Sustainable Aviation Fuel: The Future of Jet Fuel for a Greener Aviation Industry

Aviation is at a crossroads. With the clock ticking down to mitigate climate change and decarbonise the economy, airlines have a critical role to play in the more sustainable world we must build. Currently, jet fuel is burned on every single flight across the globe, accounting for around 2.4 of every 100 tonnes of carbon dioxide (CO2) released into the atmosphere. This so-called ‘well-to-wake’ contribution of CO2 is certain, measurable and in need of reduction. Failure to make substantial progress will undermine the industry’s own measurement and reduction of carbon in flight. Enter Sustainable Aviation Fuel (SAF), which stands to reduce the carbon footprint of aviation without compromising on performance. This article examines the context and benefits of SAF, the hurdles to be cleared if it is to truly take off, and the role it is likely to play in the future of aviation. With a better understanding, stakeholders can shape the decisions needed to make aviation a truly sustainable part of our future.

What is Sustainable Aviation Fuel (SAF)?

SAF is a fuel used in aviation which can substitute for fossil-based jet fuel (known widely as ‘kerosene’). Different to traditional jet fuel, which is made from petroleum, SAF can be made using renewable feedstocks such as used cooking oils, agricultural waste, processing residues such as the woody parts of plants left over after harvesting, and even carbon captured directly out of the air. The lifecycle carbon emissions from SAF burning are significantly reduced compared with conventional jet fuel through sustainable sourcing and production processes.

Because SAF is compatible with current jet fuel infrastructure and drop-in capable, meaning it can be substituted without any modifications to the fuel system, it has the potential to have a large immediate effect on emissions. This is critically important because it removes the need to modify an existing airline industry built at considerable cost. SAF also supports the circular economy, using waste and renewable resources to meet production goals Wider airline use of SAF helps the industry clean up its climate act and make great inroads toward ambitious climate targets.

Production Processes and Feedstocks

Sustainable Aviation Fuel is made from a wide range of advanced technologies and feedstocks. One of the most common pathways is the Hydroprocessed Esters and Fatty Acids (HEFA) process that converts waste oils and fats into jet fuel, while alternative pathways such as the Fischer-Tropsch process gasify biomass to produce synthetic fuel. We’re now seeing technologies such as alcohol-to-jet (ATJ) and power-to-liquid (PtL), both of which could further increase the range of feasible feedstock and production options.

SAF feedstocks encompass a wide variety of renewable and waste materials, including used cooking oil, animal fats, and agricultural residues and dedicated energy crops. Each feedstock has its unique advantages and challenges: waste oils can be an abundant and low-cost starting ingredient, but are only available in limited quantities. Dedicated energy crops can – if produced with minimal resource use – provide a more consistent supply, but could compete with food production and with higher priority land uses. SAF sustainability and large-scale impact should be based on balancing these and other factors.

Environmental and Economic Benefits

The most immediately and substantially tangible environmental benefit of SAF is its climate impact. It can dramatically reduce greenhouse gas emissions compared with conventional jet fuel. Under the EU’s Renewable Energy Directive, SAF can generate significant lifecycle emissions reductions of up to 80 per cent. These arise from sourcing feedstocks sustainably and then realising further environmental benefits through the pyrolysis or hydro-conversion processes that transform certain classes of feedstock into the fuel we use in aviation today. Through reducing or avoiding the use of fossil carbon in jet fuel and mitigating the impacts associated with upstream carbon extraction processes, SAF can also reduce other localised atmospheric pollutants such as SOx and particulate matter, helping to reduce air pollution around airports.

From an economic standpoint, SAF represents a unique chance for the aviation sector to innovate and grow. The process of developing and scaling SAF production can catalyse the creation of new industries and provide jobs, especially in rural or agricultural areas. At the same time, the rise of SAF demand provides an investment opportunity that improves the competitive position of airlines that can tout themselves as sustainable leaders. The main impediment to SAF adoption today is the cost: SAF prices are currently much higher than fossil fuel jet prices. Government subsidies, incentives and carbon pricing policies are necessary to help reduce this cost gap and encourage transition to low-carbon aviation.

Challenges and Barriers to Adoption

Despite its potential, the widescale uptake of Sustainable Aviation Fuel (SAF) has been hampered by a number of barriers. Indeed, the cost of production is significantly higher compared with conventional jet fuel. The complex and green technologies needed, as well as the use of sustainable feedstocks, puts pressure on the production cost that is much higher than conventional fossil-based alternatives. It is therefore difficult for airlines to justify switching to a more expensive fuel given the highly competitive and price sensitive industry. Investment in the research and development of technologies needed for producing SAF is therefore required in order to drive down costs.

A second significant hurdle is the scalability of sustainable feedstocks – our sources of carbon for fuel production. While SAF can be derived from a wide range of available feedstocks, supply is not unlimited and these materials and their derived products could ultimately be used for other purposes, or indeed other uses of land. It is essential for the long-term viability of SAF that we maintain a reliable, long-term supply of SAF feedstocks. Furthermore, there are regulatory or certification barriers to the adoption of SAF. We need to be able to guarantee that SAF is safe for use and meets performance standards. Certifying SAF will require a series of demonstrations before it can be widely adopted. Working with regulators to streamline these processes and maximise international cooperation is essential.

Current Initiatives and Future Prospects

There are also a range of partnerships and programmes that are focused on incentivising the development and uptake of SAF, with airlines, fuel producers, governments and international organisations promoting and partnering on SAF technologies development and robust supply chains. For example, through its vision – Zero Carbon – the International Air Transport Association (IATA) has set expectations that at least 2 per cent of the global jet-fuel mix in 2025 (and 65 per cent by 2050) will be SAF. In turn, national programmes and policies by governments are introducing incentives to provide financial assistance for SAF production and use.

The way forward for SAF is promising, but still requires perseverance and collaboration. Progress in production technology, feedstock diversification and other ingredients will be instrumental to scale up SAF. Given that it is recently entering the aviation sector, investment in the RD programme as well as barriers to scale-up – related to certification, infrastructure, blending, GHG emissions reduction and carbon trading – should be strategically adopted, facilitated by a supportive policy framework. On one hand, raising public awareness and demand for greener aviation can further push the aviation industry towards SAF adoption. On the other hand, raising awareness among travellers can contribute to a significant reduction in demand. A more sustainable aviation sector can be achieved by a combination of SAF adoption and behaviour changes among travellers.

Role of Policy and Regulation

Policy and regulation can accelerate the uptake of SAF and other low-carbon technologies through incentives, mandates and other measures. Such policies would generate favourable conditions and offer financial support for SAF’s development. For instance, carbon pricing mechanisms, subsidies and tax credits can help to offset technology costs, such as the present cost-premium between SAF and conventional jet fuel. Moreover, SAF blending mandates and requirements can stimulate demand by assuring market incentives for producers.

SAF must also be legally enabled across the world through international agreements that harmonise national regulations. The international nature of the aviation industry means that standards and policies can be built with regard to global markets. International bodies, such as the International Civil Aviation Organization (ICAO), are building international frameworks for certification and use of SAF. Global standards can help reduce variation among countries in SAF status and availability. In other words, international collaboration can minimise regulatory barriers to prevent derailing the SAF transition. What’s more, SAF should not be left to the market to deliver alone. The aviation industry needs public-private partnerships to support innovation and investment in SAF.

Conclusion

Sustainable Aviation Fuel can be the next-generation game-changer for electric aviation to operate in our environment, while meeting the United Nations Sustainable Development Goals and other international environmental initiatives. But to realise this vision, SAF innovation and adoption must overcome near-term hurdles involving cost, feedstock and regulatory issues. With collaboration between industry, government and international organisations, SAF can emerge as the mainstream solution to help make aviation more environmentally sustainable. The future of commercial aviation is here, and it is looking greener.