GE Aerospace's Passport engine during ground testing with 100% SAF in 2022.

Tests show GE and partner engines can ably operate on 100% SAF


Green Wing logo with white letters against a green backdrop, and leafs on either sideBoasting one the most extensive programmes for testing alternative fuel in the aviation industry, GE Aerospace reports that all its engines and those of its partners can ably operate on approved sustainable aviation fuel (SAF) blends today. And whilst extensive testing continues to help qualify new SAF options, the engine-maker confides to Runway Girl Network that early findings show a positive impact on contrails and emissions of using 100% SAF.

Currently, SAF approved for use is a synthetic component blended with petroleum-based Jet A or Jet A-1 fuel up to 50%. But GE Aerospace’s SAF testing has involved using 100% SAF, including plant-based material, fats, oils and greases, alcohols, waste streams, captured CO2, and other alternative feedstocks. Its work is quite expansive. Tests have been conducted on a mix of propulsion systems used for civil aviation and the military, with the aim of ensuring a more sustainable future for aviation.

Indeed, since 2016, GE has tested no fewer than ten engine models using 100% SAF. For example, in 2018, GE90 engines powered the first commercial airliner flight with 100% SAF in both engines on the Boeing ecoDemonstrator, a FedEx 777 freighter. Then in 2021, LEAP-1B engines — a product of CFM International, GE’s 50-50 joint company with Safran Aircraft Engines — powered the first passenger experimental flight with 100% SAF in one of the two engines on a United Airlines Boeing 737-8.

Notably, LEAP-1B engines this year powered test flights on 100% SAF in both engines of the Boeing ecoDemonstrator Explorer, a Boeing 737-10 destined for United Airlines, with testing conducted in collaboration with NASA. The aim of the flight-test programme was to test the effects of SAF on non-CO2 emissions.

Christiane Voigt, head of the cloud physics department at the German Aerospace Center (DLR) — which supported the campaign alongside GE, the US Federal Aviation Administration (FAA) and United — said at the time: “We saw a reduction in particle emissions when we were using SAFs, and we also saw a reduction in the ice crystals and contrails. That’s really a great result from this campaign.”

GE is also enthused about these early findings, with a GE spokesperson telling Runway Girl Network:

Testing efforts have shown lower non-volatile particulate matter (nvPM) using certain types of SAF, which is better for local air quality and potentially contrail formation. However, this is a relatively new research area and we’re interested in learning more.

Interestingly, GE doesn’t favor any specific SAF blend. “Approved SAF today are blends that meet specifications of conventional Jet A and Jet A-1, which means approved SAF can run in all GE Aerospace engines. Industry will need a variety of SAF to help meet emissions goals. GE Aerospace supports the development and adoption of all SAF options,” says the spokesperson.

In terms of SAF testing, the aerospace behemoth is certainly putting its money where its mouth is. Additional GE and GE partner engines tested at either the component level, the  engine level, or the aircraft level using 100% SAF include the F414 (for front-line fighters), GE9X, LEAP-1A, Passport (for business aviation), GEnx, HF120, and CFM56 powerplants, the latter being the world’s best-selling aircraft engine. These tests help GE understand engine performance — including operability, efficiency, and durability — and of course the impact of 100% SAF on contrails and emissions.


“We’re proud of doing the hard work to better understand the impact of different emissions on the environment and using science to guide the technology we are developing to invent the future of flight,” says Mohamed Ali, vice president of engineering for GE Aerospace.

GE Aerospace’s SAF testing efforts support the aviation industry’s broader long-term goal of net zero CO2 emissions by 2050. In an interim step, governments gathered last month at the third ICAO Conference on Aviation and Alternative Fuels (CAAF/3), setting a goal for aviation fuel in 2030 to be 5% less carbon intensive than conventional jet fuel used today.

More than 100 countries signed onto the non-binding agreement, which calls for the adoption of a new global framework to increase production of SAF as well as lower carbon aviation fuels (LCAF)l which ICAO defines as fossil-based fuels with a 10% reduction in lifecycle emissions compared to conventional kerosene — plus other cleaner energies such as hydrogen. The framework calls for improved access to financing to ensure that “no country is left behind” in the energy transition process, says ICAO.

Meanwhile, an international task force led by one of GE Aerospace’s experts is developing standardized industry specifications supporting adoption of 100% drop-in SAF, which does not require blending with conventional jet fuel.

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Featured image: GE Aerospace’s Passport engine during ground testing with 100% SAF in 2022.