Climate Science and Policy

The Sustainable Aviation Fuel (SAF) industry in the U.S., like the global SAF industry, is still in its infantile stages. But unlike the E.U. which has established a long-term SAF strategy with its mandates under ReFuelEU (requiring 70% of all fuel uplifted at EU airports be SAF by 2050)2, U.S. SAF policy remains in a state of limbo especially as the H.R. 1 bill (President Trump’s “big, beautiful bill”) headed for a Senate vote seeks to hamper the ability of the country’s leading SAF policy - the 45z Clean Fuel Production Tax Credit - to truly encourage sustainable SAF production. This paper provides an overview of the technological options available to the U.S. based on its available resources, finding that despite the early success of the HEFA (Hydrotreated Esters and Fatty Acids) pathway, domestic SAF will have to be carried forward by Alcohol-to-Jet, Gasification, and e-SAF pathways. Policy improvements are then recommended to ensure the environmental and economic sustainability of SAF production, in particular for the Alcohol-to-Jet and e-SAF sectors that have a more complex scaling road ahead of them. The objectives of these recommendations include but are not limited to ensuring a thorough LCA understanding of corn ethanol, strengthening the requirements of the Renewable Fuel Standard, and promoting the competitiveness of American electro-fuels. Their ultimate goal, however, is to reach domestic production levels of truly sustainable SAF in line with the targets of the federal government’s Grand SAF Challenge: meeting the projected domestic demand of 35 billion gallons annually by 2050.