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. However, concerns have been raised about the viability of this important change in land use, within which water supplies is one important concern as large scale biofuels production may place pressure on fresh water supplies and water quality. Despite these achievements on analyzing the water impact of production of selected biofuel crops, investigation of rapeseed production for biofuel has been limited. This study develops assessment informed by inputs from multiple models to evaluate the environmental impacts of water utilization and water quality of the different production options for HRJ production from rapeseed cultivation in North Dakota. The biogeochemical based EPIC model is incorporated to simulate the crop growth that influences the hydrological cycle. Output of the land-use management changes from the EPIC is used to run the blue water footprint analysis using the LCA software SimaPro 8.0. Evapotranspiration data from the EPIC model is incorporated to calculate green water footprint during cultivation. The UNESCO Grey Water Footprint Accounting Tier 1 Guideline is followed to estimate the grey water footprint caused by nutrient leaching and runoff. In addition, inputs for multi-modal transportation logistics were obtained from the Alternative Fuel Transportation Optimization Tool (AFTOT) models in collaboration with the US Department of Transportation Volpe National Transportation Systems Center. Co-product allocation methods were employed in scenario analyses, such as energy allocation and market value allocation, therefore producing a robust analysis of water footprint of the rapeseed HRJ life cycle with compiled life cycle inventory.
Our presentation details the methods, assumptions and initial water footprint 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 HRJ fuel derived from rapeseed in rotation with wheat has a much larger water footprint when comparing to the conventional jet fuel. In addition, although it is usually neglected, the indirect blue water footprint caused by the energy usage and the material inputs during HRJ production pathway is worth considering due to its important impact on the overall water footprint. Therefore, policy makers should consider highly the water factor when making decisions on transition to large share of biofuels.
