The Catalyst Review January 2025 - 3

Independent Perspective
The views expressed are those of the individual author and may not reflect those of The Catalyst Review or TCGR.
Is SAF a Potential Safer Harbor in Renewable Fuels?
By Woody Shiflett
Significant market shifts in the renewable fuels arena suggest it is not for investors faint of heart. US D4 Renewable
Identification Numbers (RIN) have fallen 70% in value since early 2023, and even California Low Carbon Fuel
Standard (LCFS) credits dropped 50% from May 2023 to May 2024. Biodiesel (BD) and renewable diesel (RD)
have been in oversupply in the EU owing to Chinese imports flooding the market, major projects have stalled,
and BD plants have been idled. In North America, a major renewables refinery may shut down, several BD plants
have closed, and one large RD unit repurposed from fossil fuel production to RD returned to production of fossil
fuels.1,2,3 In contrast to such headwinds, the International Air Transport Association (IATA) issued an aggressive
recommendation to reduce aviation carbon intensity by 5% by 2030, targeting 17.5 billion litres/year (300,000
barrels/day) of sustainable aviation fuel (SAF). The International Civil Aviation Organization (ICAO) tracks
announced SAF offtake agreements between airlines and SAF suppliers.4 These total some 53 billion liters, with
some 65 agreements being five years or longer and 25 ten years or longer. The more global nature of jet fuel supply
and use could insulate SAF somewhat from regional governmental variations in regulations and incentives.
Considering the status of ready technologies amenable to SAF production, the hydroprocessing tool kit is mature
and flanges well with fossil fuel refining assets. Technology providers such as Honeywell UOP and Topsoe have
been licensing their respective Ecofining™ and HydroFlex™ processes for well over a decade. More recently,
Axens has commercialized their Vegan® technology, and Chevron Lummus Global (CLG) have introduced
their ISOTERRA process. All such processes incorporate catalysts that are variants of hydroprocessing catalysts,
tailored to renewable feeds and readily capitalizing on an existing global infrastructure for catalyst manufacture.
The lowest entry barrier path to some degree of SAF production is co-processing in existing refinery units with
fossil fuels. Co-processing 5% or less renewables requires mainly a change in catalyst system employed (addressing
contaminants) and either reducing throughput or cycle life compared to fossil fuel production. Higher levels of
co-processing entail make-up hydrogen and recycle gas compressor modifications and subsequent metallurgy
upgrades to accommodate the operation and thus require capital expenditures. One advantage of co-processing is
the ability to pivot back to 100% fossil fuel production if renewables economics dictate. One technology provider
maintains the most cost-effective means to produce SAF via co-processing is to utilize a kerosene hydrotreater.5
An appropriately revamped two-stage hydrocracker presents a highly flexible unit that can adjust RD and SAF
selectivity as economics dictate as well as revert to full fossil fuel production. A unit revamp to produce 100%
renewable fuels represents the highest level of capital expenditures. Nonetheless, a revamped unit can return to
full fossil fuel production if needed.
The fundamental components of common renewable feedstocks, vegetable oils, tallow, animal fats, and used
cooking oils (UCOs), are triglycerides which are hydrodeoxygenated and hydrogenated to significant amounts of
C17-C18+ paraffin products plus propane. The desired jet fuel compounds are in the C8-C16 range. The SAF yield
via subsequent distillation of higher carbon chain products is limited, so hydrocracking is desirable to improve
the SAF yield. It nonetheless results in some yield loss due to renewable naphtha and light gas by-products. In
addition, hydroisomerization (dewaxing) is required to produce SAF with required cold flow properties. In
short, the chemistry needed to produce SAF results in a higher cost of production compared to RD. This entails
higher capital return needs.
The local situation for government renewables policy can be complex. As an example, an SAF producer in
California is faced with US RIN values 6% lower than RD and California LCFS credits 10% lower with spot
prices for jet typically some 5-6% lower than diesel. While the US Inflation Reduction Act (IRA) helps even the
unbalance, its future is uncertain.6,7 The short answer to the title question remains " it depends, " with existing
refining assets and local policy being critical.
The Catalyst Review
January 2025
3

The Catalyst Review January 2025

Table of Contents for the Digital Edition of The Catalyst Review January 2025