Stephen Kramer was skeptical when discussions around sustainable aviation fuel (SAF) first began in 2006. Achieving advancements in sustainability through fuel research and essentially changing aviation were ambitious goals – even for a single industry with the reach of aviation.
“I changed my mind when the Secretary of Agriculture committed to not only work with us but stated that SAF was critical to the U.S. farm economy,” said Kramer, a combustor technology manager at Pratt & Whitney, a Raytheon Technologies business. “I’ve always been an environmentalist, but when I saw that I could help Pratt & Whitney make a difference, well, I think a lot of us became convinced.”
SAF is derived from crops, captured CO2 and waste that would otherwise go to a landfill or be incinerated, such as packaging, textiles, paper, food scraps and cooking oil. It is cleaner and more thermally stable than petroleum-based Jet A/A-1 and will be a key enabler as aviation moves closer to the ultimate goal of reaching net-zero emissions by 2050.
All Pratt & Whitney engines are compatible with 50% SAF. Today, Pratt & Whitney’s engineers continue this industry leadership with next-generation propulsion technologies that will further reduce carbon emissions, including ultra-high bypass ratio and thermally efficient engines, hybrid electric and hydrogen-powered engines.
“To say it has become an exciting change over time doesn’t begin to capture the work being done,” said Margaret Adamson, a fuels specialist at Pratt & Whitney. The challenge, she added, is defining the standard of the SAFs. “With the positive effects of further developing SAF clear, you are seeing incentives and industries such as big oil now get involved.”
The business and environmental incentives to keep driving SAF development are great. For wide-body aircraft, taxes on jet fuel are now in place in five European nations, with plans to gradually expand that tax to the entire European Union. There is also increasing demand for improvements in efficiency and emissions in the business, regional and general aviation markets as well.
The GTF engine is at the forefront of Pratt & Whitney’s sustainability drive. Pratt & Whitney pioneered an industry first with its geared fan architecture, enabling a 16% to 20% step change in fuel efficiency, which since 2016 has already saved more than 5 million tonnes of CO2, relative to the existing fleet; but, as the team points out, P&W has only just begun to tap the potential of this technology.
Recently, Pratt & Whitney introduced the GTF Advantage configuration that reduces fuel consumption by an additional 1%, extending the engine’s lead as the most efficient powerplant for the A320neo family. In total, the engine decreases fuel and CO2 emissions by 17% compared to prior generation engines. Additionally, the GTF Advantage engine will be compatible with 100% SAF at entry into service, helping the industry meet its 2050 net-zero commitment.
“This is why I became an engineer,” said Sustainability Fellow Sean Bradshaw. “Jet engines continue to evolve and with sustainable fuels it’s a chance to be a part of something great. The fact that the engines we build today can fly on SAF means we are on a path to increase future engine ability to run on even more advanced, sustainable fuels of the future.”