Patent Publication Number: US-2004055300-A1

Title: Rankine cycle generation of electricity

Description:
RELATED APPLICATION  
     [0001] This application is related to copending U.S. patent application Ser. No. 09/867,196, filed May 29, 2001 and entitled C ONVERSION  OF S OLAR  E NERGY,  the contents of which are incorporated herein by reference. 
    
    
     
       FIELD OF INVENTION  
       [0002] The present invention relates generally to the generation of electricity and more particularly to: (a) solar generation of electricity in combination with Rankine cycle generation of electricity; and (b) use of a Rankine cycle mechanism to generate electricity or do other work.  
       BACKGROUND  
       [0003] Solar energy is freely and daily available. It is a clean, non-polluting source of energy. Providing a reliable, long term, cost effective, efficient way of using sunlight to obtain electrical and thermal power has long been an unsolved problem, until the present invention.  
       [0004] It has been proposed that flat panel solar converters be used to convert direct sunlight into thermal or electrical energy.  
       [0005] Pedestal supported flat panels using direct sunlight to generate electricity were part of the Solar One project.  
       [0006] A circular, but concave reflector mounted on a single column or pedestal has been proposed. This approach was used on the Soleras water desalination project in Saudi Arabia and on the Solar Two project in Dagget, Calif.  
       [0007] Fixed position concave reflectors placed in an array and positioned in side by side rows on an incline have ben proposed. See U.S. Pat. No. 4,202,322. Such an installation was made at the Federal Correctional Institution at Phoenix, Ariz.  
       [0008] Tiltable elongated concave reflector assemblies have been utilized, such as the one at Barstow, Calif., owned by FPL Energy SEGS VIII and IX.  
       [0009] Solar Systems comprising bidirectionally controlled Fresnel lens and solar cell assemblies, utilizing direct sunlight, have been proposed. See, U.S. Pat. No. 4,649,899, for example. Also see, U.S. Pat. No. 4,245,153. Optical detectors for dual axis tracking of the sun are known.  
       [0010] The above-identified proposals and installations have failed to provide reliable, low cost, efficient, variable capacity systems by which solar energy is converted to electrical energy. A long felt need has existed for solar energy conversion plants which are reliable, efficient, cost effective and size variable to meet both low and high capacity demands for thermal and electrical energy.  
       [0011] Further, the prior art has failed to maximize production of electricity from a solar generator by not using effluent coolant (by which the temperature of the solar generator is controlled) as a secondary source for producing additional electricity. Also, the prior art fails to meaningfully identify a commercial way by which a heated coolant, having only a moderately elevated temperature, can be used to cost effectively produce electricity or do other work.  
       [0012] Heretofore, the Rankine cycle principle has been applied to convert thermal energy into mechanical energy into electricity only in very expensive complex plants comprising steam driven turbines typically operating within a temperature range of 850° F. to 1100° F., under high pressure. Fossil fuels are used to drive boilers which produce the high temperature, high pressure steam. Fossil fuel conversion efficiencies of these types of installations may be as high as approximately thirty seven percent (37%).  
       BRIEF SUMMARY AND OBJECTS OF THE PRESENT INVENTION  
       [0013] In brief summary, the present invention overcomes or substantially alleviates long term problems of the prior art by which solar energy is cost effectively converted to electrical energy and thermal energy and the thermal energy is thereafter converted to electrical energy as well. The present invention also provides for conversion of low temperature thermal energy, wherever obtained, to electrical energy using a novel Rankine cycle mechanism to drive an electrical generator in a cost effective way. The Rankine cycle mechanism can do other work as well. The present invention provides reliable, cost effective ways for conversion of solar energy and thermal energy to electricity, where the size of the system can be correlated to the desired capacity.  
       [0014] With the foregoing in mind, it is a primary object of the present invention to overcome or substantially alleviate long term problems of the prior art by which solar energy is converted to thermal energy and electrical energy and the thermal energy is thereafter converted to electrical energy.  
       [0015] Another paramount object of the present invention is to provide reliable, cost effective systems and methods for conversion of solar energy to electricity and thermal energy and to thereafter use the thermal energy to create additional electricity or do other work, where the size of any such system can be correlated to a desired capacity.  
       [0016] Still another important object is to provide systems and methods for the conversion of low temperature thermal energy, wherever obtained, to electrical energy or do other wok using a novel Rankine cycle mechanism by which a generator is driven or another work performing mechanism is driven, in a cost effective way.  
       [0017] It is a further valuable object to provide a novel energy transforming Rankine cycle mechanism and related methodology.  
       [0018] These and other objects and features of the present invention will be apparent from the detailed description taken with reference to accompanying drawings. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0019]FIG. 1 is a schematic of a solar-to-electrical and thermal energy conversion system within the scope of the present invention, where the thermal energy is converted to electricity or used to do other work;  
     [0020]FIG. 2 is a schematic of a thermal-to-electrical energy conversion system within the scope of the present invention;  
     [0021]FIG. 3 is a perspective of a Rankine cycle mechanism, in its assembled condition, viewed from the mechanical output side, with the exterior housing removed, constructed in accordance with the principles of the present invention;  
     [0022]FIG. 4 is a perspective of the Rankine cycle mechanism of FIG. 3, in its assembled condition, viewed from the side opposite to FIG. 3;  
     [0023]FIG. 5 is an exploded perspective of the Rankine cycle mechanism of FIG. 3 for clarity of illustration; and  
     [0024]FIG. 6 is a perspective of the Rankine cycle mechanism of FIG. 3 with the near side plate removed, for clarity of illustration.  
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS  
     [0025] The present invention is specifically related to solar generation of electricity in combination with secondary generation of electricity, or the doing of other work, using heated coolant from the solar generator in conjunction with a Rankine cycle mechanism and also to Rankine cycle production of work and/or generation of electricity using a fluid having a moderately elevated temperature.  
     [0026] The present invention utilizes, in some forms, the free and limitless energy of the sun to produce electricity and thermal energy. The scale of commercial installations of the present invention can be tailored to the need, ranging from small stand alone systems for residential and small business use to intermediate sized plants for plant or factory use to massive assemblies design to supplement the supply of electricity or to mitigate against if not eliminate an electrical energy crisis, such as the recent one in California. The present invention is economical to install and maintain, is reliable and not maintenance-intensive, is efficient and cost effective to operate and does not pollute the environment. The sun is not a consumable resource.  
     [0027] Using the present invention, businesses, industrial plants, retail and office buildings, homes, farms and villages can produce some, if not all, of their own electrical power, and avoid one of the largest if not the largest uncontrollable cost of doing business today—the ever-escalating price of purchased electrical power generated from fossil and nuclear fuels.  
     [0028] This invention is capable of making significantly more energy per square foot than conventional solar collectors. Prior art flat plate collectors are incapable of co-generating the large amounts of thermal energy that the present concentrating photovoltaic generating systems make, which thermal energy, in accordance with the present invention can be converted to electrical energy as well.  
     [0029] Until now, remote installations have been faced with a difficult choice, i.e. pay the prohibitive costs of bringing in utility power, or depend on costly, noisy, and hard to maintain pollution-creating diesel, gas or propane driven electrical generators. The present invention is a better choice, which can be scaled or sized to independently produce as much electrical energy as needed on site, such as the energy needed to power a home or business, pump water, irrigate land and run remote communication installations.  
     [0030] Unlike centralized forms of power generation, de-centralized use of on-site solar obtained electrical power needs no far-flung distribution network of gigantic towers and high voltage lines. Instead it utilizes a universally available asset—sunshine.  
     [0031] Decentralized sunlight-derived electrical power can free users from the effects of peak-hour brown-outs, and from the possibility of total black-outs caused by operator error, system breakdowns or planned terrorist&#39;s actions of groups hostile to utilities or nations.  
     [0032] The cost of the generating equipment itself used in the production of power for a building can be amortized over the life of the building, as part of debt financing (mortgage). Amazing as it may seem, one of the largest and most uncontrollable costs a building owner faces is the ever-escalating cost of electrical power. Using the present invention, one actually has the ability to eliminate most of the cost of purchased electrical power now and for years to come.  
     [0033] When land and water were plentiful and labor was cheap, little was known about the delicate balance existing between the environment and the extraction, burning, and wasting of non-renewable fuels. Now it is all too apparent that our supply of fossil fuels is limited—and that these sources are causing damage to our atmosphere, water supplies, and food chain—damage that is or may soon become irreversible. The costs, too, for fossil fuels continue upward as the more accessible fuel deposits are consumed, and as the costs for machinery, labor, and transportation continue to rise around the world.  
     [0034] Ironically, the best answer to the world&#39;s need for energy has always been the sun. The sun can satisfy a significant percentage of our energy requirements while helping us to become independent of the negative aspects inherent in conventional electrical power generation. Switching to solar-derived electrical power will reduce the pollution produced by coal, oil and nuclear fuels. It will also slow the use of coal and oil and allow us to conserve these resources for more later and perhaps valuable uses. Harnessing the sun will also reduce, or eliminate, the need for nuclear power and mitigate its many risks and problems.  
     [0035] Even though the sun is just beginning to contribute to satisfying the world&#39;s energy demands on a large scale, direct sunlight has been powering satellites and spacecraft since 1958. In the 1970&#39;s the first terrestrially-directed sunlight photovoltaic devices supplied power to locations too remote to have ties to utility lines. Then, as the solar industry developed more efficient silicon cells and generators, larger grid-connected direct sunlight installations became practical.  
     [0036] The present invention is not space-intensive. The present invention, in some forms, can be mounted on an existing rooftop so that it essentially takes up no additional space at all. Ground-mounted systems on a pad or superimposed above a parking lot are also options as well. Column mounting is a further option.  
     [0037] Various embodiments of the present invention may be used in conjunction with residences, office buildings, manufacturing facilities, apartment buildings, schools, hospitals, remote communications, telemetry facilities, offshore platforms, water pumping stations, desalination systems, disinfection systems, wilderness camping, headquarters installations, remote medical facilities, refrigeration systems, farms and dairies, remote villages, weather stations, and air conditioning systems, to name a few.  
     [0038] The present invention is also useful in: (a) providing cathodic protection against galvanite corrosion, (b) storage of electrical energy in batteries, in some circumstances and (c) generation and sale of electricity to utility companies.  
     [0039] The sun is an energy source that, unlike fossil fuels, is free each day to whatever generation site is selected. It does not need to be mined, transported, refined, burned or purchased. So the costs for all these steps to produce energy are eliminated. Gone, too, are all forms of pollution. There are no particulates or gases vented into the atmosphere. Nor is there a need for millions of gallons of cooling water. (The small amount of liquid coolant used to cool the solar cells actually becomes a second form by which electrical power may be co-generated. In other words, production of thermal energy carried away by the coolant may be used to create additional electrical power.) Preferably, the liquid coolant is recirculated and reused to conserve the coolant There is no discharge of massive amounts of hot water into coastal waters to elevate the normal temperature and alter and perhaps destroy the habitats and food chains of coastal marine life. With solar energy, there are no wastes of any kind to be removed or buried in mines or dumped at sea, so there are few, if any, health risks to our generation or future generations.  
     [0040] Various embodiments of the invention are modular, allowing any installation to be large, medium or small so as to meet the exact needs of the installation for electrical energy. The electricity produced by solar cells of a solar electrical generator is direct current (DC), which, when appropriate, may be transformed into alternating current (AC) using an inverter or DC-to-AC converter. The electricity produced from thermal energy using a Rankine cycle mechanism according to the present invention may be DC, AC or three phase AC, depending on the type of generator selected for use with the Rankine cycle mechanism.  
     [0041] The prior art has failed to maximize production of electricity from a liquid cooled solar generator in that the coolant has not been used to co-produce additional electricity, or as a source by which other types of work can be done. The prior art fails to meaningfully identify a commercial way by which a heated liquid having only a moderately elevated temperature can be used to cost effectively produce electricity or do other work.  
     [0042] Previously, the Rankine cycle principle has been limited to conversion of thermal energy into mechanical energy, and thence into electrical energy, only in expensive, complex plants comprising steam driven turbines typically operated within the range of 850° F. to 1100° F., under high pressure. Fossil fuels often drive boilers which produce the high temperature, high pressure steam. Fossil fuel conversion efficiencies of these types of installations can be as high as approximately thirty seven percent (37%).  
     [0043] The present invention overcomes or substantially alleviates the long term problems of the prior art which failed to use solar energy to cost effectively convert the same to electrical energy and thermal energy as well, and failed to use the thermal energy to co-generate electricity. The present invention provides for conversion of low temperature thermal energy, however obtained, to electrical energy using a novel Rankine cycle mechanism to drive an electrical generator in a cost effective way. The mechanical energy of the Rankine cycle mechanism can do other work as well. The present invention provides reliable, cost effective ways for conversion of solar energy and/or thermal energy into electricity, where the size of the system can be cost effectively correlated to the desired capacity. The Rankine cycle aspects of the present invention employ a coolant comprising a low temperature heated liquid. The Rankine cycle mechanism drives a generator to produce electricity of the type desired. The low temperature heated liquid may be passed along a closed loop through a heat exchanger where heat is transferred from the liquid to a gas which, in turn, is displaced along another closed loop through the Rankine cycle mechanism. The heated liquid will have a temperature below its vapor point, e.g. the temperature of the liquid, when the liquid is water, will be 210° F. or less. The gas may be within the range of 50° F.-80° F., typically.  
     [0044] When the Rankine cycle aspects of the present invention are used in conjunction with a solar generator, there is an estimated thirty percent increase in the overall amount of electricity generated.  
     [0045] Generation of electricity in accordance with the present invention, allows for delivery of the energy at desired points in time, for example, when conventional sources of energy are inadequate, such as during peak load periods of time, or during blackouts or in settings where access to conventional electricity is either difficult or impossible.  
     [0046] The heated liquid can be stored in one or more insulated containers or tanks and used later at selected times to produce electricity using the Rankine cycle aspects of the present invention.  
     [0047] The Rankine cycle mechanism, in a presently preferred form, comprises a twin rotor, positive displacement device operated by displacement of low temperature fluid heated by liquid coolant used to cool the solar cells of a solar generator. Other sources of heated liquid having a temperature below the vapor point may be used to drive the Rankine cycle mechanism. Preferably, the heated liquid, when comprising a coolant used with a solar generator, is recirculated between the solar generator and heat exchanger. Preferably, the gas, passed through the same heat exchanger, is recirculated not only through the Rankine cycle mechanism but through a cooling tower or condenser as well before being returned to the coolant-gas heat exchanger, which causes the gas to expand and, therefore, aids in the gas being displaced through the Rankine cycle mechanism. Thus, both the coolant and the gas are contained within their respective closed loops, with the system being predicated upon low temperature, low pressure, pollution free operational characteristics. The overall efficiency of this system is projected to be over forty two percent (42%).  
     [0048] Thus, the present invention concerns itself with using solar energy to co-generate both primary and secondary electricity through conversion, at a solar electric generator, of solar energy to electrical energy and deriving further electricity by using the thermal energy, of a coolant used to control the temperature of the solar electrical generator, to drive a Rankine cycle generating system. In lieu of the secondary electricity, the coolant, at moderately elevated temperatures, can drive another mechanism which does other work. The coolant liquid will have a temperature below its vapor point and gas, heated by the coolant in a heat exchanger, will have a low temperature which may be within the range of 50° F.-80° F.  
     [0049] The Rankine cycle system comprises a Rankine cycle mechanism comprised of shaft-mounted lobes, turned oppositely by successively applying the force of the heated gas to first one lobe and then to the other. The shafts upon which the lobes are respectively mounted are preferably interconnected by toothed wheels or gears so that rotation of one shaft mechanically causes an opposite rotation of the other shaft at the same speed and vice versa. The lobes are constructed so that there is no “blow-by” effect. Shaft rotation (mechanical energy) is used to do work, including but not limited to the rotation of a commercially-available electric generator.  
     [0050] After the heated gas has been used to drive the Rankine cycle mechanism, in the presently preferred embodiment, the gas is cooled in a cooling tower or the like, to which the liquid coolant is not directed.  
     [0051] The continuous flow of the coolant and the gas takes place in a closed system comprised respectively of a closed liquid flow loop and a closed gas flow loop. Thus, nothing is emitted to the environment or atmosphere which could potentially be harmful.  
     [0052] The electricity produced from commercial solar generators is DC, requiring use of a DC-to-AC converter to obtain AC electricity. The electricity derived from rotation of the Rankine cycle mechanism can be tailored as desired and may be used to produce any type electricity desired. The nature of the electricity produced as a result of rotation of the Rankine cycle mechanism will be determined by the nature of the generator selected for use.  
     [0053] A second heat exchanger (the cooling tower) comprises part of one of the disclosed system through which the gas is continuously displaced. The gas is also displaced through a first heat exchanger where heat from the liquid coolant, passed continuously but separately passed through the first heat exchanger is transferred to the gas. Displacement of the gas through its loop is by pump driven circulation, or by temperature differential or both. Circulation of the liquid coolant is by pump.  
     [0054] Specific reference is now made to the Figures wherein like numerals are used to indicate like parts throughout. Specifically, illustrated in diagrammatic or schematic form in FIG. 1 is one of several novel systems, generally designated  10 , which also implements unique methodology. More specifically, FIG. 1 illustrates a solar electric generator  12 , through which liquid coolant is circulated to cool solar cells. The liquid coolant is illustrated as flowing within a closed loop comprising an influent tube  14 , a path through the generator  12  where heat created in a solar-to-electric process is transferred to the coolant, through an effluent tube  16 , and thence a pump  18 , a heat exchanger influent tube  20 , and the interior of an insulated storage tank/expansion heat exchanger  22 , in separation from the fluid in the form of gas circulated through coils  24  also disposed within the interior of the tank/heat exchanger  22 . If desired the liquid in heat exchanger  22  may be contained in a coil juxtaposed the gas coil  24 . The liquid coolant may be water having an elevated temperature below boiling. Output from a fuel cell may comprise the liquid introduced at tube  40 .  
     [0055] The size of the tank/heat exchanger  22  may be a variable, ranging from extremely large to relatively small, depending upon design criteria. The smaller the tank/heat exchanger, the lower its storage capacity for the liquid coolant, the temperature of which is below the vapor point. The larger the tank the greater the storage capacity. The closed loop in which the liquid coolant is circulated accommodates, if desired, continuous circulation of coolant during the periods when the solar electric generator  12  is exposed to sunlight. During darkness or heavy overcast, the heated liquid coolant at the interior  26  of the tank/heat exchanger  22  can remain static, without circulation with the pump  18  off, as the expandable gas is displaced through the coils  24 , in a manner and for purposes yet to be more fully described. The flow of the coolant and the gas is laminar, not turbulent. Heated liquid can also be stored in insulated tanks other than or in addition to tank  22  for Rankine cycle generation of electricity during darkness or cloudy days. In this way, storage of generated electricity in batteries can be eliminated or minimized.  
     [0056] While any liquid cooled solar electric generator may comprise generator  12 , the solar generators disclosed in the above-mentioned copending U.S. patent application Ser. No. 09/867,196 may be utilized. The photovoltaic solar cells of these solar generators produce electricity, in a manner well understood, which is output from generator  12  along electric cable  28 . This electricity is DC and can be used as such to drive DC devices, if desired. However, if AC electricity is desired, the DC electricity in line  28  may be converted at DC-to-AC converter  30  and transmitted thereafter as AC along cable  32  to either a utility interconnect  34  and thence along cable  36  to a utility grid or used on site, as depicted at  38  in FIGS. 1 and 2.  
     [0057] The heat transfer coils  24  through which the expandable gas mentioned above passes is part of a closed loop comprising seriatim, in the direction of flow beginning with the coil  24 , a gas discharge tube  40 , a Rankine cycle mechanism  42 , a tube  44 , through which gas discharge from the Rankine cycle mechanism  42  is displaced and from which the gas is introduced into a cooling coil  46  disposed in the interior  47  of a conventional cooling tower (heat exchanger)  48 . Effluent gas from the cooling tower  48  is displaced along tube  50 , through pump  52 , if used, and once more introduced into the heating coil  24  through tube  54 .  
     [0058] The output from the Rankine cycle mechanism  42  is used to drive a commercially available generator  56 . As stated above, electricity derived from the generator  56  may be used in any suitable way, such as but not limited to site use, at  38  or sold to a utility company and communicated through the utility interconnect  34  to a utility grid system along cable  36 .  
     [0059] Reference is now made to FIG. 2, which illustrates a second system, generally designated  60 , in accordance with principles of the present invention. A number of the components of the system  60  are identical to components of system  10 , which are described above. Therefore, no further description of these components is needed at this juncture. Accordingly, only the differences found in FIG. 2, when compared with FIG. 1, will be explained. Independent of source, heated liquid having a temperature below the vapor temperature thereof, is introduced along tube  20 ′ into the interior  26  of the tank/heat exchanger  22 . The source of the heated liquid delivered through tube  20 ′ can be any source such as geothermal water, discharged from any type of temperature lowering system, etc. The heated influent liquid can be passed through tank/heat exchanger  22  once or several times as deemed appropriate by those skilled in the art. The heated liquid delivered through influent tube  20 ′ may also be stored, as explained above in tank/heat exchanger  22 . The liquid with the interior  26  of tank/heat exchanger  22 , when discharged, is discharged through effluent tube  14 ′. In situations where tank/heat exchanger  22  has inadequate heated liquid storage capacity, the quantity of heated liquid being processed or stored may be enlarged by using one or more insulated storage tanks  62 , the contents of which is returned to the interior  26  of the tank/heat exchanger upon demand, using pump  64 . In any event, heated liquid contained within the interior  26  of tank/heat exchanger  22 , either in static position or being circulated therethrough, transfers heat to the previously mentioned gas passing through coils  24 . Displacement of the heated gas drives the Rankine cycle mechanism  42 , as explained above, such that electricity can be obtained when the Rankine cycle mechanism  42  turns generator  56 , which electricity can be communicated through cable  57  for on-site or nearby use or through cable  59  to utility interconnect  34 . In addition or in concert with driving generator  56 , the Rankine cycle mechanism  42  illustrated in FIG. 2 may be used to turn another device by which other work is done, as depicted at site  66 .  
     [0060] Reference is now made to FIGS. 3 through 6, which illustrate one appropriate form of the Rankine cycle mechanism  42 , fashioned in accordance with the principles of the present invention. In some embodiments, the mechanism  42  provides the advantage of portability. While the capacity and size of the mechanism  42  may vary, RPM within the range of 200-5000 producing 5 horsepower can be produced. FIGS. 3 through 6 depict the illustrated Rankine cycle mechanism  42 , with exterior side housings removed. The side housings are essentially opposite clamshells with aperture peripheral flanges, which, when assembled, prevent entry of debris and protect against injury. The side housings are respectively secured at the respective apertured flanges by screws which threadedly pass through the apertures of the flanges and aligned sequential threaded apertures  70  in the other components of the mechanism.  
     [0061] Exclusive of the housing, the Rankine cycle mechanism shown in FIGS. 3 through 6 comprises three successive contiguous plates  72 ,  74  and  76 . Plates  72 ,  74  and  76  are relatively thin and planar, sized to create a close tolerance fit between the central plate  74  and the two exterior side plates  72  and  76  to thereby prevent fluid leakage at interfaces  78  and  80 . Accordingly, plates  72  and  76  have interior and exterior smooth flat interior and exterior surfaces and are preferably formed of a suitable metal, which is not subject to corrosion and does not significantly expand due to the elevated temperature of the fluid passing through the mechanism  42  via influent tube  40  and effluent tube  42 . A pressure at influent tube  40  of 15 psi under some circumstances may be suitable. Suitable metals for fabrication of plates  72  and  76  comprise aluminum, steel, and brass. One or both plates  72  and  76  may, in the alternative, be formed of a suitable dimensionally stable rigid synthetic resinous material, such as ABS or polytetrafluoroethylene, or composite materials may be used.  
     [0062] While other materials could be used to form layer  74 , presently a wear resistant, dimensionally stable rigid and durable synthetic resinous material such as ABS, or polytetrafluoroethylene is preferred. Composite materials may also be used to form layer  74 . Layer  74 , unlike layers  72  and  76 , is peripheral only, comprising a central, figure 8-shaped hollow interior  84 , accommodating receipt and the close tolerance rotation of two adjacent, interfunctional lobes  86  and  88 , as explained later in greater detail. See FIGS. 5 and 6. Lobes  86  and  88  may be formed of rigid dimensionally stable synthetic resinous material, metal or composites. The central layer  74  also comprises an interior influent discharge port  120 , in open fluid communication with influent tube  40  by which the fluid in tube  40  is introduced successively into four lobe cavities, as explained herein in greater detail. The central layer  74  also comprises an effluent port  122  in open communication with discharge tube  42 , for the purpose explained above. The male projections of the two lobes  86  and  88  comprise surfaces  110  and cavities  112 , defined by surfaces  114  and  116 . The lobes  86  and  88  are sized so that at times during opposite rotation, the projections each comprising surfaces  110  turn into and through the female cavities  112 . See FIG. 6.  
     [0063] The oppositely rotating, intermeshing lobes  86  and  88  are non-rotatably connected, respectively, to the two parallel shafts  43 , in any conventional way, such as by use of a press-fit race  89 , or a key/keyway or set screw interconnection. The illustrated race  89  projects beyond the associated lobe  86  or  88 . The shafts are rotatably journaled in apertures  94  of the outside plates  72  and  76 , respectively, using bushings  90  and  92 , one at each end of each shaft fitted for rotation into apertures  94  (FIG. 5) in each of the two side plates  72  and  76 . The bushings  90  and  92  are slotted at  95  so that the radially size can be adjusted, by loosening or tightening an associated set screw  91  which threadedly crosses the slot to thereby size the bushing for close tolerance rotation in the apertures  94  while being non-rotatably connected to the associated shaft  43 . The two shafts  43 , respectively, terminate at their proximal ends a very short distance outside the plate  72 . These proximal shaft ends are concealed by a pair of caps  96  (FIG. 4) screw fastened at  98  to the plate  72 . Caps  96  may be formed any suitable material, such as acceptable synthetic resinous material.  
     [0064] To the contrary, the distal ends of each shaft  43  projects well beyond the exterior surface of plate  76 , as best shown in FIG. 3. Thus, the distal ends of the shafts are output shafts, the rotation or torque of which is converted to mechanical energy from which desired work is obtained, such as the generation of electricity.  
     [0065] A pair of interconnected toothed wheels or gears  100  are non-rotatably connected, respectively, to the two shafts  43  using any suitable technology. Set screws in threaded apertures  101  are illustrated in FIG. 3 as being used. Accordingly, when the lobes oppositely rotate, the two shafts  43  oppositely rotate and the two gears, interconnected at site  102 , also oppositely rotate and at the same speed. As explained hereinafter in greater detail, the positive displacement, driving force of the influent fluid entering at port  40  drives one of the lobes at a first point in time, with the other lobe following by reason of the gear interconnection at site  102 . Thereafter, the influent fluid drives the second lobe, with the first lobe becoming a follower, again by reason of the interconnection of gear teeth  104  at site  102 .  
     [0066] The mechanical energy or torque, which occurs when shafts  43  rotate, is converted to electrical energy at generator  56  (FIGS. 1 and 2) or used to do other work at  66  (FIG. 2).  
     [0067] As can best be seen in FIG. 6, the lobes  86  and  88  are identical in the embodiment illustrated and described. Three hundred sixty degree (360°) rotation of each lobe will entail two driver intervals for each lobe and two idler or follower intervals for each lobe.  
     [0068] To prevent blow-by, each lobe comprises opposite maximum diameter male radial wall surfaces or edges  110 , which rotate in close tolerance relationship with the FIG. 8 shaped surface  84  of the central peripheral layer  74 , as best shown in FIG. 6. Because of the close tolerance relationship between surfaces  110  and surface  84 , there is no material “blow-by” loss of pressure or fluid flow during rotation.  
     [0069] Further, each lobe  86  and  88  comprise opposed kidney-shaped slots or grooves  112 . Slots  112  comprise a central reduced diameter radial surface  114  and forward and rear rounded surfaces  116  each of which merges with the associated outer radial surface  110  and the associated surface  114 . The driving force of the influent fluid entering at influent tube  40  and interior port  120  is predominantly applied to the leading surface  116  within one groove  112  of the lobe  86  or  88  being driven by the fluid pressure at that point in time. The trailing surface  116  of the one groove  112  will cause discontinuance of influent fluid pressure against the associated leading surface  116  of the same kidney-shaped groove  112 , once the trailing surface  116  passes the interior discharge port  120  and temporarily closes that groove  112  to fluid access from port  120 . At this point in time, the leading surface  116  of one of the grooves  112  of the other lobe will be placed in communication with the influent fluid under pressure entering the Rankine cycle mechanism at interior port  120 , so that the second lobe becomes the driver and the first lobe becomes the follower, as explained above. This alternation in driven lobe/follower lobe sequence occurs twice per lobe for each 360° rotation of the two lobes  86  and  88 . Spent driving fluid is discharged through interior port  122  and out through effluent tube  44 . See FIG. 6.  
     [0070] The fluid used to drive the lobes  86  and  88  may be of any suitable composition. A plurality of mechanisms  42  can be used in series, in parallel or both. Gas, including steam, is preferred, but under certain circumstance liquid may be used.  
     [0071] The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.