Abstract:
Methods and Systems are provided for generating electric power. One method includes the steps of: (a) submerging a housing into a body of water, the housing defining a chamber therein; (b) maintaining the chamber at a pressure lower than the pressure exerted by the body of water on the housing; (c) admitting water from the body of water into the chamber, and driving a turbine with the water flowing into the chamber to generate electric power; (d) discharging water from the chamber into the body of water; and (e) sequentially repeating steps (c) and (d).

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority from the following provisional patent applications, all of which are incorporated by reference herein: (1) U.S. Provisional Patent Application Ser. No. 61/060,462, filed on Jun. 10, 2008, entitled Active Hydroelectric Power Device, (2) U.S. Provisional Patent Application Ser. No. 61/087,812, filed on Aug. 11, 2008, entitled Active Hydroelectric Power System With CO 2  Recycling, and (3) U.S. Provisional Patent Application Ser. No. 61/144,565, filed on Jan. 14, 2009, entitled Deep Sea Carbon Dioxide Sequestration Device. 
     
    
     BACKGROUND 
       [0002]    The present application relates to methods and systems for generating electrical power and, more particularly, to hydroelectric power plants and methods of operating such plants. 
         [0003]    Hydroelectric power generation is a very efficient and prevalent source of “green” (i.e., clean) energy. Hydropower represents about 20% of the world&#39;s electricity production with conversion efficiency rates that exceed 80% compared with fossil fuel facilities, which often operate in the 33% range. Hydroelectric power is an inexpensive way to produce electricity (averaging less than 1 cent per kWh for operations and maintenance) largely because generally no fuel is consumed in the process. This contrasts with nuclear and other thermal processes, which are more costly and deplete valuable resources. Hydroelectric power is also valued as a renewable green energy source since its production does not require the extraction and consumption of any scarce natural resource. Hydropower still represents 75% of the renewable energy produced in the U.S. though other methods such as wind power and solar energy appear to receive greater attention in governmental and industrial programs. Part of the enduring appeal of hydropower rests with its virtually emissions-free production process, its ability to provide both base level and peaking production capacity, its ability to facilitate electrical load balancing, and its ability to store potential electricity in reservoirs for use during the most demanding and lucrative time periods. Hydropower plants have been scaled in size from relatively small sizes such as 10 kW to massive installations as large as 20,000 mW. In recent years, the development of new hydroelectric sites has stalled, particularly in the U.S. Several factors have contributed to this including the previous exploitation of many of the high potential sites, growing environmental concerns regarding the ecological “footprint” of large dam/impoundment complexes, and the relatively high capital costs of new large projects. Environmental concerns with dam/impoundment projects include: loss of habitat from inundation, displacement of indigenous peoples, health concerns in developing countries, disruption of fish migration routes, and oxygen depletion in the dammed rivers. The environmental concerns combined with the high engineering costs, onerous regulatory filing procedures, long lead times, and relatively high capital costs for new construction have inhibited the development of new hydro projects, particularly in the U.S. Even though only 3% of existing U.S. dams have hydroelectric facilities, there is still not much momentum in favor of aggressive exploitation of this potential “green” energy source. Additionally, as water resources become more valuable and greater demands are placed upon the great river systems for conflicting needs such as industrial development, agricultural irrigation, and growing household consumption, hydroelectric use of the limited water resource, though non consumptive, often takes a back seat in timing and actual production to other important societal concerns. 
       BRIEF SUMMARY OF EMBODIMENTS OF THE INVENTION 
       [0004]    A power generation system in accordance with one or more embodiments includes: a housing defining a chamber therein, the housing being submersible into a body of water; a water intake valve in the housing for admitting water from the body of water into the chamber; a turbine in the housing, the turbine driven by water flowing through the intake valve into the chamber for generating electric power; a conduit coupled to the housing for placing the chamber in communication with the atmosphere for maintaining the chamber at a pressure lower than the pressure exerted by the body of water on the housing; a water outlet valve in the housing for discharging water from the chamber into the body of water; a gas inlet valve in the housing for receiving a compressed gas into the chamber from a source of compressed gas, the compressed gas evacuating water in the chamber into the body of water through the outlet valve as the compressed gas is introduced into the chamber; and a gas outlet valve for evacuating compressed gas in the chamber into the body of water through the gas outlet valve as water is introduced into the chamber from the water intake valve. 
         [0005]    A combination power generation system and deep water cooling system in accordance with one or more embodiments includes: a housing defining a chamber therein, the housing being submersible into a body of water; a water intake valve in the housing for admitting water from the body of water into the chamber; a turbine in the housing, the turbine driven by water flowing through the intake valve into the chamber for generating electric power; a conduit coupled to the housing for placing the chamber in communication with the atmosphere for maintaining the chamber at a pressure lower than the pressure exerted by the body of water on the housing; and a water intake unit for evacuating water from the chamber, and transferring the water to a given location. 
         [0006]    A power generation system in accordance with one or more embodiments includes: a housing defining a chamber therein, the housing being submersible into a body of water; a water intake valve in the housing for admitting water from the body of water into the chamber; a turbine in the housing, the turbine driven by water flowing through the intake valve into the chamber for generating electric power; a conduit coupled to the housing for placing the chamber in communication with the atmosphere for maintaining the chamber at a pressure lower than the pressure exerted by the body of water on the housing; and an electrolysis unit for evacuating water from the chamber by converting the water into hydrogen and oxygen gases, and discharging the hydrogen and oxygen gases from the chamber. 
         [0007]    A method for generating power in accordance with one or more embodiments includes the steps of: (a) submerging a housing into a body of water, the housing defining a chamber therein; (b) maintaining the chamber at a pressure lower than the pressure exerted by the body of water on the housing; (c) admitting water from the body of water into the chamber, and driving a turbine with the water flowing into the chamber to generate electric power; (d) discharging water from the chamber into the body of water; and (e) sequentially repeating steps (c) and (d). 
         [0008]    A power generation system in accordance with one or more embodiments includes: a power generation unit submersible into a body of water, the power generation unit including a housing defining at least one chamber therein, the power generation unit further including one or more turbines for generating electric power; a platform adapted to float on the surface of the body of water, the platform including a heater for heating water from the body of water; an evaporator or vacuum pump assisted regulating unit; a plurality of conduits coupling the platform and the power generation unit, the plurality of conduits including a water conduit, a steam conduit, and an air supply conduit; wherein heated water from the platform flows through the water conduit to the power generation unit to drive the one or more turbines for generating electric power, the water thereafter flowing to a hot water chamber in the housing; wherein the evaporator or vacuum pump assisted regulating unit facilitates evaporation of the water in the hot water chamber into steam that is drawn out of the power generation unit through the steam conduit. 
         [0009]    A method for generating power in accordance with one or more embodiments includes the steps of: (a) submerging a housing into a body of water, the housing defining a chamber therein; (b) maintaining the chamber at a pressure lower than the pressure exerted by the body of water on the housing; (c) heating water from the body of water into heated water; (d) dropping the heated water into the chamber, and driving one or more turbines with the water flowing into the chamber to generate electric power; (e) evaporating the heated water into steam and transferring the steam out of the housing; and (f) sequentially repeating steps (c), (d), and (e). 
         [0010]    Various embodiments of the invention are provided in the following detailed description. As will be realized, the invention is capable of other and different embodiments, and its several details may be capable of modifications in various respects, all without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not in a restrictive or limiting sense, with the scope of the application being indicated in the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1A  is a cross-section view of a submersible power generation unit in accordance with one or more embodiments of the invention shown in one state of operation. 
           [0012]      FIG. 1B  is a cross-section view of the submersible power unit of  FIG. 1A  shown in another state of operation. 
           [0013]      FIG. 2A  is a perspective view of a known water intake unit of a deep lake water cooling system. 
           [0014]      FIG. 2B  is a cross-section view of a submersible power generation unit in accordance with one or more embodiments of the invention that can be implemented in the intake unit of the deep lake water cooling system illustrated in  FIG. 2A . 
           [0015]      FIG. 2C  is a cross-section view of an alternate submersible power generation unit in accordance with one or more embodiments of the invention that can be implemented in the intake unit of the deep lake water cooling system illustrated in  FIG. 2A . 
           [0016]      FIG. 3  is a cross-section view of a submersible power generation unit in accordance with one or more further embodiments of the invention. 
           [0017]      FIG. 4  is a cross-section view of a power generation system in accordance with one or more further embodiments of the invention. 
       
    
    
       [0018]    Like reference characters denote like parts in the drawings. 
       DETAILED DESCRIPTION 
       [0019]      FIGS. 1A and 1B  illustrate a combined power generation and gas sequestration unit  10  in accordance with one or more embodiments of the invention.  FIGS. 1A and 1B  illustrate the unit  10  in two states of operation, as will be described in further detail below. The unit  10  includes a housing  12  comprising a sealed vessel submerged in a body of water  13  such as a lake or ocean. The housing  12  defines a chamber therein, which preferably includes one or more upper compartments and one or more lower compartments. In the embodiment illustrated in  FIGS. 1A and 1B , there is one upper compartment  14  and two lower compartments  16 ,  18 . In addition, the housing  12  defines a compartment  19  having one or more turbines  20  therein. Water is admitted from the body of water  13  into the housing  12  into the compartment  19  at the high ambient pressure in the body of water  13 . The water passes through and drives the one or more turbines  20  in a conventional hydroelectric power generating cycle. The upper compartment  14  of the unit  10  is in communication with the outer atmosphere through an air conduit  22  and thereby maintains a generally constant pressure of about one atmosphere (14.7 psi). Water that has flowed through the turbines  20  (i.e., “spent” water) thereby falls by gravity into the upper compartment  14  of the unit  10 . 
         [0020]    The spent water is discharged from upper compartment  14  through the sequential opening and closing of one-way pressure valves  24  in the upper compartment floor permitting the spent water to fall into the lower compartments  16 ,  18 . The spent water fills the lower compartments  16 ,  18 , and is subsequently evacuated from the lower compartments  16 ,  18  by introducing a high-pressure carbon dioxide gas into the lower compartments  16 , 18  to force the spent water out of the housing  12  and into the body of water  13 . The lower compartments  16 ,  18  are alternatingly filled with the spent water received from the upper compartment  14  and then emptied of the spent water. Water can thereby continue to flow from the body of water  13  into the upper compartment  14  and drive the turbine  20  to generate electricity. 
         [0021]    The housing  12  is submerged in the body of water  13 , preferably at a depth greater than 2800 feet. The housing  12  accordingly comprises a structure that can withstand high-pressure and corrosive conditions found in a deepwater environment. The housing  12  preferably has the general shape of a sphere, an ovoid, or a cylinder, and comprises materials and wall thicknesses suitable for use in deepwater environments, as is well known in the ocean oil drilling industry. In some cases it may be possible to use inexpensive plastic materials including HDPE (high density polyethylene) materials, particularly for units submerged at shallower depths. The housing  12  can be secured to the floor of the body of water  13 , e.g., by being tethered or anchored to the floor. The housing  12  can be supported on the floor using adjustable support legs  26 . 
         [0022]    The housing  12  includes one or more water intake valves  28 . When the intake valves  28  are opened, water from the body of water  13  is admitted into the housing. A screen  30  is preferably provided around the intake valves to filter out indigenous aquatic material and inhibit it from being ingested into the unit  10  via the vortex of water at the intake valves  28 . 
         [0023]    The water is conveyed down one or more penstocks  32  into the turbine  20  by the high ambient pressure of the deep water environment. The high-pressure water drives and spins the turbine  20 , converting the deep water&#39;s potential energy into kinetic energy. The spinning elements of the turbine  20  are connected by a shaft to a generator that converts the kinetic energy into electricity via induction as is known in the art. By way of non-limiting example, the turbine  20  can comprise a Pelton wheel system, which at high hydraulic heads, is known to operate at particularly high efficiencies. 
         [0024]    Once the water has passed through the turbine  20 , it is conveyed by gravity through generator effluent conduits  34  and gravity intake check valves  36  into the upper compartment  14  of the housing  12 . As discussed above, the upper compartment  14  of the housing  12  is in communication with the outer atmosphere through an air conduit  22  in a main conduit  38 , and accordingly maintains a pressure of about 14.7 psi or one atmosphere. The spent water accordingly flows into the lower-pressure upper chamber  14  and becomes trapped in the chamber  14  by the one-way gravity check valves  24 . The check valves  24  are then opened from time to time to transfer the water from the upper compartment  14  to the lower compartments  16 ,  18  as discussed below. The electricity generated by the turbine  20  is transmitted from the housing  12  via the electrical lines  40  in the main conduit  38  to a location where it can be used by the outside world. 
         [0025]    In accordance with one or more embodiments, the spent water is evacuated from the lower compartments  16 ,  18  into the body of water  13  using highly compressed carbon dioxide gas to force the water out of the housing  12 . This expulsion process is similar to the process a submarine uses to “blow” its main ballast tank with highly-compressed air in order to allow the submarine to ascend to the water&#39;s surface. 
         [0026]    The carbon dioxide gas is then also expelled into the body of water  13 , thereby sequestering the carbon dioxide, which is a known greenhouse gas pollutant. The system thereby makes a synergistic connection between the need to reduce greenhouse gas pollution and provide a new source of cleanly generated electricity. It has been found when carbon dioxide is expelled at depths greater than roughly 2800 feet, the carbon dioxide gas changes into a hydrate, which generally stays pooled at the bottom of the body of water  13  rather than returning to the surface as a gas to pollute the atmosphere. 
         [0027]      FIGS. 1A and 1B  illustrate the two states of operation in which the carbon dioxide and spent water are alternatingly expelled from the lower compartments  16 ,  18  of the housing. As shown, the lower compartments  16 ,  18  each include an expandable bladder  42 , which separates the spent water from the carbon dioxide. In the state shown in  FIG. 1 , the lower left compartment  16  is substantially filled with spent water, and the bladder  42  is substantially flattened. In the lower right compartment  18 , however, the bladder  42  has been inflated with carbon dioxide, forcing the spent water out of the housing  12 .  FIG. 1B  illustrates a subsequent state of operation in which, in the lower left compartment  16 , the bladder  42  has been inflated with carbon dioxide to force out the spent water, and in the lower right compartment  18 , spent water has been admitted and substantially flattens the bladder  42 . The process is repeated such that spent water is alternatingly admitted and expelled from the lower compartments  16 ,  18 . 
         [0028]    As discussed above, the upper compartment  14  is maintained at a pressure of about 14.7 psi using the air conduit  22  at valve opening  44 . Spent water in the upper compartment  14  moves via gravity through one-way pressure check valve  24  into the lower compartments  16 ,  18 . Pressure in the lower compartments  16 ,  18  need not be at 14.7 psi, but should be conducive to the entry of water by gravity from the upper compartment in order to permit continuous operation. Once a lower compartment  16 ,  18  is substantially filled with water, high pressure carbon dioxide gas is introduced from inlet valve  45  into bladder  42 , thereby inflating the bladder under great pressure and forcing the spent water out of the housing via valves  46  and into the body of water  13 . Once a lower compartment is vacated of the spent water, new spent water can be admitted via valve  24 . 
         [0029]    The weight of the spent water entering from the upper compartment  14  will flatten the bladder  42 , thereby substantially forcing residual carbon dioxide left in the bladder  42  out of the housing  12  via valves  23 . The unit  10  includes one or more monitoring sensors  48  to monitor the pressure in lower compartment  16 ,  18  such that appropriate thermodynamic conditions can be maintained to permit water flow through the lower compartments  16 ,  18 . In the event that the monitoring sensors  48  detect carbon dioxide residue in the bladder  42  sufficient to inhibit flow from the upper compartment  14 , an electronic control unit  52  coupled to the sensors  48  can actuate the introduction of auxiliary high pressure compressed air into the lower compartment  16 ,  18  from valve  50  to clear the compartment. Any residual compressed air can be purged into the 14.7 psi air conduit  22  and out into the external environment. 
         [0030]    Operation of the power generation unit  10 , including control of the valves to admit and expel water in the compartments, can be controlled using the electronic control unit  52  in the housing  12 . An additional redundant electronic control unit  54  can be provided in the event the primary control unit  52  fails. 
         [0031]    The main conduit  38  can comprise a rigid or flexible tube depending on the water pressures involved. The main conduit  38  can extend vertically from the housing  12  or extend laterally to a land location along the floor of the body of water  13 . 
         [0032]    The compressed carbon dioxide gas is provided to the power generation unit  10  via a carbon dioxide supply conduit  56  in the main conduit  38  from a remote carbon dioxide source. The compressed air used for clearing residual carbon dioxide gas can be produced on site at the power generation unit  10  using an air compressor, or alternately can be received from a remote compressed air source. 
         [0033]    In accordance with one or more embodiments, the power generation unit  10  may be raised to the water surface level for maintenance or refurbishing, as needed. Techniques for raising the unit  10  include connecting the unit with the cable to mechanically lift the unit  10  and using gas-induced buoyancy to raise the unit  10 . 
         [0034]    In accordance with one or more further embodiments of the invention, a power generation unit is provided that may be implemented with the intake unit of a deep water cooling system. Such systems have been used to pump cold water from a deep location in a lake or ocean to a land location where it can be used for cooling purposes. Examples of such systems are Cornell University&#39;s deep lake cooling system and the NELHA deep ocean pipeline. 
         [0035]      FIG. 2A  illustrates an exemplary intake unit  102  of a deep water cooling system. The intake unit includes an outer screen  104  and an inner cover  106 , both positioned on a platform  108  for covering a water intake pipe opening  110 . Water is drawn from the lake or ocean through the intake pipe opening  110 , and pumped to a location where it can be used via pipe  112 . 
         [0036]      FIG. 2B  illustrates a power generation unit  100  that is configured to be implemented in the intake unit of a deep water cooling system such as the unit  102  illustrated in  FIG. 2A . In the  FIG. 2A  exemplary intake unit  102 , the outer screen  104 , the inner cover  106 , and the platform  108 , are removed to expose the water intake pipe opening  110 . The water intake pipe opening  110  is incorporated in the power generation unit  100  depicted in  FIG. 2B  for the purpose of evacuating spent water from the unit  100 . 
         [0037]    The unit  100  illustrated in  FIG. 2B  includes an upper compartment  114  and a lower compartment  116 . In addition, the unit  100  includes a compartment  118  having one or more turbines  20 . Water is admitted from the body of water  13  into the housing  120  into the compartment  118  at the high ambient pressure in the body of water  13 . The water passes through and drives one or more turbines  20  in a conventional hydroelectric power generating cycle. The upper compartment  114  of the unit  100  is in communication with the outer atmosphere through an air conduit  22  and thereby maintains a generally constant pressure of about one atmosphere (14.7 psi). The water that has flowed through the turbine  20  (i.e., “spent” water) thereby falls by gravity into the upper compartment  114  of the unit  100 . The spent water is discharged from upper compartment  114  through the one-way pressure valves  24  in the upper compartment floor permitting the spent water to fall into the lower compartment  116 . The spent water fills the lower compartment  116 , and is subsequently evacuated from the lower compartment  116  by the water intake pipe  112  of the deep water cooling system. 
         [0038]    The attachment of the power generation unit  100  to the intake of a preexisting deep water cooling system offers the opportunity to partially defray the cost of the system through the production of electricity. The unit  100  operates similarly to the unit  10  shown in  FIGS. 1A and 1B . 
         [0039]      FIG. 2C  illustrates a power generation unit  150  in accordance with one or more alternate embodiments of the invention. The power generation unit  150  is similar to the power generation unit  100  shown in  FIG. 2B . In the unit  150 , the spent water that has flowed through the turbine  20  and drawn by the pipe  112  to a land location is recirculated and returned to the unit  150  by a return pipe  120 . Additional water can be drawn into the unit as needed to account for any water losses in transportation of the water. Recirculating the spent water reduces environmental impact on the body of water  13 . 
         [0040]      FIG. 3  illustrates a power generation unit  200  in accordance with one or more further embodiments of the invention. The unit  200  includes a housing  201  having an upper compartment  114  and a lower compartment  204 . In addition, the unit  200  includes a compartment  118  having one or more turbines  20 . Water is admitted from the body of water  13  into the housing  201  into the compartment  118  at the high ambient pressure in the body of water  13 . The water passes through and drives one or more turbines  20  in a conventional hydroelectric power generating cycle. The upper compartment  114  of the unit  200  is in communication with the outer atmosphere through an air conduit  22  and thereby maintains a generally constant pressure of about one atmosphere (14.7 psi). The water that has flowed through the turbine  20  (i.e., “spent” water) thereby falls by gravity into the upper compartment  114  of the unit  200 . The spent water is discharged from upper compartment  114  through the one-way pressure valves  24  in the upper compartment floor permitting the spent water to fall into the lower compartment  204 . The unit  200  discharges spent water through electrolysis. In particular, electrolysis is used to separate the water into its elemental parts: oxygen and water. 
         [0041]    The power generation unit  200  includes an electrolysis unit  202  in a lower compartment  204  for converting the spent water in the lower compartment  204  into hydrogen and oxygen. Once this conversion has been accomplished (preferably at least partially using electricity created locally by the turbine  20 ), the elemental parts, hydrogen and oxygen, are bubbled into deep-water high pressure storage containers  206  and  208 , respectively, attached to the housing via valves  210 . Once created, the hydrogen and oxygen may be packaged for sale off-site or converted into useful products such as ammonia through further processing. 
         [0042]    By way of non-limiting example, the electrolysis unit  202  includes a homopolar generating device rather than a more typical generator. The homopolar generator or Faraday disk is particularly well-adapted to situations of water electrolysis since it creates more suitable conditions for large-scale production, namely enormous amperage at nominal voltage. In this case, it is the amperage that determines how much water can be cracked so the large amperage afforded by the homopolar system is well suited for this purpose. 
         [0043]    In accordance with one or more embodiments, an on-site ammonia production unit is optionally included in the housing to generate ammonia from the hydrogen using nitrogen filtered from the surrounding air. Some of the electricity produced by the unit  200  can be used to support the energy needs of the ammonia production process. As ammonia has been shown to be very economically useful as the primary component of fertilizer and even as a “green” fuel for vehicles that burns without noxious effluent, making it generally continuously in a non-polluting green fashion is particularly advantageous. 
         [0044]      FIG. 4  illustrates a power generation system  300  in accordance with one or more further embodiments of the invention. The system  300  includes a platform  302 , which floats at the surface  304  of the body of water  13 , and a power generation unit  306 , which is submerged at a given depth in the body of water  13 . The platform  302  and the power generation unit  306  are connected by a main conduit  308 . 
         [0045]    The platform  302  includes a solar thermal device  310  for heating water. Water is collected at the surface  304  of the body of water  13  and processed through the solar thermal device  310 . By way of non-limiting example, the solar thermal device  304  can be a solar parabolic reflector. Once heated, water is allowed to pass by gravity through a sensor valve  306 , where it is permitted to flow through only when heated to a desired temperature, which can be approximately 212° F. In some embodiments, higher temperatures can be used if the water stays in a liquid state and is not converted to steam (e.g., superheated water). While still in the liquid state, the water is allowed to drop through conduit  312  located inside of the main conduit  308 . The conduit  312  is preferably insulated to reduce thermal losses. 
         [0046]    The water flowing through the conduit  312  flows to one or more turbines  20  in a compartment  314  in the unit  306 . Once the force of the water&#39;s mass has spun the turbine and contributed its kinetic energy to the production of electricity, the still hot water is allowed to fall by gravity into an upper chamber  316  through a gravity check valve  318 . The hot water continues to fall by gravity through pressure check valve  320  into the hot water collection sump  322  in a lower compartment  324  of the unit  306 . 
         [0047]    At the same time water at a cold deep water temperature is admitted into the unit  306  through the penstock valve  28 . The cold water passes through and drives one or more turbines  20 . The “spent” cold water falls by gravity to an upper chamber  316  through a gravity check valve  328 . The cold water continues to fall by gravity through a pressure check valve  330  into a lower compartment  328  of the unit  306 . In some embodiments, the spent cold water can be expelled from the chamber  328  back into the body of water  13  using any of the evacuation techniques described herein. In other embodiments as described below, some or all of the cold water is mixed with the water heated by the solar thermal device, and subsequently evaporated and evacuated from the housing. 
         [0048]    The hot water in the hot water collection sump  322  of chamber  324  and the cold water in chamber  328  are allowed to flow into a steam/water mixing valve  332  where a suitable amount of the cold water is mixed with the hot water to achieve a controlled temperature between approximately 165° F. and 212° F. Using known evaporation techniques, the hot water is permitted to evaporate up through a conduit  342  in the main conduit  308 . The flow of the steam through the conduit  342  may be assisted by a vacuum pump-assisted regulating unit  344 , which lowers the pressure at the upper outlet of the conduit  342  and provides the thermodynamic impetus for the hot water to evaporate and move up the conduit  342  via the “stack” effect. Alternatively, an evaporator can be used to evaporate the hot water. A heat exchange and condensation chamber  346  condenses the vapor and the high heat content of the vapor is transferred through a proximal heat exchange process to input water from the body of water  13 , which is fed to the solar thermal device  310 . With the structure, a significant portion, e.g., 75% of the heat previously added is conserved for use in the next hot water to vapor cycle. Once condensed, the vapor comprises distilled water. The distilled water can be conveyed in a conduit  348  to distilled water tank  350 . From the storage tank  350 , the water may be exported for outside consumption purposes including drinking, irrigation etc. 
         [0049]    In the case of saline water or particularly mineral-rich fresh water, a blow down cycle can be used from the tank at the bottom of the hot water collection sump  322 . The resulting mineral-rich blow down effluent is collected in a blow down tank  352  and transferred via conduit  354  to valve  356  from which it is directed under a bladder  42 . The weight of the incoming water atop the bladder  42  expels the blow down effluent into the surrounding aqueous environment  13  via a pressure check valve  358 . If additional force is needed to expel the effluent, highly compressed air may be added through air compressor  360  attached to compressed air conduit  362 . 
         [0050]    In some embodiments, a combination of evacuation techniques to discharge spent water from the power generation units can be used. For example, a power generation unit can include any combination of the water expulsion techniques described herein. 
         [0051]    It is to be understood that although the invention has been described above in terms of particular embodiments, the foregoing embodiments are provided as illustrative only, and do not limit or define the scope of the invention. Various other embodiments, including but not limited to the following, are also within the scope of the claims. For example, elements and components described herein may be further divided into additional components or joined together to form fewer components for performing the same functions. 
         [0052]    Having described preferred embodiments of the present invention, it should be apparent that modifications can be made without departing from the spirit and scope of the invention. 
         [0053]    Method claims set forth below having steps that are numbered or designated by letters should not be considered to be necessarily limited to the particular order in which the steps are recited.