From SAF Re-Ups to Paper Cups: Delta's Sustainable 2025

Delta’s centennial year was not a time for looking back at the past. In fact, in the hundred years since its founding in Macon, Georgia, US, the airline has rarely had such a progressive 12 months.

Across 2025, Delta made good progress against its fuel efficiency targets, it struck up some partnerships to develop cutting-edge prototypes of planes and cut down on the use of unsustainable materials across its flights too.

The carrier, which is now based in Atlanta, also surpassed its near-term fuel savings goal, delivering more than 55 million gallons of jet fuel savings from operational improvements in Q1 alone.

It’s an achievement that has helped save the firm more than US$125m, as well as move the dial on its pursuit of net zero.

Delta’s focus on improving efficiency

Delta's cross-enterprise Carbon Council was instrumental in the savings it made on fuel in 2025. 

The council implemented a few important measures to this end, including weight reduction on board, technology to track and reduce Auxiliary Power Unit usage between flights, optimised aircraft speed and routing, new landing procedures and drag reduction technologies like ‘winglets’.

Though the impacts of these initiatives are fairly small in isolation, together they helped to make a good dent in Delta’s emissions.

The US-based airline also launched a programme called ‘Green Station of the Year’ in an effort to encourage its employees to change behaviours and contribute to fuel savings in their day-to-day work.

Thanks to this programme, lots of Delta’s frontline team members are now competing against one another to see who can be most sustainable.

Partnerships in aircraft design

In March, Delta announced that it had partnered up with aerospace start-up JetZero, providing support for its development of blended wing-body (BWB) aircraft.

This futuristic looking plane is expected to be up to 50% more fuel efficient than the average aircraft in operation today.

Delta is providing JetZero with operational expertise through its Sustainable Skies Lab to bring the BWB aircraft closer to commercial viability.

In September, Delta joined up with Maeve Aerospace to help it expedite the development of hybrid electric aircraft for regional flights.

Compared to today's regional aircraft designs, Maeve's aircraft aims to reduce fuel consumption and emissions by up to 40% using conventional jet fuel, with further lifecycle emissions reductions possible when using SAF.

“As we work toward the next generation of aircraft, we look to partners like Maeve who embody the bold, forward-thinking innovation we champion at Delta – solutions that advance aircraft design, enhance operational efficiency, elevate employee and customer experiences, and cut emissions,” says Kristen Bojko, Vice President of Fleet at Delta Air Lines.

A year of unusual innovations

Elsewhere, Delta decided to deepen its working relationship with Airbus. This renewed collaboration saw the two companies test fello'fly – a flying technique inspired by migrating geese that pairs flights to improve fuel efficiency.

Using this technique, a pair of aircraft fly concurrently, with one creating an uplift that can markedly improve the fuel efficiency of the other. 

Airbus says that the practice can reduce fuel consumption by 5% on long-haul flights.

Delta also added MicroTau to its Sustainable Skies Lab. MicroTau is an Australian aerospace technology company that is known for creating external cladding for planes that mimics shark skin. This, the start-up says, reduces drag and saves fuel.

The technology can be applied to an aircraft's fuselage, wings and tail and may improve fuel efficiency by up to 4% according to MicroTau's estimations.

Delta is also testing finlets, fins similar to those fish have, that can be installed on the back of an aircraft on the fuselage to reshape airflow and reduce drag.

The carrier finalised modifications of the split-scimitar winglet upgrade on its 737-800 fleet this year, marking the completion of adding the most advanced winglet technology available to all existing fleets that can be modified.

Delta’s investments in SAF

Delta says it is on track to increase its usage of sustainable aviation fuel by 50% compared to last year.

In 2025, the carrier collaborated with the likes of Shell Aviation, Montana Renewables and the Port of Portland on a project that saw the first-ever commercial scale delivery of SAF to an airport – Portland International Airport.

According to Airbus, SAF can reduce an airline’s emissions by up to 80% and has the potential to deliver net negative emissions in certain circumstances.

The problem with SAF has always been supply, though. Currently, there isn't enough available to meet global demand for even a week.

Investments from the likes of Delta will be crucial in scaling the fuel as time goes by.

Thanks to its forward-thinking approach this year, Delta was named one of the world's Most Innovative Companies by Fast Company for the fifth time, ranking number three in the Corporate Social Responsibility category for its efforts on SAF.

A new generation of aircraft

One of Delta’s main goals this year has been to procure more than 35 sustainable aircraft. 

Though 2026 is just around the corner, the company says that it is on track to do so. 

On average, these new planes are more than 25% more fuel efficient per seat mile than the aircraft Delta has retired since 2019.

With approximately 90% of Delta's carbon emissions coming from jet fuel each year, the airline is keeping its focus on those modifications that are within its control while the next generation of aircraft and supporting technologies become more mature and more accessible.

Creating a more sustainable travel experience

Keeping with that same thinking, Delta officially rolled out a new range of paper cups across its entire operation this year, replacing plastic cups for all flights.

The airline began final testing of the cups on transcontinental domestic flights in 2023, completing testing in 2024 before teams worked through inventory, supply chain and logistics to make the transition possible.

The Georgia-based company also opened new facilities at Seattle-Tacoma International - the Delta One Lounge and a second Delta Sky Club.

Both these areas were created with sustainability in mind and include smart windows that adjust to sunlight, all-electric energy with motion-sensing lights and reusable dinnerware to reduce waste.

The airline also partnered with Green Taxi Aerospace to explore electric taxiing technology that aims to reduce fuel use, operating costs, taxi time and carbon emissions.

All in all, the 100-year anniversary of Delta has been a whirlwind – appropriately peppered with moments for celebration when it comes to sustainability.

“As Delta Air Lines closes out its centennial year, we’re proud to share the meaningful steps we’ve taken toward a more sustainable future of flight,” says Amelia DeLuca, Chief Sustainability Officer at Delta.

“These milestones reflect Delta’s commitment to transforming the future of flight.”