Patent Application
20070199560
The present invention relates to the field of solar energy systems. More specifically, the present invention relates to a stable structure for supporting a solar energy collection unit of a solar energy system.
Due to the finite supply of fossil energy sources, the global environmental damage caused by fossil fuels, increasing energy demand, and economic forces, society is becoming compelled to diversify energy resources, utilize existing fossil fuels more effectively, and reduce pollutants. An alternative energy resource, solar power, is already in widespread use where other supplies of power are absent such as in remote locations and in space. Solar power generally describes a number of methods of harnessing energy from the light of the sun.
Solar power technologies can be classified as either direct or indirect. Direct solar power involves only one transformation into a usable form. Direct solar power utilizes solar energy collection units such as photovoltaic cells for creating electricity, solar thermal collectors for creating heat energy, solar sails for imparting motion, fiber optic cables for conducting sunlight into building interiors to create supplemental lighting, and so forth.
Indirect solar power involves more than one transformation to reach a usable form. An exemplary type of power generation that employs indirect solar power is the use of photosynthesis to convert solar energy to chemical energy which can later be burned as fuel. The concept of using photosynthesis to convert solar energy to chemical energy has been expanded into using algae to convert carbon dioxide from waste emissions to useful, high-value biomass products. This methodology is generally referred to as carbon dioxide bio-regeneration. Early ventures entailed pumping emission gases through the base of a pond and growing algae on the surface. Unfortunately, the algae was difficult to harvest and the energy required to “churn” the pond to ensure full algal exposure to sunlight was expensive. More recent efforts have been directed toward enclosed bioreactor systems that function as solar energy collection units, with the object being to increase algae production in a cost-effective manner. Such innovations in bioreactor systems involve streamlining the harvesting of algae, limiting the energy required to operate the system, automating necessary controls (e.g. flow controllers and gas uptake), minimizing the physical space requirements, and so forth. Such innovations have increased the economic viability of utilizing indirect solar power for carbon dioxide regeneration.
Although solar collection efficiency has increased and the costs for the various solar energy collection units, such as photovoltaic cells, thermal collectors, fiber optic elements, algal bioreactors, and the like is decreasing through technological innovation, the cost effectiveness of the host support structures is not correspondingly decreasing.
Such host support structures must secure the solar energy collection units in order to withstand climatic stresses such as, wind, rain, sand storms, floods, snow, and the like. The host support structures must also secure the solar energy collection units in order to withstand geologic stresses including earthquakes, erosion, and the like.
In order to withstand the various climatic and geologic stresses, prior art support structures for solar energy collection units require a heavy structural steel pedestal or framework, typically embedded in a large concrete base or foundation. Typical installations have become sufficiently large so that cranes are required to move and install the structural steel, cement is trucked in to support the steel framework, and multiple visits to the site by multiple workers are required to complete the installation. Unfortunately, the construction of such a large structure is quite expensive, is difficult to install in remote locations, and is expensive to maintain.
Consequently, a major obstacle to a more widespread exploitation of both direct and indirect solar power technologies has been the development of stable, yet cost-effective, host structures for supporting solar energy collection units in alignment with incident rays of the sun.
Accordingly, it is an advantage of the present invention that a method of supporting a solar energy collection unit of a solar energy system is provided.
Another advantage of the present invention is that a method of supporting a solar energy collection unit is provided that allows the use of local materials to support the solar energy collection unit.
Yet another advantage of the present invention is that a method of supporting a solar energy collection unit is provided that is readily customizable, stable under stress conditions, cost effective to build and maintain, and has a minimal long term impact on the local environment.
The above and other advantages of the present invention are carried out in one form by a method of supporting a solar energy collection unit of a solar energy system. The method calls for redistributing earth at a worksite to form an elevated earthen structure having a sun facing surface, compacting the earthen structure, and arranging the solar energy collection unit upon the sun facing surface of the earthen structure.
The above and other advantages of the present invention are carried out in another form by a method of supporting a photosynthetic bioreactor of a solar energy system. The method calls for redistributing earth at a worksite to form an elevated earthen structure having a sun facing surface, orienting the sun facing surface at an angular elevation from horizontal of greater than ten degrees and less than ninety degrees, and compacting the earthen structure. The method further calls for excavating a channel proximate the earthen structure and arranging the photosynthetic bioreactor upon the sun facing surface of the earthen structure. A supply fluid is directed through the channel and a fluid inlet of the photosynthetic bioreactor is supplied with the supply fluid from the channel.
A more complete understanding of the present invention may be derived by referring to the detailed description and claims when considered in connection with the Figures, wherein like reference numbers refer to similar items throughout the Figures, and:
The present invention relates to methods of supporting a solar energy collection unit of a solar energy system. The solar energy system encompasses a variety of direct and indirect solar power technologies. Similarly, the solar energy collection unit encompasses a variety of existing and emerging apparatuses such as a photovoltaic cell, a thermal collector, a fiber optic collector, an enclosed photosynthetic bioreactor, and the like. In certain embodiments, the disclosed methods of supporting a solar energy collection unit provided herein can be utilized as part of an integrated photosynthetic bioreactor solar energy system that at least partially converts certain pollutant compounds, such as carbon dioxide, contained within combustion gases to biomass.
The term “photosynthetic bioreactor” used herein refers to an apparatus containing, or configured to contain, a liquid medium carrying at least one species of photosynthetic organism and having at least one surface of which is transparent to light of a wavelength capable of driving photosynthesis. The terms “photosynthetic organism” or “biomass,” used herein includes those organisms capable of photosynthetic growth, such as plant cells and micro-organisms (including algae and euglena). The term “biofuel” used herein includes any fuel that derives from biomass produced in the photosynthetic bioreactor.
Solar energy collection units 22 in this exemplary illustration may be photovoltaic cells, thermal collectors, and the like. Consequently, solar energy system 20 may include other supporting equipment, for example, wiring, charge controllers, batteries, inverters, and the like, not shown herein for simplicity of illustration. In addition, only three earthen structures 24 are shown for simplicity of illustration. It should be understood that the quantity of earthen structures can be readily scaled to accommodate a quantity of solar energy collection units 22 that form system 20.
Earthen structures 24 are formed utilizing the local material at worksite 26, such as sand, soil, rock, mud, and various densities of earthen blends. Such an arrangement can be built utilizing conventional earth-moving equipment, such as graders, shovels, excavators, and the like to redistribute the local material to host solar energy collection units 22. In addition, since local material is simply redistributed to support solar energy collection units 22, a great array of designs for plowing and/or excavating worksite 26 are envisioned that capitalize on the geography of worksite 26, and accommodate large scale solar energy systems. That is, alignment and realignment of solar energy collection units 22 can be accomplished by simply reshaping host earthen structures 24 and repositioning solar energy collection units 22 upon them.
Since earthen structures 24 are constructed utilizing local materials, earthen structures 24 can be installed in a variety of locations. Preferably, worksite 26 is non-arable, thereby saving arable land for agriculture, while effectively utilizing heretofore unused land. Earthen structures 24 may host low profile indigenous plant life to further stabilize earthen structures 24 and to create a more natural, aesthetically pleasing appearance. Consequently, earthen structures 24 of solar energy system 20 may be more readily accepted by the general public.
The use of local earthen materials in building earthen structures 24 provides for more efficient, time effective installation, thus decreasing setup costs. Moreover, earthen structures 24 can be repaired with materials in direct proximity to the installation, lowering maintenance costs and accelerating time to operation. Furthermore, the use of local earthen materials allows decommissioning of the installation with minimal environmental impact because the local materials can be returned to their natural position.
Evaluation of worksite 26 may reveal that the earthen support structures for solar energy collection units 22 may require additional strengtheners for assuring overall structural integrity. Non-earthen strengthening material 32 may optionally be incorporated into earthen structure 24 to provide this additional strength to earthen structure 24. In a preferred embodiment, non-earthen strengthening material 32 is detached from solar energy collection unit 22. This allows ready reconfiguration and/or replacement of units 22 without having to access material 32 by partially or totally destroying earthen structure 24. Non-earthen strengthening material 32 in a triangular configuration is presented for simplicity. Those skilled in the art will recognize that strengthening material 32 can be any of a great variety of sizes, shapes, and densities.
Further evaluation of worksite 26 may reveal that the earthen structures may be subject to erosion from dust storms, rains, flooding, and the like. Earthen structure 24 may optionally be encased in binder material 34 to assure surface integrity and robustness in the face of erosive action of wind or water.
It should be noted that sun facing surface 28 of earthen structure 24, and the other earthen structures constructed in accordance with the present invention, is oriented at an elevation angle 36 from horizontal of greater than ten degrees and less than ninety degrees. The degree of elevation angle 36 is determined to suit the particular sun exposure requirements of solar energy collection units 22 so as to optimize the energy output of units 22.
It should be further noted that earthen structure 24 provides a thermal management service to solar energy system 20 (
Heat may be dumped directly to earthen structure 24 by burying a tab 44 or heat pipe mechanism from the bezel or frame of solar energy collection units 22 into earthen structure 24. When solar energy collection units 22 are thermal collectors, working fluids that are intentionally heated in units 22 can be optionally routed via enclosed piping through the surface of earthen structure 24 (not shown). Consequently, the working fluids are insulated by earthen structure 24 preserving the energy efficiency of the overall system during cooler portions of the day or night.
In general, photosynthetic bioreactors 54 contain a liquid medium carrying a photosynthetic organism, for example, algae, and have a transparent surface 56 for driving photosynthesis. The algae in photosynthetic bioreactor solar energy system 52 absorb carbon dioxide from a source, in the presence of solar energy, through the production of cell mass. The source of carbon dioxide may be combustion gas, i.e., flue gas, produced by fossil fuel users, such as coal, oil, and gas plants. The algal biomass can be harvested from photosynthetic bioreactors 54 for creating biofuel, pharmaceuticals, cosmetics, and so forth. Those skilled in the art of algal biotechnology will recognize that some algal cultures can also be used in photosynthetic bioreactors 54 for biological removal of nitrogen compounds found in flue gases.
A particular configuration of photosynthetic bioreactors 54 is not a limitation of the present invention. Rather, photosynthetic bioreactors 54 can be any of a variety of conventional and emerging photosynthetic bioreactor configurations, including “bubble columns” or “air lift reactors,” that are supportable by earthen structure 24. The liquid medium contained in photosynthetic bioreactors 54 is typically water. However, the water need not be potable, but may be sea water, brackish water, or other non-potable locally obtained water containing sufficient nutrients to facilitate viability and growth of algae contained within the liquid medium.
In a preferred embodiment, the methodology of the present invention entails providing fluid supply channel 48 and/or fluid release channel 50 by excavating earth at worksite 26 proximate earthen structure 24. A supply fluid, i.e., water, represented by an arrow 58, is directed through fluid supply channel 48, and is supplied to a fluid inlet 60 of each of photosynthetic bioreactors 54. A release fluid, represented by an arrow 62, is supplied to fluid release channel 50 from a fluid outlet 64 of each of photosynthetic bioreactors 54, and is directed through fluid release channel 50. Release fluid 62 contains water and a concentrated amount of biomass. This biomass can be harvested at the location of fluid outlet 64, or alternatively, at a centralized algal collector (not shown) in fluid communication with fluid release channel 50.
Fluid channels 48 and 50 provide a system for channeling fluid to and from photosynthetic bioreactors 54, thus saving on expenses associated with piping and pipe installation. Of course, those skilled in the art will recognize that fluid channels 48 and 50 can be excavated with a slope that further facilitates fluid flow in the desired direction. In addition, since fluid channels 48 and 50 may be open, water flow from rain and snow can be collected in fluid channels 48 and 50 for use within photosynthetic bioreactors 54. The water flow collected in fluid channels 48 and 50 may also support co-located plant growth 66 at worksite 26 or patching of a worn structure with mud or adobe.
In an alternative embodiment, fluid supply channel 48 and fluid release channel 50 may be provided in the form of enclosed tubular members, i.e., pipes, that can be buried or can lie above ground. The enclosed tubular members may be in various cross-sectional shapes, such as circular, rectangular, oval, crescent, and so forth, in accordance with the particular configuration of the solar energy system. The enclosed tubular members may be transparent or transparent for specific light wavelength to optimize growth of algal biomass.
In an exemplary embodiment, photosynthetic bioreactor solar energy system 52 may be a large scale operation at worksite 26 covering at least one hundred acres. Substantially an entirety of worksite 36 may then be utilized to form a plurality of elevated earthen structures 24 for supporting a plurality of photosynthetic bioreactors 54, or other such solar energy collection units. Efficient algae production in concert with cost effective installation and maintenance of earthen support structures 24 facilitate the economical production of large quantities of biomass while advantageously reducing pollutant materials in combustion gases.
Referring to
The methodology of the present invention entails conforming sun facing surface 28 of earthen structure 24 to a shape of the solar energy collection unit, in this case tubular photosynthetic bioreactors 54. This is especially evident in
Referring to
In this exemplary configuration, each of horizontally arranged solar energy collection units 76 on each of terraces 74 is interconnected via a feeder tube 80, and adjacent terraces 74 are sloped in opposing directions. A supply fluid, such as water, represented by an arrow 82, is supplied to a fluid inlet 84 of a first, or highest, one of solar energy collection units 76 via, for example, fluid supply channel 48 (
Solar energy system 78 having horizontally arranged solar energy collection units 76 may be a heat gather or may alternatively be a photosynthetic bioreactor. When solar energy system 78 is configured as a heat gatherer, supply fluid 82 is heated as it flows through solar energy collection units 76, and hot release fluid 86 is released at a fluid outlet 88. When solar energy system 78 is configured as a photosynthetic bioreactor, release fluid 86 can contain water and a concentrated amount of biomass. This biomass can be harvested at the location of fluid outlet 88, or alternatively, at a centralized algal collector (not shown) in fluid communication with fluid outlet 88.
As most clearly seen in
Solar energy collection units 76 are shown as being generally circular in cross-section for simplicity of illustration. However, it should be understood that solar energy collection units 76 may be in various other cross-sectional shapes, such as rectangular, oval, crescent, and so forth, in accordance with the particular configuration of solar energy system 78.
It should be observed that installation process 92 includes some task boxes formed from solid lines and other task boxes formed from dashed lines. The task boxes formed from solid lines represent those tasks required for any earthen structure configuration, whereas the task boxes formed from dashed lines represent optional tasks that are dependent upon worksite geography and the particular solar energy system configuration.
Process 92 begins with a task 94. Task 94 is an initial step in which requirements of the particular solar energy system are defined and the earthen structure configuration is determined. The particular configuration for earthen structures 24 depends in large part upon local geography, size and quantity of the solar energy collection units, desired elevation angle for the units, and whether fluid supply and release channels are required.
Once certain configuration decisions have been made, installation process 92 proceeds to a task 96 at which graders, shovels, excavators, and the like are employed to redistribute earth at worksite 26 (
Optional tasks 98 and 100 may be performed in connection with task 80. At task 98, internal strengthening material 32 (
Next, a task 102 is performed regardless of the particular configuration of earthen structure 24. At task 102, the redistributed earth used to form earthen structure 24 is compacted to form a stable structure.
Following task 102, an optional task 104 may be performed. At task 104, the surface and surrounding area of the recently compacted earthen structure 24 may be stabilized. For example, earthen structure 24 may be encased with binder material 34 (
At task 106, solar energy collection units 22 (
An optional task 108 is performed if fluid medium is utilized in connection with the particular solar energy system configuration, such as photosynthesis bioreactor solar energy system 52 (
In addition to optional task 108, or in lieu of optional task 108, an optional task 110 is performed. At optional task 110, electronic equipment 40 (
Photosynthetic bioreactor solar energy system 52 optionally includes a primary valve 112 that enables recirculation of release fluid 62 into fluid supply channel 48. In such a situation, biomass in release fluid 62 may be harvested so that release fluid 62 can be reused, thereby conserving the working fluid. System 52 may further optionally include secondary valves 114 for controlling a flow of supply fluid 58 into individual photosynthetic bioreactors 54, so that individual bioreactors 54 can be taken offline for maintenance, replacement, and so forth.
Each of photosynthetic bioreactors 54 further includes a combustion gas inlet 116 in which combustion gas, represented by dashed arrows 118, is received into bioreactors 54. Combustion gas 118 bubbles up from the bottom of photosynthetic bioreactors 54 and supply fluid 58 flows downwardly in an opposing direction from combustion gas 118. Carbon dioxide, and/or other pollutant materials, in combustion gas 118 is converted to organic material in photosynthetic reactions occurring in bioreactors 54. Combustion gas 118 is subsequently released from photosynthetic bioreactors 54 through a gas outlet 120, with ideally a significant reduction in pollutant materials.
In summary, the present invention teaches of a method of supporting a solar energy collection unit of a solar energy system. The method entails the redistribution of local earthen materials to form an earthen structure upon which the solar energy collection unit is arranged. The methodology of excavating and redistributing local materials yields earthen support structures that are highly customizable, are cost effective to build and maintain, and have a minimal long term impact on the local environment. Moreover, the methodology of the present invention yields a stable support structure for solar energy collection units with the associated installation complexity and cost of conventional structural steel supports and concrete foundations. The incorporation of internal strengthening materials into the earthen structures and/or the encasement of the earthen structures in binder material enhance surface integrity and overall stability under stress conditions. In addition, the earthen structures can provide thermal management services to the solar energy systems, and channels can be readily provided at the worksite for supply and release channeling of a fluid medium used by the solar energy system.
Although the preferred embodiments of the invention have been illustrated and described in detail, it will be readily apparent to those skilled in the art that various modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.
