Sustainable Aviation Fuels and Advanced Propulsion Tech Will Help Industry Achieve Net Zero Goals by 2050

By Anne Wainscott-Sargent, AIAA Communications Team

[Link] Panelists discuss propulsion technology Thursday, January 9, at the 2025 AIAA SciTech Forum in Orlando, Florida. AIAA-©

ORLANDO, Fla. - An expert panel composed of three top aviation original equipment manufacturers (OEM), NASA, and the U.S. Department of Energy tackled how propulsion technology will drive the industry to achieve its goals for net zero carbon emissions by 2050 during the 2025 AIAA SciTech Forum.

Panelists emphasized fleet renewal, sustainable aviation fuels, and advanced propulsion technologies to help the industry achieve its carbon-mitigation goals.

"Aerospace is one of the hardest sectors to decarbonize," noted Peter de Bock, program director for the Department of Energy's Advanced Research Projects Agency-Energy (ARPA-E).

Organized similarly to DARPA, ARPA-E advances high-potential, high-impact energy technologies that are too early for private-sector investment. ARPA-E awardees are unique because they are developing entirely new ways to generate, store, and use energy.

"We take high-risk bets on the next generation of technology. What are things that the world would need 10 years from now?"

His agency is focusing closely on the transportation sector, which leads emissions over power generation, said de Bock, who predicts that the industry will get more scrutiny starting in 2030 and through the next decade.

"We see multiple modalities to be the path to the future. Anything you can do fully electric… can push the efficiency to 75 or 80%. That's a big deal. It's extremely hard but worth the try."

ARPA-E supports innovative technologies across the spectrum, including high-temperature alloys, atmospheric sensors, and sustainable aviation fuel production.

Low-hanging fruit for several aviation engine builders centers on technology improvements that drive fuel efficiency given how much fuel costs airlines' bottom lines.

More Efficient Propulsion

Michael Winter, chief science officer at RTX, and senior fellow of Advanced Technology at Pratt & Whitney, said 30-40% of the cost of running an airline and a modern airport is fuel.

"Propulsion efficiency really comes down to the fan or propulsor and the bypass in the nozzle," he said.

Pratt & Whitney in 2016 introduced a geared-fan architecture that has enabled a 16% improvement in fuel efficiency, noted Winter. Its geared turbofan (GTF) engine technology uses a specially designed fan that rotates at a slower speed while still achieving high bypass ratios, leading to significant fuel savings and reduced noise emissions compared to previous engine designs.

"As we look to the future, we see opportunities for greater efficiency - number one, going to higher thermal efficiency in engines, which over the last 85 years has improved about 400%." Winter added that higher thermal efficiency creates higher temperatures requiring new material systems and better cooling.

Saving Fuel with Propulsive Technology

On the propulsion technology front, GE Aerospace is embracing open fan technology. While not a new technology, it has matured over the last decade and a half, allowing it to be "as fast as a jet, [quiet], and 20% more efficient than today's engines," according to a recent GE Aerospace blog post.

GE Aerospace recently was awarded 840,000 hours on the Frontier supercomputer through the agency's INCITE program. INCITE is a highly competitive program that supports the world's most computationally intensive projects. Frontier was introduced in depth at another session during the forum by Bronson Messer II, director of science for the Leadership Computing Facility at Oak Ridge National Laboratory (ORNL). (Read more on Frontier here.)

In November, the company announced a new project with Boeing, NASA, and ORNL to model the integration of an open fan engine design with an airplane.

UK-based Rolls-Royce is pursuing continuous improvement in its gas turbine and power systems, including materials, cooling, and cycle efficiencies. Steve Wellborn, the company's senior fellow, said enhanced integration at the platform level will be critical for achieving these breakthroughs in fuel efficiency.

Embracing Whole-System Integration

Wellborn added that he sees a lot of manufacturing, digital, and service technologies coming together. "You're no longer just bolting engines onto an aircraft; you have to think of the whole system together."

"At the forefront of this has to be safety," he said.

Kathleen Mondino, manager of RISE Technology Maturation at GE Aerospace, also considers integration a critical trend. She predicts the future will be one that leverages open fan technology - "that means viewing the engine and aircraft together as one system, which hasn't been done before."

Filling Capability Gaps

NASA Glenn Research Center provides avionics providers with the tools and capabilities for optimization and simulation they need when looking at new architectures.

"We also look at where there might be a gap where there are lower technology readiness levels and do some work in that," said Joseph Connolly, deputy for Electrified Aircraft Propulsion Integration at NASA Glenn Research Center.

NASA is supporting several papers at the forum looking at concepts for hybrid-electric configuration with distribution propulsion to see what benefits the technologies might offer industry partners in the future.

Connolly also shared details on NASA's work on the Electrified Powertrain Flight Demonstration project, involving GE Aerospace and magniX, to develop a megawatt-class powertrain for commercial aircraft by the 2030s. The project includes a parallel hybrid architecture for a Saab 340 and a regional turboprop demonstrator for a Dash 7.

NASA's efforts focus on addressing key barriers in electrification, including high voltage at altitude and battery system performance.

Investing in Sustainable Fuels

Sustainable fuels are a big area of investment across the OEM community. "We see huge opportunities in hydrogen," said Winter, citing the new HySIITE (Hydrogen, Steam Injected Intercooled Turbine Engine) concept, shown to be 35% more efficient while reducing oxides of nitrogen by 99.3% and recapturing one gallon of water every three seconds.

Capitalizing on Coming Fleet Renewals
Moving aircraft to more efficient propulsion will likely occur at the end of this decade, said Mondino.

"GE Aerospace is laser focused on the narrow-body market," she said, adding that those aircraft fleets are up for renewal toward the end of this decade or at the beginning of the next.

She emphasized that making this transition will require "a big step change" in how the OEM market approaches product innovation and problem-solving.

"You've got to break out of the box that you're currently in," she said.

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