Crop-Derived SAF: AD Has a Role — If Policy Gets the Basics Right

ADBA has submitted its response to the government’s call for evidence on crop-derived sustainable aviation fuel (SAF). Our central message is straightforward: the UK has real, scalable domestic feedstock potential for crop-based SAF — including via biogas-to-SAF pathways — but unlocking it requires a policy framework that judges agricultural systems fairly, rather than singling out individual crops for scrutiny.

The Feedstock Opportunity Is Real

The UK’s biomethane sector has significant headroom to supply crop feedstock for SAF without displacing food production. Research cited in our response suggests around 43TWh of crop-derived biomethane potential from rotational and sequential cropping systems — maize, whole-crop rye and cover crops grown as part of responsible farming rotations. This sits within a total domestic biomethane potential of around 120TWh, of which NESO estimates at least 64TWh is needed to meet net zero. There is, in short, enough for both grid gas and SAF if demand and policy align. The carbon intensity figures are compelling too: UK maize and rye for biomethane achieve around 15gCO₂e/MJ under the RTFO, implying a SAF carbon intensity of approximately 25gCO₂e/MJ via Fischer-Tropsch — well within the SAF mandate thresholds.

Judge the System, Not the Crop

Indirect Land Use  (ILUC) risk and land-use sustainability cannot be meaningfully assessed crop by crop — they must be assessed at the level of the agricultural system. A crop grown in a responsible 1-in-5 rotation integrated with food production poses fundamentally different risks to a monoculture. The RTFO and SAF Mandate’s existing carbon intensity framework — if rigorously maintained and tightened where necessary — is the right tool for making these distinctions. High-risk cropping practices will show up as high CI scores; low-risk, rotation-integrated systems will not. Overlaying that with five-year agronomic records to verify land history provides robust ILUC assurance without requiring a separate, crop-specific regime.

We also flag a wider point on degraded and marginal land: policy should incentivise land restoration, not production on degraded land — which risks incentivising degradation itself. Crops grown on land being restored through AD digestate application and improved soil management should attract a carbon intensity benefit, reflecting the genuine soil carbon gains being delivered, rather than an implied credit for avoidance.

Getting crop-derived SAF right is an opportunity to modernise UK agriculture, retain domestic fuel production capacity, and put circular nutrient flows — via AD digestate — at the heart of a more sustainable farming system. ADBA looks forward to working with government to make that case.