Abstract:
Several embodiments are disclosed that enhance and improve the efficiencies of alternative electrical generating sources by converting electrical energy to potential energy through electro-mechanical means. The embodiments provide gravitational energy storage by lifting masses from lower to higher elevations during desired periods, such as when the generating sources are producing excess energy or when electrical rates are the least expensive. Energy storage is maintained until such time as it is need and then converted from potential mechanical energy to electricity by gravitational forces. By storing energy, one can supplement and enhance the efficiencies of producing electricity by alternative means such as wind and solar by expanding the times when electricity is available. Additionally, one can time-shift the purchase and use of commercial power by buying power to store energy when rates are low and using the stored energy when rates are high.

Description:
RELATED APPLICATION 
     This application claims benefit of U.S. provisional application Ser. No. 61/125,588 filed Apr. 26, 2008 and U.S. provisional application Ser. No. 61/208,409 filed Feb. 24, 2009. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The invention is directed to the field of making more efficient use of non-continuous alternative energy sources such as solar collectors and wind turbine generators, as well as taking advantage of conventional electrical energy sources during times of low demand when such energy is available (provided) at a lower cost, by utilizing improved energy storage techniques that are suitable for universal implementation. 
     2. Description of the Prior Art 
     Although wind can be found everywhere on the planet, and is always blowing somewhere, it is erratic. It is erratic as to where it blows, when it blows, at what speed it blows, the length of time it blows and what kind of wind it is . . . steady, gusting, changing direction . . . or all at the same time. This erratic factor is often overlooked when manufacturers and governments claim energy efficiencies from wind turbines. Similarly, solar collectors are dependent on a steady supply of exposure to solar radiation. Solar energy is the most inconsistent due to night and clouds. 
     Techniques for enhancing the efficiencies of these alternative and inconsistent energy sources can involve the conversion of electricity to a form of potential energy and storing that energy until it is need to be converted to electrical energy. Electricity, produced during periods of high output and low demand, can be time-shifted through energy storage so that the energy is available when the demand exceeds the output of the alternative sources. Batteries are the most common form of energy storage. However, they are expensive to acquire and maintain, and involve risks of environmental damage. Other techniques have been disclosed that involve the pumping of water to an existing reservoir for later release to drive turbines for electrical power generation. While this is suitable for large energy needs, it requires a ready and large supply of water for implementation. The enormous up front, capital costs and potentially adverse environmental impacts preclude the building of new reservoirs for these purposes. Techniques for storing air and liquids under pressure for later release have been disclosed. Such techniques are usually limited to small installations used to drive a motor or pump for a limited time and application. Each of these prior art energy storage techniques have their advantages and limitations depending on the availability of water, varying elevations, and availability of technical service for frequent maintenance. 
     SUMMARY OF THE INVENTION 
     In the present invention, several embodiments are presented in which facilities contain large masses (weights) that are electro/mechanically raised from their lowest levels to maximum heights against the force of gravity and locked in place to store potential energy. Electrically responsive motors are used to produce work on the large masses to move them from a position of low potential energy to a position of higher potential energy. Later, when electrical energy is desired to be obtained from the storage facility, the weights are controllably dropped to lower levels by gravitational forces. During the drops, the weights are connected to drive electrical generators and electrical energy is produced. By scaling up the invention one can produce sufficient electricity to power the electrical needs of factories, multi-storied high rise buildings and small villages during periods of emergencies, black-outs, or at times when energy rates are at their highest. 
     In a first embodiment, an electric motor is connected to the output of a wind turbine generator and is geared or similarly mechanically connected to lift a large mass (weight) alongside the mast pylon that supports the turbine. This usually occurs during times when there is low demand for the wind turbine generator output. During such times, the electric motor is engaged and the weight is raised from a low height towards the maximum height allowed by the embodiment. 
     A second embodiment of energy storage utilizes a single or series of masses to be raised and lowered inside the tubular mast supporting an associated wind turbine. 
     A third embodiment of energy storage utilizes a small grouping of cylindrical storage tubes having their central axes aligned along the vertical. Each storage tube contains movable masses. These tubes can be separate from a renewable or non-renewable electrical source such as wind turbine, or utility, but can be controlled individually or as a group to store energy and generate electricity at a later time. 
     A fourth embodiment of energy storage utilizes an array of vertically oriented storage tubes which each contain one or more movable masses. 
     A fifth embodiment of energy storage utilizes open cores of a high rise building to contain movable masses. This embodiment is suitable for use in association with wind turbines that are integrated within the building. 
     Other embodiments of energy storage involve various common mass storage facilities that utilize several electric motors connected to lift several large masses against the force of gravity and store those masses in positions of higher potential energy until such later time that their potential energy is required to be converted to electrical energy. At such later time, the masses are allowed to be lowered by gravity and an associated generator is mechanically driven to produce electricity for the desired load. To be viable on a large scale a “flow through” system is necessary to handle the varying input, storage and generating demands which change minute by minute, hour by hour, etc to meet the demands of Utility companies and industrial and commercial customers. 
     It is one object of the present invention to provide a relatively low cost and reliable energy storage system and method that can be used to supplement the high cost of electrical power during peak demand times. 
     It is another object of the present invention to provide a relatively low cost and reliable energy storage system and method to supplement the output of alternative and/or on-site power generation sources during times when they cannot produce electricity. 
     It is a further object of the present invention to provide an energy storage and delivery system and method that assists in load balancing distribution networks to allow alternative energy sources from solar and wind energy “schedulable”. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an elevational view of a typical and conventional 3-bladed wind turbine generator containing the first embodiment of the invention shown in a first stage of no gravitational energy storage with the liftable mass at its lowest level. 
         FIG. 2  is an elevational view of a wind turbine generator shown in  FIG. 1  shown in a second stage of gravitational energy storage the liftable mass at an intermediate level where is provides a measure of potential energy for later release. 
         FIG. 3  illustrates vertical avis type wind turbine generators associated with integral energy storage devices of the present invention. 
         FIG. 4  illustrates the concept of utilizing a small group of individual tubular towers to store energy produced by associated but remote wind turbine generators or other sources. 
         FIG. 5  illustrates the concept of employing an electric motor to raise a mass and a generator being gravity driven during the lowering of the mass within a storage tube. 
         FIG. 6  illustrates the efficiency of employing a large array of closely spaced storage tubes such as those shown in  FIG. 5 . 
         FIG. 7  illustrates the concept of employing a central shaft or open core of a multi-storied high-rise building for energy storage and integrating the storage with building mounted wind turbine generators. 
         FIG. 8  illustrates the concept of an energy storage facility for a plurality of large mass elements raised to higher levels and for generating electricity when the mass elements are lowered. 
         FIG. 9  illustrates the concept of storing large mass elements at varying heights and being able to manipulate the mass weights to a designated drop zone for electricity generation when desired. 
         FIG. 10  illustrates a system for both generating electrical power from wind turbine generators and storing energy by raising a large plurality of mass elements from an under-ground location to an above-ground level and generating electricity when the mass elements are lowered back into the below grade location. 
         FIG. 11  illustrates the details of operating the underground energy storage system of  FIG. 10 . 
         FIG. 12  illustrates another system for storing energy by raising a large plurality of mass elements to higher levels and generating electricity when the mass elements are lowered on a helical conveyor. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Energy storage is of primary importance in increasing the efficiency and scheduling of alternative sourced electrical power. While commercial utility power plants provide substantially continuous base load energy during extended periods of weeks and months, most alternative energy systems that use solar or wind power are inherently intermittent because of variations in the input energy (night, clouds and wind speeds outside the operational window). At night, when energy requirements are relatively low, the produced but unused energy is effectively “wasted”. Although alternative energy sources are inherently intermittent and therefore somewhat inefficient, there is a vast market available for otherwise wasted energy, provided practical storage and conversion to electricity is available for use at alternative times. The present invention provides a means for taking advantage of this potential market and opening up opportunities for both suppliers and users of electrical energy. For suppliers, it provides a means for off-loading or decreasing demand during periods of normally high demand with the potential result of reducing the frequency to add or replace generating equipment. It also allows suppliers to sell more energy during traditionally low demand periods (night time) at competitive rates and allows for better balancing of the grid. For the user, it provides a means of time-shifting the times it purchases electricity from the grid and to save significant amounts of money by purchasing at competitive rates during such low demand times, and then using the stored energy during times when rates and demand are highest. By combining the storage techniques of the present invention with auxiliary power sources, users can significantly reduced their electrical power costs. 
     The first embodiment is shown in  FIGS. 1 and 2 , wherein a wind turbine generator  1  is shown with a vertical support pylon  2  and a conventional set of three blades  4  connected to an electrical generator unit  6 . A large mass  10 , such as concrete or lead is secured to lifting cables  12  which are suspended from a support beam  14 . Electric motors (not shown) are mechanically connected to the lifting cables to provide work energy to the mass  10  against the force of gravity. The electric motors are connected to receive electrical energy from the output of the generator unit  6  when demand is low and it is determined that excess electricity is being generated that would otherwise be wasted. When such a condition exists, the electric motors are energized and cause mass  10  to be lifted by support cables  12  upwards along the pylon  2 . This results in the gravitational storage of energy that is maintained until electrical energy is demanded that is greater than the wind turbine generator unit is able to output. When more energy is required, such as when the wind velocities are outside the design window and the electrical distribution grid shows (or owner/user has) a demand, the mass is allowed to be lowered by gravity and through appropriate gearing, drives the generator to produce electricity and thereby increase the usable efficiency of the wind turbine. 
     A second embodiment is shown in  FIG. 3 , as an energy storage system incorporated into the hollow support pylon  22  of a vertical axis wind turbine (VAWT)  20 . Mass weights  30  are suspended within the support pylon  22  preferably with cables  32  such as are shown in  FIG. 5 . The VAWTs  20  each include an individual electrical low speed generator  54  below the turbine and the output from the generator  54  can be controlled to energize the lifting motor  52  to lift the mass  30 .  FIG. 5  illustrates the concept of using an electric motor to lift a large mass higher into the pylon or tube to store it for later use. As in the first embodiment, the mass  30  is moved from a position of relatively low energy potential to positions of higher energy potential. When it is desired to draw on the stored energy, the mass  30  is released under controlled conditions to drive an associated electrical generator  54 . In  FIG. 3 , the grade G 1  is shown to give perspective to the installation that would be preferable above and below grade. The mass of the weights and range of lift determine the quantity of potential energy that can be stored. 
       FIG. 4  shows that a separate group  40  of energy storage tubes  42  may be used to store potential energy. In this case, tubes  42  are mostly below grade G 2 . Individual tubes  42  each have a motor  52  and generator  54  located in the head  56 , as shown in  FIG. 5 , to control the raising and lowering of weights  30 . The group  40  can be associated with one or more auxiliary electrical energy sources such as wind turbines or solar collectors. However, such association is not required in order to store energy. Any source of electrical energy can serve to drive the motors that lift the weights. The group  40  is controlled to store potential energy and release energy in the form of generated electrical power when desired. 
       FIG. 6  illustrates the concept of  FIG. 5  implemented a large group  40 A of storage tubes in an array  42 X× 42 Y. As in  FIGS. 4 and 5 , Individual tubes  42  each have a motor  52  and generator  54  located in the head  56  to control the raising and lowering of weights  30 . Each tube performs the same function of mechanically storing energy and providing electrical power at a later time. However, with a great number of storage tubes, it can be seen that there is a potential for storing significant amounts of energy for later use. 
       FIG. 7  illustrates the concept of how many high rise buildings  80  contain cores or open shafts  82  that are unused; or, if used, contain significant clear air space. In such cores, the energy storage techniques disclosed herein may be implemented to supplement the production of alternative energy such as from wind turbines  84  integrated on the building  80 ; emergency power; or as a low cost alternative to commercial utility power by buying energy during times of low power cost alternative to commercial utility power by buying energy during times of low power rates (night) and storing that energy for release at times of high power rates (day). In the case of high rise buildings, the shafts  82  can be many stories high and reach deep into the substructure  81  of the building below grade G 3  and the roof can support the central lift mechanism  86  to raise and lower weights  88 . 
     Although not shown, the high rise building embodiment of  FIG. 7  can be readily adapted to be employed in abandoned mine shafts located in the vicinity of wind turbine farms. Since some mine shafts extend several thousands of feet below the surface, there is opportunity to store significant amounts of potential energy during times of low demand. 
       FIG. 8  provides an alternative embodiment to the tube structures presented above. In this embodiment, a central gravity storage facility  100  is depicted in which storage racks  102  are provided to store several weights  200   a - 200   z  in parallel stacks of mass elements in vertical series. A lifting mechanism is driven by electric motors  120   a - 120   n  in response to a control panel  140  to lift each weight to its maximum height. When individually released, the lifting mechanism is driven in an opposite direction that drives an associated electric motor in reverse or drives separate electrical generators (not shown). Since the weights  200  are stacked in vertical series, each lower weight  200  in a single stack has the same potential energy as the ones above it, since they are each raised and lowered the same distance (assuming each weight is equal to the others in the stack). But because the weights  200  are individually controlled, the overall potential energy can be significant. The embodiment shown in  FIG. 8  is suitable for buildings such as warehouses, factories and hangars, as well as basements. 
     Mass handling of weights and storing of potential energy on a large scale is depicted in  FIG. 9-12 .  FIG. 9  illustrates the general handling methods used in the large scale facilities of both above-ground and below-ground installations. The facility  300  is configured to have a lift zone  310  and a drop zone  320 . In the lift zone  310 , individual mass blocks  204   a-n  are raised from their postions of low until electricity is desired to be withdrawn from the facility  300 . The higher potential blocks  302   a-n  are placed on a slanted surface or conveyor to allow them to collect in the opposite end near the drop zone  320 . In the drop zone  320 , individual platforms are controlled and connect to one or more generators to produce electrical power when the blocks are dropped to the lower level. Electricity from conventional or auxiliary sources is used to raise heavy mass elements, preferably lead blocks (e.g. lead weighs 11,000 kgs per cubic meter), and store them as potential energy. Energy can be stored without losses for seconds, minutes, hours, days or years. When energy is required, the blocks are dropped and the resulting kinetic energy drives the generators to produce electricity. 
     A large version of a facility utilizing the principles shown in FIG. is depicted in  FIGS. 10 and 11  as an under-ground mass storage system. In  FIG. 10 , the system  400  is shown in conjunction with an array of VAWTs  500  to provide the energy needed to operate the storage facility. 
     As mentioned earlier, many utility companies provide power at much lower rates when demand is less, such as at night. No matter which source of electrical power is employed, the system of  FIGS. 10 and 11  is desirable and can provide significant cost savings. Assuming the scenario of buying and storing relatively cheap rate utility energy when it is available; and also supplementing auxiliary energy during times of high utility rates with stored energy helps to understand the advantages of the system shown in  FIGS. 10 and 11 . 
     In  FIGS. 10 and 11 , an underground generation facility  400  is shown in which the storage for the mass elements  600  at higher potential energy is at ground-level “G” or higher, while the lift zones  410  and drop zones  420  are underground. In this facility, the lift zone  410  is at the left end and the drop zone  420  is at the right. Lifting is performed by utilizing cheap or excess electricity to drive electric motors and the blocks  600  are stored at the upper level “G”. The blocks  600  are conveyed by low friction horizontal linear conveyor system  440  means to the drop zone  420  as space opens up at the right end. A horizontal belt conveyor  440  with a slope of approximately 1% is used to move the blocks towards the drop zone  420 . As electrical energy is demanded to be generated by the storage facility, the upper stored blocks  600  are released at the drop zone  420 . An escapement mechanism is controllably used to transfer the blocks  600  to the underground drop and generation section. A sloping floor in the underground section  450  contains conveyor tracks  460  that are connected to one or more generators. As the load of blocks  610  on each track is drawn downward by gravity, the generators keep producing electricity. Near the end of the first section of the conveyor tracks, a slight upward ramp  470  allows the blocks  610  to be raised by the conveyor and momentum of the blocks to a second downward sloping area  480  where they are released from the generator conveyor tracks and allowed to approach the lift zone  410  on a conveyor  490  with an approximately 1% downward slope. 
       FIG. 12  shows another embodiment of a mass energy storage facility  700  that uses several floors  702   a - n  of high potential storage. In this embodiment, the lift zone  710  is on the right and the drop zone  720  is on the left. Blocks  800  are raised by electric motors to appropriate floors where horizontal linear belt conveyors  730   a - n  provide low friction transfer of the blocks along a 1% slope towards the drop zone  720 . In order to allow each floor of potential energy storage to drive the energy generators, a helical conveyor  740  is connected to a generator and each floor is able to release blocks through a mechanical escapement mechanism to the helical conveyor  740 , as needed. These systems can be scaled up or down to meet the requirements of the electrical customer or user and the inventive concept is not restricted to any size limitation. 
     It can be seen by the drawings and accompanying explanation, the present invention is a unique improvement over conventional electrical storage techniques and facilities. And while the embodiments shown here are varied they shall not be considered to be a restriction on the scope of the claims set forth below.