Exergetic evaluation of corn-ethanol production in China Q. Yang a , B. Chen b , Xi Ji a , Y.F. He a , G.Q. Chen a, * a National Laboratory for Turbulence and Complex Systems, Department of Mechanics, Peking University, Beijing 100871, China b State Key Joint Laboratory of Environmental Science and Pollution Control, Faculty of Environment, Beijing Normal University, Beijing 100875, China Received 4 April 2007; received in revised form 25 July 2007; accepted 11 August 2007 Available online 19 September 2007 Abstract The cumulative exergetic method is used in this study to identify the renewability of the total corn-ethanol production in China when capturing all natural nonrenewable resources consumed in the integrated process including agricultural crop production, corn transportation, industrial conversion and waste treatment. A modified exergy-based indicator is thereby proposed to quantify the renewability of corn-ethanol production process. For the conditions prevailing in China, the renewability indicator as suggested by Berthiaume et al. is calculated to be 4.58, denoting the production process is highly nonrenewable. In addition, a novel indicator is also presented to reveal the environmental cost-effectiveness of the corn- ethanol process as supplement to the renewability indicator. Finally, the sensitivity analysis shows that the defined system boundaries, electricity-generation structure of the country, and technological constraints and choices of production process influence the renewability evaluation results. Ó 2007 Elsevier B.V. All rights reserved. PACS: 87.23.n; 89.60.k Keywords: Corn-ethanol; Exergy; Renewable energy; Ecological thermodynamics 1. Introduction Due to the rapid exploitation of nonrenewable energy resources in China, the scarcity of nonrenewable energy source has been awared, and more attention has been paid to technology innovation of using renewable energy as alternative energy source. Producing ethanol out of biomass has become a major concern for the Chinese government to expand the domestic energy supply and help mitigate growing dependence on imported oil after 1990s. Bio-ethanol is considered to be a much prevailing biomass-based transportation fuel due to high and volatile oil prices, low feed stocks prices, abandon of methyl tertiary butyl ether (MTBE), declining costs 1007-5704/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.cnsns.2007.08.011 * Corresponding author. E-mail address: gqchen@pku.edu.cn (G.Q. Chen). Available online at www.sciencedirect.com Communications in Nonlinear Science and Numerical Simulation 14 (2009) 2450–2461 www.elsevier.com/locate/cnsns