A University of Illinois Urbana-Champaign research team has developed a process to convert food waste into sustainable aviation fuel, offering a potential new pathway to expand supply for the growing low-carbon fuel market.
The work, published in *Nature Sustainability*, examines both the technical and economic viability of producing jet-grade fuel from urban organic waste, an area of increasing interest as the aviation industry seeks to reduce greenhouse gas emissions.
The process builds on earlier research by converting food waste into biocrude through hydrothermal liquefaction, or HTL, which accelerates the natural crude oil formation process. That biocrude is then refined into aviation fuel using catalytic upgrading and distillation.
In the latest study, researchers simplified the refining process by reducing catalytic intensity and relying more heavily on distillation, a widely used industrial process. The approach lowered costs and reduced environmental impacts compared with earlier methods, though the resulting fuel requires blending with conventional jet fuel to meet performance requirements.
Researchers tested the fuel against standards established by ASTM International and the Federal Aviation Administration, using a 50-50 blend with petroleum-based jet fuel. The findings suggest lower blend ratios, such as 10% to 20%, could also be viable for commercial use.
The project remains at the lab scale, with the team now capable of producing several liters of upgraded fuel for diesel engine testing. Jet engine trials are expected as the next phase of development.
Researchers identified feedstock collection as one of the largest barriers to scaling SAF production. Much of the available food waste currently ends up in landfills or wastewater treatment systems, creating logistical challenges for recovery and reuse.
The HTL process can use treated wastewater solids as feedstock, broadening the range of usable waste streams. However, it also produces a byproduct known as HTL aqueous phase, or HTL-AP, a nutrient-rich but potentially toxic liquid residue.
To address that challenge, the research team studied electrochemical treatment as a way to recover acids and nutrients from HTL-AP while reducing waste.
The study modeled three processing scenarios: a baseline in which HTL-AP is sent to a centralized wastewater treatment facility, a second scenario incorporating electrochemical recovery technology, and a future scenario assuming improved electrochemical efficiency.
The analysis found that the current electrochemical system nearly tripled production costs per gallon compared with the baseline because of higher capital and operating expenses. However, researchers project future improvements could reduce those costs to comparable levels.
Lifecycle analysis also showed both the baseline and improved electrochemical scenarios could achieve net-negative carbon emissions, lowering the fuel’s overall global warming potential.
The findings highlight a potential circular bioeconomy model in which urban food waste is converted into transportation fuel while reducing waste disposal burdens and carbon emissions.
Source: University of Illinois, "Illinois study explores feasibility of creating sustainable jet fuel from food waste"