Summer 2008

When Atlanta began fueling its vehicles with reduced-sulfur, low-volatility gasoline in 1999, the Environmental Protection Division of the Georgia Department of Natural Resources (DNR) needed to evaluate whether the new gasoline formulation reduced emissions as promised.

photo by Gary Meek Research scientist Alex Samoylov and senior research scientist Mikhail Fogelson collect emissions data.

Fortunately, since 1993 the Georgia DNR had been supporting a program in which Georgia Tech researchers monitored Atlanta area vehicle emissions to evaluate the state's vehicle inspections and maintenance program.

"It would have been difficult, if not impossible, to have analyzed the effect of the new fuel on vehicle emissions if data hadn't been collected before the new fuel was required," says Michael Rodgers, a principal research scientist with the Georgia Tech Research Institute (GTRI).

The composition of Atlanta's gasoline, considered a boutique fuel, is unique compared to the rest of the country. Its reduced sulfur content helps automobile catalytic converters operate more efficiently and its lower vapor pressure requirement reduces emissions of volatile organic compounds (VOCs) that contribute to ground-level ozone. Atlanta must reduce ozone production because the area has been designated as an ozone non-attainment area under the federal Clean Air Act.

To examine whether Atlanta's boutique fuel decreased emissions, Rodgers' research team – which included senior research scientist Mikhail Fogelson and research scientists Olga Kemenova and Alex Samoylov – compared emissions data from areas across the state.

The emissions of passing vehicles were measured remotely so that motorists were minimally aware of the equipment and did not alter their natural driving behavior. Rodgers' team measured hydrocarbons, carbon monoxide and nitrogen oxides in each vehicle's exhaust.

For the first three years, the fuel program ran from March until October in 25 counties surrounding Atlanta. After the first year, the results showed an improvement in vehicle emissions of approximately 9 percent in the counties that sold the new fuel.

"We found that the reduction in emissions as a result of repairing vehicles to pass vehicle inspection is comparable to the reduction we get from newer vehicles that are operating on cleaner fuels," explains Rodgers, who is also director of the Air Quality Laboratory in Georgia Tech's School of Civil and Environmental Engineering.

With this information, the Georgia DNR successfully petitioned the U.S. Environmental Protection Agency to allow Georgia to sell the cleaner fuel year-round in 45 counties surrounding metropolitan Atlanta.

"We were very fortunate to have a long-term record of Atlanta fleet emissions from the Georgia Tech remote sensing data, which provide a unique perspective on vehicle emissions that is not available elsewhere in the country and ensure that our programs meet the needs of Georgia residents," says Tim Smith, former manager of the motor fuels program and current manager of the vehicle inspection and maintenance program for the Georgia DNR.

– Abby Vogel