How is SAF Produced? Sustainable Aviation Fuel Feedstocks, Production Pathways and Latest Advancements

Sustainable aviation fuel (SAF) is the aviation industry’s most mature pathway toward reducing the carbon emissions associated with commercial and business aviation. Unlike hydrogen propulsion or electric aircraft, which require fundamental changes to aircraft design and airport infrastructure, SAF is a drop-in fuel: it works in existing engines, existing fuel systems, and existing supply chains, requiring only a shift in how the fuel itself is produced and sourced. For business aviation operators, Just Aviation’s sustainable solutions service provides SAF coordination and sustainability reporting support.

The central question for operators, sustainability managers, and procurement professionals new to SAF is: how is SAF produced, and how does that production process determine the fuel’s carbon reduction potential? The answer depends on the production pathway used, which in turn depends on the feedstock: the raw material from which the SAF is manufactured.

This guide covers the primary sustainable aviation fuel feedstocks and production pathways currently approved for commercial use, how SAF production works at each stage, how SAF compares to traditional jet fuel on cost and performance, and the latest advancements in SAF technology that are expanding both supply and the range of approved production methods.

What is Sustainable Aviation Fuel (SAF)?

Sustainable Aviation Fuel, or SAF, is a renewable and environmentally friendly alternative to conventional jet fuel. It is derived from sustainable feedstocks such as agricultural residues, waste oils, and dedicated energy crops.

Airlines belonging to the International Air Transport Association (IATA) have made a commitment to reach carbon neutrality in their operational activities by 2050. They have identified Sustainable Aviation Fuel (SAF) as a viable solution that could potentially reduce their emissions by up to 65%.

SAF has the potential to achieve this because it belongs to the category of biofuels, which are derived from plant or animal materials instead of fossil fuels. BP produces SAF by utilizing cooking oil and animal waste fat as raw materials. Additionally, alternative options for SAF production include utilizing agricultural and forestry waste, as well as municipal waste.

 

Types of Sustainable Aviation Fuels (SAF)

There are several types of Sustainable Aviation Fuels (SAF) available, each with its own production process and properties. Some of the most common types of SAF include:

1. Hydroprocessed Esters and Fatty Acids (HEFA)

This type of SAF is produced from vegetable oils, animal fats, and used cooking oil through a process called hydroprocessing. HEFA SAF is the most commonly produced and used SAF today.

2. Fischer-Tropsch (FT)

FT SAF is produced from biomass or natural gas using a process called gas-to-liquid conversion. FT SAF has high energy density and is considered a drop-in fuel that can be used in existing engines without modification.

3. Alcohol-to-Jet (ATJ)

ATJ SAF is produced from sugar, corn, or other feedstocks through fermentation and conversion to alcohol, which is then processed into sustainable jet fuel.

4. Pyrolysis

Pyrolysis SAF is produced from the thermal decomposition of biomass. The process breaks down the feedstock into a gas that is then converted into liquid fuel.

5. Biomass-to-Liquid (BTL)

BTL SAF is produced from a variety of feedstocks, such as wood chips, agricultural waste, and straw, through gasification and conversion to liquid fuel.

Sustainable Aviation Fuel Feedstocks: What SAF is Made From and How Feedstock Choice Affects Carbon Reduction

The sustainable aviation fuel feedstock is the raw material from which SAF is manufactured. Just Aviation coordinates aviation fuel and SAF uplift at airports across our global network. Feedstock choice is the single most important variable in determining the carbon reduction potential of any specific batch of SAF, because the lifecycle carbon calculation compares the carbon released when the fuel is burned against the carbon absorbed during the growth or production of the feedstock material.

The primary sustainable aviation fuel feedstocks currently approved for commercial SAF production divide into four categories.

• Lipid-based feedstocks. These include used cooking oil (UCO), animal fats (tallow and lard), and non-edible vegetable oils such as camelina and jatropha. Lipid-based feedstocks are the most widely used today because they process well through the HEFA pathway, which is the most commercially mature SAF production technology. Used cooking oil is the dominant feedstock for current SAF production globally. Lifecycle carbon reductions from lipid-based SAF typically range from 50% to 85% compared to conventional jet fuel.
• Agricultural and forestry residue feedstocks. These include corn stover, wheat straw, bagasse (the fibrous residue from sugar cane processing), and forest thinnings. These feedstocks are available in large volumes and do not compete with food supply chains, but they require more complex processing than lipid feedstocks. The Fischer-Tropsch and Biomass-to-Liquid pathways are most commonly used for residue-based feedstocks.
• Municipal solid waste (MSW) and waste gases. Non-recyclable municipal solid waste, landfill gas, and industrial waste gases including carbon monoxide and carbon dioxide from steel and cement production can all serve as SAF feedstocks through gasification and power-to-liquid pathways. MSW-based SAF has the potential for very high carbon reduction figures because it avoids the methane emissions that would otherwise result from landfill decomposition.
• Alcohol feedstocks. Sugars from sugar cane, sugar beet, corn, and cellulosic biomass can be fermented to produce ethanol or isobutanol, which are then converted to sustainable jet fuel through the Alcohol-to-Jet (ATJ) pathway. Ethanol-to-jet is the most commercially developed ATJ route and is the subject of several active production scale-up projects.

Feedstock availability is the primary constraint on SAF supply growth globally. The most economically accessible feedstocks (used cooking oil and animal fats) have limited global supply relative to aviation’s fuel demand, which is why the industry’s long-term SAF scaling plan depends on developing the agricultural residue, MSW, and alcohol pathways to commercial maturity.

How is SAF Currently Produced?

Traditional jet fuel is made from carbon-rich crude oil that is extracted from the ground. When it is burned in aircraft engines, that carbon is released into the atmosphere. Sustainable aviation fuel, however, is made from animal byproducts or agricultural waste, oils from plants and other biomass. When SAF is made from mustard seeds, for example, new mustard plants absorb and store the carbon molecules released in its combustion, making it renewable.

SAF can be manufactured using renewable feedstocks that are not derived from petroleum sources. These feedstocks include, but are not limited to, the organic waste from municipal solid waste, woody biomass, fats, greases, oils, and other similar materials. The production of SAF is still in its early stages, but there are currently three known commercial producers:

1. World Energy initiated SAF production in 2016 at its facility in Paramount, California. Initially, they supplied fuel to Los Angeles International Airport and later expanded their supply to other airports in California.
2. Neste, an international producer, began supplying SAF to San Francisco International Airport in 2020. They subsequently expanded their supply to other airports in California in 2021 and 2022. Additionally, they started supplying SAF to Aspen/Pitkin County Airport and Telluride Regional Airport, both located in Colorado.
3. Montana Renewables LLC partnered with Shell to commence SAF production in 2023. They utilize an existing petroleum production plant and supply fuel to several partner airlines.

The production of approved fuels for aviation purposes, as outlined by the ASTM (American Society for Testing and Materials), involves various technology pathways and blending limitations. The ASTM D7566 Standard Specification for Aviation Turbine Fuel Containing Synthesized Hydrocarbons sets forth quality standards for non-petroleum-based jet fuel. It specifies the approved SAF-based fuels and the maximum allowable percentage of these fuels in a blend with Jet A fuel. All three existing plants utilize the hydro processed esters and fatty acids pathway, as indicated in the table on this page. Furthermore, it is anticipated that new domestic plants will emerge, employing the alcohol-to-jet pathway with ethanol as a feedstock.

The ASTM D1655 Standard Specification for Aviation Turbine Fuels permits the co-processing of biomass feedstocks at petroleum refineries, allowing blends of up to 5%. This standard governs the quality specifications for conventional petroleum-based aviation turbine fuels.

 

How Sustainable Aviation Fuel Works ?

SAF works in a similar way to traditional jet fuel, powering aircraft engines and enabling them to generate thrust. The key difference lies in the reduced greenhouse gas emissions associated with SAF. When SAF is burned, it releases significantly fewer carbon dioxide (CO2) emissions compared to conventional jet fuel. This reduction in emissions plays a crucial role in mitigating the impact of aviation on climate change.

Latest Advancements in SAF Technology: Production, Blending and Aviation Fuel Management

The latest advancements in sustainable aviation fuel technology span three areas: new production pathway approvals, improvements in SAF blending ratios, and advanced aviation fuel management technology for handling, quality assurance, and supply chain integration.

Production pathway advancements. The ASTM D7566 standard, which governs approved SAF production pathways, has expanded from its initial two approved pathways to nine approved pathways as of the most recent revision cycle. New approvals include Power-to-Liquid (PtL) SAF, produced from captured carbon dioxide and green hydrogen, which has the potential to achieve near-zero or even carbon-negative lifecycle emissions. The PtL pathway is considered the long-term solution for SAF supply at scale because it decouples production from biological feedstock availability entirely.

Blending ratio advancements. Current approved SAF blending limits allow SAF to comprise up to 50% of the fuel blend in most certified pathways, with the remainder being conventional Jet-A or Jet A-1 fuel. Industry testing under the ASTM qualification process is actively working toward 100% SAF certification (sometimes referred to as neat SAF), which would eliminate the blending requirement and allow SAF to be used as a pure drop-in replacement. Several airlines and aircraft manufacturers have conducted 100% SAF test flights, and regulatory qualification is progressing with multiple pathway approvals anticipated within this decade.

Advanced aviation fuel management technology. Managing SAF through existing airport and aircraft fuel systems requires attention to quality assurance, blending accuracy, and documentation. Advanced aviation fuel management technology in this context includes real-time fuel quality monitoring systems that verify SAF blend ratios and fuel properties during fueling operations, digital chain of custody documentation that provides operators with the certified lifecycle carbon data needed for CORSIA compliance reporting, including through SAF book and claim mechanisms that allow operators to claim SAF benefits without physical uplift at every location, and predictive fuel demand planning systems that help fuel suppliers and operators coordinate SAF uplift across complex itineraries.

For business aviation operators, the most practically relevant SAF technology advancement is the growing number of airports and FBOs where SAF is available for uplift. While SAF availability was limited to a handful of major airports until recently, the network of SAF-capable locations has expanded significantly as regulatory mandates (particularly ReFuelEU in Europe) drive supply infrastructure investment.

How is SAF Different From Traditional Jet Fuel?

SAF stands apart from traditional jet fuel due to its renewable nature and lower carbon footprint. While conventional jet fuel is derived from fossil fuels, SAF is produced from sustainable feedstocks. Additionally, SAF has the potential to reduce greenhouse gas emissions by up to 80% compared to traditional jet fuel. This significant reduction makes SAF a vital component in the aviation industry’s efforts to achieve carbon neutrality.

 

Sustainable Aviation Fuel Benefits

 

SAF offers a range of benefits that make it an attractive option for the aviation industry:

Environmental Impact: The use of SAF can help reduce aviation’s carbon footprint, contributing to global efforts to combat climate change. For a broader overview of aviation decarbonization strategies, see Just Aviation’s guide to decarbonization solutions in business aviation.

Energy Security: By diversifying fuel sources, SAF reduces dependence on fossil fuels, enhancing energy security.

Air Quality Improvement: SAF produces fewer emissions of pollutants like sulfur and particulate matter, leading to cleaner air around airports and communities.

Technological Compatibility: SAF can be used in existing aircraft engines without requiring any modifications, making it a viable option for the current aviation fleet.

Job Creation: The development and production of SAF create new opportunities for job growth in the renewable energy sector.

 

Why Should We Switch To Sustainable Aviation Fuel “SAF”?

The aviation industry plays a significant role in global carbon emissions, and the adoption of SAF is a crucial step towards achieving sustainability. By switching to SAF, we can:

• Reduce greenhouse gas emissions: SAF has the potential to significantly reduce CO2 emissions, helping mitigate the impact of aviation on climate change.
• Enhance environmental stewardship: The use of SAF demonstrates a commitment to preserving the environment and reducing the ecological footprint of the industry.
• Drive innovation: Investing in SAF encourages research and development of new technologies, creating a pathway for cleaner and more sustainable aviation practices.
• Meet regulatory requirements: As governments and international organizations set stricter emission standards, adopting SAF becomes essential for compliance.

 

Frequently Asked Questions

How much can SAF reduce greenhouse gas emissions?

SAF has the potential to reduce greenhouse gas emissions by up to 80% compared to traditional jet fuel. This significant reduction in emissions plays a vital role in mitigating the impact of aviation on climate change.

Are there any drawbacks to using SAF?

While SAF offers numerous benefits, there are some challenges to its widespread adoption. One of the primary concerns is the limited availability and high production costs, which can make SAF more expensive than traditional jet fuel. Additionally, the infrastructure required for the production and distribution of SAF needs further development to support its widespread use.

Is SAF more expensive than jet fuel?

Yes, SAF is currently more expensive than conventional jet fuel in most markets. The price premium depends on the production pathway and feedstock used, regional incentive structures, and the specific supplier, but SAF typically costs between two and five times the price of equivalent conventional Jet-A fuel at the point of uplift.

The primary drivers of the cost difference are the relatively small scale of current SAF production compared to conventional jet fuel, the higher cost of sustainable feedstocks versus crude oil, and the additional processing steps required in SAF production pathways compared to petroleum refining.

How does SAF impact airplane performance?

From a performance perspective, SAF has been proven to be compatible with existing aircraft engines without requiring any modifications. This means that airplanes can operate smoothly and efficiently using SAF, ensuring no compromise in performance or safety.

How much SAF is currently used in commercial aviation?

Currently, the use of SAF in commercial aviation is relatively limited. However, there is a growing interest and commitment from airlines and governments to increase its usage. Several airlines have already started incorporating SAF into their fuel blends, and initiatives are underway to expand its availability in the market.

What are the future prospects for SAF adoption in aviation?

The future prospects for SAF adoption in aviation are promising. The International Air Transport Association (IATA) has set ambitious goals to achieve carbon-neutral growth in the industry by 2050. To achieve this, the widespread use of SAF will be crucial. Governments, industry stakeholders, and research organizations are actively working together to develop sustainable feedstocks, improve production processes, and create a supportive regulatory framework to accelerate the adoption of SAF.

What are the expected costs of SAF compared to traditional jet fuel in the future?

Currently, SAF production costs are higher than traditional jet fuel due to factors such as limited production capacity and feedstock availability. However, as technology advances and production scales up, it is expected that the costs of SAF will decrease, making it more competitive with traditional jet fuel in the future. Additionally, government incentives and market demand can further drive down the costs of SAF.

How can government policies and regulations encourage the use of SAF?

Government policies and regulations play a vital role in encouraging the use of SAF. Some strategies include:

• Implementing incentives and subsidies to reduce the cost of SAF production and increase its availability in the market.
• Setting carbon pricing mechanisms that create economic incentives for airlines to switch to SAF.
• Establishing long-term targets and commitments for reducing greenhouse gas emissions in the aviation sector.
• Supporting research and development efforts to improve SAF production processes and develop advanced technologies.
• Collaborating with international organizations and other governments to create harmonized regulations and standards for SAF.

Just Aviation’s Sustainable Solutions service supports business aviation operators in incorporating SAF into their operations, from identifying SAF availability at planned destinations to coordinating SAF uplift as part of trip planning. For flight departments looking to report SAF usage for CORSIA compliance, corporate ESG reporting, or voluntary carbon reduction commitments, Just Aviation provides the documentation and coordination support needed to make SAF adoption operationally straightforward. Contact our team to discuss SAF availability on your regularly flown routes and how sustainable aviation fuel can be integrated into your operation.