Patent Application
20170074248
The present invention relates to wind turbines for the generation of electricity and other forms of energy and in particular to a wind turbine station and tower with vertically oriented storage tanks or vessels for storing compressed air energy.
While attempts have been made to reduce reliance on foreign oil, many energy experts fear that some of these resources, including oil, gas and coal, may someday run out. Because of these concerns, projects have been initiated in an attempt to harness energy from what are often referred to as natural “alternative” sources—sources that will never become depleted. And due to increased energy demands, and energy costs, energy providers have begun to seriously consider the feasibility and use of energy derived from those sources including the sun and wind.
Most populated areas of the country have adequate availability of electricity, such as those provided by local utility companies and distributed through large power grids. In some remote areas, however, the cost of running overhead or underground cables from the nearest grid to the end user can be prohibitively high, and therefore, electrical power is not always readily available. And to make matters worse, the cost of installing an energy generating facility in such locations is normally incurred by the end user, such as where land is privately owned and public utility companies have no obligation to service those areas. Moreover, even if power lines are provided to these locations, significant power losses can occur due to great distances, wherein the energy that travels through the lines can be significantly diminished by the time it reaches its destination. Thus, people who live high in the mountains or in other remote areas often need to develop and provide their own energy systems, etc.
While solar power is one of the most widely known sources of naturally occurring energy, there is also the potential for harnessing tremendous energy from the wind. Wind farms, for example, have been built in many areas of the world, i.e., windmills are typically built and “aimed” toward the wind, so that when the wind blows, rotational power is created and used to drive generators, which in turn, can generate electricity. This energy is often used to supplement energy produced by utility plants and distributed through grids.
One drawback to using wind as an energy source, however, is that the wind does not always blow, and even if it does, it does not always blow consistently at the same speed, i.e., it is often unpredictable, and therefore, it is not always a reliable form of energy, and the amount of wind derived energy will differ significantly from time to time and from location to location. While some attempts have been made to store energy produced by the wind so it can be used later during peak demand periods, or when the wind is not blowing hard enough, these attempts have not yet produced systems that are sufficiently efficient, nor have they been able to reduce the costs and difficulties associated with using wind as an energy source.
For example, past attempts include using batteries to store electricity as well as large steel tanks or underground caverns to store compressed air energy, but these attempts have not been successful mainly due to their excessive costs. Indeed, when taking into account the cost of constructing wind turbines, etc., and the cost of constructing the storage tanks and other related equipment, including the towers, as well as the potential energy losses attributable to converting energy from one form to another, it has not always been cost effective to develop these types of systems.
Past attempts to store energy in the form of compressed air energy include using large costly steel tanks and underground caverns. And, when taking into account the amount of storage space normally required for a facility like this to store energy, it is often cost prohibitive to build large steel tanks and vessels to hold the compressed air needed to supply the necessary power. And, while the cost of using an existing underground cavern for storing compressed air is relatively low compared to using steel tanks, the downside is that there are only a few areas in existence that have caverns large enough and airtight enough for storing compressed air energy, and even when there is such a site, the facility that uses the cavern will have to be built directly above the cavern, which may or may not be feasible or even possible.
Notwithstanding these problems, because wind is a significant natural resource that will never run out, and is often in abundance in many areas of the world, there is a desire to develop a system that can harness wind energy and produce electrical power, but to do so in a predictable, reliable, consistent and cost-effective manner.
The present invention relates to wind turbine stations and towers and wind farms that use them for generating energy from the wind, wherein each wind turbine station preferably comprises a tower with a substantially vertically oriented high pressure storage vessel or tank for storing compressed air energy generated by a compressor associated therewith. The tower is preferably extended substantially vertically and comprises multiple storage pipes that are positioned side by side on which the wind turbine blades and nacelle are mounted. The tower is preferably high enough to enable the wind turbine blades to access the greater wind speeds that exist at higher elevations, and is preferably high enough to provide a sufficient amount of storage volume inside the storage vessel or tank for storing the compressed air energy generated by the compressor.
The wind turbine preferably comprises blades that are extended from a nacelle and adapted to rotate as the wind blows against the blades. The blades are preferably extended about an axis that is substantially horizontally oriented and connected to an energy converting device which converts the rotational energy of the blades into a usable form, such as electricity, or storable form, such as compressed air, or both.
In one embodiment, each nacelle preferably consists of a compressor for generating compressed air energy, wherein the mechanical energy produced by the wind as the blades rotate can be used to produce compressed air energy which can be stored directly into the pressure vessel or tank. This is advantageous because the energy does not have to be converted into electricity before it is used to drive the compressor.
In another embodiment, a generator for generating electricity can be provided within the nacelle, wherein the rotational movement of the blades can be used to drive an electrical generator, which in turn, produces electricity that can either be transmitted down the tower to drive a compressor located on the ground or drive a compressor located within the nacelle.
In either case, the compressed air energy produced by the compressor is preferably stored in the vessel or tank, such that it can be used later, and/or used to supply electricity directly to the end user or grid without storing it first. In such case, a switch is preferably provided that enables the system to be switched between supplying electricity for immediate use and producing compressed air energy for storage. This last situation can occur when the wind is blowing relatively hard, and there is more energy being produced than there is demand for that energy, or, even when the wind is not blowing very hard, when the demand is sufficiently low enough that extra wind energy is available for putting into storage.
In another embodiment, both the compressor and generator can be located in the nacelle, wherein a switch can be provided that enables the station to be switched between generating electricity for immediate use, on one hand, and compressing air into storage, on the other hand, i.e., similar to a hybrid station. A drive gear system, for example, can be provided that allows the rotational energy from the wind to be spit between the compressor on one hand and the generator on the other hand, wherein the distribution of energy is based on the gear ratios that are provided in connection with the drives. When there is excess energy available beyond that needed for immediate use, the compressor can be turned on and used to produce compressed air energy, which can then be stored in the vessel or tank and made available for later use. On the other hand, when there is a sufficient amount of compressed air energy available in storage, or whenever it is desirable to provide electricity directly, the system can be switched to allow the generator to produce electrical power that can be used immediately by the end user or grid.
In a variation of that embodiment, the energy producing system can be adapted such that it can always be set to generate electricity for immediate use, without regard to how much energy is provided in storage. In such case, a logic circuit or control system is preferably provided that allows the rotational energy from the wind to be converted into electricity to the extent it is needed, and the leftover or surplus energy is converted into compressed air energy and stored in the vessel or tank. In such case, a drive gear system can be provided that allows the rotational energy from the wind to be spit between the compressor on one hand and the generator on the other hand, wherein the amount of distribution of energy to either is based on the gear ratios that are engaged in the drive gears relative to either destination.
Regardless of the embodiment, the compressed air in storage is preferably converted into a usable form such as electricity at the appropriate time so that it can be made available to supplement the energy provided by the grid or other source. This is preferably done by releasing the compressed air in the vessel or tank using a turbo expander and generator set located on the ground that can produce not only electricity as the air is expanded, but also chilled air usable for ancillary purposes, such as refrigeration, air conditioning, desalination and the like.
In whatever situation applies, the compressor preferably helps to remove the moisture from the input air before it is introduced into the vessel for storage using heat exchangers, etc. This helps to reduce the amount of water that can otherwise collect within the vessel, as well as the moisture that can be introduced into the turbo expander when the compressed air is released.
In one aspect, when large diameter pipes are used that make up the storage tanks or vessels, the pipes are preferably vertically oriented so that they occupy a relatively small footprint on the ground—unlike horizontally oriented storage tanks which are often used in applications such as these. And, by orienting the pipes substantially vertically, they can also double as the supporting tower on which the nacelle and wind turbine blades are mounted, such that they can be extended higher into the air where wind velocities are greater. And by using large pipes to support the wind turbine blades, and simultaneously adapting them to store compressed air energy, the cost of building the wind turbine stations overall, including the cost of the vessels and tower and related components, including but not limited to, the blades, compressors, turbo expanders, generators, heat exchangers, etc., can be significantly reduced. In fact, in conventional wind turbine stations, the cost of building the tower can represent about fifty percent of the total cost of the wind turbine station itself, which is in addition to the cost of building the storage tanks, etc.
While the tower of the present invention can be made using a single large diameter pipe, the preferred design incorporates at least two large diameter pipes extending substantially vertically upward from the ground, wherein each is preferably extended parallel to each other, with a predetermined space in between each one, wherein adjacent pipes can be connected together using a steel vertically oriented plate or web extending between them. By using this configuration, and connecting the web between two vertically oriented pipes, the web can be designed to provide additional rigidity to the tower, which can be helpful in resisting any wind generated moment forces that can be applied to the top of the tower. It is also possible to provide access to the top of the tower by placing a ladder and safety cage or elevator, etc., on the web.
In the preferred embodiment, two vertically oriented pipes are extended parallel to each other, upward from the ground, wherein a steel web is extended between them, wherein the pipes can be anywhere from about two to four or more feet in diameter, and the web can be anywhere from two to five feet or more in width extending in between them. And, preferably, in this embodiment, the two pipes are substantially vertically oriented such that the vertical axis of each pipe is extended perpendicularly through (or substantially near) the horizontal axis of the wind turbine blades, with one pipe in front and one pipe in back, such that the configuration of the tower increases its flexural rigidity and ability to resist wind generated moment forces applied against the top of the tower by the wind. That is, by positioning the two pipes vertically, side by side, with their axis perpendicularly intersecting the horizontal axis of the wind turbine blades, and extending a web section between them, the flexural strength and moment resistance of the tower can be increased in that direction, which in turn, helps resist bending and moment stresses exerted by wind forces blowing in that direction against the top of the tower.
In another aspect, at least a portion of each pipe in the tower is preferably extended into the ground, not only so that the ground can provide support for the tower, but also because of the additional thermal conductivity properties provided by the surrounding ground and supporting material such as concrete that can help to enable the temperature of the air inside the vessel to be better controlled and regulated. This is made necessary or is otherwise beneficial because the temperature of the air can be increased as the air is compressed into the vessel by the compressor, and/or the temperature can be decreased as the air is expanded from the vessel and released by the turbo expander. The thickness and size of the pipes can also help better control the temperature of the air inside.
In the preferred embodiment, the wind turbine station preferably has two large pipes oriented upward with a first pipe having a vertical axis extending through or substantially near the front end of the nacelle, and a second pipe having a vertical axis extending through or substantially near the rear end of the nacelle, with both vertical axis extending through or substantially near the horizontal axis of the wind turbine blades, which helps to ensure that the greatest resistance to bending and moment forces coincides with the wind direction, i.e., the same direction as the horizontal axis of the blades. A thick steel web that helps to increase the moment resistance of the tower is also preferably provided, wherein the web extends between the pipes to form what is substantially similar to an I-beam in cross section extended vertically upward, wherein the pipes act as the flanges, and the web extends between them to resist the shear forces that are exerted thereon.
The number and configuration of tanks or vessels, including how many pipes that are used for each tower and how the pipes are to be oriented, etc., is preferably adaptable to maximize the flexural strength and rigidity and moment resistance of the towers, which in turn, helps to resist the bending forces that can be created as the wind blows against the wind turbine blades. This enables the towers to be built higher, which enables them to access higher speed wind conditions at higher elevations, which can increase the efficiency of the wind turbine station—more power can be generated by the same turbine. This can also make it possible for wind turbine stations to be built with greater storage capacities and avoid upwind obstructions, including adjacent wind towers, or ground conditions, such as hills or mountains, which can interfere with the wind blowing against the blades and therefore the generation of power. Additional embodiments with additional vessels or pipes can be provided to not only increase the storage capacity of the towers, but also increase the flexural strength and rigidity and moment resistance of the towers in different directions other than in the direction of the axis of the blades. In this respect, it can be seen that by providing and orienting other pipes so that their vertical axis do not extend through the same horizontal axis as the blades, the tower can be made to resist additional bending and flexural forces in other directions, i.e., more than just the direction that coincides with the horizontal axis of the blades. Indeed, given that the wind will normally blow in many directions, it can be seen that the tower may be built to resist bending and moment forces in more than just one direction, particularly when the tower is made higher, thereby exposing the blades to greater wind speeds at greater heights. When a tower is built higher, the potential exists for not only greater wind speeds to exist at the top of the tower, but also substantially greater bending and moment forces applied to the tower, which translates into higher compression and tensile forces created along the length of the tower. In such case, it will become more important for towers that are built higher to withstand greater moment forces and more extreme conditions, and thus, being able to use more than two pipes, and orienting them along different axis, can help to expand the potential scope of resistance where these types of wind turbine stations can be used. When three or more pipes are used, for example, they can form a non-linear pattern, wherein the tower can resist greater wind forces in more than one direction, to accommodate the possibility that the wind will blow in various directions at different times. For example, three pipes can be provided to form a triangular configuration, which helps to increase flexural strength and rigidity and moment resistance in at least three directions, and thereby, resist wind forces on the tower in multiple directions. When three vertical pipes are oriented in this manner, a first pipe is preferably extended with its vertical axis extending through or substantially near the front end of the nacelle, as well as perpendicularly through or near the horizontal axis of the blades, and the second and third pipes are preferably extended with their vertical axis substantially equidistant from the first pipe, substantially near or across the rearward part of the nacelle, substantially equidistant from the horizontal axis of the blades. And, preferably extended between the adjacent pipes are webs that connect the pipes together, to form the triangular configuration, and which provide greater strength, rigidity and moment resistance to the tower design by withstanding the shear forces that may be applied between the pipes. Access to the top of the tower can also be provided on one or more webs, such as by building a ladder with a safety cage around it, or an elevator, etc., onto the web between the pipes.
Embodiments with four pipes can also be provided which can be accomplished in a variety of ways. For example, the four vertical pipes can be oriented in a substantial T configuration, with the first pipe having a vertical axis extended through or substantially near the front end of the nacelle (as well as near or through the horizontal axis of the blades), and the other three pipes extended substantially rearward toward the back of the nacelle, such as along a line that is substantially perpendicular to the horizontal axis of the blades. In such case, along the back, the middle pipe preferably has a vertical axis extended through or near the horizontal axis of the blades, while the other two pipes are oriented on either side, such as substantially equidistant from the horizontal axis of the blades. In such case, a web is preferably extended between the front pipe and middle pipe, and then, on either side of the middle pipe, between the middle pipe and two side pipes. This not only increases the strength and rigidity and moment resistance provided by the tower, but also allows for a ladder and safety case or an elevator to be extended to the top of the tower.
Another embodiment using four vertical pipes can comprise a substantially square shape, or rectangular or diamond configuration, wherein the first pipe preferably has a vertical axis extended through or substantially near the front of the nacelle (as well as through or substantially near the horizontal axis of the blades). The second and third pipes can then be oriented such that their vertical axis are extended substantially equidistant from the middle of the nacelle, rearward from the first pipe, on either side of the horizontal axis of the blades. The fourth pipe in such case preferably has a vertical axis extended through or substantially near a rearward part of the nacelle, as well as through or substantially near the horizontal axis of the blades.
In such case, four webs are preferably extended between the four pipes, around the exterior thereof, thereby forming a square, rectangular or diamond shape from above. The webs not only increase the strength and rigidity and moment resistance of the tower, but also allow for a ladder and safety cage or an elevator to be extended to the top of the tower.
While the preferred embodiments have multiple pipes that are substantially parallel to each other with a web connecting them, other configurations, including pipes that are not parallel to each other, that may form a pyramid shape are also contemplated (with or without webs). Generally speaking, a wind farm can be created by using more than one wind turbine station of the type described herein, including any mixture of different types of wind turbine stations. For example, in a small application, three wind turbine stations of the type described above can be provided, wherein each tower can have its own compressor and/or electrical generator, and wherein a separate turbo expander and generator set can be provided for each wind turbine station, or one can be provided in connection with all three stations. In the latter case, to enable compressed air to travel from one station to another, or one tower to another, and so that the compressed air in all the vessels can be released by a single turbo expander and generator set, an underground pipe or tube is preferably provided that extends between the stations and towers, such that compressed air can flow from one vessel to the other, and from one tower to the other, and be released at the appropriate time.
One of the advantages of the wind turbine station and tower of the present invention is that the builder of the facility can avoid the high cost of having to construct both a separate tower and a separate storage tank for storing compressed air, wherein in current practice, the cost of the tower itself can be more than fifty percent of the total cost of the station. This way, the cost of separately providing the tower and storage tank can be eliminated, thereby making these systems more cost-effective to install.
Another advantage is that the height of the wind turbine blades can be increased substantially by creating a strengthened tower that can better resist the wind forces and resulting bending moment forces that can be applied to the top of the tower as the wind engages the turbine blades at higher elevations. This not only allows the turbine blades to be situated higher to access greater wind speeds, and therefore, achieve increased efficiencies, but also enables the wind turbine stations to be provided with greater storage capacities and located closer to potential upwind obstructions, i.e., by allowing the blades to be positioned above the height of the obstruction, it becomes possible to locate the tower closer to the obstruction.
Being able to build towers higher also enables adjacent wind towers to be built closer together, wherein the height of one can be offset from another, so they don't interfere with each other. In this respect, the swept area of the turbine blades determines the torque and power output of the stations, and must be a certain distance above and/or away from other wind turbine stations or other upwind obstructions to ensure that the airfoil cross section of the rotor blades receives the laminar flow required for the maximum torque output.
In the preferred embodiment, at least two vertically oriented tanks or vessels 9, extended parallel to one another, with their longitudinal axis extending substantially vertical, are provided and installed per tower 3, although not necessarily so, i.e., a tower 3 can have one tank or vessel 9, but preferably two or more tanks or vessels 9, as will be discussed. Preferably, as shown in the cross section drawing of
Within each tower 3, tanks or vessels 9 preferably have means for communicating with each other, such that the compressed air can pass between multiple tanks or vessels 9. For example, a tube or other passage 10 is preferably extended between tanks or vessels 9 so that compressed air can pass from one tank or vessel 9 to the other such, wherein the pressure inside both tanks or vessels 9 can be maintained in substantial equilibrium.
In the embodiment shown in
Another cable (not shown) can be extended from generator 13 down such that electricity generated by station 1 can be transmitted directly to an end user or grid, such that it can be used immediately without storing the energy first. Using the electricity without storing it first results in more efficiency since there is normally a fair amount of energy loss resulting from converting energy from electricity to compressed air and then back again. In such case, a switching mechanism is preferably provided that enables the energy output to be switched between electricity generated by generator 13 for immediate use and transmitting the electricity produced by generator 13 to drive compressor 15 for purposes of storing the compressed air in tanks or vessels 9. Whether the switch is set to one position or the other will depend on a number of factors, including whether more energy is needed immediately, or whether there is excess energy available for storage, which can be a function of the supply and demand curves for the site.
As shown in
The embodiment shown in
Having a compressor 19 in nacelle 5 avoids the need to convert mechanical power into electricity before compressing the air, i.e., power is not lost by having to convert it from the mechanical wind power to electrical power to drive the compressor. This arrangement preferably reduces the energy losses normally attributed to the following conversions: 1) from wind energy to electricity, 2) from electricity to compressed air energy, and 3) from compressed air energy back to electricity again.
The mechanical energy produced by the rotational movement of blades 7 directly powers compressor 19 and this produces compressed air energy which is then stored in tanks or vessels 9. The compressed air can then be released at the appropriate time and converted into electricity without having to convert the mechanical energy to electricity first. Accordingly, this embodiment does not need an electrical generator 13 for producing electricity before compressing the air, as in the previous embodiment, insofar as the mechanical energy directly produces compressed air energy which is then stored.
At the same time, as shown in
In another embodiment, as shown in
In either case, tower 3 is preferably configured and constructed in the following manner: In the embodiment of
With pipes 6 partially buried in ground 21, a predetermined conductive material 23 such as concrete preferably surrounds the bottom of each pipe 6, so that the hot and cold temperatures that may result as compressed air is being injected and released, respectively, can be dissipated into ground 21 by the surrounding material 23. In this respect, an increase in temperature can occur as compressed air is introduced into tanks or vessels 9 through compressor 15 or 19, or a drop in temperature can occur within tanks or vessels 9 as the mass of compressed air is released by the turbo expander and generator set 17, which will lower the air mass density. Each tank or vessel 9 preferably comprises 1) a thermal conductivity zone that extends from the bottom of each pipe 6 to about ground level, and 2) a regular conductivity zone that extends from about ground level to the top of tower 3. The thermal conductivity zone preferably has conductive material such as concrete 23 surrounding the lower portion of pipes 6 to enable warmer or colder air temperatures created within tanks or vessels 9 to be distributed into ground 21 and dissipated more rapidly. This helps to regulate and control the temperature of the air inside tanks or vessels 9, including the regular conductivity zone. The thickness of the walls of tanks or vessels 9 can also help control the temperature of the air inside. A support or bearing structure 24 is preferably provided at the bottom of pipes 6 to provide support for tower 3. The top and bottom ends of pipe 6 are preferably rounded to ensure even distribution of pressure against the walls of pipe 6, wherein nacelle 5 and support structure 24 are preferably adapted to take into account this variation in shape.
Preferably, the diameter of pipes 6 used in the towers can range from about two feet to about four feet or more, with a preferred diameter being about three feet, depending on the amount of desired storage space needed, as well as the thermal capacity needed to control the temperature of the air within tanks or vessels 9. The thickness of the walls is preferably determined based on the maximum amount of pressure to be expected within tanks or vessels 9 as well as the amount of bending forces to be expected due to wind forces being applied against the top of tower 3, which can result in extra compression and tensile forces being applied to the walls of pipes 6. The thickness of the walls of tanks or vessels 9 and web 11 are also dependent on the amount of thermal capacity that needs to be provided to regulate and control the temperature of the air inside, and the strength needed to support the weight of tower 3. Web 11 can be provided with a ladder 28 and safety cage 30, as shown in
In the embodiments of
As shown in
The increased flexural strength, rigidity and moment resistance of tower 3 enables tower 3 to be built higher, which makes the overall system more efficient. For example, using the same wind turbine, a 200 feet tower could potentially produce as much as five times more energy/power than a 60 feet tower, since greater wind speeds are typically encountered at higher elevations above ground. Enabling blades 7 to be located higher also has the advantage of increasing the storage capacity of each tower, and eliminating the deleterious effects of tall upstream obstacles, such as adjacent trees and hills, including other wind turbine stations.
By having increased flexural strength and rigidity and moment resistance, tower 3 can be built to withstand greater wind forces and therefore it can be built even taller, thereby accessing higher wind speeds using the same wind turbine, and increasing the efficiency of the wind turbine design. Accessing greater wind speeds will also enable the power output levels of the components used in the system to be scaled upward, including the compressor 15 or 19, which can advantageously make the entire system run more efficiently in terms of the cost to produce a single unit of energy output. For example, a 2,000 kW wind turbine station with a 1,200 psi compressor might be able to produce energy at a cost per unit that is less than one third the cost of producing energy using a 30 kW wind turbine station with a 1,200 psi compressor.
Larger installations also permit more airflow to be brought to the same high final pressure, and large compressors, such as centrifugal compressors, often have variable drive mechanisms that can be operated at lower torque levels, such as those produced with lower wind speeds, whereas, small compressors, such as piston air compressors, normally operate only at a predetermined torque. In the latter case, multiple smaller compressors are often required, wherein each of them may only operate at lower levels. Although variable drive technologies are more efficient and can deliver more power more consistently, the upfront cost of installing them can be substantially higher, and they can be more delicate to operate and maintain. All of these considerations should be taken into account when choosing which compressor to install.
While in the embodiments of
The embodiments of
Web 11a strengthens tower 3 and preferably extends between pipe 6a and pipe 6c. Additional webs 11b and 11c are preferably extended respectively between pipes 6b and 6c, and pipes 6c and 6d, wherein webs 11b and 11c are preferably extended along a plane that is perpendicular to the plane of web 11a, thereby forming a T configuration from above—in plan view as shown in
A separate web section is preferably provided between each pipe, i.e., web 11a is extended between pipes 6a and 6b, web 11b is extended between pipes 6a and 6c, and web 11c is extended between pipes 6b and 6c. Again, ladder 28 and safety cage 30 or elevator (not shown) can be provided on one or more webs, 11a, 11b, or 11c.
This is an example of a wind farm comprising three stations 1, but other wind farms comprising any number of wind turbine stations 1 are within the contemplation of the invention. The determination as to how many wind turbine stations should be provided in any given application is a function of many factors, including the demand for energy, and how much energy is needed for storage, etc.
In the embodiment of
The distance between stations and the length of pipe 31 and the amount of desired storage space needed within tanks or vessels 9 and pipe 31 can be considered when designing the wind farm including the number of stations to be used and where they should be located, etc. Although any number of wind turbine stations 1 can be connected to a single turbo expander and generator set 17, a determination should be made in connection with each wind farm to determine how many towers 3 and how many tanks or vessels 9 should be connected to each turbo expander and generator set 17. This is normally a function of the amount of energy needed to be produced by the wind farm, based on demand, and how much energy can be generated by the wind turbines, and how much storage space is required for any given application, but this should also be based on how many towers 3 and tanks or vessels 9 should be used in connection with a single turbo expander and generator set 17 to achieve the greatest efficiency. This last determination will often be a function of the amount of compressed air energy stored and used at any given time, and how efficiently the turbo expander and generator set 17 can be operated in connection with the size and number of tanks or vessels 9 involved, which determines the volume of compressed air that will need to be stored, wherein the goal is to optimize the efficiency of converting the compressed air energy into electricity, based on the rating of the turbo expander and generator set 17.
In this embodiment, a control system is preferably provided which enables the extent to which energy is converted into storage via compressor 51 and/or converted into electricity via generator 53 can be adjusted, based on the supply and demand cycles imposed on the system. For example, in one scenario, this embodiment can be set so that at least some of the wind energy is always converted into electricity first, to supply power to the grid or end user continuously, wherein any excess energy not needed by the grid or end user can then be used to drive the compressor to produce compressed air energy that can be stored.
In such case, a mechanism that determines when electricity is in excess and when it is not is preferably provided, wherein, in the case of a large wind farm with multiple wind turbine stations, the system is able to know what amount of energy should go into storage and what amount should be distributed to the end user or grid, and this can be determined with respect to each wind turbine station, wherein such a determination is preferably made system-wide based on the total demand imposed on the wind farm. In such case, a servo-mechanism in the control box preferably receives power demand signals and information from the end user or grid, such as in the form of power demand histories in 15 minute intervals during a period of the past 3 days, as an example. It also preferably predicts the power demand requirements on the system for an upcoming period of time, while taking into account the instantaneous wind turbine power production output levels. This applies in the case of a single wind turbine station or a wind farm composed of multiple stations wherein some are more active than others.
In either case there can be inflow of information from the following:
(1) The “end user” or “grid” can provide information regarding the real time power demand continuously exerted on the system, which can be supplied in short time intervals, such as every 15 minutes. It can also comprise data collected over a predetermined time, such as over the previous 3 day period, again, as an example.
(2) A prediction is preferably made available based on the local wind history data provided for the site that is accurate for a predetermined amount of time.
(3) Generator 53 is preferably assigned a higher priority than compressor 51 such that generator 53 will mesh with turbine driver 45 before compressor 51 will mesh with driver 45, such that electricity will be generated in sufficient amounts before excess energy will be stored.
(4) When the logic circuit of the control system identifies that there is sufficient wind power to supply both generator 53 and compressor 51, to produce both electricity and compressed air energy, both converting devices are preferably adapted so that they will mesh with the gears on turbine driver 45, so that both electricity and compressed air energy can be produced simultaneously. In this respect, the gears are preferably adapted so that the system provides a sufficient level of flexibility in distributing the appropriate amount of power to compressor 51 and/or generator 53. For example, the gears can be set so that the generator may receive increments of 100%, 80%, 60%, 40%, 20% or 0% of the wind power available from the nacelle, whereas, the compressor can receive whatever energy is left. In such case, the logic circuit preferably does not permit more electricity to be sent to the end user or grid than will be in demand at any given time, since there is no way for the system to absorb the excess electricity. And if the ratio does not permit an exact match of energy between immediate use and energy storage, any difference can be made up by supplying energy from compressed air in storage.
In practice, storage tanks or vessels 9 of the present invention are preferably used to store energy whenever energy supply exceeds demand. For example, in the embodiment of
Then, when demand exceeds available source energy, the compressed air energy in storage can be used to supply supplemental energy to the end user or grid, etc. This can be accomplished by releasing the compressed air energy from storage using the turbo expander and generator 17 to produce electricity. The cold air co-generated as the compressed air is released can then be used for ancillary purposes, such as refrigeration, air conditioning, desalination, etc. Again, a minimum pressure of at least 200 psi is preferably maintained.
Whether a station is in the energy storage or energy use mode is preferably controlled with a circuit switch which controls whether excess energy is fed into storage, or whether the stored energy is used to supplement the existing energy supply. To make that determination, the circuit preferably uses instantaneous data from one or more sensors that determine 1) the amount of pressure stored within tanks or vessels 9, 2) the amount of electric power being delivered by the wind turbine stations to the end user or grid, etc., and 3) the demand for electric power by the end user or grid, etc. Based on this data, when the criterion is met, power begins to be distributed into or out of storage, and/or is used immediately by the end user or grid, etc.
Note: In situations where small compressors are used, the system may be designed to determine whether there is sufficient wind power to drive the compressors, including whether there is only enough to drive one compressor at a time, in which case, the system can be set up so that fewer than all compressors can run at any given time. And in situations where multiple stations are used, along with a separate small compressor in each station, the system is preferably designed to determine how many small compressors can be driven at any given time, wherein, the system is preferably capable of being switched to drive only those compressors that are small enough to be driven by the available wind power supplied. If the available wind power is insufficient to drive the compressors, the compressors can be turned off, and the system can send the excess power to waste.
In connection with the features of the present invention described above, including applications where multiple wind turbine stations are constructed to create a large wind farm, it can be seen that the teachings of applicants' prior U.S. application Ser. No. 10/263,848 can be combined with the teachings of the present invention, and therefore, previous application Ser. No. 10/263,848 is incorporated herein by reference. Indeed, it can be seen that the wind turbine stations and towers of the present invention can serve as either the storage windmill stations or the hybrid windmill stations in connection with the wind farms discussed therein.
The present technology can also be used in connection with the technology described in applicants' prior U.S. application Ser. No. 10/865,865, which relates to how the compressed air energy in storage can be used to provide a limited number of substantially constant power output periods during any given 24 hour period, despite fluctuations in wind speeds, etc., and thus, U.S. application Ser. No. 10/865,865 is also incorporated herein by reference.
The present technology can also be used in connection with the various technologies described in applicants' prior U.S. application Ser. Nos. 11/585,023; 11/731,717; 12/214,137; 12/321,689; 12/587,340; and 12/930,117, and therefore, those applications are also incorporated herein by reference. For example, the chilled air co-generated by the release of compressed air from the turbo expander and generator set 17 can be used for the following purposes:
1) In connection with U.S. application Ser. No. 11/585,023, the present technology can be used in connection with a thermal energy storage system, wherein the chilled air produced by releasing the compressed air energy in storage can be used to provide chilled water in a stratified container for other purposes, such as air conditioning and the like.
2) In connection with U.S. application Ser. No. 11/731,717, the present technology can be used for desalination of seawater wherein the chilled air produced by releasing the compressed air energy in storage can be used to freeze seawater and remove salt and other impurities therefrom.
3) In connection with U.S. application Ser. No. 12/214,137, while the present technology can be used for desalination of seawater, as described above, the minerals found therein can also be removed and used for other purposes.
4) In connection with U.S. application Ser. No. 12/321,689, the present technology can be used in connection with the removal of CO2 from a coal burning power plant, using the chilled air produced by releasing the compressed air energy in storage to freeze CO2 released from the power plant, wherein the frozen CO2 can then be distributed for other purposes, such as for providing carbonation in beverages, etc.
5) In connection with U.S. application Ser. No. 12/587,340, the present technology can be used in connection with using compressed air energy to increase the efficiency of a fuel burning turbine generator, wherein the chilled air produced by releasing the compressed air in storage can be used to lower the temperature of the input air, as well as remove water particles from the input air by freezing the particles, so they don't cause damage to the turbine blades.
6) In connection with U.S. application Ser. No. 12/930,117, the present technology can be used in connection with CO2 released from a power plant, which can then be chilled using the chilled air produced by releasing the compressed air energy in storage provided by the present invention, wherein the cold liquid CO2 can then be injected into an underground rock formation containing particles of coal or gas shale, etc., to help fracture rock formations therein, and thereby release the methane gas trapped therein through adsorption.
Other uses and applications are also contemplated that are consistent with the usages described above.
