SOLAR AND CLEAN FUELS SUSTAINABLE AVIATION FUEL
A CLEARER FLIGHT PLAN FOR TACKLING AVIATION’S CLIMATE IMPACT
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A ir travel represents around 2.5% of global CO2 emissions – a proportion that is likely to grow if air travel continues on a business-as-usual trajectory, and as other sectors start to decarbonize. While many forms of land-based transport can rely on electricity via batteries or fuel cells, aviation, particularly long-haul aviation, relies on high energy-density fuel, which cannot be easily substituted by the battery technology of today, so scaling up sustainable aviation fuel (SAF), which can offer up to 100% net emission reductions and work with existing fleets, has emerged as the best option for the sector. In response, we’ve seen intense innovation in the SAF industry, with major breakthroughs in production technology and new feedstock utilization pathways – as well as widespread policy support, as countries around the world have established SAF mandates and incentives, requiring flights to start using small, but increasing, percentages of SAF. But the required scaling curve is steep - in an assessment published in Bloomberg, SAF supply needs to grow 16-fold by 2030 to stay on track to meet the industry’s net-zero goals.
The global airline industry’s post-COVID comeback showed no sign of stopping in 2024, as passenger numbers hit an all-time high of 5 billion, according to the International Air Transport Association (IATA). This growth represents a major turnaround for an industry that suffered years of losses under the pandemic – but it also represents one of the toughest climate challenges to solve as we enter the second quarter of the century.
The Feedstock Challenge One of the biggest challenges with SAF is the search for the right sources of sustainable feedstocks, with many SAF projects struggling with feedstocks that are too expensive, too scarce, or both. Today, SAF is overwhelmingly produced using the hydro-processed esters and fatty acids (HEFA) process, which converts fats, oils, and greases from sources like used cooking oil (UCO) and animal fats. Some SAF is also produced via the HEFA process using crop-based feeds like canola oil and soybean oil, but because such feeds compete with food production, these are usually not considered part of the long-term SAF solution. HEFA-based SAF has paved the way for the industry, but there are already feedstock constraints for this process and SAF adoption is still in the low single-digit percent range.
China, the world’s largest producer of UCO is on track to run out in the near future. Pressure on the supply chain not only means HEFA feedstocks are more expensive, but it also creates a strong incentive towards fraudulent behaviours, like bad actors classifying virgin oils as UCO. HEFA fuels have created the foundation for the industry – but those looking to scale up SAF production ethically are struggling to meet demand using waste streams like UCO alone. Developing new (and more scalable) carbon feedstock streams, and the process technologies to convert them cost-efficiently into drop-in liquid fuel, is therefore a core requirement of the next phase of SAF growth. Broadening Horizons In response to the supply challenges with UCO-derived fuels, the industry has begun exploring using green
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THE FUTURE OF ENERGY
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