US EPA proposes higher volatility limits for ethanol-blended gasoline

Late Friday afternoon on the eve of a long holiday weekend in the US, the federal Environmental Protection Agency announced it has proposed a rule that will relax evaporative emissions limits for summertime reformulated gasoline (RFG) containing ethanol. EPA says the action will make it easier for refiners to use ethanol in RFG and still maintain the air quality benefits of the RFG program.


Late Friday afternoon on the eve of a long holiday weekend in the US, the federal Environmental Protection Agency announced it has proposed a rule that will relax evaporative emissions limits for summertime reformulated gasoline (RFG) containing ethanol. EPA says the action will make it easier for refiners to use ethanol in RFG and still maintain the air quality benefits of the RFG program.

RFG has a minimum oxygen content requirement that makes it necessary for refiners to blend an oxygenate into gasoline. The oxygenate used in 87% of US RFG is methyl tertiary butyl ether.

EPA says use of ethanol, more so than other oxygenates, reduces vehicle carbon monoxide emissions. However, the additive has higher volatility, increasing evaporative emissions.

"Normally, for cleaner-burning gasoline with ethanol to meet pollution reduction standards, an adjustment must be made to the gasoline," said EPA. "That adjustment involves reducing the evaporative property of gasoline to accommodate ethanol, since ethanol can make gasoline evaporate more readily, which leads to an increase in air pollution.

"EPA's proposed adjustment allows refiners to slightly increase the evaporative property of gasoline in exchange for the carbon-monoxide reductions derived from using ethanol. This adjustment will maintain the overall air quality benefits of the program," EPA said, without elaboration.

The proposed rule calls for an adjustment to the volatile organic compound standard under Phase II of the federal RFG program for RFG blends containing 10% ethanol (these blends also contain about 3.5 wt % oxygen).

"For such blends, the proposed adjustment would reduce by 1 percentage point�from a 27.4 to a 26.4 percent reduction in the north, and from a 29 to a 28 percent reduction in the south�the VOC performance standard," said EPA. "We believe that air quality benefits will continue to be similar to the current RFG standards."

Ethanol production receives a 54�/gal tax subsidy from the US government.

EPA is accepting comment on the proposed rule, and on adjustment or elimination of the minimum oxygen requirement of 1.5 wt %, for 60 days. It is also accepting comment on a proposal made by Illinois requesting that the state be allowed to revert to selling gasoline that meets Phase 1 summertime RFG standards until EPA grants a "carbon monoxide credit" in the state for gasoline containing ethanol.

"The requirement for the use of oxygenate is, itself, questionable, since vehicles with fuel injection instead of carburetors...don't need it," said Petroleum Industry Research Foundation Inc. (PIRINC) in a recent report on the Midwest gasoline price spikes.

PIRINC also commented on the detrimental effects of EPA revoking environmental regulations.

In addressing the MTBE phaseout that EPA is implementing, PIRINC said, "When [local supply problems]...develop, the regulatory authorities are then faced with a choice of going back on their standards, at least temporarily, or standing by and accepting the inevitable, necessary price spikes. If standards are waived, then those in the industry who made the greatest to meet the standards are penalized relative to those who did the least.

"Creating a 'no good deed goes unpunished' precedent sends exactly the wrong signal for future compliance efforts," said PIRINC.

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