Classifications

• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
  • C12P5/00—Preparation of hydrocarbons or halogenated hydrocarbons
  • C12P5/02—Preparation of hydrocarbons or halogenated hydrocarbons acyclic
  • C12P5/023—Methane
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
  • C12N1/00—Microorganisms, e.g. protozoa; Compositions thereof; Processes of propagating, maintaining or preserving microorganisms or compositions thereof; Processes of preparing or isolating a composition containing a microorganism; Culture media therefor
  • C12N1/20—Bacteria; Culture media therefor
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
  • C12P21/00—Preparation of peptides or proteins
  • C12P21/02—Preparation of peptides or proteins having a known sequence of two or more amino acids, e.g. glutathione
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
  • C12P7/00—Preparation of oxygen-containing organic compounds
  • C12P7/02—Preparation of oxygen-containing organic compounds containing a hydroxy group
  • C12P7/04—Preparation of oxygen-containing organic compounds containing a hydroxy group acyclic
  • C12P7/06—Ethanol, i.e. non-beverage
  • C12P7/065—Ethanol, i.e. non-beverage with microorganisms other than yeasts
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
  • C12P7/00—Preparation of oxygen-containing organic compounds
  • C12P7/62—Carboxylic acid esters
  • C12P7/625—Polyesters of hydroxy carboxylic acids
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
  • C12P7/00—Preparation of oxygen-containing organic compounds
  • C12P7/64—Fats; Fatty oils; Ester-type waxes; Higher fatty acids, i.e. having at least seven carbon atoms in an unbroken chain bound to a carboxyl group; Oxidised oils or fats
  • C12P7/6436—Fatty acid esters
  • C12P7/649—Biodiesel, i.e. fatty acid alkyl esters
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12R—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES C12C - C12Q, RELATING TO MICROORGANISMS
  • C12R2001/00—Microorganisms ; Processes using microorganisms
  • C12R2001/01—Bacteria or Actinomycetales ; using bacteria or Actinomycetales
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E50/00—Technologies for the production of fuel of non-fossil origin
  • Y02E50/30—Fuel from waste, e.g. synthetic alcohol or diesel
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/10—Process efficiency
  • Y02P20/133—Renewable energy sources, e.g. sunlight
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/50—Improvements relating to the production of bulk chemicals
  • Y02P20/582—Recycling of unreacted starting or intermediate materials

Definitions

• renewable energy sources In view of the decreasing reserves of fossil fuels and environmental awareness of global warming and carbon dioxide release, renewable energy sources are moving to the centre of attention. To date, renewable energy sources, i.e. energy from natural resources such as sunlight, wind, rain, tides and geothermal heat, cover about 13% of the global energy demand. Taking into consideration the criteria of sustainability and for achieving the targets of the Kyoto Protocol, it is indispensable to further expand the use of renewable energies. While most of the energy is consumed by a minority of the world's population, the energy demand of developing and emerging countries is increasing rapidly. At the same time, resources of fossil fuels are decreasing. Thus, energy prices will increase significantly, likely along with social and political conflicts, destruction of the environment and global warming. Beside the importance of fossil oil as energy source, it is also an important and essential resource for other industries such as chemistry and pharmaceutical industry (-10% of the fossil oil). In the future, a new basis for most of the products might be required.
• Methane (CH 4 ) would have the characteristics of an ideal energy carrier: it is storable and a well-developed infrastructure is already available. However, burning methane from fossil- fuel sources increases the C0 2 release and will deplete in the foreseeable future. Thus, it would be highly desirable to provide a closed CO2 cycle by fixing CO2 in a bioprocess, i.e. to use CO2 from a renewable source or the atmosphere, yielding a product which can be readily used. Such a product is methane as the main constituent of natural gas. Its content in natural gas varies between 70% and 99%. Methane can be directly produced from carbon dioxide and hydrogen either chemically (chemical methanation or also simply denoted as methanation) or biologically (methanogenesis or biological methanation). The general reaction equation is CO+3H 2 -> CH 4 + H 2 0 in biological methanation or
• the chemical process is called Sabatier reaction or Sabatier process. Also denoted as “methanation” or “chemical methanation”. This reaction is not to be mixed up with biological methanation (see above).
• This reaction requires hydrogen and carbon dioxide, elevated temperatures and pressure, and a transition metal catalyst. More effectively, nickel or ruthenium on aluminum oxide are used as catalysts.
• This process has a good turnover rate, although disadvantages are, for example, a low selectivity, e.g. resulting in side reactions at lower temperatures, the susceptibility of the catalyst to impurities and the high energy demand for heat and pressure all of which reduce the overall process economy.
• the biological conversion of CO and C0 2 and H 2 into methane by methanogenic microorganisms is considered to be a much better alternative.
• the biological pathway is also known as methanogenesis or biological methanation.
• Methanogenic microorganisms are capable of methanogenesis or biological methanation which is a form of anaerobic respiration. Using those methanogenic microorganisms, the reactions C0 2 +4H 2 ⁇ CH 4 +2H 2 0 and CO+3H 2 ⁇ CH 4 + H 2 0 take place at relatively moderate temperatures, the reaction system is robust with a good impurity tolerance and has a high selectivity even at normal pressure.
• biogas has a methane content of between 50% and maximal 70%, the rest consists mainly of carbon dioxide, water vapour and hydrogen sulphide.
• Biogas already has an application in combined heat power plants which generate both heat and electricity, although it may also be upgraded to be used as natural gas.
• hydrogen sulphide gas, water vapour and carbon dioxide may have to be separated from biogas to increase the methane content.
• the methane evolution rate (MER) is a key parameter for an economically feasible methane production.
• the volumetric productivity is calculated from equation (1):
• volumetric productivity [mmol-L ⁇ h 1 ] (biomass concentration [g-L 1 ])- (specific methane production rate [mmol-g ⁇ h 1 ]) (1)
• the "specific methane production rate" [mmol-g " 1 -h "1 ] denotes the amount of methane [mmol] produced per gram of methanogenic microorganism (biomass) [g] per hour [h].
• the cell concentration should be as high as possible in the method and in the reaction vessel of the invention due to the fact that the cells, i.e. the biomass of methanogenic microorganisms, principally function as a catalyst for converting hydrogen and carbon dioxide into methane.
• methane educts such as CO and C0 2 should not be used for unnecessary biomass production.
• the volumetric productivity considers the size of the reactor vessel and therefore directly the investment and energy costs for a production plant. Hence, it is desired to optimise the methane yield with respect to space and time used in the process in order to keep investment costs low and optimally use energy and resource input. It can be stated that in general the volumetric productivity should be as high as possible. While MER may be at least 150 mmolcH4 ' L "1 ⁇ h "1 in a feasible process, in a typical methanogenesis or biological methanation process MER is at least in the range from 750 to 1500 mmolcH4 ' L "1 ⁇ h "1 .
• the focus is on methane production and the biomass, i.e. the methanogenic microorganisms, act as catalysts of this methanogenesis or biological methanation process.
• the biomass inside the reaction vessel should be maintained at the level considered suitable for this purpose as excess biomass production, means a loss of raw material which might otherwise be used for producing methane.
• the amount of disposable biomass is unnecessarily increased.
• carbon dioxide is the gaseous carbon containing educt for the conversion reaction to methane.
• carbon dioxide is also required for the production of biomass.
• part of the carbon dioxide which may be used for the production of methane is instead used for biomass production.
• the inventors of the present invention have surprisingly found out that the ratio of the feed rate of a phosphorous containing compound into the reaction vessel to the biomass production rate of the microorganism (R(F p hos P horous/r x )) being used for product formation is such a key process parameter.
• this ratio allows to fine-tune educt consumption by the microorganisms.
• microorganisms allows to switch the microorganisms from a gas-limited physiologic state (provision of gaseous compound is the limiting factor) to a liquid-limited physiological state (phosphorous containing compound is the limiting factor) and vice versa.
• gas-limited physiologic state provision of gaseous compound is the limiting factor
• liquid-limited physiological state phosphorous containing compound is the limiting factor
• the parameter R(F p hos P horous/r x ) is the ratio of phosphorous that has to be provided for maintaining a desired growth rate with respect to varying bioprocess conditions and/or operational modes.
• this parameter is set below a defined value the physiologic state in the bioprocess switches to a liquid limited and controlled state in which the maximum specific methane productivity of a given hydrogenotrophic methanogen can be exploited or controlled to a desired value. If set higher than a threshold value at about 0.0505 mol p hos P hate ⁇ molcarbon "1 the bioprocess goes back to its natural gas limited state where biomass growth is almost only limited by gaseous compound transfer.
• process mineral feeds such as the feed of the phosphorous containing compound
• process effluents osmolality and mineral composition are also as a consequence reduced giving the possibility to be controlled according to optional water treatment steps following the method according to the present invention.
• the liquid limited state allows decoupling of the natural coupling of biomass concentration and dilution rate in contrast to gas limited cultures.
• the decoupling benefits from the fact that the limiting compound is phosphorous and therefore not essentially required for maintaining the catalytic activity.
• the method can be applied to other essential mineral elements, i.e. essential compounds or chemical compounds, which allow the same decoupling of biomass production and product production as presented with phosphorous on Methanothermobacter marbugensis.
• the feeding ratio of a certain essential compound or substrate in proportion to the C-molar biomass growth can be fairly well predicted if desired based on the elementary composition normalized to a C-mol of a given (microbial) biomass, microorganism, microorganism strain or cell culture.
• Gas limited continuous bioprocesses show a different behavior compared with bioprocesses limited by a substrate supplemented with a liquid feed (Schill et al., 1996).
• the dependency of product and biomass formation as function of the dilution rate is found to be significantly different.
• the main differences with liquid limited bioprocesses can be summarized by a great stability for product formation rate in a broad dilution rate range.
• an exponential increase of biomass concentration at decreased dilution rate is found until limitation or inhibition occurs.
• biomass concentration tends to be very high because of a low wash-out.
• liquid substrates containing process nutrients need to be fed in a proportionally correct amount compared to biomass growth requirements, to maintain a stable catalytic activity. If a mineral or trace compound required in the multi-step enzymatic reactions is depleted, the enzymes activities are lost and methane formation stops.
• the parameter R(F p hos P horous/r x ) allows decoupling methane formation and biomass growth which is particularly important in
• a phosphorous containing compound is suitable as limiting factor which may be used to limit biomass production depending on the experimenter ' s needs while not affecting the production of the carbon containing product, such as methane, since phosphorous is a DNA building block and as such required for biomass production but not for producing a carbon containing product from a gaseous carbon containing educt which preferably does not contain phosphorous itself.
• the present invention provides a method for producing a carbon containing product from a gaseous carbon containing educt using microorganisms in a reaction vessel comprising the steps of
• step b) applying a feed rate of a phosphorous containing compound into the reaction vessel (F p hos P horous) so that the ratio of the feed rate of the phosphorous containing compound into the reaction vessel to the biomass production rate determined in step a) (R(F p hosphorous/r x )) is in the range of 0.001 to 0.5 mol p hos P horous ⁇ mo on "1 , preferably in the range of 0.005 to 0.3 mol p hos P horous ⁇ molcarbon "1 , more preferably in the range of 0.02 to 0.15 mol p hos P horous ⁇ molcarbon "1 .
• the ratio of the feed rate of phosphorous (F p hos P horous) into the reaction vessel to the biomass production rate of the microorganisms inside the reaction vessel (r x ) R(F p hos P horou s/r x ) can be used to control, i.e. decrease and increase and keep at a desired constant rate, the biomass production rate at high methane production rates.
• the present invention provides a process based technical measure which enables a person skilled in the art control the biomass production (rate) without loss in methane conversion/evolution rate.
• This technical measure is provided by a feed rate of a phosphorous containing compound into the reaction vessel (F p hos P horous) so that the ratio of the feed rate of the phosphorous containing compound into the reaction vessel to the biomass production rate of the microorganisms
• R(F p hos P horous/r x )) is in the range of 0.001 to 0.5 mol p hos P horous ⁇ molcarbon "1 , preferably in the range of 0.005 to 0.3 mol p hos P horous ⁇ molcarbon "1 , more preferably in the range of
• a ratio R Of 0.0505 molphosphate ⁇ molcarbon "1 Or R Of 0.0505 molphosphorous ⁇ molcarbon "1 of feed rate of the phosphorous containing compound into the reaction vessel to the biomass production rate of the microorganisms may be considered as the threshold value above which value the microorganisms are in a gas limited state and below which value the microorganisms are in a liquid limited state. Basically this means that in a liquid limited state, the microorganisms are limited with respect to the DNA building block phosphorous and thus biomass production is limited to the extent the experimenter limits the phosphorous supply, while the production of the carbon containing product, e.g.
• methane is high.
• microorganisms grow, i.e. biomass is produced due to a rather non-limited amount of phosphorous, while the production of the carbon containing product, e.g. methane, is also high.
• a higher amount of the phosphorous containing compound is introduced into the reaction vessel which allows growth of the microorganisms.
• this does not significantly influence the specific production of the carbon containing product as long as R is in the range from 0.001 tO 0.5 mol p hos P horous ' molcarbon "1 .
• the inventors have further found out that the possibility to control, i.e. increase, decrease or keep constant, the biomass production as long as the ratio R of the feed rate of the phosphorous containing compound into the reaction vessel to the biomass production rate (R(F p hos P horous/r x )) is in the range of 0.001 to 0.5 mol p hos P horous ⁇ molcarbon "1 is not only applicable to methods wherein methane is the carbon containing product being produced from carbon dioxide as the gaseous carbon containing educt but in general to all methods for producing a carbon containing product from a gaseous carbon containing educt using microorganisms in a reaction vessel since phosphorous as DNA building block is required for biomass production in all microorganisms and may thus be used as a control parameter for biomass production in all those microorganisms which consume a gaseous educt for product formation to switch between gas and liquid limited state.
• the ranges of 0.001 to 0.5 mol p hos P horous ⁇ molcarbon "1 , preferably in the range of 0.005 to 0.3 mol p hos P horous ⁇ molcarbon "1 , more preferably in the range of 0.02 to 0.15 mol p hos P horous ⁇ molcarbon "1 are also applicable to other microorganisms as due to similar genome lengths of microorganisms, an equal amount of phosphorous is required for equal biomass production.
• the method of the invention is generally applicable as a feed forward strategy to control biomass growth r x and exploit maximum specific productivity of carbon containing products of microorganisms consuming a gaseous carbon containing educt.
• the invention provides a method for producing a carbon containing product from a gaseous carbon containing educt using microorganisms in a reaction vessel comprising the steps of a) determining the biomass production rate of the microorganisms inside the reaction vessel (r x ), and b) applying a feed rate of a phosphorous containing compound into the reaction vessel (F p hos P horous) so that the ratio of the feed rate of the phosphorous containing compound into the reaction vessel to the biomass production rate determined in step a) (R(F p hosphorous/r x )) is in the range of 0.001 to 0.5 mol p hos P horous ⁇ mo on "1 , optionally in the range of 0.005 to 0.3 mol p hos P horous ⁇ molcarbon "1 or in the range of 0.02 tO 0.15 mol p hos P horous ' molcarbon "1 .
• R(F p hos P hate/r x ) is in the range of 0.03 to 0.11 mol p hos P hate ⁇ mO lcarbon ⁇
• R(F p hos P hate/r x ) is in the range of 0.001 to 0.05 mol p hos P hate ⁇ molcarbon "1 , preferably in the range of 0.02 to 0.04 mol p hos P horous ⁇ mO lcarbon ⁇
• R(F p hos P hate/r x ) is in the range of 0.051 to 0.3 mol p hos P hate ⁇ molcarbon "1 , preferably in the range of 0.06 to 0.15 mol p hos P h orous ' molcarbon ⁇
• R(F p hos P hate/r x ) is in the range of 0.001 to 0.05 mol p hos P hate ⁇ molcarbon "1 , preferably in the range of 0.02 to 0.04 mol p hos P hate ⁇ mO lcarbon ⁇
• R(F p hos P hate/r x ) is in the range of 0.051 to 0.3 mol p hos P hate ⁇ molcarbon "1 , preferably in the range of 0.06 to 0.15 mol p hos P hate ⁇ molcarbon "1 .
• R(F p hos P horous/r x ) is in the range of 0.001 to 0.05 mol p hos P horous ⁇ molcarbon "1 , preferably in the range of 0.02 to 0.04 mol p hos P horous ⁇ mO lcarbon ⁇
• R(F p hos P horous/r x ) is in the range of 0.051 to 0.3 mol p hos P horous ⁇ molcarbon "1 , preferably in the range of 0.06 to 0.15 mol p hos P horous ⁇ mO lcarbon ⁇
• the phosphorus containing compound is selected from the group consisting of a phosphate containing compound, PH 3 , PH 4 C1, P2H4, PC1 3 , black phosphorous, white phosphorous, violet phosphorous, red phosphorous, PF 3 , PF5, PCI5, PBr 5 , P4O6, P4O10, phosphoric acids, optionally ⁇ 3 ⁇ 4, H4P2O7, or
• methaphosphoric acid H 3 P0 3 and mixtures thereof.
• the phosphorous containing compound is a phosphate containing compound.
• the phosphorous containing compound is fed into the reaction vessel in the form of a phosphate containing compound.
• the phosphate containing compound is selected from the group consisting of KH2PO4, K2HPO4, NaKHP0 4 , Na 2 HP0 4 , NaH 2 P0 4 , K 3 P0 4 , Na 3 P0 4 , H 3 P0 4 , aluminum phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium phosphate, ammonium phosphate containing compounds, borano phosphate, boron phosphate, calcium phosphate, calcium pyrophosphate, chromium(III) phosphate, cobalt phosphate, copper(II) phosphate, MgHP0 4 , Mg(H 2 P04)2, MgHP0 4 , Mg 3 (P04)2, gallium phosphate, iron
• monocalcium phosphate monocalcium phosphate, dicalcium phosphate, tricalcium phosphate, tetracalcium phosphate, hydroxyapatite, apatite, octacalcium phophate, biphasic calcium phosphate, amorphous calcium phosphate, nickel phosphate, phosphatidic acid, phosphoric acid, phosphotungstic acid, polyphosphate, potassium dideuterium phosphate, potassium titanyl phosphate, pyrophosphoric acid, silver phosphate, sodium aluminium phosphate, sodium dithiophosphate, sodium hexametaphosphate, sodium monofluorophosphate, sodium trimetaphosphate, sodium triphosphate, triphosphoric acid, uranium phosphate, urea phosphate, yttrium(III) phosphate, zinc phosphate, zirconium phosphate and hydrates and mixtures thereof.
• the carbon containing product is preferably selected from the group consisting of methane, polyhydroxyalkanoates, fatty acids, sugars, proteins, ethanol, methanol, and mixtures thereof, preferably the carbon containing product is methane.
• the gaseous carbon containing educt may be selected from the group consisting of carbon dioxide, carbon monoxide, methane, ethane, propane, butane, ethene, propene, butane, ethyne, propyne, butyne, cyclopropane, cyclobutane, propadiene, butadiene, and mixtures thereof, wherein the carbon containing product is not methane if the carbon containing educt is methane, preferably the gaseous carbon containing educt is carbon dioxide or carbon monoxide, more preferably the carbon containing educt is carbon dioxide.
• the carbon containing product is methane
• the carbon containing educt is not methane.
• the microorganisms are selected from the group consisting of
• Methanosarcinia barkeri Methanobacterium thermoautotrophicus
• thermoautotrophicus Methanococcus maripaludis
• Methanothermobacter marburgensis Methanocaldococcus jannaschii, Clostridium ljungdahlii, Clostridium autoethanogenum, Acetobacterium woodii, Clostridium carboxidivorans, Peptostreptococcus productus, Eubacterium limosum,
• thermoautotrophicus Methanococcus maripaludis
• Methanothermobacter marburgensis Methanocaldococcus jannaschii, and mixtures thereof, and most preferably the microorganisms are of the species
• the microorganisms are methanogenic
• the carbon containing product is methane and the gaseous carbon containing educt is carbon dioxide or carbon monoxide, preferably carbon dioxide, wherein the methanogenic microorganisms in the reaction vessel are further contacted with hydrogen.
• the gas feed rate of hydrogen and the gaseous carbon containing educt, preferably carbon dioxide or carbon monoxide, into the reaction vessel is at least 0.5 wm in total, preferably at least 1.0 wm in total, more preferably at least 2.0 m in total.
• an absolute pressure above normal atmospheric pressure is applied, preferably inside the reaction vessel an absolute pressure of at least 1.5 bar is applied.
• the gas feed rate of hydrogen and the gaseous carbon containing educt, preferably of carbon dioxide or carbon monoxide, preferably carbon dioxide, into the reaction vessel is at least 1.0 wm in total, and wherein inside the reaction vessel an absolute pressure of at least 1.5 bar is applied.
• the volumetric ratio of hydrogen to the gaseous carbon containing educt preferably the volumetric ratio of hydrogen to carbon dioxide, or the volumetric ratio of hydrogen to carbon monoxide, in the gas feed introduced into the reaction vessel is in the range of 3 : 1 to 4.5 : 1 , preferably 3.5: 1 to 4.3: 1, and preferably in the range of 3.7: 1 to 4.1 : 1.
• the microorganisms in the reaction vessel are cultivated in a continuous culture.
• At least one bioreactor comprising a reaction vessel suitable for growing, fermenting and/or culturing microorganisms
• At least one device for providing, measuring and adjusting a feed of a phosphorous containing compound, preferably in the form of a phosphate containing compound, into the reaction vessel,
• At least one device for generating electric energy from a renewable and/or non-renewable energy source optionally at least one device for generating electric energy from a renewable and/or non-renewable energy source
• the gaseous carbon containing educt is selected from the group consisting of carbon dioxide, carbon monoxide, methane, ethane, propane, butane, ethene, propene, butane, ethyne, propyne, butyne, cyclopropane, cyclobutane, propadiene, butadiene and mixtures thereof, wherein the carbon containing product is not methane if the carbon containing educt is methane, more preferably the gaseous carbon containing educt is carbon dioxide or carbon monoxide.
• the carbon containing product is preferably not methane if the carbon containing educt is methane.
• the system further comprises at least one device for oxygen enriched combustion or gasification for producing carbon dioxide.
• the system further comprises at least one device for delivery, recovery, purification, measuring, enriching, storing, recycling and/or further processing of a member selected from the group consisting of a carbon containing product, off-gas, water, nitrogen, oxygen, chlorine, H 2 S, sodium sulphide, microorganisms, preferably methanogenic microorganisms, more preferably methanogenic archaea, medium and medium components, methane and other substances of use in the method according to the invention to or from the reaction vessel and/or bioreactor.
• a member selected from the group consisting of a carbon containing product, off-gas, water, nitrogen, oxygen, chlorine, H 2 S, sodium sulphide, microorganisms, preferably methanogenic microorganisms, more preferably methanogenic archaea, medium and medium components, methane and other substances of use in the method according to the invention to or from the reaction vessel and/or bioreactor.
• the renewable energy source comprises solar energy, resonance energy, magnetic energy, wind power, wave power, tidal power, water/hydro power, geothermal energy, biomass and/or biofuel combustion.
• system further comprises a device for providing, controlling and/or measuring an absolute pressure inside the reaction vessel above normal atmospheric pressure.
• Also provided is a method for producing a carbon containing product from a gaseous carbon containing educt using microorganisms in a reaction vessel comprising applying a feed rate of an essential compound into the reaction vessel so that the ratio of the feed rate of the essential compound into the reaction vessel (in mol/hour or mol/L/hour) to the biomass production rate (in C-mol/hour or C-mol/L/hour) is in a range of 20 times below to 50 times above the molar ratio of the content of the essential compound of the microorganisms in the reaction vessel, i.e. the microbial biomass in the reaction vessel, to the carbon content in the microbial biomass in the reaction vessel.
• a method for producing a carbon containing product from a gaseous carbon containing educt using a microbial biomass in a reaction vessel, wherein the microbial biomass comprises microorganisms comprising the steps of a) determining the biomass production rate (r x ) of the microorganisms inside the reaction vessel (given in C-mol/h or C-mol/L/h), and
• step c) determining the molar ratio of the content of the essential compound to the carbon content in the microbial biomass (R(n3 ⁇ 4 S sentiai/mcarbon) in mol/C-mol), d) applying a feed rate of the essential compound into the reaction vessel (Fessentiai, in mol/fiour or mol/L/hour) characterized in that the ratio of the feed rate of the essential compound into the reaction vessel to the biomass production rate determined in step a) (R(F eS sentiai/r x ) in mol/C-mol) is in a range of 20 times below to 50 times above R(n3 ⁇ 4 S sentiai/mcarbon) as determined in step c).
• (R(F eS sentiai/r x )) is in a range of 20 times below to 50 times above R(n3 ⁇ 4 S sentiai/mcarbon).
• R(messentiai/mcarbon) is 0.2
• (R(F eS sentiai/r x ) may be in a range of 0.01 to 10.
• the essential compound may be any compound which is essential, i.e. necessary, for the growth of the microorganism, biomass, microorganism strain or cell culture.
• essential compounds are compounds selected from the group consisting of nitrogen containing compound, phosphorous containing compound and sulfur containing compound.
• the essential compound is not necessary for producing the carbon containing product.
• F eS sentiai is the feed rate of the essential compound into the reaction vessel.
• R(n3 ⁇ 4 S sentiai/mcarbon) is the molar ratio of the content of the essential compound in the microbial biomass to the carbon content in the microbial biomass.
• the content of the essential compound and the carbon content in the microbial biomass may be determined as described in Duboc et ah, 1995, Journal of Biotechnology , 43: 145-158.
• Examples of essential compounds useful in the method of the invention are phosphorous (P), nitrogen (N) and sulphur (S).
• the present invention provides a method for producing a carbon containing product from a gaseous carbon containing educt using microorganisms in a reaction vessel comprising the steps of
• step b) applying a feed rate of a phosphorous containing compound into the reaction vessel (F p hos P horous) so that the ratio of the feed rate of the phosphorous containing compound into the reaction vessel to the biomass production rate determined in step a) (R(F p hosphorous/r x )) is in the range of 0.001 to 0.5 mol p hos P horous ⁇ mo on "1 , optionally in the range of 0.005 to 0.3 mol p hos P horous ⁇ molcarbon "1 or in the range of 0.02 to 0.15 mol p hos P horous ⁇ molcarbon "1 . Within this range, the experimenter may achieve qCH4,max, i.e.
• the maximal specific methane productivity per biomass amount or a value close to it may, depending on the specific needs of the experimenter, control biomass growth by increasing or decreasing the feed rate of the phosphorous containing compound.
• the value qCH4,max of each microorganism may be determined as described in Rittmann et al. (2011) Biomass and Bioenergy, 36(Jan 2012):293-301. In Rittmann et al. (2011) it is also explained how the mean elementary composition (carbon, hydrogen, nitrogen, oxygen, phosphorous and sulphur) may be determined and used in order to calculate a C-molar growth of a given microorganism in a bioprocess. This is then subsequently used in order to link the feed mol p hos P horous in proportion to the measured growth of microorganisms quantified in molcarbon.
• the microorganisms produce the carbon containing educt in high amounts, e.g. at high MER.
• the experimenter controls use of the gaseous carbon containing compound mainly for biomass production or mainly for the production of the carbon containing compound.
• the microorganisms are at a good compromise between biomass production and use of consumables, i.e. feed of phosphorous and investment of the gaseous carbon containing educt in relation to the amount of produced carbon containing product and biomass growth.
• the method state may also be considered as noted between stability and economy", wherein "economy” denotes that in view of a reduced investment of consumables, such as the phosphorous containing compound, very high amounts of carbon containing product are produced.
• “stability" of a microorganism culture is considered a status, wherein the cells may not suffer from consumable depletion, i.e. wherein phosphorous and other consumables are provided in excess and can be used for biomass production.
• R(F p hos P hate/r x ) is in the range of 0.001 to 0.05 molphosphate ⁇ molcarbon "1 , preferably in the range of 0.02 to 0.04 mol p hos P horous ⁇ molcarbon "1 .
• the microorganisms inside the reaction vessel are in a liquid limited state and the gaseous carbon containing educt will essentially only be used for producing the carbon containing product.
• the skilled person understands that also in this liquid limited state biomass is produced so that the biomass production rate is positive in general and may e.g. be in the range from 0.10 to 5.25 C-mmolbiomass/1 ' h at a maximum.
• gaseous carbon containing educt essentially in the sense of using the gaseous carbon containing educt means that a maximum of 15%, preferably a maximum of 10%, more preferably a maximum of 5%, most preferably a maximum of 1% the gaseous carbon containing educt will be used for biomass production, whereas the remaining part, i.e. 85%, preferably 90% and more preferably 95%, most preferably 99%, of the gaseous carbon containing educt is used for producing the carbon containing product, such as methane.
• R(F p hos P hate/r x ) is in the range of 0.051 to 0.3 mol p hos P hate -molcarbon "1 , preferably in the range of 0.06 to 0.15 mol p hos P horous ⁇
• the microorganisms are in a gas limited state, i.e. a state, wherein a higher percentage of the gaseous carbon containing educt is used for biomass production than the percentage which is used for producing the carbon containing educt.
• the gaseous carbon containing educt can be any carbon containing compound which is gaseous under normal atmospheric pressure and in the temperature range from 0 °C and 130 °C.
• the gaseous carbon containing educt should not be toxic to the microorganisms in the reaction vessel or should not be introduced into the reaction vessel in concentrations which are toxic to the microorganisms.
• the skilled person can easily determine whether a concentration of a compound is toxic to the microorganism cell by observing cell, i.e. biomass, growth over a short period of time, e.g. 6 h, wherein the period of time considers the standard growth behaviour of said microorganism.
• the gaseous carbon containing educt is selected from the group consisting of carbon dioxide, carbon monoxide, methane, ethane, propane, butane, ethene, propene, butane, ethyne, propyne, butyne, cyclopropane, cyclobutane, propadiene, butadiene, and mixtures thereof, wherein if the carbon containing educt is methane, the carbon containing product is not methane, preferably the gaseous carbon containing educt is carbon dioxide.
• the carbon containing product may also be any carbon containing compound which is not toxic to the cells or is removed from the reaction vessel before it may exert a negative effect on the microorganisms inside the reaction vessel. Such a negative effect may be a reduced biomass growth rate, cell death to an extent which is not observed without production of this specific carbon containing compound or reduced methane production rate or amount.
• the carbon containing product may be liquid, gaseous or solid.
• the carbon containing product is selected from the group consisting of methane, polyhydroxyalkanoates (PHA), fatty acids, sugars, proteins, ethanol, and methanol, preferably the carbon containing product is methane.
• Bio diesel production CO or C0 2 to produce biomass which contains lipids
• Biomass production Methane to protein, e.g. for animal nutrition, or C0 2 to biomass conversion for therapeutical purposes, and/or
• the gaseous carbon containing educt are carbon dioxide (C0 2 ) or carbon monoxide (CO), respectively.
• the carbon containing product is methane (1), PHA + CO2 (2), lipids and ethanol (4).
• R(F p hos P hate/r x ) should reasonably be above a value of about 0.0505 mO lphosphate • molcarbon "1 .
• the gaseous carbon containing educt may as well be a mixture of different carbon containing compounds introduced in the same or different amounts.
• one method may also lead to the production of one or more different carbon containing compounds as carbon containing products.
• the carbon containing product is neither biomass in general nor are gaseous carbon containing educt and carbon containing product identical in specific applications.
• a carbon containing educt may be identical to a carbon containing product in another embodiment of the method of the invention.
• the microorganisms are methanogenic microorganisms
• the carbon containing product is methane
• the gaseous carbon containing educt is carbon dioxide or carbon monoxide
• the methanogenic microorganisms in the reaction vessel are further contacted with hydrogen.
• the methanogenic microorganisms may be switched from gas limitation to liquid limitation depending on the experimenter ' s biomass need. If additional amounts of biomass or a higher biomass concentration is required, the amount of phosphorous, i.e. the concentration of phosphorous inside the reaction vessel may be increased by increasing the feed of the phosphorous containing compound, preferably a phosphate compound. If the biomass inside the reaction vessel is sufficient for the experimenter ' s need, the feed of the phosphorous containing compound is reduced and the gaseous carbon containing educt will essentially only be used for producing the carbon containing product. The biomass concentration and thereby the biomass production rate may e.g. be determined gravimetrically as described elsewhere, cf.
• Biomass” or “microbial biomass” or “cell culture” or “microorganisms” or “cells” of the invention equally denote to the same collective of microorganisms of one or more species which is used in the method of the invention for producing a carbon containing product from a gaseous carbon containing educt using microorganisms in a reaction vessel.
• the microorganisms i.e. cells of the biomass or cell culture in the reaction vessel of the invention, principally function as a catalyst for the biological conversion of producing a carbon containing product from a gaseous carbon containing educt using microorganisms in a reaction vessel. They are placed inside the reaction vessel of the invention by inoculation of the medium inside the reaction vessel or by inoculation of the medium prior to the transfer of the medium into the reaction vessel of the invention.
• microorganisms also denotes microorganisms in a suspension with medium as inside a reaction vessel, the cell culture of microorganisms typically comprises medium.
• the microorganisms may be removed with or without medium from the reaction vessel either completely or partially during fermentation and in any phase for various purposes, such as exchange of cells or medium and/or for analytics, such as cell weight determination or cell vitality examination, or harvest for future inoculum.
• Biomass obtained from the reaction vessel may be used as source for the recovery of metabolites and as basis for new culture medium.
• Healthy biomass denotes a good vitality status of a living biomass, i.e. of the living microorganisms.
• a "microorganism” is an organism that is unicellular or lives in a colony of cellular organisms. Microorganisms are very diverse; they include bacteria, fungi, archaea, microscopic plants (such as green algae), and animals such as plankton and the planarian. Some microbiologists also include viruses, but others consider these as non-living.
• Methodogenic in the sense of the invention denotes the capability of a microorganism of converting carbon dioxide and hydrogen into methane, i.e. being able to perform the reaction pathways of C02+4H2 ⁇ CH 4 +2H 2 0 or CO+3H 2 -> CH 4 + H 2 0 which are called methano genesis or biological methanation, respectively.
• a "methanogenic microorganism” is any microorganism which is capable of producing methane from other substances, i.e. capable of methanogenesis and/or biological methanation, preferably from carbon dioxide and hydrogen.
• the methanogenic microorganisms of the invention are capable of producing methane from hydrogen and carbon dioxide or carbon monoxide.
• the methanogenic microorganism of the invention may be grown in a reaction vessel, which is for example comprised in a bioreactor, under controlled fermentation or cell culture conditions in a controlled environment. In principle, any such methanogenic microorganism can be used for the method of the invention.
• Environment or “controlled environment” refers to the surrounding of the methanogenic microorganisms inside the fermenter or reaction vessel comprising both, the liquid, characterized for example by the medium composition, feed and exchange rate, and the gaseous phase, characterized for example by the gas feed and gas feed composition, and the applied fermentation conditions.
• the microorganism in the cell culture of the invention is obtainable from public collections of organisms, such as the American Type Culture Collection, the Deutsche Stammsammlung fur Mikroorganismen und Zellkulturen (DSMZ, Braunschweig, Germany), CBS (Utrecht, Netherlands) or the Oregon Collection of Methanogens, or they can be isolated from a variety of environmental sources.
• environmental sources include anaerobic soils and sands, bogs, swamps, marshes, estuaries, dense algal mats, both terrestrial and marine mud and sediments, deep ocean and deep well sites, sewage and organic waste sites and treatment facilities, animal intestinal tracts, volcano areas and faeces.
• Suitable cell cultures may be pure i.e. contain only cells of a single species, or may be mixed cultures i.e. contain cells of more than one species.
• a pure cell culture of microorganisms is used for the method of the invention.
• the microorganism of the invention may be selected from the group consisting of Methanobacterium alcaliphilum, Methanobacterium bryantii, Methanobacterium congolense, Methanobacterium defluvii, Methanobacterium espanolae, Methanobacterium formicicum, Methanobacterium ivanovii, Methanobacterium palustre, Methanobacterium thermaggregans, Methanobacterium uliginosum, Methano- brevibacter acididurans, Methanobrevibacter arbor iphilicus, Methanobrevibacter gottschalkii, Methanobrevibacter olleyae, Methanobrevibacter ruminantium, Methanobrevibacter smithii, Methanobrevibacter woesei, Methanobrevibacter wolinii, Methanothermobacter marburgensis, Methanothermobacter thermo- autotrophicus, Methanobacterium thermoautotrophicus, Methanothermo
• Methanococcus aeolicus Methanococcus maripaludis, Methanococcus vannielii, Methanococcus voltaei, Methanothermococcus thermolithotrophicus, Methanopyrus kandleri, Clostridium ljungdahlii, Clostridium autoethanogenum, Acetobacterium woodii, Clostridium carboxidivorans, Peptostreptococcus productus, Eubacterium limosum, Butyribacterium methylotrophicum, Rhodopseudomonas palustris, Rhodospirillum rubrum, Citrobacter sp., Thermosinus carboxydivorans,
• the microorganism is selected from Methanosarcinia barkeri, Methanobacterium thermoautotrophicus,
• thermoautotrophicus Methanococcus maripaludis
• Methanothermobacter marburgensis Methanocaldococcus jannaschii, Clostridium ljungdahlii, Clostridium autoethanogenum, Acetobacterium woodii, Clostridium carboxidivorans, Peptostreptococcus productus, Eubacterium limosum, Butyribacterium methylotrophicum, Rhodopseudomonas palustris, Rhodospirillum rubrum, Citrobacter sp., Thermosinus carboxydivorans, Carboxydothermus hydrogenoformans, Thermococcus onnurineus, Clostridium butyricum, and mixtures thereof, more preferably the microorganisms are methanogenic microorganisms, even more preferably they are methanogenic archaea or are selected from the group consisting of Methanosarcinia barkeri, Methanobacterium thermoautotrophicus, Methanothermobacter thermoautotrophic
• Methanothermobacter marburgensis Methanocaldococcus jannaschii, and mixtures thereof, and most preferably the microorganisms are of the species
• Methanothermobacter marburgensis "Archaea” are single-celled microorganisms. Archaea have no cell nucleus or any other membrane-bound organelles within their cells. In the past, they were viewed as an unusual group of bacteria and named archaea bacteria, however, to date archaea are considered as having an independent evolutionary history since they show many differences in their biochemistry in comparison to other forms of life. Thus, they are now classified as a separate domain (Archaeal domain) in the three-domain system. In this system the phylogenetically distinct branches of evolutionary descent are the archaea, bacteria and eukarya.
• the microorganism of the invention i.e. the biomass
• the microorganism is used in cell culture, i.e. the microorganism is used as suspension with medium.
• the medium of the invention comprises at least a source of nitrogen, assimilable salts, a buffering agent and trace elements. Sulphur is provided to the cells by a reducing agent or may be provided extra, thus, the reducing agent and the sulphur-providing substance may or may not be the same. Sulphur may be provided to the cells by the provision of biogas.
• the medium is generally designed to keep the cells alive, healthy and productive without being expensive and thus beneficial for the entire process economy of the method of the invention.
• the medium Prior to inoculation of the medium with a methanogenic microorganism, the medium should be degassed for being anaerobic as is required for optimal methane production by a methanogenic microorganism which is used. This applies in particular if the methanogenic microorganism is a methanogenic archaea.
• Standard medium compositions may be taken from the literature and be adapted (Rittmann et al., 2012, Biomass Bioenergy, 36:293-301).
• An example for an adapted standard medium has the following composition (L 1 ): 2,1 g NH 4 C1; 6,8 g KH2PO4; 3,4 g Na 2 C0 3 ; 0,09 g Titriplex I; 0,04 g MgCl 2 x 6H 2 0; 0,01 g FeCl 2 x4H 2 0; 0,2 mg C0CI2X6H2O; 1,2 mg NiCl 2 x6H 2 0; 0,2 mg NaMo0 4 x2H 2 0, the pH will be discussed below and can be adjusted by titrating 1 M (NH 4 ) 2 C0 3 , NaOH or NH 4 OH, NH 3 , any other ammonium compound mentioned herein, or mixtures thereof.
• Said exemplary standard medium may be used for any embodiment of the method of the invention but may
• the medium may be refreshed in a constant or step-wise mode during fermentation under continuous conditions.
• the medium feed rate or medium in-feed rate of medium or medium components is e.g. adjusted between 0.001 h "1 and 0.1 h "1 .
• the medium has to be adjusted to the specific needs of the microorganism species, i.e. cell strain.
• the fermentation conditions i.e. medium composition, and other parameters, such as phosphate feed, gaseous carbon compound containing feed, hydrogen feed, pH, temperature, stirring speed, pressure, oxidation reduction potential or medium or medium component (i.e.
• Consable comprises all substances, components and/or materials in any form, i.e. solid, gaseous or liquid, which might be required by the methanogenic microorganisms in the reaction vessel of the invention, such as for example phosphorous, the gaseous carbon containing educt, e.g. carbon dioxide, and hydrogen. Also included are substances which are fed into the reactor to maintain a certain fermentation condition. The supply of consumables can be adjusted by the experimenter throughout the method of the invention if deemed appropriate by the experimenter. "Procedural requirements" comprise all situations which may arise during the method of the invention, such as the requirement to switch from gas to liquid limitation state.
• the phosphorous containing compound is selected from the group consisting of phosphate containing compound, PH3, PH4CI, P2H4, PCI3, black phosphorous, white phosphorous, violet phosphorous, red phosphorous, PF3, PF5, PCls, PBr 5 , P 4 0 6 , P4O10, phosphoric acids, H3PO4, H3PO3, H4P2O7, and
• phosphorous is fed into the reaction vessel in the form of a phosphate containing compound which may be selected from the group consisting of KH2PO4, K2HPO4, NaKHP0 4 , Na 2 HP0 4 , NaH 2 P0 4 , K3PO4, Na 3 P0 4 , H3PO4, aluminum phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium phosphate, ammonium phosphate containing compounds, borano phosphate, boron phosphate, calcium phosphate, calcium pyrophosphate, chromium(III) phosphate, cobalt phosphate, copper(II) phosphate, MgHPC , Mg(H 2 P04)2, MgHPC , Mg 3 (P04)2, gallium phosphate, iron(II) phosphate, iron(III) phosphate, Pb3(PC"4)2, lithium iron phosphate, manganese(II) phosphate,
• monocalcium phosphate monocalcium phosphate, dicalcium phosphate, tricalcium phosphate, tetracalcium phosphate, hydroxyapatite, apatite, octacalcium phophate, biphasic calcium phosphate, amorphous calcium phosphate, nickel phosphate, phosphatidic acid, phosphoric acid, phosphotungstic acid, polyphosphate, potassium dideuterium phosphate, potassium titanyl phosphate, pyrophosphoric acid, silver phosphate, sodium aluminium phosphate, sodium dithiophosphate, sodium hexametaphosphate, sodium monofluorophosphate, sodium trimetaphosphate, sodium triphosphate, triphosphoric acid, uranium phosphate, urea phosphate, yttrium(III) phosphate, zinc phosphate, zirconium phosphate and hydrates and mixtures thereof.
• the absolute pressure during the method inside the reaction vessel may also be in the range of 1.0 bar to 1200 bar, 1.2 bar to 1000 bar, 1.3 bar to 500 bar, preferably in the range of 1.5 bar to 1000 bar.
• the range of 1.5 bar to 5 bar and more preferably the range of 5 to 12 bar has been calculated by the inventors to be optimal for the production of the carbon containing product and would be well tolerable by the microorganisms of the present invention, in particular if the microorganisms are archaea and the carbon containing product is methane.
• some methanogenic microorganisms, such as methanogenic archaea are known to tolerate very well extremely high pressures.
• the pressure values mentioned before and in the following may be applied in the method of the invention for producing methane.
• Methanogenic archaea which are extremely tolerable to high pressures are naturally derived from a high pressure environment, such as from deep sea.
• bioreactor and in particular the reaction vessel in this embodiment is suitable for such high pressures.
• suitable reaction vessels, bioreactors and pressure resistant materials are well known to a person skilled in the art and can for Example be obtained from Sartorius (Gottingen, Germany), such as Biostat ® Cplus, Buchi (Essen, Germany) or other suppliers of bioreactors.
• the volumetric ratio of hydrogen to carbon dioxide in the gas feed introduced into the reaction vessel is in the range of 3 : 1 to 4.5 : 1 , preferably 3.5 : 1 to 4.3 : 1 , and more preferably in the range of 3.7: 1 to 4.1 :1, most preferably the ratio is 3.9: 1.
• Off-gas denote a gaseous outcome of the reaction vessel of the invention and thus of the method which is typically a gas mixture leaving the reaction vessel, such as it is the case if the gaseous carbon containing educt is carbon dioxide and the carbon containing product is methane.
• the qualitative and quantitative content of the off-gas depends on various factors, such as the total gas feed rate into the reaction vessel, the feed of the gaseous carbon containing educt and product and the composition of the gas feed into the reaction vessel.
• the off-gas may comprise water vapour, the gases which are introduced into the reaction vessel, such as for example hydrogen, nitrogen, carbon dioxide, carbon monoxide, hydrogen sulphide or else, and gases which are produced by the microorganisms, such as methane.
• the off-gas mixture may further contain contaminants which may be present in the gases which are introduced into the reaction vessel or originate from the cell culture, for example oxygen, compounds from biogas generation, nitrogen gas and others.
• a typical off-gas mixture may mainly comprise methane, preferably the methane content is at least 40%, 45%, 50%, or 60%, more preferably the methane content is at least 70%>, more preferably 80%>, 84%, 86%, or 88%, even more preferably the methane content in the off-gas is at least 90%, most preferably the methane content is at least 92%, 94%, 96%, 98% or 99% wherein the higher the content the more preferred.
• a high methane content can for example be achieved by feedback control devices.
• the methane from the off-gas may be separated by standard means, e.g. by membranes such as obtainable from Du Pont (Wilmington, DE, USA) or Gore (Newark, DE, USA). Methane may further be used in end-user applications as energy carrier for energy applications to produce heat and/or electric energy or else or as raw material in various chemical and biological conversions.
• In-gas denotes the total gas or gas mixture which is fed into the reaction vessel and thus provided to the microorganism.
• the term is used to describe the total gas introduced into the reaction vessel or bioreactor, however, that does in no way mean that all potentially introduced gases are introduced in a mixture or single gas flow.
• the gases which may be comprised in the in-gas may thus be introduced as a mixture, separately via different devices or tubes or timely one after another via the same device r tube or via different devices or tubes.
• the in-gas or in-gas feed comprises the gaseous carbon containing educt , i.e. comprises the gas(es) which are required for the production of the carbon containing product, such as methane, i.e.
• hydrogen and carbon dioxide as the gaseous carbon containing educt, and other gases which may be required, such as for example carbon monoxide, nitrogen, hydrogen sulphide or else, or which are introduced as contaminants. This is especially the case if real gases are used as gas sources for the method of the invention.
• “Feed” in general means the introduction, flow or transfer of a gas, liquid, suspension or any other substance into the reaction vessel or into the bioreactor of the invention, such as a phosphorous containing compound feed or a feed of the gaseous carbon containing educt, such as carbon dioxide, carbon monoxide, methane, ethane, propane, butane, ethene, propene, butane, ethyne, propyne, butyne, cyclopropane, cyclobutane, propadiene, and butadiene, wherein the carbon containing product is not methane if the carbon containing educt is methane, preferably the gaseous carbon containing educt is carbon dioxide, and also the removal or withdrawal of a gas, liquid, suspension or any other substance from the reaction vessel or from the bioreactor to the outside, such as the feed of the carbon containing product, e.g.
• methane polyhydroxyalkanoates, fatty acids, sugars, proteins, ethanol, and methanol, preferably methane.
• methane is not also meant to be the carbon containing product.
• methane which is introduced as gaseous carbon containing educt is not converted 100% to the respective carbon containing compound, it may nevertheless be present in the off-gas leaving the reaction vessel.
• “In-gas feed” denotes the feed or flow or introduction of the in-gas, such as carbon monoxide, hydrogen or carbon dioxide, into the reaction vessel of the invention.
• Haldrogen in-gas feed or “hydrogen gas feed” denotes the feed or flow of hydrogen comprising in-gas or of hydrogen gas into the reaction vessel or bioreactor.
• Carbon dioxide in-gas feed or “carbon dioxide gas feed” denotes the feed or flow of carbon dioxide comprising in-gas or carbon dioxide gas into the reaction vessel or bioreactor.
• Fee rate in general denotes the amount of a gas, liquid, suspension or any other substance into the reaction vessel or into the bioreactor of the invention. Rarely, feed rate may also be used to describe the removal or withdrawal of a gas, liquid, suspension or any other substance from the reaction vessel or from the bioreactor to the outside within a certain period of time, such as of the phosphorous containing compound which may be fed in the form of a phosphate or phosphate containing compound or the gaseous carbon containing educt.
• In-gas feed rate or “gas feed rate” denotes the volume of an in-gas or gas which is introduced into the reaction vessel per volume of reaction medium within a certain period of time. Thus, the in- gas feed rate or gas feed rate reflects the amount of gas provided to the
• the in-gas feed rate or feed rate may be given as volume gas per volume of reaction vessel medium per time period (e.g. wm, volume per volume per minute), i.e. per minute, hour or day, preferably per minute.
• volume gas per volume of reaction vessel medium per time period e.g. wm, volume per volume per minute
• hour or day preferably per minute.
• volume of gas introduced into the reaction vessel is given in relation to the volume of reaction medium.
• the “reaction medium” or “reaction vessel medium” is the liquid medium inside the reaction vessel of the bioreactor, i.e. the cell suspension, which comprises the microorganisms.
• the volume of the reaction medium is determined gravimetrically, by differential pressure, radar or any other method known to the skilled person.
• Exemplary suppliers are e.g. MettlerToledo (Gsammlungsee/Switzerland) for balances and e.g. Lewa (Leonberg, Germany) for pumps.
• the gas feed rate of all gases which are introduced in parallel may be given in total, which denotes the sum gas feed rate of both hydrogen and carbon dioxide together.
• gases such as hydrogen and carbon dioxide
• the total gas feed rates e.g. the gas feed rate of hydrogen plus the gas feed rate of carbon dioxide should be considered to determine the total gas feed rate.
• the gas feed rate of hydrogen and carbon dioxide/monoxide into the reaction vessel is at least 0.5 wm in total
• the volume of hydrogen gas and the volume of carbon dioxide/monoxide are to be summed up as total volume of gas (volume of hydrogen plus volume of carbon dioxide) which is introduced into the reaction vessel per volume of reaction medium inside the reaction vessel and comprising the methanogenic microorganisms per period of time, e.g. per minute.
• a method for producing methane as a highly preferred embodiment of the present invention comprises preferably contacting methanogenic microorganisms in a reaction vessel with hydrogen and carbon dioxide/monoxide as the gaseous carbon containing educt, wherein the gas feed rate of hydrogen and carbon dioxide, i.e. the sum gas feed rate of hydrogen and carbon dioxide, i.e.
• the gas feed rate of hydrogen plus the gas feed rate of carbon dioxide or carbon monoxide, into the reaction vessel is at least 0.5 wm in total, at least 1 wm in total, is at least 1.1 wm in total, preferably is at least 1.2 wm in total, 1.3 wm in total, 1.4 wm in total, more preferably is at least 1.5 wm in total, 1.6 wm in total, 1.7 wm in total, 1.8 wm in total, 1.9 wm in total, most preferably is at least 2.0 wm in total or is at least 2.1, 2.3, 2.5, 2.7, 2.8, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 7.0, 7.5, 8.0, 9.0, 10.0, 12.5, 15.0, 17.5, or at least 20.0 wm in total or higher, or the gas feed rate of hydrogen and carbon dioxide, i.e.
• the sum gas feed rate of hydrogen and carbon dioxide, i.e. the gas feed rate of hydrogen plus the gas feed rate of carbon dioxide, into the reaction vessel is in the range of 1.0 wm to 25 wm in total, preferably is in the range of 1.2 wm to 100.0 wm in total 1.2 wm to 25.0 wm in total, more preferably is in the range of 1.5 wm to 15.0 wm in total, even more preferably is in the range of 1.7 wm to 10.0 wm in total, most preferably is in the range of 2.0 wm to 8.0 wm in total.
• the nitrogen concentration inside the reaction vessel is in the range of 0.0001 to 35 mmol/L, 0.0001 to 30 mmol/L, 0.0001 to 28 mmol/L, 0.0001 to 25 mmol/L, 0.001 to 23 mmol/L, 0.05 to 20 mmol/L, 0.0001 to 25 mmol/L, 0.0001 to 23 mmol/L, 0.0005 to 20 mmol/L, 0.001 to 18 mmol/L, 0.001 to 17 mmol/L, 0.001 to 15 mmol/L, 0.001 to 12 mmol/L, 0.001 to 10 mmol/L, 0.001 to 7 mmol/L, 0.001 to 5 mmol/L, 55 to 1000 mmol/L, 60 to 500 mmol/L, 65 to 500 mmol/L, 70 to 400 mmol/L, 75 to 300 mmol/L, or 75 to
• the total gas feed may vary between 0.05 wm and 20 wm without significantly influencing the outcome of the method in producing methane.
• Real gas denotes that a gas is not absolutely pure, i.e. is gas mixture.
• real gas denotes that beside the gaseous carbon containing educt also other gases are comprised which are denoted as contaminants.
• an "ideal gas” is absolutely pure according to general industrial standards.
• a typical example for a real gas is “biogas” or also the off-gas of the method of the invention.
• Biogas typically refers to a gas produced by the biological breakdown of organic matter, e.g. biomass, in the absence of oxygen, such as for example biomass fermentation. Biogas originates from biogenic material and is a type of bio fuel like bioethanol.
• Biogas is produced by anaerobic digestion or fermentation of biodegradable materials, i.e. of biomass, such as manure, sewage, municipal waste, green waste, plant material and energy crops.
• biomass fermentation denotes the anaerobic digestion or fermentation of biodegradable materials, i.e. of bio mass.
• This type of biogas comprises primarily methane and carbon dioxide and may be used as gaseous carbon containing educt in a method for producing a carbon containing product being methane.
• Other gas species generated by use of bio mass is wood gas, which is created by gasification of wood or other bio mass. This type of gas consists mainly of nitrogen, hydrogen, and carbon monoxide, with trace amounts of methane.
• the gaseous carbon containing educt may be any gas, including a real gas, ideal gas or industrial gas.
• an "industrial process” is any process which involves chemical or mechanical steps to aid in the manufacture of an item or items, usually carried out on a larger scale by man and not by nature.
• relevant industrial processes produce the gaseous carbon containing educt, e.g. carbon dioxide, carbon monoxide, and/or hydrogen or other gases and substances which might be required for the method of the invention as educt. If said substances are a side product of said industrial process, they are sometimes referred to as waste products (e.g. "industrial waste gas”).
• Industrial processes which produce or release the gaseous carbon containing educt, hydrogen or others are also denoted as "industrial sources" for those gases.
• the gas is referred to as being an "ideal gas” having a very high or absolute purity/quality or being a “real gas” having a lower or not absolute purity, meaning that one or more other gases may be present in various amounts, however, the gas species not being harmful to the cells of the invention or being present in the real gas in an amount not being harmful to the cells.
• the gaseous carbon containing educt which is used in the method of the invention and may be converted into methane by methanogenic microorganisms in a preferred embodiment of the invention, may be pure or of high quality/purity, i.e. "ideal gas", or be a "real gas", characterized in that it comprises beside carbon dioxide also other gases which are denoted as contaminants.
• the carbon dioxide may be of any source. These carbon dioxide sources include but are not limited to ideal gas sources delivering ideal gas or real gas sources delivering real gas. Ideal gases may be obtained by various purchasers which are known to the skilled person (e.g. Air Liquide, Paris, France).
• Sources of real gas are natural sources, such as the atmosphere, fixed carbon dioxide in living or dead biomass or industrial processes, also denoted as "industrial sources”, comprising the combustion or oxygen combustion or oxygen enriched combustion of carbonaceous material, such as biomass, waste, biofuel, fossil fuels, or else, the burning of vegetable matter, biogas, bioethanol, biomass fermentation or anaerobic digestion to produce liquid fuels and coal, biomass gasification processes, general gasification, combustion from engines, such as cars, any other carbon dioxide releasing process, carbon dioxide contained in the off-gas of the method of the invention or combinations thereof.
• carbon dioxide real gas is used for the method of the invention if the gaseous carbon containing educt is carbon dioxide, i.e.
• carbon dioxide from a real gas source more preferably the carbon dioxide real gas is from an industrial process, such as industrial waste gas, biogas or biomass fermentation, off-gas of the method of the invention itself, from other methane producing processes performed by methanogenic archaea, oxygen combustion or oxygen enriched combustion or mixtures thereof.
• an industrial process such as industrial waste gas, biogas or biomass fermentation
• off-gas of the method of the invention itself, from other methane producing processes performed by methanogenic archaea, oxygen combustion or oxygen enriched combustion or mixtures thereof.
• using the off-gas of the method itself and using carbon dioxide which was produced by oxygen enriched combustion using the oxygen produced by the electrolysis of water improves educt utilization, economy and cost-effectiveness of the overall method.
• Real gas of carbon dioxide or hydrogen is often cheaper and also makes a contribution to environmental protection due to optimal raw material usage.
• carbon dioxide, which would otherwise be released to the atmosphere as waste gases and potentially would contribute to global warming, is recycled and used as new energy source raw material.
• Combustion e.g. "oxygen enriched combustion” or “oxygen combustion” is a process wherein carbonaceous material, e.g. petroleum, coal, living and/or dead biomass reacts with an oxidizing element, such as oxygen, into carbon dioxide or also carbon monoxide, by thermal conversion.
• the oxygen which is required for combustion may be derived from the electrolysis of water (see below).
• Devices for combustion, oxygen enriched combustion or oxygen combustion may be obtained from Mitsubishi Heavy Industries, Tokyo, Japan. Biomass for combustion and/or gasification may also be dried biomass of the method of the invention.
• the gaseous carbon containing educt may be of any source and may also be mixtures of different sources. It may be necessary to remove contaminants from the gaseous carbon containing educt prior to its feed into the reaction vessel of the bioreactor of the invention by various methods which are known to the person skilled in the art, such as e.g.
• a carbon dioxide scrubber if carbon dioxide is the gaseous carbon containing educt, contacting the gas with an absorbing medium which selectively absorbs the gaseous carbon containing educt, such as amine, monoethanolamine solutions or quicklime absorption, or which selectively absorbs the gaseous carbon containing educt from a real gas, activated charcoal or activated coal, by polymer membrane gas separators, molecular sieves, others and combinations thereof. All aforementioned methods are also useful for recovery, purification, enriching, storing, recycling and/or further processing of the carbon containing educt or product which is contained in the off-gas.
• the carbon containing educt After the carbon containing educt is separated from other components of the off-gas it may be fed back by tubes or other devices and means which are known to the skilled person into the reaction vessel as gaseous carbon containing educt to be converted into the carbon containing product, such as methane, i.e. will be introduced into the reaction vessel as part of the in-gas, and is thus recycled. In this way, the use of carbon dioxide is optimized. The same, of course, also applies to gaseous carbon containing educts in general.
• any gaseous carbon containing compound e.g. carbon dioxide
• any natural, industrial, technical or artificial process which releases said gaseous carbon containing compound
• gaseous carbon containing compound may be used as gaseous carbon containing educt.
• a gaseous carbon containing educt is carbon dioxide derived from gasification.
• Gasification is a process which converts carbonaceous materials, e.g. petroleum, coal, living and/or dead biomass, bio fuel or else into carbon dioxide, hydrogen and carbon monoxide, by thermal conversion and a controlled amount of oxygen and/or steam into a resulting gas mixture called resulting gas mixture called resulting gas mixture called resulting gas mixture called resulting gas mixture called resulting gas mixture called resulting gas mixture called resulting gas mixture called resulting gas mixture called resulting gas mixture called resulting gas mixture called resulting gas mixture called resulting gas mixture called resulting gas mixture called resulting gas mixture called resulting gas mixture called resulting gas mixture called resulting gas mixture called resulting gas mixture called resulting gas mixture called resulting gas mixture called resulting gas mixture
• the oxygen which is required for gasification may be derived from the electrolysis of water (see below).
• the carbon dioxide comprising real gas is purified according to any of the techniques mentioned above or known in the art, to increase the carbon dioxide content to around 80%. Gasification reactors or devices can be obtained from
• Carbon dioxide i.e. carbon dioxide gas
• any source e.g. ideal, industrial or real
• carbon dioxide of different ideal and real sources may be mixed in any ratio and the mixture may be used. It is also appropriate to mix the gas sources or change the gas sources during fermentation or during performing the method. In any way, it is not even necessary to determine the exact composition of the real gas or determine the exact hydrogen content in the real gas which is another very important advantage of the method of the invention over the methods known in the art.
• the hydrogen i.e. hydrogen gas
• the hydrogen which is e.g. used for the method of the invention in case the carbon containing product is methane, and which may be converted into methane by methanogenic microorganisms, may be pure or of high quality/purity, i.e. "ideal gas", or "real gas” characterized in that it comprises beside hydrogen also other gases which are denoted as contaminants, or "industrial gas".
• the hydrogen may be of any source. Ideal hydrogen gases may be obtained by various purchasers which are known to the skilled person (e.g. Air Liquide, Paris, France).
• Hydrogen sources include but are not limited to ideal gas sources delivering ideal gas, or real gas sources delivering real gas, such as natural sources, industrial processes (industrial "waste gas") comprising the electrolysis of water and/or brine, propane dehydrogenation, hydrogen from oil refining, such as from cracking process, biomass fermentation, be made via methane steam reforming or hydrogen may be off-gas released from the method or reaction vessel of the invention or from other methane producing processes performed by methanogenic archaea. Hydrogen is recovered from the off-gas of the method using a separation device such as a membrane which allows the comparatively small hydrogen molecules to pass through the pores of the membrane and allows the comparatively large molecules of the other gas components to be rejected by the membrane.
• a separation device such as a membrane which allows the comparatively small hydrogen molecules to pass through the pores of the membrane and allows the comparatively large molecules of the other gas components to be rejected by the membrane.
• Such separation devices and membranes may be obtained for example from Du Pont (Wilmington, DE, USA) or Gore (Newark, DE, USA).
• the hydrogen recovered from the off-gas is then fed back into the reaction vessel via tubes or means which are known to the skilled person to be used as hydrogen source for the conversion of the gaseous carbon containing educt into methane by the methanogenic microorganisms.
• the use of hydrogen of the off-gas of the invention improves educt utilization and process economy of the overall method.
• hydrogen of different sources may be mixed in any ratio. As it also applies for carbon dioxide, it is also appropriate to mix the hydrogen gas sources or change the hydrogen gas sources during fermentation or during performing the method.
• the hydrogen content in the gas sources may vary greatly without affecting the feasibility of the invention, preferably, the hydrogen comprising real gas comprises at least 80% of hydrogen, more preferably at least 85%o, even more preferably at least 90%>, most preferably at least 95%. If it is necessary to purify the hydrogen comprising real gas prior to use in the method, this may be done according to any of the techniques mentioned above or known in the art. Also for hydrogen real gas, it is not necessary to determine the exact composition of the real gas or determine the exact hydrogen content in the real gas which is also a very important advantage of the method of the invention over the methods known in the art if the partial pressure ratio is controlled.
• Electrolysis in the sense of the invention means a method or process which uses an electric current to induce an otherwise non-spontaneous chemical reaction. In the process, an electric current passes through a substance, thereby causing a chemical change of said substance, usually the gaining or losing of electrons. Electrolysis requires an electrolytic cell, such as an electrolyser, e.g. Hofmann voltameter, consisting of separated positive and negative electrodes (anode and cathode, respectively) immersed in an electrolyte solution containing ions or in a molten ionic compound. Reduction occurs at the cathode, where electrons are added that combine with positively charged cations in the solution.
• an electrolytic cell such as an electrolyser, e.g. Hofmann voltameter, consisting of separated positive and negative electrodes (anode and cathode, respectively) immersed in an electrolyte solution containing ions or in a molten ionic compound. Reduction occurs at the cathode, where electron
• Standard or high-pressure electrolyser can be obtained from various manufacturers such as from Hydrogen Technologies (Notodden/Porsgrunn, Norway), Proton Energy Systems (Wallingford, CT, USA), Heliocentris Energy Solutions AG (Berlin, Germany), Claind (Lenno, Italy), Hydrogenics GmbH (Gladbeck, Germany), Sylatech Analysentechnik GmbH (Walzbachtal, Germany), h-tec Wasserstoff- Energy-Systeme GmbH (Luebeck, Germany), zebotec GmbH (Konstanz, Germany), H 2 Logic (Herning, Denmark), QuinTech (Goeppingen, Germany), and electrolysis may be performed according to the manufacturer ' s instructions.
• Hydrogen can also be produced by the electrolysis of brine (i.e. a water sodium chloride mixture). This electrolysis is commonly used for the production of chlorine, wherein hydrogen is produced as a side product.
• brine i.e. a water sodium chloride mixture
• This electrolysis is commonly used for the production of chlorine, wherein hydrogen is produced as a side product.
• the passed through current leads to the oxidation of chloride ions to chlorine.
• the overall reaction equation is: 2 NaCl + 2 H 2 0 ⁇ Cl 2 + H 2 + 2 NaOH.
• the water and/or brine for the electrolysis may be obtained by any source, such as tap water, from rivers, lakes, sea water, rain or waste water from industrial processes (here the explanations of industrial waste gas apply accordingly).
• the water and/or brine may be purified by distillation, filtration and/or centrifugation and other means which are well known to a person skilled in the art and can for example be taken from "Water Treatment, Principles and Design", 2. edition, 2005, John Wiley & Sons.
• the energy for any industrial process mentioned herein which provides the gaseous carbon containing educt or any other precursor of the method e.g. hydrogen, oxygen, carbon dioxide or else, in particular for the electrolysis of water or brine to provide hydrogen and/or oxygen which may then be used for gasification or combustion processes to provide carbon dioxide, or for the bioreactor which requires energy, e.g.
• the energy for the industrial processes is from a renewable energy source, in particular the energy for the hydrogen-producing electrolysis, for gasification or combustion is from a renewable energy source.
• Renewable energy is energy which comes from natural resources or sources and is renewable, i.e. naturally replenished.
• Renewably energy comprises wind power, solar power, geothermal power, water/hydro power, wave power, tidal power, bio fuels, bio mass and combinations thereof.
• the energy source is selected from the group consisting of solar energy, magnetic, resonance energy, wind, water and geothermal power.
• a "device for generating electric energy from a renewable and/or non-renewable energy source” are the reactors or devices, i.e. respective power plants, which convert the energy of the energy source, such as thermal, kinetic, chemical and/or mechanical energy into electric energy. Said power plants may be large-scale power plants or household-scale devices or else.
• Solar powered electrical generation relies on concentrated solar heat (e.g. heat engines) and solar power (e.g. photovoltaics in solar panels).
• a device for generating electric energy from solar power may for example be selected from photovoltaics, concentrated solar power system or else and may be obtained for example from Bosch Solar Energy AG (Erfurt, Germany), sonnen systeme
• Solar hot water system solar heat engines may be used for heating the bioreactor of the system of the invention.
• Biomass is also regarded as renewable energy source and is biological material from living or recently living organisms, such as wood, waste, (hydrogen) gas, and alcohol fuels.
• Living or recently living organisms comprise plants and trees, such as miscanthus, switchgrass, hemp, corn, poplar, willow, sorghum, sugarcane, eucalyptus or palms, but also forest residues, e.g. dead trees, branches and tree stumps, yard clippings, wood chips, garbage, plant or animal matter used for production of fibres or chemicals, and biodegradable waste that can be burnt as fuel.
• biomass e.g.
• bioethanol, biobutanol (biogasoline), biogas, syngas, bioethers, biodiesel or solid biofuels as wood pellets, cube or pucks are a wide range of fuels which are in some way derived from biomass.
• the energy for the production of biomass or biofuel is thus derived from the sun and converted by photosynthesis into the biological material.
• Devices for generating electric energy from biomass or biofuel comprise biomass power plants, and can be obtained for example from SBBiogas GmbH (Marktbreit, Germany), Evonik New Energys GmbH (Saarbruecken, Germany) or Envi Con & Plant Engineering GmbH (Nuremberg, Germany).
• a device for generating electric energy from wind power may for example be selected from wind turbine, wind mill, wind pump or drainage.
• Suppliers of said devices are for example for small applications: Superwind (Bruehl, Germany), Braun Windturbinen (Nauroth, Germany), Urban Green Energy (New York, USA) and Helix Wind (Poway, USA).
• Exemplary suppliers of wind turbines for larger applications are Vestas (Randers, Denmark), GE Wind Energy (Fairfield, USA), Sinovel (Beijing, China), Enercon (Aurich, Germany), Goldwind (Urumqui, China), Gamesa (Zamudio, Spain) and Siemens Wind Power (Brande, Denmark).
• Geothermal electricity is electricity generated from geothermal energy.
• a device for generating electric energy from geothermal power may for example be selected from dry steam power plant, flash steam power plant, hybrid plant and binary cycle power plant and may be obtained for example from Ansaldo Energia (Genoa, Italy) or ECONAR (Maple Grove, MN, USA).
• hydroelectric power stations In general, the production of hydro electricity uses the gravitational force of falling or flowing water.
• Conventional hydroelectric power stations use the potential energy of dammed water for driving a water turbine and generator. The energy amount obtained in this way depends on the water volume and the difference in height between the source and the water's outflow.
• Pumped-storage hydroelectric power stations produce electric energy to supply high peak demands by moving water between reservoirs of different levels.
• water is released back into the lower reservoir through a turbine which is connected to a generator or preferably may be connected to the bioreactor or device for producing hydrogen and/or oxygen by the electrolysis of water and/or brine.
• run-of-the-river hydroelectric stations small, micro or pico hydro stations are available.
• a device for generating electric energy from water/hydro power may for example be obtained from AC-Tec G.m.b.H (Kaltern, Italy) or EnBW Energy Baden- Wurttemberg AG (Karlsruhe, Germany).
• Wave power denotes the energy of ocean surface waves.
• a device for generating electric energy from wave power may for example be selected from point absorber or buoy, surfacing following or attenuator oriented parallel to the direction of wave propagation, terminator, submerged pressure differential, oriented perpendicular to the direction of wave propagation, oscillating water column, or an overtopping facility.
• the devices comprise a hydraulic ram, elastomeric hose pump, pump-to- shore, hydroelectric turbine, air turbine or a linear electrical generator, optionally also a parabolic for increasing the wave energy at the point of capture.
• Such devices may be located close to shoreline, near shore or offshore. Suppliers are for example Ocean Navitas Ltd. (Marton, UK), AWS Ocean Energy Ltd.
• a device for generating electric energy from tidal power which uses the daily rise and fall of water due to tides may for example be selected from tidal power stations, undershot waterwheels, dynamic tidal power plants, tidal barrage, tidal lagoons and turbine technology, such as axial turbines or crossflow turbines.
• Suppliers are for example BioPower Systems (Mascot, Australia), Neptune Renewable Energy Ltd. (North Ferriby, UK) or Clean Current Power Systems Incorporated (Vancouver, Canada).
• Carbon dioxide and hydrogen are both required for methane production which is a preferred embodiment of the present invention. Both gases are generally fed into the reaction vessel of the invention at a certain gas feed rate as described above.
• both gases may be introduced into the reaction vessel according to the desired ratio of their partial pressures or according to a certain volumetric ratio. They may be pure or contaminated with other gases tolerated by the system, i.e. not irreversibly harmful to the methanogenic microorganisms. A contamination with other gases may e.g. occur when industrial waste gases of carbon dioxide from the atmosphere are used. Positively, this also reduces the release of greenhouse gases or removes carbon dioxide from the atmosphere.
• the gases are partially dissolved in the medium or reaction medium of the invention which comprises the methanogenic microorganisms. The dissolved part of the gases is then taken up by the microorganisms of the invention and converted into methane, subsequently.
• the gases may be fed separately into the reaction vessel or be mixed outside the reaction vessel in a feed rate which is at least 0.5 wm or 1 wm in total, is at least 1.1 wm in total, preferably is at least 1.2 wm in total, 1.3 wm in total, 1.4 wm in total, more preferably is at least 1.5 wm in total, 1.6 wm in total, 1.7 wm in total, 1.8 wm in total, 1.9 wm in total, most preferably is at least 2.0 wm in total or is at least 2.1, 2.3, 2.5, 2.7, 2.8, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 7.0, 7.5, 8.0, 9.0, 10.0, 12.5, 15.0, 17.5, or at least 20.0 wm in total or higher, or the gas feed rate of hydrogen and carbon dioxide or carbon monoxide, i.e.
• the sum gas feed rate of hydrogen and carbon dioxide or carbon monoxide i.e. the gas feed rate of hydrogen plus the gas feed rate of carbon dioxide or carbon monoxide, into the reaction vessel is in the range of 1.0 wm to 25 wm in total, preferably is in the range of 1.2 wm to 100.0 wm in total 1.2 wm to 25.0 wm in total, more preferably is in the range of 1.5 wm to 15.0 wm in total, even more preferably is in the range of 1.7 wm to 10.0 wm in total, most preferably is in the range of 2.0 wm to 8.0 wm in total, optionally in a ratio which results in a certain partial pressure ratio or certain volumetric ratio and then fed in a mixture.
• the in-gas or gas feed of hydrogen and carbon dioxide or monoxide always denotes the total amount of hydrogen and carbon dioxide or monoxide provided to the methanogenic microorganisms.
• it is suitable to either mix the two gases hydrogen and carbon dioxide prior to the introduction into the reaction vessel or to introduce both gases separately via two different gas feed lines to the reaction vessel or to introduce the two gases timely one after another, as long as the gas feed rate is maintained, and optionally the volumetric ratio of hydrogen to carbon dioxide or the ratio of the partial pressures of hydrogen to carbon dioxide is maintained as described herein.
• the mix-ratio may be adjusted in real time according to the determined partial pressure ratio or volumetric ratio of hydrogen and carbon dioxide inside the reaction vessel as desired by the skilled person and as described above.
• a “fermentation condition” or “state condition” is a parameter of the method of the condition which may be adjusted by the skilled person who performs the method of the invention.
• “fermentation conditions” in the sense of the invention are all standard fermentation conditions which are known to a person skilled in the art of microorganism fermentation (Bailey, Ollis (1986) Biochemical Engineering Fundamentals, McGraw-Hill Science, New York, USA).
• Examples of fermentation conditions are the gas or liquid limitation, phosphorous feed rate, biomass production rate, nitrogen concentration, the feed rate of the gaseous carbon containing educt, liquid compound feed rates, partial pressures of hydrogen and carbon dioxide and thus the ratio of the partial pressures of hydrogen and carbon dioxide, the oxidation reduction potential, the pH value, biomass concentration, temperature, pressure, stirring speed, medium composition, gas feed rates, medium exchange rates and others.
• the fermentation conditions which are required for optimal cell performance regarding cell growth or methane production, may fluctuate and vary and will have to be adjusted accordingly by the experimenter.
• the temperature inside the reaction vessel depends on the microorganism which is used for the method of the invention and the skilled person is familiar with techniques how to determine the optimal temperature for cultivating a microorganism. In general, a temperature of 37 ⁇ 1 °C is sufficient for the used microorganisms. However, for methanogenic archaea the temperature may be in the range from 40 °C to 100 °C. Preferably, for mesophilic microorganisms, such as Methanosarcinia barkeri or Methanococcus maripaludis, the temperature of the biomass in the reaction vessel is in the range of about 30 °C to about 40 °C, more preferably in the range of about 35 °C to about 37 °C.
• thermophiles such as Methano- thermobacter marburgensis, Methanobacterium thermoautotrophicus or Methano- thermobacter thermoautotrophicus
• the temperature inside the bioreactor was about 60 °C to 67 °C, preferably about 65 ⁇ 1 °C, or about 85 °C to 90 °C for organisms such as Methanocaldococcus jannaschii.
• Methanothermobacter marburgensis also grows and produces methane very well at lower temperatures of about 45 ⁇ 1 °C to about 55 ⁇ 1 °C.
• the method of the invention may also be performed at 37 ⁇ 1 °C, 45 ⁇ 1 °C, 47 ⁇ 1 °C, 49 ⁇ 1 °C, 50 ⁇ 1 °C, 52 ⁇ 1 °C, 54 ⁇ 1 °C, 55 ⁇ 1 °C, 57 ⁇ 1 °C, 59 ⁇ 1 °C, 60 ⁇ 1 °C, 62 ⁇ 1 °C, 64 ⁇ 1 °C, 67 ⁇ 1 °C, 69 ⁇ 1 °C or 70 ⁇ 1 °C or at a temperature in the range of 45 ⁇ 1 °C to 67 ⁇ 1 °C, 50 ⁇ 1 °C to 65 ⁇ 1 °C inside the reaction vessel.
• the stirring speed is adjusted to a value which is optimal for a high gas liquid mass transfer in the volume of the respective reaction vessel, in a typical fermentation the stirring speed is at least 20 rpm or 50 rpm, preferably, at least 500 rpm, more preferably at least 1000 rpm, even more preferably at least 1500 rpm, most preferred, the stirring speed is at least 1500 rpm or the maximum which can be applied by the stirrer used in the reaction vessel of the bioreactor.
• the stirring speed in particular of large- volume reaction vessels such as 15,000 L, may be significantly less than 1500 rpm, for example in the range between 20 rpm to 100 rpm, e.g.
• the pH of the cell culture inside the reaction vessel should be broadly in the neutral range.
• the pH value of the invention is in the range of 4.0 to 9.0, more preferably, the pH value is in the range of 5.0 to 8.0 or 5.5 to 7.8, even more preferably, the pH value is in the range of 6.4 to 7.6, in particular preferably, the pH value is in the range of 6.7 to 7.2, most preferably, the pH value is about 6.5 ⁇ 0.5, 6.9 ⁇ 0.5 or 7.0 ⁇ 0.5.
• methanogenesis and biological methanation are anaerobic processes and inhibited by oxygen.
• certain amounts of oxygen may be tolerated by the system.
• a common oxygen scrubber may be used to remove oxygen from the in-gases, i.e. from the hydrogen and carbon dioxide feed.
• a common oxygen scrubber may be used.
• WO 2008/094282 have shown that even 100% oxygen feed for more than 10 hours only stopped methane production for a that time and that the system soon recovered and started to again produce methane. In no way, the system will be permanently damaged. Thus, the system is very robust to oxygen contamination and oxygen is tolerated to a certain extend. It is, however, preferred to have a very low oxygen contamination inside reaction vessel, preferably below 2%.
• the pressure may be adjusted to a value of above normal atmospheric pressure, or to a value of at least 1 bar, 1.2 bar, 1.4 bar, 1.5 bar, 1.6 bar, 1.7 bar, 1.8 bar, or at least 1.9 bar, preferably at least 2.0 bar, 2.1 bar, 2.2 bar, 2.25 bar, 2.3 bar, 2.4 bar, 2.5 bar, 2.6 bar, 2.7 bar, 2.8 bar, 2.9 bar, 3.0 bar, more preferably of at least 3.2 bar, 3.4 bar, 3.6 bar, 3.8 bar, 4.0 bar, 4.25 bar, 4.5 bar, 4.75 bar, or of 5 bar.
• the absolute pressure inside the reaction vessel may also be in the range of 1.0 bar to 1200 bar, 1.2 bar to 1000 bar, 1.3 bar to 500 bar, preferably in the range of 1.5 bar to 1000 bar.
• the range of 1.5 bar to 5 bar has been calculated by the inventors to be optimal for the production of methane and would be well tolerable by the microorganisms of the present invention.
• some methanogenic microorganisms, such as methanogenic archaea are known to tolerate very well extremely high pressures.
• the pressure values mentioned before and in the following may be applied in the method of the invention for producing methane.
• Methanogenic archaea which are extremely tolerable to high pressures are naturally derived from a high pressure environment, such as from deep sea.
• Absolute pressure in the sense of the invention denotes the total pressure which is inside the reaction vessel including the normal atmospheric pressure and the additional pressure applied by the method operator via a device such as the device according to the invention for providing, controlling and/or measuring an absolute pressure inside the reaction vessel of at least 1 bar or higher as described above.
• a person skilled in the art knows very well that the normal atmospheric pressure may vary with time and also depending on the location where a method is performed.
• Atmospheric pressure is defined as the force per unit area exerted onto a surface by the weight of air above that surface in the atmosphere. In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the mass of air above the measurement point. As elevation increases, there is less overlying atmospheric mass, so that pressure decreases with increasing elevation.
• "normal atmospheric pressure” in the sense of the invention is generally a pressure of 1 ⁇ 0.05 bar, however, depending on the location of operation "an absolute pressure above normal atmospheric pressure” denotes any additional increase of the pressure inside the reaction vessel compared to the outside of the reaction vessel. A person skilled in the art knows very well how to determine or find out the pressure which applies to his location.
• the pressure inside the reaction vessel may also be given in the unit “barg" which denotes the pressure inside the reaction vessel independent from the atmospheric pressure. In this case, the local atmospheric pressure value has to be added to the pressure given as "barg".
• Exemplary suppliers of pressure controllers are e.g. LABOM Mess- und Regel- technik GmbH (Hude, Germany), KROHNE Messtechnik GmbH (Duisburg, Germany) or others.
• the gas feed rate of hydrogen and carbon dioxide or monoxide (carbon dioxide or carbon monoxide or a mixture thereof is also denoted herein as "carbon dioxide/monoxide”) into the reaction vessel is at least 0.5 wm in total, 1.0 wm in total, at least 1.2 wm in total, at least 2, 2.5, 3, 3.5, 4, 4.5, at least 5 wm in total or at least 6, 7, 8, 9, 10, 15, 20 wm in total, and inside the reaction vessel an absolute pressure of at least 1 bar, 1.2 bar, 1.4 bar, 1.5 bar, 1.6 bar, 1.7 bar, 1.8 bar, or at least 1.9 bar, preferably at least 2.0 bar, 2.1 bar, 2.2 bar, 2.25 bar, 2.3 bar, 2.4 bar, 2.5 bar, 2.6 bar, 2.7 bar, 2.8 bar, 2.9 bar, 3.0 bar, more preferably of at least 3.2 bar, 3.4 bar, 3.6 bar, 3.8 bar, 4.0 bar, 4.25
• the gas feed rate (wm) is controlled via typical mass flow controllers which are well known to a person skilled in the art.
• Typical mass flow controllers are e.g. supplied by Bronkhorst (Kamen, Germany), Wagner (Offenbach, Germany), Brooks
• the batch mode typically no mass (solid, liquid, gaseous) transfer into the reaction vessel or into the bioreactor is allowed.
• the system comprising the bioreactor and the microorganism cells in the reaction vessel is closed.
• all compounds still need to be fed into the reaction vessel and be provided to the microorganisms inside the reaction vessel or not. If this is the case, the fermentation mode may also be regarded as semi-batch mode.
• the continuous cultivation mode is characterized by a continuous supply with fresh medium or medium components, gases or other substances, in particular the phosphorous containing compound, which are continuously required by the cells in the reaction vessel, such as hydrogen, carbon dioxide or medium.
• the reaction volume i.e. the culture volume
• the system comprising the bioreactor and the methanogenic cells in the reaction vessel can be regarded as being open and components are exchanged.
• these two fermentation modes describe a setting of the bioreactor comprised in the system of the invention.
• Batch mode conditions are very often applied during the initial phase when cells are dividing and biomass is increasing exponentially, whereas continuous cultivation conditions are often applied when cell growth stagnates or is constant, such as in the methane production phase.
• the cells are usually kept over a longer period of time for producing the desired product, here methane.
• the bioreactor comprises 1) at least one bioreactor comprising a reaction vessel suitable for growing, fermenting and/or culturing microorganisms,
• At least one device for providing, measuring and adjusting a feed of a gaseous carbon containing educt, preferably of carbon dioxide, carbon monoxide or methane, into the reaction vessel,
• At least one device for generating electric energy from a renewable and/or non-renewable energy source optionally at least one device for generating electric energy from a renewable and/or non-renewable energy source
• the gaseous carbon containing educt is selected from the group consisting of carbon dioxide, carbon monoxide, methane, ethane, propane, butane, ethene, propene, butane, ethyne, propyne, butyne, cyclopropane, eye lo butane, propadiene, butadiene and mixtures thereof, wherein the carbon containing product is not methane if the carbon containing educt is methane, preferably the gaseous carbon containing educt is carbon dioxide or carbon monoxide.
• Suitable for fermenting, growing and culturing the microorganisms in the sense of the invention denotes that the reaction vessel allows to maintain a surrounding or condition which generally promotes cell growth, if desired, fermentation and culturing of the cells. This comprises, for example, maintaining the culture at a predetermined temperature, stirring the cells and providing substances which are essential for the metabolism of the cells, e.g. the phosphorous containing compound according to the experimenter ' s needs, gases, e.g. the gaseous carbon containing educt, medium or medium components, such as nitrogen.
• the reaction vessel may be any container wherein microorganism may be cultured, grown and fermented.
• the reaction vessel is made of glass, plastic or steel depending on the pressure which is applied to the culture of microorganisms.
• the reaction vessel may be connected to all necessary devices and measuring probes for adjusting the fermentation conditions of the invention to grow the microorganisms up to a desired biomass concentration and/or to switch between gas and liquid limitation of the microorganisms or to keep the cells in one of the states over a period of time which may be selected by the experimenter.
• the period of time may be understood as minutes or hours or days or even longer.
• the method of the invention also allows keeping methanogenic microorganisms in a non-methane-producing state without further cell growth.
• the bioreactor of the invention may be derived from a standard bioreactor suitable for culturing, fermenting, growing and/or processing of a biomass comprising the microorganisms of the invention.
• Suppliers of standard bioreactors are, for example, Applikon Biotechnology B.V. (Schiedam, The Netherlands), Infers (Bottmingen, Switzerland), Bioengineering (Wald, Switzerland) and Sartorius Stedim Biotech GmbH (Gottingen, Germany).
• the bioreactor i.e. reactor comprises at least one vessel or container suitable for culturing, fermenting and/or processing of the methanogenic microorganisms, i.e. the reaction vessel of the invention.
• the bioreactor may also comprise two or more reaction vessels. These reaction vessels may be linked, for example via tubes, pipes or else, to transport the cell culture comprising the suspension of methanogenic microorganisms from one reaction vessel to the other or back if needed.
• the bioreactor may be equipped with various means and devices for adjusting and monitoring the fermentation conditions in the bioreactor and in the reaction vessel or in the reaction vessels.
• the bioreactor comprises the components and devices which are necessary to culture the microorganisms of the invention in a way that they are able to grow and produce the carbon containing product and what else is necessary to perform the method of the invention.
• an ideal stirred tank bioreactor is used for the method of the invention.
• This bioreactor comprises a reaction vessel with head plate and multiple inlet and outlet ports. The probes for temperature, nitrogen, pH and oxidation reduction potential measurement are fitted to the ports.
• the bioreactor is further equipped with an agitator with impeller blades (Rushton) on at least three levels.
• agitator systems are available from EKATO HOLDING GmbH, Freiburg im Breisgau, Germany.
• Medium and liquid reducing agent is fed via a pump, controlled gravimetrically or with a flow meter or is needed to control the oxidation reduction potential.
• Acid or base is added by titration to control pH as desired.
• Gas liquid mass transfer denotes the transfer of mass in general, i.e.
• phase is to be understood in its thermodynamic meaning and not to be mixed up with a fermentation "phase of the invention".
• phase is to be understood in its thermodynamic meaning and not to be mixed up with a fermentation "phase of the invention".
• phase of the invention Of particular importance for the method of the invention is the transfer of the gaseous carbon containing educt, e.g. carbon dioxide, and optionally hydrogen, from the gaseous phase to the liquid phase which comprises the biomass suspension and the microorganism inside the reaction vessel, and the transfer of methane from the liquid phase to the gaseous phase inside the reaction vessel to leave the reaction vessel.
• the gas liquid mass transfer indirectly influences the mass transfer from the liquid to the solid phase, such as the biomass.
• the bioreactor and also the reaction vessel comprised in the bioreactor may be connected to various sources of gaseous carbon containing educts, hydrogen and carbon dioxide, nitrogen, real gases and others through the at least one device for introducing of gaseous substances and further to automated systems for feeding liquid, gaseous and solid substances and materials into the bioreactor via peristaltic pumps and others. Also devices and means may be attached to the bioreactor which measure the composition of the educt gases for the method and which further improve the quality of the gas to be fed into the reaction vessel, in case of a real gas application, or the off-gas.
• the bioreactor also comprises a device for removing and measuring the off-gas from the reaction vessel.
• the off-gas composition may be measured for example by an individually applied gas analyser system, such as supplied by Blue- Sens gas sensor GmbH (Herten, Germany).
• the off-gas produced by the method of the invention may optionally be further processed by standard means, such that hydrogen, nitrogen and carbon dioxide, which were not converted into methane, are separated from methane and/or from each other. Hydrogen, nitrogen and carbon dioxide which are comprised in the off-gas are preferably recycled in that they are fed back into the reaction vessel of the invention.
• Hydrogen may be separated from the off-gas of the invention using a separation device such as a membrane which allows the small hydrogen molecules to pass through the pores of the membrane and does not allow the passage of larger molecules or by classical condensation using a cold finger or else. Aforementioned methods are of course also applicable to increase a hydrogen content in the used hydrogen educt gas or real gas.
• a separation device such as a membrane which allows the small hydrogen molecules to pass through the pores of the membrane and does not allow the passage of larger molecules or by classical condensation using a cold finger or else.
• Aforementioned methods are of course also applicable to increase a hydrogen content in the used hydrogen educt gas or real gas.
• Carbon dioxide may be separated from the off-gas of the invention for example with an absorbing medium which selectively absorbs carbon dioxide or which selectively absorbs gases other than carbon dioxide from the off-gas or by any method described above. Separating devices for phosphorous and nitrogen are also known to a person skilled in the art. Both hydrogen and carbon dioxide which have been recovered from the off-gas may be used as educts in
• nitrogen and carbon dioxide are removed from the off-gas also other gases such as water vapour and other gases may be removed to increase the percentage of methane in the off-gas for methane or natural gas based applications.
• gases such as water vapour and other gases
• Most preferred is a percentage of methane in the off-gas which closely resembles natural gas, i.e. is between 40% and 100%, preferably between 60% and at least 90%, and more preferably at least 95%. Using the method of the invention it is even possible to reach 97% methane or more Vol-% methane.
• the bioreactor may further comprise devices which allow the sterile and anaerobic entry and exit of substances required for the method of the invention.
• substances required for the method of the invention are for example the biomass comprising the microorganisms, the medium or medium components, water, gases, such as the gaseous carbon containing educt, the carbon containing product, hydrogen, carbon dioxide, methane, hydrogen sulphide, nitrogen or mixtures thereof, and compositions which might contain a mixture of all these substances.
• the bioreactor of the invention is further equipped with discharge lines, pumps and compressors.
• the bioreactor at least comprises all devices which are necessary to feed the gases which are required for the method of the invention, i.e. the gaseous carbon containing educt, optionally hydrogen and carbon dioxide, phosphorous in gaseous, dissolved or solid form, liquid substances, such as the cell culture suspension and fresh medium or medium components, devices for removing the off-gas of the invention, excess liquid and gaseous parts from inside the bioreactor, and all other components which are necessary to control the fermentation parameters of the invention.
• the bioreactor and reaction vessel is suitable for culturing, fermenting and/or processing of a biomass comprising microorganisms under high pressure, e.g. a pressure higher than the normal atmospheric pressure.
• the bioreactor comprises a reaction vessel or housing made of a material which is suitable for high pressure and fulfils the requirements of occupational safety and follows work safety rules.
• the material of the housing may be selected from the group comprising steel, such as stainless steel according to European standard EN 10088, for example 1.43XX, 1.44XX, 1.45XX, or else.
• a reaction vessel of the bioreactor of the invention for culturing microorganisms may have different volumes, wherein larger volumes are preferred for the industrial production of methane.
• the industrial production of methane as a preferred embodiment of the present invention also comprises the methane production in decentralized household applications, wherein the volume of the reaction vessel comprised in the bioreactor may be in the smaller and middle range, and largely depends on the particular methane amount which is needed and the available space.
• the volume of the reaction vessel is at least 1 L, preferably at least 5 L, 10 L, 25 L, more preferably at least 50 L, 100 L, 500 L, 1000 L, even more preferably the volume of the reaction vessel is at least 5000 L, 10,000 L, 20,000 L, 50,000 L, most preferably the volume of the reaction vessel is at least 100,000 L.
• more than one reaction vessel is comprised in the bioreactor of the invention or more than one bioreactor comprising one or more reaction vessels are combined, for example attached serially or in parallel. In a serial arrangement, the volume of the reaction vessel is typically smaller, i.e.
• the volume of the reaction vessel may also be larger, as indicated above, for example at least 1 L, preferably at least 5 L, 10 L, 25 L, more preferably at least 50 L, 100 L, 500 L, 1000 L, even more preferably the volume of the reaction vessel is at least 5000 L, 10,000 L, 20,000 L, 50,000 L, or the volume of the reaction vessel is at least 100,000 L.
• a serial or parallel arrangement allows using the carbon containing product, if gaseous, hydrogen, nitrogen, methane and carbon dioxide comprising off-gas as new educt gases or in-gas for the next following reaction vessel and bioreactor.
• the methane is removed from the off-gas before it is re-used as in-gas.
• educts i.e. the gaseous carbon containing educt, such as carbon dioxide, and hydrogen, which have not been converted into methane or else in the preceding reaction vessel, may again be used.
• the fermentation conditions may be applied individually. It is also possible to use different microorganism species and mixtures thereof in each of the reaction vessels.
• the bioreactor is designed in a way that the gaseous carbon containing educt, e.g. carbon dioxide, the phosphorous containing compound, and, if applicable, the hydrogen released from the reaction vessel in the off-gas of the invention is re-used in the method of the invention.
• the gaseous carbon containing educt e.g. carbon dioxide, the phosphorous containing compound, and, if applicable, the hydrogen released from the reaction vessel in the off-gas of the invention.
• all educts are recycled.
• the system further comprises at least one device for oxygen enriched combustion or gasification for producing carbon dioxide.
• the system comprises at least one device for delivery, recovery, purification, measuring, enriching, storing, recycling and/or further processing of a member selected from the group consisting of off-gas, water, nitrogen, oxygen, chlorine, H 2 S, sodium sulphide, microorganisms, preferably methanogenic microorganisms, more preferably methanogenic archaea, medium and medium components, methane and other substances as of use in the method of the invention to or from the reaction vessel and bioreactor.
• the renewable energy source may comprise solar energy, wind power, wave power, tidal power, water/hydro power, resonance energy, magnetic energy, geothermal energy, biomass and/or bio fuel combustion.
• the bioreactor may further comprises at least one device for providing, controlling and/or measuring an absolute pressure inside the reaction vessel of above normal atmospheric pressure or of at least 1 bar, 1.2 bar, 1.4 bar, 1.5 bar, 1.6 bar, 1.7 bar, 1.8 bar, or at least 1.9 bar, preferably at least 2.0 bar, 2.1 bar, 2.2 bar, 2.25 bar, 2.3 bar, 2.4 bar, 2.5 bar, 2.6 bar, 2.7 bar, 2.8 bar, 2.9 bar, 3.0 bar, more preferably of at least 3.2 bar, 3.4 bar, 3.6 bar, 3.8 bar, 4.0 bar, 4.25 bar, 4.5 bar, 4.75 bar, or 5 bar, 7 bar, 8 bar, 9 bar, 10 bar, 12 bar, 15 bar, 16 bar, 20 bar or at least 25 bar or in the range of 1.0 bar to 1200 bar, 1.2 bar to 1000 bar, 1.3 bar to 500 bar, preferably in the range of 1.5 bar to 1000 bar, preferably the absolute pressure is in the range of 1.5 bar to 5 bar and more preferably the range of 5 to 12 bar.
• Said device for providing, controlling and/or measuring an absolute pressure inside the reaction vessel is also suitable for providing and maintaining absolute pressures in the range of 1.0 bar to 1200 bar, 1.2 bar to 1000 bar, 1.3 bar to 500 bar, preferably in the range of 1.5 bar to 1000 bar.
• the range of 1.5 bar to 5 bar has been calculated by the inventors to be optimal for the production of the carbon containing product and would be well tolerable by the microorganisms of the present invention, in particular if the microorganisms are archaea.
• Figure 4 Table covering data of verification run for CH4 production at
• Figure 5 Figure 5 depicts the signals obtained in the verification experiment as indicated: G in [NL/min], CH 4 [Vol.%], C0 2 [Vol.%], H 2 [Vol.%], MER [mmol ⁇ L ⁇ h 1 ].
• microorganism used in all the experiments presented in this work is a hydrogenotrophic, thermophilic and methanogenic archaeon, strain Methanothermo- bacter marburgensis DSM 2133 (Schonheit et al. (1980) Arch. Microbiol.,
• the software MODDE 9.0 (UMETRICS, Umea, Sweden) was used to generate a bi- variate 3 level optimization CCF design.
• the choices for the design space are based on preliminary knowledge and described step wisely in the following section.
• the basal medium recipe was modified from the existing one to contain KH2PO4, NaCl and TE only. TE concentration was maintained constant in every experiment.
• NaHC0 3 was removed from the basal medium recipe as carbonate is supplemented by CO2 gassing.
• the reference medium composition available in literature was set as the up-up edge of the design space.
• the concentration of KH2PO4 and NaCl in basal medium was adjusted in order to provide at the fixed dilution rate (D re f) for varying specific elemental feed rates in the bioreactor.
• a 1 :20 reduction of KH2PO4 and NaCl concentrations in the basal medium was determined by a pre-screening dynamic experiment (not shown).
• a logarithmic transform was applied to the input parameters. This allowed placing centre point experiments at the logarithmic mean rather than at the arithmetic mean. This was done in order to enhance the resolution in the region of low feeding rates (region of interest) while not affecting the orthogonality of the design space.
• a bi-variate 3 level optimization composite face centred (CCF) design was selected. This allows also the resolution of interaction and quadratic terms in the model.
• the following two controlled factors were selected as input parameters: CKH2PO4 and CNaci in [g L "1 ].
• DoE was used to carry out a multivariate optimization of the basal medium composition.
• MODDE 9.0 UMETRICS, Umea, Sweden
• the following responses were chosen for the DoE because they reflect process performance and physiology:
• the second model describes how qCH 4 varies as a function of DoE parameters. It can be seen in response contour plot B that qCH 4 varied from 42 up to 129 [mmol g "1 h "1 ]. This three-fold increase proofs the possibility of enhancing the process specific productivity also for gas limited bioprocesses by applying a defined feed strategy. It can clearly be seen looking at B that the parameter influencing mostly qCH 4 was FKH2PO4. On the other hand, FNaci shows an almost insignificant influence. The possibility of controlling the specific productivity of a given microorganism in a bio- process is comparable to the control of the turnover rate of a solid catalytic particle.
• the catalytic "particle” here being a gram of microorganisms dry cell weight can turn over up to three times more substrates to product when the full catalytic activity is exploited. This means that it is possible to grow up to three times less cells while not affecting process performance. This also means, a potential three-fold decrease for nutrients feed compare to the gas limited state and evidence how tendentiously a gas limited bioprocess poorly exploit its full catalytic potential if no specific control strategy is applied.
• NaCl is a salt not necessarily referred primarily to as a substrate.
• concentration affects significantly the osmolality observed in the bioprocess and so physiology of most living organisms. Therefore, further investigation could be required to fully picture the influence of NaCl (and indirectly of osmolality) on process performance and growth attributes of Methanothermobacter marburgensis. Different osmolality might trigger metabolic changes and the microorganism would need to adapt to this varying environment according to literature (Martin et al. (1999) Appl. Environ. Microbiol, 65(5): 1815- 1825, Ciulla et al.
• response contour plot D shows the variation of YX/CH4 [C-mol C-mol 1 ] which reflects the reaction selectivity for the carbon transformation (Seifert et al. (2013) Bioresour. Technol, 136:747-751).
• a substantially gas limited BMPP faced a growth limitation which did not impact MER.
• KH2PO4 was found to be suitable to affect only growth and to not be deleterious in case of limitations for methane formation.
• the limitations on KH2PO4 allowed the uncoupling of growth and CH4 production which was reflected in lower r x for constant MERs.
• the trend observed in D is not surprisingly similar to the one observed in response contour plot C as YX/CH4 is the ratio between the varying growth rate observed in the design space with the constant MER values.
• FKH2PO4 significantly influenced growth while not impacting MER.
• bioprocess technology seeks scalable parameters the ratio of FKH2PO4 to r x (R(FKH2P04/r x )) was selected for scaling a feeding strategy based on r x . In gas limited state the latter is depending mostly on dilution and gas transfer rate. If R(FKH2P04/r x ) is below 0.05 mol p hos P horous ⁇ mo on "1 then a liquid limitation is expected to occur.
• R(FKH2P04/r x ) is a suitable parameter for scaling and transferring the feeding strategy of biological methane production processes (BMPPs). It allows scaling the feeding strategy independently of dilution and gassing applied to the process but based on growth. In fact, to increase methane off-gas content, gassing rates need to be reduced for a given reactor setup.
• BMPPs biological methane production processes
• this ratio could be used for controlling the desired physiologic state in a BMPP by applying a feed forward approach limiting selectively the microorganism growth.
• This shift of metabolism from gas to liquid limitation was identified in the DoE with the parameters YX/CH4 which under gas limited condition is expected to be
• Figure 5 depicts that by setting R(FKH 2 po4/r x ) to a constant value of 0.2, it was possible to maintain the gas limited state while different process conditions where applied to the BMPP.
• r x can be easily estimated knowing hydrogen transfer rate and dilution rate applied to the process through Yxjcm.
• This Example presents an experimental workflow consisting of an optimization DoE and a verification experiment for developing a scalable strategy for a feeding gas limited bioprocess and exploiting its maximum biocatalytic activity.
• the methodology comprised adapting an optimization DoE by applying a logarithmic transform to the selected input parameters. This allowed having DoE centre points located at the logarithmic mean rather than at the arithmetic mean while keeping orthogonality of the design space for fitting the model by MLRs. This method could be applied both in up or low corners of a DoE space while allowing a greater resolution of the selected responses in the desired plane section of the design space.
• the parameter R(FKH2P04/r x ) was selected for scaling and transferring the feed strategy of BMPP.
• a gas limited state was targeted, so the parameter R(FKH2P04/r x ) was fixed to a value of 0.2 according to the reference experiment while applying a 50% reduction of dilution and gassing rates.

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