Sustainable Aviation Fuel (SAF) has become an increasingly popular topic in the industry and as this technology is gathering momentum, many people still have questions about it. So, here’s everything you need to know about SAF ahead of the Sustainable Skies World Summit, as we answer the most talked about questions.
7. What is SAF?
Sustainable Aviation Fuel is an alternative to fossil fuels, typically made from plant and animal materials. Compared to traditional jet fuel, SAF reduces carbon emissions by up to 80%, depending on the source of material, method of production and the overall supply chain.
Other fuels being researched and tested include Lower Carbon Aviation Fuels (LCAF) and Zero Emission Fuels (ZEF)
Lower Carbon Aviation Fuels (LCAF)
- LCAFs are bio-jet fuels that could act as a complementary measure to SAF.
- The overall CO2 emissions savings vary. Currently, these fuels must be blended with kerosene for certification reasons but also because there is not enough production to meet fuel demand.
- Recommendations to accelerate this sector call on policy makers to support initiatives delivering at least a 50% reduction in CO2 emissions and have a significant supply of feedstock in order to create LCAF at a big enough scale.
Zero Emission Fuels (ZEF)
- ZEFs are also known as carbon-neutral fuels, meaning they produce no net-greenhouse gas emissions or carbon footprint.
- They are typically made using carbon dioxide (CO2) as a feedstock, which involves capturing and converting CO2 into a viable aviation fuel such as liquid methanol.
6. Is SAF the same as biofuel?
SAF is generally the preferred term in aviation as it encompasses the scope of materials used to produce it, including both biological and non-biological resources. Biofuels are not necessarily always produced sustainably, and therefore the term is avoided when discussing aviation-specific fuels. Biodiesel in particular is not suitable for use in aviation.
5. Who makes Sustainable Aviation Fuel?
Currently, some of the top producers of SAF include Neste, World Energy, Gevo, Alder Fuels and SkyNRG. In December 2022, the UK government announced funding for 5 UK-based projects to produce SAF, some of which focus on converting household waste into sustainable fuel.
4. How does Sustainable Aviation Fuel reduce emissions?
Compared to conventional fuels, burning SAF fuel reduces the amount of CO2 emissions across its lifecycle as well as other impurities such as sulphur dioxide.
‘One of things that really confuses people is that when we consume SAF in the engines we still produce a form of CO2, but it’s obviously made from biogenic sources or from captured CO2’ … ‘So in terms of increasing net CO2 in the atmosphere, SAF doesn’t do that. It’s the timeline over which we are recycling that carbon which is important’
Leigh Hudson, Environmental Manager – Carbon Management, British Airways (SSWS22 Webinar)
3. Is Sustainable Aviation Fuel actually sustainable?
SAF provides a significant reduction of CO2 emissions, but it is a drop-in solution meaning most current aircraft can only use a 50% blend of SAF and normal jet fuel. 100% SAF flights have been tested but they require technological modifications to the aircraft first.
2. Who uses Sustainable Aviation Fuel?
Based on recent data, more than 50 airlines are using or have trialled the use of SAF, with a total of over 450,000 flights to have taken to the skies (IATA). As it stands, the biggest barriers preventing more widespread usage of SAF is the cost and availability.
1. Is Sustainable Aviation Fuel more expensive?
Generally, SAF is far more expensive that traditional fuels, often double the cost. This is the main reason why many airlines and carriers have been reluctant to adopt it. The cost of production partnered with the low demand is what is keeping the overall cost of SAF so high, with many citing the need for government incentives and investment as the solution.
‘SAFs are wonderful, they’re great, if you can get it. We wholeheartedly support any effort from government incentives and through the market to ramp up as fast as possible the production of these game changing sustainable aviation fuels.’
Sean Bradshaw, Technical Fellow – Sustainable Propulsion, Pratt & Whitney (SSWS22 Webinar)
The Bigger Debate: SSWS25 Agenda
To accommodate for the increased predicted numbers of flights and passengers in 2050, a huge amount of SAF will need to be produced. So, how does the industry do this?
Is SAF the right strategy? Is hydrogen or electric a better investment?
The discussion around SAF and the road to Net Zero more generally will be a key topic of conversation in a number of panel sessions planned for SSWS25.
Join the conversation at the Sustainable Skies World Summit, 14-15 May 2025 at Farnborough International, UK
At the moment, much of the discussion surrounding sustainable aviation is centred on Net Zero targets. The specific roadmaps differ from country to country but on the whole, they are predominately set on reducing carbon dioxide (CO₂) emissions by 2050.
Many argue that these measures do not go far enough and that the real goal should be focused on True Zero. How the industry plans to reach these targets, through alternative technologies and addressing the non-CO₂ effects, will be introduced in this blog and further discussed at the Sustainable Skies World Summit in May 2024.
What is the difference between Net Zero and True Zero?
Net Zero quite simply is the target of negating the amount of greenhouse gases produced by human activity by reducing emissions and removing carbon dioxide already in the atmosphere. The UK Government has set out strategies to decarbonise all sectors of the UK economy in order to meet Net Zero targets by 2050.
In comparison, True Zero considers both CO₂ and non-CO₂ effects and is what many in the industry believe should be regarded as the true goalpost in sustainable aviation.
What are the Non-CO₂ Effects?
Although carbon dioxide emissions are the most frequently talked about, they only make up a small percentage of the issue. Emissions from aviation specifically also include nitrogen oxides (NOx), water vapour and contrails, particulates, carbon monoxide, unburned hydrocarbons, and sulphur oxides (SOx). These could potentially have a 2–3 times greater climate change impact than CO₂ alone (Roland Berger).
Non-CO₂ emissions have frequently been overlooked with much of the attention being placed on carbon emissions alone, but as the industry looks beyond Net Zero 2050 targets it must broaden its scope and truly address how we can achieve zero emission flight.
What is Zero Emission Flight?
Flying without producing any emissions is a difficult challenge. Zero emission flight ultimately requires an alternative source of power to conventional jet fuel and the industry is working tirelessly to research and develop new solutions that utilise hydrogen, electric, solar and hybrid technologies all with the hope of delivering truly zero emission flight.
The leading technologies showing potential at the moment are electric and hydrogen. Electric vertical take-off and landing aircraft (eVTOLs) could offer a zero emission solution but currently only for short distance flights. Learn more about the role of eVTOLs here.
Hydrogen on the other hand, could provide the answer to truly zero emission flight, with many leading aerospace companies paving the way with research and development.
Hydrogen in Focus
Hydrogen has been safely used in the industry for many years and could play a major role in the future of sustainable flying. Firstly, hydrogen can be combusted to create electrical power for battery-powered aircraft such as eVTOLs. Secondly, hydrogen can be used as a fuel itself, replacing the need for conventional jet fuel and sustainable aviation fuel in the long run.
The latter option, whilst boasting the most potential, also creates the biggest challenge. There are numerous engineering challenges to consider with hydrogen technology but by far the most pressing is the fuel density of hydrogen. Simply put, to use hydrogen as a direct fuel you would need much bigger fuel tanks than what is currently used on commercial airliners. This will require a fundamental shift in how aircraft are designed.
To compare this with the use of Sustainable Aviation Fuels (SAF), which currently require no change to the aircraft itself, hydrogen is a huge long-term investment and something not everyone is yet fully behind. With numerous technologies being developed and tested, it has become difficult for investors to know which path to back.
Short-Term vs. Long-Term Investment
To achieve Net Zero targets and ultimately True Zero, there will likely not be a single solution, but instead a combination of changes to technology, fuels and operations. The short-term measures we make will play just as important role and these include maximising the usage of SAF, minimising fuel burn through operation efficiency and carbon removal measures. SAF is one of the leading developments and currently can cut carbon emissions by 65% (source: IATA). Learn more about SAF here.
However, to achieve absolute zero emission flight we must go further. A revolution in either sustainable fuels or technology will have the greatest impact and these long-term measures will likely require a shift in how we view flying and perhaps lead to a big change in aircraft design.
As it stands, many of the short-term measures only concern reducing CO₂ emissions to meet Net Zero targets. To take this further, considering non-CO₂ emissions and reaching True Zero, longer-term strategies and bigger changes will be required.
Going Beyond Flight
To reach True Zero, zero emissions in the skies also need to be reflected on the roads and other forms of transport. To achieve this across the industry, we must go beyond the actual flight and consider operational and airport emissions too. This includes collaborating with other transport industries and analysing the full supply chain. Read more about Operation Efficiency.
Leading Voices
ZeroAvia, ‘Hydrogen-electric is the best option for long-term transition to clean aviation’
Airbus’ ZEROe Project, ‘Airbus’ ambition is to bring to market the world’s first hydrogen-powered commercial aircraft by 2035’
Rolls-Royce, ‘Pioneering hydrogen engine combustion’
Roland Berger, ‘The Roadmap to True Zero’
IATA, ‘Liquid hydrogen as a potential low-carbon fuel for aviation’
What to expect at SSWS24
The conference programme at this year’s Sustainable Skies World Summit will feature sessions dedicated to zero emissions, this includes the exploration of non-CO₂ effects and the impact of zero emission aircraft.
Hear from the leading experts about what projects and technologies are worth investing in and how collaboration across the sector is performing. Join the conversation at SSWS24!
The conversation will also continue at this summer’s Farnborough International Airshow, with many of the sessions from SSWS24 feeding directly into the sustainability theme at FIA2024.
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Voyager aircraft powered by 43% Sustainable Aviation Fuel (SAF) flies over North Sea.
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The aircraft used a blend of traditional fossil fuels and SAF such as cooking oil.
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Flight marks the launch of a new aviation Net Zero Carbon roadmap for commercial aviation.
The Royal Air Force has successfully completed a Voyager air-to-air refuelling flight, powered by an approximately 43% blend of Sustainable Aviation Fuel (SAF).
Flying from RAF Brize Norton, over the North Sea and via Farnborough on its return home, the Voyager aircraft also undertook air-to-air refuelling with Typhoons, as part of planned training.
Made from waste-based sustainable feedstocks, such as used cooking oil, SAF reduces lifecycle carbon emissions by up to 80% compared to traditional jet fuel and will be key to reducing the RAF’s reliance on global supply chains and fossil fuels, while improving operational resilience.
This significant moment follows a series of recent milestones achieved by the RAF towards a sustainable aviation future, including the world first RAF Voyager flight fuelled by 100% SAF.
RAF Images: Credit: Crown copyright
Defence Minister, Baroness Goldie said:
“Greater use of alternative and sustainable fuel can only lead to positive outcomes for Defence, the United Kingdom, and our collective endeavour against climate change.
“This is not an easy undertaking by the RAF, but time and again we see that by working collaboratively with our partners across industry we can achieve crucial transformation.”
Part of a two-day industry led conference – Sustainable Skies World Summit – the flight marks the UK aviation industry publishing its updated aviation Net Zero Carbon roadmap outlining how commercial aviation will become more sustainable and commercially viable.
The annual event, hosted at Farnborough International Exhibition & Conference Centre, brings together various partners from industry to showcase the latest developments in sustainable aviation technology and support efforts moving towards the implementation phase of meeting its net zero commitment.
Supporting the RAF’s ambitions to be Net Zero by 2040, the Voyager flight was part of an existing task from the Chief of the Air Staff to gather the required data to inform the longer-term transition away from fossil fuels.
The RAF has identified that using SAF and alternative aviation fuels will be critical for the future operational capability of the RAF and wider military aviation.
The UK’s SAF programme is already one of the most comprehensive in the world and supports our vision to set the UK up to be a global leader in the development, production, and use of SAF.
Supporting the Prime Minister’s priority to grow the economy, new aviation technologies and fuels provide huge opportunities for economic growth, delivering jobs and prosperity across the country.
RAF Images: Credit: Crown copyright
Chief of Staff Support and Chief Engineer, Air Vice-Marshal, Paul Lloyd said:
“The continued success of sustainable aviation fuel is reassuring to see. If we are to achieve our net zero goal by 2040 then exploiting these technologies is going to be an enormous but worthwhile endeavour.
“Despite the challenge, the benefits of reducing our reliance on traditional supply chains and fossil fuels outweigh it.
“The RAF is proud to be leading in this area and I welcome the announcement introduction of commercial uses of SAF.”
Providing increased reliability and range, the Voyager aircraft gives the RAF an enhanced capability in support of troop mobility, the movement of military assets, and supports UK air defence.
With a payload of 43 tonnes of freight and 291 seat passenger capacity, plus an aeromedical evacuation capability, Voyager also delivers flexibility in air mobility to the UK Armed forces in support of military and humanitarian operations.
During the two days of the Sustainable Skies World Summit, the Jet Zero Council (JZC) – a partnership between industry and government with the aim of delivering at least 10% SAF in the UK fuel mix by 2030 and zero emission transatlantic flight within a generation – will also meet. The Jet Zero Council is driving the ambitious delivery of new technologies and innovative ways to cut aviation emissions.
The SAF for the flight was sourced by International Airlines Group (IAG), and supplied by bp.
