Submitted to: Eastern Native Grass Symposium
Publication Type: Proceedings
Publication Acceptance Date: September 27, 2006
Publication Date: October 13, 2006
Citation: Adler, P.R., Del Grosso, S.J., Parton, W.J., Easterling, W.E. 2006. Land Use Change Effects from Cellulosic and Grain Ethanol Production under Climate Change. In: Sanderson, M.A, Adler, P., Goslee, S., Ritchie, J., Skinner, H., Soder, K., editors. Proceedings of the Fifth Eastern Native Grass Symposium, October 10-13, 2006, Harrisburg, Pennsylvania. p. 1. Interpretive Summary: An interpretive summary is not required.
Technical Abstract: Bioenergy cropping systems could help offset greenhouse gas emissions, but quantifying that offset is complex. Bioenergy crops offset carbon dioxide emissions by converting atmospheric carbon dioxide to organic carbon in crop biomass and soil, but they also emit nitrous oxide and vary in their effects on soil oxidation of methane. Growing the crops requires energy (e.g., to operate farm machinery, produce inputs such as fertilizer), and so does converting the harvested product to usable fuels. The objective of this study was to quantify all these factors and model the impact of climate change on the net effect of switchgrass (Panicum virgatum L.) and a corn (Zea mays L.) rotation on greenhouse gas emissions. We used the DAYCENT biogeochemistry model to assess soil greenhouse gas fluxes and biomass yields in Pennsylvania. DAYCENT results were combined with estimates of fossil fuels used to provide farm inputs and operate agricultural machinery and fossil fuel offsets from biomass yields to calculate net greenhouse gas fluxes for each cropping system considered. Displaced fossil fuel was the largest greenhouse gas sink followed by soil carbon sequestration. N2O emissions were the largest greenhouse gas source. All cropping systems simulated provided net greenhouse gas sinks compared with the fossil fuel life cycle, even in the long term when there were no further increases in soil carbon sequestration. Compared with the life cycle of gasoline and diesel, ethanol and biodiesel from corn rotations reduced greenhouse gas emissions by 30-35% and over 110-120% for switchgrass.