DOE’s Updated 45Z GREET Model Brings Clarity to US Biofuels Markets

The US Department of Energy’s updated 45ZCF-GREET (Greenhouse gases, Regulated Emissions, and Energy use in Technologies) model gives the renewable fuels industry something it has been waiting for: a clearer framework for calculating lifecycle emissions under the 45Z Clean Fuel Production Credit.

For US biofuels producers, this is more than a technical update. Carbon intensity scores are becoming a central driver of project economics, tax credit value, feedstock strategy, and long-term investment planning.

With the updated model now available, ethanol, biodiesel, renewable diesel, renewable natural gas, and sustainable aviation fuel producers have a more defined basis for evaluating how their fuels may qualify under 45Z.

That clarity arrives at an important moment.

Producers have been navigating a period of policy transition, shifting from earlier incentive structures toward a credit that directly rewards lower-carbon production. Under 45Z, the credit value depends on the fuel's emissions profile. As a result, even small changes in lifecycle carbon accounting can influence margins, capital allocation, and competitive positioning across the renewable fuels value chain.

Why GREET Matters for 45Z

GREET refers to the lifecycle analysis model used to estimate emissions associated with fuels, products, and energy systems across the supply chain.

For 45Z, the 45ZCF-GREET model is used to determine emissions rates for eligible clean fuels. In practical terms, that means the model helps determine how much value a producer can capture from the credit. Lower carbon intensity generally supports higher credit value, while higher carbon intensity limits the potential benefit.

This makes GREET a market-shaping tool. It does not simply measure emissions. It influences which fuels, feedstocks, technologies, and production pathways are most economically attractive under federal policy.

Read More: Feedstock Fundamentals: What Are Biofuels Made From?

A More Investable Framework for Producers

The most immediate implication of the updated model is improved planning certainty.

For much of the market, uncertainty around carbon accounting has been a constraint on investment. Producers need confidence in the credit value of their efforts on multiple fronts:

• Carbon Capture

• Renewable Power Procurement

• Energy-efficiency Upgrades

• Process Fuel Changes

• Feedstock Adjustments

The updated 45ZCF-GREET model gives producers a clearer basis for modeling expected returns. That matters for existing assets and new projects alike.

For ethanol producers, the model may help clarify the value of investments that reduce plant-level emissions, including:

• Carbon Capture and Storage

• Renewable Natural Gas

• Lower-Carbon Power

For renewable diesel and biodiesel producers, it sharpens the focus on feedstock carbon intensity, supply chain documentation, and procurement strategy. For SAF developers, it provides a stronger foundation for assessing long-term project economics in a market that remains highly dependent on policy support.

In each case, the central question becomes the same. Which operational changes deliver the greatest carbon reduction per dollar invested?

Market Outlook: Feedstocks Will Become More Strategically Important

The updated model is likely to increase competition for feedstocks that can deliver favorable carbon-intensity scores.

In renewable diesel, biodiesel, and SAF markets, feedstock selection is already one of the most important determinants of production economics. Used cooking oil, tallow, distillers corn oil, soybean oil, canola oil, and other fats, oils, and greases can produce meaningfully different emissions outcomes depending on their lifecycle assumptions and sourcing requirements.

As the 45Z credit value becomes more closely tied to carbon intensity, producers are likely to place a higher premium on feedstocks that offer both reliable availability and lower emissions profiles. This could support stronger demand for waste- and residue-based feedstocks, especially when those materials help producers improve creditworthiness or preserve margins in competitive markets.

At the same time, supply limitations remain a constraint. Low-carbon feedstocks are not unlimited. Accordingly, competition from renewable diesel, SAF, biodiesel, oleochemicals, animal feed, and export markets can quickly tighten availability. As a result, the market may see wider spreads between feedstocks based on both physical supply/demand and their carbon values.

For soybean oil and other crop-based feedstocks, the outlook is more complex. These markets benefit from scale, established logistics, and deep agricultural supply chains.

However, their competitiveness under 45Z will depend heavily on emissions scoring, regional production practices, and the ability to document lower-carbon attributes. Over time, this may create stronger incentives for improved farm-level practices and more efficient processing. Ultimately, this provides better traceability across the supply chain.

Implications for Corn Ethanol

Corn ethanol remains central to the US renewable fuels landscape, and the updated 45ZCF-GREET model could influence how producers evaluate their role in low-carbon fuel markets.

The ethanol sector has several available levers to reduce carbon intensity:

• Carbon Capture and Storage

• Renewable Power

• Biomass or Biogas Process Energy

• Improved Plant Efficiency

• Lower-Carbon Agricultural Inputs

The challenge is determining which investments generate sufficient credit value to justify the cost.

45Z may help separate producers by carbon performance. Plants that can lower emissions cost-effectively may be better positioned to preserve margins, access premium markets, and participate in future SAF supply chains. Plants with higher carbon intensity may face greater pressure to invest or risk becoming less competitive as buyers and policymakers place more weight on lifecycle emissions.

This dynamic could accelerate a shift already underway in ethanol markets. Carbon intensity is becoming a commercial differentiator rather than just a compliance metric.

Margin Structures Could Shift Across Renewable Fuels

The updated model may also change how producers think about margins.

Historically, renewable fuel margins have been driven by multiple factors:

• Feedstock Costs

• Fuel Prices

• RIN Values

• LCFS credits

• Tax Incentives

• Logistics and Operating Efficiency

45Z adds another layer: the monetizable value of carbon reduction. That could make carbon intensity a more direct component of margin strategy.

Producers with lower-carbon pathways may be able to capture higher credit value, offset higher feedstock costs, or justify additional investment in emissions-reducing technology. Producers with less favorable carbon profiles may need stronger fuel prices or lower input costs to remain competitive.

This creates a more differentiated market. Two producers making the same fuel may have very different economics depending on feedstock sourcing, process energy, facility efficiency, and emissions documentation.

For investors, lenders, and project developers, this makes carbon modeling increasingly important during due diligence. It is no longer enough to ask whether a project can produce renewable fuel at scale. The more important concern is whether it can produce renewable fuel with a low enough carbon intensity to support durable economics.

SAF Development Gets a Clearer Signal

Sustainable aviation fuel remains one of the most closely watched growth areas for US renewable fuels. Demand from airlines, corporate decarbonization programs, and policy mandates continues to support long-term interest in SAF production.

However, SAF projects are capital-intensive and often depend on policy incentives to reach commercial viability. Greater clarity around 45Z emissions scoring helps developers evaluate which pathways are most likely to generate attractive returns.

That clarity is especially important for alcohol-to-jet, hydroprocessed esters and fatty acids, and other emerging SAF pathways. Producers need to understand how feedstock choices, process energy, hydrogen inputs, and facility design will affect lifecycle emissions and credit value.

The updated model does not eliminate market risk, however. SAF still faces challenges around production costs, feedstock availability, offtake structures, and infrastructure. But it does give developers and investors a more reliable framework for comparing pathways and making capital decisions.

A Stronger Signal for Carbon-Smart Supply Chains

One of the broader implications of 45Z is that carbon intensity will increasingly affect decisions upstream of the fuel plant.

Feedstock producers, aggregators, logistics providers, processors, and fuel marketers all play a role in reducing lifecycle emissions. As credit value becomes more dependent on verified carbon performance, documentation and traceability will become even more important.

This could create opportunities for agricultural producers that adopt lower-emission practices, waste-feedstock suppliers that can verify origin and handling, and fuel producers that can build transparent supply chains.

It may also create new challenges as well. Producers will need reliable data, credible verification, and clear internal systems for tracking emissions-related attributes. In markets where documentation is weak or inconsistent, capturing carbon value may be more difficult.

What to Watch Next

The updated 45ZCF-GREET model is a major step, but it is not the end of the policy and market adjustment process.

Market participants will still need to evaluate how the model affects specific pathways, facilities, and feedstock combinations. Additional federal guidance, tax interpretation, and implementation details may also shape how producers claim and monetize the credit.

In the near term, producers are likely to focus on three questions:

1. How does the updated model affect expected credit value by fuel pathway?

2. Which operational or feedstock changes provide the strongest return on investment?

3. How can producers document emissions performance in a way that supports credit claims and customer confidence?

The answers will influence not only project economics, but also competitive positioning across the US renewable fuels market.

The Bottom Line

The updated 45ZCF-GREET model gives US renewable fuel producers a clearer framework for evaluating carbon intensity and credit value under 45Z.

That clarity should support stronger investment planning, a more disciplined feedstock strategy, and sharper competition around low-carbon production pathways.

Ethanol, biodiesel, renewable diesel, RNG, and SAF markets all stand to be affected. However, the impact will vary by feedstock, facility configuration, and emissions profile.

For the US biofuels industry, the message is clear: carbon intensity is no longer just a policy calculation. It is becoming a core market signal.

Don't miss out on what's important across the biofuels market. Subscribe to our weekly blog and monthly newsletter for convenient updates, direct to your inbox.