UK Company Creates SAF from Sewage

While the roster of feedstocks utilized for sustainable aviation fuel (SAF) continues to grow, one of the most ubiquitous and intriguing being explored by a UK company is sewage. Gloucestershire-based Firefly Green Fuels has developed a process to turn human waste into SAF.

A 20-year veteran of the biofuels industry, company CEO James Hygate set out to find a low-value, abundant feedstock to use in SAF production. “Globally, sewage is a material in constant production; it's an unavoidable byproduct of human existence,” he told AIN.

“We know that in many places this sewage is already processed, leaving a tricky-to-dispose final product known as sewage sludge or biosolids. In the UK, we are engaged in very productive talks with utility companies who are excited about the potential of our technology to take this problematic waste product off their hands.”  

Using a new process, Firefly Green Fuels has successfully produced samples of SAF from sewage sludge and expects to submit its pathway to ASTM International, the international standards organization, by year-end.

“It's hard to say for certain how long the process will take, but we're reliably informed that it'll take at least a year to get a green light,” said Hygate, adding that the fuel will be considered a drop-in fuel and will be usable in existing infrastructure. Studies have demonstrated that Firefly's pure SAF can provide 90 percent lifecycle carbon emissions savings compared to traditional fossil-based fuels, but like all other SAFs—currently, at least—it will require blending with conventional jet fuel for use.

The company has calculated that each person produces enough raw waste to make slightly more than one gallon of SAF a year. As an example, a typical large-cabin business jet will burn 3,500 gallons of fuel during a transatlantic flight. “Whilst there isn't nearly enough waste for this solution to power every flight in the world, we can make a significant impact towards reducing the aviation industry's fossil fuel dependency,” Hygate noted.

The company’s plans call for its first commercial plant to come online before the end of the decade. It will be able to convert 1 million tonnes of biosolids into 43,000 tonnes of SAF, along with other byproducts. “Once this hurdle has been overcome, we expect interest in our solution to massively expand, and we foresee significant global growth from 2030 onwards,” Hygate stated.

Aside from establishing a new pathway for SAF production and contributing to the aviation industry's sustainability, the company views its process as a potential lever for wider environmental, social, and economic change.

“By implementing our technology in global locations where, for example, raw sewage is currently discharged into waterways, we will support significant improvements in biodiversity and public health,” said Hygate. “Our solution could also be seen as a route towards energy independence for countries that currently rely on fuel imports to fly their jets.”