Bridging the gap between academic research and real-world solutions
In the pursuit of scientific advancement, the journey from theoretical research to tangible solutions is often fraught with challenges.
Written by
Emmanuel Wada Sr., PhD, P.E.
The Urgency for Sustainable Aviation Fuel
The aviation industry, a significant contributor to global greenhouse gas emissions, faces increasing pressure to decarbonize. Sustainable Aviation Fuel (SAF) offers a promising solution: a drop-in renewable fuel capable of reducing aviation's environmental footprint. Among the various pathways to SAF production, the Hydroprocessed Esters and Fatty Acids (HEFA) pathway currently stands out as the most commercially deployed and mature technology. This makes it a critical area of understanding for both industry veterans and newcomers.
Decoding the HEFA Pathway
The HEFA process utilizes esters and fatty acids found in various feedstocks, including vegetable oils, animal fats, algal oils, and waste greases. The conversion of these feedstocks into SAF involves three primary stages: pretreatment, hydroprocessing, and product fractionation. Pretreatment removes impurities, ensuring the longevity and efficiency of the catalysts used in the subsequent hydroprocessing stage. Hydroprocessing then refines the pretreated feedstock through reactions like hydrodeoxygenation and isomerization/hydrocracking. Finally, fractionation separates the resulting hydrocarbons into different fuel products, including SAF.
The Current Landscape of HEFA SAF
Currently, the HEFA pathway is responsible for the vast majority of SAF production worldwide. Announced domestic total SAF production capacity is expected to reach 2.0 billion gallons per year (BGPY) by 2030, with most of this anticipated to come from HEFA. Total announced domestic HEFA capacity (including renewable diesel) could reach approximately 9.6 BGPY by 2030. A notable trend is the increasing design of facilities with the flexibility to produce either SAF or renewable diesel (RD), allowing producers to adapt to market conditions and incentives.
Challenges and the Path Forward for HEFA
Despite its current prominence, relying solely on HEFA to meet ambitious SAF goals presents challenges. Feedstock supply is a major constraint, with multiple industries competing for the same limited resources. While some believe the 2030 goal might be achievable through HEFA alone, others caution against overreliance, emphasizing the need to develop other SAF pathways to meet the far more substantial 2050 targets. Industry stakeholders also highlight the importance of consistent policies and incentives to drive SAF production and balance it with RD production. Understanding these dynamics is crucial for industry players looking to invest and for learners seeking to grasp the complexities of the SAF landscape.
sources:
•Rosales Calderon, Oscar, Ling Tao, Zia Abdullah, Michael Talmadge, Anelia Milbrandt, Sharon Smolinski, Kristi Moriarty, et al. 2024. Sustainable Aviation Fuel State-of-Industry Report: Hydroprocessed Esters and Fatty Acids Pathway. Golden, CO: National Renewable Energy Laboratory. NREL/TP-5100-87803.
