Aviation’s new fuel source? The carbon waste from your cornfields.De Smet Engineers & Contractors (DSEC)
Carbon dioxide emitted from ethanol plants could be repurposed to create low-carbon jet fuel. This new type of jet fuel can cut aviation emissions by more than 80 percent compared to fossil fuels, according to new research published in the SAE International Journal of Sustainable Transportation, Energy, Environment, and Policy.
The study reveals a promising opportunity to turn what is currently considered waste into a valuable and sustainable energy resource.
During ethanol production, the fermentation process releases approximately 85 percent of the volume as highly pure carbon dioxide. This makes it easier and less energy-intensive to capture than CO₂ from coal or cement plants. Since the corn used to make ethanol already absorbs CO₂ from the atmosphere, reusing the gas released during fermentation would recycle existing carbon rather than add more to the air.
“It is exciting to explore whether this ‘waste’ stream can actually become a significant asset, turning inefficiency into advantage and accelerating the real-world application of emerging technologies,” said Stephen McCord in a press release. He is a research scientist in mechanical engineering at the University of Michigan and the lead author of the study.
Aviation generates over a gigaton of fossil CO₂ emissions annually, making it one of the most challenging sectors to decarbonize.
Sustainable aviation fuels (SAFs) derived from biomass waste or used cooking oils are already in limited use, but scaling up their production remains a challenge. In 2023 alone, U.S. ethanol production reached 15.6 billion gallons, emitting 48 megatons (million metric tons) of CO₂, an untapped feedstock.
The study notes that could be redirected toward SAF production.
Comparing pathways to low-carbon flight
The researchers evaluated several methods for producing jet fuel from ethanol and CO₂. The conventional Alcohol-to-Jet process, which converts ethanol into aviation fuel with a yield of roughly 90 percent, reduces carbon intensity by only 4.5 to 20 percent compared to kerosene.
To identify better alternatives, the team analyzed two CO₂-based routes that begin by converting captured CO₂ into synthesis gas, or syngas, a mix of carbon monoxide and hydrogen. In the gas fermentation route, syngas is first converted into ethanol, which is then refined through Alcohol-to-Jet conversion. In contrast, the Fischer-Tropsch Synthesis method directly transforms syngas into long-chain hydrocarbons similar to jet fuel.
A life cycle assessment revealed that both methods significantly outperformed the conventional approach. Fischer-Tropsch could reduce carbon intensity by up to 90 percent, while gas fermentation achieved reductions of around 84 percent.
“We hope to inform future development and policy by highlighting which routes are most promising for reducing aviation’s carbon footprint using existing waste resources,” said Volker Sick, former Director of the Global CO₂ Initiative and DTE Energy Professor of Advanced Energy Research at U-M, who served as senior author.
A faster path to scale
Although Fischer-Tropsch offered slightly higher reductions, gas fermentation followed by alcohol-to-jet was identified as the most practical short-term solution. The study notes that this pathway could leverage existing ethanol infrastructure and workforce expertise, allowing for faster industrial deployment.
“A variety of factors need to be considered when planning how to produce large quantities of sustainable aviation fuels from CO₂. Starting with CO₂ from corn ethanol fermentation promises the fastest path to scaling up this new industry,” said Sick.
While electrification and hydrogen tech continue to face limitations for long-distance flight, the study argues that sustainable hydrocarbon fuels will remain essential. “These conversion routes provide a viable way to ‘defossilize’ aviation fuel and make meaningful progress towards reducing aviation’s carbon footprint, offering a realistic, near-term solution where alternatives are limited,” McCord added.
