Written question asked by Greg Smith (Conservative) on Tuesday, 7 July 2026, in the House of Commons. It was due for an answer on Tuesday, 14 July 2026 (named day). It was answered by Keir Mather (Labour) on Tuesday, 14 July 2026 on behalf of the Department for Transport.

Aviation: Alternative Fuels

Question: To ask the Secretary of State for Transport, whether the price of sustainable aviation fuel since the introduction of the UK Sustainable Aviation Fuel Mandate has met the assumptions used in the Department's published impact assessment.

Answer: The assumptions used in the Sustainable Aviation Fuel (SAF) Mandate cost-benefit analysis are projections of future SAF production costs over the appraisal period, rather than observed market prices. These estimates are subject to uncertainty regarding future technology deployment, feedstock availability and market developments. This is covered in detail in the SAF Mandate cost-benefit analysis. At present, hydroprocessed esters and fatty acids (HEFA) fuel is the only SAF pathway with a sufficiently mature and established market from which viable commercial price data are available. Other SAF pathways are not yet deployed at a scale that enables meaningful comparisons against the assumptions used in the cost-benefit analysis. Based on available market data, while SAF prices are inherently volatile and can fluctuate over time in either direction, we are confident that the range of estimates for HEFA SAF in the cost-benefit analysis remains accurate.

Secondary information