Impact of oxygenated fuels on atmospheric emissions in major Colombian cities

Abstract

The use of oxygenated gasolines has increased in Latin America over the past several years with the goal to reduce oil dependence, improve gasoline combustion and emit fewer pollutants to the atmosphere. Countries such as Brazil, Colombia, Mexico, Argentina, and Peru blend their gasoline with ethanol in different proportions. In Colombia, the regulation establishes a 10% vol of ethanol in gasoline (E10). Ethers are also used to oxygenate gasolines. MTBE (methyl tert-butyl ether) is blended in gasoline primarily in Mexico, Venezuela, and Chile, while ETBE (ethyl tertiary-butyl ether) is used in Argentina. The U.S. EPA Motor Vehicle Emissions Simulator (MOVES) model was adapted to Colombia to evaluate gasoline blends with two renewable oxygenates (ethanol and ETBE) on the emission of criteria pollutants (PM2.5, CO, NOx, SO2), Total Gaseous Hydrocarbons (TGH), Volatile Organic Compounds (VOCs), and toxic compounds. We followed the same approach used to build MOVES-Mexico and assess fuel specifications changes on vehicle emissions.The MOVES-Colombia model finds that E10 increases fuel volatility, VOCs, NOx, PM2.5, and SO2 emissions, and decreases CO relative to the unoxygenated base gasoline (E0). The impact of E10 consumption on air quality is due not only to primary pollutants, but also to the emission of ozone and PM2.5 precursors. Compared to E10 and E0, the ETBE blends reduce fuel volatility and emissions of VOCs, TGH, CO, NOx, PM2.5, and SO2. The introduction of ETBE could help major urban areas to meet air quality standards even with their current vehicle fleets. This work highlights that the effect of new fuel specifications needs to be properly assessed in terms of air quality before they are put in place. The development of modeling tools, such as MOVES-Colombia, facilitates the study of fuel quality and vehicle technology on pollutant emissions.