降低喷气航空燃料乙醇的碳强度（英）

Issue Brief 26-03 byMichael A. Toman,Nafisa Lohawala, andJhih-Shyang Shih— April 2026 renewable diesel and other markets, raising concernsabout long-term availability. By contrast, US corn-basedethanol production occurs at large scale, supported byextensive agricultural supply chains and processinginfrastructure, creating the possibility of expandingSAF production by leveraging an established industry.Such expansion may also become more relevantfor ethanol producers if demand for ethanol in roadtransportation declines as electric vehicles gain marketshare. The analysis also noted that ETJ may be morecost-competitive, in part because corn feedstocks aretypically less expensive than vegetable oils. Sustainable aviation fuels (SAFs) are widely viewed asessential in the near-to-medium term for significantlyreducing greenhouse gas (GHG) emissions in theaviation sector. The International Civil AviationOrganization (ICAO) has set a goal of net-zero aviationemissions by 2050, and several jurisdictions—includingthe European Union and United Kingdom—haveadopted policies mandating increasing SAF use. TheUnited States has several tax breaks available to SAFproducers.1Despite these policy signals, however, SAFproduction remains far below the scale required to meetICAO’s longer-term emission-mitigation targets (ICAO2025a). However, the analysis highlighted an importantchallenge: the life-cycle carbon intensity (CI) of corn-based ETJ. CI is a central metric in SAF policy becausemany programs worldwide condition eligibility or creditvalues on the estimated CI of a fuel relative to fossiljet fuel. The CI for corn-based fuels can be substantial,reflecting emissions from fertilizer use, farm energy,ethanol processing, and potential land-use change incrop production. The potential role of corn-based ETJas a low-carbon aviation fuel depends on the extent towhich its CI can be reduced without sharply increasingproduction costs. Several technological pathways exist for producingSAF. One emerging option is ethanol-to-jet (ETJ), whichconverts ethanol derived from biomass into jet fuelthrough a series of chemical processes. Because ethanolproduction is already well established—particularlyin the United States—ETJ has attracted attentionas a pathway that could expand SAF supply in thenear-to-medium term. Companies such as LanzaJet(which began operating the first commercial-scale USETJ facility in 2024), Gevo, and Summit Next Gen arepursuing ETJ. We examine how this CI-reduction challenge couldbe addressed by focusing on emissions-reductionstrategies that the literature identifies as havingrelatively large mitigation potential across the ETJsupply chain. Although these strategies can loweremissions, they also introduce additional costs andinfrastructure requirements that create barriers forscaling up ETJ. Lohawala (2026) examined the potential role of corn-based, or “first-generation,” ETJ in SAF markets bycomparing it with the hydroprocessed esters and fattyacids (HEFA) pathway—the most established SAFtechnology today—which converts lipid feedstocks,such as vegetable oils and animal fats, into jet fuel.That analysis identified several factors that have drawninterest to ETJ relative to HEFA. First, lipid feedstocksare limited and already face competing demand from discounted cash flow analysis in the techno-economicassessment; it does not account for policy incentivesor downstream costs included in the final sales price.Relative to the Lab Study, our estimates incorporatesome additional relevant cost components. Third, wepresent estimates of the marginal costs of reducingemissions for the options considered, relative to fossil jetfuel. Finally, we discuss key implementation challengesand uncertainties in the estimates and the implicationsfor ETJ’s role in reducing aviation emissions. 1.Approach To explore the trade-offs, we draw on a study byresearchers at the National Renewable EnergyLaboratory and Argonne National Laboratory (Uddin etal. 2025; the “Lab Study”). The study provides estimatesof carbon-reduction potential and incremental cost ofseveral strategies in producing corn-based ETJ. Weextend this analysis by incorporating additional costcomponents and examining practical constraints ondeploying the strategies on a larger scale. Life-cycle emissions assessments and techno-economicassessments can vary due to differences in underlyingassumptions. Nevertheless, the estimates from the LabStudy provide a good illustration of both possibilitiesand challenges related to reducing the CI of corn ETJ. The study uses the 2024 Research and Development(R&D) version of Argonne’s Greenhouse Gases,Regulated Emissions, and Energy Use in Technologies(GREET) model developed to estimate life-cycle CI.We focus on strategies that the Lab Study finds to beamong the more effective at reducing the CI of first-generation ETJ production.2These include growingcover crops to increase soil carbon, using lower-carbonenergy sources in the ethanol pl