Biobutanol: The future biofuel

Emerging interest of economic biobutanol production at industrial level is being stimulated owing to flourishing environmental issues and hiking of price for petroleum-based liquid fuels due to continuous depletion of oil reserves. Moreover, biobutanol also demonstrated various significant properties over bioethanol (commercialized biofuel) such as high calorific value, low freezing point, high hydrophobicity, low heat of vaporization, no need of modification in exiting car engines, less corrosive, no blending limit (can be used up to 100%), its dibutyl ether derivative has potential for diesel fuel, etc. Unfortunately, economic feasibility of biobutanol fermentation is suffering due to low butanol titer as butanol itself acts as inhibitor during fermentation. To overcome this problem several genetic and metabolic engineering strategies are being tried. Still, none of the attempts are successful efficiently as butanol disrupts the cytoplasmic membrane and its functions, which are essential for survival of organism. Therefore, online product recovery technologies with continuous fermentation are being optimized to enhance the butanol productivity. However, studies based on economic evaluation of biobutanol production illustrated that production cost of biobutanol primarily depends on cost of raw material. In this direction, conversion of cheaper lignocellulosic biomass (agriculture waste and wood residue) to biobutanol is promising the great potential towards the economic feasibility of this liquid fuel.