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Carbon Intensity of Corn Starch Ethanol: State of the Science Assessment

Carbon Intensity of Corn Starch Ethanol: State of the Science Assessment

David MacIntosh, Sc.D.
Environmental Health & Engineering, Inc.

Transcript

  1. Carbon Intensity of Corn Starch Ethanol: State of the Science

    Assessment David MacIntosh, Sc.D. Chief Science Officer Environmental Health & Engineering, Inc. Newton, MA www.eheinc.com National Ethanol Conference February 16, 2021
  2. eheinc.com 2 Co-authors and Acknowledgements Greg Norris Life Cycle Analyst

    Co-Founder and CEO at NewEarth B Directs the Sustainability and Health Initiative for NetPositive Enterprise (SHINE) at MIT Melissa Scully Environmental Health Scientist Staff Scientist II in the Advanced Analytics Team, Environmental Health & Engineering Tania Alarcon Falconi Environmental Health Scientist Senior Scientist in the Advanced Analytics Team, Environmental Health & Engineering Adjunct Assistant Professor, The Gerald J. and Dorothy R. Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA Financial Support for the Research POET LLC, Sioux Falls, South Dakota Peer Network We are grateful for the assistance and contributions from members of the expert network, all of whom graciously and generously made themselves available to support our team throughout this project.
  3. eheinc.com 3 Approach Interview leading LCA researchers Critically evaluate literature

    Identify most credible carbon intensity values
  4. eheinc.com 4 Fuel Production 29.6 gCO 2 e/MJ (26.5 –

    32.7) Agriculture 26.0 gCO 2 e/MJ (22.8 – 29.2) Land Use Change 3.9 gCO 2 e/MJ (-1.0 – 8.7) Co-product Credit -12.8 gCO 2 e/MJ (-13.5 – -12.1) Denaturant 1.3 gCO 2 e/MJ (0.6 – 2.0) Fuel & Feedstock Transport 3.1 gCO 2 e/MJ (2.2 – 4.1) Tailpipe 0.3 gCO 2 e/MJ (0.1 – 0.6) Total Carbon Intensity 51.4 gCO 2 e/MJ (37.6 – 65.1) Current Central Best Estimate for Carbon Intensity of Corn Ethanol
  5. eheinc.com 5 Corn Ethanol Versus Neat Gasoline Latest scientific evidence

    indicates the current CI of corn ethanol is 46% lower than neat gasoline Ethanol 51 gCO 2 e/MJ Average Gasoline 96 gCO 2 e/MJ (32-61%)
  6. eheinc.com 6

  7. eheinc.com 7 Corn Production: Trends in Carbon Intensity Since 1990

    … Yield Increased ~50% More bushels of corn per acre of land Source Data U.S. Department of Agriculture National Agricultural Statistical Survey Chart R.L. Nielsen Department of Agronomy Purdue University
  8. eheinc.com 8 Corn Production: Trends in Carbon Intensity Since 1990

    … Yield Increased ~50% More bushels of corn per acre of land Fertilizer Intensity Down ~40% Less fertilizer per bushel of corn Translates to lower emissions of nitrous oxide, a potent greenhouse gas Source Data U.S. Department of Agriculture National Agricultural Statistical Survey Chart Wang et al. 2011 doi:10.1016/j.biombioe.2011.01.028
  9. eheinc.com 9 Corn Production: Trends in Carbon Intensity Since 1990

    … Yield Increased ~50% More bushels of corn per acre of land Fertilizer Intensity Down ~40% Less fertilizer per bushel of corn Translates to lower emissions of nitrous oxide, a potent greenhouse gas Energy Intensity Down ~50% Less liquid fuel and electricity per bushel of corn Source Data U.S. Department of Agriculture Agricultural Resource Management Study, 2015 Year Energy Use Intensity (Megajoules per bushel of corn) 1991 20.8 1996 27.3 2001 16.3 2005 12.2 2010 9.2 More recent data pending
  10. eheinc.com 10 Ethanol Refining: Trends in Carbon Intensity Since 1990

    … Energy Intensity Down ~50% Less natural gas and electricity per gallon of ethanol Also Increase in wind and solar energy contributing to the electricity grid Increase in gallons of ethanol produced per bushel of corn Source Data U.S. Department of Agriculture National Agricultural Statistical Survey Chart Wang et al. 2011 doi:10.1016/j.biombioe.2011.01.028
  11. eheinc.com 11 Land-use Change Model Estimates Over Time

  12. eheinc.com 12 What Makes a Good Land Use Change Model?

    Accounts for … • Land intensification • Increases in yield • Increases in fraction of planted crop that is harvested • Prior use of land • Region-specific land productivity and prices Calibrated to empirical data Publicly available Convergence in the United States on GTAP-BIO
  13. eheinc.com 13 Comparison of Land-use Change Emissions Associated with Corn

    Ethanol
  14. eheinc.com 14 Key Take-Aways The latest and most credible science

    has converged over time and shows that … • Carbon intensity ~ 51 gCO2 e/MJ … 46% lower than gasoline • LUC ~ 4 gCO2 e/MJ is a small component of the total Current estimates are a snapshot in time, whereas practices are evolving …
  15. eheinc.com 15 Potential for Further Reductions in Carbon Intensity Recommended

    reading Liu et al. 2020 Shifting agricultural practices to produce sustainable, low carbon intensity feedstocks for biofuel production. Environmental Research Letters 14 (2020) 084014, https://doi.org/10.1088/1748-9326/ab794e
  16. eheinc.com 16 Key Take-Aways The latest and most credible science

    has converged over time and shows that … • Carbon intensity ~ 51 gCO2 e/MJ … 46% lower than gasoline • LUC ~ 4 gCO2 e/MJ is a small component of the total Current estimates are a snapshot in time, whereas practices are evolving … • Technological innovation on farms and biorefineries in conjunction with emerging policy and markets • Opportunities to decrease greenhouse gas impacts of corn starch ethanol further
  17. Carbon Intensity of Corn Starch Ethanol: State of the Science

    Assessment David MacIntosh, Sc.D. Chief Science Officer Environmental Health & Engineering, Inc. Newton, MA www.eheinc.com National Ethanol Conference February 16, 2021