The Renewable Fuels association is urging federal officials to use a 30-year time frame to account for land use change (LUC) emissions as they work to complete the upcoming 40BSAF-GREET model, which will be used to calculate emissions reductions for the sustainable aviation fuel (SAF) tax credit. 

The Sustainable Aviation Fuel Interagency Working Group is a coalition of experts representing the USDA, U.S. EPA, U.S. Department of Energy and U.S. Department of Transportation’s Federal Aviation Administration that was formed last year to create the updated 40BSAF-GREET model, which is expected to incorporate new data and science, including new modeling of key feedstocks and processes used in aviation fuel.

The working group in December 2023 set a self-imposed deadline to issue the 40BSAF-GREET model by March 1. Agriculture Secretary Tom Vilsack on that date announced release of the model would be delayed by “weeks, not months,” citing the need to get calculations for climate-smart agriculture right. 

In a letter sent to the working group on April 1, the RFA outlines the important of ensuring the 40BSAF-GREET model’s time period for greenhouse gas (GHG) emissions accounting is consistent with methods that have already been determined by the U.S. Treasury to satisfy the criteria of Section 2011(o)(1)(H) of the Clean Air Act. The RFA is specifically urging the working group to use a 30-year time period for emission accounting, which is the same time period that is used in Renewable Fuel Standard regulations. 

“Using a different time period (e.g., 25 years) for emissions accounting would render the upcoming 40B(e)(2) GREET model inconsistent with CAA Section 211(o)(1)(H),” the RFA wrote in the letter. “Failing to use a 30-year time period would also render the modified GREET model inconsistent with the only ‘similar methodology’ (i.e., EPA’s RFS program) that has been approved, to date, by Treasury for emissions calculations under the 40B credit.”