GREENHOUSE GAS EMISSIONS AND ETHANOL

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GREENHOUSE GAS EMISSIONS AND ETHANOL

• Gary Z. Whitten

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INTRODUCTION

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

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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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Estimations Controversial

• Delucchi (91) most widely quoted
• But assumptionssupport 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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Coproduct credit important

• Corn oil, protein feed, gluten meal, CO2
• Delucchi and others dont 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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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