US EPA’s RFS anti-backsliding study discounts biodiesel benefits

By Ron Kotrba | July 09, 2020

The National Biodiesel Board submitted its formal comments July 8 to the U.S. EPA on the agency’s Renewable Fuel Standard Anti-Backsliding Determination and Study. The EPA issued a rulemaking May 29 proposing to determine that no additional appropriate fuel control measures are necessary to mitigate air quality impacts of required renewable fuel volumes under the RFS.

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 proposed the latter.

In the NBB’s comments, Kurt Kovarik, vice president of federal affairs for the organization, noted that NBB supports EPA’s determination that no additional fuel control measures are necessary, but he added that the association believes the study undercuts the known benefits of the RFS program on air quality. More specifically, since the study only considers blends of 5 percent biodiesel, NBB said it “fails to acknowledge the known linear beneficial decrease in emissions from increased use of higher blends of biodiesel.”

Kovarik went on to explain that, according to the Diesel Technology Forum, only 43 percent of U.S. commercial trucks have modern aftertreatment systems to significantly reduce NOx and particulate matter (PM) emissions, leaving a majority of on-road diesels without the significant emissions controls.

“As a result,” he wrote, “the impact that biodiesel will have on on-road engines alone is greater than the anti-backsliding study suggests. Additionally, while EPA acknowledged the limited data on emissions in nonroad engines using biodiesel, there are known benefits. Because nonroad engines typically do not utilize diesel particulate filters or any other advanced emission control devices, greater emissions benefits can be obtained by using biodiesel at any blend level, due to the emissions profile of biodiesel.”

Compared to fossil diesel, biodiesel has several benefits greenhouse and tailpipe emissions benefits, including reducing lifecycle greenhouse gases by 86 percent, PM by 47 percent and hydrocarbon emissions by 67 percent, among others.

In NBB’s comments to EPA, Kovarik detailed several emissions studies, highlighting the benefits of biodiesel blends greater than 5 percent, and even brought to EPA’s attention the inconsistencies in its own previous studies on biodiesel vs. findings in the recent anti-backsliding study.

“In a 2008 study, EPA found that biodiesel had roughly 10 times less emissions of PM compared to distillate fuel oil,” he wrote. “The same study found that SO2 was nearly four times higher for the distillate petroleum fuel oil than for biodiesel, and NOx emissions were slightly higher for the distillate fuel. This finding differs from the anti-backsliding study that showed no difference in SOx and an overall 0.4 percent increase in NOx for on-road biodiesel. Overall, according to EPA, biodiesel emitted less pollutants than the distillate fuel oil, and the low-lifecycle CO2 emissions for the biodiesels results in a net CO2 reduction of nearly 75 percent when compared to the petroleum distillate fuel.”  

The use of increasing biodiesel volumes helps improve on-road, off-road and other applications, such as the heating oil industry, Kovarik stated. “The absence of EPA’s historical data of biodiesel use across the country should not discount the benefits of biodiesel that are clearly known and articulated through existing reliable data,” he wrote. “Failure to account for the impacts of both higher and lower biodiesel blends, assuming B5 across the nation, does a disservice to the industry that is working to continuously improve [its] tailpipe emissions profile … The potential for tailpipe emission reductions and reductions in emissions toxicity by using biodiesel in all applications should not be ignored.”

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