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U.S. Renewable Fuel Standard Should Be Informed by Environmental Impact

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EPA’s change to the RFS will generate increased greenhouse gas emissions from transportation fuel use over the next several years.

For the first time in the short history of the U.S. government’s Renewable Fuel Standard, the Environmental Protection Agency (EPA) has proposed to decrease the total amount of renewable fuel required as part of the national supply, with a 41 percent cut to the advanced biofuel category.

But a study recently published by our organization found that EPA’s proposed reductions in biofuel use in 2014 would automatically increase use of petroleum and increase the associated emissions of greenhouse gases. In order to achieve lower emissions in 2014, compared to 2013, EPA must ensure an increase in biofuel use.

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Our study, published in the Industrial Biotechnology Journal, examines the EPA’s proposed rules. It is available online and we invite responses.

If the EPA’s proposal undermines development of advanced biofuels—as we expect it will—the United States will forgo measurable reductions in greenhouse gas emissions over many years. Advanced biofuels must demonstrate a reduction in greenhouse gases of at least 50 percent compared to a baseline of petroleum gasoline or diesel produced in 2007. But if EPA continues to use the proposed methodology for setting the annual RFS obligations in future years, U.S. greenhouse gas emissions from transportation fuels will remain above the 2013 level for many years. (See related coverage: “Biofuels at a Crossroads.”)

The model we developed begins with Energy Information Administration projections of fuel use from 2013 through 2022. EIA predicts that diesel use will steadily increase over the time period and gasoline use will increase in the short term before continuing its long range decline. Gasoline use in the United States peaked in 2007, but has declined in recent years due to the economic downturn. Its use is expected to continue to decline as fuel economy standards that favor diesel use come into effect.

We next calculated the percentages of petroleum blendstock for gasoline and diesel, ethanol, biodiesel, advanced and cellulosic biofuels that would be used each year under various scenarios—the EPA’s newly proposed methodology, the statutory RFS rules, and a continuation of the past practice of setting the advanced biofuel volume obligation at the highest achievable level. The volumes of each portion of the fuel supply were then assigned GHG emission scores—measured in metric tons of CO2 equivalent—and an annual total was tallied for each scenario.

The greenhouse gas emission scores are drawn from a model that includes land-use change calculations for biofuels. This model also includes an updated emissions profile for petroleum fuels, since the United States now relies more on marginal sources of petroleum—such as Canadian oil sands—than it did in 2007. (Take the quiz: “What You Don’t Know About Biofuel.”)

However, our model allows for EPA’s estimates of emissions to be assigned to the volumes. Substitution of EPA estimates would not change the primary and secondary findings of our study. If we increase petroleum in our fuel mix over the next few years by decreasing biofuel use, that petroleum will most likely come from Canadian oil sands and include more lifecycle carbon emissions.

The study also demonstrates that increased fuel efficiency standards may not by themselves achieve reductions in greenhouse gas emissions. In the short term, economic recovery could unleash pent-up demand for transportation fuel. And over the next decade, fuel economy standards will continue to boost use of diesel fuel even while lowering gasoline use. Diesel fuel emits more carbon during its lifecycle. And, if the petroleum used also emits more carbon over its lifecycle, the impact of decreased use could be offset significantly. A combination of fuel efficiency and use of lower carbon fuels is needed to achieve year-over-year reductions in carbon emissions.

When making changes to the renewable fuel standard, EPA must evaluate the impact of its rules on the environment, including climate change; energy security; future commercialization of advanced biofuels; sufficiency of infrastructure to deliver and use biofuel; costs to consumers; and job creation, rural economic development, and food prices. We published this study as a contribution to the EPA’s evaluation of its rule and its impact on climate change. Our hope is that EPA incorporates it into its analysis of the final rule, due in June. (See my earlier post: “Why New Biofuel Feedstocks Deserve Investment, Incentives.”)