Abstract:
A system and process for generating hydroelectric power within a body of water uses head pressure existing between two depths of the water. A vertically arranged conduit has an upper water intake and is in fluid communication with a reservoir situated at a lower depth. In a first cycle, water flow is established in the conduit between the water intake and lower reservoir when the reservoir is substantially full of air but at a hydrostatic pressure less than the hydrostatic pressure at the top of the water conduit. A turbine mounted adjacent the reservoir and at a lower depth than the water intake drives an electric generator. As water is introduced into the reservoir, air is scavenged by a compressor and used to drive water from a second reservoir. After the first reservoir is generally full of water, valves are provided to cease the flow of water through the water intake and flow of air out the exhaust tube. An air pump thereafter introduces air scavenged from the first reservoir into the second reservoir to force water out of a second reservoir water outlet port. The generating cycle is then repeated.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a continuation-in-part of U.S. application Ser. No. 11/998,360 entitled, “System and Process for Generating Hydroelectric Power” by Steven J. De Angeles, filed on Nov. 30, 2007, the entire contents of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to electric energy generation systems and methods. More particularly, this invention relates to a system and method for generating electrical energy using head pressure or hydrostatic water pressure. 
       BACKGROUND 
       [0003]    Attempts have been made to generate electricity without also disrupting ecosystems, which always happens when a river is dammed, without generating environmental pollutants, which always happens when fossil fuels are burned and, without using inherently dangerous fissile materials, which nuclear power requires. While wind turbines might be considered unsightly and tidal systems require their being located proximate to the ocean, systems and methods for generating electric power that use forces of nature are environmentally harmless. A system and method for generating electric power that does not depend on the relatively unpredictable wind, or solar energy that is not available at night and which does not necessarily require placement in an ocean would be an improvement over the prior art. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0004]      FIG. 1  is a side elevational view of a system for generating electric energy; 
           [0005]      FIG. 2  is side elevational view of an alternate embodiment of a system for generating electric energy; and 
           [0006]      FIG. 3  is a side elevational view of another alternate embodiment of a system for generating electric energy. 
       
    
    
     DETAILED DESCRIPTION 
       [0007]      FIG. 1  illustrates a first embodiment of a system  2  for generating electric energy using hydrostatic water pressure differentials found at varying depths in all bodies of water, the methodology of which is considered herein to be another form of hydroelectric power generation. A platform  4  is attached to buoys  6  (shown in broken lines) floating in a relatively deep body of water  8 , the surface of which is identified by reference numeral  10 , the bottom of which is identified by reference numeral  12 . 
         [0008]    The platform  4  supports equipment that includes an above-water or surface air pump  14 , a controlling computer  16 , a wind-driven electricity generator  18  and a solar array  20  that generates electricity from sun light. The combined weight of the platform  4  and the various equipment it supports ( 14 ,  16 ,  18 ,  20  et al) requires the buoys  6  to provide a significant buoyant force and thus require the buoys  6  to extend below the water surface  10  by a relatively significant distance. 
         [0009]    Ropes, cables or rigid beams  22  attached to the buoys  6  support a pair of flexible water conduits  24  that extend downwardly toward the bottom  12  of the body of water  8 . Each water conduit  24  has a water intake opening  26 , located below the water surface  10 . The length of the cables  22  and the length of the buoys  6  below the surface  10  determine the depth of the intake  24  and the hydrostatic force present at the intakes  26 . 
         [0010]    Each conduit  24  has a second end  28  coupled to an input port  30  of a water-driven turbine  32 , which is submerged well below the level of the water intakes  26 . Two turbines  32  are shown. Both turbines  32  are coupled to an electric generator  36 . The turbines  32  are configured such that rotation of either turbine  32 , or both turbines  32  at the same time, causes the generator  36  to generate electricity, which is carried to the surface for distribution to the electric grid (not shown) by way of an insulated cable  94 , which also carries control lines (not shown) between the computer  16  and various, submerged computer-controlled devices described herein. Whether the generator  36  is one that generates alternating current (A.C.) or direct current (D.C.) is a design choice. 
         [0011]    The turbines  32  are designed and configured to be driven by flowing water as they are in a conventional hydroelectric dam. In addition to an input port  30 , each turbine  32  has an output port  34  from which turbine waste water flows, after the flowing water surrenders kinetic energy to the turbine  32 , causing it and the generator  36  to rotate. 
         [0012]    In  FIG. 1 , the combined water-driven turbines  32  and generator  36  are depicted as being on top of a submerged, water-tight reservoir  38  having two, water-tight chambers  40 A and  40 B, which are defined by an air-tight wall  42 . The reservoir  38  is preferably located far below the level of the water intakes  26  and is attached to the bottom  12  of the body of water  8  by legs or pillars  44 . The reservoir  38  can also be kept submerged by ballast, not shown. The chambers  40 A and  40 B, preferably, but not necessarily have equal volumes. 
         [0013]    The output ports  34  of the turbines  32  are coupled to a corresponding chamber  40 A or  40 B through turbine exhaust manifolds  46 , discharge ends of which are coupled to corresponding computer-controlled chamber intake valves  48 A and  48 B at a water inlet of each chamber  40 A and  40 B. In one embodiment, the exhaust manifolds are embodied as water conduits, however, in another embodiment, the exhaust manifolds can be integrally formed to be part of the turbine housing. 
         [0014]    The pathway between the intakes  26  to the computer-controlled intake valves  48  and the chambers  40  is sealed. The only way for water to flow into the chambers  40  is through an intake  26 , flowing through a conduit  24 , through a turbine  32 , through an exhaust manifold and control valve  48  and falling into a chamber  40 A or  40 B. The flow of water from the intakes  26  and through a turbine  32 , and the generation of electricity, is thus controlled by the computer opening and closing the valves  48 A and  48 B. At the same time that water starts flowing into a chamber  40   a  or  40   b,  an the air exchanging compressor  90  coupled between the two chambers  32 A and  32 B is activated by the controlling computer  16 . The air exchanging compressor  90  captures or “scavenges” and re-cycles air in the first chamber  40 A by directing it into the second chamber  40 B to drive water in the second chamber  40 B into the body of water  8  through a corresponding one-way water check valve or a sliding, water-tight door  54  as the water level rises in the first chamber. 
         [0015]    Water will flow into the intake  26 , through the conduit  24 , turbines  32 , driving the generator  36  as it goes, and flow into a chamber  40 A or  40 B, if the hydrostatic pressure inside the chamber  48 A is less than the hydrostatic pressure at the intake  26 . Electric energy can thus be generated so long as water flows through the turbines  34  with sufficient energy to drive the generator  36  as well as any load it might be connected to. In order to generate electricity using the head pressure between an intake and a chamber, it is necessary to create a pressure differential by purging a chamber  40 A or  40 B of water and reduce internal hydrostatic pressure relative to the hydrostatic pressure at an intake  26 . 
         [0016]    Hydrostatic pressure inside the chambers  40 A and  40 B can be reduced below the hydrostatic pressure at the intakes  26  by driving water out of a chamber  40 A or  40 B and reducing its internal pressure. To start the system  2 , water inside the chambers  40 A and  40 B is initially driven from a first chamber  40 A or  40 B by high-pressure air provided by a the surface-located air compressor  14 . The surface air compressor  14  runs on electric power stored in one or more batteries (not shown) and which are charged using electricity generated from the wind turbine generator  18  or collected by the solar panels  20 . The controlling computer  16  monitors battery charge state and controls the outputs of the wind-driven generator  16  and solar panel  20  accordingly. The controlling computer  16 , which is also powered by one or both of the generator  18  or solar array  20 , also controls operation of the air pump  14 . The energy required to create a pressure differential between the intakes and chambers and the power to operate the system in a steady state is thus provided by environmentally benign, renewable energy sources. 
         [0017]    The high-pressure air from the surface air compressor  14  is carried to one of the chambers,  40 A for example, by way of a high-pressure air line  50 , the distal end of which is coupled to a first, computer-controlled air valve  52 . The computer controlled air valve  52  is opened and controlled by the computer  16  to allow high pressure into the chamber  40 A. High pressure air drives water from the chamber  40 A just as it does the water in the ballast tanks of a submarine. 
         [0018]    The high-pressure air line  50  is shown connected to the left-side chamber  40 A but whether the high-pressure air line  50  is coupled to the left side chamber  40 A or right side chamber  40 B is a design choice. When the air pressure at the air valve  52  reaches a sufficiently high level, air from the air pump  14 , enters the left-side chamber  40 A and displaces water from the chamber  40 A just as ballast tanks of a submarine are “blown.” Water flows out of the chambers  40 A and  40 B through a one-way check valve  54 . 
         [0019]    Compressed air is preferably provided to the chamber  40 A until the water is emptied, however, the chambers need not be literally emptied of every drop of water they can contain. An “empty” chamber should be considered to be a chamber that has been purged of water using compressed air, but without driving so much water from the chamber that compressed air is vented into the body of water  8  and wasted, as can happen when compressed air is used to drive water from a ballast tank. The determination of whether a chamber is “empty” can be made by determining the water level inside the chamber. Determining the water level inside the chambers  40 A and  40  can be measured a number of different ways but in a preferred embodiment, the water level is measured by one or more computer-controlled ultrasonic water level detectors  56  located inside the chambers, the detectors  56  being coupled to the controlling computer  16 . In an alternate embodiment, water level inside the chambers  40  is measured by a mechanical float and transducer (not shown) coupled to the controlling computer  16 , or by a series of electrodes (not shown) at various depths inside the chambers, each of which is also coupled to the controlling computer  16 . 
         [0020]    After the chamber has been emptied by compressed air, hydrostatic pressure inside the chamber  40 A will be too high to allow water to flow into the chamber from the intake  26  end of the conduits  24 . In order to reduce the hydrostatic pressure inside the chamber  40 A, the air exchanging compressor  90  coupled between the two chambers  40 A and  40 B is activated by the controlling computer  16 . The air exchanging compressor  90  scavenges high-pressure air in the first chamber  40 A by directing it into the second chamber  40 B to drive water in the second chamber  40 B into the body of water  8  through a corresponding one-way water check valve or water-tight sliding door  54 . 
         [0021]    In a preferred embodiment, the air exchanging compressor  90  is inside the reservoir  38  and coupled to each chamber  40 A and  40 B as schematically shown in the figure. In an alternate embodiment not shown, the air exchanging compressor  90  is outside the reservoir  38  and submerged. In yet another embodiment that is also not shown, the air exchanging compressor  90  is above the water surface  10  on the platform  4  and coupled to each of the chambers  40 A and  40 B by high-pressure air lines not shown. 
         [0022]    In order to reduce the pressure inside the chambers  40 , the air exchanging compressor  90  is configured to pump air from a chamber  40 , i.e., partially evacuate a chamber, relative to the hydrostatic pressure at the intakes  26 . The air exchanging compressor  90  is thus tasked with moving highly compressed air that is initially supplied by the surface air compressor  14 , from a first chamber  40 A or  40 B to a second chamber  40 B or  40 A respectively, and pumping down or partially evacuating the first chamber to allow it to receive water from the turbine outlet port  34 . The term “waste water” is used herein to refer to water discharged from a turbine. 
         [0023]    In steady state operation, water in one chamber  40 A or  40 B is driven from the chamber using high-pressure air driven by the air exchanging compressor  90 . After the chamber  40 A or  40 B has been emptied, the air-exchanging compressor  90  re-uses the high-pressure air to empty the other chamber,  40 B or  40 A respectively and pumps down or even partially evacuates the first chamber,  40 A or  40 B respectively. 
         [0024]    In an alternate embodiment, high-pressure air required during water purging cycles can be temporarily stored and retrieved in a high-pressure air tank or tank assembly, which can either be submerged and proximate to the chambers  40  or on the platform. An optional high-pressure tank used to store compressed air between cycles can facilitate the storage and retrieval of high-pressure compressed air between water-purging cycles by providing a high-pressure air reservoir cushion or reserve. It can also store high-pressure air required to initialize the system and eliminate the need for the surface air pump and its associated high-pressure air line  50 . 
         [0025]    When the hydrostatic pressure in a chamber is reduced below the hydrostatic pressure at an intake  26 , opening a water control valve  54  at an inlet of a chamber  40 A or  40 B allows water to flow into an intake  26 , downward through the conduit  24 , through a turbine  32  and drive the generator  36  to generate electricity. Water will continue to drive the generator, filling the chamber  40 A or  40 B, reducing its volume and increasing hydrostatic pressure inside the chamber  40 A or  40 B until the hydrostatic pressure inside the chamber  40 A or  40 B equalizes relative to the hydrostatic pressure at the intake  26 . When the hydrostatic pressure inside a chamber reaches a level where water flow rate is insufficient to drive the generator  36 , the chamber  40  can be considered to be full. High pressure air in the second chamber  40 B or  40 A, (or from the aforementioned high-presure tank assembly) respectively, is thereafter routed from the second chamber  40 B or  40 A into the just-filled chamber  40 A or  40 B by the air exchanging compressor  90 . The second chamber  40 B or  40 A is thereafter pumped down or evacuated by the air exchanging compressor  90  to prepare the second chamber  40 B or  40 A to receive water that passes routed through the turbine  32  to drive the generator. 
         [0026]    As a system, the chambers  40 A and  40 B, water level detectors  56 , air-exchanging compressor  90 , control valves  54  and controlling computer  16  are designed and configured to cyclically and repeatedly purge chambers and allow chambers to fill with water. One chamber  40 A or  40 B is purged of water and high-pressure air, allowing the other chamber to be filled with water that flows through a turbine  32  to drive the generator to generate electricity  36 . While the chamber  40 A or  40 B is being filled, the other chamber  40 B or  40 A respectively is being purged of water using high pressure air. After the first chamber  40 A or  40 B is filled with water from a turbine, the system re-purges water from the first chamber while the second chamber begins to receive water from the turbine. The separate chambers  40 A and  40 B are repeatedly and cyclically filled with water from the intakes and emptied using compressed air. The chambers  40 A and  40 B are thus emptied by high pressure air that is re-used by shuttling the high-pressure air between the chambers after they&#39;re emptied. 
         [0027]      FIG. 2  illustrates a second embodiment of a system  2  for generating electric energy. The buoys  6  are shown using solid lines to better illustrate their location, when a platform  4  is used. 
         [0028]    The principal difference between the embodiment of  FIG. 1  and  FIG. 2  is the use of a single intake  26  at a much lower depth in the body of water. Another difference between  FIG. 1  and  FIG. 2  is the use of a “Y” connection that splits or divides water input to the single intake  26  into two relatively short water conduits  24 . 
         [0029]    Using a single intake  26  set deep in the water as shown in  FIG. 2 , increases the hydrostatic or head pressure at the intake  26  over what it would otherwise be at a shallower depth. Lowering the intake  26  also enables the water conduits  24  to be shortened, which reduces head loss. 
         [0030]      FIG. 3  illustrates a third embodiment of a system  3  for generating electric energy using hydrostatic water pressure differentials. Various aspects of the system  3  of  FIG. 3  can also be optionally used with the system  2  depicted in  FIG. 1  and/or  FIG. 2 . 
         [0031]    The embodiment shown in  FIG. 3  omits the platform  4  shown in  FIG. 1 , the wind-driven generator  18  and solar array  20 . The controlling computer  16  is also submerged and co-located with the water-tight reservoir  38 . 
         [0032]    As with the embodiment shown in  FIG. 2 , in  FIG. 3 , a single intake  26  is located close to the reservoir  38  and split into two separate, short water conduits  24 . The water intake  26  is preferably located less than a few inches above the turbines  32 . As with the embodiment shown in  FIG. 2 , shortening the water conduits  24  reduces the head loss that a long water conduit would cause, which increases water pressure on the turbine. 
         [0033]    The surface located air compressor  14 , which provides start-up air pressure, is located on shore  68 . High-pressure start-up air from the shore-located air compressor  14  is carried through a submerged high-pressure air line  50  that runs over the bottom  12  of the water body  8 . Electric power generated by the generator  36  is carried through a submerged cable  94  that runs over the bottom  12  of the water body  8  to the electric power grid  96 . An optional high-pressure air tank assembly  72  provides start-up air and can store compressed air between cycles. In an optional embodiment (not shown), a boat or barge that floats over the system ( 2  or  3 ) to provide start-up compressed air. 
         [0034]    Those of ordinary skill in the art will recognize that the systems described above and depicted in the figures requires an initial start up power to empty at least one of the chambers  40 A or  40 B initially. In the embodiment shown in  FIG. 1  and  FIG. 2 , system start-up or “initialization” power is preferably provided by renewable energy generated by the wind-driven generator  18  or the solar panels  20  described above. In the embodiment of  FIG. 2 , initialization power can be provided from the same sources located on shore or land  68  and carried to the submerged system  3  via submerged cable. 
         [0035]    Wind power is known to be unpredictable but can be generated with or without sunlight. Solar power is very predictable but is not available at night. The systems depicted in the figures store wind generated and/or solar generated power in a battery array (not shown) until it is needed for the system&#39;s initialization. 
         [0036]    Once the start up power has been provided to the systems  2  and  3  and hydrostatic water pressure is driving the generator  36 , the systems  2  and  3  can generate electric power, regardless of whether the wind is blowing or the sun is shining. The systems  2  and  3  can therefore advantageously generate electric power when other renewable energy sources might not be able, such as at night when the wind also frequently stops blowing. 
         [0037]    Those of ordinary skill in the art will recognize that the efficacy of the systems in each of the figures will depend on several factors that include but which are not limited to water depth, chamber volumes, water conduit head losses and turbine efficiency. The systems can nevertheless work in any body of water, but their efficacy, including output power, will be determined by the aforementioned factors. 
         [0038]    The descriptions set forth above are for purposes of illustration. Those of ordinary skill will recognize that while the systems depicted in the figures use two intakes  24 , two conduits  26  and two turbines  44  that drive a single generator  46 , equivalent alternate embodiments usesa single intake  24 , a single conduit  26 , one turbine and one generator  46  with turbine effluent being selectably and alternately routed to a first chamber  40 A or  40 B and then to the other chamber  40 B or  40 A using one or more computer-controlled valves, not shown but well known to those ordinary skill. Another alternate embodiment uses a single, short conduit  26 , such as the ones shown in  FIG. 2  and  FIG. 3 , routing water to two or more separate turbines, each of which is coupled to one or more generators. 
         [0039]    The foregoing description is for purposes of illustration and not for limiting or defining the invention. The invention and its scope is defined by the appurtenant claims.