The Environmental Protection Agency has proposed an 80% reduction in the sulfur content of U.S. diesel fuel beginning Oct. 1, 1993.
EPA Administrator William K. Reilly called the move "an important step" for cleaner air. He said the reduction will have the largest effect in urban areas where particulate levels are the highest and the number of people exposed the greatest.
"This action, along with the stringent heavy duty particulate reduction standards for 1991 and later vehicles, will virtually eliminate the black smoke from diesel tailpipes, cutting particulates by 90%," Reilly said.
EPA said diesel exhaust has been identified as a possible carcinogen. The minute size of diesel particulates are of special concern because, when inhaled, they stay a relatively long time in the respiratory tract.
COSTS, BENEFITS
EPA estimated the rule will add 1.8-2.3/gal to diesel's cost, depending on volume controlled. It requires refiners to reduce the sulfur content of diesel used on the road to 0.05 wt % from 0.25 wt %.
EPA said the rulemaking will cost refiners $380-910 million in 1995 and from $540 million to $1.3 billion by 2010.
Partially offsetting this cost will be the diesel manufacturers' ability to use less costly emission control devices, resulting in consumer savings of $60-325/vehicle, the agency said. It expects total savings, including expected fuel savings from the use of catalytic devices, will be $200 million in 1995 and $465 million in 2010.
If the diesel fuel sulfur cuts result in significantly reduced engine wear, as some information suggests, consumer savings could outweigh the increased costs per gallon for the low sulfur fuel, EPA said.
Diesel fuel aromatics will be controlled at near current levels by requiring a minimum cetane index specification or an optional maximum aromatics content standard.
The rule will give small refiners until 1995 to phase in the new standards, but they will be required to meet interim standards.
EPA said to protect 1994 and later model year engine designs, which will require the low sulfur fuel, fuel produced under a 2 year extension may be sold only for pre-1994 engine equipped vehicles or to off-highway markets.
It said the rulemaking will help diesel engine manufacturers meet the tighter particulate exhaust standards in 1991 and 1994.
In addition to lowering particulates, the rule is designed to reduce secondary formation of particulates in the atmosphere. Most sulfur in the fuel is emitted as sulfur dioxide, much of which is further oxidized in the atmosphere to form sulfuric acid and ammonium sulfides, contributors to acid rain.
The agency said the rule should reduce particulates by 196,000 tons/year and sulfur dioxide levels by 580,000 tons/year by 1995.
The rulemaking incorporates some proposals that diesel engine makers and the oil refining industry had made to EPA in 1988.
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