Startup Firefly Green Fuels is raising eyebrows in the aviation industry by creating a sustainable aviation fuel completely derived from human wastewater . This achievement is notable as independent aviation industry regulators have verified that, although the new fuel bears chemical similarities to kerosene derived from fossil sources, it does not contain fossil carbon, making it a truly sustainable fuel.
Although the transition to electric or hydrogen-powered aircraft will take several years, Sustainable Aviation Fuels (SAF) emerge as a viable solution to continue using large aircraft without contributing to global emissions. James Hygate, CEO of Firefly Green Fuels, began converting rapeseed oil into biodiesel for vehicles two decades ago and his company, which currently supplies equipment to convert cooking oil into biodiesel globally, has turned its attention to applying this approach to aircraft engines.
After exploring various sources of organic waste, Hygate, in collaboration with chemist Dr Sergio Lima of Imperial College, London, identified the potential of human wastewater as a feedstock. Together, they developed a process known as hydrothermal liquefaction (HTL) , which transforms wastewater into “bio-crude,” a substitute for crude oil that is processed into SAF.
The HTL process also generates biochar, which can be used for carbon capture in construction and agriculture, improving soil quality. Simultaneously, biokerosene derived from this process undergoes independent testing, demonstrating a virtually identical chemical composition to conventional fossil-based A1 jet fuel.
The team has been the recipient of a £2 million research grant awarded by the UK Department for Transport. Additionally, a full-scale demonstrator plant is being planned for construction in the United Kingdom to carry out further development of this technology.
The future of sustainable aviation fuel
Firefly Green Fuels aims to make its approach more widely accepted than crop-based Sustainable Aviation Fuels (SAF), as the use of human waste does not compete with food security. It is estimated that by processing all of the UK’s wastewater, 5% of aviation fuel demand could be met, moving closer to the 10% target for SAF.
This advancement not only represents an innovative and sustainable solution for the aviation industry, but also addresses the issue of waste management, transforming an abundant and unwanted resource into a valuable fuel for the future of aviation.
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