Understanding the Sustainable Aviation Fuels (SAF) for the Greener Aviation

Understanding the Sustainable Aviation Fuels (SAF) for the Greener Aviation

Introduction

In Nov. 2023, the 1st trans – Atlantic flight using 100% SAF departed from London to New York operated by Virgin Atlantic with regulatory approval from Britain's Civil Aviation Authority. Previously, other commercial airlines that have powered on to the SAF had been on shorter journeys and in up to 50% blends with aviation turbine fuel (ATF, the conventional fuel) as per regulatory limit.

The first commercial test flight powered with SAF (20% blend of biofuel, made from coconut and babassu) flew was from London to Amsterdam by the Virgin Atlantic in Feb. 2008.

If the aviation sector has to align itself with the goals enshrined in the Paris Agreement of 2015 and curb the global warming, the industry needs to transit completely from fossil fuels in long – term. One of the ways, the sector is seeking to replace ATF is by scaling – up the adoption of SAF.

The aviation sector been amongst one of the carbon – intensive sector, contributes 2% of all carbon emissions produced annually and 12% of all CO2 emissions produced by transportation sector as a whole. According to studies from International Council on Clean Transportation, on average, the global passenger aircraft emitted 90 g CO2 per RPK (revenue passenger km) in 2019.

In general, SAF aids to reduce the climate impact of the aviation sector.  Compared with other sectors, aviation is relatively a small contributor to the global GHG emissions. However, it is recognized as one of the fastest – growing and the number of flights is expected to grow at an alarming rate over the next decades.

Challenges to decarbonization in the aviation sector

Airlines and startups in SAF space are still in nascent stages of testing breakthrough technologies including multiple approaches towards green hydrogen. It is due to the unique challenge and inherent to the aviation sector as compared to other modes of transport. Differently from the roadways and railways, which have mostly made significant progress towards electrification of the power shaft, whereas in the aviation sector, 80% of emissions are long – haul flights that cover a distance over 1,600 km and for which there are no commercially – viable alternative to the ATFs.

Compared with automobile and power generation sector, where significant progress has been made towards decarbonization, the aviation sector is still in the experimental days of commercializing the new fuel technology.  It is worth to note that, the electric batteries at best have a role to play on shorter, regional routes and urban travel and airlines are making these investments.

Whereas, the critics are of the opinion that the aviation industry has been too slow and late – mover to decarbonize and seek climate solutions, but concede that it is a tough task to formulate net – zero strategies for the aviation sector, because of its unique safety and regulatory requirements.  

On the positive side, the airlines have completed the test – flights with SAF and deals with SAF producers have started to accumulate. 

In 2022, American Airlines — one of the largest airlines globally, finalized the deal with biofuel company Gevo to procure 500 million gallons of SAF over 5 years as a part of its net – zero carbon directive. Thus, the American Airlines became the first airline globally to receive validation from Science Based Targets initiative (SBTi) for its intermediate GHG emissions reduction targets.

Sustainable Aviation Fuel (SAF)

SAF is an umbrella term for energy sources (which are non – fossil derived/ biofuel fuels) and/or replacement fuel made from raw materials to decarbonize the aviation industry.

Alternatively, they may be called as ‘aviation biofuel’, ‘bio – jet fuel’ or ‘bio – aviation fuel (BAF)’.

It is a chemically indistinguishable from ATFs, but the production process is significantly different and greener than traditional fuels.

Depending on the feedstock and technologies (solid biomass using pyrolysis processed with Fischer – Tropsch process (FT-SPK), alcohol – to – jet (ATJ) process from waste fermentation, synthetic biology through a solar reactor, etc.) used to produce the SAF, it still produces fewer emissions, but overall the reduction of “lifecycle GHG emissions” is drastically as compared to the conventional jet fuel.

However, some emerging SAF pathways even have a net – negative carbon footprint such as the integration of carbon capture, utilization and storage (CCUS) to achieve net – negative lifecycle emissions.

Hence, the ability of SAFs to reduce the carbon intensity makes it an important instrument towards aviation sector’s net – zero goals.

Figure: Lifecycle of SAF

Sources/Feedstock of SAF

The most common feedstock for the production of SAF are derived from plants and/or animal materials, municipal waste and agricultural residues. The feedstock for the production of the SAF include:

Generally, the SAF is produced through used cooking oil and agricultural waste, which is widely viewed as the aviation industry best option for cutting – down the GHG emissions.

The SAF undergoes the strict testing at U.S. Federal Aviation Administration Clearinghouse to meet the standards required for ASTM (American Society for Testing and Materials) D4054 certification from ASTM International.

They are certified as being sustainable by a third-party organisation such as Roundtable on Sustainable Biomaterials (RSB) “ICAO CORSIA”.

Significance of SAF

According to the International Air Transport Association (IATA), the SAF could contribute around 65% of the emission reduction needed by the aviation sector to reach net – zero by 2050. This will require a massive scale – up the production in order to meet demand.  It has the potential to decarbonize medium – and long – haul flights which generates the most emission and could extend the life of older aircraft types by lowering their carbon footprint.

In addition, there are various combinations available to decarbonize the aviation sector such as elimination of emissions at the source, offsetting and carbon capture technologies, etc.

The largest acceleration is expected in the 2030s as policy support becomes global, SAF becomes competitive with fossil kerosene, and credible offsets become scarcer.

According to the International Energy Agency (IEA) forecast, the SAF production should expand from 18 to 75 billion litres between 2025 and 2040, representing an increased share of SAF from 5% to 19% in the aviation sector. However, according to the technical review conducted by the U.S. Department of Energy, the SAF are is more expensive than fossil jet kerosene taking taxation and subsidies into account as of 2020.

Advantages

Following are some the direct and additional (indirect) benefits from the adoption of SAF across the aviation sector:

However, despite the significant direct and indirect advantages aiding the adoption of SAF, the critical challenge still remains to figure – out the “sustainable” pathways to increase the supply of SAF while lowering the cost.

Disadvantages/Criticism of SAF

Following are major concerns related to upscaling of the SAF:  

  1. High cost: It is typically 2 – 4 times more expensive than ATF.
  2. Limited resources and feedstock availability: For example, the first commercial test flight powered from SAF in 2008 by the Virgin Atlantic from London to Amsterdam, if it was to be operated on 100% coconut oil (ingredient of SAF) have consumed 3 million coconuts which have meant entire global coconut crop supply would be needed to produce the coconut – derived SAF.
  3. The current infrastructure isn’t well – developed, which hinders the scaling up of SAF production & its availability in the market.
  4. Certification process: The certification process for SAF involves stringer quality & sustainability criteria, which can be complex & time – consuming. The lack of globally recognized standards further complicates the certification process.
  5. Cascading effects related to Sustainability: With upscaling of SAF, it is predicted that to cultivate more biomass crops will lead to substantial deforestation and threaten the fragile food security.

Due to these challenges, airlines looking to cut their GHG emissions further faces two hurdles:

  1. Many airports don't a steady readily available supply of SAF to fuel the planes.
  2. If they do, the cost is considerably higher as compared to ATFs.

 Policy initiatives for adoption of SAF

  1. During the 41st International Civil Aviation Organization (ICAO) Assembly in South Korea (2022), the Long Term Global Aspirational Goal (LTAG) was adopted for international aviation of net – zero carbon emissions by 2050 in support of UNFCCC Paris Agreement. 
  2. The technical analysis conducted by the ICAO highlight that SAF has the greatest potential to reduce CO2 emissions from the international aviation market. Hence, the ICAO is working to facilitate SAF development and deployment through globally – accepted environmental Standards for SAF such as Carbon Offsetting and Reduction Scheme for International Aviation CORSIA which includes methodologies to allow aircraft operators to reduce carbon offsetting requirements through the use of SAF and Lower Carbon Aviation Fuels (LCAF).
  3. U.S.: The U.S. Inflation Reduction Act of 2022, introduced the Fueling Aviation's Sustainable Transition (FAST) Grant Program under the Department of Transportation which aim to provides USD 244.5 million in grants for SAF – related "production, transportation, blending, and storage”, along with financially incentivising the uptake of green hydrogen technology.
  4. EU: In 2023, the EU agreed to decarbonize air travel with the world longest green fuel mandate for aviation called as ReFuelEU aviation initiative. The new rules are set to enquire aviation fuel suppliers to supply a minimum share of SAF at EU airport starting at 2% of overall fuel supplied by 2025 This will rise to 6% by this end of decade, before climbing to 70% by 2050. The measures also require aircraft operators departing from EU airports to refuel only with the fuel necessary for flight to avoid emissions related to extra weight or so called "tankering" - when operators deliberately carry excess fuel to void refueling with SAF. Airports meanwhile will need to make sure their infrastructure is fit for purpose when it comes to distributing the SAF.

Significant Industry – led initiatives to boost SAF adoption

  1. In Sep. 2008, Sustainable Aviation Fuel Users Group (SAFUG) was formed by world’s 25 leading airlines (representing 33% of commercial aviation fuel demand), aerospace manufacturers (Boeing, Airbus and Embraer), fuel service providers (Honeywell UOP), and environmental NGOs such as Natural Resources Defense Council (NRDC) and World Wildlife Fund (WWF). It focuses on accelerating the development and commercialization of SAF in the aviation sector.
  2. In February 2023, United Airlines & 5 corporate partners (Air Canada, Boeing, GE Aerospace, JP Morgan Chase and Honeywell) launched USD 100 mn venture capital fund “United Airlines Ventures Sustainable Flight Fund" to invest in startup & technology developing and expanding the availability SAF.
  3. In 2021, 60 organization across airlines, transport and cargo industries signed 2030 Ambition Statement under the World Economic Forum's Clean Skies for Tomorrow Coalition – whose mission is to accelerate the deployment of sustainable aviation fuels (SAF) – has achieved a milestone on the path to net – zero emissions by 2050, by working together to power global aviation with 10% SAF by 2030.

Conclusion

The decarbonization of the aviation sector is a crucial pathway to move ahead towards low carbon economic model and sustainable and climate – resilient future.

Thus, the initial pivot to SAF would likely rely mainly on bio – based aviation fuels, but that they would eventually be replaced more sophisticated power - to - liquid fuels or e – fuels.

Probably in the long – run, there would be a sustainable and optimized way of sustainable energy, but in the transition, the fastest way is to scale – up  adoption of the SAF.

 

It's fantastic to see such dedication towards #decarbonization and #sustainableaviation! 🌍✈Remember, as Leonardo da Vinci once said, "Once you have tasted flight, you will forever walk the earth with your eyes turned skyward." Imagine the endless possibilities when we combine this passion for flight with sustainable practices. Excitingly, we're also venturing into a groundbreaking journey with a sponsorship opportunity for the Guinness World Record of Tree Planting, aiming to inspire further green action globally! 🌳 Check it out here: http://bit.ly/TreeGuinnessWorldRecord

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