U.S. patent application number 12/912991 was filed with the patent office on 2011-02-24 for hydraulic energy accumulator.
This patent application is currently assigned to YSHAPE, Inc.. Invention is credited to Marian V. GOGOANA, James B. Whitttaker.
Application Number | 20110041490 12/912991 |
Document ID | / |
Family ID | 39497082 |
Filed Date | 2011-02-24 |
United States Patent
Application |
20110041490 |
Kind Code |
A1 |
GOGOANA; Marian V. ; et
al. |
February 24, 2011 |
HYDRAULIC ENERGY ACCUMULATOR
Abstract
Example energy storage systems (20, 20', 20'') comprises a fluid
circuit (22, 22', 22'') and an electrical unit (24, 24', 24'')
configured to operate as a motor in a first phase of operation and
to operate as a generator in a second phase of operation. The fluid
circuit (22, 22', 22'') comprises a first fluid container (30, 30',
30'') situated so content of the first fluid container experiences
a first pressure level; a tank (32, 32', 32'') having its content
at a second pressure level (the second pressure level being less
than the first pressure level): and, a first hydraulic motor/pump
unit (34, 134, 34'') connected to communicate a first working fluid
between the tank and the first fluid container. In the first phase
of operation electricity is supplied to the first hydraulic/motor
unit (34, 134, 34'') whereby the first hydraulic/motor unit
transmits the first working fluid from the tank into the first
fluid container (30, 30', 30''). In the second phase of operation
pressurized first working fluid in the first fluid container (30,
30', 30'') is transmitted from the first fluid container through
the first hydraulic/motor unit 34, 134, 34'') to the tank (32, 32',
32''), thereby causing the electrical unit (24, 24', 24'') to
generate electricity.
Inventors: |
GOGOANA; Marian V.;
(Merrimack, NH) ; Whitttaker; James B.;
(Arlington, VA) |
Correspondence
Address: |
NIXON & VANDERHYE, PC
901 NORTH GLEBE ROAD, 11TH FLOOR
ARLINGTON
VA
22203
US
|
Assignee: |
YSHAPE, Inc.
Merrimack
NH
|
Family ID: |
39497082 |
Appl. No.: |
12/912991 |
Filed: |
October 27, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11947238 |
Nov 29, 2007 |
7843076 |
|
|
12912991 |
|
|
|
|
60867658 |
Nov 29, 2006 |
|
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Current U.S.
Class: |
60/484 |
Current CPC
Class: |
F15B 1/024 20130101 |
Class at
Publication: |
60/484 |
International
Class: |
F16D 31/02 20060101
F16D031/02 |
Claims
1. An energy storage system comprising: a fluid circuit comprising:
a first fluid container situated so content of the first fluid
container experiences a first pressure level; a tank configured so
that content of the tank is at a second pressure level, the second
pressure level being less than the first pressure level; a first
hydraulic motor/pump unit connected to communicate a first working
fluid between the tank and the first fluid container; an electrical
unit configured to operate as a motor in a first phase of operation
and to operate as a generator in a second phase of operation,
wherein in the first phase of operation electricity is supplied to
the first hydraulic/motor unit whereby the first hydraulic/motor
unit transmits the first working fluid from the tank into the first
fluid container, and wherein in the second phase of operation
pressurized first working fluid in the first fluid container is
transmitted from the first fluid container through the first
hydraulic/motor unit to the tank thereby causing the electrical
unit to generate electricity.
2. The apparatus of claim 1, wherein the first hydraulic motor/pump
unit is connected between the tank and the first fluid container;
wherein the first pressure level is vacuum; and wherein the first
fluid container is submerged whereby the first pressure level is
hydrostatic pressure.
3. The apparatus of claim 2, wherein the first fluid container
comprises a first flexible bladder.
4. The apparatus of claim 2, wherein the fluid circuit and the
electrical unit are situated below the reference pressure
level.
5. The apparatus of claim 2, further comprising a ballast
configured to prevent at least a portion of the system from
floating.
6. The apparatus of claim 3, further comprising: a second fluid
container situated so that content of the second fluid container is
at a second container pressure level, the second container pressure
level being less than the first pressure level; a second hydraulic
motor/pump unit; a third hydraulic motor/pump unit; wherein the
second hydraulic motor/pump unit is operatively connected to the
electrical unit and fluidically connected between the second fluid
container and the third hydraulic motor/pump unit, wherein the
third hydraulic motor/pump unit is fluidically connected between
the second hydraulic motor/pump unit and the first fluid container;
and wherein the second hydraulic motor/pump unit and the third
hydraulic motor/pump unit are configured during the first phase of
operation to operate as pumps to transmit fluid from the second
fluid container to the first fluid container, and during the second
phase of operation to operate as motors as fluid from the first
fluid container is transmitted to the second fluid container;
wherein the electrical unit is configured during the first phase of
operation to operate as the motor for the second hydraulic
motor/pump unit and during the second phase of operation to operate
as a generator driven by the second hydraulic motor/pump unit.
7. The apparatus of claim 1, further comprising: a second fluid
container, the first hydraulic motor/pump unit being fluidically
connected between the tank and the second fluid container for
communicating a second working fluid between the tank and the
second fluid container; wherein the first working fluid comprises
compressed gas; wherein the first fluid container is submerged in a
liquid, the first fluid container having a fluid container first
internal region in communication with the liquid and a fluid
container second internal region in communication with the
compressed gas; wherein the first hydraulic motor/pump unit is
configured during the first phase of operation to operate as a pump
to transmit the second working fluid from the second fluid
container to the tank and thereby drive the first working fluid
from the tank to the fluid container first internal region and
during the second phase of operation to operate as a motor as the
second working fluid is driven by the first working fluid from the
tank to the second fluid container; wherein the electrical unit is
configured during the first phase of operation to operate as the
motor for the first hydraulic motor/pump unit and during the second
phase of operation to operate as a generator driven by the first
hydraulic motor/pump unit.
8. The apparatus of claim 1, further comprising: an electrical
power source; a cable network configured during the first phase of
operation to convey electricity from the electrical power source to
the electrical unit to operate the electrical unit during the first
phase of operation and configured during the second phase of
operation to transmit electricity generated by the electrical unit
to the electrical power source.
9. The apparatus of claim 8, wherein the electrical power source is
a power grid, a storage cell, or a renewable power source.
10. The apparatus of claim 8, further comprising a transformer
connected on the cable network between the electrical power source
and the electrical unit.
11. A method of operating an energy storage system, the method
comprising: situating a first fluid container so content of the
first fluid container experiences a first pressure level; situating
a tank so that content of the tank is at a second pressure level,
the second pressure level being less than the first pressure level;
providing an electrical unit configured to operate as a motor in a
first phase of operation and to operate as a generator in a second
phase of operation; communicating a first working fluid between the
tank and the first fluid container in a first direction during the
first phase of operation and in a second direction during the
second phase of operation, in the first phase of operation
supplying electricity to the first hydraulic/motor unit whereby the
first hydraulic/motor unit transmits the first working fluid from
the tank into the first fluid container; in the second phase of
operation transmitting pressurized first working fluid in the first
fluid container from the first fluid container through the first
hydraulic/motor unit to the tank thereby causing the electrical
unit to generate electricity.
12. The method of claim 11, further comprising connecting the first
hydraulic motor/pump unit between the tank and the first fluid
container; situating the first fluid container below a reference
pressure level; and submerging the first fluid container whereby
the first pressure level is hydrostatic pressure.
13. The method of claim 12, further comprising using a first
flexible bladder as the first fluid container.
14. The method of claim 12, further comprising situating the fluid
circuit and the electrical unit below the reference pressure
level.
15. The method of claim 12, further comprising using a ballast to
prevent at least a portion of the system from floating.
16. The method of claim 13, further comprising: situating a second
fluid container situated so that content of the second fluid
container is at a second container pressure level, the second
container pressure level being less than the first pressure level;
providing a second hydraulic motor/pump unit and a third hydraulic
motor/pump unit, the second hydraulic motor/pump unit being
operatively connected to the electrical unit and fluidically
connected between the second flexible bladder and the third
hydraulic motor/pump unit, wherein the third hydraulic motor/pump
unit is fluidically connected between the second hydraulic
motor/pump unit and the first flexible bladder; during the first
phase of operation operating the second hydraulic motor/pump unit
and the third hydraulic motor/pump unit as pumps to transmit fluid
from the second flexible bladder to the first flexible bladder,
during the second phase of operation operating the second hydraulic
motor/pump unit and the third hydraulic motor/pump unit as motors
as fluid from the first flexible bladder is transmitted to the
second flexible bladder; during the first phase of operation
operate the electrical unit as the motor for the second hydraulic
motor/pump unit; and during the second phase of operation operating
the electrical unit as a generator driven by the second hydraulic
motor/pump unit.
17. The method of claim 11, further comprising: providing a second
fluid container with the first hydraulic motor/pump unit being
fluidically connected between the tank and the second fluid
container for communicating a second working fluid between the tank
and the second fluid container; providing the first working fluid
as comprising compressed gas; submerging the first fluid container
in a liquid and providing in the first fluid container a fluid
container first internal region in communication with the liquid
and a fluid container second internal region in communication with
the compressed gas; during the first phase of operation operating
the first hydraulic motor/pump unit as a pump to transmit the
second working fluid from the second fluid container to the tank
and thereby drive the first working fluid from the tank to the
fluid container first internal region; during the second phase of
operation operating the hydraulic motor/pump unit as a motor as the
second working fluid is driven by the first working fluid from the
tank to the second fluid container; during the first phase of
operation operating the electrical unit as the motor for the first
hydraulic motor/pump unit; and during the second phase of operation
operating the hydraulic motor/pump unit as a generator driven by
the first hydraulic motor/pump unit.
Description
[0001] This application is a continuation of U.S. Non-provisional
patent application Ser. No. 11/947,238, filed Nov. 29, 2007, which
claims the priority and benefit of U.S. Provisional Patent
Application 60/867,658, filed Nov. 29, 2006, entitled "Hydraulic
Energy Accumulator", both of which are incorporated herein by
reference in their entirety.
BACKGROUND
[0002] I. Technical Field
[0003] This invention pertains to the storage of energy, and
particularly to the storage of electricity during a low demand time
period for retrieval during a high demand time period.
[0004] II. Related Art and Other Considerations
[0005] In many geographical or utility service areas the demand for
electricity varies during a day or other time period. For example,
power consumption during a hot summer day may be considerably
greater than for the night. And typically the per unit cost of
power is greater during a peak time period than for an off-peak or
lower demand time period, with a kilowatt hour (KWH) sometimes
being many times more expensive in peak demand time periods than in
low demand periods.
[0006] Supply, delivery, and affordability of power during peak
times can thus be problematic. For this reason in some localities
or regions it can be advantageous to accumulate and store power
(e.g., electricity) during non-peak time periods so that the stored
power can instead be utilized during a peak demand time. In view of
such factors as scarcity and/or the greater cost of electricity
during peak demand times, the accumulation and storage of
electricity for time re-distribution is often desirable, even
though the act of accumulating and storing the electricity may
itself consume energy.
[0007] Electrical power availability can be time re-distributed in
several traditional ways. One way is to store electrical energy by
pumping water to a high altitude during non-peak demand times and
then turbining the water at peak hours for electricity generation.
Other ways involve such techniques or mechanisms such as
compressing air in caves (CAES) during non-peak demand times; use
of flywheels, and chemical storage or the like. Example prior art
techniques are non-exhaustively illustrated in U.S. Pat. No.
4,281,256; U.S. Pat. No. 3,163,985; and U.S. Pat. No. 4,353,214,
for example.
[0008] Without electricity re-distribution techniques such as the
foregoing, industry is forced to increase production capacity in
order to meet ever increasing peak demands. And yet some of the
existing electricity re-distribution techniques have their own
disadvantages and inefficiencies.
BRIEF SUMMARY
[0009] An example energy storage system comprises a fluid circuit
comprising an electrical unit configured to operate as a motor in a
first phase of operation and to operate as a generator in a second
phase of operation. The fluid circuit comprises a first fluid
container situated so content of the first fluid container
experiences a first pressure level; a tank having its content at a
second pressure level (the second pressure level being less than
the first pressure level): and, a first hydraulic motor/pump unit
connected to communicate a first working fluid between the tank and
the first fluid container. In the first phase of operation
electricity is supplied to the first hydraulic/motor unit whereby
the first hydraulic/motor unit transmits the first working fluid
from the tank into the first fluid container. In the second phase
of operation pressurized first working fluid in the first fluid
container is transmitted from the first fluid container through the
first hydraulic/motor unit to the tank, thereby causing the
electrical unit to generate electricity.
[0010] In some example embodiments, the first hydraulic motor/pump
unit is connected between the tank and the first fluid container;
the first fluid container is situated below a reference pressure
level; and the first fluid container is submerged. Pressure
experienced by the first fluid container at the first pressure
level occurs by reason of submersion and causes, during the second
phase of operation, the first working fluid to be forced back to
the tank. Transmission of the first working fluid back to the tank
causes the first hydraulic motor/pump unit to operate as a motor to
drive the electrical unit which operates as a generator of
electricity.
[0011] In some example embodiments, the first fluid container
comprises a first flexible bladder which is submerged in liquid
(e.g., under a reference pressure level such as a surface level of
the liquid, e.g., sea level). In some example embodiments, the
fluid circuit and the electrical unit are also situated below the
reference pressure level (e.g., below sea level). In such example
embodiments, the system can further comprise a ballast configured
to prevent at least a portion of the system from floating.
[0012] Another example embodiment of energy storage system further
comprises a second fluid container; a second hydraulic motor/pump
unit; and, a third hydraulic motor/pump unit. The second fluid
container is situated so that content of the second fluid container
is at a second container pressure level, the second container
pressure level being less than the first pressure level. The second
hydraulic motor/pump unit is operatively connected to the
electrical unit and fluidically connected between the second fluid
container and the third hydraulic motor/pump unit. The third
hydraulic motor/pump unit is fluidically connected between the
second hydraulic motor/pump unit and the first fluid container. The
second hydraulic motor/pump unit and the third hydraulic motor/pump
unit are configured during the first phase of operation to operate
as pumps to transmit fluid from the second fluid container to the
first fluid container. The second hydraulic motor/pump unit and the
third hydraulic motor/pump unit are configured during the second
phase of operation to operate as motors as fluid from the first
fluid container is transmitted to the second fluid container. The
electrical unit is configured during the first phase of operation
to operate as the motor for the second hydraulic motor/pump unit
and during the second phase of operation to operate as a generator
driven by the second hydraulic motor/pump unit.
[0013] Another example embodiment of energy storage system further
comprises a second fluid container, with the first hydraulic
motor/pump unit being fluidically connected between the tank and
the second fluid container for communicating a second working fluid
between the tank and the second fluid container. In this example
embodiment, the first working fluid comprises compressed gas. The
first fluid container is submerged in a liquid and has a fluid
container first internal region in communication with the liquid
and a fluid container second internal region in communication with
the compressed gas.
[0014] The first hydraulic motor/pump unit is configured during the
first phase of operation to operate as a pump to transmit the
second working fluid from the second fluid container to the tank
and thereby drive the first working fluid from the tank to the
fluid container first internal region and during the second phase
of operation to operate as a motor as the second working fluid is
driven by the first working fluid from the tank to the second fluid
container. The electrical unit is configured during the first phase
of operation to operate as the motor for the first hydraulic
motor/pump unit and during the second phase of operation to operate
as a generator driven by the first hydraulic motor/pump unit.
[0015] One or more of the example embodiments typically
additionally comprises an electrical power source and a cable
network configured during the first phase of operation to convey
electricity from the electrical power source to the electrical unit
to operate the electrical unit during the first phase of operation
and configured during the second phase of operation to transmit
electricity generated by the electrical unit to the electrical
power source. In differing embodiments, the electrical power source
can be a power grid; a storage cell; and/or a renewable power
source. As an example implementation, a transformer may be
connected on the cable network between the electrical power source
and the electrical unit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The foregoing and other objects, features, and advantages of
the invention will be apparent from the following more particular
description of preferred embodiments as illustrated in the
accompanying drawings in which reference characters refer to the
same parts throughout the various views. The drawings are not
necessarily to scale, emphasis instead being placed upon
illustrating the principles of the invention.
[0017] FIG. 1 is a schematic view of an energy storage system
according to an example embodiment including a fluid circuit and an
electrical unit.
[0018] FIG. 1A is a schematic view showing operation of the energy
storage system of FIG. 1 in a first phase of operation.
[0019] FIG. 1B is a schematic view showing operation of the energy
storage system of FIG. 1 in a second phase of operation.
[0020] FIG. 2 is a schematic view of the energy storage system of
FIG. 1 employed in a submerged implementation.
[0021] FIG. 3 is a schematic view of an energy storage system
according to an example embodiment and further showing an example
power station served by the energy storage system.
[0022] FIG. 4 is a schematic view of an energy storage system
connected to a power supply system which is in the form of an
electrical grid.
[0023] FIG. 5 is a schematic view of an energy storage system
connected to a power supply system which is in the form of natural
energy source such as a wind-driven power source.
[0024] FIG. 6 is a schematic view of an energy storage system
according to another example embodiment.
[0025] FIG. 7 is a schematic view of an energy storage system
according to yet another example embodiment.
[0026] FIG. 8 is a schematic view of an energy storage system
according to still yet another example embodiment.
DETAILED DESCRIPTION
[0027] In the following description, for purposes of explanation
and not limitation, specific details are set forth such as
particular architectures, interfaces, techniques, etc. in order to
provide a thorough understanding of the present invention. However,
it will be apparent to those skilled in the art that the present
invention may be practiced in other embodiments that depart from
these specific details. That is, those skilled in the art will be
able to devise various arrangements which, although not explicitly
described or shown herein, embody the principles of the invention
and are included within its spirit and scope. In some instances,
detailed descriptions of well-known devices, circuits, and methods
are omitted so as not to obscure the description of the present
invention with unnecessary detail. All statements herein reciting
principles, aspects, and embodiments of the invention, as well as
specific examples thereof, are intended to encompass both
structural and functional equivalents thereof. Additionally, it is
intended that such equivalents include both currently known
equivalents as well as equivalents developed in the future, i.e.,
any elements developed that perform the same function, regardless
of structure. Thus, for example, it will be appreciated by those
skilled in the art that block diagrams herein can represent
conceptual views of illustrative circuitry embodying the principles
of the technology.
[0028] FIG. 1 illustrates a first example embodiment of an energy
storage system 20 which includes fluid circuit 22 and electrical
unit 24. As explained herein, electrical unit 24 is connected to
operate as a motor in a first phase of operation (e.g., to generate
a torque through a rotatable shaft 26) and to operate as a
generator in a second phase of operation (e.g., to generate an
electrical current in response to rotation of shaft 26). Fluid
circuit 22 comprises fluid container 30; tank 32; and hydraulic
motor/pump unit (HM/PU) 34. In an example implementation of the
first embodiment, fluid circuit 22 and electrical unit 24 are
situated below a pressure reference level P.sub.R, e.g., below sea
level (meaning that fluid circuit 22 and electrical unit 24 are
submerged in water or other liquid) or below ground level.
"Submerged in liquid" or "submerged in water" can include, for
example, submerged in a natural body of water such as the ocean or
very deep lake, or submerged in a flooded mine, for example. Fluid
container 30 is situated so that its content is pressurized at a
first pressure level, e.g., at hydrostatic pressure P.sub.1. For
example, fluid container 30 can comprise a first flexible bladder.
The content of tank 32 is at a second pressure level P.sub.2 (e.g.,
vacuum). Thus, P.sub.2<P.sub.1 since, e.g., rigid walls of tank
32 isolate or insulate the content of tank 32 from any forces
acting outside tank 32 and maintain vacuum within tank 32.
[0029] In fluid circuit 22 hydraulic motor/pump unit (HM/PU) 34 is
connected to communicate a first working fluid between tank 32 and
fluid container 30. For example, and as illustrated in FIG. 1,
hydraulic motor/pump unit (HM/PU) 34 can be connected between tank
32 and fluid container 30 by appropriate fluidic tubes or pipes.
For example, tank 32 is connected to hydraulic motor/pump unit
(HM/PU) 34 through fluid tube 36 and hydraulic motor/pump unit
(HM/PU) 34 is connected to fluid container 30 through fluid tube
38.
[0030] The electrical unit 24 is connected by cable network 40 to
power station 42. In an example embodiment, power station 42 can
comprise power supply system 44 and an optional power station
controller 46. Electrical unit 24 is configured to supply a torque
via rotation of shaft 26 to hydraulic motor/pump unit (HM/PU) 34
during a first phase of operation so that the hydraulic motor/pump
unit (HM/PU) 34 operates as a pump and transmits a working fluid
from tank 32 into fluid container 30. FIG. 1A shows the first phase
of operation, and particularly shows by arrow 50 the power supply
system 44 supplying electrical power to electrical unit 24. As
depicted by arrow 52, the power received by electrical unit 24
during the first phase is used by electrical unit 24 to operate
(via shaft 26) hydraulic motor/pump unit (HM/PU) 34 in a direction
so that the working fluid stored in tank 32 is pumped through tubes
36 and 38 and into fluid container 30 in the manner depicted by
arrow 54. In the implementation in which fluid container 30
comprises a first flexible bladder, the working fluid pumped into
fluid container 30 causes the flexible bladder of fluid container
30 to volumetrically expand against hydrostatic pressure forces
(pressure level P.sub.1). Upon completion of the pumping of the
first phase, fluid circuit 22 including hydraulic motor/pump unit
(HM/PU) 34 is sealed or shut so that the working fluid does not
escape from fluid container 30 back into tank 32. The sealing or
shutting of the fluid circuit and thus the sealing of the working
fluid in this manner may be accomplished by appropriate valves,
e.g., either valves internal to hydraulic motor/pump unit (HM/PU)
34 or valves positioned downstream from hydraulic motor/pump unit
(HM/PU) 34 (e.g., in tube 38 or at a mouth of fluid container 30).
Such valve(s) can be controlled by a suitable controller such as
controller 46. Thus, the controller can comprise electrical unit 24
or be situated at power station 42.
[0031] Electrical unit 24 is configured and controlled to generate
electricity during the second phase of operation. FIG. 1B shows the
second phase of operation, wherein fluid circuit 22 is open so that
pressurized working fluid in fluid container 30 is transmitted from
fluid container 30 through pipes 38 and 36 and through pump 34 in
the manner depicted by arrow to tank 32. In other words, with fluid
circuit 22 open, working fluid in fluid container 30 which is under
hydrostatic pressure P.sub.1 escapes through fluid circuit 22 to
tank 32 where pressure P.sub.2 (vacuum)<pressure P.sub.1. In the
second phase of operation, hydraulic motor/pump unit (HM/PU) 34 is
operated in reverse, e.g., as a motor to turn shaft 26, so that the
working fluid flowing therethrough turns an armature or the like at
the end of shaft 26 so that electrical unit 24 generates
electricity. The electricity generated by electrical unit 24 during
the second phase of operation is applied on cable network 40 to
power station 42 as depicted by arrow 64 in FIG. 1B.
[0032] In an example implementation illustrated in FIG. 2 wherein
the energy storage system is submerged below sea level (SL), the
system optionally comprises a ballast 70 configured to prevent the
system from floating. The power station 42 is situated on land 72,
or even partially on a floating platform. Preferably the power
station 42 is situated above the pressure reference level P.sub.R.
In the example embodiment, cable network 40 conveys electricity
from electrical power source 44 to electrical unit 24 for use of
the electricity to operate electrical unit 24 during the first
phase of operation.
[0033] As shown in the foregoing example, non-limiting embodiments,
one "cell" comprises storage tank 32; an electrical motor/generator
in the form of electrical unit 24 which is coupled to hydraulic
motor/pump unit (HM/PU) 34; fluid container 30 (in the example form
of a flexible (e.g., rubber) bladder); and switching means (e.g.,
valves) for the working fluid.
[0034] The FIG. 1 and FIG. 2 embodiment thus takes advantage of the
pressure existent at great depth in water. The pressure tank 32
filled with working fluid and placed at great depth can be emptied
with hydraulic motor/pump unit (HM/PU) 34 (during the first
operational phase or accumulation period). For the second
operational phrase or generation period, working fluid released
back through hydraulic motor/pump unit (HM/PU) 34 causes electrical
unit 24 to function as an electrical generator to generate
electricity. As an example, at a depth of 2000 meters, one MWH can
be stored in a tank of 14 m diameter.
[0035] This submerged embodiment offers better efficiency than, for
instance, CAES technology, since in CAES air heats up when
compressed (cooling/heating it leads to energy loss). Moreover, the
submerged embodiment of FIG. 1 and FIG. 2 can also be located in
many places around continental coasts, and thus does not suffer
from geographical limitations such as those involved with CAES
technology.
[0036] FIG. 3 shows an example implementation wherein transformer
76 is connected between electrical unit 24 and power station 42.
Preferably transformer 76 is positioned at a relatively short
distance from electrical unit 24, with a primary of transformer 76
being connected to electrical unit 24 and a secondary of
transformer 76 being connected to power station 42. Thus, as
understood from the FIG. 3 implementation which includes
transformer 76, cable network 40 carries a stepped down power level
from electrical unit 24 to power station 42. The transformer 76 is
thus preferably submerged, and has adequate casement to prevent
contact of transformer 76 with liquid. For example, transformer 76
can be provided in a same casement or liquid-tight housing as is
electrical unit 24.
[0037] In one example implementation illustrated in FIG. 4, the
electrical power source (e.g., power supply system) of power
station 42 is a power grid 82. In another example implementation
illustrated in FIG. 5, the electrical power source of power station
42 is a natural or renewable power source 84 such as a wind-driven
or solar power source. Thus, energy storage system 20 can be used
not only for storing electricity from power grid 82, but also from
"wind farms" or solar cells or the like floating directly above,
creating a good match for remote islands, for instance.
[0038] In the FIG. 1 representation, the structure shown below the
reference pressure constitutes a "cell". Plural cells, such as the
one shown in FIG. 1 or other figures hereof, can be connected to
power supply system 44 (whatever its type) on the shore or on land
72.
[0039] It should be appreciated that, in any of the foregoing or
other embodiments described herein, at least portions of the power
station 42 can be situated below the reference pressure level,
e.g., below sea level. For example, as illustrated in FIG. 6,
transformer and switching elements 90 can be located below the
reference level or even comprise electrical unit 24. In fact, in
some implementations the electrical unit 24 can have on one of its
ends a motor/generator and on the other end a high voltage cable.
In such implementation, the electrical unit 24 can hold electrical
switches, a high voltage transformer, radio communication means,
and so on. If submersed, the electrical unit 24 should be protected
from water by a separation tank or other suitable structure (which
may also include the motor/generator).
[0040] In a first phase or accumulation sequence of operation, the
example embodiment of FIG. 6, the electrical energy is transported
from surface through cable 40 and transformer/switching portions
90, reaching electrical unit 24 working as a motor. Through shaft
26 which connects electrical unit 24 and hydraulic motor/pump unit
(HM/PU) 34, the mechanical energy activates the hydraulic
motor/pump 34 that works as a pump. The pumping action performed by
hydraulic motor/pump unit (HM/PU) 34 draws or even empties the
working fluid from tank 32, thereby creating a vacuum in tank 32.
The pumping action of hydraulic motor/pump unit (HM/PU) 34 pushes
the working fluid into fluid container 30, which (particularly when
in the form of a flexible bladder) finds itself under hydrostatic
pressure. In this way the electrical energy is converted into
mechanical energy and finally into potential energy proportional
with the volume of the hydraulic fluid and the pressure difference
between the tank 32 (vacuumed) and the fluid container 30. The
fluid container 30 can be at a significant depth pressure, e.g.,
100+ bar.
[0041] In a second phase of operation (also known as a
recuperation/generation sequence), the potential energy is
converted back into electrical energy. The hydraulic working fluid
from fluid container 30 (under high pressure) activates the
hydraulic motor pump 34 (now acting as a motor) and escapes into
tank 32 (under no pressure). The mechanical energy goes back
through shaft 26 to the electrical unit 24 (now acting as a
generator). The electrical energy produced by electrical unit 24
goes to the switch 24 of power station portions 90, though cable
40, and back to the power grid.
[0042] The efficiency of a method such as that described above with
reference to FIG. 6, for example, is improved in contrast to a
CAES-type system, since the present method has no change in working
fluid volume. The hydraulic working fluid used is incompressible
compared with air used by CAES. This eliminates one of the biggest
hurdles (since compressed air heats up significantly when it
reaches 100-200 Barr).
[0043] FIG. 7 illustrates another example embodiment of an energy
storage system 20' which includes fluid circuit 22' and electrical
unit 24'. Electrical unit 24' is connected through shaft 26' to
operate as a motor in a first phase of operation and to operate as
a generator in a second phase of operation. The energy storage
system 20' further comprises, in addition to comparably numbered
elements understood from previous embodiments, second fluid
container 130; second hydraulic motor/pump unit 134; and, third
hydraulic motor/pump unit 135. The second fluid container 130 is
situated so that content of second fluid container 130 is at a
second bladder pressure level P.sub.2, the second flexible bladder
pressure level being less than the first pressure level P.sub.1.
The second hydraulic motor/pump unit 134 is operatively connected
to the electrical unit 24' and fluidically connected between the
second fluid container 130 and third hydraulic motor/pump unit 135.
The second hydraulic motor/pump unit 134 is connected by pipe 150
to third hydraulic motor/pump unit 135. The third hydraulic
motor/pump unit 135 is fluidically connected between the second
hydraulic motor/pump unit and fluid container 30'. The second
hydraulic motor/pump unit 134 and the third hydraulic motor/pump
unit 135 are configured during the first phase of operation to
operate as pumps to transmit fluid from second fluid container 130
to fluid container 30'. The second hydraulic motor/pump unit 134
and third hydraulic motor/pump unit 135 are configured during the
second phase of operation to operate as motors as fluid from the
fluid container 30' is transmitted to second fluid container 130.
The electrical unit 24' is configured during the first phase of
operation to operate as the motor for the second hydraulic
motor/pump unit 134 and during the second phase of operation to
operate as a generator driven by the second hydraulic motor/pump
unit 134.
[0044] The example embodiment of FIG. 7 thus brings to the surface
(e.g., above reference level P.sub.R) the transformer/switch 90'
and motor-generator-serving electrical unit 24'. This has an
advantage of avoiding the need for pressure chambers or sealants
and the like which are needed around these electrical components
when submerged or immersed.
[0045] In the FIG. 7 embodiment, the working fluid in pipe 50 is
used as means for energy transfer between the surface and the
depth, rather than an electrical cable such as shown in previous
embodiments. At the surface, the electrical energy from the grid
goes to switch 164 to electrical unit 24' coupled with the second
hydraulic motor/pump unit 134 pumping the working fluid from second
fluid container 130 to third hydraulic motor/pump unit 135. The
second fluid container 130 can take the form of a second flexible
bladder. The mechanical energy is transferred through shaft 92 to
the hydraulic motor/pump unit (HM/PU) 34 and, as in the previous
embodiment, empties tank 32 into fluid container 30, thereby
storing potential energy in the first phase or accumulation
phase.
[0046] At a time of peak electrical demand, the whole system of
FIG. 7 works as a generator, operating essentially in reverse as
understood from the foregoing description and embodiments. In
particular, hydraulic motor/pump unit (HM/PU) 34 now reverses its
operation to function as an hydraulic motor; third hydraulic
motor/pump unit 135 operates as a hydraulic pump to pump working
fluid up pipe 50 to second hydraulic motor/pump unit 134; 134
operates as a motor to drive electrical unit 24' to function as an
electrical generator.
[0047] The embodiment of FIG. 7 thus employs high-pressure fluid to
transfer energy between the cells (bottom of the ocean) and the
surface. This enables the electrical power equipment (reversible
pump-motor, generator, etc.) to function "dry" above water.
[0048] FIG. 8 illustrates another example embodiment of an energy
storage system 20'' which includes fluid circuit 22'' and
electrical unit 24''. Electrical unit 24'' is connected to operate
as a motor in a first phase of operation and to operate as a
generator in a second phase of operation. The energy storage system
20'' further comprises, in addition to comparably numbered elements
understood from previous embodiments, second fluid container 130''.
Further, in the FIG. 8 embodiment the first hydraulic motor/pump
unit 34'' is fluidically connected between storage cell or tank
32'' and second fluid container 130'' for communicating a second
working fluid between the tank 32'' and the second fluid container
130''. In the example embodiment of FIG. 8, the first working fluid
comprises compressed gas which is communicated by hose or pipe 50''
between tank 32'' and fluid container 30''. The first fluid
container 30'' is submerged in a liquid 160 and has a fluid
container first internal region 162 in communication with the
submerging liquid 160 and a fluid container second internal region
164 in communication with the compressed gas. The first hydraulic
motor/pump unit 34'' is configured during the first phase of
operation to operate as a pump to transmit the second working fluid
from the second fluid container 130'' to the tank 32'' and thereby
drive the first working fluid from tank 32'' to the first internal
region 160 of fluid container 30''.
[0049] The first hydraulic motor/pump unit 34'' is configured
during the second phase of operation to operate as a motor as the
second working fluid is driven by the first working fluid from the
tank 32'' to the second fluid container 130''. In this regard,
escape of the first working fluid in the form of compressed gas
from fluid container first internal region 162, as controlled by
valves or the like in pipe 50'' (or otherwise situated in fluid
circuit 22'') pushes the second working fluid from tank 32''
through hydraulic motor/pump unit (HM/PU) 34'' (acting as a motor)
into second fluid container 130''. The electrical unit 24'' is
configured during the first phase of operation to operate as the
motor for the first hydraulic motor/pump unit 34'' and during the
second phase of operation to operate as a generator driven by the
first hydraulic motor/pump unit 34''.
[0050] For energy transport the FIG. 8 embodiment thus does not use
an electrical cable or hydraulic fluid, but compressed fluid as the
working fluid. The compressed fluid (e.g., compressed air) as the
first working fluid is situated at the top of pressure tank 32''
and thus presses down on the second working fluid (e.g., hydraulic
fluid) in the same tank. In an example implementation, the
compressed air of the first working fluid can have a pressure
substantially equal to the depth pressure (which is constant) of
the previous embodiments. This advantageously avoids compressing
air from the atmospheric pressure, thereby overcoming a deficiency
of other techniques such as CAES, for example.
[0051] In the first or accumulation phase of the FIG. 8 embodiment,
electrical energy from the grid goes through the transformer/switch
90'' to electrical unit 24'' operating as a motor, coupled with
hydraulic motor/pump unit (HM/PU) 34'' operating as a pump.
Pressure tank 32 is thus filled with the second working fluid,
which pushes the first working fluid (e.g., compressed air)
downwards through tube 50'' into the opened chamber (e.g., fluid
container first internal region 162) of fluid container 30''.
[0052] In the second or recuperation-generating phase of the FIG. 8
embodiment, the second working fluid (e.g., hydraulic fluid) in
tank 32'' is simply turbined by hydraulic motor/pump unit (HM/PU)
34'' acting as the hydraulic motor and through electrical unit 24''
and transformer/switch 90'' back to the grid.
[0053] The FIG. 8 embodiment comprises a long pressure pipe 50''
between surface and depth, in an example implementation of
considerable diameter (e.g., 6-12''), and a surface pressure tank
(e.g., tank 32'') with relatively thicker walls.
[0054] Systems as described herein can also be use deep in
inundated mines. On the ocean, the "surface" should be a marine
platform. Some embodiments have the advantage of installing the
electrical generator and transformers (static converters if using
direct current) above water. On the other hand, extra pressure
tanks add to investment and friction on the downward air tube may
decrease the recuperation factor.
[0055] Any suitable fluid as be used as the working fluid for
communication between tank(s) and the flexible bladder(s). Examples
of the working fluid include but are not limited to hydraulic fluid
or hydraulic oil, glycol, or water with any form of lubricant
inside.
[0056] One or more of the above-described embodiments have numerous
advantages, such as (but not limited to): Being scalable; low
prototype and production price; ability to be situated in multiple
locations; consistency with actual energy policy trends;
accessibility by submarines able to work at such depth; better
storing efficiency than CAES. This storage device is remarkably
inexpensive compared with investments for CAES or gravitational
hydropower storage.
[0057] The foregoing embodiments thus provide electricity
re-distribution techniques suited for meeting increasing peak
demands.
[0058] Although the description above contains many specificities,
these should not be construed as limiting the scope of the
invention but as merely providing illustrations of some of the
presently preferred embodiments of this invention. Thus the scope
of this invention should be determined by the appended claims and
their legal equivalents. Therefore, it will be appreciated that the
scope of the present invention fully encompasses other embodiments
which may become obvious to those skilled in the art, and that the
scope of the present invention is accordingly to be limited by
nothing other than the appended claims, in which reference to an
element in the singular is not intended to mean "one and only one"
unless explicitly so stated, but rather "one or more." All
structural, chemical, and functional equivalents to the elements of
the above-described preferred embodiment that are known to those of
ordinary skill in the art are expressly incorporated herein by
reference and are intended to be encompassed by the present claims.
Moreover, it is not necessary for a device or method to address
each and every problem sought to be solved by the present
invention, for it to be encompassed by the present claims.
Furthermore, no element, component, or method step in the present
disclosure is intended to be dedicated to the public regardless of
whether the element, component, or method step is explicitly
recited in the claims. No claim element herein is to be construed
under the provisions of 35 U.S.C. 112, sixth paragraph, unless the
element is expressly recited using the phrase "means for."
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