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GREENHOUSE GAS EMISSIONS AND ETHANOL

GREENHOUSE GAS EMISSIONS AND ETHANOL. Gary Z. Whitten. INTRODUCTION. Ethanol can reduce greenhouse gases Estimations controversial Coproduct credit important Methane from stover not important? . Ethanol reduces greenhouse gases.

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GREENHOUSE GAS EMISSIONS AND ETHANOL

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  1. GREENHOUSE GAS EMISSIONS AND ETHANOL Gary Z. Whitten

  2. INTRODUCTION • Ethanol can reduce greenhouse gases • Estimations controversial • Coproduct credit important • Methane from stover not important?

  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%

  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

  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

  6. Methane from stover not important? • Stover (stalks) are turned into soil • Landfills make methane • Methane 27.5 times CO2 for GWP • Therefore, turning CO2 to methane very bad • But landfills are deep and soil is not so okay

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