UBC Theses and Dissertations
The potential of the aviation sector to reduce greenhouse gas emissions using biojet fuels Ringsred (Beavers), Anna
Aviation is the fastest growing industry in the transport sector and its GHG emissions are expected to increase 7-fold over the next 35 years. To achieve the industry’s goals of a 50% emission reduction by 2050, groups such as the International Civil Aviation Organisation (ICAO) have stated that biofuels will play an essential role. Although various methods of producing biojet fuel have been proposed, the specific GHG emission reductions that might be achieved have yet to be fully elucidated. This thesis explores the Lifecycle Assessment (LCA) of biojet fuel production via thermochemical and oleo-chemical means through the review of biojet LCA literature. By comparing the assumptions used within, it became apparent that the nature of the LCA model had a significant impact on the carbon intensity results. Results using the GHGenius model were found to be significantly different than results from GREET or SimaPro, likely due to the inclusion of land use change and the use of the displacement allocation method in the GHGenius model. Although these two variables influenced the results more than any other variable, the location of production also had a significant impact on the oleo-chemical and pyrolysis methods, as did the source of hydrogen. Even with these differences, all models agreed that biojet fuel produced by gasification provided the lowest greenhouse gas emissions. In the second part of this thesis, the LCA of B.C. forest biomass-to-biojet pyrolysis scenarios were modeled, assessing three possible biomass supply chains: (Vancouver Mainland (forest residue), Vancouver Island (forest residue) and Prince George (wood pellets)). The GHG emission reductions of each supply chain scenario compared to petroleum jet fuel were 71.1%, 70.6%, and 68.2%, respectively. A sensitivity analysis of the Prince George scenario indicated that the results were most sensitive to the type of feedstock used for pellet production, the allocation method used, the moisture content of the feedstock and the source of hydrogen. It was shown that, independently, these variables can change the GHG emission results by 10% - 60% or, combined, could reduce the overall GHG emissions to - 22.13 gCO₂eq/MJ biojet fuel (125% reduction).
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