Note: Descriptions are shown in the official language in which they were submitted.
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Mobile system for generating electricity from water currents
FIELD OF THE INVENTION
This invention relates to modular systems for producing electricity from the
kinetic
energy present in flowing water.
BACKGROUND
"I'he renewable energy sources are important in order to guarantee a
sustainable power
production in the future. Hydropower is the largest and the most applied
renewable
energy source in the production of electricity. Today conventional hydropower
is
constrained by land use, environmental concerns and high up-front
capitalization. The
renewable energy technology, such as hydrokinetic energy systems, is a
valuable part of
the overall solution.
These systems generate electricity from the kinetic energy present in flowing
water. They
may operate in rivers or manmade channels. Hydrokinetic systems utilize the
water
stream's natural pathway. No dam or impoundment is needed, therefore there is
no major
civil work to change the landscape, disturb the local ecology or uproot
communities.
"I,here are no toxic by-products produced in the generation of electric power.
As long as
the water flows, the hydrokinetic systems produce electricity or mechanical
energy.
The most desirable to implement or cost-effective hydrokinetic system must
produce the
required amount of electricity and be optimal in terms of cost, size, weight,
and
reliability. Another essential quality of such a system is its modular design.
A modular hydrokinetic system is made of a number of standardized units or
modules
that can be fitted together to construct a large power system in a variety of
ways. An
additional advantage of a modular technology is that particular modules may be
interchanged, added to or removed from the system as required. Such gives a
time
advantage for installation, modification, repairs and maintenance, thereby
insuring that
the system is more cost-competitive.
Further, there are a very large number of streams and small rivers, which do
have
significant water flows. It would be advantageous to have a modular
constructed
flexible hydrokinetic system that is suitable to use a variety of both deep
and shallow
water flows.
Thus there is a need for a robust hydrokinetic energy system that meets the
above-mentioned criteria. The present invention is intended to satisfy that
need.
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DESCRIPTION OF PRIOR ART
In a hydrokinetic energy system, the kinetic energy of flowing water is
transformed into
inechanical energy by use of an underwater turbine. The mechanical energy is
then
utilized to turn a generator and produce electrical energy.
'I,here are several different types of underwater turbines. In general,
underwater turbines
of the prior art have been of two main classes, namely:
- Turbines having a horizontal axis of rotation;
- Turbines, which have a vertical axis of rotation.
The art of interest will be discussed in the order of their perceived
relevance to the
present invention.
Horizontal Axis Hydro Turbines
'I'his category covers devices, which are known as Submersible Propeller Water
Turbines
or Underwater Windmills. The design of these turbines consists of a concentric
hub with
radial blades, similar to that of a windmill. Mechanical power is applied
directly or
through a speed increaser to an electric generator.
A propeller turbine generally has a runner with three to six blades in which
the water
contacts all of the blades constantly. The pitch of the blades may be fixed or
adjustable.
When submerged in a fast moving water source, the propeller is rotated by the
force of
the passing water.
Examples of Horizontal Axis Hydro Turbines are disclosed in U.S. Pat. Nos.
6472768,
6267551, 6254339, 6168373, 5798572, 5226804, and 4613279.
Such companies as Verdant Power, UEK Corporation, Marine Current Turbines Ltd.
are
also pursuing similar technologies for underwater power generation.
lnformation is available on their websites at:
ht~//wtivw.verdanthower.com/'Tech/lowimpact.shtm(
http,,!/uekus.com/index.htnil
http://www.marineturbines.com/home.htm respectively.
Propeller style generators work well for locations with fast moving,
relatively deep
streams. Clearly, devices such as these are simply too large for use in
streams of shallow
waters. Additionally, they suffer from low efficiency, poor starting torque
and bearing
problems.
Vertical Axis Hydro Turbines
Currently known the most efficient prototype of the Vertical Axis Hydro
Turbine, which
the applicant is aware of, was invented by Edouard Petrounevitch and disclosed
in the
International Patent Application No PCT/CA2006/000326 for Modular System for
Generating Electricity from Moving Fluid.
The embodiments of this system comprise a set of interconnected modules. Each
module
contains a fluid flow energy converter positioned in a protecting housing. A
converter
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consists of a vertical axis underwater hydro-turbine and a water flow
accelerator. The
turbine has an arrangement of paddles with mutually perpendicularly oriented
floatable
and sinkable blades. Such orientation of blades provides a positive feedback
minimizing
the blades' friction while maximizing a drag force and maximizing the
turbine's
efficiency. A water flow accelerator funnels incoming water current through
the working
part of the turbine and protects the resting part of the turbine from moving
water. It
further decreases the blades' friction and increases the fluid velocity
through the turbine
thereby enhancing the power output of the converter. An array of
interconnected modules
can be used to create versatile configurations of robust submersible
hydroelectric power
systems, which are inexpensive to build, install, maintain and dismantle.
It would be advantageous to further improve the efficiency of this system by:
- Eliminating the vertical load applied to vertical axis bearings;
- Additional acceleration of the incoming water flow;
- lmproved configuration of the turbine blades;
- Vertical and horizontal self-adjustment of system modules to an optimal
position
in a path of the water flow.
Furthermore, there is a need for a mobile hydro-systems module, which does not
require
complex anchoring mechanisms and can be easily relocated.
In this respect, the water current energy conversion system according to the
present
invention substantially departs from the conventional concepts and designs of
the prior
art, and in doing so provides a cost-effective solution primarily developed
for the purpose
of generating electricity from shallow water currents.
OBJECTS OF THE PRESENT INVENTION
The main object of the present invention is to create a new and more practical
system for
harvesting kinetic energy of water currents, by overcoming the drawbacks of
the known
systems.
Another object of the invention is to increase the entire system efficiency
through the
increase of turbine efficiency. This is achieved by employing a wing-type
vertical axis
hydro turbine with a zero vertical load applied to axis bearings and having an
arrangement of the turbine blades, hub, and radial wings in an innovative way.
It is a further object of the invention to produce a system module for
generating
electricity which is capable of self-adjusting to an optimal position in the
water current,
consequently further increasing the entire system efficiency.
Lastly, it is an object of the present invention to produce a new robust and
cost-effective
system module for generating electricity from shallow water currents, which
does not
require complex anchoring mechanisms and can be easily relocated, hence
providing a
vast number of possible site-locations for installation of such a device.
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'I'hese and other objects of the present invention will become readily
apparent
upon further review of the following specification and drawings.
SiJMMARY OF THE INVENTION
'The present invention provides a mobile system for producing electricity from
the kinetic
energy present in flowing water. The system may operate in rivers or manmade
channels.
"I"he embodiments of the system comprise a set of interconnected modules. Each
module
contains a submersible water current energy converter and a self-adjusting
buoyant
mooring mechanism. A converter consists of a pair of contra-rotating vertical
axis wing-
type turbines, connected to electrical generators, and a water flow
accelerator which can
have either a common channel for both or a dedicated channel for each turbine.
Each turbine comprises a hub which is mounted via bearings on an inner
vertical axis to
the protecting housing, a plurality of radial support wings attached to the
hub, a plurality
of paddle support members fixedly and symmetrically mounted on upper and lower
sides
of support wings, two sets of paddles, and a plurality of radial stop wings
attached to the
hub.
'The first set of paddles with floatable blades is located above the radial
support wings, as
the second set of paddles with sinkable blades is located below the radial
support wings.
'I'he paddle support members hold the paddles. The stops, built in said paddle
support
members, and radial stop wings limit the free rotation of the paddles within a
ninety
degree angle.
The paddles comprise a pair of sinkable or floatable blades having a
rectangular-like
geometry with the arc-shaped outer edges. The blades are asymmetrically fixed
by their
leading edges to the shafts at both ends in a mutually perpendicular
orientation. Such
orientation of blades provides a positive feedback minimizing the blades'
friction and
maximizing the turbine's performance. The blades' geometry allows interception
of the
incoming water flow nearly completely, thus further enhancing the turbine's
efficiency.
The hub, radial support wings, radial stop wings, and paddle shafts are filled
with a
buoyant material to eliminate the vertical load applied to vertical axis
bearings, thus
decreasing the bearing friction force and increasing the power output of the
converter.
A pair of electrical generators and speed increasers transforms the rotational
energy of
turbines into electricity.
A V-shaped water flow accelerator with a gradually decreasing rectangular
cross-section
directs incoming water flow through the working parts of turbines, blocking
the opposite
parts of turbines from moving water and urging said turbines to turn in
mutually opposite
directions. An inlet of the accelerator, having the form of a rectangular
pyramid, is
covered by filter panels to prevent clogging of the module and fish
entrapment. The small
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cross-section area of the accelerator's outlet is incorporated into the front
panel of the
turbine unit.
A turbine unit's protecting housing comprises a strong steel frame, which
supports the
turbines, speed increasers and electrical generators. Two counter-rotating
turbines are
mounted side by side in order to neutralize the twisting moment produced by
each
turbine.
The system module is capable of self-adjusting to the optimal position in
water current
vertically and horizontally, consequently further increasing the entire system
efficiency.
It uses a simple anchoring mechanism and can be easily relocated. Such gives a
time
advantage for installation and maintenance.
'The array of these modules may be connected to an underwater transmission
line, thus
providing versatile forms of robust hydroelectric power systems which are
inexpensive to
build, install and maintain.
The present invention, unlike previous efforts to generate electricity from
moving water,
is practical and economical because its design uses a new water current energy
converter,
which surpasses the efficiencies of other known free-flow hydro energy
devices. It covers
a wide market segment around the globe - areas with shallow river or channel
currents.
There are two preferred embodiments of the system.
The embodiment A is the system assembly comprising an array of interconnected
modules employing a water current energy converter, which contains a pair of
contra-
rotating vertical axis wing-type turbines, and a water flow accelerator with a
common
funneling channel for both turbines.
The embodiment B is the system assembly comprising an array of interconnected
modules employing a water current energy converter, which contains a pair of
contra-
rotating vertical axis wing-type turbines, and a water flow accelerator with a
dedicated
funneling channel for each turbine.
BRIEF DESCRIPTION OF THE DRAWING
FIG.1 is a schematic view of a self-adjusting system module for harvesting the
kinetic
energy from water currents;
FIG.2 is a plain frontal view of the water current energy converter with a
common
funneling channel for both turbines;
FIG.3 is a top view of FIG. 2;
FIG.4 is a frontal view of the vertical axis wing-type hydro turbine;
FIG.5 is a top view of FIG.4;
FIG.6 is a frontal view of the paddle;
FIG.7 is a side view of FIG.6;
FIG.8 is a top view of FIG.6;
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FIG.9 is a schematic view of a mooring configuration;
FIG.10 is a plain frontal view of the water current energy converter with a
dedicated
funneling channel for each turbine;
FIG.I 1 is a top view of FIG.10.
DETAILED DESCRIPTION OF THE INVENTION
Embodiment A
The embodiment A is the system assembly comprising an array of interconnected
buoyant unidirectional modules. Each module employs a water current energy
converter,
which contains a pair of contra-rotating vertical axis wing-type turbines, and
a water flow
accelerator with a common funneling channel for both turbines.
'The system module (FIGS.1 through 3) is capable of self-adjustment to
changing water
flow conditions. It contains a submerged water current energy converter and a
self-
adjusting buoyant mooring mechanism.
A converter includes a detachable turbine unit 21, positioned in a protecting
housing, and
a detachable water flow accelerator 22.
A turbine unit 21 (FIGS.2 and 3) consists of a pair of contra-rotating
vertical axis wing-
type turbines 23 and 24, connected to the detachable electrical generators 25
and 26
respectively.
Each turbine (FIGS.4 and 5) comprises a hub 27, which is mounted via bearings
on an
inner vertical axis 28 to the protecting housing 29, a plurality of radial
support wings 30,
attached to the hub 27, a plurality of paddle support members 32 fixedly and
symmetrically mounted on upper and lower sides of support wings 30, two sets
33 and 34
of paddles with mutually perpendicularly oriented asymmetric blades 35 and 36
that are
fixed to the shafts at both ends, and two sets 37 and 38 of radial stop wings
attached to
the hub 27.
The first set 33 of paddles with floatable blades is mounted via bearings
built in the
paddle support members 32 located on the upper side of support wings 30. The
second set
34 of paddles with sinkable blades is mounted via bearings built in the paddle
support
members 32 located on the lower side of support wings 30.
1'he stops, built in paddle support members 32, and radial stop wings 37 and
38 limit the
free rotation of paddles 33 and 34 within a ninety degree angle. Generally,
each set may
comprise any number of paddles (preferably three) made from any suitable
material, such
as steel, aluminum, plastic or fiberglass, which provides sufficient buoyancy
for the
floatable blades, and reasonable gravity for the sinkable blades.
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As shown in FIGS.6 through 8, the blades 40 are asymmetrically fixed by their
leading
edge 41 to the shaft 42 at both ends in a mutually perpendicular orientation.
Such
orientation of blades provides a positive feedback minimizing the blades'
friction and
maximizing the turbine's performance.
'I'o ensure the most efficient utilization of the water current, the blades 40
should
preferably have a rectangular-like geometry with the arc-shaped outer edges
43. The
distance between parallel leading 41 and trailing 44 edges should not exceed
the half of
the turbine's radius.
The high efficiency of the presented turbine comes from creating the maximum
drag
force by vertically oriented blades on the power generating side 45, and
practically zero
frictional force produced by horizontally oriented blades on the resting side
46 of the
turbine (FIGS.4 and 5). The blades 40 extend beyond radial support wings 30,
thus
increasing torque to spin the turbine.
When the water is not flowing, the sinkable blades of the lower paddles,
located below
radial support wings 30, are partially open via the force of gravity, thus
creating 45-
degree angles between their surfaces and the vertical axis of the turbine.
When water
flows against the partially opened blades on the power generating side of the
turbine, the
water current applies as an opening force against the blades. Two forces
(gravity and
water flow) start to turn the blades on the power generating side toward their
vertical
position. The cross flow area is increasing and the turbine begins spinning.
At the same
time, because of their mutually perpendicular orientation, the blades on the
opposite sides
of'the paddles are turning toward their horizontal position, decreasing the
frictional force.
This creates a positive feedback resulting in further increasing the turbine's
spinning.
When the blades reach the vertical position, stops, built in paddle support
members 32,
and radial stop wings 38 prevent paddles from turning further. As a result,
the vertically
oriented blades create the maximum drag force while the frictional force of
the
horizontally oriented blades is negligible, thereby maintaining high
efficiency of the
presented turbine.
The upper paddles, located above radial support wings 30, work in a similar
way. The
only difference is that a buoyant force applies to the floatable blades of the
upper paddles
instead of a gravitational force applied to the sinkable blades of the lower
paddles.
The hub 27, radial support wings 30, radial stop wings 37, 38 and paddle
shafts are filled
with a buoyant, foam-like material. Because of the Archimed's force created by
a foam-
like material inside, no vertical load is applied on vertical axis bearings,
thus
considerably increasing the power output of the converter.
A turbine unit 21 employs two counter-rotating turbines mounted side by side
in order to
neutralize the twisting moment produced by each turbine. Such arrangement
allows the
system module to automatically maintain an optimum heading to the river
stream. This
configuration also has the advantage of being able to use a simple but
effective mooring
mechanism.
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The turbine unit's protecting housing 31, shown in FIGs.I through 3, is a
strong steel
frame, having a shape of the right prism, which supports the turbines 23 and
24, and
electrical generators 25 and 26. The flat screen panels cover the frame's
side, front, top
and bottom entrances. These panels serve both to improve the efficiency of the
converter,
by creating a funneling channel together with the flow accelerator 22, and to
protect the
turbine unit from debris.
A pair of electrical generators 25 and 26 transforms the rotational energy of
turbines 23
and 24 into electricity. The belts 51 and 52 rotatably couple the generator
pulleys 53 and
54 to the turbine pulleys 55 and 56 respectively. These belts and pulleys
serve as speed
increasers to connect slowly spinning turbines to electrical generators. The
belts in the
present example are timing belts. Alternatively, other driven means, as well
as any
suitable submersible electrical generators may be employed.
Power available from a turbine increases as the cube of the water flow
velocity. If the
velocity is doubled, the available power then increases by a factor of eight.
It is therefore
important to make use of velocities that are as high as possible, which would
enable the
number of turbines to be significantly reduced, and this would have a marked
effect on
the capital cost. This is achieved through the use of the V-shaped water flow
accelerator
22 (FIGS.1 through 3).
Screen panels 61 and 62 cover the right and left sides of the accelerator. The
top and
bottom sides of the accelerator are covered by a pair of screen panels 63 and
64.
An inlet of the accelerator has the form of a rectangular pyramid 65 covered
by filter
panels, made of steel net, to avoid clogging of the converter by debris and
fish
entrapment.
The small outlet area 66 of the accelerator 22 is incorporated into a central
opening of the
front screen panel of the turbine unit 21. This water flow accelerator directs
incoming
water flow through the working parts of a left and a right turbines urging
them to turn in
mutually opposite directions and blocking the resting parts of the turbines
from moving
water. It increases the water velocity through the turbines, further decreases
the blades'
friction and reduces resistance to the turbine rotation, thereby enhancing the
power output
of the converter.
A self-adjusting buoyant mooring mechanism (see FIGS. 1 and 9) includes a
pontoon 70,
a converter-lifting winch 71, which is incorporated into the stern part of the
pontoon, a
whee172, positioned at the centre of the bottom side of the inlet area of the
converter 73,
a pair of wheels 74 and 75, attached to the bottom side of the outlet area of
the converter
73, and mooring line 76 running from the front part of the converter 73 to the
anchor 77.
The front part of the pontoon 70 is pivotally secured to the top side of the
inlet area of the
submerged water current energy converter 73. The winch rope 781imits the range
of the
vertical rotation of the outlet part of the converter from 0 to preferably 30
degrees.
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It is known that the speed of the water stream on the surface is highest, but
it drops down
fast with increasing the depth. A buoyant mooring mechanism allows an inlet of
the tilted
converter to be placed closer to the water surface in order to utilize both
the kinetic
energy of a faster-moving surface water layer and the potential energy
inherent in the
water level difference, thus increasing the water flow velocity through the
turbine unit.
Further, a buoyant mooring mechanism allows the converter to operate optimally
under
the influence of varying water levels 79 (FIG. 9) subject to various external
factors such
as rainfall or drought.
Securely moored to the river or channel bed, the system module orients itself
into the
water current like a boat at anchor. It is cheap and simple to assemble,
dismantle and
transport for relocation.
One or more modules can be placed in a river or channel for the purpose of
generating
electricity or pumping water. The electricity produced by the system is
transmitted
through the flexible underwater cables to the shore. After employing the
appropriate
voltage regulators and transformers, the generated power is then supplied to
the
consumers via the power-distributing network.
tJnlike the previous efforts to generate electricity from moving water, the
present
invention surpasses the efficiencies of other known free-flow hydro energy
devices
because its design uses a new water current energy converter, capable of self-
adjusting to
an optimal position in the water flow vertically and horizontally, and having
a zero
vertical load on turbine axis bearings. Torque is gained by an increase in
horizontal
distance instead of an increase in vertical distance, which allows it to be
used in shallow
water currents with a very low head. This technology drastically reduces
material
strength requirements for the turbine blades, system weight and cost.
Consequently, it
adapts perfectly for the wide market segment - areas with shallow and/or slow
water
currents, therefore providing a significant advantage to the prior art.
Embodiment B
The embodiment B is the system assembly comprising an array of interconnected
buoyant unidirectional modules. Each module is analogous to that described in
the
embodiment A. The only difference is that a water current energy converter
employs a
water flow accelerator with a dedicated left funneling channel 81 for a left
turbine and a
dedicated right funneling channel 82 for a right turbine (see FIGS. 10 and
11).
T'he present invention is not to be limited by what has been particularly
shown and
described, except as indicated by the appended claims.
