Challenges in Syngas Fermentation for Bioethanol Production: Syngas Composition

Energy challenges in developing countries are more significant if they continue to use fossil materials and have an impact on air quality. Lignocellulosic biomass can be an alternative to new renewable sources to replace fossil materials. Indonesia produces various sources of lignocellulosic biomass, which can be used in multiple energy sources such as bioethanol. The hybrid pathway is one of the routes for producing bioethanol. The first stage of the hybrid process is the conversion of biomass into CO, CO2, and H2 (syngas) gas through the gasification process. Then the syngas is converted into bioethanol through fermentation using microorganisms as biocatalysts. The bioethanol production line is the Wood-Ljungdahlii pathway. Factors that affect syngas are the type of biomass (chemical, physical, and morphological properties) and the gasification process (type of gasifier, temperature, gasification agent, and ratio equilibrium (ER)). This paper reviews the challenges in implementing syngas fermentation. In particular, variations in the composition of syngas as a substrate for fermentation.