"Sorganoli(R)": In-field Production of Ethanol from Sweet Sorghum

Specific objective of the study was to determine if it was really possible to carry out in-field fermentation of sweet sorghum juice to ethanol with little or no process control. The main objectives of present research are to determine the effect of numerous process variables (yeast type, pH, nutrient and agitation) on in-field ethanol production from sweet sorghum and to determine the nutrient stability of sorghum juice. Testing of parameters enabled us to understand the impact of each variable on the fermentation performance and the sugar to ethanol conversion efficiency. Initial laboratory experiments were conducted to screen different types of fermenting microorganism (Zymomonas mobilis, Kluyveromyces marxianus and industrial dry distillers yeast, Saccharomyces cerevisiae), optimum temperature conditions (7, 37, and 7 and 41oC), optimum pH conditions (pH 4.3, 4.3 and 5.4) and the agitation effect. Two in-field factorial design experiments were conducted using various vessel sizes: 3.8 L, 19 L and 209 L with variables being yeast from two different suppliers (Fermax and Superstart Distillers S.cerevisiae), nutrients (with and without urea) and pH (5.4 and 4.3). Results indicated that both varieties of yeast tested were able to carry out fermentation under extreme temperature (7 and 37oC). Maximum ethanol produced was 7.9% w/v in 120 h from an initial sugar concentration of 16%. Fermax yeast showed significantly greater amount of ethanol production compared to other fermenting microorganisms. Other process variables such as scaling-up of fermentation vessel, adding urea or lowering pH did not significantly affect sugar to ethanol conversion efficiency of yeasts. Uniform heat and mass distribution (ethanol and sugars) was observed during fermentation in absence of agitation and scaling-up. Sorghum juice composition was stable under refrigerated conditions. Based upon the experimental findings we are able to conclude that in-field fermentation of sorghum juice is possible with no temperature control, no added nutrients, and no pH adjustment and is potentially a feasible process for ethanol production.Biosystems and Agricultural Engineerin

Critical factors affecting the integration of biomass gasification and syngas fermentation technology

Gasification-fermentation is a thermochemical-biological platform for the production of fuels and chemicals. Biomass is gasified at high temperatures to make syngas, a gas composed of CO, CO2, H2, N2 and other minor components. Syngas is then fed to anaerobic microorganisms that convert CO, CO2 and H2 to alcohols by fermentation. This platform offers numerous advantages such as flexibility of feedstock and syngas composition and lower operating temperature and pressure compared to other catalytic syngas conversion processes. In comparison to hydrolysis-fermentation, gasification-fermentation has a major advantage of utilizing all organic components of biomass, including lignin, to yield higher fuel production. Furthermore, syngas fermentation microorganisms do not require strict CO:H2:CO2 ratios, hence gas reforming is not required. However, several issues must be addressed for successful deployment of gasification-fermentation, particularly those that involve the integration of gasification and fermentation. Most previous reviews have focused only on either biomass gasification or syngas fermentation. In this review, the critical factors that affect the integration of biomass gasification with syngas fermentation, such as carbon conversion efficiency, effect of trace gaseous species, H2 to CO ratio requirements, and microbial preference of carbon substrate, are thoroughly discussed

Critical factors affecting the integration of biomass gasification and syngas fermentation technology

Gasification-fermentation is a thermochemical-biological platform for the production of fuels and chemicals. Biomass is gasified at high temperatures to make syngas, a gas composed of CO, CO2, H2, N2 and other minor components. Syngas is then fed to anaerobic microorganisms that convert CO, CO2 and H2 to alcohols by fermentation. This platform offers numerous advantages such as flexibility of feedstock and syngas composition and lower operating temperature and pressure compared to other catalytic syngas conversion processes. In comparison to hydrolysis-fermentation, gasification-fermentation has a major advantage of utilizing all organic components of biomass, including lignin, to yield higher fuel production. Furthermore, syngas fermentation microorganisms do not require strict CO:H2:CO2 ratios, hence gas reforming is not required. However, several issues must be addressed for successful deployment of gasification-fermentation, particularly those that involve the integration of gasification and fermentation. Most previous reviews have focused only on either biomass gasification or syngas fermentation. In this review, the critical factors that affect the integration of biomass gasification with syngas fermentation, such as carbon conversion efficiency, effect of trace gaseous species, H2 to CO ratio requirements, and microbial preference of carbon substrate, are thoroughly discussed

Critical factors affecting the integration of biomass gasification and syngas fermentation technology

Gasification-fermentation is a thermochemical-biological platform for the production of fuels and chemicals. Biomass is gasified at high temperatures to make syngas, a gas composed of CO, CO2, H2, N2 and other minor components. Syngas is then fed to anaerobic microorganisms that convert CO, CO2 and H2 to alcohols by fermentation. This platform offers numerous advantages such as flexibility of feedstock and syngas composition and lower operating temperature and pressure compared to other catalytic syngas conversion processes. In comparison to hydrolysis-fermentation, gasification-fermentation has a major advantage of utilizing all organic components of biomass, including lignin, to yield higher fuel production. Furthermore, syngas fermentation microorganisms do not require strict CO:H2:CO2 ratios, hence gas reforming is not required. However, several issues must be addressed for successful deployment of gasification-fermentation, particularly those that involve the integration of gasification and fermentation. Most previous reviews have focused only on either biomass gasification or syngas fermentation. In this review, the critical factors that affect the integration of biomass gasification with syngas fermentation, such as carbon conversion efficiency, effect of trace gaseous species, H2 to CO ratio requirements, and microbial preference of carbon substrate, are thoroughly discussed