Assessing deployment strategies for ethanol and flex fuel vehicles in the U.S. light-duty vehicle fleet

Abstract

Within the next 3-7 years the US light duty fleet and fuel supply will encounter what is commonly referred to as the "blend wall". This phenomenon describes the situation when more ethanol production has been mandated than can be blended legally in the existing gasoline fuel supply. While there are currently measures under review to extend fuel certification to from 10% to 15% ethanol blends, this will not be enough to reach the existing Renewable Fuel Standard targets that grow over the next decade to 36 billion gallons of biofuel. This research focuses on a quantitative assessment of how to effectively use policies to match the deployment of ethanol with capable vehicles to use ethanol, and the infrastructure to the fuel. A model of the light duty vehicle fleet has been used find the number of vehicles required to meet ethanol fuel usage targets. The key variables explored in this work are (i) the volumetric target for total biofuels (ii) the legal blend limit of ethanol in gasoline, (iii) fleet vehicle sales penetration and (iv) a metric for the relative utilization of ethanol and gasoline for flex fuel vehicles. Each of these factors can be varied independently to understand the existing relationship between each in the context of the US light-duty vehicle fleet. Ultimately, coordinated polices focusing on each of these key factors can ease the transformation of the automotive fuel industry away from petroleum dominated supplies.