Propulsion Technology And SAF Are Fastest Path To Decarbonize Aviation

This year Dubai plays center stage to a series of critical global gatherings which will address sustainability both in our industry and across the wider world, with CAAF/3 and COP28. CAAF/3 will bring together ICAO and industry leaders to encourage government policies and initiatives to stimulate investment in new SAF production and feedstock technologies which are needed to dramatically increase availability and reduce costs.  With just over 26 years to reach our industry’s goal of net-zero carbon emissions, and with demand for aviation expected to more than double over the same period, the time to accelerate initiatives for sustainable aviation is now.

At Pratt & Whitney, and across RTX, we are determined to continually drive emissions reductions for today’s fleet, while also developing the technologies that will make future generations of aircraft even more efficient. Improving efficiency and unlocking new energy sources has always been at the core of our mission, driven by the need to enable sustainable growth in our industry, so the benefits of aviation can continue to be enjoyed to an ever-larger portion of the world’s population.

Technological advancements have already enabled aircraft engines to improve fuel burn by on average 1% per year since the dawn of the jet age, and it is a trend we are determined to continue across all our commercial product families. For example, our expanding PW127XT engine series delivers 3% improved fuel burn and reduced emissions, along with 40% improved time on wing compared to the previous regional turboprop standard. Similarly, our GTF Advantage engine will extend the efficiency of the GTF engine by up to 1%, thereby making it up to 17% more efficient than previous generation engines. Applied across the fleet, these improvements will add to the 1.4 billion gallons of fuel and 14 million metric tons of CO₂ emissions saved by GTF engines since entry into service in 2016. In addition, since GTF Advantage engines will be compatible with 100% SAF, they’ll be ready to reduce lifecycle emissions even further.

To enable the next “big step” in efficiency, more advanced aircraft propulsion technologies will take time to develop and deploy at scale. This is why SAF is so critical for reaching the net-zero goal. As a “drop in” solution, SAF will enable us to reduce the environmental impact of aircraft flying today and in the coming decades. Supply is well short of what the industry needs, but momentum is building behind airline demand, energy companies and supporting government policies, which could improve incentives for financing the required investments in production infrastructure. CAAF/3 provides a key opportunity to accelerate momentum by recognizing the importance of balanced policies that will enable production ramp-up and by aligning on a global a SAF accounting framework. ICAO’s vision of an 80% reduction in carbon intensity from the use of SAF in 2050, compared to traditional fossil fuel, provides the needed impetus for development.

While we continue to ensure our engines are compatible with current and future SAF specifications through a comprehensive testing program, preparing for a future where SAF is more readily available, we are looking at a broad range of advanced technologies to insert into future engine models.

We’re particularly excited about hybrid-electric propulsion, which draws on the extensive expertise across RTX businesses, with Pratt & Whitney and Collins Aerospace working closely across multiple key demonstrator programs. Adding to its decades long expertise in electric systems, Collins Aerospace recently opened a new state-of-the-art development facility at Rockford, Illinois, called “The Grid”, which will help propel our testing of high-powered, megawatt-class electric motors and generators, and electrical distribution systems.

But what will we do with all these megawatts of power? By integrating electric motors with gas-burning thermal engines, we see considerable opportunities to optimize efficiency across the whole flight cycle of an aircraft, bringing significant benefits in terms efficiency and emissions reduction. For the RTX hybrid-electric flight demonstrator, led by Pratt & Whitney Canada, we are targeting a 30% improvement in efficiency compared to today’s most advanced regional turboprops. And with the SWITCH project (Sustainable Water Injecting Turbofan Comprising Hybrid-Electrics) – which includes MTU Aero Engines, GKN Aerospace, and Airbus as collaborators – we are developing a hybrid-electric GTF demonstrator engine, which could support future short and medium range aircraft.

We’re making good progress. The hybrid-electric flight demonstrator completed its first engine run in December 2022, and we are targeting flight tests to begin in 2024. A smaller scale program, STEP-Tech (Scalable Turbo-electric Powertrain Technology) also completed its first engine run and electrical system integration test earlier this summer. While fuel burning, all our hybrid-electric technologies will be compatible with 100% SAF, as well as other alternative fuels like hydrogen. As we transition away from fossil fuels to potentially more costly alternatives, the additional efficiencies of hybrid-electric propulsion will be even more valuable.

Hydrogen, perhaps the ideal fuel for zero carbon emissions flight, presents considerable challenges, but we also see significant opportunities to unlock additional efficiencies. The HySIITE (Hydrogen Steam Injected, Inter‐Cooled Turbine Engine) concept takes full advantage of the qualities of for liquid hydrogen fuel to enable up to 35% more efficiency and 80% less NOx than today’s most efficient single aisle aircraft.

Across all these projects, industry collaboration is key, especially through the multiple public/private partnerships now directed at addressing aviation’s emissions challenge. Whether the RTX Hybrid-Electric Flight Demonstrator, supported by the governments of Canada and Quebec, or the SWITCH project, supported by the European Union’s Clean Aviation initiative, these ventures will help accelerate the demonstration of novel technologies which could bring benefits to our industry and the wider world.

Combined, these programs will help mature new components and technologies. We recognize there is no single path to getting to net-zero so we actively collaborate with industry partners around the globe on technologies that reduce fuel consumption, advanced materials that can withstand higher temperatures, and on demonstrator programs with novel aircraft designs such as blended wing body and transonic truss-braced wing. We have a clear roadmap to achieving the industry’s goals, delivering value for our customers, and securing the future of sustainable aviation.  Learn More