Environmental Impact of Corn Grain Ethanol Production focussed on Energy Intensity and Global Warming Potential
Leibniz-Institute for Agricultural Engineering Potsdam-Bornim, Department Technology-Assessment and Substance Cycles, Max-Eyth-Allee 100, 14469 Potsdam, Germany; e-mail: sikraatz@atb-potsdam.de Abstract. The need of fossil fuels and renewable energy is steadily increasing. The evaluation of the sustainability of the bio-fuel production needs to be considered in detail and under a holitistic point of view. The goals of this study are to enumerate the life cycle Energy Intensity (EI) and Global Warming Potential (GWP) of corn grain ethanol production, and to explore ethanol production scenarios which differ at the treatment of the Whole Stillage (WS) co-product, the starch content of the corn kernels and the corn production process at farm scale. A case study of ethanol production in Wisconsin, United States is done. The system boundaries of the investigation are from ‘cradle to plant gate’. In this study statistic data are used for real conditions of corn grain production in Wisconsin. The data for energy use at the biorefinery industrial processes are sourced from an ethanol plant survey. From the comparison of co-product use scenarios, we find that recycling the WS into electricity, heat and fertilizer is the most environmentally beneficial co-product use because it results in a 54% lower EI and a 49% lower GWP than the processing of WS into Distillers Dried Grains with Soluables (DDGS). An increasing starch content of the corn kernels shows a strong decrease of the EI and GWP of the ethanol production up to 20%. Key words ethanol, Life Cycle Assessment, corn, biofuel.
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The U.S. Renewable Fuels Standard enacted in The Energy Independence and