Critical analysis of techno-economic estimates for the production cost of lignocellulosic bio-ethanol

Bio-ethanol has been claimed to be a green and sustainable alternative to gasoline. The use of food crops on a large scale is ethically unacceptable, but lignocellulosic ethanol has potential to become an alternativfe transportation fuel. This relates to technical issues, and to the eventual cost of bio-ethanol, which requires determination of an absolute production cost. The minimum ethanol selling price (MESP) estimated in different studies varies between $234 and $1210 per m(3) ethanol ($0.89 and $4.58 per gallon), although often the same processing methods are assumed. This entails uncertainties about the potential of bio-ethanol from lignocellulosic sources. In this study, the main key factors determining these deviations are pinpointed. The assumed values in the different studies were critically investigated and more accurate, unambiguous values proposed. By doing this, a current production cost of $651 per m(3) ethanol was calculated and a realistic projection towards the near future estimates an MESP of $511. Corn ethanol has already a higher price than the current price of lignocellulosic ethanol due to the high cost of corn. A comparison with gasoline yields a 10% lower price than the future MESP of lignocellulosic ethanol. Due to rising gasoline prices, lignocellulosic ethanol is likely to become in the future not only a more ecological but also a more economical attractive transportation fuel. (C) 2013 Elsevier Ltd. All rights reserved.