Powering the future of sustainable flights

Australians love their travel and with huge distances to cover between domestic destinations and beyond, our aviation fuel use continues to rise. 

And we’re not the only ones – the aviation industry contributes about 2.5% of the world’s total carbon and accounts for about 8% of global oil production. 

But as commercial aircraft operators around the world work towards net zero goals, it’s proving one of the most difficult industries to decarbonise. 

The demand for jet fuel is growing, particularly in the Asia Pacific region – demand in Australia is expected to increase by 75 per cent before 2050, with Boeing forecasting around 42,600 new commercial jets will be needed over the next 20 years. 

At the same time, the limitations of technology make electric engines and alternative fuels like green hydrogen impractical for long haul flights, meaning commercial airlines and defence forces are increasingly looking for solutions in sustainable aviation fuels. 

Sustainable aviation fuel – a drop-in replacement for traditional aviation fuel solutions – is quickly gaining a foothold and is already used in more than 250,000 flights. 

What is sustainable aviation fuel?  

Sustainable aviation fuel (SAF) is a low carbon alternative to traditional jet fuel made from renewable sources like waste or crops. 

SAF works with existing aircraft infrastructure. The CSIRO’s Sustainable Aviation Fuel Roadmap says it offers the largest potential to reduce carbon emissions over the next 30 years in all aviation segments. 

It’s currently made from five main types of raw materials: oils and fats, sugar and cereal, municipal solid waste, wood and agricultural residue, or renewable energy and carbon, which are used to replace a proportion of the crude oil feedstock. 

Depending on the feedstock, SAF can achieve a reduction in CO2 emissions of at least 70% and up to 85% compared to conventional kerosene-based fuel – a significant incentive for airlines when CO2 compliance costs are increasing at around 3.4% a year.  

Already, Airbus aircraft are 50% SAF compatible. To address supply, the CSIRO and Boeing are working together to explore production opportunities and Australia and New Zealand are partnering with a view to becoming an integral part of a growing sustainable aviation fuel supply chain. 

At Emerald in Queensland, a multi-grain processing facility is being built specifically to support the SAF industry with a capacity to process about 70,000 tonnes a year once complete to support an industry which is projected to be worth up to $3 billion annually by 2030. 

How is SAF made?

Each different feedstock uses a different production technology which must be approved by the ASTM before being commercially deployed. 

 Most of the SAF supplied today is made by converting waste fats, oils, and greases into synthetic kerosene using hydrotreated esters and fatty acids (HEFA).  

 Standalone units work by turning sustainable feedstocks into synthetic kerosene (SK), which is certified under the ASTM D7566 standard. It is then blended with up to 50 per cent conventional jet fuel, certified to ASTM D1655 or Defence Standard 91-091 and supplied as a conventional Jet A/Jet A-1 fuel. 

 Alternatively, SAF can be produced through co-processing, where up to 5% sustainable feedstocks are hydro-processed alongside fossil feedstocks in a refinery. 

The CSIRO is researching use of gas to liquid technology to create SAF from sustainable sources.

 

Sustainable aviation fuel – Pros and Cons

 Pros – Clean technology and efficiency 

 The good news is SAF is safe to use in any aircraft that currently use jet fuel. 

 It achieves lifecycle carbon emission savings of up to 80 per cent – good news for the environment and for reducing compliance costs – this year, tests in Germany with aircraft running on 100% sustainable aviation fuel also found reductions in soot and contrails.  

 SAF also has a higher energy density than conventional jet fuel, requiring slightly less fuel to be carried and combusted during flight, thereby improving fuel efficiency. 

Cons -Price and supply: Fuel is one of the largest operational expenses for commercial airlines and the cost of SAF has until now far outstripped traditional Jet A1 fuel. 

 In 2020, the overall cost of jet fuel was $0.5 per liter. Meanwhile, the cost of SAF was $1.1 per litre, more than double the price of conventional jet fuel. 

 But the tide is turning and with jet fuel prices growing at about 1% a year, the efficiencies sustainable fuel can achieve and growth in supply are expected to make it roughly equal to jet fuel and carbon emission costs by 2037. 

 The CSIRO says while Australia has the feedstock, a lack of on-shire refining capability may also contribute to higher costs and supply constraint in the short-term. 

Storing sustainable aviation fuel

In more good news, SAF can be stored in the same fuel infrastructure as other jet fuels and the same principles apply for ensuring fuel stays fresh and in good condition. 

The F.E.S Tanks range of portable, self-bunded double-walled aviation fuel tanks provides a hassle-free solution for AVGAS, Jet A1 and SAF that meets or exceeds Australian Standards, with none of the hassle of cleaning and inspecting underground tanks. 

F.E.S aviation fuel tanks are also made with a sloping floor and without interior baffles, ensuring a free drainage floor pan and allowing for the safe removal of water from aviation fuel as part of your daily maintenance program. 

For expert advice on your sustainable aviation fuel storage needs, call the team at F.E.S Tanks to discuss the aviation fuel storage solution that’s right for you. 

What’s so special about avgas aviation fuel?

General aviation is a critical industry in Australia, particularly for regional communities. 

It delivers education and health services, tourism, regional health and education services, supports agriculture and enables emergency services. 

In most cases, the aircraft involved are piston engine aircraft powered by avgas aviation fuel.  

What is avgas?

Avgas, short for aviation gasoline, is an aviation fuel used in planes driven by spark-ignited internal combustion piston engines. It is different from jet fuel, which is kerosene based, and from the petrol used in motor vehicles because it needs to power higher performance aircraft engines.  

A fuel’s octane rating measures its ability to withstand compression in the engine without detonating – piston engine aircraft require a high-octane fuel. For this reason, the most common types of avgas still contain tetraethyl lead, which assists with engine lubrication and helps prevent engine knocking (premature detonation). Because tetraethyl lead is toxic, only the minimum amount needed to achieve the required fuel octane rating is used – and manufacturers are working to find safer and more sustainable alternatives. 

How is avgas classified?

Different grades of avgas have different maximum lead concentrations and are identified by the octane rating of the fuel tested to both “aviation lean” and “aviation rich” standards. These standards relate to the lean engine settings typically used for cruising and the rich settings used for take-off and when full power is required. 

Different types of avgas are identified by their octane ratings and are coloured for easy identification. 

Types of avgas 

There are two main avgas grades (100 and 100LL low lead) used in the general aviation community.  

• Avgas 100 is the standard high-octane fuel for aviation piston engines. It has a high lead content and is dyed green. The two major specifications for Avgas 100 are the ASTM D910 and UK DEF STAN 91-090. The two specifications differ in antioxidant content, oxidation stability requirements and maximum lead content. 

• Avgas 100LL is a lower lead version of Avgas 100. This grade is listed in the same specifications as Avgas 100, namely ASTM D910 and UK DEF STAN 91-090. Avgas 100LL is dyed blue. 

• In the United States, the Federal Aviation Administration has approved an unleaded avgas, the G100UL. In Australia, unleaded avgas is still in development, with the Civil Aviation Safety Authority warning in 2023 that it should not simply be substituted for leaded fuel. Shell is among major suppliers working on development of an unleaded avgas with similar octane performance to Avgas 100LL, but testing and development is still underway. This fuel is controlled by the specification ASTM D7960. 

Getting avgas storage right

Avgas is extremely flammable and toxic. Storing it properly in accordance with regulations is critical for safety in the air and on the ground. 

Storage and transfer points provide the greatest opportunity for fuel contamination, with surfactants, water, particulates and misfuelling the most common contaminants for aviation fuel.  

• Water contamination is possibly the greatest threat to aviation fuel. Free water can enter the fuel through degraded seals, accumulation at low points in the tank or pipeline or condensation from air entering the tank. In piston-powered aircraft, water can collect in the carburettor float bowl and stop the engine. This is why regular testing with a water detecting kit is essential. 

• Particulates like rust, scale, lint and dust can cause engine stalling and damage. While rust is most common, other solids that can cause this type of contamination include dust and pollen, which can enter through tank vents or slip past seals. Rubber particles and fibres can also enter through damaged hoses and filters, while microbial infestation can create slimy residue. Avoid refuelling from fuel cans, which increases the risk of particulate contamination.

•  Surfactants are are soap or detergent-like compounds that can be introduced into the fuel during processing and transfer, including through cross-contamination and fuel additives. While small amounts are common, excessive amounts reduce the surface tension between water and the fuel. This can cause water and small particles in the fuel to remain suspended rather than settling into the sumps. Surfactants also tend to collect in filter elements making them less effective. 

F.E.S Tanks avgas storage solutions

F.E.S Tanks avgas fuel tanks are made to the highest quality standards with a 100% stainless steel inner tank and all fittings are also made of stainless steel, minimising the risk of rust and particle contamination or water leaks. They’re also built without an interior baffle to ensure free drainage and allow for the safe removal of water. 

Talk to the experts at F.E.S Tanks to get the most out of your avgas fuel storage.