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Title: Nitrogen rate and landscape impacts on life cycle energy use and emissions from switchgrass-derived ethanol

Switchgrass-derived ethanol has been proposed as an alternative to fossil fuels to improve sustainability of the US energy sector. In this study, life cycle analysis (LCA) was used to estimate the environmental benefits of this fuel. To better define the LCA environmental impacts associated with fertilization rates and farm-landscape topography, results from a controlled experiment were analyzed. Data from switchgrass plots planted in 2008, consistently managed with three nitrogen rates (0, 56, and 112 kg N ha –1), two landscape positions (shoulder and footslope), and harvested annually (starting in 2009, the year after planting) through 2014 were used as input into the Greenhouse gases, Regulated Emissions and Energy use in transportation (GREET) model. Simulations determined nitrogen (N) rate and landscape impacts on the life cycle energy and emissions from switchgrass ethanol used in a passenger car as ethanol–gasoline blends (10% ethanol:E10, 85% ethanol:E85s). Results indicated that E85s may lead to lower fossil fuels use (58 to 77%), greenhouse gas (GHG) emissions (33 to 82%), and particulate matter (PM2.5) emissions (15 to 54%) in comparison with gasoline. However, volatile organic compounds (VOCs) and other criteria pollutants such as nitrogen oxides (NOx), particulate matter (PM10), and sulfur dioxides (SO x) were highermore » for E85s than those from gasoline. Nitrogen rate above 56 kg N ha –1 yielded no increased biomass production benefits; but did increase (up to twofold) GHG, VOCs, and criteria pollutants. Lower blend (E10) results were closely similar to those from gasoline. The landscape topography also influenced life cycle impacts. Biomass grown at the footslope of fertilized plots led to higher switchgrass biomass yield, lower GHG, VOCs, and criteria pollutants in comparison with those at the shoulder position. Lastly, results also showed that replacing switchgrass before maximum stand life (10–20 years.) can further reduce the energy and emissions reduction benefits.« less
 [1] ;  [2] ;  [3] ;  [2] ;  [4] ;  [4]
  1. Air Force Institute of Technology, WPAFB, OH (United States). Dept. of Systems Engineering and Management
  2. South Dakota State Univ., Brookings, SD (United States). Plant Science Dept.
  3. South Dakota State Univ., Brookings, SD (United States). North Central Regional Sun Grant Center
  4. South Dakota School of Mines and Technology, Rapid City, SD (United States). Dept. of Civil and Environmental Engineering
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Global Change Biology. Bioenergy
Additional Journal Information:
Journal Volume: 8; Journal Issue: 4; Journal ID: ISSN 1757-1693
Research Org:
South Dakota State Univ., Brookings, SD (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Bioenergy Technologies Office (EE-3B)
Country of Publication:
United States
09 BIOMASS FUELS; bioethanol; emissions; energy use; greenhouse gases regulated emissions and energy use in transportation; life cycle analysis; switchgrass
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1438469