A new round of changes under consideration by the US Environmental Protection Agency for gasoline chemistry requires assessment on two levels: cost and necessity.
EPA is meeting with officials of the automobile, refining, and gas processing industries to discuss a tightening of standards for gasoline sulfur content and volatility. The sulfur limit for refiners now is 30 ppm average with an 80 ppm cap. A 95 ppm sulfur cap applies downstream of the refinery gate. EPA is discussing a 10 ppm sulfur refinery average with a 20-25 ppm cap. The volatility change would eliminate a 1 psi rvp waiver for gasoline containing 10 vol % ethanol (E10), now most of the fuel sold in the US.
According to oil and gas industry representatives who have met with EPA officials, changes are all but certain. EPA hopes to complete its proposal by 2011, publish final rules by September 2012, and implement the sulfur changes by fall 2016 and those for volatility by the summer of 2016 or 2017. A busy regulatory agenda might keep EPA from completing the proposal before next year.
Timing concern
A major concern is timing of implementation. To meet new sulfur standards, refiners will have to install hydrotreaters. To lower volatility, they'll need to remove large amounts of butane and pentane. Their current practice is to store light liquids that can't be blended into gasoline during summer, when volatility limits are tightest, for use at other times of the year. Lower volatility limits will mean more butane and pentane to store, which will require new tanks.
Construction at refineries requires permits that can take years to secure. The permitting requirements might make compliance with the new proposals according to EPA's projected schedule difficult if not impossible. After the volatility change, butane and pentane that can't be stored because of slow tank construction will have to be sold, possibly glutting markets.
Also troublesome is the possibility that EPA will cap gasoline sulfur at 20-25 ppm at the refinery. That move would severely restrict flexibility. A refinery might have to curtail gasoline production and total throughput whenever it encountered even an isolated problem with desulfurization.
In addition to raising chances for disruption to refinery operation, the prospective rules threaten gasoline supply in other ways. The increased processing they require will lower product yields. And marginally economic refineries might be unable to make the necessary investment and have to close.
Against the costs these adjustments imply must be weighed the environmental compulsion for new restrictions. Both changes relate to ground-level ozone—sulfur because of damage the substance can do to emission equipment aboard vehicles and volatility because of evaporative emissions of compounds that combine in sunlight to form the pollutant.
Ozone is a tough problem and always will be in large, sunny cities. During 1980-2009, however, national average ozone levels have fallen by as much as 30%. According to EPA, ozone levels fell in the 1980s but leveled off in the 1990s before falling again in most years since 2002. The overall decline for ozone has been less than those of other statutory pollutants such as nitrogen dioxide, sulfur dioxide, and carbon monoxide. And while levels of the other pollutants are well below their national standards, that of ozone beat the standard only in 2009.
Progress impressive
Ozone progress is impressive nevertheless. It's especially so in view of increases in economic activity and driving that have occurred since regulation of the pollutant began and of past moves by EPA to toughen ozone standards and make compliance more difficult. EPA's latest assault on ozone looks like large imposed cost for little environmental gain.
The industry can meet the new requirements by building equipment, adjusting logistics, and shuttering facilities as necessary. But fuel supply will suffer. Costs will rise. And ozone levels won't fall by much as a result. Someone needs to ask how much solution the US can afford to this shrinking problem.
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