Relative reactivity of emissions from methanol-fueled and gasoline-fueled vehicles in forming ozone

Abstract

A trajectory model was used to estimate the ozone-forming potential of emissions from methanol- and gasoline-fueled vehicles. The composition of the emissions from the two types of vehicles was based on new measurements of the individual organic compounds emitted by vehicles operating on gasoline, M85 fuel, and M100 fuel. Simulations were conducted using a range of atmospheric conditions and two different chemical mechanisms. The results suggest that replacing gasoline-fueled vehicles with methanol-fueled vehicles may not reduce ozone in all urban areas. Also, it was found that the experimental methanol-fueled vehicle tested provides, at best, small ozone reductions compared to prototype gasoline-fueled vehicles. Additional work is necessary to reduce formaldehyde emissions from methanol-fueled vehicles. Lastly, if both M85 and M100 vehicles are assumed to have the same low-formaldehyde fraction in the emissions, the results suggest that M85 vehicles provide 80-85% of the ozone reductions of M100 vehicles.