Expanding the ethanol blend wall in California: Emissions comparison between E10 and E15

This study assessed the potential of increasing ethanol content in California reformulated gasoline (CaRFG) by investigating the exhaust emissions from a fleet of 20 light-duty vehicles. A baseline CaRFG E10 (10% ethanol by volume) fuel was splash blended with denatured ethanol to create a E15 fuel. Each vehicle/fuel combination were exercised over triplicate Federal Test Procedure (FTP) cycles on a chassis dynamometer. Our results showed no statistically significant fuel effect on nitrogen oxide (NOx) emissions for E15, whereas total hydrocarbons (THC), non-methane hydrocarbons (NMHC), and carbon monoxide (CO) showed either marginally or statistically significant reductions for E15. Particulate matter (PM) and solid particle number emissions were positively impacted by ethanol, exhibiting statistically significant reductions. Acetaldehyde and ethanol emissions responded strongly with ethanol across the fleet of 20 vehicles, while formaldehyde emissions did not show a statistically significant effect. Monoaromatic species and 1,3-butadiene showed mixed results, with ethylbenzene and the xylene isomers showing strong fuel differences. Although no strong differences were found for carbon dioxide (CO2) emissions, E15 showed life cycle greenhouse gas (GHG) emissions savings when compared to E10.