Gas Fermentation: Difference between revisions

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[[Category:Technologies & Solutions]]

[[Gas Fermentation]] is the production of fuels from [[biomass]] by the use of microorganisms. Biomass is gasified to a mixture of carbon monoxide (CO), carbon dioxide (CO<~~sup~~>2</~~sup~~>), hydrogen (H2), and nitrogen (N2), known as the synthesis gas or [[syngas]]<ref>[https://microbialcellfactories.biomedcentral.com/articles/10.1186/s12934-017-0676-y#Sec11 Gas Fermentation]</ref>. The microorganisms then fix the available carbon contained within the [[biomass]] into platform chemicals, fuels and polymers<ref name="ref1">[https://www.frontiersin.org/articles/10.3389/fmicb.2016.00694/full Gas Fermentation]</ref>. This is achieved via the [[wikipedia:Wood–Ljungdahl pathway| Wood-Ljungdahl Pathway (WLP)]] which is the most efficient known pathway to convert CO<~~sup~~>2</~~sup~~> to secreted organic products<ref>[https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/wood-ljungdahl-pathway Wood-Ljungdahl Pathway]</ref>.

[[Gas Fermentation]] is the production of fuels from [[biomass]] by the use of microorganisms. Biomass is gasified to a mixture of carbon monoxide (CO), carbon dioxide (CO2), hydrogen (H2), and nitrogen (N2), known as the synthesis gas or [[syngas]]<ref>[https://microbialcellfactories.biomedcentral.com/articles/10.1186/s12934-017-0676-y#Sec11 Gas Fermentation]</ref>. The microorganisms then fix the available carbon contained within the [[biomass]] into platform chemicals, fuels and polymers<ref name="ref1">[https://www.frontiersin.org/articles/10.3389/fmicb.2016.00694/full Gas Fermentation]</ref>. This is achieved via the [[wikipedia:Wood–Ljungdahl pathway| Wood-Ljungdahl Pathway (WLP)]] which is the most efficient known pathway to convert CO2 to secreted organic products<ref>[https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/wood-ljungdahl-pathway Wood-Ljungdahl Pathway]</ref>.

=== The Process ===

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The biomass is gasified which results in the carbonaceous material reacting with steam and air at elevated temperature (600-1000°C) and high pressure (>30 bar) to form a [[syngas]] or synthetic gas of variable composition. Excess heat generated from [[gasification]] can be used to generate steam for product distillation and/or electricity.

===== Gas Pre-treatment =====

As well as the main constituents (CO, H2, CO<~~sup~~>2</~~sup~~>), input gas streams can also contain impurities such as particulates, tar and aromatics and other inhibiting gases which need to be removed in order for the microorganisms to operate efficiently. Particulates can be removed by cyclone separators and filters. Tars can be condensed and removed by quenching hot [[syngas]] or alternatively can be reformed by heating at 800-900 °C using olivine, dolomite and nickel compounds as catalysts, producing additional [[syngas]].

As well as the main constituents (CO, H2, CO2), input gas streams can also contain impurities such as particulates, tar and aromatics and other inhibiting gases which need to be removed in order for the microorganisms to operate efficiently. Particulates can be removed by cyclone separators and filters. Tars can be condensed and removed by quenching hot [[syngas]] or alternatively can be reformed by heating at 800-900 °C using olivine, dolomite and nickel compounds as catalysts, producing additional [[syngas]].

===== [[Gas Fermentation]] =====

The treated [[syngas]] is cooled and compressed and then sparged into a bioreactor containing the gas-fermenting microorganisms in an aqueous medium. There is a multitude of variables to consider to ensure the yield of the desired product such as bioreactor design, agitation, gas composition and supply rate, pH, temperature, headspace pressure, oxidation-reduction potential (ORP), nutrients and amount of foaming in the bioreactor.

@@ Line 1: / Line 1: @@
 [[Category:Technologies & Solutions]]
-[[Gas Fermentation]] is the production of fuels from [[biomass]] by the use of microorganisms. Biomass is gasified to a mixture of carbon monoxide (CO), carbon dioxide (CO<sup>2</sup>), hydrogen (H2), and nitrogen (N2), known as the synthesis gas or [[syngas]]<ref>[https://microbialcellfactories.biomedcentral.com/articles/10.1186/s12934-017-0676-y#Sec11 Gas Fermentation]</ref>. The microorganisms then fix the available carbon contained within the [[biomass]] into platform chemicals, fuels and polymers<ref name="ref1">[https://www.frontiersin.org/articles/10.3389/fmicb.2016.00694/full Gas Fermentation]</ref>. This is achieved via the [[wikipedia:Wood–Ljungdahl pathway| Wood-Ljungdahl Pathway (WLP)]] which is the most efficient known pathway to convert CO<sup>2</sup> to secreted organic products<ref>[https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/wood-ljungdahl-pathway Wood-Ljungdahl Pathway]</ref>.
+[[Gas Fermentation]] is the production of fuels from [[biomass]] by the use of microorganisms. Biomass is gasified to a mixture of carbon monoxide (CO), carbon dioxide (CO<sub>2</sub>), hydrogen (H2), and nitrogen (N2), known as the synthesis gas or [[syngas]]<ref>[https://microbialcellfactories.biomedcentral.com/articles/10.1186/s12934-017-0676-y#Sec11 Gas Fermentation]</ref>. The microorganisms then fix the available carbon contained within the [[biomass]] into platform chemicals, fuels and polymers<ref name="ref1">[https://www.frontiersin.org/articles/10.3389/fmicb.2016.00694/full Gas Fermentation]</ref>. This is achieved via the [[wikipedia:Wood–Ljungdahl pathway| Wood-Ljungdahl Pathway (WLP)]] which is the most efficient known pathway to convert CO<sub>2</sub> to secreted organic products<ref>[https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/wood-ljungdahl-pathway Wood-Ljungdahl Pathway]</ref>.
 === The Process ===
@@ Line 11: / Line 11: @@
 The biomass is gasified which results in the carbonaceous material reacting with steam and air at elevated temperature (600-1000°C) and high pressure (>30 bar) to form a [[syngas]] or synthetic gas of variable composition. Excess heat generated from [[gasification]] can be used to generate steam for product distillation and/or electricity.
 ===== Gas Pre-treatment =====
-As well as the main constituents (CO, H2, CO<sup>2</sup>), input gas streams can also contain impurities such as particulates, tar and aromatics and other inhibiting gases which need to be removed in order for the microorganisms to operate efficiently. Particulates can be removed by cyclone separators and filters. Tars can be condensed and removed by quenching hot [[syngas]] or alternatively can be reformed by heating at 800-900 °C using olivine, dolomite and nickel compounds as catalysts, producing additional [[syngas]].
+As well as the main constituents (CO, H2, CO<sub>2</sub>), input gas streams can also contain impurities such as particulates, tar and aromatics and other inhibiting gases which need to be removed in order for the microorganisms to operate efficiently. Particulates can be removed by cyclone separators and filters. Tars can be condensed and removed by quenching hot [[syngas]] or alternatively can be reformed by heating at 800-900 °C using olivine, dolomite and nickel compounds as catalysts, producing additional [[syngas]].
 ===== [[Gas Fermentation]] =====
 The treated [[syngas]] is cooled and compressed and then sparged into a bioreactor containing the gas-fermenting microorganisms in an aqueous medium. There is a multitude of variables to consider to ensure the yield of the desired product such as bioreactor design, agitation, gas composition and supply rate, pH, temperature, headspace pressure, oxidation-reduction potential (ORP), nutrients and amount of foaming in the bioreactor.