Current Use and Future Technologies: How Sustainable Aviation Fuel Is Made

SAF Has Important Chemical Differences from Traditional Aviation Fuel

To begin, a short review of conventional jet fuel can provide helpful context. Conventional aviation fuel is an energy-dense kerosene-based propellant. It was created to provide the tremendous power required by modern aviation engines. It has a higher ignition temperature and a lower freezing point than regular gasoline because it has a longer sequence of hydrocarbons. However, since (like gasoline) it is dependent on fossil fuels, it emits a lot of CO2 during combustion. 

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On the other hand, SAFs are an option derived from renewable hydrocarbon sources which are not obtained from fossil fuels. These include woodland biomass, waste cooking oil, and municipal garbage. The idea behind sourcing hydrocarbons from waste is sustainability. Ideally, supplies ought to be able to be replenished frequently. According to Shell, SAF was first used in 2008.

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Several airline companies have declared intentions to utilize SAF at various levels, and the trend is growing. The International Civil Aviation Organization (ICAO) anticipated in 2019 that SAF usage would reach 8 billion liters by 2032 from current levels of 6.45 million liters.

SAF Leverages Waste Products to Power Aircraft

To make SAF, the main ingredient or "feedstock" is first obtained from one or more source materials. Feedstocks could be waste items like oils or domestic garbage or be specially developed plant matter. Fats, oils, and greases (FOGs) are now a major supply of SAF feedstock.

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For instance, Neste has a deal with McDonald's to utilize cooking oil from its Dutch locations. Furthermore, organic matter and municipal solid waste are becoming more popular as energy sources. These have the ability to substantially cut CO2 emissions between 85% and 95% during their lifespan compared to conventional jet fuel. However, SAF has a lower energy density than traditional fuel, so it requires a high volume of feedstock.

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These feedstocks are gathered and sorted before being processed to generate fuel. This transformation is accomplished using a variety of methods. Hydrotreated Esters and Fatty Acids (HEFA) are the most often used technology for FOGs. The refined liquids react with hydrogen and other catalysts before being distilled into usable fuel.

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On the other hand, Fischer-Tropsch Synthetic Paraffinic Kerosene (FT-SPK) is a common technique to convert solid biomass. This entails gasifying solid biomass at extreme temperatures to produce a synthesis gas, which is then processed into hydrocarbon chains.

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Current Jet Engines Require a Blend of Fuels

Pure SAF is not suitable for use. However, it may be utilized in current jet engines after being combined with conventional jet fuel. This guarantees that the performance does not excessively degrade and that the engines do not face too much wear. SAF fuel blends must fulfill stringent specifications to ensure safety and reliable function.

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SAF is combined with regular fuel in concentrations of up to 50%. Many fuels now employ considerably smaller quantities of SAF, although this is predicted to rise significantly, perhaps up to 100%. United Airlines has conducted test flights, including one engine powered entirely by SAF. However, they did so without any passengers.

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The blended mix of fuels is re-certified as Jet A or Jet A-1 fuel and may be handled, carried, and used in the same manner as regular fuel. One of the most convenient consequences of the process is that, after blending, no adjustments to the current gasoline infrastructure or supply chain are necessary. For alternative fuels like hydrogen, this is a serious obstacle.

Other Technologies in SAF Are In Development

The development of new SAFs will undoubtedly continue. For example, synthetic kerosene is a current initiative that uses "power-to-liquid" techniques, which have the potential to cut emissions by up to 99%. Power-to-Liquid refers to the electrolytic transformation of renewable energy into fuels, mainly hydrogen.

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However, there is still a considerable distance to go before this is widely adopted. Still, it has the potential to offer a circular, carbon-neutral system for aviation by converting the CO2 created by burning fuels into a new power source.

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SAF Will Continue to Grow in Vale in the Coming Years

SAF's present application is pretty restricted. Despite significant promises from several carriers, overall utilization remains minimal compared to regular jet fuel. The cost of large enough feedstocks and production methods should decrease with better technology and societal buy-in. In the long term, it may even provide more consistent prices than oil, and it will become increasingly vital as the sector draws ever closer to halving its CO2 emissions by 2025. Along with other advances in the industry, SAF is another illustration that many airlines are making a serious push for sustainability.

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Key Takeaways 

• Respect Your Destination – Hyper efficiency is not all there is to travel sustainability. Learn as much as you can about the social customs of your destination. In addition, clean up after yourself so residents and future travelers can enjoy.
• Avoid Single-Use Plastic – Not only is it an ongoing problem in aviation, but it plagues less affluent destinations. Moreover, the resurgence of plastic containers brought on by COVID disproportionately affects poorer nations. Bring or buy reusable containers on your trip.
• Go to the Park – Not just parks, but see as many conservation areas as possible. The cost of admission goes directly to funding conservation initiatives.