Firefly specialises in a process which converts sewage sludge, a low-value waste product available in large quantities, into SAF.

More than 57 million tonnes of sewage sludge are produced in the UK each year, with the potential to produce 250,000 tonnes of SAF.

Firefly’s SAF, which will be independently certified against the sustainability standard RSB, is projected to deliver a 90% reduction in greenhouse gas emissions compared to fossil jet fuel on a life cycle basis.

The agreement with Firefly and investment in new SAF technology represents the latest milestone in Wizz Air’s broader sustainability strategy, including its fleet renewal plan and already low-cost operations with the latest technology aircraft and high seat density and load factors.

Michael Berlouis, head of strategic projects at Wizz Air, said: "In addition to fleet renewal and operational efficiency, SAF is crucial for reducing carbon emissions from aviation.

"However, feedstock availability remains the key challenge for the industry. Our investment in Firefly and its sewage sludge SAF technology is a major step forward for Wizz Air in securing its long-term ability to provide low-cost fares to its customers in an ever more environmentally sustainable way."