Aligned with § 40B(e)(2), the agencies participating in the Sustainable Aviation Fuels Lifecycle Analysis Interagency Working Group (IWG) commit that a modified GREET model will be available by March 1, 2024, subject to further guidance by the Treasury Department (Treasury) and the Internal Revenue Service (IRS), to calculate the lifecycle greenhouse gas emissions reduction percentage for SAF sold or used after December 31, 2022. This modified version of GREET will incorporate new data and science, including new modeling runs specific to key feedstocks and processes for use in aviation fuel. The modified GREET model will integrate other categories of indirect emissions, such as crop production and livestock activity, in addition to land use change emissions as informed by GTAP-BIO and/or GCAM. Additionally, the modified GREET model will integrate key greenhouse gas emission reduction strategies such as: Carbon Capture and Storage (CCS), Renewable Natural Gas (RNG), Renewable Electricity, and Climate-Smart Agriculture practices. After the modified GREET model is released, and subject to any further guidance from Treasury and the IRS, a registration applicant using the modified model would also need to meet all statutory requirements under § 40B, including registration, sustainability, traceability, and unrelated party certification.
