Drought effects on composition and yield for corn stover, mixed grasses, and Miscanthus as bioenergy feedstocks

Abstract

Drought conditions in 2012 were some of the most severe in recent history. The purpose of this study is to examine the impact of drought on quality, quantity, and theoretical ethanol yield (TEY) of three bioenergy feedstocks, corn stover, mixed grasses from Conservation Reserve Program lands, and Miscanthus × giganteus. To assess drought effects on these feedstocks, samples from 2010 (minimal to no drought) and 2012 (severe drought) were compared from multiple locations in the US. In all feedstocks, drought significantly increased extractives and reduced structural sugars and lignin; subsequently, TEYs were reduced 10–15%. Biomass yields were significantly reduced for M. × giganteus and mixed grasses. When reduction in quality and quantity were combined, TEYs decreased 26–59%. Drought negatively affected biomass quality and quantity that resulted in significant TEY reductions. Such fluctuations in biomass quality and yield may have significant consequences for developing lignocellulosic biorefineries.

Acknowledgements

The authors would like to acknowledge the support from numerous colleagues at the Idaho National Laboratory: Garold Gresham, David Muth Jr., Nathanael Kilburg, James Mahoney, Cole Glass, Sabrina Morgan, Matthew Bryant and Karen Delezene-Briggs; National Renewable Energy Laboratory: Amie Sluiter and Stefanie Maletich; ARS-USDA: Larry Pellack and Gary Radke; University of Illinois: Emily Thomas, Andy Wycislo, and DoKyoung Lee; and University of Nebraska: Roch Gaussoin; University of Georgia: Carl Jordan; and the University of Missouri.

The maps of US drought conditions were courtesy of the National Drought Mitigation Center at the University of Nebraska-Lincoln. The US Drought Monitor is jointly produced by the National Drought Mitigation Center at the University of Nebraska-Lincoln, the United States Department of Agriculture, and the National Oceanic and Atmospheric Administration.

Supplemental data

Supplemental data for this article can be accessed here.

Executive summary

Composition

• Drought significantly increased extractives and decreased structural components of the plant cell wall including cellulose (primarily glucan), hemicellulose (primarily xylan), and lignin.

• Severity of drought conditions influenced the chemical composition of biomass; mixed perennial grasses that experienced smaller differences in drought conditions had no significant change in glucan and increased xylan.

• Nitrogen fertilization did not influence chemical composition of Miscanthus × giganteus biomass significantly as compared with drought influences.

Theoretical ethanol yield/dry biomass yield

• Theoretical ethanol yield was significantly decreased by 10–15% for drought affected corn stover, mixed perennial grasses, and Miscanthus × giganteus.

• Dry biomass yields for corn stover were not affected by drought but were lowered for the mixed perennial grass and Miscanthus × giganteus.

• Theoretical ethanol yield on an area basis factoring in both loss in structural sugars and dry biomass yield decreased by 26–59% for mixed perennial grasses and M. × giganteus.

Conclusion

• Drought had significant impacts on compositional quality of all three bioenergy feedstocks.

• Corn stover dry biomass yield was not negatively affected by the drought as the other feedstocks were; however, drought-affected M. × giganteus still had overall high dry biomass yields.

• Drought appears to be a significant risk factor affecting cellulosic bioenergy feedstock supply.

Additional information

Funding

This work was supported by the US Department of Energy, Bioenergy Technologies Office, under DOE Idaho Operations Office Contract DE-AC07-05ID14517. This project was also partially supported by Agriculture and Food Research Initiative Competitive Grant No. 2011-68005-30411 from the USDA National Institute of Food and Agriculture. The authors have no other relevant affiliations or involvement with any other organization with a financial interest or conflict regarding the information presented in this manuscript.