Sustainable aviation fuel (SAF) supply in the UK increased dramatically by 188% in 2023 making up for just 0.28% of total fuel supplied for aviation.

Do you know that this will jump to 10% by 2030? How? You have possibly heard that in April 2024, the UK government unveiled its highly anticipated SAF Mandate, signalling a bold commitment to decarbonise air travel.

Pending parliamentary approval, the UK will start applying soon from 1 January 2025 one of the world's first legally binding SAF mandates. The draft instrument to enable the SAF Mandate – the Renewable Transport Fuel Obligations (Sustainable Aviation Fuel) Order 2024 (SI 2024 Draft) – has already been laid before Parliament. If you are a producer, here are your answers on how the new SAF Mandate will affect your business. 

What is the UK's SAF Mandate?

The groundbreaking policy sets an obligation on aviation fuel suppliers to blend increasing proportions of SAF into the UK aviation fuel mix. The SAF Mandate is broken into two obligations:

SAF Mandate main obligation

The main obligation seeks to achieve at least 10% SAF in the UK aviation fuel mix by 2030 by setting targets for 15 years, from 2025 to 2040. This obligation builds on the UK government's previous commitment in line with the Jet Zero Strategy . In 2025, the overall SAF trajectory will be set at 2% of the total fossil jet fuel supplied, which is approximately equal to 230,000 tonnes of SAF. This will increase every year linearly reaching 10.5% in 2030. The target is further lifted to 15.8% for 2035 touching eventually 23.7% in 2040. Beyond 2040, the targets will remain the same, until they are reviewed, and legislation is updated as technology advances and costs drop.

Power to liquid obligation

Power to liquid obligation (PtL) i.e. the conversion of low-carbon electricity into liquid fuel known also as e-jet fuel, provides the greatest GHG emissions savings with reduced risks of negative environmental impacts or of dependency on certain feedstocks. To accelerate this advanced fuel deployment, the SAF Mandate introduces an obligation from 2028 that PtL covers 0.2% of total jet fuel demand. This will increase to 0.55% in 2030 and 4.48% in 2040.

What fuels are eligible under the SAF Mandate?

You probably already know that SAF is made through innovative processes from a wide range of sources such as biomass and waste byproducts, or synthetically from low-carbon energy. But the SAF Mandate supports only those fuels that avoid deforestation, reduction in biodiversity and competition with food production, and that meet strict sustainability criteria.

Sustainability, land and forest criteria

The main sustainability condition relates to a minimum amount of greenhouse gas (GHG) emissions reduced with SAF compared to fossil kerosene. For the first year of the Mandate, this threshold of GHG emissions savings is set at 40%. However, the threshold will possibly increase over the years as other sectors that support SAF production, such as the electricity grid, decarbonise. To calculate the lifecycle carbon intensity of SAF, the Mandate will adopt the same methodology as the Renewable Transport Fuel Obligation (RTFO) does for renewable fuels.

Schedules 1 to 3 of the Draft Order describe in detail the sustainability criteria, and more specifically the land and forest criteria that the feedstock used to produce sustainable aviation fuel must meet.

Eligible fuels

If the sustainability criteria are met, eligible SAF fuels include:

  • Sustainable, non-recyclable wastes or residues for example, used cooling oil, forestry residues, agricultural waste.
  • Recycled carbon fuels (RCFs) for example, unrecyclable plastics, industrial flue gas. From 1st July 2024 the Renewable Transport Fuel Obligations (Amendment) Order 2024 (SI 2024/634) classifies RCF as renewable in line with the Energy Act 2023, thus enabling SAF production.
  • PtL fuels made for example from hydrogen combined with non-biomass CO2 using low carbon (renewable or nuclear) electricity.
  • Aviation turbine fuel (avtur), aviation gasoline (avgas) and hydrogen.

The UK government notes in the Jet Zero strategy that a successful and resilient SAF industry will need a range of technologies and feedstocks to meet demand. The majority of SAF currently produced in the UK comes from the treatment of Hydroprocessed Esters and Fatty Acids (HEFA). But HEFA is a finite source. To strengthen SAF supply resilience, the Government decided to set a cap on HEFA. The cap will become more stringent over time. The HEFA cap, as a proportion of the overall trajectory, will be set at 100% in 2025 and 2026, decreasing to 71% in 2030, and 35% in 2040. The HEFA cap will apply on any fuel that uses a segregated oil or fat as a feedstock.

What about hydrogen?

The eligibility criteria of the Mandate apply to hydrogen only when it is used as a precursor i.e., when it contributes to the final energy content of the fuel. In this case hydrogen must be low carbon, for example hydrogen derived from renewable or nuclear energy, biohydrogen from wastes or residues, and RCFs.

When hydrogen is used as a key process input in SAF production pathways, for example in hydroprocessing, it does not contribute to the final energy content of the fuel. Therefore, it is not subject to eligibility criteria, but it is still accounted for on the lifecycle emissions of the final produced fuel. 

The current Mandate does not cover carbon capture, utilisation and storage (CCUS) enabled hydrogen (for example blue hydrogen), but this might change in the future.

What support will investment in SAF production receive?

The Mandate creates a secure and growing demand for SAF. Sure, this brings certainty to invest in domestic production capacity, but this certainty must go hand-in-hand with revenue support. As a SAF producer, you possibly are one of the successful bidders to the Advanced Aviation Fuel Fund and got a piece of the £135 million pie to produce advanced fuels. Or, you probably already have some support thought tradeable certificates under the existing RTFO scheme in return for supplying SAF.

From 1 January 2025, the SAF Mandate starts and SAF certificates will be supplied only under the new dedicated SAF RTFO scheme in line with the Draft Order. So, you will be able to get revenue support directly through those SAF tradeable certificates. Or you might be able to sell SAF at higher price to suppliers that do not meet their obligation and want to avoid paying a price for the amount of SAF they can't supply (buy-out mechanism). But this last option will be available for a limited time.

Revenue certainty mechanism

So, more funding is needed to kick-start the SAF production industry. That is why the Government has launched, together with the SAF Mandate, a consultation to establish a revenue certainty mechanism by the end of 2026 as provided the Energy Act 2023. The aim of the revenue certainty mechanism is to reduce financing risks for emerging SAF plants, thereby attracting investment into UK SAF projects and increasing domestic SAF production. The consultation that closes on 20 June 2024 considers four revenue certainty options. The Government's favourite option is the guaranteed strike price. This option could operate separately but in tandem with the SAF Mandate. If you are familiar with the Contracts for Difference mechanism, the GSP functions in a similar way. The producer and the government enter into a contract that guarantees a fixed price per litre of SAF (strike price). The flow of any payment will be determined based on the difference between the strike price and reference price.

Interim measures

What happens between now and the end of 2026? As the Government states in the consultation, the Jet Zero Council and its working groups explore interim measures to support SAF production. However, we do not know any details on these measures.

Multiple incentives

SAF and chemical precursors used in the production of SAF are traded globally and might receive support in their country of origin. These multiple incentives may have a detrimental impact on domestic SAF producers. To address this distortion and ensure a level playing field for the UK SAF production, the Government introduces in the Draft Order an obligation for the SAF supplier to declare that the fuel supplied has not received support both domestically and internationally under a different scheme or mechanism other than the SAF Mandate. This support does not include investment aid, tax exemption or reduction, and tax refund.

The Government provides further clarifications on the interaction of the SAF Mandate with the existing support schemes for hydrogen and CCUS:

  • Hydrogen: In principle SAF produced with hydrogen in the form of fuel or chemical precursor can receive subsidies both under the existing RTFO legislation and the Hydrogen Business Production Model (HBPM) provided that the same volumes are not claimed under both schemes. However, the Government still works on how the new SAF RTFO legislation will be treated under the HBPM.

Treatment is different when hydrogen is used as a process input in SAF production. In that case, a producer can claim support both under the HBPM and the SAF Mandate. In case you want to know more on HBPM, read this article.

  • Carbon Capture Utilisation and Storage (CCUS): CCUS can be used across low carbon fuel production pathways to reduce the carbon intensity of the resulting fuel. CCUS technology currently receives support under the industrial carbon capture business model (ICC) with the waste ICCC being the most relevant to SAF production. The SAF Mandate will reward greenhouse gas savings from CCUS, giving an added incentive for producers to install the technology. Therefore, support under waste ICC may no longer be needed or it may be adjusted as outlined in the most recent guidance of the ICC business model. The adjustment options under consideration include an item on SAF Mandate during the negotiation process of the ICC business model, or a provision in the contract to make a payment adjustment and account for support under the SAF Mandate. You can read more about UK CCUS in our article.

What further changes does the SAF Mandate bring?

The SAF Mandate introduces significant changes to promote sustainable aviation. As a producer, it is imperative that you align your SAF with the stringent certification standards mandated by the UK government. These standards are gateways to market qualification, ensuring your SAF's eligibility for sale.

SAF producers will be interested to hear that the UK's SAF Clearing House officially launched in April 2024. This is the central hub that will coordinate the testing and certification of new SAFs. The UK SAF Clearing House is already inviting fuel producers to apply for funding and technical assistance for the advancement of sustainable aviation fuels.

Like the existing RTFO, the Draft SAF RTFO Order details how the Department for Transport (DfT) will oversee the implementation and management of the SAF Mandate with a dedicated administrative unit within it. As the regulator of the SAF Mandate, DfT will ensure compliance with the SAF Mandate obligations, manage accounts, and make sure that SAF claimed under the scheme meets the sustainability criteria.

Our insight on the SAF Mandate

The SAF Mandate is closely interconnected with the existing Renewable Transport Fuel Obligation (RTFO). They both aim to reduce greenhouse gas emissions in the transport sector and provide incentives for renewable fuels. The SAF Mandate builds upon the success of the RTFO, through its focus on aviation. However, you must keep in mind that from 1st January 2025, SAF is removed from the existing RTFO legislation, and stands with its own dedicated legislation in the Draft Order.

The SAF Mandate provides producers with greater certainty. By setting a firm target – 10% of jet fuel from sustainable sources by 2030 – the UK has demonstrated its dedication to sustainable aviation. This certainty creates a stable market environment, encouraging investment in SAF production plants. says it wants to see at least 5 commercial scale SAF plants under construction in the UK by 2025. This is an ambitious target, and we will need to see whether it is achievable on those timeframes. However, as the aviation industry has outlined, the SAF Mandate is not enough; it is the revenue certainty mechanism that will increase production.

What do you need to do next?

The UK government has already laid before Parliament the secondary legislation to underpin the SAF Mandate, while changes to primary legislation are still pending. Both the primary and secondary legislation are intended to be adopted during 2024 with the Draft Order adopted possibly this summer after the elections.

The SAF Mandate is not just a legal requirement, but an opportunity for producers to lead the way toward a sustainable future. Producers must ensure that their SAF production adheres to the certification standards outlined in the Mandate.

Producers will also need to focus on innovation to improve their SAF production processes. This may involve the exploration of new feedstocks (such as waste materials or by-products) or through optimising production efficiency. Producers will need to establish robust supply chains for feedstock sourcing, production, and distribution. Collaboration with airlines, airports and fuel distributors will be crucial to ensure a seamless supply chain.

Where can you read more about the SAF Mandate?

If you want to read the full text of the SAF Mandate then you can access it here.

Do you want to know more about how the SAF Mandate might impact your business?

Simply reach out to Sarah Daun, Kevin Bell or Peter Snaith.


This article was also authored by Megan Grieves, Trainee Solicitor at Womble Bond Dickinson.

This article is for general information only and reflects the position at the date of publication. It does not constitute legal advice.