Estimates of Sustainable Aviation Fuel Production Capacity at U.S. Renewable Diesel Plants Through 2026

by Maria Gerveni, Scott Irwin, Todd Hubbs and Steven Ramsey (farmdoc daily) ... However, there is only one feasible pathway at the present time for ramping up SAF production quickly. This is through the conversion of part, or all, of the production capacity at existing or soon to be completed renewable diesel plants. Renewable diesel production capacity in the U.S. has exploded in recent years and is estimated to reach 5.2 billion gallons in 2025 (farmdoc daily, November 6, 2024). While this represents a large installed base of production capacity, there is limited information available on precisely how much of this capacity could be converted to SAF production. Hence, the purpose of this article is to estimate the volume of renewable diesel production capacity in the U.S. that has the potential to be converted to SAF production through 2026. This is the 20th in a series of farmdoc daily articles on the renewable diesel boom (see the complete list of articles here).

Analysis

The vast majority of renewable diesel in the U.S. is fully refined and cracked using HEFA (hydrotreated esters and fatty acids) petroleum refining technology. For a detailed discussion about this production technology, see the farmdoc daily article from February 8, 2023). Our latest estimates of HEFA renewable diesel plant capacity in the U.S. are shown in Table 1. Several sources are used. For 2020 through 2023, we use the list of plants and capacities collected by the Energy Information Agency (EIA) in its annual survey of nameplate production capacity. ... If no other data were available, we used the 2023 EIA survey results.

HEFA renewable diesel plants can be constructed with the option of refining crude oil instead of organic fats and oils. To the best of our knowledge, only one renewable diesel plant has exercised this optionality. The 184-million gallon Chevron USA renewable diesel plant in El Segundo, California announced last year that it was switching to refining crude oil due to poor margins in renewable diesel.

The second optionality that can be built into HEFA renewable diesel plants is to produce SAF. This optionality can range from using a modest part of a plant’s capacity to produce SAF to making SAF the main output of the plant. It is important to differentiate this type of optionality from the small amount of SAF that is a normal by-product of renewable diesel production. In addition, the same vegetable oil and animal fat feedstocks are used whether renewable diesel or SAF is produced in the plant.

There are two other important considerations in the decision to exercise SAF optionality for a HEFA renewable diesel plant. First, there is a loss in throughput for each gallon of SAF that is produced. Industry sources indicate that renewable diesel production capacity is lowered by approximately 1.125 gallons for each gallon of SAF produced.

Second, production of SAF results in higher volumes of lower valued co-products such as naptha and fuel gas.

We find that the bulk of optional SAF capacity at renewable diesel plants is of quite recent vintage. Before 2024, only two plants had the option to produce SAF as a primary output and capacity totaled 67.3 million gallons. This jumped sharply to five plants in 2024 with 648.9 million gallons of capacity and then to six plants with 834.4 million gallons in 2025 and 2026. It is noteworthy that total renewable diesel production capacity in the U.S. in 2025 and 2026 could range from 4.325 to 5.261 billion gallons, depending on the level of capacity that is devoted to SAF production. If SAF optionality is at the maximum in these two years, projected renewable diesel production capacity would be reduced by nearly 20 percent.

References

Gerveni, M., T. Hubbs and S. Irwin. "Biodiesel and Renewable Diesel: What’s the Difference?" farmdoc daily (13):22, Department of Agricultural and Consumer Economics, University of Illinois at Urbana-Champaign, February 8, 2023.

Troderman, J., and E. Shi. “Domestic Renewable Diesel Capacity Could More Than Double through 2025.” Today in Energy, U.S. Energy Information Administration, February 2, 2023. https://www.eia.gov/todayinenergy/detail.php?id=55399