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Published bySolomon Cummings Modified over 9 years ago
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1 GREENHOUSE GAS EMISSIONS AND ETHANOL Gary Z. Whitten
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2 INTRODUCTION Ethanol can reduce greenhouse gases Estimations controversial Coproduct credit important Methane from stover not important?
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3 Ethanol reduces greenhouse gases Estimates of Ahmed and Morris depend on primary energy source and technology Corn/coal zero to 35% Corn/N.gas 10% to 35% Corn/stover 40% to 60% Cellulose/Bio. 60% to 70%
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4 Estimations Controversial Delucchi (‘91) most widely quoted But “assumptions…support virtually any conclusion” (Delucchi, 1991) Ahmed & Morris update and focus to most realistic scenarios Used average (‘92) and best to set ranges
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5 Coproduct credit important Corn oil, protein feed, gluten meal, & CO2 Delucchi and others don’t give this credit More ethanol may not require more corn In ‘85 0.6 billion gallons from 83 m. acres In ‘93 1.1 billion gallons from 73 m. acres Used 5% of corn and there is surplus
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6 Methane from stover not important? Stover (stalks) are turned into soil Landfills make methane Methane 27.5 times CO 2 for GWP Therefore, turning CO 2 to methane very bad But landfills are deep and soil is not so okay
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