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 ‘ billion gallons from 83 m. acres In ‘ 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 CO 2 for GWP Therefore, turning CO 2 to methane very bad But landfills are deep and soil is not so okay