Lowering the Carbon Intensity of Ethanol-to-Jet Aviation Fuel

Sustainable aviation fuels (SAFs) are widely viewed as essential in the near-to-medium term for significantly reducing greenhouse gas (GHG) emissions in the aviation sector. The International Civil Aviation Organization (ICAO) has set a goal of net-zero aviation emissions by 2050, and several jurisdictions—including the European Union and United Kingdom—have adopted policies mandating increasing SAF use. The United States has several tax breaks available to SAF producers. See Lohawala et al. (2026) for an overview of SAF policy frameworks in the United States and other jurisdictions. Despite these policy signals, however, SAF production remains far below the scale required to meet ICAO’s longer-term emission-mitigation targets (ICAO 2025a).Several technological pathways exist for producing SAF. One emerging option is ethanol-to-jet (ETJ), which converts ethanol derived from biomass into jet fuel through a series of chemical processes. Because ethanol production is already well established—particularly in the United States—ETJ has attracted attention as a pathway that could expand SAF supply in the near-to-medium term. Companies such as LanzaJet (which began operating the first commercial-scale US ETJ facility in 2024), Gevo, and Summit Next Gen are pursuing ETJ.Lohawala (2026) examined the potential role of corn-based, or “first-generation,” ETJ in SAF markets by comparing it with the hydroprocessed esters and fatty acids (HEFA) pathway—the most established SAF technology today—which converts lipid feedstocks, such as vegetable oils and animal fats, into jet fuel. That analysis identified several factors that have drawn interest to ETJ relative to HEFA. First, lipid feedstocks are limited and already face competing demand from renewable diesel and other markets, raising concerns about long-term availability. By contrast, US corn-based ethanol production occurs at large scale, supported by extensive agricultural supply chains and processing infrastructure, creating the possibility of expanding SAF production by leveraging an established industry. Such expansion may also become more relevant for ethanol producers if demand for ethanol in road transportation declines as electric vehicles gain market share. The analysis also noted that ETJ may be more cost-competitive, in part because corn feedstocks are typically less expensive than vegetable oils.However, the analysis highlighted an important challenge: the life-cycle carbon intensity (CI) of corn-based ETJ. CI is a central metric in SAF policy because many programs worldwide condition eligibility or credit values on the estimated CI of a fuel relative to fossil jet fuel. The CI for corn-based fuels can be substantial, reflecting emissions from fertilizer use, farm energy, ethanol processing, and potential land-use change in crop production. The potential role of corn-based ETJ as a low-carbon aviation fuel depends on the extent to which its CI can be reduced without sharply increasing production costs.We examine how this CI-reduction challenge could be addressed by focusing on emissions-reduction strategies that the literature identifies as having relatively large mitigation potential across the ETJ supply chain. Although these strategies can lower emissions, they also introduce additional costs and infrastructure requirements that create barriers for scaling up ETJ.