Rethinking Growth in the Age of Green Skies
Sustainable Aviation Fuel, often lauded as the aviation industry’s silver bullet for decarbonisation, carries with it more than just the promise of cleaner skies. As airports position themselves as climate leaders, SAF emerges as both a technological hope and a strategic dilemma. The deeper question lies not in whether SAF can reduce emissions but whether its deployment justifies large-scale airport expansion.
What Makes SAF So Special?
SAF replaces conventional jet fuel with a blend derived from municipal waste, biomass, or even CO2 captured directly from the atmosphere. When used, it emits CO2—just like fossil jet fuel—but this carbon originates from sources already in the carbon cycle, thus neutral in net terms if sourced and refined responsibly.
This closed-loop concept appeals to climate regulators and aviation industry stakeholders, especially as SAF can be used with existing aircraft and airport infrastructure. It is already blended into jet fuel at major hubs and has successfully powered flights at 100 percent concentration during trials.
A Reality Check on Emissions
Despite its appeal, SAF is not a panacea. Its sustainability hinges on how it is produced. If fossil energy powers the production process or if land use changes release additional emissions, the lifecycle benefits are compromised. Moreover, current rules permit fuels to be labelled “sustainable” even if they reduce emissions by only 40 percent. In practice, blending limits (up to 50 percent with fossil jet fuel) result in flights achieving as little as 20 percent emission reductions.
Still, major policy frameworks are backing SAF. Mandates in the US, UK, and EU are targeting significant volumes by 2050. Ambitiously, SAF is expected to deliver up to 65 percent of aviation’s carbon reduction under industry net zero goals.
Why We Are Not Flying on 100 Percent SAF Yet
Cost remains a primary constraint. Even under optimistic scenarios, SAF production costs exceed fossil jet fuel by 190 to 500 percent. Technologies like direct air capture—while highly sustainable—are among the most expensive due to their energy intensity.
Moreover, feedstock limitations present a bottleneck. The most economical options like used cooking oil are finite. Scaling up SAF production will require shifting to more contentious sources, potentially disrupting food systems or increasing land-use emissions.
Scaling SAF Is Not About Parity, It Is About Prioritisation
A significant insight is that SAF will likely never reach cost parity with fossil fuels without sustained policy support. But that is not a flaw—it is a feature. SAF should be viewed not through the lens of cost parity, but as an ethical and environmental imperative.
Rather than delaying action until it becomes cheap, the challenge is to design aviation strategies that accept SAF’s higher cost as the price of climate responsibility. This repositions SAF not as a competitor to fossil fuels but as a cornerstone of responsible growth.
Does SAF Justify Airport Expansion?
Herein lies a paradox. SAF is often cited to support airport expansion, suggesting that increased capacity can be sustainable. However, even in best-case scenarios, SAF uptake will remain modest in the short term. Global SAF use was just 0.3 percent of aviation fuel in 2024. Realistically, it may only reach 6 percent by 2030 in the EU.
Furthermore, SAF does not address all climate impacts. Non-CO2 effects like nitrogen oxide emissions and contrail formation persist. While SAF may reduce contrail impacts by up to 44 percent, these benefits remain under study and are far from universal.
An Opportunity to Redefine Progress
Rather than a green light for unbounded airport expansion, SAF presents an opportunity to redefine what progress in aviation means. It calls for climate-aligned infrastructure, demand-side interventions, and strategic investments that support decarbonisation without defaulting to growth-based narratives.
Conclusion: A More Nuanced Flight Path
SAF is not a blank cheque for expansion, but a signal to invest in smarter, more sustainable aviation systems. Airports that align their development plans with realistic SAF deployment, lifecycle sustainability, and community impacts will lead the transition. In doing so, they position themselves not just as transport hubs but as leaders in climate-conscious infrastructure.