US EPA proposing allowing high-octane, higher ethanol content fuels as part of Tier 3 regs; E30 as example
As part of the proposed Tier 3 rulemaking on vehicle emissions and gasoline sulfur content released last week (earlier post), the US Environmental Protection Agency (EPA) is proposing to allow vehicle manufacturers to request approval for an alternative certification fuel—such as a high-octane 30% ethanol by volume (E30) blend—for vehicles they might design or optimize for use on such a fuel.
Higher octane fuels can lead to higher compression ratios which in turn can lead to more efficient gasoline engines and reduced fuel consumption. With turbocharged gasoline engines, there is a double benefit: higher compression ratios and increased boost. (Earlier post.) Having approval for such a high octane certification fuel would, the EPA proposed in the Tier 3 Notice of Proposed Rulemaking:
...help manufacturers that wish to raise compression ratios to improve vehicle efficiency, as a step toward complying with the 2017 and later light-duty greenhouse gas and CAFE standards (2017 LD GHG). This in turn could help provide a market incentive to increase ethanol use beyond E10 by overcoming the disincentive of lower fuel economy associated with increasing ethanol concentrations in fuel, and enhance the environmental performance of ethanol as a transportation fuel by using it to enable more fuel efficient engines.
Under the proposal, automakers could petition the EPA for approval of a higher octane, higher ethanol content test fuel if:
they could demonstrate that such a fuel would be used by the operator and would be readily available nationwide;
vehicles would not operate appropriately on other available fuels; and
- such a fuel would result in equivalent emissions performance.
EPA is specifically seeking comments on the appropriateness of the alternative test fuel provisions at §1065.701(c) and the need to specify more precisely the makeup of such a fuel (ethanol content, as well as other fuel parameters) in the regulations at this time.
As one aspect concerning evaporative emissions, EPA notes that as the ethanol level in the fuel increases, the volatility increase caused by blending ethanol with gasoline begins to decline, such that at E30 there is only about a 0.5-psi RVP increase.
While this still represents an increase compared to the standards that apply to gasoline other than E9-10, it is considerably less than the full 1-psi RVP increase that result at E10, EPA noted. Thus, the evaporative emission increase caused by E30 would then be less than for E10.
(Currently, the Clean Air Act limits the volatility of gasoline to 9.0 psi RVP and 7.8 psi RVP in southern ozone non-attainment areas—but allows a 1 psi RVP waiver for E10. This waiver applies only to E10 (E9-E10), not more, not less.)
Therefore, EPA is specifically seeking comments on whether it would be appropriate to allow higher RVP levels for such blends, at least in some limited situations and time frames in which new efforts are being made to introduce such blends into the market.
It is also seeking comment on whether there are other aspects of the proposed Tier 3 standards that might need to be modified to provide an incentive for, or remove obstacles to, the development of highly efficient vehicles optimized for use on higher level ethanol blends.
Statutorily, however, there are currently a number of Clean Air Act requirements that EPA would need to meet to extend broad authority to the octane level of gasoline, noted Paul Machiele, Fuels Center Director, EPA, during a talk on the statutory and regulatory backdrop for fuel standards at the 2013 SAE International High Octane Fuels Symposium (HOF) earlier this year.
On approach, he said, would be to justify why technologies enabled by higher fuel octane are necessary to meet the light duty vehicle greenhouse gas standards (LD GHG).