Economic analysis of biobutanol recovery from the acetone-butanol-ethanol fermentation using molasses

Commercial production of biobutanol via acetone-butanol-ethanol (ABE) fermentation is challenged by the energy-intensive recovery of biobutanol from inherently diluted fermentation broth. Towards the solution of this problem, four combinations (scenarios) of separation techniques such as distillation, gas stripping (GS), liquid-liquid extraction (LLE), and pervaporation (PV) are investigated for the minimum unitary production cost of biobutanol. Cost components for the installation and operation of the plant are estimated using Matlab software and method given by Peters and Timmerhaus. Production costs with significant variables viz. biobutanol yield, price of molasses, and fermenter volume are individually estimated. Gas stripping followed by distillation is found as the most economical scenario with a unitary production cost of INR 74/kg. The optimum values of yield and fermenter volume are found as 0.4 kg ABE/kg sugars and 100 m³, respectively. The optimization of three major variables around the baseline values provides nearly 10% reductions in the cost with present fermentation technology. This economic analysis of biobutanol recovery certainly contributes to the commercial production of biobutanol from renewable raw materials. The economic feasibility of biodiesel production may offer better environment to the mankind.