Are We Finally At a Tipping Point for Sustainable Aviation Fuel?

Sustainable air travel is an elusive goal. Zero-emission electric aircraft have begun to emerge, but only at a small scale and for short distances. Bio-based sustainable aviation fuel offers the potential for more rapid scale-up because it can be blended with conventional jet fuel for use in existing aircraft and fueling infrastructure. Until recently, sustainable aviation fuel was only available in limited quantities, but new supplies may soon change that. 

The slow pace of sustainable aviation fuel uptake

Sustainable aviation fuel (SAF)  stakeholders have experimented with many different kinds of bio-based sources since the early 2000s, including algae, food waste, and agricultural and forest waste, along with cultivated energy crops including oilseeds and grasses as well as corn and soy.

But progress is moving at a snail’s pace. United Airlines, for example, became the first major airline to test sustainable aviation fuel back in 2009 and since then has explored various bio-based sources including algae. The company says it has invested in the “future production” of more than 5 billion gallons of sustainable aviation fuel, but achieving that scale is a long-term goal.

In the meantime, United advises that “production remains very limited,” and very expensive as well, and the airline is not alone. Sustainable aviation fuel accounted for less than 0.15 percent of the total fuel used among 77 leading airlines last year, according to a survey from the European organization Transport & Environment.

Corn, soy oil, and other cultivated crops accounted for more than 30 percent of the sustainable aviation fuel used among the airlines T&E surveyed, indicating that agriculture-related carbon emissions could offset much of the gains from using bio-based resources. In addition, 100 percent bio-based fuel is not a complete solution. Also called “neat” SAF, 100 percent bio-based sustainable aviation fuel is not certified for use on its own. Instead, it is blended with conventional jet fuel, making it all the more important to keep agricultural supply chain emissions down to a minimum.

The electrofuels solution

Electrofuels are an alternative solution that is gaining ground. Sometimes called solar fuels or e-fuels, electrofuels are synthetic hydrocarbon fuels produced by deploying electricity — ideally from solar power or other renewable resources — to separate green hydrogen gas from water. The hydrogen is then combined with captured carbon to create new fuels that are chemically identical to fossil-sourced fuels, meaning they can be used on their own on a drop-in basis instead of blending with conventional jet fuels.

Although cost is an obstacle, some analysts project the price of green hydrogen will dip to a competitive level by 2030.

United is among the aviation stakeholders signaling that the electrofuels pathway is a promising one. Last month, the company's United Airlines Ventures Sustainable Flight Fund invested in the U.S. electrofuels startup Twelve. The startup describes its green hydrogen process as a form of artificial photosynthesis, deploying renewable energy to produce sustainable aviation fuel from carbon dioxide and water, yielding a potential cut of 90 percent in lifecycle carbon emissions compared to conventional jet fuel.

With additional funding in hand, Twelve plans to begin producing fuel at a plant in Moses Lake, Washington, later this year and aims for an output of 50,000 gallons annually. The company also entered a 14-year contract with a five-airline group in Europe, to be named later, for a total of 260 million gallons of fuel.

More sustainable aviation fuel is on the way

Bio-based sustainable aviation fuel ventures also continue to attract investors and public funding.

The U.S. Energy Information Administration (EIA) recently noted a sharp increase in production of what it classifies as "Other Biofuels," which practically doubled from December 2024 to February 2025. “Other Biofuels” include renewable heating oil and emerging biofuels, but the EIA notes that sustainable aviation fuel is beginning to dominate the category, making it a useful indication of activity in this sector. “With [sustainable aviation fuel] production capacity now around 30,000 [barrels per day] and growing in 2025, SAF will likely drive significant growth ... and make up most of U.S. Other Biofuels production,” EIA reported. 

Among the recent projects the agency highlighted is a 15,000 barrel-per-day facility in Texas under the umbrella of Diamond Green Diesel, a joint venture of Valero Energy and the firm Darling Ingredients, which focuses on producing biofuels from animal fats, used cooking oil and food waste among other sources. 

Another newly operational project comes from New Rise Renewables, which converted a former biodiesel operation in Nevada to produce sustainable aviation fuel. The company, a branch of the firm XCF Global, began producing fuel at the facility in February at a rate of 3,000 barrels per day. XCF says a third-party buyer has already contracted for more than 3 million gallons.

Meanwhile, the Montana Renewables branch of Calumet is now producing sustainable aviation fuel at its facility in Great Falls, Montana. “Montana Renewables expects to reach 120- to 150-million-gallon SAF capacity sooner than previously reported for a fraction of the cost,” Calumet reported in May, citing its experience over the past two years as the main factor enabling the facility to expand while cutting costs. The company says it's on track to reach a capacity of up to 300 million gallons per year by 2028.

The expansion of Montana Renewables is particularly noteworthy because it is one of few renewable energy projects supported by the Donald Trump administration. To help finance the expansion, Montana Renewables applied for and received a loan guarantee of $1.44 billion from the U.S. Department of Energy. The transaction was closed during the final days of the Joe Biden administration. On Feb. 18, almost a month after President Trump took office, Calumet announced that the first drawdown of $782 million was authorized by the Energy Department.

That may appear remarkable, considering the president’s efforts to promote fossil energy resources while quashing federal support for wind and solar energy. Still, when the president announced his “Unleashing American Energy Dominance” plan, biofuels were listed among the domestic energy resources to receive priority treatment alongside hydropower and nuclear energy and, of course, oil, natural gas and coal.