ABSTRACT
Increasing population, rapid industrialization, and contrivance of new technologies have led to enhanced energy consumption, which further engendered situations like energy crunch and environmental pollution. Due to incessant use, the nonrenewable resources are depleting at a rapid rate and various kinds of noxious gases and contaminants are released into the ecosphere. These conditions have prompted scientists to think about alternate renewable energy resources such as biofuels that are considered as the most viable option. Biofuel production from biomass has been gaining worldwide acceptability from the scientific community. Biofuels are categorized into three divisions: first-generation, second-generation, and third-generation biofuels. Ethanol, biodiesel, green diesel, and biogas are some examples of biofuels. Every year, millions of tons of agricultural biomass are generated. Biomass has been classified into two groups: lignocellulosic and non-lignocellulosic. Complexity and recalcitrancy of biomass necessitate the pretreatment via different methods; i.e., physical, chemical, thermophysical, thermochemical, and biological methods are necessary to make the contents available for further conversion to desired products. Three main approaches for biomass to biofuel conversion are physicochemical conversion, thermochemical conversion, and biochemical conversion. Thermochemical conversion is achieved through pyrolysis, gasification, liquefaction, and combustion processes while biochemical conversion is done through anaerobic digestion and fermentation. The current chapter is aimed at providing a comprehensive overview of various biochemical approaches for the conversion of biomass feedstock to biofuels.
