Monday, November 5, 2007
37-12

Simulating Net Energy Value of Ethanol from Corn Grown under Southeastern US Climate Conditions.

Tomas Persson1, Axel Garcia y Garcia, Joel Paz2, Clyde W. Fraisse3, James Jones3, and Gerrit Hoogenboom2. (1) 1109 Experiment St., University of Georgia, Univ. of Georgia, Dept. of Biological & Agricultural Engineering, Griffen, GA 30223, (2) Dept. of Biological & Agricultural Engineering, University of Georgia, 1109 Experiment Street, Griffin, GA 30223, (3) Dept. of Agricultural & Biological Engineering, University of Florida, P. O. Box 110570, Gainesville, FL 32611

There is an increasing interest in producing ethanol from corn in the USA. The net energy value (NEV) of ethanol is crucial to its use as a substitute for fossil fuels. The objective of this study was to estimate the effect of temporal and spatial weather variations in the southeastern USA on the NEV of ethanol. A model simulating climatic and farm management effects on NEV of ethanol produced from corn grain has been developed. In the model, grain yield is simulated as a function of weather and soil factors based on the Cropping System Model (CSM)-CERES-Maize and used as input to a spreadsheet calculation of the NEV of the produced ethanol. The energy model takes into account grain yield, energy input related to farm management, e.g. fertilizer application rates and irrigation, and energy requirement related to ethanol processing and transportation. Grain yield for commonly grown corn hybrids were simulated for weather and soils representing the southeastern USA for 68 historical weather years. Different irrigation scenarios, planting dates and nitrogen application rates were also evaluated. Preliminary results showed that, for a range of soil and weather conditions, and crop management scenarios, ethanol produced from irrigated corn had a higher NEV than ethanol produced from rainfed corn. For rainfed conditions, NEV of ethanol produced from corn grown during La Niña years was significantly higher than NEV of ethanol produced from corn grown during El Niño and neutral years. Also soil, planting date and nitrogen application rate significantly affected the ethanol NEV. Under rainfed conditions, the lowest nitrogen fertilization rates resulted in the highest NEV. This study showed that weather, soil and farm management practices have a significant impact on the NEV of ethanol produced from corn grain. Future research will include the estimation of NEV from ethanol produced from corn stover.

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