Sustainable aviation fuel

One of the most exciting areas in the field of aviation environmental action and a cornerstone of the commitment to flying net zero is the increasing use of sustainable aviation fuel, commonly known as SAF. Haldane Dodd Executive Director, ATAG

Since the first test flight on a commercial aircraft in 2008 and the approval of sustainable aviation fuels for use in aircraft operations in 2011:

  • over 495,000 commercial flights have taken place using alternative-traditional fuel blends (see the actual number of flights here)
  • around US$ 40 billion sustainable aviation fuel forward purchase agreements have been signed by 45 airlines
  • airlines covering 34% of global passengers and 40% of global RPKs have committed to a significant proportion of their fuel uplift being through SAF in 2030.

Sustainable aviation fuel such as algae, jatropha or waste by-products have great potential for securing the sustainable growth of air travel as they can reduce CO2 emissions by around 80% over their full lifecycle.

potential reduction

Aviation is pushing for government support and investment to allow for the scale-up in supply of sustainable aviation fuel, as a key element of the commitment to fly net zero. So far, around 40 countries are implementing or considering SAF policy options.

With the right policy support, around 5.6 million tonnes (7 billion litres) of the total aviation fuel supply – representing around 2% – could be fulfilled using sustainable aviation fuel by 2025 and without further policy measures, around 6-10% of supply by 2030.

5.6 million tonnes
SAF by 2025, with the right policy support

What is sustainable aviation fuel?

Sustainable aviation fuel - which is sometimes referred as biofuel, renewable aviation fuel, renewable jet fuel, alternative fuel or biojet fuel - is usually produced from biological sources. Rather than being made from fossil fuels, they are synthesised from a wide range of sustainable feedstocks such as waste oil and fats; municipal solid waste; cellulosic waste (such as corn stalks); cover crops such as camelina, carinata, and pennycress; non-biogenic alternative fuels; jatropha; halophytes and algae.

Sustainable aviation fuel is a safe replacement for conventional (fossil-based) jet fuel.  It is almost chemically identical but is generated from feedstocks that absorb CO2 and provide a net reduction in CO2 emissions when compared to fossil fuels.

Other sources can also be considered as sustainable, such as drawing CO2 out of the atmosphere and using low-carbon electricity to make sustainable aviation fuel.

Commercial flights are currently permitted to fly with a blend of SAF and conventional fossil-based kerosene of up to 50%, to ensure compatibility with aircraft, engines and fuelling systems. The industry is working towards commercial aircraft being permitted to fly on 100% SAF in the near future.

Beginner's guide to sustainable aviation fuel (April 2023)

Key advantages of sustainable aviation fuel

Environmental benefits: SAF represents a huge opportunity for aviation to reduce its environmental impact. Today’s sustainable aviation fuel can reduce CO2 emissions by up to 80% over its lifecycle compared to conventional jet fuel, but with 100% possible in the future

Research is also underway into fuels that could even have a negative emissions lifecycle, meaning that they absorb more CO2 than they emit.

Diversified supply: SAF offers a viable alternative to conventional fossil-derived kerosene and can substitute traditional jet fuel with a more diverse geographical fuel supply through non-food crop sources.

A drop-in alternative: SAF uses the existing fuel supply and distribution infrastructure, ensuring the energy transition can take place faster compared to other options that would require a wholesale change in aviation’s systems and equipment.

Economic and social benefits: SAF could provide a solution to the volatile fuel costs that aviation is faced with. It can provide economic benefits to parts of the world (especially developing nations) that have land that is unviable for food crops but is suitable for sustainable aviation fuel feedstock growth.

Refining infrastructure is likely to be installed close to feedstock sources, generating additional jobs and economic activity. For many developing countries, SAF represents a significant economic and employment opportunity – it is estimated that the shift to SAF could result in up to 14 million jobs being created or transferred from fossil fuel energy jobs.

14 million
potential jobs in SAF
possible new SAF production facilities throughout the globe

We anticipate that there will be an increase in the use of SAF by mid-century as part of a wider shift in aviation’s energy sources, including low-carbon electricity and green hydrogen. It is likely that aviation will need between 330-445 million tonnes of SAF per annum by 2050.

Key challenges to deployment

The extensive commercial flights and testing of SAF in numerous demonstration flights by 50+ different airlines has shown that the barriers to increased SAF deployment are economic and political, rather than technical.

These challenges include:

  • ensuring an adequate supply of feedstock and low-carbon energy, enabling sufficient quantities of SAF to be produced to make them commercially viable
  • ensuring that the cost of SAF is competitive, in order to compete with petroleum-based jet fuel
  • ensuring that aviation receives an appropriate allocation, relative to other forms of transport, of available sustainable feedstocks
  • ensuring that governments implement appropriate policy mechanisms to allow the SAF industry to scale up and deliver the economy of scale benefits, including incentivising the use of feedstocks for aviation as a priority over other sectors
  • reducing the risk for private investors, to enable greater investment in SAF and an increase in production
$1.0-1.45 trillion
required in investment
of the current annual investment in fossil fuels and gas
  • ensuring all aircraft in the fleet are compatible with the use of 100% SAF – expected to be complete around 2030. Until then, the 50% blend limit of SAF and conventional jet fuel will remain.

“Book and claim” – helping to scale up deployment

Book and claim is a mechanism that will help scale up SAF deployment efficiently, thereby accelerating the industry’s decarbonisation efforts. It will address the initial limited supply of SAF versus the growing demand and will enable airlines to purchase SAF without being geographically connected to a SAF supply site.

Before SAF becomes fully available globally, it will be more economically efficient to produce it in certain parts of the world. Airlines wishing to take part in the early adoption of SAF, therefore, may wish to support SAF production sites in different parts of the world even if they do not fly to those locations.

With book and claim, airlines can buy the SAF they need where it is most competitively produced and obtain the CO2 emissions credits.  The SAF can be incorporated into the distribution systems of local airports located close to the SAF plant. Other airlines using that airport will use the physical SAF, but only the purchasing airline will receive the credit for having purchased it and supported the scaling up of SAF.

Fueling net zero for air transport

In October 2021, the air transport industry committed to achieving net zero carbon emissions by 2050. ATAG was instrumental in bringing the sector together to make the commitment and coordinated the signing of a declaration.

Sustainable aviation fuel will play a very important role in flying net zero. This is explored in ATAG’s 2021 Waypoint 2050 report, which was the culmination of several years of work among experts, led by ATAG, to explore how a long-term climate goal for aviation could be reached.

As part of the Waypoint 2050 additional analysis, ATAG worked with the consultancy ICF to further explore the role of sustainable aviation fuel. An in-depth analysis was carried out to assess how aviation can deploy sufficient sustainable aviation fuel to meet its climate ambitions. The findings are provided in the Fueling Net Zero report (2021).

Fueling net zero report (September 2021)

The report explores the pathway to ensuring that sufficient sustainable aviation fuel is available, evaluates the various feedstocks and technologies required, as well as estimating the necessary investment and cost to airlines. A massive scale-up in the production of sustainable aviation fuel will be essential for the continued decarbonisation of aviation. Infrastructure will need to be built, commercial partnerships will need to be developed and processes established.

Fueling Net Zero explains that rapid technology developments in the future will reduce the price of sustainable aviation fuel. In addition, improvements in supply chains, production processes and the installation of carbon capture and sequestration will increase the carbon reduction achieved by sustainable aviation fuel.

It also indicates that aviation will require 5,000 – 7,000 renewable fuel refineries by 2050. The sustainable aviation fuel industry will have to leverage feedstocks across almost every country, improving energy security, independence, and resilience for many nations. These will be closer to the sources of feedstocks and the airports to which sustainable aviation fuel will be delivered, across all countries, rather than the more concentrated energy system that we have today.