Abstract
Research on corn ethanol is overly focused on whether corn ethanol is a net energy yielder and, consequently, has missed some other fundamental issues, including (1) whether there is significant error associated with current estimates of the EROI of corn ethanol, (2) whether there is significant spatial variability in the EROI of corn ethanol production, (3) whether yield increases will translate linearly to increases in EROI, (4) the extent to which assumptions about co-product credits impact the EROI of corn ethanol, and (5) how much of the ethanol production from biorefineries is net energy. We address all of these concerns in this research by: (1) performing a meta-error analysis of the calculation of EROI, (2) calculating the EROI for 1,287 counties across the United States, and (3) performing a sensitivity analysis for the values of both yield and co-products within the calculation of EROI. Our results show that the average EROI calculated from the meta-error analysis was 1.07 ± 0.2, meaning that we are unable to assert whether the EROI of corn ethanol is greater than one. The average EROI calculated across 1,287 counties in our spatial analysis was 1.01, indicating that the literature tended to use optimal values for energy inputs and outputs compared to the average conditions across the Unites States. Increases in yield had a trivial impact on EROI, while co-product credits had a large impact on EROI. Based on our results from the spatial analysis and the location of biorefineries across the United States, we conclude that the net energy supplied to society by ethanol is only 0.8% of that supplied from gasoline. Recent work indicates that only energy sources extracted at EROIs of 3:1 or greater have the requisite net energy to sustain the infrastructure of the transportation system of the United States. In light of this work, we conclude that production of corn ethanol within the United States is unsustainable and requires energy subsidies from the larger oil economy.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Cleveland, C. (2005). Net energy from the extraction of oil and gas in the United States. Energy, 30(5), 769.
Cleveland, C. J., Costanza, R., Hall, C. A. S., & Kauffmann, R. (1984). Energy and the US economy: A biophysical perspective. Science, 225(4665), 890–897.
ESRI. (2007). ESRI geographic software. http://www.esri.com/. Accessed 12 Oct 2007.
Farrell, A. E., Plevin, R. J., Turner, B. T., Jones, A. D., O’Hare, M., & Kammen, D. M. (2006). Ethanol can contribute to energy and environmental goals. Science, 311, 506–508.
Gagnon, N., Hall, C. A. S., & Brinker, L. (2009). A preliminary investigation of the energy return on energy invested for global oil and gas extraction. Energies, 2, 490–503.
Graboski, M. S. (2004). A rebuttal to “Ethanol Fuels: Energy, economics and environmental impacts” by D. Pimentel.
Hall, C. A. S., Cleveland, C. J., & Berger, M. (1981). Energy return on investment for United States petroleum, coal, and uranium. In W. Mitsch (Ed.), Energy and Ecological Modeling (pp. 715–724). Elsevier Publishing Co.
Hall, C. A. S., Kaufmann, R., & Cleveland, C. J. (1986). Energy and resource quality: The ecology of the economic process. New York: Wiley.
Hall, C. A. S., Stanford, J. A., & Hauer, F. R. (1992). The distribution and abundance of organisms as a consequence of energy balances along multiple environmental gradients. OIKOS, 65, 377–390.
Hall, C. A., Balogh, S., & Murphy, D. J. (2009). What is the minimum EROI that a sustainable society must have? Energies, 2(1), 25.
Kaufmann, R., & Cleveland, C. J. (2007). Environmental science. Boston: McGraw Hill.
Liska, A. J., Yang, H. S., Bremer, V. R., Klopfenstein, T. J., Walters, D. T., Erickson, G. E., et al. (2008). Improvements in life cycle energy efficiency and greenhouse gas emissions of corn-ethanol. Journal of Industrial Ecology, 00, 1–17.
Lovering, T. S. (1969). Mineral resources from the land. In P. Cloud (Ed Resources and Man) (pp. 109–134). San Fransisco: Freeman.
Mulder, K., & Hagens, N. J. (2008). Energy return on investment: Towards a consistent framework. Ambio, 37(2), 74.
Mulder, K., Hagens, N., & Fisher, B. (2010). Burning water: A comparative analysis of the energy return on water invested. Ambio, 39, 30–39.
Murphy, D. J., & Hall, C. A. S. (2010). Year in review—EROI or Energy return on (energy) invested. New York Annals of Science, 1185(Ecological Economics Reviews), 102–118.
Odum, H. T. (1973). Energy, ecology, and economics. Ambio, 2(6), 220–227.
Oliveira, M. E. D. D., Vaughan, B. E., & Rykiel, E. J. J. (2005). Ethanol as fuel: Energy, carbon dioxide balances, and ecological footprint. BioScience, 55, 593–602.
Patzek, T. (2004). Thermodynamics of the corn-ethanol biofuel cycle. Critical Review in Plant Sciences, 23(6), 519–567.
Patzek, T. W. (2007). A first-law thermodynamic analysis of the corn-ethanol cycle. Natural Resources Research, 15(4), 255–270.
Persson, T., Garcia y Garcia, A., Paz, J. O., Jones, J. W., & Hoogenboom, G. (2009). Net energy value of maize ethanol as a response to different climate and soil conditions in the southeastern USA. Biomass and Bioenergy, 33(8), 1055–1064.
Pimentel, D. (2003). Ethanol fuels: Energy balance, economics, and environmental impacts are negative. Natural Resources Research, 12(2), 127–134.
RFA. (2009). Renewable fuels association. www.ethanolrfa.org. Accessed 15 Sept 2009.
Ricardo, D. (1821). On the principles of the political economy and taxation. London, England: J.M. Dent and Sons, Ltd.
Shapouri, H., Duffield, J. A., McAloon, A., & Wang, M. (2004). The 2001 net energy balance of corn-ethanol. Corn Utilization and Technology Conference. Indianapolis, Indiana.
Shapouri, H., Duffield, J. A., & Wang, M. (2002). The energy balance of corn ethanol: An update. US Department of Agriculture, Office of the Chief Economist. Report No. 814.
USCB. (2007). United States census bureau: Census bureau geography. http://www.census.gov/geo/www/. Accessed 20 Oct 2007.
USDA. (2009). United States department of agriculture, Economic Research Service. www.ers.usda.gov/data/fertilizeruse/. Accessed 16 Sept 2009.
Wang, M. (2001). Development and use of GREET 1.6 Fuel-Cycle model for transportation fuels and vehicle technologies. Argonne National Laboratory. Report No. ANL/ESD/TM-163.
Wang, M., Saricks, C., & Wu, M. (1997). Fuel-cycle fossil energy use and greenhouse gas emissions of fuel ethanol produced from U.S. Midwest corn. Center for transportation research, Argonne National Laboratory.
Wang, M., Wu, M., & Huo, H. (2007). Life-cycle energy and greenhouse gas emission impacts of different corn ethanol plant types. Environmental Research Letters, 1–13.
Whittaker, R. H. (1956). Vegetation of the great smoky mountains. Ecological Monographs, 26, 1–80.
Acknowledgments
The authors would like to thank the Santa Barbara foundation for financial support. We would also like to thank 3 anonymous reviewers for many helpful comments.
Author information
Authors and Affiliations
Corresponding author
Additional information
Readers should send their comments on this paper to BhaskarNath@aol.com within 3 months of publication of this issue.
Appendix 1
Appendix 1
See Table 5.
Rights and permissions
About this article
Cite this article
Murphy, D.J., Hall, C.A.S. & Powers, B. New perspectives on the energy return on (energy) investment (EROI) of corn ethanol. Environ Dev Sustain 13, 179–202 (2011). https://doi.org/10.1007/s10668-010-9255-7
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10668-010-9255-7