Abstract:
A system includes a first plate and a second plate. The first plate is arranged to be thermally coupled to a first surface and the second plate is arranged to be thermally coupled to an environment. The environment has a temperature that is different than the first surface. The system also includes a thermoelectric device that includes a plurality of thermoelectric elements. The thermoelectric device includes a third plate coupled to the plurality of thermoelectric elements and thermally coupled to the first plate. The thermoelectric device also includes a fourth plate coupled to the plurality of thermoelectric elements and thermally coupled to the second plate. The system also includes a dielectric fluid arranged between the first plate and the second plate. The thermoelectric elements are submersed in the dielectric fluid.

Description:
RELATED APPLICATION 
       [0001]    This application claims benefit under 35 U.S.C. §119(e) of U.S. Provisional Application Ser. No. 61/709,895, titled “A System For Thermoelectric Energy Generation,” Attorney&#39;s Docket 017083.0341, tiled Oct. 4, 2012, by Joshua E. Moczygemba and U.S. Provisional Application Ser. No. 61/745,413, titled “A System For Thermoelectric Energy Generation,” Attorney&#39;s Docket 017083.0343, filed Dec. 21, 2012, by Joshua E. Moczygemba, 
     
    
     TECHNICAL FIELD 
       [0002]    This disclosure relates to generally to energy generation and more particularly to a system for thermoelectric energy generation. 
       BACKGROUND  
       [0003]    The basic theory and operation of thermoelectric devices has been developed for many years. Presently available thermoelectric devices used for cooling typically include an array of thermocouples that operate in accordance with the Peltier effect. Thermoelectric devices may also be used for heating, power generation, and temperature sensing. 
         [0004]    A thermoelectric device produces electrical power from heat flow across a temperature gradient. As the heat flows from hot to cold, free charge carriers in the thermoelectric material are also driven to the cold end. The resulting voltage is proportional to the temperature difference via the Seebeck coefficient. 
       SUMMARY 
       [0005]    In one embodiment, a system includes a first plate and a second plate. The first plate is arranged to be thermally coupled to a first surface and the second plate is arranged to be thermally coupled to an environment. The environment has a temperature that is different than the first surface. The system also includes a thermoelectric device that includes a plurality of thermoelectric elements. The thermoelectric device includes a third plate coupled to the plurality of thermoelectric elements and thermally coupled to the first plate. The thermoelectric device also includes a fourth plate coupled to the plurality of thermoelectric elements and thermally coupled to the second plate. The system also include sa dielectric fluid arranged between the first plate and the second plate. The thermoelectric elements are submersed in the dielectric fluid. 
         [0006]    In some embodiments, a gasket may be situated within a groove of the first plate. The system may include a wall situated between the first plate and the second plate. The wall may be situated around the thermoelectric device. The wall may include thermally insulative material. 
         [0007]    In one embodiment, a method includes thermally coupling a first plate to a first surface and thermally coupling a second plate to an environment. The environment has a temperature that is different than the first surface. The method further includes generating electricity using a thermoelectric device based on a temperature gradient between the first plate and the second plate. The thermoelectric device includes a plurality of thermoelectric elements submersed in a dielectric fluid. The thermoelectric device also includes a third plate coupled to the plurality of thermoelectric elements and thermally coupled to the first plate as well as a fourth plate coupled to the plurality of thermoelectric elements and thermally coupled to the second plate. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    Reference is now made to the following description taken in conjunction with the accompanying drawings, wherein like reference numbers represent like parts. 
           [0009]      FIGS. 1A and 1B  illustrate one embodiment of a system that is configured to generate electric energy. 
           [0010]      FIG. 2  is an exploded view of one embodiment of a thermoelectric generator. 
           [0011]      FIG. 3  is a side view of one embodiment of a thermoelectric generator including a diaphragm. 
           [0012]      FIG. 4  is a side view of one embodiment of a thermoelectric generator that incorporates a fin. 
           [0013]      FIG. 5  is a side view of one embodiment of a thermoelectric generator that incorporates an electronic device. 
           [0014]      FIG. 6  illustrates one embodiment of a thermoelectric device. 
           [0015]      FIGS. 7A and 7B  are a set of charts depicting examples of performance characteristics of embodiments of thermoelectric generators. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]      FIGS. 1A and 1B  illustrate one embodiment of system  100  that is configured to generate electrical energy. In some embodiments, pipe  120  is in a high pressure (e.g., 100-10,000 psi) environment  140  (e.g., deep sea water, such as 10,000 feet below sea level at approximately 40 degrees Fahrenheit) and contains a hot (e.g., between 100 and 300 degrees Fahrenheit) medium (e.g., liquid or gas). As such, there is a temperature gradient between pipe  120  and environment  140  (e.g., a gradient between 50 and 200 degrees Fahrenheit). Thermoelectric generator  110  is situated such that one side of generator  110  is thermally coupled to pipe  120  (e.g., by being secured directly to pipe  120  or with suitable thermal interface materials such as graphite pads, grafoil, or other thermal pads situated between pipe  120  and generator  110 ) while another side of generator  110  is exposed to environment  140 . Thermoelectric generator  110  is situated inside insulation  130  that covers pipe  120  such that a side of generator  110  is still exposed to environment  140  (as depicted in  FIG. 1B ). Thermoelectric generator  110  is configured to generate electricity based on the temperature difference between pipe  120  and environment  140  using the Seebeck effect. In some embodiments, generator  110  may be a reliable source of electrical energy suitable to power electronics such as sensors due to the near constant temperature difference between pipe  120  and environment  140 . In some embodiments, pipe  120  may contain a cold medium and environmental  140  may be hot; thermoelectric generator  110  may provide electrical energy in this situation due to the temperature difference between pipe  120  and environment  140 . 
         [0017]    In some embodiments, high pressure environment  140  may include environments such as deep sea water. Another example of environment  140  is the interior of a pressure vessel. Yet another example of environment  140  is the interior of a pipeline. Thus, while the present disclosure discusses deep sea water as an example environment, the disclosure is applicable in other environments, such as those that have higher than normal pressure and those that lead to temperature gradients between the environment and devices in the environment. 
         [0018]    In some embodiments, system  100  may be a continuous power source designed to harvest thermal energy (e.g., from subsea pipelines). The large temperature gradients between the pipelines and water may facilitate sustained, long term thermal energy harvesting. An example utility of this is avoiding battery replacement which may not be an economical option in such an environment. Example advantages of embodiments of system  100  are that system  100  may provide perpetual or continual, no maintenance power for subsea or deep sea applications. As another example, system  100  can be used to implement a sustainable, low-cost solution to monitoring ocean floor pipelines. Typically, ocean floor pipelines are costly to monitor and repair, especially after they have been substantially damaged. Using system  100 , problems may be detected beforehand and costly repairs can be avoided. For example, electrical energy produced by system  100  can then be used to power low-power electronics that can be used to monitor a pipeline in a convenient package which can be attached to the pipeline during a field jointing process. 
         [0019]      FIG. 2  is an exploded view of one embodiment of thermoelectric generator  200  that may be used to implement thermoelectric generator  110  of  FIGS. 1A and 1B . Cold side plate  230  is fastened to hot side plate  280  using fasteners  220  (e.g., nails, screws, and/or rivets). Thermoelectric device  250  is situated between plates  230  and  280  such that one side of thermoelectric device  250  is thermally coupled to plate  230  while another side of thermoelectric device  250  is thermally coupled to plate  280 . Immediately surrounding thermoelectric device  250  is wall  260 . Plates  230  and  280  as well as wall  260  may have grooves that are configured to receive gaskets  240  and  270 . Plate  230  may also include an orifice that allows for fluid to be poured into generator  200  once it is assembled and that orifice may be sealed using plug  210 . 
         [0020]    In some embodiments, plates  230  and  280  can be titanium, stainless steel, aluminium, 90Cu10Ni alloy, or any bare or coated metal. In some embodiments, plates  230  and  280  may provide long term protection against sea water. In some embodiments, exterior sided edge insulation (suck as insulation  130 ) may be placed around the side edges of the housing (e.g., around plates  230  and  280 ) to further insulate thermoelectric generator  200  from thermal shorting (e.g., due to sea water in applicable circumstances). 
         [0021]    In some embodiments, gaskets  240  and  270  may be hydraulic gaskets. Materials such as viton, nitrile, hydrogenated nitrile, fluorsilicone, epdm, silicone may be employed to form gaskets  240  and  270 . Gaskets  240  and  270  may prevent mixing of hydraulic fluid and sea water. 
         [0022]    In some embodiments, wall  260  may be a low conductivity wall. For example, thermally insulative materials (e.g., polysulfone, Teflon, polycarbonate, nitrile, acrylic) may be used to form wall  260 . This may reduce, minimize, or prevent thermal shorting from the hot side to the cold side of thermoelectric generator  200 . This can be used to help force heat through thermoelectric device  250 . 
         [0023]    In some embodiments, thermoelectric generator  200  may produce electrical energy when a temperature difference exists between plates  230  and  280 . Gaskets  240  and  270  may allow generator  200  to operate in aquatic environments such as deep sea water. Wall  260  may allow generator  200  to operate in the presence of high pressure such as those encountered in deep sea water. An example advantage is that gaskets  240  and  270  as well as low pressure differences between the inside of thermoelectric generator  200  and its environment may allow for using materials with low thermal conductivity to reduce or minimize reduction in performance due to thermal shorting. Another example advantage is that thermal shorting effects through housing of thermoelectric generator  200  may be reduced. For example, materials used for plates  230  and  280  as well as wall  260  can be chosen to avoid thermal shorting. As another example, thermal shorting can be avoided by allowing for plates  230  and  280  to have different shapes and thicknesses than what is typically used in high pressure environments. 
         [0024]    In some embodiments, a configuration of thermoelectric generator  200  may eliminate wall  260  as well as gaskets  240  and  270  and replace them with a single hydraulic gasket. The size, shape and material of this single hydraulic gasket could be tailored to minimize conduction between plates  230  and  280 . One or more thin layers of dielectric hydraulic fluid (e.g., mineral oil, silicone oil, or vegetable oil) may serve as thermal interfaces between thermoelectric device  250  and plates  230  and  280 . In some embodiments, graphite pads, grafoil, or other thermal pads may serve as thermal interfaces between thermoelectric device  250  and plates  230  and  280 . Dielectric hydraulic fluids may be used in combination with thermal pads as thermal interfaces between thermoelectric device  250  and plates  230  and  280 . 
         [0025]      FIG. 3  is a side view of one embodiment of thermoelectric generator  300 . Thermoelectric generator (“TEG”)  300  may be used to implement thermoelectric generator  200  of  FIG. 2  and thermoelectric generator  110  of  FIGS. 1A and 1B . Cold side plate  310  i fastened to hot side plate  320  using fastener  340  through channel  330 . Thermoelectric device  380  is situated between plates  310  and  320  such that one side of thermoelectric device  380  is thermally coupled to plate  310  and another side of thermoelectric device  380  is thermally coupled to plate  320 . Orifice  350  provides a manner in which to introduce substances into thermoelectric generator  300  such as fluid  390 . Orifice  350  is sealed using plug  360 . Diaphragm  370  may interface with plug  360 . Some or all of the spaces between and/or around thermoelectric elements of thermoelectric device  380  may include baffles  385  (e.g., open cell hexagonal strips). In some embodiments, thermoelectric generator  300  can handle very large isostatic pressures. Testing has shown that 10,000 psi under isostatic conditions poses no significant change to performance of thermoelectric device  380 . 
         [0026]    In some embodiments, diaphragm  370  can allow for pressure equalization in the event air is trapped in the interior portion of the block. One mechanism by which this could occur with thermoelectric modules is the collapsing or air pockets entrained in solder joints as isostatic pressure increases. In such a case, diaphragm  370  would be sized so as to compensate for he change in internal volume of housing in TEG  300 . Diaphragm  370  would then displace, rather than housing of TEG  300  needing to support, the pressure differential. 
         [0027]    In some embodiments, fluid  390  may be a low thermal conductivity, dielectric, incompressible fluid. In some embodiments, a fluid counteracts the external pressure of the seawater at large depths (reducing the need for thick walls for housing of TEG  300 ) and evenly distributes the pressure to every surface of the TEG module. For example, a hollow egg crushes quickly at low depth, but the same egg completely filled with an incompressible fluid could be submerged to large depths (e.g., the bottom of the Marianas Trench) without rupture. Also, since fluid  390  has a low thermal conductivity, transfer of heat from hot pipe to cold plate through the fluid is minimized. In some embodiments, the need for thick housing walls and strong materials is also reduced, significantly reducing thermal bypass through these walls (around TEG  300 ) from hot to cold side. In some embodiments, such a design significantly increases power output of TEG  300  (because the excess heat does not saturate the cold plate). Fluid  390  may be a hydraulic fluid (e.g., k=0.13 W/m-K), such as mineral oil, silicone oil, or vegetable oil to minimize thermal conductions losses through fluid  390  from hot to cold reservoirs. In some embodiments, liquid  390  may include a low thermal conductivity, non-compressible filer (e.g., a powder that is incompressible and not electrically conductive such as aluminum oxide, silicate, or ceramic type powders) or other suitable alternatives. The filler can be used to prevent convection currents. Also, a thin layer of fluid  390  can serve to aid or replace thermal interface material between thermoelectric device  380  and plates  310  and  320  thereby reducing the thermal interface contact resistance. 
         [0028]    In some embodiments, thermoelectric generator  300  includes aspects that may facilitate generation of electric energy in high pressure environments such as deep sea water based on temperature differences between plates  310  ad  320 . For example, dielectric fluid  390  may be used to alleviate differential pressures. As another example, baffles  385  and/or filler material may be used to suppress convection currents. 
         [0029]      FIG. 4  is a side view of one embodiment of thermoelectric generator (“TEG”)  400  that incorporates fin  440 . Thermoelectric generator  400  may be used to implement thermoelectric generator  200  of  FIG. 2  and thermoelectric generator  110  of  FIGS. 1A and 1B . Cold side plate  410  and hot side plate  420  are each thermally coupled to different sides of thermoelectric device  430 . Fin  440  is situated on cold side plate  410  and may assist in heat transfer to the environment in which thermoelectric generator  400  is situated (e.g., deep sea water). 
         [0030]    In some embodiments, fin  440  may be any fixture capable of increasing the surface area over which TEG  400  may exchange thermal energy with its environment. For example, fin  440  may be a zipped or stacked fin heat exchanger comprising a plurality of closely-spaced fins separated from one another by a series of spaces. Each fin may include one or more flanges or other features operable to interlock the plurality of fins together into a single, unitary array. For example, flanges may be a series of frusto-conically-shaped perforations in fin  440  that are nested inside one another to link each of the individual fins together. Fin  440  may include a plurality of zipped fin structures, with each having a flat bottom coupled to a plurality of parallel fins. Fin  440  may be implemented using extrusion or skiving processes. Fin  440  may be a folded fin structure comprising a single sheet of material that has been consecutively folded over onto itself to create a single array of closely spaced fins. Fin  440  may include a lateral (e.g., generally L-shaped) fold at one end that, when aggregated together, form a flat. 
         [0031]      FIG. 5  is a side view of one embodiment of thermoelectric generator  500  that incorporates an electronic device. Cold side plate  510  and hot side plate  520  are each thermally coupled to different sides of thermoelectric devices  530 . Electrical energy is generated by thermoelectric device  530  as a result of temperature differences between plates  510  and  520  and can be directed to electronic component  550  via leads  540   a - b . Electronic component  550  is situated within cold side plate  510 . Examples of electronic component  550  include circuit boards, power storage, sensors, and transmitters. 
         [0032]      FIG. 6  illustrates one embodiment of thermoelectric device  600  that may be used to implement thermoelectric device  250  of  FIG. 2 , thermoelectric device  380  of  FIG. 3 , thermoelectric device  430  of  FIG. 4 , and thermoelectric device  530  of  FIG. 5 . Thermoelectric device  600  includes a plurality of thermoelectric elements  630  disposed between plates  610  and  620 . Electrical terminals  640  and  650  are provided to allow thermoelectric device  600  to be electrically coupled with to one or more devices that use, transform, or store electrical power. 
         [0033]    In some embodiments, thermoelectric elements  630  fabricated from dissimilar semiconductor materials such as N-type thermoelectric elements and P-type thermoelectric elements. Thermoelectric elements  630  are typically configured in a generally alternating N-type element to P-type element arrangement and typically include an air gap disposed between adjacent N-type and P-type elements. In many thermoelectric devices, thermoelectric materials with dissimilar characteristics are connected electrically in series and thermally in parallel. 
         [0034]    Examples of thermoelectric devices and methods of fabrication are shown in U.S. Pat. No. 5,064,476 titled Thermoelectric Cooler and Fabrication Methods; U.S. Pat. No. 5,171,372 titled Thermoelectric Cooler and Fabrication Method; and U.S. Pat. No. 5,576,512 titled Thermoelectric Apparatus for Use With Multiple Power Sources and Method of Operation. 
         [0035]    N-type semiconductor materials generally have more electrons than would be found in the associated ideal crystal lattice structure. P-type semiconductor materials generally have fewer electrons than would be found in the associated ideal crystal lattice structure. The “missing electrons” are sometimes referred to as “holes.” The extra electrons and extra holes are sometimes referred to as “carriers.” The extra electrons in N-type semiconductor materials and the extra holes in P-type semiconductor materials are the agents or carriers that transport or move heat energy between plates  610  and  620  through thermoelectric elements  630  when subject to a DC voltage potential. These same agents or carriers may generate electrical power when an appropriate temperature difference is present between plates  610  and  620 . Terminals  640  and  650  may be coupled to one of plates  610  and  620  in a manner that withstands high temperature environments, such as resistance welding, tungsten inert gas (TIG) welding, and laser welding. 
         [0036]    In some embodiments, thermoelectric elements  630  may include high temperature thermoelectric material. Examples of high temperature thermoelectric materials include lead telluride (PbTe), lead germanium telluride (PbxGel-xTe), TAGS alloys (such as (GeTE)0.85(AgSbTe2)0.15), bismuth telluride (Bi2Te3) based alloys, and skutterudies. 
         [0037]    In some embodiments, thermoelectric elements  630  may include a diffusion barrier that includes refractory metals (e.g., a metal with a melting point above 1,850° C.). Suitable refractory metals may include those that are metallurgically compatible with high temperature thermoelectric materials and metallurgically compatible with other components of thermoelectric device  600 . For example, a molybdenum diffusion barrier may be used. This may be advantageous in that molybdenum may be metallurgically compatible with various aspects of thermoelectric device  600 . For example, as further discussed below, thermoelectric device  600  may include an aluminum braze that is metallurgically compatible with a molybdenum diffusion barrier. Such a diffusion barrier may prevent or reduce the change or occurrence of Kirkendall voiding in thermoelectric device  600 . Other suitable examples of diffusion barrier materials that could have similar properties to molybdenum include tungsten and titanium. 
         [0038]    In some embodiments, alternating thermoelectric elements  630  of N-type and P-type semiconductor materials may have their ends connected by electrical conductors. Conductors may be metallization formed on thermoelectric elements  630  and/or on the interior surfaces of plates  610  and  620 . Conductors may include aluminum. Ceramic materials may be included in plates  610  and  620  which define in part the cold side and hot side, respectively, of thermoelectric device  600 . In some embodiments, the ceramic materials may provide electrical isolation from hot and cold side sources. Aluminum metallized ceramics may accommodate thermal stresses (i.e., due to high temperature exposure) of the ceramic/aluminum bond. Examples of suitable ceramic materials include anodized aluminum, aluminum oxide, aluminum nitride, and beryllium oxide. 
         [0039]    In some embodiments, thermoelectric elements  630  may be coupled to plates  610  and  620  using a medium. The medium may include brazes and/or solders. For example, aluminum-based brazes and/or solders may be used, such as aluminum-silicon (Al—Si) braze family and/or zinc-aluminum (Zn—Al) solder. In some embodiments, using such brazes and/or solders may provide for high temperature operation and allow for flexible joints. Kirkendall voiding may be prevented or reduced. 
         [0040]      FIGS. 7A and 7B  are a set of charts depicting examples of performance characteristics (based on models and experiments) of embodiments of thermoelectric generators configured as described above with respect to  FIGS. 1A-6 . Chart  700  depicts power output (both of a model and experimental results) of a thermoelectric generator, such as thermoelectric generator  110  of  FIG. 1A , as a result of the amount of temperature difference present (e.g., the difference in temperature between pipe  120  and environment  140  of  FIG. 1A ). The following table provides examples of the values used in chart  700 : 
         [0000]    
       
         
               
               
               
             
               
               
               
             
           
               
                   
               
               
                 Temperature 
                 Power 
                 Model 
               
               
                 Difference (F.) 
                 (Watts) 
                 (Watts) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 200.192 
                 1.067 
                 1.050 
               
               
                 200.176 
                 1.066 
                 1.050 
               
               
                 158.731 
                 0.707 
                 0.691 
               
               
                 157.284 
                 0.696 
                 0.679 
               
               
                 128.209 
                 0.474 
                 0.465 
               
               
                 94.964 
                 0.268 
                 0.262 
               
               
                 73.661 
                 0.164 
                 0.160 
               
               
                 54.983 
                 0.093 
                 0.090 
               
               
                 45.232 
                 0.063 
                 0.061 
               
               
                 44.779 
                 0.062 
                 0.060 
               
               
                 32.362 
                 0.033 
                 0.032 
               
               
                 32.011 
                 0.032 
                 0.031 
               
               
                 25.349 
                 0.020 
                 0.019 
               
               
                 25.103 
                 0.020 
                 0.019 
               
               
                 21.568 
                 0.015 
                 0.014 
               
               
                 21.353 
                 0.014 
                 0.014 
               
               
                 17.838 
                 0.010 
                 0.010 
               
               
                 13.450 
                 0.006 
                 0.006 
               
               
                 10.690 
                 0.004 
                 0.003 
               
               
                 7.576 
                 0.002 
                 0.002 
               
               
                 5.546 
                 0.001 
                 0.001 
               
               
                 3.719 
                 0.001 
                 0.000 
               
               
                 2.878 
                 0.000 
                 0.000 
               
               
                   
               
             
          
         
       
     
         [0041]    Charts  710  and  720  indicate power outputs of a thermoelectric generator, such as thermoelectric generator  110  of  FIG. 1A , as compared to the temperature of a pipe (e.g., pipe  120  of  FIG. 1A ) to which the thermoelectric generator is attached. Chart  710  is the result of experiments where ice water (“ICE”), at 4.44 degrees Celsius, is used and where room temperature (“RT”) water, at 25 degrees Celsius, is used. The following tables provide examples of the values used in chart  710 : 
         [0000]    
       
         
               
             
               
               
               
             
               
               
               
             
           
               
                   
               
               
                 Ice 
               
             
          
           
               
                   
                 Pipe Temperature 
                 Power 
               
               
                   
                 (F.) 
                 (Watts) 
               
               
                   
                   
               
             
          
           
               
                   
                 42.8 
                 0.0 
               
               
                   
                 49.6 
                 0.001 
               
               
                   
                 67.1 
                 0.009 
               
               
                   
                 80.6 
                 0.021 
               
               
                   
                 98.6 
                 0.047 
               
               
                   
                 103.6 
                 0.057 
               
               
                   
                 108.5 
                 0.067 
               
               
                   
                 120.2 
                 0.095 
               
               
                   
                 131.0 
                 0.125 
               
               
                   
                 152.6 
                 0.196 
               
               
                   
                 162.5 
                 0.233 
               
               
                   
                 176.5 
                 0.288 
               
               
                   
                 196.3 
                 0.371 
               
               
                   
                 210.7 
                 0.435 
               
               
                   
                 225.5 
                 0.505 
               
               
                   
                 260.2 
                 0.681 
               
               
                   
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
             
               
               
               
             
           
               
                   
               
               
                 Room Temperature 
               
             
          
           
               
                   
                 Pipe Temperature 
                 Power 
               
               
                   
                 (F.) 
                 (Watts) 
               
               
                   
                   
               
             
          
           
               
                   
                 42.8 
                 0.000 
               
               
                   
                 49.6 
                 0.000 
               
               
                   
                 67.1 
                 0.000 
               
               
                   
                 80.6 
                 0.000 
               
               
                   
                 98.6 
                 0.008 
               
               
                   
                 103.6 
                 0.012 
               
               
                   
                 108.5 
                 0.016 
               
               
                   
                 120.2 
                 .095 
               
               
                   
                 131.0 
                 0.049 
               
               
                   
                 152.6 
                 0.097 
               
               
                   
                 162.5 
                 0.125 
               
               
                   
                 176.5 
                 0.170 
               
               
                   
                 196.3 
                 0.244 
               
               
                   
                 210.7 
                 0.304 
               
               
                   
                 225.5 
                 0.372 
               
               
                   
                 260.2 
                 0.543 
               
               
                   
                   
               
             
          
         
       
     
         [0042]    Chart  720  is the result of experiments where water at 40 degrees Fahrenheit is used. The following table provides examples of the values used in chart  720 : 
         [0000]    
       
         
               
               
               
             
               
               
               
             
           
               
                   
                   
               
               
                   
                 Pipe Temperature 
                 Power 
               
               
                   
                 (F.) 
                 (Watts) 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 266 
                 0.551 
               
               
                   
                 230 
                 0.403 
               
               
                   
                 194 
                 0.272 
               
               
                   
                 158 
                 0.157 
               
               
                   
                 122 
                 0.071 
               
               
                   
                 86 
                 0.018 
               
               
                   
                   
               
             
          
         
       
     
         [0043]    Depending on the specific features implemented, particular embodiments may exhibit some, none, or all of the following technical advantages. By enabling deep sea operation, TEG energy harvesting may be a solution for deep water monitoring of oil pipe lines. A housing for a thermoelectric generator that can withstand significant amount of pressure yet also allow heat to be transferred through a thermoelectric device has been described. Other technical advantages will be readily apparent to one skilled in the art from the preceding figures and description as well as the proceeding claims and appendices. Particular embodiments may provide or include all the advantages disclosed, particular embodiments may provide none of the advantages disclosed. 
         [0044]    Although several embodiments have been illustrated and described in detail, it will be recognized that modifications and substitutions are possible.