Open Call for Evidence -- SAF Mandate: Crop-Derived Sustainable Aviation Fuel Public Comment DEADLINE March 16, 2026

December 23, 2025

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(U.K. Department for Transport) In 2023, transport accounted for 35% of economy-wide greenhouse gas (GHG) emissions when including international aviation and maritime. The government is committed to delivering greener transport, which will support the missions to kickstart economic growth and make Britain a clean energy superpower.

We expect low carbon fuels to play a key role in transport decarbonisation. The use of these fuels can complement electrification by helping to decarbonise combustion engines (internal combustion engine and jet) where alternatives are limited, and whilst the transition to zero emission technologies is underway.

Aviation is currently the second largest contributor of carbon emissions from transport and is set to overtake road vehicles as transport’s largest emitter by 2040.

Sustainable aviation fuel (SAF) is one of the key measures required to reach net zero emissions from aviation by 2050. SAF can be made from a variety of feedstocks and can be blended with conventional jet kerosene for use in existing engines and infrastructure.

We are encouraging the production, development and use of SAF in the UK in 3 main ways.

We are building demand through the SAF Mandate by setting targets for the supply of an increasing amount of SAF in the overall UK aviation fuel mix. The SAF Mandate is now in place.
The Advanced Fuels Fund aims to grow the UK supply of SAF by supporting first-of-a-kind SAF production plants through the project pipeline to reach investment ready stage and achieve commercial scale. £63 million has been allocated across 17 UK projects for this financial year. The Spending Review 2025 will continue support for the production of SAF in the UK from 2029 to 2030.
We are helping to derisk SAF projects by legislating to introduce a revenue certainty mechanism. A revenue certainty mechanism will help de-risk SAF projects in the UK by addressing barriers to investment in a nascent market that is using innovative technologies. Such a mechanism will help provide greater certainty of future revenue and attract investment in commercial scale SAF plants within the UK.

Since the start of this year, the SAF Mandate has been supporting the uptake of SAF by setting a legal obligation on UK jet fuel suppliers to supply SAF. The government has always been clear that it will support SAF with the highest sustainability credentials and that delivers genuine GHG savings.

The SAF Mandate provides certainty to industry by setting a legal framework that establishes the demand for SAF in the UK. This certainty facilitates an environment in which commercial decisions can be made confidently, supply chains are developed, and investment is attracted into the sector. Government is committed to maintaining that certainty and confidence and will not propose changes unless a) there is a strong rationale and b) such changes can be made that are consistent with wider government objectives, in a way that maintains policy stability and investor confidence.

The production of SAF is a rapidly developing technology. As the SAF market develops, government will need to ensure that the SAF Mandate:

continues to deliver genuine GHG savings while minimising cost impacts on aviation consumers
aligns with the UK’s overall progress towards future carbon budgets
interacts effectively with other low carbon fuel support mechanisms, including other SAF support schemes and the Renewable Transport Fuel Obligation (RTFO)
facilitates the development of a UK domestic production sector
keeps up with technological developments while providing the certainty needed to create an attractive investment environment

This is why we are gathering evidence on the use of crops in SAF production. This document focuses on feedstock availability and cost of crop-derived SAF production, the impacts of crop-derived SAF production on UK industry, and sustainability risks and how regulation may be able to mitigate against these.

Background

The SAF Mandate, which came into force on 1 January 2025, is the UK’s key policy mechanism to secure demand for SAF. It delivers GHG emission savings by encouraging the supply of SAF within the UK aviation industry. It does this by setting a legal obligation on fuel suppliers in the UK to supply an increasing proportion of SAF over time.

The SAF Mandate has 2 obligations – the ‘main obligation’ and the ‘power-to liquid obligation’. In 2025, the main obligation is set at 2% of the total fossil jet fuel supplied. This will increase annually to reach 9.5% in 2030 and 18.5% in 2040. The power-to liquid obligation will be introduced from 2028 at 0.2% of total jet fuel demand and will reach 3.5% of total jet fuel demand in 2040.

At the end of an obligation period, suppliers must redeem certificates against their obligations. Suppliers can gain certificates by:

supplying SAF which meets the sustainability criteria and claiming certificates in proportion to the GHG savings that SAF achieves, or
purchasing certificates from other suppliers or account holders

Where suppliers do not redeem sufficient certificates against their obligations, they will be required to pay the buy-out. This provides a method of compliance where suppliers are unable to secure a supply of SAF. The buy-out prices are set at a level to encourage the supply of SAF over the use of the buy-out and effectively set a maximum cost for the scheme, thereby delivering GHG emissions reductions at an acceptable cost.

To ensure that space is left for the more advanced fuels to develop, the SAF Mandate also includes a cap on the amount of hydroprocessed esters and fatty acids (HEFA) that can be used to meet the main obligation. HEFA can contribute a maximum amount (100%) of SAF demand in 2025 and 2026, decreasing to 71% in 2030 and 35% in 2040.

To ensure the design of the SAF Mandate reflects the latest technological and commercial developments, there will be continuous monitoring of trends and impacts of the SAF Mandate, including on consumers. Formal reviews will be conducted and published at least every 5 years, with the first formal review by 2030.

Feedstock eligibility and sustainability criteria

The government has been clear that the mandate must deliver fuels with the highest sustainability credentials. We have therefore put in place strict sustainability criteria that SAF must meet in order to be eligible under the mandate.

SAF must be made from sustainable biogenic wastes or residues (such as used cooking oil or food waste), recycled carbon fuels (such as unrecyclable plastics), or be power to liquid fuels made using low carbon (renewable or nuclear) energy. SAF produced from crops (including food, feed, energy or cover crops) is not permitted.

All SAF must meet a minimum GHG savings threshold of 40% against a fossil fuel comparator of 89 gCO2e/MJ. Depending on the type of feedstock used, further sustainability criteria apply including:

land criteria which prevent feedstocks used for biofuels produced on lands categorised as having high biodiversity value, or lands which have high carbon stocks – these apply to agricultural wastes and residues
forest criteria which ensure biomass must not come from protected land types unless the harvest of biomass does not interfere with nature protection – these apply to forestry wastes and residues
soil carbon criteria which require monitoring or management practices are in place to ensure impacts on soil quality and soil carbon from harvesting are limited – these apply to agricultural wastes and residues
sustainable waste management criteria, which require adequate monitoring or management plans, must be in place to address local environmental impacts caused by sourcing or processing – these apply to wastes of fossil origin

The purpose of this call for evidence

The SAF market is currently in its early stages of development. As a result, there is considerable uncertainty about its long-term development, and the evidence and data reaching out to 2050 and beyond. When developing the SAF Mandate, government acknowledged the uncertainty of this nascent industry. Therefore, it was confirmed that there would be continuous monitoring of trends to ensure the policy keeps pace with technical and commercial developments.

The decision to only permit wastes and residues was confirmed in the government response to the first consultation published in 2023. This decision was taken to encourage fuels that deliver the greatest GHG savings and have lower risk of negative environmental impacts. Many respondents agreed with the exclusion of crops, although a few stakeholders noted that including crops could reduce the cost of SAF and allow UK bioethanol plants to sell their product for SAF production. Since then, the UK has already seen a strong uptake of SAF ahead of the SAF Mandate’s introduction, accounting for approximately 2% of all jet fuel supplied to the UK in 2024 under the Renewable Transport Fuel Obligation (RTFO)^{[footnote 1]}.

All the SAF supplied under the RTFO in 2024 was HEFA and there is a need to diversify technologies so that higher targets can be met in the future. Advanced technologies have perceived challenges to reach production due to uncertainty in revenue and technical and construction risks, though progress is being made with the first commercial scale alcohol-to-jet plant starting production earlier this year in the US. We can expect growing global demand for SAF as other jurisdictions such as the EU, Brazil, South Korea, and Singapore look to implement their own SAF mandates or similar incentives.

In addition to this, ICAO’s Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) places a requirement on airlines to reduce their carbon emissions, which can include the use of SAF. The regulation of SAF and feedstock eligibility varies across these support schemes. For example, the EU has primarily focused on wastes and residues but recently permitted intermediate crops and non-food/feed crops grown on degraded land. Meanwhile, CORSIA does not have specific feedstock eligibility criteria and instead regulates the fuel through a set of sustainability criteria, including aspects such as water, soil, food security and indirect land use change (ILUC) factors.

While there are positive early signs regarding the scale-up and availability of SAF in the UK, as targets increase, we must ensure there is sufficient SAF availability to meet demand in the long term. As such, it is essential to have the most up to date information across a range of feedstocks. Government last formally gathered views from stakeholders in 2023 and we are conducting this call for evidence to give stakeholders who have new or improved evidence on crop feedstocks to formally submit it. The call for evidence, therefore, focuses on the potential benefits, risks and trade-offs of using crops in SAF production.

This call for evidence does not propose any changes to the SAF Mandate. In light of the responses to this call for evidence, should there be a case to review the feedstock eligibility criteria, it would be subject to consultation and any changes would require amendments to legislation.

Scope of call for evidence

This document seeks evidence, as well as broader feedback, on the use of crops in SAF production. This will improve our understanding of the impacts and interactions on areas such as feedstock availability, industrial development, sustainability and regulation.

Through the call for evidence, government is seeking feedback on the following types of crops.

Energy crops

These consist of non-food cellulosic material or lignocellulosic material that are grown for the purpose of being used as fuel or energy, are not considered a residue or waste, and would not normally be used for food in feed.

Cover crops

The specific definition is dependent on individual regulatory schemes, but generally refers to non-food or feed crops grown to protect and improve soil health, particularly during periods when the main crop is not actively growing. Typically, they are ploughed in before sowing another crop, and are not harvested. However, for the purposes of low carbon fuel production they would need to be harvested, which could remove benefits to soil health. Note that we are seeking feedback on an appropriate definition when referring to cover crops, which is set out later in this document.

Food and feed crops

These feedstocks can be used for food and feed as well as low carbon fuel production. These could include starch-rich crops, sugars, oil crops and main crops.

We request that, when responding to each question, you consider a separate response for each of these crop feedstock categories so that we can fully understand details specific to each type of crop.

Please note that the above categorisation may not be exhaustive and we also welcome any comments on crops which respondents do not consider to be covered by the categories above. Agricultural wastes and residues from crop production are already eligible under the SAF Mandate so are not considered further under this call for evidence. Stakeholders should also consider specific land types, for example, crops grown on marginal or degraded land.

Meeting the SAF Mandate targets

For 2025, the overall SAF trajectory is set at 2% of total jet fuel, rising to 10% in 2030 and 22% in 2040. The analysis undertaken in 2024 to develop the mandate and inform target setting considered fuel availability modelling. This analysis included the potential waste and residue feedstock and production constraints for all production pathways and was based on the best available data at the time.

Currently, the majority of SAF supplied is HEFA from used cooking oil (UCO) or similar waste oil feedstocks such as tallow and brown grease. The finite nature of these feedstocks means that continuing a reliance on one specific feedstock and pathway could lead to sustainability impacts and supply chain disruptions or bottlenecks. The risk of this is likely to increase as more countries introduce SAF targets, which have been spurred on by ICAO’s adoption of a global 2030 target for 5% emissions reduction from use of SAF. We, therefore, expect growing global demand for constrained supplies of waste oils for use not only in HEFA SAF production but also in other uses, such as renewable diesel for use in surface transport. This is supported by analytical projections, which highlight the risk of insufficient supply of this feedstock leading to higher prices and requiring a shift towards alternative technologies and feedstocks^{[footnote 2]}^{[footnote 3]}.

This is why the UK has taken action to diversify the SAF portfolio by introducing the HEFA cap and PtL obligation in the SAF Mandate and supporting a range of technologies through the Advanced Fuels Fund. However, advanced technologies must overcome several challenges, including technical and construction risks, securing investment and agreeing offtake agreements. Should these technologies not come online at the same rate as the SAF Mandate is increased, this would lead to buy out and higher costs for consumers for no carbon benefit.

In response to these challenges, some stakeholders have proposed that SAF Mandate feedstock eligibility should be broadened to allow SAF developers to draw on a wider feedstock pool, providing greater flexibility for producing SAF. It is suggested that this could reduce the dependence on UCO and therefore mitigate the risks highlighted above. In addition to this, subject to the type of crop used, it could provide an alternative to advanced technologies if these plants do not develop at the rate originally expected.

Crop supply chains and technologies have been established for the purpose of low carbon fuel production and there is existing infrastructure, such as bioethanol facilities, that could be used as a precursor to producing jet fuel. It has been suggested that inclusion of some crop-derived SAF could reduce overall costs in meeting the mandate, which may reduce the costs passed through to aviation consumers. However, this would be subject to the GHG savings that crop-derived SAF achieves and, therefore, the number of certificates that crop-derived SAF is rewarded.

However, there are potential significant demand implications when using crop feedstocks, which need further consideration.

Land availability: Increasing the demand on crops could lead to direct or indirect land use change, causing land such as forests or wetlands to be converted and increasing GHG emissions.

Competition with existing and emerging uses: SAF would have to compete for these resources with other energy and non-energy uses. Beyond the food sector, crops are also used widely in other sectors such as electricity generation. As countries across the globe introduce decarbonisation policies, the competition for sustainable biomass feedstocks across sectors will increase and global supply may not be able to keep up with this demand. There is a risk that crops are diverted away from existing uses if SAF producers have greater purchasing power. This could potentially impact the price of crops, risk commercial operation of other uses and may not deliver additional GHG savings across the economy.

Sustainability: There could be food and feed supply chain impacts by competing for land, labour and other resources, while impacting food prices. Crop cultivation could also be associated with impacts on biodiversity, water and soil. Accommodating the additional demand, while minimising impacts on the environment could be challenging. The extent of these impacts is discussed further in sustainability and regulation section.

Through this call for evidence, we are seeking the latest data sources and reports on feedstock availability across the different crop types, as well as any information on the cost of SAF production associated with these feedstocks. The amount of competition could vary significantly depending on the type of crop in question. We would welcome views on where there are competing demands for specific types of feedstocks and, therefore, whether permitting these feedstocks in the SAF Mandate could divert materials away from existing uses and other emerging uses. We ask respondents to consider several factors when assessing the availability of feedstocks for SAF. These include domestic policies relating to biomass production and availability, domestic and global land availability and land use impacts (for example, impact on food security), biomass crop yields, competition from both energy and non-energy uses, and likelihood to increase feedstock supply if other sector uses come online.

Question 1: How much feedstock is likely to be available for each of the crop types and at what cost could SAF be produced from these crops and using which technologies? Please provide evidence and consider how this may vary between current day and 2040, considering policies relating to biomass production and availability, land availability and land-use impacts. Please also consider how much feedstock is available in the UK specifically, in addition to a global scale.

Question 2: What competing uses and emerging/future uses exist for crop feedstocks? Please comment on specific crops where possible.

Support the UK low carbon fuel industry

The government has been clear that it wants to support a UK SAF production industry. We are already encouraging the production of SAF in the UK by:

Legislating to introduce a revenue certainty mechanism. On 14 May 2025, the government response to the second consultation on approach to industry funding for SAF revenue certainty mechanism was published and the SAF Bill was introduced at the House of Commons. The Bill passed the House of Commons on 15 October.

Supporting first-of-a-kind SAF production plants through the project pipeline to reach investment ready stage and achieve commercial scale through the Advanced Fuels Fund. £63 million has been allocated across 17 UK projects for this financial year. The Spending Review 2025 will continue support for the production of SAF in the UK from 2029 to 2030.

The government approach has so far focused on developing advanced technologies using wastes and residues. Often, SAF producers will be required to identify multiple sources for waste or residue feedstocks, rely on complex collection systems, or compete for wastes that are already in long-term contracts for other uses. This can present a challenge for developers in securing reliable supply. Investors have identified a risk that, in the absence of long-term feedstock contracts, SAF producers will not be able to attract sufficient feedstocks to maintain forecasted levels of production and therefore attract the required returns on investment.

It has been suggested that, in some cases, broadening the feedstock criteria to permit crops could facilitate the signing of long-term feedstock contracts and ensure projects receive the investment they require to be built. It could also provide greater flexibility for producers to use multiple feedstocks or switch feedstocks over time, thus creating greater security over supply of feedstock. Overcoming these barriers could expedite the development of SAF projects in the UK, as well as establishing supply markets. This could provide a pathway for the early deployment of SAF production facilities with the potential to transition to wastes and residue feedstocks in the future once they have demonstrated successful operation.

Industry has also highlighted the potential benefits of SAF production facilities utilising locally sourced crop feedstocks, which could provide new secure off-takers for farmers and crop-based bioethanol producers in the UK. It is argued that permitting crops could therefore provide opportunities for supporting jobs throughout the supply chain in the UK. However, given that the SAF Mandate permits SAF from anywhere in the world, any UK production would compete internationally. Other countries where crops are grown for the purposes of low carbon fuel on a significant scale may outcompete the UK in both carbon intensity and cost of production, therefore, potentially increasing import dependence under the SAF Mandate.

There is also a risk that permitting crops in the SAF Mandate could cause uncertainty in the SAF sector and deter investment into advanced technologies. While oil crops would fall within the definition of the HEFA cap, other crops could be used to produce non-HEFA SAF. If allowed in the mandate, this would put crop-based technologies in direct competition with the nascent advanced non-HEFA technologies and could risk undermining the business case for the latter and the current government approach to diversify the feedstock mix. Government remains committed to supporting our low carbon fuels industry in the UK and the SAF Mandate must align with wider goals and support, not hinder, the crucial diversification of SAF feedstocks, for which the mandate has been carefully designed.

Question 3: What are the potential impacts of crops on a UK SAF production industry? Please consider any potential benefits or risks to advanced technology development.

Question 4: If there are risks to advanced technology development, are there any policy options to mitigate these? Please consider short- and long-term measures.

Question 5: What are the impacts of crop use in SAF production on the wider UK supply chain? Please consider UK competitiveness compared to other regions, including potential agronomic practices that could be adopted to ensure the UK is competitive.

Question 6: Please provide data on the carbon intensity of crop-derived SAF production, taking into account different types of crops and production pathways. 

Sustainability and regulation

A number of sustainability risks associated with crop use have been well documented, including environmental, economic and social impacts. Any decision to make crops eligible under the mandate would require confidence that these impacts can be managed and mitigated through effective sustainability standards. These would need to be underpinned by robust assurance processes to ensure genuine GHG savings are delivered and any wider impacts are minimised. Through this call for evidence, it will be important to understand the latest evidence concerning these impacts, how these vary between crops and how regulation could be designed to effectively mitigate against these risks both domestically and internationally.

The SAF Mandate already has sustainability criteria in place to mitigate against some of these risks as they apply to biogenic wastes and residues (further information on sustainability criteria can be read in guidance):

land criteria: prevents biofuels produced on lands categorised as having high biodiversity value, or lands which have high carbon stocks
soil carbon criteria: ensures that for agricultural feedstocks, monitoring or management practices are in place to ensure impacts on soil quality and soil carbon from harvesting are limited
forest criteria: must not come from protected land types and must be harvested in such a way as to minimise negative impacts on soil quality and forest biodiversity
minimum GHG savings threshold: SAF must achieve at least a 40% GHG saving compared to a fossil fuel comparator of 89 gCO2e/MJ

Typically, fuel suppliers will use sustainability accreditation schemes, such as International Sustainability and Carbon Certification (ISCC), to conduct assurance processes and ensure sufficient evidence can be demonstrated against these criteria.

In December 2025, government published a consultation on the common biomass sustainability framework. This proposed that a common framework is applied across government schemes, including the SAF Mandate, to strengthen confidence in biomass use and apply robust, clear and consistent rules on sustainable biomass across our net zero programmes. This includes minimum sustainability requirements for the use of crops for bioenergy, including for SAF. Therefore, any future decisions on the treatment of crops in the SAF Mandate will need to be considered in light of this consultation.

However, the consultation highlights the need for flexibility in certain areas, including allowing individual policies apply further sustainability criteria based on sector-specific risks identified. Government has identified a range of potential sustainability risks associated with crop-derived SAF, discussed in turn below.

Through this call for evidence, we are seeking information to better understand these issues, as well as any other risks that have not been identified, and whether there are viable mitigations or protections, including through regulation. We are particularly interested in evidence which shows how these risks may vary depending on the type of crop, location, agricultural practices and any other relevant factors. We are also interested in evidence of any new technology or processes that could help to mitigate these risks.

Greater direct greenhouse gas (GHG) emissions

Crop based biofuels typically have greater GHG emissions compared to waste-based fuels. This is generally because of the GHG emissions associated with the cultivation of crops, whereas for wastes, the GHG calculation starts at the point the collection of the waste. Upgrading feedstocks and intermediates to SAF can also significantly increase GHG emissions. However, there is variation amongst crops with some feedstocks and conversion processes potentially achieving significant GHG savings (PDF).

Standard approaches in assessing direct GHG emissions allow regulators to protect against negative impacts through GHG based measures. Under the SAF Mandate, to ensure supply of SAF with the highest sustainability credentials, SAF must meet a minimum GHG savings threshold of 40% and greater GHG savings are incentivised through certificates rewarded in proportion to GHG savings. We are seeking stakeholder views on whether, were crops permitted in the SAF Mandate, there would need to be any changes to the minimum GHG savings threshold or certificate reward system.

Emissions from indirect land use change

The use of crop-based biofuels can drive significant GHG emissions through indirect land use change ILUC. This occurs when additional demand for agricultural land due to the use of crops for biofuels leads to land conversion (for example, deforestation) elsewhere. The risk of crop-based biofuels leading to indirect land use change are typically considered highest for oil crops (palm oil, soy, rapeseed) and are lower for grains. This is due to different factors, including availability of replacement products and where exactly crops might be grown (for example, for oil crops the risk is often higher as many of these crops are grown in regions close to rainforests with very high carbon stock).

While there is a significant and long-standing body of evidence on ILUC^{[footnote 4]}^{[footnote 5]}^{[footnote 6]}^{[footnote 7]}^{[footnote 8]}, there is generally a lack of scientific consensus on its magnitude, and a lack of policy consensus on how it can be best accounted for and managed in low carbon fuel policies^{[footnote 9]}^{[footnote 10]}. As a result, a variety of approaches are taken internationally. As a result, a variety of approaches are taken internationally. These can be broadly divided into 2 streams:

Risk based: This is the approach taken by the EU to phase out fuels that are classified as high-ILUC risk based on a set of criteria. The UK and EU also both cap the contribution of crop-based feedstocks and exclude the use of food and feed crops in aviation. ILUC factors are added for reporting but not compliance purposes^{[footnote 11]}^{[footnote 12]}.

Use of ILUC factors: This is the approach taken under ICAO’s CORSIA scheme and the Californian Low Carbon Fuel Standard. These factors seek to quantify the indirect GHG impact of the use of crop-based feedstocks using economic models like GTAP-Bio and GLOBIOM and adding them to the reported carbon intensity of the fuel alongside direct emissions such as those from cultivation, transport and processing. The magnitude of these factors across different models can be highly variable.

Given this diversity of approaches globally, with their own opportunities and challenges, we request that stakeholders provide further evidence on the ILUC impacts of different crop-based fuels and how this could be most robustly and accurately be accounted for and mitigated. This could include examples of what has worked well in other low carbon fuel policies and how this could be robustly applied within the SAF Mandate.

Food security

As the use of crops for biofuel production can compete with food and feed uses of land and feedstock, it also has the potential to increase food prices and have a negative impact on global food security^{[footnote 13]}^{[footnote 14]}^{[footnote 15]}. A particular concern is that use of crop-based biofuels can exacerbate food shocks, for example, grain shortages which are seen as a result of Russia’s illegal war in Ukraine^{[footnote 16]}^{[footnote 17]}. Even where certain crops cannot be used for food or feed, it may be difficult to decouple the impacts of using such feedstocks from the food/feed supply chains.

However, the global food system is highly complex, and some stakeholders have argued that crop-based SAF, when deployed within an integrated and optimised system, can go hand in hand with or even enhance food and feed production. A common example given is how biofuel production from crops (for example, corn, wheat, soy) can also result in significant amounts of high-protein animal feed. Others point to cover crops and how these could improve overall soil quality and provide a feedstock for SAF production, in addition to the main crop. We would like more evidence on how these interactions play out on both a local and global scale and whether regulation could be designed to maximise these synergies and mitigate any risk to food security.

Domestically, a key principle of the government’s land use framework proposed earlier this year (PDF) is to support sustainable and resilient food production. It is critical that the SAF Mandate policy supports appropriate land use, which must consider the important role of domestic food production in our food security. This will also help to reduce the risk of displacing food production and any associated environmental impacts abroad.

Wider environmental impacts

The intensive cultivation of crops for biofuel production is associated with a variety of environmental impacts, including direct and indirect loss of biodiversity, potential contributions to local air pollution (for example, for example pre-harvest field burning in sugarcane production) significant water consumption particularly when irrigation is required, and causing increases in environmental problems such as acidification and eutrophication compared to fossil fuels. However, the extent to which crops have an impact on these parameters is highly dependent on a number of factors. For example, the impact on biodiversity is impacted by growth cycle, fertiliser and pesticide use and degree of human intervention.

Typically, these parameters are not considered in lifecycle assessment due to difficulties in measuring impacts and lack of standardised approaches leading to uncertainty in carbon intensity values. This means that these impacts are not protected against by GHG based measures, for example, a minimum GHG savings threshold. Alternatively, appropriate agricultural management processes could be put in place to mitigate against these wider environmental risks, as sustainability criteria like the soil carbon criteria seek to do for agricultural wastes and residues. This could include, for example, requirements to limit water use or adequate monitoring to ensure illegal land clearance is avoided. We are seeking feedback on how these impacts can best be regulated, including through either the use of carbon intensity values and agricultural management practices.

Cover crops and crops on degraded or marginal land

Cover crops are often cited as a type of crop that mitigates against some of these environmental risks by reducing erosion and nutrient leaching, improving soil fertility and increasing biodiversity. In 2024, the EU permitted intermediate crops to be an eligible feedstock for its SAF Mandate to increase the availability of sustainable feedstocks that can be used to meet renewable energy targets, subject to strict criteria being met^{[footnote 18]}. Further guidance is due to be published, which will set out how these crops will not trigger demand for additional land and how soil organic matter can be maintained.

Geography may limit where such crops can be grown if the intention is not to impact the harvest and planting of the main crop. Furthermore, increased demand for cover crops could lead to land-use change. For example, if a farmer who is harvesting 2 crops in a given year decides to replace one of those crops with a cover crop for biofuel production, it would cause land-use change, including potentially through reduced yields of the primary crop. A key challenge is therefore setting a definition of cover crops that can apply globally and avoid impacts on ILUC and the food/feed supply chain.

For example, setting a definition which can apply in Europe, where main crops may be harvested only once per year and in South America, where main crops can sometimes be harvested more than once per year. Another issue with setting a definition may arise where it conflicts with other schemes that require cover crops to be ploughed back into the soil to improve soil health. For example, the Sustainable Farming Incentive defines cover crops in this manner. Allowing cover crops to be used in SAF production might mean farmers switch to cover crops that are, for example, less effective at reducing soil erosion or require more pesticides, or do not bring additional benefits due to being harvested. Government would like information on how cover crops could be robustly defined, including in terms of specific agricultural practices, that can apply globally and mitigate the risks highlighted above, including any impact on primary crop yields.

The EU also now permits the use of non-food and feed crops grown on severely degraded land for use in SAF production. Crops grown on degraded land may offer an opportunity to use additional land, however, there is uncertainty over how much degraded land is available and how usable degraded land is. A specific definition would be required that sets out the conditions for such land to be considered degraded, for example content of organic matter or the amount of erosion, and would have to be applied globally. It will also be necessary to measure such conditions and have the assurance processes in place for verification, including through voluntary certification schemes. There can be an inherent tension between (1) defining land as too degraded for its use for biofuel feedstock production to affect agricultural supply and demand and (2) suggesting that degraded land can be suitable for viable production of biofuel feedstocks.

Any definition that the UK introduced should also be compatible with definitions under other UK schemes, for example, the Green Gas Support Scheme.

Question 7: What are the sustainability risks that exist for each of the crop types? Please consider how these risks vary between different crop types and regions.

Question 8: To what extent does ILUC exist for different crops? How can ILUC most robustly and accurately be accounted for?

Question 9: To what extent can policy frameworks for crop-based biofuels be designed to minimise the impact of crop-based feedstock use on international market volatility? Are there any regulatory measures that could help mitigate any impact on potential price spikes?

Question 10: What agronomic practices and management measures could be applied to mitigate against any sustainability risks identified?

Question 11: Are the current sustainability criteria sufficient to mitigate against risks identified? If not, what sustainability criteria would be required?

Question 12: What assurance measures are required to evidence these crops protect against risks identified?

Question 13: How could cover crops and crops on degraded or marginal land be defined? Please provide evidence of the availability, as well as the risks and benefits of growing crops on this degraded or marginal land.

How to respond

See the Ways to respond section of the call for evidence page on GOV.UK to find out how you can respond to this call for evidence.

The call for evidence period began on 22 December 2025 and will run until 11:59pm on 16 March 2026. Ensure that your response reaches us before the closing date.

What will happen next

We will publish a summary of responses and the government response on the homepage for this call for evidence. Paper copies will be available on request.

If you have questions about this call for evidence, please contact:

SAF Mandate team
Great Minster House
33 Horseferry Road
London
SW1P 4DR

Alternatively, you can email: lowcarbonfuel.consultation@dft.gov.uk.

Full list of questions

These questions are included here so you can read them in the context of this document. The call for evidence response form may include more questions, for example, questions about who you are.

See the Ways to respond section of the GOV.UK home page for this call for evidence to read a full list of questions and find out how you can respond to them.

Question 2: What competing uses and emerging/future uses exist for crop feedstocks? Please comment on specific crops where possible.

Question 3: What are the potential impacts of crops on a UK SAF production industry? Please consider any potential benefits or risks to advanced technology development.

Question 4: If there are risks to advanced technology development, are there any policy options to mitigate these? Please consider short- and long-term measures.

Question 6: Please provide data on the carbon intensity of crop-derived SAF production, taking into account different types of crop and production pathways. 

Question 7: What are the sustainability risks that exist for each of the crop types? Please consider how these risks vary between different crop types and regions.

Question 8: To what extent does ILUC exist for different crops? How can ILUC most robustly and accurately be accounted for?

Question 10: What agronomic practices and management measures could be applied to mitigate against any sustainability risks identified?

Question 11: Are the current sustainability criteria sufficient to mitigate against risks identified? If not, what sustainability criteria would be required?

Question 12: What assurance measures are required to evidence these crops protect against risks identified?

Freedom of information

Information provided in response to this consultation, including personal information, may be subject to publication or disclosure in accordance with the Freedom of Information Act 2000 (FOIA) or the Environmental Information Regulations 2004.

If you want information that you provide to be treated as confidential, please be aware that, under the FOIA, there is a statutory code of practice with which public authorities must comply and which deals, amongst other things, with obligations of confidence.

In view of this, it would be helpful if you could explain to us why you regard the information you have provided as confidential. If we receive a request for disclosure of the information, we will take full account of your explanation, but we cannot give an assurance that confidentiality can be maintained in all circumstances. An automatic confidentiality disclaimer generated by your IT system will not, of itself, be regarded as binding on the department.

Data protection

The Department for Transport (DfT) is carrying out this call for evidence on the treatment of crops under the SAF Mandate.

Your personal data collected through this call for evidence is processed in line with our online forms, surveys and consultations privacy notice.

In addition to the information given, we are asking all organisations their area of work, to ascertain their relationship to the topic.

DfT’s privacy policy has more information about your rights in relation to your personal data, how to complain and how to contact the Data Protection Officer.

To receive this information by telephone or post, write to:

Data Protection Officer
Department for Transport
3rd Floor
One Priory Square
Hastings
East Sussex TN34 1EA

Alternatively, you can call: 0300 330 3000

Your information will be kept securely on secure IT systems within DfT and will be destroyed within 24 months after the consultation has been completed.

Footnotes

Data based on RTFO Statistics 2024: Final Report and DESNZ Energy Trends ↩
SAF Market Outlook, SkyNRG and ICF, 2025 ↩
Clear Skies Ahead: Ensuring success for the UK SAF Mandate, Philip New, 2025 ↩
Environmental sustainability of biofuels: a review ↩
Use of U.S. Croplands for Biofuels Increases Greenhouse Gases Through Emissions from Land-Use Change ↩
Study on Indirect Land Use Changes ↩
Environmental outcomes of the US Renewable Fuel Standard ↩
The Gallagher Review of the indirect effects of biofuels production ↩
https://www.transportenvironment.org/uploads/files/2019_01_High_low_ILUC_TE_briefing_final.pdf ↩
Progress and barriers in understanding and preventing indirect land-use change ↩
https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:52019DC0142&from=DE#:~:text=Addressing%20ILUC%20through%20REDII ↩
https://www.gov.uk/government/publications/renewable-transport-fuel-obligation-rtfo-compliance-reporting-and-verification ↩
The impact of biofuels on food security - ScienceDirect ↩
Food not fuel: Why biofuels are a risk to food security ↩
Systematic review on effects of bioenergy from edible versus inedible feedstocks on food security ↩
Biofuels’ impact on food security debate resurfaces amid Ukraine war ↩
The imbalance of food and biofuel markets amid Ukraine-Russia crisis: A systems thinking perspective ↩
The EU’s definition, as stipulated in Annex IX of the amended Renewable Energy Directive, defines these as: ‘Intermediate crops, such as catch crops and cover crops that are grown in areas where due to a short vegetation period the production of food and feed crops is limited to one harvest and provided their use does not trigger demand for additional land, and provided the soil organic matter content is maintained, where used for the production of biofuel for the aviation sector’. ↩

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