(401a) A Model-Based Life Cycle Analysis of Hydrotreated Renewable Jet Fuel (HRJ) from Oilseed Feedstocks Replacing Fallow in the U.S. Northern Great Plains
This life cycle assessment (LCA) of hydrotreated renewable jet (HRJ) fuel produced in the U.S. Northern Great Plains regions from rotation of biofuel rapeseed with grain crops uses a model-based approach. The utilized models to obtain life cycle input data include Environmental Policy Integrated Climate (EPIC), Alternative Fuel Transportation Optimization Tool (AFTOT), tier 1 models from the Intergovernmental Panel on Climate Change (IPCC), and other process models. Life cycle inputs are obtained using geospatial data on soils and weather and spatially explicit information on bioenergy rapeseed replacement of fallow in food crop-fallow rotations for different price points of rapeseed based on relative profitability of growing options. A cradle-to-grave LCA of the entire chemical conversion and utilization pathway was developed considering emissions of greenhouse gases (GHGs) and consumption of total primary, renewable, and fossil energy. Fertilizer utilization was predicted and crop management of the different production options was evaluated using EPIC. Different strategies for allocation of environmental impacts among the planned co-products was investigated. Comparisons is made relative to petroleum jet fuel products to determine savings of GHG emissions and fossil energy demand. LCA results show that introducing fuel oilseeds to existing crop rotations to replace fallow have significant advantages in terms of GHG emissions. With consideration of soil carbon sequestration from replacing fallow period, the GHG emissions can be as low as -235 g CO2 eq/MJ jet fuel to -349 g CO2 eq/MJ jet fuel using displacement allocation, and -55 g CO2eq/MJ jet fuel to -107 g CO2 eq/MJ jet fuel using energy allocation, over the price points from $400 to $800/Mg rapeseed. Soil organic carbon and N2O emissions vary along the price points, and are influenced by the fertilizer application, tillage system, crop rotations, etc. The cumulative energy demand for production of rapeseed HRJ is larger than for fossil jet fuel, however, most of the energy inputs are from renewable biomass and at all price points requires less fossil energy comparing to fossil jet, with net energy return on fossil energy invested of up to 4 to 1. Total net revenues at lower prices of $400 are $1.6 million per year, and reaches $56.2 million per year at the highest price of $800. These results provide insights on the potential impacts of expanded rapeseed biofuel production systems in regional contexts compared to the current cropping systems and answered the questions of what is the best agricultural practice to enhance the sustainability of HRJ fuel production.