Biofuel generated from logging residues could make switching to sustainable aviation fuel (SAF) more cost-efficient and carbon friendly than previously thought, according to new research from the University of Georgia.

In a recent journal article Puneet Dwivedi, a professor of sustainability sciences in the Warnell School of Forestry and Natural Resources, proposed developing SAF from logging residues generated during forest harvests and thinning operations in Georgia, the largest forestry state in the country.

This study focuses on the environmental and economic impacts of SAF production from logging residues in Georgia. By analyzing two production methods, ethanol-to-jet (ETJ) and iso-butanol-to-jet (Iso-BTJ), the study estimates the life cycle carbon emissions and unit production costs associated with SAF.

The minimum aviation fuel selling price (MASP) for ETJ and Iso-BTJ pathways, after accounting for co-product revenues, was $2.71 per liter and $2.44 per liter, respectively, with capital investment at biorefineries, biomass transportation, and variable production costs being the main cost drivers. Dwivedi suggests once government subsidies like the Inflation Reduction Act of 2022 and the Renewable Identification Number credit are considered, the MASP could drop to between $2.29 and $0.83 per liter for ETJ and between $2.04 and $0.59 per liter for Iso-BTJ.

Conventional aviation fuel makes up about 2-3% of all carbon emissions in the United States, Dwivedi said.

“Every industry—like steel, cement, automobiles, etc.—is trying to reduce their carbon footprint,” he said. “However, it’s easier to decarbonize on land than the air.”

Due to their size and weight, airplanes and other aircraft can’t use batteries. Scientists and air industries, however, have been considering switching to a form of biofuel for quite some time, even considering vegetable oil as a potential source.

Several factors play into the costs of biofuel production, including the construction of production facilities and transporting the materials.

The carbon emissions for ETJ and Iso-BTJ fuels are 758 and 976 grams of CO₂ (carbon dioxide) per liter, respectively, which means they produce 70.6% and 62.1% less carbon compared to regular aviation fuel. While using logging residues for SAF can greatly lower the aviation industry’s carbon emissions, government support is needed to help reduce the higher production costs and encourage wider use.

Most logging operations in Georgia take place on private land in partnerships between landowners and companies. Dwivedi noted the environmental concern of cutting down trees, but he pointed out that after the trees are harvested, the landowners would replant the harvested area for starting the next round of forest management.

With a large forestry base and home to Hartsfield Jackson Airport, the busiest airport in the world, Georgia could be the perfect place to begin SAF operations, Dwivedi said.

Published in Elsevier, the paper “Life cycle emissions and unit production cost of sustainable aviation fuel from logging residues in Georgia, United States” was co-authored by Hosne Ara Akter and Farhad Hossain Masum, also of Warnell School.