Autos not hurt by different sulfur levels

The American Petroleum Institute says preliminary results of vehicle emissions tests indicate the effects of higher sulfur levels in gasoline on emissions performance of modern vehicles are temporary and immediately reversible.

API said that means that any emission increase from having cars operate on gasolines with different sulfur levels would be remedied by operating the cars on a few gallons of lower-sulfur fuel.

The association and the National Petrochemical & Refiners Association recently proposed that the U.S. Environmental Protection Agency consider two national gasolines with different sulfur levels (OGJ, Mar. 30, 1998, p. 29).

They suggested an average summer sulfur level of 150 ppm for 22 eastern states and 300 ppm for 27 other states where air quality problems are less serious. California would continue to use its own reformulated, low-sulfur gasoline. They said the proposal represents a 50% cut in gasoline sulfur levels.

API said its tests found vehicle-to-vehicle differences in technology are significant. "Some vehicles are more sulfur resistant and had lower emissions than others, but the effects of sulfur were reversible on all vehicles tested."

The research, conducted by an independent laboratory, tested seven low-emitting vehicles on gasoline with two sulfur levels: 40 ppm and 540 ppm. The tests used the same procedures EPA will use to certify emissions performance of future vehicles.

API said testing has been completed on four of the seven vehicles. Complete results for all cars are expected in about a month.

It said the preliminary research also indicates that the vehicles produced emissions low enough to meet the tailpipe emissions standards stated in the Clean Air Act for model-year 2004.

EPA study

Meanwhile, EPA said it plans to make its own regulatory proposal on gasoline sulfur in December. It recently released a staff paper that made no recommendations but generally supported the need for some level of sulfur control.

EPA said, "The Clean Air Act requires EPA to consider whether or not further reductions in air pollution from motor vehicles will be required beginning in the year 2004. Sulfur in gasoline is an important part of any future decisions about tailpipe standards because sulfur inhibits the performance of catalytic converters."

EPA said reducing sulfur would cost much less than industry has estimated. It said going to 150 ppm would cost 1.2-1.9¢/gal, compared with the API's estimate of 2.65¢, and cutting to 100 ppm would cost 2.0-3.3¢ versus API's 3.4¢.

But, while EPA said cutting sulfur to 40 ppm would cost 5.2-8.7¢, API said it would cost 5.1¢. EPA's data were based on Northeast and Gulf Coast refiners, while API's included Midwest refiners.

EPA also said emerging technologies could lower costs of reaching 40 ppm to 1-2¢/gal.

The study said targeting sulfur cuts to particular regions with seasonal pollution problems would reduce refiners' costs, but the effects of sulfur on equipment would have to be reversible, and reversibility appears to vary from vehicle to vehicle.

It said a single national sulfur standard would allow auto makers to design cars for one fuel instead of a range of fuels, simplify enforcement, boost cleaner technologies, and help areas that otherwise could slip out of compliance with air standards.