The UK government's flagship policy to decarbonise the aviation sector is already showing signs of strain, with newly released data indicating the country is not on course to meet its initial targets. Official figures reveal that the supply of sustainable aviation fuel (SAF) into the UK market is falling short of the levels required by the legally binding mandate that came into effect at the start of the year.
The Data Reveals a Supply Gap
According to the government's own statistics, the volume of sustainable aviation fuel supplied for use in the UK during the first part of 2025 has failed to keep pace with the mandated requirements. The SAF mandate, which became law on 1 January 2025, requires that a minimum of 2% of all jet fuel used by UK airlines must be sustainable. This percentage is set to rise steadily to 10% by 2030 and 22% by 2040 as part of the nation's journey to net-zero carbon emissions by 2050.
The disclosed data highlights a concerning gap between policy ambition and practical reality. Industry analysts suggest that a combination of high global demand for limited SAF supplies, complex certification processes, and the premium cost of the fuel compared to conventional kerosene are creating significant headwinds. This shortfall poses a direct risk to the UK's legally binding carbon budgets and its international climate commitments.
Industry and Environmental Reaction
The aviation industry has expressed deep concern over the emerging data. Airlines, while publicly committed to the green transition, are facing immense pressure from the cost implications. Sustainable aviation fuel can be two to five times more expensive than traditional fossil-based jet fuel, a cost that is difficult to absorb without passing it on to passengers in the form of higher fares.
Environmental groups have seized upon the figures as evidence that the government's strategy is insufficient. Critics argue that an over-reliance on a single technological solution like SAF, without parallel policies to curb overall demand for flights or accelerate the development of zero-emission aircraft, is a flawed approach. They warn that missing these early targets sets a dangerous precedent, undermining confidence in the entire 2050 net-zero aviation roadmap.
Government Response and Future Challenges
In response to the data, a government spokesperson reaffirmed its commitment to the SAF mandate but acknowledged the "challenging global market." The Department for Transport pointed to its broader £165 million Advanced Fuels Fund as a mechanism to stimulate UK SAF production and build domestic supply chains. However, with no commercial-scale SAF production plants currently operational in the UK, the nation remains dependent on imports in the short term, leaving it vulnerable to international competition and supply constraints.
The situation is further complicated by the definition of what constitutes 'sustainable' fuel. The UK mandate currently allows fuels derived from certain waste oils and agricultural residues, but excludes controversial crop-based biofuels. Ensuring a robust and truly sustainable supply that does not create other environmental harms, such as deforestation or competition with food crops, remains a key challenge for policymakers and fuel producers alike.
The coming months will be critical. If the supply gap is not closed, the government may face difficult choices: weakening the mandate's targets, which would damage its climate credibility, or enforcing penalties on airlines, which could have knock-on effects for the travel industry and consumers. This early stumble for the SAF mandate underscores the immense complexity of decarbonising one of the hardest-to-abate sectors of the economy.
