A Spotlight on Butanol and Propanol as Next-Generation Synthetic Fuels

The exhaustive extraction and prodigious utilization of fossil fuels have led to the large-scale increase in the emissions of greenhouse gases. In addition, the per capita demand of petrochemical resources is escalating due to rapid industrialization and the rising number of vehicles in the transportation sector. There is a growing interest in the development of alternative fuels to reduce the carbon footprint and air pollution caused by the fossil fuels. Biofuels produced from plant residues are carbon neutral and can be produced through biomass-to-liquid and biomass-to-gas conversion technologies. Bioethanol, biopropanol, and biobutanol are some alcohol-based fuels and chemicals that have found multifarious industrial applications. Although bioethanol is blended with gasoline for use as a transportation fuel, it is often criticized over food-versus-fuel debate because of its raw materials being food crops such as corn, sugarcane, and other grains. In addition, butanol and propanol have high potentials over ethanol in replacing gasoline partially or completely due to their advanced fuel properties. This chapter throws light on butanol and propanol as the next-generation synthetic fuels. The aspects discussed in this chapter include their fuel chemistry as well as production technologies from petrochemicals and bio-based feedstocks. The biotechnological developments in the fermentation of lignocellulosic biomass to produce butanol and propanol are provided. The chapter concludes with a note on industrial challenges and future prospects in employing butanol and propanol as commercial biofuels and biochemicals.