Abstract:
A power systems utilizing at least two heat source streams with substantially different initial temperatures, where the systems include a simple vaporization, separation, and energy extraction subsystem, a recycle subsystem, and a condensation and pressurization subsystem and methods for making and using same.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    Embodiments of the present invention relate to power systems utilizing at least two heat source streams with substantially different initial temperatures, and to methods for making and using same. 
         [0003]    More particularly, embodiments of the present invention relate to power systems utilizing at least two heat source streams with substantially different initial temperatures, where the systems include a simple vaporization, separation, and energy extraction subsystem, a recycle subsystem, and a condensation and pressurization subsystem. The present invention also relates to methods for making and using same. 
         [0004]    2. Description of the Related Art 
         [0005]    In geothermal applications, it is common for several initial wells to be drilled before a production well having an adequately high source temperature is located within a geothermal field. These initial wells deliver geothermal streams having temperatures lower than that of a well that will eventually be used as the production well. The drilling of these initial wells, which are then not utilized for energy extraction, is considered to be an inevitable part of the geothermal field cost. 
         [0006]    Thus, there is a need in the art for power generation systems that are capable of utilizing streams derived from initial and production wells. 
       SUMMARY OF THE INVENTION 
       [0007]    Embodiments of this invention relate to systems for generating power from at least one lower temperature heat source stream from at least one initial geothermal well and at least one higher temperature heat source stream from at least one production geothermal well. The system comprises a vaporization subsystem. The vaporization subsystem includes a booster pump to increase a pressure of an intermediate pressure rich solution stream forming a higher pressure rich solution stream. The vaporization subsystem also includes a lower temperature heat exchange portion to partially vaporize the higher pressure rich solution stream using a combined heat source stream comprising a cooled higher temperature heat source stream and a lower temperature heat source stream. The vaporization subsystem also includes a higher temperature heat exchange portion to further vaporize the higher pressure rich solution stream. The vaporization subsystem also includes a first separator to separate the further vaporized higher pressure rich solution stream into a higher pressure lean liquid stream and a higher pressure vapor richer solution stream. The system also comprises an energy extraction subsystem. The energy extraction subsystem includes at least one turbine to convert a portion of thermal energy in the higher pressure vapor richer solution stream into a usable form of energy forming a lower pressure richer solution stream. The system also comprises a separation and pressure reduction subsystem. The separation and pressure reduction subsystem includes a first throttle control valve to reduce a pressure of the higher pressure lean liquid stream to form an intermediate vapor-liquid lean stream. The separation and pressure reduction subsystem also includes a second separator to separate the intermediate vapor-liquid lean stream into an intermediate pressure rich vapor stream and an intermediate pressure leaner liquid stream. The separation and pressure reduction subsystem includes a first mixing valve to combine the intermediated pressure lean solution stream and the intermediate pressure rich vapor stream forming the intermediated pressure rich solution stream. The separation and pressure reduction subsystem includes a second throttle control valve to reduce the pressure of the intermediate pressure leaner liquid stream forming a lower pressure leaner liquid stream. The separation and pressure reduction subsystem includes a second mixing valve to combine the lower pressure leaner liquid stream and the lower pressure richer solution stream. The system also comprises a condensation subsystem including a condenser to fully condense a lower pressure lean solution stream forming the lower pressure fully condensed lean solution stream. The systems utilize streams comprising a multi-component working fluid. In certain embodiments, the multi-component working fluid at least one lower boiling point component and at least one higher boiling point component. In other embodiments, the multi-component fluid is selected from the group consisting of a ammonia-water mixture, a mixture of two or more hydrocarbons, a mixture of two or more freon, a mixture of hydrocarbons and freons, and mixtures thereof. In other embodiments, the multi-component fluid comprises a mixture of compounds having favorable thermodynamic characteristics and solubilities. In other embodiments, the multi-component fluid comprises a mixture of water and ammonia. In other embodiments, a flow rate of the higher temperature heat source stream is substantially lower than a flow rate of the lower temperature heat source stream. In other embodiments, the flow rate of the higher temperature heat source stream is as low as 25% of the flow rate of the lower temperature heat source stream. In other embodiments, the higher temperature heat source stream is adjusted so that the flow rate is sufficient to provide as much heat as is required in the third heat exchange process. In other embodiments, if the flow rate of the higher temperature heat source stream is too small to provide the required heat for the third heat exchange process, then a temperature of the higher pressure partially vaporized rich solution stream is reduced so as to provide a balance between the heating process and the cooling process of the third heat exchange process. In other embodiments, if the flow rate of the higher temperature heat source stream is too small to provide the required heat for the third heat exchange process, then a temperature difference between a temperature of the lower temperature heat source stream and a temperature of the higher pressure rich solution stream at the point within the second heat exchanger is increased so that the utilization of available heat from the lower temperature heat source stream is reduced. In other embodiments, a total power output of the systems is reduced. In other embodiments, the heat source streams are varied to optimize a power output of the system. In other embodiments, the temperature differences between the heat source streams and the working fluid streams in the second heat exchange unit and the third heat exchange unit are substantially reduced as compared to a system using only the higher temperature heat source stream. In other embodiments, a thermodynamic irreversibility of heat transfer from the heat source streams to the working fluid streams is substantially reduced in the system and the system has a substantially higher 2nd Law efficiency as compared to a system that utilizes only the higher temperature heat source stream. In other embodiments, a thermal efficiency of the system remains as high as a system using only the higher temperature heat source stream. In other embodiments, a total power produced in the system is substantially higher than a system using a mixture of higher temperature source stream and lower temperature heat source stream. In other embodiments, the lower temperature heat source stream comprises initial wells drilled into a geothermal field and the higher temperature heat source stream comprises production wells in the geothermal field. 
         [0008]    Embodiments of this invention relate to methods for generating power from at least one lower temperature heat source stream from at least one initial geothermal well and at least one higher temperature heat source stream from at least one production geothermal well. The methods for power generation comprises increasing a pressure of an intermediate pressure rich solution stream forming a higher pressure rich solution stream in a booster pump of a vaporization subsystem, partially vaporizing the higher pressure rich solution stream using a combined heat source stream comprising a cooled higher temperature heat source stream and a lower temperature heat source stream in a lower temperature heat exchange portion of the vaporization subsystem, further vaporizing the higher pressure rich solution stream in a higher temperature heat exchange portion of the vaporization subsystem, and separating the further vaporized higher pressure rich solution stream into a higher pressure lean liquid stream and a higher pressure vapor richer solution stream in a first separator. The methods also include converting a portion of thermal energy in the higher pressure vapor richer solution stream into a usable form of energy forming a lower pressure richer solution stream in at least one turbine of an energy extraction subsystem. The methods also comprise reducing a pressure of the higher pressure lean liquid stream to form an intermediate vapor-liquid lean stream in a first throttle control valve of a separation and pressure reduction subsystem, separating the intermediate vapor-liquid lean stream into an intermediate pressure rich vapor stream and an intermediate pressure leaner liquid stream in a second separator of the separation and pressure reduction subsystem, combining the intermediated pressure lean solution stream and the intermediate pressure rich vapor stream forming the intermediated pressure rich solution stream in a first mixing valve of the separation and pressure reduction subsystem, reducing the pressure of the intermediate pressure leaner liquid stream forming a lower pressure leaner liquid stream in a second throttle control valve of the separation and pressure reduction subsystem, and combining the lower pressure leaner liquid stream and the lower pressure richer solution stream a second mixing valve of the separation and pressure reduction subsystem. The methods also comprise fully condensing a lower pressure lean solution stream forming the lower pressure fully condensed lean solution stream in a condenser of a condensation subsystem. The methods utilize a multi-component working fluid. In certain embodiments, the multi-component working fluid at least one lower boiling point component and at least one higher boiling point component. In other embodiments, the multi-component fluid is selected from the group consisting of a ammonia-water mixture, a mixture of two or more hydrocarbons, a mixture of two or more freon, a mixture of hydrocarbons and freons, and mixtures thereof. In other embodiments, the multi-component fluid comprises a mixture of compounds having favorable thermodynamic characteristics and solubilities. In other embodiments, the multi-component fluid comprises a mixture of water and ammonia. In other embodiments, a flow rate of the higher temperature heat source stream is substantially lower than a flow rate of the lower temperature heat source stream. In other embodiments, the flow rate of the higher temperature heat source stream is as low as 25% of the flow rate of the lower temperature heat source stream. In other embodiments, the higher temperature heat source stream is adjusted so that the flow rate is sufficient to provide as much heat as is required in the third heat exchange process. In other embodiments, if the flow rate of the higher temperature heat source stream is too small to provide the required heat for the third heat exchange process, then a temperature of the higher pressure partially vaporized rich solution stream is reduced so as to provide a balance between the heating process and the cooling process of the third heat exchange process. In other embodiments, if the flow rate of the higher temperature heat source stream is too small to provide the required heat for the third heat exchange process, then a temperature difference between a temperature of the lower temperature heat source stream and a temperature of the higher pressure rich solution stream at the point within the second heat exchanger is increased so that the utilization of available heat from the lower temperature heat source stream is reduced. In other embodiments, a total power output of the systems is reduced. In other embodiments, the heat source streams are varied to optimize a power output of the system. In other embodiments, the temperature differences between the heat source streams and the working fluid streams in the second heat exchange unit and the third heat exchange unit are substantially reduced as compared to a system using only the higher temperature heat source stream. In other embodiments, a thermodynamic irreversibility of heat transfer from the heat source streams to the working fluid streams is substantially reduced in the system and the system has a substantially higher 2nd Law efficiency as compared to a system that utilizes only the higher temperature heat source stream. In other embodiments, a thermal efficiency of the system remains as high as a system using only the higher temperature heat source stream. In other embodiments, a total power produced in the system is substantially higher than a system using a mixture of higher temperature source stream and lower temperature heat source stream. In other embodiments, the lower temperature heat source stream comprises initial wells drilled into a geothermal field and the higher temperature heat source stream comprises production wells in the geothermal field. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The invention can be better understood with reference to the following detailed description together with the appended illustrative drawings in which like elements are numbered the same: 
           [0010]      FIG. 1  depicts an embodiment of a power system for extracting energy from a production geothermal well and at least one initial geothermal well. 
           [0011]      FIG. 2  depicts a geothermal field including two production wells and two initial wells. 
       
    
    
     DEFINITIONS USED IN THE INVENTION 
       [0012]    The term “substantially” means that the value of the value or property that the term modifies is within about 10% of the related value or property. In other embodiments, the term means that the value or property is withing 5% of the related value or property. In other embodiments, the term means that the value or property is withing 2.5% of the related value or property. In other embodiments, the term means that the value or property is withing 1% of the related value or property. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    The inventor has found that power systems may be constructed that extract energy from a combination of at least one lower temperature heat source stream from at least one initial well in a geothermal field and at least one higher temperature heat source stream from at least one production well in the geothermal field. While it is possible, using a conventional power system, to simply mix higher temperature and lower temperature heat source streams, such mixing causes thermodynamic irreversibility, drastically reducing efficiency that may be attained from using the mixed streams. Therefore, in the prior art, the lower temperature heat sources have simply not been used. 
         [0014]    In the present systems, power is generated by using both types of heat source streams, lower temperature heat source streams and higher temperature heat source streams from a geothermal field. The use of both types of streams from the same geothermal field is possible because the working fluid of the present system is a multi-component working fluid and has variable compositions throughout the systems. This means that the boiling point of the working fluid occurs at variable temperatures. The multi-component working fluid includes at least one lower boiling point component and at least one higher boiling point component. Therefore, with a properly selected of working fluid composition, in which there is a high concentration of the lower boiling component called a rich solution, the heat consumption in a low temperature portion of a vaporization or boiling subsystem is much greater than the heat consumption in a high temperature portion of the vaporization or boiling subsystem. As a result of using a multi-component working fluid, the present invention system may be constructed so that a separate higher temperature heat source stream is used in the high temperature portion of the vaporization or boiling subsystem, and then, subsequently, a combined stream including a somewhat cooled higher temperature heat source stream and at least one lower temperature heat source stream for the low temperature portion of the vaporization or boiling subsystem. 
         [0015]    Because a maximum temperature of the working fluid in the systems of this invention is defined by a maximum initial temperature of the higher temperature heat source stream, the thermal efficiency of the systems as a whole is the same as if all of the heat used in the system came from a single higher temperature heat source stream (i.e., the thermal efficiency of the systems is related to a maximum initial temperature of the higher temperature heat source stream). However, the total quantity of heat available to the systems is drastically increased by using the lower temperature heat source streams in the low portion of the boiling subsystem. This allows for the production of much more power than would be possible with only the higher temperature heat source stream, but the thermal efficiency of the system remains as high as it would have been if the lower temperature heat source stream had not been used. 
       Suitable Reagents and Equipment 
       [0016]    The working fluid used in the systems of this invention are multi-component fluids comprising a lower boiling point component and a higher boiling point component. Suitable multi-components fluids include, without limitation, ammonia-water mixtures, mixtures of two or more hydrocarbons, mixtures of two or more freon, mixtures of hydrocarbons and freons, or mixtures thereof. In general, the fluid may comprise mixtures of any number of compounds with favorable thermodynamic characteristics and solubility. In certain embodiments, the multi-component fluid comprises a mixture of water and ammonia. 
         [0017]    It should be recognized by an ordinary artisan that at those points in the systems of this invention were a stream is split into two or more sub-streams, dividing valves that affect such stream splitting are well known in the art and may be manually adjustable or dynamically adjustable so that the splitting achieves the desired stream flow rates and system efficiencies. Similarly, when stream are combined, combining valve that affect combining are also well known in the art and may be manually adjustable or dynamically adjustable so that the splitting achieves the desired stream flow rates and system efficiencies. 
       Specific Embodiments 
       [0018]    Referring now to  FIG. 1 , a fully condensed lean solution stream S 1  having parameters as at a point  1  at a first and lowest pressure is pumped to a second pressure and higher pressure that is lower than a third pressure and highest pressure of the streams S 6 , S 15 , S 16  and S 17  in a vaporization or boiling subsystem as described below by a booster pump P 1  to form a pressurized, fully condensed lean solution stream S 2  having parameters as at a point  2 . The fully condensed lean solution stream S 1  has a low concentration of the lower boiling component of the multi-component working fluid. The pressurized, fully condensed lean solution stream S 2  corresponds to a state of a subcooled liquid. 
         [0019]    The pressurized, fully condensed lean solution stream S 2  is then mixed with a second saturated rich vapor stream S 13  having parameters as at a point  13  as described below. As a result of being mixed with the pressurized, fully condensed lean solution stream S 2 , the vapor stream S 13  is fully absorbed by the lean solution stream S 2  forming a saturated or slightly subcooled liquid rich solution stream S 3  having parameters as at a point  3 . The system is designed so that a total flow rate of the rich solution stream S 3  is higher than a flow rate of the streams S 1  and S 2  due to the absorption of the rich vapor stream S 13 . 
         [0020]    The rich solution stream S 3  is then sent into a feed pump P 2 , and pumped to the third pressure, which is a desired elevated pressure, forming a liquid rich solution stream S 6  having parameters as at a point  6 , corresponding to a state of subcooled liquid. 
         [0021]    The subcooled liquid rich solution stream S 6  is then sent into a lower temperature portion of the vaporization subsystem comprising a second heat exchange unit or a lower temperature boiler HE 2 , where it is heated in counter flow with a combined heat source stream S 45  in a second heat exchange process  45 - 42 - 43  or  6 - 7 - 15  obtaining parameters as at a point  7  within the second heat exchange unit HE 2  and boils exiting the second heat exchange unit HE 2  to form a partially vaporized rich solution stream S 15  having parameters as at a point  15 , corresponding to a state of a boiling vapor-liquid mixture. 
         [0022]    Thereafter, the rich solution stream S 15  enters into a higher temperature portion of the vaporization subsystem comprising a third heat exchange unit or a higher temperature boiler HE 3 , where the rich solution stream S 15  is further heated in counter flow with a higher temperature heat source stream S 40  having parameters as at a point  40  in a third heat exchange process  40 - 41  or  15 - 16  to form a further vaporized rich solution stream S 16  having parameters as at a point  16 , corresponding to a state of a vapor-liquid mixture and a cooled higher temperature heat source stream S 41  having parameters as at a point  41 . Note that there is less liquid and more vapor in the vapor-liquid rich solution stream S 16  than in the less vaporized rich solution stream S 15 . 
         [0023]    The rich solution stream S 16  is then forwarded into a first gravity separator S 1 , where the rich solution stream S 16  is separated into a vapor richer solution stream S 17  having parameters as at a point  17  and a first saturated lean liquid stream S 8  having parameters as at a point  8 . 
         [0024]    The first lean liquid stream S 8  is then sent through a first throttle valve TV 1 , where its pressure is reduced to a pressure equal or substantially equal to the second pressure, which is the pressure of the lean solution stream S 2  as described above to form a vapor-liquid stream S 9  having parameters as at a point  9 , corresponding to a state of a vapor-liquid mixture at the second pressure. 
         [0025]    The mixed stream S 9  is then forwarded to a second gravity separator S 2 , where it is separated into the second saturated rich vapor stream S 13  having the parameters as at the point  13  as described above and a second saturated lean liquid stream S 14  having parameters as at a point  14 . 
         [0026]    Meanwhile, the stream S 17  is sent into a turbine T 1 , where it is expanded and a portion of its heat is converted into a usable form of energy such as mechanical and/or electrical energy or power forming a spent stream S 18  having parameters as at a point  18 , corresponding to a state of wet vapor. 
         [0027]    At the same time, the second saturated lean liquid stream S 14  described above is sent through a second throttle valve TV 2 , where its pressure is reduced to a pressure equal to a pressure of the spent stream S 18  forming a lower pressure mixed vapor-liquid lean steam S 19  having parameters as at a point  19 , corresponding to a state of a vapor-liquid mixture. 
         [0028]    The stream S 19  is then mixed with the spent stream S 18  to form a vapor-liquid lean solution stream S 20  having parameters as at a point  20 . 
         [0029]    The stream S 20  then enters into a first heat exchange unit or a condenser HE 1 , where it is cooled and fully condensed in counter flow with a coolant stream S 51  in a coolant heat exchange process  51 - 52  or  20 - 1  to form the fully condensed lean stream S 1  having the parameters as at the point  1  as described above and a spent coolant stream S 52  having parameters as at a point  52 . 
         [0030]    The coolant enters the system as an initial coolant stream S 50  having parameters as at a point  50 , which is then sent into a coolant pump P 4  in the case of a liquid coolant or into a coolant fan F 4  (not shown), where its pressure is increased to form a pressurized coolant stream S 51  having parameters as at a point  51 . The stream S 51  is then sent into the condenser HE 1 , where it cools and condenses the stream S 20  in the coolant heat exchange process  20 - 1  or  51 - 52 . 
         [0031]    Meanwhile, a higher temperature heat source stream S 40  having the parameters as at the point  40  enters into the third heat exchange unit HE 3 , where it is cooled in counter flow with the stream S 15  providing heat for the third heat exchange process  15 - 16  or  40 - 41  as described above to form the cooled higher temperature heat source stream S 41  having the parameters as at the point  41 . The system is designed so that the temperature of the stream S 41  at the point  41  is greater than or equal to an initial temperature of the lower temperature heat source stream S 44  having the parameters as at the point  44  as described below. 
         [0032]    The cool higher temperature heat source stream S 41  is then mixed with the lower temperature heat source stream S 44  having the parameters as at the point  44  as described above to form a combined heat source stream S 45  having parameters as at point  45 . 
         [0033]    The combined heat source stream S 45  is then sent into the second heat exchange unit HE 2 , where it is cooled in counter flow with the stream S 6  providing heat for the second heat exchange process  6 - 7 - 15  or  45 - 42 - 43  as described above so that the combined stream S 45  changes parameters from the point  45  to the point  42  and then to form the spent combined heat source stream S 43  having the parameters as at the point  43 , whereupon the combined heat source stream exists the system. 
         [0034]    The system is closed. 
         [0035]    In the systems of this invention, the pressure profile of the streams is tabulated in Table I, which the stream compositions from richest to leanest are tabulated in Table II. 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                 TABLE I 
               
             
             
               
                   
               
               
                 Stream Pressures 
               
             
          
           
               
                   
                 Stream 
                 Pressure 
               
               
                   
                   
               
               
                   
                 S6, S15, S16, S17, and S8 
                 highest 
               
               
                   
                 S2, S3, S13, and S14 
                 intermediate 
               
               
                   
                 S1, S18, S19, and S20 
                 lowest 
               
               
                   
                   
               
             
          
         
       
     
         [0036]    The systems of this invention establish a thermodynamic cycle including streams having three different pressure. The highest pressure streams pass through the vaporization subsystem including a feed pump P 2 , the second and third heat exchange units HE 2  and HE 3  and a first gravity separator S 1  and then through the energy extraction subsystem including the turbine T 1 . The lowest pressure streams are combined and fully condensed in the condensation subsystem including the first heat exchange unit HE 1 . The intermediate pressure streams are separated in a second separator S 2 , pressurized in a first pump P 1 , combined with a lean solution stream to make a rich solution stream, reduced in pressure in a first throttle control valve TV 1  before being fed to the separator S 2 , reduced in pressures in a second throttle control valve TV 2 , and combined with the spent stream to form a lean solution stream in a separation and pressure reduction subsystem. 
         [0000]    
       
         
               
             
               
               
               
               
             
           
               
                 TABLE II 
               
             
             
               
                   
               
               
                 Stream Compositions 
               
             
          
           
               
                   
                 Stream 
                 Composition 
                 Designation 
               
               
                   
                   
               
               
                   
                 S17 and S18 
                 richest 
                 richer solution 
               
               
                   
                 S13 
                 richer 
               
               
                   
                 S3, S6, S15, and S16 
                 rich 
                 rich solution 
               
               
                   
                 S8 and S9 
                 lean 
               
               
                   
                 S20, S1, and S2 
                 lean 
                 lean solution 
               
               
                   
                 S14 and S19 
                 leanest 
               
               
                   
                   
               
             
          
         
       
     
         [0037]    The lean solution streams S 20 , S 1 , and S 2  and the stream S 8  and S 9  are leaner than the rich solution streams S 3 , S 6 , S 15 , and S 16 , but there relative leanness relative to each other will depend on the working fluid used and the operating parameters of the system so they are designated as only being lean. 
         [0038]    In the systems of this invention, a flow rate of the higher temperature heat source stream S 40  may be substantially lower than a flow rate of the lower temperature heat source stream S 44 . Modeling computations have shown that the systems of this invention may be operated properly with the flow rate of the higher temperature heat source stream S 40  as low as 25% of the flow rate of the lower temperature heat source stream S 44 . 
         [0039]    The flow rate of the higher temperature heat source streams S 40  and S 41  is adjusted so that the flow rate is sufficient to provide as much heat as is required in the third heat exchange process  15 - 16  or  40 - 41 . In the case that the flow rate of the higher temperature heat source stream S 40  is too small to provide the required heat for the third heat exchange process  15 - 16  or  40 - 41 , then one of two options must be employed. In option one, a temperature of the stream S 16  at the point  16  must be reduced so as to provide a balance between the heating process  15 - 16  and the cooling process  40 - 41  of the third heat exchange process  15 - 16  or  40 - 41 . In the second option, a temperature difference between a temperature of the stream S 45  at the point  42  and a temperature of the stream S 6  at the point  7  has to be increased, i.e., the utilization of available heat from the lower temperature heat source stream S 44  must be reduced. Either way, the total power output of the systems of this invention would be reduced. One experienced in the art may choose one or the other of these options, or a mix of both, to come up with an optimal available power output possible from a given set of heat sources. 
         [0040]    The temperature differences between the heat source streams and the working fluid streams in the second heat exchange unit HE 2  and the third heat exchange unit HE 3  are substantially reduced as compared to a system that would have used only the higher temperature heat source stream S 40 . As a result, the thermodynamic irreversibility in the process of heat transfer from the heat source streams to the working fluid streams is substantially reduced and the system has a substantially higher 2nd Law efficiency as compared to a system that utilizes only the higher temperature heat source. 
         [0041]    At the same time the thermal efficiency of the system remains as high as it would be in a system where only the higher temperature heat source is utilized. 
         [0042]    Likewise, the total power produced in the present systems are substantially higher than would be possible with a conventional system using a mixture of higher temperature sources and lower temperature heat sources. 
         [0043]    The present systems allow for the use of wells in geothermal fields, for power generation purposes, that would otherwise not have been useable due to having too low an initial temperature. This allows for a substantial reduction in a specific cost per kilowatt of power output for geothermal fields having at least one lower temperature stream, generally from initial site drilling and at least on higher temperature or production of heat source. 
         [0044]    Referring now to  FIG. 2 , a geothermal field  100  is shown to include a geothermal formation  102  below a surface  104  of the ground  106 . Into the field  100 , a set of initial wells  108  was drilled locating the geothermal formation  102  permitting a set of production wells  110  to be drilling into the geothermal formation  102 . The production wells  110  supply the higher temperature heat source streams and the initial wells  108  supply the lower temperatures heat source streams. 
         [0045]    All references cited herein are incorporated by reference. Although the invention has been disclosed with reference to its preferred embodiments, from reading this description those of skill in the art may appreciate changes and modification that may be made which do not depart from the scope and spirit of the invention as described above and claimed hereafter.