Transforming Waste into Jet Fuel: The Role of Pyrolysis in Sustainable Aviation Fuel (SAF)

The roar of a jet engine, once a symbol of endless adventure, now emphasizes the urgency of sustainability. In the midst of climate change, the aviation industry faces significant pressure to drastically reduce its carbon footprint.

While electric and hydrogen-powered planes are on the horizon for shorter routes, the immediate and most promising solution for long-haul flights lies firmly with Sustainable Aviation Fuel (SAF). 

But what if the solution to cleaner skies isn’t just about innovation in fuel chemistry, but about rethinking waste itself? Enter pyrolysis—an ingenious technology that transforms everything from agricultural residues to municipal solid waste and plastics into high-quality jet fuel. 

This approach doesn’t just cut emissions; it turns pressing environmental challenges into powerful opportunities, advancing a truly circular economy for aviation.

As pyrolysis gains traction, it offers a glimpse into a future where the planes of tomorrow could be powered by the waste of today, bridging the gap between sustainability and the ever-growing demand for air travel.

The Urgent Need for Sustainable Aviation Fuel (SAF)

The global aviation sector is projected to grow significantly in the coming decades, leading to a corresponding increase in its carbon emissions. While efficiency improvements and operational changes can help, they are insufficient to meet the ambitious decarbonization targets set by international bodies like the International Air Transport Association (IATA), which aims for net-zero carbon emissions by 2050.

Traditional jet fuel, derived from fossil sources, releases substantial amounts of greenhouse gases (GHGs) upon combustion. SAF offers a viable alternative, designed to reduce carbon emissions by up to 80% over its lifecycle compared to conventional jet fuel. However, the current production of SAF is limited, and expanding its availability requires exploring diverse and sustainable feedstocks. This is where waste-to-fuel technologies, particularly pyrolysis, come into play.

Airlines Sustainability Efforts

Airlines are increasingly focusing on sustainability, driven by a growing awareness of their environmental impact and pressure from consumers and regulators. Many major airlines have set ambitious goals to reduce carbon emissions, with some aiming for net-zero emissions by 2050. These efforts include investing in more fuel-efficient aircraft, optimizing flight paths to reduce fuel consumption, and, most importantly, adopting Sustainable Aviation Fuel (SAF). The use of SAF is a critical component of their strategy to decarbonize, as it can significantly reduce greenhouse gas emissions compared to conventional jet fuel.

What is Sustainable Aviation Fuel (SAF)

Sustainable Aviation Fuel (SAF) is a type of alternative jet fuel made from renewable and waste-derived resources—such as agricultural residue, municipal solid waste, used cooking oil, forestry waste, or animal fats—instead of traditional fossil petroleum sources. SAF is chemically very similar to conventional jet fuel, which makes it a "drop-in" fuel: it can be blended with regular jet fuel (typically up to 50%) and used in existing aircraft engines and airport infrastructure without modification.

The main benefits of SAF are:

• Significant reduction in lifecycle greenhouse gas emissions: Depending on the feedstock and production method, SAF can reduce emissions by up to 80%, with future generations of SAF potentially achieving reductions up to 94%.
• Compatibility with current infrastructure: SAF can be used in existing aircraft and fueling systems without changes, supporting a smoother transition for the aviation industry.
• Support for industry climate targets: SAF is seen as the most viable near-term solution for reducing aviation’s carbon footprint and helps airlines and regulators work toward net-zero carbon emissions by 2050.

Sustainable Aviation Fuel (SAF) Companies

The rise of SAF has led to the emergence of numerous companies specializing in its production. These companies are at the forefront of developing innovative technologies to create aviation fuel from non-petroleum sources. Key players in this space include:

Neste: A leading producer of renewable diesel and SAF, utilizing a variety of waste and residue raw materials.

LanzaJet: A technology provider and producer of SAF from ethanol and other sustainable sources.

World Energy: A company with a long history in renewable fuels, now a major producer of SAF.

Gevo: Focuses on converting sustainable resources like isobutanol into SAF.

Fulcrum BioEnergy: Pioneers in producing SAF from municipal solid waste via gasification and Fischer-Tropsch synthesis.

Types of Sustainable Aviation Fuel (SAF)

Synthetic aviation fuel is a type of SAF created through chemical processes rather than from biological feedstocks. One of the most promising methods for producing synthetic aviation fuel is Power-to-Liquid (PtL) technology. This process uses renewable electricity to split water into hydrogen and captures carbon from the air or industrial sources. The hydrogen and captured carbon are then synthesized into a liquid fuel. This method is particularly exciting because it has the potential to create a fuel with a very low carbon footprint, and the availability of biomass does not limit it.

Bio-jet fuel is a type of SAF derived from biomass, such as plant matter, animal fats, and waste oils. These feedstocks are processed to produce fuel that is chemically similar to conventional jet fuel, allowing it to be used in existing aircraft engines without modification. 

Common feedstocks for bio-jet fuel include used cooking oil, algae, and dedicated energy crops like camelina and jatropha. The use of bio-jet fuel significantly reduces life-cycle carbon emissions because the carbon released during combustion is offset by the carbon absorbed by the plants during their growth.

There are several approved pathways for producing SAF, each with its own unique feedstock and production method. The most common types include:

• Hydroprocessed Esters and Fatty Acids (HEFA): The most common type of SAF today, produced from waste oils and fats.
• Fischer-Tropsch (FT): A process that converts syngas (a mixture of hydrogen and carbon monoxide) from sources like municipal solid waste, forestry residues, or captured CO2 into a liquid fuel.
• Alcohol-to-Jet (ATJ): Converts alcohols, such as ethanol or isobutanol, into jet fuel.
• Hydrothermal Liquefaction (HTL): A process that uses high temperature and pressure to convert wet biomass into a biocrude oil that can be refined into jet fuel.

Summary of SAF-Type Differences:

Sustainable Aviation Fuel Price

The price of SAF is currently a major barrier to its widespread adoption. SAF is significantly more expensive than conventional jet fuel, often costing two to five times more. This high cost is primarily due to the limited production scale, the cost of sustainable feedstocks, and the capital-intensive nature of the production technologies. However, as production scales up, new technologies become more efficient, and government incentives for SAF production and use are implemented, prices are expected to decrease.

Sustainable Aviation Fuel Production

SAF can be produced from a diverse range of feedstocks, which is a key advantage of the technology. These feedstocks are generally categorized into three main groups:

• Oils and fats: Used cooking oil, animal fats, and waste from vegetable oil processing.
• Biomass: Agricultural residues, forestry waste, and purpose-grown energy crops.
• Waste products: Municipal solid waste, landfill gas, and industrial waste gases.

Making Jet Fuel from CO2

Making jet fuel from captured CO2 is a revolutionary approach to creating synthetic SAF. This process, often referred to as Power-to-Liquid (PtL) or e-fuel technology, involves using renewable electricity to power an electrolyzer that splits water into hydrogen and oxygen. The hydrogen is then combined with captured CO2 in a synthesis process (like Fischer-Tropsch) to create a liquid hydrocarbon fuel. This method has the potential to be a truly carbon-neutral solution for aviation, as the carbon emitted during combustion is balanced by the carbon captured during the production process.

Carbon Neutral Aviation Fuel

The concept of carbon-neutral aviation fuel refers to fuels that, when burned, do not contribute to a net increase in atmospheric CO2. This is achieved by using feedstocks or processes that capture as much CO2 from the atmosphere as is released during the fuel's life cycle. For example, bio-jet fuels made from algae or dedicated energy crops are considered carbon-neutral because the plants absorb CO2 as they grow. Similarly, synthetic fuels made from captured CO2 can be carbon-neutral if the electricity used in their production is from renewable sources.

Can Planes Fly on 100% SAF?

The short answer is: increasingly, yes! While commercial flights currently use blends of SAF with conventional jet fuel (typically up to 50%), recent test flights have successfully demonstrated the ability of commercial aircraft to fly on 100% SAF. These groundbreaking trials have shown not only comparable performance to traditional jet fuel but also significant reductions in soot particle emissions and contrail ice crystal formation, further bolstering SAF's environmental benefits. The industry is actively working towards certification for higher blend ratios, paving the way for a future where planes routinely fly on unblended SAF.

Pyrolysis in Sustainable Aviation Fuel (SAF)

While the rise of Sustainable Aviation Fuel (SAF) has introduced several pathways for decarbonizing air travel, pyrolysis is emerging as a game-changer. This revolutionary technology addresses a key limitation of the most common SAF methods today: the scarcity of sustainable feedstock. By turning abundant and problematic waste materials into high-quality jet fuel, pyrolysis offers a scalable and truly circular solution for the aviation industry.

Pyrolysis vs. HEFA SAF—Which Is Better?

When it comes to SAF production pathways, Hydroprocessed Esters and Fatty Acids (HEFA) currently dominate the market. HEFA primarily uses waste fats, oils, and greases (FOGs) as feedstock. While effective, the availability of these specific feedstocks is limited.

This is where pyrolysis shines. Pyrolysis offers a crucial advantage by being feedstock-agnostic, meaning it can process a much wider range of waste materials, including:

• Lignocellulosic biomass: Agricultural residues, forestry waste, dedicated energy crops.
• Municipal solid waste (MSW): The organic, non-recyclable portion of household waste.
• Waste plastics: A significant environmental challenge that pyrolysis can convert into valuable resources.
• Waste tires: Another challenging waste stream that can be transformed into jet fuel.

This broader feedstock flexibility makes pyrolysis a more scalable and sustainable long-term solution, reducing reliance on potentially constrained resources. Furthermore, some studies suggest pyrolysis can offer lower production costs due to the affordability of its waste feedstocks compared to the more limited and expensive vegetable oils used in HEFA.

How Pyrolysis Converts Waste into Renewable Jet Fuel

Pyrolysis is a thermochemical process that involves heating organic materials in the absence of oxygen. This breaks down complex organic compounds into simpler ones, yielding three main products:

The raw bio-oil produced from pyrolysis is typically highly oxygenated, acidic, and unstable, requiring further upgrading to meet jet fuel specifications. This upgrading usually involves hydroprocessing (also known as hydrotreating or hydrodeoxygenation), where the bio-oil is treated with hydrogen under high pressure and temperature in the presence of catalysts. This process removes oxygen, nitrogen, and sulfur, and rearranges the hydrocarbon chains to produce a high-quality, stable, and "drop-in" ready jet fuel that is chemically identical to conventional jet fuel.

Upgrading Bio-oil to Jet Fuel: A Crucial Step

The raw bio-oil produced from pyrolysis is not directly suitable as jet fuel. It contains high levels of oxygen, water, and various complex organic compounds that can lead to instability, corrosiveness, and low energy content. Therefore, a crucial upgrading process is required to transform bio-oil into a usable SAF.

Common upgrading techniques include:

• Hydrotreatment (Hydrodeoxygenation): This is the most widely used upgrading method. Bio-oil is reacted with hydrogen at high temperatures and pressures in the presence of a catalyst. This process removes oxygen, sulfur, and nitrogen, producing a stable, high-quality hydrocarbon fuel similar to conventional jet fuel.
• Catalytic Cracking: This involves breaking down larger molecules in the bio-oil into smaller, more volatile ones suitable for jet fuel.
• Esterification and Hydroprocessing: A combination of processes that convert fatty acids present in some bio-oils into hydrocarbons.

The resulting upgraded bio-oil, now a high-quality hydrocarbon, can be blended with conventional jet fuel or used as a standalone SAF, meeting stringent aviation fuel specifications.

The Future of Pyrolysis: Pathways to Sustainable Aviation Fuel (SAF)

Pyrolysis offers several pathways for SAF production, each with its own advantages:

• Fast Pyrolysis with Hydrotreating: This is a common and promising pathway. Fast pyrolysis produces a significant yield of bio-oil, which is then refined through hydroprocessing.
• Catalytic Fast Pyrolysis (CFP): Incorporating catalysts directly into the pyrolysis process can improve the quality of the bio-oil, making the subsequent upgrading steps more efficient and potentially leading to higher yields of desired jet fuel components like cycloalkanes.
• Co-pyrolysis: Combining different waste feedstocks (e.g., plastics and biomass) can optimize the pyrolysis process and improve the characteristics of the resulting bio-oil for SAF production.

These diverse pathways highlight the versatility and adaptability of pyrolysis in tackling various waste streams and tailoring the output for aviation needs.

How Pyrolysis is Revolutionizing Sustainable Aviation Fuels

Pyrolysis is revolutionizing SAF by:

Pyrolysis-Derived SAF: The Next-Generation Sustainable Aviation Fuel Explained

Pyrolysis-derived SAF represents a significant leap forward in sustainable aviation. It's not just about burning something different; it's about a fundamental shift in how we source and produce aviation fuel. By converting challenging waste materials into high-quality, renewable jet fuel, pyrolysis offers a pathway to drastically reduce aviation's carbon footprint and create a truly sustainable future for air travel. The resulting fuel meets stringent aviation specifications, ensuring safety and performance are never compromised.

From Biomass to Jet Fuel: The Power of Pyrolysis for SAF Production

The journey from biomass (or other waste) to jet fuel via pyrolysis is a testament to innovative engineering and chemistry. It involves:

• Feedstock Collection and Pre-treatment: Sourcing and preparing the waste material (e.g., drying, sizing).
• Pyrolysis: Thermal decomposition in an oxygen-free environment to produce bio-oil, char, and syngas.
• Bio-oil Upgrading: Extensive hydroprocessing to remove impurities and unwanted components, and to improve the fuel properties.
• Distillation and Blending: Further refining to achieve the desired jet fuel specifications and blending with conventional jet fuel (if required).

This integrated process demonstrates the immense potential of pyrolysis to close the loop on waste and transform it into a crucial component of a greener aviation industry.

Why Pyrolysis is Key in Sustainable Aviation Fuel Innovation

Pyrolysis is central to SAF innovation for several reasons:

• Feedstock Abundance: It unlocks a vast and diverse pool of non-food-competing feedstocks, which is critical for long-term scalability.
• Waste Management Solution: It provides an effective and environmentally sound way to manage various waste streams.
• Cost Competitiveness: The potential for lower feedstock costs and efficient processing can make pyrolysis-derived SAF more economically viable.
• Technological Advancement: Ongoing research and development are continually improving pyrolysis efficiency, bio-oil quality, and the overall SAF production process.
• Pathway to Net-Zero Aviation: As a highly effective method for producing low-carbon, drop-in fuel, pyrolysis is an indispensable tool in the aviation industry's pursuit of net-zero emissions.

As the aviation industry seeks to reduce its environmental footprint, achieving full decarbonization without Sustainable Aviation Fuel (SAF) seems quite unlikely in the near future. Other strategies, such as developing more fuel-efficient aircraft and optimizing flight paths, are essential but alone are not enough to meet the ambitious net-zero targets.

• Electric and Hydrogen-Powered Aircraft: Though promising, electric and hydrogen technologies are still in their infancy for commercial aviation. They are currently only viable for smaller aircraft on short-haul routes due to the significant weight and volume of batteries and hydrogen tanks. This makes them unsuitable for the long-haul flights that constitute a large portion of the industry's carbon footprint.
• Operational Efficiencies: Airlines have been implementing operational efficiencies for years, from flying more direct routes to reducing the weight on board. While these measures have a positive impact, they offer incremental improvements and cannot achieve the deep decarbonization required to meet climate goals.
• Carbon Offsetting and Trading Schemes: Carbon offsetting, while a useful tool, does not directly reduce emissions from flying. It involves investing in projects that reduce greenhouse gases elsewhere to compensate for aviation's emissions. This is often viewed as a temporary measure and is not a long-term solution for eliminating the industry's carbon footprint.

Ultimately, SAF is a crucial and readily available solution that can be used in existing aircraft without requiring significant infrastructure changes. It's the most effective way to achieve substantial emission reductions for both short- and long-haul flights, making it an indispensable part of any comprehensive decarbonization strategy.

Finally!
Pyrolysis stands at the forefront of the sustainable aviation fuel revolution, offering a practical and transformative solution to one of the aviation industry’s greatest challenges: decarbonizing long-haul air travel. By harnessing the power of waste—whether it’s agricultural residues, municipal solid waste, or even plastics—pyrolysis turns environmental problems into high-value jet fuel, embodying the principles of the circular economy.

As airlines and governments race toward ambitious net-zero goals, the scalability and feedstock flexibility of pyrolysis-derived SAF give it a unique and vital role. Not only does this technology promise to reduce aviation’s carbon footprint drastically, but it also unlocks new pathways for innovation, waste management, and economic growth.

The journey to widespread adoption of sustainable aviation fuels is just beginning, but pyrolysis is already charting a course toward cleaner skies. By transforming today’s waste into tomorrow’s flight, we’re not just making aviation more sustainable—we’re pioneering a future where every journey leaves the planet better than we found it.