U.S. patent application number 15/084558 was filed with the patent office on 2016-07-21 for underwater energy storage system and power station powered therewith.
This patent application is currently assigned to Arothron Ltd.. The applicant listed for this patent is Arothron Ltd.. Invention is credited to Ron ELAZARI-VOLCANI.
Application Number | 20160207703 15/084558 |
Document ID | / |
Family ID | 44368229 |
Filed Date | 2016-07-21 |
United States Patent
Application |
20160207703 |
Kind Code |
A1 |
ELAZARI-VOLCANI; Ron |
July 21, 2016 |
UNDERWATER ENERGY STORAGE SYSTEM AND POWER STATION POWERED
THEREWITH
Abstract
An underwater energy storage system includes a tank for storing
a compressed gas that is adapted to be stored underwater. The tank
includes at least one water opening through which water from
surrounding environment can flow into and out of the tank, and at
least one gas opening through which the compressed gas is received.
The underwater energy storage system further includes at least one
duct communicating between the at least one opening for gas flow
and a source of compressed gas and a compartment constructed over a
roof of the tank, wherein said compartment is adapted for receiving
weights at a sinking site of the tank.
Inventors: |
ELAZARI-VOLCANI; Ron;
(Moshav Ein-Sarid, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Arothron Ltd. |
Zikhron-Yaakov |
|
IL |
|
|
Assignee: |
Arothron Ltd.
Zikhron-Yaakov
IL
|
Family ID: |
44368229 |
Appl. No.: |
15/084558 |
Filed: |
March 30, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14446400 |
Jul 30, 2014 |
9309046 |
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15084558 |
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13577254 |
Aug 5, 2012 |
8801332 |
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PCT/IL2011/000157 |
Feb 15, 2011 |
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14446400 |
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61304499 |
Feb 15, 2010 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H02K 7/1823 20130101;
H02J 15/006 20130101; B65D 88/78 20130101; F02C 6/16 20130101; B65D
2590/023 20130101; F17C 1/007 20130101; B65D 2590/026 20130101;
Y02E 60/16 20130101; B65D 88/02 20130101 |
International
Class: |
B65D 88/78 20060101
B65D088/78; H02K 7/18 20060101 H02K007/18; B65D 88/02 20060101
B65D088/02 |
Claims
1. An underwater energy storage system comprising: a tank for
storing a compressed gas that is adapted to be stored underwater,
the tank enclosing a constant volume and comprising: at least one
water opening through which water from surrounding environment can
flow into and out of the tank; and floating structures adapted to
cover a surface of the water contained in the tank; at least one
gas opening through which the compressed gas is received; and at
least one duct communicating between the at least one opening for
gas flow and a source of compressed gas.
2. The system of claim 1, wherein the floating structures are
adapted to prevent evaporation of water in the tank based on
covering the surface of the water.
3. The system of claim 1, wherein the floating structures are
formed from Styrofoam.TM..
4. The system of claim 1, wherein the compressed gas is air.
5. The system of claim 1, wherein the compressed gas is carbonic
gas.
6. The system of claim 1, wherein the tank is partitioned into a
plurality of chambers, said chambers include chamber walls with gas
openings that provide free gas flow between the chambers and
wherein each of the chambers includes water opening through which
water from surrounding environment can flow.
7. The system of claim 6, wherein a chamber wall that surrounds a
chamber that directly communicates with the at least on duct
through which the compressed gas is received, is provided with
added reinforcements.
8. The system of claim 6, wherein the at least one duct through
which the compressed gas is received branches into a plurality of
ducts each of which directly communicates with one of the chambers
of the tank.
9. The system of claim 1 comprising an electricity producing
turbine installed on the at least one water opening.
10. The system of claim 1 comprising a water duct connected to the
at least one water opening and extending upward therefrom, said
duct adapted to provide a water opening at a height above the water
opening of the tank.
11. The system of claim 1, wherein the tank is casted with
concrete.
12. The system of claim 1, wherein the tank includes a floor.
13. The system of claim 1, wherein the tank includes walls that
have a thickness that increases over a height of the walls.
14. The system of claim 1, wherein the tank includes walls with
structural reinforcements, wherein an amount of the reinforcement
provided increases over a height of the tank.
15. The system of claim 1, wherein the tank includes inner walls
that are coated with a metal layer.
16. The system of claim 15, wherein a thickness of the metal layer
increases over a height of the tank.
17. The system of claim 1, wherein the tank includes outer walls
that are coated with a metal layer.
18. The system of claim 1, wherein the at least one duct
communicating between the at least one opening for gas flow and a
source of compressed gas is lined with a plurality of ribs adapted
to cool the compressed gas as it flows from the source to the
tank.
19. The system of claim 1, comprising at least one duct
communicating between the at least one opening for gas flow in the
tank and a pneumatic device.
20. The system of claim 19, comprising a heat exchange unit for
transferring heat generated by the source of compressed gas to gas
flowing from the at least one duct communicating between the at
least one opening for gas flow in the tank and a pneumatic device.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 14/446,400 filed on Jul. 30, 2014, which is a
continuation of U.S. patent application Ser. No. 13/577,254 filed
on Aug. 5, 2012, now U.S. Pat. No. 8,801,332, which is a National
Phase of PCT Patent Application No. PCT/IL2011/000157 having
International Filing Date of Feb. 15, 2011, which claims the
benefit of priority under 35 USC .sctn.119(e) of U.S. Provisional
Patent Application No. 61/304,499 filed on Feb. 15, 2010. The
contents of the above applications are all incorporated by
reference as if fully set forth herein in their entirety.
FIELD OF THE INVENTION
[0002] The present invention, in some embodiments thereof, relates
to underwater energy storage and, more particularly, but not
exclusively, to underwater energy storage of compressed air.
BACKGROUND OF THE INVENTION
[0003] Although renewable energy from natural resources such as
sunlight, wind, rain, and tides are typically clean, plentiful and
relatively cheap, its use has been limited due to an inherent
problem that renewable energy is not always available on demand.
Compressed air energy storage is a way to store energy generated
during periods of low energy demand for use during periods of high
energy demands. It has been proposed to store compressed air in a
high pressure environment such as deep underwater to avoid the
costs of high-pressure vessels for storing the compressed air. A
compressed air energy storage device in development stages is
described in an article published on Apr. 28, 2010 on
www(dot)energystorageforum(dot)com/tag/compressed-air/downloaded
from the internet on Jan. 27, 2010. The article discloses a
pumpkin-shaped, underwater, compressed-air-storage devices being
trialed at the University of Nottingham. It is described that the
compressed-air-storage devices, constructed from steel and polymer,
are designed to be pumped full of high-pressure air during times of
high winds and low demand, with the stored energy used to turn
turbines to create electricity when needed on the grid. The article
states that the compressed-air-storage devices being trialed at the
University of Nottingham could prove key to overcoming one of the
main obstacles to Europe's long-term ambitions for utility-scale
renewable-energy production--that peak power-generating times from
offshore wind farms rarely match peak demands for electricity
onshore.
[0004] Japanese Patent Application No. JP54011517 published on Jan.
27, 1979, entitled "Marine pressurized water type energy storing
method," the contents of which is incorporated by reference,
describes a rigid dome shaped air storage tank including a water
valve and an air pipe for storing pressure energy in a pressurized
water vessel placed in or on the bottom of the sea with compressed
air pumped in from an air compressor set in the marine space.
[0005] Japanese Patent Application No. JP63239320 published on Oct.
5, 1988, entitled "Underwater Energy Storage Device," the contents
of which is incorporated by reference, describes a hollow rigid
bottomless case placed on the bottom of the sea for storing
pressurized air. During the nighttime or the like where the surplus
power is produced, a compressor is operated to feed pressurized air
into the hollow case through a connecting pipe, and then, by
forcing the seawater through a water passage hole, the electrical
energy is stored as an air-pressure energy in the case. During the
daytime, a generator is operated by making use of the pressurized
air stored in the case.
[0006] Japanese Patent Application No. JP2271032, published on Nov.
6, 1990, entitled "Compressed air storage device for underwater
installation and submerging method thereof," the contents of which
is incorporated by reference, describes an underwater installation
compressed air storage device including main compressed air storage
tank of bottomless shell construction and an additional weight
adding part in its lower part. It is described that the device is
softly landed to the sea bottom by releasing compressed air from a
work deck barge and special underwater concrete is placed in the
additional weight adding part through a pipe. The storage device is
connected to a compressor and a turbine on the ground with a
pipe.
[0007] Japanese Patent Application No. JP4121424 published on Apr.
22, 1992, entitled "Air storage power generation method and air
storage power generation plant," the contents of which is
incorporated by reference, describes an underwater compressed air
storage tank that floats above the seabed and has an opening at the
bottom through which water is introduced and expelled. Water
surrounding the tanks cools the air so that the temperature is
decreased, while the pressure is maintained constant. Under
condition of power shortage, the cooled compressed air is feed to a
boost compressor and afterwards supplied to a combustor as
combustion air through an air pipeline.
SUMMARY OF THE INVENTION
[0008] According to an aspect of some embodiments of the present
invention there is provided a utility-scaled underwater energy
storage system and method for storing compressed air underwater.
According to some embodiments of the present invention, the
underwater energy storage system includes features for withstanding
and/or counterbalancing forces applied on a compressed air storage
tank due to differential pressure conditions that exist over a
height of the storage system when stored underwater. According to
some embodiments of the present invention, the underwater energy
storage system includes features for submerging and anchoring the
storage system underwater. According to some embodiments of the
present invention, the underwater energy storage system includes
feature for cooling compressed air as it flows from a compressor to
a storage tank of the underwater energy storage system. According
to some embodiments of the present invention, the underwater energy
storage system is an adiabatic storage system including features
for storing heat produced during compression of the air and using
the stored heat to heat air discharged from the underwater energy
storage system.
[0009] According to aspects of some embodiments of the present
invention there is provided an underwater energy storage system
comprising: a tank for storing a compressed gas that is adapted to
be stored underwater, the tank comprising: at least one water
opening through which water from surrounding environment can flow
into and out of the tank; and at least one gas opening through
which the compressed gas is received; at least one duct
communicating between the at least one opening for gas flow and a
source of compressed gas; and a compartment constructed over a roof
of the tank, wherein said compartment is adapted for receiving
weights at a sinking site of the tank.
[0010] Optionally, the compartment is formed with a banister
encompassing the roof of the tank.
[0011] Optionally, the banister is an integral part of walls of the
tank that extends above a height of the roof.
[0012] Optionally, the compartment is partitioned with partitioning
walls adapted to provide structural support for the roof of the
tank.
[0013] Optionally, the tank includes sloped walls, and wherein the
banister at least partially encompasses the walls of the tank.
[0014] Optionally, the compartment includes a door, wherein the
door provides for releasing weights received in the compartment
when opened.
[0015] Optionally, the weights include at least one of rocks, sand
and gravel.
[0016] Optionally, the tank includes walls that have a thickness
that increases over a height of the walls.
[0017] Optionally, the tank includes walls with structural
reinforcements, wherein an amount of the reinforcement provided
increases over a height of the tank.
[0018] Optionally, the tank is partitioned into a plurality of
chambers, said chambers include chamber walls with gas openings
that provide free gas flow between the chambers and wherein each of
the chambers includes water opening through which water from
surrounding environment can flow.
[0019] Optionally, a chamber wall that surrounds a chamber that
directly communicates with the at least on duct through which the
compressed gas is received, is provided with added
reinforcements.
[0020] Optionally, the at least one duct through which the
compressed gas is received branches into a plurality of ducts each
of which directly communicates with one of the chambers of the
tank.
[0021] Optionally, the system comprises: a plurality of tanks; and
gas ducts connected between gas openings of each of the plurality
of tanks, wherein the gas ducts provide free gas flow between the
plurality of tanks.
[0022] Optionally, the system comprises a water duct connected the
at least one water opening and extending upward therefrom, said
duct adapted to provide a water opening at a height above the water
opening of the tank.
[0023] Optionally, the system comprises an extension extending from
a floor of the tank, the extension defining an open channel in
which weights can be contained for anchoring the tank on a bed of a
water body.
[0024] Optionally, the tanks includes prongs extending outward from
a floor of the tank, wherein said prongs are adapted to be embedded
in a bed of a water body for stabilizing the tank on the bed of the
water body.
[0025] Optionally, the tank is casted with concrete.
[0026] Optionally, the tank includes inner walls that are coated
with a metal layer.
[0027] Optionally, a thickness of the metal layer increases over a
height of the tank.
[0028] Optionally, the tank includes outer walls that are coated
with a metal layer.
[0029] Optionally, the at least one duct communicating between the
at least one opening for gas flow and a source of compressed gas is
lined with a plurality of ribs adapted to cool the compressed gas
as it flows from the source to the tank.
[0030] Optionally, at least a portion of the ribs are outer ribs
that encompass an outer diameter of the duct and wherein the outer
ribs are structured to be in line with a direction of current flow
in the sinking site of the system.
[0031] Optionally, the system comprises at least one duct
communicating between the at least one opening for gas flow in the
tank and a pneumatic device.
[0032] Optionally, the system comprises a heat exchange unit for
transferring heat generated by the source of compressed gas to gas
flowing from the at least one duct communicating between the at
least one opening for gas flow in the tank and a pneumatic
device.
[0033] Optionally, the heat exchange unit includes a heat exchange
pool formed between a damn constructed at a distance from a beach
and the beach.
[0034] Optionally, the heat exchange unit includes at least one
thermal energy storage element through which the at least one duct
communicating between the at least one opening for gas flow and a
source of compressed gas and the at least one duct communicating
between the at least one opening for gas flow in the tank and a
pneumatic device pass through.
[0035] Optionally, the system comprises a heat exchange unit
adapted to harness cooling of gas discharged from the tank for
desalinating water.
[0036] Optionally, the compressed gas is compress air.
[0037] Optionally, the compressed gas is condensed carbonic
gas.
[0038] According to aspects of some embodiments of the present
invention there is provided an underwater energy storage system
comprising: a plurality of tanks for storing compressed air
underwater, wherein each of the tanks include at least one water
opening through which water from a surrounding water body can flow
into and out of the tank and at least one air opening for receiving
and discharging the compressed air; a first duct for communicating
air flow between the at least one air opening of at least one of
the plurality of tanks and a source of compressed air; and at least
one second duct for communicating air flow between the at least one
air opening of each tank.
[0039] Optionally, the system comprises a water duct connected to
the at least one water opening of each of the plurality of tanks
and extending upward therefrom, said duct adapted to provide a
water opening at a height above the water opening of the tank.
[0040] Optionally, at least a portion of the plurality of tanks are
partitioned into a plurality of chambers, said chambers include
chamber walls with air openings that provide free air flow between
the chambers and wherein each of the chambers includes water
opening through which water from surrounding environment can
flow.
[0041] Optionally, at least a portion of the plurality of tanks
includes walls with structural reinforcements, wherein an amount of
the reinforcement provided increases over a height of the tank.
[0042] Optionally, t least one an inner or outer wall of the
plurality of tanks is coated with a metal layer.
[0043] Optionally, the at least one duct communicating between the
at least one opening for air flow and a source of compressed air is
lined with a plurality of ribs adapted to cool the compressed air
as it flows from the source to the tank.
[0044] Optionally, the system comprises at least one duct
communicating between the at least one opening for air flow in at
least one of the plurality of tanks and a pneumatic device.
[0045] Optionally, the system comprises a heat exchange unit for
transferring heat generated by the source of compressed gas to air
flowing from the at least one duct communicating between the at
least one opening for gas flow in at least one of the plurality of
tanks and a pneumatic device.
[0046] According to aspects of some embodiments of the present
invention there is provided an underwater energy storage system
comprising: a bell shaped tank with a concave shaped wall for
storing compressed air underwater, wherein the tank includes a
water opening through which water from a surrounding water body can
flow into and out of the tank and at least one air flow opening for
receiving compressed air; and at least one duct extending from the
at least one air flow opening and a source of compressed air.
[0047] Optionally, a shape of the tank is defined to counterbalance
an increase in tensile forces along a height of the tank due to an
increase in pressure drop along a height of the wall.
[0048] Optionally, a change in a diameter of the tank over the
height is defined to reduce tensile forces on wall of tank as the
pressure drop across the wall increases.
[0049] Optionally, the tank is shaped such that a diameter of the
tank at a given height multiplied by the given height is constant
for all heights of the tank.
[0050] Optionally, the system comprises a water duct connected to
the water opening and extending upward therefrom, said duct adapted
to provide a water opening at a height above the water opening of
the tank.
[0051] According to aspects of some embodiments of the present
invention there is provided an underwater energy storage system
comprising: a tank for storing compressed gas underwater, wherein
the tank includes at least two stories, wherein the stories are
fluidly connected through at least one opening between a ceiling of
a lower story and a floor of an upper story, the opening adapted to
provide free flow of compressed gas and water, wherein the lower
story of the tank includes at least one water opening through which
water from a surrounding water body can flow into and out of the
tank and wherein the upper story of the tank includes at least one
air flow opening for receiving compressed air, and wherein a
diameter or an extent of the upper story of the tank is less than a
diameter or an extent of the lower story of the tank; and at least
one duct extending from the at least one air flow opening and a
source of compressed air.
[0052] Optionally, the diameter of the upper story is defined to
counterbalance larger tensile force on walls of the tank in the
upper story as compared to tensile force on the walls of the tank
in the lower story.
[0053] Optionally, the system comprises a plurality of tanks; and
air ducts connected between air opening of each of the plurality of
tanks, wherein the air ducts provide free gas flow between the
plurality of tanks.
[0054] Optionally, the at least one duct extending from the at
least one air flow opening and a source of compressed air is lined
with a plurality of ribs adapted to cool the compressed air as it
flows from the source to the tank.
[0055] Optionally, the system comprises at least one duct
communicating between the at least one air flow opening in the tank
and a pneumatic device.
[0056] Optionally, the system comprises a heat exchange unit for
transferring heat generated by the source of compressed air to air
flowing from the at least one duct communicating between the at
least one air flow opening in the tank and the pneumatic
device.
[0057] According to aspects of some embodiments of the present
invention there is provided n underwater energy storage system
comprising: a rigid tank for storing a compressed gas that is
adapted to be stored underwater, the tank includes: at least one
opening through which water from surrounding environment can flow
into and out of the tank; and an opening through which the
compressed gas is received; and at least one duct communicating
between the at least one opening for gas flow and a source of
compressed gas; and a collapsible bag housed in the rigid tank
including an opening that communicates with the opening through
which the compressed gas is received, wherein the collapsible bag
is adapted to receive and contain the compressed gas.
[0058] Optionally, the gas is condensed carbonic gas.
[0059] Optionally, the system comprises a compartment constructed
over a roof of the tank, wherein said compartment is adapted for
receiving weights at a sinking site of the tank.
[0060] Optionally, the tank is rests on a bed of a water body.
[0061] Optionally, the bag is partially connected to a floor of the
tank.
[0062] Optionally, an inner wall of the tank is coated with
friction protective material.
[0063] According to aspects of some embodiments of the present
invention there is provided an underwater energy storage system
comprising: an underwater storage tank for storing compressed air,
wherein the tank is formed from a roof construction rigidly
connected to walls of an underwater geological formation, wherein
said roof construction includes at least one opening though which
compressed air is received; and at least one duct communicating
between the at least one opening for air flow and a source of
compressed air.
[0064] Optionally, the system comprises at least one duct
communicating between the at least one opening for gas flow in the
tank and a pneumatic device.
[0065] According to aspects of some embodiments of the present
invention there is provided an underwater energy storage system
comprising: a tank for storing a compressed air that is adapted to
be stored underwater, wherein the tank is a floorless tank, the
tank including: a collapsible portion, wherein the collapsible
portion includes an opening adapted to communicate with a duct
through which the compressed air is received and an open bottom
from which water can enter and exit the collapsible portion; and a
rigid portion adapted to provide a rigid construction for
maintaining the bottom open; and at least one duct communicating
between the opening for air flow and a source of the compressed
air.
[0066] Optionally, the collapsible portion is protected with a
rigid cage.
[0067] Optionally, the system comprises an anchoring element
attached to the rigid portion, wherein the anchoring element is
adapted to maintain the tank at a given height above a bed of a
water body.
[0068] According to aspects of some embodiments of the present
invention there is provided an underwater energy storage system
comprising: an underwater storage tank for storing compressed air,
wherein the tank is formed from a rigid cover forming a cavity
therein, wherein the tank includes an opening for air flow through
which compressed air is received and is bottomless, and wherein the
tank is adapted to float over a bed of the water body; at least one
anchoring element holding the underwater storage tank for anchoring
the storage tank at a height above the bed of a water body; at
least one duct communicating between the opening for air flow and a
source of the compressed air.
[0069] Optionally, the storage tank is dome shaped.
[0070] Optionally, the storage tank has a shape of a truncated
sphere.
[0071] Optionally, the storage tank is constructed from at least
one of metal, concrete and a rigid polymer.
[0072] Optionally, the at least one anchoring element is in a form
of a net connected to a weight, where the net is adapted for
encompassing the storage tank.
[0073] According to aspects of some embodiments of the present
invention there is provided a method for casting an underwater
energy storage system at a sinking site, the method comprising:
providing a frame defining walls of an underwater storage tank,
wherein the frame is fitted with duct for defining an opening for
water flow communication between the tank and a surrounding water
body, and wherein the frame is fitted with duct for defining an
opening for air flow; blocking at least one of the opening for
water flow communication and the opening for air flow; transporting
the frame to a sinking site; and pouring casting material in the
frame.
[0074] Optionally, the method comprises releasing blocking of the
at least one of the opening for water flow communication and the
opening for air flow so that the tank can sink.
[0075] Optionally, the method comprises controlling sinking with a
chain of buoys.
[0076] According to aspects of some embodiments of the present
invention there is provided a thermal energy storage element in the
form of a sphere constructed from concrete or ceramic material and
embedded with at least one metal rod, wherein the metal rod at
least partially protrudes through the sphere.
[0077] Unless otherwise defined, all technical and/or scientific
terms used herein have the same meaning as commonly understood by
one of ordinary skill in the art to which the invention pertains.
Although methods and materials similar or equivalent to those
described herein can be used in the practice or testing of
embodiments of the invention, exemplary methods and/or materials
are described below. In case of conflict, the patent specification,
including definitions, will control. In addition, the materials,
methods, and examples are illustrative only and are not intended to
be necessarily limiting.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0078] Some embodiments of the invention are herein described, by
way of example only, with reference to the accompanying drawings.
With specific reference now to the drawings in detail, it is
stressed that the particulars shown are by way of example and for
purposes of illustrative discussion of embodiments of the
invention. In this regard, the description taken with the drawings
makes apparent to those skilled in the art how embodiments of the
invention may be practiced.
[0079] In the drawings:
[0080] FIG. 1 is a simplified schematic drawing of an exemplary
underwater energy storage system and a power station powered
therewith in accordance with some embodiments of the present
invention;
[0081] FIG. 2 is a simplified schematic diagram showing exemplary
forces acting on an underwater storage tank due to differential
pressure along a height of the underwater storage tank in
accordance with some embodiments of the present invention;
[0082] FIGS. 3A and 3B are simplified schematic drawing of
exemplary underwater energy storage systems with reinforced
construction for withstanding pressure drops across walls of the
storage tank in accordance with some embodiments of the present
invention;
[0083] FIGS. 4A, 4B and 4C are simplified schematic drawings of
exemplary underwater energy storage systems including a storage
tank whose diameter decreases as a function of tank height in
accordance with some embodiments of the present invention;
[0084] FIGS. 5A and 5B are simplified schematic drawings of
exemplary underwater energy storage systems including a cylindrical
storage tank that is partitioned in accordance with some
embodiments of the present invention;
[0085] FIG. 6 is a simplified schematic drawing of exemplary
underwater energy storage system including a cuboid shaped storage
tank that is partitioned in accordance with some embodiments of the
present invention;
[0086] FIGS. 7A and 7B are simplified schematic drawings of
exemplary underwater energy storage systems including partitioned
tank with reinforced walls around an air entrance chamber in
accordance with some embodiments of the present invention;
[0087] FIG. 8 is a simplified schematic drawing of an exemplary
underwater energy storage system including a plurality of
inlet/outlet ducts that converge into a single duct in accordance
with some embodiments of the present invention;
[0088] FIG. 9 is a simplified schematic drawing of an exemplary
underwater energy storage system including a plurality of storage
tank modules that are fluidly connected in accordance with some
embodiments of the present invention;
[0089] FIGS. 10A and 10B are simplified schematic drawings of
exemplary underwater energy storage systems including a floorless
storage tank that is anchored at a height above a seabed in
accordance with some embodiments of the present invention;
[0090] FIG. 11 is a simplified schematic drawing of an exemplary
underwater energy storage system partially formed from natural
underwater landscape formations in accordance with some embodiments
of the present invention;
[0091] FIGS. 12A, 12B and 12C are simplified schematic drawings of
exemplary underwater energy storage systems including a flexible
storage bag in accordance with some embodiments of the present
invention;
[0092] FIG. 13 is a simplified schematic drawing of an exemplary
underwater energy storage system including a flexible compressed
energy storage container housed in rigid storage underwater tank in
accordance with some embodiments of the present invention;
[0093] FIGS. 14A and 14B are simplified schematic drawings showing
an exemplary method for casting and sinking an exemplary underwater
energy storage system in accordance with some embodiments of the
present invention;
[0094] FIG. 15 is a simplified schematic drawing of an exemplary
underwater energy storage system including an inlet pipe for
cooling compressed air in accordance with some embodiments of the
present invention;
[0095] FIG. 16 is a simplified schematic drawing of an exemplary
heat exchange and heat preservation system for use with an
underwater energy storage system in accordance with some
embodiments of the present invention;
[0096] FIG. 17 is a simplified schematic drawing of a variety of
exemplary heat preservation pools for use with an underwater energy
storage system in accordance with some embodiments of the present
invention;
[0097] FIG. 18 is a simplified schematic drawing of an exemplary
heat exchange unit for desalinating water for use with an
underwater energy storage system in accordance with some
embodiments of the present invention; and
[0098] FIGS. 19A and 19B are simplified schematic drawings of
exemplary thermal energy storage elements for use with an
underwater energy storage system in accordance with some
embodiments of the present invention.
DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION
[0099] The present invention, in some embodiments thereof, relates
to underwater energy storage and, more particularly, but not
exclusively, to underwater energy storage of compressed air.
[0100] According to some embodiments of the present invention there
is provided an underwater energy storage unit including a rigid
storage tank equipped with a structure for receiving and containing
weights over a rooftop of the storage tank that can act to
counterbalance pressure differences between compressed air within
the tank and pressure level of water at a height of the roof of the
tank. Optionally, the structure is a banister and the weights
include rocks and sand that are poured over the rooftop. In some
exemplary embodiments, the structure for receiving weights includes
a door for expelling the weights on demand, e.g. to float the tank
above water.
[0101] The present inventors have found that significant pressure
drops may exist across an upper portion of the walls where the
outside water pressure is significantly lower than an inner
pressure of the tank. Optionally, the tank is designed to be wide
and short to avoid large pressure differences at a height above the
floor of the tank. According to some embodiments of the present
invention, the tank is constructed from walls that are reinforced
in a gradual manner to counterbalance the gradually changing
pressure drop along a height of the tank. According to some
embodiments of the present invention, the tank is shaped with a
diameter that decreases over a height of the tank. Optionally, a
diameter of the tank along a height of the structure is defined to
counterbalances increasing tensile forces along a height of the
wall due to increase in pressure drop across the walls. Optionally,
the diameter of the tank steadily decreases so that the tensile
forces on the walls due to pressure drop are maintained constant
over the height of the tank.
[0102] According to some embodiments of the tank includes one or
more openings through which water freely flows in and out of the
tank. Optionally, a pipe connected to one or more openings provides
a water flow opening at a height above a seabed so that water that
flows into the tank does not include solid particles typically
found near the seabed. Optionally the pipe provides for maintaining
free water flow, even when the tank sinks into the seabed.
Typically, the tank also includes one or more openings connected to
pipes through which compressed air can flow into and out of the
tank. Optionally and air flow pipe that directs air from a
compressor to the tank includes formed with heat exchange ribs for
reducing the temperature of the air before entering the underwater
tank.
[0103] According to some embodiments of the present invention, the
underwater tank is partitioned into a plurality of chambers that
have air and optionally water flow communication between them.
Optionally the partitioning provides additional reinforcements to
the tank structure. Optionally, a cavity defined by the banister
above the roof of the tank is also partitioned to provide
reinforcement to walls and ceiling of the tank. Optionally, the
chambers also have water flow communication between them. According
to some embodiments of the present invention, an air flow pipe
directly communicates with one or more of the compartments of a
storage tank. Optionally, a single air flow pipe branches into a
plurality of pipes that directly communicate with each chamber
and/or cell in a single tank.
[0104] According to some embodiments of the present invention the
underwater energy storage system is constructed from a plurality of
tanks, e.g. modular units that have air flow communication between
them. Optionally, a single air flow pipe branches into a plurality
of pipes that directly communicate with each of the modular units.
The present inventors have found that by constructing underwater
energy storage system from a plurality of modular units, each of
the units can have a relatively smaller volume and typically a more
structurally sound construction due its size. Additionally, such a
system can be more cost effective since it can be composed from
standardized sized units.
[0105] According to some embodiments of the present invention, the
underwater storage tank is partially constructed from a flexible
material. Optionally, the tank is floorless and is anchored at a
height above the seabed. Optionally, the tank is partially
constructed from existing geological formations, e.g. a canyon.
Optionally, a rigid underwater storage tank houses a flexible bag
for storing a gas and/or fluid. Optionally the rigid underwater
storage tank includes water flow opening that provides free water
flow in and out of that tank to counterbalance changes in a volume
of the housed flexible bag.
[0106] According to some embodiments of the present invention, the
underwater storage tank is constructed from a frame or mold that
defines an inner cavity that is cast with cement. According to some
embodiments of the present invention, the frame is transported to a
sinking site and the underwater storage tank is cement casted on
site. Optionally, a frame or mold defines a plurality of underwater
tanks that can be in fluid communication. Optionally, one or more
water flow pipes and air flow pipes are fitted onto frame prior to
concrete (or cement) casting.
[0107] According to some embodiments of the present invention, the
underwater energy storage system is an adiabatic system that stores
heat generated during air compression and used the stored heat to
expand and heat discharged air and/or is used to desalinate water.
Optionally, energy is stored in heat exchange reservoirs and/or in
thermal energy storage elements.
[0108] Before explaining at least one embodiment of the invention
in detail, it is to be understood that the invention is not
necessarily limited in its application to the details of
construction and the arrangement of the components set forth in the
following description and/or illustrated in the drawings. The
invention is capable of other embodiments or of being practiced or
carried out in various ways.
[0109] Referring now to the drawings, FIG. 1 illustrates a
simplified schematic drawing of an exemplary underwater energy
storage system and power station powered therewith in accordance
with some embodiments of the present invention. According to some
embodiments of the present invention, an underwater energy storage
system 100 stored in a water body 50, e.g. a sea, lake or reservoir
level and anchored on a bed 80 of the water body 50 includes a
rigid tank 10, an inlet air duct 31 for receiving compressed air,
an outlet air duct 33 for releasing compressed air, and one or more
water ducts 22 and/or water openings 20 for receiving and expelling
water to and from the underwater environment. Typically, tank 10
includes a floor 65 so that flow in and out of tank 10 is only
provided through dedicated openings, e.g. openings 20, 21 for water
flow and 31, 32 for air flow. Typically, tank 10 is filled with
water 25 and compressed air 35.
[0110] According to some embodiments of the present invention, air
compressed with a compressor 94 is pumped and/or feed through inlet
pipe 31 into tank 10 for storage and released through outlet pipe
32 when an energy source is required. Typically, air is compressed
during off-peaks hours, stored in tank 10 and then controllably
released during peak hours when additional energy is required.
Optionally, energy from waves are harnessed to compress air. In
some exemplary embodiments, air released from tank 10 is used to
drive a turbine 92, e.g. a wind turbine connected with electricity
main 97. Optionally, wind turbine 92 directly extends from tank 10,
e.g. tank 10 serves as a structural base for wind turbine 92.
Typically, inlet duct (or pipe) 31 and outlet duct (or pipe) 32 are
equipped with valves 39 for controlling flow through the pipes.
Typically, ducts 31 and 32 are connected to openings in an upper
portion of tank 10 where air is present. Optionally, ducts 2, 3 are
connected to one or more openings in roof 48 of tank 10. In some
exemplary embodiments, inlet and outlet flow of air is provided
with a single duct connected to a single opening in tank 10.
Optionally, a single inlet/outlet duct connected to storage tank 10
branches into one or more additional ducts, e.g. inlet and/or
outlet ducts. Ducts 31 and 32 may be either rigid or flexible.
[0111] According to some embodiments of the present invention,
water is free to flow into and out of water ducts 22 and/or water
openings 20 to balance pressure level in tank 10 as air flows into
and out of tank 10. Typically, compressed air 35 is stored in tank
10 at constant pressure. In some exemplary embodiments, duct or
pipe 22 is connected to a lower part of tank 10 typically below the
expected minimum water level and extends upwards, e.g. with a slope
so that water can be collected into tank 10 from a height above bed
80 of the water body 50 where the water, e.g. sea or lake water is
expected to be clean from particles such as sand and dust.
Optionally, duct or pipe 22 is several meters long, e.g. 5-50
meters or 30 meters to provide unobstructed water flow even in
cases when the tank sinks into bed 80 of the water body.
Optionally, tank 10 includes a plurality of openings for water flow
optionally connected to water flow ducts to provide sufficient
water flow in and out of the tank even in cases when one or more of
the openings are obstructed. Optionally openings 20 and/or ducts 22
are equipped with filters to prevent obstruction of water flow
openings.
[0112] In some exemplary embodiments, an electricity producing
turbine (not shown) is installed in one or more water openings 20
or openings of ducts 22 and is used to generate electricity during
periods of air discharge when water flow is rushed into tank 10. In
some exemplary embodiments, oil 66 is provided in tank 10 to cover
water surface 77 and thereby prevent evaporation of water in tank
10. Optionally, floating structures, e.g. Styrofoam.TM. is added to
cover water surface 77 and thereby prevent evaporation of water in
tank 10. Alternatively, water 77 is not covered with a material to
prevent evaporation.
[0113] Typically, air pressure in tank 10 is maintained at a
pressure level defined by a depth of water 25 in tank 10 and depth
under water level 78 in which tank 10 is submerged. Since the air
pressure in the structure is typically close to or the same as the
external water pressure, storing tank 10 in deeper water, increases
the pressure of air 35 and thereby the amount of air and energy
that it can store.
[0114] According to some embodiments of the present invention,
underwater energy storage system 100 includes a compartment 40 over
ceiling 47 of tank 10 for storing weights and/or fillers 49. In
some exemplary embodiments, weights 49 are composed from sand,
rocks gravel and/or recycled wastes that are poured into and/or
positioned in compartment 40 during and/or after submersion of tank
10 underwater. Optionally weights 49 is cement poured into
compartment 40. In some exemplary embodiments, compartment 40 is
defined by a banister 45 that surrounds roof 48 and/or tank 10.
Optionally, underwater energy storage system 100 includes a frame
244 that extends from tank 10, e.g. from floor 17 and forms a
cavity 43 for receiving weights 49. According to some embodiments
of the present invention, floor 17, frame and/or banister 244 are
integral parts of tank 10, e.g. a single unit with tank 10.
According to some embodiments of the present invention, weights 49
provide a gravitation force 84 on tank 10 for resisting floatation
of the tank. In some exemplary embodiments, compartment 40 is sized
and designed to contain a volume and mass of weights 49 that can
provide a gravitational force that counterbalances pressure drop
across roof 48 generating an upward force 82. This feature is
explained in more detail herein below.
[0115] Optionally, floor 65 includes prongs and/or extensions 18
that are designed to be buried in seabed 80 and thereby stabilize
tank 10 on the seabed. Optionally prongs 18 are an integral part of
tank 10 and are constructed from cement. Alternatively, prongs 18
are constructed from metal extending out from flow 65.
[0116] According to some embodiments of the present invention, tank
10 is constructed from one or more of concrete, cement, metal and
plastic. Typically, tank 10 is constructed as a single unit for
durability. Optionally, tank 10 is constructed from cement with
fibers mixed into the cement that may increase durability of tank
10 and prevent cracking. Optionally fibers from one or more of
polymer material, glass and metal is mixed into the cement. The
present inventor has found that the types of forces and directions
of forces applied on the tank can vary greatly due to changing
conditions in and around the tank. Changes in conditions may be due
for example to changes in the volume of water and/or air in the
tank, to changes in temperature drop across the walls of the tank
and/or due to changes in water currents. According to some
embodiments of the present invention, tank 10 is constructed from a
composite of different types of materials to provide durability
against varying forces, e.g. tensile and compressive forces that
may be applied on tank 10 over time. In some exemplary embodiments,
tank 10 is constructed from reinforced concrete, e.g. concrete
reinforced with metal to provide durability against both tensile
and compressive forces, e.g. metal for providing durability against
tensile forces and concrete for providing durability against
compressive forces. In some exemplary embodiments, tank 10 is
coated inside and/or outside with metal, alloys, polymers or oils.
Optionally, metal coating is used to prevent leakage of air through
cement and to facilitate damage repairs by patching or welding.
Optionally, tank 10 is constructed with reinforced concrete that
includes a metal and/or polymer layer on at least one of the inside
and outside walls. Optionally corrosion and/or cathodic inhibitors
are used to retard corrosion. Optionally, tank 10 may be
cylindrical in shape and have a diameter between 20-200 meters
and/or between 30-120 meters with a height of between 5-20 meters
and/or 5-12 meters. In some exemplary embodiments, compartment 40
has banister 45 with a height that is between 40-100 percent, e.g.
60 percent of a height of tank 10.
[0117] In some exemplary embodiments, tank 10 may be fully or
partially built on land, transported by sea to the desired location
and sunk. In some exemplary embodiments, concrete is poured above
or under sea level in a shell that defines structure of tank 10.
According to some embodiments of the present invention, rocks or
the like is piled over tank 10 to prevent its floating when air is
being compressed into it.
[0118] Reference is now made to FIG. 2 illustrates a simplified
schematic diagram showing exemplary forces acting on an underwater
storage tank due to differential pressure along a height of the
underwater storage tank in accordance with some embodiments of the
present invention. While water pressure in water body 50 such as a
sea, ocean and/or lake varies with depth of the water the air
pressure in a tank 10 is typically constant at any one time and is
defined by a difference between the height of water surface 78 of
water body 50 and a height of water surface 77 contained in tank
10. Typically, the pressure drop across wall 88 increases over
height `H` due to the varying pressure conditions outside tank 10.
Typically, the greatest pressure drop occurs over highest portion
of the walls, e.g. near roof 48 and across roof 48 of tank 10. The
present inventors have found that for utility sized tanks 10, e.g.
tanks, the tensile forces due to the pressure drops may be
significant and may potentially lead to bursting and/or cracking of
tank 10.
[0119] In the exemplary embodiment shown in FIG. 2, tank 10 has a
height of 20 meters (vertical height) and is anchored to a seabed
80 that is 501 meters below sea level 78. When a water level 77 in
tank 10 is low, tank 10 is almost full with compressed air and the
air pressure inside the structure is determined from a difference
in depth of water in tank 10, e.g. water level 77 and depth of
water the seabed (or lakebed), e.g. water level 78. In this
particular example, a water level 77 in tank 10 is at a height of 1
meter above sea level 80, e.g. a depth of 500 meters from sea level
78 so that the air pressure in tank 10 is 51 ATM. The air pressure
of 51 ATM is applied uniformly inside tank 10, e.g. on walls 88 and
ceiling 47 of tank 10 while the water pressure outside of tank 10
changes over height H of tank 10 causing a pressure drop across
walls 88 and ceiling 47 (or roof 48) of tank 10. For example, at a
depth of 490 meters, water pressure outside of tank 10 is 50 ATM
and the pressure drop is 1 ATM. At a depth of 480 meters, water
pressure outside tank 10 is 49 ATM and the pressure drop is 2
ATM.
[0120] The present inventors have found that outward force 82
applied on ceiling 47 (of roof) of tank 10 can be particularly
large because force 82 is a summation of upward pressure 82 applied
to ceiling 47 due to pressure drop and also due to buoyancy and/or
flotation forces of tank 10. According to some embodiments of the
present invention, compartment 40, e.g. an open compartment formed
by roof 48 and banister 45 filled with material 49, e.g. rocks,
gravel and/or sand is adapted to apply a gravitational force 84 to
counterbalance upward force 82. Typically, weight of filling 40 is
defined to match expected upward force 82. The present inventors
have found using weights to counter balance forces simplifies
construction of tank 10 and provides for adjusting counterbalancing
forces on site based on environmental conditions, e.g. depth that
tank 10 is stored. In addition, weights such as sand and rocks are
easily attainable and typically inexpensive.
[0121] According to some embodiments of the present invention,
compartment 40 and/or banister 45 includes a door 60 that can be
controllably opened to release the weights 49 on demand.
Optionally, the door 60 is opened and weights 49 are released from
compartment 40 in cases when it is desired to raise tank 10. In
some exemplary embodiments, tank 10 is raised for repair and/or for
transporting tank 10 to an alternate site, e.g. having a seabed at
a different depth. Optionally, door 60 includes a latch or other
mechanism that is controlled from above the water level 78. In some
exemplary embodiments, inlet/outlet duct 30 extends from ceiling 47
of tank 10 and is surrounded by a shield 38 for protection against
possible damage when pouring the weights over roof 48. Optionally
inlet/outlet duct is a flexible pipe.
[0122] Reference is now made to FIGS. 3A and 3B illustrating
simplified schematic drawing of exemplary underwater energy storage
systems with reinforced construction for withstanding pressure
drops across walls of the storage tank in accordance with some
embodiments of the present invention. According to some embodiments
of the present invention, walls of tank 10 are reinforced to
withstand pressure across walls 88 due to inherently higher
pressure in the upper portion of tank 10 (with respect to the
vertical direction) as compared to the water pressure outside tank
10 at that level. According to some embodiments of the present
invention, the reinforcements are designed to steadily increase
with height of walls 88 so that stronger reinforcement is provided
in upper portions of walls 88 (with respect to vertical) where the
pressure drops across walls 88 is larger.
[0123] Referring now to FIG. 3A, tank 10 is built with walls 88
having a thickness that steadily increases with height so that the
wall thickness is thickest at a height where the pressure drop
across the walls is the largest and thinner where the pressure drop
across the walls is smaller. Widening (or thickening) of the walls
at upper portions of tank 10 may also provide additional support
for ceiling 21. Optionally, tank 10 additionally includes an
external reinforcing belt 61 surrounding tank 10 to reinforce the
wall from the outside against blasting outwardly.
[0124] Referring now to FIG. 3B, in some exemplary embodiments, the
walls of tank 10 are cast with reinforced concrete and the
reinforcements provided are steadily increased with height of the
walls, e.g. by steadily increasing the diameter and/or the
proximity of reinforcement bars added to the concrete or other
casting material. In some exemplary embodiments, reinforcement bars
62 used in lower portion of walls 88 are smaller in diameter as
compared to reinforcement bars 63 having larger diameter.
Optionally, reinforcement bars 62 in lower portion of tank 10 are
more sparsely distributed as compared to reinforcement bars, e.g.
bars 62 or 64 in an upper portion of tank 10. Optionally, the
proximity between bars is increased gradually over height of tank
10. In some exemplary embodiments, this gradual increase in wall
strength provides for withstanding gradually increasing forces due
to increase pressure drops across the wall along the height of the
tank.
[0125] Optionally, tank 10 additionally includes internal walls 86
plated or coated with a material other than the inner wall
material, e.g. constructed from metal. In some exemplary
embodiments, a thickness of internal walls is gradually increased
(or in a step wise fashion) over a height of tank 10 so that it
provides increases reinforcement with height to counterbalance the
increased pressure drop across the walls over the height of tank
10. Optionally, thickness 67 of internal wall 86 in upper portion
of internal wall 86 is larger than thickness 68 in a lower portion
of internal wall 86. Optionally, the thickness of the internal
walls increased by gradually increasing the number of layers making
up the inner wall and/or maybe increased by increasing the
thickness of the layer. Typically, internal wall 86 with varying
thickness provides a smooth internal surface.
[0126] It is noted that although it is possible to construct the
wall with uniform strength, for utility sized underwater energy
storage systems, the gradual reinforcements described herein may
provide for significantly reducing the bill of materials.
[0127] Optionally, ceiling 47 is further reinforced by adding one
or more pillars 69 extending from a floor 65 of tank 10 to ceiling
47. Optionally, further reinforcements may be in the form of a
metal construction 64 extending between the walls 88 and at least
partially supported by walls 88.
[0128] Reference is now made to FIGS. 4A, 4B and 4C illustrating
simplified schematic drawings of exemplary underwater energy
storage systems including a storage tank whose diameter decreases
as a function of tank height in accordance with some embodiments of
the present invention. According to some embodiments of the present
invention, a tank 11 is substantially cone shape and/or includes
walls that taper over the height `H` of tank 11.
[0129] Referring now to FIG. 4A, optionally, weights 49 are poured
over tank 11 and are used to counter balance forces due to pressure
drops and buoyancy in the ceiling as well as on the walls. In some
exemplary embodiments, underwater energy storage system 100
includes a banister or wall 46 around walls of tank 11 providing a
compartment in which weights 49 are stored. Optionally, tank 11 is
dome shaped. Optionally banister 46 surrounds walls of tank 10 at a
height above bottom of tank 11 and above one or more water openings
20. According to some embodiments of the present invention,
banister 49 includes one or more doors 60 that can be opened on
demand to release weights 49. Optionally, doors 60 are manipulated
with a cable 51 from above the water. Optionally, the weights are
added during or after submerging and are removed when it is desired
to float the tank to surface.
[0130] According to some embodiments of the present invention, the
gravitation force exerted on the walls by weights 49 at least
partially counterbalances outward forces, e.g. tensile forces
exerted on the walls and ceiling of tank 11 due to a pressure drop
across the walls 88 and ceiling 47. According to some embodiments
of the present invention, tank 11 is shaped with a changing slope,
e.g. dome shaped so that the counterbalancing force provided by the
weights has increasing force component in a direction perpendicular
to walls for higher levels of walls 88 where the pressure drop is
greater.
[0131] Referring now to FIG. 4B, in some exemplary embodiments,
underwater energy storage system 100 includes a cone shaped (or
bell shaped) underwater compressed gas storage tank 111 with
concave shaped walls 89. In some exemplary embodiments, tank 111 is
shaped so that a diameter of cone shaped tank 111 at a given height
multiplied by at a height above the floor 65 at that given height
is a constant. For example for a tank 111 that has a height `H` of
10 meters, at a height of 1 meter above floor 65, the diameter of
the tank may be 100 meters, at a height of 2 meters above floor 65
the diameter of the tank may be 50 meters, at a height of 5 meters
the diameter of the tank will be 20 meters and at a height of 10
meters the diameter of the tank may be 10 meters wide. The present
inventors have found that altering the diameter in this manner, a
force, e.g. tensile force applied on walls 89 along the height `H`
of tank 111 due to pressure drop can be maintained constant
although the pressure drop across the walls increases with height
of tank 111.
[0132] Referring now to FIG. 4C, in some exemplary embodiments, the
diameter of an underwater compressed gas storage tank 112 is
decreased in a stepwise fashion at defined heights of tank 112. In
some exemplary embodiments, tank 112 is constructed from a
plurality of stories that are fluidly connected through openings 23
between the stories. Typically, each story above a first story has
a smaller diameter than the story under it. In some exemplary
embodiments, each story is cylindrical in shape and is associated
with a constant diameter. Optionally, one or more of the stories of
tank 112 includes walls that taper over a height of the story.
Typically, compressed air is received from the uppermost story via
air duct 30 and water openings 20 are provided on the lowest
story.
[0133] Reference is now made to FIGS. 5A and 5B illustrating
simplified schematic drawings of exemplary underwater energy
storage systems including a cylindrical storage tank that is
partitioned in accordance with some embodiments of the present
invention. According to some embodiments of the present invention,
underwater energy storage unit 100 includes a cylindrical shaped
tank 13 for storing compressed air including partitioning for
reinforcing tank 13 against forces applied on it. According to some
embodiments of the present invention, tank 13 includes partitions
that form chambers 71, e.g. sector shaped chambers. In some
exemplary embodiments, inlet/outlet air duct 30 extends from one or
more of chambers 71. Optionally, air duct 30 is centered over tank
13 and is open to each of chambers 71. In some embodiments of the
present invention, chambers 71 include air openings 33 in upper
portion of each chamber that provides for air flow between
inlet/outlet air duct 30 and each of chambers 44. In some exemplary
embodiments of the present invention, chambers 71 additionally
include water openings 21 in a bottom portion of each chamber 71 to
allow free water flow between chambers 71. Typically, one or more
of chambers 71 include water openings 20 providing water flow
between tank 13 and water body 50.
[0134] Referring now to FIG. 5B, in some exemplary embodiments,
underwater energy storage system 100 includes a compartment 41 for
storing and/or receiving weights 49 above a compressed air tank 13
that is constructed from walls 88 of tank 13 that are extended
above ceiling of tank 13. According to some embodiments of the
present invention, compartment 41 includes partitioning walls that
extend between walls 88 that divide compartment 41 into sectors
shaped compartments 73. In some exemplary embodiments, partitioning
walls 74 provide addition reinforcements to walls and ceiling for
tank 13 against forces acting on tank 13. Optionally, partitioning
walls 74, tank walls 88 and ceiling of tank 13 are constructed as a
single unit, e.g. formed from a single construction for added
durability. In some exemplary embodiments, partitioning 74
reinforces ceiling of tank 13 against breaking outwardly due to the
pressure drop across ceiling.
[0135] According to some embodiments of the present invention,
compartment 41 includes one or more openings and/or doors 60 that
can be opened on demand to release weights 49. Optionally, a floor
of compartment 41 is slanted down toward door 60 such that the
weights fall out of the compartment due to gravitational pull.
Optionally, tank 13 includes reinforcing belt 61 around upper
portion of tank 13 for additional support of the walls 88.
[0136] Reference is now made to FIG. 6 illustrating a simplified
schematic drawing of exemplary underwater energy storage system
including a cuboid storage tank that is partitioned in accordance
with some embodiments of the present invention. According to some
embodiments of the present invention an underwater energy storage
energy system 100, includes a tank 12 that is cuboid shaped and
includes partitioning walls 75 that divide the inner volume into
smaller compartments 71, e.g. cuboid shaped compartments. Typically
partitioning walls 75 provide additional support to a ceiling and
walls of tank 12. According to some embodiments of the present
invention, partitioning walls 75 include opening 33 for free flow
of air between compartments 71 and openings 21 for free flow of
water between compartments 71.
[0137] Optionally, one or more air ducts 30 are connected through
openings in one or only compartments 71 and air flow to and from
duct 30 flows through other compartments through openings 33.
Typically, tank 12 includes openings 20 for free water flow in and
out of tank 12. Optionally, each compartment 71 has dedicated
openings 20 providing water flow communication between tank and
water body 50 and there is no water flow between compartments
71.
[0138] Reference is now made to FIGS. 7A and 7B illustrating
simplified schematic drawings of exemplary underwater energy
storage systems including partitioned tank with reinforced walls
around an air entrance chamber in accordance with some embodiments
of the present invention. According to some embodiments of the
present invention, compressed air storage tank 10 is partitioned
into a plurality of partitions 71, e.g. sector shaped partitions
(FIG. 7A) or grid shaped partitions (FIG. 7B). Typically, each of
the compartments includes air holes 33 through which air can flow
between compartments and to and from an inlet and/or outlet air
duct. According to some embodiments of the present invention, air
flows in and out of tank 10 via one or more central chambers 37
through which an inlet and/or outlet duct, e.g. duct 30, 31 and/or
32 connects to tank 10. According to some embodiments of the
present invention, walls 36 defining chamber 37 are constructed to
be wider and/or have more reinforcements than other walls of tank
10, e.g. walls 75. Optionally, walls 36 are constructed to
withstand shockwaves that may occur as compressed air is feed into
tank 10.
[0139] Reference is now made to FIG. 8 illustrating a simplified
schematic drawing of an exemplary underwater energy storage system
including a plurality of inlet/outlet ducts that converge into a
single duct in accordance with some embodiments of the present
invention. According to some embodiments of the present invention,
an air duct 331 branches into a plurality of ducts 333. In some
exemplary embodiments, each of ducts 333 connect to one of a
plurality of chambers 75. In some exemplary embodiments, branching
of air duct 331 provides reducing potential pressure drop between
different compartments 75. Optionally, reinforcing structures 332
are added around a junction of the branching of ducts 333.
[0140] Reference is now made to FIG. 9 illustrating a simplified
schematic drawing of an exemplary underwater energy storage system
including a plurality of storage tank modules that are fluidly
connected in accordance with some embodiments of the present
invention. According to some embodiments of the present invention,
underwater energy storage system 110 is constructed from a
plurality of underwater compressed air storage tanks 15 that are
fluidly connected through air and/or gas ducts 34 connected between
tanks 15. According to some embodiments of the present invention,
each of tanks 15 additionally includes one or more water flow
openings 20 allowing free flow of water into and out of each tank
15. In some exemplary embodiments, each tank 15 includes a
compartment 40 for receiving weights such as sand gravel and rocks
as described herein above.
[0141] According to some embodiments of the present invention, one
or more air ducts 30 is connected to one or a portion of the tanks
15 on a first end and to a compressor(s) and/or power generating
unit(s) above sea level (or water level) at an opposite second end.
According to some embodiments of the present invention, air flow
through air duct 30 extends or flows to all tanks 15 via air ducts
34. Alternatively, air duct 30 is replaced with air duct 331 (FIG.
8) that are partitioned into a plurality of ducts, each of which is
directly connected to one of tanks 15 so that air flow in and out
of duct 30 is directly communicated to each of tanks 15. Optionally
in such a case, connecting air ducts 34 are not required. The
present inventors have found that constructing an underwater energy
storage system from a plurality of modular tanks 15 that can be
used together to provide energy to a single plant and/or energy
generating (or converting) unit, provides for adjusting a volume of
an underwater energy storage system without having to redesign
and/or resize the underwater compression tank. Optionally, each
tank 15 has a uniform volume and shape. Alternatively, a number of
different sized tanks are manufactured that can be combined in
different ways to meet the demands of specific power sites.
Constructing the underwater energy storage system with modular
storage units, e.g. tanks 15 also provides for reducing cost of the
system since the size and shape of the tanks are standardized and
do not have to be redesigned for different systems.
[0142] It is noted that although most of the embodiments of the
present invention describe an underwater compressed air tank with a
flat roof, other shaped roofs are also in the scope of the present
invention. Optionally roofs of one or more of tanks 10, 12-16 may
have other shapes, e.g. a convex or concave shape.
[0143] Reference is now made to FIGS. 10A and 10B illustrating
simplified schematic drawings of exemplary underwater energy
storage systems including a floorless storage tank that is anchored
at a height above a seabed in accordance with some embodiments of
the present invention. According to some embodiments of the present
invention, underwater energy storage system 200 includes a
floorless or bottomless tank 230 that is held at a defined height
above a seabed 80 with one or more anchors 231 and/or with an
anchor 235 holding a net 234 encompassing tank 230. In some
exemplary embodiments, tank 230 is a rigid tank. Typically, a rigid
construction is more durable than known flexible constructions and
maintains a constant volume. Typically, flexible structures are
more susceptible to damage due biological and/or chemical erosion
occurring underwater or due to mechanical damage caused by fish,
clams and the like that may damage flexibility of the bags and may
tear or puncture the bags.
[0144] According to some embodiments of the present invention, tank
230 is held at a height above a seabed. Optionally, the height over
which tank 230 is held enables unobstructed water flow 232 through
open bottom 242 of the tank 230 even in cases when anchors 231 sink
into the seabed. Typically, tank 230 includes an inlet/outlet air
duct 30 connected to the top of tank 230 through which compressed
air is pumped in for storage and/or released when energy to power a
generator or device is required. Typically, tank 230 includes a
volume of water 25 on a bottom portion of tank 230 and a volume of
air 35 stored on an upper portion of tank 230. Typically, the level
77 of water in tank 230 is determined by the amount of compressed
air stored in tank 230. Optionally, tank 230 is dome shaped.
Optionally, tank 230 is constructed from a flexible and/or
collapsible material. Optionally, tank 230 is in the form of a
truncated sphere (FIG. 10B), a cylinder, a cone, and/or a
hemisphere. In some exemplary embodiments, tank 230 is held at a
defined height above seabed 80 with a net 234, e.g. a metal net
that covers tank 230 and is held by a weight that may rest on
seabed 80.
[0145] Reference is now made to FIG. 11 illustrates a simplified
schematic drawing of an exemplary underwater energy storage system
partially formed from natural underwater landscape formations in
accordance with some embodiments of the present invention.
According to some embodiments of the present invention, underwater
energy storage system includes a tank 229 that is partially formed
from existing under water structures such as walls of a canyon 220.
In some exemplary embodiments, a roof 248 and/or one or more walls
are anchored onto the canyon 220 to form a compressed air tank 229
with an open bottom that allows free water flow 232 from the bottom
of the tank. Typically, compressed air is pumped into an upper
portion of the tank with an air duct 30 and water enters through a
bottom portion of tank 229. Optionally roof 248 is constructed from
concrete casting.
[0146] Reference is now made to FIGS. 12A, 12B and 12C illustrating
simplified schematic drawings of exemplary underwater energy
storage systems including a flexible storage bag in accordance with
some embodiments of the present invention. According to some
embodiments of the present invention, an underwater energy storage
system 102 includes underwater compressed air tank 230 that is
partially formed with flexible and/or collapsible material 241,
e.g. a large plastic bag that forms an open bottom tank. In some
exemplary embodiments, tank 230 is surrounded by a protective cage
243, e.g. a metal grating to provide rigidity to tank 230 and/or to
strengthen construction of tank 230 (FIG. 12A). Optionally, a
bottom 242 of tank 230 is maintained open by attaching collapsible
material 241 to a rigid rim and/or ring 251 of cage 243. In other
exemplary embodiments, tank 230 is not protected by a cage 243 but
a rigid ring 251 is attached to open end of tank 230 (FIG. 12B) and
is used to maintain tank 230 open and prevent it from collapsing
completely. Typically, anchor 231 is attached to tank 230 through
rigid structure of ring 251 and/or of cage 243 to prevent tearing
of material 241. In yet other embodiments of the present invention,
tank 230 is formed from a bag from flexible and/or collapsible
material 241 that is maintained at a height above a seabed 80 with
a frame 244 that sits on seabed 80 (FIG. 12C).
[0147] Optionally, frame 244 forms cavity and/or hollow space 43
filled with rocks 49 providing a gravitation force for anchoring
tank 230. In some exemplary embodiments, water flows freely into
and out of tank 230 through water openings 20 and/or through duct
22 formed in (or extending from) frame 244 to counterbalance inflow
or outflow of air 35 through inlet/outlet pipe 30.
[0148] Optionally, air tanks 230 may be particularly suitable when
smaller volume tanks, e.g. having a diameter of a few meters, e.g.
5-10 meters are required. Typically, floorless air tanks, e.g.
rigid or collapsible are smaller and also cheaper to manufacture
and may be suitable for smaller scaled applications and/or as
additions to larger scaled applications. Optionally, air tanks 230,
e.g. collapsible or rigid may be particularly suitable for storing
compressed air over a seabed that has a sharp incline, over a
seabed that is generally not flat, e.g. has large rocks and/or over
a seabed that is generally not suitable for supporting a large
structure having a flat floor. In some exemplary embodiments, tank
230 designed to float over a seabed provides a cost effective
alternative to flattening out a rocky area of a seabed so that a
tank may be positioned over the seabed.
[0149] Reference is now made to FIG. 13 illustrating a simplified
schematic drawing of an exemplary underwater energy storage system
including a flexible compressed energy storage container housed in
rigid storage underwater tank in accordance with some embodiments
of the present invention. According to some embodiments of the
present invention, underwater energy storage system 101 includes
rigid storage tank 10 that stores compressed soluble gases or
fluids in a flexible bag 260 housed within rigid storage tank 10.
Optionally, bag 260 stores condensed carbonic gas. In some
exemplary embodiments, the gases or fluids are feed into bag 260
via duct 30 that extends above water level 78. Optionally the
soluble gases and/or liquids are hazardous materials that require
storage in safe and stable conditions. Optionally, rigid
construction of tank 10 protects container 260 from swaying and
erosion, e.g. due to biological and/or chemical erosion or due to
mechanical damage caused by fish, clams and the like that may
damage flexibility of the bags. Typically, the rigid construction
of tank 10 provides stability, anchoring and with holding
pressures.
[0150] In some exemplary embodiments, tank 10 is anchored to a
seabed and allows free water flow into and out of tank 10 through
one or more water channels 20. Typically, free water flow through
channels 20 provide for stabilizing pressure in tank 10. For
example as more material is feed into bag 260, bag 260 expands and
water 25 is expelled from tank 10. Optionally, a flexible cable or
line 231 is attached to a bottom of bag 260 on one end and to floor
65 on another end to avoid jamming opening to air duct 30.
Typically, inner walls 87 of tank 10 are smooth and/or rounded to
protect bag 260 from being punctured. Optionally, inner walls 87
are additionally coated with smooth low friction and/or friction
protective materials such as various polymers.
[0151] Reference is now made to FIGS. 14A and 14B illustrating
simplified schematic drawings showing an exemplary method for
casting and sinking an exemplary underwater storage system in
accordance with some embodiments of the present invention.
According to some embodiments of the present invention, an
underwater energy storage system 1215 includes a metal or polymer
frame or mold 170 that defines one or more tanks 171 for storing
energy, e.g. in the form of compressed air. In some exemplary
embodiments, each tank 171 is fitted with a floor 65. Optionally,
tank 171 does not include a floor. Optionally, the floor is a metal
or polymer floor. Typically, frame 170 includes one or more
openings though which water pipes 21 are fitted between neighboring
tanks 171 and through which water ducts between the chambers and
outside walls are fitted. Typically, frame 170 includes one or more
openings through which one or more inlet/outlet pipes 30 are
fitted. In some exemplary embodiments, frame 170 additionally
includes one or more openings through which air pipes 33 between
neighboring tanks are fitted. According to some embodiments of the
present invention, frame 170 defines an inner portion and/or cavity
180 that can be filled with material, e.g. concrete to complete
construction of system 1215. In some exemplary embodiments, frame
170 is filled on site, e.g. after transportation to a desired
sinking location.
[0152] According to some embodiments of the present invention,
frame 170 is transported on water to a desired sinking location.
Typically, during transport, water openings 20 are closed so that
water does not enter tanks 171. Optionally, once a desire sinking
location is reached, system 1215 is anchored with one or more
anchors 213 so immobilize system 1215. Optionally, frame 170 is
transported by a ship and a crane is used to lower frame into the
water. According to some embodiments of the present invention,
concrete is poured into cavity 180 while system 1215 is floating
over a desired sinking location. In some exemplary embodiments, a
concrete mixer 176 brought to the spot on board a ship 177 or barge
pours concrete into cavity 180 using a concrete pump 178 to fill
cavity 180. In some exemplary embodiments, air trapped in tanks 171
keeps system 1215 afloat while the cement is being poured.
Optionally one or more buoys 196 are used keep system afloat while
the cement is being poured.
[0153] According to some embodiments of the present invention, once
the casting is completed and the casting is sufficiently dray,
system 1215, valves 23 on water openings 20 and valves 39 on air
pipes 30 are opened and so that water enters tanks 171 and system
1215 can sink to the desired location. Optionally, if tanks 171 are
floorless, channels 20 are always open and only valves 39 are
opened to allow air release through pipe 30. In some exemplary
embodiments, buoys, e.g. buoy chains are used to stabilize system
1215 and control the sinking speed.
[0154] Reference is now made to FIG. 15 illustrating an a
simplified schematic drawing of an exemplary underwater energy
storage system including an inlet pipe for cooling compressed air
in accordance with some embodiments of the present invention.
According to some embodiments of the present invention, underwater
energy storage system 104 includes an inlet pipe 31 through which
compressed air flows from a compressor (not shown) to a compressed
air tank 10. In some exemplary embodiments, compressed air pumped
into pipe 31 is at a high temperature, e.g. hundreds of degrees
Celsius and requires cooling prior to entering tank 10. If air
enters underwater tank 10 at significantly higher temperatures than
surrounding environment, the temperature drop across tank 10 may
cause cracks and/or damage to tank 10. In some exemplary
embodiments, inlet pipe 31 includes one or more heat exchange ribs
along a length of inlet pipe 31 to promote cooling of air flowing
through pipe 31. In some exemplary embodiments pipe 31 includes one
or more ribs 55 encompassing outer diameter 31 for enhancing heat
exchange between water 50 and air within pipe 31. Optionally, the
outer ribs 55 shaped as flat rings. Optionally, outer ribs 55 are
constructed to be aligned with water currents typical found in an
area where system 104 is situated. Optionally, rib 55 is a single
spiral shaped rib that extends along a length of pipe 31.
Optionally, walls of tank 10 include heat transfer elements that
are operable to release heat that may be stored in tank 10.
Optionally water outlet 22 provides a mechanism for releasing heat
accumulated in tank 10.
[0155] Reference is now made to FIG. 16 illustrating a simplified
schematic drawing of an exemplary heat exchange and heat
preservation system for use with an underwater energy storage
system in accordance with some embodiments of the present
invention. According to some embodiments of the present invention,
underwater energy storage system 105 is an adiabatic system (or
semi-adiabatic system) that retains heat produced by compression
and returns it to the air when the air is expanded to generate
power. Typically, during compression a large amount of heat is
created in compressor 94 and inlet pipe 31 carrying air from
compressor to underwater tank 10. In some exemplary embodiments,
pipe 31 first passes through a fluid reservoir and/or a heat
exchange pool 272 where heat in pipe 31 is released. In some
exemplary embodiments, reservoir 272 is thermally isolated.
Optionally, pipe 31 includes one or more ribs 55 around a portion
pipe 31 within fluid reservoir 272 for enhancing heat exchange
within the reservoir. Optionally, compressor 94 includes cooling
ribs 95 that are additionally submerged in fluid of fluid reservoir
272 for cooling (submerging is not shown). Typically, heat
accumulated rises in reservoir 272.
[0156] In some exemplary embodiments, heat accumulated in reservoir
272 rises to an upper portion of the tank and is used to heat air
released from tank 10 through pipe 32 prior to being used for
operating a turbine 92. Typically, pipe 32 passes through an upper
portion of reservoir 272 where the heated fluid rises. Optionally,
pipe 32 also includes one or more ribs 55 around a portion of pipe
32 within reservoir 272 for enhancing heat exchange. Typically,
heat exchange with pipe 32 results in cooling and cooled fluid
flows to a bottom of reservoir 272 which can be later used to cool
air through pipe 31.
[0157] Reference is now made to FIG. 17 illustrating a simplified
schematic drawing of a variety of exemplary heat preservation pools
for use with an underwater energy storage system in accordance with
some embodiments of the present invention. According to some
embodiments of the present invention one or more air flow pipes 31
providing air flow from an air compressor to an underwater
compressed air storage tank 10 pass through a heat preservation
pool 273 and/or a heat exchange unit to accumulate heat created
during compression that can later be used for heating air
discharged from tank 10 (air discharge pipe is not shown).
Typically air flow pipe includes ribs 55 for enhancing heat
exchange. In some exemplary embodiments a pool 273 is constructed
from an isolating material, e.g. a flexible or rigid isolating
material and is filled with water. Typically, a volume of pool 273
will depend on a volume of a tank 10 and depth (or compression
level) in which it is stored and will typically be larger than
thank 10. In one example, a tank 10 stored at a depth of about 400
meters may have a volume of about 30,000 m.sup.3 and an associated
pool 273 may have a volume of 10,000 m.sup.3. In some exemplary
embodiments, pool 273 floats in seawater 50. Optionally, buoys 281
are used to help pool 273 float. Optionally buoys 281 are also
designed to cover water surface in pool and thereby prevent
evaporation of the water in pool 273. Alternatively and/or
additionally, a pool 273 lies near a beach or on land and air flow
pipes 31 pass through pools 273. In some exemplary embodiments,
pool 276 is formed with a damn 278 constructed at a distance from a
beach, and the seabed 80 between the damn and the beach. Typically
damn 278 extends above sea level 78 and separates a body of water
from the sea to form pool 276. In some exemplary embodiments, heat
exchange is performed over surface water 78 and used to condensed
water vapors in air. Optionally, condensed water vapors 284 are
collected in a collection channel 285 and directed to a collection
tank 286. Optionally, condensed water vapors in collection tank 286
can be used as a fresh water source.
[0158] Reference is now made to FIG. 18 illustrating an exemplary
heat exchange unit for desalinating water for use with an
underwater energy storage system in accordance with some
embodiments of the present invention. According to some embodiments
of the present invention, an air release pipe 32 gathers heat from
the surroundings when the pressure begins to fall. Typically, air
from pipe 32 cools significantly as pressure falls. In some
exemplary embodiments, air from pipe 32 is conducted through a
larger, thermally insulated pipe 312 around which a fluid with a
low freezing temperature flows, e.g. through a vessel 313. In some
exemplary embodiments, discharged air is further heated by passing
it through a heat reservoir 320 prior to using the air as an energy
source, e.g. to operate a turbine.
[0159] In some exemplary embodiments a pump 315 pumps fluid in
vessel 313 through a pipe system 314 and/or heat exchanging ribs
316. In some exemplary embodiments, heat exchanging ribs 316 are
positioned over a water surface and due to cooling, water vapors
317 condense on them and flow down into a collection unit 319
including a collection tank 277. Alternatively, heat exchanging
ribs 316 are immersed in sea water and the cooling provided causes
the surrounding water, e.g. water in a collection tank to freeze.
Optionally, the thawed ice is collected and used as a fresh water
source.
[0160] Reference is now made to FIGS. 19A and 19B illustrating
simplified schematic drawings of exemplary thermal energy storage
elements for use with an underwater energy storage system in
accordance with some embodiments of the present invention.
According to some embodiments if the present invention, heat
generated during air compression is stored in solid thermal storage
elements. In some exemplary embodiments, the solid thermal storage
elements is formed from a solid ball 321, e.g. a cement or ceramic
ball for storing heat that includes one or more metal rods 322 that
extend out of and/or through cement ball 322. Optionally metal rods
322 is used enhance heat transfer into cement ball 322. Optionally,
material other than metal is included in balls 321 to increase heat
transfer. Typically, rods 322 embedded in ball 322 enhance heat
exchange between the surrounding environment and cement balls 321.
Optionally, a material in the form of a powder or small particles,
e.g. nano-particles is used as solid thermal storage elements. The
present inventor has found adding material such as metal, e.g. such
as rods 322, powder or small particles that has a high thermal
conductivity to materials that can store heat, e.g. ceramics and
concrete with low thermal conductivity improves the efficiency
thermal storage element.
[0161] According to some embodiments of the present invention, a
pipe including high temperature air flowing from a compressor to an
underwater compressed air tank passes through a reservoir filled
with balls 321 prior to entering into underwater storage tank. Heat
dissipated from the pipe is stored in balls 321 for later use.
[0162] In some exemplary embodiments, a solid thermal storage
element is in the form of a solid block 323, e.g. a cuboid or
cylinder shaped block formed around one or more inlet air pipes 31
and discharge air pipe 32. Typically, solid block is constructed
from cement or a ceramic material. Optionally, the cement or
ceramic is mixed with metal fibers or metal particles for enhancing
heat transfer. Optionally, ribs 324, e.g. running lengthwise along
pipe 31 within solid block provide in enhancing heat exchange
between air in pipes 31 and 32 and solid block 323. Optionally,
heat accumulated in sold block 323 during off-peak hours when air
is compressed and directed into an underwater storage tank, is
stored in block 323 and later used to heat discharge air used to
generate power during peak hours.
[0163] It is noted that although most of the embodiments of the
present invention have been described in reference to underwater
energy storage systems that are stored in the sea, the embodiments
of the present invention are not necessarily limited in that
respect and can also be applied for underwater energy storing in
other water bodies, e.g. lakes and reservoirs.
[0164] It is noted that although most of the embodiments of the
present invention have been described in reference to storage of
compressed air, other gases and/or fluids maybe stored with
underwater energy storage system described hereinabove.
[0165] The terms "comprises", "comprising", "includes",
"including", "having" and their conjugates mean "including but not
limited to".
[0166] The term "consisting of" means "including and limited
to".
[0167] The term "consisting essentially of" means that the
composition, method or structure may include additional
ingredients, steps and/or parts, but only if the additional
ingredients, steps and/or parts do not materially alter the basic
and novel characteristics of the claimed composition, method or
structure.
[0168] Whenever a numerical range is indicated herein, it is meant
to include any cited numeral (fractional or integral) within the
indicated range. The phrases "ranging/ranges between" a first
indicate number and a second indicate number and "ranging/ranges
from" a first indicate number "to" a second indicate number are
used herein interchangeably and are meant to include the first and
second indicated numbers and all the fractional and integral
numerals therebetween.
[0169] It is appreciated that certain features of the invention,
which are, for clarity, described in the context of separate
embodiments, may also be provided in combination in a single
embodiment. Conversely, various features of the invention, which
are, for brevity, described in the context of a single embodiment,
may also be provided separately or in any suitable subcombination
or as suitable in any other described embodiment of the invention.
Certain features described in the context of various embodiments
are not to be considered essential features of those embodiments,
unless the embodiment is inoperative without those elements.
* * * * *