Renewable Diesel vs Sustainable Aviation Fuel: Why Such a Difference in Adoption Rates?

April 18, 2025

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by Jim Lane (Biofuels Digest) At first glance, RD and SAF appear nearly inseparable—often co-produced in HEFA systems, governed by overlapping policy frameworks, and sharing many investors, incentives, and technologies. Traditional analysis sees them as market twins. Yet, in this analysis out from SAF adoption leader and hard-working champion IAG, the numbers for SAF lag far behind renewable diesel.

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Converting this chart to gallons, think around 130 million gallons or so for these players, total — taking in to account there are more players than these top 10 and American and United hadn’t yet reported. Any way you look at it, renewable diesel is in the billions, SAF in the millions.

In the third quarter of last year, renewable diesel accounted for nearly 65 percent of distillate fuel consumed in California, the US’s largest market, according to EIA. Market shares for RD in the west coast states are expressed in the 20-70% market share range. SAF is in the sub-2% range. Here’s a chart for that.

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The challenge with techno-economic analysis and traditional technology adoption models

Traditional techno-economic analysis views renewable diesel and SAF as scalable, lower-carbon fuel option that benefit from infrastructure compatibility and regulatory support. HEFA (Hydrotreated Esters and Fatty Acids) technology, in particular, is celebrated for its streamlined process—feedstock goes in, drop-in diesel comes out. TEA emphasizes ROI, capital intensity, carbon intensity, and policy stacking.

GTESI analysis, based on the Genral Theory of Evolutionary Systems and Information, widens the lens. GTESI reveals a critical divergence in persistence dynamics.

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Renewable Diesel benefits from alignment across all four GTESI vectors. It’s easy to explain (“used oil becomes fuel”), integrates smoothly into existing infrastructure, and supports high-frequency trust rituals—from earnings calls to truck-stop pump expansion. Thermodynamically, it’s a relatively low-complexity, entropy-manageable system.

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In GTESI terms, renewable diesel currently thrives not because of a singular breakthrough, but because of its high alignment across multiple dimensions. Narrative simplicity (“used cooking oil becomes jet fuel”), ritual stability (from earnings calls to plant openings), and infrastructure integration (brownfield refinery conversions) create a resilient ecosystem. This coherence enhances persistence.

But GTESI also sees stress ahead: feedstock scarcity could strain symbolic cohesion and raise entropy burdens. If producers must work harder to explain the system—or defend cost premiums—the balance between symbolic trust and operational reality may fracture.

Turning to SAF

SAF, by contrast—especially non-HEFA pathways like ethanol-to-jet—suffers from narrative strain (high SCD), operational friction (high EED), and rituals that remain speculative rather than confirmatory (moderate TRFI). Even HEFA-SAF, while technically feasible, runs into symbolic mismatch: the aviation sector demands ultra-purity, rigorous carbon accounting, and future-proof scaling—conditions that exaggerate minor process inefficiencies into major trust gaps.

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• Marathon’s Infrastructure Fit: Co-processing and brownfield conversion reduce symbolic and physical friction. High ritual coherence with traditional refining.

• Lifecycle Performance: Shows alignment between feedstock emissions and carbon credit performance—a strong thermodynamic-symbolic linkage.

• Capital Formation: Unlike speculative DAC or ATJ, HEFA capital investment maps well to thermodynamic reality, with multiple FID-stage or operating plants.

IV. GTESI Sector Forecast

• Short-Term (1–3 years): Continued growth driven by policy, energy security narrative, and path dependence.

• Mid-Term (4–7 years): Strain likely due to feedstock competition and policy rebalancing—potential SCD inflection point.

• Watch for: Signs of EED strain—i.e., increasing efforts to justify expansion despite input scarcity and rising LCFS friction.

V. Takeaways

• Renewable Diesel succeeds not because it is perfect, but because it exhibits high coherence across GTESI dimensions.

• It is symbolically credible, thermodynamically tolerable, and ritually reinforced.

• The model flags future fragility, not current collapse. But watch for IPR-SCD decoupling if feedstock cost exceeds symbolic justification.

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Gevo LCA Report (CRA): Despite a well-argued emissions case, the loss of volume and carbon credits in the ETJ pathway undermines the narrative payoff.
Saddler & Comer: Complexity of scaling ethanol-based SAF and low carbon intensity loss confirm high SCD and entropy reinjection.
ATJ Tech Papers: Frequent reliance on “future scale” and “policy bridge” arguments reveals symbolic gaps in present trust structures.

IV. GTESI Sector Forecast

Short-Term (1–3 years): Modest gains via policy support, demonstration plants. TRFI will rise or collapse based on real project delivery.
Mid-Term (4–7 years): Without large-scale operation and favorable LCA crediting, GTESI predicts narrative exhaustion and funder fatigue.
Watch for: Projects slipping from FID to indefinite delay; loss of trust rituals (e.g., silent partners, vanished policy enthusiasm).

V. Takeaways

ATJ is not a failure, but its symbolic momentum exceeds its thermodynamic coherence.
It has potential, but must rapidly close the gap between narrative and entropy export reality.
GTESI sees an IPR trap ahead: persistence is only likely with extraordinary trust rituals, breakthrough tech compression, or unusual policy fortification. READ MORE

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The Outlook for the Renewable Diesel Market (CropLife)
Sustainable Aviation Fuel: Another Driver for Future Crop Use (CropLife)

Excerpt from CropLife: At the 2025 Ohio Agribusiness Association annual meeting, Michael Reginelli, Risk Management Consultant at Advance Trading, Inc., gave a speech on the U.S. energy sector. In this, Reginelli specifically mentioned soybean oil-driven renewable diesel as one of the key market drivers going forward.

“In 2024, renewables made up about 9% of U.S. energy consumption,” he said. “Renewable diesel is driving the growth in the soybean processing industry. And it’s staggering how quickly that industry is growing. Overall, it’s up 16 times between 2010 and 2025. And it’s expected to have the same rate of growth over the next few years as well.”

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In part because of this growth for renewable diesel, Reginelli predicted the U.S. would see more soybean crushing plants coming online over the next few years. However, politics could get in the way of this expansion.

“Policy is probably one of the biggest components of this growth right now, but it’s also the one with the most uncertainty,” he said. “Any pullback on policies supporting renewables could change this equation for new crush plant investment.” READ MORE

Excerpt from CropLife: According to Michael Reginelli, Risk Management Consultant at Advance Trading, Inc., SAF could be “a very big deal” when it comes to ethanol demand.

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According to the data, SAF can reduce greenhouse gas emissions by up to 80% compared to fossil-based jet fuel. As Reginelli summed up: “The carbon reduction with SAF is massive.”

Right now, reported Reginelli, the U.S. has a mandate in place to have the country’s aviation industry reduce its carbon emissions by 20% by the end of this decade. Some individual airline companies have set their own emission reduction numbers as well.

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According to Reginelli, SAF production is projected to begin in earnest by 2027, with more investment being made in bringing new production capacity online. “And things for this market should really take off by 2030,” he concluded. READ MORE