A Life-Cycle Analysis of the Greenhouse Gas Emissions of Corn-Based Ethanol

To reflect the full range of recently published literature relating to the contribution of international landuse change to the current GHG profile of corn ethanol, ICF adopted a composite approach that averaged the results of three recently published studies (CARB, 2015; Dunn et al., 2015; and GTAP, 2013) and four scenarios developed from their results that allow for alternative sets of emissions factors and the increased use of double cropping (Babcock and Iqbal, 2014). These seven results are shown in Figure 3-4. Dunn et al. (2015) quantify two emissions related to international land-use change distinguished by the use of the Winrock and the Woods Hole emissions factors (EFs). ICF developed four scenarios from the results of the most recently published GTAP study (GTAP 2013) to account for the use of ARB EFs and Winrock EFs as well as increased double cropping (denoted “Adjusted” in Figure 3-4). Across these seven results, the average emissions impact is 8.61 g CO2e/MJ. This value converts to 9,082 g CO2e/MMBtu, which is the value ICF used as the contribution of international land-use change to corn ethanol’s current GHG profile