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The Energy Independence and Security Act of 2007 established a new Renewable Fuel Standard (RFS2) requiring increased biofuel use (through 2022) and greater fuel economy (through 2030) for the US light-duty vehicle (LDV) fleet. Ethanol from corn and cellulose is expected to supply most of the biofuel and be used in blends with gasoline. A model was developed to assess the potential impact of these mandates on the US LDV fleet. Sensitivity to assumptions regarding future diesel prevalence, fuel economy, ethanol supply, ethanol blending options, availability of flexible-fuel vehicles (FFVs), and extent of E85 use was assessed. With no E85 use, we estimate that the national-average ethanol blend level would need to rise from E5 in 2007 to approximately E10 in 2012 and E24 in 2022. Nearly all (97%) US gasoline LDVs were not designed to operate with blends greater than E10. FFVs are designed to use ethanol blends up to E85 but comprise only 3% of the fleet.

This study investigates the life cycle greenhouse gas (GHG) emissions of a set of vehicles using two real-world gliders (vehicles without powertrains or batteries); a steel-intensive 2013 Ford Fusion glider and a multi material lightweight vehicle (MMLV) glider that utilizes significantly more aluminum and carbon fiber. These gliders are used to develop lightweight and conventional models of internal combustion engine vehicles (ICV), hybrid electric vehicles (HEV), and battery electric vehicles (BEV). Our results show that the MMLV glider can reduce life cycle GHG emissions despite its use of lightweight materials, which can be carbon intensive to produce, because the glider enables a decrease in fuel (production and use) cycle emissions. However, the fuel savings, and thus life cycle GHG emission reductions, differ substantially depending on powertrain type. Compared to ICVs, the high efficiency of HEVs decreases the potential fuel savings.

This paper provides an overview of the effects of blending ethanol with gasoline for use in spark ignition engines. The overview is written from the perspective of considering a future ethanol-gasoline blend for use in vehicles that have been designed to accommodate such a fuel. Therefore discussion of the effects of ethanol-gasoline blends on older legacy vehicles is not included. As background, highlights of future emissions regulations are discussed. The effects on fuel properties of blending ethanol and gasoline are described. The substantial increase in knock resistance and full load performance associated with the addition of ethanol to gasoline is illustrated with example data. Aspects of fuel efficiency enabled by increased ethanol content are reviewed, including downsizing and downspeeding opportunities, increased compression ratio, fundamental effects associated with ethanol combustion, and reduced enrichment requirement at high speed/high load conditions.