Airlines are struggling to meet climate mandates and their own net-zero targets as sustainable aviation fuel remains scarce and expensive.
As governments push carriers to use more of it, airlines are increasingly exploring new technologies, including one that turns sewage into jet fuel.
Sustainable aviation fuel currently accounts for about 0.5% of global jet fuel use and is mainly made from used cooking oil. But that supply is limited, and production has failed to keep pace with policy ambitions — more SAF plants were canceled than approved in 2025.
One option drawing interest is hydrothermal liquefaction (HTL), a process that converts sewage, wastewater, and other organic waste into an oil that can be refin