By Emily Skor, CEO of Growth Energy

As you may have seen in the news, a recent PNAS article by Tyler Lark contains wildly overstated and speculative claims about the environmental impact of biofuels, in particular the relationship between the RFS and greenhouse gas (GHG) emissions.

As has been shown repeatedly, there is simply no evidence that the RFS increases GHG emissions on a lifecycle basis, compared to gasoline.

Quite the opposite, plant-based, cleaner-burning biofuels provide almost 50 percent lifecycle GHG emission reductions compared to gasoline. Further claims that have sought to tie the RFS to impacts to wildlife have been thoroughly disproven.

In addition, to claim that the RFS is a driver of land use change is wholly unsupported by the evidence.

The total acreage of land devoted to corn agriculture has remained unchanged for nearly a century, and to claim that the RFS somehow drives corn prices and land use change is just simply untethered from reality.

We’ll continue to set the record straight on these inaccurate claims and let the science speak for itself when it comes to the many climate and environmental benefits of biofuels.

For a deeper dive, check out this rebuttal from leading scientists.

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On August 8, 2022, the Department of Energy (DOE) sent a letter to Growth Energy in response to our call on the agency to address the inaccurate and misleading study by Tyler Lark and others that claims to have been partially funded by the department.

In response, DOE shared its concerns over the credibility of the findings of the Lark study.

We appreciate the concerns you have raised regarding the study released by Tyler Lark, et al., from the University of Wisconsin-Madison. We share many of your concerns about the methods and assumptions used in the study and are taking steps to ensure that more widely accepted science is shared in the public domain.

DOE shared its support for the use of biofuels, including corn ethanol, as a “readily available energy solution that deserves full consideration when strategizing our energy and environmental agenda.”

The most recent DOE study in 2021 found that U.S. corn ethanol has 44-52% lower greenhouse gas (GHG) emissions than petroleum gasoline. Other credible studies have found similar results. A recent study from researchers at Harvard and other institutions find that conventional ethanol reduces greenhouse gas emissions by 46% relative to gasoline.

On December 14, 2022, the U.S. Department of Agriculture the Department of Energy (DOE) posted a memo in response to Lark’s study in the Proceedings of the National Academy of Sciences echoing concerns of faulty data.

“The findings of Lark cannot be corroborated with USDA site level, modeled, or national datasets. On the contrary, our review concludes that the Lark et al. 2022 significantly overestimated soil carbon losses associated with biofuel production and did not clearly demonstrate a link to the RFS.”

Based on USDA’s review of Lark et al. 2022, they identified three major methodological flaws with the soil carbon calculations:

  • Failure to account for cropland-to-cropland conversions that would occur from the increase in corn ethanol demand. This could include, for instance, the transition of land that is moving in-and-out of other row crops into corn production.
  • The (mis)classification of CRP land as native or longer-term grasslands in the soil carbon calculations.
  • The carbon response functions used by Lark et al. (2022), from Poeplau et al. 2022, are misapplied and overestimate emissions from grassland-to-cropland conversions.

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