The Renewable Fuels Association and Growth Energy filed comments with the U.S. EPA on July 8 supporting the agency’s proposed anti-backsliding determination but criticizing the use of outdated and flawed data.

RFS regulations contained in the Clean Air Act require the EPA to complete an anti-backsliding study to determine if required RFS blending volumes adversely impact air quality as a result of changes in vehicle and engine emissions. After considering the results of the study, the agency is required to either promulgate fuel regulations to mitigate adverse impacts on air quality, or determine that no such measures are necessary.

The EPA on May 29 issued a rulemaking proposing the second option—stating that the agency has determined no such measures are necessary.

“EPA is proposing to determine that no additional fuel control measures are necessary because since 2017, EPA has been implementing the Tier 3 Motor Vehicle Emissions and Fuel Standards which are more stringent and reduce concentrations of ozone, PM2.5, NO2, and air toxics now and in the future,” said the agency in a notice posted to its website. “In making this determination, EPA considered the analyses performed for the Tier 3 rulemaking, as well as the anti-backsliding study.”

A public comment period on the proposed finding was open through July 8.

In its comments, the RFA expressed support for the EPA’s proposal to determine that no additional measures are necessary to mitigate “potential adverse air quality impacts” associated with the RFS. The group, however, also challenged the flawed air quality modeling and analysis conducted by EPA to inform the proposed determination.

“We agree that no additional ‘fuel control measures’ are necessary, but we reach this conclusion for a different reason than EPA,” wrote Geoff Cooper, president and CEO of the RFA. “We believe no additional measures are necessary because the scientific evidence demonstrates that increasing the concentration of ethanol in gasoline generally improves air quality and does not cause ‘adverse air quality impacts.’”

“We remain concerned that the Anti-Backsliding Study (ABS) used to inform the proposed determination continues to rely upon an outdated and unreliable emissions model, the Motor Vehicle Emission Simulator (MOVES), to estimate the emissions impacts of ethanol-blended motor fuels,” the RFA said in its comments. “The agency, itself, has acknowledged the ABS ‘has a number of limitations.’ Indeed, it does. We firmly believe this model and the resulting ABS report are inappropriate tools for assessing the real-world air quality impacts of renewable fuels. We have repeatedly asked the Agency to look at empirical data and real-world emissions measurements when assessing the air quality impacts of ethanol-blended gasoline, and we renew that request today.”

The RFA noted that multiple independent third-party reviews have found that the MOVES2014 model used by EPA to estimate the exhaust emissions of ethanol-gasoline blends is fatally flawed due to its use of manipulated input data and unreliable “adjustment factors” and equations. RFA’s comments recommend several options for improving EPA’s evaluation of emissions related to ethanol-blended fuels and the association offers to “…work constructively with the agency to complete a more meaningful assessment of ethanol’s air quality impacts.”

RFA’s comments also note that real-world data collected by EPA show significant reductions in air pollution during the period of RFS implementation. “Since the RFS was adopted in 2005, EPA data from air monitors show that carbon monoxide concentrations are down 31 percent, nitrogen dioxide is down 22 percent, ozone is down 13 percent, fine particulate matter is down 37 percent, and sulfur dioxide is down 81 percent,” according to the comments. “The levels of all these pollutants have now fallen below the national standard. The emissions trends strongly suggest that increased use of ethanol (which led to a simultaneous reduction in the use of aromatics and olefins) has played an important role in reducing air pollution.”

Growth Energy made similar statements in its comments. “The Renewable Fuel Standard has stood the test of time as America’s single most successful clean energy policy, driving down greenhouse gas emissions while displacing toxic petroleum-based aromatics, like benzene, a known carcinogen,” said Chris Bliley, senior vice president at Growth Energy. “An ever-growing body of evidence confirms ethanol’s role in protecting air quality, and EPA should not be passing up an opportunity to showcase these clean energy solutions.” 

Growth Energy written comments offer a detailed technical analysis on the clean air benefits of homegrown ethanol, illustrating areas where “the Anti-Backsliding Study overstates the RFS’ potential adverse impacts on air quality and understates the emissions and air quality benefits of ethanol-blended fuels.”

Despite the omissions, Growth Energy stressed its support for the agency’s final determination that additional fuel control measures are unnecessary.  
 
“Correction of the Anti-backsliding Study to address these errors would reinforce EPA’s conclusion that new fuel regulations are unnecessary under Section 211(v),” wrote Growth Energy. “In any event, even without such corrections, EPA’s existing analysis amply supports that no new fuels regulations are necessary.” 
 
However, the addition of real-world data would offer policymakers a more accurate view of ethanol’s role in improving air quality, added Growth Energy. 
 
“Using the actual fuel properties of E10 in conventional areas to recreate EPA’s emissions analysis results in substantial decreases in NOx, VOC, and PM emissions, as well as even greater reductions in benzene and 1,3 butadiene, both potent air toxics, as well as carbon monoxide,” wrote Growth Energy. “The emissions reductions associated with the replacement of aromatics with ethanol are consistent with a broad body of scientific literature substantiating the emissions benefits of ethanol-blended fuels.”  

Additional information is available on the regulations.gov website under Docket ID No. EPA-HQ-OAR-2020-0240.