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Synthetic and Sustainable Aviation fuels (SAF)

A big push has been to increase the efficiency of aircraft engines, mainly to make them go faster, to fly higher and use less fuel. Now a new concern has come to the fore, that of environment.


We have to use as little fuel as possible, create as little CO2 as possible and think about mitigating some of the other non-CO2 effects of air transport. Aviation is commonly seen as one of the sectors that will pose the biggest decarbonization challenge. Given that the sector is expected to grow at an annual rate of 4% until 2050, it can be expected that the resulting emissions will have an increasing climate impact. However, compared to road traffic, air transport has different technical limitations that prevent it from adopting electricity or hydrogen-based decarbonisation in the near term.


But on top of that, we’ve seen, coming to the fore, whole areas like electric propulsion or partial electric propulsion, so-called hybrid propulsion, where we combine traditional engines with batteries with electric motors and can then make some very serious dents in the carbon footprint of travel.


The long lifecycles of aircrafts and development time of aircraft engines complicate the need for a fast and widespread transition to new, low-carbon technologies. New infrastructure and globally uniform standards would be required to achieve this transition and the adoption of new technologies. The aviation sector will not be able to sustain a slow and gradual 20-year shift to new engine designs powered by electricity or hydrogen if it wants to start decarbonising in the near future.


The industry is researching new alternative fuels that can be virtually no carbon or net zero carbon. So, in the case of hydrogen, no carbon, there’s no hydrogen in, no carbon in the fuel. So, if you burn hydrogen and it burns very nicely and very fast and very hot, you can propel an aircraft engine with a gas turbine like today, without leaving any CO2 behind it all. Or, you can put it through a hydrogen fuel cell, create electricity and drive in electric mode. We got those two options.


Therefore, to limit and eventually decrease carbon emissions, consideration will need to be given to synthetic fuels that are compatible with existing technology, infrastructure and regulation. Fuels fulfilling this requirement are known as ‘drop-in’ fuels as they can simply be dropped into the existing systems.

The two main drop-in fuel types suitable for aviation are biofuels and synthetic fuels. Synthetic fuels for aviation are produced through a power-to-liquid (PtL) process which, when powered by renewable energy, can result in a carbon-neutral, drop-in fuel for the aviation sector. The transition to synthetic fuels could start by gradually increasing the ratio of synthetic fuel to fossil fuel as the existing infrastructure and aircrafts adapt.


For synthetic aviation fuel, that’s really about taking carbon out of the atmosphere. Carbon dioxide, capturing it from the atmosphere. Producing hydrogen, using green electricity, infusing those two back together to make a new fuel. And then yes, you burn it and you let the CO2 back out, but that cycle is net zero.


Given their supply levels, biofuels could have an advantage over synthetic fuels in the short
term, but synthetic fuels could be favourable in the long term. Since fuel types will always be subject to fuel standards, they must be 100% compliant with the relevant standards if they are to achieve successful market entry. The existing regulations already allow for a 50/50 blend of synthetic fuel with conventional jet fuel (kerosene). However, the certification of new synthetic fuels requires a large volume for testing, which can be a challenge for producers developing fuels for research and development (R&D) purposes.

Fuel costs are one of the most important items in an airline’s cost structure, which is perhaps the most significant barrier for synthetic fuels. To be competitive in the market, synthetic fuels have to be equal with or below the cost and the performance level of conventional fuels. However, due to synthetic fuel’s more intricate production process, they come at a higher cost, estimated at between EUR 2.26 and EUR 3.25 per litre compared with around EUR 0.40 to EUR 0.60 for jet fuel.

The barriers described above prevent significant growth in synthetic fuel demand, thus hindering the economies of scale needed to lower synthetic fuel prices. This indicates that there is a need for political strategies, frameworks and measures that promote and guide the uptake of synthetic fuels. The main costs in synthetic fuel production are the energy and capital costs. An instrument that could reduce uncertainty for synthetic fuel production is a guaranteed price for these fuels, similar to that specified for renewables in the German Renewable Energy Sources Act (EEG).

A further political measure could come in the form of incentives to develop synthetic fuels,
which would help the industry to move towards large-scale commercialisation through
economies of scale. State aid through loan guarantees or subsidies to key R&D areas, such
as hydrogen production for synthetic fuels, could encourage further private investment by
lowering net production costs and investment risk. This approach was demonstrated by the
EU REFHYNE project that provided half the cost of the world’s largest electrolyser, which
produces 1,300 tonnes of hydrogen per year (one of the main inputs of synthetic fuels) in
Wesseling, Germany.

Political measures to incentivise consumption of synthetic fuels will perhaps be the most
important factor. One possibility is a carbon price, which is already implemented under the
European Emissions Trading System (EU-ETS), although it would require higher prices and
fewer free allowances to the aviation sector to be effective. Another instrument could be
taxation of fuels or, conversely, the reversal of energy tax exemptions for aviation fuels.
Compulsory blending quotas should also be considered, but could prompt logistical issues.
On the other hand, green certificates would separate the physical use of synthetic fuels and
the monetary support, so overcoming the logistical issues of quotas and allowing gradual


Project FIERCE fuels the future of synthetic jet fuel generation

Since 2008, the Air Force has used alternative fuels, known as sustainable aviation fuels (SAF), that require blending with traditional fossil fuels. Most of these alternative fuels require refinement or blending by large refineries. In recent years, energy companies, engine/aircraft manufacturers and airlines have come together to explore new fuel synthesis technologies that would not require blending with fossil fuels.


Beginning in fall 2021, as part of the Chief of Staff of the Air Force’s Blue Horizons Fellowship, Project FIERCE partnered with the Air Force Research Laboratory, AIR COMPANY and the Hsu Educational Foundation to create and test a fully synthetic “drop-in” replacement jet fuel from captured carbon dioxide and water. The most recent round of testing confirmed it as the first fuel made entirely from carbon dioxide emissions that matches the properties and performance of Jet A-1, and contains all necessary components of jet fuel, including aromatics.


This synthetic jet fuel, distributed under the name AIRMADE SAF is net carbon neutral. It requires as much captured carbon input as is emitted when the fuel is burned, but rather than contributing additional emissions, it’s recycling.


The Department of Defense is largely tied to the commercial energy and fuel markets, both domestically and abroad. A complex system of pipelines, ships, trucks and aircraft ensures fuel is delivered to bases. However, many areas of operation cannot always easily access the supply chain and fuel storage is limited in capacity. With this challenge in mind, Project FIERCE’s proof of concept explored the idea of on-site fuel generation. For now, just a few gallons can be produced in a day, but as this technology scales, forward bases could benefit from diversified supply, or operate independently without fuel resupply requirements.


The unmanned flight test team at the Hsu Educational Foundation executed the first flight demonstration in July with the 100% synthetic jet fuel. This collaboration between the Air Force and the Hsu Educational Foundation is a public-private partnership that is accelerating dual-use technology.


Sustainable Fuel Market

Sustainable aviation fuels (SAF) are defined as renewable or waste-derived aviation fuels that meets sustainability criteria


The sustainable aviation fuel market is projected to grow from USD 219 million in 2021 to USD 15,716 million by 2030, at a CAGR of 60.8% during the forecast period. The aviation industry is keen on bringing down the carbon footprints to achieve a sustainable environment and meet the stringent regulatory standards on emissions.


Alternative solutions, such as improving aero-engine efficiency by design modifications, hybrid-electric and all-electric aircraft, renewable jet fuels, etc., are being adopted by various stakeholders of the aviation industry.


However, out of these solutions, adoption of sustainable aviation fuels such as e-fuels, synthetic
fuels, green jet fuels, biojet fuels, hydrogen fuels is one of the most feasible alternative solutions
with respect to socio and economic benefits when compared to others, which contributes
significantly to mitigating current and expected future environmental impacts of aviation. In addition, airlines across the entire aviation industry are expanding their commercial fleets, due to rise in air travel These large and growing fleets are propelling the demand for the sustainable aviation fuel as a near to mid-term solution for reducing GHG emissions.


COVID-19 impact on the Sustainable Aviation Fuel Market

COVID-19 has taken a colossal toll on the world’s economic activity, with individuals, organizations, governments, and businesses having to adapt to the challenges of the crisis. Air travel restrictions across various regions for both domestic and international flights have led to inactive fleets across the globe. Like many other sectors, the sustainable aviation fuel market is also disproportionately impacted by the COVID-19 pandemic due to delays in the production activities across various industries. In addition, many older, less efficient airplanes that are parked as part of the contraction will not return to service. However, much of the industry will likely defer in acquiring new aircraft containing technology improvements until demand is stronger, the solvency of the carriers is assured, and the price of jet fuel exerts  pressure to add fuel-saving evolutionary technologies to the fleet .


Opportunity: Drop-in capability of SAF increases its demand to reduce carbon footprint

Sustainable aviation fuel, when blended with petroleum-based fuel, is fully fungible drop-in fuels.
These fuels are also known as synthetic fuels, renewable jet fuels, e-fuels, green fuels, conventional biojet fuel, and alternative jet fuels depending on the processes, technological pathways and feedstocks used in the production. These fuels are not treated differently than current fuels from petroleum and can use the airport fuel storage and hydrant systems, saving money on infrastructure costs. The continuous efforts to use existing depreciated equipment and infrastructure or coprocessing with other streams can potentially be an approach to reducing capital costs. A drop-in fuel is deemed to be equivalent to conventional jet fuel and can be used in current engines and infrastructure without any modifications. These requirements are essential for safety, general usage, and reduction of carbon footprint in the aviation industry.

Challenge: High cost of SAF increases operating cost of airlines

The airlines cannot meet their self-imposed targets for reducing GHG emissions based on engine
and flight improvements alone—they need SAF. Fuel cost is a significant fraction of operating costs. SAF, even though made from the waste and the feedstocks that are available for very low cost, requires advanced and expensive technological pathways. SAF is more expensive than petro-jet, given that new production capacity has to be deployed. SAF will not be widely available because production capacity will be built to contracts, not as a commodity, at least in the first decade or so.

New biofuel factories take time and money to build, driving up the price of their offtake once they get online and hampering their ability to reach the critical mass of profitability.


Recent Developments

In August 2020, Gevo, Inc. entered into a binding renewable hydrocarbons purchase and sale
agreement with Trafigura Trading LLC, a wholly-owned subsidiary of Trafigura Group Pte Ltd.
The contract will enable Trafigura to supply SAF to both the US and international customers
whose interest is growing in low-carbon jet fuel.

In June 2020, Hypoint, Inc. was awarded a contract by Urban Aeronautics, Inc., a leader in
VTOL aircraft, to provide zero-carbon hydrogen fuel cell technology for the CityHawk eVTOL

In June 2020, Amazon Air secured up to 6 million gallons of sustainable aviation fuel supplied
by Shell Aviation and produced by World Energy.

In December 2019, Neste signed an agreement with KLM to supply its SAF for the flights from
Amsterdam Airport Schiphol. This agreement allowed Neste to join KLM’s corporate biofuel
program that aims to reduce CO2 emissions of business travel on KLM flights by 100%.
In December 2019, World Energy collaborated with Shell and Air France to supply its SAF for
the flights from San Francisco. This collaboration between Air France, World Energy, and Shell
exemplifies the rise in demand for SAF


References and Resources also include:




Cite This Article

International Defense Security & Technology (May 30, 2023) Synthetic and Sustainable Aviation fuels (SAF). Retrieved from
"Synthetic and Sustainable Aviation fuels (SAF)." International Defense Security & Technology - May 30, 2023,
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"Synthetic and Sustainable Aviation fuels (SAF)." International Defense Security & Technology [Online]. Available: [Accessed: May 30, 2023]

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