A circular hydrothermal refinery for sustainable aviation fuel from food waste

The aviation industry faces a formidable challenge in transitioning to carbon-neutral flight without compromising the rigorous performance standards of jet engines. While hydrothermal liquefaction (HTL) of wet waste offers a transformative pathway for sustainable aviation fuel (SAF) production, its potential remains hindered by biocrude quality and the environmental burden of the aqueous phase (HTL-AP). Here we present an integrated hydrothermal refinery that converts food waste into a high-performance SAF candidate through a closed-loop process of HTL, catalytic upgrading and HTL-AP valorization. Our refined fuel—composed predominantly of cycloalkanes (70.5 wt%)—exhibits a higher heating value and lower freezing point than conventional Jet A. Critically, unlike alcohol-to-jet or hydrotreating esters and fatty acids (HEFA) pathways, this HTL-derived SAF meets flash point and viscosity constraints as a 100% drop-in fuel without blending. We further address the ‘waste’ bottleneck by employing partial electrooxidation and electrodialysis to recover high-purity acetic acid (91.6% of organics) and nutrients (>76.9%) from the HTL-AP, while simultaneously generating sufficient hydrogen to sustain the biocrude hydrotreating stage. Techno-economic and life-cycle analyses reveal that while electricity costs currently influence the minimum fuel selling price, the integration of renewable energy and optimized electrochemical recovery can achieve market competitiveness (US$3.82 GGE⁻¹) and a net-negative carbon footprint (−8.5 kg CO₂e GGE⁻¹). These findings establish a circular, carbon-negative framework for transforming urban organic waste into high-density aviation energy.