Might jet fuel be produced from human sewage?
A company called Firefly Green Fuels, based in Gloucestershire, is trying to make jet fuel out of human faeces. It is a waste stream that is currently not used, except for as fertiliser for agriculture (which is controversial, due to the danger of a range of chemicals that are not removed from sewage, and microplastic particles). Currently human waste, ie. sewage, breaks down and emits CO2, among other things. If sewage is used to make allegedly low carbon jet fuel, it would need complex treatment requiring a lot of energy, and there would be a further waste product in the end. Such fuels, which could just as well be used for vehicles etc on the ground, as for aviation, would emit just as much CO2 when burned as conventional fuels. Burned in jet engines, it would also produce contrails – which have their own atmospheric heating effect. Supposing jet fuel, or other vehicle fuel, could be produced from human sewage, there might then be a need for another agricultural fertiliser to replace it. The aviation industry is trying to find fuels that it can claim are “low carbon”, if they are produced from carbon that has come from plants or animals – rather than fossil fuels. . Tweet Poop-powered planes: could jet fuel made from sewage take off? By Nell Lewis, CNN January 5, 2024 In the race for alternative, sustainable jet fuels, some companies are getting creative. We’ve heard about planes powered with cooking oil, but what about jet fuel made entirely from human poop? Firefly Green Fuels, an aviation company based in Gloucestershire, UK, has created just that – and, unsurprisingly, the prospect of poop-powered planes is attracting attention. While sustainable aviation fuel (SAF) is not new, the idea of using sewage – an abundant and unavoidable waste – is a novelty. So, could it really be the future of air travel? Commercial aviation produces about 2.5% of global carbon emissions, contributing to climate change. Efforts to reduce the sector’s impact are underway, with the development of electric and hydrogen-powered planes. But the technology is still a long way off powering long-haul passenger flights. Instead, the industry is looking to use SAF – with the International Air Transport Association (IATA) estimating that it could contribute up to 65% of the reduction in emissions needed for aviation to reach net-zero in 2050. SAF burns like normal jet fuel and produces the same amount of emissions while a plane is flying, but it has a lower carbon footprint during its entire production cycle, because it’s usually made from plants that have absorbed carbon dioxide (CO2) from the atmosphere when they were alive. Or, in the case of sewage, it’s made from plants and other food that have been eaten by humans and passed through the digestive system. That absorbed CO2 is released back into the atmosphere when the SAF burns, whereas burning jet fuel made from fossil fuels emits carbon that has been locked away. So far, sewage has been an untapped resource when it comes to SAF, but James Hygate, CEO of Firefly, thinks this is a missed opportunity. “There’s loads of it, it’s everywhere in the world and there’s not really any good use for it at the moment which makes a very low-value material,” he tells CNN. That’s why the company, a spin-off from Green Fuels, which has been developing low-carbon fuels since the early 2000s, including biodiesel made from rapeseed oil for cars and trucks, turned its hand to jet fuel – and poop. Processing poop To turn human waste into a usable fuel, Firefly uses a method called hydrothermal liquefaction, which is good for wet waste. By combining high pressure and heat, it converts the sewage into carbon-rich biochar (a powder that can be used as a crop fertilizer) and crude oil. So far, production has been on a small scale in a laboratory. But early results have been promising, with independent analysis by researchers in universities in the EU and US finding it almost identical to standard fossil jet fu