Sustainable Aviation
RTX Hybrid-Electric Propulsion Achieves Key Ground Test Milestone
RTX’s integrated hybrid-electric system completes full-power testing, targeting 30% fuel efficiency gains for regional aviation through collaboration with Pratt & Whitney Canada and H55 S.A.
RTX Hybrid-Electric Flight Demonstrator: A Leap Toward Sustainable Aviation
The aviation industry stands at a pivotal juncture as it confronts the dual challenges of reducing carbon emissions and meeting increasing passenger demand. One of the most promising technological developments in this arena is hybrid-electric propulsion. In June 2025, RTX Corporation announced a significant milestone in its Hybrid-Electric Flight Demonstrator program: the successful full-power ground test of its integrated propulsion system. This achievement represents a critical step toward reducing fuel consumption and emissions in regional aviation.
Combining the capabilities of Pratt & Whitney Canada, Collins Aerospace, and H55 S.A., the demonstrator integrates a thermal engine, a 1 MW electric motor, and a 200 kWh battery system. This collaboration not only showcases engineering innovation but also reflects a broader industry trend toward electrification and sustainability. The system aims to deliver up to a 30% improvement in fuel efficiency compared to conventional turboprops, aligning with global goals for net-zero emissions by 2050.
Historical Context and Technological Evolution
Early Innovations in Electric Aviation
The journey toward hybrid-electric propulsion began over a decade ago. In 2011, Siemens, Diamond Aircraft, and EADS introduced the DA36 E-Star, the world’s first serial hybrid-electric aircraft. This experimental platform used a 70 kW electric motor powered by a Wankel engine generator, achieving a 25% reduction in fuel consumption during test flights. Though modest in scale, it marked the beginning of a new paradigm in aviation propulsion.
By 2020, Airbus and Rolls-Royce had launched the E-Fan X project, which tested a 2 MW electric motor on a BAe 146 aircraft. Although the project was eventually discontinued, it provided critical insights into high-voltage systems, thermal management, and the integration of electric propulsion into existing airframes. NASA and GE further contributed in 2022 by validating hybrid components under simulated high-altitude conditions, paving the way for scalable systems suitable for commercial use.
These early efforts laid the foundation for RTX’s demonstrator. Each project contributed valuable data, helping to improve power density, battery performance, and the overall feasibility of hybrid-electric aircraft. RTX’s current program builds on this legacy, moving from conceptual validation to practical application.
“The lessons learned from early hybrid-electric projects have been instrumental in shaping today’s more advanced demonstrators.”, Michael Winter, RTX Chief Scientist
RTX’s Strategic Electrification Roadmap
RTX has strategically positioned itself at the forefront of hybrid-electric aviation through a series of targeted investments and partnerships. In 2022, it invested in H55 S.A., a Swiss battery technology company, to develop lightweight, high-capacity battery systems. This collaboration led to the creation of the 200 kWh battery pack used in the demonstrator, featuring advanced cooling systems to prevent thermal runaway during rapid charging and discharging cycles.
In 2023, RTX joined the EU-funded SWITCH project, which aims to integrate hybrid-electric propulsion with water-enhanced turbofan technologies. The goal is to reduce CO₂ and NOₓ emissions by 50% in next-generation engines. These initiatives demonstrate RTX’s commitment to long-term sustainability and its role in shaping future propulsion architectures across multiple aircraft segments.
By aligning with both commercial and regulatory sustainability targets, RTX is not only advancing technology but also influencing industry standards and expectations. Its roadmap reflects a comprehensive approach that combines innovation, collaboration, and regulatory foresight.
Technical Achievements and Industry Collaboration
Integrated Propulsion System Architecture
The RTX Hybrid-Electric Flight Demonstrator features a tri-component propulsion system designed for performance and efficiency. The core elements include a Pratt & Whitney Canada thermal engine optimized for steady-state power, a 1 MW Collins Aerospace electric motor for supplemental thrust, and a 200 kWh battery system developed with H55 S.A. The synergy between these components is critical to achieving the program’s performance targets.
During the June 2025 ground test, the system successfully delivered 1,800 shaft horsepower, simulating a full mission profile from takeoff to cruise and recharge. The ability to transition between power sources without thermal degradation underscores the robustness of the system. This milestone validates the integrated design and opens the door for flight testing in the near future.
The battery pack’s aerospace-grade lithium-ion cells and co-developed high-voltage mobile charging unit represent significant engineering advancements. These features are essential for ensuring safety, reliability, and performance in operational environments.
Strategic Industry Partnerships
RTX’s demonstrator program is supported by a consortium of industry leaders and research institutions. AeroTEC is leading the modification and flight testing of the De Havilland Dash 8-100 testbed, ensuring compliance with airworthiness standards. GKN Aerospace has provided high-voltage wiring and interconnection systems capable of handling the 1 MW power load, while Ricardo has contributed to propulsion system integration and thermal management.
These partnerships are not merely transactional; they represent a collaborative ecosystem aimed at accelerating the commercialization of hybrid-electric technology. Each partner brings specialized expertise, creating a synergy that enhances the overall effectiveness of the program.
Such collaborations are increasingly vital as the aviation industry seeks to navigate complex technological, regulatory, and market challenges. By pooling resources and knowledge, these partnerships offer a scalable model for future innovation.
“Our role in modifying the Dash 8 ensures that cutting-edge technologies can be safely transitioned from lab to flight.”, Justin Morigeau, AeroTEC
Expanding Applications and Future Potential
RTX is already exploring new applications for its hybrid-electric architecture. In July 2024, it partnered with Airbus Helicopters to adapt the technology for the PioneerLab H145 demonstrator. This rotary-wing project aims for a 30% fuel efficiency gain by replacing one engine with a Pratt & Whitney PW210 derivative and dual 250 kW electric motors. This initiative underscores the versatility of RTX’s system across different aircraft types.
The company’s strategic vision extends beyond regional turboprops to include potential applications in urban air mobility and single-aisle commercial jets. As battery technology improves and regulatory frameworks solidify, the scalability of hybrid-electric systems will become increasingly viable.
These developments suggest a future where hybrid-electric propulsion is not a niche innovation but a mainstream solution across aviation segments. RTX’s work today is laying the groundwork for that future.
Conclusion: Charting the Path to Sustainable Flight
The RTX Hybrid-Electric Flight Demonstrator marks a significant advancement in the journey toward sustainable aviation. By achieving full-power ground test validation, the program demonstrates the technical feasibility of hybrid-electric propulsion for regional aircraft. The integration of a thermal engine, electric motor, and advanced battery system reflects a mature and scalable approach to reducing fuel consumption and emissions.
Looking ahead, the success of this program could influence the broader adoption of hybrid-electric systems across the aviation industry. While challenges remain, particularly in battery energy density, regulatory approval, and infrastructure, RTX’s collaborative model and technological leadership position it well for future success. As the industry moves toward net-zero targets, hybrid-electric propulsion will likely play a pivotal role in achieving sustainable flight.
FAQ
What is the goal of RTX’s Hybrid-Electric Flight Demonstrator?
The program aims to improve fuel efficiency by up to 30% for regional turboprops using a hybrid-electric propulsion system.
What companies are involved in the project?
Key collaborators include Pratt & Whitney Canada, Collins Aerospace, H55 S.A., AeroTEC, GKN Aerospace, and Ricardo.
When will the demonstrator begin flight testing?
Following the successful ground test in June 2025, flight testing is expected in the near future, pending regulatory approvals and additional system validations.
Sources
Photo Credit: RTX
Sustainable Aviation
SABA Members Back Infinium eSAF Facility With Long-Term Deals
Google, McKinsey, and others sign binding SAFc agreements to support Infinium Energy’s 100,000 MT/year Texas eSAF project.
Corporate members of the Sustainable Aviation Buyers Alliance (SABA) have signed binding, multi-year agreements to purchase sustainable aviation fuel certificates (SAFc) from Infinium Energy’s planned electro-sustainable aviation fuel (eSAF) facility in Texas. The commitments, announced on September 22, 2026, are designed to provide the financial demand signals necessary for Infinium to reach a final investment decision on the project.
In a press release issued by SABA, the organization confirmed that American Airlines (AA) will serve as the physical offtaker for the fuel, managing logistics and delivery. The corporate buyers purchasing the associated certificates include AVEVA, Bain & Company, Google, and McKinsey & Company. The agreement marks the first time SABA’s procurement model has been utilized to directly drive new production capacity for scalable sustainable aviation fuel.
Project Atlas production and environmental targets
Infinium Energy was selected through a SABA procurement process earlier in 2026 to provide ultra-low carbon eSAF. The fuel is produced using waste carbon dioxide and renewable energy, distinguishing it from traditional biofuel pathways that rely on agricultural or waste feedstocks.
The planned Texas facility, designated Project Atlas, is expected to have an annual sustainable aviation fuel (SAF) production capacity of 100,000 metric tons. According to the alliance, the contracted volumes will support an expected greenhouse gas abatement of 212,000 metric tons of carbon dioxide equivalent (mtCO2e). SABA equates this emissions reduction to approximately 3,500 commercial flights between John F. Kennedy International Airport (JFK) and Los Angeles International Airport (LAX).
“We’re proud to partner with SABA members including AVEVA, Bain & Company, Google, McKinsey, and others, as well as American Airlines to bring Infinium Energy’s next world scale eSAF facility to life. Their commitment reflects a shared conviction that decarbonizing aviation requires real investment in next-generation supply,” said Robert Schuetzle, CEO of Infinium Energy.
Aggregating demand through book-and-claim
The transaction utilizes a book-and-claim model. Corporate buyers purchase the SAFc to claim the environmental benefits against their business travel emissions, while the physical fuel is delivered to partner airlines. This mechanism allows corporations to fund SAF production even when the physical fuel cannot be delivered directly to the airports their employees use.
American Airlines will manage the physical integration of the eSAF into the commercial aviation fuel supply chain. Jill Blickstein, Chief Sustainability Officer at American Airlines, stated that the corporate commitments broaden participation in the SAF market and demonstrate how customers can collaborate with airlines and fuel producers to advance decarbonization.
SABA, a joint initiative of the Environmental Defense Fund (EDF), the Center for Green Market Activation (GMA), and RMI, has aggregated $500 million in SAFc demand from 35 companies to date. Aviation currently accounts for approximately 2 to 3 percent of global greenhouse gas emissions.
“Novel technologies are critical to meeting future demand for sustainable aviation fuel, but they will not be operational in time without investments made today. This procurement demonstrates how aggregated, long-term demand can help take promising eSAF projects from idea to reality,” said Jon Creyts, CEO of RMI.
AirPro News analysis
We view this agreement as a critical structural step for the eSAF market. Power-to-Liquid (PtL) fuels like those planned for Project Atlas face a steep commercialization barrier. They are highly capital-intensive to build and currently produce fuel at a significant cost premium compared to both conventional Jet A and HEFA-based SAF derived from waste fats and oils.
Airlines operate on thin margins and generally cannot absorb the full green premium of eSAF alone. By unbundling the environmental attributes from the physical fuel, the SABA model allows highly capitalized corporate entities like Google and McKinsey & Company to absorb that premium. More importantly, signing binding, multi-year offtake agreements provides the revenue certainty that infrastructure lenders require before financing first-of-a-kind industrial facilities. If Project Atlas reaches a positive final investment decision based on these contracts, it will validate the book-and-claim model as a viable financing mechanism for next-generation aerospace infrastructure.
Sources: Sustainable Aviation Buyers Alliance via PR Newswire
Photo Credit: Sustainable Aviation Buyers Alliance
Sustainable Aviation
EU Exceeds 2025 SAF Mandate at 2.79 Percent Blend Rate
EASA reports EU airports hit 2.79% SAF blend in 2025, surpassing the 2% ReFuelEU mandate with 1.1M tonnes supplied.
The European Union surpassed its initial Sustainable Aviation Fuel (SAF) mandate in 2025, with SAF accounting for 2.79 percent of all jet fuel supplied to EU airports during the first mandatory reporting year.
According to the 2026 ReFuelEU Aviation Annual Technical Report published by the European Union Aviation Safety Agency (EASA) on September 17, 2026, fuel suppliers delivered 1.1 million tonnes of SAF against a total aviation fuel supply of 39.3 million tonnes. The 2.79 percent blend rate comfortably exceeded the 2 percent minimum required by the ReFuelEU regulation for 2025. This uptake resulted in an estimated reduction of 3.77 million tonnes of CO2 equivalent greenhouse gas emissions.
“We are pleased to confirm that the SAF mandate under ReFuelEU Aviation was not only met but exceeded,” EASA Executive Director Florian Guillermet stated in the agency’s press release.
Compliance and distribution across European hubs
The EASA report indicates high compliance rates across the sector. Ninety-three percent of aircraft operators and 90 percent of fuel suppliers fulfilled their reporting obligations in 2025. EASA noted that noncompliance among aircraft operators was primarily limited to small business jet operators, nonscheduled carriers, and third-country operators that failed to respond to competent authorities.
SAF distribution reached 121 Airports across all 27 Member States, representing 79 percent of all Union airports. Uptake was heavily concentrated at major European hubs. Amsterdam Airport Schiphol (AMS) accounted for 29 percent of the tracked SAF supply, followed by Frankfurt Airport (FRA) at 8 percent and Paris Charles de Gaulle Airport (CDG) at 7 percent.
Supply chain dynamics and feedstock dependencies
While the headline blending figures demonstrate regulatory success, the technical report reveals a structural reliance on imported raw materials. Although 86 percent of the SAF supplied at EU airports was refined domestically within the European Union, 85 percent of the underlying feedstocks originated from outside the bloc.
The primary feedstock utilized was Used Cooking Oil (UCO) processed via the Hydroprocessed Esters and Fatty Acids (HEFA) pathway. Of the imported feedstocks, 61 percent originated from China, with additional volumes sourced from Malaysia and Indonesia. On the refining side, Neste’s Rotterdam facility alone produced 33 percent of all European SAF in 2025.
AirPro News analysis
The successful implementation of the 2 percent mandate in 2025 proves that the logistical framework for SAF distribution at major European hubs is functional. However, the heavy reliance on Asian Used Cooking Oil presents a long-term vulnerability for European aviation. As the ReFuelEU mandate scales to 6 percent in 2030, the Regulations will also introduce sub-mandates for synthetic aviation fuels (e-fuels). With approximately 50 synthetic fuel projects awaiting final investment decisions and no large-scale e-fuel facilities currently operational in Europe, we anticipate significant capital mobilization will be required over the next 36 months to prevent future supply bottlenecks and reduce dependency on imported biomass.
Photo Credit: European Union Aviation Safety Agency
Sustainable Aviation
Montana Renewables Cuts SAF Expansion Cost to $137M
Calumet’s Montana Renewables targets 200M gallons of SAF annually by 2028 for $137M, down from a $1.2B plan.
Calumet, Inc. and its subsidiary Montana Renewables, LLC announced a revised expansion plan on September 1, 2026, that will scale SAF production to 200 million gallons annually by 2028 for a fraction of the originally projected cost.
By repurposing existing refining equipment at the Great Falls, Montana facility, the company expects to complete the MaxSAF project with only $137 million in remaining capital. This abandons a previous $1.2 billion megaproject design. The pivot eliminates the need for third-party equity and minimizes debt while accelerating domestic sustainable aviation fuel (SAF) capacity.
Capital efficiency and Department of Energy funding
The original Phase 2 plan contemplated $1.2 billion in capital expenditure. The revised strategy captures 70 percent of the expected benefit for 15 percent of the cost. The financial restructuring involves an amended Loan Guarantee Agreement (LGA) with the U.S. Department of Energy (DOE).
The original LGA was executed in January 2025, with a $782 million first tranche funded in February 2025 to recapitalize Montana Renewables, LLC (MRL). Under the amended agreement, the company will make a final draw of $34 million. This is significantly lower than the original $658 million Phase 2 DOE funding limit.
Calumet CEO Todd Borgmann stated the Office of Energy Dominance Financing (EDF) supported the adjustment to the loan agreement.
“Our amended agreement with the DOE facilitates innovative technology and domestic energy security at a fraction of the original cost. EDF’s willingness to right-size the LGA reflects its ongoing support for Montana’s largest agricultural investment. We look forward to our continued collaboration with the DOE on the success of this project,” Borgmann said.
Borgmann credited the company’s engineering and operational teams for developing a project that maximizes output while drastically reducing the required capital investment.
Production timeline and capacity milestones
The Great Falls facility currently operates at a 60 million gallon SAF run-rate following a spring 2026 constraint removal. A scheduled turnaround in the fourth quarter of 2026 will tie in repurposed equipment from the adjacent Calumet Montana Refining facility.
Following the fourth-quarter integration, the company expects to exceed an 80 million gallon SAF run-rate by December 31, 2026. Production is projected to surpass 120 million gallons by spring 2027 and reach the 200 million gallon target by December 31, 2028.
Total renewable product sales, including renewable diesel and renewable gasoline, are targeted at 17,000 barrels per day by year-end 2028. This represents a 40 percent expansion. The expanded facility will consume 2 billion pounds of ranch- and farm-originated feedstocks annually.
AirPro News analysis
The revised MaxSAF expansion highlights a strategic shift in how producers approach SAF scaling. As noted by Aviation Week on September 2, 2026, the plan allows the largest US producer of SAF to more than triple its production capacity for barely 10 percent of the originally planned investment.
During Calumet’s second-quarter 2026 earnings call on August 7, 2026, the company confirmed that Montana Renewables completed performance testing of the newly installed MaxSAF catalyst, which met or exceeded expectations. By leveraging existing fossil-fuel infrastructure rather than pursuing multi-billion-dollar greenfield projects, producers can bring SAF to market faster and with significantly lower financial risk. This capital-efficient model may set a precedent for other refiners looking to enter or expand in the renewable fuels sector without diluting equity or taking on unsustainable debt.
Sources: Calumet, Inc.
Photo Credit: Montana Renewables
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