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Global warming intensity of biofuel derived from switchgrass grown on marginal land in Michigan |
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| Authors: | Seungdo Kim Bruce E Dale Rafael Martinez-Feria Bruno Basso Kurt Thelen Christos T Maravelias Douglas Landis Tyler J Lark G Philip Robertson |
| Institution: | 1. DOE Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, Michigan, USA;2. DOE Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, Michigan, USA
Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan, USA;3. DOE Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, Michigan, USA Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, Michigan, USA;4. Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey, USA Andlinger Center for Energy and Environment, Princeton University, Princeton, New Jersey, USA DOE Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, USA;5. DOE Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, Michigan, USA Department of Entomology, Michigan State University, East Lansing, Michigan, USA;6. DOE Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, USA Nelson Institute Center for Sustainability and the Global Environment (SAGE), University of Wisconsin-Madison, Madison, Wisconsin, USA |
| Abstract: | Energy crops for biofuel production, especially switchgrass (Panicum virgatum), are of interest from a climate change perspective. Here, we use outputs from a crop growth model and life cycle assessment (LCA) to examine the global warming intensity (GWI; g CO2 MJ?1) and greenhouse gas (GHG) mitigation potential (Mg CO2 year?1) of biofuel systems based on a spatially explicit analysis of switchgrass grown on marginal land (abandoned former cropland) in Michigan, USA. We find that marginal lands in Michigan can annually produce over 0.57 hm3 of liquid biofuel derived from nitrogen-fertilized switchgrass, mitigating 1.2–1.5 Tg of CO2 year?1. About 96% of these biofuels can meet the Renewable Fuel Standard (60% reduction in lifecycle GHG emissions compared with conventional gasoline; GWI ≤37.2 g CO2 MJ?1). Furthermore, 73%–75% of these biofuels are carbon-negative (GWI less than zero) due to enhanced soil organic carbon (SOC) sequestration. However, simulations indicate that SOC levels would fail to increase and even decrease on the 11% of lands where SOC stocks >>200 Mg C ha?1, leading to carbon intensities greater than gasoline. Results highlight the strong climate mitigation potential of switchgrass grown on marginal lands as well as the needs to avoid carbon rich soils such as histosols and wetlands and to ensure that productivity will be sufficient to provide net mitigation. |
| Keywords: | γ-valerolactone (GVL) cellulosic biofuel dynamic LCA global warming intensity marginal land static LCA switchgrass |