Workshop on Biofuel Greenhouse Gas Modeling
EPA hosted a virtual public workshop on biofuel greenhouse gas (GHG) modeling February 28 - March 1, 2022. This was a virtual meeting and open to the public. The purpose of this workshop was to solicit information on the current scientific understanding of greenhouse gas modeling of land-based crop biofuels used in the transportation sector. The meeting was conducted by EPA’s Office of Transportation and Air Quality (OTAQ) in consultation with the Department of Agriculture and the Department of Energy. Thank you to everyone who attended the workshop and submitted comments to the docket.
EPA solicited comments through a docket that was open from March 1, 2022 - April 1, 2022. A copy of these comments can be found on the Federal eRulemaking Portal here. We reviewed the 29 comments that were received through the docket. After reviewing these comments we decided to conduct a model comparison exercise to advance our scientific understanding of available models.
On June 21, 2023 EPA published the results of the model comparison exercise. We conducted this exercise with the five models discussed in the workshop (ADAGE, GCAM, GLOBIOM, GREET, and GTAP). We ran common scenarios through each framework including a reference case, a corn ethanol scenario, and a soybean oil biodiesel scenario. The goals were to identify differences across the models and to understand how these differences affect biofuel GHG estimates, as well as to explore further details about these tools. The outcomes of this exercise are available in the Model Comparison Exercise Technical Document (pdf) (3.5 MB, June 2023, EPA-420-R-23-017).
Background
Biofuel greenhouse gas modeling is used by EPA and other federal agencies for research and policy decision purposes across a variety of programs. For example, EPA is required to model the lifecycle greenhouse gas emissions of biofuels under the RFS Program when determining whether an individual biofuel meets the greenhouse gas emission reduction requirement established by the Clean Air Act. In addition, EPA is required to more broadly evaluate the greenhouse gas emissions associated with the overall RFS program when setting future volume obligations. Finally, the greenhouse gas emissions of biofuels are an important consideration of emerging policies designed to meet deep decarbonization goals.
This workshop seeks to solicit information on the current scientific understanding of greenhouse gas modeling of land-based biofuels and how this information can be applied to a range of current and future actions. EPA is explicitly seeking comment on the following questions: 1) what sources of data exist and how can they be used to inform the assumptions that drive GHG estimates; 2) how best to characterize the sources of uncertainty associated with quantifying the GHG emissions associated with biofuels; and 3) what model(s) are available to evaluate the lifecycle GHG emissions of land-based biofuels, and do the model(s) meet the Clean Air Act requirements for quantifying the direct and significant indirect emissions from biofuels.
Agenda
Monday, February 28, 2022 (All times are listed in Eastern Daylight Time (EDT))
12:00-12:05 pm | Welcome and Opening Keynote
Speaker | Sarah Dunham, U.S. Environmental Protection Agency |
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12:05-12:45 pm | Session 1: Biofuel Greenhouse Gas Modeling Uses
This introductory session discusses the purpose of the workshop and the needs for biofuel greenhouse gas (GHG) modeling. This session will provide an overview of the methodology used currently in the RFS program and additional applications of biofuel modeling at the federal and state levels. Speakers will discuss the differing and common needs of biofuel modeling at these different initiatives and levels.
Moderator | Diana Galperin, U.S. Environmental Protection Agency |
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Presentations |
GHG Biofuel Modeling in the U.S.: Summary of the RFS statutory Requirements and Future Needs (pdf)
Presentation by Karl Simon, U.S. Environmental Protection Agency |
U.S. Aviation Climate Action Plan, Sustainable Aviation Fuels, and CORSIA (pdf)
Presentation by Jim Hileman, Federal Aviation Agency |
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Interagency Working Draft Biofuel Greenhouse Gas Modeling Workshop (pdf)
Presentation by Cheryl Laskowski, California Air Resources Board |
12:45-1:00 pm | Session 1: Questions & Answers
Panelists will answer audience questions.
1:00-1:30 pm | Session 2: Recent Developments in Biofuel Production and Implications for Modeling Future Biofuel Impacts
The biofuels sector has evolved since the inception of the Renewable Fuel Standard program and similar biofuel policies. This evolution has occurred alongside changes in the agricultural sector. Federal partners will highlight recent trends in biofuel and agricultural production and provide input on how this data can be incorporated into the modeling of GHG emissions.
Moderator | Aaron Sobel, U.S. Environmental Protection Agency |
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Presentations |
Factors contributing to cropland patterns and changes in the United States (pdf)
Presentation by Bill Hohenstein, U.S. Department of Agriculture |
Modeling and Analysis Needs for Biofuels (pdf)
Presentation by Zia Haq, U.S. Department of Energy |
1:30-1:45 pm | Session 2: Questions & Answers
Panelists will answer audience questions.
1:45-2:00 pm | Break
2:00-2:45 pm | Session 3: Feedstock Supply and Land Use Change
Biofuel feedstocks may be sourced in numerous ways, therefore biofuel feedstock supply has a complex relationship with land use change. While observational land cover and land use data have improved in recent years, uncertainties remain on how these data can be applied to land use change analysis. This session will discuss recent historical trends in US and global land use change and biofuel feedstock supply and what current science can tell us about the relationships between these phenomena as it applies to biofuel GHG modeling.
Moderator | Chris Ramig, U.S. Environmental Protection Agency |
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Presentations |
The National Resources Inventory 35 Years of National Resources Monitoring (pdf)
Presentation by Patrick Flanagan, U.S. Department of Agriculture |
Next frontiers in global land cover/ land use monitoring (pdf)
Presentation by Nancy Harris, World Resources Institute |
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Considerations for Land Use Change and Satellite Data (pdf)
Presentation by Dev Shrestha, University of Idaho |
2:45-3:00 pm | Session 3: Questions & Answers
Panelists will answer audience questions.
3:00-3:45 pm | Session 4: Soil Carbon, Biomass Carbon, and Climate Smart Agricultural Practices
Global modeling of emissions from land use and land use change can be challenged by the data quality of biomass and soil carbon stocks, which can vary significantly based on local conditions. In addition, agricultural management practices can impact the storage of soil carbon. There has been a lot of progress on these topics in the scientific community and this session will discuss the latest science on biomass carbon, soil organic carbon and climate smart agriculture, and how this information could be used in a modeling context.
Moderator | Lauren Rafelski, U.S. Environmental Protection Agency |
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Presentations |
Carbon: Where is it and how can we know? (pdf)
Presentation by Seth Spawn-Lee, University of Wisconsin-Madison |
Impacts of Agricultural Practices on Soil Carbon (pdf)
Presentation by Jane Johnson, U.S. Department of Agriculture |
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Soil Carbon and the DayCent Ecosystem Modeling Platform (pdf)
Presentation by Stephen Ogle, Colorado State University |
3:45-4:00 pm | Session 4: Questions & Answers
Panelists will answer audience questions.
4:00-4:05 pm | Workshop Day 1 Summary
Presentations | Sharyn Lie, U.S. Environmental Protection Agency |
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Tuesday, March 1, 2022 (All times are listed in Eastern Daylight Time (EDT))
12:00-12:05 pm | Workshop Day 2 Welcome
12:05-1:30 pm | Session 5: Overview of Modeling Frameworks of Crop-Based Biofuels
Multiple models exist which can model the GHG emissions associated with crop-based biofuels. This session provides an overview of the diverse types of models that can be used to evaluate the GHG emissions associated with biofuels.
Moderator | Michael Shell, U.S. Environmental Protection Agency |
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Presentations |
Biofuel Life-cycle Analysis with the GREET Model (pdf)
Presentation by Michael Wang, Argonne National Laboratory |
GTAP-BIO Model and Data Base: Main Components and Improvements (pdf)
Presentation by Farzad Taheripour, Purdue University |
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The Global Biosphere Management Model(GLOBIOM) (pdf)
Presentation by Stefan Frank, International Institute for Applied Systems Analysis |
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ADAGE Global CGE Model (pdf)
Presentation by Yongxia Cai, RTI International |
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Review of the Global Change Analysis Model (pdf)
Presentation by Page Kyle, Pacific Northwest National Laboratory |
1:30-1:45 pm | Session 5: Questions & Answers
Panelists will answer audience questions.
1:45-2:00 pm | Break
2:00–3:05 pm | Session 6: Sources of Uncertainty in Biofuel GHG Estimates
This session will discuss areas of scientific uncertainty in biofuel GHG modeling. The major categories include data, modeling and methodological uncertainties. The speakers will discuss ways to reduce uncertainties through the incorporation of best available data and science. Recognizing that a significant level of uncertainty is inherent to crop-based biofuel modeling, they will also discuss best modeling practices to evaluate uncertainties and communicate results.
Moderator | Aaron Levy, U.S. Environmental Protection Agency |
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Presentations |
Review of Land Use Change Emission Estimates (pdf)
Presentation by Vassilis Daioglou, Utrecht University / PBL Netherlands Environmental |
Uncertainty in estimating the climate effects of biofuels (pdf)
Presentation by Richard Plevin, Research Consultant |
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The role of land cover data in limiting biofuels’ GHG emissions (pdf)
Presentation by Jennifer Dunn, Northwestern University & Steffen Mueller, University of Illinois at Chicago |
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The Role of Modeling Given Uncertainty (pdf)
Presentation by Nikita Pavlenko, The International Council on Clean Transportation |
3:05-3:20 pm | Session 6: Questions & Answers
Panelists will answer audience questions.
3:20-3:25 pm | Break
3:25-3:55 pm | Session 7: Public Input
Participants of the workshop are welcomed to ask or comment on any topics related to the GHG analysis of land-based biofuels.
3:55-4:00 pm | Summary & Concluding Remarks
Speaker | Sharyn Lie, U.S. Environmental Protection Agency |
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Federal Register Notice: Announcing Upcoming Virtual Meeting on Biofuel Greenhouse Gas Modeling (pdf) (published December 28, 2021)