HW_4%20Solutions - CE 108 Homework #4 Solutions 1. Estimate...

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CE 108 Homework #4 Solutions 1. Estimate the volume of ethanol that could be produced using the entire U.S. corn crop from 2007. From the USDA 2007 Census of Agriculture (Table 1-“corn for grain”): 2007 US corn yield = 86,248,542 acres = 12,738,519,330 bushels 1 bushel corn = 56 lb = 25.4 kg ( http://www.unc.edu/~rowlett/units/scales/bushels.html ) Calculate corn yield (kg/ha); This crop yield is slightly higher than the yield used by Farrell et al. for the EBAMM program. Calculate energy content (E eth ) of US corn crop converted to ethanol: Assume ethanol biorefinery yield of 0.40 L/kg crop (Farrell et al., 2006) Calculate energy content (E gas ) of gasoline used in the US in 2007: 2007 US motor gasoline consumption = 9,076,000 brl/day (Energy Information Administration - Annual Energy Review 2007, Table 5.13c) Lower heating value of gasoline = 115500 BTU/gal ( www.eia.doe.gov ) The energy content of the entire US corn crop converted to ethanol is nearly an order of magnitude less than the energy content of motor gasoline used in the US in 2007.
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2. Calculate GHG emissions from the production of sugar cane ethanol using the EBAMM program. For this question, six values needed to be changed in the EBAMM spread sheet: (1) Nitrogen fertilizer emissions (2) Emissions from coal use in biorefinery phase (3) Emissions from natural gas use in biorefinery phase (4) Crop yield (5) Biorefinery yield (6) Coproduct credits For this question, I used data presented in Smeets et al. (2009). A number of other sources were used by the class, a selection of which I’ve included in the reference list at the end of the solution set. I accepted a range of values for each of the six values, provided the estimates were
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HW_4%20Solutions - CE 108 Homework #4 Solutions 1. Estimate...

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