Abstract:
In a preferred embodiment, the invention comprises an apparatus for generating electrical power which utilizes an electrically superconductive coil immersed in a cryogenic fluid for generating a magnetic field within a region surrounding the superconductive coil when an electrical current circulates in the superconductive coil. The apparatus further includes a prime mover and a conduit which conducts a flow of gas resulting from evaporation of a cryogenic fluid to the prime mover to induce rotational motion in the prime mover. An electrical conductor is rotatably mounted within the region surrounding the superconductive coil in which the magnetic field is generated. The electrical conductor is operatively connected to the prime mover so that rotational movement of the prime mover is transferred to the electrical conductor to generate an electrical output current.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    Typically, in electrical power plants in operation today, the prime mover for the generator is a mechanical turbine. The source of power for the turbine is normally either falling water obtained from lakes formed by damming rivers, or steam, obtained by turning liquid water into a gas (steam) by the addition of heat which may be obtained from the combustion of fossil fuels or nuclear reactions. Use of other sources of electrical energy, such as batteries, fuel cells, solar cells, and wind powered generators, is normally less economical than the use of turbine generators.  
           [0002]    The underlying theory and equations which allowed others to build machines to convert other forms of energy into electrical energy were developed by James Maxwell and Michael Faraday. In the conversion of heat energy into electrical energy, the latent energy in fossil fuels is first converted into heat energy through the combustion process. This heat energy is then added to a working fluid (water) to increase its potential energy. This heat energy is then converted into mechanical energy by rotating a turbine, which includes electrically conducting coils, in a magnetic field. The fundamental principle utilized in producing electrical energy is that when an electrical conductor (wire) is moved through a magnetic field, an electrical current will flow through the conductor. By connecting this conductor to an external device the electrical current is made to move through the external device, such as an electrical motor, designed to produce a useful effect, and return to the generator.  
           [0003]    Massive distribution systems are now required to transport electricity from the generator to the user. The costs associated with developing electrical power distribution systems are extremely high. Moreover, these distributions systems are fragile and need constant maintenance and repair, and power distribution is constantly threatened by climatic disruptions and sabotage.  
           [0004]    There is a long felt need for a system for generating electrical power which is non-polluting. There is also a long felt need for a system for generating electrical power which does not require a massive distribution system of electrically conducting wires.  
           [0005]    It should be noted that the description of the invention which follows should not be construed as limiting the invention to the examples and preferred embodiments shown and described. Those skilled in the art to which this invention pertains will be able to devise variations of this invention within the scope of the appended claims.  
         SUMMARY OF THE INVENTION  
         [0006]    In a preferred embodiment, the invention comprises an apparatus for generating electrical power which utilizes an electrically superconductive coil immersed in a cryogenic fluid for generating a magnetic field within a region surrounding the superconductive coil when an electrical current circulates in the superconductive coil. The apparatus further includes a prime mover and a conduit which conducts a flow of gas resulting from evaporation of a cryogenic fluid to the prime mover to induce rotational motion in the prime mover. An electrical conductor is rotatably mounted within the region surrounding the superconductive coil in which the magnetic field is generated. The electrical conductor is operatively connected to the prime mover so that rotational movement of the prime mover is transferred to the electrical conductor to generate an electrical output current.  
           [0007]    In another embodiment, the invention comprises a method for manufacturing a superconductive electrical conductor in which a channel is formed in a mold and a material which is superconductive below a critical temperature is deposited in the mold. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 shows a diagram in partial cross-section of a generator in accordance with a preferred embodiment of the invention  
         [0009]    [0009]FIG. 2A shows a cross-sectional side view of a prime mover comprising a plurality of spaced-apart disks.  
         [0010]    [0010]FIG. 2B shows a top view of a prime mover comprising a plurality of spaced-apart disks.  
         [0011]    [0011]FIG. 3A shows a top view of an implementation of a superconductive coil.  
         [0012]    [0012]FIG. 3B shows a side view of an implementation of a superconductive coil  
         [0013]    [0013]FIG. 3C is a perspective view of a segment of the superconductive coil.  
         [0014]    [0014]FIG. 4 illustrates in schematic form the generation of a current in a Faraday disk.  
         [0015]    [0015]FIG. 5 illustrates the application of the invention to the operation of an automobile.  
         [0016]    [0016]FIG. 6 illustrates the application of the invention for supplying electrical power to a residence. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENT  
       [0017]    [0017]FIG. 1 shows a diagram of an electrical power generator  10  in accordance with a preferred embodiment of the invention. In a preferred embodiment of the invention, power for the prime mover is derived from the conversion of a cryogenic fluid from a liquid to a gas under pressure. The term “cryogenic fluid” is intended to mean a substance which is gaseous at temperatures typically found at the earth&#39;s surface, but which may be liquified at lower temperatures. Although nitrogen may be a more practical cryogenic fluid for implementing the invention, those of ordinary skill in the art will understand that other gases which liquify at low temperatures, such as hydrogen or helium, may be utilized in implementing the invention.  
         [0018]    Seventy-eight percent of the earth&#39;s atmosphere is gaseous nitrogen. Therefore, nitrogen is available at any point on the earth in unlimited amounts. Nitrogen becomes a liquid at about minus 321 degrees Fahrenheit (−321° F.), which is about seventy seven degrees Kelvin (77° K). When heat is added to liquid nitrogen to convert it into a gas, the volume of the nitrogen expands by a factor of about 850/1; that is, a one cubic inch volume of liquid nitrogen becomes about 850 cubic inches of gaseous nitrogen at 77° K. If heat is then added to this one (1) cubic inch volume and the temperature is increased from 77° K to an ambient temperature of 288° K, the pressure of the nitrogen will be about 80 pounds per square inch gage (psig). Accordingly, the thermal energy which is added to the nitrogen may be released to produce a mechanical motion. In accordance with a preferred embodiment of the present invention this produced mechanical motion is utilized to produce electrical power.  
         [0019]    In one embodiment of the invention, yttrium barium copper oxide is used as the superconducting material. However, other superconducting material, including but not limited to thallium barium calcium copper oxide and bismuth strontium calcium copper oxide , may be utilized so long as the temperature at which the material becomes superconductive is higher than the temperature at which the cryogenic fluid becomes liquid.  
         [0020]    The liquid nitrogen  14  is contained in cryogenic container  12  and superconducting coil  22  is immersed in the liquid nitrogen. As heat is absorbed by the liquid nitrogen, the liquid nitrogen initially boils off as gaseous nitrogen  16 , which collects at the top of cryogenic container  12 . When the pressure of the gaseous nitrogen increases to a selected level, it will activate pressure regulator  28 , which permits gaseous nitrogen to flow, under pressure, through conduit  26  and  30  and nozzles  58 , to the prime mover  24 .  
         [0021]    As shown in FIGS. 2A and 2B, in a preferred embodiment, prime mover  24  is a turbine comprising a plurality of disks, mounted closely together in substantially parallel planes. The gaseous nitrogen flows between these disks and induces rotational motion of the prime mover. Prime mover  24  is mounted on disk element  32 , which is mechanically coupled to Faraday disk  44  through shaft  38 , through which rotational motion of the prime mover  24  is coupled to Faraday disk  44 . Faraday disk  44 , which may be formed from copper or other highly conductive material, rotates within the magnetic field developed by electrical current circulating in coil  22 . As a result of the rotation of the Faraday disk through the magnetic field, a voltage is generated between the center and the outer edge of the Faraday disk. As described further below, current flows from the Faraday disk to a user of electrical energy and back to the Faraday disk through electrical conductors applied to the center and outer edge of the Faraday disk.  
         [0022]    Liquid nitrogen, denoted by numeral  14  is contained within cryogenic container  12 , which may comprise a conventional Dewar type vessel  11  and cryogenic barrier  18 , which forms the top of cryogenic container  12 . Dewar type vessel  11  may be a conventional double walled container with a vacuum or a low thermal conductivity material between the walls. Note that FIG. 1 is drawn for the purpose of illustrating the invention and is not intended to be a scale drawing. Cryogenic barrier  18 , which forms the top of the cryogenic container  12  would typically be much smaller in relation to vessel  11  than is shown is FIG. 1. Container  12  is configured for maintaining superconductive coil  22  submerged in the liquid nitrogen. The container  12  must be sealed and of sufficient mechanical strength to withstand the pressure build-up of the gaseous nitrogen as the liquid nitrogen boils off.  
         [0023]    [0023]FIG. 1 shows conduit  20 , through which liquid nitrogen may be added to cryogenic container  12  from an external source (not shown) of liquid nitrogen. Conduit  20  may be conventional cryogenic tubing known to those of ordinary skill in the art. Also shown is level sensor  40  and the cryogenic valve  48  that level sensor  40  controls. When level sensor  40  detects that the level of the liquid nitrogen has fallen below a selected level, level sensor  40  opens cryogenic valve  48  to allow additional liquid nitrogen to flow into cryogenic container  12  from the external liquid nitrogen source. This level is selected to keep the superconductive coil  22  submerged in the liquid nitrogen in order to maintain the superconductivity of the coil. Level sensor  40  is operatively connected to cryogenic valve  48 , typically through an electrically conducting wire  21 .  
         [0024]    In a preferred embodiment, power is generated by rotating a Faraday disk  44  in a magnetic field resulting from current flow through coil  22 . Power for rotating the Faraday disk is generated by the absorption of heat by the liquid nitrogen, which converts a portion of the liquid nitrogen  14  into gaseous nitrogen. Although cryogenic barrier  18  will have low thermal conductivity, the material forming cryogenic barrier  18  is chosen to conduct a limited amount of heat into the liquid nitrogen chamber for converting the liquid nitrogen to a gas at a controlled rate. Because the nitrogen is confined in cryogenic container  12 , pressure will increase in this space as the liquid is converted to a gas. The gaseous nitrogen is held in the cryogenic container until a desired operating pressure is reached. Pressure regulator  28  is set to open at the desired operating pressure so that the gaseous nitrogen flows from conduit  26  to conduit  30  and then through nozzles  58 . As the gaseous nitrogen is propelled through the nozzles  58  it reaches a very high velocity (typically 330 meters per second at about 15 psig, or greater at higher pressures). This high velocity gas now flows through the prime mover  24  and into the center space  54  within the prime mover, and then out to the atmosphere through exhaust conduit  56 . As discussed below, the gaseous flow through prime mover  24  causes rotational motion of the prime mover. This rotational motion is then transferred through shaft  38  to Faraday disk  44 .  
         [0025]    As shown in FIG. 1, safety valve  29  may be included in the gaseous nitrogen flow path so that if for any reason the pressure within cryogenic container  12  exceeds a selected maximum pressure, safety valve  29  will open and release gaseous nitrogen into the atmosphere.  
         [0026]    The electrical energy output of the generator  10  is proportional to the intensity of the magnetic field produced by superconducting coil  22 , which is proportional to the current flow in the coil  22 . Because the current flow that can be generated in a superconducting coil is much greater than the current flow that can be generated in a conventional wire, a much more powerful magnetic field can be produced by a superconducting coil than by conventional wire. A particularly advantageous feature of superconducting coils is their ability to sustain an electrical current in the coil without additional electrical input as long as the coil is below the critical temperature of the superconductive material from which the coil is made. Therefore, once the electrical current has started to flow in the coil, the input connections to the coil can be “shorted” together and, provided the temperature of the coil is maintained below its critical (superconducting) temperature, the current will continue to flow in the coil for very long periods of time. Because of the availability of liquid nitrogen, a high temperature superconducting coil is especially useful for producing the magnetic field in the generator portion of the machine.  
         [0027]    An advantageous mechanical feature of a preferred embodiment of the invention is that the liquid nitrogen which is utilized for maintaining the magnetic field producing coil at a superconducting temperature may also be utilized for developing the mechanical energy for operating the generator. Although a preferred embodiment of the invention is described in terms of using the evaporating cryogenic fluid from cryogenic container  12  for driving the prime mover  24 , those of ordinary skill in the art will understand that the gaseous stream which drives the prime mover may be obtained from a source other than the container in which the cryogenic fluid is stored for maintaining the superconductive coil  22  at a superconducting temperature. For example, the source of the gaseous stream could be another container of evaporating cryogenic fluid.  
         [0028]    A conductive coil, which may be made from a high temperature surperconductive material, such as yttrium barium copper oxide (YBCO), is preferably immersed within liquid nitrogen. Accordingly, superconductive coil  22  is shown mounted on a portion of cryogenic barrier  18  which extends downwardly into the cryogenic container  12 , so that in normal operation, coil  22  will be immersed in the liquid nitrogen, or other cryogenic fluid. Typically, the upper portion of cryogenic container  12  will contain gaseous nitrogen, which is designated by numeral  16  in FIG. 1. The superconductive coil may be cemented to the cryogenic barrier  18  as shown, but it can be fastened within cryogenic container  12  in any manner that will maintain the coil  22  in a stable position relative to Faraday disk  44 . Those of ordinary skill in the art will understand that the mechanism used for holding coil  22  in place must be able to withstand the temperature of the liquid nitrogen, or other cryogenic fluid utilized.  
         [0029]    The construction of an implementation of the coil  22  is shown in FIGS. 3A, 3B and  3 C. Because of the difficulty in forming a wire from yttrium barium copper oxide (YBCO) and other superconductive material, the coil may be formed within a mold comprising ceramic loop  70 , as shown in FIGS. 3A and 3B. Spiral groove  72  may be cut into ceramic form  70 , which may extend to a depth location  74  within the ceramic loop. This spiral groove is shown reaching the top surface of ceramic loop  70  at location  76 , and reaching the bottom of ceramic loop  70  at location  78 . The superconducting coil is formed by filling the spiral groove  72  with the superconductive material. In order to connect the upper end of the spiral loop at location  76  to the lower end of the spiral loop at location  78 , a connective groove  80  may be formed in the ceramic form  70  extending from location  76 , down the interior side of ceramic form  70 , to location  78 , as shown in FIG. 3C. By filling this connective groove  80  with the superconductive material, the upper end  76  and the lower end  78  of the spiral loop are joined together to form a superconductive coil.  
         [0030]    Also shown in FIG. 3C is a small resistance heater  82  mounted in juxtaposition to connective link  80 . As explained below, to initiate operation of the system, a battery (not shown) is connected between terminal  84 , which is electrically connected to location  76  and one end of resistance heater  82 , and terminal  86 , which is electrically connected to location  78  and the other end of resistance heater  82 .  
         [0031]    Although the method for fabricating a superconductive electrical conductor described with reference to FIGS. 3A, 3B and  3 C is described primarily with respect to the fabrication of a coil for implementing the generator described with reference to FIG. 1, the inventive manufacturing method described with reference to FIGS. 3A, 3B and  3 C is equally applicable to the fabrication of superconductive electrical conductors for other applications.  
         [0032]    As shown more clearly in FIGS. 2A and 2B, in a preferred embodiment, prime mover  24  comprises a plurality of disks  23 , which may be made from a high strength aluminum alloy. These disks are affixed together in axial alignment in spaced apart positions, in substantially parallel planes. In one implementation of the invention these disks are affixed together by bolt assemblies  62 , which may comprise shoulder bolts. Bolt assemblies  62  may include spacers  64 , as shown in FIG. 2A, between each of the disks  23 . In a particular implementation of the invention, bolt assemblies  62  also affix the prime mover  24  to support disk  32 . FIGS. 2A and 2B show four bolt assemblies  62 , however, a different number of bolt assemblies may be utilized. The number of disks  23 , the spacing between the disks and the dimensions of the disks may also vary, depending on the required power output, mechanical ruggedness and other design criteria which may be applicable to a particular implementation of the invention.  
         [0033]    Rotational movement of prime mover  24  is generated by the flow of the gaseous nitrogen from conduit  30  through one or more high velocity nozzles  58  and through the space between the disks  23  of the prime mover  24 . The gaseous stream will typically be projected by the nozzles in a direction which is substantially tangential to the edges of the disks  23 . The nozzles may be machined into the wall of the housing structural member  50  within which the disks  23  rotate, rather than separate items connected to the end of conduit  30 . The nozzles  58  may substantially increase the velocity of the gaseous nitrogen stream. The disks  23  are closely spaced apart so that the gaseous flow through the spaces between the disks  23  will drag the disks in the direction of the gaseous flow, and since prime mover  24  is mounted, via support disk  32 , onto shaft  38 , rotational motion of the disks  23  included in the prime mover is generated. Rotational speed of the prime mover assembly increases until the surface speed of the outside edge of the disks  23  reaches almost the same velocity as that of the gaseous jet emanating from the nozzles  58 . To increase the power produced by this prime mover assembly, the number of disks  23  and nozzles  58  may be increased, and the volume of nitrogen flow may be increased accordingly. The gas flow across the surface of the disks  23  drags the disk surfaces along the direction of the gas flow. This action takes place in a “layer” of the gas next to the disk surface. It has been called the “boundary” between the gas and the geometrical surface, hence “boundary layer” effect.  
         [0034]    Although a preferred embodiment of the invention has been described in terms of a prime mover comprising a plurality of closely spaced, parallel, coaxially mounted disks, those of ordinary skill in the art will recognize that a bladed turbine may also be utilized in implementing the invention, as well as other more conventional prime movers which operate on gas expansion.  
         [0035]    The rotational motion of prime mover  24  is transferred to the Faraday disk  44  through shaft  38 . Shaft  38  comprises a bolt-like unit, which may be secured to support disk  32  by nut unit  36  in a conventional nut and threaded shaft configuration. Shaft  38  and nut unit  36  may each be made from stainless steel, copper or other material having similar qualities of strength and ruggedness. Nut  36  may be shaped to facilitate flow of gas from the prime mover through exhaust port  56 . Shaft  38  may be fixedly connected to Faraday disk  44  by brazing, or by a threaded connection or other means known to those of ordinary skill in the art. Shaft  38  and Faraday disk  44  may also be machined as a unitary structure. Bearing  42  is positioned between shaft  38  and housing structural member  50 , to maintain the shaft in alignment and to permit rotational movement of the shaft  38  in sliding engagement with bearing  42 . In a particular embodiment bearing  42  may also be configured to extend into the space between support disk  32  and structural member  50 , so provide clearance so that support disk  32  can rotate freely. In a preferred embodiment, bearing  42  is made from electrically conductive material in order to conduct electrical current which flows through shaft  38  from the center of the Faraday disk. Bearing  42  may be formed from graphalloy, or other material having similar qualities of low thermal expansion, high electrical conductivity and low surface friction.  
         [0036]    Faraday disk  44  is mounted in sliding engagement within bearing  46 . In a preferred embodiment, bearing  46  is made from electrically conductive material in order to conduct current into (or from) the outer edge of the Faraday disk. Bearing  46  may be formed from graphalloy, or other material having similar qualities of low thermal expansion, high electrical conductivity and low surface friction. In a preferred embodiment, bearings  42  and  46  provide a means for transmitting electrical energy from the Faraday disk to an external electrical load, as well as a suitable low friction bearing for the shaft  38  and the Faraday disk  44 .  
         [0037]    As shown schematically in FIG. 4, Faraday disk  44 , which may be made from copper or other highly conductive material, rotates through the magnetic flux lines  60  resulting from current flow in coil  22 . In accordance with a preferred embodiment of the present invention, an intense magnetic field is produced through the use of the superconducting coil. Induction occurs as a magnetic field is changing strength. In accordance with a preferred embodiment of the invention, the rotating portion of electric power generator  10  moves in relation to the stationary magnetic field and hence produces an electrical current. FIG. 4 illustrates in schematic form the generation of a current in a Faraday disk. The magnetic lines of flux denoted by the letter “B”, are shown flowing through the Faraday disk, which is indicated to be rotating in a counterclockwise direction. This rotational movement of the Faraday disk generates an electrical voltage, V, between the center point of the disk, and its outer edge. By positioning a first electrode in contact with the center point of the disk and a second electrode at the outer edge of the disk, a current flow is generated. In the embodiment shown in FIG. 1, bearing  42  is the first electrode and bearing  46  is the second electrode.  
         [0038]    It is well known to those of ordinary skill in the art that the power that may be produced by a Faraday disk is governed by the following formulas:  
         V=sB  (Eq. 1)  
         [0039]    where:  
         [0040]    V=voltage developed across the Faraday disk  
         [0041]    s=rotational speed of disk in revolutions per second, and  
         [0042]    B=magnetic flux in Teslas.  
             I   =     V   r             (     Eq   .              2     )                               
 
         [0043]    where:  
         [0044]    I=current in amperes  
         [0045]    V=voltage developed across the Faraday disk  
         [0046]    r=resistance of external load in ohms  
         [0047]    and:  
         W=IV  (Eq. 3)  
         [0048]    where  
         [0049]    W=output power in watts  
         [0050]    I=current in amperes  
         [0051]    V=voltage developed across the Faraday disk.  
         [0052]    Although a preferred embodiment of the invention has been described in terms of using a Faraday disk for generation of electrical power, those of ordinary skill in the art will understand that other electrical conductor configurations may be utilized. For example, an electrically conducting coil configuration typical of the electrical conducting coils normally used in electrical power generation system could be rotated in the magnetic field generated by the superconducting coil for generating output power.  
         [0053]    Electrical power generator  10  may be powered up as follows. Once the cryogenic container  12  has been filled with liquid nitrogen and level sensor  40  has closed cryogenic valve  48  and stopped the flow of liquid nitrogen into the cryogenic container  12 , electrical energy is supplied to coil  22 . As stated above in the discussion with respect to FIG. 3C, this electrical energy may be supplied from a battery (not shown) which is connected between terminals  84  and  86 . The voltage and current capacity of the battery is selected in accordance with the desired current flow into superconducting coil  22 . Typically, the battery will be connected to terminals  84  and  86  by means of electrically conducting wires which will pass through a conduit (not shown) in cryogenic container  12 .  
         [0054]    As previously stated, resistance heater  82  is connected between terminals  84  and  86 , and when a battery is connected across terminals  84  and  86 , current will flow through coil  22  and through resistance heater  82 . Resistance heater  82  is positioned in juxtaposition to connective link  80 , and will maintain connective link  80  at a temperature above its superconductive temperature. Normally, as current begins to flow from the battery through the superconductive coil  22  and back to the battery, the temperature of the coil  22  will be above its critical (i. e., superconductive) temperature. When the coil  22 , which is immersed in liquid nitrogen, reaches a temperature below its superconductive temperature, the coil becomes superconductive, and the voltage across terminals  84  and  86  will drop to substantially zero, and the electrical power to the resistance heater is thereby substantially removed. The connective link  80  will then cool to a temperature below its critical temperature and connective link  80  will become superconductive. A superconductive coil has now been formed, with a flow path connecting the beginning of the coil at location  76  to the end of the coil at location  78 . The battery may now be disconnected, and the electrical current will continue to flow in coil  22  without any additional current needed from the battery as long as the coil is kept at or below the critical (superconducting) temperature of the material form which the coil is formed  
         [0055]    As the liquid nitrogen in cryogenic container  12  absorbs heat, the liquid nitrogen is continually boiled off to produce gaseous nitrogen. The process of absorption of heat energy from the environment is a process that depends on the difference in temperature between the environment and the liquid nitrogen and the quality of heat conductive paths between the environment and the liquid nitrogen. Heat flows toward the lowest temperature. Hence, the heat from the earth will by nature flow toward the liquid nitrogen and boil the nitrogen, and then continue to heat the gaseous nitrogen until the gaseous nitrogen reaches the ambient temperature on the earth at the location of the generator. The thermal design of electrical power generator  10  will control the rate at which heat flows to the liquid nitrogen. Accordingly, the thermal capabilities of the generator may be designed to accommodate the heat flow required to provide the power desired from the machine.  
         [0056]    Electrical insulating barrier  13  is fabricated from electrically non-conducting material in order to form an electrical barrier between the cryogenic barrier  18  and element  50 . Electrical insulating barrier  13  also functions as a structural element to secure structural element  50  and graphalloy bearing  42  in position. Element  50  is formed of an electrically conducting material, such as stainless steel or copper, and is electrically connected through the graphalloy bearing  42  and shaft  38  to the center of Faraday disk  44 . Cryogenic barrier  18  is connected through graphalloy bearing  46  to the outer edge of Faraday disk  44 . Electrical insulating element  13  provides electrical insulation between cryogenic barrier  18  and element  50 . Current developed by the Faraday disk is conveyed from the center of the Faraday disk, through shaft  38 , graphalloy bearing  42 , structural element  50  and through a first electrical conductor (not shown) to an external electrical power user. The return current path is through a second electrical conductor (not shown), cryogenic barrier  18  and graphalloy bearing  46  to the outer edge of Faraday disk  44 . Element  50  also provides a housing for the prime mover. Element  52  closes the housing and provides an exhaust port for the spent gaseous nitrogen.  
         [0057]    The upper portions of the machine, comprising cryogenic barrier  18 , electrical insulating barrier  13 , structural member  50 , and exhaust cover  52  may also function as heat exchangers in addition to providing the mechanical structure of the machine. In addition, in one embodiment of the invention sufficient resistivity may be built into cryogenic barrier  18  so that as the power output demand from the generator increases and the current flow through cryogenic barrier  18  increases, the heat generated in cryogenic barrier  18  will increase accordingly, thereby providing a proportionate increase in the rate of conversion of the liquid nitrogen to gaseous nitrogen for driving the prime mover. If it is anticipated that a generator may be required to provide power over wide power output range, additional heat exchangers may be included as a part of the generator.  
         [0058]    Uses for the invention may include but are not limited to supplying power for operating an automobile and supplying power to operate the electrical appliances and equipment found in a personal residence. FIG. 5 illustrates the use of the invention for supplying power to an automobile  96 . A liquid nitrogen storage unit, designated by numeral  90 , supplies liquid nitrogen to the generator  92 , which is substantially similar to generator  10  described with reference to FIG. 1. Gaseous liquid nitrogen is exhausted through conduit  100 . The output of the generator  92  supplies the power to the vehicle control and propulsion system  94 , which may be similar to the control and propulsion system utilized in prior art electrically powered automobiles. Depending on the output voltage level from generator  92 , the generator may optionally be applied to a converter  98 , to convert the output of the generator to the appropriate voltage level for operating the automobile. Such converters are well known to those of ordinary skill in the art and will not be described in detail herein  
         [0059]    [0059]FIG. 6 illustrates the use of the invention for supplying power to a residence. As shown in FIG. 6, liquid nitrogen is supplied from liquid nitrogen storage unit  104  to the generator  106 , whose construction is substantially similar to generator  10  described with reference to FIG. 1. The output of generator  106  is supplied to converter  108 , which converts the output from generator  106  to the frequency and voltage required for running a residential electrical system, which typically is 120 or 240 volts, at 50 or 60 Hz. frequency. Such converters are well known to those of ordinary skill in the art and will not be described in detail herein.  
         [0060]    It will be appreciated that various modifications, alternatives, variations, and changes may be made without departing from the scope of the invention as defined in the appended claims. It is intended to cover by the appended claims all such modifications involved within the scope of the claims.