power producing magnets.
Furthermore, the magnetic field around the
ends of the PMA collapses around the PMA instead of leaking away into space as
the PMA approaches the end-braking magnet which causes an increased
electromagnetic interaction and linkage with the end-braking coil increasing
the braking effect of the coil and the current pulse generated by the coil.
Q25: What are the advantages of a fixed
end-magnet braking system versus the disadvantages?
Advantage: When the PMA approaches the end
magnet braking system coil, the motion of the magnet is considerably slowed
down by the braking coil which converts much of the kinetic energy remaining in
the PMA after encountering a large wave either to heat or if desired into
electrical energy which may be collected and added to the output of the power
magnets interacting with the FCA.
Advantage: Whatever remaining kinetic energy
is left over in the PMA causes is stored in the increasingly compressed
repulsive magnetic field between the end braking magnet and the end deflecting
magnet (or end power magnet) that occurs as the PMA continues to approach the
end braking magnet. At the point the forward velocity of the PMA has completely
been halted, all of the kinetic energy remaining in the PMA has been converted
to potential energy stored in the compressed magnetic field and will be ready
to be released in the wave’s next half cycle for conversion into electrical
power by the FCA.
Advantage: the presence of a mechanical
spring in larger systems assists the function of the end braking magnet because
as the spring is progressively compressed by the approach of the PMA to the end
of the sliding tube, the energy of the PMA is sequentially stored and then
released during the next half cycle as is the case with the end braking magnet.
Advantage: The “collision” with the end
braking electromagnetic unit is completely elastic (unless the end braking
coils are shorted out to produce heat) and the energy of the PMA as it travels
to the end of the LEG slide tube is conserved completely for conversion to
Advantage: Since the end braking magnet and
the entire braking unit is fixed to the much more massive fixed subunit which
holds the stator, the recoil velocity of the stator upon impact of the PMA with
the braking unit is near zero, a desirable situation for more efficient power
In case the WEC goes into resonance with a
series of waves whose amplitude is not only large but whose frequency remains
so close to the natural frequency of the mass spring system of the LEG causing
the possibility of very violent motions of the rotor and damage to the device,
the fixed end braking magnet, coil, and if present, spring, provides sufficient
damping so as the device will not destroy itself. (Note #1: The damping from the spring is thermo-elastic
and is therefore part of the mechanical damping characteristics of the device,
and the damping from end braking coils contribute to the electrical damping
characteristics of the device (whether PMA kinetic energy is dissipated as heat
with a direct short of the end braking coils or as electrical power if the
generated pulse is sent over to the PCC); the end braking magnet essentially
contributes virtually nothing to either damping component.) (Note #2: these
components of the LEG damping are not present constantly – they are active only
when the PMA is in the vicinity of the end electromagnetic braking unit.)
would be the advantages of mobile end braking magnets?
The kinetic energy left in the PMA when a
large wave hit and all of the power could not be attenuated by the field coil array
(FCA) could be changed into electrical power over a somewhat larger bandwidth
of wave frequencies as compared to a fixed end braking magnet.
What would be the disadvantages of mobile end braking magnets?
Increased mechanical complexity with a longer
string that would have to be run through the end-braking magnet and attached to
the PMA at one end and then attached to the end of the stator fixed unit. A
cable would still have to be attached to the buoy collar. This would have to be
done at each end. The mobile end magnet would then have to move with that
spring meaning that it too would have to be attached to the spring in some
Energy is generated only with a large wave,
and most waves except in storm conditions when the device should be shut down,
will not cause sufficient electric power to be generated because the end magnet
would not move enough.
The incremental increase in energy extraction
by making the end-braking magnet vibrate if it were mobile would not be much
more than the electric energy pulse produced by the PMA slowing being slowed
down by the large fixed coils at each end of the rotor slide tube.
The incremental increase in energy extraction
would be less both in terms of amount and cost then if simply another PMA
magnet and more coils were added to the PMA; the PMA would be lengthened by one
more structural magnetic unit of 2 power producing magnets and its pole pieces
with additional coils to keep the polarity of the PMA end poles the same.
You would attenuate somewhat the focusing
effects of the end-braking magnet pushing back the magnetic flux of the ends of
the PMA back into the interior of the PMA for more power production.
You would decrease the braking effect against
the PMA for large waves if the end-braking magnet was mobile and not a fixed
component of the stator fixed subunit.
While a mobile braking magnet would allow the
WEC to be responsive to a range of frequencies of waves (increase bandwidth),
the combined power of the damped wave train generated as the PMA forced the
end-braking magnet to oscillate would be approximately the same order of
magnitude as the one large pulse generated by the PMA being braked by the large
gauged end coils. Furthermore, no matter which method is chosen, the amount of
extra power generated by an occasional wave is just a tiny fraction of the
power being generated with each wave by the PMA. However, nevertheless it is
power that can be captured.
Only one movable braking magnet would be
potentially useful notwithstanding the above disadvantages a moving braking
magnet to produce extra power. However, if both were mobile, non-linear
instabilities such as bucking of the cable etc. would totally neutralize any
power increase and this could potentially develop if both end braking magnets
were vibrating at the same time.
A mobile braking magnet would produce a
damped series of electrical pulses in the end braking coil that would partially
coincide with the electrical impulse produced in the end braking coil just
previously by the decelerating PMA and there could be undesirable interference.
A vibrating end braking magnet would transmit
vibrations to the PMA via their interacting repelling magnetic fields, which
could cause the PMA (though much more massive than the end braking magnet) to
vibrate as it slowed to a stop which is less satisfactory than a smooth
Q28: Are there differences in operation of an
LEG where the rotor is the PMA and the stator is the FCA as is been analyzed
with these FAQ issues versus the LEG where the PMA is the stator and the FCA is
The physics, magnetic field distribution, and
the electrical power output generated are the same between these two variants
of the Vibristor-
The structural mechanical operation is
somewhat different between the two varieties of WEC but the functional
operation is similar.
What is the advantage of an array of WEC’s if one WEC becomes
If one WEC develops an open coil, the PCC
simply ignores the high impedance of that coil and the device operates as
before with some loss of power output because of that defective coil.
If one WEC develops a shorted coil, the PCC
will protect the WEC via its blocking diodes to prevent other coil outputs from
shorting out through the shorted coil thereby destroying the FCA for that
device. As the PMA passes over the shorted coil, there would be a momentary
braking action “bump” but it would be of minor degree as even though the coil
is shorted significantly increasing Lenz back EMF force over that coil, the
large number of coil turns of small gauge wire keeps the shorted current low
(as opposed to the braking coils of large gauge diameter wire and few turns).
If more than one coil of one WEC shorts out
or opens, the same effects as above would occur, but the effects would be more
pronounced, the WEC output and therefore its conversion efficiency would drop
but the device would still be functional.
If the entire WEC, that is its output,
developed an open circuit, nothing would happen because as a result of the PCC,
each WEC is in parallel with all the other WEC’s of the array and hence the
only consequence would be a slight decrease output and efficiency of the energy
conversion of the array but the array would remain fully functional.
If the entire WEC, that is its output,
shorted out, again nothing would happen because as a result of the PCC, each
WEC is in parallel and isolated from all the other WEC’s in the array no matter
what the number of WEC’s were, and no damage or significant loss of power
conversion of the array would occur. In fact, the shorted output would keep the
PMA of the WEC relatively immobile because of the large load current would
stall the PMA from Lenz’s back EMF and largely keep it stationary.
versions of the Vibristor-R, usually small ones with short stroke distance,
where there are no perturbing and restoring force springs and where these
functions are taken over by the “magnetic spring” repulsion and levitation
between the end braking magnet and the end of the PMA covered under the patents
Yes, one of the patent claims covers the
function of the upper end braking magnet performing the function of the
perturbing force spring and the lower braking magnet performing the function of
the restoring force spring. If the Vibristor-R is in a horizontal vibrating
mode, upper and lower springs lose their “upper” and “lower” significance.
Q31: Are there any serious impacts to the
environment using arrays of small Vibristor WEC’s?
If an array is too large in area through
which the wave train propagates, too high a percentage of the impacting wave
will be harvested potentially reducing turbulence in the water below what is
necessary for mixing of food plankton thereby possibly interrupting the food
chain for fish and other organisms.
The problem can be ameliorated by harvesting
no more than 75% to 90% of the energy in a given area of ocean surface and by
having restrictions on the dimensional size of the array. Thus the geometric
dimensions of the array as well as the number of layers of Vibristor-R WEC’s
impacting the incoming waves would be limited.
Because the Vibristor-R has only one moving
part with no hydraulic fluids or significant amounts of liquid lubricant, there
would be no chemical impact on the environment in the event of device failure.
If a single Vibristor-R failed, it would not
sink to the ocean floor as debris to decompose as it would be held in place by
the other WEC’s in the array.
Even if a single Vibristor-R got loose and
sunk to the floor, it is such a small volume of debris that there would be no
Properly designed electrical circuitry would
prevent stray electrical currents from impacting ocean life.
If a large storm destroyed the entire array
and caused it to sink to the ocean bottom, the only chemicals released would be
decomposition products of the copper and the rare earth magnets. Given the
relatively total cumulative amounts of these two substances present, the
environmental hazard would be minimal.
Are there any serious impacts to the environment using single or several
large widely spaced Vibristor arrays, that is, in a “wave farm”?
1) For the
reasons explained in Q32, there would be none except for the fact that the destruction
of a large Vibristor® WEC would produce a large debris field on the ocean floor
but no more than a ship that sunk in deep water with minimal environmental
What are the environmental advantages of using a single large VibristorWEC?
1) No effects
on ocean life and the food chain, plankton, and ocean turbulence.
lubricants, hydraulic fluids.
3) No major
obstruction to fishing, shipping.
4) Its low
presence above the surface of the water will make it relatively invisible at
small distances thus not affecting the seascape appearance and generally not
visible from shore.
What are the environmental advantages of using a large WEC array with
small multiple Vibristor WEC’s?
hydraulic or liquid lubricants to escape.
profile above the surface of the water makes it invisible to viewers from the
likely to break up from large waves in a storm.
4) Will not
sink to ocean floor in even of device failure.
5) Amount of
energy extractable from a given area of ocean surface is adjustable by varying
the geometric size and number of layers of the array.
extraction of energy can be avoided thereby preventing harm to marine life by
interference with plankton and the food chain.
co-existent with fisherman and other users of the ocean.
What are the advantages of other types of types of non-Vibristor WEC’s
both used singly and in arrays?
1) Some can
be used in resonant mode with the predominant wave frequency in the area of
unit can produce an enormous amount of power, up to a MW.
can be very strong.
highest conversion efficiencies, such as the Salter Duck, are linear to rotary
5) They can
handle the largest waves.
6) They can be
fitted to out rigger wave period sensing devices that can change their natural
resonant frequency if they are dependent upon that parameter.
What are the disadvantages of other types of types of non-Vibristor WEC’s
both used singly and in arrays?
unfriendly – problems with navigation, fishing, lubricant spills, high
non-Vibristor® units must be spaced far apart allowing large amounts of the
wavefront and its energy to pass through without any energy capture.
to attach securely to the sea bottom especially with severe storms.
5) Often not
omnidirectional in response and needs a steering mechanism.
complicated, requiring numerous parts, linear to rotary mechanical power trains,
with bearings, gears, hydraulics, or other mechanical structures.
to service and replacement is almost impossible; one defective part will render
a large unit inoperative.
to transport for deployment.
Increased difficulty handling simultaneous wave trains propagating in different directions.
to be custom made and does not lend itself to mass production.
Terribly inefficient at wave lengths other than for which it was designed.
likely to become unstable in a storm with very large waves.
How is the potential electrical power (energy delivered per unit of
time) dependent on the height, period of the wave and the force exerted by the
wave on the WEC and how does that translate into the force exerted on the rotor
and the resultant velocity of the rotor and thus the amount of kinetic energy
of the wave harvested into the rotor?
potential electric power, the wave energy flux per unit of wavefront length, is
proportional to the square of the wave height (or significant wave height for a
random sea spectrum) and the period of the wave.
2) The motion
amplitude of the rotor and the kinetic energy developed into the rotor is
dependent on the mechanical damping factor of the mass spring system of the
Vibristor® and the frequency of the ocean wave relative to the natural resonant
frequency of the WEC.
3) The motion
of amplitude of the rotor and the kinetic energy harvested by the buoy rotor
component is dependent on the amplitude (height) of the wave which is
determined by the magnitude of the original stimulus that produced the wave,
and the force of that given wave amplitude (height) upon the Vibristor® which
is in turn dependent upon the cross sectional area of the buoy collar, the
depth of submersion of the collar, and the wavelength of the impinging wave.
4) In a
random sea wave spectrum, it is the significant height and wave amplitude that
is used defined as the average height (or amplitude = one half the height) of
the highest one third waves transversing the point of observation within a
given time period of observation.
What is the response of vertical linear electric generator (LEG) in a
wave energy converter (WEC) that operates with linear heaving motions to a sine
wave of resonant frequency? Non-resonant frequency? Semi-sinusoidal frequency?
Impulse or square wave input, Standing Wave Input? Multiple simultaneously
arriving wave trains from different directions?
Resonant frequency: Maximal vertical response
of the rotor to the oncoming ocean wave.
Non-resonant frequency: A decreasing of the
maximal vertical response amplitude of the rotor as the wave frequency
increases past the Vibristor® natural frequency dropping down toward zero (the
right of the rotor amplitude vs. frequency curve) and a decreasing of the
maximal vertical response of the rotor dropping down toward the amplitude of
the ocean wave (the left of the rotor amplitude vs. frequency curve) as the
wave frequency decreases from the resonant frequency of the WEC.
The explanation in the next question, Q39,
gives a more detailed explanation of the above.
Semi- Sinusoidal frequency: The WEC will
respond predominantly to the frequency as in # 1 and #2 above that forms the
predominant harmonic of the non-sinusoidal wave.
Impulse or Square Wave frequency: Similar to
that of a Semi-Sinusoidal response, only the higher frequencies will be quickly
damped out by the WEC with no response to these higher harmonics.
Standing Wave: There will be no vertical
response to the standing wave as for any given point in space, the vertical
displacement of the water level remains constant and hence the rotor will not
move. However, there will be harmful drastic pitch motions if the wave length
of the wave approximates the diameter of the collar unless the WEC is sitting
relatively motionless at an anti-node trough in the standing wave pattern.
Simultaneous wave trains coming from
different directions: The resulting wave form hitting an omnidirectional WEC
like the Vibristor® will exhibit chaotic vertical movement that will virtually never
be in resonance with the natural vibrational frequency of the WEC (and if it
is, would the resonance effect would only be transitory). Any summation or
difference frequency formed by the superimposition of multiple wave fronts will
be damped out if greater than the natural frequency of the Vibristor® and the
WEC will act as a wave rider in chaotic fashion if these frequencies are less
than the WEC’s natural frequency of resonance.
Q39: What happens with the vertical
oscillation distance versus natural resonant frequency / wave frequency ratio
graph and why does a wave wider allow operation both at the resonant peak and either
side of the graph; Why does power output of the WEC will drop to very low
levels if it operates at extremely low wave frequencies (i.e. a tidal wave) –
the extreme left of the curve and extremely high wave frequencies – the extreme
right of the curve.
At the wave frequency that matches the
natural resonant frequency of the Vibristor®, the magnitude of the motion of
the buoy collar attached to the rotor will exceed the magnitude of the height
of the wave by a fraction depending on the damping factor of the system. Power
output is therefore a maximum at the resonant frequency of the WEC, equal to
the frequency of the predominant wave impinging on the WEC. At that point the
vertical movement of the collar of the WEC is in phase with the vertical
movement of the ocean wave maximizing the captured harvested energy of the
vertically moving rotor.
At high wave frequencies, the resonant
frequency of the Vibristor® will be much less than the wave frequency and the
WEC could not keep up with the rapid vertical oscillation of the water from the
waves propagating past, and thus the collar will tend not to move nearly as
much as the wave amplitude or not at all. The movement of the buoy collar will
become more and more out of phase with the vertical displacement of the wave as
the wave frequency goes up. Furthermore, the diameter of the collar may be
several times the wavelength of the small wave and the large number of troughs
and large number of wave crests will tend to cancel each other out producing no
net vertical motion. This effect becomes more pronounced as the wave frequency
goes up and eventually the rotor stays stationary and no power is produced.
This limits to some extent the effect of increasing the cross-sectional area of
the buoy floatation collar in order for the natural frequency of the WEC to try
to approach resonance with higher frequency ocean waves.
3) At ocean wave frequencies lower than the
natural resonant frequency of the Vibristor® the buoy collar and rotor will
follow exactly the vertical water displacement of the wave because of its very
low mass. (If the mass was very high, not only would the stator also move in
compensation as per Newton’s third law, but also, the movement of the rotor
might even lag the motion of the wave unless the wavelength of the wave was
very low.) Thus as the frequency continues to drop, the rotor buoy collar will
continue to follow the wavefront water displacement in phase with it. However,
at very low frequencies, while the rotor will displace at the same amount as
the vertical displacement of the impinging wave front, power will go down
because the vertical motion velocity of both the rotor and the wave will go
down leading to less magnetic lines of force being cut by the stator coils per
unit of time causing the amount of power produced to go down. In fact with
really large waves of low amplitude and huge wave length, i.e. a tsunami, there
is no power produced at all because the rotor hardly moves much like a ship
does not feel a tsunami when it is out in the middle of the ocean. Again, the
developed kinetic energy of the rotor which represents kinetic energy harvested
from the wave is proportional to the square of the ocean wave frequency (the
velocity of the rotor is the time derivative of the displacement of the rotor
with the ocean wave vertical distance displacement, and thus proportional to
the frequency of the ocean wave, and hence, since the kinetic energy developed
in the rotor is proportional to its velocity squared (as well as its mass), the
amount of energy harvested in the rotor is proportional to the wave frequency
squared). Note that with a tsunami the ocean wave frequency is very close to zero,
hence, there is virtually no power developed in the rotor. (See also Question
Also, with wavelengths longer than the
diameter of the buoy collar, the loss of vertical displacement linear energy
due to pitch effects is less because of the lower slope of the water level for
a wave of given amplitude.
Q40: How does a PMA using compressive
repulsive magnetic field technology (CRMFT) work?
PMA’s using CRMFT take magnetic fields from
adjacent like repulsive magnetic fields and under great pressure cause them to
be compressed together such that when a stack of alternating pairs of repulsive
magnetic poles are placed one upon another to produce the magnet stack, a very
intense magnetic field radiates out the sides of the stack perpendicular to the
long axis of the stack. If the stack is cylindrical in cross sectional area,
the flux lines radiate outward in a uniform density around the cylinder. Along
the axis of the stack of magnets, areas of N pole regions alternating with S
pole regions with these pole regions extending around the entire perimeter of
If one goes from one end of the PMA to the
other along the curved outer cylindrical surface, one will encounter repulsive
alternating N and P magnetic regions with the fields radiating outward perpendicularly
along the entire long axis of the PMA. This arrangement of magnetic fields is
what allows the FCA coil windings to be placed along the entire length of the
The compression of the magnetic fields into a
confined area formed by the space occupied by the low carbon steel pole pieces
between the magnets is what allows for the intensification of the magnetic
fields seen in this configuration.
Q41: How is the structure of the CRMFT PMA
The basic structure of the CRMFT PMA is the
structural magnetic unit (SMU). It consists of two magnets, usually rare earth
magnets because of their strong magnetization and field formation, oriented
together in such a manner that two of their poles are in repulsive mode that is
NSSN or SNNS. In between each magnet is a pole piece of low carbon 1018 steel
(or similar steel) that contains the repulsive magnetic field that is
compressed and confined to them. Also at one of the ends of this SMU structure
is another pole piece making 2 pole pieces per SMU. If the SMU is the end SMU,
it will have pole pieces at both ends of the structure as well as in the middle
or 3 in total.
The magnets have to be forced together under
great force and this is done by attaching a magnet when it is being installed
at the growing end of the PMA to a pole piece that is threaded in its central
hole and then the complex of the magnet and pole piece is threaded slowly onto
the growing end of the PMA. Once about to be placed in its proper position, a
special type of magnetic epoxy that is extremely strong is placed between the
magnet and the pole piece below it and the structure is bonded together. Hex
nuts at the ends of the PMA can be attached to the threaded rod to make the
connection even sturdier. As result there is a tremendous amount of magnetic
energy stored in a PMA and it would fly apart explosively if it were not held
together in this type of packaging.
The PMA consists of an even number of SMU’s
to insure that the polarity of both ends of the PMA is the same. This is done
to make sure that no lines of force emanating from one end of the PMA would
loop around in air to get to the other end thereby avoiding the coil windings.
The number of SMU’s that can be attached together is theoretically unlimited as
is the length of the PMA subject only by the structural stability of a very
long PMA structure.
The strong large magnets of the PMA are known
as the power producing magnets.
At each end of the PMA, to cut magnetic flux
leakage being wasted by radiation into space without intersection with coil
windings, lie the smaller end-deflecting magnets that are facing both the outer
pole of the end power producing magnet and the pole of the end-braking magnet
that lies at the end of the rotor slide tube. The N pole of the end-braking
magnet would be facing the N pole piece of the last power producing magnet and
the S pole of the end-braking magnet would be facing the S pole of the end braking
magnet and likewise, the same would be occurring for the lower other end of the
PMA structure. Note here an N pole can be exchanged for a S pole and an S pole
can be exchanged with an N pole.
Note that the PMA can be used without the
end-deflecting magnets if a need to do this actually arose.
Q42: How does a CRMFT PMA differ from a
conventional stack of magnets placed N pole to S pole to N pole etc.
In conventional magnet stacks of north poles
of one magnet being stacked above the attracting opposite pole
of the magnet below it, the field lines do travel out the N pole of one end of
the stack, circle around in space, and re-enter the stack through the S pole
end, and then travel through the stack’s interior to complete the magnetic loop
when it enters the N pole end from the interior of the stack.
In the CRMFT PMA the field lines form
localized loops within the magnet stack such that a magnetic field flux line
leaves a N pole and arcs to the two nearest S poles completing the magnetic
line loop within either of the two adjacent magnets. No flux lines go through
all the magnets from one end to the other.
In the conventional magnet stack, one end is
a N pole; the other end is a S pole. In the CRMFT PMA both ends of the stack
are of the same polarity, either both N poles or both S poles.
In the conventional magnet stack, many of the
flux lines emanating out of and into the stack go into and come out of the
surrounding space parallel to the long axis of the stack. These flux lines
parallel to the long axis never would intersect coil windings, while in the
CRMFT PMA, there are hardly any magnetic lines parallel to the long axis,
whatever lines to exit out of an end must curve back and intercept a pole of
opposite polarity within the stack, and thus virtually all the lines of force
intersect coil windings to produce current.
Since in a conventional magnet stack, the
lines radiate out and into only the ends of the stack, that is where the coils
must be located and the coils have to be large, bulky, and long on the stacks
long dimension to capture as many coil flux linkages as possible including many
almost parallel to the long axis flux lines. Even so, many flux lines that are
completely parallel to the long axis escape into space.
In the CRMFT PMA, since the flux lines
emanate to and from the stack along the circular side of the stack, coils that
are smaller in dimension and cost can line the entire length of the stack and
produce electricity with very little leakage into space of the magnetic field.
In the conventional magnet stack, there is no
magnetic field compression that increases flux density interacting with the
coils whereas in the CRMFT PMA, there is repulsive magnetic fields that are
compressed together to greatly increase the intensity of the magnetic field in
the vicinity of the coil windings.
Conventional magnet stacks cannot be made
arbitrarily long by adding an unlimited number of magnets. While initially, two
conventionally stacked NSNS magnets together will have twice the magnetic field
strength and holding power as each of the individual magnets, and three magnets
will have three times as much, there is a point of diminishing returns where
adding on additional magnets will not increase the strength of the magnet stack
end pole magnetic fields any further. The reason: magnetic flux lines travel in
closed loops. The longer the stack, the longer the closed loop. The resistance
of a material to the flow of lines of flux is known as the reluctance and the
lower the permeability of the material to a magnetic field, the higher the
reluctance or resistance to magnetic flux flow (analogous to resistance in an
electrical circuit). While the portion of the loop in the magnet stack is
relatively not affected by the length of the magnet stack because of the magnet’s
internal low reluctance, the half of the loop path outside the magnet stack is
in air that has a very high reluctance and resistance to the flow of magnetic
field lines. This limits the buildup of the magnetic field emanating out of the
end poles to a maximum and adding additional magnets creates a point of
CRMFT PMA structures possess totally
different magnetic flux flow patterns. Such a PMA consists of an pairs of
magnets oriented so that their like polarities are adjacent to each other and
their end poles have magnetic fields that are reach repulsive with respect to
the adjacent magnet poles in those locations. The result is that the flux flow
loops always flow out of one N pole repulsive region between the two magnets
into the S pole of each of these two magnets and in no case is the magnetic
flux required to follow a path longer than somewhat greater than twice the
thickness of each magnet and this holds true no matter how many magnets are in
the stack and how long the PMA is. Thus, PMA’s can be constructed that are many
meters long subject only to the structural strength and stability of the PMA
Q43: Why is the preferred cross-sectional
geometry of the PMA is circular?
For a given sized amount of magnetic material
in a circular disk magnet, a disk of thickness t and radius r with a cross
sectional area of πr2 and curved side area of πr2h:
the curved side area of the disk produces the highest flux density along its
sides compared for instance a magnet with a square cross section but equal
amount of magnetic material.
Circular windings surrounding a cylindrical
magnet stack provides for the shortest coil windings thus conserving copper and
is thus cheaper.
The magnets themselves are cheaper because
they are easier to fabricate.
The inner coil windings can be closer to the
magnet if circular windings are wound around circular magnets.
The produced magnetic fields are more uniform
with no discontinuities or hot spots or cold spots (isolated spots) of severely
decreased or increased magnetic fields.
Q44: How is the CRMFT PMA stabilized?
patented method of attaching and stabilizing a configuration of magnets with
repulsive magnetic fields is used.
Q45: What functions does the pole pieces
serve in the PMA?
Allows a space for the repelling magnetic
field of high intensity to reside instead of the field lines being pushed back
into the interior of the two repelling magnets which could eventually
demagnetize the magnets.
Low carbon steel has a very high saturation
point of 20,000 Gauss (2 Tesla) which is 4 times the saturation of air and
higher than iron pole pieces (1.2 T). Thus the magnetic fields can be
compressed to a higher level resulting in greater field intensities.
With low carbon pole pieces whose thickness
is as thin as one eighth the thickness of the magnet, maximum field intensities
coming out of the magnet pole surfaces can be increased from 0.5 T to 1.0T
achieved in the lab so far, and can easily be increased to 2.0T, the limit of
magnetic field saturation in the pole pieces.
The pole pieces act as magnetic flux lenses
that focus the magnetic flux onto the coils surrounding the PMA (The coils of
the FCA) without the need for heavy ferromagnetic focusing structures.
Q46: What are the end-deflecting magnets and what
is their function?
They are magnets that are smaller in size as
compared to the power producing magnets of the PMA and are located at each end
of the PMA and attached to the PMA power magnet stack with a pole piece.
Their primary purpose is to decrease magnetic
flux leakage out into space and instead reflect these lines of force back into
the interior of the PMA.
The amount of flux leakage into space which
wastes magnetic field lines that can be used to produce electricity is much
less with the CRMFT PMA then with a conventional magnet stack of alternating
magnetic poles. However, even so there still is a sizeable amount of leakage.
If the N pole end of the PMA has added onto
it an additional pole piece and a smaller magnet in a repulsive pole configuration
such that the N pole of this end-deflecting magnet faces the N pole end of the
PMA, almost all of the flux lines leaving the end N pole of the PMA will be
deflected back onto the interior of the PMA.
Since magnetic flux must travel in closed
loops, and since these loops can only flow in two adjacent magnets forming a
pair that we call one structural magnetic unit, the vast majority of the flux
lines deflected from the N pole of the end-deflecting magnet will be bent back
and go into the S pole closest to it that is on the other side of the end power
magnet of the PMA.
In doing this deflection, almost all of the
flux lines will curve back onto the PMA and cut across the coil windings
creating additional electrical power that would have otherwise been wasted from
magnetic leakage into space.
In small Vibristor® units without springs in
the end-braking unit, the S pole of the end-deflecting magnet would also be
repulsed by the S pole of the end-braking magnet, and thus the end-deflecting
magnet would serve the dual purpose of decreasing flux leakage and helping to
brake the PMA in the event of a large wave.
The end deflecting magnets may be omitted if
the magnets in the PMA are large and strong enough and the PMA stroke distance
is relatively short so that a repulsive force of the ends of the PMA can be
produced against the end braking magnets as the PMA approaches the latter with
a large wave while it is still a considerable distance away; this repulsive
force would exert the equivalent of the focusing effect of the end deflection
magnets as the PMA approached the end braking magnet. However, for smaller
magnet PMA’s that are travelling over long stroke distances, the end deflecting
magnets are essential.
Q47: What is the structure of the Field Coil
Array (FCA), the power producing armature of the LEG?
The FCA ideally should consist of coils that
surround the entire length of the rotor slide tube though in smaller less
powerful versions, a smaller number of coils can be used.
There is a defined multiple of the number of
coils used for each Structural Magnetic Unit (SMU) of the PMA (consisting of
two magnets and their associated pole pieces).
A minimum of 4 coils per SMU.
A larger number of coils may be used for very
The number of coils per SMU is intimately
related to the most optimal power production for a given number of coils and
magnets, the efficiency of the power conversion process improves because a
smaller percentage of the windings will be contained in coils that are over
regions of net zero magnetic flux, or regions in which adjacent N and S poles
are contributing to equal opposing amounts of flux intersecting the coil with
no resultant power generation.
Q48: Why is the width of the air gap between
the inner coil windings and the outer surface of the PMA much less critical
than in other generator configurations?
The only component of the magnetic field that
produces power in the coils are those flux lines that are oriented
perpendicular to the direction of movement of the PMA (or the long axis of the
Eventually, these perpendicular field lines
(also called radial, or orthogonal) begin to curve around to approach adjacent
magnetic poles, and field lines traveling in this direction are parallel to the
direction of motion of the PMA (and its long axis). They produce no power in
the coils because of their direction of orientation.
In order for a field line to produce a
voltage in a conductor, 3 quantities known as vectors because direction is
important are required to point in directions perpendicular to each other.
These 3 quantities are the direction of orientation of the magnetic field line
(which for power production must radiate perpendicularly out of the side
cylindrical surface of the PMA), the direction of movement of the PMA (which is
always parallel to the long axis of the PMA), and the orientation of the coil
winding (the cross section of the coil winding is perpendicular to the
direction of motion of the PMA).
Normally, in the conventional configuration
of NSNS magnet stacking, lines that exit out from a magnet perpendicular to the
magnet’s surface curve immediately around to the adjacent pole to complete the
magnetic loop circuit so that a surrounding coil must be extremely close to the
moving magnet’s surface to produce what is known as a coil magnet air gap or
simply air gap to be as small as possible to allow for reasonably efficient
power conversion. This requires expensive precise machine tolerances in
The CRMFT avoids the need for critically
small air gaps because of the compression of the magnetic fields between
repelling poles. This compression accomplished with great force causes the
magnetic field lines to exit from the PMA perpendicular to its surface it
remains in that radial direction perpendicular to the direction of motion of
the PMA for some distance out. Thus, the air gap can be considerably wider than
with conventional magnet configurations with no loss of power generating
This tolerance to air gap width occurs
because it can be shown that the number of perpendicular radial field lines
that intersect a coil winding remains constant at any given cross-section of
the PMA and surrounding coil winding provided that the field lines have not yet
appreciably began curving around in a direction tangential to the long axis of
the coil and coil movement direction as they flow toward an adjacent magnetic
coil. If the number of radial magnetic flux lines intersecting a winding
remains constant, the induced voltage will remain constant for a constant
velocity of the PMA rotor independent of the width of the air gap as long as
the width is a very small percentage of the radius of the PMA magnets.
Of course, even with the compression of the
magnetic fields and the further focusing of the magnetic field lines into the
radial direction by the pole pieces in between the magnets, the magnetic field
lines have to eventually start curving around to adjacent magnetic poles so
that the coil windings cannot be too far away from the PMA or else power conversion
will fall off sharply as the number of field lines remaining in the radial
power producing direction will drop off sharply at significant distance from
The larger the diameter of the magnets in the
PMA, the larger the air gap can be with no loss of power conversion
efficiency. A finite element computer
simulation is being worked out to analytically define the air gap’s optimal
Q50: Are there any limitations on the length
of the PMA?
For reasons to be explained below, there is no
limit other than the structural stability of the means to support a very long
PMA in a WEC device.
A PMA can be theoretically hundreds of meters
long, especially if the largest commercial magnets are used, maximizing the
diameter of the magnets for structural support for a very long PMA and
maximizing the diameter of the central threaded rod of the PMA without
producing a loss in power producing efficiency.
In conventional NSNS magnet stack
configuration, once one gets beyond 10 magnets stacked, there is no useable
increase in the total amount of magnetic flux lines generated by the stack and
thus long magnet stacks of this type are not feasible. With the Compressive
Repulsive Magnetic Field Technology (CRMFT) this problem is entirely eliminated and the total amount of magnet flux lines
available for power conversion is linearly
proportional to the number of magnets used for magnets of a given shape,
size, and magnetization, and this total magnetic flux is distributed along the
sides of the PMA.
Q51: What are the advantages of compressive
repulsive magnetic fields in the LEG?
Eliminates huge long coils at the end of the
Permanent Magnet Array Cylinder (PMA) thereby using less expensive amounts of
Even without the end blocking focusing
magnets, there is significant reduction in end leakage of magnetic flux lines
out the ends of the PMA from flux lines whose direction are parallel or nearly
parallel to the long axis of the PMA cylinder simply because there are vastly
less flux lines in a magnetic circuit comprising a magnetic circuit through the
entire length of the PMA.
The use of powerful magnets may cause
dangerous magnetic fields at the ends of the PMA which might be a problem for
handling the Linear Electric Generator (LEG) when not in use or installed in a
device. This is helped by the end blocking magnets whose fields are much
The use of two much smaller end focusing
blocking magnets at each end of the PMA acts an excellent magnetic shielding
because these two magnets are also used in the Compressive Repulsive Magnetic
Field Technology (CRMFT) configuration and thus virtually all lines of force
are bent backward back onto the PMA to an interior opposing pole virtually
reducing magnetic flux leakage to almost nothing. Note that the flux leakage of
the end focusing blocking magnets which are much smaller and are not used for
power production is of no consequence and is very small in amount.
Further decreasing the amount of magnetic
leakage into space is the fact that the end polarities of the CRMFT PMA are the
same. Hence, any leakage of a flux line out one end can never return to the
other end of the PMA and thus to complete the magnetic circuit which is a must,
it must return to an interior pole of opposite polarity, and it would be more
probable to a nearer interior pole, and thus it must cut across a coil winding.
Note that the effects of #4 and #5 does make for some variation in the maximum
field strength in the various compressive repulsive field regions along the
axis of the PMA cylinder.
A high intensity and relatively uniform
magnetic field is produced in a direction perpendicular to the long axis of the
PMA cylinder other than for small node regions located at the direct center of
an individual magnet’s side.
The compression of the magnetic fields in
regions of like adjacent poles produces a significant increase in the flux
density that cuts across the coil windings in a favorable perpendicular or near
perpendicular direction to the axis of the coils.
Although the sum total of the flux produced
by the standard (NSNS) configuration is equal the sum total of the flux of an
equal number of equally sized magnets in the CRMFT configuration, nearly 100%
of all the flux lines in the latter come out of the circular surface of the PMA
cylinder in a direction perpendicular or nearly perpendicular to the long axis
of the surrounding coils, a condition necessary for optimal maximum power
output whereas in the former standard configuration, a significant number of
lines of flux come out in a direction parallel or nearly parallel to the long
axis of both the field coil array and the PMA cylinder which is not suitable
for coil winding flux linkages and electrical power production.
There are no long regions relatively void of
magnetic flux along the side of the PMA cylinder with the CRMFT whereas there
are with the standard configuration, and whatever the small amount of flux is
present, their direction is parallel to the long axis of the coil array and PMA
cylinder, and only lie adjacent to the cylinder surface – thus they are useless
for electrical power generation.
There is no significant eddy or hysteresis
energy losses anywhere in the magnetic assembly as there are no large
ferromagnetic flux focusing structures present that move relatively to the
linear motion of the magnets.
The magnetic field focusing is done by the
magnets and the pole pieces themselves with no heavy ferromagnetic structures
to do this.
There are no Lenz Law back EMF forces
produced in the pole pieces because they do not move relative to the motion of
the magnetic field.
There are no back EMF forces generated from
the magnet motion other than in the coils themselves as there are no bulky
ferromagnetic structures surrounding the coils in an attempt to focus and
concentrate the flux around the coils as in conventional generators.
In the conventional configuration, as you
stack the number of magnets to a larger and larger number, the incremental
field strength at the ends of the magnets becomes smaller and smaller until
after about configuring a PMA of about 10 magnets, there is virtually no
further gain to increase the PMA length with more magnets. In the CRMFT
configuration, the number of lines of force leaving the side of the PMA
cylinder is more or less constant except for small node areas at the midpoint
of an individual magnet’s thickness, and the average amount of flux per unit
length along the entire cylindrical surface remains fairly constant no matter
how many magnets are added making for PMA lengths that can be meters long. This
is very advantageous to wave energy converters (WEC) employing LEG’s where
large wave energies can be absorbed and converted with long PMA cylinders. The
technical reason for this is that in the standard configuration, as the length
of the PMA long axis increases, magnetic circuit consisting of the path of the
flux through the interior of the PMA and the return path through air (which is
of low magnetic flux permeability or permanence) becomes longer and longer
between the two end poles increasing the reluctance of a good portion of the
magnetic circuit there thereby reducing the flux density and total flux going
from the end N pole to the end S pole. Contrast that with the CRMFT array in
which repulsive pole regions of the PMA cylinder prevent any flux lines from
traveling through the interior of the PMA. Instead, the magnetic circuits are
all local coming out of one N pole repulsive region and quickly back into the
adjacent S pole repulsive region and so forth. Thus no matter how many extra
magnets are added and how long the LEG is, the return air path of the flux will
always be both shorter, relatively the same or almost the same length and the
length of the PMA or number of magnets used will have no significant effect on
the flux output average per magnet and will have no decreasing effect on the
benefit of adding additional magnets to the PMA length. Another way of putting
it, the Permanence Coefficient goes down as the standard PMA grows in length
and number of magnets, and stays constant in the CRMFT PMA no matter how long
it is and how many magnets are added.
The CRMFT array is very scalable both in
terms of going from using very small rare earth magnets to extremely large
magnets and the number of magnets may be at a minimum one pair to a maximum of
many hundreds of magnets with no theoretical maximum, only limits subject to
safe handling, assembly, wave size, and structural stability of the LEG itself
(not the PMA itself which can be made quite stable even with huge diameter and
length scaling). Thus the CRMFT array can be used from miniature structures for
tiny environmental vibrational energy harvester generators to moderate
structures such as buoys to grid scale power generating WEC’s.
If the PMA is in a neutral position relative
to the coils (i.e. a wave node), a small wave that moves the PMA a short
distance in the conventional configuration will produce no power as the
vertical oscillation of the magnets will be completely within the “dead zone”
interior region of low magnetic flux density that occurs along most of its
length at all points except at the ends. In contrast, with the CRMFT array, the
smallest ocean wave vibrational disturbance will produce electrical power.
The use of pole pieces and the compression of
magnetic fields together from repelling adjacent magnetic poles significantly
increases the measured magnetic field intensity (B) that occurs If the along the long axis of the PMA as the
lines of force exit perpendicularly from the cylindrical surface. In the lab
this was measured to be on the order of 80 to 90% (5500 Gauss (G) or 0.55 Tesla
(T) to 9700 G or 0.97 T) with magnets and pole pieces of thickness 2 to 1
respectively. If this effect is maximized using optimally predicted effective
ratios of magnet thickness to pole piece thickness depending upon the
application, the B magnetic field intensities can be increased for the magnets
we used in the research PMA’s (2” in diameter
1” thick NdBrFe rare magnets and
2” in diameter 0.5” thick 1018 steel pole pieces) from about 5500 G (0.55 T) to
about 18000 to 20,000 Gauss (1.8 to 2.0 T), an up to 400% gain, with the limit
being set only by the magnetic saturation permeability of the steel pole
The pole pieces at as magnetic lenses that
direct the flux back onto the coil windings working in concert with the other
design factors that do this.
Normally, the severe repulsion of the
repelling like polarity magnetic fields (which are stabilized by a patent
pending structural assembly array and assembly process) would repel the
magnetic flux back into the interior of the magnets located at the repulsive
magnetic field regions. This effect is extremely delirious and should not be
allowed to happen as it would happen if there were no pole pieces used at all.
If this situation in fact does occur, the magnets will be slowly but
progressively demagnetized with time as the repulsive magnetic force will act
as a coercive magnetic force operating in a direction opposite to the original
force of magnetization of the magnets. This effect is neutralized by using pole
pieces which because of their much greater permeability pulls the flux lines
into them and away from the magnet interior pole regions. Until the pole pieces
are saturated, they can prevent this effect from happening. Thus again, the
optimal design of the CRMFT PMA is such that the ratio of the magnet thickness
to the pole piece thickness results in the pole pieces being saturated. If one
goes beyond that, even with the pole pieces, the magnetic repulsive field
between adjacent magnets will not be able to be confined to the pole pieces and
the magnets could be eventually demagnetized. One can either limit the size of
the magnet thickness or increase the thickness of the steel pole pieces to keep
the pole pieces in magnetic saturation. Note that low carbon steel rather than
iron or other types of steel are used because of its superior high permeability
and saturation characteristics.
Because the magnets travel through the surrounding
coils rather than adjacent to them as in some other WEC’s powered by LEG’s we
have another factor that causes virtually all of the flux lines generated by
the PMA to intersect the coil windings and produce power.
The PMA’s themselves are scalable in arrays
to produce 3 dimensional “crystalline like” matrices because of the unique
geometrical and pole configuration. This structure has been patented.
So far, we have been discussing the CRMFT in
terms of wave energy converting LEG’s. All generators can be used as linear
motors and the characteristics of this magnetic array need yet to be explored
for use in rail guns, linear servo mechanisms and actuators etc.
The CRMFT PMA has so far been discussed as
being used as the rotor in an LEG with the Field Coil Array (FCA) being used as
the stator. The PMA and the FCA can be interchanged to the stator and the rotor
respectively with no change in function.
Because one can use long CRMFT PMA’s in wave
energy conversion as well as any other vibrational energy harvestable source of
energy, as the size of the PMA increases relative to the height of the wave,
the efficiency of the energy conversion will increase toward a theoretical 100%
subject to all of the other physical constraints that would put a limit on the
conversion efficiency but it is clear that very high efficiencies can result.
The shape of the CRMFT PMA is conducive to
its use in long strips or geometrical arrays to disperse wave energy for the
protection of coastal beaches and structures with electrical energy as a useful
byproduct. A patent has been granted for these structures.
When compared to the Halbach magnetic array
in which the total flux of magnetic field as on the top of the array is twice
the flux that would be on either side of a NSNS standard conventional permanent
magnet array with very little flux on the bottom side of the array (assuming
rectangular magnets), the CRMFT is superior because all of the flux is
compressed into a perpendicular or near perpendicular direction of the motion of
the magnets and the long axis of the coils, and this compression causes flux
densities in the region of the coils to be much higher than would be seen in
the Halbach array (estimated at least to be 400% with magnets capable of being
used in the lab, twice that of the Halbach array). Note that many of the flux
lines in the Halbach array flow parallel to the long axis of the PMA and the
coils and thus many of the flux linkages are in effective for producing power.
For that reason, the Halbach array is not used for electrical power production.
In the conventional magnet stacking of
alternate poles, the air gap between the innermost coils and the outer surface
of the PMA is critical – the larger the gap, the greater the diminution of the
magnetic field intensity crossing the inner coil windings and the less the
power output. Furthermore, the further the radial distance from the PMA outer
curved surface, the greater the component of the magnetic field parallel to the
long axis of the PMA (which produces less power as there are less flux winding
linkages created) and this problem because more critical very quickly with the
coil thickness (outside diameter minus the inside diameter) as it is the radial
component of the magnetic field perpendicular to the long axis of the PMA that
cuts across the full thickness of the coil that creates the maximum number of
coil flux linkages that produces the maximum power output. Because the magnetic
fields are compressed and then focused by the magnetic pole pieces to such an extent
that virtually all of the magnetic field lines emanating from the curved
cylindrical surface of the PMA are in the radial direction perpendicular to the
PMA long axis, and because the very great proportion of the field stays radial
and perpendicular to that axis, the size of the air gap is no longer that
critical as the number of flux linkages for a surrounding coil remains the same
no matter what the size of the air gap (that is a reasonably sized air gap from
a fraction of a mm. to several mm, depending upon the diameter of the magnet
and the degree of magnetization of the magnet). Hence the PMA rotor stator
sliding mechanism and interaction can be built more economically to a less
critical precision and dimensional tolerance.
Because in the CRMFT configuration, the
compression of the magnetic fields cause virtually the entire magnetic field as
it leaves the cylindrical surface of the PMA to be perpendicular to the long
axis of the PMA, and it to stay perpendicular to the long axis for quite some
radial distance out. As a result, the field lines begin to diverge toward the
direction parallel to the long axis quite a distance away and they immediately
begin to point again back to the perpendicular direction as the field lines
travel the short magnetic loop quickly to the adjacent magnetic poles instead
of pursuing wide air spaced magnetic loops as per the conventional
configuration. As a further result, even if the coil thickness is considerable,
the direction of the magnetic field lines throughout the coil thickness is
perpendicular to the long axis of the FCA (which is parallel to the long axis
of the PMA) which produces the maximum flux winding linkages and power
production. The thickness of the coils used with the conventional configuration
has to be sharply limited, a limitation that does not occur with the CRMFT
The cylindrical cross-section, though not
required, in most cases is used as the optimal configuration of the CRMFT PMA
as it results in totally uniform and symmetric radial feels emanating out of
the entire cylindrical surface of the cylinder.
If two identical magnets are placed in the
conventional NS attachment configuration, the total space occupied by the flux
lines will be significantly greater than the same two magnets forced together
in the CRMFT mode. The total amount of magnetic flux will be equal in either
case, but in the CRMFT configuration, that flux will occupy a smaller volume,
and hence, the average magnetic field intensity in the region near the magnets
where power producing coils would be located will be greater.
Using materials with a higher magnetic
saturation than 1018 low carbon steel will lead to even higher magnetic field
compression and intensity.
Measurements with and without the end
deflecting magnets using a gauss meter has shown that with the size PMA being
used ( 3 magnet pairs, 2" diameter and 1" thickness magnets),
measurements indicated a 20% increase in the intensity of the peak magnetic
fields when the end deflecting magnets were used. This is over and above the
estimated 200% increase in efficiency of magnetic flux cutting across a given
amount of coil windings as compared to the standard NSNSNS configuration.
If we use just the PMA without the end
deflecting magnets, it is estimated (and this will be shown hopefully
analytically by the computer simulation) that there is a significant loss of
magnetic flush for small PMA's and therefore, the end deflecting magnet is much
more significant for small PMA structures. The explanation is as follows: If each
magnet produces N total magnetic lines of flux, the PMA as a whole produces nN
total flux where n = the number of magnets in the PMA. However, flux only
escapes into space and does from the N pole end of the PMA, goes into space
with most of this flux not intersecting the coils because their direction is
parallel to the long axis of the PMA and when they do curve around to return to
a S pole in the interior of the PMA, it is way beyond the location of the
coils. Thus this represents magnetic flux leakage which impairs the efficiency
of the generator. The amount of leakage remains the same no matter how long the
PMA is and how many magnets are used, because unlike the conventional
configuration of NSNS where all the flux comes out the end of the PMA, in the
CRMFT configuration only the flux from the end magnet comes out as flux loops
in this configuration is only to the adjacent poles and not out into space
except for the end magnet. The use of end deflecting magnets is critical for
short small PMA's such as wrist watches, personal energy harvesters, buoys, etc
but less critical for larger PMA's such as Wave Energy Converters. Reason: (A
semi-analytical explanation) If the minimum sized PMA using 2 magnets produces
a total amount of flux of 2N, and let's
assume that 50% of the flux emanating out of the end magnet that is lost is
N/2, the % loss of flux of the system is
(N/2)/2N or 25% which is significant. However, if the PMA has 10 magnets, n=10,
the total flux is 10N, the amount lost to space at the ends is still only N/2
(as opposed to 50% of 10N or 5N in the conventional configuration), the
percentage leakage is (N/2)/10N or only 5% and an end deflecting magnet is not
really necessary to prevent flux leakage and its effect on the power generation
is nil (though an end deflecting magnet is still useful to help in braking the
PMA with the end braking magnet). It is this arrangement of magnetic fields
that is responsible for an estimated 200% improvement in the magnetic flux coil
winding linkage for magnets and coils of a given size of the NSSNNSSN CRMFT
versus the standard older NSNSNSN technology.
While the CRMFT causes virtually all of the
magnetic flux lines to curve around to the interior of the PMA cutting across
the coil windings producing power, some of the lines further away from the PMA
may curve around in such a manner that the radial component of the magnetic
field perpendicular to the axis of movement and long axis of the PMA (the only
component of the field that produces power in the coil windings) may less than
and even small relative to the tangential field component(parallel to the
direction of motion and long axis of the PMA) in the vicinity of the winding
which produces no power and wastes magnetic flux reducing the efficiency of
conversion. The ratio of the
perpendicular component to the tangential component can be enhanced at points
further out from the PMA in the outer windings of the coil by surrounding the
coils with a thin circular sheet of very high permeable magnetic shielding
Q52: How can you show what number of
successively intersected small WEC’s operated at the wave riding mode be equal
in the ability of a single large unit operating in the resonant mode?
A very large wave will contain a huge amount
of power per meter of wavefront. A LEG WEC would have to have a rotor moving
through at least 3 times the distance optimally of the amplitude of the wave it
most likely was to encounter and perhaps considerably more to take into
consideration resonance matching between the WEC and the incoming wave. The
device can only capture energy of that section of the wavefront that intersects
the diameter of the WEC, so if a large unit has to harvest a large amount of
energy from a large wave for a reasonable efficiency, it has to be of a very
large circumference. If several units
are to be used in close proximity to each other, they still have to be spaced a
reasonably distance apart from each other because of their large size to
prevent collisions thus allowing much of the wavefront to pass between them
without intersecting a WEC. Generally, such a device should be run at a
resonance mode with respect to the oncoming waves expected at that location.
Such units are hard to transport, install, and in the event of mechanical
failure, to replace and are extremely expensive. Because they would be designed
for a specific location to be matched with the prevailing sized waves in that
location, they would be custom made. If waves other than the ones they were
specifically designed for did not occur at a particular time, the device’s
efficiency would drop dramatically. Three smaller WEC’s whose combined stroke
distance is equal to a WEC three times larger, and by placing these WEC’s one
behind the other in close proximity to each other, one can achieve the same
power extraction as with the large unit. Each Vibristor® removes its share of
power from the passing wave and the sum total of the energy removed by all 3
devices would approximate the energy harvested from the optimized larger
Q53: How can small wave riding WEC’s decrease
loss of efficiency due to pitch motion as compared to large WEC units?
1) If the
wavelength of the ocean wave is much larger than the diameter of the buoy
collar, the slope of the wave (change in height of the wave with distance) will
be low which would cause the tipping angle of the buoy collar to be very low
and near zero causing the rotational motion of the collar to be minimal. This
effect is more pronounced with smaller waves as compared with waves of larger
height. With less of the wave’s energy being converted into rotational kinetic
energy, more of the harvested energy is converted into linear kinetic energy.
Note that only the vertically directed kinetic energy harvested in the rotor
produces electric power and there is no contribution from any rotational
component as the LEG does not respond to that type of kinetic energy and indeed
its operation may be hampered if there is too much pitch rotation to the
movement of the buoy floatation collar.
for a given wave height and wavelength, the diameter of the collar should be
long enough so that there are usually two wave crests under the collar at all
times minimizing pivoting rotational energy and maximizing vertical linear
3) Note that
for one peak to be under the collar at any one time you have the maximum amount
of linear vertical displacement kinetic energy but you also have the maximum
amount of pitch rotational energy as well. However, if you have two wave peaks
and one trough under the collar, one peak is cancelled out by one trough but
you still have a net gain of one peak of vertical motion while the two peaks
together cancels out the rotational component.
if the buoy diameter exceeds many wavelengths of the wave, there is little linear
vertical motion as all of the wave peaks are cancelled out by the wave troughs,
which is the situation of a very large tanker or cruise ship being relatively
motionless even with sizeable waves of considerable amplitude.
Q54: What applications exist for the
Any application that involves a linear
vibrational source of kinetic energy.
Sample applications: mountain bike charger,
personal electronics charger, animal migration GPS power source, emergency
boating power source, ocean powered navigational and instrumented buoys,
electrokinetic coastal protection arrays, electromagnetic shock absorbers,
vibrational energy harvester circuit component for powering low power
electronic circuits, sensor power sources, harvesting energy from vibrating
buildings, car braking surfaces in front of toll booths, ocean powered mines,
and most importantly, grid scale electrical energy harvesting from the world’s
The device can be used in reverse – an
electric signal is provided to the coils causing a magnet to move or if the
magnet is stationary, the coil to move – audio loudspeakers, linear motors,
rail guns, linear actuators and stamping devices, crowd control sound weapon.
The Vibristor® because of its scalability
both upward and downward in size as well as the numerous applications in which
it can be used can be described as a platform technology.
Q55: How can the Vibristor® be scaled upward
By increasing the thickness, diameter of the
magnet, and hence the volume of each magnet: Power increases with the
dimensions raised to the 3.5th power.
The N magnetization factor (energy product in
Mega gauss-oresteds can be increased from the N42 level (in the prototype) to
N55, the magnets with the highest possible commercially available rare-earth
magnet magnetization (scale runs from N1 to N70).
The number of magnets in the PMA (SMU’s) can
be unlimited making for stacks that are up to many, many meters in length.
Using the largest magnets with the highest
magnetization levels and very long PMA’s can produce very large WEC’s which in
itself may be used in multiple device closely packed arrays making grid scale
Q56: How can the Vibristor® be scaled
downward in size?
By scaling down the geometric dimensions of
the magnets and associated coils to produce Vibristors small enough to allow for small scale energy
harvesting devices such as human motion energy harvesting devices.
Even smaller downscaling will allow the Vibristor®
to be used as a circuit component that can power sensors and low power
electronics in areas of the environment where vibrational energy sources are
Theoretically, the technology could be scaled
down to MEMS (micro-electromechanical systems) dimensions.
Q57: How is the magnetic field of the PMA
radiating across the FCA made more intense?
By using larger diameter magnets and pole
By using the thinnest possible pole pieces
with the optimal ratio of the magnet thickness to pole piece thickness. Note
the pole pieces will be such so as to prevent the compressed repulsive magnetic
fields from supersaturating the low carbon steel ferromagnetic pole pieces
forcing the repulsive magnetic fields back into the interior of the adjacent
magnets which will cause the magnets to slowly demagnetize.
By using end-deflecting magnets at the end of
the PMA to deflect any magnetic lines of force escaping into space back around
onto the PMA magnetic poles thereby intersecting the coil windings in the
By using a cylindrical cross section for the
PMA, the distance across which a given amount of flux lines radiate outward
from the PMA from one repulsive magnetic field region is minimized and kept most uniform as opposed to other
geometric shapes. Total flux / area through which the flux radiates = flux
density (field intensity). Also, flux density varies with the radius of
curvature of the region through which the flux radiates and the cylindrical
surface of the PMA has a constant radius of curvature at all points on its
Q58: How can the windings comprising the FCA
surrounding the PMA be made more efficient?
1) The inner
windings of the coil are of thinner gauge and therefore there are more turns in
the region of the highest intensity of the magnetic field thereby increasing
the voltage produced in the inner windings.
2) One uses
an increasing number of coils for each structurally magnetic unit as the
thickness of the magnets increases.
relationship between the length of the SMA and the number of coils per SMA
occurs because as n goes up, that is the number of coils per SMA goes up, the
fraction of the coils that are over equal but opposite amounts of magnetic flux
decreases (only two coils are ever over an equal amount of N and S directed
flux) goes down, thereby causing the sine wave output to gradually shift to a
square wave resulting in a higher duty cycle train of half cycles which when
rectified increases output efficiency, output, and decrease ripple voltage.
Q59: How is the produced electrical energy
collected from the WEC’s? (PCC)
The power output from each coil of the FCA is
collected along with other coils through an n-phase bridge rectifier circuit, a
current summation circuit, a bipolar n-phase bridge rectifier circuit, or a
voltage summation circuit to form one power output from one WEC.
The power output from all of the WEC’s of
each row of the array is combined together at the next level using the above 4
The power output from each of row of the
array is combined together at the third level of collection using the above 4
Q60: How is the produced electrical energy
transmitted from the WEC’s
cables running to shore that can be as long as 80 km. for AC and 125 km. for
2) If the
array is adjacent to a seawall, the cable running out of the array can run
along the sea wall.
Q61: How can the produced electrical energy
be stored after it is produced?
Q62: How is an array of WEC’s structured?
configuration, dual units.
2) Strips of
single or dual layers of units.
shaped arrays – square, circular (most optimal), rectangular, polygonal.
to a large fixed floating heavy structure (“boat mass”)
Q63: How is a single WEC or array of WEC’s
2.) To the
3.) To piers,
bulwarks, and sea walls.
4.) To off
shore wind farm turbines.
5.) To each
other in arrays.
flexible or rigid connectors.
Q64: How is the efficiency of the WEC
1) There are
several different types of efficiency that are of relevance.
2) First: Device Energy Harvesting Efficiency: Kinetic
energy developed in the rotor divided by the energy of the area of ocean
surface beneath the floatation collar.
Electrical Energy Conversion Efficiency: Electrical Energy Output divided by
the kinetic energy developed in the rotor.
Total Device Energy Harvesting and Conversion Efficiency: Electrical Energy
Output of the device divided by the energy of the area of ocean surface beneath
the floatation collar.
Total Array Energy Harvesting and Conversion Efficiency: Total Electrical
Energy Output (= to n times the Device Electrical Energy Output, assuming an
array of n devices, each with the same output) divided by the total ocean
surface area covered by the array.
Device Power Harvesting Efficiency: Mechanical power developed by the rotor
divided by the power present in the wavefront distance intersecting the device.
7) Sixth: Electrical Power Conversion Efficiency:
Electrical power output of the WEC divided by the mechanical power developed in
Total Device Power Harvesting and Conversion Efficiency: The electrical power
output of the device divided by the power of the wavefront intersecting the
Total Array Power Harvesting and Conversion Efficiency: Total Electrical power
output of n devices of an n device array divided by the Total Wavefront power
entering the array.
10) From a practical standpoint, the Total Device
Power Harvesting Conversion
Efficiency and the Total Array Power Harvesting and Conversion Efficiency are
the two most used.
Q65: How is the mechanical complexity of the
Vibristor® compared to other devices?
simple mechanically with only one moving part, the buoy collar rotor structure.
2) No gear
trains, hydraulic drives, slide bearings, rotary generator components.
3) May be
mass produced with low cost off the shelf components.
4) The energy
harvesting component (the floatation collar), the prime mover (the rotor) all
moves linear, usually but not necessarily in a vertical direction as one single
floatation collar and rotor directly covert kinetic mechanical energy into
Q66: In summary, what are the most important
characteristics of the Vibristor® Linear Electric Generator?
moving part, the buoy collar-rotor structure.
energy harvesting and direct conversion of harvested mechanical energy into
electricity all with a single action.
interactions between the rotor and the stator of the LEG.
4) Ability to
be deployed by the hundreds or even thousands in arrays.
deleterious environmental impact.
6) A new type
of power generating magnetic field configuration (compressed repulsive magnetic
field technology) that can be up to 200% more efficient in producing power.
bearing levitation technology.
magnetic fields without heavy ferromagnetic armatures.
magnetic, and mechanical elastic braking technology.
10) Off the
replacement and serviceability for maintenance.
12) Does not
have to operate at resonance with ocean waves.
13) Can be
used in wave riding mode.
capable of extremely high efficiencies of energy extraction.
dimensionally from huge devices down to tiny devices.
from rotors with just two magnets and four coils to devices that are many
meters long with hundreds of magnets and coils.
17) No liquid
lubricants or hydraulic fluids.
18) Can be
tethered to anything – bulwarks, seawalls, each other in arrays, freely
floating, seabed, structures attached to the seabed, massive floating boat-like
19) Arrays can
be of any size or of any geometric shape suitable to fit the particular area of
ocean where deployed.
20) Ability to
continue operation even if part of the WEC is non-functional (open or shorted
coils, non-functioning electronic circuits etc.)
ability to be shut off in anticipation of maintenance or storms.
LEG’s can be of any arbitrary length up to including very long devices
containing hundreds of coils and magnets.