Classifications

• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
  • C12N1/00—Microorganisms; Compositions thereof; Processes of propagating, maintaining or preserving microorganisms or compositions thereof; Processes of preparing or isolating a composition containing a microorganism; Culture media therefor
  • C12N1/12—Unicellular algae; Culture media therefor
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
  • C12M1/00—Apparatus for enzymology or microbiology
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01G—HORTICULTURE; CULTIVATION OF VEGETABLES, FLOWERS, RICE, FRUIT, VINES, HOPS OR SEAWEED; FORESTRY; WATERING
  • A01G15/00—Devices or methods for influencing weather conditions
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/34—Chemical or biological purification of waste gases
  • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
  • B01D53/84—Biological processes
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  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
  • C12M1/00—Apparatus for enzymology or microbiology
  • C12M1/14—Apparatus for enzymology or microbiology with means providing thin layers or with multi-level trays
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
  • C12M21/00—Bioreactors or fermenters specially adapted for specific uses
  • C12M21/02—Photobioreactors
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
  • C12M23/00—Constructional details, e.g. recesses, hinges
  • C12M23/02—Form or structure of the vessel
  • C12M23/14—Bags
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
  • C12M23/00—Constructional details, e.g. recesses, hinges
  • C12M23/02—Form or structure of the vessel
  • C12M23/18—Open ponds; Greenhouse type or underground installations
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
  • C12M23/00—Constructional details, e.g. recesses, hinges
  • C12M23/50—Means for positioning or orientating the apparatus
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
  • C12M23/00—Constructional details, e.g. recesses, hinges
  • C12M23/58—Reaction vessels connected in series or in parallel
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
  • C12M27/00—Means for mixing, agitating or circulating fluids in the vessel
  • C12M27/18—Flow directing inserts
  • C12M27/20—Baffles; Ribs; Ribbons; Auger vanes
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
  • C12M33/00—Means for introduction, transport, positioning, extraction, harvesting, peeling or sampling of biological material in or from the apparatus
  • C12M33/18—Rollers
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
  • C12M33/00—Means for introduction, transport, positioning, extraction, harvesting, peeling or sampling of biological material in or from the apparatus
  • C12M33/22—Settling tanks; Sedimentation by gravity
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
  • C12M39/00—Means for cleaning the apparatus or avoiding unwanted deposits of microorganisms
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
  • C12M43/00—Combinations of bioreactors or fermenters with other apparatus
  • C12M43/04—Bioreactors or fermenters combined with combustion devices or plants, e.g. for carbon dioxide removal
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2257/00—Components to be removed
  • B01D2257/50—Carbon oxides
  • B01D2257/504—Carbon dioxide
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
  • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
  • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
  • Y02C20/00—Capture or disposal of greenhouse gases
  • Y02C20/40—Capture or disposal of greenhouse gases of CO2
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/50—Improvements relating to the production of bulk chemicals
  • Y02P20/59—Biological synthesis; Biological purification
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P60/00—Technologies relating to agriculture, livestock or agroalimentary industries
  • Y02P60/20—Reduction of greenhouse gas [GHG] emissions in agriculture, e.g. CO2

Definitions

• This invention relates to generally to the field Of CO 2 sequestration and more specifically to an apparatus and methods for sequestering CO 2 using algae.
• CO 2 carbon dioxide
• Land-based algae systems are very effective in capturing CO 2 , but are limited by available land space and cost. In an open passive or batch system, it is only possible to produce approximately 150 metric tons of dry biomass from algae per hectare per year. Using these figures, it would require over 200 hectares of open land to capture the output from a 1000-megawatt gas turbine power plant, not even taking into consideration weather and water availability.
• Critical to the production of large amounts of algae is the presence of light. Algae uses light to convert CO 2 into sugars, i.e. photosynthesis. Unfortunately, light only penetrates a few centimeters into an active culture of algae. As the algae organisms multiply and the culture density increases, the degree of light penetration decreases.
• An apparatus and method for sequestering and removing CO 2 from a gas using algae are described herein.
• the disclosed apparatus and methods provide a continuous process for the sequestration of CO 2 using one or more bioreactors, each having baffled channels that allow the algae to react with CO 2 .
• Each bioreactor is formed from a transparent or translucent polymeric material that forms a channel therethrough that is inexpensive as well as easily manufactured.
• the channel through the transparent or translucent polymeric material provides a large surface area for light exposure allowing greater exposure of the algae to light as well as flexibility in channel configurations.
• the apparatus for sequestering CO 2 comprises a culture tank containing a suspension of water and at least one type of algae.
• the culture tank comprises a plurality of gas jets for introducing a C ⁇ 2 -containing gas into the suspension.
• the apparatus also comprises one or more bioreactors each forming a channel for the flow of the suspension therethrough, wherein each bioreactor comprises a plurality of baffles and an inlet. Each inlet is located preferably at the top of each bioreactor and is in fluid communication with the culture tank.
• the apparatus comprises a pump for pumping the suspension to the inlets at the top of the one or more bioreactors.
• a method of sequestering CO 2 comprises introducing a CO 2 - containing gas into a culture tank filled with a suspension of water and at least one algae such that the CO 2 is dissolved in the suspension.
• the method further comprises flowing the suspension from the culture tank through a plurality of vertically suspended bioreactors by gravity flow, the plurality of bioreactors each having culture channels with a plurality of horizontal baffles.
• the method comprises exposing the bioreactors to light.
• the method comprises converting the CO 2 into at least one organic compound by photosynthesis.
• Figure 1 illustrates a schematic of an apparatus for sequestering CO 2 using algae
• Figure 2 illustrates a cross-sectional side-view and frontal view of a portion of an embodiment of a bioreactor culture channel
• Figure 3 illustrates another embodiment of a bioreactor culture channel
• Figure 4A illustrates an elevation view of a bioreactor with vertical baffles
• Figure 4B illustrates an elevation view of an embodiment having upwardly angled baffles
• Figure 4C illustrates an elevation view of an embodiment having upward and downward angled baffles in a parallel configuration
• Figure 4D illustrates an elevation view of an embodiment having all downward angled baffles
• Figure 5A illustrates a top view of a configuration of one or more bioreactors in a rectangular matrix formation
• Figure 5B illustrates a top view of configuration of one or more bioreactors in another rectangular matrix configuration
• Figure 5C illustrates a top view of a configuration of one or more bioreactors in a polygonal configuration
• Figure 6 illustrates a cleaning apparatus for a bioreactor. NOTATION AND NOMENCLATURE
• Figure 1 illustrates an embodiment of an apparatus for sequestering CO 2 using algae.
• the apparatus includes a culture tank 101, a pump 122, and one or more bioreactors 131.
• the culture tank 101, pump 122, and bioreactors 131 are all in fluid communication with each other and are all connected to each other via a plurality of conduits or lines.
• the culture tank 101 is filled with a suspension of algae and water.
• culture tank 101 has a rectangular structure.
• culture tank 101 may be of any configuration, i.e. cylindrical, known to one of ordinary skill that is optimal for culturing algae.
• Culture tank 101 is made out of materials that are resistant to corrosion such as polymers or stainless steel.
• culture tank 101 is constructed out of plastic, plastic liner, treated metal, or combinations thereof.
• culture tank 101 is closed to the atmosphere such that apparatus 100 is a closed system. Having a closed system prevents contamination of the algae suspension as well as evaporation of the water.
• the only gas entering culture tank 101 is through gas jets 103.
• all culture medium and fluids entering bioreactors 131 are preferably sterile to further prevent contamination. That is, the suspension is flowed through the bioreactors 131 under sterile conditions.
• sterile conditions may refer to conditions known to those of ordinary skill in the art sufficient to maintain an aseptic environment free of contaminating germs or microorganisms.
• Culture tank 101 also comprises at least one gas jet 103.
• the gas jets 103 introduce a CO 2 - containing gas into culture tank 101.
• Gas jets 103 may comprise any type of suitable inlets such as valves, nozzles, or gas diffusers.
• the plurality of gas jets 103 comprise a plurality of gas diffusers. Gas diffusers break up the introduced gas into smaller, more soluble bubbles.
• the plurality of gas jets 103 are located at the bottom of culture tank.
• any suitable algae may be cultured in the tank 101.
• the algae species Chlorella
• suitable algae species include, without limitation, red algae, brown algae, Spirulina, or combinations thereof.
• the algae species is preferably non-filamentous so as not to clog the apparatus.
• the algae species is a single-cell algae species ranging from about 1 micron to about 15 microns.
• water i.e. tap water or distilled water
• water is used to culture the algae.
• the water is sterile and free from all contaminants.
• saltwater may be used to culture saltwater species of algae.
• any appropriate culture mediums know to those of skill in the art may be used depending on the specific algae species.
• a plurality of fish may be maintained in culture tank 101.
• the fish consume algae as well as produce nitrate in the form of feces.
• the fish feces are used to further nourish the algae.
• culture tank 101 may include one or more feed inlets to introduce or provide additional nutrients to the algae.
• the one or more feed inlets may be coupled to one or more feed tanks filled with specific types of nutrients, minerals, mediums, or the like.
• the one or more feed tanks may be disposed in series or in parallel to culture tank.
• feed inlets and feed tanks are maintained under sterile conditions.
• a feed conduit 120 extends from the culture tank 101 to the pump 122.
• Pump 122 is any suitable device capable of pumping the suspension. Examples of suitable devices include without limitation, centrifugal pumps, impeller pumps, or rotary pumps.
• feed conduit 120 additionally comprises an air inlet valve 124 allowing more C ⁇ 2 -containing gas to saturate the algae suspension. Air inlet valve 124 allows gas to enter the feed conduit 120, but does not allow any of the algae suspension to escape. Thus, the algae suspension is constantly being supplied with carbon dioxide.
• Feed conduit 120 further extends from pump 122 to an inlet manifold 151. Inlet manifold 151 distributes the CCVenriched algae suspension to the inlets 132 of each bioreactor 131.
• the inlet 132 of each bioreactor 131 is preferably located on the top of each bioreactor 131 such that the algae suspension flows downward through the bioreactor as shown in Figure 2.
• the bioreactors 131 are generally constructed from any transparent or translucent polymeric material.
• a polymeric material that is permeable to light is preferably a flexible material.
• a flexible material allows the bioreactor to compensate for different flow rates as well as being easier to handle.
• the polymeric material may even possess elastic properties. Examples of suitable materials include without limitation, polypropylene, polystyrene, polypropylene-polyethylene copolymers, polyurethane, or combinations thereof.
• the bioreactors 131 are made of polyethylene. Any type of polyethylene may be used including high-density polyethylene or low-density polyethylene.
• the polymeric material is UV treated to withstand repeated and extended exposure to light.
• the thickness of the polymeric material is in the range of about 3 mm to about 10 mm, more preferably from about 4 mm to about 6 mm.
• the polymeric material preferably has a tensile strength capable of withstanding the weight of at least 50 gallons of water.
• the polymeric material is typically produced in the form of a tube and is heat sealable.
• the tubular polymeric material is folded forming adjacent sides that are heat sealed to close the upper and lower ends of the tubular polymeric material and to form internal flow channels 133, hereinafter described in further detail.
• the bioreactors 131 may be made from two planar sheets of polymeric material that are heat sealed to seal the sides of the bioreactors 131.
• bioreactors 131 are substantially planar in configuration.
• each bioreactor is about 10 ft tall and about 2 ft wide, alternatively about 10 ft tall and about 4 ft wide, alternatively about 10 ft tall and about 10 ft wide.
• each bioreactor may range from about 4 feet wide to about 30 feet wide and from about 5 feet tall to about 20 feet tall.
• the heightwidth ratio of each bioreactor may be any ratio. In embodiments, the heightwidth ratio of each bioreactor may range from about 10: 1 to about 1: 1.
• each bioreactor 131 may have different heights and widths in order to optimize light exposure to the circulating algae.
• Flow channels 133 are formed by a plurality of baffles or partitions 135.
• Baffles 135 serve to maximize the residence time of the algae in each flow channel 133. The greater the residence time of the algae, the longer the algae in the bio-reactor 131 is exposed to light.
• the residence time of the algae in bioreactors 131 may range from about 1 minute to about 60 minutes, alternatively from about 5 minutes to about 45 minutes, , alternatively from about 10 minutes to about 15 minutes.
• the baffles 135 may be created by heat-sealing the polymeric material at specific locations along adjacent sides of the material. Baffles 135 define the flow channel 133 within each bioreactor 131.
• Figure 2 shows a cross-section of channels 133 in a typical embodiment of a bioreactor 131.
• h refers to the height of each channel 133 (the space between each baffle 135) and w refers to the maximum width of each channel 133.
• h is no more than about 3 inches. Additionally, in most embodiments, h is preferably no more than about 2 inches.
• the width, w, of each channel is set such that the algae flowing through each channel 133 receives sufficient light to survive.
• the weight of the suspension flowing through the bioreactor stretches the polymeric material causing the width w to be maintained at a minimum so as to allow the light passing through the polymeric material to reach all of the algae in the suspension flowing through the channels 133.
• baffles 135 are arranged in an alternating horizontal configuration to form generally horizontal channels 139 and end channels 137.
• Each horizontal channel 139 has an open end 141 and a closed end 143.
• End channel 137 is formed around the open end 141 of an upper baffle 135 together with a closed end 143 of an adjacent lower baffle 135.
• Baffles 135 form a serpentine configuration of the channel 133.
• Each baffle end 141 creates turbulence in the algae suspension as it flows downward through the bioreactor 131.
• baffles 135 are angled upward to increase residence time of algae in bioreactor 131 as shown in Figure 3. That is, each baffle 135 forms an upward acute angle 155 with the side 157 of bioreactor 131 toward the top of bioreactor 131.
• a corner 149 or pocket is formed at the intersection of each baffle 135 and side 157 of bioreactor 131. Corner 149 may cause the formation of vortexes in the circulating algae and culture medium.
• baffles 135 may be angled downwardly as shown in Figure 4D.
• baffles 135 may be angled at any suitable angle from the side 157 of bioreactor 131 ranging from about 30° to about 160°.
• each baffle 135 is angled at the same angle.
• each baffle 135 may be angled at different angles to each other.
• Figures 4A-D illustrate various configurations of baffles 135 which may be incorporated into bioreactor 131.
• FIG 4B shows an embodiment where baffles 135 are all upwardly angled.
• Figure 4C shows an embodiment where baffles 135 are configured in an alternating upward and downward angled parallel arrangement.
• Figure 4D shows an embodiment where baffles 135 are all downwardly angled.
• the arrangement of baffles 135 are not limited by these embodiments, but may comprise an unlimited number of configurations to increase the sequestration of CO 2 by the algae.
• each bioreactor may comprise a different baffle arrangement or configuration in order to optimize algae residence time.
• the plurality of transparent bioreactors 131 are suspended or hung vertically. Bioreactors 131 may be hung in any suitable configuration.
• FIGS 5A-C depict a schematic top view of the different variations at which the bioreactors 131 may be hung or suspended from a top-down view.
• Figure 5 A shows a typical embodiment in which the bioreactors are configured in a rectangular matrix formation.
• the matrix is two bioreactors wide and 6 bioreactors channels deep.
• FIG. 5B shows yet another embodiment in which the matrix is 6 bioreactors wide and two bioreactors deep.
• the bioreactors 131 preferably are no more than 6 inches apart.
• Figure 5C illustrates another embodiment in which the bioreactors are arranged in a polygonal configuration.
• the bioreactors provide nearly unlimited possibilities in configurations so as to maximize exposure of the culture medium to light.
• bioreactors 131 are hung at different heights. Hanging bioreactors
• an outlet manifold 153 directs flow from the outlet 134 of each bioreactor 131.
• outlets 134 are located at the bottom of each bioreactor and lead to an outlet manifold 153.
• Outlet manifold 153 distributes the flow into an outlet conduit 139.
• Outlet conduit 139 recirculates the algae suspension back into culture tank 101.
• each bioreactor 131 has an individual outlet conduit coupled to each outlet 134. Each outlet conduit then drains directly into culture tank.
• each bioreactor 131 includes a gas inlet 163 as seen in Figure 2. Gas inlet 163 is typically disposed at the bottom or lower end of each bioreactor 131. However, gas inlet 163 may be disposed at any portion of bioreactor 131.
• gas inlet 163 may be coupled to gas supply line 107. Furthermore, gas inlet 163 may include a valve for adjusting the flow of gas into bioreactor 131. The function of gas inlet 163 will be described in more detail below.
• outlet manifold 153 may have one or more vents to purge any excess oxygen present in the bioreactors. The one or more vents may comprise one or more purge valves. Furthermore, the one or more vents may vent excess oxygen in a manner such as to maintain sterile conditions in the bioreactors 131.
• bioreactor 131 includes at least two cleaning members 148 to cause any algae clinging to the interior of the bioreactor 131 to drop off and flow through the bioreactor 131.
• cleaning members 148 are elongate bars or rollers movably disposed horizontally on either face of bioreactor 131.
• bioreactor 131 is disposed in between cleaning members.
• cleaning members 148 are coupled to vertical tracks 146 disposed on both sides of bioreactor 131. Cleaning members 148 may compress bioreactor 131 between each member 148 and move vertically up or down the height of bioreactor 131 to release any algae that has attached to the inner surface of bioreactor 131.
• cleaning members 148 may be coupled to vertical tracks 146 by movable screw arms such that cleaning members 148 move up and down to compress or release each bioreactor 131.
• Cleaning members 148 may be operated by computer control or manually.
• an artificial light source is provided.
• the light source preferably is natural sunlight, one or more artificial light sources may also be utilized. Examples of suitable artificial light sources are fluorescent lamps, halogen lamps, etc. In a specific embodiment, a combination of metal halogen lights and a sodium vapor light is utilized.
• the artificial light sources may be arranged around the one or more bioreactors 131 to provide as much light to the algae within each bioreactor 131.
• the apparatus includes an algae harvester 171.
• a tank outlet conduit 163 runs from the culture tank 101 to algae harvester 171.
• algae harvester 171 comprises a filter to strain out algae from the algae suspension.
• Algae harvester 171 also comprises a conveyer, which passes by a heating device to remove moisture from the algae. The conveyer runs to a collector, which is capable of straining out the dried algae.
• the apparatus includes a water reclamation device or recycler 173.
• Water vapor is pumped from culture tank 101 to water recycler 173 via the water recycle conduit 161.
• the water recycler 173 includes a condenser, which condenses the water vapor.
• the water recycler 173 comprises a filtration system to purify the water before sending the recycled water back to the culture tank 101.
• water recycler 173 may comprise any device known to those of skill in the art used to purify water.
• the one or more bioreactors 131 are entirely covered by a protective shell 181.
• the function of the shell 181 is to prolong the life of bioreactors 131 and protect them from environmental elements such as wind and rain.
• the protective shell 181 is a Quonset-type shell.
• the Quonset-shell is preferably made of a weatherproof material that is permeable to light. Examples of suitable materials include without limitation, polyethylene, polycarbonate, polyvinylchloride, polypropylene, or glass.
• the protective shell 181 is a greenhouse-type enclosure. In such embodiments, the heat produced within the greenhouse-type enclosure can be converted to electrical power for powering supplemental artificial light sources.
• various lines such as inlet conduit 120 or outlet conduit 139 may be run deep underground to cool the culture medium and algae.
• the ground may act as a natural heat sink or heat exchanger to absorb heat from the warmer fluid within the lines. Even during the hot summer months, the ground may remain cool enough to cool the culture medium and algae flowing through apparatus 100.
• a method for sequestering CO 2 comprises forcing CCVcontaining gas into a culture tank 101 containing a suspension of algae and water through gas jets 103.
• the gas jets 103 bubble the gas into the algae suspension.
• gas jets 103 are provided gas from gas supply line 107.
• ambient air is bubbled into the culture tank 101.
• the CO 2 in the gas is then dissolved in the algae suspension.
• the algae suspension entering the feed conduit 120 has a predetermined CO 2 concentration.
• the CO 2 level is no more than about 5,000 ppm, alternatively no more than about 2,500 ppm, alternatively no more than about 1 ,000 ppm.
• CO 2 concentration beyond a certain level causes the algae suspension to become acidic, thereby stunting algae growth.
• the CCVenriched algae suspension is pumped from the culture tank 101 through feed conduit 120 to inlet manifold 151.
• culture tank 101 is located underground.
• pump 122 pumps the algae suspension from underground culture tank 101 to the top of the bioreactors 131 through feed conduit 120.
• culture tank 101 is elevated at the same height as the top of bioreactors 131.
• the algae suspension flows from culture tank into the inlet manifold 151 by gravity. Pump 122 is instead used to pump the algae suspension from outlet line 139 to culture tank 101.
• Inlet manifold 151 distributes the algae suspension to the top of each vertically suspended bioreactor 131. From inlet manifold 151, the algae suspension flows down through circuitous channels 133 of bioreactors 131 also via gravity flow. As the suspension flows down through the bioreactors 131, the algae in the mixture are exposed to light, preferably natural sunlight. The algae uptakes or sequesters the CO 2 dissolved in the suspension and converts it into sugars and carbohydrates through the process of photosynthesis. In photosynthesis, a photon strikes a chloroplast within the organism. The chloroplast contains the compound, chlorophyll. In the presence of chlorophyll and CO 2 , a chemical reaction takes place forming carbohydrates, sugars, and oxygen.
• the algae sequester the CO 2 and convert it into other useful carbon compounds.
• the produced compounds are a source of nutrients for the algae allowing further growth and production of algae.
• the algae go through cellular respiration, converting the sugars into energy for the production of further algae.
• about 1,000 to about 1,200 tons Of CO 2 per hectare of land may be sequestered a year.
• the flow rate of the algae suspension is dependent on the height of bioreactors 131 among other factors.
• the flow rate of the suspension flowing through each bioreactor may range from about 1 gallon/hr to about 100 gallons/hr, preferably from about 5 gallons/hr to about 75 gallons/hr, more preferably from about 10 galloons/hrto about 50 galloons/hr.
• the flow rate of the algae suspension through the bioreactors may range from about 1 cm/s to about 50 cm/s, preferably from about 3 cm/s to about 25 cm/s, more preferably from about 5 cm to about 15 cm/s.
• the algae suspension exits bioreactors 131 through an outlet manifold 153 that combines the output from each bioreactor into a single outlet conduit 139, re-depositing the enriched algae into culture tank 101.
• each bioreactor 131 has an outlet conduit, which flows directly into culture tank 101.
• each bioreactor 131 has an outlet conduit which directs the algae into the inlet of another bioreactor 131.
• algae may be circulated or cycled through each bioreactor 131 at least once to maximize exposure of the algae to light.
• the algae from the one or more bioreactors 131 eventually return to culture tank 101 and then are continuously recirculated again and again through one or more bioreactors 131.
• the advantage of the continuous process is that even if some algae do not receive sufficient light in one cycle, chances are that those algae eventually will be exposed to light because of the continuous re-distribution of the algae through the one or more bioreactors 131.
• a gas such as carbon dioxide is introduced (e.g. bubbled) in each bioreactor 131 through gas inlet 163.
• the gas may be introduced from gas supply 107 or from another source such as ambient air. Any suitable gas may be introduced into bioreactor 131 through gas inlet.
• the gas introduced into bioreactor 131 may serve several purposes. For instance, the bubbling action of gas through the bioreactor 131 may facilitate further agitation and mixing of the algae and the culture medium within bioreactor 131. Without being limited by theory, the introduction of gas also may serve to maintain the rate of photosynthesis by the algae as the photosynthetic reaction is dependent on CO 2 concentration. If the CO 2 concentration within the bioreactor 131 drops too low, the algae may cease its photosynthesis.
• introduction of C ⁇ 2 -containing gas into bioreactor 131 via the gas inlet may provide a further means of absorbing or sequestering CO 2 from the ambient air.
• algae growth or concentration may be monitored by measuring the light level, which penetrates each bioreactor. For example, if the light level is less than about 250 footcandles, algae growth has likely reached a saturation point or density in which light cannot penetrate the innermost areas of bioreactors.
• algae growth or concentration may be measured using methods or devices known by those of skill in the art to measure cell density (i.e. cells/mL of culture solution). For example, devices and methods such as without limitation, a Coulter Counter ® or centrifugation may be used to determine cell density.
• conditions inside apparatus 100 may be monitored using any suitable type monitoring devices. Other variables that may be monitored include without limitation, pH, temperature, flow rate, and pressure.
• the algae harvester 171 is used to remove and recover algae so that it can be used for other purposes.
• algae is filtered from the algae suspension and then deposited on a conveyer belt.
• the conveyor belt passes through a drying chamber or a heater to dry the algae.
• the dried algae are then collected for future use.
• the dried algae are used to produce oil for biodiesel.
• the dried algae can be used in many applications including without limitation, nutritional tablets for livestock, fuel for wood-burning stoves, and components for paper products.
• the filtered water is returned to culture tank 101 through recycle conduit 165.
• the disclosed methods and apparatus are capable of reducing the CO 2 level in an area by an amount ranging from about 100 ppm to about 1,900 ppm.

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