WO2009142765A2 - Apparatus and methods for photosynthetic growth of microorganisms in a photobioreactor - Google Patents

Apparatus and methods for photosynthetic growth of microorganisms in a photobioreactor Download PDF

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Publication number
WO2009142765A2
WO2009142765A2 PCT/US2009/003182 US2009003182W WO2009142765A2 WO 2009142765 A2 WO2009142765 A2 WO 2009142765A2 US 2009003182 W US2009003182 W US 2009003182W WO 2009142765 A2 WO2009142765 A2 WO 2009142765A2
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light
array
culture
growth
tank
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PCT/US2009/003182
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French (fr)
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WO2009142765A3 (en
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Nicholas Eckelberry
Steven Shigematsu
Christopher Beaven
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Orginoil, Inc.
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Priority to US12/126,842 priority Critical patent/US20090291485A1/en
Priority to US12/126,842 priority
Priority to US13095708A priority
Priority to US12/130,957 priority
Priority to US61/061,661 priority
Priority to US6166108P priority
Priority to US8130608P priority
Priority to US61/081,306 priority
Priority to US12/349,298 priority
Priority to US34929809A priority
Application filed by Orginoil, Inc. filed Critical Orginoil, Inc.
Publication of WO2009142765A2 publication Critical patent/WO2009142765A2/en
Publication of WO2009142765A3 publication Critical patent/WO2009142765A3/en

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    • CCHEMISTRY; METALLURGY
    • C12BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12NMICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N13/00Treatment of microorganisms or enzymes with electrical or wave energy, e.g. magnetism, sonic waves
    • CCHEMISTRY; METALLURGY
    • C12BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12MAPPARATUS 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
    • C12M21/00Bioreactors or fermenters specially adapted for specific uses
    • C12M21/02Photobioreactors
    • CCHEMISTRY; METALLURGY
    • C12BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12MAPPARATUS 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
    • C12M31/00Means for providing, directing, scattering or concentrating light
    • C12M31/12Rotating light emitting elements
    • CCHEMISTRY; METALLURGY
    • C12BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12NMICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N1/00Microorganisms, e.g. protozoa; 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
    • C12N1/06Lysis of microorganisms
    • C12N1/066Lysis of microorganisms by physical methods
    • CCHEMISTRY; METALLURGY
    • C12BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12NMICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N1/00Microorganisms, e.g. protozoa; 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
    • C12N1/12Unicellular algae; Culture media therefor
    • CCHEMISTRY; METALLURGY
    • C12BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12PFERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
    • C12P5/00Preparation of hydrocarbons or halogenated hydrocarbons
    • C12P5/02Preparation of hydrocarbons or halogenated hydrocarbons acyclic
    • C12P5/023Methane
    • CCHEMISTRY; METALLURGY
    • C12BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12PFERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
    • C12P7/00Preparation of oxygen-containing organic compounds
    • C12P7/64Fats; Fatty oils; Ester-type waxes; Higher fatty acids, i.e. having at least seven carbon atoms in an unbroken chain bound to a carboxyl group; Oxidised oils or fats
    • C12P7/6436Fatty acid esters
    • C12P7/6445Glycerides
    • C12P7/6463Glycerides obtained from glyceride producing microorganisms, e.g. single cell oil
    • CCHEMISTRY; METALLURGY
    • C12BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12PFERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
    • C12P7/00Preparation of oxygen-containing organic compounds
    • C12P7/64Fats; Fatty oils; Ester-type waxes; Higher fatty acids, i.e. having at least seven carbon atoms in an unbroken chain bound to a carboxyl group; Oxidised oils or fats
    • C12P7/6436Fatty acid esters
    • C12P7/649Biodiesel, i.e. fatty acid alkyl esters
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E50/00Technologies for the production of fuel of non-fossil origin
    • Y02E50/10Biofuels, e.g. bio-diesel
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E50/00Technologies for the production of fuel of non-fossil origin
    • Y02E50/30Fuel from waste, e.g. synthetic alcohol or diesel

Abstract

System and methods for enhancing mass production of algae, diatoms or other photosynthetic organism are described, involving the use of light arrays configured to provide photosynthetically effective illumination from closely distributed lights spaced at strategic intervals in order to appropriately increase contact between photosynthetic water-based organisms and light. Illumination and/or nutrient provision can be timed so as to disperse light and/or nutrients when the organism is in a receiving mode. A process flow system is also described which can be scaled for the mass production of photosynthetic based organism, and which can be set up in modular and preferably portable form. The systems and methods are useful in applications such as energy production, fuels, foods, pharmaceuticals, plastics, and CO2 fixation. Also described are systems and methods for lysing cells and extracting components, and for producing electricity with CO2 recycling.

Description

APPARATUS AND METHODS FOR PHOTOSYNTHETIC GROWTH OF MICROORGANISMS IN A PHOTOBIOREACTOR
FIELD OF THE INVENTION
[0001] The present invention relates to apparatus and methods for photosynthetic growth of microorganisms in a photobioreactor system, and for obtaining useful products from such systems.
BACKGROUND OF THE INVENTION
[0002] The following discussion is provided solely to assist the understanding of the reader, and does not constitute an admission that any of the information discussed or references cited constitute prior art to the present invention.
[0003] Natural light consists of a continuous spectrum of wavelengths, and a portion of this spectrum, ultraviolet or UV rays, is recognized as harmful to algal growth while other, relatively narrow bands of the light spectrum are recognized as critically important for optimum growth. In photosynthesis, light must first be absorbed in order to produce conversion of CO2 to carbohydrate. Continuous full frequency light is wasteful because algae cannot use light while it is absorbing and fixing carbon as part of its metabolic process, and because a significant fraction of the light energy is wasted because it is not utilized in the photosynthetic process. Therefore, extraneous light frequencies may beneficially be reduced or eliminated. It has also been determined that the frequencies of light for most effective photosynthesis and growth vary for different species being grown.
[0004] For efficient algal growth, light must therefore be distributed at the right frequencies and only for the time required for the photosynthesis process to occur. This time frame is roughly 1 second of light exposure for the initial reactions to occur, with 6 seconds for the conversion process of fixing CO2 into a carbohydrate. Previously described methods and apparatus for culturing algae in mass quantities generally fail to properly provide appropriate light exposures for optimal algal growth. [0005] In outdoor raceways, for example, UV exposure from the full spectrum natural light results in algae at the surface of the water oxidizing, algae in secondary levels receiving some light in a limited fashion, and algae in tertiary layers receiving little light and therefore dying degrading, creating a anaerobic bio- mass that affects the overall growth of the raceway. Attempts to solve this problem led to the creation of shallow ponds or raceways. However, such shallow water approaches engender the problem of high evaporation and saline deposits, which also reduces the efficacy of continuous outdoor growth. Weather, diurnal cycles and invasion by opportunistic species further aggravate the difficulties of mass algae culturing in outdoor settings.
[0006] It has therefore been determined that growing algae in a photo-bio- reactor (PBR) would be the preferred method of mass culturing algae provided energy costs are dramatically reduced and a compact infrastructure is designed that addressed the concerns of light and nutrient delivery while providing for high density growth of fresh and sea-water organisms. For most applications, the system must also be scalable to suit the escalating fuel and electricity demands of the planet.
[0007] In current PBRs, the costs in lighting and energy requirements have made prior solutions impractical for all but the culturing of organisms used in high value products in pharmaceuticals or neutraceuticals.
[0008] In early work by William Oswald described in Pat. No. 3520081 , a rotating tank that enhances contact between algae and light to accelerate algae growth was used. Oswald points to the inherent problem of mass culturing of algae as providing a suitable environment for optimum growth since algae growth as a mass feed stock is limited by two factors: close proximity to light and nutrients. Additionally algae species, in particular high growth genus with valuable attributes such as lipid or carbohydrate content (TAGs)1 such as Nanochloropsis, chlorella and others, all require specific light frequencies and nutrients for accelerated growth. And while the use of rotating tanks has some benefits, the impracticality of scale becomes apparent when discussing very large scale systems, e.g., multi million gallon systems. [0009] Robinson et al., Pat. No. 5137828, suggests that a central core of light within a tube would enhance production by bringing the algae mass in contact with light and nutrients. This method has the benefits of lowering the land mass required for mass algae production and filtering out unwanted UV light frequencies by the strategic uses of reflective surfaces. Distinct problems with this method were fouling of the tube's surface by organic matter and the small industrial scale.
[0010] Yang et al., Pat. No. 5614378, addresses the problem of fouling with a cleaning system incorporated within a network of optical fibers in a life support system that generates oxygen. Scaling of this system to mass culturing is impractical and indeed not the intent of this PBR, as it is designed for life support in space.
[0011] Muhs et al., U.S. Pat. No. 6603069, describes a method of capturing light from a solar collector which feeds light at the correct frequency through a network of fiber-optics into a bio-reactor.
[0012] Hirabayashi et al. US Pat 6579714 describes an algae culture apparatus and method utilizing a growth apparatus having spaced apart inner and outer walls which are dome-shaped, conical, or cylindrical. Light can pass through the walls into the space between where the algae are cultured.
[0013] Yogev et al., US Pat 5958761 describes a "bioreactor for improved productivity of photosynthetic algae [which] includes a tubular housing surrounding a tubular envelope located therein. The housing and envelope define a space there between to be filled with fluid. The housing and envelope are made of at least a translucent material and have inlet and outlet ports providing access to the space and the interior of the envelope. A mixer for mixing algae media is disposed inside the envelope. There is also provided a bioreactive system, wherein the envelope contains a fluid of selective refractive index and wherein, for a given geometrical relationship between the housing and the envelope, the radiation concentration power is controlled by modifying the refractive index of the fluid." [0014] Raymond, US Pat 4253271 describes an apparatus and process for the culture of algae in a liquid medium in which the medium circulates through an open trough and is exposed to an atmosphere which is temperature regulated. The nutrient content of the liquid medium is regulated to control the chemical composition growth and reproduction characteristics of the cultured algae. Before it is allowed to strike the medium, sunlight is passed through a filter to remove wavelengths which are not photosynthetically active. Heat energy can be recovered from the filter.
[0015] In another study, the use of rotating annular reactors with lights placed within was examined. (Zittelli, Rodolfi, and Tredici, 2003, Mass cultivation of Nannochloropsis sp. In annular reactors, J Appl Phycology 15:107-114.) The annular reactor consisted of two 2-m-high Plexiglas cylinders of different diameter placed vertically one inside the other so as to form an annular culture chamber. Artificial illumination was supplied by lamps placed inside the inner cylinder.
[0016] In addition to providing suitable growth conditions, in many applications it is commonly desirable to recover particular products from the microorganisms. For such recovery, it is usually necessary to lyse the cells in some manner. Currently, cell lysing is commonly accomplished chemically, such as by using detergents, solvents, or enzymes. However, this approach has the disadvantage of requiring a supply of the appropriate chemicals, with the associated storage and disposal problems. Cell lysing can also be accomplished thermally, either alone or in conjunction with chemical treatment. However, conventional heating techniques often take a relatively long time, which can result in excessive evaporation and/or cell component degradation.
[0017] Cells can also be lysed using microwave irradiation. Typically, microwave cell lysing appears to be related to thermal cell lysing. (See, e.g., Fujikawa et al., "Kinetics of Escherichia coli Destruction by Microwave Irradiation," Appl Environ Microbiol, 1992 (March), 58:920-24.) Thus, microwave irradiation provides a convenient method for heating samples sufficiently for cell lysing and typically more rapidly than using conventional heating. In addition, cell lysing using microwaves is easier to control, because the microwave radiation may be readily turned on or off as required, and wavelengths and intensities can be selected or adjusted.
[0018] Conventional microwaving (e.g., using current kitchen microwaves and the like) usually use microwaves at 2.45 GHz. Such microwaves function primarily by interacting with the highly polar water molecules in the material being heated. Thus, for example, Pare, US Pat 5002784, issued March 26, 1991 , mentions the use of microwave to explode plant cells and extract material. This patent describes the use of hexane or liquid CO2 as a "transparent" solvent with low dielectric constant versus high water content and its electrical opacity. Two later related patents, US 5338557 and US 5458897 additionally describe a system for the extraction of volatile oils from plant matter. The system still makes use of microwave transparent material to create temperature differentials and the like for optimized extraction.
[0019] In another patent, Nair et al., US Pat 6623945, issued September 23, 2003 describes a system and method for effecting cell lysis of cells in small samples. The system includes a wave guide cavity and utilizes microwaves of 18 to 26 GHz.
[0020] In some algae production processes, attention is given to CO2. Hitzman, US Pat 4,044,500 describes cycling back CO2 as part of a food-based program to increase quality through the use of an aerobic digester. Worthington, US Pat 4,267,038 indicates that spinning off CO2 from waste methane can be used to grow algae for ancillary product, lshida et al. US Pat 4,354,936 indicates that methane gas, when introduced into algae alkalized water, separates out CO2 and results in essentially pure methane. This patent is later cited by Ueda, US Pat 5,578,472 in focusing on the production of ethanol using a loop system of burning the mass to recover methane and CO2, which is then used to grow algae. The goal is the creation of ethanol, which, when used, will release CO2 into the atmosphere. Thus, the Ueda system results in being carbon positive. Hsu et al., US Pat 5,500,306, iss. Mar 19, 1996 states that electricity can be generated from bio-mass, but there is no consideration as to the discharge of CO2 from the generation of electricity though the use of a fuel cell. Each of these patents is incorporated herein by reference in its entirety.
SUMMARY OF THE INVENTION
[0021] This invention provides a solution to vexing problems in culturing of photosynthetic microorganisms, especially algae. In particular, prior photobioreactors have suffered from a number of difficulties which have inhibited broad application of the reactors for bulk applications, including high energy utilization, fouling of light emitting surfaces, and diurnal growth cycles. This invention addresses those problems with a system that provides efficient light utilization with comparatively low energy costs. One feature of this approach is to provide the light at closely spaced intervals within a photobioreactor so that light is provided throughout the photobioreactor rather than just at the surface and/or at culture medium/photobioreactor wall interfaces. This can be accomplished in a number of different ways, for example, using a light array constructed with a central axle with light wands extending from the axle, or an array of light wands extending upwards and/or downwards in the culture medium. Likewise, the growth medium may be passed by the light sources, and/or the light sources may be passed by the medium.
[0022] Thus, a first aspect of the invention concerns a culture system for photosynthetic microorganisms. The system includes a culture tank, at least one light array positioned within the tank, where the light array provides a plurality of light paths sufficiently short to provide photosynthetically effective light to most and preferably substantially all of the photosynthetic microorganisms passing between adjacent light sources in the array. That is, the light emitting projections (e.g., light wands or bars) are positioned such that most and preferably essentially all medium passing between adjacent light emitting projections of the array will receive photosynthetically effective illumination. The system also includes a drive which causes relative motion between growth medium in the culture tank and the light array (e.g., a drive system for moving the light array within the tank and/or a fluid impeller such as a mixer and/or a pump).
[0023] In certain embodiments, the light array is a stationary array; the light array is a rotatable light array; the rotatable light array includes a plurality of light emitting projections projecting from a rotatable axle; the rotatable light array includes a plurality of light emitting projections extending upward, e.g., from a generally planar mounting body; the rotatable' light array includes a plurality of light emitting projections extending downwards, e.g., from a generally planar mounting body; the at least one light array includes a plurality of light emitting projections extending upward and a plurality of light emitting projections extending downward.
[0024] An advantageous embodiment of the system includes at least one rotatable light array positioned within the tank, where the light array includes an axle, a rotational drive connection linked to the axle, a plurality of light emitting projections (e.g., light wands or bars) extending outward from the axle and positioned such that most and preferably essentially all culture media passing between adjacent light emitting projections will receive photosynthetically effective illumination, and a rotational drive linked to and providing power through the rotation drive connection to rotate the rotatable light array.
[0025] In certain embodiments of the system incorporating a rotatable light array about an axle, the array includes a plurality of flat arrays distributed along the axle, e.g., at least 3, 4, 5, 7, 10, 15, 20, 30, 40, or 50 such flat arrays or is in a range defined by taking any two of the specified numbers of flat arrays as inclusive endpoints; the flat arrays are spaced at distances of 0.25 to 10 cm, 0.5 to 10 cm, 0.5 to 7 cm, 0.5 to 5 cm, 0.5 to 4 cm, 0.5 to 3 cm, 0.5 to 2 cm, 1 to 10 cm,
1 to 7 cm, 1 to 5 cm, 1 to 4, 1 to 3 cm, 2 to 10 cm, 2 to 7 cm, 2 to 5 cm, 2 to 4 cm, or 2 to 3 cm along the axis of the axle, with the distance referring to either the center-to-center distance or to the separation between successive wands; the flat array includes at least 2, 3, 4, 5, 7, 10, 15, or 20 wands or is in a range defined by taking any two of the specified values as inclusive endpoints; the rotatable light array rotates at 0.2 to 20, 0.2 to 15, 0.2 to 10, 0.2 to 5, 0.2 to 3, 0.2 to 2, 0.5 to 20, 0.5 to 10, 0.5 to 5,, 0.5 to 4, 0.5 to 3, 0.5 to 2, 1 to 10, 1 to 5, 1 to 4, 1 to 3, or 1 to
2 rpm; the axle is positioned essentially vertically in the tank; the axle is positioned essentially horizontally in the tank.
[0026] In some embodiments, a light array include essentially parallel light wands, e.g., in an essentially planar array; a planar array includes at least 5, 10, 15, 20, 25, 30, 35, 40, 50, 70, or 100 light wands, or is in a range defined by taking any two of the specified values as inclusive endpoints.
[0027] Also in particular embodiments, the light array(s) is moved in the culture such that illumination is provided to a particular volume within the tank repetitively with average repeats of 1 to 20, 1 to 15, 1 to 10, 3 to 20, 3 to 15, 3 to 10, 4 to 10, 4 to 8, or 5 to 7 seconds; the wavelengths of light emitted from the light wands is selected to provide effective photosynthesis while reducing power consumption, e.g., having a luminance peak within the range of 400 and 720 nm and lower luminance outside that band, or with luminance peaks within one or both of the bands of 400 to 510 nm and 600 to 720 nm with lower luminance outside those bands; the peak of luminance emitted in the ultraviolet radiation in the range of 15 to 400 nm (or ranges of 15 to 350, 50 to 400, 50 to 350, 100 to 400, or 100 to 350 nm) is no more than 50, 40, 30, 20, 10, or 5% of the highest luminance peak in the range of 400 to 720 nm.
[0028] In particular embodiments, the system includes at least one light array that includes a plurality of light emitting projections extending upward; a light array with a plurality of upwardly extending light projections is rotatable or fixed or linearly moveable; rotation of an array with upwardly extending light emitting projections is driven by a central drive shaft; downwardly extending light emitting projections in a light array are mounted in a mounting body.
[0029] Similarly in particular embodiments, the culture system includes a light array which includes a plurality of light emitting projections extending downward; a light array with downwardly extending light projections are rotatable, fixed, or linearly moveable; downwardly extending light projection of a light array are mounted in a mounting body, e.g., a generally planar circular mounting body such as a disk; the mounting body of a light array with downwardly extending light projection is positioned above the fluid level in the tank (in use the light emitting projections extend down into the culture medium); rotation of a light array mounting body (e.g., with downwardly extending light emitting projections) is drive by a rim drive; in systems with upwardly extending light emitting projections or downwardly extending light emitting projections or both, light emitting projections are arranged in a sector pattern, e.g., with 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 sectors of light emitting projections in the upwardly extending array or in the downwardly extending array or in both.
[0030] Further, in particular embodiments, the culture system includes a first light array which has a plurality of light emitting projections extending upward and a second array which has a plurality of light emitting projections extending downward either, both, or neither of the arrays are rotatable; in a system with such first and second light arrays, the first and second array intermesh or the light emitting projections of the first array terminate below the light emitting projections of the second array; .
[0031] In certain embodiments, the system also includes at least one channel (and may include at least one reservoir) for distributing nutrients to culture media in the tank, e.g., CO2 and/or nitrogen (for example as nitrates).
[0032] In some systems, a plurality of light arrays are included in a single tank, e.g., at least 2, 3, 4, 5, 7, 10, 15, or 20 such arrays, or a number of arrays in a range defined by taking any two of the specified values as inclusive endpoints.
[0033] Advantageous embodiments include a light controller which controls at least one of the parameters of light intensity, light delivery periodicity, light duration, and light wavelength for light emitted from the light wands; the system includes a controller which controls delivery of at least one nutrient to the culture (e.g., CO2 and/or nitrogen such as in the form of nitrates); the system also includes at least one culture medium sensor, e.g., a sensor(s) producing signals corresponding to pH and/or oxidation reduction potential (ORP) and/or turbidity, preferably a controller receives signals from the sensor and controls light emitted from said light wands at least in part as a function of said signals and/or controls delivery of at least one nutrient (e.g., CO2 and/or nitrogen) to the culture tank.
[0034] In some embodiments, the drive causes circulation of culture medium in the culture tank and through said light array; the drive causes circulation of culture medium in the culture tank and through the light array, and also causes rotation of the light array. [0035] In still further embodiments, photosynthetically effective illumination is provided to substantially all culture medium passing through the light array on substantially the same periodicity and with approximately equal illumination intervals.
[0036] A related aspect concerns a light distribution array in which a plurality of light emitting projections (usually light bars or wands) are positioned such that most, and preferably substantially all, culture medium passing between successive light emitting projections (e.g., light bars) is within one growth plane of a light emitting projection.
[0037] In particular embodiments, the light distribution array is as described for the preceding aspect or otherwise as described for a light array useful in the present invention.
[0038] In certain embodiments, the array includes an axle (preferably rotatable) and a plurality of light emitting wands extending from and distributed along said axle. The wands may for example, be spaced at distances of 0.25 to 10 cm, 0.5 to 10 cm, 0.5 to 7 cm, 0.5 to 5 cm, 0.5 to 4 cm, 0.5 to 3 cm, 0.5 to 2 cm, 1 to 10 cm, 1 to 7 cm, 1 to 5 cm, 1 to 4, 1 to 3 cm, 2 to 10 cm, 2 to 7 cm, 2 to 5 cm, 2 to 4 cm, or 2 to 3 cm along the axis of the axle, with the distance referring to either the center-to-center distance or to the separation between successive wands. In embodiments of other configurations, e.g., a planar array, successive light wands can be distributed at distances or separations as just specified for the axle-type array.
[0039] In certain embodiments (e.g., for an axle-type array), the light distribution array of includes a plurality of flat arrays of light emitting wands; the light emitting wands in an array are distributed over a distance of at least 0.2, 0.3, 0.4, 0.5, 0.7, 1.0, 1.5, 2.0 meters, or more, e.g., along an axle in an axle-type array or in a plane in a planar array; the light emitting wands include at least one light source which is an LED, a cold cathode fluorescent light (CCFL), or an external electrode fluorescent light (EEFL). [0040] Another aspect of the invention concerns a system for carbon fixation and/or product recovery which includes a culture system (e.g., as specified for the first aspect above or otherwise described herein for the invention), a process controller which monitors at least one culture parameter indicative of photosynthesis or growth (e.g., pH, ORP, and/or turbidity) and regulates light (e.g., light duration, light delivery period, light intensity, and/or light wavelength) and/or nutrient delivery (e.g., CO2 and/or nitrogen such as in the form of nitrates) to the culture.
[0041] In certain embodiments, the system includes a culture tank, at least one rotatable light array positioned within the tank, where the light array includes an axle, a plurality of light emitting projections extending outward from the axle and distributed along the axle, and positioned such that essentially all culture medium passing between adjacent light emitting projections will receive photosynthetically effective illumination, and a rotational drive connection. The system also includes a rotational drive which is linked to and provides power through the rotation drive connection to rotate the rotatable light array.
[0042] In certain embodiments, the system also includes an oil extractor, e.g., extracting lipids from the cultured microorganisms, and/or a biomass digester which receives biomass from the culture tank. In some embodiments, CO2 generated from a biomass digester is used as a nutrient in a culture tank.
[0043] The system can also include an electrical generator powered by at least one product of the system, e.g., an oil-based fuel such as biodiesel, biomass, or methane.
[0044] A related aspect of the invention concerns a method for growing photosynthesizing microorganisms, including exposing photosynthetic microorganisms (e.g., algae, diatoms, or photosynthetic bacteria) in a growth medium in a photobioreactor to photosynthetically effective light from a light array, where the light array includes a plurality of light wands spaced such that substantially all of the growth medium between successive light wands in the light array receive photosynthetically effective illumination.
[0045] In particular embodiments the light array is as specified for an aspect above or otherwise described herein for the invention.
[0046] Also in particular embodiments, the microorganisms are grown in a system as specified for an aspect above or otherwise described herein.
[0047] In addition to the systems described above, this invention also provides an advantageous system for culturing photosynthetic microorganisms, especially algae, in a modular and preferably portable configuration. In some embodiments, the modular system can advantageously utilize the systems and methods as described in the aspects above or otherwise described herein for this invention. Thus, this modular system utilizes high efficiency photobioreactors to provide the ability to scale up production while still maintaining a small physical footprint. In desirable systems, the photobioreactors utilize light emitters at closely spaced intervals within a photobioreactor so that light is provided throughout the photobioreactor rather than just at the surface and/or at culture medium/photobioreactor wall interfaces.
[0048] Thus, a further aspect of the invention concerns a modular system for photosynthetic growth of microorganisms (e.g., algae, diatoms, or photosynthetic bacteria). The modular system includes at least one photosynthetic microorganism growth module which includes a support frame, with a plurality of growth tanks mounted in the support frame. Each of the growth tanks includes a growth sensor set and a light array (e.g., as described herein) which has a plurality of light sources. Highly preferably, those light sources are arranged such that photosynthetically effective light is provided by the light sources to substantially all of the culture medium within the volume described by the light array. The growth module also includes a nutrient injection system, and at least one growth process parameter is controlled by a growth controller in response to at least one signal from the growth sensor set. [0049] In particular embodiments, the growth controller is mounted within the support frame, the system also includes at least one processing module (e.g., mounted in a separate support frame), and the growth controller is located in the processing module; the support frame is a freight container; the support frame is a rail car; the growth module is stackable with at least one other growth module and/or with at least one processing module; the modular system includes a plurality of the growth modules, e.g., at least 2, 3, 4, 6, 8, 10 or more such growth modules, or includes 2 to 5, 4 to 8, 5 to 10, or 10 to 20 growth modules.
[0050] Also in certain embodiments, the modular system includes a microorganism processing system, preferably as a processing module. In particular embodiments, the processing system includes at least one or any combination taken 2, 3, or 4 at a time of a lipid separator, a dewaterer, a biomass digester receiving biomass grown in the growth tanks, and a cell disruptor; the system includes a biomass digester and methane generated by the biomass digester is used as a fuel for an electrical generator, e.g., a generator providing electricity to the modular system.
[0051] For some embodiments, a growth module includes 2 to 5, 3 to 6, 4 to 8, 5 to 10, or 10 to 20 growth tanks; each of a plurality of growth tanks in a growth module has a liquid capacity of at least 100, 200, 300, 400, 500, 700, 1000, 2000, 3000, or 4000 liters, or has a liquid capacity of 100 to 500, 300 to 700, 500 to 1000, or 1000 to 5000 liters; a modular system has a culture capacity (or the volume of culture simultaneously grown) of at least 5000, 10,000, 20,000, 30,000, 50,000, or 100,000 liters, or a capacity of 5000 to 20,000, 10,000 to 50,000, 20,000 to 70,000, 50,000 to 100,000, or 100,000 to 500,000 liters.
[0052] In particular embodiments, the modular system includes a dewatering system which removes water from biomass grown in the growth tanks; and a water recycling system which recycles that water back to the growth tanks; the nutrient injection system includes a connection for CO2 from an external CO2 generator, e.g., an electrical power plant burning carbon-based fuel (for example, coal, oil, natural gas, or cellulosic materials); the nutrient injection system includes a CO2 storage tank; the modular system also includes a remote monitoring and control system, e.g., including an internet link.
[0053] A related aspect of the invention concerns a method for growing photosynthetic microorganisms by culturing the microorganisms in a modular system for photosynthetic growth of microorganisms, e.g., a modular system as described for the preceding aspect or otherwise described herein.
[0054] Thus, in advantageous embodiments, the method involves culturing photosynthetic microorganisms in a modular system for photosynthetic growth of microorganisms, where the modular system includes at least one photosynthetic microorganism growth module which includes a support frame, with a plurality of growth tanks mounted in the support frame. Each of those growth tanks includes a growth sensor set and a light array which has a plurality of light sources arranged such that photosynthetically effective light is provided by the light sources to the culture medium, preferably to substantially all of the culture medium within the volume described by the light array or even more preferably to substantially all of the culture medium in the growth tank. The system also includes a nutrient injection system and at least one growth process parameter is controlled by a growth controller in response to at least one signal from the growth sensor set.
[0055] In addition to the photosynthetic microorganism growth systems, the present invention further concerns a system and method for lysing microorganisms and extracting desired materials. In particular, the system is adaptable to extraction of lipids from microorganisms such as algae. The system utilizes inline microwave exposure to heat the cells and thereby lyse or at least weaken the cells. The microwaved cells can then be run through a mixer which creates micro bubbles, leading to further lysis or cell degradation as the bubbles collapse and enhancing separation of lipids from other cellular components. The microwave frequency, duration, and intensity of the microwave treatment can be adjusted to be suitable for the particular organisms and other conditions being treated. [0056] Thus, in a further aspect and as indicated above, the invention concerns a system for lysing microorganisms and extracting particular desired cellular materials, such as but not limited to cellular lipids. The system includes an inline electromagnetic radiation system directing cell disrupting electromagnetic radiation (e.g., a microwave system directing microwave radiation) into microorganisms suspended in an aqueous medium in a conduit. The system also includes a second cell disruption system downstream from the electromagnetic radiation system. The second cell disruption system, may for example, be an ultrasonic system such as a micron mixer, and is positioned such that it accepts the microorganisms (usually as a cell suspension) after they are subjected to the electromagnetic radiation. In embodiments incorporating such micron mixer, the mixer creates microbubbles in the cell suspension medium. The electromagnetic radiation lyses or at least weakens the cell structure, e.g., the cell wall and/or cell membrane, and the second cell disruption system (e.g., ultrasonic system such as a micron mixer) causes additional cell degradation or cell lysis or both.
[0057] In particular embodiments, at least 30, 40, 50, 60, 70, 80, or 90% of the energy of the electromagnetic radiation is in the range of 300 MHz to 300 GHz, 300 MHz to 1 GHz, 1 GHz to 30 GHz1 or of 30 GHz to 300 GHz; the electromagnetic radiation includes effective infrared and/or ultraviolet radiation; the electromagnetic radiation, e.g., microwave radiation, is scanned or stepped over multiple frequencies.
[0058] In particular embodiments, the conduit includes a microwave waveguide; the conduit includes a shielded pipe, e.g., an FCC compliant RF shielded pipe; a culture concentrator, e.g., a filter, vortex or cyclone separator, or centrifuge, is positioned before the inline electromagnetic radiation system (e.g., inline microwave system); the culture concentrator removes at least 50, 60, 70, 80, or 90% of the water of the aqueous medium; the cell suspension after the culture concentrator is a pumpable suspension, or a flowable suspension.
[0059] Also in particular embodiments, the system also includes an oil:water separator positioned to receive medium (e.g., cell suspension after passing through the second cell disruption system (e.g., the static mixer); the oil:water separator separates a lipid phase and an aqueous phase; residual biomass is separated from the lipids; the system also includes a biomass digester, and residual biomass is passed to the digester.
[0060] Likewise, a related aspect concerns a method for obtaining a desired cellular material (e.g., lipids) from a microorganism (typically from microorganism cells in a cell suspension), and involves exposing the microorganisms to cell disrupting electromagnetic radiation in an inline electromagnetic radiation system (e.g., in a microwave system directing microwave radiation) into microorganisms suspended in an aqueous medium in an inline conduit (e.g., microwave radiation within an inline waveguide), where the frequency and intensity are sufficient to lyse or at least weaken the cell wall and/or cell membrane of at least some of said microorganisms. Following the electromagnetic radiation exposure, the microorganism cells are passed through a second cell disruption process, e.g., an ultrasound process such as passing the cells through a micron mixer which creates microbubbles in suspension and then allows the bubbles to collapse.
[0061] In certain embodiments, the method involves processing the microorganism cells through a system as described for the preceding aspect or otherwise described herein for the present invention.
[0062] Also in certain embodiments, the method includes passing the disrupted suspension through an oil:water separator.
[0063] Another related aspect concerns an inline electromagnetic radiation (e.g., microwave) treatment system. The system includes at least one controlled frequency electromagnetic radiation generator (e.g., a signal generator) which produces electromagnetic radiation (e.g., microwave, infrared, or ultraviolet frequency radiation), and an inline electromagnetic radiation system directing cell disrupting electromagnetic radiation (e.g., a microwave system directing microwave radiation) into microorganisms suspended in an aqueous medium in a conduit. Many systems will also include an amplifier which amplifies the electromagnetic radiation signal (e.g., microwave frequency radiation signal) producing amplified electromagnetic radiation, e.g., amplified microwaves. For systems which include an inline microwave radiation system, the system also includes an inline waveguide which receives the amplified microwaves and which is configured to allow flow of a suspension through the waveguide.
[0064] Yet another related aspect concerns a method for lysing microorganism (e.g., an algae), and involves directing microorganisms through a conduit, and directing microwave and/or other cell disrupting electromagnetic radiation of at least one frequency or frequency range into the microorganisms in the conduit at intensity(ies) and at a frequency (ies) sufficient to cause cell lysis or at least cell weakening, e.g., damage or break cell walls and/or cell membranes.
[0065] In particular embodiments, the frequency or frequencies are selected to preferentially target cell membrane lipids and/or at least one major cell wall constituent; the conduit is shielded and functions as a wave guide; the frequency or frequencies include microwave, infrared, and/or ultraviolet frequencies; the electromagnetic radiation is as described above for the first aspect or otherwise described herein for the present invention.
[0066] Yet another related aspect concerns a method for providing an inline electromagnetic radiation lysing system, by selecting one or more electromagnetic radiation frequencies which target cell membrane lipids or cell wall components, e.g., to a significantly greater degree than microwave radiation at 2.45 GHz, and constructing an inline electromagnetic radiation delivery system in which electromagnetic radiation corresponding to one or more of the selected frequencies is delivered to a suspension containing volume. The intensity of the electromagnetic radiation should be sufficient to lyse or at least weaken the cell wall and/or cell membrane of at least one type of microorganism in suspension within the radiation delivery system.
[0067] In particular embodiments, the electromagnetic radiation includes microwave, infrared, and/or ultraviolet radiation; the electromagnetic radiation is adsorbed by the cell membrane lipids or cell wall components at least 0.3, 0.4, 0.5, 0.6, 0.7, 0.8. 0.9, 1.0, 1.2, 1.4, 1.6, 1.8, or 2.0 times the level of absorption by water. [0068] Further related aspects of the invention concern a combined photosynthetic microorganism growth system and lysis system. The system includes a growth system as described above which passes cell suspension to a cell lysis system as also described above. Particular embodiments include each combination of embodiments of the growth system and lysis system. In addition the invention provides a method of photosynthetic cell growth and lysis by using the just-specified system or an embodiment thereof.
[0069] Still further, the present invention concerns systems and methods involving growth of algae in which electricity is generated with substantially no release of carbon dioxide or methane. Preventing or limiting such release is accomplished by recycling CO2 generated from digesting algae biomass and from burning methane or other combustible fuel for electricity generation. Thus, the invention provides electricity generation using an above ground fuel source in CO2 neutral or CO2 sequestering processes.
[0070] The systems utilize a CO2 input to the system (e.g., from any of a variety of CO2 sources. In most cases, additional energy input is also utilized, e.g., electricity input. Highly preferably, such energy input utilizes clean energy sources, e.g., solar, wind, and the like, for electrical power inputs.
[0071] Thus, a first aspect of the invention concerns a method for renewable carbon sequestering production of electricity, which involves growing algae biomass in an algae culture system, separating the algae biomass from culture water, digesting the biomass, thereby producing a combustible fuel (e.g., methane or ethanol), burning the combustible fuel in an electrical generating system, thereby producing electricity, and recycling CO2 from the exhaust gas of the burning to the culture system. Alternatively, the combustible fuel (or a derivative thereof) can be utilized in a fuel cell to generate electricity. For certain types of fuel cells the combustible fuel will be processed in a reformer to produce hydrogen.
[0072] In particular embodiments, the combustible fuel is methane or ethanol; oxygen from the culture system is used in burning the combustible fuel; CO2 (e.g., produced in the digester) is separated from the methane prior to the burning; the culture water is used in separating the CO2 from the methane.
[0073] Also in particular embodiments, oxygen from the culture system is micron mixed with methane or other combustible fuel from the digester prior to burning in the electricity generating system; CO2 is collected from the exhaust gas of the burning and is recycled in the algae culture system.
[0074] In certain embodiments, the method utilizes a system as described below or otherwise described herein for this invention.
[0075] In an alternative aspect, all or part of the biomass produced in the algae growth system is de-watered and burned to provide heat energy for electricity production. CO2 from such burning is captured and recycled in the growth system. Thus, this aspect is substantially like the preceding aspect except that some or all of biomass is not digested. Where none of the biomass is digested, the digester and components for the capture of CO2 and combustible fuel from the digester may be omitted from the system.
[0076] In a related aspect, the invention provides a system for renewable carbon sequestering production of electricity. The system includes an algae culturing tank, an algae/water separator which receives culture medium from the culturing tank and separates algae biomass from culture water, a digester which receives the algae biomass from the separator, where digestion of the biomass in the digester produces methane or other combustible fuel, an electrical generator powered directly or indirectly by the combustible fuel (e.g., methane powered electrical generator which burns the methane from the digester), and at least one CO2 collector which separates methane from CO2 from the digestion or collects CO2 from the exhaust gases from the methane burning or both, wherein the CO2 is recycled for growing algae in the culturing tank.
[0077] In certain embodiments, the CO2 collector includes a CO2 separation column which receives combined methane and CO2 from the digester and removes CO2 leaving at least partially purified methane; the system also includes a static mixer which receives methane from the digester and oxygen from the culturing system and micron mixes the methane and oxygen prior to burning in the methane powered electrical generator; the system also includes an micro mixer which receives green water from the separator .
[0078] In certain embodiments, the system includes a photobioreactor and/or other system components, e.g., as described in Shigematsu & Eckelberry, US Pat Appl 12/126,842, filed 05/23/2008, which is incorporated herein by reference in its entirety.
[0079] As used herein, the term "growth plane" refers to a volume of water irradiated by light in which photosynthetic growth of suspended photosynthetic microorganisms will effectively occur (assuming other growth requirements for such growth are also satisfied). For example, for solar irradiation of algal cultures in ponds, the growth plane commonly extends only about one to a few centimeters down from the surface. In the present apparatus having moving light arrays, a growth plane is defined by the distance light emitted from a light wand will be photosynthetically effective. Thus, successive light wands may be placed two growth planes apart and the entire space between will receive photosynthetically effective illumination.
[0080] In reference to light present in a photosynthetic culture medium, the term "photosynthetically effective" means the intensity of photosynthetically active radiation (PAR) is sufficient for the organism being cultured to perform photosynthesis effectively such that there is net fixation of CO2.
[0081] In connection with the present light arrays, the term "project from", "extends from" and similar terms means that the specified item (e.g., a light wand) terminates in the referenced structure (e.g., a mounting body) and extends a substantial distance from that referenced structure relative to the size of the light array. In many cases, light emitting projections will extend at least 3, 6, 9, 12, 18, or more inches.
[0082] The term "mounting body" refers to a substantially rigid body configured for mounting of light emitting projections [0083] The term "carbon-based fuel" is used to refer to a fuel material which is used directly or indirectly to generate energy through oxidation (typically burning) of carbon-containing compounds. Examples of such fuels include oil, natural gas, short chain alkanes such as methane, ethane, propane, and butane, coal, cellulosic materials, and combinations of such fuels.
[0084] As used herein, in connection with a process, the term "carbon negative" means that there is substantial CO2 from the air being sequestered, e.g., by an energy production system. "Carbon positive" indicates that the process results in a net release of CO2 into the atmosphere, for example by the unconfined burning of carbon-based fuels. "Carbon neutral" process, such as solar and wind power, result in essentially no net sequestration or dispersal of CO2.
[0085] In the context of this invention, the term "culture medium" refers to the aqueous medium used for growth of the algae, which may include the cells being grown or following such growth. After at least the majority of the algae biomass is removed from culture medium following algae growth, the aqueous solution or suspension is termed "green water" or "culture water".
[0086] In the context of the present invention, the term "combustible fuel" refers to one or more organic compounds produced by the system (usually in a digester) which will burn (after ignition) in the presence of oxygen (e.g., the oxygen in air) with release of heat. Examples include methane (and other short chain alkanes) and ethanol (and other short chain alcohols).
[0087] Also in this context, the term "electrical generating system" refers to a set of functionally linked components which, when provided with suitable chemical compounds (e.g., oxygen and at least one fuel compound such as methane, methanol, or ethanol) can produce electricity. In most case, the electricity is generated using a rotating generator driven by a steam turbine or internal combustion engine. As one alternative, a fuel cell generating system may be used.
[0088] Additional embodiments will be apparent from the Detailed Description and from the claims. BRIEF DESCRIPTION OF THE DRAWINGS
[0089] Fig. 1 shows a schematic cross-section of a portion of an exemplary light rod for the present invention.
[0090] Fig. 2 shows a schematic top view of an exemplary flat light array.
[0091] Fig. 3 shows a schematic view of an integrated growth and recovery system utilizing rotating light arrays in growth chambers.
[0092] Fig.4 shows a schematic view of downwardly and upwardly projecting light arrays.
[0093] Fig. 5 shows a schematic side view of a growth tank and associated components.
[0094] Fig. 6 shows a schematic top view of a growth module fitted in a container with associated processing components.
[0095] Fig. 7 shows a simplified diagram of major components of a system suitable for use in a modular system for growth and processing of photosynthetic microorganisms.
[0096] Fig. 8 shows a schematic layout of an inline microwave lysing system.
[0097] Fig. 9 shows a schematic layout of a system for algae oil production involving microwave cell lysing and micron bubble cell disruption.
[0098] Fig. 10 shows a schematic diagram of the major components of an exemplary system for electricity production with carbon dioxide recycling.
[0099] Fig. 11 schematically illustrates a fixed light array.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS General Discussion
[00100] The use of cultivation systems for the growth of algae to be used as feed stock, e.g., for fuels, food, and plastics, as well as for other purposes, has come under intense scrutiny in the past few years. While many devices and schemes have been proposed for both outdoor (e.g., raceway) and indoor (photobioreactor) cultivation (see, e.g., Background), addressing proper lighting and nutrient dispersal had not been adequately resolved in order to attain high, consistent growth of the cultured organisms with sufficiently low costs, and systems remain unsuitable for consistent, large scale production.
[00101] One portion of the present invention directly addresses the issues of proper lighting and/or nutrient dispersal in a photobioreactor system, by utilizing a light array (or set of light arrays), often a rotating light array, which provides photosynthetically effective light to photosynthetic microorganisms passing through the light array. Accomplishing this includes appropriate spacing of light sources such that attenuation of light in the growth medium does not result in a significant proportion of organisms receiving less than effective illumination levels. The system can also be configured to disperse nutrients in the growth medium.
[00102] Even though exemplary uses of the present light arrays are in production of algal lipids, e.g., for production of biodiesel, and in overall biomass production, they can also be used in other applications, e.g., in waste treatment. For example, the light arrays can be incorporated in systems such as waste water treatment aeration tanks or outdoor raceway ponds. The advantage is delivery of a consistent light source at the right frequency to the whole of a bio-mass regardless of natural light vagaries.
[00103] Further, the present invention is directed to a system for enhancing the cultivation and harvesting of algae and other photosynthetic water living organisms through the use of enclosed photobioreactors configured in a modular and preferably portable manner. For example, such systems can be mounted within or on a container such as flat-bed or box car railcar or shipping container, which can preferably be conveyed to a desired site, e.g., to a CO2 producing site. As another alternative the system can be constructed on or within a support frame or in a custom container.
[00104] In particularly beneficial configurations, the system has the advantage of not requiring natural sunlight for its operation and is adaptable to any climate or other natural variable. The system can significantly reduce the footprint required for mass growth of photosynthesizing microorganisms such as algae through high output growth methods, which may include a method of increasing active growth volume within each individual growth tank. The high output growth tanks can be arranged in a compact matter, e.g., in series horizontally and/or stacked vertically, thus achieving high output in a small area. The system makes use of technology to reduce costs and provide economy of scale.
[00105] Particular advantageous embodiments of the present invention utilize structures to provide proper lighting and preferably also nutrient dispersal in a photobioreactor system, by utilizing a light array (or set of light arrays), often but not necessarily a rotating light array, with growth tanks. Such light arrays can also be configured to disperse nutrients in the growth medium.
[00106] Even though exemplary uses of the present modular systems (and/or light arrays) are in production of algal lipids, e.g., for production of biodiesel, and in overall biomass production, they can also be used in other applications, e.g., in waste treatment.
[00107] One of the important issues leading to the development of photobioreactors is the increasing cost and looming reduced availability of fossil fuels. Biofuels and their potential for energy independence or at least reduced reliance on imported oil has led countries, corporations and communities to seek out alternative methods of cultivating and harvesting fuels and fuel precursors, e.g., as oils, alcohol, and sugars from sources such as palm, corn, soybean, and sugar cane. The large scale development of mono-cultures of such has engendered its own problems, and there is growing consensus that this effort is possibly more destructive than the continued use of fossil fuels. [00108] Algae, however, has shown potential as a carbon neutral energy feedstock. The often referenced NREL Aquatic Species Study, for one, concluded that if all fundamentals were right, the lipid and energy yield from the cultivation and harvesting of algae could become a substantial energy resource. Algae also contain valuable properties for the food and pharmaceutical industry; and can be modified or engineered through genetics and/or growth conditions (e.g., particular nutrient profiles) to deliver high value end products
[00109] Achieving economical production in photobioreactors can advantageously take advantage of an understanding of the important parameters for photosynthesis in aqueous media. The process of photosynthesis involves the provision of energy from the photonic activity of light, e.g., sunlight and/or artificial light. That energy is required for a photosynthetic microorganism, e.g., unicellular organism, to fix a carbon atom in organic compounds and create the structures or organelles that will in turn engender culture growth.
[00110] Despite the requirement for energy from light for photosynthetic growth of microorganisms such as algae, direct sunlight and especially its UV component is too harsh for continued growth, so the primary culture layer directly exposed to sunlight dies in only a short time, and becomes a protective layer for the next layer. That second layer effectively becomes the growth layer or growth mass.
[00111] Furthermore, it has been found that the actual light used by photosynthetic microorganisms is only roughly 10% of the total sunlight spectrum. The actual frequencies of light that is required for optimum growth have also been determined and they fall within a very narrow wavelength band primarily within the visible wavelengths. These wavelengths vary according to the type of photosynthetic microorganism grown, e.g., red algae, green algae, blue green algae, bacteria, or diatoms. In actual practice, to this point algae are most often selected for commercial culture, and there are only a few genera of algae that are suitable for sustainable growth. These have been identified according to their lipid value or other desirable factors, though it is not the intent of this description to place limits on the type of microorganism (e.g., unicellular organism) as the system is adaptable to most species. [00112] Many past attempts at mass cultivation have taken place outdoors in large ponds or raceways. Unfortunately, the aforementioned cycle of cellular death from excess sunlight, along with uneven CO2 distribution and the need for close proximity to a CO2 source, the acreage and energy required to achieve any meaningful result, and continuing contamination issues has proved to be an insurmountable combination of problems for outdoor algae mass cultivation. Such problems have therefore led to the interest in closed or semi-closed photobioreactors (PBRs).
Light arrays and array configurations
[00113] The present systems can advantageously incorporate light arrays which are configured such that photosynthetically effective illumination is provided to substantially all of the photobioreactor culture medium volume within the volume described by the light array. One or more such light arrays may be used in each culture tank.
[00114] An example of such a light array has a rotating axle on which a plurality of light wands or light bars are attached, distributed along the axle. (The description herein emphasizes rotating light arrays, but also applies to other light array configurations except in particular instances where it is clearly only applicable to the rotating configurations.) In many cases, light wands are also distributed around the axle much like branches of a tree, e.g., forming a flat array of light wands. The light wands are distributed along the axle such that there are relatively narrow gaps between the paths described by successive light wands. For example, when the light wands are arranged in successive flat arrays, there is a plurality of such flat arrays distributed along the axle with relatively small gaps between successive flat arrays. The light wands can alternatively be distributed in various other ways, such as spiral or helix positioning, alternate offset positioning, and others. Highly advantageously, the spacing between successive light wand paths is selected such that photosynthetically effective light is provided across the entire space between the successive light wand paths, taking into consideration the intensity of the lights and the expected turbidity of the medium as the culture grows. In many cases, the spacing of the light wands will be in a range of about 2 to 10 cm, more commonly about 2 to 5 cm.
[00115] While rotating light arrays are advantageous, other configurations and other movement patterns can also be used which similarly provide the close spacing between successive light wands. In one illustrative configuration, a light array is arranged as a set of parallel light bars (preferably close-set light bars). The parallel light bars can be linked substantially in a plane, forming a planar array. Such a planar array can be moved generally linearly within a culture tank to provide light to photosynthesizing microorganisms. The linear movement would often be in a back-and-forth manner. That is, the movement would usually be in a direction substantially orthogonal to the plane of the array. Thus, in a rectangular tank, for example, a vertical or horizontal array of parallel lights may be moved along an axis of the tank in a back-and-forth pattern or in a cyclic pattern, e.g., in which the array moves linearly along the upper portion of the tank, then moves down and returns moving linearly along the lower portion of the tank. A plurality of such planar arrays can be utilized in a single tank, e.g., such that a particular planar array traverses only a portion of the tank, e.g., thereby increasing the illumination frequency.
[00116] Similarly, an array the same or similar to those described for the rotating light arrays can be used with linear movement. For example, a light array with a plurality of flat arrays of light wands attached to and extending from a central axle can be moved along the axis of the axle in a reciprocal manner. Once again, a plurality of such light arrays may be used in a particular culture tank.
[00117] Other useful light array configurations incorporate light wands or bars which extend downward and/or upward in the medium. For example, light wands may be mounted on a disk or other mounting body. Such a mounting body can, for example, be positioned above the fluid level in the bioreactor tank, such that the light wands extend down into the culture medium. Similarly, light wands may be mounted on a mounting body (or on the bottom of the tank) and extend upward in the culture medium. These configurations provide an advantage for rotating light arrays because they allow the radial distribution of light sources to be varied as desired in a simple manner. For example, light sources can be positioned such that the light exposure throughout the volume of medium described by the rotating light array is essentially equal. This can be accomplished by providing additional closely space light sources at positions further out from the rotational center. This can be distinguished from the light array design which has light wands extending outward from a central axle. In this arrangement, while the periodicity of light exposure is the same throughout the rotationally described volume, the exposure time for different points through that volume differ substantially due to the increasing linear speed of the light sources for points progressively further away from the axle.
As an alternative or in addition to the light array movement as just described, growth medium movement may be used to move the organisms suspended in the growth medium past the light sources in a light array.
[00118] Other such configurations of light emitting elements arranged and/or moved such that most or substantially all of the photosynthesizing microorganisms in a culture tank will be in close proximity to the emitted light may also be used.
[00119] For any of the light wand configurations, it is highly beneficial if substantially all of the culture medium that passes between successive light wands is exposed to light (desirably to photosynthetically effective light) from the light wands. Such exposure is generally a function of the light source parameters along with the light wand distribution and medium turbidity. The light wand parameters include the selection, placement, and orientation of the light sources on the light wands, be they LED, fluorescent, cold cathode fluorescent, or other. As indicated above, the light wands are located such that the separation between successive light wand rotational paths is such that a gap is defined by movement (e.g., rotation) of the array. This gap is preferably sized and configured such that, in combination with the light source parameters, substantially no area within that gap is dark. Thus, the light distributing axle has the advantage of placing light and/or nutrients closer to the biomass.
[00120] The sizing of the gap can also be selected to create a flow-through for the suspended bio-mass, effectively generating, through Bernoulli's principles, natural high and low pressure zones that enhance flow-through and/or promotes the creation of minor eddies which in turn promote cell growth.
[00121] The present light arrays are highly adaptable to a wide variety of different culture system requirements. For example, when used in a culture system, the light array may be fixed in place, such that it is not readily and rapidly repositionable or removable, but alternatively and advantageously the light array can be configured such that it can be readily removed, replaced, and/or repositioned within a culture tank. An advantage of such mobility is that the light source (i.e., the light array) can thus be moved in and out of the culture tanks rather than moving the mass of organism culture medium, and also can be conveniently adapted to various types of cultures and culture conditions. In addition, the light array can be positioned vertically or horizontally (or in any other desired orientation) in the culture tank.
[00122] Such arrays can be used in various applications, including in culture which maximizes biomass and/or numbers of organisms (which can be referred to as biomass growth), as well as in other applications such as waste treatment (which can be referred to as process growth). The light arrays can also be used in culture tanks for which the emphasis is on increasing the amount or fraction of a desired product or products, e.g., lipids (such culturing can be referred to as product growth).
[00123] In some cases, a system may include separate culture tanks or different process stages for increasing cell number and for increasing the level of a particular product. The culture conditions may differ for those different purposes, including provision of different levels and/or frequencies of light. Thus, for example, when used in a tank for biomass growth, the light array may, for example, deliver a higher density light delivery system as compared to a product growth tank. Thus, in a product growth tank, an array with fewer and/or less intense lights and/or lights of different frequencies can be placed in growth tanks. In some cases, such product grow tanks would have the light arrays placed essentially horizontally. For example, these product growth tanks can used to increase TAG, lipid or carbohydrate values in organisms and, in many cases, would require less light and/or the light can be programmed to enhance production of the desired products, e.g., in approximate diurnal cycles. In some configurations, the lights in growth tanks can be under the control of an electronic light controller(s) that increases or decreases illumination frequencies and/or changes the light wavelengths, e.g., to promote lipid production or production or other valuable product(s).
[00124] Even though the use of movement of light arrays will typically be more efficient, it is also possible to rely on fluid movement rather than (or in addition to) light array movement to bring cells and light source into close proximity. For example, one or more light arrays may be provided in a tank, and culture medium containing cells pumped gently through the tank or the culture medium may be gently mixed such that cells will cycle past the light sources. Similar to the situation with the rotating or otherwise moving light arrays, medium with cells will pass in close proximity to the light sources and therefore will receive photosynthetically effective illumination.
[00125] The effectiveness of the present light array design is supported by a study on correlations between certain illumination parameters and growth rates for particular algal species. Initially it was shown that there is poor correlation between the incident light intensities, the average light intensities and the light energy supplied per unit photobioreactor volume (E/V) and linear growth rates of Chlorella pyrenoidosa in cuboidal photobioreactors of various sizes. It was also found that at a given E/V, the linear growth rates decreased with increase in the photobioreactor depth, indicating that the light distribution inside the photobioreactor must be considered for the rational design and scale-up of photobioreactors. Therefore, a light distribution coefficient {Kiv), defined as the cell concentration at which 50% of the photobioreactor volume receives enough light for photosynthetic growth, was proposed. It was shown that linear growth rates increased with increase in Kiv but the data were scattered, and that at a constant Kiv, a linear relationship was observed between the linear growth rate and the E/V. Similarly, when the E/V was held constant, there was a good correlation between the Kiv and the linear growth rate. A light supply coefficient, defined as
E/V. Kiv was then proposed as an index of the light supply efficiency of photobioreactors. Good correlation was found between the light supply coefficient and the linear growth rates of both C. pyrenoidosa and Spirulina plantensis in cuboidal photobioreactors of various sizes as well as in various types of both internally illuminated and externally illuminated cylindrical photobioreactors. (Ogbonna et al., 1995, Light supply coefficient: A new engineering parameter for photobioreactor design, J Ferm and Bioeng 80:369-376.)
[00126] The present light arrays allow the light supply coefficient to be at highly beneficial levels, e.g., due to the ability to provide photosynthetically effective illumination throughout the volume of culture medium encompassed by the light array.
[00127] Another way of considering the present invention is in the context of algal growth in top illuminated ponds. In general, for incident light that is initially of an appropriate intensity for growth, the intensity will attenuate rapidly as it passes through a cell suspension. The result is that growth effective light is only available in a thin layer. For example, in a pond with natural light, almost all of the growth occurs in the top approximately Y2 inch, which can be referred to as a growth plane. The present light arrays essentially reproduce such growth planes within a tank, thereby eliminating the limitation of growth occurring only at the top surface and/or wall surface of the growth tank. This is accomplished by spacing light sources such that a plurality of growth planes is created. For example, with a rotating light array, two adjacent light rotation planes can be arranged spaced approximately two growth planes apart. That is, the spacing between the rotation planes is such that the lights traveling in one of the rotation planes provide effective illumination to a distance approximately equal to one growth plane, and the lights traveling in the adjacent rotation plane provide effective illumination to a distance approximately equal to one growth plane. In this way, effective illumination is provided across the entire distance between light rotation planes.
[00128] The distance equal to one growth plane will depend on at least the cell density, the light requirements for the organism being cultured, and the initial light intensity from the light wand. In many cases, a growth plane will be in the range of about 0.5 to 2.5 cm. Nutrient dispersal
[00129] In addition to providing illumination, the light arrays can provide nutrient dispersal, e.g., CO2 and/or nitrogen. For example, the rotating axle can include a dispersal mechanism or tube to distribute nutrients such as CO2 and nitrates.
[00130] Such dispersal mechanism can, for example, involve passage of such nutrients through or along a rotating array axle. The nutrients can be passed into the surrounding medium, e.g., through openings in the passageway and/or can be directed (e.g., using tubing) along at least some of the light wands and passed into the medium along or proximal to the wands. Of course, nutrients may also be injected or otherwise passed into the medium with other mechanisms and at different locations.
Illumination and nutrient control
[00131] In a functional system, it is advantageous to control, actively and/or as part of the basic design of the system, illumination and/or provision of nutrients. Such control can be applied to a number of different parameters.
[00132] For example, the process optimization of the light system can be further enhanced by the timing of lights in an artificial setting. In natural settings, it has been observed that diurnal cycles are critical to growth of many photosynthetic algae, and relates to CO2 utilization and carbon fixation by the algae. As part of the cycles, CO2 is trapped during the night for release and utilization during the day. At dawn, when light becomes available, the rate of consumption of carbon dioxide through photosynthesis exceeds that of CO2 production through respiration and, as a result, the store of carbon dioxide is depleted and algal growth becomes limited. In other words, the carbon dioxide accumulated during the night hours is stored for use in the daytime hours. Carbon dioxide concentrations as high as 25 mg/L have been observed at night in lagoons. (Williford, H. K. and Middlebrooks, E. J. (1967). "Performance of field-scale facultative wastewater treatment lagoons." J. WPCF, 39, 2008-2019.) [00133] In effect the natural diurnal cycle is a natural metering cycle for daytime CO2 uptake and fixation. However, in a photobioreactor, by maintaining lights at the correct frequency and increasing photonic activity in close proximity to the bio- mass, we have found that CO2 fixation or uptake can be substantially extended, even as much as extending it such that CO2 fixation occurs on a twenty four hour basis, eliminating the diurnal cycle. In such tests, we have found that this storage/ release cycle can be artificially extended to a 24 hour rotation as now control of CO2 release is timed by lighting which is synchronized to the uptake of carbon by the algae rather than to a diurnal cycle approximation.
[00134] In photosynthesis, the cycle of storage and release can be directly measured in ORP and pH. We find that when the bio-mass is absorbing CO2, it releases energy in the form of a negative hydroxyl (OH"). This brings the pH up and its counter indicator, the oxidation reduction potential (ORP) (units in mV), down. By carefully monitoring the pH and/or ORP levels, we can determine when the biomass is able to uptake CO2.
[00135] The use of light sources arranged such that the algae being cultured is in close proximity to the light sources, e.g., often within about a quarter inch to one inch, can be beneficially combined with selection and/or active control of the specific bandwidths of radiance (i.e., the light wavelengths) which are provided for the illumination. In general plant physiology, the term Photosynthetically Active Radiation (PAR) refers to the radiation in the range of wavelengths between about 400 nm and 720 nm. This is the energy that is absorbed by the assimilation pigments in blue-green algae, green algae and higher order plants. The wavelengths for the lower limit (400 nm) and upper limit (720 nm) are not entirely rigid. Photosynthetic reactions have, for example, been established in some algae at wavelengths shorter than 400 nm. In general, the lower limit depends on the structure and the thickness of the leaf as well as on the chlorophyll content. Some research projects have shown 700 nm as the upper wavelength limit.
[00136] For plant physiology, this range can be divided into three narrower bands: - 400 nm to 510 nm: strong light absorption by chlorophyll, high morphogenetic effect
- 510 nm to 610 nm: weak light absorption by chlorophyll, no morphogenetic effect
- 610 nm to 720 nm: strong light absorption by chlorophyll, high morphogenetic and ontogenetic effect. (Tutorials section of Gigahertz Optics web site).
[00137] The limited bandwidths effective for photosynthesis can be used to increase the energy efficiency of a photobioreactor by reducing or excluding ineffective wavelengths and/or damaging (UV) wavelengths.
[00138] The light wavelengths absorbed by the light assimilation pigments of photosynthetic bacteria can vary from that indicated above for plants, in some cases including wavelengths longer and/or shorter than the plant PAR.
[00139] Still further, timing the exposure to light, e.g., to coincide with the CO2 fixation pattern of the cells, can further improve energy efficiency and/or enhance photosynthetic growth. Thus, for example, it appears that the algal cells do not require continuous light, but rather can be illuminated intermittently to imitate photosynthesis reactions, with the series of reactions running to completion during a relatively dark interval. It appears that an approximately 6 second cycle is effective, although other cycles or intervals may also be used. That is, within each 6 second cycle (or other interval), light is provided to a particular volume of culture medium for a short interval, e.g., about 0.1 to 1.0 second, followed by little or no light. This can be accomplished, for example, using the rotating light wands such that a light wand is in position to illuminate a particular spatial position on such cycle. For example, a flat array of 5 light wands rotating at 2 rpm will provide such 6 second cycle.
[00140] Using such arrays with outwardly projecting light wands results in equal periodicity throughout the included volume of medium. However, due to the increasing linear speed of the light wand the further away from the axle or other rotation center one considers, the illumination interval for particular points in the medium decreases in the same direction. This can be adjusted, for example, using a rotating light array in which light wands pointing upward and /or downward are arranged in generally sector patterns which extend outward from the rotation center. The sector pattern may be straight (e.g., defined as the sector between two radial lines) or curved. One or more sectors may have light wands. The result is that as the array rotates a particular point in the medium will be exposed to photosynthetically effective illumination for the entire interval from when the leading edge of the sector approaches within a distance of one growth plane until the trailing edge of the sector moves away a distance of one growth plane. Thus, with appropriate angular width of sectors, the illumination intervals for points throughout the volume of medium swept by the rotating light array may be equalized or at least made closer to equal.
[00141] Instead of or in addition to illumination timing based on rotation rates of light arrays, control of light exposure can be accomplished by directly controlling light emission, either separately or in combination with light array rotation (or other type of light array movement). Such control can, for example, include periodicity, illumination interval, and for suitable light sources, intensity. Such parameters can be programmed in an extremely large number of different ways. Programming may be accomplished in software and/or in hardware.
[00142] An example of such programmable illumination uses an array(s) with light wands pointing upwards or downwards or both and distributed across the area of a tank or other substantial area. The individual light sources can then be controlled in any desired pattern. For example, lights may be illuminated for equal time intervals in a repetitive pattern traveling across the array. As an alternative, lights may be illuminated in a rotating pattern or in an annular pattern (i.e., with an annulus of illuminated lights which repetitively expands and/or contracts).
[00143] Thus, as described above, the present light arrays are effective for providing effective, or even optimized, light intensities to a large fraction or even substantially all of the culture medium encompassed by the light array over a broad range of cell concentrations. This is accomplished by placing light sources with appropriately selected and/or controlled light intensities such that the light needs to traverse only short paths (e.g., about 0.5 to 2.5 cm) in order to contact substantially all of the cells in the light array volume. CO2 uptake directly diminishes as a function of the distance of algae to light (assuming the maximum light intensity is not so great as to damage the algae). Therefore, by placing light sources (e.g., light wands) in the tank at narrow intervals, the algae passing between adjacent light sources can be exposed to photosynthetically effective light intensities. That is, the reduction in light intensity across the medium in the gap between adjacent light sources is kept relatively small, and therefore the reduction in CO2 uptake by algae across that gap is also kept relatively small. Therefore, with appropriately selected path lengths, a large fraction of the cells will be within a distance from at least one light source such that the cells will receive photosynthetically effective light intensity. Such configuration of light sources such that essentially all of the algae will be exposed to light that is of appropriate intensity for photosynthesis can significantly increase the total photosynthetic activity of the culture. Provision of light of proper wavelengths and/or provision of light on a beneficial illumination schedule can then enhance energy usage and/or growth.
[00144] In accordance with the description above, the present systems (e.g., modular systems) can include one or more controllers which regulate one or more culture and/or processing parameters. Such parameters may, for example, include pH, temperature, illumination intensity, illumination wavelengths, illumination timing pattern and/or illumination cycle frequency, and the like.
Tanks
[00145] As indicated above, the present light arrays can be advantageously used in any of a broad range of tank shapes and sizes. For any tank size and shape, it is beneficial for as much as possible, (preferably essentially all) of the culture medium in the tank to be exposed to light at close proximity to light sources of a light array. For example, for a cylindrical tank, a light array can be located and sized such that much of the volume in the tank will be within the volume described by rotation of the light array. Alternatively, the combination of rotation of the light array and flow of the bulk fluid results in substantially all of the tank fluid being exposed to effective illumination. Likewise, modular systems as described herein may incorporate any of a broad range of sizes and/or shapes of such tanks. [00146] For larger tanks, especially tanks that are not cylindrical (e.g., rectangular tanks), it can be beneficial to utilize multiple light arrays, which may be the same or different. Use of multiple light arrays is beneficial, for example, to provide more consistent light exposure to the microorganisms being grown, to avoid dead spots in the tank, to prevent the difference between light exposure at the tips of light wands and the light exposure near the axle from being too great, and/or to prevent shear generated near the tips of light wands from being excessive due to speeds that are too high. For example, in a square tank, 5 light arrays may be used, a larger one centrally located and a small one in each of the four corners. In another example, in a rectangular tank that is elongated horizontally, a series of light arrays of equal size may be distributed along the length of the tank. Many other arrangements can also be selected based, e.g., on the particular tank size and shape and/or culture requirements of the organism to be grown.
[00147] Tanks can also be constructed of a variety of materials. For example, tanks may be constructed of plastics such as polycarbonate, or glass, or of metal such as stainless steel. The material and thickness can be selected based on normal considerations such as tank size, cleaning requirements, and effects on organisms to be grown, among others.
[00148] Tanks may also be made to enhance light usage by means of a reflector (e.g., a reflective layer or separate reflector) oriented to reflect light that would escape through the tank walls (and/or bottom and/or top) back into the culture medium. It is preferable that light emission and such recovery reflection are properly balanced to avoid photobleaching or other deleterious effects on organism growth and/or on production of desired product. Alternatively or in addition to light recovery, light can be transmitted into the culture medium from light emitters at the tank wall(s) or by transmission through tank walls.
Exemplary Light Arrays, Illumination, and Organism Growth
[00149] A number of different exemplary features and options of the present invention are described below. [00150] The use of light arrays as described for the present invention provides significant advantages due to the ability to control the illumination provided to the cultured microorganisms appropriately. As indicated above, these light arrays can be configured in a number of different ways. Advantageous light array configurations include rotating light arrays. Such configurations can enhance biomass growth by the close contact between the growing photosynthesizing organisms and light. At the same time, the invention can provide great scalability, something not reasonably achievable by many of the prior designs. Further, the light arrays, e.g., rotating light arrays, can be used in pre-existing tanks and/or sized according to desired spatial distributions and/or movement speeds and/or production rates. A further advantage is that the present systems can be constructed at relatively low cost.
[00151] For example, a rotating light array can be, but is not necessarily, symmetrical about a central axis. A simplified illustration of such a light array is shown in Fig. 1 and Fig. 2. As shown in the cross-sectional side view diagram of Fig. 1 , the light wands 10 of the light array 12 are mounted on a central shaft or axle 14 providing a central axis. The illustrated axle can have a passageway or duct 16 (which commonly is centrally located) which can be used, for example, to feed nutrients into the culture medium. The motor 18 drives the axle 14, e.g., through a slip ring configuration 20 so as to prevent tangling of wires, although direct drive can also be used. The motor is set to rotate at a desired speed or to follow a programmed speed profile over time, e.g., through pre-programming or variable speed drive. The light wands 10 can be placed at intervals along the axle so as to promote fluid flow and maximum effective illumination along the narrow gaps between the light wands.
[00152] The top view of the light array provided in Fig. 2 shows a view of the rotating axle within a tank 30. In this view, a single flat array of light wands 10 is visible. The shape of the tank can be of any type, e.g., circular, square, etc.
[00153] A light array similar to that shown in Fig. 1 and Fig. 2 was tested for growth of Nannochloropsis in a cylindrical growth tank to compare energy usage between the light array system using cold cathode fluorescent lights and a simple externally illuminated mechanically mixed tank using a grow light. The light array included flat arrays of five lights at 1.5 inch intervals along the central axle, and was rotated at one rpm. The test showed that the light array system was substantially more efficient in producing biomass, requiring much less energy per unit biomass increase.
[00154] Alternative light array configurations as indicated previously are illustrated schematically in Fig. 4. The illustrated light arrays include an array 60 with a plurality of downwardly projecting light wands 62 and an array 80 with a plurality of upwardly projecting light wands 82. Photobioreactors may include either an upwardly projecting or a downwardly projecting light array or both. The downwardly projecting light array 60 includes the light wands 62 mounted at one end to an array mounting body 64, in this case a mounting disc with its flat plane essentially perpendicular to the long axis of the light wands. In many cases it is desirable for the array to be rotated. This can be accomplished, for example, using a rim drive (e.g., a pinion motor 66 as illustrated) or a center drive (e.g., a coaxial motor 68 as illustrated). Such a center drive will commonly drive through a central shaft 70. Electrical contacts for powering the lights can be provided conventionally, e.g., using slip contacts for rotating light arrays. If the array will not be rotated, usually the growth medium will be circulated past the light array. Arrays of this type can be mounted with the array mounting body within the growth medium, at the surface of the medium, or above the surface of the medium.
[00155] The array 80 with upwardly projecting light wands 82 has the light wands mounted in an array mounting body 84 (similar to the array just described above). In this case, the array mounting body may be a surface of the tank or may be a separate body such as the disc illustrated. In most cases, the light wands will be mounted substantially perpendicularly to the plane of the array mounting body. The array may be fixed or may be rotated. When configured for rotation, the rotation may be driven in various ways, but most often a central shaft drive will be utilized. Such a central shaft may for example, be a shaft extending from above (e.g., as an extended shaft 70), or may be from below, e.g., at axis 86. Where the drive shaft is from below, often the shaft will extend through the tank wall (e.g., the bottom wall) and will be suitable sealed at that penetration point. [00156] As indicated above, the upwardly projecting and downwardly projecting arrays may be utilized separately or together. When used separately, in advantageous configurations the light wands extend substantially the entire depth of the medium in the reactor tank. When used together, the light arrays may be placed such that the light wands from the respective arrays do not intermesh, or may be placed such that the light wands do intermesh. That is, the downwardly projecting light wands may terminate above the upwardly projecting light wands, or may be placed such that the distal ends of the downwardly projecting light wands are closer to the mounting points of the upwardly projecting light wands than the distal tips of those wands, creating an overlap of the wands. In some cases, the downwardly projecting light wands will overlap at least 50, 70, 80, or 90 percent of the length of the upwardly projecting light wands.
[00157] Fig. 11 schematically shows an illustrative light array suitable for a fixed array in a growth tank. The array 200 includes a plurality of light wands 202 (in this case each light wand includes a linear array of LEDs). The light wands 202 project down into the culture medium in the photobioreactor tank 204. In this case, the photobioreactor includes an axial mixer 206. A large variety of mixer designs may be used.
[00158] Of course, while the arrays as just described will usually be operated in configurations where the light wands are oriented substantially vertically, either or both of the arrays are just described may also be utilized in other orientations. In such cases, references to upward and downward may be changed to appropriately reflect the changed orientation.
Systems and System Process Control
[00159] Process systems utilizing the present invention can be configured in a variety of ways. An exemplary process system utilizing a light array, e.g., as illustrated in Fig. 1 and Fig. 2, is shown in Fig. 3. The diagram shows an illustrative configuration of a system utilizing light arrays. This system includes a complete power generation scheme which includes algae as a CO2 capture system. The products of the system are fuels and electricity through co-generation of methane gas. [00160] Efficiency is accomplished by using essentially all the elements of the biomass. It is understood that by configuring the type of algae stock (with the potential use of bacteria), one can achieve substantial amounts of fuels (e.g., biodiesel) and/or methane and/or overall biomass. Such method can be used without further modification, or can be use for production of methanol and/or other compounds in processes for which methane or methanol is a feed stock.
[00161] In this system the light arrays 12 are positioned directly in a tank 40, such as a sewage or sluice or aeration pond. The algae stock's growth is optimized to capture as much CO2 as is possible. The biomass is then disgorged into what could be referred to as a product growth tank 44, where maximum lipid value is created in time, also utilizing light arrays 12.
[00162] The biomass is then fed through a gravity clarifier 46 or separator where constituent parts, such as sugars, oil and/or other valuable products are captured. Depending on the particular components to be captured, lysis and/or particular types of extraction and/or purification may be included. In the illustrated system, lipids are separated for use in biodiesel production 48.
[00163] The biomass from which desired components have been separated is then fed to a thickener or dewatering system (removing much of the residual water) and then to an anaerobic digester 50, where the biomass is then processed for methane gas. The gas is then stripped of its constituent CO2, gas through a gas separator 52, e.g., a conventional bubbler. The CO2 is re-introduced to the biomass growth tank 40 and/or the product growth tank 44. The methane is burned (optionally along oxygen captured from the growth tanks) for clean energy generation in a conventional methane burning generator 54.
[00164] The described process flow is only one of many potential uses of the present invention. The present light arrays bring to the culturing of algae and other photosynthesizing microorganisms the advantage of a rapid, controllable growth method. Further, the design can be configured in modular fashion, providing easy scale-up of capacity. Still further, the light arrays can be retrofit to existing systems and/or systems incorporating the light arrays can be made portable. [00165] Thus, the light arrays and systems utilizing such arrays are applicable to any of a number of different processes, for example, for the creation of lipids for bio-fuels, remediation systems for flue stack cleaning or CO2 fixation, waste treatment, and the like. Advantageously, these light array armatures can be adapted to creation of biomass inexpensively and with low capital costs.
Exemplary Modular Systems and Process Controls
[00166] As indicated above, some aspects of the present invention concern modular and preferably portable photobioreactor systems. These systems provide a modular, portable large scale algal (or other photosynthetic microorganism) mass growth system that that can be housed in a container(s) such as a railway car, truck container, flat bed or other transportable structure.
[00167] The system is preferably fully enclosed with computerized controls, and optimized grow tanks and can be connected to a CO2 source. Each growth tank contains the full mechanical means of cultivating algae or other photosynthetic microorganisms but can be connected, e.g., in parallel or in series, to another or other units.
[00168] The lighting for photosynthesis can advantageously be independent of sunlight and can use the latest technology in low energy lights, which can be strategically placed within the grow tanks as a light array. These lights can be powered by electricity produced by solar, wind or other clean renewable technologies, and/or by electricity generated by current conventional power plants.
[00169] The output from the growth tanks can be disgorged (e.g., daily) for further processing. In most cases, the suspension from the growth tanks will be dewatered, e.g., using a conventional dewatering system. That water can be recycled in the system, often after at least partial purification. The dewatered biomass can be used as a source of fuel, e.g., through optional lipid extraction technologies and/or digested in a methane digester. The fuel output can then be used as an energy source. Of course, it would be possible to burn dried biomass directly as a source of energy, but the need for substantial initial drying, the difficulty in achieving efficient clean burning, and the lack of flexibility of use result in this usually being not preferred.
[00170] An exemplary growth tank is shown in Fig. 5, and an exemplary arrangement for a present modular system is shown schematically in Fig. 6. The principal components of this exemplary container system (in this case a standard 40 by 8 foot by 8 foot container ubiquitous throughout the freight industry) are sectional tanks that are spaced, usually evenly spaced, within the container. In this example, the modules contain four growth tanks with their lighting systems, where the tanks are all made of equal dimensions; roughly 8 feet by 8 feet by 7 feet high. Of course, other configurations; such as configurations having different numbers of tanks, e.g., 1 , 2, 3, 5, 6, 7, 8, or even more tanks, and/or configurations using tanks of different shapes and/or sizes can also be utilized. Likewise, modular systems may be constructed in which the tank(s) are not mounted within containers. For example, a modular system may be constructed using a large tank or tanks, e.g., 8-12 or 10-16 feet lateral dimension (e.g., diameter for a circular tank or shortest side length for a rectangular tank).
[00171] Nonetheless, especially in cases where a container is used, it can be advantageous to utilize tanks sized to allow maintenance access to the entire set of tanks. For example, in a container a clear area of about 16-24 inches along one side can be used for access. In other cases, access may be provided in other ways, e.g., the container can be equipped with access ports or openable access panels to provide service access.
[00172] These modules include interconnections to provide electrical power, fluid handling, and process control. Thus, for example, tubing, valves (e.g., solenoid valves), and connections are provided to allow controlled filling and emptying of tanks and nutrient injection. The tanks also have sensors which allow monitoring of the culture. These sensors can, for example, measure CO2 uptake, total dissolved solids, pH, ORP and other measurements designed to monitor growth and potential problems. The sensors generate signals which are read by a process controller, usually a computer-based controller. Each module may have its own controller or a controller may monitor and control more than one growth module. Monitoring and control functions may also be split, e.g., between controllers in separate modules and a central controller (e.g., located in a processing system which may be in a processing module). Optionally, at least some of the monitoring and control may be performed by a remote controller, e.g., over the internet or other network. In some systems, the system includes a local controller(s) and can also be remotely monitored and controlled, e.g., via internet. For example, the culture status may be monitored and/or controller settings may be checked or changed and/or intervention in the process may be performed remotely.
[00173] As desired, the connections and controls within and between growth modules may be configured in many different ways. In many cases, each of the growth tanks within a module is independent of other tanks in the module. Alternatively, certain tanks may be used as biomass growth tanks, and one or more others may be used as product growth tanks in which the amount and/or proportion of particular desired components (e.g., lipids) is increased or qualitatively changed. Similarly, different growth modules may be used independently to growth the microorganisms which are subsequently processed. In one alternative, some of the growth modules are used for initial biomass growth, and one or more of the modules are used for product growth. Thus, though the modules are interconnected, discrete flow controls are provided (e.g., solenoid valves) that can shut off or increase/decrease flows (e.g., of water, CO2 and/or other nutrients) for each growth tank (or set of linked growth tanks) depending on the intended process. In many cases, the flow controls are configured such that the separate tanks are independent. Most often, such independent tanks will disgorge their cultures to a processing system.
[00174] The system can also contain components for pre-processing of the algae rich medium. For example, static mixers can be placed at the end phase of the daily grow yield to begin the process of biomass degradation (e.g., cell disruption) for use as fuel stock or organic biomass.
[00175] In our research, we have found that daily disgorgement of the biomass for use is preferable, as we then avoid or at least reduce contamination issues and foreign species invasions that have plagued other growth schemes. In the absence of significant contamination, a small percentage of the microorganisms from the growth medium can be retained to incubate the new lot, which then incubates the next day's growth; additional algae stock can be added at any time to supplement the culture, e.g., as a spike to the initial inoculum. This continuous batch method of cultivation can also resolve or substantially reduce the issue of sterilization, provided the system is kept relatively closed. The system can encompass a sterilization cycle, e.g., on an as needed basis. Such sterilization may, for example, include UV and/or ozone sterilization, and/or alcohol denaturing.
[00176] As indicated, an example of a growth tank is shown in Fig. 5. As shown, the growth tank (80) is generally cylindrical, and includes a sensor set in sensor enclosure (82). The tank is associated with a master control box (84), which includes sensing and control components (e.g., for fluid control, nutrient injection, pH, CO2 monitoring, and electrical connections. Thus, for controlling fluid flows into and out of the tank, a fluid processing system (86) is provided. A nutrient/CO2 injection system (87) is also connected (connections not shown) to the tank to deliver CO2 or other nutrients into the tank. The nutrient injection connections may be in any of many different location(s). Electrical connections (88) are also provided, e.g., for powering a light array(s), as well as for connections to solenoid valves, sensors, and the like. Specific electrical connections are not shown because the particular connections will depend on design choices for sensors, control elements, and the like.
[00177] Such tanks can be made using a number of different materials, although preferred materials are vacuum formed composite materials which satisfy rigidity, temperature control and manufacturing considerations such as costs and relative simplicity. The tank can include a light array or arrays (not shown) that may be mounted in various ways, e.g., mounted above the tank or in a top surface or cover for the tank. The tank can also include a rigid frame that would support the vertical addition of other tanks in addition to a horizontal extension through the modular extensions. [00178] An example of a process flow design of a modular algae growth system is shown in Fig. 6 as a simplified sample representation of the complete system configured in container (90), with four grow tanks (92). The use of a 40-foot container is one embodiment of a portable growth module. The modules can alternatively be fitted in a 20-foot container, in or on a rail car, or in or on any other conveyance. The module can also be free standing, e.g., in a shed or warehouse. In general, a module is constructed in a support frame, which may be closed as in the case of freight containers, or may be partially or fully open. In advantageous configurations, the modules can be stacked one on top of another for maximum utilization of space. For example, depending on the design and location, modules may be stacked 2, 3, or 4 modules high, or even more.
[00179] The system includes low power lighting system array (94) such as cold cathode fluorescent lights (CCFL)1 external electrode fluorescent lights (EEFL), and/or light emitting diodes (LED), preferably a frequency designed demand lighting system, as a light array. The purpose of the light array is to enhance (preferably maximize) light distribution throughout the vessel. The lights can, for example, be mounted on rotating devices to create a rotating light array to saturate the grow tanks (92); and/or lights can be static. The selection of light array can, for example, depend on the tank or system design and/or the type of microorganism (e.g., algae) being cultivated.
[00180] The grow tanks (92) can be made of any of a variety of materials or combination of materials that provide necessary strength and compatibility with culturing the selected organisms. For example, plastic, fiberglass, stainless steel, or other waterproof material can be used. Sensors (e.g., mounted in sensor enclosure (96)) monitor the conditions in the tank. Sensor signals are relayed to the controller computer (98) via a monitoring system (99). The computer dictates the introduction of nutrients such as CO2 (100) or nitrates (101). The CO2 and nitrates can be delivered via pump (102) after being micron mixed in a static mixer (104). The plumbing of the grow tanks is such that solenoids (106) can turn on and off flows to the tanks with flow meters (107). [00181] The controller software controls when to release the contents of the tanks when certain conditions have been met; such as turbidity, ORP1 pH and other grow factors. After growth, the algae mass as suspension (108) is fed into single step extraction unit (110), and then to a gravity clarifier (112) (or oil and water separator and/or flocculation units). The lipid mass is extracted and sent to tanks (114); and the biomass fed to digesters (116). The water, including micron sized algae is sent back through a recycling system (118) where it is reused as needed.
[00182] The system can also include other components, such as components providing UV light disinfection, ozone injection, or alcohol sterilization.
[00183] The system can be customized along many variables; such as light intensity, algae genus and other factors to affect final product. The system can beneficially be powered by reusable energy technologies, such as solar, wind or other. Battery backup power or a backup generator can also be included.
[00184] For portable systems, the system can be trucked, railed or otherwise transported to a CO2 source such as a coal fired power plant or such CO2 generating source, or to a pharmaceutical or food manufacturer location where, for example, bottled CO2 could be used.
[00185] Of course, modular process systems utilizing the present invention can be configured in a variety of ways. An exemplary process system adaptable to the present modular configuration and showing additional components as compared to the system shown in Fig. 6, but still simplified, is shown in Fig. 7.
[00186] In this system, water, which may be purified with reverse osmosis unit (120) and which can include fresh and recycled water, is held in water tank (121) until needed. It can then be pumped using pump (122) either directly to growth tank (124) or through nutrient/CO2 mixing tank (126) and static mixer (128). When needed, CO2 is provided from CO2 input (129). Growth tank (124) includes a light array (and/or fluid mixer) (not shown) driven by motor (130). Following growth of the culture, culture medium with biomass is pumped using recirculating pump (132) into Single Step Extraction (SSE) tank (134) in which at least partial cell disruption occurs. From the SSE tank, the biomass medium passes into gravity clarifier (136) which separates lipids and biomass from the water. The lipids are collected in straight vegetable oil (SVO) collection tank (138) and can be further processed, e.g., for biodiesel. The water is recycled back to cleaning and sterilization system (144). The bio-mass from the clarifier/separator (136) is delivered to thickening system (140). The thickened biomass is sent to one or more anaerobic digesters (142). Preferably, methane and CO2 from the digester are collected and separated. The methane may advantageously be used as fuel for an electrical generator, and/or the CO2 may be used as nutrient CO2 in the system. The process is preferably carried out under the control of a Process Automation Control Computer (141), e.g., using sensors, monitors, and other system inputs. Because of the many varied possible sensor and control connections, connections between the control computer and system components are not shown. The described process flow is only one of many potential uses of the present invention. Thus, the modular systems are applicable to any of a number of different processes, for example, for the creation of lipids for bio-fuels, remediation systems for flue stack cleaning or CO2 fixation, waste treatment, and the like.
[00187] The described process flow is only one of many potential uses of the present invention. Thus, the modular systems are applicable to any of a number of different processes, for example, for the creation of lipids for bio-fuels, remediation systems for flue stack cleaning or CO2 fixation, waste treatment, and the like.
LYSING AND EXTRACTION
[00188] For extracting valuable components from microorganisms, particular algae, the processes generally involve disruption of the cell membrane (and cell wall if present) of the particular microorganism. Such disruption may be by mechanical, chemical, or thermal means, or by a combination of those approaches. This can be combined with separation or extraction of the desired cell components. Of course, the separation or extraction methods can vary greatly depending on the type of organism involved, the component(s) desired for separation or extraction, the desired level of purity. The present invention concerns both the cellular disruption or lysis, and the separation.
[00189] All living cells, prokaryotic and eukaryotic, have a plasma membrane that encloses their contents and serves as a semi-porous barrier to the outside environment. The membrane acts as a boundary, holding the cell constituents together and keeping foreign substances from entering.
[00190] The plasma membrane is composed of a double layer (bilayer) of lipids, oily substances found in all cells. Most of the lipids in the bilayer can be more precisely described as phospholipids, that is, lipids that feature a phosphate group at one end of each molecule. Phospholipids are characteristically hydrophilic ("water-loving") at their phosphate ends and hydrophobic ("water-fearing") along their lipid tail regions. In each layer of a plasma membrane, the hydrophobic lipid tails are oriented inwards and the hydrophilic phosphate groups are aligned so they face outwards, either toward the aqueous cytosol of the cell or the outside environment. Phospholipids tend to spontaneously aggregate by this mechanism whenever they are exposed to water.
[00191] Within the phospholipid bilayer of the plasma membrane, many diverse proteins are embedded, while other proteins simply adhere to the surfaces of the bilayer. Some of these proteins, primarily those that are at least partially exposed on the external side of the membrane, have carbohydrates attached to their outer surfaces and are, therefore, referred to as glycoproteins. The positioning of proteins along the plasma membrane is related in part to the organization of the filaments that comprise the cytoskeleton, which help anchor them in place. The arrangement of proteins also involves the hydrophobic and hydrophilic regions found on the surfaces of the proteins: hydrophobic regions associate with the hydrophobic interior of the plasma membrane and hydrophilic regions extend past the surface of the membrane into either the inside of the cell or the outer environment
[00192] Most single-celled algae, such as the Volvocales, also possess true cell walls. The most-studied species is Chlamydomonas reinhardii. Its cell wall lacks long, fibrillary carbohydrates. Most of it is made up by glycoprotein, and even here an extensin-like protein rich in hydroxyproline is found. Among the identified sugar residues are arabinosyl-, galactosyl- and mannosyl residues. In the electron microscope it seems as if the wall consists of seven layers. The middle layer contains an extensive grid-shaped framework of polygonal plates consisting mainly of glycoproteins, while the layers above and below display fiber-like structures. The thickness of the outer layer varies since it includes components that the cell takes up from its surrounding.
[00193] Microwave radiation describes a range of electromagnetic radiation commonly considered to cover a range of wavelengths from 1 mm to 1m (300 MHz to 300 GHz). Microwaves are a pervasive component of our environment. However, such presence of microwaves, for the most part, has little or no significant effect on tissue, or cell structure. However, if the microwave frequency and amplitude is properly adjusted, then the energy coupling between the microwaves and particular compounds in the cell can occur and contribute significant heating. In most case, the energy coupling occurs due to the reorientation of molecules with significant dielectric moment to the alternating electromagnetic field of the microwaves. That reorientation manifests as physical motion leading to heating of the system as that motion is transferred to surrounding molecules as random kinetic energy. Commonly, the microwave radiation is selected such that the molecules most affected are water molecules.
[00194] The coupling of microwave energy to water molecules is the underlying principle behind the conventional microwave oven, which uses microwaves with a peak frequency of about 2.45 GHz (i.e., a wavelength of about 12.2 cm).
[00195] The water heating effect has been exploited to lyse cells, by using microwaving to heat water surrounding and within the cell, such that the heating alters the cellular structure of the cell sufficiently to cause lysis. For plant cells, microwave cell lysis appears to occur through bursting the xylem water transport system. However, this mechanism is not available to cell lysing of microorganism cells which do not have a xylem system within their structure. While microwave heating of water molecules can be used in the present systems and methods, because of the relatively large about of water present in cultures of microorganisms, the energy cost to lyse mass quantities of cells has made this approach expensive for producing large amounts of lipids or other mass applications.
[00196] However, energy can be effectively transferred to other molecules using other frequencies. Thus, in applying microwave lysing to various microorganisms, it is useful to recognize that all cells have differing parameters as to lipid, carbohydrate and protein. Because of these differing parameters, different organisms will respond differently to exposure to microwaves, e.g., to different frequencies and amplitudes. Indeed, at particular frequencies (resonance frequencies) the energy coupling is particularly efficient. Molecules commonly have multiple resonance frequencies, depending on a number of parameters, e.g., molecular size, branching, polarity, and environment. Therefore, it is highly beneficial to adjust the frequencies or range of frequencies used for the particular organism to achieve more efficient energy transfer. Thus, the frequencies can range over the entire microwave spectrum (300 MHz to 300 GHz1 or wavelengths from about 1 mm to about 1 m), and even through the infrared spectrum (wavelengths from about 750 nm to about 1 mm). (See additional discussion of infrared radiation below.)
[00197] Microwave frequencies (or wavelengths) which provide particularly advantageous energy coupling to lipids in microorganisms (especially cell membrane lipids) can be determined by scanning across the microwave spectrum. Advantageously, selected frequencies will have efficient coupling to the desired molecules (e.g., phospholipids) and efficient coupling compared to the coupling to water molecules. Most advantageous are frequencies at which the interaction between the lipids and the microwaves is strong and the interaction between the microwaves and water is not so high as to lose excessive energy to heading the bulk fluid.
[00198] Thus, for at least the initial determination of advantageous microwave frequencies, a variable frequency signal generator is useful, with the generated signal then amplified using a signal amplifier before being directed to the cell suspension (typically in a waveguide). Depending on the particular lysing application, such variable frequency signal generator can be used for production purposes, or a fixed frequency (or limited spectrum) signal generator can be selected and used where that signal generator produces frequencies suitable for that intended application. Similarly, any other source of microwave radiation which produces microwaves of effective frequency and intensity may be used.
[00199] Likewise, infrared radiation is an intrinsic part of the environment, and similarly has no deleterious effects under such conditions. However, infrared radiation can also couple to molecules and transmit energy to such molecules, generally in the form of vibrational motion. This effect has been exploited for IR spectroscopy as well as for both generalized and specific molecule heating.
[00200] For example, Altschuler et al., US Pat 6605080 (which is incorporated herein by reference in its entirety) describes the use of infrared heating at specific wavelengths to target and liquefy fat tissue. As reported in that patent, certain wavelength bands showed significantly better lipid absorption than others, with advantageous ranges of 880-935, 1150 to 1230, 1690 to 1780, and 2250 to 2450 nm, corresponding to peaks of approximately 920, 1210, 1715, and 2300 nm. For certain of the wavelengths, the ratio of the absorbance factor of lipid to the absorbance factor of water approached 2. Sources for providing IR radiation in the specified bands were described, including IR lasers.
[00201] Thus, similar to the process indicated for microwaves and as described in US Pat 6605080, effective IR frequencies can be identified and used to preferentially target cell membrane lipids in particular microorganisms.
[00202] Thus, the present invention can utilize either or both of microwave and infrared radiation for lysing (or at least weakening) cells membranes and/or cell walls. As described above, frequencies which energetically couple efficiently to water may be used, but preferably one or more frequencies are used which couple effectively with cell membrane and/or cell wall components (desirably more efficiently than with water) of a microorganism which is to be cultured (or is being cultured). In this way, the cell membranes and/or cell walls can be selectively disrupted, lysing or at least weakening the cell. [00203] Such advantageous treatment of the microorganism cells can utilize multiple frequencies or frequency bands in the microwave and/or IR spectra. As was mentioned above, commonly particular types of molecules have multiple frequencies at which the interactions with the microwave or IR radiation is more efficient than at others and/or the ratio of the interaction efficiencies (e.g., absorption factors) for the target molecules compared water is sufficiently high to provide effective disruption of the cell membrane and/or cell wall materials rather than just heating the bulk medium. Such frequencies are preferably selected for use in the present invention, even though bulk medium heating will lyse cells and can be used.
[00204] In addition to the use of microwave and/or IR frequencies, other frequencies of the electromagnetic spectrum which can disrupt or otherwise weaken cell walls and/or cells membranes can be used in the present invention. For example, it has been shown that UV irradiation can damage cell walls or cell membranes. Thus, such UV irradiation can be used, separately or in combination with microwave and/or IR irradiation to disrupt cell walls in the present bulk processing system. Similarly, any other wavelengths which are found to weaken or disrupt cell walls and/or cell membranes may be used in the present invention. The damage to cell walls and/or cell membranes may be of one or more types. For example, the electromagnetic radiation may thermally heat the particular cell structure and thereby weaken it and/or break bonds within a structure (e.g., cell wall) and/or heat and create internal pressure in the cell sufficient to break a cell membrane and/or cell wall.
[00205] The disruption created by the electromagnetic radiation (e.g., microwave and/or IR and/or UV) treatment can advantageously be carried further by using a second high throughput disruption method. An advantageous method is the use of a micron bubble flocculation unit. Such micron bubble cell disruption is described, for example, in Eckelberry, US Pat. Appl. 11/829883, entitled Algae Growth System for Oil Production, which is incorporated herein by reference in its entirety. In such a system, a cell suspension is processed through a mixer which creates a very large number of micro bubbles, e.g., creating a bubble slurry. In a suitable container, collapse of those bubbles generates shock waves or cavitation effects which can lyse or further disrupt microorganism cells.
[00206] Alternatively, another source of ultrasonic waves may be used. Thus, for example, it was recently found that the use of ultra-sound in a growth reactor promotes micro-algae cell collapse (e.g., as described in 6,540,922 Cordemans et al.).
[00207] In contrast, we have found that by using certain static mixers, including but not limited to the particular mixer described in Uematsu, U.S. Patent 6,279,611 (incorporated herein by reference in its entirety), we can generate the same frequencies required to affect cellular breakdown without the added costs of the sound generator.
[00208] This is accomplished by generating bubbles with an average size of about 60mμ or less and causing the bubble field to include both micron and nano bubbles in varying percentages. For example, this can be accomplished using a static mixer that generates appropriately small bubbles and often using multiple passes with the recirculating pump to decrease the average bubble size. Due to the configuration of the mixing vessel in relation to the reactor vessel, we can introduce this mix of both micron and nano sized bubbles without affecting the content of the reactor. However, by having two vessels, one for mixing and other a reaction vessel, the latter can now act as the implosion vessel. The micron mix of water, air and chemicals will seek to reconfigure in the reaction vessel, e.g., to return to its homeostatic state as found in nature. The characteristic of such extensive mixing of air and water concurrent with other elements as required such as alcohols, ozone and other amendments is fourfold:
[00209] 1. A micron mix of fluids, air and chemicals, created by a mixer, which, upon disgorgement in the secondary vessel creates a shock wave on cavitation implosion within the reaction vessel. A report of such shock wave generation stated that with strong bubble interaction effects, the collapse of the cloud is accompanied by the formation of an inward propagating bubbly shock wave. A large pressure pulse is produced when this shock passes the bubbles and causes them to collapse. The focusing of the shock at the center of the cloud produces a very large pressure pulse which radiates a substantial impulse to the far field and provides an explanation for the severe noise and damage potential in cloud cavitation.
[00210] 2. The ultrasonic effect created concurrently with the propagation of the shock wave. The value of the shock wave in cell disruption occurs when the stretched bubble is imploded; this can advantageously be accomplished when there are two vessels; a bubble creation/mixing vessel and an implosion vessel.
[00211] 3. The creation of excessive heat which further oxidizes the micro-algae. This heat is generated by the friction caused by the breakdown of material and the inherent quality of the micron bubble shock wave to propagate and refract on cell material.
[00212] 4. Optionally, if ozone is added, the oxidizing quality of ozone gas mixed at micron level now reconfigured to oxygen, as it has donated it's free radical to the organic material.
[00213] Thus, for carrying out extraction, the holding period of the micron mixed fluid in the mixing chamber (used during the growth phase) is dispensed with, and the micron mixture of water and any constituents to be used to assist cell disruption and/or extraction (e.g., enzymes, though the disruption can be performed without enzymes) is flowed directly to the inner dispensing rod and into the reaction chamber, where the cavitation effect promotes the ultra-sonic breakdown of the cell wall.
[00214] The mix can then be processed through a separator to remove lipid components. Such separator may be of a variety of different types. For example, the mix can be separated by processing in a flocculator where the mixture flocculates due to the micro-bubble activity, removing much of the bio-mass. The oil and water can be separated, e.g., based on density differential, such as by settling and/or in a centrifuge.
[00215] Alternatively or in addition, extraction of lipids can be carried out in various other ways. For example, hexane solvent extraction can be used in isolation or it can be used along with an oil press/expeller method to obtain the lipids. For example, after the oil has been extracted using an expeller, the remaining pulp can be mixed with cyclohexane to extract the remaining oil content. The oil dissolves in the cyclohexane, and the pulp is filtered out from the solution. The oil and cyclohexane can be separated by means of distillation. These two stages (cold press & hexane solvent) together will be able to extract more than 95% of the total oil present in the algae. Another extraction method is the super critical fluid method (usually using CO2).
[00216] Thus, the present invention utilizes electromagnetic radiation, e.g., microwaves, as an initial cell treatment to lyse or at least weaken microorganism cell structure. For example, a microwave signal of appropriate frequency can be generated, amplified and directed through a wave guide implanted within a cylinder for inline cell lysing of algae for the purpose of lipid extraction. The broken biomass can then be processed through an additional cell disruption mechanism. In an advantageous system, the broken biomass suspension is entrained through a static mixer creating a micro-bubble slurry which in turn further disrupts the cells through the ultrasonic effect of cavitation. As the micro-bubbles reconfigure, the extracted lipids float to the top for ultimate recovery and processing.
[00217] A simplified layout of an inline microwave lysing system is shown in Fig. 1. This system is referred to as an inline microwave lysing system because the lysis chamber is inline in the system flow, as distinguished, for example, from a separate holding tank. In the system the lysing chamber is an inline wave guide fitted inline in a pipe which is fed by an algae grow unit. The algae (or other microorganisms) are subjected to the microwaves as they pass through the pipe. Preferably the microwaves or other electromagnetic radiation is at specific frequencies selected to be effective to accomplish or assist cell lysis and/or lipid extraction. Such frequencies may vary, e.g., according to algae genus. For microwave radiation, the wave guide (and associated pipe) if preferably RF FCC compliant shielded pipe.
[00218] As schematically illustrated in Fig. 8, the microwave signal is generated with a signal generator (150), which is connected to an amplifier (152) which in turn is connected to a wave guide (154) which acts as the transmission antenna. As the algae mass is dropped into the T connector of algae input pipe (156) it is prevented from back flushing by a one way valve (158). The product is continuously microwaved as it is entrained by the pump (160). After passing through the microwave wave guide region the algae is pumped through pipe 162 to a flocculation unit or other downstream processing components (not shown). The wave guide is effectively the antenna and is highly preferably properly shielded to comply with FCC or other rules. Wave propagation into the environment is limited by the configuration of the system itself with the pump acting as the stop point.
[00219] This microwave lysing system can be incorporated into a complete system as shown in simplified schematic form in Fig. 9. In this system, algae or other microorganisms are grown in grow tank (170) which cultivates the bio-mass. The bio-mass is then fed (e.g., by gravity flow) into a water/biomass separator, e.g., a vortex, or cyclone separator (172) which removes a substantial amount of the water from the culture, typically leaving a slurry. Preferably sufficient water remains so that the cell suspension will readily flow in a pipe. Thus, the cell suspension (with sufficient water) is passed (e.g., by gravity flow) into container (174). The excess liquid (176) can sent back to the grow tank for reuse in growing. The bio-mass product (i.e., the cell suspension) then flows through the microwave waveguide as described for Fig. 8, where it is microwaved inline. The microwaved cell suspension is pumped by pump 160 through static mixing micronizing unit (164), creating a bubble slurry with micron bubbles (e.g., commonly of about 60 micrometer or less). The disrupted cell suspension is passed to a flocculator/separator 166 where oil 166 is separated from residual biomass 168 and water. The residual biomass can be passed to a digester 169 or simply used as feed cake or fertilizer, or other such uses.
ELECTRICITY GENERATING SYSTEMS
[00220] In some applications, it is beneficial to arrange a system for a loop method for the generation of electricity. Whether used at water reclamation sites or bioreactors, the process is based on an ability to grow a large amount of algae continuously and in a sustainable manner, which may be in either in salt or fresh water. In some cases, this system incorporates a growth system and/or lysis system as described above. The system is configured to minimize or at least significantly reduce the release of carbon dioxide and methane from an integrated carbon fixation and electricity generating system.
[00221] Thus, the present systems incorporate controlled algae growth followed by suitable processing of the biomass output of that growth. Highly preferably the grow tanks for the system include covers and exhaust pipes to capture the O2 generated by the photosynthetic algae growth. The algae mass is cultivated in such a manner as to produce the maximum amount of biomass with economy of space, time and energy usage. A large percentage of the slurry of mature biomass and water is regularly disgorged into a water mass separator such as a cyclone, centrifuge, and/or plane separator. After the biomass is separated from much of the culture water, the biomass is shunted to a digester, usually an anaerobic digester.
[00222] The green or culture water, separated from its major biomass constituent, can be used for CO2/methane separation. For example, the green water can be entrained through a methane/CO2 bubble column where it is used as a high pH matrix to enhance separation of the two gases produced by the digester. The CO2 is cycled back for reuse in the grow tanks, e.g., after compression and holding in tanks, for use in the growing of algae. The methane gas and recovered O2 can be piped (even co-piped) to a co-generation electricity or heat production unit such as a boiler and steam driven electric generator.
[00223] The green water recovered from the digester can be disinfected (e.g., ozone disinfected) and recycled back into the grow tanks where it is commingled with the algae mass to start a new algae expansion cycle. More incubated algae and fresh or salt water (as appropriate for the particular culture) are additionally mixed with fresh nutrients and CO2 to ensure maximum growth. The system preferably includes real time computer monitoring of relevant process parameters, e.g., disbursement of nutrients, CO2, temperature, bacteria count and cell count, to ensure proper management of resources. [00224] The process can include further innovations in regards to fluid handling, such as the use of micro-bubbles in the high pH matrix in the column separation phase and the use of micro-mixing of oxygen and methane in the cogeneration phase to optimize heat production and reduce NOX emissions through elevation of boiler temperatures.
[00225] Furthermore, the addition of oxygen to the burning of methane gas drives the burn process to more complete combustion, resulting in primarily CO2 and water being produced, according to the reaction
CH4 + 2 O2 - -> CO2 + 2 H2O
[00226] Therefore the by-product of the loop under ideal conditions is substantially pure water and CO2, which can be recovered and reused in the process. Residual ash can be used for mineral supplementation in the process and/or for uses external to the system.
[00227] The residual biomass from the digester can also be utilized within the system or externally. For example, the residual biomass can be used to provide nutrients for algae growth within the system, e.g., to provide nitrogen such as in the form of nitrates, or can be burned, e.g., for generating heat. Alternatively, the residual biomass can be used for fertilizer or other high nitrate value organic soil amendment. When used as a fertilizer or other soil amendment, carbon compounds within the residual biomass can increase soil organic matter, remaining sequestered in the soil and/or in plants growing in that soil for significant periods of time. Preferably the enzymes used in anaerobic digestion are neutralized prior to reuse.
[00228] The present invention can incorporate and utilize applicable previously described technologies for the various process stages. For example; "Production of high methane content product by two phase anaerobic digestion". Thomas D. Hayes et al. (Patent number: 4,722,741 Filing date: Mar 11 , 1985), which is incorporated herein by reference in its entirety, has direct relevance for methane separation. [00229] A simplified schematic of a system is shown in Fig. 10. In this system, algae is cultivated in grow area (170). This area can, for example, be any of the following: Waste treatment plant container, open sea containment area, grow tank with lights, grow tank as described by Oswald 3,520,081 "Method for growing algae" Nov 1964, Shoon 3,763,824 "System for growing aquatic organisms" Nov 1971, where log product is retained for future incubation, Oswald et al. 3,362,104, Nov 13, 1964, all of which are incorporated herein by reference in their entireties, or any other method which provides rapid growth and economy of scale.
[00230] On a regular basis, often on about a daily basis, a significant fraction (often most) of the culture medium with grown biomass is released into a water separator (172) where the biomass is separated from water. The algae grow area (170) retains a percentage of the mature algae, often 10-20%, so as to maintain actively growing algae (e.g., log rate growth) in the grow area. The bio-mass (174) separated from most of the culture water is moved to a digester such as an anaerobic digester (176), where, through enzymatic breakdown, methane gas and associated CO2 (177) are produced.
[00231] The gases generated by the digestion are passed through a CO2/methane separator such as column separator (180). In conjunction with the contact of methane and CO2 through the CO2/methane separator, the green water (182) from the water separator (172) can be entrained through a pump (e.g., centrifugal pump) (184) and a static mixer (186) where a plurality of microbubbles is generated, thereby enhancing contact between the highly alkaline water and the gases system, thereby obtaining the benefits as described by John A. Cairo, Jr. et al., US Pat 5,156,745, issued Nov 13, 1990, "Induced gas liquid coalescer and fluid separator", which in incorporated herein by reference in its entirety. A system based on the finding of the benefits of alkaline matrix in the separation of methane and CO2 is described in Leonard S. Love, US Pat 4,530,762, issued Mar 28, 1984 (which is incorporated herein by reference in its entirety) wherein Love describes a method of increasing methane extraction through caustic soda injection in a timely manner promoting more efficient methane extraction. [00232] The use of the highly alkaline (typically of a pH of 9.0 or higher) green water from the biomass/water separation in the Cθ2/methane separation phase lowers the demand for chemicals, deleterious CO2 bubble formation, and transit time. The green water (188) which will be recycled to the grow areas is now rich in suspended CO2 as well as carbon compounds and others that are part of a nutrient stream for the mature algae in the grow tanks.
[00233] In the final stage, the methane gas (190) is combusted in a methane powered electricity generating system, e.g. burned in a boiler (192). CO2 emitted from the burn stage can be recaptured and used in the grow stage, e.g., after compression and storage.
[00234] Prior to burning for the production of electricity, the methane and recovered oxygen (194) can be co-mixed, e.g., with the use of a pump (196) and static mixer (198). The use of turbulent flows at the injection stage of fluids for combustion is referenced in Beer, US Pat 5411394, issued Oct 5, 1993 (which is incorporated herein by reference in its entirety), where it is indicated that the use of turbulent flows in the injection ports, reduces NOX. In most cases, injection of O2 to increase yield is not widely used in industry due to the high cost of oxygen and issues relating to transport. In contrast, in the present system the cultivation of large amounts of algae generates an excess of oxygen which can be used to improve methane burning and electricity production with low cost and improved practicality.
[00235] It is envisioned that the system would include storage and in some cases compression systems to store oxygen, methane and/or CO2 at applicable stages. Such compression will require energy input. Any such energy input is highly preferably from renewable sources, e.g., electricity produces by wind, photovoltaic arrays, and/or other renewable sources of energy.
[00236] In addition, burning of the methane or other combustible fuel generates substantial heat. Some of that heat, e.g., heat generated from the boilers and remaining after passing steam through a steam powered electrical generator, can be used for growth tank heating as needed. Water/Biomass Separation
[00237] Methods and apparatus for separating biomass from culture medium are well known. Any of a variety of such approaches can be used in the present invention. However, it is advantageous to select an energy efficient method. Examples include cyclones, centrifuges, and inclined plane separators. Alternatively or in addition, membrane or other filtration media separations may also be used. A large variety of such separators have been described and may be used for separating biomass and water.
Digesters
[00238] Following removal of a large fraction of the culture water from the biomass, the biomass can be digested. In most cases, this will be performed using an anaerobic digester. The use of such digesters has been described, for example, for digesting manure. Such applications also include using the resulting methane for power generation. Different digesters will produce differing relative proportions of CO2 and methane, e.g., ranging from about 50% methane to about 90% methane. Preferably, other gases are produced in at most minor amounts. In most cases, such digesters are bacterial digesters, but enzymatic digesters can also be used.
[00239] For example, various digesters and systems have been described in Ainsworth et al., US Pat 6,569,332; Nilsson et al., U.S. Pat. Nos. 5,906,931 , Masse et al, No. 5,863,434., No. 5,821 ,1 11 to Grady et al. No. 5,746,919 to Dague et al., No. 5,709,796 to Fuqua et al., No. 5,626,755 to Keyser et al., No. 5,567,325 to Townsley et al., No. 5,525,229 to Shih, No. 5,464,766 to Bruno, No. 5,143,835 to Nakatsugawa et al., No. 4,735,724 to Chynoweth, No. 4,676,906 to Crawford et al., No. 4,529,513 to McLennan, No. 4,503,154 to Paton, No. 4,372,856 to Morrison, No. 4,157,958 to Chow, and No. 4,067,801 , each of which is incorporated herein by reference in its entirety.
[00240] In addition to digesters which produce methane, digesters (or fermenters) which produce other combustible fuels, e.g., ethanol, can be used as alternatives to or in addition to methane producing digesters. In such cases, the alternative combustible fuel can be used similarly to the methane for use in a combustible fuel driven electrical generator system.
[00241] In most cases, the biomass separated in the water/biomass separator will be used in the digester without additional processing. However, in some cases, it may be desirable, e.g., for more efficient digestion, to further process the biomass. For example, in some cases it may be desired to further dry the biomass, e.g., using heating and/or vacuum drying. More commonly, it may be desirable to disrupt cells in the algae biomass. A number of different methods may be used, including mechanical, ultrasound, and/or microwave approaches. For example, microwave cell lysis systems such as those described in Shigematsu et al. US Prov Pat Appl 61/061 ,661 , filed 06/16/2008, which is incorporated herein by reference in its entirety, may be used in the present invention.
CO2/Methane Separation from Digester
[00242] As indicated above, in most cases a digester or digesters will be used which produce substantial methane. However, the methane is usually mixed with CO2. At least two alternatives exist for utilizing the methane. The methane and CO2 mixture can be burned directly without separation. This will result in higher CO2 levels in the exhaust gas from the burning. Advantageously, the CO2 can be substantially from the methane prior to the burning. A beneficial approach for this is to use the difference in solubility of CO2 and methane is a polar solvent as a separation mechanism. This property may be exploited in a variety of different separators. One convenient and relatively inexpensive approach is to pass the CO2/methane mix over a column in which the respective gases can efficiently partition between an aqueous phase and a gas phase. It has also been found that high pH aqueous solutions are more effective for this separation. Because the spent culture water is typically high pH, e.g., usually at or above pH 9.0, the aqueous phase may be (or include) the spent culture water.
[00243] In some cases, the gas partition may be enhanced by creating microbubbles of the gases being separated with the aqueous phase, e.g., by pumping the aqueous phase (e.g., culture water) through a static mixer which entrains microbubbles of the gas.
[00244] The result of using differential partition of the CO2 and methane between an aqueous phase (or other solvent) is generally that the CO2 will be substantially stripped from the gas phase and will be in solution in the liquid phase. Such aqueous phase (e.g., culture water) can be recycled in the system (usually after sterilization, e.g., by UV or ozone) for growth of additional algae.
Electricity generation
[00245] As described above, the methane, or other combustible fuel (e.g., ethanol) produced in the present system, can advantageously be used to directly or indirectly power an electrical generator. Under suitable conditions, the combustible fuel may be used directly, such as in an internal combustion engine) to drive an electrical generator. This approach is particularly suitable if a clean methane is produced in the system.
[00246] An alternative is to use the combustible fuel to generate heat, which is used to generate steam, which is used to drive a steam turbine, which drives the electrical generator.
[00247] Either of these approaches (and variants thereof) will produce significant amounts of CO2 (along with water) from the methane burning. If the burning is sufficiently clean, the exhaust gas may be used to provide CO2 without further purification. However, in many cases, the exhaust gas will also include appreciable amounts of NOX and/or sulfur-containing compounds. Particulate matter may be removed by conventional methods, e.g., by density-based methods, electrostatic methods, and/or filtration methods. In addition, it is often beneficial to remove or at least substantially reduce NOX and sulfur-containing gas compounds. This can be accomplished using any of a variety of methods, e.g., using methods applicable to scrubbing flue gases. [00248] The amount of such NOX compounds may be reduced using oxygen injection. For example, oxygen produced by the algae during photosynthetic growth may be captured and used, e.g., as indicated in the following section.
[00249] Still another alternative is to use a fuel cell electrical generating system. The type of fuel cell will dictate the fuel to be used, e.g., hydrogen, methanol, methane, etc. For systems in which hydrogen is used in the fuel cell, generally a combustible fuel produced in the digester will be passed through a reformer to produce hydrogen. Thus, the present systems can include fuel cell generating systems, either with or without a reformer.
CO2 Capture from Burning
[00250] Methods for capturing CO2 from gases generated by burning of carbon- based fuels are known and can be utilized in the present systems and methods. For example, substantial development has taken place for capturing CO2 from natural gas and coal powered electrical generating plants. Commonly, when air is used in the combustion, the exhaust gases include substantial CO2, along with NOX compounds and often some sulfur-containing compounds. Of course, for such fuels, using oxygen rather than air for combustion will result in substantially less or even essentially no NOX and/or sulfur-containing compounds in the exhaust gases. In particular, where methane is used as the fuel, burning the methane will produce primarily CO2 and water. However, use of oxygen (with its associated storage costs and dangers) is usually impractical. In the present systems, oxygen produced by and collected from the algae growth process can be used to enrich the combustion air. It has been reported that injection of oxygen in a combustion chamber will reduce NOX production as well as cause generally cleaner burning due to increased heat. These properties can be used in the present systems.
[00251] For example, the oxygen from the algae growth may be injected in the combustion chamber. This injection can advantageously be performed after mixing the algae-produced oxygen with air and/or the methane. As indicated, this will result in cleaner burning. [00252] All patents and other references cited in the specification are indicative of the level of skill of those skilled in the art to which the invention pertains, and are incorporated by reference in their entireties, including any tables and figures, to the same extent as if each reference had been incorporated by reference in its entirety individually.
[00253] One skilled in the art would readily appreciate that the present invention is well adapted to obtain the ends and advantages mentioned, as well as those inherent therein. The methods, variances, and compositions described herein as presently representative of preferred embodiments are exemplary and are not intended as limitations on the scope of the invention. Changes therein and other uses will occur to those skilled in the art, which are encompassed within the spirit of the invention, are defined by the scope of the claims.
[00254] It will be readily apparent to one skilled in the art that varying substitutions and modifications may be made to the invention disclosed herein without departing from the scope and spirit of the invention. For example, variations can be made to the tank size, shape, and/or construction materials; to the light array size, number, placement, and/or light configuration; to the selection of cultured organism, to the culture media used, and/or to the product obtained from the cultured cells. Thus, such additional embodiments are within the scope of the present invention and the following claims.
[00255] The invention illustratively described herein suitably may be practiced in the absence of any element or elements, limitation or limitations which is not specifically disclosed herein. Thus, for example, in each instance herein any of the terms "comprising", "consisting essentially of and "consisting of may be replaced with either of the other two terms. The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention that in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by preferred embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention as defined by the appended claims.
[00256] In addition, where features or aspects of the invention are described in terms of Markush groups or other grouping of alternatives, those skilled in the art will recognize that the invention is also thereby described in terms of any individual member or subgroup of members of the Markush group or other group.
[00257] Also, unless indicated to the contrary, where various numerical values or value range endpoints are provided for embodiments, additional embodiments are described by taking any 2 different values as the endpoints of a range or by taking two different range endpoints from specified ranges as the endpoints of an additional range. Such ranges are also within the scope of the described invention. Further, specification of a numerical range including values greater than one includes specific description of each integer value within that range.
[00258] Thus, additional embodiments are within the scope of the invention and within the following claims.

Claims

WHAT IS CLAIMED IS:
1. A culture system for photosynthetic microorganisms, comprising a culture tank; at least one light array positioned within said tank, wherein said light array provides a plurality of light paths sufficiently short to provide photosynthetically effective light to substantially all of the photosynthetic microorganisms passing between adjacent light sources in said array; and a drive which causes relative motion between growth medium in said culture tank and said light array.
2. The culture system of claim 1, wherein said light array is a rotatable light array.
3. The culture system of claim 2, wherein said rotatable light array comprises an axle, a rotational drive connection linked to said axle, and a plurality of light emitting projections extending outward from said axle.
4. The culture system of claim 3, wherein said rotatable light array comprises a plurality of flat arrays distributed along said axle.
5. The culture system of claim 4, wherein adjacent flat arrays are separated a distance of 0.5 to 5 cm.
6. The culture system of claim 4, wherein a flat array comprises at least 4 light wands.
7. The culture system of claim 2, wherein during normal use, said rotatable light array rotates at 0.5 to 10 rpm.
8. The culture system of claim 3, wherein said axle is positioned substantially vertically in said tank.
9. The culture system of claim 3, wherein said axle is positioned substantially horizontally in said tank.
10. The culture system of claim 1 , wherein said light array comprises a plurality of light emitting projections extending upward.
11. The culture system of claim 10, wherein said array is rotatable and rotation of said light array is driven by a central drive shaft.
12. The culture system of claim 1 , wherein said light array comprises a plurality of light emitting projections extending downward.
13. The culture system of claim 12, wherein said light array are mounted in a generally planar circular mounting body.
14. The culture system of claim 13, wherein said mounting body is positioned above the fluid level in said tank.
15. The culture system of claim 12, wherein said light array is rotatable.
16. The culture system of claim 15, wherein said light array is mounted in a generally planar circular mounting body and said mounting body is driven by a rim drive.
17. The culture system of claim 1 , wherein said at least one light array comprises a first array comprising a plurality of light emitting projections extending upward and a second array comprising a plurality of light emitting projections extending downward.
18. The culture system of claim 17, wherein said first and second array intermesh.
19. The culture system of claim 18, wherein said first array or said second array or both are rotatable.
20. The culture system of claim 17, wherein the light emitting projections of said first array terminate below the light emitting projections of said second array.
21. The culture system of claim 20, wherein said first array or said second array or both are rotatable.
22. The culture system of claim 1, comprising a plurality of said light arrays.
23. The culture system of claim 1 , wherein the wavelengths of light emitted from said light wands is selected to provide effective photosynthesis while reducing power consumption.
24. The culture system of claim 1 , further comprising at least one channel for distributing nutrients to culture media in said tank.
25. The culture system of claim 1 , further comprising a light controller which controls at least one parameter selected from the group consisting of light intensity, illumination periods, and light wavelength for light emitted from said light wands.
26. The culture system of claim 25, further comprising at least one culture medium sensor, wherein said controller receives signals from said sensor and controls light emitted from said light wands at least in part as a function of said signals.
27. The culture system of claim 26, wherein said signals correspond to pH or oxidation reduction potential (ORP) or both.
28. The culture system of claim 1 , wherein said drive causes circulation of culture medium in said culture tank and through said light array.
29. The culture system of claim 1 , wherein said drive causes circulation of culture medium in said culture tank and through said light array, and also causes rotation of said light array.
30. The culture system of claim 1 , wherein photosynthetically effective illumination is provided to substantially all culture medium passing through said light array on substantially the same periodicity and with approximately equal illumination intervals.
31. The culture system of claim 1 , wherein said at least one light array comprises a distribution of downwardly extending or upwardly extending light emitting projections or both arranged over an area in a pattern such that essentially all culture medium within said light array is exposed to photosynthetically effective light , and
32. A light distribution array, comprising a plurality of light emitting wands mounted in a light mounting body and extending from said body, wherein said light emitting wands are spaced 0.5 to 5 cm apart.
33. The light distribution array of claim 30, wherein said array is configured to provide photosynthetically effective light in a photobioreactor.
34. The light distribution array of claim 30, wherein said light mounting body is an axle.
35. The light distribution array of claim 32, comprising a plurality of flat arrays of light emitting wands mounted on said axle.
36. The light distribution array of claim 32, wherein said light emitting wands are distributed along said axle over a distance of at least 0.5 m.
37. The light distribution array of claim 31 , wherein said array comprises a plurality of light emitting wands oriented in a generally upward orientation when said array is mounted in a photobioreactor.
38. The light distribution array of claim 31 , wherein said array comprises a plurality of light emitting wands oriented in a generally downward orientation when said array is mounted in a photobioreactor.
39. The light distribution array of claim 30, wherein said light emitting wands comprises at least one light source which is a light emitting diode (LED), a cold cathode fluorescent light (CCFL), or an external electrode fluorescent light (EEFL).
40. A system for carbon fixation and product recovery, comprising a culture system comprising a culture tank; a light array comprising a plurality of light emitting projections positioned so that said projections extend within said tank such that that essentially all culture medium in said tank passing between adjacent light emitting projections will receive photosynthetically effective illumination; a drive which causes relative motion between growth medium in said culture tank and said light array; and a process controller which monitors at least one culture parameter indicative of photosynthesis and regulates at least one of light duration, light intensity, and light wavelength.
41. The system of claim 38, wherein said array is rotatable.
42. The system of claim 38, wherein said light emitting projections are mounted on a mounting body.
43. The system of claim 39, wherein said mounting body is an axle.
44. The system of claim 41 , wherein said plurality of light emitting projections are mounted on and extend outward from said axle.
45. The system of claim 40, wherein said mounting body is a generally horizontal planar structure.
46. The system of claim 40, wherein said array is rotatable.
47. The system of claim 38, wherein said light array comprises a plurality of light emitting projections extending upward.
48. The system of claim 45, wherein said array is rotatable and rotation of said light array is driven by a central drive shaft.
49. The system of claim 38, wherein said light array comprises a plurality of light emitting projections extending downward.
50. The system of claim 47, wherein said light array are mounted in a generally planar circular mounting body.
51. The system of claim 47, wherein said light array is rotatable.
52. The system of claim 49, wherein said light array is mounted in a generally planar circular mounting body and said mounting body is driven by a rim drive.
53. The system of claim 38, wherein said at least one light array comprises a first array comprising a plurality of light emitting projections extending upward and a second array comprising a plurality of light emitting projections extending downward.
54. The system of claim 51 , wherein said first and second array intermesh.
55. The system of claim 51 , wherein said first array or said second array or both are rotatable.
56. The system of claim 51 , wherein the light emitting projections of said first array terminate below the light emitting projections of said second array.
57. The system of claim 38, further comprising an oil extractor.
58. The system of claim 38, further comprising a biomass digester which receives biomass from said culture tank.
59. The system of claim 38, further comprising an electrical generator powered by at least one product of the system.
60. The system of claim 57, wherein said product is an oil-based fuel.
61. The system of claim 57, wherein said product is biomass.
62. The system of claim 57, wherein said product is methane.
63. The system of claim 38, further comprising a biomass digester, wherein CO2 produced in said digester is used as a nutrient in said culture tank.
64. A method for growing photosynthesizing microorganisms, comprising exposing photosynthetic microorganisms in a growth medium in a photobioreactor to photosynthetically effective light from a light array, wherein said light array comprises a plurality of light wands spaced such that substantially all of the growth medium between successive light wands in said light array receive photosynthetically effective illumination.
65. A modular system for photosynthetic growth of microorganisms, comprising at least one photosynthetic microorganism growth module comprising a support frame; a plurality of growth tanks mounted in said support frame, wherein each said growth tank comprises a growth sensor set and a light array comprising a plurality of light sources arranged such that photosynthetically effective light is provided by said light sources to substantially all of the culture medium within the volume described by said light array, a nutrient injection system, wherein at least one growth process parameter is controlled by a growth controller in response to at least one signal from said growth sensor set.
66. The modular system of claim 65, wherein said growth controller is mounted within said support frame.
67. The modular system of claim 65, wherein said support frame is a freight container.
68. The modular system of claim 65, wherein said growth module is stackable with at least one other said growth module.
69. The modular system of claim 65, comprising a plurality of said growth modules.
70. The modular system of claim 65, further comprising a microorganism processing module which comprises a lipid separator.
71. The modular system of claim 70, further comprising a dewaterer.
72. The modular system of claim 65, further comprising a microorganism processing module which comprises a biomass digester receiving biomass grown in said growth tanks. ^
73. The modular system of claim 72, wherein methane generated by said biomass digester is used as a fuel for an electrical generator.
74. The modular system of claim 65, wherein each of the tanks in said plurality of growth tanks has a liquid capacity of at least 200 liters.
75. The modular system of claim 65, comprising 4 to 8 growth tanks.
76. The modular system of claim 65, wherein at least 20,000 liters of microorganism culture is grown simultaneously.
77. The modular system of claim 65, further comprising a dewatering system which removes water from biomass grown in said growth tanks; and a water recycling system which recycles said water back to said growth tanks.
78. The modular system of claim 65, wherein said nutrient injection system comprises a connection for CO2 from an external CO2 generator.
79. The modular system of claim 78, wherein said external CO2 generator is a power plant burning carbon-based fuel.
80. The modular system of claim 65, wherein said nutrient injection system comprises a CO2 storage tank.
81. The modular system of claim 65, comprising at least four of said photosynthetic microorganism growth modules.
82. The modular system of claim 65, wherein said modular system also comprises a remote monitoring and control system.
83. The modular system of claim 82, wherein said monitoring and control system includes an internet link.
84. A method for growing photosynthetic microorganisms, comprising culturing photosynthetic microorganisms in a modular system for photosynthetic growth of microorganisms, wherein said modular system comprises at least one photosynthetic microorganism growth module comprising a support frame; a plurality of growth tanks mounted in said support frame, wherein each said growth tank comprises a growth sensor set and a light array comprising a plurality of light sources arranged such that photosynthetically effective light is provided by said light sources to substantially all of the culture medium within the volume described by said light array, a nutrient injection system, wherein at least one growth process parameter is controlled by a growth controller in response to at least one signal from said growth sensor set.
85. A system for obtaining lipids from microorganisms, comprising an inline microwave system directing microwave radiation into microorganisms suspended in an aqueous medium in a conduit; and a micron mixer positioned such that it accepts said microorganisms after they are subjected to said microwave radiation, and which creates microbubbles in said medium, wherein said microwave radiation lyses at least some of said microorganisms and said micron mixer causes additional cell degradation or cell lysis or both.
86. The system of claim 85, wherein at least 50% of the energy of said microwave radiation is in the range of 300 MHz to 300 GHz.
87. The system of claim 85, wherein at least 50% of the energy of said microwave radiation is in the range of 300 MHz to 1 GHz.
88. The system of claim 85, wherein at least 50% of the energy of said microwave radiation is in the range of 1 GHz to 30 GHz.
89. The system of claim 85, wherein at least 50% of the energy of said microwave radiation is in the range of 30 GHz to 300 GHz.
90. The system of claim 85, wherein said microwave radiation is scanned over multiple frequencies.
91. The system of claim 85, wherein said conduit comprises a shielded pipe.
92. The system of claim 85, further comprising a culture concentrator positioned before said inline microwave system.
93. The system of claim 92, wherein said culture concentrator comprises a vortex separator.
94. The system of claim 92, wherein said culture concentrator removes at least 75% of the water of said aqueous medium.
95. The system of claim 85, further comprising an oil:water separator positioned to receive medium after passing through said static mixer.
96. Trie system of claim 95, wherein said separator separates a lipid phase and an aqueous phase.
97. The system of claim 96, wherein said aqueous phase comprises biomass, and said system further comprises a digester which receives said biomass.
98. A method for extracting lipids from microorganisms in a suspension, comprising exposing said microorganisms to microwave radiation within an inline waveguide, wherein said microwave radiation is at a frequency and intensity sufficient to lyse at least some of said microorganisms; and following said exposing, passing said microorganisms through a micron mixer which creates microbubbles in said suspension.
99. The method of claim 96, further comprising passing said suspension through an oil:water separator.
100. The method of claim 96, wherein said extracting is performed using a system of any of claims 85-97.
101. An inline microwave treatment system, comprising a signal generator which produces microwave frequency radiation; an amplifier which amplifies said microwave frequency radiation producing amplified microwaves; and an inline waveguide which receives said amplified microwaves and which is configured to allow flow of a suspension through said waveguide.
102. A method for lysing microorganisms, comprising directing microorganisms through a conduit; and directing microwave radiation into said microorganisms in said conduit at an intensity and at a frequency or frequencies sufficient to cause cell lysis.
103. The method of claim 102, wherein at least one said frequency is selected to preferentially target cell membrane lipids.
104. The method of claim 102, wherein at least one said frequency is selected to target one or more major cell wall constituents.
105. The method of claim 102, wherein said conduit is shielded and functions as a wave guide.
106. A method for providing an inline electromagnetic radiation lysing system, comprising selecting one or more electromagnetic radiation frequencies which target cell membrane lipids or cell wall components to a significantly greater degree than microwave radiation at 2.45 GHz; constructing an inline electromagnetic radiation delivery system wherein said electromagnetic radiation is delivered to a suspension containing volume.
107. The method of claim 106, wherein said electromagnetic radiation includes microwave radiation.
108. The method of claim 106, wherein said electromagnetic radiation includes infrared radiation.
109. The method of claim 106, wherein said electromagnetic radiation includes ultraviolet radiation.
110. The method of claim 106, wherein said electromagnetic radiation is adsorbed by said cell membrane lipids or cell wall components at least 0.5 of the level of absorption by water.
111. The method of claim 106, wherein said electromagnetic radiation is adsorbed by said cell membrane lipids or cell wall components at least at the level of absorption by water.
112. A method for renewable carbon sequestering production of electricity, comprising growing algae biomass in an algae culture system; separating said algae biomass from culture water; digesting said biomass, thereby producing a combustible fuel; burning said combustible fuel in an electrical generating system, thereby producing electricity; recycling CO2 from the exhaust gas of said burning to said culture system.
113. The method of claim 112, wherein said combustible fuel is methane.
114. The method of claim 112, wherein oxygen from said culture system is used in burning said combustible fuel.
115. The method of claim 113, wherein CO2 is separated from said methane prior to said burning.
116. The method of claim 115, wherein said culture water is used in separating said CO2 from said methane.
117. The method of claim 112, wherein oxygen from said culture system is micron mixed with methane from said digester prior to burning in said electrically generating system.
118. The method of claim 114, wherein CO2 is collected from the exhaust gas of said burning and is recycled in said algae culture system.
119. A system for renewable carbon sequestering production of electricity, comprising an algae culturing tank; an algae/water separator which receives culture medium from said culturing tank and separates algae biomass from culture water; a digester which receives said algae biomass from said separator and digestion of said biomass in said digester produces methane; a methane powered electrical generator which burns said methane from said digester; and at least one CO2 collector which separates methane from CO2 from said digestion or collects CO2 from the exhaust gases from said methane burning or both, wherein said CO2 is recycled for growing algae in said culturing tank.
120. The system of claim 119, wherein said CO2 collector comprises a CO2 separation column which receives combined methane and CO2 from said digester and removes C02 leaving at least partially purified methane.
121. The system of claim 119, further comprising a static mixer which receives methane from said digester and oxygen from said culturing system and micron mixes said methane and oxygen prior to burning in said methane powered electrical generator.
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