Start-up turns human waste into sustainable kerosene

The company Firefly Green Fuels turns human waste into sustainable kerosene. The fuel has a 90 percent lower CO2 footprint than conventional kerosene.

What is available in large quantities, can be produced again and again without any problems and is also cheap? Human feces! James Hygate finds these eliminations, which usually fill very few people with enthusiasm, “exciting”.

The Brit is CEO of the company Firefly Green Fuels, which specializes in sustainable fuel. For a long time, Hygate worked with old vegetable oil. But a while ago he came up with a new idea: turning human feces into kerosene.

Firefly Green Fuels: Aus Kot mach Kerosin

To do this, he met with the chemist Dr. Sergio Lima from Imperial College London. In a first step, they produce pyrolysis oil, which Lima and Hygate call “organic raw”. According to Lima, this thick, black slurry behaves chemically like crude oil.

The substance is then heated, distilled and made into usable fuel. The exciting thing about it: The carbon footprint of this fuel is 90 percent lower than conventional kerosene, as a joint study with Cranfield University has shown. James Hygate speaks of a kerosene that is “free from fossil fuels”.

Of course, energy is needed to produce organic kerosene. But Lima finds the fact that this would result in 90 percent CO2 savings over the entire life cycle of the feces kerosene simply “crazy”.

Independent testing has shown that Firefly Green Fuels' kerosene is almost identical to standard aircraft fuel. The process could therefore make an interesting contribution to making global air traffic more sustainable. The German Aerospace Center is already experimenting with the process.

The race for sustainable aviation fuels

Globally, air traffic accounts for around two percent of the global carbon footprint. But this proportion is increasing very quickly. And: Propelling aircraft more sustainably is much more difficult than with other means of transport. This is particularly true for long-haul aircraft. Because while aircraft can certainly be powered electrically for short distances, this is more difficult for long distances.

Powering aircraft with batteries is complicated. Because recharging during the flight is not possible. In order to offer enough range, correspondingly large batteries would have to be used, which in turn would significantly affect the weight of the aircraft. Hydrogen aircraft are also a possibility, but they are still in their early stages.

Therefore, kerosene from old vegetable or cooking oils is currently often used for sustainable aviation fuels (SAF). Because old oils cannot fully cover demand, new vegetable oil is also produced for SAFs.

But that's not ideal. This requires land that agriculture then lacks for growing food. This means that biofuel and food are in direct competition. Growing plants intended for biofuel can also lead to monocultures, which then degrade the soil. At the same time, these cultivation areas also take up a lot of space.

All of this is problematic. That's exactly why Firefly Green Fuels' feces approach is so interesting. Because the excretions arise anyway. Nobody needs the feces for anything else and they can easily be produced again and again, locally too.

Limitations of kerosene from feces

At the same time, fecal kerosene is certainly not a panacea for making air travel more sustainable. According to James Hygate's calculations, a return flight between London and New York would require the annual excreta of 20,000 people, assuming that each person could produce around four to five liters of fuel per year through feces.

The entire UK would therefore only be able to produce around five percent of the kerosene required for air traffic using faeces. This is still significant for Hygate.

Airlines in the UK currently have to use ten percent sustainable fuel. Half of this could be covered with feces alone. And: worldwide, only 0.2 percent of aircraft fuel is sustainable. Feces could at least increase this proportion.

Whether Firefly Green Fuels' process can be scaled also depends on how expensive and complex it is. Because if the processing of the poop is more expensive than organic kerosene made from vegetable oil, then the poop kerosene will have a hard time asserting itself.

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