SAF’s Billion-Ton Question

by Luke Geiver (Ethanol Producer Magazine) This spring, the U.S. Department of Energy air-dropped a report that should give the nascent sustainable aviation fuel (SAF) industry a massive crate of confidence. With the release of the 4th installment of a decades-old study designed to highlight the available volume of biomass in the U.S. suitable for bioenergy and bioproduct production, the DOE answered a big question about the future of SAF: Is there enough biomass to produce it commercially, long-term, at scale?

“We did not set out to find a billion tons of biomass,” said Mark Elless, technology manager for the Bioenergy Technologies Office of Renewable Carbon Resources at DOE, when asked about the objective of the latest 2023 Billion-Ton Report released in early 2024. In fact, the large team that worked on the Biomass Resource Availability Study actually found that the U.S. has closer to 1.5 billion tons of biomass available for use as feedstock for a wide range of applications.

Valerie Sarisky-Reed, director of the Bioenergy Technologies Office (BETO), talked directly about the implications of the report in relation to that SAF Grand Challenge.

“The goal of meeting 100% of U.S. aviation fuel needs has been set for 2050, and that's projected to be approximately 35 billion gallons,” Sarisky-Reed said. “The Billion-Ton Report shows that this resource can indeed be met sustainably.”

Apparent SAF Focus
The BT23 is designed to be policy and end-use agnostic, according to Elless. But during the report-release webinar outlining the main takeaways, three of the four presenters spoke to what the report means for SAF production in their opening statements.

“This resource assessment could really be considered to be conservative,” Sarisky-Reed said. “In other words, there is more biomass resource potentially available in the U.S. than we’re accounting for because of the overlying sustainability constraints.”

Langholtz explained that the assessment was intended to be a survey of primarily existing biomass-producing industries. “This report doesn’t say how much biomass should go to SAF,” he said. “It explores an end-use agnostic, overall production capacity. But certainly, production demands for SAF and other decarbonization goals could be realized with the capacity we have here.”

By the numbers, the amount of biomass available in the U.S. right now is between 1.1 to 1.5 billion tons from the following sources: food waste, municipal solid waste, agricultural and forest wastes, animal wastes and energy crops. If every ton of available biomass was utilized, 15% of future U.S. energy needs could be met. Certain factors, like sustainability, economic viability in the context of near-term conditions, along with other variables, helped determine if a biomass resource should be included in the available tonnage amount.

The report team did note multiple examples of uncertainty in their assessment, including: product-specific market demands (which might incentivize a mix of energy crops different from those included in the report); the adoption of premiums, which could cause prices to vary over time and by region; short-stature corn, which could present unknown impacts to residue availability; progress in waste reduction; and changes in future energy profiles.

Two themes were observed throughout the RFI responses, BETO said. First, a clear need exists for long-term, stable policy to serve as an indicator of regulatory certainty for the industry. Second, stakeholder coalitions can and should provide a functional platform for collaboration and engagement among a diverse set of supply chain participants.

Some want an SAF registry to enable the sharing of key fuel documentation and attributes.

The creation of a tool to identify resources and availability of SAF would also be beneficial for the overall supply chain buildout.

A list of constraints or barriers to the advancement of SAF and its supply chain were long. There are issues with short-term policy timelines, including many incentives that sunset before some SAF facilities can even be built. There is competition between state incentives. There are also inconsistent definitions of renewable biomass within legislation, commenters said.

“For example,” one RFI participant stated, “differences between the RFS program’s definition of renewable biomass and the U.S. Forest Service’s wildfire crisis 10-year strategy means a difference of tens of millions of tons of biomass per year available for SAF production.”

Carbon-intensity (CI) scoring presents an issue for new feedstocks not used in large volumes before. Technology compatibility will take time for new or novel pieces to be tested. And some of the newest technology products—like electrolyzers used in hydrogen production—require long wait times of 18 to 24 months.

Another issue called out in the RFI work by BETO was related to pre-commercial demonstration requirements. Many new technologies using novel catalysts, reactors and process configurations need to go through a demonstration phase. “Not only is the demonstration of these complex integrated processes an extremely challenging undertaking, but these must also be carried out in different geographic locations to validate opportunities from diversified feedstock sources,” which the commenter noted, “introduces entirely new challenges.” READ MORE