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Title:
BIOREACTOR VESSEL WITH NATURAL LIGHTING SYSTEM
Document Type and Number:
WIPO Patent Application WO/2008/005926
Kind Code:
A2
Abstract:
A system and related methods generate biomass in the presence of a fluid, primarily using natural light. The system in one embodiment includes a bioreactor vessel for receiving the fluid and biomass. The vessel includes a drain for draining the fluid and at least a portion of the biomass for recovery, as well as an inlet for receiving a gas at least partially comprising CO2 to promote growth of the biomass. At least one optical conduit adjacent the vessel is optically associated with a light collector including at least one reflector for reflecting collected natural light to the optical conduit. At least one light distribution device associated with the optical conduit delivers the collected natural light to the vessel to facilitate growth of the biomass.

Inventors:
WINSNESS, David, J. (1735 Windsor Drive, Alpharetta, GA, 30004, US)
Application Number:
US2007/072656
Publication Date:
January 10, 2008
Filing Date:
July 02, 2007
Export Citation:
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Assignee:
GS INDUSTRIAL DESIGN, INC. (1 Penn Plaza, Suite 1612New York, NY, 10119, US)
WINSNESS, David, J. (1735 Windsor Drive, Alpharetta, GA, 30004, US)
International Classes:
C12P1/00; C12P7/06
Foreign References:
US4952511A
US6603069B1
Other References:
GORDON: 'Tailoring optical systems to optimized photobioreactors' INTERNATIONAL JOURNAL OF HYDROGEN ENERGY vol. 27, no. 11-12, November 2002 - December 2002,
CSOGOR ET AL. JOURNAL OF APPLIED PSYCHOLOGY vol. 13, no. 4, August 2001,
Attorney, Agent or Firm:
DORISIO, Andrew, D. et al. (King & Schickli, PLLC247 N. Broadwa, Lexington KY, 40507, US)
Download PDF:
Claims:

In the Claims

1. A system for generating biomass in the presence of a fluid, comprising: a bioreactor vessel for receiving the fluid and biomass, said vessel including a drain for draining the fluid and at least a portion of the biomass for recovery and an inlet for receiving a gas at least partially comprising CO 2 to promote growth of the biomass; at least one optical conduit adjacent the vessel; a light collector including at least one reflector for reflecting collected natural light to the optical conduit; and at least one light distributor associated with the optical conduit for delivering the collected natural light to the vessel to facilitate growth of the biomass.

2. The system according to claim 1, wherein the at least one reflector comprises a primary reflector and further including a second reflector for focusing the light reflected by the primary reflector.

3. The system according to claim 1, wherein the light distributor comprises a panel formed of a light-transmissive material.

4. The system according to claim 3, further including a plurality of panels positioned in the vessel.

5. The system according to claim 3, wherein the light- transmissive material comprises plastic.

6. The system according to claim 1, wherein the collector is mounted for movement about one or more axes to maintain a face of the reflector generally perpendicular to the sun's rays.

7. The system according to claim I, further including means for supplying a fluid for making up any fluid removed from the vessel during recovery.

8. The system of claim 1, wherein the light collector comprises a trough having a predetermined length and width.

9. The system of claim 8, wherein the trough includes an opening for allowing light to transmit to the optical conduit.

10. The system of claim 8, wherein the light collector comprises a plurality of troughs arranged in a row.

11. The system of claim 1 , wherein the vessel includes media for supporting the biomass.

12. The system of claim 11, wherein the media comprises a plurality of substrates, and further including at least one optical conduit adjacent each substrate.

13. The system of claim 1, further including means for creating a light/dark cycle within at least a portion of the vessel.

14. The system of claim 13, wherein the creating means comprises a shutter.

15. The system of claim 13, wherein the creating means comprises a motive device for adjusting the position of the light collector.

16. The system of claim 13, wherein the creating means comprises a motive device for moving the optical conduit.

17. The system of claim 13, wherein the creating means comprises a motive device for moving the light collector.

18. A method for generating and recovering biomass, comprising: providing a vessel with a liquid and the biomass; using a collector including at least one reflector to receive and deliver natural light to a light distribution device positioned within the vessel and at least partially submerged in the liquid; and harvesting the biomass.

19. The method of claim 18, wherein the step of harvesting the biomass comprises at least partially draining the liquid from the vessel.

20. The method of claim 18, further including the step of delivering a gas at least partially comprising CO 2 to the fluid in the vessel.

21. The method of claim 20, wherein the step of delivering the gas comprises sparging the gas in the liquid.

22. The method of claim 18, further comprising creating a light/dark cycle within at least a portion of the vessel.

23. The method of claim 22, wherein the step of creating a light/dark cycle comprises: delivering the natural light to a first portion of the vessel at a first time; and delivering the natural light to a second portion of the vessel at a second time after the first time.

24. The method of claim 18, further including the step of moving the collector to maintain a face of the reflector generally perpendicular to the sun's rays.

Description:

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BioREACTOR VESSEL WITH NATURAL LIGHTING SYSTEM

This application claims the benefit of U.S. Provisional Application Ser. No. 60/818,256, filed June 30, 2006, and U.S. Provisional Patent Application Ser. No. 60/842,398, filed September 5, 2006, the disclosures of which are incorporated herein by reference.

Copyright Statement

A portion of the disclosure of this document contains material subject to copyright protection. No objection is made to the facsimile reproduction of the patent document or this disclosure as it appears in the Patent and Trademark Office files or records, but any and all rights in the copyright(s) are otherwise reserved.

Technical Field

The present invention relates generally to biomass production and, more particularly, to a bioreactor vessel with a natural lighting system.

Background of the Invention

When CO 2 is released into the earth's atmosphere in excessive amounts, it retains heat and makes the surface temperature warmer. This is deleterious for obvious reasons. At present growth rates, estimated CO 2 levels in the atmosphere will increase from 350 ppmv (at present) to 750 ppmv in as little as 80 years. Leveling CO 2 concentrations at 550 ppmv

requires reducing net CO 2 emissions by over 60% from 1990 levels during the next 100 years.

One prior proposal for a possible partial solution to the foregoing problem involves using biological agents to feed on the CO 2 -laden flue gas resulting from the combustion of non-renewable fossil fuels. Specifically, U.S. Patent No. 6,667,171 to Bayless et al., describes one type of system for passing flue gas including CO 2 over a plurality of porous membranes supporting a colony of microbial agents, such as cyanobacteria or algae. These agents thrive on the CO 2 and, in the process, convert it to harmless oxygen and create a significant amount of starchy biomass. The oxygen can in theory simply be released to the environment, and the biomass harvested and used to produce valuable products, such as ethanol or biodiesel. A similar type of system is described in U.S. Patent Publication No. 2005/0260553 to Berzin. While these types of systems no doubt ameliorate the above- described problem with CO 2 , one issue is the difficulty in efficiently growing, collecting, and recovering the biomass, such as algae. Specifically, many types of algae grow best when delivered only a certain spectrum of sunlight, and typically that excluding ultraviolet and infrared wavelengths. Also, growing algae in relatively large volumes of fluid is desirable to facilitate recovery, but it can be difficult to provide light well within the depths of a vessel substantially filled with fluid and algae. Likewise, as discussed in the Bayless et al. patent, harvesting the biomass can be a particularly delicate undertaking, especially when it is grown on substrates.

Accordingly, a need exists for a more efficient and economical

manner of growing and recovering biomass using natural lighting.

Summary of the Invention

In one aspect of the invention, a system for generating biomass in the presence of a fluid is provided. The system comprises a bioreactor vessel for receiving the fluid and biomass, the vessel including a drain for draining the fluid and at least a portion of the biomass for recovery and an inlet for receiving a gas at least partially comprising CO 2 to promote growth of the biomass. At least one optical conduit adjacent the vessel receives light from a light collector including at least one reflector for reflecting collected natural light. At least one light distributor associated with the optical conduit delivers the collected natural light to the vessel to facilitate growth of the biomass.

In one embodiment, the at least one reflector comprises a primary reflector and further including a second reflector for focusing the light reflected by the primary reflector. Preferably, the light distributor comprises a panel formed of a light-transmissive material (such as transparent or translucent plastic) and, most preferably, a plurality of panels positioned in the vessel. The system may further include means for supplying a fluid for making up any fluid removed from the vessel during recovery.

In this or another embodiment, the light collector comprises a trough having a predetermined length and width. Preferably, the trough includes an opening for allowing light to transmit to the optical conduit. A plurality of troughs may be arranged in a row, preferably substantially covering a corresponding surface of the vessel. The collector may be mounted for movement such that a face of the reflector is maintained

generally perpendicular to the sun's rays.

The vessel may further include media for supporting the biomass. Preferably, the media comprises a plurality of substrates, such as polyester sheets. The system may be arranged such that at least one optical conduit lies adjacent each substrate.

In any of these embodiments, the system may further include means for creating a light/dark cycle within at least a portion of the vessel. This creating means may comprise a shutter for temporarily blocking the light, or a motive device for adjusting the position of the light collector. Still another alternative is for the creating means to take the form of a motive device for moving the optical conduit.

Another aspect of the invention is a method for generating and recovering biomass. The method may comprise the steps of providing a vessel with a liquid and the biomass, using a collector including at least one reflector to receive and deliver natural light to a light distributor positioned within the vessel and at least partially submerged in the liquid; and harvesting the biomass.

In one embodiment, the step of harvesting the biomass comprises at least partially draining the liquid from the vessel. The method may further include the step of delivering a gas at least partially comprising CO 2 to the fluid in the vessel. Preferably, the step of delivering the gas comprises sparging the gas in the liquid.

The method may further include the step of creating a light/dark cycle within at least a portion of the vessel. This step may involve delivering the natural light to a first portion of the vessel at a first time, and delivering the natural light to a second portion of the vessel at a second

time after the first time. The method may further include moving the collector to keep a face of the reflector generally perpendicular to the sun's rays.

Brief Description of the Drawings

Figures Ia and Ib illustrate one embodiment of a natural lighting system for a bioreactor in accordance with one aspect of the invention;

Figures 2a and 2b are different schematic views of another embodiment of a natural lighting system for a bioreactor in accordance with one aspect of the invention;

Figure 3 provides a schematic view of a bioreactor incorporating a natural lighting system; and

Figure 4 is a top plan schematic view of a vessel including a plurality of elongated light collectors.

Detailed Description of the Invention

One aspect of the invention is a method and related system of generating biomass using natural light and recovering it for further use, such as fuel or feedstock for fuel generation. As shown in Figures Ia and Ib, the system 10 may include two basic components: (1) means for collecting solar energy, including natural, visible light; and (2) means for using the collected energy to help generate biomass in an associated vessel. Each of these components of the system 10 is now described in detail.

As shown in Figure Ia, the means for collecting natural light may comprise a collector 12 for collecting solar energy, primarily in the form of light. In the illustrated embodiment, this collector 12 comprises a primary reflector 14 (such as a parabolic mirror, which may dish-shaped or

elongated in one direction so as to form a trough; see Figure 2b) for reflecting collected light to a secondary reflector 16. This secondary reflector 16 is designed to receive and concentrate the light L collected by the first reflector 14 to a beam B. This beam B may then be focused onto a filter media 15, such as quartz, to remove any unwanted wavelengths (such as ultraviolet light). Any unwanted energy, such as that resulting from the filtering, can be redirected for further use, such by delivering it to a photovoltaic cell or solar hydrogen generation tubes. Alternatively, both reflectors 14, 16 may be coated to remove desirable portions of the light spectrum while allowing others (e.g., infrared or UV) to pass.

Light from the collector 10 is delivered to the means for using the collected energy to help generate biomass. As shown in Figure Ib, this means includes a vessel including a bioreactor tank 20 of any shape (spherical, tubular, cubic, etc.), for containing a desired biomass seed material, such as algae. This tank 20 preferably includes a closed top 21 through which the optical lines or tubes pass to deliver the collected light to the interior compartment thereof.

Within the interior compartment or chamber of the tank 20 is positioned a device for distributing or radiating the collected light throughout the fluid. This device comprises at least one, and preferably an array, of light distributors 22 in the form of panels or tubes positioned within the tank 20. These distributors 22 communicate via optical conduits 24 (which may be comprised of one or more optical fibers) with the collector 10 through an opening 14a in the primary reflector 14. The distributors 22 of the light manifold thus formed are preferably fabricated of light-transmitting plastic materials, such as acrylic, and

dimensioned and arranged in tandem such that light can radiate and spread about the entire tank 20 to promote biomass growth throughout. The sidewalls forming the tank 20 may even comprise plastic light-transmitting panels for delivering light to the interior, either from the collector 10, the sun, or other source. The panels 22 may also be perforated to allow fluid or biomass to circulate freely throughout any fluid in the tank 20. Suitable connectors 26 or couplers may also be used for connecting the panels or tubes 22 with the conduit 24.

Optionally, the light collecting means may also be arranged to create a light/dark cycle, which may be desirable for promoting or enhancing the growth of certain types of biomass. In the embodiment shown in Figure 2 a, this is achieved using a shutter 28 adapted for moving in and out of the path of light transmission otherwise established between the secondary reflector 16 and the conduit 24 (which may be by way of filter 15). The shutter 28 may comprise a plate that completely blocks the transmission of light, or one that reflects light in an oscillating manner. To effect movement into the light transmission path, the plate 24 may be associated with a motive device, such as a linear motor, ball screw, rotary motor, or the like. Alternatively, light/dark cycles may be created by oscillating the distributor 22 toward and away from the transmission path. For instance, the conduits 24 could be moved such that one of the distributors 22 receives all light from the second reflector, and then shifted later in time such that the light is transmitted through another distributor 22. That way, none of the light energy is wasted. Still another alternative for a light/dark cycle is to oscillate the secondary reflector 16 to direct light alternatively between the conduits 24 associated with selected panel or tubes 22 for

receiving the light (note action arrow R in Figure 2a). In either case, the movement may be effected by a suitable motive device, such as a rotational or linear motor.

In the embodiment illustrated in Figure 2b, the primary reflector 14 of the light collector 10 is shown in the form of an elongated, generally U- shaped trough having a predetermined length and width (one of which preferably matches at least one corresponding dimension of the vessel). This trough may extend the entire length or width of the tank 20, and multiple rows of troughs may be provided in a tandem fashion (see the top plan schematic view of Figure 4, and note trough-shaped collectors 12a, 12b, and 12c arranged in a row, each having a length G generally corresponding to a width W of the tank or vessel 20). Of course, the use of troughs advantageously maximizes the amount of coverage of the corresponding side of the vessel 20. The one or more collectors 12 (trough(s)) provided may be mounted so as to be capable of moving to ensure the maximum exposure to light is achieved. Most preferably, the mounting is such that it allows each collector 12 to track the sun on two different axes (e.g., one to allow the trough to face the sun vertically (such as rotation about axis Z in Figure 2b) and a second axis to allow the entire trough to rotate at its base to allow the trough (or more particularly, a face of the reflector) to remain perpendicular to the sun's rays (such as rotation (tilting) about axis X or

Y)). Movement may be effected by a suitable motive device (not shown).

The associated secondary reflector 16 collects reflected light and focuses it, preferably in beam form, onto the non-concentric conduits 24, the corresponding ends of which may be exposed by an elongated, non-

concentric opening 14a formed in the trough 14. The conduits 24 in turn deliver the light to the associated tubes or panels 22 such that it may irradiate the biomass. Unlike the concentric dish type of primary mirror in the collector 10 of Figure 2a, the trough-style primary reflector advantageously maximizes the amount of light collected while potentially minimizing wasted space between the collectors when arrayed.

The tank 20 also includes an inlet 20a that communicates with a source of gas for facilitating growth of the biomass, and preferably one comprising a substantial amount of CO 2 . This gas may be delivered under pressure via one or more conduits or spargers (not shown) with outlets located at or near the bottom of the tank 20. Preferably, the gas comprises an exhaust gas with a substantial concentration of CO 2 , such as that emanating from the generation of power using fossil fuels, fermenters, or the like. Accordingly, it is most desirable for the system 10 to be located at or near a power generation plant or like source of unwanted CO 2 in gaseous form (such as the fermenter(s) associated with an ethanol plant).

An advantage of the disclosed system 10 using a liquid-filled tank 20 is that the algae may be harvested by simply partially or fully draining the vessel, either on an intermittent or continuous basis, through an associated drain 20b. For example, the tank 20 may be operated such that a portion of the biomass is drained while an equivalent amount of makeup fluid (water) is provided in order to maintain the desired concentration for optimal growth. Algae may also be recovered by periodically cleaning the light tubes or panels, which may be done using a mechanical system with a brush or scraper or, alternatively, a fluid system (either liquid or gas). Indeed, at a sufficiently high flow rate, the bubbling CO 2 emanating from the bottom of the tank 20 to provide a sparging function could even be

used to provide some level of cleaning action.

The fluid drained from the vessel during harvesting may require filtering to recover the biomass. This may be done in the manner described in U.S. Patent No. 6,083,740. Once harvested, the biomass typically includes a large amount of starch, as well as oil or cellulosic concentrations. Oil can be extracted and converted into biodiesel, cellulose can be enzymatically converted into fuel, and the high starch be used in a fermentation process, such as for producing ethanol (either in a separate fermentation and cooking stage prior to distillation, or in the same line used to produce ethanol from the milled corn, depending on the type of enzyme action available). The byproduct of CO 2 created may then be used to supply the vessel (tank 20), which in turn produces more biomass. Essentially, the CO 2 is being "recycled" into products for fermentation to create more ethanol. In an alternative embodiment, the means for collecting light of the system 10 may be used with a bioreactor of the type described in U.S. Patent No. 6,667,171 to Bayless et al. For example, as shown in Figure 3, the tank 20 forming part of the bioreactor contains the growth media 30, which may comprise a plurality of generally upstanding substrates (e.g., porous membranes), for supporting the biomass, such as algae or cyanobacteria. A fluid delivery system associated with the tank 20 includes a conduit 32 for wetting the media to promote biomass growth, as well as to possibly wash away the biomass for recovery through the associated drain 20b (note regulator 32 for controlling the fluid flow from a water reservoir 36). A light collector 12, such as the trough shown in Figure 2b, is positioned adjacent the tank 20, with the associated light

tubes or panels 22 projecting into the interior adjacent the media 30.

The foregoing description provides illustration of the inventive concepts. The descriptions are not intended to be exhaustive or to limit the disclosed invention to the precise form disclosed. Modifications or variations are also possible in light of the above teachings. The embodiments described above were chosen to provide the best application to thereby enable one of ordinary skill in the art to utilize the inventions in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention.