The Federal court's decision allows states to propose a higher fuel oxygenate content to attain Federal air quality standards. Western cities including Denver, Las Vegas, and Phoenix have been in this predicament and have proposed higher fuel oxygenate levels than the 2.7 percent CAA minimum. The underlying issue is the ethanol mandate that will result, ostensibly, from the court's decision. The Act permits the oxygenate additive, methyl tertiary butyl ether to account for no more than 2.7 percent of fuel content. A higher oxygenate allowance would require an alternative additive to make up at least any portion over the 2.7 percent.
Ethanol remains the only other oxygenate available in commercial quantities.
Several petroleum refiners challenged EPA's earlier decision allowing states the flexibility to propose higher oxygenate mixes. In a July 7 opinion, however, the court ruled against Exxon-Mobil, reinforcing the lead role states play in achieving attainment of air quality standards.