En Route to Market: Alder Fuels and NREL Partner to Scale Sustainable Aviation Fuel Technology for Commercial Use

by Erik F. Ringle (National Renewable Energy Laboratory) A critical pathway for producing large quantities of low- to negative-carbon sustainable aviation fuel (SAF) is en route to market following a collaborative research and development agreement between the National Renewable Energy Laboratory (NREL) and Alder Fuels.

The technology—an advanced pyrolysis process that converts biomass into refinery-ready biocrude oil—is backed by millions of dollars in funding from United Airlines, Honeywell UOP, AvFuel, the U.S. Department of Defense, and the U.S. Department of Energy's (DOE's) Bioenergy Technologies Office.

"Climate alarm bells are being triggered every day around the globe," said Zia Abdullah, NREL biomass laboratory program manager. "In recognition of that reality, this agreement is a firm step for swiftly slashing the carbon impact of aviation in less than a decade. Even more than that, it shows how NREL can supply bold solutions for accelerating total aviation decarbonization."

According to Bryan Sherbacow, president and CEO of Alder Fuels, the partnership represents a giant step toward realizing the promise of climate-friendly SAF at scale.

"The United States has the potential to demonstrate to the world that we can think boldly and meet this challenge head on," he said. "The industry appetite to embrace the change is there, and we're at a tipping point. The next public-private push is going to make all the difference."

How To Scale SAF Production? Uncompromising Analysis With Critical Decision-Making

These technological breakthroughs underwrite United Airlines' commitment to buy 1.5 billion gallons of additional SAF over the next 20 years—one of the largest commercial investments in renewable energy in aviation history. Since then, the company has also announced additional partnerships with aviation leaders Avfuel and Boeing.

The success is a testament to the rigor of NREL and Alder Fuels' "stage gate" development process. The meticulous approach enables partners to pause and think critically about the engineering and commercial readiness of the technology. That way, partners can determine if it should proceed to the next phase of development.

"NREL are the leaders when it comes to developing cutting-edge research and rigorous technical audits that can advance our collective journey towards a sustainable future," Sherbacow said. "We're so excited to team up with them and to get their expertise as we successfully test and evaluate every step of our conversion process."

Indeed, although SAF technologies may be reaching the tipping point to commercialization, uncompromising analysis is key for readying them for adoption at airports across the country.

For example, NREL and Alder Fuels continue to develop and mature a novel recipe for making carbon-negative SAF from wet waste, a low-cost resource that includes food waste, animal manure, sewage, and inedible fats, oils, and greases. First described in a leading scientific journal in early 2021, that technology continues to edge closer to market adoption.

According to Alder Fuels Chief Technology Officer Derek Vardon, the close public-private partnership between NREL and Alder Fuels promotes technical readiness and commercial viability.

"NREL has brought the brightest scientific minds in the world together to focus on the challenge of turning bio-based and waste feedstocks into low-carbon fuels for aviation," he said. "Bringing industry leaders to the table, particularly our partners at Honeywell UOP, we at Alder Fuels are committed to convening a powerhouse public–private team to make our technology a scalable commercial reality."

SAF production is cited as a core strategy in the Biden–Harris administration's goals to reduce aviation emissions 20% by 2030 and reach zero emissions by 2050. Because SAF is made from a wide range of renewable biomass and waste resources, the fuel can net deep reductions in GHG (greenhouse gas) emissions compared to conventional jet fuel.

Analysis by NREL shows that Alder Fuels' greencrude technology—which includes NREL's SAF from wet waste and Alder's advanced pyrolysis technology—can make energy-dense liquid fuels with a negative carbon footprint. When blended with conventional jet fuel in high volumes—up to 100%—the resulting fuel could support net-zero-carbon flight.

Alder Fuels' pyrolysis technology uses only residual materials—such as sugarcane bagasse or sustainably harvested forestry waste—or purpose-grown grasses that can be planted on marginal land not suitable for growing food. Such perennial grasses, like miscanthus, can reverse desertification by restoring nutrients to the earth and building soil. Furthermore, by converting wet waste into greencrude—the precursor for converted SAF—Alder Fuel's technology avoids landfill methane emissions, a climate pollutant 20 times more potent than carbon dioxide.

NREL's partnership with Alder Fuels is one example of its numerous research and development projects that support a sustainable aviation future. With access to world-class lab spaces, NREL scientists are sought after for their expertise and analysis on biofuels.

"Partnerships like the one between NREL and Alder are essential to meeting the goals of the U.S. Sustainable Aviation Fuel Grand Challenge," said Valerie Reed, director of the DOE Bioenergy Technologies Office. "DOE is committed to pursuing technology demonstrations that will decarbonize the economy, including aviation."

"We see these efforts directly translating to more SAF at airports across the country," Abdullah said. "That is transformational. To decarbonize aviation by mid-century, our success will be measured by the gallon."