Assessing the Additional Carbon Savings with Biofuel


A recent study by DeCicco et al. (Climatic Change 138:667–680, 2016) claims that corn used for ethanol should not be considered to be inherently biogenically carbon-neutral because not all that corn was grown additional to the level otherwise. By assessing the extent of carbon neutrality of corn for ethanol using the reference point baseline approach and historical data that study concluded that the carbon intensity of US corn ethanol is 27% higher than that of gasoline. We develop a framework to determine the carbon neutrality of corn for ethanol by assessing the additional carbon uptake by crops using an anticipated baseline approach. We also apply this framework to determine the additional corn produced for ethanol and include the direct life cycle carbon emissions of only that portion of corn in the direct life cycle carbon intensity of corn ethanol. We implement this framework by integrating an economic model of the agricultural sector in the USA with a biogenic carbon model and life cycle analysis to quantify biogenic carbon uptake and direct life cycle emissions with and without corn ethanol expansion over the 2007–2027 period. We find that the combined biogenic carbon emissions and direct life cycle carbon emission intensity of corn ethanol (not including indirect land use related emissions) is 21% lower than gasoline. The lower value of this carbon intensity of corn ethanol compared with gasoline is robust to a wide range of parametric assumptions.

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    The estimate of DDGS co-product credit is obtained from Wang et al. [26]. Although the BEPAM does calculate the amount of DDGS used as a replacement for corn and soybean in livestock feed, it does not include other factors that determine the magnitude of the co-product carbon credit, such as impact on methane emissions due to enteric fermentation in animals and the impact on cattle lifetimes and feeding days and on animal performance. Since our focus here is primarily on isolating the effects of additional corn production on feedstock emissions to be included on the carbon intensity of corn ethanol and comparing our estimates with those in the literature, we rely on estimates of carbon emissions at other stages of ethanol production and the co-product credit on the existing literature.


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The authors thank Cristina Canter and Zhangcai Qin from the Argonne National Laboratory for data and helpful suggestions for this research. This work was funded by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research under Award Number DE-SC0018420..

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Correspondence to Madhu Khanna.

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Khanna, M., Wang, W. & Wang, M. Assessing the Additional Carbon Savings with Biofuel. Bioenerg. Res. 13, 1082–1094 (2020).

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  • Biogenic carbon intensity
  • Corn ethanol
  • Economic model
  • Dynamic optimization
  • Anticipated baseline approach
  • Life cycle carbon intensity