Gregory Polek has spent his entire career in aviation journalism with AIN, starting as a proofreader and assistant to then-managing editor Mary Mahoney in 1995 after serving an internship with&nbsp;New Jersey Monthly&nbsp;magazine and completing his B.A. degree in English/Writing at New Jersey’s William Paterson College. By 1997 Polek accepted a position as an associate editor, covering the regional airline beat for&nbsp;Aviation International News&nbsp;in place of retiring industry veteran Don Anderson. The assignment took Polek across North America and Europe to profile regional airlines varying in size and mission from the likes of floatplane operators Kenmore Air and Chalk’s Ocean Airways to regional jet operators such as SkyWest and American Eagle. Today, in his dual role as Air Transport Editor and International Airshow Editor, Polek writes, edits, and manages AIN’s commercial aviation content while overseeing each of the company’s daily international air show publications in Paris, Farnborough, Singapore, and Dubai. Most recently Polek has assumed oversight of daily coverage of the Helicopter Association International’s annual Heli-Expo convention.

Senior Editor

Gregory Polek

While estimates of the extent to which the use of sustainable aviation fuel (SAF) reduces CO2 emissions in aircraft can vary, aerospace manufacturers generally cite an 80 percent lifecycle carbon emissions benefit for 100 percent SAF.&nbsp;Scientists know less about how the contrails produced by SAF emissions differ from those generated by kerosene, however, prompting Boeing to partner with United Airlines and NASA to study the phenomenon with its latest EcoDemonstrator aircraft.
Contrails, or the persistent condensation trails produced when airplanes fly through cold, humid air, can trap heat in the atmosphere, some of the latest research suggests. To learn more, Boeing in early October began flying a CFM Leap-1B-powered 737 Max 10 destined for United Airlines on 100 percent sustainable aviation fuel (SAF) and conventional fuel in separate tanks, alternating the fuels during testing. Studying multiple fuels with the same engine allows researchers to differentiate the emissions reductions resulting from advanced engine technology from those resulting from advanced jet fuel chemistry.
Although the sample of results from last month’s testing remains too small to draw any conclusions, researchers from Boeing, NASA, GE Aerospace, and German aerospace research center DLR expressed optimism over the observations from the first three weeks of trials. Speaking late last month from Boeing offices in Seattle, DLR research team lead Christiane Voigt explained some of the science behind SAF’s effect on the production of contrails.
“These sustainable aviation fuels have a lower aromatic content and these are precursors to the soot particle emissions and the soot particles are the precursors for the ice crystals and contrails,” she noted. “Science tells us that warming from contrails might be as large as the warming from CO2 emissions.”
NASA’s DC-8 Airborne Science Lab flies behind the 737 to measure emissions produced by each type of fuel and contrail ice particles. Based at NASA’s Armstrong Flight Research Center, the DC-8 incorporates a suite of sensors and data systems adaptable to specific missions or instruments. Nicki Reid, operations engineer/DC-8 mission manager for the NASA Airborne Science Program, explained that the DC-8 flies between four and five miles behind the EcoDemonstrator while the research team alternates from one fuel to another in the Max 10.
“We’ll fly through for maybe 20 or 30 minutes sampling on jet-A, and then as we’re coming back through, we’ll make a turn and fly through that exact same position in the air so that we’ll have the same humidity, the same altitude, we’ll have the engines running at the same power and we’ll direct the Boeing team to switch to the SAF so that we can determine the actual difference between both of those fuels,” she said.
The most recent EcoDemonstrator flights build upon testing in 2021 and 2022 on a 737 Max 9 and a 777-200ER, respectively. Analysis of the resulting data confirmed that the use of paraffinic SAF yields “dramatic” particle emission reductions, the extent to which depending on the chemical composition of the SAF used.
“We know from ground measurement tests that we reduced soot emissions when we go with paraffinic fuel relative to higher aromatic fuels,” explained Boeing emissions technical fellow Steve Baughcum. “And because it was a synthetic fuel and never really had any sulfur in the feedstocks, it’s a low-sulfur fuel for us so that we expect both to reduce soot emissions and the volatile aerosols that are being produced by the aircraft. So we can basically explore how those reductions change the contrail properties that we measure in the aircraft.”
Funded by the FAA’s Ascent Center of Excellence, the SAF for the most recent studies comes from World Energy in California. While Boeing has set a target date of 2030 to begin delivering aircraft compatible with 100 percent SAF, company vice president of product development Mike Sinnett explained that the transition will require examination of the long-term effects of using the fuel on each aircraft component that touches fuel.
Sinnett added that researchers know that running 100 percent SAF in aircraft that have had long-term exposure to jet-A could result in seal damage. SAF lacks the aromatics contained in jet-A, which helps seals swell to prevent leakage. Although they know running 100 percent SAF on a new airplane not exposed to conventional jet fuel will not affect the seals, the long-term effects on the entire fuel system and other parts of the airplane such as the wings and engines need further study.
“The other issue is the density differences change how you gauge the fuel,” noted Sinnett. “We account for that in the flight test environment, but certainly over the longer term we’ll have to make sure that our fuel gauging systems or fuel quantity systems can account for a much broader range of densities that we see today in conventional jet fuel.”

News about environmental issues relating to aircraft operations, including noise issues, emissisions, and regulations. See Fuel for biofuel.

Latest Boeing EcoDemonstrator Jet Assesses Impact of SAF Use on Contrails

Researchers are encouraged by early findings on a Boeing 737 Max 10 airliner

Scientists know less about how the contrails produced by sustainable aviation fuels differ from those generated by kerosene. 

Latest Boeing EcoDemonstrator Studies Tackle SAF’s Contrail Effects

2024 Corporate Aviation Leadership Summit

Curt Epstein

News and developments about aviation fuel, including jet fuel, aviation gasoline, and biofuel.

News and issues relating to the aerospace industry that are related to the science, engineering and business of flight in space involving civil, industrial and military applications, and similar topics related to flight in the atmosphere of the Earth that are not covered more directly by other AINonline subject channels. In other words, both astronautical and aeronautical subjects, except for those aeronautical topics that are specifically covered elsewhere on this website.

The report sees the Midwest as a future hotbed of SAF production

Environmental Group Sees U.S. e-Fuel Potential

Kerry Lynch

News and issues relating to business, corporate and private aviation, primarily regarding turbine-engine-powered airplanes and helicopters. Subjects include aircraft, engines, maintenance, operations, personnel, acquisitions, accidents, safety, security, and training.

NBAA called a study suggesting business aviation emissions will need to be regulated 'misleading' 

NBAA Challenges Study Highlighting Bizav Emissions

NASA's Gulfstream G-III will use lidar technology to scan contrails of GE's Boeing 747

NASA and GE Plan Flight Tests To Study Contrails

Charles Alcock

News and developments about airplanes, helicopters and unmanned air vehicles used in all varieties of operations, including airlines, military, business, commercial, general aviation and private.

News and developments about aircraft engines, including turbofan, turboprop, turboshaft and piston.

News and issues relating to international air transport and cargo carriers, national airlines and regional airlines, including aircraft, engines, personnel, acquisitions, accidents, safety, security and training.

Project also includes Lockheed Martin Skunk Works, Honeywell Aerospace, and American Airlines, plus MIT and University of Michigan

NASA Contracts Electra for AACES Sustainable Airliner Program

New developments at airports including regulations and noise issues; legal disputes; openings, acquisitions and mergers.

New developments at FBOs including regulations and noise issues; legal disputes; openings, acquisitions and mergers.

4,000 solar panels have been fitted on buildings across the London-area facility

Solar Generates 25% of Farnborough's Electric Power

Matt Thurber

News and issues concerning general aviation, specifically airplanes and helicopters powered by piston and alternative engines (i.e., non-turbine powered aircraft). Subjects include aircraft, engines, personnel, acquisitions, accidents, safety, security and training.

Dubai Airshow 2023

In this article

Boeing 737 Series

Boeing Commercial

More In Environment

Environmental Group Sees U.S. e-Fuel Potential

The report sees the Midwest as a future hotbed of SAF production

NBAA Challenges Study Highlighting Bizav Emissions

NBAA called a study suggesting business aviation emissions will need to be regulated 'misleading'

NASA and GE Plan Flight Tests To Study Contrails

NASA's Gulfstream G-III will use lidar technology to scan contrails of GE's Boeing 747

NASA Contracts Electra for AACES Sustainable Airliner Program

Project also includes Lockheed Martin Skunk Works, Honeywell Aerospace, and American Airlines, plus MIT and University of Michigan

Solar Generates 25% of Farnborough's Electric Power

4,000 solar panels have been fitted on buildings across the London-area facility

San Carlos Flight Center Adopts Unleaded Swift 100R

High-octane unleaded avgas is becoming more available in California

Minnesota Selected for SAF Production Site

DG Fuels plans for the $5 billion production facility to be operational by 2030

Still In Its Infancy, SAF Growing by Leaps and Bounds

With jet-A holding a 75-year head start over SAF, it will take time to catch up

AIN Products

SUBSCRIPTIONS

RESOURCES

ABOUT AIN