(77f) Carbon Footprint of Hydrotreated Renewable Jet Produced through Rapeseed Rotation with Wheat and Other Crops in North Dakota

Hydrotreated Renewable Jet (HRJ) fuel from oilseed plants has increasingly become important for the aviation sector to address energy security and climate change mitigation. Rapeseed is considered a promising HRJ source for its high quality oil content and the potentially attractive agro-economic benefit to replace the fallow period in wheat/fallow rotations in the Great Plains.  Previous quantitative methodologies, such as RSB and IPCC methods, can be used to estimate regional variations in N₂O and soil C emissions for rapeseed cultivation, however, they cannot capture the biogeochemical processes of the N and C dynamics in soils due to relying on simple equations. Here we use biogeochemical based WinEPIC model to simulate regional differences in N₂O emissions and soil carbon changes of rapeseed rotation with winter wheat for the rapeseed HRJ life cycle. This dynamic N₂O emissions and soil carbon changes results are incorporated into our overall rapeseed HRJ fuel LCA modeling work using the LCA software SimaPro.  In addition, inputs for multi-modal transportation logistics were obtained from the Alternative Fuel Transportation Optimization Tool (AFTOT) in collaboration with the the US Department of Transportation Volpe National Transportation Systems Center.   Different co-product allocation methods were employed in scenario analyses, such as energy allocation, market value allocation, and displacement allocation, therefore producing a robust analysis of GHG emissions and cumulative energy demand of the rapeseed HRJ life cycle with compiled life cycle inventory. Our presentation details the methods, assumptions and initial LCA results for different scenarios of importance in North Dakota, one of the 10 US states studied in this project, when considering the rapeseed HRJ life cycle.  Preliminary results indicate that soil carbon increases when rapeseed is grown in rotation with wheat and other crops and that N₂O emissions from application of synthetic N fertilizers and incorporation of crop residues are lower than predicted using the IPCC Tier 1 method.  Both of these results contributed to a favorable carbon footprint result for rapeseed HRJ, yielding greater than 50% savings of greenhouse gas emissions compared to fossil jet fuel.