There’s a ritual involved in creating the perfect Sichuan hot pot and it involves fat — lots of it. Diners first immerse slivers of meat in a spicy soup rich in molten animal tallow, then dip each morsel in a plate of vegetable oil, before finally devouring it. It’s a rich delicacy, one that produces about 12,000 tons of waste oil each month in the Chinese city of Chengdu alone.
So in 2016, a startup began exporting some of that leftover restaurant grease to Europe and Singapore, where it gets recycled into fuel pure enough to fly airplanes.
Responsible for around 2% of the world’s total emissions of planet-warming gases, the aviation industry is under pressure to find greener ways to power its jet engines. Several major airlines, including British Airways, Cathay Pacific Airways and Delta Air Lines, have pledged to replace about 10% of their jet fuel with a sustainable alternative by 2030, and more than 50 have begun to experiment with it, but cleaner substitutes are still being developed.