A system and method for growing algae

Abstract

A system (100) for growing algae comprises: (a) an algae growth and oxygen generation stage (10) comprising: an algae growth medium (14), said algae growth medium (14) receiving carbon dioxide (44) from a source of carbon dioxide (38); and a flow path (18A, 18B, 86, 91) through which algae growth medium flows from a feed end to a harvesting end; and (b) a control system for controlling operation of the closed system combustion stage and algae growth and oxygen generation stage, wherein the control system controls dosing of a nitrate species into algae growth medium (14) along the flow path (18A, 18B, 86, 91).

Description

A System and Method for Growing AlgaeTECHNICAL FIELD

[0001] This invention relates to a system and a method for growing algae including generating and using nitrate species for growing algae and which may usefully form part of a process for producing a chemical product, in particular a biofuel, from algal lipids.BACKGROUND ART

[0002] The following discussion of the background art is intended to facilitate an understanding of the present invention only. The discussion is not an acknowledgement or admission that any of the material referred to is or was part of the common general knowledge as at the priority date of the application.

[0003] All references, including any patents or patent applications, cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the Applicant reserves the right to challenge the accuracy and pertinence of the cited documents. It will be clearly understood that, although a number of prior art publications may be referred to herein, this reference does not constitute an admission that any of these documents forms part of the common general knowledge in the art, in Australia or in any other country.

[0004] NOx gases of which there is a mixture of many constituents (and for example, but not limited to (N2O, NO, NO2, N2O3, N2O4, and N2O5) are reasonably well understood with respect to their solubility in water, and also their reaction with water and other gases such as O2. There is also a great body of literature relating to their formed acids resulting from reactions with water and derived products such as nitrous acid and nitric acid.

[0005] Bowman’s theory provides an understanding for the calculation of NO gas production and is relevant to exhaust gases from combustion, including from furnaces and combustors (for example as used in gas turbines), and is included by reference: Bowman, C. T. Chemistry of Gaseous Pollutant Formation and Destruction, Chapter4 of Fossil Fuel Combustion: A Source Book. Bartok, W. and Sarofim, A. F. editors, John Wiley & Sons, Inc., New York, NY, 1991, and clearly defines the relationship between temperature, pressure and Oxygen and Nitrogen gas concentration and the production of NO. This relationship is expressed as:d[NO1 (in kgMol / m3 / sec) = 1.44x1 O20exp(-69500 / T) [O2]°5[N2]dt T0 5where T is gas temperature in kelvins,t is reaction time in secondsThis theory demonstrates that temperature is a driving producer of NOx during combustion of which approximately 95% is NO.

[0006] There is literature on the required nitrogen levels required by healthy algae to be supplied by nitrogen fertilising agents, not mentioning the direct use of NOx gases and products of NOx gases, nor demonstrating a method of effectively utilizing insoluble NOx gas components in a closed system and the management of consequential acidification of algae growth medium when NOx gases are efficiently utilised and in which algae are typically grown.

[0007] Furthermore, it is accepted that healthy algae requires approximately 7% nitrogen by weight, which places a high commercial impost by way of necessary nitrogen fertiliser in an algae growth system. If for example, urea fertiliser (approximately 47% Nitrogen) was used with costs in excess of USD1000 per tonne, this would imply that 20ML / year of lipid oil extracted at a yield of 30% from algae requires approximately 4,200 Tons / year of nitrogen (approximately 8,900 tonnes of urea) at a cost in excess of USD8 million / year in fertiliser. This represents a significant and problematic cost of approximately 40% (or more) of revenue from biofuel products derived from lipid processing.

[0008] The alternative is to have nitrogen deficiency which affects algal productivity by decreasing photosynthesis, growth rates and longevity. The effects are reported in many studies with the clear implication that considerable nitrogen must be provided to growing algae if lipid oil is to be produced at scale.

[0009] The Applicant’s International Patent Publication Nos. W02023056502, WO20241 68383, and corresponding applications, the contents of which are hereby incorporated herein by reference, each describe a system and method for growing organisms, in particular algae, which may use NOx as a nutrient, and as an agent for flocculation.

[0010] The invention has been developed against the above background.SUMMARY OF INVENTION

[0011] According to a first broad aspect of the present invention, there is provided a system for growing algae comprising:(a) an algae growth and oxygen generation stage comprising:an algae growth medium, said algae growth medium receiving carbon dioxide from a source of carbon dioxide; anda flow path through which algae growth medium flows from a feed end to a harvesting end,(b) a control system for controlling operation of the algae growth and oxygen generation stage,wherein the control system controls dosing of nitrate species into algae growth medium along the flow path.

[0012] In a second broad aspect of the present invention, there is provided a method for growing algae comprising:(a) growing algae in an algae growth medium, the algae growth medium receiving carbon dioxide from a source of carbon dioxide; and(b) flowing algae growth medium from a feed end to a harvesting end of a flow path; and(c) controlling dosing of nitrate species into algae growth medium along the flow path.

[0013] By “nitrate species” is intended any nitrate which acts as a nutrient for algae. The nitrate species is preferably selected from the group consisting of nitrogen acids (e.g. nitric acid, nitrous acid), nitrate salts including ammonium nitrate and potassium nitrate. In some cases, the nitrate species may be generated within the system and dosed into the algae flow path. However, nitrate species may also be sourced independently of the system and dosed into the flow path. Preferably, nitrogen acids, optionally buffered with ammonium nitrate, are dosed in controlled amounts into the flow path to control nitrogen input for algal growth. Nitrate in algae medium solution, which results in (acidic) decreased pH, firstly from nitrogen acid doses and secondly from algae preferentially consuming ammonia, the latter resulting if ammonia solution is introduced as an algae medium pH buffer, or ammonium nitrate salts are introduced as an algae nitrogen feedstock additive, is balanced by algae then consuming nitrates to adjust the pH towards neutrality.

[0014] The nitrate species is preferably intermittently dosed in controlled amounts into the flow path. The nitrate species is also desirably dosed into the flow path at a plurality of points spaced along the flow path.

[0015] Control of dosing of nitrate species into the flow path may be a function of at least one parameter selected from the group consisting of measured algal density and pH of the algae medium at one or more selected points along the flow path and speed of flow of algae growth medium through the flow path.

[0016] Where the nitrate species is acidic in nature, in particular nitric acid, dosing of the nitrate species may be controlled to achieve a selected pH or pH range suitable for the algae being grown. Algae species that can tolerate an acid regime of pH 6 to 7 are preferred, for example. In this regard, the pH of the algae growth medium is desirably controlled to optimise algal growth for the particular algal species selected.

[0017] Related to control of pH is control over conductivity of the algae growth medium. Harvesting of algae requires flocculation and, in preferred embodiments, harvesting is by electro-flocculation which is optimised by controlling the pH and conductivity of algae growth medium when directed to an electro flocculation device. Following harvesting of algae by electro flocculation, the barren algae growth mediummay be used for dosing of nitrate species into the flow path. Other modes of flocculation, for example involving pH control to an acidic or alkaline range dependent on algal species as described in the Applicant’s International Patent Publication WO 2024168383, may be used.

[0018] Preferably, a plurality of light diffusion (LD) devices are disposed in the flow path. LD devices allow transmission of light into algae growth medium and enable a higher depth and volume of algae growth medium than possible without inclusion of LD devices. Desirably, light is transmitted to algae throughout the depth of algae growth medium within the flow path. Light may be transmitted directly from a light source or transmitted by reflection. In preferred embodiments, an LD device may be separated from an adjacent LD device by an intervening partition with algae growth medium caused to circulate through flow path portions defined by surfaces of the LD device and surfaces of the partition. The algae growth medium may be caused to flow around, or through, a bottom portion of the LD device and over an upper surface of the partition. The intervening partitions, which may also be referred to as baffles, increase flow path length, raise algal medium at depth to the surface to allow efficient transfer of gases and allow more efficient use of land to accommodate the system for growing algae.

[0019] The above features of the system and method for growing algae may be applied to an “open” algae growth system, for example one in which algae are grown in a raceway system. By “open” is intended stages and other components having free and open access to the atmosphere. An open algae growth system therefore utilises atmospheric carbon dioxide.

[0020] However, a range of carbon dioxide sources may be employed, optionally in combination, for closed systems including a closed system algae growth and oxygen generation stage and a closed system combustion stage for supplying nutrient containing gas to the closed system algae growth and oxygen generation stage and receiving gas containing oxygen and insoluble NOx from the closed system algae growth and oxygen generation stage. The term “closed” means stages and / or components and / or sub-systems of the system wherein gases should not, and desirably cannot, escape outside of the system as a whole.

[0021] A preferred closed system combustion stage combusts carbonaceous material in an oxygen rich environment at a combustion temperature and pressure promoting generation of an exhaust gas comprising controlled proportions of carbon dioxide and a determined quantity of NOx gases. The exhaust gas typically also contains components including SOx, minerals and carbonic acid though other components may be present. The control system controls operation of the closed system combustion stage to control nutrient input to, and optimise algal growth in, the closed system algae growth and oxygen generation stage.

[0022] In that regard, the exhaust gas from the closed system combustion stage may comprise at least a portion of - if not all of - a feedstock gas for growing algae in the algae growth medium in the above referenced closed system algae growth and oxygen generation stage. NOx from the feedstock gas is then solubilised, in the form of nitrate species as described below, and metabolised by growing algae in the algae growth and oxygen generation stage. As solubilised nitrate species, including NOx, tend to acidify and lower the pH of the algae growth medium, the control system controls pH of the algae growth medium in the flow path as above described to maintain algal viability though some pH stress, i.e. pH away from theoretical optimum for growth, may promote higher lipid density in the cultivated algae. pH of the algae growth medium may be controlled by controlling closed system combustion stage operation as well as nitrate species dosing.

[0023] The generation of oxygen by growing algae makes it convenient and desirable for an offtake or exit gas from the closed algae growth and oxygen generation stage, and comprising carbon dioxide, oxygen and non-solubilised NOx in controlled proportions, to be directed to the closed system combustion stage. Nonsolubilised NOx may dissociate into the same or other NOx species in the closed combustion stage, such dissociation being facilitated by inclusion of at least one corona discharge device. Where, as typical, the exit gas from the closed combustion stage includes NOx and introduced water vapour, the at least one corona discharge device causes precipitation of nitrogen acids, in particular nitric acid. Such nitrogen acids may be produced in excess of an amount required for dosing along the flow path. Excess nitrogen acid, in particular nitric acid, may be directed to chemical production, for example ammonium nitrate production as described below.

[0024] The source of carbon dioxide may include a biomass disintegration system, for example being selected from the group consisting of an anaerobic digestion system, an aerobic digestion system, and a combination of such systems. The systems are desirably closed so that carbon dioxide containing gas composition of exhaust gas from the anaerobic digestion system directed to the algae growth and oxygen generation system; or the gas composition of exhaust gas rich in oxygen from the aerobic digestion system and directed to the combustion system, may be controlled to optimise algae growth. It will be understood that such exhaust gas includes components, including gases, additional to carbon dioxide.

[0025] The source of carbon dioxide may include a closed sugar fermentation system, such as for production of alcohol or beer, from the juice of a fermentable sugar bearing crop such as sugar cane or sorghum, and / or from sugars produced by hydrolysis and saccharification of cellulosic material. The residue following extracting juices, typically in the form of bagasse, may be recovered and treated as described below. Carbon dioxide from fermentation is captured and directed to the algae growth and oxygen generation system. The efficiency of fermentation and production of carbon dioxide may be enhanced with hydrolysis of bagasse, conveniently by nitric acid as generated in the system, and then desirable saccharification into additional sugars.

[0026] Where ammonia is produced, saccharification will carry ammonium nitrate in solution resulting from neutralising nitrogen acids with ammonia in solution after the hydrolysis of bagasse and prior to saccharification and then fermentation will further carry the ammonium nitrate with fermented beer (i.e. an alcohol containing solution), as will filtration and then distillation of ethanol resulting in ammonium nitrate which is separable or extractable, conveniently using evaporation, for example by spray drying.

[0027] Nitric and nitrous acid can be precipitated from the exhaust stream of the corona discharge device contained within the closed system combustion stage and separately stored for use as a nitrate fertiliser, for controlled application to bagasse pretreatment systems and as a reaction agent with ammonia solution to produce additional ammonium nitrate.

[0028] The pH of the algae medium, as modified by intermittent dosing of nitric and nitrous acids in the algae medium flow path, is preferably restored towards pH neutrality by algae consuming nitrates in solution.

[0029] In some embodiments, the system comprises a gas production system for producing a gas or alkaline solution formed by dissolution of said gas in water to blend with the algae growth medium in the flow path. Preferably, the gas production system is an ammonia (NH3) gas or ammonia solution production system and the control system may then control addition of ammonia gas or ammonia solution to the algae growth medium to achieve a determined pH range. Conveniently, the control system controls addition of ammonia and feedstock gas to the algae growth medium to buffer the pH of the algae growth medium. Preferably, nitrogen is primarily supplied to the closed algae growth and oxygen generation stage in the form of nitrates that may be reactively buffered with ammonia species which would, in particular, include ammonia, ammonia in water and ammonium hydroxide.

[0030] A conditioning vessel may be provided for reaction of nitric acid formed from NOX with ammonia to produce in situ a pH neutral salt, such as ammonium nitrate. If ammonium nitrate is selected as nitrate species for dosing, its dosing along the flow path is controlled to avoid nitrate levels reaching toxic levels detrimental to algae growth or lethal to algae due to preferential algal metabolism of ammonium ions. Despite the utility of ammonium nitrate as a nutrient for algae, such toxicity would result if it were dosed at only one end, such as the feed end, of the flow path.

[0031] The closed system algae growth and oxygen generation stage preferably at least includes closed growth vessels in the form of “sealed tent(s)”, and more preferably multi-panelled sealed tent system as described below, for growing waterborne algae, with carbon dioxide and requirements being driven by a required carbon dioxide and nitrogen uptake rate of the algae. Each growth vessel contains a gas space disposed above a volume of liquid algae growth medium. Growth vessels may be kept separate with no communication between gas spaces in adjacent growth vessels, other than as purposefully directed through end panel reticulation. In the case of panels within the preferred multi-panelled tent system integrating a plurality of panels, a gas barrier is desirably provided between each panel to enable the gasspace above the liquid algae growth medium to be closed off from the gas space of adjacent panel(s).

[0032] The sealed tents or panels within the multi-panelled sealed tent(s) are conveniently formed of a flexible material enabling a tent or panel to expand or contract to accommodate volume of gas in a gas space in the multi-panelled tent system. Conveniently, a roof portion of the closed algae growth and oxygen generation stage is configured to rise and fall depending on the volume of gas in the algae growth and oxygen generation stage which may include a mechanism, conveniently a telescopic standoff connected between a base and the roof portion and expandable or contractable for accommodating the movement of the roof portion dependent on fluctuations in volume of gas in the gas space.

[0033] Nitrate species are preferably dosed in controlled amounts into sealed tents or panels comprising the closed algae growth and oxygen generation stage. Panels may be arranged in groups, each group comprising at least one panel. In this case, the controlled amount of nitrate species dosed into each panel is determined with reference to the volume and / or pH of algae growth medium and measured density of algae to meet the nitrogen demand of the algae in each panel. Nitrate species may be dosed to achieve a target algal density or density range in each panel.

[0034] The system preferably includes a carbon dioxide and NOx balancing system for balancing carbon dioxide and NOx delivered by exhaust gases from the “closed combustion” stage with carbon dioxide and NOx requirements in the “closed algae growth and oxygen generation” stage and in particular, for organism growth to produce biomass. Such balancing of carbon dioxide and NOx allows efficient use of the carbonaceous material used in the closed combustion stage while maintaining an appropriate physiological response in the algae. The carbon dioxide and NOx balancing system includes a carbon dioxide and NOx storage means. The need to store NOx produced by the combustion stage is described in detail in the Applicant’s International Publication WO202416838 incorporated herein by reference and not repeated here. The carbon dioxide and NOx balancing system is conveniently included within the above described “sealed tent(s)”.

[0035] Algae may be harvested for processing in harvesting and processing stage(s) to produce a further chemical product, in particular from lipids and proteins contained in the algae, as described below. For example, and preferably, algal lipids from the harvested algae may desirably be processed into a biofuel, such as Biodiesel (a fatty acid methyl [or ethyl] ester), Renewable Diesel (a paraffin) and / or other paraffinic fuels such as Sustainable Aviation Fuel (SAF). A range of further chemical products may be produced using carbon dioxide and nitrates as a feedstock. Algal lipids are in themselves a chemical product though processing of algae is not limited to processing of their algal lipids, other chemical products present within the algae may also be extracted or further processed to a further chemical product.

[0036] The systems described above are advantageously modular. In this way, one or more of the combustion, “algae growth and oxygen generation” stages and associated equipment may be provided as discrete modules which may be replaced with new modules if required to vary capacity, adopt improved technology and / or for maintenance purposes.

[0037] The systems and methods described herein enable algal growth for production of chemical products, in particular biofuels, with a significantly lower cost for nitrogen required by growing algae. At the same time, the methods and systems provide the capacity to scrub a range of chemical components from combustion gases - in particular carbon dioxide, NOx and SOx - while providing the ability to produce valuable chemical products.BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Further features of the system and method for growing algae of the present invention are more fully described in the following description of several non-limiting embodiments thereof. This description is included solely for the purposes of exemplifying the present invention. It should not be understood as a restriction on the broad summary, disclosure or description of the invention as set out above. The description will be made with reference to the accompanying drawings in which:

[0039] Figure 1 is a block diagram schematically illustrating one embodiment of a system for growing algae, producing lipids, ethanol and ammonium nitrate according to one embodiment of the present invention.

[0040] Figure 2 depicts a schematic long section diagram of a “closed algae growth and oxygen generation” stage showing multiple panels within a tent system and an algae flocculation and fertilisation configuration and a relationship to other components of the invention and which may be used in accordance with embodiments of the present invention.

[0041] Figure 3 depicts a schematic cross section of a panel within a multi-panelled sealed tent which may be used in the closed algae growth and oxygen generation stage in accordance with embodiments of the present invention.

[0042] Figure 4 depicts a schematic cross section and long section of an electro flocculation device which may be used in the closed algae growth and oxygen generation stage in accordance with embodiments of the present invention.

[0043] Figure 5 depicts a schematic cross section of a portion of the closed algae growth and oxygen generation stage including light diffusion (LD) devices and adjacent partitions in accordance with embodiments of the present invention.

[0044] Figure 6 depicts one possible relationship between LD device containers of Figure 5 secured to a common footing with adjacent Partitions.

[0045] Figure 7 depicts a schematic layout of devices and adjacent partitions in a tent system in accordance with embodiments of the present invention.

[0046] Figure 8 depicts a schematic diagram showing recirculating gas flow within the tent system of embodiments of the invention.

[0047] Figure 9 depicts a schematic diagram of a telescopic standoff included within panels of the tent system of Figure 7.DEFINITIONS

[0048] The following definitions are provided as general definitions and should in no way limit the scope of the present invention to those terms alone but are put forth for a better understanding of the following description.

[0049] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the invention belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. For the purposes of the present invention, additional terms are defined below. Furthermore, all definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and / or ordinary meanings of the defined terms unless there is doubt as to the meaning of a particular term, in which case the common dictionary definition and / or common usage of the term will prevail.

[0050] For the purposes of the present invention, the following terms are defined below.

[0051] The articles “a” and “an” are used herein to refer to one or to more than one (i.e. to at least one) of the grammatical object of the article. By way of example, "an element" refers to one element or more than one element.

[0052] The term “about” is used herein to refer to quantities that vary by as much as 30%, preferably by as much as 20%, and more preferably by as much as 10% to a reference quantity. The use of the word ‘about’ to qualify a number is merely an express indication that the number is not to be construed as a precise value.

[0053] Throughout this specification, unless the context requires otherwise, the words “comprise”, “comprises” and “comprising” will be understood to imply the inclusion of a stated step or element or group of steps or elements but not the exclusion of any other step or element or group of steps or elements.

[0054] Any one of the terms: “including” or “which includes” or “that includes” as used herein is also an open term that also means including at least the elements / features that follow the term, but not excluding others. Thus, “including” is synonymous with and means “comprising”.

[0055] In the claims, as well as in the summary above and the description below, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” “composed of,” and the like are to be understood to be open-ended, i.e., to mean “including but not limited to”. Only the transitional phrases “consisting of’ and “consisting essentially of” alone shall be closed or semiclosed transitional phrases, respectively.

[0056] Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, preferred methods and materials are described. It will be appreciated that the methods, apparatus and systems described herein may be implemented in a variety of ways and for a variety of purposes. The description here is by way of example only.

[0057] As used herein, the term “exemplary” is used in the sense of providing examples, as opposed to indicating quality. That is, an “exemplary embodiment” is an embodiment provided as an example, as opposed to necessarily being an embodiment of exemplary quality for example serving as a desirable model or representing the best of its kind.

[0058] Also, various inventive concepts may be embodied as one or more methods, of which an example has been provided. The acts performed as part of the method may be ordered in any suitable way. Accordingly, embodiments may be constructed in which acts are performed in an order different than illustrated, which may include performing some acts simultaneously, even though shown as sequential acts in illustrative embodiments.

[0059] The phrase “and / or”, as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and / or” should be construed in the samefashion, i.e., “one or more” of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the “and / or” clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to “A and / or B”, when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.

[0060] As used herein in the specification and in the claims, “or” should be understood to have the same meaning as “and / or” as defined above. For example, when separating items in a list, “or” or “and / or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of’ or “exactly one of,” or, when used in the claims, “consisting of” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used herein shall only be interpreted as indicating exclusive alternatives (i.e. “one or the other but not both”) when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of.” “Consisting essentially of,” when used in the claims, shall have its ordinary meaning as used in the field of patent law.

[0061] As used herein in the specification and in the claims, the phrase “at least one”, in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, “at least one of A and B” (or, equivalently, “at least one of A or B,” or, equivalently “at least one of A and / or B”) can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); inanother embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.

[0062] For the purpose of this specification, where method steps are described in sequence, the sequence does not necessarily mean that the steps are to be carried out in chronological order in that sequence, unless there is no other logical manner of interpreting the sequence.DESCRIPTION OF PREFERRED EMBODIMENTS

[0063] Referring to Figure 1 there is shown a block diagram of a system 100 for generating and using carbon dioxide and NOx gases to produce lipids from algae (118) that enables the production of biofuels, in particular Biodiesel (a fatty acid methyl [or ethyl] ester), and / or Renewable Diesel (a paraffin) and / or other paraffinic fuels such as Sustainable Aviation Fuel. The system 100 comprises a “closed system combustion stage” 38 containing one or more “closed system combustors orfurnace / s” that generates an exhaust gas carbon dioxide, NOx and other gases 44 for consumption in the “closed system algae growth and oxygen generation” stage 10. Embodiments include generation of exhaust gas from any combustion process whether or not conducted in a combustor for example a gas turbine or reciprocating engine, furnace or other combustion device.

[0064] The closed system combustion stage 38 and closed algae growth and oxygen generation stage 10 co-operate to optimise algal growth and harvesting in block 11 under the control of an electronic control system, such as a SCADA process control system.Closed System Combustion Stage

[0065] The closed system combustion stage 38 combusts carbonaceous material to produce at least carbon dioxide and NOx containing gases. “Carbonaceous material” is a material which is rich in, or yields, carbon. It includes, for example, plant material, bagasse and / or other fuels (such as coal, biomethane, hydrocarbon gases,paraffins or other fossil fuels). Carbonaceous material may be selected from a range of fuels with the carbon dioxide and NOx containing exhaust gas stream from a combustor burning the fuel being captured (as a closed system) and directed to the algae growth and oxygen generation stage 10 described later and also a closed system allowing controlled usage of the captured exhaust gas stream as an algal nutrient stream. Growth of algae using such exhaust gas stream offers an option for scrubbing out carbon monoxide, NOx, SOx, minerals, acids (in particular carbonic acid), water vapour and other components of combustor exhaust gas.

[0066] In the embodiment that also includes the use of a feedstock 2 containing sugar, ethanol 206 thence ethylene can be produced through a serialised process train 1 ,40,291 ,300,205 and optionally containing stages 260,262,271 ,280 for the production of biofuels and plastics, in particular paraffin oil products and polyethylene products from ethylene.

[0067] Figure 1 is an embodiment where carbonaceous material 4 is produced from a feedstock, and in particular, sweet sorghum 2 is crushed 1 to produce bagasse 4 and sorghum juice 66.

[0068] The intent is that unprocessed bagasse 4 will find its way to the anaerobic digestor 200, either directly from the crusher 1 or through a serialised process train 260,262,271 ,280,40,291 that breaks down the cellulosic material in the bagasse into sugars that can be fermented 40, with the un-saccharificated component of the bagasse 4 filtered 291 and directed to the anaerobic digestor 200.

[0069] The carbonaceous material 4 may also be burnt in a furnace (or other combustor) to produce an exhaust gas and the option of steam power generation. The exhaust gas comprises carbon dioxide and further components selected from the group consisting of carbon monoxide, NOx, SOx, minerals, gases found in air and acid gases such as carbonic acid gas. Such components are nutrients for algae and are consumed in the closed algae growth and oxygen generation stage 10.

[0070] Alternatively, and as per the embodiment shown in Figure 1 , the carbonaceous material 4 may be directed to an anaerobic digestor 200, either directly or via a saccharification process train described below, and which is used to producea constituency of gases 6 that contain methane, carbon dioxide and ammonia, and where these three main constituents are separated in an optional gas washer 203, preferably a pressure vessel that spays the gases with water under pressure, to separate methane 7 from a water solution of carbon dioxide 44B and ammonia 272, to then feed the combustor with enriched methane gas 7 and remnant gases not separated into solution by the gas washer 203.

[0071] In the embodiment, the saccharification chain 260,262,271 ,280 relies on flaking 260 the bagasse 4 into, preferably about 1 mm, flakes 261 and then applying hydrolysis pretreating 262 to the flakes 261 and accompanying biomass, in a warm acidic bath conveniently using nitric acid 263 which can be obtained from the corona discharge device 210. The hydrolysis pretreated flake solution 270 is returned to a neutral pH solution 271 with the application of ammonia solution 272 obtained from the anaerobic digestor 200 or optional gas washer 203 to produce hydrolysate containing ammonium nitrate 273.

[0072] It is this hydrolysate 273 that is then saccharificated 280 with enzymes 281 to produce sugars from the cellulosic materials contained in the hydrolysate 273. Typical enzymes and only as an example, include alpha amylase enzyme.

[0073] The solution of sugars, ammonium nitrate and biomass 282, can then be fermented 40 to produce a beer 290 that includes ammonium nitrate.

[0074] The beer 290 is filtered 291 to remove vinaigrette, lignin material from bagasse and other biowaste 292, which is directed to the anaerobic digestor 200. Filtration can include for example, micro filtration, ultra filtration and reverse osmosis.

[0075] If Reverse Osmosis is utilised (and which will require prefiltration) the beer 293 is then a concentrated solution of ethanol and ammonium nitrate. The ethanol 55 can be distilled 300 from the beer 293 and passed through an optional vapour permeation system 205 to produce high purity ethanol 206.

[0076] The remaining solution containing ammonium nitrate 301 and after distillation 300 can be processed through a precipitator 310 which evaporates off the water to produce ammonium nitrate product 311.

[0077] The ammonia solution 272 produced by the anaerobic digester 200 and separated by the optional gas washer 203, may be used toa. neutralise 271 nitric acids in solution with hydrolysis pretreated bagasse 270 and after pretreatment to form ammonium nitrate in solution together with hydrolysis pretreated bagasse 273; and / or b. blend ammonia solution 272 with nitric acids 263 to form ammonium nitrate solution delivered to either filtration system 291 , distillation system 300, or precipitator 310 (paths not shown) for further downstream precipitation of ammonium nitrate 311 .A byproduct of the anaerobic digestor 200 is a digestate 201 , that if buried, then carbon storage is established and will provide a carbon credit against the process of system 100.

[0078] Also optional to system 100 is the use of algae remnant waste 13 obtained after lipid extraction and high in nitrogen that can be aerobically digested 204 to further concentrate the biomass into nitrogen containing digestate fertiliser 202.

[0079] If the digestate fertiliser 202 is buried (as a commercially viable fertiliser) then carbon storage is established and will provide a carbon credit against the process of system 100.

[0080] The system 100 comprises a “Closed System Combustor” within the Closed System Combustion stage 38 containing one or more Closed System Combustors that generates an exhaust gas carbon dioxide, NOx and other gases 44 for consumption in algal growth and harvesting block 11 . These gases can optionally pass through an inline corona discharge device 210 to produce and extract NOx gasses in water vapour as nitrogen containing acids for further processing into nitrogen fertilisers (nitrates) for algae growth. Embodiments include generation of exhaust gas from any combustion process whether or not conducted in a combustor (by example, a gas turbine as depicted in Figure 1 ), furnace, reciprocating engine or other carbon dioxide generation system. The combustor 38 is preferably connected to an electric power generation system to produce power 209 for system 100.

[0081] The combustion stage 38 and other carbon dioxide generation systems 203,204,40 and algal growth and harvesting block 11 are controlled by the above referenced control system.Closed System Combustion Stage

[0082] A plurality of closed system combustors 38 may be provided. In other embodiments, power station off gas may be used rather than combustors.

[0083] Each closed system combustor 38 may operate with a feed gas of about 40% to 90% oxygen and 0% to 10% carbon dioxide and nitrogen containing gas to produce a high concentration of CO2 and a determined quantity of NOx gases to the algae growth and oxygen generation stage 10.

[0084] In the case of a combustor designed for lower concentrations of oxygen in the gas mix, it may be expedient to recirculate exhaust gases from the combustor into input gases of the combustor. This is common practice in gas turbine technology to reduce the oxygen inlet content, with the intent to reduce the amount of NOx produced. In this invention however, this same technology could be utilised to reduce the amount of oxygen in the feed gas to provide acceptable operating temperatures for the combustor. The recirculated exhaust gas can be blended with the high concentration oxygen supply from algal growth and harvesting block 11 and, in particular, the algae growth and oxygen generation stage 10. Such a modification may implement an industry standard cogeneration configuration to draw heat from the exhaust of the combustor, as well as optional heat exchangers to condition the temperature of blended gases for input into the inlet of the combustor 38.

[0085] The closed system combustor 38 is dimensioned to handle the supplied carbonaceous material, and is a closed system preferably intolerant to gas leakage.

[0086] The closed system combustor 38 burns the carbonaceous material 4 or methane 7 (or other fuel type depending on the embodiment) in an oxidant gas 39 sourced from algal growth and harvesting block 11 to produce high grade CO2 and NOx gases 44 that are captured within the closed system combustor 38 and passed through a heat exchanger and optional corona discharge device 210 for delivery ofCC and NOx feedstock 44 and nitrate species 263 to the, likewise closed system, algae growth and oxygen generation stage 10 via the algae flocculation and nitrate species preparation stage 137, i.e. algal growth and harvesting block 11.

[0087] Furthermore, and optionally, the corona discharge device 210 produces nitrogen acids 263, in particular nitric acid, as nitrogen nutrient required by algae in the algae growth and oxygen generation stage 10 and for supply of acid to a hydrolysis pretreatment system 262 to produce pretreated bagasse 270 for optional saccharification 280 of hydrolysate 273.

[0088] Oxidant gas (37, thence 39) used for combustion, contains a mixture of oxygen in major proportion and carbon dioxide in minor proportion and nitrogen gases including NOx gas, is sourced from algal growth and harvesting block 11 . Carbon dioxide and NOx in the gas mixture from algal growth and harvesting block 11 is the unconsumed proportion of the CO2 gas and NOx produced during combustion together with oxygen and nitrogen in the mixture, the oxygen substantially produced by growth of algae in the algae growth and oxygen generation stage 10 and described below.

[0089] Air is only preferred in small quantities in combustion due to its high concentration of nitrogen gas which, if not converted to NOx, is a dilutant to the desired high concentrations of oxygen and carbon dioxide and takes up carbon dioxide storage space and consumes gas transfer energy, i.e. energy required for pumping the gas. The preferred closed system combustion stage 38 therefore reduces economically detrimental and combustion physics issues which have arisen with use of boiler flue gases as a source of carbon dioxide for algal growth.

[0090] The combustor 38 burns the carbonaceous material 4 or 7 or other fuel type depending on the embodiment in a gas 37, in the optional absence of aerobic digestor 204, or from a gas 39 containing high concentrations of oxygen and the remainder carbon dioxide and NOx sourced from algal growth in algal growth and harvesting block 11 , together with a minor proportion of nitrogen (preferably air). This in-turn enables the production of high concentrations of CO244 and reconstituted NOx gases to be supplied to algal growth and harvesting block 11 and, in the case of CO2 and NOx 44 from the combustion stage 38 and then optional corona discharge device 210and passed through a heat exchanger to be cooled before supplying the gas as a nutrient for algae in algal growth and harvesting block 11 . In this regard, exhaust gas from combustion gas is hot and its temperature must be reduced to avoid destruction of algae in algal growth and harvesting block 11 and more desirably at a temperature within that optimal for algal growth.

[0091] In the case of carbonaceous material 4 containing moisture (such as bagasse or wood) the exhaust gases 44 from the combustion stage 38, will also contain condensed water and other condensates and water vapour. In the case of the carbonaceous material to the combustor 38 being coal or mineral diesel, the exhaust gases 44 are likely to contain sulphur containing compounds and minerals commonly found in those carbonaceous materials, but lower concentrations of moisture. Furthermore, because there is a likelihood of water contained in plant fuel, such as for example, bagasse, there is the possibility of carbonic acid contained in the combustion exhaust gas formed by the reaction of CO2 with water under high temperature in the combustion stage. Likewise, if coal was used as a combustion fuel, there is a likelihood of sulphur containing acids and with some carbonic acid. Also present may be other acid gases that will contribute to the acidity of the algae medium when the combustion exhaust gas is percolated through the algae medium in the algae growth and oxygen generation stage as described below. Further, sulphur and other species present in combustion exhaust gas are nutrients that can be utilised in algae growth.

[0092] Air is preferably not used as a combustion gas though it may be introduced, as required, as a source of nitrogen to form NOx as determined by the control system and described further below. The algae growth and oxygen generation stage 10 operates more efficiently using high concentrations of CO2 feedstock, than gases resulting from the combustion of bagasse 4 in air (containing principally oxygen and nitrogen). With respect to air, and though a small amount of air is required to produce NOx, CO2 storage within algal growth and harvesting block 11 will be adversely impacted if gases containing carbon dioxide and oxygen, but also containing about 78% by volume nitrogen, are utilised. That would simply poach space with little benefit to the purpose of the undissolved CO2 and NOx gas flow 32A as shown in Figure 8 and the utilization of gas storage 32 (Figures 2 and 3).

[0093] Carbon dioxide is, in the most part, inert in the combustion stage 38 combustion exhaust gas, though some carbonic acid is likely to be formed, and to a much lesser extent cyanide which undergoes hydrolysis to form ammonia and a small amount of formate. The carbon dioxide passes through that system to enrich the carbon dioxide as produced by the combustion stage 38 to be delivered back to algal growth and harvesting block 11 as a nutrient for algal growth. If air was used as a feedstock to the combustion stage 38, the nitrogen (78% by volume) would, in a lower than preferred temperature environment, oxidise to produce some NOx gases but would in the main be also inert, both to the combustion stage 38 and algal growth and harvesting block 11 . However, by configuring the combustor 38 to burn at sufficiently high temperatures and with high oxygen concentrations, optionally under pressure, a controlled amount of nitrogen 13 can be introduced to produce NOx gas to be processed into a nitrogen fertiliser for the algae medium. Notwithstanding that air (i.e.78% nitrogen) would, not promote high combustion temperatures and in the main, occupy valuable storage space and is therefore not preferred as a component of the combustion gas of the combustion stage 38.

[0094] Ultimately, all nitrogen originating from small amounts of air added to the combustion stage (and to a lesser extent, that nitrogen contained in the carbonaceous material used for combustion) will, by reprocessing remnant nitrogen gasses and undissolved NOx by dissociation and recirculation as enabled by the closed system gas communication between algal growth and harvesting block 11 and the closed combustion stage 38, be absorbed by the algae growth medium.

[0095] In combustion stage 38, composition of exhaust gases 44, and correspondingly the feedstock gases and nitrogen acids delivered to the algae growth medium and, in turn, the pH of the algae growth medium, is conveniently controlled by controlling a plurality of the following:(a) concentration of gases such as oxygen, carbon dioxide, NOx and nitrogen to the combustion stage 38;(b) throughput rate of exit gas from the algal growth and harvesting block 11 to the closed combustion stage 38;(c) combustion or flame temperature;(d) gas pressure during combustion;(e) where introduced, throughput rate of nitrogen to the combustion stage 38;(f) throughput rate of carbonaceous material to the combustion stage 38;(g) quantities and pH of nitrate species controllably dosed into the flow path within the algae growth and oxygen generation stage 10; and(h) quantities and pH of alkaline solution controllably dosed into the flow path within the algae growth and oxygen generation stage 10.

[0096] Desirably, the closed system combustion stage 38 operate(s) continuously, preferably year-round, to provide carbon dioxide and NOx as feedstocks to the algae growth and harvesting block 11. A consistent or constant feed of carbon dioxide and NOx from the combustion stage 38 to the algal growth and harvesting stage 11 is preferable if algal growth is to be maintained at a rate matched with the required production rate of the chemical product, for example a biofuel. The generation of CO2 and NOx within the combustion stage 38 can be controlled to meet algal uptake or demand by controlling the supply of suitable carbonaceous material as fuel to the combustion stage 38. Bum rate in a combustor 38 may also be controlled with a target set for carbon dioxide production.

[0097] The combustion stage 38 can operate at varying bum rates by varying the throughput of carbonaceous fuel, enabling flexible and intermittent operation. The carbon dioxide, oxygen and NOx gases balancing system may, as above described, include storage 32 of carbon dioxide, oxygen and NOx gases in case the combustion stage 38 generates at any one-time, an imbalance of carbon dioxide and NOx gases against that required to maintain the carbon dioxide and nitrogen uptake rate of the algae, and likewise, the algae producing less oxygen in the absence of light (i.e. at night) than required by the combustion stage 38.

[0098] A heat exchanger / s is a component of the closed system combustion stage 38 and is used to remove heat from the CO2 and NOx containing exhaust gas fromthat combustion stage 38, suitable for delivery of the gas 44 at desired temperature, as described above, to the algal growth and harvesting stage 11 . Furthermore, heat reticulated as combustion gas or steam from the combustion stage 38 can be used via additional heat exchangers to:a. power a steam turbine electrical generator 190; and / orb. warm diced bagasse / acid solution 261 for hydrolysis pretreatment 262; and / orc. distillation 300 of ethanol solution 293 produced in fermentation 40;and / ord. heating ethanol 55 for vapour permeation purification system 205;and / ore. distillation 310 of ammonium nitrate precipitate 311 from solution, resulting from ammonia 272 neutralizing 271 acidic (nitric acid) pretreated bagasse 270; and / orf. to preheat algal lipids in downstream processing.Closed System Algae Growth And Oxygen Generation Stage 10

[0099] “Closed System Algae Growth And Oxygen Generation” stage 10 involves one or typically a plurality of vessels, in this embodiment in the form of a “Closed Multi-Panelled Sealed Tent System” 12, for growing algae, the number of panels of which is determined by available CO2 and nitrogen nutrient supply to stage 10 amongst other factors. These vessels may be termed “closed growth vessels”. As algae grow, they move through panels of tent system 12 (Figure 8) in a flow of liquid algae growth medium along a tortuous flow path through the algae growth and oxygen generation stage 10.

[0100] The Applicant’s International Patent Publication Nos. WO W02023056502, WO20241 68383, and corresponding applications, the contents of which are herebyincorporated herein by reference, describe the algal growth and oxygen generation stage 10 of a system and method for growing organisms, in particular algae, which may use NOx as a nutrient, and as an agent for flocculation. Algae are grown in a liquid algae growth medium substantially comprising water with a source of carbon dioxide. Other nutrients may be supplied from combustion system 38 or other stages of the system 100 as described here and, if necessary, as known in the art of growing algae.

[0101] Contained in the tent system 12 are one or more Light Diffusion Device(s) 18B (herein “LD Devices”) in the form of translucent sealed containers as shown in Figures 3 and 5 and each separated by a “Partition(s)” 18A. As shown, the LD devices 18B are aligned orthogonal to the flow of liquid algae growth medium 14.

[0102] LD Device(s) 18B capture light 84 above or about the surface 14A of the liquid algae growth medium 14 and diffuse that light through water 81 contained in the LD Device(s) 18B separate from, and unhindered by, the typical turbidity of algae growth medium 14. The water 81 is preferably doped with light reflective material to enhance light diffusion.

[0103] The light reflective material in the clarified water 81 may, for example, be a combination of a Florescent Brightener and a dye. A pink dye is preferable as it provides some blue spectrum with the red spectrum at the exclusion of green. Green spectrum is emitted by algae and not useful to photosynthesis.

[0104] The water 81 in each LD Device 18B is preferably initially sterilised and clarified for example using membrane technology and is conveniently permanently stored in each LD Device 18B. The water 81 provides sufficient hydrostatic pressure to counter the hydrostatic pressure of the liquid algae growth medium 14, and assist the LD Device(s) 18B to keep their shape.

[0105] The LD Device(s) 18B are sealed at each lateral end with a water and airproof seal, to permanently store water in the LD Device(s) 18B. Air and water in the LD Device(s) 18B can be injected / removed using a hose(s) that is sealed and fixed into the end(s) of the LD Device(s) 18B.

[0106] The shape of the LD Device(s) 18B is maintained by injecting some air 80 in each LD Device 18B, that air 80 occupies the space between the surface of the water 81 and the top of the LD Device(s) 18B providing it with buoyancy.

[0107] The use of air 80 in LD Device(s) 18B is preferred to CO2 (which is used in the CO2 storage system 32), as air is not as soluble as CO2 and avoids the buildup of carbonic acid in the water 81 .

[0108] Ducts 91 (Figure 6), in the form of a series of perforations, are inserted into the lower support walls of the LD Device(s) 18B at a height that is between the top of the sand ballast 87A and below the container portion of the LD Device(s) 18B. The container portion holds water 81 which is preferably doped with light reflective material. Sufficient ducts 91 are inserted so as to minimize any impact on the quantities of flow of algae growth medium underneath the container component of the LD Device(s) 18B. It may be necessary to thicken the LD Device(s) 18B walls in the region of the ducts 91 to establish structural integrity of the LD Device(s) 18B.

[0109] Figure 6 shows a combination of LD Device 18B I Partition / s 18A all fixed or braced (welded to) to a common footing 240 and weighted with ballast 87,87A. The number of pairs of LD Device 18B and Partition 18B fixed to the common footing 240 is a design and installation consideration. An LD device 18B and adjacent partition 18A may be braced together. One or more LD device / s 18B and partition / s 18A may, in embodiments, be fabricated as a single unit.

[0110] Exemplary to the invention, and without limitation, if the LD Device(s) 18B are constructed with about 3mm UV protected translucent plastic material (such as for example: PE (PolyEthylene), PET (Polyethylene Terephthalate), PMMA (PolyMethyl MethAcrylate) or other suitable plastics that are commercially available), then the LD Device(s) 18B will have sufficient rigidity, and allow the containers to stand supported by the algae medium.

[0111] Each LD Device 18B container is buoyant (see Figure 5) resulting from air 80 captured at the top of the container component of the LD Device(s) 18B. The degree of buoyancy of each LD device 18B is controllable to optimise light capture and distribution.

[0112] Preferably, the base of the container component is located above the common footing 240 (or optional sand ballast 87A covering the common footing 240) and preferably at a distance of 5cm to 15cm above the floor 160 or ballast 87A, to allow the movement of water through ducts 91 underneath the LD Device(s) 18B container portion and thereby connecting algae growth passages 86 on either side of an LD Device 18B, where an algae growth passage 86 (Figure 5) is that space between an LD Device(s) 18B and Partition(s) 18A. Ducts 91 and algae growth passages 86 comprise a single “flow path” along which liquid algae growth medium and growing algae flow at a controlled flow rate through tent system 12 as described below. Such flow path for the liquid algae growth medium 14 encourages the transfer of CO2 and oxygen between liquid algae growth medium 14 and the gas storage space 32 above the liquid algae growth medium 14 in each panel.

[0113] The dimensions of the LD Device(s) 18B, and in particular width at the surface of the liquid algae growth medium 14, are selected as a function of available light energy. Sunlight can be measured in moles of photons and without wishing to be bound by theory, typical noonday sunlight in Northern Australia is about 1 ,700 pmol.photons / m2 / sec. However, the optimum irradiance for a wide range of algae species is typically between 120 to 400 pmol.photons / m2 / sec which is a small fraction of the sun’s radiation.

[0114] Therefore an average quantity of light 85 emitted from the sides of the LD Device(s) 18B can be calculated, assuming an absorption rating for the combination of translucent ceiling sheet 20 and LD Device(s) 18B, applied to the expected sunlight radiation energy, and when the red and / or blue Photosynthetically Active Radiation (“PAR”) spectrums are separated (for use by the algae), an average irradiation energy 85 from the sides of the LD Device(s) 18B can be computed to assist in determining the dimensions, both width and depth, of the LD Device(s) 18B as well as the spacing between an LD Device 18B and an adjacent partition 18A.

[0115] The extent of the light pathway 85 from the sides of the LD Device(s) 18B through the liquid algae growth medium 14 can be approximated using a linear interpolation of algae density using as a basis the penetration of light limited to, for example, 5cm at 1 ,5gm / Litre (as described in Raeisossadati (2020) Luminescent solarconcentrators to increase microalgal biomass productivity; PhD Thesis; Murdoch University, WA, Page 62 and 80 and the contents of which are hereby incorporated herein by reference). This enables a calculation of the separation between LD Device(s) 18B and Partitions 18A in the tent system 12 commensurate with average algal density at the location of a selected LD Device 18B and adjacent partition 18A. By way of example, if the algae density was 1 gm / L would infer a maximum travel distance of light to be about 7.50cm and would represent the design distance between LD device 18B and Partition 18A.

[0116] A control system doses nitrate species along the flow path of algae growth medium feeding growing algae through the tent system 12, the flow path being a tortuous one as defined by LD devices 18B and partitions 18A. In the following embodiment, the selected nitrate species is nitric acid 263 readily produced by the above described corona discharge device 210.

[0117] By way of example, and not to limit this invention, the volume of about 0.026% concentration nitric acid (about pH 5.38) added in measured doses to each panel in the tent system 12 is sufficient to meet the about 7% by weight nitrogen demand of new algae growth and used to create the following table at paragraph

[0125] ,

[0118] This solution of 0.026% concentration nitric acid 31 may be obtained as an offtake from the electro flocculation device 137, (though alternate sources of nitric acid - including nitric acid generated at corona discharge device 210 - are acceptable) would be low in algae concentration but with sufficient nitric acid that enables achievement of an acceptable or optimised conductivity of algae growth medium in electro flocculation device 137.

[0119] Because such nitric acid 31 from the electro flocculation device 137 therefore has low concentration of algae, being only about 0% to 20% of the algae flocculated from the Far End panel 165 of the tent system 12, it will dilute the algae concentration of each panel 161 -165, but given the flow rate of algae medium through each panel 161 -165 and the duration of the algae in the panel, there is sufficient duration toreestablish the algae medium 14, in this table, to about an algae concentration of 1.01 mg / L.

[0120] Supply Tanks 241 (one or more) contain nitric acid 31 for supply to each group of panels (being one or more panels), and which through the control system, supply measured (and even intermittent) doses of nitric acid 31 to each group of panels (being one or more panels). In other embodiments, the nitric acid may be replaced by other nitrates subject to their influence on conductivity (enabling easier algae harvesting at electro flocculation device 137).

[0121] In other embodiments, the supply tanks 241 may be omitted, providing that the control system can supply each group of panels with measured doses of nitric acid, or alternative suitable nitrate species, directly from the electro flocculation device 137 of from a centralised nitrate solution storage tank.

[0122] Typical daily doses of nitric acid 31 are tabulated in “Volume of added Nitric Acid Solution (m3)” of the below table and when blended, in substantially lower volume having pH of 5.34, with the nitrate depleted medium of the panel, will provide an algae growth regime within each panel of about pH 6.34 to pH 7.0. Certain species of algae (such as Chlorella Vulgaris) typically have a flocculation efficiency of about 20% in an agitated environment at a pH 6.34, and thus the LD Device cleansing system described in the Applicant’s incorporated by reference International Patent Publication Nos. WO W02023056502, WO2024168383, and corresponding applications, is useful to this system.

[0123] The appropriate growth rate to use for various species of algae can be contentious, but for this example 92mg / L / day is used. Also, the following table utilises a 1 day growth period for algae in each panel and with 20 panels is 20 days of culture.

[0124] The following table assumes 40cm wide LD Devices in about 1 ,7m water and arranged in 6.5m wide panels within the tent system 12 as schematically shown in Figure 7, Diagram A.

[0125] Top row of the table is a “Far End Panel” 165. It is this “Panel Volume” that contains the volume of algae medium to be flocculated each day. 2ndRow has 102m3of algae medium at 1.01 mg / L recycled back to first panel “Near End Panel” as algae seed.

[0126] The above example table demonstrates that by introducing measured amounts of nitric acid 31 , consistent with the expected growth rate of algae and hencenitrogen requirement, it is possible to maintain a consistent design width between LD Device 18B and Partition 18A, in this case 7.39cm.

[0127] Thus, all panels have eleven LD Device 18B I Partition 18A pairs across each panel. A gas barrier is provided to enable the gas space above the liquid algae growth medium 14 in one panel to be closed off from the gas space of adjacent panels. This serves two purposes. First, circulation of gases is forced along each panel (along an elongated as well as tortuous flow path) to extend the gas flow route within the tent system 12 for efficient transfer of gas components (notably CO2, NOxand O2) between the algae growth medium and the circulating gas (exhaust gas from closed system combustion stage 38 as described above). Second, such barrier mitigates against a leak in the tent system 12 at the location of the particular panel 161-165. Gas flow between adjacent barrier separated panels is controllable through the use of suitable piped / gas reticulation between panels with suitable valve arrangements. One embodiment of gas barrier is described below.

[0128] Algae seed in sufficient concentration is drawn from either:a. one of the far end 165 panels and provided to a near end panel 161 ;and / orb. the offtake from the electro flocculation 137 system,but because of the significant volume difference between panels, only about a tenth (102m3) of the available volume containing algal seed is needed to be delivered to the near end panel 161. The remaining algal seed volume is distributed along the flow path of the algal growth and oxygen generation stage 10 under the prorating scheme described above.

[0129] Because the length of the Far Panels 162-165 may be considered excessive, then it is possible to section the panels using section brace(s) 59A (as shown in Figure 7 Diagrams A and B). For example, if a 20m panel section length was desired, then the same approximate length of ceiling sheet 20 can be joined to a subsequent length of ceiling sheet 20 in continuation of the panel by bracing the two ceiling sheets 20between a clamping strip 56 and a base plate 57 that is fixed to the panel section brace 59A which in turn, is mounted on a floor plate 58.

[0130] This then allows the LD Devices 18B and Partitions 18A to be manufactured in manageable lengths suitable for a panel section.

[0131] The above example is schematically shown in Figure 7 Diagram A where five panels 161 , 162, 163, 164, and 165 of the tent system 12 are schematically shown, demonstrating a consistent layout for each panel, of LD devices 18B and partitions 18A where the panel length increases with the cumulative addition of measured “Volume of Added Nitric Acid Solution (m3)”.

[0132] If, in the above example, the movement of algae is controlled with an inflow of liquid medium 14 into the tent system 12 through the inlet 24 (Figure 2) of about 4.8 m3 / hr (a combination of 102m3 / day from a far end panel and 13.1 m3 / day of measured nitric acid solution at pH 5.38) together with measured inflows of nitric acid 31 at subsequent panels and an outflow of 1160m3 / day at the outlet 26, it will take 21 days to traverse the tent system 12 (one day per panel and 21 panels).

[0133] This implies that the liquid algae growth medium flow rate over a partition 18A is about 4.2 cm / minute assuming a 6cm deep aperture of water flowing over the partition 18A and is consistent for all partitions in all panels.

[0134] Because of the slow flow speed of the liquid algae growth medium of 4.2cm / minute, very little energy is lost in the water flow as turbulence.

[0135] The flow of liquid algae growth medium, described in Figure 5, is enabled by LD Device(s) 18B container component(s) desirably located at a sufficient distance from the floor 160, but secured by its construction to a common footing 240; that construction enabling LD Device(s) 18B containing ducts 91 to allow the movement of water underneath the container component(s) of the LD Device(s) 18B, and with the tops of the LD Device(s) 18B above the algae growth medium water level 14A forcing that water movement, whereas the tops of partition(s) 18A are below the algae medium water level 14A allowing the algae growth medium to flow over the top of the partitions 18A. Partition(s) 18A are fixed to a common footing 240 residing on the floorof the “multi-panelled sealed tent” 12. The common footing 240 fixes a LD Device 18B and partition 18A pair, or groups of pairs.

[0136] Thereby, as an alternate pattern of LD Devices 18B and partitions 18A, the flow of liquid algae growth medium is sequentially directed over the partitions 18A, then vertically down the side of the LD Devices 18B, to flow beneath the LD Device container component(s) 18B and then vertically up the side of the LD Devices 18B to then flow over the next partition 18A.

[0137] Figure 7 Diagram C schematically shows how each panel 161 -165 is joined on its long side with the sealed ceiling sheets 20 of adjacent panels clasped between the clamping strip 56 and the base plate 57 that is fixed to the standoff 59 which in turn, is mounted on the floor plate 58. The floor plate 58 is secured either by mounting the common footing 240 on top of the floor plate 58 or by using tethers that are welded to the base 160 together with tie down straps. Sand, screed and / or gravel 87, can also be optionally used and layered on the floor plate 58 and / or common footing 240 to provide ballast and stability against wind forces, to assist in securing the base plate 57 and provide thermal ballast to assist in maintaining a more constant water temperature and controllable algal growth in the tent system 12.“Open System Algae Growth”

[0138] This same configuration of LD Devices 18B and Partitions 18A can also be applied to an “Open System Algae Growth” system without the need for a ceiling sheet (seal 20) allowing open access of the algae medium to the atmosphere. This then eliminates the need for panels, supporting standoffs 59,59A, clamping strips 56, base plates 57 and floor plates 58 and therefore structurally becomes a continuum of LD Devices 18B and Partitions 18A in the flow of the algae medium.

[0139] In this case of an open system algae growth system, because of the reduction of available carbon dioxide to a concentration commensurate with the earth’s atmosphere of 0.04% CO2 w:w, the assumed algal growth rate of 92mg / L / day would not apply, but a growth rate consistent with the environment and other available nutrients, would be accounted for in defining the dimensions of the open system algae growth system.

[0140] Other design considerations such as nitric acid feed rates along the flow path, target algae concentration and therefore separation between each LD Device 18B and partition 18A, conductivity of algae medium for flocculation and implementation of electro flocculation are also taken into account.Gas Volume Variation in Tent System 12

[0141] The standoff 59 in tent system 12 is structured to provide the above referenced gas barrier between adjacent panels by hanging a barrier plate 60 from the base plate 57 to below the water level 14A along the length of the panel. This embodiment is schematically shown in Figure 7, Diagram D. In this way, if a leak or damage occurred in the ceiling sheet 20, then the panel, say panel 162, in which the leak occurred can be shut down and excluded from the gas regime of the other panels 161 , 163, 164 and 165 of tent system 12. Carbon dioxide / oxygen gas flow 32A (shown in Figure 8) between panels 161-165 and hence the entire tent system 12, is enabled through connecting pipes and / or ducts connecting each panel with its adjacent panels, for example panel 162 has adjacent panels 161 and 163. The connecting pipes are valved to control gas flow and also enable the connection of downstream panels, isolation of panels and rerouting of gas flow in the case of a leak or damage to a panel’s seal or ceiling sheet 20. As Figure 8 shows, the direction of carbon dioxide / oxygen gas flow 32A between panels is directed perpendicular to the direction of water (i.e. algae growth medium) flow.

[0142] This routing of gas between panels may be optionally configured to include groups of panels, where a group of panels has the gas barrier plate 60, partially removed at one end of a panel to allow gas to traverse that one panel and then flow into the next, and the gas returned in the adjacent (next) panel. This eliminates piping and / or ducting and valves 167,166 (Figure 8) at that one end of the adjacent panels enabling gas flow along one panel and back via the next panel. This may be repeated optionally to provide groups of panels and allows the tent system 12 to be configured such that the amount of construction of pipes and / or ducts connecting panels is reduced and optionally the pipe and / or duct components are only on one side of the tent system 12.

[0143] The barrier plate 60 (Figure 7 D) between panels also hinders the reverse dilution of oxygen gas back through the panels against the desired direction of gas flow assisting in producing an ever increasing proportion of oxygen in the CO2 and oxygen storage 32 as the gas progresses from panel to panel of the tent system 12, as directed by the gas reticulation used to connect adjacent panels of the tent system 12. Thus, the feed gas 43,44,44B has a high proportion of CO2, whereas the exit gas 37 flowing through offtake 36 has a high proportion of oxygen, which then can be fed to the closed system combustion stage 38.

[0144] It should be noted that the gas flow may be reversed, depending on design preference from “Far End” to “Near End” or “Near End” to “Far End” of tent system 12.

[0145] Gas reticulation or circulation within the tent system 12 is diagrammatically presented in Figure 8 showing a subset (161 to 165) of all panels, wherein CO2 gas is injected 166 into a panel preferably as far as possible from the gas outlet pipe 167 of that panel. In this embodiment, panels are not grouped as described above with gas barrier plates 60 partially removed, but with Figure 8 simply showing an example of gas reticulation through panels of the tent system 12. The capture of oxygen is effected in each panel (say for example panel 162) and therefore the gas outlet pipe 167 will contain that proportion of oxygen accumulated from proceeding panels together with gases contained within that panel 162 and which is then injected 166 into the next panel (say for example panel 161 ). Thus the proportion of oxygen steadily increases as the gas flow 32A passes from one panel to the next (refer to Figure 8), until the Oxygen: CO2 gas mixture is captured at the gas offtake 36.

[0146] The Valves on Gas Outlet 167 from a panel, the Gas Inlet 166 into the next panel and the Gas Bypass 168 to direct gas past a panel, are preferably configured to establish a gas flow that routes the gas over the entire length of each panel with the alternate valve sets at 169 closed to enforce that flow as presented in Figure 8, Valves 166,167,168 and valve sets 169 can be reconfigured for gas flow to bypass a panel to enable maintenance of the tent system 12 or to otherwise achieve a desired gas flow pattern. Again, this illustration simply provides an example of gas reticulation through panels of the tent system 12. Irrespective, the result is an extended and elongated route for gas flow over the algae growth medium 14 and higher time for carbon dioxideor other gas (in particular NOx) absorption by the algae growth medium. Conversely, more time is also provided for oxygen produced by respiring algae to diffuse out of the algae growth medium.

[0147] The embodiment described by Figure 1 increases the sources of supply of CO2 and NOx in comparison to the Applicant’s systems as described in its International Patent Publication Nos. W02023056502, WO2024168383, namely adding CO2 from fermentation 43, CO2 and NOx from combustion 44, CO2 from anaerobic digestion 44b and O2 and CO2 from aerobic digestion 39 as shown in Figure 1.

[0148] A large number of tent systems 12, potentially many hundreds of tent systems 12 could be included dependent on factors such as biofuel production targets and / or exhaust gas output from a combustor or power station or where the system (100) is used to scrub NOx and other acid gases from that exhaust gas.Telescopic Standoffs

[0149] Advantageously, the standoffs 59,59A of tent system 12 are telescopic so that the flexible ceiling 20 may lift and fall with varying amounts of gas contained in the panels.

[0150] Figure 9 depicts a rod 221 and piston 220 configuration contained within a bore 231 that allows for vertical extension of the standoffs 59,59A.

[0151] Rod 221 and piston 220 are attached 222 to the clamping configuration 223 that clamps to the barrier plate 60 and the bore 231 is also clamped 230 to the floor plate 58, either to a barrier plate fixed to the floor plate 58 (to stop sand ballast drift) or directly to the floor plate 58.

[0152] The telescopic standoffs 59,59A of tent system 12 may be vertically inverted depending on design requirements.

[0153] Clamping block 232 is clamped together by “attaching plates” (not shown) that both secure either side of the clamping block together and also with the use of “attaching plates” (not shown) secure the clamping block 232 to the bore 231 .

[0154] The clamping block impedes over extension of the piston 220 and piston rod 221 beyond the physical extent of the bore 231 . At the same time, the clamping block enables the complete assembly of the support 59, 59A at construction.

[0155] Dimensions of the clamping block 232 and bore 231 are consistent with each other. Piston 220 is dimensionally consistent with internal bore 231 dimensions. Piston Rod 221 is consistent with internal dimensions of clamping block 232. Separation of clamping plates 223 is consistent with thickness of barrier 60 whilst separation of clamping plate 230 is consistent with the thickness of a barrier plate that may be optionally fixed to the floor plate 58 (to stop sand ballast drift), notwithstanding the clamping plate(s) 230 may be attached directly to the floor plate 58. The length of the internal bore 231 and piston rod void in clamping block 232 is consistent with the length of the piston 220 and piston rod 221 .

[0156] Bore 231 has pressure equalization and sufficient for movement dampening either by hole(s) that allows external fluids (to bore 231 ) to penetrate via the hole(s) into the internal bore or preferentially by a channel running the length of the internal bore 231 and inserted into the wall(s) of the internal bore 231 .Ammonia Production

[0157] The embodiment described in Figure 1 utilises an anaerobic digestor 200 to produce ammonia, methane and carbon dioxide as the main constituents of gases as described by Buswell’s formula and is included by reference: A.M. Buswell, H.F. Mueller, Mechanism of methane fermentation, Ind. Eng. Chem., 44 (1952) 550-552. The ammonia is highly soluble and captured in solution within the anaerobic digestor.

[0158] It is this solution that can be blended with nitric acid, which is produced in excess to that required as an algal nutrient as above described, to form ammonium nitrate and then processed using preferably cogeneration heat from the combustor to precipitate the ammonium nitrate which may be sold as a fertiliser.

[0159] This production of ammonia, by anaerobic digestion, is far less energy intensive than the Haber-Bosch Process, but notwithstanding, given that system 100 is optionally capable of producing hydrogen 208 as a by-product of electrolysis withinthe electro flocculation process described above, then an expedient method of preparing the hydrogen for transport is to convert it to ammonia. In which case, a process to produce ammonia but not limited to the Haber-Bosch Process would be required to fix the hydrogen 208 to nitrogen.Algae Separation and Nitrate Species Solution Preparation

[0160] Algae are separated or harvested by electro flocculation device 137 (as shown in Figure 4). Electro flocculation requires a highly electrically conductive algae growth medium, which is facilitated by the above described introduction of nitric acid 31 into the flow path 18A, 18B, 86, 91 (Figures 5 and 6). In preferred embodiments, as described above, nitric acid is selected to achieve sufficient conductivity of the liquid algae growth medium on entering the electro flocculation device 137.

[0161] By way of example and not limitation, a pH of 5.38 created using nitric acid 263 together with 0.08% NaCI (freshwater) concentration in the algae growth medium 14 undergoing electro flocculation, will provide a conductivity of about 2,300 uSiemens / cm enabling a 2amp current with a voltage of about (and without limitation) 35V to operate across 2.3m of algae medium utilising two 2m * 30cm area plate electrodes 250.

[0162] Salts other than NaCI which in small doses are not harmful to algae growth, can also be used to enhance the conductivity of the algae growth medium 14.

[0163] The deflocculated nitric acid solution 31 is then distributed in measured doses to each of the groups of panels 161 -165 (each group being one or more panels).

[0164] If necessary, a recirculation system 147 may be included to direct gases including CO2 and non-solubilised NOx to the electro flocculation device 137 to aerate the algae growth medium using a porous plate 145 and assist collection of flocculated algae.

[0165] The electro flocculation device 137 contains electrodes 250 which are placed each side of a channel. Algae growth medium 14 containing algae passes through the channel and past the oppositely charged electrodes 250. The algae medium 14is here aerated using gases from the sources of supply of CO2 and NOx from 44 and recirculated gases 147 which lift the flocculated algae for harvest by skimming.

[0166] Skimming uses weighted plates 144 that are hinged to a chain rotating between ends of the electro flocculation device, to deposit algae in collection tray 149.

[0167] Gases from the electro flocculation device 137 exit via outlet 148 and are then recirculated through the tent system 12.

[0168] Because of the voltage required to achieve sufficient current between the two electrodes 250 to provide commercial grade flocculation, there will be electrolysis of water into constituent parts of hydrogen 208 and oxygen.

[0169] The hydrogen 208 can be captured and separated from the other gases that exit via outlet 148 from the electro flocculation device 137.

[0170] An optional partition may be installed between the roof of electro flocculation device 137 and below the algae medium surface of electro flocculation device 137 for separating the airspace above the anode and cathode electrodes to assist separation of hydrogen. However, this would double the amount of mechanical equipment required to skim the algae medium and add complexity to maintenance, and is not included in preferred embodiments.

[0171] Because the flow of gas into tent system 12 is only about 5m3 / min to 10m3 / min it is convenient to extract the hydrogen as a byproduct using columnar separation. Hydrogen is less dense than the other gases (about 0.083 kg / m3at 1 atm & 20DegC) compared to the density of combined gases (1.34kg / m3) from the recirculation system 147 and which are percolated through the electro flocculation device 137 to aerate the algae growth medium and assist harvesting. The air mix is passed into a column and the buoyant hydrogen 208 bled from the top of the column. Gases lower in the column are delivered to tent system 12.Injection of Carbon Dioxide and NOx into the Tent System 12

[0172] Carbon dioxide and NOx gases 44 that pass through the electro flocculation device 137 together with carbon dioxide gases 43,44B are directed via a manifold totent system 12 using valve(s) 34 at or about the “far end” of the tent system 12 and via the “far end” plate(s) 16 (Figure 2).

[0173] The direction of carbon dioxide 43,44,44B flow from the “far end” plate 16 to the “near end” plate 17 (and by doing so, becomes enriched with oxygen 37), though preferred, is not limiting, as there may be occasions in which the direction of carbon dioxide 43,44,44B flow may need to be from “near end” plate 17 to “far end” plate 16.Processing of Algae

[0174] Harvesting and processing of algae to biofuel may generally conveniently proceed as described in the Applicant’s International Patent Publication No. WO W02023056502 incorporated herein by reference and not repeated here. However, the electro flocculation of algae by electro flocculation device 137 potentially reduces the need for power consuming centrifugal separation during harvesting prior to processing of algae to produce biofuels.

[0175] The key step in processing of algae is extraction of algal lipids or lipid oils which are then converted to biofuel. A potential benefit in providing algae with sufficient nitrogen (for example, algae may contain 7% nitrogen dry weight) using the method and system as described above is that the remnant components of the algae cells, with lipid oils removed, have an increased measure of nitrogen by weight, and can serve as a nitrogen fertiliser for agriculture. For example, and only by way of illustration, if algae contain 7% nitrogen and 30% lipid oil, removal of the lipid oils will leave about 10% by weight nitrogen in the remnant algae. That the algae is harvested from a nitrate containing solution (the liquid algae growth medium), in particular a nitric acid containing solution, and once the pH neutralised with ammonia will also increase the amounts of nitrogen in and on the algae remnant. This is not as bountiful as urea (a common fertiliser containing about 47% nitrogen) but it is a byproduct of the invention and the nitrogen, in part, is organically bound to the algae remnant as distinct to highly soluble urea (which has water runoff issues) and so is a more persistent nitrogen product which can be used for good purpose as a nitrogen fertiliser in the agricultural industry. Furthermore, if the algae remnant is composted using aerobic digestion, nitrogen will remain in the compost whilst carbonaceous material is consumed by aerobic bacteria to produce mainly CO2 and water. It is thereforepredicted that the composted algae product may contain about 18% nitrogen. Preferably the CO2 digestion product 39 would be beneficially returned to the algae growth and harvesting block 11 via the combustion stage 38.

[0176] It will be appreciated by those skilled in the art that variations and modifications to the systems and methods for growing algae as described herein will be apparent without departing from the spirit and scope thereof. The variations and modifications as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of the invention as herein set forth.

Claims

CLAIMS:

1. A system for growing algae comprising:(a) an algae growth and oxygen generation stage comprising:an algae growth medium, said algae growth medium receiving carbon dioxide from a source of carbon dioxide; anda flow path through which algae growth medium flows from a feed end to a harvesting end; and(b) a control system for controlling operation of the algae growth and oxygen generation stage,wherein the control system controls dosing of a nitrate species into algae growth medium along the flow path.

2. The system of claim 1 , wherein the control system implements intermittent dosing of the nitrate species in controlled amounts into the flow path.

3. The system of claim 1 or 2, wherein the control system doses nitrate species into the flow path at a plurality of points spaced along the flow path.

4. The system of any one of the preceding claims, wherein control over dosing of nitrate species into the flow path is a function of at least one parameter selected from the group consisting of measured algal density at one or more selected points along the flow path and speed of flow of algae growth medium through the flow path.

5. The system of any one of the preceding claims, wherein the nitrate species is a nitrogen acid.

6. The system of claim 5, wherein the nitrate species comprises a nitrogen acid buffered with ammonium nitrate.

7. The system of any one of the preceding claims, wherein said algae growth stage includes at least one light diffusion device arranged within the flow path.

8. The system of claim 7, comprising a plurality of light diffusion devices, each light diffusion device being separated by an intervening partition, the flow pathincluding flow path portions defined by surfaces of the light diffusion devices and surfaces of the intervening partitions.

9. The system of any one of the preceding claims, wherein the control system controls pH of the algae growth medium in a determined range.

10. The system of any one of the preceding claims, wherein the algae growth stage comprises an electro flocculation device for harvesting algae.

11. The system of claim 10, wherein the control system controls the conductivity of algae growth medium directed to the electro flocculation device by control over the dosing of nitrate species into said algae growth medium.

12. The system of claim 10 or 11 , wherein said a solution containing said nitrate species is produced primarily by a corona discharge device.

13. The system of any one of claims 10 to 12, wherein a solution containing nitrate species is also established in the electro flocculation device during harvesting of algae.

14. The system of claim 12 or 13, wherein said nitrate species is nitric acid.

15. The system of any one of the preceding claims, wherein the algae growth system is an open system with carbon dioxide being supplied from the atmosphere.

16. The system of any one of claims 1 to 14, wherein the source of carbon dioxide is a closed system combustion stage for combusting carbonaceous material in an oxygen rich environment at a combustion temperature and pressure promoting generation of an exhaust gas comprising controlled proportions of carbon dioxide and a determined quantity of NOx gases, the exhaust gas being directed to the algae growth and oxygen generation stage as a closed system.

17. The system of claim 16, wherein said closed system combustion stage comprises a corona discharge device to produce a solution containing nitrate species, preferably nitric acid.

18. The system of claim 17, wherein said exhaust gas is humidified to precipitate nitrogen acids, optionally by moistening said exhaust gas with water vapour sprays.

19. The system of any one of claims 16 to 18, wherein said exhaust gas comprises at least a portion of a feedstock gas for growing algae in the algae growth medium in which NOx species are solubilised in the form of said nitrate species and metabolised by growing algae, an exit gas from the closed algae growth system comprising carbon dioxide, oxygen and non-solubilised NOx in controlled proportions being directed to the closed system combustion stage for dissociation into the same or other NOx species.

20. The system of any one of the preceding claims 1 to 14 or 16 to 19, wherein said source of carbon dioxide includes a biomass disintegration system.

21. The system of claim 20, wherein said biomass disintegration system is selected from the group consisting of an anaerobic digestion system, an aerobic digestion system and a combination of said systems.

22. The system of any one of claims 1 to 14 or 16 to 19, further comprising a gas production system for producing a gas or alkaline solution formed by dissolution of said gas in water to blend with the algae growth medium in the flow path.

23. The system of claim 22, wherein the gas production system is an ammonia (NH3) gas or ammonia solution production system.

24. The system of claim 23, wherein an anaerobic digestion system is the ammonia (NH3) gas production system.

25. The system of claim 23 or 24, wherein the control system controls addition of ammonia gas or ammonia solution to the algae growth medium to achieve a determined pH range.

26. The system of any one of claims 23 to 25, comprising a conditioning vessel for reacting nitric acid containing solution generated in the system, optionally prior or subsequent to an electro flocculation device, with ammonia to produce a soluble ammonium nitrate.Tl. The system of any one of claims 1 to 14 or 16 to 26, wherein said source of carbon dioxide includes a closed fermentation system for fermenting juice extracted from a sugar bearing crop.

28. The system of claim 27, wherein remnant cellulosic material is obtained during juice extraction, and reduced in particle size for hydrolysis.

29. The system of claim 28, wherein hydrolysis of cellulosic material occurs in a nitrogen acid solution produced in the system, said solution being subsequently neutralised with ammonia to form ammonium nitrate in solution with hydrolysate.

30. The system of claim 29, wherein the cellulosic material is hydrolysed and saccharificated to provide a sugar containing ammonium nitrate solution and therefore additional sugars for the closed fermentation system.

31. The system of claim 30, wherein said source of carbon dioxide includes a closed fermentation system for fermenting sugars from a solution containing ammonium nitrate.

32. The system of claim 31 , wherein ammonium nitrate in said sugar containing solution is separable as an ammonium nitrate by-product.

33. The system of any one of claims 1 to 14 or 16 to 32, wherein the algae growth and oxygen generation stage comprises a multi-panelled sealed tent system comprising a plurality of panels, each panel including a gas space disposed above a volume of liquid algae growth medium.

34. The system of claim 33, wherein a gas barrier is provided between each panel to enable the gas space above the liquid algae growth medium of one panel to be closed off from the gas space of adjacent panel(s).

35. The system of claim 34, wherein a gas space of one panel is connected with the gas space of an adjacent panel through a connecting pipe or duct including a control valve, controllable by the control system, for controlling gas flow through said connecting pipe or duct.

36. The system of any one of claims 33 to 35, wherein each panel is formed of a flexible material enabling a roof portion of a panel to expand or contract to accommodate volume of gas in a gas space within the multi-panelled tent system.

37. The system of claim 36, wherein each panel comprises a telescopic stand off connected between a base and the roof portion and expandable or retractable for accommodating the movement of the roof portion dependent on fluctuations in volume of gas in the gas space.

38. The system of any one of claims 33 to 37, wherein the controlled amount of nitrate species dosed into each panel is determined with reference to the volume and pH of algae growth medium and measured density of algae to meet the nitrogen demand of the algae in each panel.

39. The system of claim 38, wherein nitrate species is dosed to achieve a target algae density or algae density range in each panel.

40. The system of any one of the preceding claims, comprising a processing stage for producing a biofuel from harvested algae.

41. The system of claim 12, wherein said electro flocculation device produces hydrogen.

42. A method for growing algae comprising:(a) growing algae in an algae growth medium, said algae growth medium receiving carbon dioxide from a source of carbon dioxide;(b) flowing algae growth medium from a feed end to a harvesting end of a flow path; and(c) controlling dosing of nitrate species into algae growth medium along the flow path.

43. The method of claim 42, comprising harvesting algae by electro-flocculation at said harvesting end.

44. The method of claim 42 or 43, comprising processing harvested algae to produce a biofuel.

45. The method of any one of claims 42 to 44, wherein the source of carbon dioxide is an exhaust gas from a closed system combustion stage, said exhaust gas comprising controlled proportions of carbon dioxide and a determined quantity of NOx gases.

46. The method of claim 45, further comprising producing nitric acid from said exhaust gas by corona discharge.

47. The method of any one of claims 42 to 46, wherein said source of carbon dioxide comprises carbon dioxide generated by fermenting juice extracted from a sugar bearing crop748. The method of claim 47, where remnant cellulosic material is obtained during juice extraction, and reduced in particle size for hydrolysis.

49. The method of claim 48, as dependent from claim 47, comprising hydrolysing said cellulosic material by said nitric acid to form a hydrolysate cellulosic material.

50. The method of claim 49, comprising producing ammonia and reacting said ammonia with nitric acid to produce ammonium nitrate in solution with said hydrolysate cellulosic material.

51. The method of claim 50, comprising saccharificating hydrolysate cellulosic material present in said ammonium nitrate containing solution to form a sugar containing ammonium nitrate solution.

52. The method of claim 51 , comprising fermenting said sugar containing ammonium nitrate solution.

53. The method of any one of claims 50 to 52, comprising producing ammonia by anaerobic digestion.

54. The method of any one of the claims 50 to 53 where ammonium nitrate is extracted from a solution containing ethanol.

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