EP1534550A4

EP1534550A4 - Rankine cycle generation of electricity

Info

Publication number: EP1534550A4
Application number: EP02725746A
Authority: EP
Inventors: Paul Lawheed
Original assignee: Sun Trust LLC
Current assignee: Sun Trust LLC
Priority date: 2002-03-14
Filing date: 2002-04-23
Publication date: 2005-10-26
Also published as: EP1534550A1

Abstract

Systems (10) or combinations and methodology for converting solar energy to electrical energy and thermal energy and for converting the resultant thermal energy to electrical energy are disclosed. Systems and methodology for conversion of low temperature thermal energy, wherever obtained, to electrical energy using a Rankine cycle mechanism (42) to drive an electrical generator (56) or to other work in a cost effective way are also disclosed.

Description

RANKINE CYCLE GENERATION OF ELECTRICITY

Related Application

This application is related to copendingU.S. Patent Application Serial No. 09/867,196,

filed May 29, 2001 and entitled CONVERSION OF SOLAR ENERGY, the contents of which are incorporated herein by reference.

Technical Field

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 Art

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.

It has been proposed that flat panel solar converters be used to convert direct sunlight into

thermal or electrical energy.

Pedestal supported flat panels using direct sunlight to generate electricity were part of the

Solar One project.

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, California. Fixed position concave reflectors placed in an array and positioned in side by side rows on an incline have ben proposed. See U.S. Patent No.4,202,322. Such an installation was made at the Federal Correctional Institution at Phoenix, Arizona.

Tiltable elongated concave reflector assemblies have been utilized, such as the one at Barstow, California, owned by FPL Energy SEGS VIII and IX.

Solar Systems comprising bidirectionally controlled Fresnel lens and solar cell assemblies, utilizing direct sunlight, have been proposed. See, U.S. Patent No. 4,649,899, for example. Also see, U.S. Patent No. 4,245,153. Optical detectors for dual axis tracking of the sun are known.

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.

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.

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%).

Disclosure of the Invention

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.

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.

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.

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.

It is a further valuable object to provide a novel energy transforming Rankine cycle mechanism and related methodology.

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

Figure 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;

Figure 2 is a schematic of a thermal-to-electrical energy conversion system within the

scope of the present invention;

Figure 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;

Figure 4 is a perspective of the Rankine cycle mechanism of Figure 3, in its assembled

condition, viewed from the side opposite to Figure 3;

Figure 5 is an exploded perspective of the Rankine cycle mechanism of Figure 3 for

clarity of illustration; and

Figure 6 is a perspective of the Rankine cycle mechanism of Figure 3 with the near side

plate removed, for clarity of illustration. Best Mock for Carrying Out the Invention

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

Ranlcine cycle production of work and/or generation of electricity using a fluid having a

moderately elevated temperature.

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.

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.

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. 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.

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.

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's actions of groups hostile to utilities or nations.

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.

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. Ironically, the best answer to the world'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.

Even though the sun is just beginning to contribute to satisfying the world's energy demands on a large scale, direct sunlight has been powering satellites and spacecraft since 1958. In the 1970'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.

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.

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. 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.

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.

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.

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.

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%).

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 Ranlcine 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.

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.

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.

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 Ranlcine cycle aspects of the present invention.

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%).

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.

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.

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.

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. 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.

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 tlirough 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.

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 Figure 1 is one of several novel systems, generally designated 10, which also implements unique methodology. More specifically, Figure 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. 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.

While any liquid cooled solar electric generator may comprise generator 12, the solar

generators disclosed in the above-mentioned copending U.S. Patent Application Serial 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 Figures 1 and 2.

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 Ranlcine 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 tlirough tube 54.

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.

Reference is now made to Figure 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 Figure 2, when compared with Figure 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 Ranlcine cycle mechanism 42 illustrated in Figure 2 may

be used to turn another device by which other work is done, as depicted at site 66.

Reference is now made to Figures 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. Figures 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.

Exclusive of the housing, the Rankine cycle mechanism shown in Figures 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.

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 Figures 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 88are sized so that at

times during opposite rotation, the projections each comprising surfaces 110 turn into and

through the female cavities 112. See Figure 6.

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 joumaled 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 (Figure 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 (Figure 4) screw fastened at 98 to the plate 72. Caps 96 may be formed any suitable material, such as acceptable synthetic resinous material.

To the contrary, the distal ends of each shaft 43 projects well beyond the exterior surface of plate 76, as best shown in, Figure 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.

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 Figure 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. The mechanical energy or torque, which occurs when shafts 43 rotate, is converted to

electrical energy at generator 56 (Figures 1 and 2) or used to do other work at 66 (Figure 2).

As can best be seen in Figure 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.

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 figure 8 shaped

surface 84 of the central peripheral layer 74, as best shown in Figure 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.

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 Figure 6.

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.

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.

What is claimed and desired to be secured by Letters Patent is:

Claims

1. A method of using solar energy to generate primary and secondary electricity comprising the acts of:

directly converting solar energy to electricity at a solar electric generator;

cooling the solar electric generator with a coolant;

utilizing heat carried away from the electric generator by the coolant to drive a Rankine

cycle generating system to also produce electricity.

2. A method according to Claim 1 wherein the coolant is a liquid and wherein the utilizing act comprises passing the heated coolant as a liquid through a heat exchanger to elevate the temperature of gas being passed through the heat exchanger which drives a Rankine cycle mechanism to produce torque which in turn drives an electricity producing-generator.

3. A method according to Claim 2 wherein the gas comprises steam.

4. A method according to Claim 1 wherein the electricity produced by the directly

converting act is direct current electricity.

5. A method according to Claim 4 further comprising the act of converting the direct

current electricity to alternating current electricity.

6. A method according to Claim 2 wherein the liquid coolant is recirculated through

the solar electric generator and the heat exchanger.

7. A method according to Claim 2 wherein the gas is cooled and thereafter recirculated through the heat exchanger.

8. A method according to Claim 2 wherein the gas is displaced through a cooling

device after passing through the Rankine cycle mechanism and before being returned to the heat exchanger.

9. A method according to Claim 2 wherein the liquid coolant discharged from the

solar generator has a relative low temperature range below the vapor point and the gas is within a temperature range of 80° F or less.

10. A method according to Claim 2 wherein the gas is displaced into the Rankine cycle mechanism at a pressure on the order of 15 psi.

11. A method of using liquid at a moderately elevated temperature to do work

comprising the acts of:

displacing liquid at an elevated temperature, below its vapor temperature through a

liquid-gas heat exchanger;

displacing a gas through the liquid-gas heat exchange to transfer heat from the liquid to

the gas; displacing the gas to rotate a Rankine cycle lobe-displacement mechanism to create

rotation of at least one output shaft; converting the output shaft rotation to work.

12. A method according to Claim 11 further comprising the act of recirculating the

gas through the heat exchanger and the Rankine cycle mechanism.

13. A method according to Claim 11 wherein the third displacing act comprises

rotating two output shafts and the converting act comprises work derived from the rotation of two shafts.

14. A method according to Claim 13 wherein the two output shafts are geared together for common though opposite rotation.

15. A method according to Claim 12 further comprising the act of cooling the gas after it leaves the Rankine cycle mechanism and before it returns to the heat exchanger.

16. A method according to Claim 11 wherein the converting act comprises driving

an electric generator via shaft rotation to obtain electricity.

17. A method of generating electricity by displacing a fluid at a moderately elevated

temperature comprising the acts of:

introducing the fluid at a temperature within a range of up to 100° F and at an influent

pressure within a range on the order of 15 psi into a space between oppositely rotatable lobes

respectively mounted on interconnected shafts within a Rankine cycle mechanism;

applying the pressure of the fluid: (a) first predominantly against one lobe to forcibly

rotate that lobe in a first direction causing the other lobe, through the interconnected shafts, to

oppositely rotate in a second direction and (b) second predominantly against the other lobe to forcibly rotate the other lobe in the second direction causing the one lobe, through the interconnected shafts, to rotate in the first direction; driving an electric generator with one or both shafts to create electricity.

18. A method according to Claim 17 wherein the fluid is a gas.

19. A method according to Claim 18 wherein the gas comprises steam.

20. A method of generating electricity comprising the acts of:

impinging influent fluid under low pressure and at a moderately elevated temperature on

a continuous flow basis against a first shaft-mounted lobe of a Rankine cycle mechanism to forcibly rotate the first lobe and the shaft upon which the first lobe is mounted in a first direction, a second shaft-mounted lobe being caused to oppositely rotate in a second direction as a follower;

thereafter impinging the continuous flow influent fluid against the second lobe to forcibly

rotate the second lobe and the shaft upon which the second lobe is mounted, the first lobe and

the shaft upon which the first lobe is mounted to rotate in the first direction as a follower; generating electricity via shaft rotation derived from the Rankine cycle mechanism.

21. A method according to Claim 20 further comprising the act of elevating the temperature of the fluid in a heat exchanger using a liquid at a temperature below its boiling

point.

22. A method of generating electricity using a Ranlcine cycle mechanism comprising

the acts of: impinging influent fluid having an elevated temperature first against one lobe and then

another lobe to rotate the lobes in opposite directions and to turn at least one output shaft;

using the rotation of the at least one output shaft to drive a generator by which electricity

is produced.

23. A system for using solar energy to co-generate primary and secondary electricity comprising the acts of:

a solar generator which directly converts solar energy to electricity;

a cooling unit for cooling the solar electric generator with a coolant;

a Rankine cycle mechanism which utilizes heat derived from the coolant to drive a generator to also produce electricity.

24. A system according to Claim 23 wherein the coolant comprises a liquid, the

cooling unit comprises a heat exchanger by which the elevated temperature of the liquid coolant increases the temperature of a gas being passed through the heat exchanger, and the Rankine cycle mechanism comprises at least one output shaft the rotation of which drives the generator.

25. A system according to Claim 24 wherein the gas comprises steam.

26. A system according to Claim 23 wherein the electricity produced by the solar

generator is direct current electricity.

27. A method according to Claim 26 further comprising a direct current-to-alternating

current converter by which the direct current electricity is transformed to alternating current

electricity.

28. A method according to Claim 24 wherein the cooling unit comprises a recirculator

by which liquid coolant is continuously recirculated through the solar electric generator and the

heat exchanger.

29. A system according to Claim 24 wherein the cooling unit comprises a recirculator

by which the gas is continuously recirculated through the heat exchanger and the Ranlcine cycle mechanism.

30. A system according to Claim 29 wherein the cooling unit further comprises a

second heat exchanger whereby the gas is continuously displaced through the second heat

exchanger after passing through the Rankine cycle mechanism and before being returned to the

first heat exchanger.

31. A system according to Claim 24 wherein the liquid coolant discharged from the solar generator has a relative low temperature range below its vapor temperature and the gas is within the temperature range below the temperature of the liquid coolant.

32. A system according to Claim 24 wherein the gas is displaced into the Rankine cycle mechanism at a pressure of on the order of 15 psi.

33. A system for using liquid at a moderately elevated temperature to do work

comprising:

liquid-gas heat exchange through which a liquid at an elevated temperature below its

vapor point is displaced and through which a gas is displaced to transfer heat from the liquid to the gas;

a Rankine cycle lobe-displacement mechanism using the gas passed therethrough, after

discharge from the heat exchanger, to rotate at least one output shaft;

a device driven by the shaft rotation to do work.

34. A system according to Claim 33 further comprising a pump by which wherein the

gas is recirculated through the Ranlcine cycle mechanism and the heat exchanger.

35. A system according to Claim 34 further comprising a gas cooler for cooling the gas after it leaves the Rankine cycle mechanism and before it returns to the heat exchanger.

36. A system according to Claim 33 wherein the Rankine cycle mechanism comprises

two oppositely rotated output shafts both of which drive the work device.

37. A system according to Claim 36 wherein the Rankine cycle mechanism comprises

two interconnected shaft-mounted, oppositely rotating gears non-rotatably respectively connected

to two output shafts for common though opposite rotation.

38. A system according to Claim 33 wherein the work device comprises an electric

generator turned by rotation of the at least one shaft to obtain electricity.

39. A system for generating electricity by displacing a fluid at a moderately elevated

temperature comprising the acts of:

a Ranlcine cycle mechanism into which the fluid is introduced at a temperature within a

range on the order of 100 ° F or less and at a pressure within a range of on the order of 15 psi into

a space between oppositely rotatable lobes respectively mounted on interconnected shafts of the

Ranlcine cycle mechanism;

such that the pressure of the fluid is: (a) first applied against one lobe to forcibly rotate

that lobe in a first direction causing the other lobe, through the interconnected shafts, to oppositely rotate in a second direction and (b) then is applied against the other lobe to forcibly rotate the other lobe in the second direction causing the one lobe, through the interconnected shafts, to rotate in the first direction; an electric generator connected to one or both shafts to create electricity.

40. A system according to Claim 39 wherein the fluid is a gas.

41. A system according to Claim 40 wherein the gas comprises steam.

42. A system for generating electricity comprising:

a Rankine cycle mechanism which receives influent fluid under low pressure and a

moderately elevated temperature on a continuous flow basis such that the fluid: (a) first against a first shaft-mounted lobe of the Ranlcine cycle mechanism to forcibly rotate the first lobe and

the shaft upon which the first lobe is mounted in a first direction, a second lobe shaft-mounted being caused by said rotation of the first lobe to oppositely rotate in a second direction as a

follower and (b) thereafter against the second lobe to forcibly rotate the second lobe and the shaft

upon which the second lobe is mounted, the first lobe and the shaft upon which the first lobe is

mounted being caused by said rotation of the second lobe to rotate in the first direction as a follower; an electric generator connected to one or both shafts to generate electricity due to shaft rotation.

43. A system according to Claim 42 further comprising a heat exchanger by which

the temperature of the fluid is elevated using a liquid at a temperature below its boiling point

before introduction into the Rankine cycle mechanism.

44. A system for .generating electricity comprising a Ranlcine cycle mechanism

comprising interconnected oppositely rotating shaft mounted lobes such that influent fluid having

an elevated temperature is impinged first against one lobe and then the other lobe to concurrently

rotate the lobes in opposite directions to turn the shafts and a generator rotated by one or both

output shafts to drive the generator to create electricity.