U.S. patent application number 11/804704 was filed with the patent office on 2008-02-28 for wind turbine system.
This patent application is currently assigned to General Compression, Inc.. Invention is credited to Eric Ingersoll, David Ritvo Marcus.
Application Number | 20080050234 11/804704 |
Document ID | / |
Family ID | 39113638 |
Filed Date | 2008-02-28 |
United States Patent
Application |
20080050234 |
Kind Code |
A1 |
Ingersoll; Eric ; et
al. |
February 28, 2008 |
Wind turbine system
Abstract
A wind turbine system for producing compressed air from wind
energy. The wind turbine harvests energy from wind to produce
mechanical energy. A compressor receives mechanical energy from the
wind turbine to compress air to an elevated pressure. Thermal
energy may be removed from the air, and the air is stored in a
storage devices, such that the air may be released from the storage
device on demand.
Inventors: |
Ingersoll; Eric; (Cambridge,
MA) ; Marcus; David Ritvo; (West Newton, MA) |
Correspondence
Address: |
WOLF GREENFIELD & SACKS, P.C.
600 ATLANTIC AVENUE
BOSTON
MA
02210-2206
US
|
Assignee: |
General Compression, Inc.
Attleboro
MA
|
Family ID: |
39113638 |
Appl. No.: |
11/804704 |
Filed: |
May 19, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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60932956 |
May 19, 2006 |
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60932958 |
May 19, 2006 |
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60932960 |
May 19, 2006 |
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60932951 |
May 19, 2006 |
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60932952 |
May 19, 2006 |
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60932955 |
May 19, 2006 |
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60932959 |
May 19, 2006 |
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60932954 |
May 19, 2006 |
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60932957 |
May 19, 2006 |
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Current U.S.
Class: |
416/132B ;
290/55; 60/327; 60/670 |
Current CPC
Class: |
F03D 9/25 20160501; Y02E
60/16 20130101; Y02E 10/72 20130101; F03D 80/60 20160501; F03D
9/007 20130101; F03D 9/17 20160501; F03D 9/28 20160501; F03D 15/10
20160501; Y02E 70/30 20130101 |
Class at
Publication: |
416/132.B ;
290/55; 60/327; 60/670 |
International
Class: |
B63H 1/06 20060101
B63H001/06 |
Claims
1. A system for producing compressed air from wind energy, the
system comprising: a wind turbine that harvests energy from wind to
produce mechanical energy; a compressor that receives mechanical
energy from the wind turbine to compress air to an elevated
pressure; a storage device that receives the air from the
compressor such that the air can be released from the storage
device on demand; and an expander for expanding air received from
the storage device to generate electric energy; wherein thermal
energy is removed from the air prior to being received by the
storage device, further wherein thermal energy is added to the
compressed air prior to being expanded to generate electric
energy.
2. The system according to claim 1, wherein the thermal energy
added to the compressed air is provided by a renewable energy
source.
3. The system according to claim 2, wherein the renewable energy
source comprises one or more of solar energy, biomass energy, and
geothermal energy.
4. The system according to claim 1, wherein the thermal energy is
added via a fluid medium into the compressed air.
5. The system according to claim 4, wherein the fluid medium is a
heated vapor.
6. The system according to claim 5, wherein the heated vapor is
steam.
7. The system according to claim 4, wherein the fluid medium is a
combustible gas that provides thermal energy to the compressed air
as the fluid medium is combusted.
8. The system according to claim 1, wherein the thermal energy is
added via a working fluid that is heated remotely from the
compressed air.
9. The system according to claim 8, wherein the working fluid is
heated by a renewable energy source.
10. The system according to claim 1, used to create renewable
energy credits.
11. A system for producing desalinated water with the assistance of
wind energy, the system comprising: a wind turbine that harvests
energy from wind to produce mechanical energy; a compressor that
receives mechanical energy from the wind turbine to compress water
vapor to an elevated pressure and temperature; wherein water vapor
provided to the compressor is drawn from a fluid containing system
of a desalination facility to promote the evaporation of feed
water.
12. The system of claim 11, further comprising: a heat exchanger
that transfers heat of the compressed water vapor so the feed water
to promote evaporation.
13. A system for producing liquefied air products utilizing wind
energy, the system comprising: a wind turbine that harvests energy
from wind to produce mechanical energy; a compressor that receives
mechanical energy from the wind turbine to compress air to an
elevated pressure; and an expander to expand air received from the
compressor to produce liquefied air products from the compressed
air.
14. The system according to claim 13, further comprising: a heat
exchanger positioned to cool compressed air prior to the compressed
air being expanded.
15. The system according to claim 14, wherein the heat exchanger is
configured to receive air expanded by the expander to pre-cool
compressed air.
16. The system according to claim 13, wherein the compressor and
the expander are positioned in a nacelle of the wind turbine.
17. The system according to claim 16, wherein the expander
comprises a expander that derives mechanical work from air that is
expanded therein.
18. The system according to claim 17, wherein the compressor and
the expander are mechanically coupled, and work produced by the
turbine helps drive the compressor.
19. A method of producing compressed air from wind energy, the
method comprising: harvesting wind with a wind turbine to produce
mechanical energy; compressing air to an elevated pressure with a
compressor driven by the mechanical energy; removing thermal energy
from the air; conveying the air to a storage device after thermal
energy is removed from the air; storing the compressed air in the
storage device at a working pressure greater than 10 atmospheres;
conveying the compressed air to an electric energy production
facility; adding thermal energy to the compressed air; and
expanding the compressed air to drive a turbine to produce electric
power.
20. The method according to claim 19, wherein adding thermal energy
comprises adding a thermal energy from a renewable energy
source.
21. The method according to claim 20, wherein the renewable energy
source comprises one or more of solar energy, biomass energy, and
geothermal energy.
22. The method according to claim 19, wherein adding thermal energy
comprises adding thermal energy via a fluid medium into the
compressed air.
23. The method according to claim 22, wherein adding thermal energy
comprises adding thermal energy via a working fluid that is heated
remotely from the compressed air.
24. The method according to claim 19, further comprising: creating
renewable energy credits.
25. A method of producing desalinated water with the assistance of
wind energy, the method comprising: harvesting wind with a wind
turbine to produce mechanical energy; compressing water vapor to an
elevated pressure with a compressor driven by the mechanical
energy; drawing water vapor from a fluid containing system a
desalination facility to promote evaporation of a feed water.
26. A method for producing liquid air products utilizing wind
energy, the method comprising: harvesting wind with a wind turbine
to produce mechanical energy; compressing air to an elevated
pressure with a compressor driven by the mechanical energy;
expanding the compressed air to produce liquefied air products from
the compressed air.
27. The method according to claim 26, further comprising: cooling
the compressed air prior to expanding the compressed air.
28. The method according to claim 26, further comprising: cooling
the air during the process of compressing the air.
29. The method according to claim 28, further comprising: driving
the compressor with energy received by the expander as the
compressed air is expanded.
Description
RELATED APPLICATIONS
[0001] This Application claims the benefit of U.S. application Ser.
No. 11/437419 filed on May 19, 2006, U.S. application Ser. No.
11/437424 filed on May 19, 2006; U.S. application Ser. No.
11/438132 filed on May 19, 2006; U.S. application Ser. No.
11/437261 filed on May 19, 2006; U.S. application Ser. No.
11/437407 filed on May 19, 2006; U.S. application Ser. No.
11/437408 filed on May 19, 2006; U.S. application Ser. No.
11/437836 filed on May 19, 2006; U.S. application Ser. No.
11/437406 filed on May 19, 2006; and U.S. application Ser. No.
11/437423 filed on May 19, 2006, each of which are hereby
incorporated by reference in their entirety.
BACKGROUND
[0002] 1. Field
[0003] This invention relates generally to a system for harvesting
energy from the wind.
[0004] 2. Discussion of Related Art
[0005] From its commercial beginnings more than twenty years ago,
wind energy has achieved rapid growth as a technology for the
generation of electricity. The current generation of wind
technology is considered mature enough by many of the world's
largest economies to allow development of significant electrical
power generation. By the end of 2005 more than 59,000 MW of
windpower capacity had been installed worldwide, with annual
industry growth rates of-greater than 25% experienced during the
last five years.
[0006] Certain constraints to the widespread growth of wind power
have been identified. One constraint relates to the difficulty in
dispatching energy harvested from the wind when needed by
customers. Relatively unpredictable wind speeds affect the
hour-to-hour output of wind plants, and thus the ability of power
aggregators to reliably supply a given amount of energy at any
particular time. Additionally, interconnection costs based upon
peak usage are spread over relatively fewer kwhs from intermittent
technologies such as wind power as compared to other
technologies.
[0007] The applicant appreciates that a need exists for improving
wind turbine systems such that energy, when harvested, can be
provided to appropriate markets at a desired time. The applicant
also appreciates that a need exists to maximize the amount of
energy that may be harvested from the wind at any given time.
SUMMARY OF INVENTION
[0008] According to one aspect of the invention, a system is
disclosed for producing compressed air from wind energy. The system
comprises a wind turbine that harvests energy from wind to produce
mechanical energy A compressor receives mechanical energy from the
wind turbine to compress air to an elevated pressure. A storage
device receives the air from the compressor such that the air can
be released from the storage device on demand. An expander for
expanding air received from the storage device is used to generate
electric energy. Thermal energy is removed from the air prior to
being received by the storage device and thermal energy is added to
the compressed air prior to being expanded to generate electric
energy.
[0009] According to another aspect of the invention, a system is
disclosed for producing desalinating water with the assistance of
wind energy. The system comprises a wind turbine that harvests
energy from wind to produce mechanical energy. A compressor
receives mechanical energy from the wind turbine to compress air to
an elevated pressure. A storage device receives the air from the
compressor such that the air can be released from the storage
device on demand. Air provided to the compressor is drawn from a
fluid containing system of a desalination facility to promote the
evaporation of sea water.
[0010] According to yet another aspect of the invention, a system
for producing liquefied air products utilizing wind energy is
disclosed. The system comprises a wind turbine that harvests energy
from wind to produce mechanical energy. A compressor receives
mechanical energy from the wind turbine to compress air to an
elevated pressure. An expander expands air received from the
compressor to produce liquefied air products from the compressed
air.
[0011] According to still another aspect, a method of producing
compressed air from wind energy is disclosed. The method comprises
harvesting wind with a wind turbine to produce mechanical energy
and compressing air to an elevated pressure with a compressor
driven by the mechanical energy. The compressor also comprises
removing thermal energy from the air and conveying the air to a
storage device after thermal energy is removed from the air.
Compressed air is stored in the storage device at a working
pressure greater than 10 atmospheres. The compressed air is
conveyed to an electric energy production facility. Thermal energy
is added to the compressed air and the compressed air is expanded
to drive a turbine to produce electric power.
[0012] According to another aspect, a method of producing
desalinated water with the assistance of wind energy is disclosed.
The method comprises harvesting wind with a wind turbine to produce
mechanical energy and compressing air to an elevated pressure with
a compressor driven by the mechanical energy. Air is conveyed to a
storage device after thermal energy is removed from the air. The
compressed air is stored in the storage device at a working
pressure greater than 10 atmospheres. Air is drawn from a fluid
containing system of a desalination facility to promote evaporation
of sea water.
[0013] According to another aspect, a method for producing liquid
air products utilizing wind energy is disclosed. The method
comprises harvesting wind with a wind turbine to produce mechanical
energy. Air is compressed to an elevated pressure with a compressor
driven by the mechanical energy. Compressed air is then expanded to
produce liquefied air products from the compressed air.
BRIEF DESCRIPTION OF DRAWINGS
[0014] The accompanying drawings are not intended to be drawn to
scale. In the drawings, each identical or nearly identical
component that is illustrated in various figures is represented by
a like numeral. For purposes of clarity, not every component may be
labeled in every drawing. In the drawings:
[0015] FIG. 1 is a perspective view of a wind turbine system and a
power plant, according to one embodiment.
[0016] FIG. 2 is a perspective, cutaway representation of a wind
turbine, according to one embodiment.
[0017] FIG. 3 is a shows representation of a multi-stage
compression cycle, according to one embodiment.
DETAILED DESCRIPTION
[0018] This invention is not limited in its application to the
details of construction and the arrangement of components set forth
in the following description or illustrated in the drawings. The
invention is capable of other embodiments and of being practiced or
of being carried out in various ways. Also, the phraseology and
terminology used herein is for the purpose of description and
should not be regarded as limiting. The use of "including",
"comprising", or "having", "containing", "involving", and
variations thereof herein, is meant to encompass the items listed
thereafter and equivalents thereof as well as additional items.
[0019] Aspects of the invention relate to a system for producing
compressed air from wind energy. The system includes one or more
wind turbines that, when driven by the wind, provide mechanical
energy to a compressor. The compressor, in turn, compresses a
working fluid, such as air, to an elevated pressure. The compressed
working fluids may then be released to accomplish a desired task,
such as the production of electricity, the liquification of air,
and other processes that require the input of energy.
[0020] According to one aspect of the invention, energy from the
wind is stored as compressed air. A given system may have a finite
amount of storage for compressed air. In this regard, it may be
advantageous to compress the air in a manner that maximizes the
amount of air that can be stored. To help accomplish this, heat may
be removed from the compressed air prior to being conveyed to the
storage device, which can help maximize the amount of compressed
air that can be stored by a given storage device. Moreover, energy
may be less expensive to store in a compressed working fluid that
is closer to the ambient temperature than one that is at a higher
temperature.
[0021] According to one aspect, air liquefaction may also be used
as a mechanism for storing energy for later use. It is to be
appreciated that liquefied air occupies a much smaller volume than
air at a comparable pressure. Air stored as liquid may later be
heated and expanded to drive a turbine, or for any of the other
uses discussed herein. Liquid air may be produced with an expander
that is closely coupled to the compressor. The expander may be
positioned within the nacelle of a wind turbine, the tower of a
wind turbine, or on the ground at a wind form, according to some
embodiments. A common expander may receive compressed air from
multiple wind turbines or each wind turbine may be associated with
a single expander. It is to be appreciated that many of the methods
and devices discussed herein that operate in association with
energy stored as compressed air may also operate with energy stored
as liquid air.
[0022] According to some embodiments, compressors may compress
fluids other than air--such as various types of vapors, like CO2,
refrigerants, water vapor, and the like. These vapors may act as
working fluids in closed loop systems, such as closed loop systems
used for refrigeration, drying, and distillation, to name a few. It
is to be appreciated that many of the methods and devices discussed
herein that operate in association with compressed air, may also
operate with various types of vapors.
[0023] Turn now to the figures, and initially FIG. 1, which shows a
schematic representation of a system that may be used to produce
compressed air for subsequent release on demand. As illustrated,
the system includes a plurality of wind turbines 16 that may
harvest energy from the wind. One or more wind turbines drive
compressors that draw air from the ambient environment and compress
the air to an elevated pressure. Heat that results from compression
may be removed from the air prior to, during, or after the
compression process. A multi-stage compression scheme may be used
to facilitate the removal of heat from the air and/or to allow the
system to compress the air to higher pressures. Once compressed,
the air is conveyed to a storage device 10, which as illustrated,
includes a pipeline. The compressed air may be conveyed by the
pipeline to a turbine at a power generation plant 12, where heat
may be added to the air and the air may be expanded to drive a
turbine that produces electricity.
[0024] Embodiments of the invention facilitate storing energy
received from the wind, such as in compressed air, so that the
energy may be released later when needed or desired. In this
regard, the system facilitates the production of "on demand" or
"dispatchable" wind energy. This may allow wind energy to be
harvested and stored during times when the demand, and thus price
for energy, is low so that such energy may be released at a later
time when the demand is higher. Additionally, facilities that can
be relied upon to provide energy when needed may qualify as firm
capacity. In this regard, these facilities may be capable of
replacing other non-renewable power generation facilities that
might otherwise be required to meet the peak demands of a
particular grid.
[0025] FIG. 2 shows a schematic representation of one embodiment of
a wind turbine 16. The turbine includes multiple blades 18 mounted
to a shaft 17. The blades are configured to receive energy from the
wind, and in turn, to rotate the shaft. The shaft provides energy
to compressors 22 located within the nacelle 21 of the turbine.
[0026] The turbine of FIG. 2 is a "direct drive" device, as the
term is used herein--that is, the energy from the wind is not
converted to electrical energy prior to being conveyed to the air
compressor(s) of the system. It is to be appreciated that direct
drive turbines may include various types of belts, chains, friction
drives, gearings, shafts, clutches, and other mechanical,
pneumatic, and/or hydraulic devices, which may be used to convey
energy to the compressor. According to one embodiment, the rotor of
the turbine may drive a hydraulic clutch that is selectively
engaged to drive the compressor(s). Similarly, direct drive
turbines may also include electronic devices for measuring or
controlling the conveyance of wind energy to the compressor with
the turbine still being considered a direct drive device.
[0027] The compressor(s) that receive energy from a given turbine
may be located in the nacelle of the turbine itself. Such
configurations may help improve the reliability of the wind turbine
by reducing the length and/or complexity of any linkage between the
rotor and the compressor(s). It is to be appreciated, however, that
some embodiments may not incorporate all compressors into the
nacelle, as some systems may use secondary compressors that are
located in the tower, the ground, or underground. Other embodiments
may incorporated all or a portion of the compressors directly in
the tower structure that supports the nacelle, or elsewhere. Still,
some embodiments may not have any compressors located in nacelles
of the wind turbines, as aspects of the invention are not limited
in this respect.
[0028] Various systems may be used to store compressed air. As
shown in FIG. 1, the system may comprise a pipeline that conveys
the compressed air to a desired destination. These pipelines may be
constructed according to guidelines similar to those used in the
construction of natural gas pipelines. Larger pipelines may cost
more to install, but may be capable of storing greater quantities
of compressed air, such that the additional cost may be
justifiable. Larger pipelines may also be capable of conveying
compressed air at lower flow rates with lower frictional losses.
Aspects of the invention, however, are not limited to any
particular type of storage device, such as gas pipelines, as other
devices may also be used to store compressed air.
[0029] Natural or man-made vessels may also be used as storage
devices for compressed air. According to some embodiments,
geographic features, such as salt-domes or exhausted natural gas
cavities may be used to store compressed air. Similarly, man-made
devices, such as pressure vessels, bladders, and underground or
underwater facilities may be used as the sole storage device for a
particular system, or may augment the amount of storage provided by
the pipelines of a particular system.
[0030] Embodiments of the system may store compressed air at
various different operating Pressures. Generally speaking, systems
that can store higher pressures may be more costly to produce, but
can allow greater amounts of energy to be stored in a given volume
of space. According to some embodiments, such as those that utilize
pipelines constructed along guidelines normally used for natural
gas systems, compressed air is stored at pressures up to 100
atmospheres. According to other embodiments, maximum storage
pressures may be lower than 100 atmospheres, although maximum
system pressures are generally greater than 10 atmospheres--a
pressure that is higher than that normally associated with "shop
air" systems. Still, other embodiments may store compressed air at
pressures much greater than 100 atmospheres, as aspects of the
invention are not limited in this respect. By way of example,
systems may be capable of achieving maximum storage pressures of
240 atmospheres are greater. Recently developed composite
reinforced pipes may facilitate achieving these pressures.
[0031] Systems may operated with different ranges of operating
pressures. According to some systems, the operating pressure may
vary widely between maximum pressures as high as 240 atmospheres,
and lower pressure near ambient. However, according to some
embodiments, smaller pressure ranges may prove beneficial, such as
by minimizing stress on storage facilities and minimize the
temperature swings in storage facilities during charging and
discharging. Accordingly some operating pressures are targeted to
vary not more than 100 atmospheres, 80 atmospheres, 50 atmospheres,
or even less, as aspects of the invention are not limited in this
respect.
[0032] The compression of a working fluid, such as air, typically
results in a temperature increase. In fact, compressing air from
atmospheric pressure to 100 atmospheres, as discussed above, may
cause an about 550 degree Celsius or greater increase in air
temperature, if the compression occurs adiabatically. Such high
temperatures may pose design challenges for the compressor and
other portions of the system that must accommodate such
temperatures.
[0033] Heat (i.e., thermal energy) may be removed from air prior
to, during, or after compression. Removing heat in this manner may
reduce the maximum temperature that a system may be designed to
accommodate. Additionally, increasing density at a given pressure
and removing heat from compressed air (or any other working fluid)
may increase the mass of air that can be stored in a given volume
of space, as it is to be appreciated that a given mass of air
occupies less space when at a lower temperature. In this regard,
providing relatively cooler air to a storage device may increase
the total mass of air that may be stored by the device.
[0034] Thermal energy that is removed from the air prior to storage
is energy that may prove more costly to store or transport than the
energy associated with the additional mass of air that may be
provided to storage when the compressed air is at a lower
temperature. Storing greater quantities of relatively cooler air
may allow systems to be configured without as much, or no
insulation surrounding the storage device. Additionally, thermal
energy may be added back to the compressed air prior to, during, or
shortly after expansion of the compressed air at a relatively low
cost, particularly when compared to the costs of retaining the
thermal energy that results directly from compression. Although
embodiments may include removing thermal energy from compressed air
at compression, it is to be appreciated that aspects of the
invention are not limited in this respect.
[0035] Aspects of the invention may also facilitate separation of
the energy associated with the compression of air, the energy
associated with the heating of air that occurs upon compression.
The energy associated with the compressed air may be utilized upon
expansion of the compressed air to perform useful work, and may be
stored in a pipeline or vessel until such work needs to be
performed. The thermal energy may be used for any type of process
that requires heat, and may be stored for later use in a medium,
such as a cooling fluid, until such heat is required.
[0036] Thermal energy may be removed from air prior to compression.
According to some embodiments, an evaporative cooler is used to
accomplish this effect. Air may be passed through a wet or damp
medium, such as a fibrous medium that promotes the wicking of
water. Water may evaporate from the medium and into air prior to
the air entering the compressor(s). This evaporation may draw
thermal energy away from the air in quantities associated with the
latent heat of vaporization for water, and the amount of water that
evaporates. Some sensible heat exchange of thermal energy may also
occur from the air to the water, which may further reduce the air
temperature. It is to be appreciated that sensible heat exchange
refers to thermal energy that results in a change of temperature.
It is to be appreciated that cooling fluids other than water may
also be used in evaporative coolers, as aspects of the invention
are not limited in this respect.
[0037] Other types of heat exchangers may be used to cool air prior
to compression. According to some embodiments, air may be passed
through a bank of plates that are cooled by a working fluid. A
plurality of cooling fins may extend into the airflow path to
remove heat from the air. The working fluid provided to the heat
exchanger may be evaporated during the heat exchange process, or
may remain in a constant liquid or gaseous state, as aspects of the
invention are not limited in this respect. It is to be appreciated
that the above listed types of heat exchangers is merely exemplary,
as other types of heat exchangers may also be used.
[0038] As discussed above, thermal energy may be removed from air
at any point during the compression process. According to some
embodiments, a cooling fluid is introduced directly into the air
that is compressed. The cooling fluid may remove thermal energy
from the air due to sensible heat exchange, although some
evaporative cooling may also occur. This cooling fluid may be
introduced to the air at any point prior the compressed air being
delivered to storage. The cooling fluid may follow the air into the
compression chamber of the compressor(s), and any other portions of
the compression process. In this respect, the cooling fluid may be
subjected to the same pressures as the air that progresses through
the compression process. As discussed herein, the cooling fluid is
typically removed from the compressed air prior to the air being
delivered to the storage medium.
[0039] The temperature of the cooling fluid will not typically
increase due to the increase in pressure that is experienced as the
air and cooling fluid are compressed. This is due to the generally
incompressible nature of cooling fluids, such as water. Instead,
the cooling fluid remains at a temperature similar to that of the
fluid prior to compression. As the compressed air is heated due to
compression, the difference in temperature between the air and
cooling fluid increases, thus causing heat in the air to move to
the cooling fluid in efforts to reach equilibrium. The cooling
fluid is then heated, primarily due to sensible heat exchange from
the hotter, compressed air, although some evaporative cooling may
also take place.
[0040] The system may include features to increase the contact area
between the cooling fluid and the air that is being compressed.
This increased contact area may promote heat transfer between the
cooling fluid and the air. According to some embodiments, the
cooling fluid may be sprayed into the air, such that the cooling
fluid, at least initially, is introduced to the air as water
droplets. Increased contact area may be achieved through other
mechanisms as well, such as with turbulators or other features
within the system that may cause the cooling fluid to be agitated
while passing thereby.
[0041] Cooling fluid may be introduced at directly into the
compression system at different times. By way of example, cooling
fluid introduced during a pre-cooling phase, primarily for
evaporative cooling, may then serve to sensibly cool the air as the
air is compressed. Cooling fluid may also be introduced to the air
just prior to the air being compressed, during compression, and/or
immediately after compression, as aspects of the invention are not
limited in this respect.
[0042] The process of compressing air may result in a net
production of water. As may be appreciated, the relative humidity
of air increases as the air is compressed. Once a relative humidity
of 100% is reached, further compression will result in water
falling out of the air. By way of example, a 1.8 Megawatt wind
turbine compressing 10,000 cubic feet per minute or air at 30%
relative humidity may produce upward of several hundred gallons of
water per day, when discharge pressures of the compressor are at or
about 100 atmospheres. This water and/or cooling fluids may be
removed from the compressed air prior to storage, although it is
not required to be.
[0043] The compressed air may be cooled by mechanisms other than
through cooling fluid injected directly into the air. By way of
example, compressed air may be directed through any type of heat
exchanger, such as a thin-plate heat exchanger, a shell and tube
heat exchanger, a bank of cooling fins, and the like, as aspects of
the invention are not limited in this respect. Such heat exchanger
may be positioned about the compressor itself, so that cooling
occurs during compression. These devices may also be positioned to
cool air prior to compression, as discussed above, or after
compression, as aspects of the invention are not limited in this
respect. It is also to be appreciated that embodiments of the
invention may incorporate any combination of approaches for cooling
compressed air, or no techniques at all.
[0044] According to some embodiments, it is desirable to achieve
isothermal, or near isothermal compression, such that compressed
air exits the compressor at approximately ambient temperature.
Minimal cooling of the compressed air would occur when the air is
resident in the storage device, assuming the storage device is also
at ambient temperature. In this respect, the capacity of a storage
device may be better utilized, particularly during periods when the
prevailing winds are strong, and there is much wind energy to be
harvested and stored.
[0045] Various types and sizes of compressors may be employed to
compress the air. By way of example, scroll type compressors,
reciprocating or oscillating compressor, axial and/or centrifugal
compressor may be used in various embodiments of wind turbines.
Some examples include a toroidal intersecting vane compressor, as
disclosed in US Publication No. US2005/0135934, or an oscillating
vane compressor. The compressor(s) may act continuously, such as
with a scroll type compressor or a centrifugal compressor, or may
act in discrete phases, such as with many reciprocating or
oscillating type compressors. Reciprocating and oscillating
compressors, when employed, may be configured to have multiple
compression chambers that act in parallel, in efforts to maximize
flow rates and to reduce any pulsations in the flow of compressed
air through the system. It is to be appreciated that the above
listing of compressor types is merely exemplary, as aspects of the
invention are not limited to any one type of compressor.
[0046] Embodiments of the compressors may compress air to a
predetermined pressure, at which point the air and any cooling
fluid may be released from the compression chamber. Alternately,
compressors may be configured to release the compressed contents
when a predetermined clearance volume is attained. Additionally,
according to some embodiments, the volume or pressure at which
compressed air is released may be varied during operation.
[0047] According to some embodiments, the compression may be
carried out in multiple stages. Multi-stage compression may
facilitate obtaining higher compressor outlet pressures.
Additionally, multi-stage compressor may provide an opportunity to
cool compressed air between compression stages. Intercooling the
air in this manner may help reduce the maximum temperature that air
experiences for any given discharge pressure of the overall
compression system. According to some embodiment, dividing the
compression among multiple stages and multiple compressors may
facilitate an overall increase in the volumetric efficiency of each
compressor, a reduction in the size of each compressor, a reduction
in the flow rates that each compressor may have to accommodate,
and/or reduction in the pressure differential that each compressor
may accommodate.
[0048] Multi-stage compression may be accomplished according to
various, different strategies. As represented in FIG. 3, one
embodiment includes four separate stages of compression. The first
stage 20 may comprise one or more compressors (two are shown). The
compressors may be four chamber, double acting 22 compressors. In
such compressors, all four chambers are acting to compress air at
any given time. As discussed herein, such a configuration may help
decrease the size and cost may be reduced while the amount of mass
flow may be increased.
[0049] The second stage 24, as illustrated in FIG. 3, includes a
single, double acting, four chamber compressor 22 that receives the
compressed air output from each of the first stage compressors. Due
to the increased pressure of the air and the corresponding
reduction in volumetric flow rate, the second stage may comprise a
single compressor. Similar reductions in volumetric flow rates may
also occur at the third 26, 28 and fourth stages, which may
comprise compressors 22 of a similar design, sized accordingly, or
different types of compressors, as aspects of the invention are not
limited in this respect. Also represented in FIG. 3 are
intercoolers 30 that may be incorporated into each stage of the
compressor.
[0050] Each stage of compression in the embodiment shown in FIG. 3
may increase the pressure of the air by a factor of between 3 and
3.5 in some operating modes, and in some instances by a factor of
3.16. This ratio of compressor outlet pressure to compressor inlet
pressure is defined as a "pressure ratio". The pressure ratio of
3.16 evenly distributes the work across each stage of compression,
and results in a discharge pressure of about 100 atmospheres.
Discharge pressure, as the term is used herein, describes the
pressure at which the overall compression system releases air, such
as to a storage device. Distributing the pressure ratio evenly, in
this manner, may in turn, allow the temperature rise associated
with each stage of compression to be more evenly distributed, which
can help increase the amount of heat that is removed from the
compressed air, according to some embodiments.
[0051] According to other embodiments, the pressure ratios of
various compression stages may differ. By way of example, according
to one embodiment, the pressure ratio declines at each subsequent
compression stage. In this sense, each successive compression stage
increases the pressure of the air by a smaller amount. Such a
scheme may help reduce the pressure differential experienced by the
later stages, since later stages in the compression process will be
dealing with greater absolute pressures, but with smaller pressure
ratios. It is to be appreciated that in other embodiments of
multi-stage compressors, that pressures ratios may differ from
stage to stage according to different schemes, as aspects of the
invention are not limited to those described above.
[0052] The compressors illustrated in FIG. 3 are each configured to
receive air or air and cooling fluid, and to compress the contents
to a defined outlet pressure. Upon reaching the defined pressure,
the air or air and cooling fluid is then output from the
compressor. According to some embodiments, the outlet pressure is
defined by a valve positioned at the compressor outlet. Embodiments
may have compressors with such valves set to a constant release
pressure, or may include valves with release pressures that may be
varied during operation of the compression system. The valve may be
mechanical, such as a spring activated shuttle valve, or may be an
electronically operated valve, as aspects of the invention are not
limited in this respect.
[0053] The compressor may be operated to prevent the waste of
mechanical energy. It is to be appreciated that pressure levels in
a storage device may not be constant through all phases of
operation. Compressing air to pressure much higher than that
present in the storage device may require additional work that is
difficult to recover when the compressed air expands upon entry
into the storage device. Accordingly, some embodiments are
configured to control discharge pressure of the compression system
to be equal to or just slightly greater than the pressure in the
storage device. Controlling the system in this manner may help
improve the overall efficiency of the system. According to some
embodiments, the discharge pressure is controlled to be 1/4 atm
greater than the storage pressure, 1/2 atm greater than the storage
pressure, 2 atm greater than the storage pressure, or 5 atm greater
than the storage pressure. Other controlled differences between
discharge and storage pressures are also possible, as aspects of
the invention are not limited in this respect.
[0054] In one embodiment, discharge pressures may be controlled by
altering the pressure ratio(s) of the compressor. In embodiments
that employ multi-stage compression, the pressure ratio of each
stage may be reduced by a proportional amount until the desired
discharge pressure is obtained. However, it is to be appreciated
that the pressure ratios of multi-stage compressors may be altered
in different manners to achieve a desired discharge pressure, as
aspects of the invention are not limited in this manner.
[0055] Multi-stage compression may facilitate removal of heat
between successive stages of compression. According to some
embodiments, intercoolers may be positioned between compressors of
each stage. In this regard, the amount of heat removed from the
system may be increased. Intercoolers may also help reduce the
maximum temperature that the air attains throughout the entire
compression process. Cooling fluid may also be introduced between
each of the compression stages, either in combination or in place
of the intercoolers, as aspects of the invention are not limited to
any one type of cooling.
[0056] Embodiments of the wind turbine may include features for
cooling the compressors themselves. According to some embodiments,
the compressors may include a coolant jacket through which cooling
fluid is run to remove heat from the compressor. Cooling fins may
be positioned about the external surface of the compressor to aid
in the removal of heat. Still, other methods and devices may be
used to cool the compressor itself, or the compressor may lack such
features altogether, as aspects of the invention are not limited in
this respect.
[0057] Embodiments may include features to protect the compressor
and/or other components from cold weather conditions. By way of
example, embodiments that include coolant jackets may include
heaters to prevent compressor damage that might otherwise occur if
cooling fluids were to freeze in the coolant jacket. Additionally,
or in place of anti-freeze, the cooling system may be used to
circulate warming fluids to prevent freezing damage. It is to be
appreciated that protection for freezing may be implemented in cold
weather conditions when the turbine is not operating, as normal
heat rejection during operation may be sufficient to prevent
freezing and any associated damage.
[0058] Embodiments of the invention may use different approaches to
removing heat from cooling fluid that is used to cool the
compressed air and/or the compressor itself. According to one
embodiment, the cooling fluid is circulated from the nacelle, down
the tower, and into the earth. The earth may act as a heat sink,
removing enough heat from the cooling fluid to bring the cooling
fluid back to or near the ground temperature. The cooling fluid may
be stored in a relatively large underground tank to increase the
average time that the cooling fluid is resident underground before
returning to the nacelle. The surface area of the tank may also be
maximized to promote heat transfer between the earth and the
cooling fluid, such as through the use of ground loops.
[0059] According to one embodiment, water retrieved from air that
is being compressed may help remove heat from the cooling fluid.
The process of compressing air may result in a net production of
water as at least a portion of the water vapor present in the air
received by the turbine is removed during compression, as discussed
above. This water may typically be cooler than the maximum
temperature obtained by the air during compression, and thus may
serve to cool the air and/or the cooling fluid itself. It is to be
appreciated that embodiments of the invention may include features
to remove heat from a cooling fluid other than those described
above, such as traditional air to water radiators, evaporative
cooling towers or ponds, nearby bodies of water, and the like, as
aspects of the invention are not limited in this respect.
[0060] According to some approaches, a primary cooling fluid may
receives thermal energy from the compressed air or compressor and
may, in turn, reject this heat to a secondary cooling fluid. Here,
the first cooling fluid may be optimized for temperatures and
conditions at the compressor or in the nacelle of a turbine, while
the secondary coolant is optimized for conditions elsewhere, such
as at the ground where the secondary cooling fluid resides. A heat
exchanger may be used to transfer heat between the primary and
secondary cooling fluids. In other embodiments, only a single
cooling fluid or no cooling fluids may be used, as aspects of the
invention are not limited in this respect.
[0061] Various types of coolants may be used to cool the compressed
air and the compressor itself. According to some embodiments, it
may be desirable to use an environmentally friendly coolant, such
as ethanol. In this regard, coolant that may escape to the
environment may be less likely to cause environmental harm. Ethanol
may also prevent freezing of the coolant, which may be advantageous
for wind turbines situated in colder environments. Ethanol and
other environmentally safe coolants may prove particularly useful
for direct introduction into the compressed air for cooling, as
such fluids may prove to be more likely to escape into the
environment. Closed loop cooling systems, such as those used in
heat exchangers for performing pre-cooling, intercooling, or for
feeding a coolant jacket to cool the compressors themselves may be
chosen such that the coolant is evaporated when receiving heat,
returning to a liquid state for heat rejection. According to other
embodiments, coolants may receive heat, and later reject heat
without changing phases, as aspects of the invention are not
limited in this respect, or to any one type of cooling fluid.
[0062] Compressed air, provided to the storage device, may be
utilized in various different types of applications. According to
some embodiments, the compressed air may be used to drive turbines
that, in turn, provide electric power when needed.
[0063] According to some embodiments, the compressed air may be
expanded from a storage device at operating pressure and fed
directly to a turbine or any other type of expander, where the
expanding air may produce electrical power. Large combustion
turbines typically receive air that has been compressed to between
about 30 and about 40 atmospheres, although other pressures are
possible. The work associated with compressing air to such
pressures often represents between roughly one half to three
quarters of the gross power that the turbine may produce. In this
respect, providing compressed air from a storage device in such a
manner as to reduce or substantially eliminate the compressor work
may double or triple the net output of the turbine, according to
some embodiments.
[0064] Compressed air may be provided to power generation turbines
in different manners. According to some embodiments, air is
expanded from operating storage pressure and temperature and is fed
directly to a turbine. As discussed herein, operating storage
pressures may typically range between 10 atmospheres and 100
atmospheres, although higher and lower pressures are possible. The
stored air will typically also be at roughly ambient temperature.
It is to be appreciated that the stored air, through the process of
expansion, may reach cryogenic temperatures upon discharge from the
expander, particularly for air that is stored at the higher
pressures, such as those up to and greater than 100 atmospheres,
200 atmospheres, or even 250 atmospheres.
[0065] Heat may be added to the compressed air prior to feeding the
air to a turbine. The added heat may increase the energy that may
be derived from the turbine to create electricity. Turbines in
existing power plants may be constructed to operate with air at
particular working temperatures, and in this respect, additional
efficiencies may be realized by matching the temperature of the air
provided to a turbine to that which is normally provided. According
to some embodiments, the compressed air is heated to between about
1100 and 1500 Celsius and expanded to between about 30 and about 40
atmospheres prior to being fed to the turbine, although other
temperature and pressure levels are possible, as the invention is
not limited in this respect. By way example, the temperatures that
turbines may accommodate are being increased through ongoing
research, and it is contemplated that the temperatures provided by
aspects of the invention may be as high as those that turbines can
accommodate.
[0066] Adding heat to compressed air that is provided to a turbine
may result in exhaust heat from the turbine that can be recuperated
to perform useful work. By way of example, in some embodiments, the
exhaust from a turbine may be used to preheat compressed air that
is being provided to the turbine. The exhaust gases may be used to
directly heat the compressed air, either before any expansion
occurs, or during the expansion process but prior to the air being
fed to the turbine. In other embodiments, heat from turbine exhaust
gases may be used in a remunerator, or to heat the working fluid of
a heat exchanger, that in turn, preheats compressed air prior to
the air being fed to the turbine. It is to be appreciated, however,
that aspects of the invention do not require the recuperation of
heat from the turbine, as the invention is not limited in this
respect.
[0067] Compressed air may be heated by various different means
before being fed to a turbine. According to some embodiments, heat
is added by combusting fuel directly in the compressed air. This is
typically accomplished with liquid or gaseous fuels, such as
natural gas, among other choices. According to other embodiments,
steam may be injected directly into the compressed air. Other
methods may also be available for directly heating the air prior to
the air being introduced to the turbine. According to some
embodiments, the air is heated directly by a solar concentrator,
which may prove particularly advantageous as such devices are
capable of attaining very high air temperatures. Still, other
methods of directly heating the compressed air are possible, as
aspects of the invention are not limited to those described
above.
[0068] Embodiments may also use methods of indirectly heating the
compressed air, such as with a heat exchanger that receives thermal
energy from a working fluid. The working fluid, in turn, may be
heated by multiple different types of sources, including biomass,
coal, waste heat from other production or power plant facilities,
solar heat from a collector, such as a trough style collector, and
the like. According to some embodiments, the source of heat that is
used to provide thermal energy to the compressed air may be a
renewable energy source. In this respect, an energy provider may
obtain additional government benefits for energy that is
produced.
[0069] Air may be fed to turbines at various, different pressures.
As discussed above, according to some embodiments, the air is fed
to the turbine at the operating pressure of the storage device.
Here, the pressure of air fed to the turbine may vary according to
the operating pressure of the system. In other embodiments, the
pressure may be controlled to a single pressure, or range of
pressures, such as between 30 and 40 atmospheres, before being
introduced to the turbine. It is noted that expanding the air from
100 atmospheres to 40 atmospheres typically only incurs an
approximately 45 degree Celsius decrease in temperature, such that
the thermal energy required to bring such expanded air to a desired
temperature is not significantly increased.
[0070] Turbines that receive compressed air from a storage device
may be configured in different manners. According to some
embodiments, the turbines may be of similar construction to those
that are found in existing, natural gas power plants. Such turbines
are typically coupled to a compressor that may be used to compress
air provided to the turbine when compressed air is not provided by
the storage device. When compressed air is provided by the storage
device, the compressor may be mechanically disconnected from the
turbine, such that energy is not expended to rotate the compressor
and compress additional air. Twin shaft compressor/turbine
arrangements are also suitable for such embodiments. According to
some embodiments, the compressor may be isolated from the
atmosphere, such that rotation of the compressor does not compress
air and minimizes any energy consumption by the pressure stages of
the compressor/turbine.
[0071] According to other embodiments, compressed air may be
expanded and fed through a steam turbine directly from storage, as
such turbines are typically configured to operate with greater
efficiencies over a wider range of operating pressures.
[0072] According to some embodiments, the air compressed by the
wind turbine may be expanded to produce liquid air. The compressed
air may be released from a storage device may, or may be released
directly from compressor discharge. Expansion of compressed air is
accompanied by a cooling of the air. In some embodiments, the air
may be cooled such that at least a portion of the expanded air
changes phase and become liquid.
[0073] Techniques may be used to increase the percentage of
compressed air that is liquefied upon expansion. As may be
appreciated, increasing the reduction in pressure that occurs upon
expansion may increase the amount of thermal energy that is
released as the air expands to atmospheric pressure, such that
greater cooling and more liquefied air is obtained. Additionally,
according to some embodiments, expanded and cooled air that is not
converted to the liquid phase may be used to pre-cool compressed
air. In this regard, energy may be removed from the compressed air
such that upon expansion, a greater percentage of the air is
converted to liquid. Other methods may be used to pre-cool the
compressed air, either alone or in combination with air that has
been expanded, as aspects of the invention are not limited to any
one method or device for pre-cooling compressed air.
[0074] Compressing air to higher pressures may allow liquid air to
be produced and stored at higher temperatures. According to some
embodiments compressed air may be received from a storage device
and compressed further to produce liquid air, either in addition to
or in place of creating liquid air upon expanding the stored
compressed air. Still, other methods may be used to increase the
amount of liquid air that is derived from the compressed air, as
aspects of the invention are not limited to those discussed
above.
[0075] Products, such as industrial grade or even laboratory grade
oxygen and nitrogen, may be produced with liquid air produced by
various embodiments of the system. According to some approaches,
fractional distillation may be used to isolate oxygen, nitrogen, or
any other particular components from the air.
[0076] According to some embodiments, the compressed air may be
used to produce oxygen or nitrogen directly through methods like
pressure swing adsorption. In such embodiments, compressed air from
a storage device is exposed to a substance that adsorbs oxygen, or
some other constituent of air, at higher pressures. After exposure
in the compressed air, the substance is exposed to a lower pressure
environment, where oxygen (or another constituent of air) is
released and collected.
[0077] Isolated air products, like laboratory grade or industrial
grade oxygen, have many existing and growing markets. By way of
example, oxygen may be used in the gasification and combustion of
gasified solid fuels, by oxygen fired coal plants, integrated
gasification combined cycle plants, natural gas plants, combined
cycle plants, and the like.
[0078] Air liquefaction may also be used as a mechanism for storing
energy for later use. It is to be appreciated that liquefied air
occupies a much smaller volume than air at a comparable pressure.
By way of example, liquid air occupies approximately _b 1/80th of
the volume of gaseous air at 100 atmospheres. Air stored as liquid
may later be heated and expanded to drive a turbine, or for any of
the other uses discussed herein.
[0079] According to some embodiments, air liquefaction for energy
storage occurs in place of storing energy as compressed air.
Liquefaction may occur at a wind farm, and in some embodiments,
within the nacelle of a turbine. In one embodiment, the expander
comprises a turbine connected mechanically to the compressor(s),
such that the turbine may help drive the compressor(s) as the
compressed air is expanded. In some embodiments, the turbine and
compressor may be mounted to a common shaft. The reduction in
storage volume for liquefied air may facilitate transportation of
energy harvested by a wind farm through means other than a
pipeline. By way of example, ships, trucks, and rail may be used to
transport liquid air containers from a wind farm or single wind
turbine to various destinations. In the case of a pipeline, the
size, cost, and losses associated with moving the fluid through the
pipeline may be reduce.
[0080] The manner in which compressed air released from a storage
device may utilize heat energy allows for numerous synergies with
other types of processes. By way of example, Aluminum production
facilities typically produce great amounts of waste heat that is
typically output to the environment, often at great costs.
According to some embodiments, this heat may be transferred, either
directly or through a working medium, to compressed air before the
compressed air is expanded through a turbine to produce
electricity. This electricity, in turn, could, be provided to the
Aluminum plant to power internal processes that may require
energy.
[0081] Co-located facilities may benefit from other synergies as
well. By way of example, plants often expend large amounts of
energy to compress air for internal uses, such as powering tools,
materials handling, robots and the like. Plants may receive
compressed air directly from a storage device, such that
electricity does not need to be used to compress air on-site.
Cooling may also be provided directly to production, processing, or
plants by the expansion of compressed air. Such cooling may be used
for any processes internal to a plant that may require cooling,
such as industrial process, including refrigeration, and the
like.
[0082] According to some embodiments, a turbine that utilizes air
provided from a storage device may be co-located with a peak power
production plant to provide synergistic benefits. Peak power
production facilities typically incur additional power production
requirements during the hottest times of day, when consumers are
operating air conditioners at maximum power. At such times, heat is
more readily available, such as in a solar collector, for
pre-heating compressed air before being fed to a turbine for
electric power generation. The correlation between energy demand by
consumers and solar energy availability for pre-heating compressed
air allows for increased synergistic benefits.
[0083] Embodiments of the system may also be constructed to take
advantage of synergies that may exist with facilities that require
sub-atmospheric pressure. By way of example, the compressors of one
or more wind turbines may be used to draw a vacuum to help
evaporate fluids, such as salt water. The may prove particularly
beneficial for desalination plants, where the evaporated water may
later be condensed to provide fresh water.
[0084] Wind turbines, according to aspects of the present
invention, may be positioned as solitary turbines, or may be
grouped together in wind farms. Wind turbines may also be
positioned anywhere, particularly where prevailing winds are
typically strong. By way of example, turbines may be positioned in
wide open plains and or in bodies of water, standing on the bottom
of floating atop supporting structures. Such embodiments may
provide a readily accessible source of cooling in the waters of a
large inland lake or ocean.
[0085] Other types of plants that may find synergies with
embodiments of the present invention may include but are not
limited to, an aluminum production facility, a fertilizer, ammonia,
or urea production facility, a liquid air product production
facility that can be used in manufacturing liquid air, liquid
oxygen, liquid nitrogen, and other liquid air products, a fresh
water from desalination production facility, a ferrosilicon
production facility, an electricity intensive chemical process or
manufacturing facility, a tire recycling plant, coal burning
facility, biomass burning facility, medical facility, cryogenic
cooling process, or any plant that gasifies liquid oxygen,
nitrogen, argon, CO2, an ethanol production facility, a food
processing facility. Examples of food processing facilities include
but are not limited to, dairy or meat processing facilities and the
like.
[0086] Aspects of the invention also relate to obtaining renewable
energy credits with wind generated energy. As may be appreciated,
electricity may be provided to consumers by retailers, often known
as load serving entities. Load serving entities, in turn, purchase
the electricity they provide from wholesale suppliers of
electricity. In deregulated control areas, an independent system
operator may be responsible for the administration of the wholesale
power markets and network reliability.
[0087] Some governments choose to establish and administer
renewable energy portfolio standard (RPS) to promote power
generation fuel diversity. Under the RPS, load serving entities may
be obligated to purchase a defined percentage of their annual
retail sales from qualified wholesale suppliers to comply with the
RPS or provide so called compliance or penalty payments if they are
unable to procure a sufficient amount of qualified supply. The
compliance obligation typically increases annually by a defined
increment set in advance by a governmental entity. The RPS may act
to incent wholesale suppliers to develop new power plants that will
generate electricity in certain government-preferred ways. In
return suppliers may become eligible to receive renewable-energy
credits (REC). According to some embodiments, the preferred ways
may relate to the technology used to create the electricity, such
as by the type of fuel burned to produce the electricity. The
preferred ways may also relate to the nature of the emissions that
result from a particular electricity generating process.
[0088] At least a portion of the electricity is available for sale
to a wholesale or retail customer or on the open market. Renewable
energy credits can be associated with the electricity produced,
associated with electricity produced from the wind energy systems
and the thermal energy systems, like those discussed herein. In one
embodiment, the renewable energy credits are associated with a
value placed on the produced electricity.
[0089] It is envisioned that the power generation system described
herein creates opportunities for novel approaches to: increasing
existing power generation efficiency, improving pollution
abatement, and enabling pollution sequestration; and thereby may
incent governments to craft novel forms of renewable-energy credits
that said power system would qualify to obtain. For example, the
wind energy system can be coupled to a thermal energy system and
the wind energy and thermal energy from the thermal energy system
is collected and stored. The renewable energy credits can be among
the following: sulfur dioxide credits, nitrous oxide (NOX) credits,
mercury reduction credits, cap and trade pollution credits,
renewable obligation certificate (ROCs) credits, renewable energy
credits (RECs), carbon credits, green energy credits, CO2 credits,
financially valuable environmental attributes, power purchase
agreements and the like. The thermal energy system can be selected
from, biomass, geothermal, solar, coal, natural gas, oil,
industrial process heat, nuclear, heat from a chemical or
manufacturing process, a wind compressor intercooler, a body of
water and the like. At least a portion of the wind power can be
used convert at least a portion of the thermal energy to
electricity to increase efficiency of conversion. The thermal
portion of the wind energy can be stored, managed, and enhanced by
a solar thermal collector, thermal inertial mass, thin walled
tubing with anti-freeze distributed inside the tank, fossil fuel,
or biomass, or bio fuel burner, a circulation device for using hot
air, and the like.
[0090] In one embodiment, green credits are provided for the
production of electricity from the wind energy system alone or in
combination with the thermal energy system. The renewable energy
credits attributed to wind power can receive green energy credit.
In another embodiment, those renewable energy credits attributed to
the thermal energy system, with attributes that qualify them as
green energy credits, such as but not limited to thermal inputs
derived from biomass combustion or gasification, also receive green
energy credits. In one embodiment, a green energy credit of the
thermal energy is increased in response to utilizing the wind power
to covert the thermal energy into electricity.
[0091] All or a portion of the renewable energy credits can be sold
to third parties. The sale to third parties can occur through a
variety of mechanisms, including but not limited to, through a
broker, a sales organization, an auction, directly from the wind
energy system owner or manager, from a contracted owner of the
renewable energy credit and the like.
[0092] The delivery of wind energy can be coordinated and
stabilized. An energy delivery schedule can be created from the
wind energy system in response to predictions for wind speed, wind
power availability levels, historical, current and anticipated
power and green energy prices, and historical, current and
anticipated transmission availability. The delivery schedule can be
used to match a customer's anticipated demand. The delivery
schedule can manage updates and corrections to schedules on very
short notice. The delivery schedule can be used to set a reduced
number of constant power output periods during an upcoming period
of time. By way of illustration, during the upcoming period of time
energy, delivery levels can remain substantially constant despite
fluctuations and oscillations in wind speed and wind power
availability levels.
[0093] The upcoming period of time can be any period of time,
including but not limited to the next 24 hour period. In one
embodiment, no more than seven constant power output periods occur
during any given 24 hour period.
[0094] The delivery schedule can take into account the amount of
energy that can be supplied directly from the wind power system as
well as stored energy. In one embodiment, the delivery schedule is
utilized to determine an amount of energy that can be provided from
storage, and an amount of power expected to be used and withdrawn
by a power grid. In another embodiment, the delivery schedule is
utilized to assist in ensuring that wind energy is available at
constant power output levels even when the wind energy availability
levels drop below a demand for power needed by a power grid.
[0095] In another embodiment, at least one demand history is
created for a location to help forecast and predict how much energy
will be used at the location during an upcoming period of time.
Energy availability from the wind energy system can be determined.
The demand history can be used for delivery of wind energy to the
location to manage load, offset spikes, sags, and surges, and meet
the needs of the grid and the customer.
[0096] Embodiments of the wind energy system can be coupled to a
power grid that can be accessed to supply energy into storage by
using electricity to run the generator/expanders backwards as
motor/compressors to pressurize the system, which will then be
expanded on demand to make electricity. An energy usage schedule
can be developed using forecasts and predictions to for the
upcoming time period to determine how energy from storage should be
used to achieve a desired cost savings. A demand charge can be
determined that may be applied based on spikes or surges that can
occur during the upcoming time period, and an energy usage schedule
then developed to reduce and/or offset the spikes or surges in a
manner that achieves cost savings at a location. The location can
be a commercial property end-user of energy and storage of energy
is used to lower overall costs of energy at the commercial property
end-use, and the like.
[0097] In one embodiment, an estimated cost savings for the
upcoming time period is determined, and then that determination is
repeated for an extended period of time, to help determine an
overall cost savings that can be achieved during the extended
period of time.
[0098] Having thus described several aspects of at least one
embodiment of this invention, it is to be appreciated various
alterations, modifications, and improvements will readily occur to
those skilled in the art. Such alterations, modifications, and
improvements are intended to be part of this disclosure, and are
intended to be within the spirit and scope of the invention.
Accordingly, the foregoing description and drawings are by way of
example only.
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