(641d) Review of Bio-Jet Fuel Conversion Pathways

Bio-derived jet fuel has become a key subject in the aviation industry strategy to address the challenges from reducing operating cost, environmental performance and impacts to the global ecosystem.  For producing a long-term renewable aviation fuel, economic and environmental sustainability are necessary. Researchers from oil refining industry, commercial aviation industry, government, biofuel companies, agriculture organizations and academic systems are looking forward to developing a commercial viable process that has not only low production cost but low GHG emissions. Additionally, the fuel produced from the process has to meet the ASTM specifications and is intended to be 100% drop-in for the replacement of current petroleum jet fuel. This study reviewed the current major technologies for converting bio-based materials into renewable aviation fuels. All the conversion pathways are classified to four categories: (1) syngas-to-jet, includes Fischer-Tropsch(F-T) synthesis and gas fermentation; (2) renewable-oil-to-jet, includes hydroprocessed renewable jet (HRJ) via plant oil and algal oil, catalytic hydrothermolysis (CH) and hydrotreated depolymerized cellulosic jet (HDCJ, also named pyrolysis) via pyrolysis oil; (3) alcohol-to-jet, includes the conversion of ethanol, butanol and methanol to jet fuel from lignocellulosic biomass feedstocks; (4) sugar-to-jet, includes fermentation of sugars to hydrocarbon  or hydrocarbon precursors as well as catalytic conversion of sugars or sugar intermediate to fuels. Discussions for each pathway are primarily focused on the available feedstocks, conceptual process design, process economics, life-cycle assessments and commercial readiness, based on the literature studies. With the help of this comprehensive review on bio-derived jet fuel conversion technologies in recent literatures, it is believed that, whereas there are significant issues related to feedstock price and availability and energy consumption of the process, bio-derived jet fuels could progressively replace a great portion of conventional jet fuel required to meet the commercial and military demand.