Sustainable Transportation Energy Pathways (STEPS)
Currently, gasoline fuel in California includes approximately 5.7% ethanol (E5.7). Another mixture, E10, combines10% ethanol and 90% gasoline for use in internal combustion engines of most modern automobiles and light-duty vehicles. E10 blends are mandated in some areas for emissions and other reasons. The potential effects of an E10 ethanol-blend policy in California are uncertain. In California, ethanol fuel or corn feedstock is largely imported from midwest states creating interstate transport challenges. Ethanol fuel cannot be transported in the fuel pipeline system and needs to be blended with gasoline near the end-market locations. Additionally, certain blend fractions of ethanol in gasoline can increase evaporative emissions and permeation, resulting in larger air quality concerns. Moreover, especially in California, E10 from corn is supported largely because it facilitates the transition away from petroleum and toward biofuels. But this issue has not been thought through, and is subject to a variety of uncertain assumptions. If implemented, an E10 policy in California would have impacts on ethanol consumption and greenhouse gas emissions, among other effects. Under an E10 policy in California, the ethanol consumption in 2020 will range from 1.56 billion to 2.40 billion gallons, with a base case value of 1.68 billion gallons. The average greenhouse gas emission reduction in 2020 using an E10 policy for the present combination of feedstock will be 1.37% compared to the current E5.7 blend, with a range of -0.94% to 3.87%.