A comparison of small engine emissions powered by alcohol and gasoline fuel

Small engines create a disproportionate amount of pollutants for their size. No research on the emissions of a small, carbureted engine run on widely available 100% alcohol fuel exists. To address this problem, we hypothesized that an alcohol-based fuel could be used as an effective means of lowering small engine emissions. To investigate the extent of small engine emissions improvement, a Toro push lawn mower with a 6.5 hp engine was modified to run on alcohol fuel. We tested for the common pollutant's nitrous oxide, unburnt hydrocarbons, sulfur dioxide, and carbon monoxide using a Testo 350 portable emissions analyzer. Two fuels were used. The first was Klean Strip Denatured Alcohol, which is a mixture of ethanol and methanol. The second was made up of 10% ethanol and 90% gasoline (E10) and is available at most gas stations. The Klean Strip Denatured Alcohol fuel produced significantly less nitrous oxides, sulfur dioxide, carbon monoxide, and hydrocarbon emissions when compared to the E10 fuel. Of the four measured pollutants, the alcohol-based fuel consistently produced at least 40% less emissions compared to the E10 fuel. The use of a methanol and ethanol blend in small engines could drastically reduce existing small engine emissions.