A New Era of Aviation Sustainability Sustainable aviation fuel (SAF) is no longer just a distant vision—it’s the cornerstone of aviation’s journey toward net-zero emissions. As the industry searches for ways to decarbonize, co-processing in existing refineries emerges as an innovative and cost-effective pathway to scale SAF production. By leveraging renewable feedstocks and existing refinery infrastructure, co-processing bridges the gap between traditional fossil fuels and the green fuels of tomorrow.

1. The Basics of Co-Processing

The cost disparity between synthetic and fossil fuels is rooted in production challenges and resource constraints:

A Win-Win Approach Co-processing involves introducing renewable feedstocks—such as vegetable oils, animal fats, and other bio-based materials—directly into existing refinery units, such as kerosene hydrotreaters. This method allows refineries to produce a blend of renewable and fossil-based fuels without the need for extensive modifications.

• Reduced Carbon Footprint: The process helps significantly cut CO2 emissions by replacing a portion of fossil-based feedstocks with renewable alternatives.

• Flexibility: ASTM standards permit renewable feedstock levels of up to 5% for SAF production. This allows refineries to start small and scale gradually.

• Seamless Integration: Co-processing avoids the need for building new infrastructure, making it a low-CAPEX solution.

2. Why Co-Processing Matters for SAF Production

The aviation industry accounts for 2-3% of global CO2 emissions, making decarbonization a pressing priority. SAF is a game-changer, offering up to an 80% reduction in lifecycle greenhouse gas emissions compared to conventional jet fuel. Co-processing aligns perfectly with this mission, offering several critical benefits:

• Strategic Advantage: Refineries adopting co-processing now position themselves as pioneers in the renewable energy transition, gaining a competitive edge.

• Scalability: Co-processing allows refineries to ramp up SAF production while navigating the challenges of supply chain constraints.

• Economic Viability: With minimal investment, refineries can diversify their operations and tap into the growing SAF market.

3. The Cost of transition

Key Considerations While co-processing is cost-effective compared to building new facilities, several factors influence the overall investment:

• Hydrogen Availability: Refineries with excess hydrogen supply can co-process SAF with minimal modifications, reducing costs.
• Infrastructure: Facilities with modern kerosene hydrotreaters operating at moderate pressures often only require catalyst changes.
• Logistics: Acquiring and storing renewable feedstocks, as well as adapting supply chains, can add to operational expenses.

For refineries with limited capabilities, upgrading hydrogen units or hydroprocessing systems may be necessary, leading to higher CAPEX requirements.

4. Technical challenges

Overcoming Barriers to Success Despite its promise, co-processing is not without its challenges. One of the most significant hurdles is maintaining the freeze point of jet fuel, a critical safety parameter in aviation. Renewable feedstocks can deteriorate cold flow properties, necessitating the use of advanced dewaxing catalysts.

Additionally, most kerosene hydrotreaters are not designed for high renewable feedstock volumes. Operators need to navigate:

• Limited catalyst volumes.
• Low operating pressures.
• Restricted maximum operating temperatures.

Innovative solutions, such as selective hydrodeoxygenation catalysts, are essential to unlocking the full potential of SAF production through co-processing.

5. The role of ASTM standards in SAF developments

ASTM standards ensure that SAF meets stringent safety, quality, and performance criteria. For co-processing, ASTM D1655 outlines specific pathways, including:

• 5% co-processing of triglycerides, free fatty acids, and fatty acid esters.
• Fischer-Tropsch-derived hydrocarbons with renewable synthesis gas.
• Hydroprocessed renewable hydrocarbons with maximum feed and product percentages.

These standards provide a robust framework for scaling SAF production while maintaining the integrity of aviation fuel.

6. Co-Processing in Action

Global Trends and Success Stories Refineries worldwide are beginning to adopt co-processing as a viable SAF production method. Europe and Asia are at the forefront, with several facilities already demonstrating the potential of co-processing.

In one notable example, a European refinery achieved SAF production with minimal CAPEX investment by leveraging an existing kerosene hydrotreater and upgrading its catalyst system. Similarly, Asian markets are showing strong interest, driven by favorable policies and increasing demand for sustainable fuels.

7. The future of Co-Processing

Opportunities and Innovations Looking ahead, co-processing holds immense potential for scaling SAF production and meeting ambitious climate goals. Key drivers include:

• Policy Support: Initiatives like ReFuelEU and CORSIA provide strong incentives for refineries to invest in SAF production.
• Technological Advancements: Innovations in catalysts and process optimization will reduce costs and improve efficiency.
• Market Demand: Growing interest from airlines and corporate customers underscores the urgency of SAF adoption.

Refineries that embrace co-processing today will be well-positioned to capitalize on these trends and lead the way in sustainable aviation.

A Path to Sustainable Growth Co-processing represents a unique opportunity for refineries to align with the global push for sustainability while unlocking new revenue streams. By leveraging existing infrastructure, embracing innovation, and navigating technical challenges, the aviation industry can take a significant step toward achieving its net-zero goals.

The future of sustainable aviation fuel lies in collaboration, creativity, and commitment. Refineries, policymakers, and industry leaders must work together to scale co-processing and realize the full potential of SAF. The journey is just beginning, and the possibilities are limitless.