Sustainable Aviation Fuel: Engineering the Future of Flight

As a Process Engineer at Kent, I’ve had the privilege of exploring some of the most pressing challenges in engineering today. One that stands out is sustainable aviation fuel (SAF) — a solution that could revolutionise the aviation industry while reducing its environmental footprint.

Aviation is a difficult industry to decarbonise. It accounts for around 8% of the UK’s total carbon emissions and is central to both economic growth and global connectivity [1]. However, with a commitment to achieve net zero emissions by 2050, the aviation sector must find viable solutions [2].

Why SAF?

SAF offers a unique advantage over other alternatives like hydrogen or battery-powered planes. It’s a ‘drop-in fuel’, meaning it can be used with minimal changes to existing aircraft and airport infrastructure. This makes it an ideal short- to medium-term solution while more disruptive technologies continue to develop.

Compared to traditional jet fuels, SAF reduces both carbon and non-carbon emissions, such as particulate matter and contrails related to the lower aromatic content. It’s a practical step toward greener aviation, but it comes with challenges.

What’s Driving the Change?

There are three major forces behind SAF adoption:

1. Policy: Governments around the world are introducing incentives and mandates to promote SAF. For example, the UK aims to have five SAF plants under construction by 2025, with a 10% SAF mandate by 2030 [3]. Similarly, the EU has committed to 70% SAF use in airports by 2050, and the US offers tax credits for SAF production [4].
2. Moral Considerations: Increasingly, consumers and businesses are seeking greener travel options. Airlines are responding by integrating SAF into their operations as part of broader Environmental, Social, and Governance (ESG) strategies.
3. Financial Drivers: Although SAF is currently more expensive than traditional jet fuel, its long-term potential for price stability is significant. By decentralising fuel production and utilising diverse feedstocks, SAF can reduce dependency on volatile global markets.

How is SAF Made?

SAF can be produced through multiple pathways, using feedstocks such as waste oils, municipal solid waste, and even captured CO₂. These processes lean on both traditional chemical engineering principles and technologies like Fischer-Tropsch synthesis and alcohol-to-jet conversion.

While SAF currently requires blending with traditional jet fuel, future advancements in aircraft aim to enable 100% drop-in SAF for use across entire fleets. This will significantly reduce emissions and improve sustainability.

Overcoming Challenges

SAF production is not without its hurdles. Feedstock availability, process complexity, and high energy demands are just a few of the technical challenges engineers face. For example:

• Many projects rely on municipal solid waste (MSW) or waste oil, but its availability is limited to densely populated areas.
• Producing SAF from waste materials involves energy-intensive processes like gasification and pyrolysis. Developing energy-efficient systems and integrating renewable energy sources are key to overcoming this.

From an economic perspective, cost remains the biggest barrier. Widespread adoption requires balancing financial incentives, consumer demand, and policy support to ensure SAF is a competitive alternative.

Looking Ahead

SAF represents an important step toward decarbonising aviation. While current methods rely heavily on waste-based feedstocks, future pathways, including carbon capture and green hydrogen, promise a more sustainable and scalable solution.

As engineers, we have the responsibility to optimise these technologies and ensure SAF projects are designed with lessons learned from past challenges. By tackling these issues head-on, we can contribute to a more sustainable future for aviation — and for our planet.

If you’re interested in discussing SAF, its challenges, or opportunities, I’d love to hear your thoughts. Let’s collaborate on building a greener future!

References:

[1] Sustainable Aviation. Net Zero Carbon Road-Map. 2022

[2] IATA. Our Commitment to Fly Net Zero by 2050. IATA.ORG. [Online] 2021: https://bit.ly/4d16kkQ

[3] UK Government. Jet Zero Strategy. 2022

[4] European Commission. ReFuelEU Aviation. 2023