Aviation emits around one billion tonnes of CO₂ each year. A promising sustainable aviation fuel feedstock has been sitting in drums, largely unused, for decades

Flying accounts for roughly 2.5% of global CO₂ emissions. That figure sounds modest until you factor in aviation’s full climate impact at altitude: contrails, nitrogen oxide effects, and other non-CO₂ warming push aviation’s effective climate impact to roughly two to three times its CO₂ contribution alone. Unlike road transport, aviation cannot wait for batteries. The energy density required to lift a fully loaded aircraft does not fit inside any electrochemical storage technology within a commercially realistic timeframe. That leaves one serious near-term option: sustainable aviation fuel.

The SAF market is growing fast, but not fast enough. Global production reached approximately one million tonnes in 2024, double the year before, and demand is being locked in by mandate. The UK requires 10% SAF blending by 2030, rising to 22% by 2040. For UK airlines alone, that implies procurement of over one billion litres of SAF annually by the end of the decade, most of which has no confirmed domestic supply source. The EU’s ReFuelEU Aviation regulation sets similar, and in later years even higher, blending mandates across 27 Member States. Market analysts put the global SAF opportunity at $15–20bn annually by 2030. Yet, current production covers less than 0.5% of jet fuel demand, and the dominant pathway, hydroprocessed used cooking oil, is approaching feedstock limits. The supply gap is structural, not temporary.

The feedstock sitting in plain sight

The UK holds substantial biomass resources: agricultural and forestry residues, energy crops, and organic waste streams representing tens of millions of tonnes of dry biomass annually, as reflected in the UK’s 2023 Biomass Strategy scenarios. Much of it is currently used for low-value heat generation or left as field residue. Fast pyrolysis, a thermochemical process that heats biomass rapidly in the absence of oxygen, can convert this material into a liquid intermediate in seconds. The technology is mature and commercially available today.

The liquid it produces, fast pyrolysis bio-crude, is dark, pungent, and chemically complex. Globally, a few hundred thousand tonnes are produced annually, from a handful of commercial plants, used mainly for industrial heat, co-firing in power stations, or as a feedstock for smoke flavourings and wood preservatives. It has never fulfilled its potential as a SAF precursor. Not because the energy is not there, but because no one had found a clean way to extract it.

20 years to this moment

Dr Sanjeev Gajjela first worked with fast pyrolysis bio-crude as a doctoral student at Mississippi State University. He spent the following two decades developing bio-crude upgrading processes across industry and academia, accumulating around 40 patent filings along the way. The photograph supplied with this article was taken at a commercial tolling facility in South Carolina, USA, where bio-crude upgrading work was carried out on contract during earlier industry research. That work, and two decades like it, is what PySAF’s fractionation platform is built on.

The sample in the vial he is holding is upgraded fast pyrolysis bio-crude, labelled pyroligneous acid for shipping purposes – the same material contained in the drums behind him. He has been trying to unlock its potential ever since.

When he founded PySAF Ltd in late 2025, the question driving it was one that had followed him throughout his career: why is this feedstock still being wasted?

Separating the problem

The answer PySAF has developed is a proprietary fractionation process that splits fast pyrolysis bio-crude into two distinct streams before any further upgrading occurs.

The first, PyXCrude™, concentrates the lipophilic and phenolic fractions into a material with substantially improved fuel properties: water content below 1%, 97% metals removal versus raw bio-crude, and a higher heating value of around 30 MJ/kg. It is designed for catalytic hydrotreating to produce SAF blendstock, and is also compatible with co-processing at existing petroleum refineries. The second stream, PyXSugra™, captures the aqueous carbohydrate fraction at around 97 grams per litre of fermentable C5 and C6 sugars, opening routes to bio-hydrogen, biomethane, and bio-based chemicals.

Conventional attempts to upgrade whole fast pyrolysis bio-crude directly face a consistent set of obstacles: high water content dilutes the organic fraction, elevated metal concentrations accelerate catalyst poisoning, and chemically incompatible species cause phase instability under hydrotreating conditions. The result is high hydrogen consumption, rapid catalyst deactivation, and poor fuel yields. PyXCrude bypasses these problems by arriving at the hydrotreater already de-watered, de-metalled, and chemically concentrated. Less hydrogen is consumed, catalyst life is extended, and the yield of usable fuel product improves. The fractionation step does the hard work before upgrading begins.

By separating before upgrading, PySAF sidesteps the core technical problem that frustrated previous approaches: chemically incompatible fractions interfering with each other during conversion. Each stream then goes to the chemistry best suited to it.

The process reached Technology Readiness Level 5 in January 2026, with sample material now supplied to external partners under formal materials transfer agreements. The technology has attracted inbound interest from major energy companies and is being evaluated by academic and industry partners across the UK and Europe.

Unlike most energy transition companies, PySAF does not need to build primary production infrastructure. The fractionation technology slots directly into existing biomass supply chains, reducing both capital requirements and time to first revenue, with modular fractionation units designed for deployment alongside existing UK biomass infrastructure.

A seed funding round is now open to fund UK laboratory establishment and the first joint development agreements. A Series A in 2027 will fund the first modular fractionation unit at pilot scale.

The drums of dark liquid in that photograph are not waste. They never were. PySAF Ltd is now raising its seed round to prove it.

Please note, this article will also appear in the 26th edition of our quarterly publication.