When employees of GE Aviation and its Italian business Avio Aero have questions about Sustainable Aviation Fuel (SAF), they have at least two industry-recognized in-house experts to turn to: Gurhan Andac, GE Aviation’s engineering leader for aviation fuel and additives, and Antonio Peschiulli, Avio Aero’s combustion technology engineering leader.

Andac, Peschiulli and their colleagues have been evaluating and testing SAF, sometimes referred to as biofuel, in aircraft engines for more than a decade. The first commercial biofuel demonstration flight in 2008 was a GE CF6-powered Boeing 747. Similarly, the first commercial biofuel revenue flight took place in 2011 with CFM56* engines.

Then, in 2018, GE90 engines powered the world’s first commercial airliner flight with 100% SAF. The Boeing ecoDemonstrator flight test program took place in 2018 in collaboration with Federal Express with a 777 Freighter.

Today, all GE Aviation and CFM International engines can operate with approved SAF.

This work is critical to helping the global aviation industry meet its collective goals to reduce emissions. The International Air Transport Association (IATA), along with other industry partners, recognizes the need to address the global challenge of climate change and adopted a series of targets to reduce CO2 emissions from air transport. One of these goals is a reduction in net aviation CO2 emissions of 50% by 2050, relative to 2005 levels.

The level of CO2 emissions generated by consumption of jet fuel, on a life cycle analysis basis, can be up to 80% lower with SAF than Jet A or Jet A-1. The feedstock generation, production, and distribution process to produce SAF is where the most carbon footprint benefits are realized.

“SAF allows a more sustainable production and distribution process — that is consistent with economic, social, and environmental goals — along with an ecological balance as it mitigates consumption of natural resources and contribution to climate change, reducing aviation’s carbon footprint,” Andac confirms.

Engineers at GE Aviation have been evaluating testing Sustainable Aviation Fuel in aircraft engines for more than a decade. Today, all GE Aviation and CFM International engines can operate with approved SAF.

Air travel powered by so-called biofuels has been possible since the development of an industry standard for SAF by ASTM International in 2009. Since then, seven process pathways to SAF have been cleared through the ASTM process. These seven SAF pathways meet the same product standards as Jet A or Jet A-1. The significant difference is the source materials or feedstock from which they are synthetically derived — SAF can be made from vegetable oils, animal fats, algae, alcohol and sugar derivatives, and even organic waste — and the proportion in which they are blended with traditional fossil fuels.

Because SAF that meet ASTM standards also meet Jet A and Jet A-1 certification, these fuels are considered a “drop-in” substitute.

“Our teams ensure that the use of SAF does not adversely impact the engine system and its components, thanks to vigorous testing and analysis activities during evaluations,” continues Andac.

“We are also strongly engaged with the industrial and governmental organizations and committees that have the task of maintaining and developing SAF and related standards both on an operational level, and regarding policies and regulations that help the transition from conventional to more sustainable fuels; not to mention, also with customers who want to use them and make the transition,” Andac said.

Peschiulli has dedicated himself, along with his Avio colleagues, to comparative studies of traditional and alternative fuels within the laboratory shared with the Politecnico di Torino, called Great Lab (Green Engine for Air Transport). They study the relative effects on the aircraft engine influenced by the nature of the source material on which the fuel is based. Peschiulli’s commitment to sustainable aviation programs also developed subsequently with Clean Sky2.

SAF is readily available at some airports (e.g., Los Angeles, San Francisco, Oslo, Stockholm) and has already been used for over 320,000 commercial flights (blended in small percentage with Jet A or A-1 fuels). This accounts for less than 1% of global aviation fuel consumption, which is why a push towards the adoption of sustainable aviation fuel is increasingly desirable. In fact, according to studies in the ATAG’s Waypoint 2050 report, growth in use of SAF at the current rate would only yield 2% of global fuel consumption by 2025.

The same report also shows that displacement of traditional jet fuel could reach 86% of the global fuel supply (450-500 million tons) by 2050 with new investments, regulatory policies, and increases or optimizations in SAF production and their supply chain. Also, according to industry studies, if the contribution of completely new technologies such as hybrid electric or hydrogen fuel was added, the sector would be able to reach the much-desired goal of zero carbon emissions by 2065.

Transitioning to more widespread use of SAF presents several complexities, including the comparatively high product and process costs and challenges around the infrastructure and supply chain, which is still underdeveloped globally.

“Along with research and development, policy and regulations are needed to advance the technology to reduce the cost, and to establish robust infrastructure and supply chain. Such efforts are required to reach a future state where SAF could be used without blending it with the conventional fuel,” Peschiulli said.

Even as the aviation industry pushes for wider adoption and availability of SAF pathways currently approved, Andac and Peschiulli are looking ahead to a new challenge: A future SAF that requires no blending with petroleum. Efforts are underway within GE and across the industry to enable the use of SAF without blending with Jet A fuel.

“In a sector as regulated and high-tech as aeronautics, on the one hand, aviation design applies stringent standards to fuel properties to ensure safe operation of the combustor, and on the other hand, the process of certifying the fuel itself ensures that it — whatever the raw material or production process — continues to comply with those requirements,” Peschiulli explains. “It needs work to ensure that SAF-fueled jet engines can operate at the same safety level of the ones using conventional fuel, gaining more experience than that we have nowadays.”

“Surely” adds Peschiulli, “in addition to the issue of costs, an ethically sustainable production is also key. Indeed, the production process of those SAF obtained from vegetable oils and related cultivations must actually respond to sustainability criteria including social-economic impacts, in favor of the global environmental protection and food needs.”

*CFM56 engines are a product of CFM International, a 50-50 joint company between GE and Safran Aircraft Engines.