Here are the facts: commercial aviation contributes 2.5% to the total global carbon emissions that negatively affect climate change. Technology is nowhere near the point of long-faul passenger flights being electric or hydro-powered, so instead, airlines are looking to alternative, more sustainable jet fuels and some companies are getting creative. The International Air Transport Association (IATA) estimates that sustainable aviation fuel (SAF) could help the aviation industry reach its net-zero target in 2050 by contributing up to 65% of the reduction in emissions. 

Cue: Firefly Green Fuels, an aviation company based in Gloucestershire, UK, has created a jet fuel that is made entirely from human faeces. Yes, you read that right, poop. While SAF burns like normal jet fuel and the same amount of emissions are released while the plane is in air, it does still have a lower carbon footprint overall. 

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During the production process SAF takes materials that have already absorbed carbon dioxide (CO2) like plants, or in this case, sewage. That absorbed CO2 is released back into the atmosphere when SAF burns. Regular jet fuel is made from fossil fuels which emits carbon that has been locked away. 

So how does Firefly Green Fuels turn human poop into usable fuel? It used hydrothermal liquefaction, which combines high pressure and heat to convert the sewage into carbon-rich biochar and crude oil. While production has only been on a small scale in a lab, early results are promising with independent analysis finding it almost identical to standard fossil jet fuel with a 90% lower carbon footprint. 

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