New Study Finds California’s Soybean ILUC Values Are Outdated

December 05, 2025

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(Clean Fuels Alliance America) The analysis reveals CARB’s ILUC values for US soy-based biodiesel and renewable diesel lack current data overstate emissions -- A recent study commissioned by Clean Fuels Alliance America and Farmers Fueling the Future finds that California’s indirect land use change (ILUC) assumptions for U.S. soy-based biodiesel and renewable diesel are outdated lacking modern agricultural practices and current science.

The analysis, Land Use Change Emissions Associated with Soybeans: Considerations for California’s LCFS, conducted by Life Cycle Associates (LCA), highlights substantially lower ILUC emissions for soy-based fuels than those currently used by the California Air Resources Board (CARB). Considerations include advances in economic modeling, land-use data, yield responsiveness, trade patterns and carbon stock measurements.

CARB last updated its soybean ILUC value in 2018 using modeling tools and data that predate many of today’s improvements in agricultural productivity and global market dynamics. The latest research shows ILUC values well below CARB’s current assumptions calculated with more recent global data through updated GTAP modeling.

According to the report, improvements in modeling and data inputs have consistently reduced estimated ILUC emissions for soy-based biodiesel and renewable diesel, producing results that better align with observed land-use and market behavior.

“This study confirms that today’s farmers are meeting growing clean fuel demand through higher yields and responsible practices—not land expansion,” said Dave Walton, Executive Board Member for Clean Fuels and the American Soybean Association. “CARB must modernize its approach and base its values on today’s science to accurately recognize the real carbon benefits of soy-based biodiesel and renewable diesel.”

According to Clean Fuels, the findings underscore the need for California’s Low Carbon Fuel Standard to reflect current data and real-world agricultural performance as the state works to decarbonize its transportation sector.

The full study is available on cleanfuels.org.

About Farmers Fueling the Future

Farmers Fueling the Future is a biofuel research initiative between the American Soybean Association and the Iowa Soybean Association.

ABOUT CLEAN FUELS ALLIANCE AMERICA

Made from an increasingly diverse mix of resources such as recycled cooking oil, soybean oil, and animal fats, the clean fuels industry is a proven, integral part of America’s clean energy future. Clean Fuels Alliance America is the U.S. trade association representing the entire biodiesel, renewable diesel and sustainable aviation fuel supply chain, including producers, feedstock suppliers and fuel distributors. Clean Fuels receives funding from a broad mix of private companies and associations, including the United Soybean Board, Nebraska Soybean Board and other state checkoff organizations. For more information, visit cleanfuels.org. READ MORE

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Land Use Change Emissions Associated with Soybeans, Considerations for California’s LCFS (Life Cycle Associates)
Rethinking ILUC Part 1: California Falters on Clean Fuels (Clean Fuels Alliance America)
Rethinking ILUC Part 2: Lessons for California and Other Policymakers (Clean Fuels Alliance America)

Excerpt from Clean Fuels Alliance America (Part 1): On November 6, the California Air Resources Board (CARB) hosted a Public Forum on Land Use Change (LUC) and other issues central to the clean fuels industry.

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Under California’s Low Carbon Fuel Standard (LCFS), soy- and canola-based fuels are assigned carbon intensity (CI) scores that are 50% to over 100% higher than they would be otherwise. This increase comes from the so-called indirect or induced land use change (ILUC) value — a theoretical estimate of global land conversion emissions that are assumed to result from increased demand for crop-based fuels. For those unfamiliar with this debate, the narrative presented at CARB’s Forum could leave the impression that U.S. biodiesel and renewable diesel are driving global hunger and tropical deforestation. That’s simply not true — and it’s deeply problematic that the clean fuels industry wasn’t invited to share the data that tells a more complete story about the food-climate-energy nexus.

If our industry had been invited to present at the Forum, the audience would have learned what we know and hold true as we seek to accelerate the adoption of clean fuels. Namely, the audience would have learned:

Mitigating emissions now is substantially more valuable than doing so later.
Good policy is a balance of environmental, social and economic aspects, not the environment at the expense of everything else.
Crop-based fuels complement, not compete with, food production.
The problem is not farming revenue. It is, however, responsible land stewardship.
Agriculture cannot only be a part of climate solutions; it must be a part of climate solutions.

The Time Value of Carbon: Mitigation Delayed Is Mitigation Denied

Climate science is clear: mitigating emissions now is substantially more valuable than doing so later. According to the latest carbon impulse response functions:

Waiting five years to cut emissions requires over 13 times more reductions to have the same climate benefit.

In other words, early action counts – by making incremental progress now, we can buy ourselves more time and less irreversible impacts.

This is particularly important to agriculture, the myriad markets that are built on its shoulders, and the very topic CARB sought to explore: land use change. That’s because delaying the switch to bio-based alternatives away from fossil fuels could actually accelerate cropland expansion and agriculture’s greenhouse gas emissions since crop yields are highly likely to decline in a hotter world. The LCFS credit system was even designed with this in mind, rewarding early action with banked credits. Banking credits then isn’t just fiscally responsible — it’s environmentally responsible.

Real Sustainability Balances Climate, People and Prosperity

As the Brundtland Commission defined decades ago, sustainability means “meeting the needs of the present without compromising the ability of future generations to meet their own needs.” That includes the triple bottom line: environmental integrity, economic viability and social well-being. READ MORE

Excerpt from Clean Fuels Alliance America (Part 2):

ILUC is a theoretical estimate of emissions attributed to global land conversion modeled as induced by increases in crop-based fuel demand. ILUC modeling arose from reasonable concerns that large-scale displacement of fossil fuels with crop-based fuels could incentivize expansion of cropland onto natural ecosystems, thereby releasing stored carbon and threatening biodiversity. But the trajectory of modeling this risk has shown over time to be less and less of the threat originally raised.

To evaluate this risk, economic equilibrium models have paired market forecasts with global carbon stock data, constructing counterfactual scenarios of how agriculture and energy markets could theoretically evolve under heightened demand for biofuel crops. This is where those who attended CARB’s Public Forum saw debates and presentations on Purdue University’s GTAP-BIO model, International Institute for Applied Systems Analysis’ GLOBIOM model, and Pacific Northwest National Lab’s GCAM model. While a potentially useful exercise, these models are inherently uncertain. Their complexity, reliance on assumptions, and lack of real-world verification make their results best understood as scenario-based indicators of potential risk—not as direct measures of greenhouse gas emissions or environmental harm.

ILUC values from model results do not reflect actual environmental harm.

Many attributes of the modeling from their very basic structure to the parameters they rely on create the variability in their outputs. For example, GTAP-BIO, which is used in California per its regulatory text, is a computable general equilibrium (CGE) model, which means it looks at the global economy as a whole and models how all markets react to the increased demand for crop-based fuels from labor to agriculture to oil to land. GLOBIOM and GCAM, which were also highlighted at the Forum are partial equilibrium (PE) models, models that focus on certain markets, like forestry and agriculture, with greater detail than a CGE model but without the capability to model the entire global economy. What does this translate to? Higher ILUC results from PE models than CGE models based on that very fundamental structure. If you restrict the ways in which markets can adapt to a new normal there will be more impact. This does not mean the lower numbers associated with CGE models are wrong; they simply reflect a hypothetical outcome. It’s a disingenuous argument, then, to say that GTAP-BIO underestimates the risk of ILUC simply because the output is lower than other models assessed.

The agricultural community is quick to highlight that intensification (increases in yield from new technology) has generated significant increases in feedstock supply, without the need to utilize or convert new acres in other regions of the world.

A 45% jump in soybean yields since the 1990s added 15 billion lbs of soybean oil in 2025—exceeding U.S. biomass-based diesel demand in 2024—without requiring a single acre of new cropland.

EPA has nicely laid out the myriad ways in which various ILUC models differ and what may drive material differences in outcomes but not for the untrained eye. I was early in my understanding of ILUC modeling when they published their report, but as I kept asking “why,” the reasons became obvious. The different models exist because they’re asking slightly different questions. And, frankly, different experts have different opinions about how economic markets react or how best to represent changes to the various markets biodiesel and renewable diesel play in—namely, agriculture and energy.

Nevertheless, ILUC values have been incorporated into regulatory frameworks, effectively functioning as precautionary adjustments to account for potential land conversion risk. California and the other low-carbon fuel states as well as ICAO’s CORSIA take these modeled values and add them to the carbon intensity of fuel pathways based on their feedstock, and in the case of CORSIA, sometimes also based on the regional origin of that feedstock. This use underscores these models’ purpose: they are tools for risk mitigation, not definitive evidence of biofuels’ actual climate impact. As such, other less cumbersome tools may be more appropriate to incorporate into clean fuel policy. They certainly should be less controversial than the black box penalties that fuel producers must tack onto their supply chain CI scores regardless of how sustainable their feedstock’s actual supply chain is.

According to the International Energy Agency (IEA), growing the sustainable fuels industry will bring millions of jobs to the regions where these fuels are produced and, importantly, deliver “sustained emissions reductions while improving domestic energy security and creating new economic development opportunities.” IEA suggests this is all possible so long as we use transparent and robust carbon accounting methodologies that enhance comparability and interoperability. The right methodologies will enable performance-based policies and incentives that reward progress in measurable emission reductions.

I emphasize measurable here because if those who are for and against low-carbon liquid fuels can agree on nothing else, we can agree that ILUC values are not measurable. This is the root cause of the endless controversy: no single ILUC model can satisfy opposing stakeholders.

But IEA goes farther. Through their analysis of low-carbon fuel policies the world over, they have highlighted that ILUC values are the least certain (read: immeasurable) and most determinative factor in a pathway’s performance. IEA, therefore, recommends that carbon accounting methodologies separate the supply chain CI score from ILUC so that it is “managed through [a] separate polic[y] and not lumped together with [CI] considerations.”

With this in mind, Clean Fuels is taking IEA’s recommendations to heart. We are working on a framework that captures the concerns of ILUC risks while rewarding stewardship, transparency, and continuous improvement across our supply chains. We believe that this approach should reflect key principles that guard against unintended consequences while enabling continuous improvement. This framework and its implementation should therefore:

Reflect the risk tolerance of the environment in which it operates. U.S. programs in states with a heavy agriculture presence have more to gain in economic development than risk of inducing deforestation, so their policies should reflect that balance.
Mitigate the risk of converting high carbon stock and biodiverse lands. If the real concern is tropical deforestation because tropical forests are our planet’s lungs, sequester the most carbon, and hold a disproportionate number of the world’s known species, then we must focus on what is happening on the ground there.
Be technology neutral. As I previously put forth, the problem is not a soy plant, it’s anything taking up the land of previously high-carbon stock and biodiverse land.
Dynamically capture changing conditions at different geographical scales. A U.S. produced biodiesel made from oil processed in the U.S. from soybeans grown in the U.S. where the local, state, and federal governments have not only restrictive land use laws but also strict enforcement mechanisms, should have a bright green light. Conversely, a biodiesel made from soybean oil that has its roots in a region that has questionable land use laws or questionable enforcement of the laws on the books should be treated less favorably.
Reward process improvements. Effective decarbonization demands balancing social, economic, and environmental priorities while relentlessly pursuing better outcomes. This means centering our decisions on practices that improve the long-term sustainability of the land we depend on.
Consider the informal economy and fraud prevention. Even with good conservation laws in the books, governments’ ability to prevent deforestation is only as good as their enforcement mechanisms that deter bad actors.

We are actively working to flesh out how these principles can be operationalized to create a simplified and transparent system for policymakers to implement in their low-carbon fuel programs.

In the interim, we also recognize that complex regulatory processes may slow or limit the ability of agencies to act in the near term. California just finalized its 3-year rulemaking process without touching ILUC values and thereby continuing their reliance on the GTAP-BIO model. But the LCFS also states that CARB should use the best available economic and scientific information, which means that ILUC modeling, where employed, should be regularly updated. We encourage CARB to do what it can to stay true to that mission and for other jurisdictions who see modeled ILUC values as the best fit for their program to reflect the most recent understanding of:

Relationships between global agricultural and energy economies.
Global land cover and land use classifications and data trends.
Land sector carbon stocks.
Carbon cycling during land conversion.

These four aspects are all contained in the models mentioned above and are essential to ensuring the models reflect our latest and best understanding of the world we live in. While California relies on global and energy economic information from 2004 for its ILUC values, the modelers at Purdue have updated GTAP-BIO to better reflect the evolution of agriculture and energy markets since then, most recently with the global economy’s state in 2017. They have also recently updated their carbon stock and carbon cycling methodologies to reflect the latest soil carbon databases and recommendations from the Intergovernmental Panel on Climate Change.

At Clean Fuels, we fully embrace making progress each and every day to have science better inform the decisions we make to support the energy transition. We look forward to collaborating with stakeholders who share our dual focus: making near-term policy improvements while working toward larger, lasting reforms that advance economic, social, and environmental wellbeing. READ MORE