Hosein Shapouri and James A. Duffield. “The Energy Balance of Corn Ethanol: An Update”. Agricultural Economic Report No. 813, 2002 – “RESULTS All energy inputs used in the production of ethanol is adjusted for energy efficiencies developed by GREET model. The estimated energy efficiencies are for gasoline (80.5 percent), diesel fuel (84.3 percent), LPG (98.9 percent), natural gas (94 percent), coal (98 percent), electricity (39.6 percent), and transmission loss (1.087 percent). After adjusting the energy inputs by these energy efficiencies, the total estimated energy required to produce a bushel of corn in 2001 was 49,753 Btu. Table 3 summarizes the input energy requirements, by phase of ethanol production on a Btu per gallon basis (LHV) for 2001, witho ut byproduct credits. Energy estimates are provided for both dry- and wet- milling as well as industry average. In each case, corn ethanol has a positive energy balance, even before subtracting the energy allocated to byproducts. Table 4 presents the final net energy balance of corn ethanol adjusted for byproducts. The net energy balance estimate for corn ethanol produced from wet- milling is 27,729 Btu per gallon, the net energy balance estimate for dry- milling is 33,196 Btu per gallon, and the weighted average is 30,528 Btu per gallon. The energy ratio is 1.57 and 1.77 for wet- and dry- milling, respectively, and the weighted average energy ratio is 1.67.”
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