『Abstract
　Nonrenewable energy cost is accounted for the believed renewable biofuel of corn-ethanol in China. By a process-based energy analysis, nonrenewable energy cost in the corn-ethanol production process incorporating agricultural crop production, industrial conversion and wastewater treatment is conservatively estimated as 1.70 times that of the ethanol energy produced, corresponding to a negative energy return in contrast to the positive ones previously reported. Nonrenewable energy cost associated with wastewater treatment usually ignored in previous researchers is shown important in the energy balance. Denoting the heavy nonrenewability of the produced corn-ethanol, the calculated nonrenewable energy cost would rise to 3.64 folds when part of the nonrenewable energy cost associated with water consumption, transportation and environmental remediation is included. Due to the coal dominated nonrenewable energy structure in China, corn-ethanol processes in China are mostly a conversion of coal to ethanol. Validations and discussions are also presented to reveal policy implications again corn based ethanol as an alternative energy in long term energy security planning.

Keywords: Nonrenewable energy cost; Biofuel; Corn ethanol』

1. Introduction
2. Methodology
3. Estimation and results
　3.1. Nonrenewable energy-intensity coefficients for fossil fuels
　3.2. Nonrenewable energy-intensity coefficients for electricity
　3.3. NE cost of the agricultural process
　　3.3.1. NE inputs to potash fertilizer production
　　3.3.2. NE inputs to phosphorus fertilizer production
　　3.3.3. NE inputs to urea production
　　3.3.4. NE inputs to pesticide production
　3.4. NE cost in the conversion of corn into ethanol
　3.5. NE cost associated with wastewater treatment in ethanol plant
　3.6. Evaluation of NEIED
4. Validation
　4.1. Other NE inputs
　4.2. Co-product credits
5. Discussion and concluding remarks
Acknowledgments
References