Mobile Sources - Cleaner fuels

Control of pollutants from mobile sources

One way to reduce air pollution from cars and trucks is to use a gasoline that is designed to burn clean. This cleaner burning gasoline, called reformulated gasoline or RFG, is required in cities with the worst smog pollution, but other cities with smog problems may choose to use RFG. Reformulated gasoline contains less volatile organic compounds (VOCs), and will contain oxygen additives to make the fuel burn more efficiently. Also, all gasolines will have to contain detergents, which, by preventing build-up of engine deposits, keep engines working smoothly and burning fuel cleanly.

Figure: Methyl tertiary-butyl ether (MTBE)

Methyl tertiary-butyl ether (MTBE) is the oxygen additive most commonly used by the petroleum industry to satisfy the two percent oxygen mandate in the RFG program. MTBE is used in approximately 87 percent of RFG, with ethanol being the second most commonly used additive. Oxygenates increase the combustion efficiency of gasoline, thereby reducing vehicle emissions of carbon monoxide. On the other hand, EPA encourages the development and sale of alternative fuels such as alcohols, liquefied petroleum gas (LPG) and natural gas in order to lower fuel emissions.