SAF: The Future in Flight

May 31, 2024

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by Jefferson dos Santos Estevo* (Advanced Biofuels USA) On May 23, 2024, the RSB - Roundtable on Sustainable Biomaterials Association, launched a series of webinars on Sustainable Aviation Fuels (SAF). These online events feature experts from various companies connected to the topic of SAF. In total, there will be four virtual meetings aimed at enhancing understanding of the issue.

The main goal of the series is to raise awareness about the energy transition in the aviation sector and highlight the importance of mitigating greenhouse gas emissions, even though aviation currently accounts for only 2-3% of global emissions. According to a presentation by RSB Director Elena Schmidt, the key objective of the series is to "help navigate the world of sustainable aviation fuels," by clearly explaining how they work, the challenges involved, the projections for the future, and their development and use.

On the first day, the theme was SAF: The Future in Flight. The session was moderated by Hannah Walker, RSB's Director of Outreach & Engagement. The first presenter, Courtney Unruh, Director of SAF & Sustainability at Alaska Airlines, discussed the challenges of emission mitigation in the aviation sector. She explained that SAF is currently the main alternative, expected to account for 65% of emission reductions by 2050. This is followed by emission markets like CORSIA (Carbon Offsetting and Reduction Scheme for International Aviation), contributing 19%, new technologies in the sector 13%, changes in aircraft, and operational improvements such as route changes, 3%. For Alaska Airlines, the goal is to enhance all these areas to achieve carbon neutrality by 2040, with a significant focus on the use of SAF.

The second participant was Charlotte Hardenbol, Head of Sales & Marketing at SkyNRG. Her presentation focused on "What is Sustainable Aviation Fuel." SkyNRG is a producer of SAF and has been working in this field since 2011, when they supplied fuel for the first commercial flight using SAF. The company aims to help various stakeholders, including airlines, to mitigate aviation emissions by 2050, in line with the ICAO (International Civil Aviation Organization) agreement.

Hardenbol emphasized the necessity of reducing emissions in the aviation sector, especially as flight numbers increase, to prevent further rises in emissions. SAF is currently the most viable solution since other technologies, such as electric or hydrogen-powered aircraft, are still a long way off.

So far, more than 600,000 flights have used SAF, involving over 50 airlines worldwide, significantly contributing to emission reductions in the sector. The market, currently valued at 0.2 billion euros, has the potential to grow to 50 billion euros. By 2050, the target year for major international goals, could reach 500 billion euros, achieving net-zero emissions in civil aviation.

Regarding SAF production, Hardenbol explained that it can be made from various raw materials using different methods. The main types include:

HEFA (Hydroprocessed Esters and Fatty Acids): Made by vegetable oils, animal fats, used cooking oils, the most commonly used currently is recycling used cooking oil. This technology is well-developed but still faces a shortage of raw materials;
FT (Paraffinic Kerosene synthesized by Fischer-Tropsch): This pathway uses sources like urban, agricultural, and forestry solid waste biomass, as well as non-renewable raw materials like coal and natural gas. Same as HEFA, good technology, but the problem is raw materials;
ATJ (Alcohol-to-Jet): Primarily uses ethanol made from biomass. This technology is advancing and has significant production potential;
Power-to-Liquid (PtL): Involves carbon capture, with hydrogen use, to produce green and sustainable fuel. Although this technology still needs development, it has abundant raw material availability and is highly scalable.

Hardenbol highlighted that advancing these technologies and expanding raw material sources are crucial for the future of SAF and achieving the ambitious targets set for 2050.

A central point in the presentation was to better understand the sustainability of SAF. In summary, Schmidt emphasized that while SAF still emits gasses, similar to those produced by fossil fuels when burned, there is a key difference. Unlike conventional aviation fuels, produced from fossil resources from underground which release stored carbon into the atmosphere, SAF is produced using alternative raw materials, described above. So, instead of using petroleum and its derivatives, it uses other options, including agricultural and forestry residues, even municipal waste. This means that the CO2 emitted during a flight is absorbed by the biomass used to produce SAF.

At the end of the presentation, Schmidt showed data on production in Europe and the United States, revealing possibilities for growth, especially with the use of the FT and ATJ pathways. However, she explained that this growth depends on more financial incentives and national policies. Currently, the main alternative is HEFA, although production remains limited in these countries and globally.

Continuing the discussion on SAF sustainability, the final presentation was given by Arianna Baldo, RSB's director on the subject. In her words, she focused on putting the "S" in SAF, explaining how and why it can be considered sustainable. Generally, as explained earlier, the entire production chain must aim to minimize or reduce emissions. Only then can a company prove that its fuel is clean and sustainable, obtain certification, and count the emission reductions toward its goals.

In other words, for SAF to be sustainable, its production must comply with various regulations throughout the entire supply chain. This includes avoiding the use of pesticides, diesel, and minimizing emissions during transport to the airport, for example. According to Baldo, for SAF to be certified as sustainable, it must demonstrate more than a 50% reduction in emissions across its production chain. The entire chain must undergo certification processes, and the certifying company must also be accredited to ensure the process's credibility and prevent CO_² reductions double counting.

In the final moments, listeners had the opportunity to ask questions. The first question, about verification, was answered by Hardenbol. She explained the entire process of documenting the sustainability chain, demonstrating how it can be proven that the fuel is genuinely sustainable or SAF. This highlights the importance of companies like RSB for certification and ensuring authenticity.

Next, there was a question about 100% SAF flights, which Unruh explained that such flights have already occurred, but they are still in the testing phase, primarily due to safety concerns. Additionally, the limited availability of SAF poses an obstacle, even at airports that do offer SAF, which are still few in number.

Following up on the SAF availability issue, Hardenbol emphasized that besides the lack of raw materials, there are logistical problems related to fuel distribution and the absence of SAF infrastructure at many airports. This underscores the importance of models like Book and Claim, which will be discussed in another webinar in the series, to advance SAF usage even in different locations where it is available. High costs are also linked to the limited availability, from raw material collection to production. Baldo pointed out that more incentives and policies from countries or local governments are needed to promote SAF and reduce prices, which are currently very restricted.

In response to my question about the difficulties other countries, such as Brazil, face in using SAF, all panelists agreed that political incentives, lack of raw materials, and especially infrastructure for the entire production chain—from raw material collection to aircraft refueling—are significant challenges. However, all agreed that additional incentive policies are needed, highlighting a notable disparity among nations.

In summary, the webinar was highly informative, greatly enhancing the understanding of what SAF is, how it works, and the current state of its production and use, primarily in developed countries like Europe and the USA. It also addressed sustainability throughout the entire chain and explained how certifications are conducted.

You can watch a recording of the event here: https://www.youtube.com/watch?v=iUY0lKDh7WI

*Post-doctoral researcher in Political Science at the Federal University of Goias, Brazil. Fellow of CNPQ and FAPEG jeffersonestevo@ufg.br