Ethanol, isobutanol, and biohydrocarbons as gasoline components in relation to gaseous emissions and particulate matter

The exhaust emissions of three cars using different biofuels were explored at a temperature of -7 °C. The biofuels studied contained both low- and high-concentration ethanol blends, isobutanol, and biohydrocarbons. A multipoint fuel injection car (MPFI), direct-injection spark-ignition car (DISI), and flex-fuel car (FFV) represented three different spark-ignition-car technologies. At -7 °C, substantial emissions were observed for the three cars, and differences were found among ethanol, isobutanol, and biohydrocarbons as fuel components. For example, E85 resulted in high acetaldehyde, formaldehyde, ethanol, ethene, and acetylene emissions when compared to E30 or lower ethanol concentrations. Isobutanol-containing fuel showed elevated butyraldehyde, methacrolein, and isobutanol emissions. The highest particulate matter (PM) emissions, associated polyaromatic hydrocarbon (PAH) and indirect mutagenicity emissions were detected with the DISI car. Oxygenated fuels reduced PM emissions and associated priority PAH emissions in the DISI car. PM and PAH emissions from the MPFI and FFV cars were generally low. A combination of 10% ethanol and biohydrocarbon components did not change emissions significantly when compared to ethanol-only-containing E10 gasoline. Therefore, a combination of ethanol or isobutanol with biohydrocarbon components offers an option to reach high gasoline bioenergy content for E10-compatible cars.