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BACKGROUND OF THE INVENTION
Although it has long been known that the sun is a virtually inexhaustible
energy source, very little serious effort has been applied to practically
utilizing solar energy. Recently, however, as fossil fuel sources have
proven to be inadequate to meet present demands for energy, more attention
has been given to the problem of depleting the supply of fossil fuel
within the foreseeable future. It has become apparent that alternative
energy sources must be developed.
Substantial effort has been made in the field of energy production using
nuclear energy sources. However, the quantity of nuclear material is also
limited and many experts consider nuclear energy a stop-gap solution at
best. Conversion of solar radiation into usable energy appears to be an
ultimate solution to our long-term energy requirements.
Not only is solar energy virtually inexhaustible, it is clean and produces
no polluting wastes or by-products. Even in geographical areas where cloud
cover makes solar energy conversion ineffective, electricity which was
produced elsewhere by solar energy conversion could be utilized.
The earliest attempts to utilize solar radiation were directed to apparatus
for raising water for irrigation purposes. Such a system was described in
1890 in U.S. Pat. No. 433,055 issued to C. Tellier. The patents of Aubrey
G. Eneas were obtained in 1900 and described a solar powered steam engine
"especially intended for use in connection with irrigation of the grid
plains of the West."
Until the advent of electricity, such energy producing systems were
relatively inflexible. They were effective only during sunlight hours and
only to produce work in the vicinity of the solar conversion apparatus.
Conversion of solar radiation into electricity permitted the converted
energy to be transported and stored. In 1921, W. J. Harvey disclosed a
refinement in U.S. Pat. No. 1,386,781 for tracking the sun to permit
utilization of the maximum available energy during sunlight hours. Since
this system utilized a clockwork mechanism, it was necessary to
periodically adjust and verify the tracking course to compensate for the
progression of the sun's track across the sky throughout an annual cycle.
The problem of balancing a constant energy generating system against a
variable energy demand was attached by A. Weipel. In his 1965 U.S. Pat.
No. 3,214,915, he disclosed a system in which a constant output
hydroelectric generator is used in a variable demand arrangement. During
peak demand periods, all electricity produced by the generator is applied
to a customer distribution network. When customer demand goes down, the
excess electricity is used to power a hydraulic pump which raises water
from a low-lying reservoir to a reservoir at an elevated location. Later,
the potential energy thus stored is recovered by the action of water from
the elevated reservoir in powering the hydroelectric generator.
However, no system is perfectly efficient and it is always necessary to
compensate for losses in the system. If the Weipel system is placed where
there is significant rainfall, the natural runoff could provide such
compensation if it were collected in the elevated reservoir. However, in
sunny, arid regions the compensating effect of rainfall is minimized. In
fact, because of increased evaporation in arid regions, such a system
would have increased losses in such a setting.
Prior systems for collecting and concentrating solar radiation have been of
two general configurations, planar and deep-dish. The planar collectors
have been inefficient because of the relatively large reflective losses
produced by radiation reflecting away from their surface. Deep-dish
configurations have been effective in minimizing reflective losses, and in
concentrating collected radition. However, the intricate shape, such as
parabolic surfaces, makes such deep-dish collectors expensive to
fabricate. For example, the United States Army's 80-foot diameter
collector at White Sands, New Mexico, cost almost a million dollars and a
larger one fabricated by the French in 1970 cost twice that much.
Systems for directly converting solar energy into electricity are not new;
but they are very expensive. Solar cells produce electricity at a cost
that is prohibitive, up to one hundred times the cost of electricity
produced by a coal-fired generating plant.
It is therefore an object of my invention to produce electricity converted
from solar energy at a low, competitive cost.
It is also an object of my invention to produce an electrical generating
system having a generating capability unrelated to demand with storage
capacity for energy generated in excess of demand.
It is a further object of my invention to produce an energy storage system
using solar radiation as principal energy input and compensation for loss
and operational inefficiency.
Yet another object of my invention is to produce a solar radiation
conversion system that will automatically track the sun so that the
maximum solar effect may be realized at all times.
Still another object of my invention is to produce a solar radiation
collector having a simple, economically produced and highly efficient
configuration.
SUMMARY OF THE INVENTION
In an illustrative embodiment of my invention, a circular collector for
solar radiation is fabricated from a plurality of modular elements to form
a reflective surface. Apparatus is provided to automatically track the
position of the sun and to aim the collector to receive maximum radiation
on its surface. A concentrator automatically focuses the collected
radiation onto the surface of a boiler. The boiler produces steam which
powers a hydraulic pump and an electrical generator. When the demand for
electricity is less than the generating capacity, the excess energy powers
the pump to move water from a low-level reservoir to an elevated
reservoir. Water from the elevated reservoir is used to drive another
electrical generator as necessary to meet demand.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a perspective view of a system embodying my invention, shown in
its natural environment;
FIG. 2 is a graphical representation of consumer electricity demand
throughout the hours of a day;
FIG. 3 is a plan view of a solar radiation collector in accordance with my
invention;
FIG. 4 is a partial cross-sectional view of the collector shown in FIG. 3;
FIG. 5 is a partial cross-sectional view taken along the line shown in FIG.
4;
FIG. 6 is a partial cross-sectional view taken along the line shown in FIG.
4;
FIG. 7 is a functional schematic of the system shown in FIG. 1;
FIG. 8 is an elevation view of the collector shown in FIG. 3;
FIG. 9 is a cross-sectional view of the collector taken along the line
shown in FIG. 8;
FIG. 10 is an enlarged detail view showing the plan view of a portion of
the collector taken along the line shown in FIG. 8;
FIG. 11 is an elevation view of the apparatus of FIG. 10; and
FIG. 12 is a partial plan view taken along the line shown in FIG. 8.
DETAILED DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT
A typical system in accordance with my invention is depicted in FIG. 1 of
the drawing. A solar energy conversion tower 10 is placed to collect and
concentrate solar radiation and convert the latent heat thereof into
usable energy. A portion of the energy is converted directly into
electricity to supply customers served by the system. The balance of the
energy is stored, to be used to produce electricity when customer demands
increase. The energy is stored by pumping water into an elevated reservoir
or lake 11 from a lower reservoir or lake 13. At a later time, the
potential energy represented by the water in reservoir 11 may be utilized
to produce electricity by allowing water in reservoir 11 to power a
hydroelectric generator 12 and be discharged into reservoir 13.
Only a single conversion tower 10 has been depicted. However, it will be
clearly understood that any number of such towers could be operated in
parallel. The physical size limitations on tower 10 are unrelated to any
demand for electricity. Rather than increasing the size of tower 10
indefinitely to produce systems of ever increasing generating capacity,
the towers are designed for optimum physical size and then merely
duplicated to increase generating capacity for the system. This is
particularly advantageous where the community utilizing the system is
growing and the demand for electricity increasing. Rather than being
necessary to replace a conversion tower with a physically larger tower to
meet increasing demands, additional towers may merely be added to increase
the system capacity.
The electrical outputs of the towers may be combined using a conventional
electrical distribution network (not shown). The storage capacity of each
tower is connected in parallel either physically, by having each tower
connect to the water conduits to and from the reservoir, or functionally
by having their water inlets connected to reservoir 13 and their water
outlets discharging into reservoir 11.
For reasons of economy, the generating station 12 would not normally be
duplicated. Station 12 may be strategically located relative to upper
reservoir 11 or lower reservoir 13, and be expanded to provide increasing
capacity as needed. It would, however, be possible to provide multiple
hydroelectric generators 12 to meet special needs.
The necessity for providing storage capacity is immediately apparent from a
study of the varying consumer demand shown graphically in FIG. 2. There is
a minimum system demand residual requirement, occurring generally during
the late evening and early morning hours. During the mid-morning hours,
the demand increases as the system's customers awaken and commercial or
industrial needs increase. Demand tapers off somewhat until the noon hour
approaches when demand peaks again. Following the noon hour, demand again
tapers off, only to increase again at the dinner hour. Following the
dinner hour, demand tapers off again until the demand for hot water at
bedtime causes demand to increase again, producing another peak. FIG. 2
represents a typical day, but it should be recognized that variations
occur for work days and weekends and for variations in demand in response
to weather and temperature changes throughout the year.
Obviously, a system having a capacity sufficient only to meet the residual
demand would be unsatisfactory. On the other hand, a system having a
capacity sufficient to meet the maximum peak demand would be both
unnecessary and uneconomical. The design demand for such a system is the
averaged demand depicted by the dashed line in FIG. 2. If the dashed line
in FIG. 2 represents the maximum electrical generating capacity of tower
10, and the solid line represents the electricity needs of the system's
customers, the system would function as follows. Whenever generating
capacity exceeds demand (at 10 A.M., for example), the excess generating
capacity is utilized to raise water from lower reservoir 13 to the
elevated reservoir 11. Once demand exceeds the generating capacity of the
tower 10 (at noon, for example), the potential energy stored earlier in
the day is utilized by taking water from reservoir 11, using it to power
the hydroelectric generator 12 and produce the additional electricity
needed, and then discharging the water into reservoir 13.
Since reservoir 11 could be located to collect natural runoff of rainwater
from higher elevations, an additional energy source would be utilized.
Reservoir 11 could be a naturally occurring lake, or a man-made lake
created by damming such as those found throughout the Southwestern United
States. Any rainfall accumulation in reservoir 11 would further compensate
for losses or inefficiencies of the system, due for example to evaporation
from the reservoirs. In addition, since the conversion tower 10 is ideally
placed where there is strong, continuous sunlight uninterrupted by
cloudcover, the surrounding atmosphere may be arid or semi-arid, making
loss due to evaporation a significant efficiency factor.
An additional advantage in providing energy storage capacity is inherent in
the solar energy converter. Beyond the obvious fact that such a system can
generate electricity only during sunlight hours while demand continues
throughout the nighttime as well, such a system is basically inflexible. A
natural variation in the intensity of the solar radiation occurs from a
low at sunrise to a maximum at solar noon and back to a minimum at sunset.
Therefore, it can be seen that the variation in generating capacity is
unrelated to variations in demand. But more significant, the generating
capacity of a solar radiation collector is essentially constant during
sunlight hours. There is no way to speed it up, or slow it down to adjust
to varying demands. The size of the radiation collecting apparatus is
fixed. The only way that the amount of energy collected could be decreased
below the system's capacity would be to dissipate (waste) a portion of the
energy received from the sun.
Other types of generators, such as oil-fired, coal-burning or hydroelectric
generators, can be operated at variable capacity because the energy input
can be regulated. The speed of the powering engine can be varied, or the
quantity of water released to power the generator may be regulated. But a
solar generator is powered by an unregulated energy source. Solar
radiation is received at the earth's surface with its intensity depending
only on atmospheric conditions. Whether that energy is utilized or not,
the available energy is unchanged. The sun is, in effect, a constant value
energy source. There is no way to regulate the energy producing value of
the source, therefore the most efficient system must utilize all the
available energy regardless of the demand on the system. Thus, the
importance of the energy storage capacity of the system pertains not only
to around-the-clock capacity, but also to the operational efficiency of
utilizing all the energy available.
It has not been specifically mentioned, but it should be apparent, that the
energy storage capability is also valuable to compensate for weather
variations. An electricity producing system that is wholly effective only
on clear, sunny days would be completely unsatisfactory. Therefore, even
in areas where cloud cover is unusual, it would be necessary to provide a
capability for providing electricity in the absence of sunlight.
At the heart of the conversion tower 10 is a circular collector 16 as shown
in FIG. 3. Collector 16 gathers the solar radiation and reflects the
radiation to a focal area where it can be concentrated. As FIG. 3 shows,
collector 16 is fabricated from a number of individual reflective areas.
The assembly of collector 16 is best understood in conjunction with FIG.
4, which is a partial cross-section taken along a radial line.
As FIG. 4 shows, collector 16 is assembled on a framework 17 having a
planar rear or bottom surface. Frame 17 includes an inner rim 18
fabricated from channel stock. Rim 18 is circular in plan and represents
the inner extension of collector 16. FIG. 5 is a cross-sectional view
taken across FIG. 4, as shown, and depicts the configuration through the
radial portion of framework 17 and through the numerous reflective areas.
Extending radially outward, and terminating in an outer rim 19, are a
number of radial T's 23. Forming intermediate rings between inner rim 18
and outer rim 19 are two T-shaped rings, inner T support 21 and outer T
support 22. Outer rim 19 is fabricated from L-shaped stock.
Framework 17 consists of inner rim 18, inner T support 21, outer T support
22, outer rim 19 and the radial T's 23. Framework 17 connects to form a
plurality of annular rings separated into annular segments. Each segment
within an annulus is identical to the other segments within that annulus.
For example, each segment of the inner annulus comprising collector 16 is
an identical inner pannel 25. Each segment of the middle annulus
comprising collector 16 is an identical center panel 26. And each segment
of the outer annulus comprising collector 16 is an identical outer panel
27.
Collector 16 is assembled as follows. After framework 17 is fabricated, the
inner lip of an inner panel 25 is inserted into the open side of inner rim
18. Each panel 25 is then dropped into place where it is supported by the
inside flange of inner T support 21 and by the flanges of radial T's 23.
Panel 25 is then locked in position and secured to framework 17 by a
locking bar 31 which fastens to inner T support 21 with screws 32. Bar 31
fits into a locking notch 34 which is common to each of the inner, center
and outer panels 25, 26 and 27, respectively.
As FIG. 4 clearly shows, locking bar 31 creates a channel shape when it is
fastened to inner T support 21. The center annulus is then assembled by
inserting the inner lip of center panels 26 into the channel provided by T
support 21 and locking bar 31. Similar to panels 25, the panels 26 are
supported, when properly positioned, by radial T's 23 and the inner flange
of outer T support 22. Panels 26 are then fastened to framework 17 by
inserting a locking bar 31 into the locking notch 31 and securing the bar
to T support 22 with screws 32.
The panels 27 are similarly assembled. The inner lip of the outer panels 27
is inserted into the channel formed by outer T support 22 and locking bar
31. Panel 27 is then supported by radial T's 23 and the inner flange of
outside rim 19. Once positioned, panel 27 is locked in place by inserting
locking bar 31 into the locking notch 34 and securing it to rim 19 with
screws 32.
The individual elements that make up framework 17 could be economically
fabricated from extruded metal, such as aluminum, and either welded or
screwed together. Although inner rim 18, outer rim 19, inner T support 21
and outer T support 22 were described as ring shaped or circular, it
should be borne in mind that that is not a necessity. These elements could
be readily fabricated from lengths of straight stock. The resultant shape
would approximate a circular configuration but would in fact be a many
sided polygon, a 48-sided figure for example.
Examination of FIGS. 4 and 5 also reveals that although the rear surface of
panels 25, 26 and 27 is flat, the forward or upper surface is concave.
Because the radius of each annulus is different, the radius of curvature
of panels 25, 26 and 27 will vary. This permits the radiation reflected by
the surface of the panels to be focused at a single central focal area.
FIG. 5 particularly shows the radius of curvature of panel 26 in a
direction across the radial direction of collector 16. Panel 26, which is
typical of panels 25 and 27, includes a molded plastic foam core 28 and a
reflective surface 29. Core 28 is molded to the desired configuration,
including the composite curve of the top surface. To provide the
reflective properties desired on the top surface of the panel, a
reflective surface is added to the surface of the molded core.
The reflective surface 29 could be fabricated in a number of ways. For
example, a metallized layer could be sprayed onto core 28. However, the
most economical fabrication technique is simply to secure a thin layer of
aluminum sheet to core 28 with adhesive. This may be done either as a
separate step following the molding of core 28, or it may be incorporated
directly into the molding operation.
Referring now to FIG. 6, another feature of the individual panels can be
seen. Once again, panel 26 is depicted, but it is typical as well of
panels 25 and 27. In order to reduce effects of wind pressure on the
extensive surface of collector 16, and thereby reduce the required
strength of framework 17 and panels 25, 26 and 27, the panels are provided
with wind pressure relief slots 35. Slots 35 are molded directly into core
28 (as is the locking notch 34 previously discussed). Because slots 35
extend completely through core 28, air pressure buildup is minimized since
the rear of collector 17 is now connected to the front surface of the
collector and any pressure buildup due to wind is prevented. Since the
slots 35 serve to equalize pressure on the front and rear surfaces of
collector 16, it makes no difference whether the wind is flowing from the
front or from the rear.
Because each panel within an annulus is identically shaped, and since each
panel is individually secured as described, repairs to the surface of
collector 16 can be readily made by replacing a panel. In addition to the
possibility of damage due to gusty wind, individual panels could be broken
by foreign objects, whether those objects are vandal's stones, birds or
hailstones. Not only are broken panels easily replaceable, any panel that
loses its reflective efficiency due to dirt, deformation or deterioration
of the reflective material could be readily replaced, either permanently
or temporarily to permit cleaning, etc.
The system depicted in FIG. 1 is shown functionally in FIG. 7. Incoming
solar radiation 40 is reflected by the upper surface of collector 16. The
reflected radiation focuses on a concentrator 41 positioned on the central
axis of collector 16. Concentrator 41 focuses the concentrated radiation
on the surface of a spherical boiler 42 by reflection from its reflective
convex shape. Boiler 42 is heated by the latent heat in the concentrated
radiation. The water in boiler 42 is converted into steam that is
delivered through a conduit 43 to a steam turbine 44. A discharge line 45
moves the spent steam out of turbine 44 and through the coils of an
air-cooled condensing unit 46. The condensing unit 46 is cooled by air
from a circulation fan 47 to convert spent steam back into water by
removing the heat of vaporization. The condensed water is delivered to a
return reservoir 48 via a pipe 49 where the condensate is stored until it
is needed to replace water in boiler 42.
A limit switch 51 in boiler 42 detects a low water condition. Switch 51
connects through wire 52 to an electric motor 53. When switch 51 detects
the low water condition in boiler 42, motor 53 turns on to drive a water
pump 54. Pump 54 takes water from pipe 55, which connects to the
condensate reservoir 48 and pumps it through return line 56 to boiler 42.
When the water level is raised to its proper level in boiler 42, motor 53
turns off.
The power shaft of turbine 44 connects, through clutches which are not
shown but which are well known in the art, to electrical generator 58 and
to hydraulic pump 50. As described earlier, turbine 44 provides rotating
power to drive generator 58 so long as the customer demand requires full
capacity from the generator. As demand decreases and becomes less than the
capacity of generator 58, pump 59 utilizes the available energy to pump
water from the low reservoir 13 via pickup pipe 61 and into the elevated
reservoir 11 via a pump outlet pipe 62.
It should be apparent that boiler 42 and its related apparatus is merely
illustrative of means for converting the heat of concentrated solar
radiation into usable energy. Boiler 42 could be replaced by other energy
converting devices, such as chemical converters, without affecting the
operation of the system. The alterations required to accommodate
alternative means for utilizing the heat of the concentrated radiation
would be apparent to those skilled in the art and no attempt will be made
to describe all feasible variations.
As the customer demand exceeds the generating capacity of generator 58, or
during non-sunlight periods, water from reservoir 11 flows into plant
inlet pipe 63 for delivery to hydroelectric generator 12. Generator 12
uses the incoming water as a power source to generate the power required
to meet the system demands. Water is then discharged into reservoir 13 via
discharge line 64.
Because the sun is a moving energy source, and because collector 16 is most
effective when solar radiation is received at a direction parallel to the
central axis, it is beneficial to have collector 16 mounted in such a way
that it can be moved to follow the sun's path across the daytime sky.
Collector 16, and the mounting tower 66 including concentrator 41, are
mounted to rotate about a pivot 67 located approximately concentric to
boiler 42. As seen in FIG. 8, collector 16 can be oriented at almost any
angle. This permits collector 16 to track the elevation of the sun. To
facilitate movement of the large mass represented by collector 16 and
mounting tower 66, a counterweight 68 is provided on the opposite side of
pivot 67.
The pivot 67 is connected to upright support 73 which carries the vertical
load of collector 16 and mounting tower 66. In order to track the varying
azimuth position of the sun, upright support 73 is mounted to rotate. As
can be seen in conjunction with FIG. 9, support 73 may be rotated about
conversion tower 10 by movement of supporting roller carriage 74 along a
circular rail 72 mounted on a supporting base 71. Rail 72 is A.S.C.E.
track supported on a poured concrete ring foundation forming base 71.
As will be explained later in more detail, the synchronous gear drive
motors which comprise carriage 74 are operated to properly orient support
73 on rail 72. The collector 16 and tower 66 assembly is then rotated
around pivot 67 to aim the assembly directly at the sun.
To further insure that maximum available energy is being utilized,
concentrator 41 is mounted on tower 66 in such a way that it may be
selectively positioned along the central axis of collector 16 to insure
that the concentrated radiation is properly focused on boiler 42. As shown
in FIGS. 10 and 11, concentrator 41 and an automatic tracking assembly 77
(which will be explained later in detail) are mounted so that a rack gear
78, which connects to the concentrator and tracking assembly mechanism,
engages a pinion drive gear 79 connected to the shaft of a control motor
80. Motor 80 connects to the mounting tower 66. When it is desired to
reposition concentrator 41 to refocus the concentrated radiation, motor 80
is operated to rotate gear 79. The advancement of gear 79 along rack gear
78 causes the entire assemblage including concentrator 41 to move relative
to tower 66.
Although it was described earlier how collector 16 could be moved to track
the sun across the sky, no method of accomplishing this was described.
Obviously, the tracking apparatus could be operator controlled. But more
practical is the use of a stored program tracking system. The programming
of such a tracking system is well known and is used to track terrestial
targets for astronomical telescopes. Another form of automatic tracking
apparatus is depicted in FIG. 12. This apparatus could be used as a
substitute for, or to augment, a programmed tracking system.
The system of automatic tracking shown in FIG. 12 comprises four
photo-electric cells 82, 83, 84 and 85 which are isolated from each other
by a light baffle 87. If the light received on cells 82 and 84 is unequal,
the apparatus is not aimed directly at the sun. The inequality would be
used to produce an electrical signal causing the drive motors of carriages
74 to operate. As soon as the apparatus is positioned along the sun's
azimuth, the light received by cells 82 and 84 will be equal and the drive
motors of carriage 74 will be turned off. If the light received by cells
83 and 85 is now unequal, the elevation of the apparatus will be changed
by rotation about pivot 67. When the light received by cells 83 and 85 is
equal, the elevation will be equal to that of the sun and the apparatus
will be properly aimed.
The automatic tracking apparatus just described can be used to continuously
track the solar position or it can be used intermittently. The
intermittent operation can be accomplished by either timing the operating
cycle of the tracking mechanism, to periodically re-aim the apparatus, or
by introducing a sensitivity filter into the circuitry. The sensitivity
filter would render the tracking circuitry inoperative until a threshold
value of inequality was exceeded in the amount of light received at the
photo cells. This would avoid the continuous operation of the tracking
system while insuring that the apparatus would not exceed perfect aim
position by more than a pre-determined amount. Thus, the tracking
mechanism would be operative to maintain perfect aim within a tolerance.
It should also be pointed out that adequate safety features should be
provided. The heat generated by the concentrated radiation is substantial.
If the system malfunctioned and no safety features were present, the
potential for damage to the system is significant. The low water switch 51
could be provided with an emergency shutoff to activate a safety circuit
if very low water conditions are encountered, such as by a failure of pump
54. To prevent the concentrated radiation from burning up the surface of
boiler 42, or from creating excessive steam pressure in the system, the
focusing mechanism of concentrator 41 could be energized to intentionally
de-focus the radiation until repairs are made. If this measure should
prove to be ineffective, it would be very simple to intentionally de-track
the aiming mechanism to aim collector 16 away from the sun. A third
method, apparatus for which is not shown, is to employ a retractable sun
screen. Such a screen could be positioned either to cover all or part of
collector 16, or to cover concentrator 41. The sun screen would prevent
the reflection and concentration of radiation.
To illustrate the size and capacity of a system embodying my invention, let
me give the following example. If collector 16 is 180 feet in diameter,
concentrator 41 is 50 feet in diameter and boiler 42 is 30 feet in
diameter, the following calculations are valid. The usable area of
collector 16 will be just under 23,500 square feet. For a solar intensity
of 180 B.T.U. per square foot, and a system efficiency of 85%;
approximately 1000 kilowatts per hour will be generated by each conversion
tower 10 during sunlight hours. Allocating 1.25 acres per conversion tower
10, a concentration of over 500 towers might be produced in a square mile
area.
The hydroelectric generation capacity is calculated as follows. Each
acre-foot of water produces almost 72,000,000 foot-lbs for a 100 foot
drop. This produces over 1000 kilowatt hours per acre of water with a 100
foot drop. If the effective area of upper reservoir 11 is 100 acres, with
a 30 foot pull down, and a drop of 300 feet to hydroelectric generator 12,
approximately 8,300,000 kilowatt hours could be generated.
It is is assumed, as a worse case example, that all solar produced energy
is used to raise water to the reservoir and that all customer demanded
energy was produced by hydroelectric regeneration, the following figures
apply. Using a square mile area, 500 units would each produce 1000
kilowatts per hour during the sunlight hours. Thus, a total of 4,000,000
kilowatts would be stored. This would allow a system demand averaging over
150 megawatts for a 24-hour period, with peak potential of 500 megawatts
during sunlight hours.
The figures given above are presented only to give an approximation of the
capacity and effectiveness of this system. It is not intended, and should
not be interpreted, as a limitation on the system or as a representation
as to the operating efficiency and capacity of the system. The embodiment
described was presented merely for purposes of illustration. It should be
apparent that those skilled in the art could devise variations of the
described embodiment that still embody the invention claimed.
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