The Effects of Methanol/Gasoline Blends on Automobile Emissions

This report presents the Auto/Oil AQIRP results of a methanol fueled vehicle emission study. Nineteen early prototype flexible/variable fueled vehicles (FFV/VFV) were emission tested with industry average gasoline (M0), an 85% methanol-gasoline blend (M85), and a splash-blend of M85 with M0 (gasoline) giving 10% methanol (M10). Vehicle emissions were analyzed for the FTP exhaust emissions, SHED diurnal and hot soak evaporative emissions, and running loss evaporative emissions. Measurements were made for HC, CO and NO_x emissions and up to 151 organic emission species, including air toxic components. M0 and M10 emissions were very similar except for elevated M10 evaporative emissions resulting from the high M10 fuel vapor pressure. M85 showed lower exhaust emissions than M0 for NMHC (non-methane hydrocarbon), OMHCE (organic material hydrocarbon equivalent), CO and most species. M85 had higher exhaust emissions for NMOG (non-methane organic gases), NO_x, methanol and formaldehyde. Aggregate toxics were independent of fuel. M85 had lower diurnal emissions and higher hot soak OMHCE and NMOG than M0. M85 had higher running loss emissions than M0. M85 showed 50% reductions in exhaust and evaporative ozone forming Specific Reactivities (grams ozone per gram NMOG) and also Ozone Forming Potential (grams ozone per mile) relative to the M0 fuel.