EPA 'Tier III' Test Change May Complicate Achieving Fuel Economy Goals
by Lori Nicholson (IWP News) EPA’s recent decision in its “Tier III” vehicle emissions rule to increase the amount of ethanol in certification fuel used to determine an automobile’s compliance with the standard could complicate automakers’ ability to meet separate fuel economy and greenhouse gas (GHG) rules for cars subject to a different type of certification, observers say.
The Tier III rules, finalized earlier this year, increased the amount of ethanol in EPA’s certification fuel from zero (E0) to a 10 percent ethanol (E10) gasoline blend, but did not change the calculation used by the agency to account for the decreased energy content of ethanol in assessing fuel economy and vehicle GHGs.
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That creates a disconnect between the Tier III tests that acknowledge the use of lower-emitting higher ethanol blends and the fuel economy and GHG standard testing that does not account for it, observers say.
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Brian West, a fuels and engines expert with DOE’s ORNL, explained that the impacts to fuel economy would be corrected if EPA changed the “R” factor to account for the E10 change.
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West said the change to the R factor cited by the automakers would allow vehicles to take advantage of the CAFE and GHG benefits offered by higher ethanol blends due to the higher octane the fuel offers. Higher octane allows for the use of smaller, high compression engines that are more efficient. “With [a] correct R Factor, high-octane mid-level blends can offer real CAFE as well as GHG benefits,” West said. He believes EPA will revise the equation “for ethanol-blended fuels for fuel economy certification,” although EPA has been silent on doing so.
West added that the Obama administration’s CAFE and GHG rules, Tier III, and the RFS could work together, if EPA examines the best way to incorporate higher octane fuels. “A new high octane fuel could make better use of ethanol’s properties, helping the nation achieve multiple goals,” he stated.
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Automakers raised the idea of an alternative means of measuring octane in gasoline in their comments on the proposed version of Tier III, saying it would help eliminate poorly blended fuels with lower octane in certain states where local laws allow for low octane fuels.
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The ethanol industry’s June 26 lawsuit, Energy Future Coalition, et al. v. EPA, filed with the appellate court seeks for EPA to raise the test fuel to E30 as a means of compelling automakers to certify their engines on higher ethanol blends. READ MORE
