With aviation accounting for nearly 10% of U.S. transportation GHG emissions and approximately 3% of total U.S. emissions, according to the EPA, companies are committed to a future of renewables and sustainable practices to decarbonize the industry.
Hannah Zunker, manager of training for Diamond Green Diesel (DGD), said DGD — a 50/50 JV between Valero Energy and Darling Ingredients — is one of the largest producers of renewable fuels in the world.
"Valero brings a tremendous amount of expertise on the fuels manufacturing side of the business while Darling brings expertise on the feedstock side of the business," Zunker said, serving as a panelist during the 2025 AFPM Annual Meeting in San Antonio.
DGD commenced production of renewable diesel in 2013 with its first train of renewable fuels and has continued to grow its renewables portfolio with many expansions and new facilities in the past four years. This includes DGD’s facility just outside of New Orleans, which was optimized, expanded and expanded again to about 290m gal of DGD a year, Zunker said. After Hurricane Ida in 2021, the DGD 2 facility increased renewable fuels production to 730m gal overall. Additionally, Zunker said the company added a renewable gasoline unit, which is tracked separately from its other fuels.
Diamond Green expands SAF; Delta, Honeywell highlight consumer, tech strategies
From left are Masato Webb with Delta, Hannah Zunker with DGD, moderator Jeff Coleman with PBF Energy and Keith Couch with Honeywell UOP.
In 2022, DGD opened a new plant in Port Arthur, Texas, which raised its output to more than 1.2 billion gal/yr of renewable fuel, followed by the Q4 2024 addition of its first SAF unit to come online.
"We run the typical mix of feedstocks you would see in that space, used cooking oils, animal fats … distillers corn oil or technical corn oil, depending on which part of the world you come from and what you call it," Zunker said.
Masato Webb, program manager of SAF for Delta Airlines who also spoke on the AFPM panel, said the company is committed to decarbonization strategies. Using a twopronged sustainability approach, Webb said Delta starts with the travel experience.
"We are a commercial airline, and we see that our customers expect us to put decarbonization first in the work we’re doing," Webb said.
The second prong of Delta’s approach involves aircraft operations. Specifically, the Delta Carbon Council, an internal initiative focused on implementing fuel-saving measures, has saved more than 30m gal of jet fuel through more efficient flying, he said, by retiring aircraft not meeting that goal.
Rounding out the panel, Keith Couch of Honeywell UOP emphasized that while sustainability is key, SAF must also be financially viable to earn shareholder approval.
He stressed that reducing capital and operating costs — through smarter technology and more efficient use of resources — is critical to scaling SAF production. "We have to start treating utilities like scarce resources," he said, adding that success depends on putting the right molecules into the right process units with minimal energy use.
He noted that global policy differences and limited feedstock availability are major hurdles, and that affordability is essential to scale up production.
Couch highlighted the wide range of SAF production technologies being explored, from ethanol-to-jet and alcohol-to-jet to biomass and e-fuels. He said no single method will dominate and that feedstock access, regional policies and cost will determine which projects succeed.
He also pointed out that newer pathways like e-fuels are extremely expensive, requiring billions in investment and massive amounts of power. While some projects are moving forward, he stressed that continued innovation is critical to lowering costs and making these options feasible at scale.
